ENGINEERING RESEARCH INSTITUTE UNIVERSITY OF MICHIGAN ANN ARBOR, MICH. INFLUENCE OF HOT-WORKING CONDITIONS ON THE HIGH-TEMPERATURE PROPERTIES OF A HEAT-RESISTANT ALLOY By John -Fi Ewiing:-. J.;, E-reeman -; May 20, 1955 Project 1478-9

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TABLE OF CONTENTS Page INTRODUCTION a 0 0 0 0 0 0 0 0 0 0 O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 o 00 0 0 0 0 0 0 0 0 0 o0 4 EXPERIMENTAL PR OCEDURES,.............................. 0.. 6 Materialt...,,0......0.......0.. 0...0.....00.000000.0.00 00.0 8 Lattice Parameters,s.......................000........... 13 Microsstructural Studies00000o oo0000000000000000 0 00000000000000 13 RESULTS,,, o o o000000000 oooo oooo 000000000000o00000o0o000o00o0000000000o0 14 Isothermal Rolling 00. o0 a0 00 0 00 0 0 0 0 0 0.a 0 C 0 0 14 Rolling with Falling Temperatures0 00 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0, 0 0 0 0 0 0 0 0 00 24 Special Cyclic Conditions of Rollingo 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 27 Response to Heat Treatment0.o 0 o 0. o0 o o0. o. o 0 a ~ ~ 0 0 0 30 DISCUSSION. o o o o o o o o oo o o o o o o o o oo o o o o o o o o o o o o o o o o oo o o o o o o o 0 0 32 Control of Properties in the Hot-Worked Condition 0 0 0 0 0 0 0 0 0 0 0 0 0 0 32 Mechanisms of Strengthening and Weakening by Hot-Workingo 0 0 0 0 0 36 Reheat Effects o o 0 0 0 a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 a 0 0 0 0 0 44 Response to Heat Treatment.o 0.*. 0 0000a00000000000000000000. 44 General Observations,... 00000000000000000000000000000a000000 47 Limitations of Resultsoooo000000000000a00000000000000000000.ooo 49 CONCLUSIONS. 0o00000aa00000000000000000000000000000000000000000000 52 REFERENCES 0 0 0 0 0 0 0 0 0 0 00 0o 0o o 0 o 0 0 o 0 o o o a o o 56 TABLES000 0 o o 0 o0 o000000 o0 00 0 0 o0 o o o o o o o0 57 FIGURESo o00 o 000 0000000000000000000 00000 00000000000 00000000 73 ii

SUMMARY The relationships between conditions of hot working and properties at high temperatures and the influence of the hot working on response to heat treatment was investigated for a 20 Cr - 20 Ni - 20 Co - 3 Mo - 2 W - 1 Cb alloy. Commercially produced bar stock was solution treated at 2200'F to minimize prior history effects and then rolled at temperatures of 2200O 2100e, 2000~, 18000 and 1600~Fo Working was carried out at constant temperature and with incremental decreases in temperature simulating a falling temperature during hot working. In addition, a few special repeated cyclic conditions involving a small reduction at a high temperature followed by a small reduction at a low temperature were used to study the possibility of inducing very low strengths by the extensive precipitation accompanying such procedureso Most of the rolling was done in open passes with a few check tests with closed passes. Reductions up to 40 percent were used with some conditions carried to as high as 65-percent. Heat treatments at both 20500 and 2200'F subsequent to working were used to study the influence on response to heat treatment, The evaluation of the effects of rolling were based on rupture tests at 1200~ and 1500~F, creep rates during the rupture tests and for stresses of 25,000 psi at 1200~F and 8,000 psi at 1500~Fo Hardness, microstructures and lattice parameter measurements were used to obtain data explaining the metallurgical factors responsible for the observed effects on properties at high temperatures. The results explain many of the observed variations in properties for the hot-worked condition. Limited isothermal deformations increase strength, Larger reductions either do not increase strength or cause a decrease. Working over a falling temperature range can give very high strengths at 1200'F, equal to those usually obtained only by hot-cold work, Repeated reduction with low reheat temperatures leads to very low strengths, Hardness does not correlate

with strengths because hardness can continue to increase while strengths fall off for more than optimum reduction. Very uniform response to heat treatment was obtained suggesting that variable response when it occurs may be mainly due to unidentified heat-to-heat differences. The variations in strength in the hot-worked condition appear to be due to working having both a strengthening and weakening effect on the structure of the alloy. Strengthening apparently was mainly due to strain hardening. Recrystallization when it occurred was a weakened effect. It suggests that weakening in the absence of recrystallization is due either to the same structural changes from rolling which induce recrystallization at the higher temperatures or to a recovery process similar to recrystallization, possibly the formation of substructures in the grains. Working over a falling temperature range allows more strengthening of the type effective at 1200'F for a given reduction. Considerable precipitation occurs during working from 1600~ to 2000~F, particularly at 18000F. This appears to be detrimentaltolong time strength at 12000F but to have little effect at I5000F due to extensive precipitation during testing at 1500~F, Temperature of working has a substantial effect on properties at 12000F apparently due to the effects of the precipitation reaction. It also seemed to have considerable influence on ductility in the rupture test at 1500~F. There were a number of striking relations between conditions of working and properties at high temperatures. For working at constant temperature, maximum strengths at 12000F were obtained for 15-percent reduction. This was probably true for temperatures from room temperature to 21000F. In addition, if it were not for the influence of the high temperature precipitation reaction, the strengths would apparently be nearly constant. Constant maximum rupture strengths were obtained at 15000F for isothermal working from 16000 to 22000F but the optimum reductions were not constant.

Lattice parameters varied markedly with conditions of working and with cooling rate for reasons which are not understood. Grain size in itself did not appear to be a controlling factor. Due to the limitations of experimental conditions there are a number of limitations to the generality of the results.

4 INTRODUCTION The investigation covered by this report studied by controlled experiments the principles governing the influence of hot-working conditions on the hightemperature properties of one type heat-resistant alloy in the hot-worked condition and the influence of such hot-working conditions on response to subsequent final heat treatments. The study applies mainly to those complex austenitic heat-resistant alloys dependent on solution treatment or hot-cold work for properties at high temperatures, and not on strong age-hardening reactions. The particular alloy used was nominally 0, 15 C - 20 Cr - 20 Ni - 20 Co - 3 Mo - 2 W - 1 Cb - balance Fe. Working was carried out at several constant temperatures to define the influence of amount of reduction at a given temperature. Specific reductions at specific temperatures over a range of decreasing temperatures were used to study the influence of working over the usual falling temperature range. Additional limited studies were made to establish the effects of possible heating and working schedules involving reheats to temperatures below and in the resolution range with reductions at low temperatures where extensive precipitation occurs. In addition to investigating the properties in the hot-worked condition, samples were given typical final solution, solution and aging, and solution and hot-cold working treatments to study the effects of prior working on response to heat treatment. At least two general factors influence the properties of individual alloys of the type investigated at high temperatures. Fi-rst, various final treatments may be used to obtain specific properties. These can range in wrought products from the hot-worked condition with no subsequent treatment through so-called stress relieving solution treatments at various temperatures with or without subsequent aging treatments, and, for the type of alloy considered, possibly cold work or hot-cold working operations after the other treatments.

5 The other general factor leading to variability in properties arises from the variation in properties with specific final treatments. Recognized possible sources of the latter type of variation include the influence of conditions of hot working on the response to final treatments, variations in chemical composition, and unidentified heat-to-heat differences. Properties in the hot-worked condition are considered to be difficult to control. Practical limitations in the reproducibility of conditions of working as well as lack of information regarding the influence of the conditions of working are involved. It is known that both very high or very low strengths are observed in hot-worked products not subjected to further treatment as well as intermediate values of strength. No completely reliable means of predicting the level of properties was available. Certainly microstructure or hardness and other normal short time mechanical property tests do not reliably predict creep and rupture values. No information was available regarding the influence of amount and temperature of reduction on properties. Likewise, there was no good information on the degree of influence of the hot-working conditions on response to the usual final treatments as reflected in the property ranges for a specific final treatment. Extensive previous studies had been carried out for the NACA. on the same alloy as that used for the present investigation to establish the influence of various types of treatment on the properties at high temperatures. The primary objective of these studies had been to determine the basic fundamental causes for variation in properties at high temperatures. It had been found that the creep and rupture strengths were primarily a function of the degree of solution of odd sized alloying atoms in solid solution and the degree of strain hardening present from working the metal, So far as could be ascertained, precipitation only reduced creep strength as measured by secondary creep rates by removal of odd sized atoms from solution. Increases in rupture strength from

6 precipitation appeared to be due mainly to increased deformation before fracture occurred and some reduction in creep rates during primary creep. These latter effect only increased rupture strength at relatively short times for rupture (high stress levels) where their influence predominated over lowered secondary creep resistance. Strain hardening increased creep and rupture strengths up to the point where recovery effects occurred during testing due to excessive cold work for stability. A major objective of the present investigation was to explain observed variation in properties at high temperatures due to working conditions at high temperatures in terms of fundamental concepts. Detailed microstructural studies were carried out to define the structural effects of hot-working. Hardness was used to measure strain hardening effects. X-ray deffraction studies were instituted with the expectation of being able to study the degree of solution of odd sized atoms from the alloying elements. The research was conducted by the Engineering Research Institute of the University of Michigan under the sponsorship and with the financial assistance of the National Advisory Committee for Aeronautics as part of an investigation of the fundamental metallurgy of heat-resistant alloys of the types used in propulsion systems for aircraft. EXPERIMENTAL PROCEDURES Although there are numerous methods for hot-working metals and alloys, such as rolling, forging, extruding, and pressing, this investigation was limited to rolling. By rolling it was relatively easy to control working variables such as temperature and amount of deformation with reproducible rates of deformation, Bar stock was selected as the experimental material as the best compromise between convenience for manipulation and minimizing temperature variation during working. This investigation was restricted to

7 two of the most important variables, rolling temperature and amount of reduction. The rate of compression during rolling was kept as nearly constant as possible by keeping the roll speed, roll diameter and initial cross-sectional area of the stock constant. In this report the term "hot working" refers to all working carried out in the temperature range usually associated with the hot working of complex, heat-resistant alloys, irrespective of whether or not recrystallization occurs. Technically, the term hot working should refer only to working at or above the simultaneous recrystallizatioxl temperatures. In commercial practice hot working is carried out over a falling temperature range. Although the starting temperature may be well above the minimum temperature required for recrystallization, the finishing temperatures can be so low that no recrystallization takes place during the latter stages of working. In such cases, despite some recovery or stress relief, the metal is partially strain hardened or cold worked. The research program was organized as follows: 1. Stock was isothermally rolled varying amounts at temperatures ranging above and below the minimum temperature of recrystallization during rolling. 2. Stock was non-isothermally rolled over controlled temperature ranges to provide a basis for determining how the usual decreasing temperatures during hot working influenced the high-temperature strengths. 3. Stock was cyclicly rolled over three temperature ranges to determine the influence of extensive precipitation during rolling on the properties at elevated temperatures. 4, Heat treatment was carried out after selected conditions of rolling to determine if the influence of hot working was reflected in the response to heat treatment.

8 5. Rupture and creep tests, hardness measurements, microstructural examinations, and lattice parameter measurements were made after the various hot working operations to obtain information for studying the mechanism by which hot working affects high-temperature properties. Material The material used in this investigation was 7/8-inch bar stock from a commercial heat of alloy having the following chemical analysis: Chemical Composition (percent) C Mn Si Cr Ni Co Mo W Cb N 0.13 1, 63 0. 42 21. 22 19.00 19. 70 2. 90 2, 61 0. 84 0. 13 The bar stock was produced from a 13-inch billet, The commercial processing details are given in table Io. The same lot of bar stock had been utilized in other fundamental studies on the same type of heat-resistant alloys at the University of Michigan (1)(2)(3). The data from these prior studies, concerned with the influence of heat treatment and cold working on high temperature strength, would simplify arriving at general principles, All stock was solution treated for one hour at 22000F and then water quenched before rolling to minimize the effects of the prior working. R ollinag Figure 1 summarizes the conditions of hot rolling carried out, Most of the specimens were rolled in open passes on a two high, single-pass, nonreversible mill with five-inch rolls. The rolls were power driven and revolved at a speed of 70 RPM, No lubricant was used on the rolling surface. For rolling temperatures of 1800~F and above, an automatically controlled, gas-fired furnace holding temperatures to + 5~F was used, An automatically controlled electric muffle furnace was used for temperatures below 18000F,

Cooling curves from the various rolling temperatures showed the maximum temperature drop during rolling to be 50~F. Consequently, the stock was heated to 250F above the rolling temperature. A holding time of one-half hour before rolling established thermal equilibrium between the furnace and bars. The initial bar lengths were chosen to give a final length after rolling of 12 inches. All reductions were based on the original cross-sectional area. The rolling procedure for making reductions up to 15 percent at 1600~F, and up to 25 percent from 1800~ to 2200~F, was to pass the bar through the rolls twice for a given roll setting, turning the bar 90 degrees between passes. Reductions of 25 percent at 1600~F, and 40 percent at 18000F and above, could not be made in a single roll setting because of the limitations of the rolling mill. Consequently, for these reductions the stock was first rolled 10 percent at 1600~F or 15 percent at 18000F and above, reheated for five minutes, and then reduced an additional 15 percent at 16000F or 25 percent at 18000F and above. A 40-percent reduction at 1600'F required successive reductions of 10, 15, and 15 percent respectively, with two five-minute reheats. A reduction of 65 percent required successive reductions of 15, 15, 15, 10, and 10 percent, with four reheats. All bars were air cooled after the final reductions. Rolling over a temperature range involved the following procedure. In order to roll first at 22000F and then finish at 2000~F, the bars were rolled initially 15 percent at 22000F, replaced in the furnace and the furnace cooled to 2025~F in 6 minutes, and then reduced an additional 25 percent. Two furnaces were used to roll bars first at 2200~, 2000~, or 1800'F, followed by a second reduction at 1800~ or 1600~F, The bars for these series were first heated to the initial rolling temperature in the established manner, rolled, and then immediately placed in the second furnace which was maintained at the desired lower rolling temperature, cooled to that temperature in the furnace, and given the second reduction. One series of bars was rolled 10 percent each

10 at 2200~, 2000~, 1800~, and 1600~F, giving a total reduction of 40 percent. For this weries the gas-fired furnace was used to cool between 22000 and 2000'F and the electric furnace used for temperatures of 1800~ and 1600~F. In these experiments involving one or more reductions at successively lower temperatures, a dummy bar with a thermo-couple inserted into the center along the longitudinal axis was used to determine when the stock was at the proper rolling temperature. Measurements with the dummy bar indicated a period of 6 minutes was sufficient to reach the desired temperature for all temperature intervals. An unusual and complex series of reductions was carried out to check the effect of precipitation during rolling on the high-temperature strength of this alloy. One group of bars in this series was rolled as follows: heated to 1800~F, held 1/2 hour, rolled 5 percent, cooled tp 1500~F, rolled 5 percent, held 2 hours, and then reheated to 1800~F, with the cycle repeated three more times giving a total of 40-percent reduction. The two other groups of bars in this series were rolled in the same way except the rolling temperatures were 2000~ and 1500~F and 2200~ and 1500~F, respectively. In order to check the uniformity of working over the cross-sectional area, hardness surveys were made across the transverse sections of selected bars rolled between 5 and 25 percent. Vickers hardness tests (50 kg load) were used for these surveys. Likewise, six bars from each of three rolling conditions were checked for hardness to see if there were any pronounced variation in the hardness of similarly rolled bars. No variations were found in either case. In the open-pass rolling the roll speed, roll surface,and initial size of the stock were kept the same throughout the investigation. This was done in order to keep variations in the compression rate nearly the same. However, by varying the amount of reduction, the compression rate during rolling was

11 also varied. Although variations in compression rate have little effect on strain hardening during cold working, they do have an effect durring hot rolling. A small amount of closed-pass rolling was done to study the relative influence of a change in the mode of deformation during rolling. That is, rolling in closed passes eliminated the lateral spread which ocurred during open-pass rolling. The closed-pass work was done on a large reversing mill recently installed at the University of Michigan and equipped with rolls 9-1/2 inches in diameter and 27 inches longo The roll speed used was 30 RPM. Reductions of 15 and 25 percent at 18000 and 2000'F, and 65 percent at 1800'F were made in closed passes. The rolling procedure was the same as described above for openpass rolling with the exception that the stock was passed through the rolls only once for the 15 or 25 percent reductions, The 65-percent reduction at 1800~F was made using a series of 7/8, 3/4, 5/8, and 1/2-inch square passes. These square passes were separated from one another by oval passes, Six reheats were required. Prior to rolling 15 or 25 percent in a closed pass, the bars were shaped to an initial size such that after going through the 3/4-inch pass, the desired reduction was obtained, The actual reductions after rolling for both open and closed passes in no instance differed by more than 2 percent from the desired reductions. Creep and Rupture Tests Both rupture and creep tests were used to evaluate the experimental variables. Testing temperatures of 12000 and 1500'F were used to cover the temperature range in which the type of alloy is widely used. The effect of all rolling conditions on rupture and creep strength in the hot-worked condition was determined. Selected conditions of rolling were subjected to subsequent heat treatment in order to evaluate influences of hot

12 working conditions on response to heat treatment. Stress-rupture tests were of sufficient duration to establish the rupture strengths for 100 and 1000 hours. The creep tests of 1000 hours duration were conducted at 12000F under 25, 000 psi and under 8, 000 psi at 1500~Fo Creep data were also established for the rupture tests. Minimum creep rates were used to evaluate the effects of variables on creep resistance. Conventional beam loaded units were used for both creep and rupture tests. The test specimens machined from the bar stock were 0O 250-inch in diameter with a 1-inch gage length. Accurate measurements were made on all specimens prior to testing. Time-elongation data were taken during the rupture tests by a method in which movement of the beam was related to the extension of the specimen. Modified Martens-type extensometers with a sensitivity of + 0. 00002inch were used to obtain time-elongation data for the creep tests. Reynolds, et al, (4) found there was good agreement between creep rates from the two types of deformation measurements. The creep and rupture units were equipped with automatically controlled electric resistance furnaces, Temperature variations along the gage length of the specimens were held to less than 30F, The loading practice followed was to bring both specimen and furnace up to within 100~F of the testing temperature overnight. In the morning the unit was brought on temperature and then loaded, Several check creep tests were run during this investigation, as noted in the tabulation of the experimental data, and the corresponding creep rates checked within + 0. 00003 percent per hour. Hardness Hardness was intended to measure strain hardening during hot working. It is recognized that certain variations in hardness resulted from precipitation. However, for any given rolling temperature the change in hard

13 ness with amount of reduction was primarily a function of the strain hardening, Hardness measurements were made at the center of transverse sections cut from all specimens after rolling, A Brinell hardness machine using a 10 mm ball and a 3,000 kg load was used. Lattice Parameters The intent was to use lattice parameter variations as a measure of the extent to which odd sized elements remained in solution after rolling. A minimum of 0O 03-inch was removed from the surface of samples in an electrolytic polisher in order to insure a surface free of preparation strains0 An electrolyte consisting of one-third concentrated HC1 and two-thirds glycerine was used. The parameter measurements were made using a high precision symetrical focusing camera0 Cohen's method (5) was used to compensate for uniform shrinkage of film and camera radii errors. Several check tests were run and the reproducibility was determined to be within 0. 0005A. For the most part, the measurements were made on surfaces transverse to the rolling direction0 However, several measurements were also made on surfaces either parallel to or at 450 to the rolling direction to check for possible orientation effects. Microstructural Studies Sections parallel to the rolling axis were cut from all bars after rolling and prepared for metallographic examination. All specimens were electrolytically etched in 10 percent chromic acid solution. Besides examining the structures of the variously rolled bars, extensive studies were made on completed creep specimens.

14 RESULTS The results of the experimental studies are presented separately for IsothermalRolling, Rolling with Falling Temperatures, Special Cyclic Conditions of Rolling, and Response to Heat Treatment. In each case, the influence of conditions of rolling was evaluated through determination of rupture and creep properties at 1200~ and 1500~F, hardness values, microstructures, and lattice parameters. All testing was carried out on hot worked material except for that involving the influence of working conditions on response to heat treatment. Attention is directed to the fact that in each case the hot working was carried out starting with 7/8-inch square bar stock that had been heated 1 hour at 22000F and water quenched. The stock had been commercially produced from a large arc furnace ingot, Isothermal R oiling The data reported in this section are for the as-rolled condition when rolled at constant temperature. Tables II through V and figures 2 through 19 present the rupture and creep data. Hardness data are included as table VI and figure 20. Typical microstructures are shown by figures 21 through 27. Lattice parameter data are in table VII and are illustrated by figures 28 through 32. Rupture Properties at 12000F. - The influence of amount of reduction and temperature of rolling on the rupture properties at 1200'F were as follow s: 1. A reduction of approximately 15 percent resulted in maximum rupture strength for both 100 and 1000 hours for rolling temperatures of 16000 to 2100~F (see figures Za through 6a). Reductions between 0 and 40 percent at 2200OF had no significant influence on the rupture strengths.

15 20 The influence of temperature of reduction on rupture strengths is summarized by figure 7a, The maximum strengths at 15-percent reduction increased as the rolling temperature was reduced from 22000 to 2000OF. Lowering the rolling temperature to 1800~ and 1600~F increased the strength for 100 hours slightly more; but resulted in a decrease in 1000-hour strength. The loss in strength by larger reductions was nearly constant at each temperature so that the curves for 40-percent reduction (fig. 7a) was nearly parallel to the 15-percent reduction curve. The only exception was for 1000 hours at 1600~F where strength continued to increase slightly. 3. Simply reheating to the rolling temperatures had little effect on rupture strength, except for a significant lowering of strength for 2100~F as is shown by the 0-percent reduction curve of figure 7a. Rolling increased rupture strength above that resulting from simply reheating to the rolling temperature in all cases, except for 2200~F. Certainly reductions larger than 65 percent would be required to reduce strength below that for material simply heated for -1/2 hour at the other rolling temperatures. 4, The maximum rupture strengths were from 7000 to 10, 000 psi higher than when reheated without reduction at 2100' to 1600~F. The range in 100-hour strengths was from 42,000 to 57,000 psi, with oneilower value of 38,500 psi resulting from reheating at 2100'F without reduction, The corresponding range for 1000-hour strengths was 37,000 to 47, 000 psi, again with a low value of 33, 000 psi for reheating to 2100Fo, 5. No significant difference in rupture strength between material rolled in open and closed passes was found for a limited number of samples rolled at 18000 and 2000~F. {See table V and figures 4a and 5a). 60 Increasing reductions at 2200~ and 2100~F increased elongations for fracture in 100 and 1000 hours from as ow as 5 percent to as high as 18 percent (figs. 9 and 10). Rolling to increased reductions at 20000 and

16 1800~F first lowered and then increased elongations (figs. 11 and 12)o The increase at larger reductions was not observed in stock rolled at 1600~F (fig. 13.). It should be noted that simply reheating to these latter three temperatures increased elongations relative to the stock originally solution treated at 2200'F. Minimum elongations in 100 and 1000 hours were both in the order of 5 percent for all conditions of rolling. The rupture-test elongations for material rolled in closed passes at 1800~ and 2000~F agreed perfectly with those for open passes, except for higher elongation after a 25-percent reduction at 2000'F for the closed pass material, (Compare tables III and V.) Creep Properties at 1200Fo, - The relations between minimum creep rate at 12000F for stresses of 50, 000 and 25,000 psi and percent reduction at the rolling temperatures, as presented in table III and figures 15 and 16 show that: 1. Increasing amounts of reduction first increased creep resistance (reduced minimum creep rates) to a maximum for a limited amount of reduction. Creep resistance then fell. off for larger reductionso 2, The amount of reduction giving maximum creep resistance (fig. 19a) varied with both the rolling temperature and the testing stress. For a stress of 50,000 psi this reduction was 15 percent, except for 2200~ and 1800~F. For the lower stress of 25,000 psi, the reduction ranged from 5 to 15 percent with the largest reduction being required at 2000~ and 2100~Fo The influence on creep resistance under 50,000 psi was similar to the rupture strengths, except for the high reduction at 1800~0F0 Except for rolling at 2000~ to 2200 F, less reduction was required for maximum creep resistance under 25, 000 psi, 3. Rolling at 16000. 1800~ and 2000~F gave similar and definitely higher creep resistance for 25,000O psi (fig. 16) than did rolling at 2100~ and 2200~F. Creep resistance, however, fell off considerably with increased

17 reductions past those giving maximum resistance for all temperatures of rolling. At the higher stress of 50,000 psi (fig. 15), the decrease in creep resistance past the maximum was much less after rolling at the three lower temperatures than for 2100~ and 2200 F. The material rolled at 2000 F, however, was considerably weaker than those rolled at 16000 and 1800~F. 4. The creep resistance after rolling in closed passes (tables III and V), with the exception of the somewhat low strength of the stock rolled 65 percent at 1800~F, agreed well with the creep resistance of bars rolled corresponding amounts in open passes. 5. The creep resistance of stock reheated from 1600~ to 2100~F for 1/2 hour without rolling (figs. 15 and 16) was lower for both 50,000 and 25, 000 psi than the creep resistance of the material reheated to 22000F for 1/2 hour, Reheating to 18000F lowered creep resistance the most. 6. Isothermal reductions from 5 to 25 percent at 18000 and 1600~F, and from 5 to 15 percent at 2000'F eliminated first stage creep during the 1000hour creep tests using 25, 000 psi. Larger reductions resulted in the reappearance of the first stage component. Creep tests on all the specimens rolled at 2100~F had a first stage component. There was no first stage component during the 1000-hour creep tests involving specimens previously reduced 0 to 15 percent at 2200~F. However, reductions in excess of 15 percent at 2200~F did result in a first stage creep component. Rupture Properties at 1500~F. - The major features of the data can be summarized as follows: 1. A specific reduction gave the highest rupture strength at 1500~F for each rolling temperature (figs. 2b through 6b). These reductions were the same for both 100 and 1000 hours (fig. 9) and continually increased as the rolling temperature was lowered from 2200~ to 1600~F. There was no appreciable difference in the maximum strength (fig. 7b) with rolling temperature at either 100

18 or 1000 hourso 2. Although there were no variations with rolling temperature in the maximum rupture strengths, there were pronounced differences at each temperature between the maximum strength and the strengths produced by both larger and smaller reductions (see fig. 7b). The largest variation in strength for open pass rolling resulted from rolling at 1800'F where the maximum and minimum 100hour strengths were 21,500 and 14,C00 psi, respectively. Corresponding values for 1000 hours were 16,000 and 7,500 psi. The lowest values obtained were for a closed pass reduction of 65-percent at 1800'F which yielded values of 10, 500 and 5,700 psi, respectively, for 100 and 1000 hourso 3. Many conditions of working resulted in lower strength than heating to the working temperature without reduction (fig. 7b) or solution treatment at 2200~F. This is in contrast to 12000F where improved strength resulted for all reductions considered. 4. Reheating to the roiling temperature without reduction had little effect on strength at 1500~F, as is shown by the curves for O-percent reduction in figure 7b. An exception was the low 1000-hour strength after heating at 18000F. 5. The rupture strength. after rolling in closed passes (table V and figs. 4b and 5b) agreed well with those for open passes for reductions of 15 and 25 percent at 18000F and 15 percent at 2000Fo. A reduction of 25 percent in closed passes at 20000F gave somewhat higher and 65 percent at 1800'F gave somewhat lower strengths than for the corresponding reductions in open passes. 60 Conditions of rolling had very pronounced effects on elongation in the rupture tests at 1500~F (figs, 9 through 13)o The elongations at 100 hours varied between 4 and 60 percent and at 1000 hours from 5 to 41 percent. The relations involved were: (a) The elongation decreased with increasing amounts of reduction to minimum values and then tended to increase with further reduction.

19 (b) The differences in elongation between reheating with no reduction and the reduction giving minimum elongation (fig. 14) became very large at temperatures below 2200~F. Pronounced increases in elongation resulting from simply reheating the stock originally solution treated at 2200'F were removed by subsequent working. The effect was much greater at 100 hours than at 1000 hours. For instance, reheating to 1800~F resulted in an elongation at 100 hours of 57 percent whereas the same material reduced 40 percent at 18000F had an elongation of only 4 percent. At 1000 hours the corresponding values were 25 and 5 percent. (c) Reductions for minimum elongation at each rolling temperature (fig. 14) ranged from 15 to 40 percent at 100 hours and were 15 percent at all temperatures for 1000 hours. Actually rather low values were associated with reductions of 15 to 40 percent at all rolling temperatures. (d) There are reductions at all temperatures which give rather low elongations and less or more reduction resulted in increased elongation. Reference to figures 9 through 13 shows that high elongation is particularly associated with large reductions at 2100 and 2200~F. The increase with large reductions was much less at the lower temperatures. (e) The limited data for closed pass rolling (table V) indicate the same general influence of hot working on elongation in the rupture tests. The differences resulting from open and closed pass rolling were no greater than the degree of scatter which might be expected where ductility varies so rapidly with conditions. Creep Properties at 15000Fo - The variations in creep data can be summarized as follows: 1. There was an optimum reduction (figs0 17 and 18) at each rolling temperature resulting in the highest creep resistance at 1500~F. This optimum reduction increased slightly as the rolling temperature was lowered (fig. 19b),

20 and was generally somewhat less for the tests at 8, 000 psi than for those at 15,000 psi. 2. The loss in creep resistance for reductions greater than those producing the maximum was generally quite rapid, particularly at 8,000 psi. The larger reductions generally resulted in considerably lower creep resistance than material simply reheated without reduction, There was some indication that for very large reductions the creep resistance was not lowered as much. 3. The creep resistance of stock rolled 15 and 25 percent at 1800~ or 2000'F in closed passes (table V) agreed well with the creep resistance of the bars rolled corresponding amounts in open passes. However, the creep resistance of 8, 000 psi of stock rolled 65 percent at 1800'F in closed passes was low. 4. The minimum creep rates for an initial stress of 15,000 psi ranged from 0. 002 to 0. 13 percent per hour as the result of varying the rolling temperatures from 22000 to 1600~F, and the percent reduction from 0 to 65 percent. Over the same ranges of rolling temperatures and reductions the minimum creep rates for an initial stress of 8,000 psi varied from 0. 00003 to 0. 024 percent per hour. 5, The creep resistance at 1500~F of the stock reheated at 1600' to 2100'F for 1/2 hour without rolling was lower for both 15,000 and 8,000 psi than that of the bar stock reheated to 2200~F for 1/2 hours. Reheating,as well as reduction, affected the creep resistance with the maximum effect at 1800'F. 6. Reductions from 0 to 40 percent at 18000 and 1600'F slightly decreased the first-stage component of creep in the 1000-hour creep tests under a stress of 8,000 psi in comparison to the original stock. The reduction of 65 percent at 18000F resulted in both a substantial increase in the first-stage component and the appearance of a third-stage component. Reductions at 22000 to

21 2000~F did not decrease first-stage creep. Hardness - Brinell hardness measurements were made after all conditions of rolling and are tabulated in table VI. Figure 20 presents the relationship between Brinell hardness and amount of isothermal reduction in open passes at rolling temperatures ranging between 1600~ and 2200~Fo The essential features of the hardness data can be summarized as follows: 1. Hardness increased with percent reduction at all temperatures. However, there was a rapid drop in hardness when the reduction reached 7 percent at 2200~ and 10 percent at 2100~F. Little further increase was obtained for more than 15-percent reduction at 2000'Fo All reductions at 1800~ and 1600~F increased hardness, the amount of increase decreasing with increased reduction, When reduced at 22000 and 2100~, minimum hardness was obtained for reductions of 12-15 percent followed by a slight increase and again a decrease for more reduction. 2. The Brinell hardness of the bars rolled 15 or 25 percent in closed passes at either 20000 or 1800~F agreed well with the corresponding bars rolled in open passes. The hardness of the bar rolled 65 percent in closed passes at 1800~F was substantially lower than that of the corresponding bar rolled in open passes. 3. The overall levels of the various hardness curves in figure 20 were influenced by the heating temperature alone, as evidenced by the increases in the hardness of stock simply reheated to the rolling temperatures and cooled without rolling. Influence of Rolling Conditions on Microstructures. - Typical microstructures of the bars given various reductions at 22000, 2000~, 1800~ and 1600~F are shown in figures 21 through 24, respectively. The changes in microstructure during rolling can be summarized as follows: 1 Recrystallization occurred during rolling at 22000, 21000 and

22 2000~F depending on the amount of reduction. Recrystallization was not observed during open pass rolling at 18000 or 1600~F. It did occur during the 65-percent reduction in closed passes at 1800~F. 2. The observed conditions of recrystallization were as follows: 2200~F - started at 5 to 7-percent reduction - essentially complete at 15-percent reduction -continued refinement of grain size with further reduction. 2100~F - started at 10-percent reduction - essentially complete at 15-percent - continued refinement with further reduction. 2000~F - started at 15-percent reduction - required a reduction of 65 percent for complete recrystallization. It will be noted that the discontinuities in the hardness curves of figure 20 correspond with the observed recrystallization characteristics. 3. A finely dispersed precipitate formed in the matrix when the alloy was previously solution treated at 22000F and then reheated to 18000 or 2000'F for 1/2 hour. Increasing the amount of reduction of these temperatures appeared to increase the amount of precipitation in the matrix. Previous to this investigation it was not known that this alloy was subject to precipitation in the matrix between 1800~ and 2000~F. Even rolling at 22000F appeared to cause a dispersed precipitate to form in grain boundaries. 4. A. matrix precipitate did not form in the bar stock during the 1/2 hour reheat at 1600'F although grain-boundary precipitate did form. Moreover, there was no visible evidence of any general precipitation in the matrix during rolling at 1600~Fo *Microstrucres after Creep Testing. - Metallographic examination was made of the creep specimens after testing for 1000 hours in order to obtain information on the structural stability of the as-rolled condition during testing

23 at 1200~ and 1500~F. Figures 25 and 26 show microstructures of bar stock rolled at 16000 and 2200 F, respectively, and tested at 1200~F, Figure 27 shows typical structures after testing at 1500~Fo The structural changes during creep testing are summarized as follows: 1. Structural changes during testing at 1200oF were largely dependent on the initial as-rolled condition of the bar stock. Extensive precipitation took place in the matrix during testing provided precipitation had occurred during rolling. The precipitation was much less after rolling at 2200~ or 2100~F where little precipitation occurred during rollingo Rolling at 1600~F, however,apparently resulted in nucleation of precipitates during testing inasmuch as extensive precipitation occurred even only grain boundary precipitation was evident after rolling. The structure after testing of the material rolled at 1800~ and 2000~F was similar to that rolled at 1600~Fo In cases where matrix precipitation did occur during testing at 1200~F, it appeared to increase with increasing amounts of rolling. 2. The structural changes which occurred during creep testing at 15000F appeared to be largely independent of the initial conditions of the microstructure. That is, precipitation and/or agglomeration occurred in all bars during testing and all structures were remarkably similar after testing. Lattice Parameter Measurements.- Lattice parameter measurements are tabulated in table VII, Although measurements were possible over the complete range of reductions at temperatures of 2000'F and above, determinations could be made for only the 0, 5, 10, and 50 percent reductions at 1800~F. The diffraction lines were too diffuse for all other reductions at 1800'F and for all reductions at 16000F. Check measurements, whenever made, are also given in table VIIL Most determinations were carried out on surfaces transverse to the direction of rolling with some check measurements at other angles to the rolling direction. The influence of amount and temperature of reduction on lattice

24 parameters (figs. 28, 29 and 30) was fairly complex. Successive minimum and maximum values appeared as the amount of reduction was increased. The amount of reduction required to produce these effects increased as the rolling temperature was reduced. A measurement made on stock reduced 35 percent at 2000'F without reheating plotted on the curve (fig. 28) intermediate between the values for reductions of 25 and 40 percent. This indicated that the reheating for the 40-percent reduction was not the cause of the rapid increase in parameter when the reduction was increased from 25 to 40 percent. This conclusion is further substantiated by a similar behavior at 21000F and 2200'F within the reduction range where reheats were not used. The agreement between measurements made transverse to the rolling with the check determinations at other angles (fig. 28) indicates that any orientation effects were small. During the course of the investigation it was established that cooling rate had a pronounced effect (figs. 31 and 32) on the measured lattice parameter. Air cooling resulted in larger parameters than water quenching. Limited data for a range of cooling rates from 20250F show that intermediate cooling rates resulted in larger parameters. That is, air cooling resulted in larger values than either very slow or very rapid cooling (fig. 32). Temperatures used for these studies were the same as those for heating for rolling, 25~F above the nominal rolling temperature. The use of the cooling rate at 12000F for preparing figure 32 was simply a matter of convenience for measurements of the rates. This defined cooling rate effects somewhat better than a description of the method of cooling alone. Rolling with Falling Temperatures Specimens were prepared by non-isothermal rolling over controlled temperature ranges to obtain data to investigate how the usual decreasing

25 temperatures during hot working influenced high-temperature strengths. Experiments were confined to combinations of reductions totaling 40 percent0 The initial rolling temperatures varied from 1800~ to 22000F. Rupture Properties at 1200Fo. - Rolling first at 2200~ or 2000~F and then at 2000~, 1800~ or 1600~F for a total reduction of 40 percent (tables VIII and IX) had the following effects: 1o Very high strengths resulted from reduction at 22000 or 2000~ and then at 1800~ or 1600~Fo The strengths were considerably higher (fig. 33a) than those obtained by isothermal reductions of either 15 or 40 percent at 1600~ or 1800~F, 2. A reduction of 25 percent at 22000 followed by 15 percent at 2000"F resulted in lower strength than either 15 or 40 percent isothermally at 2000~F (fig. 33a). 3. Elongations (table IX) were as high or higher than comparative isothermally rolled materials. A reduction of 10 percent at all four temperatures gave both high strength and very high elongation Creep Properties at 12000F. - The creep data (table IX) were similar to the rupture data in that finishing at 1600~ or 1800~F gave high creep resistance while 20000F gave comparatively low resistance (see fig. 34). The advantage of rolling first at 2200~ or 2000~ and finally at 16000 or 1800~F over isothermally rolled bars was not outstanding as it was in the rupture tests. Rupture Properties at 15000F. - Rupture strengths (table IX) increased with finishing temperature as is shown by figure 33b. The strengths were in general higher than those resulting from reductions of 40 percent at constant temperature. They were, however, well below the maximum strengths associated with smaller isothermal reductions. The strengths were also less than those for isothermal reductions of 15 percent where these were less than the maximum values.

26 The rolling over a falling temperature, therefore, avoided part of the loss in strength associated with large reductions in constant temperature rolling. The conditions used did not, however, produce higher strengths than for specific constant temperature reductions at 1600~ or 1800~F, as was observed at 1200~F. The relatively high strengths for reductions of 10 percent at each temperature of rolling suggests that a schedule of small reductions as temperature decreases migh be beneficial to strength. Rolling over a falling temperature did not markedly improve elongation in the rupture tests over that of isothermally rolled stock (tables III and IX) except for the schedule of 10-percent reduction at each temperature. The material finished at 20000F may have been improved also. In all other cases, the elongations were similar to those of comparative isothermally rolled stock. Creep Properties at 1500~Fo- The creep resistance (table IX) increased as the finishing temperature was lowered (fig.,. 35) The values mostly ranged between those for isothermal rolling to reductions of 15 and 40 percent. Certain sequences gave strengths similar to the most creep resistant isothermal conditions while those rolled 25 percent at 2200'F followed by 15 percent more at the lower temperatures tended to be similar to material isothermally rolled 40 percent. Hardness. - All of the conditions of rolling except one developed high as-rolled hardness values in the range of 272 to 283 Brinell(table VI). The one exception was the material rolled between 2200~ and 2000~F which had a hardness of 220 BHN. Except for this latter condition the hardness values approached those obtained by isothermal reductions of 40 percent at the finishing temperature, rather than those obtained isothermally with the actual final reductions. Microstructures.- Examination of the structures after rolling (fig. 36) and after subsequent creep testing (fig. 37) gave the following results:

27 1. Rolling at 2200~F before rolling at lower temperatures reduced grain size by recrystallization. For this reason the grain sizes subsequently rolled at 16000 and 1800'F were finer than those of the material isothermally rolled at these temperatures. ( Compare fig. 36 to figs. 21 and 22). The material rolled first at 22000 and then at 2000CF was very fine grained indicating that recrystallization continued at the lower temperature. Rolling first at 2000~F and then at 1600'F resulted in a duplexed grain structure because recrystallization was incomplete during the reduction at 2000~F. 2. Samples rolled initially at 2200'F and then at lower temperatures did not have the general matrix precipitation observed in samples isothermally rolled at 1800~ and 2000~Fo The precipitate was, however, present in material rolled initially at 1800 ~ or 2000 F and finally at 1600 F,. 3. After creep testing at 1200~F (fig, 37) the structures showed little precipitation during testing for material initially rolled at 22000 and finished at 1600~ or 1800~F. All other conditions underwent considerable precipitation at 1200'F. Structures of all samples tested at 1500'F showed the same extensive precipitation and agglomeration described for the isothermally rolled stock, The only difference noted was the changes in grain size. Special Cyclic Conditions of Rolling Samples were prepared by cyclic reductions of 5 percent at 15000F and at three higher temperatures of 18000, 2000~ and 2200~F. Repeated reductions at the upper and lower temperature were used until a total reduction of 40 percent was obtained, These conditions were investigated to study the possibility of producing abnormally low as-rolled strength by using conditions leading to extensive precipitation and agglomeration of precipitates. This condition was approximated with a top temperature of 1800~Fo Top temperatures of 2000~ and 2200~F were selected as being in and above the solution temperature range for the alloy. Owe

28 of the main reasons for this worlk was the absence of abnormal.ly low strengths for the isothermally and non-isothermally rolled materials. Such low strengths are sometimes observed in practice and the possibility of extensive precipitation by use of low working temperatures was explored as a possible explanation. Rupture and Creep Properties at 1200Fo. - Cyclic rolling between 15000 and 1800"F resulted in lower rupture strength and higher elongation than when upper temperatures of 2000~ or 2200~F were used. (See table X and XI and fig. 38a). The material rolled between 15000 and 18000F had strengths similar to those for the material simply reheated to 18000F without reduction and considerably below any of those rolled isothermally or with falling temperatures. (Compare data in table XI with tables II. and V). On the other hand, rolling 5 percent first at 15000 and then at 2000~ and 22000F produced much higher strengths than any condition of isothermal rolling at 20000 or 2200~F and approaching those obtained by 25-percent reduction at 20000 or 2200"F followed by 15 percent at 18000 or 1600F., The cyclic rolling resulted in substantially higher elongations than were obtained by other conditions of rolling, except 10 percent at 2200~, 2000~, 18000 and 16000Fo, (Compare data in table XI with tables III and V). Creep resistance was also much lower for the material cyclically rolled at 15000 and 18000F than when the upper temperatures were 2000~ or 2Z00~F. (See table XI and fig. 39). The creep rates were actually faster than any other condition of rolling except large reductions at 2200~Fo. (Compare data in table XI with table III or IX). On the other hand, those which were rolled between 1500~ and 20000 or 2200~F were as creep resistant as was obtained under any other conditions of rolling. Rupture and Creep Properties at 1500F. - The rupture strengths were very low for the material rolled at 15000 and 18000F whereas raising the

29 upper temperature to 20000 and 2200'F resulted in considerably higher values. (See tables X and XI and fig. 38b). As at 1200~F, the strengths resulting from rolling at 15000 and 1800'F were low in comparison to isothermal rolling or rolling over a falling temperature range. In fact, only material reduced 65 percent at 1800~F had as low strength. (Compare data in table XI with tables III, V, and IX)o Likewise, those rolled at 1500~ and 20000 or 2200~F were nearly as strong as the strongest produced by the other conditions of rolling. Elongations were quite good at 100 hours. The material rolled at 15000 and 2000~F had very low elongation at 1000 hours. The conditions of cyclic rolling influenced creep resistance in the same way as it did rupture strength. (See tables X and XI and fig. 39). Rolling at 1500~ and 1800~F resulted in very low creep resistance, again only 65-percent reduction at 1800~F caused as low strength. (Compare data in table XI with tables III, V, and IX). The other two conditions of cyclic rolling gave strengths on the high side of the range found in the investigation. Hardness. - There was very little difference in hardness (table VI) for the three conditions of cyclic rolling. The values were 253 for the material rolled at 1500~ and 1800'F and 248 when the upper temperatures were 2000~ or 2200 ~F. Microstructures - As expected, the cycling between 1500~ and 1800WF resulted in extensive precipitation and agglomeration (fig. 40). When the upper temperatures were 2000~ or 2200~F there was little evidence of this. There was little difference in grain size as the result of the three conditions of cyclic rolling. Apparently, the grain refinement obtained at the higher temperatures with equivalent single reductions was avoided. Likewise, the material rolled between 1500~ and 1800~F did not show as much distortion as the material rolled 40-percent at 1800~Fo

30 Response to Heat Treatment A study was made of the degree to which the conditions of hot-working influenced the properties after four heat treatments within the temperature range commonly used in heat treating the alloy. Solution Treated at 22000F, Water Quenched. - The rupture strengths and creep resistance were remarkably uniform in this condition after a wide range in hot rolling conditions. (See tables XII and XIII and fig. 41). All of the rolling conditions studied did not substantially alter the response to the heat treatment. The individual stress-rupture time curves gave the following ranges in rupture strength: 12000F - 100 hours: 42,000 to 45,000 psi 12000F - 1000 hours: 37,000 to 40,000 psi 15000F - 100 hours: 17,500 to 18,500 psi 15000F - 1000 hours: 13,000 to 14,000 psi (only 2 conditions tested to 1000 hours) The minor nature of this variation is shown by figure 41 where all the individual tests plotted well on single stress rupture time curves. Moreover, the rupture strengths agreed with the values for the original stock solution treated at 22000F without any rolling. Elongations, however, were considerably higher than were obtained for the original stock. The limited creep data showed little variation and were similar to the original stock Solution Treated 2200~F, 1 hour, Water Quenched and Aged at 1400~F for 24 Hours. - The data obtained (tables XIV and XV) for a number of conditions of hot-working showed no significant variation in rupture strength or creep resistance. The small range in rupture strengths disappeared when all the actual data points were plotted as one curve in figure 42,

31 Solution Treated 2050~F, 2 Hours, and Water Quenched.- A temperature of 2050'F was used for an extensive series of tests on the basis that this intermediate temperature might show more influence of the rolling conditions on response to heat treatment as reflected in creep and rupture properties. While the data (tables XVI and XVII) again show little variation as a result of different conditions of rolling, there was somewhat more than was observed after treatment at 22000F. The following ranges in rupture strength were indicated by the individual stress-rupture time curves: 12000F - 100 hours: 43,000 to 48,500 psi 12000F - 1000 hours: 38,000 to 42,000 psi 1500~F 100 hours: 16,000 to 18,500 psi 1500~F 1000 hours: 12,000 to 13,500 psi The actual variation represented is illustrated by figure 43 where all the test points plot very nearly on one stress-rupture time curve. No systematic relationship between hot rolling conditions and the variation in strengths was found. Solution Treated 20500F, 2 Hours, Water Quenched and 15-Percent ~ — I'- - I I I L.l._.. I I. l _ _ L. r.-I I_ Hot-Cold Work at 1200~F. - The three conditions of cyclic rolling, representing extremes in as-rolled rupture and creep strength, were solution treated at 2050'F and then reduced 15-percent by rolling at 1200~F. The resultant hot-cold worked materials had practically no variation in strength or ductility. (See tables XVIII and XIX and fig. 44). Moreover, the strengths were the same as had previously been obtained for this same treatment (ref. 1).

32 DISCUSSION Application of the results of this investigation explain many of the variations in high temperature properties of the alloy studied and those of similar metallurgical characteristics when tested in the hot-worked condition. The metallurgical mechanism responsible cannot be accounted for in terms of solid solution, internal strain from cold work, precipitation effects or structural stability. Apparently, some other factor involving the plastic deformation of the metal during working is involvedo The absence of an appreciable influence from prior working on response to heat treatment was unexpected. Apparently, if heat treating conditions are adequate for completion of metallurgical reactions, the properties will be relatively independent of prior history and the major source of variation arises from heat-to-heat differences0 Control of Properties in the Hot-Worked Condition There were two outstanding results from the studies of the properties at 1200~ and 1500~F in the hot-worked condition: 1. As the amount of reduction under isothermal conditions was increased, strengths increased up to an optimum reduction. Further reductions either did not continue to increase strength or resulted in a fall-off in strength. 2, Successive reductions over a decreasing temperature range produced higher strengths at 1200'F than were obtained during working at constant temperature. At 1500'F, the strengths were only slightly higher than were obtained by equivalent total isothermal reductionso These two features of the data can be applied in a general way to account for some of the variations in strength commonly observed for the hotworked condition: i, Medium to low strengths would be expected from large reductions at nearly constant temperature. This seems verified by being charac

.33 teristic of the properties of the alloys from high production processes involving rapid and extensive reductions at relatively high working temperatures. 2. On the other hand, experimentally produced materials frequently have abnormally high strength in the hot-worked condition. This probably arises from production conditions where the metal is given successive small reductions as the temperature decreases, Almost all alloys of the type considered have shown record high strengths in the hot-worked condition. A sequence of hotworking of this type is almost certainly responsible. The experiments carried out in this investigation were not as complete as would be desirable. It appears, however, that the working schedule must meet the following requirements: (a) The reductions must either all be below the amounts causing recrystallization or, if recrystallization occurs at the higher temperatures, be carried down to temperatures where recrystallization ceases. (b) Probably many small reductions at small temperature intervals are most effective. The falling temperature-small reduction principle appears to have considerable importance for high strength at 1200'F. Strengths equal to or in excess of those normally obtained only by hot-cold work in the range of 1200' to 14000F can be produced with finishing temperatures in excess of 18000F. For example: Rupture Properties at 1200~F 100 Hours 1000 Hour's Strength Elongation Strength Elongation Working Conditions (psi) (%) (psi) (%) 25% reduction at 22000F + 15% at 1800~F 61, 000 5 48,000 6 10%o reduction at 22000, 2000~, 1800~ and 1600~F 60,000 20 48,000 18 2050~F, 2 hr., W. Q. + 15% reduction at 1200~F 56,000 4 50,000 4 2200~F, 1 hr., -W.Q, + 15% reduction at 1200~F 54,000 1 52,000 5

34 Apparently, many small reductions at frequent temperature intervals is the key to high ductility in rupture tests in combination with high strength. In addition to the major generalities of the results, there were a number of additional important features of the data of a somewhat more detailed nature relating to properties in the hot-worked condition after isothermal working: 1. Maximum rupture strength at 1200~F is obtained by 15-percent reduction at any temperature. There was little effect from increasing the reduction beyond 15-percent (fig. 45), except for a loss in strength when worked at 21000~F. 2. The temperature of working has a considerable influence on the level of rupture strength at 12000F (figs. 7 and 45), Relatively high rupture strengths, in excess of 50, 000 and 40, 000 psi for 100 and 1000 hours, require working below 2100~F.' 3. The hot-worked condition generally yields rupture -strengths at 1200~F higher than can be obtained by heat-treatment alone. Only exposure to 2100'F and large reductions at 21000F gave lower strengths (fig. 45), In most cases heat treatment will reduce rupture strength at 1200'F. 4, The control of rupture strengths at 1500~F for the hot-worked condition is mostly dependent on the degree of reduction (figs. 7 and 46) and only slightly dependent on the temperature of working. Specific reductions dependent on the temperature of working (fig. 8) are required for maximum strength with large reductions being detrimental. It is noteworthy that a reduction of 7-percent at 22000F yielded as high rupture strength at 15000F as could be obtained by any other conditions of working investigated. Lowering the temperature of working (fig. 46) generally increases the rupture strength at 1500'F for more than optimum reductions. 5. It appears that high elongation and reduction of area in rupture tests at 12000F is dependent on large reductions from 18000 to 2000~F.

35 (See figs. 9 through 14. High temperature working with recrystallization also increases ductility. 6, Elongation and reduction of area in rupture tests at 1500'F was very sensitive to degree of reduction, (See figs. 9 through 14,) Reheating to the working temperatures alone greatly increases their values for 100 hours, However, they can be reduced to very low values by increasing amounts of reduction, High values are only obtained when working is carried out at essentially constant temperature if the temperatures are in excess of 2000~ or the reductions are very small. 7, Creep resistance in low stress tests is apparently more sensitive to degree of reductions than rupture strength. (Compare figs. 16 and 18 with 45 and 46 ) At 1200~F, a good deal of the sensitivity to temperatures of working observed in rupture tests is retained (fig. 16), Low strengths are particularly to be expected for large reductions above 2000'F. At 1500~F, the creep resistance was more sensitive to degree of reduction (fig. 18) with an indication that large reductions below 2000'F might be particularly damaging. 8, The reduction for maximum creep resistance under low stresses is less than for maximum rupture strength (fig. 19), 9, Repeated small reductions to low temperatures with reheats to below 2000~F can lead to very low strengths, Apparently this is the source of low strength in sheet when low reheat temperatures are used to reduce scaling and help preserve a good surface. For the alloy studied, reheat temperatures of 20000 to 22000F for 1/2 hour were adequate to give relatively high strengths. 10o Recrystallization during working without further working at a lower temperature leads to low hardness and low strength. 11, The alloy studied was subject to extensive precipitation during working in the temperature range of 1600~ to 2000O~F. Apparently this is a

36 major source of the excess constituents so frequently observed in the microstructure of alloys of this type. It apparently can lead to low long time rupture strengths at 12000F and probably is related to other strength effects, Mechanisms of Strengthening and Weakening by Hot-Working The results of this investigation mainly provide a basis for hypothesis to explain the observed influences of hot-working conditions on the creeprupture properties of the alloy. Apparently both strengthening and weakening occur during working as evidenced by the increases and then decreases in strength as the amount of reduction was increased. The relative effects vary with test stress and temperature of testing, It appears that a major factor in strengthening involves strain hardening, although this is probably an incomplete simplification. The suggestion is made that weakening mainly arises from a recovery type process during working exhibiting itself as recrystallization during working at the higher temperatures. When recrystallization does not actually occur, the damage arises from- the same structural alterations as those which induce recrystallization to occur at higher temperatures. In addition, there are other effects from the precipitation during working at 16000 to 20000F and during testing. Strengthening during working. - The correlations of hardness to rupture and creep strength (figs. 47 through 54) show that there were reasonably close relationships between hardness and rupture strengths at 12000F. When the stress was reduced to 25,000 psi at 12000F, the resulting creep strength did not correlate as well and the strengths at 15000F were little influenced by hardness. It is recognized that hardness is an imperfect indicator of strain hardening. The correlation at 12000F for high stress rupture tests, however, seems fairly good evidence that when creep is largely a slip process under relatively low temperature rapid creep conditions, strain hardening is a major controlling factor, As the creep rate is reduced and the

37 test temperature increased so that the creep process becomes more what can be somewhat loosely termed "viscous" in nature, strain hardening becomes less effective and the correlation breaks down. Weakening during working- The appearance of recrystallization seems to definitely limit strengthening from working. The evidence at 1200~F for rupture strength is not entirely clear on this point. Maximum rupture strength on working at 21000 occurred for 15-percent reduction whereas recrystallization started at 10-percent and was reasonably complete at 15-percent. It will be noted, however, that this was the only case where rupture strengths fell-off with further reduction (fig. 45) and it may be necessary to obtain complete recrystallization before weakening occurs. Strengths did not increase with reduction at 22000F presumably due to continuous recrystallization. Continuous recrystallization during working first at 22000 and then at 2000"F was also accompanied by low strength. The appearance of recrystallization during closed-pass rolling to a reduction of 65-percent at 18000F did not result in much reduction of rupture strength at 1200'F, probably because it was incompleteo Recrystallization is a recovery process from lattice -strain. It appears first in the grain boundaries. Larger reductions result in its initiation within grains. The suggestion is therefore made that the same structural alterations which lead to recrystallization also lower resistance to creep as it becomes more a function of grain boundary conditions (lower creep rates and higher temperatures) and probably accumulated damage within the crystals. Because actual recrystallization apparently causes damage, it may well be that some sort of similar process such as subgrain formation occurs in the absence of recrystallization. The damage component seems to be accumulative because rupture strengths at 15000F and low stress creep resistance at both 12000 and 15000F is increasingly reduced as reductions are

38 increased past the optimum. Secondly, it appears at smaller reductions as the creep stress is reduced and the test temperature increased (fig. 19), as would be expected for the theory. In fact, due to the analogy of the increasing damage from increasing reduction as creep becomes more viscous in nature, there is reason to suspect that a major source of damage may be the non-slip or viscous flow so long identified with rapid plastic deformation by experimenters. Certainly plastic deformation is non-homogeneous in polycrystalline aggregates and gives evidence of both slip and non-slip processes. Detailed experimental results related to mechanism,- The optimum reduction for maximum rupture strength at 1200~F was constant at 15-percento This suggests that the damage component begins to predominate at this reduction regardless of the temperature of working, There is in fact considerable reason to believe that 15-percent reduction gives near optimum strength for temperatures of reduction as low as 1000'F when stock is initially solution treated at 22000F (ref, 1)o Apparently the hardness can continue to increase with further reduction in the absence of recrystallization but the rupture strength does not. This results in the strengths no longer correlating with hardness (figs. 47 and 48) when worked at 18000 and 1600'FEand probably at lower temperatures. In reference 7, it was shown that correlation with internal strain broke down for creep resistance at 1200'F under 50, 000 psi when a reduction of 40-percent was used at 76~Fo It now seems, however, that this breakdown was due to excessive deformation rather than to recovery during testing as originally proposed. To account for the observed behavior, it seems necessary to postulate that only strain-hardening accumulated with reductions up to 15 percent at any temperature is effective before the damage component prevents further strengthening from increasing strain hardening, It would certainly be easiest

39 to explain this if subgrain formation controlled rupture strength and it was largely dependent on degree of reduction and independent of temperature of working. This explanation would seem to require a rupture strength independent of the temperature of working. Actually, this is not far from the facts. In figure 55 rupture data for reductions of 15-percent down to 10000F have been added to those from this investigation for material initially solution treated at 2200'F. There is remarkably little variation in strength for reductions between 10000 and 2000'F and these can be accounted for in terms of the precipitation reaction between 16000 and 2000 Fo The maximum rupture strengths at 15000F were constant (fig. 8) regardless of the temperature of reduction. Again the data suggest that a recrystallization type of subgrain mechanism controls. In this case, however, it is necessary to have the amount of reduction to obtain the optimum structure decrease with increasing temperature of working. If this is not the case then there must be a complex interrelationship between cold work, recrystallization, precipitation during working, precipitation and agglomeration during testing and the mechanisms of creep and rupture leading to uniformity of rupture strength. Precipitation during hot-working. - The rupture data were replotted (fig. 56) as change in rupture strength for varying reductions. This gave quite uniform changes in strength for a given reduction at 12000F independent of the temperature of reduction, except for 2200~F. There was little change at 1500~F where strengths originally had been mainly a function of only degree of reductiono The sensitivity of rupture strength at 12000F to temperature of reduction was therefore mainly due to effects of heating to the lower temperature. In particular, the low strength of material worked at 21000F seems due to exposure to that temperature and not the effect of reduction, The results of reduction at the other temperatures were also brought closer together. The only

40 suggested explanation involves some influence on the precipitation which is only microscopically evident after working at lower temperatures. The low strength after working at 2200~F seems due to continuous recrystallization preventing strengthening either through restriction of strain hardening or the development of unfavorable grain structures at this temperature0 The drop in maximum rupture strengths for 1000 hours at 12000F from working at 1600~ to 2000~F (fig. 559 seems related to the precipitation during hot-working. The precipitation also induced extensive precipitation during testing at 1200~Fo Both effects would be expected to have little effect on short time rupture strength but would be expected to lower long time strength (ref. 3). The precipitation effects could account for the fall off in strength at 1200~F for the observed hardness after working at 1600~ and 1800~F (figs. 47 and 48). Previous work (refo 3) had shown that during aging hardness can increase but strength increase. The evidence, however, seems more in favor of the main influence being the changes in structure as controlled by'working. This seems to be supported by the lack of evidence of a precipitation effect on low stress creep where precipitation would be expected to be more influential in reducing strength than in rupture tests. Precipitation seemed to have little effect at 1500Fo. It is presumed that this was due to precipitation and agglomeration during testing being so rapid and extensive that precipitation had little influence on properties. In view of the improvement in the relation between rupture strength at 12000F and amount of reduction by using changes in rupture strength, data were replotted using changes in hardness rather than actual hardness. This considerably widened the scatter over those shown by figures 49 through 54. It was concluded that actual hardness was a better measure of strength than changes in hardness. The changes in hardness due to heating to the working

41 temperature (fig. 20) were apparently related to the strengths. Ductility in rupture tests. - The data suggest that the same mechanisms which lead to weakening in most cases lead to increased elongation and reduction of area in the rupture tests. This seems to be particularly true for recrystallization. There are details in the ductility relationships which do not appear to fit into this mechanism. However, the factors which control amount of deformation before fracture are not understood and the deviations are therefore difficult to explain. The most difficult factor to explain is the pronounced increases in elongation at 1500'F for 100 hours resulting from simply reheating to the working temperatures (fig. 14) and the pronounced decreases with increasing reduction at both 100 and 1000 hours. It strongly suggests some influence from the precipitation reaction. The reductions for maximum strength seem to bear little, if any, relation to the reductions for minimum elongation, There must be some complex effects of working which change the initiation of cracking and fracture. Apparently, when the recovery processes during working become sufficiently extensive, ductility is restored. Hot-working with decreasing temperature.- The major change introduced by working on a falling temperature was an apparent increase in the amount of hardening from working first at 22000 and then at 18000 or 1600 F. Not only was the hardness higher than would have been anticipated from isothermal data but the rupture strengths at 1200~F were accordingly higher (figs. 47 and 48), The hardness values after working at 20000 or 1800~ and then at 1600'F were near to the incremental additive effects estimated from isothermal data at the two temperatures. The same was true for reductions of 10 percent at 2200~, 20000, 18000 and 1600~F, The material worked first at 22000 and then at 20000F had low hardness due to continuous recrystallization at both temperatures. The rupture strengths at 12000F of material worked at 20000

42 and 1600'F and those given the reductions of 10 percent were also high and in accord with their hardness. Thus the procedure also allowed the development of high strength and high hardness with large total reduction. This was not quite so true for working first at 1800' and then at 1600~F. The continuously recrystallized material from working at 22000 and 2000'F had strength in accord with its hardness. All of these factors point to an increase in the low temperatures strengthening mechanism during working without an increase in the weakening effect. The cause is not clear from the data. The material worked first at 2200~F may have been simply made more susceptible to strain hardening for a given reduction at lower temperatures. Reduction of grain size with a corresponding increase in the grain boundary area to be moved to obtain a given degree of damage could be involved. The suppression of precipitation during working at 18000 and 1600~F may have been involved. The high strengths of the material worked without recrystallization suggests that a stable structure was developed by the high temperature working which could be given further limited reductions at lower temperatures without increasing the damage. The improvement in strength for low stress creep (fig. 50) was less than for rupture strength, as would be expected. The strengths at 1500~F were generally more nearly in accord with a total reduction of 40 percent (figs. 33, 35, and 51 through 54) than for any additive effect of strengthening without increasing damage. Apparently, insofar as strength at 15000F was concerned, the weakening component involved in the amount of reduction was not inhibited by working on a falling temperature. Cyclic heating and working. - When the samples were prepared by heating and working repeatedly at 1500~F and at 18000, 2000~ or 2200~F, there was opportunity for a number of complicated reactions to occur. Precipitation and agglomeration were extensive when the top temperature was 1800~F. Pre

43 sumably, extensive precipitation took place particularly at 1800'F. When the top temperature was 20000F, the opportunity for precipitation at the top temperatures was reduced. Presumably, there was no precipitation at 22000F and opportunity for nearly complete solution of precipitates formed at 1500'F. Likewise, the opportunity for recovery from prior working was present during the 1/2 hour heating periods at the upper temperature. If it is assumed that the 1/2 hour at 22000F gave opportunity for nearly complete solution and recovery from prior working then the properties ought to be close to those arising from reductions of 5 percent at 22000F plus 5 percent at 1500 F. Data are not available for working at 1500~F. However, estimates based on available data from this investigation and reference 1 indicate that the hardness and properties are close to those which might be anticipated on this basis. Moreover, they are generally in accord with the hardness correlations of figures 47 through 54. The same is true for an upper temperature of 20000F. The material worked between 1800~ and 1500"F, however, had both low strength and low hardness. Moreover, the properties were low on the basis of the hardness correlations (figs. 47 through 54). It is presumed that the combination of extensive precipitation and agglomeration during working at 18000 and 1500'F combined with recovery effects at 18000F and the damage of extensive reduction at low temperatures all contributed to low strength. The recovery from the damage of extensive deformation when 20000 or 22000F was the top temperature would seem to be the major factor. This is probably too much of a simplification for a complex situation but covers the major factors,

44 Reheat Effects The role of reheats was given very little attention in this investigation. The indications were, although it was not proven, that the brief 5 minute reheats used had little influence on the accumulative effects of continued reduction by isothermal hot-working with reheats. On the other hand, solution treatments of 2 hours at 2050~ or 1 hour at 2200~F apparently erased prior history effects. The assumption, therefore, is that in practice reheats will have effects in between these extremes depending on the time and temperature. Sufficiently long times and high temperatures for the metallurgical reactions to attain completion should result in the material being reduced with reheats to start with no great influence from prior history after each reheat. Too short times and low temperatures for completeness of reactions will introduce materials with varied initial properties and structures on which the additional working will be superimposed. This would presumably alter the degree of reduction effects as set forth in this investigation. The material cyclically rolled between 18000 and 1500'F (table XI) gave every indication that 1/2 hour at 1800'F was not removing prior history effects. On the other hand, those cyclically rolled between 2000~ or 2200~F and 1500'F had properties fairly close to those which might be anticipated for solution treated material reduced 5 percent at those temperatures and then given 5 percent at 15000F. Thus the 112 hour at the higher temperatures on the fourth cycle may have quite effectively eliminated any influence from the first three cycles. Response to Heat Treatment The results from this investigation indicate that response to heat treatment is virtually independent of prior working conditions for heattreating temperatures in the range of 2050~ to 2200~Fo That is, quite uniform response at either 2050~ or 2200~F was obtained although the properties were

45 different after each treatment. These data are proof that the damage component from working is not permanent and can be removed by heat treatment, This leaves a question as to the cause of variations in properties observed in practice for specific treatments. The suggestion is that they are due to unidentified heat-to-heat variations, Before being accepted, however, checks should be made for cases where actual differences are observed to make sure that there are not conditions of working in practice which can introduce variable response. Treatment at 2200'F was found to eliminate differences observed between two heats during a previous investigation (refs. 1 and 6). One heat tended to have substantially higher strengths at 12000F when heat treated at 2050~F and then hot-cold worked. This is reflected in figure 55 for Heat 30276. More extensive data in reference 6 showed that the material from Heat 30276 had substantially lower strength at the higher temperatures and longer time periods when initially treated below 2200 F. Moreover, there were extensive structural changes which did not occur in Heat A1726, the material used for the present investigation. There is no clear evidence as to whether the difference between the heats was due to differences in prior history or to heat-to-heat differences. Since a treatment at 2200~F seemed to eliminate the difference between the two heats, the tendency is to suspect prior history as the major factor. This, however, has not been established. The available comparative data are presented in table XX and, with the exception noted, show remarkable agreement considering the possible variations in treatment and testing, It will be noted that,insofar as Heat A1726 is concerned, the original stock heat treated only at 20500F had similar properties to the material initially treated at 22000F and then rerolled before heat treatment at 20500F in this investigation.

46 Heat treatment would be expected to dissolve precipitates and allow their diffusion for chemical uniformity. In addition, recovery from straining effects would be expected either by recrystallization or by.annealing without recrystaflization. From the results obtained in this investigation, it appears that 2 hours at 20500F is somewhat marginal for these reactions to take place. The variations were somewhat more than seems attributable to testing variables. This together with the variations in strength for the same treatment observed in references 1 and 6 between heats leads to some question as to the completeness of the metallurgical reactions in 2 hours at 2050~F after all conditions of working. The absence of any apparent effects from reheating during isothermal working indicates that response to heat treatment is sensitive to time at temperature during heat treatment. Evidently, the 5 minute reheats were too brief to allow much change when the working was being carried out at or close to the reheat temperature. On the other hand, the half-hour periods at the upper temperatures of 20000 and 2200'F during cyclic working apparently were very effective, whereas 18000F was not, It is apparent that as the temperature and time of heat treatment is increased prior history variations will have less effect on the response to treatment. Apparently, complete independence from all such effects requires higher temperatures than 2050 F for 2 hours, whereas there are conditions which can be eliminated by one-half hour as low as 2000~Fo There are working conditions which lead to abnormal grain growth. It is recognized that under these conditions the response to heat treatment will not be independent of prior history regardless of treatment condition. It should be noted that the elongations in rupture tests were more variable than the strengths. In particular, higher elongationa at 1200'F were obtained after a 2200~F solution treatment than were obtained from the original stock,

47 General Obs ervations The relationships between hardness and properties in figures 47 through 54 clearly demonstrate the reasons for the inadequacy of hardness for predicting properties at high temperatures. Large reductions at essentially constant temperature or repeated reductions with reheats to low temperatures too short in duration to allow recovery and solution leads to low strength in relation to the hardness. Furthermore, if a heat treatment is used which does not effectively remove effects of prior history (or allows unidentified heat to heat differences to exert an effect) there will be abnormal variations in the relationship between hardness and strength. For instance, the material from Heat 30276 (ref. 6) had high rupture strength at 12000F in relation to its hardness (fig. 55) and low at 1500'F (table XX) in comparison to the material used for the data of the present report. No direct relationship between grain size and properties were observed. Recrystallization during working was frequently accompanied by low strength. It is doubtful, however, that grain size in itself was nearly as much a factor as was strain hardening, recovery effects and possible structural alterations or precipitation effects accompanying the deformation. The high temperature precipitation accompanying exposure to or working in the temperature range of 16000 to 2000~F had not previously been observed. It certainly is the source of the extensive precipitates frequently observed in hot-worked products. There is good evidence that this precipitate is detrimental to longer time strengths at 1200~F and that its effect was a maximum at 1800 F. Precipitation during working was also accompanied by increased precipitation during testing at 1200~F. This as well as the original precipitation during working could have contributed to the decreased long time strength. Most of the data suggested that the very extensive precipitation and agglomeration during testing at 1500~F overshadowed any effects from prior

48 precipitation. It must, however, be admitted that there were certain cases where a modification of precipitation effects by working would have been a convenient way to explain the results at 1500~F. This was particularly true for the relative= ly high strengths at 1500'F of the materials worked at 1600'F and the large reductions possible at 1600~F without much loss in strength. The reasons for or the significance of the sensitivity of the lattice parameters to cooling rate are not understoodo Likewise, their variation with temperature and degree of reduction is not clear0 There does not appear to be an obvious reason for the observed effect of cooling rate. The variation in parameters with conditions of working does not seem explanable on the basis of ordinary solution and precipitation of odd sized atoms, or in terms of the influence of the working on the crystal structure of the grains. Lattice parameter variations were, however, so large that they do raise a question as to the presence of unidentified metallurgical reactions which could be having more effect on properties than now seem evidento Certainly the results could not be used to estimate solubility of alloying elements as was originally intended0 The observation that diffraction lines were too diffuse for accurate parameter measurements after all reductions at 1600-F and for intermediate reductions at 1800'F suggests that working the metal must not be the same at all temperatures0 The sharpening of the lines for large reductions supports a recovery type mechanism for weakening in the ab-sence of visible recrystallization. Certainly there were corresponding hardness levels at 16000F where lattice parameters could be measured for equivalent hardness values after working at the higher temperatures. This seems to be additional evidence that the plastic flow mechanism during working could be understood better0

49 Limitations of Results The most serious limitation of the results appears to be involved in the use of material drastically hot-worked previously and the use of a 2200'F solution treatment. This treatment was deliberately used to minimize any effects of prior history. The seriousness of this limitation is somewhat difficult to establish. As previously discussed there was little difference in response to a 2050'F solution treatment without the 2200'F treatment in reference 1 work as compared to this investigation with the high temperature treatment. On the other hand, another heat responded considerably differently, either due to a difference in prior working or to heat-to-heat difference which could apparently be eliminated by a 2200~F treatment. It would certainly not be expected that the results would hold for conditions where'the prior working had not broken up the cast structure. The differences in properties between treatment at 22000F and at lower temperatures suggests that the response to further working ought to be different for different initial treatments, However, the initial heating for working at lower temperatures itself altered properties. This may have been sufficient to override the effects of the initial treatment at 2200"F. If so, then the data are applicable for all temperatures of working where the heating for working is sufficient to eliminate the effects of prior working. In any case, this could not be true for temperatures below 20000F and apparently in some cases for temperatures higher than 2050~F. In those cases the effects of working are superimposed on altered initial structures from those considered in this investigation, with a consequent alteration in response to working. The limitations introduced by the method and conditions of working are uncertain. It is expected that the general principles would remain the same. It is difficult, however, to foresee the effects of more rapid and larger reductions during rolling, the difference between rolling and hammer forging, the in

50 fluence of constraint of dies, etc. The surprisingly little difference between open and closed pass rolling suggests that suTch factors may be minor, Only when closed-pass rolling induced recrystallization for a 65-percent reduction whereas it was absent during open pass rolling was the difference significant. The conditions of working on a falling temaperature investigated were extremely limited. It now appears that this would be a fertile field for further experimentation to cover more ranges of reductions and temperatures of reduction. It is suspected that still higher strengths at both 1200' and 1500'F than those observed would be developed. Also, more conditions leading to low strength. Furthermore the mechanism involved ought to be clearero Also, there is reason to suspect that working rapidly enough to cause an increase in temperature might be very damaging to strengths. in this investigation, reasonably uniform working throughout the cross sections was obtained. In actual practice there may be considerable variation in the metal movement within a given cross section. This should lead to variable properties across the section in the hot-worked condition0 The properties at each individual point should9 however, be in accordance with degree of metal movement as indicated by this investigationo Also, all tests in this investigation were carried out on samples taken from the bars in the direction of rolling. There may or may not be significant differences in properties for other directions in relation to the direction of working. It is believed that the general principles observed apply to all alloys of the same general metallurgical typeo This would include practically all of the Superalloys, except those dependent on the age-hardening derived from aluminum plus titanium, The amounts and temperatures of reduction for increases or decreases in strength would be expected to vary depending on. relative strain hardening and recovery characteristics during working, as well as individual structural stability characteristics during testing0

51 The observations recorded in the Results regarding the influence of working conditions on the extent and duration of the various stages of creep was not extensively evaluated. They could have pronounced effects on the time to attain limited amounts of creep and thereby be as important as the other properties more extensively examined.

52 CONCLUSIONS Many of the variations in properties at high temperatures in the hotworked condition for alloys of the type investigated can be predicted from the results. Medium to low strengths will result from high rate of production pro. cesses where large reductions are made at nearly constant high temperatures. Very high strengths at 1200'F and relatively high strengths at 15000F are characteristic of gradual reductions over a decreasing temperature range, probably being responsible for the common high strengths of experimental materialso Strengths equal to those characteristic of hot-cold working at 1200~F can be obtained by such procedures with finishing temperatures as high as 1800~F. Repeated working with abnormally low reheat temperatures is one cause of very low strengths. These general explanations of characteristic properties for hotworked products are based on the following detailed conclusions: o1 Strengths increase to maximum values and then remain constant or decrease as the amount of reduction at constant temperature in increased. Optimum reductions generally are no more than 15-percent and for long time creep resistance are less, Strengths at 1200'F were sensitive to the temperature of hot-working, tending to decrease as temperature increased. Strengths at 1500'F were relatively insensitive to temperature of working. Both were dependent on the degree of reduction, 2. Working over a decreasing temperature range induces higher strengths at 1200 F than can be obtained by working at a constant temperature. Strengths at 15000F are not improved very much in relation to isothermal reductions of the same degree. Low strengths were only obtained when recrystallizationr continued at all temperatures of working 3. Repeated working between 18000 and 15000F yielded very low strengths while upper temperatures of 20000 and 22000F gave quite high strength.

53 The data clearly show that hardness is not a reliable indicator of strength mainly because hardness can continue to increase while strengths are falling off with more than optimum reduction. Ductility in the rupture tests, particularly at 1500 ~F, decreased and then increased with the amount of reduction and very low values were only avoided for the larger reductions above 2000~F. The metallurgical causes for the observed variations in strength and ductility were not established, The data suggest that: 1. Strain hardening is a major source of strengthening, although other factors are involved, 2, Recovery effects due to recrystallization or to the same factors which induce recrystallization appeared to limit strengthening and cause decreasing strength with increasing reduction past the optimum amounts. 3. There were many aspects of the fall-off in strength for more than optimum reduction which suggested the development of subgrain structures as a mechanism. The decrease in the amount of reduction for reduced strength and the accumulative damage effects for low stress creep suggests that weakening appears first in the grain boundary regions, as suggested by recrystallization starting first in such areas. 4. Rupture strengths at 1200"F did not fall-off much with more than optimum reduction of 15 percent suggesting that the damage component of working had less influence on the resistance to the more uniform crystalline slip processes of creep at relatively low temperatures and high stresses than on the more viscous creep processes at low stresses and higher temperatures. 5. An extensive precipitation reaction at 16000 to 2000'F appeared to reduce long time rupture strength at 12000F,. This heretofore unrecognized precipitation reaction also induced extensive precipitation during testing at 12000F, Apparently it had little effect at 15000F due to the extensive precipita

54 tion for all conditions during testing at that temperature. 6, Apparently some effect of the precipitation reaction was involved in the sensitivity of strength at 1200'F to the temperature of working, This also appeared to be the case for ductility in rupture tests at 1500Fo, 7, The results, in conjunction with data from other investigations, suggests that maximum rupture strength at 1200'F for working at constant temperature occurs at a reduction of 15 percent regardless of the temperature of working from room temperature to 2100~Fo Secondly, there is reason to believe that if the precipitation at 16000 to 21000F did not influence strength, the maximum strengths would be nearly constant. Maximum rupture strengths at 1500~F were independent of temperature of working from 1600~ to 2200~F but did not occur at constant reduction, 8. Working over a falling temperature range permitted an increase in the amount of hardening and strengthening for 1200'F for a given degree of reduction at the finishing temperature if recrystallization occurred at the higher working temperatures, If -reductions were kept small at all temperatures so that recrystallization did not occur, the strengthening at 1200'F, from limited reduction, appeared to become additive. The weakening component appeared to remain constant as a function of degree of reduction. Very uniform response to heat treatment were observed in this investigation regardless of the conditions of hot working, It appeared that 2050'F was marginal with no effect at 2200Fo, Brief reheats during isothermal working to maintain temperature did not appear to induce any changes. A reheat of onehalf hour at 2000~F after limited reduction at both 2000' and 1500~F appeared to eliminate the effects of prior working. This suggests that reheats range in their effectiveness depending on whether the temperature and time at temperature are sufficient for the metallurgical reactions to reach completion,

55 An unexplained high degree of sensitivity of lattice parameters to conditions of hot working and to cooling rate was observed. There are a number of limitations to the results imposed by the limitations of the experimental investigation. The experimental material was extensively hot-worked and then solution treated at 2200'F prior to working for this investigation. Rather few data for working over a falling temperature range were obtained. Little study of reheat effects was done. The limitation of the test material to one alloy also raises a question as to the generality of the results. Because hot working was limited to rolling further proof of the validity of expressing the results in terms of amount of reduction would be desirable even though there was little difference between open and closed pass rolling.

56 REFERENCES 1. Freeman, J. W,, Reynolds, E, E,, and Frey, Do N,: A Study of Effects of Heat Treatment and Hot-Col&dWork on Properties of Low-Carbon N-155 Alloyo NACA TN 1867, 1949 2, Frey, D, N.0, Freeman, J, W,, White, Ao E,: Fundamental Effects of ColdWorking on Creep Properties of Low-Carbon N-155 Alloyo NACA TN 2472, 1951, 3. Frey, D, No, Freeman, J, W,, and White, A, Eo Fundamental Effects of Aging on Creep Properties of Solution-Treated Low-Carbon N-155 Alloy. NACA Rep, 1001, 1950 (Supercedes NACA TN I940) 4, Reynolds, E, E,, Freeman, J, W,, White, A, E,: Influence of Chemical Composition on Rupture Properties at 12000F of Forged Chromium-CobaltNickel-Iron Base Alloys in Solution Treated and Aged Condition. NACA Repo 1058, 1951 (Supercedes NACA TN 2449)o, 5, Barrett, C, S,: Structure of Metals, McGraw-Hill Book Co,, New York 1952, 6. Freeman, To Wo, White, A, E,: Properties of Low-Carbon N-155 Alloy Bar Stock from 12000F to 1800Fo, NACA RM51BO5, 1951,

TABLE I PROCESSING OF LOW-CARBON N155 7/8-INCH BROKEN CORNER SQUARE BAR STOCK FROM HEAT A-1726 (Reported by the Manufacturer) An ingot was hammer cogged and then rolled to bar stock under the following conditions: 1. Hammer cogged to 13-inch square Furnace temperature 2210~ - 2220~F Three heats - Starting temperature on die 2050' - 2070~F Finish temperature on die 18300 - 1870 F 2. Hammer cogged to 10-3/4-inch square Furnace temperature 2200~ - 2220~F Three heats - Starting temperature on die 2050~ - 2070~F Finish temperature on die 1790" - 1800 F 3. Hammer cogged to 7-inch square Furnace temperature 2200~ - 2220~F Three heats - Starting temperature on die 2050~ - 2070~F Finish temperature on die 1790 - 1890 ~F Billets ground to remove surface defects. 4. Hammer cogged to 4-inch square Furnace temperature 2190~ - 2210~F Three heats - Starting temperature on die 20400 - 2060~F Finish temperature on die 1680~ - 1880~F Billets ground to remove surface defects. 5. Hammer cogged to 2-inch square Furnace temperature 21800 - 2210~F Three heats - Starting temperature on die 2050~ - 2065~F Finish temperature on die 1730~ - 1870 F Billets ground to remove surface defects. 6. Rolled from 2-inch square to 7/8-inch broken corner square - one heat Furnace temperature 2100~ - 2110~F Bar temperature start of rolling 2050~ - 2060~F Bar temperature finish of rolling 1910~F 7. Bars are numbered 1 through 56, Number I bar represents the extreme bottom of ingot and Number 56 the extreme top position. All billets were kept in number sequence throughout all processing, so that ingot position of any bar can be determined by its number. 8. All bars were cooled on the bed and no anneal or stress relief was applied after rolling.

TABLE II RUPTURE AND CREEP TEST RESULTS AT 1200' AND 15000F FOR BAR STOCK ROLLED ISOTHERMALLY BETWEEN 1600' AND 2200~FIN OPEN PASSES Tested at 12000F Tested at 1500~F Initial Rupture Rupture Reduction Minimum Initial Rupture Rupture Reduction Minimum Rolling Condition Stress Time Elongation of Area Creep Rate Stress Time Elonation of Area Cree Rate osid (h0rs.) (%in 1 inch) () (/hr. ) (psi) (hrs. ) (% in hr. (psi) (/a in~~~~~~~~~~~~~~~~~~~~~ 1(/ inh T.F (%o/hr.) Rolled at160O~F 0 Percent reduction 52,000 29 11 15 - 18,000 85 49 38 - 45,000 179 8 12 0.022 16,000 322 54 56 0.085 41,000 377 8 10 0.012 15,000 324 62 56 0.02 25,000 1002 (Creep Test) 0. 00036 8,000 996 (Creep Test) 0. 00015 5 Percent reduction 55,000 28 5 8 - 22,000 37 27 26 0.2 48,000 113 5 10 0.015 18,000 211 50 42 0.02 40,000 598 7 - 0.0035 16,000 474 31 42 0. 0075 25,000 1054 (Creep Test) 0.000035 8,000 995 (Creep Test) 0. 00007 10 Percent reduction 55,000 54 3 8 0.015 23,000 75 32 26 0.4 43,000 503 2 8 0. 003 19,000 221 27 25 0. 009 25,000 1007 (Creep Test) 0. 000048 15,000 1246 20 31 0. 0024 15 Percent reduction 55,000 134 5 4 0.01 23,000 76 14 22 - 50,000 272 5 3 0.045 20,000 187 14 27 0.013 48,000 664 5 7 0.0015 18,000 449 11 20 0.0085 25,000 1099 (Creep Test) 0. 0001 16,000 684 6 8 0. 003 25, 000 996 (Creep Test) 0. 0001 8, 000 994 (Creep Test) 0. 00003 25 Percent reduction 58,000 72 3 4 - 25,000 62 4 4 4 50,000 172 3 6 0.005 20,000 259 14 7 0.043 43,000 990 5 - 0.00076 17,000 768 6 11 0.004 25,000 1053 (Creep Test) 0. 000d12 8,000 992 (Creep Test) 0. 00006 40 Percent reduction 55,000 100 4 4 0. 013 21,000 88 13 11 - 45, 000 390 4 4 0.005 18,000 251 7 6 0.0075 25,000 1007 (Creep Test) 0.00012 16,000 423 8 4 0. 0028.- - - - 8,000 1135 (Creep Test) 0. 00022.- - - - 8, 000 960 (Creep Test) 0. 00019 Rolled at 1800'F 0 Percent reduction 50,000 44 10 9 0. 1 21,000 33 48 44 - 40,000 352 8 8 0.0095 16,000 205 61 56 0.15 37,000 1499 27 23 0.006 11,000 975 26 22 0.005 25, 000 997 (Creep Test) 0. 0007 8,000 1052 (Creep Test) 0. 00029 5 Percent reduction 50,000 90 10 10 0. 054 20,000 47 59 31 0.15 48,000 137 10 6 0.03 16,000 343 54 48 0.013 38, 500 881 9 14 0. 0055 14, 500 979' 23 40 0. 003 25, 000 1008 (Creep Test) 0. 000095 8, 000 994 (Creep Test) 0. 000035 10 Percent reduction 50,000 118 8 8 0.019 22,000 38 42 47 0.28 42,000 331 8 9 0.007 17,000 343 19 27 0.009 38,000 895 19 13 0. 0024 15,000 >1076 (Turned Off) 0. 0025 25, 000 1000 (Creep Test) 0. 00004 8, 000 1006 (Creep Test) 0. 0004 15 Percent reduction 55,000 76 5 6 0.055 23,000 62 37 40 0.22 50,000 205 6 8 0.021 20,000 185 31 36 0.038 48,000 268 8 10 0.017 18,000 378 11 18 0.0095 45,000 893 13 14 0. 0045 16,000 > 989 (Turned Off) 0. 0025 25,000 1186 (Creep Test) 0. 00006 - - - -- - 25, 000 1008 (Creep Test) 0. 00006 - - - - 25 Percent reduction 50,000 90 4 2 - 25,000 29 19 23 0.21 48,000 253 4 6 0. 008 23,000 61 10 9 0. 075 47,000 136 4 3 0.0052 21,000 115 8 13 0.018 45,000 534 7 6 0.0044 19,000 230 12 9 0.0055 25,000 1030 (Creep Test) 0.000088 16,000 470 5 4 0. 0035 8, 000 1063 (Creep Test) 0. 0001 40 Percent reduction 54,000 83 6 6 0.04 20,000 78 4 4 0.04 50,000 233 7 9 0.0075 16,000 323 5 5 0.009 47,000 415 9 7 0.0047 13,000 382 5 2 0. 004 44,000 532 5 6 0.0044 12,000 626 7 4 0.003 25, 000 1006 (Creep Test) 0. 0002 8,000 1033 (Creep Test) 0. 00045 65 Percent reduction 55,000 41 20 22 0.2 18,000 37 30 7 45,000 325 19 22 0.02 11,000 254 18 15 0.018 40,000 762 23 O 20 0.008 8,000 730 20 5 0. 0028 25,000 1005 (Creep Test) 0. 00026 Rolled at 2000'F 0 Percent reduction 52,000 20 11 10 0.12 20,000 41 63 32 0.6 42,000 308 9 12 0.016 16,000 243 35 49 0.045 39,000 836 14 13 0.008 13,000 1171 32 39 0.0035 25,000 1002 (Creep Test) 0. 00065 8,000 1006 (Creep Test) 0. 00012 5 Percent reduction 48,000 19 5 13 - 20,000 37 38 42 0.14 43, 000 310 9 11 0. 012 17,000 477 20 29 0.01 40,000 384 6 11 0.005 15,000 1014 19 28 0.0035 25, 000 1009 (Creep Test) 0. 00007 8,000 996 (Creep Test) 0. 000045 10 Percent reduction 50,000 40 5 9 - 22,000 52 25 23 0.15 45,000 171 5 7 0.016 19,000 341 10 16 0.011 42,000 600 11 - 0.006 17,000 754 9 10 0.006 25,000 1149 (Creep Test) 0. 00005 8,000 1003 (Creep Test) 0. 00006 15 Percent reduction 55, 000 66 6 6 0. 07 24, 000 62 25 35 0. 2 52,000 151 6 8 0.023 20,000 176 11 11 0.019 50,000 719 12 13 0.0074 16,000 629 3 3 0.0043 45,000 949 16 23 0. 0049 13,000 >1457 (Turned Off) 0. 00035 25,000 1197 (Creep Test) 0.00004 8,000 1154 (Creep Test) 0.00065 25, 000 1000 (Creep Test) 0. 00005 - - - { - -

TABLE II (continued) RUPTURE AND CREEP TEST RESULTS AT 1200~ AND 1500'F FOR BAR STOCK ROLLED ISOTHERMALLY BETWEEN 1600' AND 2200'F IN OPEN PASSES Tested at 1200~F Tested at 1500~F Initial Rupture Rupture Reduction Minimum Initial Rupture Rupture Reduction Minimum Rolling Condition Stress Time Elongation I of Area Creep Rate Stress Time Elongation of Area Cree Rate (psi) h s. o in inch) (%.) (o/hr. (psrsi) h (hrs.) (1o in inch) Th.. oiled at 2000~F 25 Percent reduction 52, 000 86 9 10 0. 082 21,000 61 15 19 0.1 50,000 185 10 12 0.026 18,000 180 10 13 - 48,000 348 14 16 0.02 16,500 287 5 5 0.0056 45,000 967 11 20 0.0045 15,000 420 2 4 0.004 25,000 1001 (Creep Test) 0. 0001 12,500 816 6 6 0.0023 - - - - - 8,000 1025 (Creep Test) 0.00013 40 Percent reduction 52,000 69 21 13 - 18,000 62 28 24 - 50,000 183 15 15 0.03 16,000 197 7 9 0.016 44,000 1786 19 19 0.026 12,500 341 11 12 0.0085 25, 000. 1008 (Creep Test) 0. 00033 10, 000 816 9 8 0. 0016 - ~~- - I~- ~ 8,000 989 (Creep Test) 0. 00055 65 Percent reduction 50, 000 311 28 24 0.02 18,000 62 23 28 - 25,000 1038 (Creep Test) 0. 00013 15,000 252 19 24 0. 015..- - - I12,500 600 13 11 0. 0043.....- - ~~8,000 1002 (Creep Test) 0. 00036 olled at 2100'F 0 Percent reduction 45,000 24 11 I 12 - 18,000 74 40 43 38,000 106 5 12 0.01 15,000 403 43 48 0. 015 32,000 >1122 > 5 (Turned Off) 0.0023 8,000 1003 (Creep Test) 0. 0001 25, 000 1.038 (Creep Test) 0. 0006 - - - - - 5 Percent reduction 45, 000 45 6 12 0.014 20, 000 86 43 38 0.14 40,000 210 - 10 0.0026 17,000 378 27 36 0.011 37,000 1095 12 11 0. 0028 15,000 766 20 23 0. 0026 25, 000 999 (Creep Test) 0. 00021 8, 000 1247 (Creep Test) 0. 00006 10 Percent reduction 45,000 86 11 15 0.019 22,000 86 28 42 - 43, 000 378 12 10 0.01 20,000 132 45 39 0. 045 40,000 840 11 - 0.0046 19,000 250 18 25 25, 000 1005 (Creep Test) 0. 00015 8,000 1163 (Creep Test) 0. 00008 2-1/2 Percent reduction 45,000 67 Broke in Threads - 23,000 48 23 32 - 43,000 180 8 3 0.0076 20,000 194 17 23 0.015 40,000 959 15 15 0.0036 18,000 340 12 22 0.005 25,000 994 (Creep Test) 0. 00014 17,000 656 10 16 0. 0028 8,000 1146 (Creep'est) 0. 000046 15 Percent reduction 50,000 60 14 9 0. 025 20,000 64 20 26 0.09 45,000 270 15 10 0.011 16,000 727 6 7 0.0038 - - - - - 8,000 1003 (Creep Test) 0. 00015 25 Percent reduction 25, 000 1007 (Creep Test) 0. 00052 20, 000 41 39 42 -..- - - 15,000 302 13 20 0. 025..- - - 8,000 1145 (Creep Test) 0. 00014 40 Percent reduction 49,000 10 8 - - 18,000 64 44 43 - 45,000 109 11 11 0.065 15,000 114 52 48 0.035 40,000 394 18 18 0.021 10,000 648 29 35 0.0044 38,000 1032 19 15 0.014 8,000 1150 (Creep Test) 0.0007 25, 000 1000 (Creep Test) 0. 00095 - -.. Rolled at 2200'F I 0 Percent reduction 50,000 38 9 12 0.04 19,000 84 16 25 0.12 45,000 111 4 15 0.011 17,000 196 27 18 0.027 40,000 238 6 12 0.0052 14,000 1417 25 23 0.0035 35,000 >1800 - - 0. 002 8,000 1000 (Creep Test) 0. 00005 25, 000 998 (Creep Test) 0. 00022 - - - - - 3 Percent reduction -. - - - 20. 000 61 35 30... - - - - 16,000 552 41 36 0.011 - ~~~~- - - -8,000 1007 (Creep Test) 0. 000048 5 Percent reduction 45,000 36 12 18 - 22, 000 78 29 30 - 40,000 305 5 11 0.0031 20, o00o 137 22 17 0.019 38,000 1101 6 6 0.00035 19,000 181 19 22 0. 012 25,000 983 (Creep Test) 0. 00016 17,000 434 15 19 0. 0035 ~~~~~~~~~- - - -8, 000 992 (Creep Test) 0. 00006 7 Percent reduction 50,000 37 8 12 - 22,000 66 28 29 - 40,000 366. 7 5 0. 004 20,000 164 21 39 0.025 25, 000 - (Creep Test) 0.00018 18,000 454 15 24 0.012. — - - 8, 000 998 (Creep Test) 0. 00008 10 Percent reduction 50,000 16 11 19 - 21,000 99 21 28 0.016 42,000 98 7 9 0.0052 18,000 392 19 28 0.008 35,000 >1816 (TLrned Off) 0. 0017 16,500 981 12 16 0.005 25,000 1008 (Creep Test) 0. 0002 8,000 1134 (Creep Test) 0.00011 12 Percent reduction 45,000 46 7 14 - 20,000 77 23 47 0.11 40,000 238 7 12 0. 005 17,000 664 12 16 -.: ~ 37,000 1172 8 13 0. 0029 8,000 993 (Creep Test) 0. 0001 15 Percent reduction 48,000 12 10 5 - 19,000 45 19 18 L 45, 000 110 8 8 0.015 17,000 174 32 44 0.07 40, 000 158 8 6 0. 0045 16,000 227 45 43 0.075 35,000 >1314 >8(Turned Off) 0. 0027 13,000 >1143 (Turned Off) 0. 0032 25, 000 1174 (Creep Test) 0. 00038 8,000 1007 (Creep Test) 0. 000125 18 Percent reduction 45,000 34 7 11 - 18,000 63 25 49 40,000 336 7 6, 0.007 16,000 206 20 37 - 38,000 816 19 11 0.0058 15,000 512 17 30 - 25,000 1010 (Creep Test) 0. 0004 8,000 1016 (Creep Test) 0. 00012

,TABLE II (concluded) RUPTURE AND CREEP TEST RESULTS AT 1200~ AND 1500~F FOR BAR STOCK ROLLED ISOTHERMALLY BETWEEN 1600~ AND 2200~F IN OPEN PASSES Tested at 1200~F Tested at 1500~F' [Initial Rupture Rupture Reduction!Minimum Initial Rupture, Rupture Reduction,Minimumt Rolling Condition STres i me Elongation of Are Ci'eu aepSrs Tm lnain o ra C~ Rate (psi, (hrs. I (%j in I i n c /oh)r (%) ) (psii (hr s.) 1(*/ in 1inch) 1 (%7) Rolled at 2200~F 20 Percent reduction I - - I 7002 8 2 36-[ I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 25 Percent reduction 48, 000 50 9 { 10.081 8, 000 84 56'!50 O. 26 4,00 94 6 10 0. 02.2 1 5, 500 252 35 41 0 4 4,00 365 7 I 10 i0.0074 14, 000 633 483.0 35, 000 1340 5 4',0. 0027 8, 000 1200 (Creep Test) 0. 00072 t 25, 000 1679 (Creep Test)!0. 00055 7, 000 938 (Creep Test) 0. 00013 40 Percent reduction 45, 000 47 9 II 1 0. 07 1,000 86 44 i41 0. 16 42, 000 241 10 12 O. 022 1,000 Z55 44!40 0. 05 40, 000 881 14 15 0092 1,500 518 40 i40 0. 022 2 5,000 1000 (Creep T'est).064 8 000 1136 (Creep Te'st) 0. 00098 2 00 1003 (Creep Test) 0. 00065 8,000 1068 (Creep Test) 0. 00088 65 Percent reductionI17 0 18 493.....~~~~~~~~~~~~~~~~~~~~5 000 278 41 45 O. 032 1 000 1137 20 32 O. 007 - 000 1009 (C r e T est)' 0. 0004. TABLE II I SUMMARY OF THE RUPTURE AND CREEP PROPERTIES AT 1200~ AND 1500~F FOR BAR STOCK ROLLED ISOTHERMVALLY BETWEEN 1600~ AND 2200'F IN OPEN PASSES Tested at 1200~F Tested at 1500~F Rupture Strengths Interpolated Rupture Minimum Creep. Rate IRupture Strengths'Interpolated Rupture /Minimum Creep Rate!Rolling Condition (i)Elongation (lo in I inch)[ %/hour.. 10 ( {psi) lElongation (%1 in 1 inch) lo/hour.. 105!100 hr. 1000 hr. 100 hour I1000 hour f 5,0_0 00 psi, Z5, 000 piI100 hr.{1000 hr. [100 hour [1000 hour [15, 000 psi{8, 000 psi lRolled at 1600~F''![' 0 Percent reduction 4 7, 500:37, 500*! 9 7* I4, 500!35 17, 500 14, 500'[ 49 [ * [ 4, 500 [ 15 I 5 [48,000! 38,500! 5! 88 2, 000 3. 5 [ 19, 500 14, 500* 37 [ 25* 500 7! 10: 50, 000:40, 000! 3 3 I1, 000: 4. 8 121,500! 15, 500I 30! 20 [ 250 [ 8 15 i57. 000 4 3, 000 [ 5 [ 5 { 450 {10 li22, 500 15, 500! 14 [ 6 200 3 25 2i,00 1, 0 0 5 5,500 4 43, 000 3 5 500 12!2,0 650 0 40 5 5, 000!44,000' 4 { 4* [ 800 i12 420, 500 ]14, 500' 12! 8* [ 750 [22 ~!Rolled at 1800oF'!; 0Per....t reduction 46, 000 i36, 000 10 i 20 10, 000 70 t17, 500 11, 000 ii57 26 [ 8, 500 [29 5 149, 000 38, 000 10 I 9 5, 500 9. 5 { 18, 500't13, 500 i 55 i 23 { 800 } 3. 5 10 50, 000! 37, 500 8 20 2, 200 41 1,50 5 0 40 15 2 250 4 15 5 ~~{3, 000 45, 000 6 { 15 1',700 6 21, 500 16, 000 { 35 { 5 150{-, 25 50, 000 i44, 000 4 { 9,00921, 000!14, 500*{ 10 5* { 0:40 t 52, 000 4 3, 000 6 5 750 20 18, 500 11, 000'i 4 7 I 1, 000 I45:65!50, 000!40, 000 20 2 23 j 800 2 26!14, 000 i7, 500 2 5, o 1 3, ooo 280'Rolled at 2000~F!:' 0Pe.....t reduction 145, 500!38, 000! 10; 14!9,0O00 b 5 i18, 000.13, 000 I 60 32! 2, 000 }12: 5 4 45,000 39, 000' 6 8*'6, 000 7 }19, 000 15, 500 I 35 19 { 350 I 4. 5: 10 i47, 000,40, 000 5 12 2), 800 5 2l, 000 16, 500 20O 9 3 350 I 9 15' 53,500 {47, 000 6 { 16 2, 000 4 2 2,000 14, 500 I 17 5 [ 300 { 6. 5 [ 25 15 1,500 4 5, 000, 9 1 1 3, 000 [10 [19, 500 12, 000 [ 12 6 I 400 13 40 51. 000 {45, 000 2 0; 19!3, 500 33 1 6, 500 10, 000 [ 17 9 t 1, 2400I 55 ] 65 ~~~~~~ ~~ - -,000;12 t{i17, 000 11, 000 { 22 1 5 1, 400 ]36 Rolled at 2100~F' [ { 0Percent reduction 38, 500!33, 000 5 7 0 0 1 0 3 0* 4 5,50 1 5 {43, 000 {37, 000 6; 12 4, 000 21!1:50 1,50 3 20 1 0 10 {44, 500 39, 500 1 1' 11 3, 500 15 2,00 I6 o* 3 9 0 1 2 145, 000 I40, 000, 9 15;3, 000 {14 121, 000 1 5, 5001 22 10 t 300. 15 48, 000 4 1 000' 1 3 15' 2, 300' - tl19, 000 15, 500 [ 2 6 { 600 1 15 Z5 - - - 55 ~~~~~~~~~~~~!17, 500 13, 000'[ 25 lo* - { 13 40 J44, 000!38, 000 1 i 7 5 12, 000 295 {1 6 000 9, 000 { 50 25 / 3, 500 { 70':oldat 22ooo'F 0Percent reduction 45, 000 1-7.50 37 [0 7!3, 300 {22 I 18, 500 14, 500{ 8 2 800 5 3 19 —, - l9000 15, 000 35 41 / 600 t 4. 8 5 ~~~~42, 500!38, 000 8 6 1, 700 1 0 0 5 0* 2 3 5 7 {44, 000 36, 500*, 8 - - [ -! 21, 000 17 000* 2. 12' 300 8 1o 42,,ooo ~3,,o 7, 00 5 2,,ooo 20 2o /, ooo 16,oo 50,~o 12 35 zo i -? - - -; - I50 1 l8, 000' - I - - It 25',44, 000:,8, 000 6 6!4, 000! 55! 17, 500 13, 000 40 30 4, 500 I 7 40:43, 500, 39, 500 9 { 15 140, 000; 65 1/17, 500 11, 500 4 32 7, 0001 94

TABLE IV RUPTURE AND CREEP TESTS RESULTS AT 1200' AND 1500'F FOR BAR STOCK ROLLED ISOTHERMALLY AT 1800' OR 2000'F IN CLOSED PASSES Tested at 1200'F Tested at 1500'F Initial Rupture Rupture Reduction Minimum Initial Rupture Rupture Reduction Minimum Rolling Conditions Stress Time Elongation of Area Creep Rate Stress Time Elongation of Area Creep Rate (psi)( hrs. ) ((% in 1 inch) ( S ) (o/hr. ). (psi) (hrs.) (o(% in 1 inch) ( % ) (%/hr.) Rolled at 1800~F 15 Percent reduction 55, 000 61 6 8 0. 05 23, 000 38 36 29 0. 040 50,000 151 4 6 0.016 20,000 226 17 12 0.012 25, 000 1025 (Creep Test) 0.00004 18, 000 354 13 20 0.007 - - - - - 8, 000 1001 (Creep Test) 0. 00003 25 Percent reduction 50, 000 51 4 6 0.012 24, 000 22 4 6 0.02 48, 000 141 7 4 0.0053 21,000 158 19 25 0.009 45,000 464 10 6 - 17,000 423 5 8 0. 005 25,000 1030 (Creep Test) 0. 00006 8, 000 1001 (Creep Test) 0. 00005 65 Percent reduction 52, 000 24 23 33 0. 02 14, 000 31 36 41 - (Using square and 45, 000 238 17 32 0. 032 8, 000 238 - - 0.024 oval passes) 40, 000 467 22 28 0.011 6, 000 806 38 31 0. 0065 25, 000 999 (Creep Test) 0. 00045 - - - - Rolled at 2000F 15 Percent reduction 52,000 60 6 7 - 20, 000 172 5 6 0. 03 48,000 302 10 10 0.02 18,000 248 4 4 0.008 25, 000 1030 (Creep Test) 0. 000045 16, 000 725 9 6 0. 007 - - - - - 8, 000 1005 (Creep Test) 0. 00006 25 Percent reduction 55, 000 54 15 10 0. 022 23, 000 76 9 10 0. 022 50,000 342 15 14 0.027 20,000 194 5 9 0. 008 48,000 738 14 12 0.011 16,000 642 5 2 0.002 25, 000 1001 (Creep Test) 0. 000075 8, 000 1005 (Creep Test) 0. 00008 TABLE V SUMMARY OF THE RUPTURE AND CREEP PROPERTIES AT 1200' AND 1500'F FOR BAR STOCK ROLLED ISOTHERMALLY AT 1800'F OR 2000'F IN CLOSED PASSES Tested at 1200'F Tested at 1500F Rupture Strengths Interpolated Rupture Minimum Creep Rate Rupture Strengths Interpolated Rupture Minimum Creep Rat Rolling Condition (si) Elongation (% in 1 inch) %/hour x 103 (psi) Elongation (% in 1 inch) %/hour x 106 100 hr. 1000 hr. 100 hour 1000 hour 50,000 psi 25, 000 psi 100 hour ur 15,000 psi 8,000 psi Rolled at 1800~F 15 Percent reduction 53,000 45,009* 5 - 1,600 4 21,500 16,000* 25 - 200 3 25 Percent reduction 49,500 44, 000* 4 - 1,200 6 21,000 14,500* 12 5* 300 5 65 Percent reduction 48, 000 39, 000 * 20 22* 13, 000 45 10, 500 5, 700 36 38 8, 000 2,400 (Using square and oval passes) Rolled at 2000~F 15 Percent reduction 52,000 46, 000 * 6 - 3,000 4.5 22, 000 15, 000 5 9 400 6 25 Percent reduction 53,000 46,000 15 13 2,700 7.5 21,000 14,500 8 5 280 8 * Extrapolated

TABLE VI B3RINEL HARDNESS OF THE AS-ROLLED BAR STOCK Isothermal Rolling JAolling Temperature Reduction, percent OF 0 3 5 7 10 12 15 18 20 25 40 65 (Open Passes) 1600 214 221 - 239 - 255 - - 270 292 180J 202 - 226 - 237 - 247 259 276 284 9oo0 202 - 215 229 240 245. 240'251 2100 195 213 218 221 203 211 214 210 2200 184 197 208 209 206 200 185 191 194 198 202 194 (Closed Passes) 1800 - - - - - 243 - 263 251 2000, - 238 249 Rolling Conditions Non-Isothermal Rolling Brinell Hardness 25% at 2200'F plus 15% at 2000'F 221 25% at 2200'F plus 15% at 18000F 272 15% at 22000F plus 25% at 1800' F 273 25%fo at 2200'F plus 15% at 16000F.278 10% each at 22000, 20000, 18000, and 1600OF 274 25% at 20000F plus 15%fo at 1600'F 283 25% at 1800'F plus 1.5% at 1600'F> 283 Heat to 18000F, 1/2 hr, roll 5%., cool to 1500'F, roll 5%o, hold.2 hrs, reheat to 1800'F. 253 Repeat cycle 3 more times. Heat to 2000'F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%, hold 2 hrs, reheat to 20000 F. 248 Repeat cycle 3 more times. Heat to 2200'F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%, hold 2 hrs, reheat to 2200'F. 248 Repeat cycle 3 more times.

TABLE VII VARIATIONS IN THE LATTICE PARAMETER* Rolled at 1600~F No Reduction - 3. 5874A Rolled at 1800~F No Reduction - 3. 5890A 10% Reduction - 3. 5869A No Reduction - 3. 5886 40% Reduction - 3. 5891 5% Reduction - 3. 5877 40% Reduction - 3. 5887 Rolled at 2000~F No Reduction - 3. 5889A 25{% Reduction - 3. 586,8A No Reduction - 3. 5889 31%0 Reduction - 3. 5870 5%o Reduction - 3. 5878 35% Reduction - 3. 5893 10%o Reduction - 3. 5870 35%o Reduction - 3. 5890 15%0 Reduction - 3. 5866 (90~ to rolling direction) 18% Reduction - 3. 5869 40% Reduction - 3. 5906 18%0 Reduction - 3. 5867 40%/ Reduction - 3. 5895 (45~ to rolling direction) 65% Reduction - 3. 5900 18% Reduction - 3. 5871 (900 to rolling direction) Rolled at 2100~F No Reduction - 3. 5894A 11o Reduction - 3. 5887A 3% Reduction - 3.'5864 12% Reduction - 3. 5880 5% Reduction - 3. 5863 12% Reduction - 3. 5883 5% Reduction - 3. 5865 15% Reduction - 3. 5892 7% Reduction - 3. 5870 25% Reduction - 3. 5890 9% Reduction 3. 5879 40% Reduction - 3. 5880 * Unless specified otherwise, specimens were air cooled and measurements made on surfaces transverse to the rolling direction. (concluded on following page)

TABLE VII (continued) Rolled at 2200~F No Reduction - 3. 5900A 11%o Reduction - 3. 5890A 3% Reduction - 3. 5884 11%o Reduction - 3. 5891 3% Reduction - 3. 5878 15% Reduction - 3. 5880 5-1/2% Reduction - 3. 5860 15% Reduction - 3. 5875 5-1/2% Reduction - 3. 5866 20% Reduction - 3. 5880 6% Reduction - 3. 5862 25% Reduction - 3. 5888 6%o Reduction - 3. 5871 40% Reduction - 3. 5901 7%o Reduction - 3. 5881 40% Reduction - 3. 5895 7%o Reduction - 3. 5881 Specimens Heated to Indicated Temperature, 1/2 Hour, Water Quenched 1625~F - 3. 5837A 2025~F - 3. 5847A 18250F - 3. 5844 22250F - 3. 5883 Specimens Heated to 2025'F, 1/2 Hour and Cooled as Indicated Oil Quenched - 3. 5848A Cooled in Vermiculite - 3. 5854 Furnace Cooled - 3. 5834

TABLE VIII RUPTURE AND CREEP RESULTS AT 1200~ AND 1500'F FOR BAR STOCK ROLLED OVER CONTROLLED TEMPERATURE RANGES Tested at 1200'F Tested at 1500'F Initial i Rupture Rupture Reduction Minimum Initial Rupture Rupt ure Reduction Minimum Rolling Conditions Stress ~ Time Elongation of Area Creep Rate Stress Time Elongation of Area Creep Rate psi) (hrs.) in 17nch) 70) / -T hrs.)T (hrs. ) (% in 1 inch) ( )) (%/hr. Rolled 25 percent at 2200'F plus 15 percent at 2000'F 50, 000 60 (Piece Missing) 0. 094 20, 000 58 52 33 0.36 47, 000 78 10 6 0. 055 16, 000 143 22 36 0.054 42,000 230 8 9 0.017 12,000 751 21 21 0.0005 38,000 1377 24 18 0.0055 - - - - 25,000 1124 (Creep Test) 0. 00058 - - - - Rolled 25 percent at 2200~F plus 15 percent at 1800'F 60, 000 155 5 5 0. 017 20, 000 90 8 6 0. 058 55,000 273 5 6 0.014 16,000 350 11 11 0.01 50,000 724 6 9 0. 0025 8,280 736 (Creep Test) 0. 00035 25, 000 1175 (Creep Test) 0. 00005 8, 000 1079 (Creep Test) 0. 000185 Rolled 15 percent at 2200~F plus 25 percent at 1800'F 60, 000 91 5 8 0.05 19, 000 i 151 5 5 - 55, 000 277 8 9 0. 011 16,000 f 514 4 8 - 50,000 420 4 9 0.003 14,000 542 7 5 0.006 47,000 1410 8 9 0.0025 12,500 867 7 6 0.0015 45, 000 1866 5 7 0. 0018 8, 000 1146 (Creep Test) 0.00024 25, 000 1008 (Creep Test) 0. 000024 - - - - Rolled 25 percent at 2200~F plus 15 percent at 1600~F 60, 000 121 3 2 - 23, 000 7 19 14 0. 12 55,000 318 3 11 0.0076 19,000 179 12 9 0.018 25, 000 1068 (Creep Test) 0. 000047 14, 000 659 5 5 0. 005 Rolled 10 percent each at 2200', 2000',1800' and 60,000 106 20 22 0.019 23, 000 112 27 14 0. 038 1600'F 50, 000 736 25 16 0. 0015 20,000 231 7 7 0. 017 48,000 1091 18 27 0.0026 16,000 914 6 5 0.0019 25, 000 1155 (Creep Test) 0. 00006 8, 000 1075 (Creep Test) 0. 000035 25,000 1146 (Creep 1est) 0. 00008 Rolled 25 percent at 2200~F plus 15 percent at 1600'F 60,000 101 10 14 - 21, 000 73 3 4 53,000 391 19 19 0.0061 18,000 315 9 3 0. 0058 25, 000 1178 1 (Creep Test) 0.000075 16, 000 416 7 2 _ _ - - - _ 8, 000 994 (Creep Test) 0. 0001 Rolled 25 percent at 1800~F plus 15 percent at 1600'F 60,000 40 5 9 - 20,000 113 5 9 0.04 50,000 343 4 5 0.0041 17,000 310 2 6 0.012 25,000 1004 (Creep Test) 0.00005 8,000 994 (Creep Test) 0.00004 TABLE IX SUMMARY OF THE RUPTURE AND CREEP PROPERTIES AT 1200' AND 1500'F FOR BAR STOCK ROLLED OVER CONTROLLED TEMPERATURE RANGES Tested at 1200'F Tested at 1500~F Rupture Strengths Interpolated Rupture Minimum Creep Rate Rupture Strengths Interpolated Rupture Minimum Creep Rate Rolling Conditions ( i) Elongation (%O/ in 1 inch) %/hour x 10 (pi Elon ation (% in 1 inch %//hour x 10 100 hr 1000 hr. 1 00hour 000 hour 50,000 psi 25,000psi 100 hr. 1000 hr. 100 hour 1000 hour |15,000 psi 8,000 psi Rolled 25 percent at 2200~F plus 15 percent at 2000'F 47,000 39,000 10 20 9,200 58 17,500 11,500 30 20 3,500 - Rolled 25 percent at 2200~F plus 15 percent at 1800'F 61,000 48,000 5 6 550 5 19,500 13,500* 15 - 1,000 18.5 Rolled 15 percent at 22000F plus 25 percent at 1800'F 60,000 48,000 5 8 400 2.4 20,000 13,000 5 5 600 24 Rolled 25 percent at 2200~F plus 15 percent at 1600'F 61,000 49,500* 3 3* 600 4.7 21,500 13,500 19 5 700 - Rolled 10 percent each at 2200', 2000', 1800', and 60,000 48,000 20 18 550 6 23,500 16,000 28 16 230 5 1600'F. Rolled 25 percent at 2000~F plus 15 percent at 1600~F 60,000 49, 000* 10 - 450 7.5 20,500 15,000* 3 5* 240 10 Rolled 25 percent at 1800F plus 15 percent at 1600'F 55,000 46,000* 5 - 410 5 20,000 14,000* 5 - 600 4 * Extrapolated

TABLE X RUPTURE AND CREEP TEST RESULTS AT 1200' AND 1500'F FOR CYCLIC ROLLED BAR STOCK Tested at 1200'F Tested at 1500F Initial Rupture Rupture Reduction Minimum Initial Rupture Rupture Reduction Minimum Rolling Conditions Stress Time Elongation of Area Cree Rate Stress Time Elongation of Area Cree Rate Heat to 1800'F, 1/2 hr, 50, 000 64 44 38 0.24 20, 000 26 29 35 roll 5%, cool to 1500'F, roll 45, 000 157 33 I 40 0.11 17, 000 29 28 26 5%, hold 2 hrs, reheat to 37, 000 540 30 I 40 0.011 8, 000 479 10 10 0.0115 1800'F.Repeat cycle 4 times 25, 000 1086 (Creep Test) 0. 00073 Heat to 2000'F, 1/2 hr, 55, 000 108 18 18 0.1 22,000 62 16 26 0.11 roll 5%,cool to 1500'F, roll 50,000 396 13 17 0.015 18,000 271 10 9 0.0078 S%, hold 2 hrs, reheat to 4S, 000 797 16 22 0. 0056 15, 000 784 3 2 0.0025 2000'F.Repeatcycle4 times. 25,000 1080 (Creep Test) 0.000078 8, 000 870 (CreepTest) 0.00018 Heat to 2200'F, 1/2 hr, 55,000 187 16 22 0.045 22,000 62 28 37 0.053 roll 5%, cool to 1500'F, roll 50, 000 258 11 16 0. 016 18, 000 324 22 5%, hold 2 hrs, reheat to 45, 000 712 19 19 0.011 15, 000 1028 14 12 0.0084 2200'F.Repeat cycle 4 times. 25, 000 1087 (Creep Test) 0. 000056 8, 000 1151 (Creep Test) 0007 TABLE XI SUMMARY OF RUPTURE AND CREEP PROPERTIES AT 1200' AND 1500'F FOR CYCLIC ROLLED BAR STOCK Tested at 1200'F Tested at 1500'F Rupture Strengths Interpolated Rupture Minimum Creep Rate upture Strength Interpolated upture um reep te Rolling Conditions jpsj) Elongation (lo in 1 inch %o/hour x 10 (p is Elongation (% in 1 inch % /hour x l05 100 hr. 1000 hr. T00 hour 1000 hour 50,' 000 si 5 000 s 100 hr. 1000 hr. 100 hour 1000 hour 15,000 s.,000 si eat to 1800'F, 1/2 hr, 47, 000 34, 500 40 30 24, 000 730 12, 800 6,500 20 10 1150 oil 5%, cool to 1500'F, roll S%, hold 2 hrs, reheat to 800'F. Repeat cycle 4 times. eat to 2000'F, 1/2 hr, 55, 500 44, 000 18 1S 1,500 7. 8 20, 000 14, 500 12 5 250 18 roll S%., cool to 1500'F, roll 5%. hold 2 hrs. reheat to 2000'F. Repeat cycle 4 times. eat to 2200'F, 1/2 hr, 57, 500 44, 000 20 20 2, 000 5. 6 21,000 15, 000 25 14 440 7 roll S%, cool to 1500'F, roll S%, hold 2 hrs, reheat to 2000'F. Repeat cycle 4 times.

TABLE XII RUPTURE AND CREEP TEST RESULTS AT 1200~F FOR BAR STOCK ROLLED AS INDICATED AND THEN SOLUTION TREATED AT 2050~F, 2 HOURS, AND WATER QUENCHED Initial Rupture Rupture Reduction Minimum Rupture Strength Interpolated Rupture Minimum CreepRate Rolling Conditions Stress Time Elongation of Area Creep Rate (psi) Elongation (o in I inch) /o/hour i 10l (psi) (hrs.) s("/oin 1 inch) ( -) /o/hour 100 hours'1000 hours 100 hours 100s 0 hours 500 si 0,0 00 psi 15 percent at 16000F 55,000 16 11 13 - 44,500 38,000 11 11 2,800 50 48,000 34 11 13 - 35,000 >1145 >10 (Turned Off) 0. 0033 48,000 34 11,001 25, 000 914 (Creep Test) 0 0005 15 percent at 1800'F 50,000 42 8 16 - 46,500 39, 000* 10 10* 3, 700 40 42, 000 389 10.5 0.012 25, 000 96 1 (Creep Test) 0. 0004 25 percent at 1800'F 50, 000 49 10 13 0. 04 48, 000 42, 000 10 20 4 000 44 43,000 614 23 16 0.013 25,0001 1170 (Creep Test) 0. 00044 40 percent at 1800'F 50,000 73 17 10 - 48,500 38, 000* 15 10* 42,000 6327 12 13 0. 0165 65 percent at 1800'F 50, 000 27 9 12 - -47,500 - 10 45, 000 345 12 1 1 0. 02 15 percent at 2000'F 50, 0001 11 7 7 - 43,000 38, 000* 54 40,000 329 - j 0.016 25,0001 1124 (Creep Test) 0.00054 25 percent at 2000'F 50,000 14 5 18, I 0 5 160 47,000 26 9 18 45,000 392 10 16 0.085 25, 000 1011 (Creep Test) 0. 0006 40percentat 2000F 48,000 44 8 14 0..11 15 percent at 2200'F 50,000 40 10 15 I - I 47,000 40, 500* 10 8* 2,200 60 43,000 428 8 6 101 25,000 4897 (Creep Test) 0. 0006 25 percent at 2200'F 50, 000 18 10 23 - 48,000 38,000 10 - 64 36,000 > 817 (Turned Off) 0o. 0064 25,000 1277 (Creep Test) 0. 00064 40 ercent at 2200'F 45.000 151 7 7 - 46, OO - 7 25 percent at 22000~F 450,000 1 4 5!1 60 ~25 percent atZ'F 1 45,0001' 29 12 11 - 43, 000 t 38,500* 14 20* 7,500 53 plus 15 percent at.40,000 416 19 16 0. 017 1600'F -.25,000 1155 (Creep Test) 0. 00053 Rolled 10 percent each 50,000 44 9 15 0.08 48,000 40,000 12 8,000 49 at 2200', 2000, 1800', 45,000 1 103 12 11 0.040 and 1600'F. 40,000 > 842 (Turned Off) 0. 0062 * Eatrapoated:25,000 1113 (Creep Test) 0.00049 Extrapolated TABLE XIII RUPTURE AND CREEP TEST RESULTS AT 1500'F FOR BAR STOCK ROLLED AS INDICATED AND THEN SOLUTION TREATED AT 2050-F, 2 HOURS, AND WATER QUENCHED Initial Rupture Rupture Reduction, Minimum Rupture Strength Interpolated Rupture Minimum CreepRate Rolling Conditions Stress Time E4 Lation in Area4I Creep Rate (])Si) p Elon ation )% in 1 inch) 9's/hour x 105 s (hrs.) sin 1 inch) %7hour I 100 hours 1000 hours ours 1000 hour l5,OOUpsi 8 p000 psi 15 percent at 1600'F 23,000 16 I 58 53 18,000 12,800 60 1 - 3,200 5 18,000 113 70 60 15,000 354 8 35 51 0. 027 14,000 391 43 36 I 0.023 58,000 914 (Creep Test) 0.00005 15 percent at 1800'F 20,000 30 64 37 - 17,500 13, 500* 50 - - 6 16,000 204 39 39 - 8, 000 961 (Creep Test) 25 percent at 1800'F 20,000 60 61 57 0.320 17,500 12,000* 60 14,000 14,000 429 44 49 - 40 percent at 1800'F 16,000 186 57 56 0.10 - - - - 65 percent at 1800'F 16,000 96 31 55 15 percent at 2000'F 20,000 34 57 54 0.560 17,000 12, 50050 135 3,5 00 6. 5 16,000 167 49 1 50 0.042 12,000 1460 32 40 0.0064 8, 000 973* (Creep Test) 0. 000065 25 percent at 2000'F 25 percent at 2000'F 20,000 1 34 35 32 - 17,000 12,000 50 35 2,800 16, 000 217 58 54 0.042 12,500 684 35 39 0.0048 40 percent at 2000'F 18,000 58 66 61 0.240 16,000 - 50 - 5,000 13,000 472 47 48 0.016 15 percent at 2200'F 20, 000 35 67 58 - 17,500 13,000* 55 40* 4,000 12 14,000 523 42 48 0.021 8,000 1176 (Creep Test) 0. 00021 25 percent at 22005F 23,000 14 57 52 - 18,500 N 50 18,000 155 64 57 0.06 40 percent at 2200 iF 15,000 270 53 53 - - - - 25 percent at 2200hF 20,000 31 41 49 17,000 13,000* 44 i 4,200 10 plus 15 percent at 15,000 276 46 251 0.043 1600'F 8,000 987 (Cree Test) 0. 00015 a220 2000', --- 1800' 14,000 S80 1 43 5 0 - I Rolled 10 percent each 20, 000 46 64 69 0. 2 18, 000 13, 000 50 40 3,100 at 200, 200" 180"14,000 391 43 36 0. 023 and 16000 9 _ _ * Entrapolated

TABLE XIV RUPTURE AND CREEP TEST RESULTS AT 1200~F FOR BAR STOCK ROLLED AS INDICATED AND THEN SOLUTION TREATED AT 2200~F, 1 HOUR, AND WATER QUENCHED Initial Rupture Rupture Reduction Minimum Rupture Strength Interpolated Rupture Minimum Creep Rate Rolling Conditions Stress Time Elongation of Area Creep Rate (psi) Elongation (% in 1 inch) %/hour x 105 (psi) (hrs.) (7 in 1 inch) (%) a /hour 100 hour 1000 hour urs 1000 hours 50,000psi Z5,000psi 15 percent at 1800~F 0, 000 17 11 16 - 45, 000 40, 000 8 12 - - 5,000 89 8 15 - 0,000 1062 12 16 - 25 percent at 1800'F 48, 000 41 12 14 - 45, 500 39, 000 12 10 - - 40,000 792 10 10 0. 005 65 percent at 1800'F 45,000 82 13 8 42,000 133 10 12 0.0052 42,000 37,000 10 6 1,400 38 37, 000 936 6 10 0. 0035 25, 000 1003 (Creep Test) 0. 00038 15 percent at 2000~F 45,000 86 12 10 0. 07 44,500 38,500 12 5 - 34 40,000 534 7 8 25, 000 1046 (Creep Test) 0. 00034 65 percent at 2000'F 45, 000 47 (Broke in Threads) - - - - - 35 25, 000 1001 (Creep Test) 0. 00035 15 percent at 2200'F 45, 000 29 11 18 - 43, 000 38, 500* 10 6* - - 40,000 439 6 7 - 5 percent at 2200'F 45, 000 81 9 18 0. 015 44, 000 - 9 - - 40,000 266 7 11_ _ $ Extrapolated TABLE XV RUPTURE AND CREEP TEST RESULTS AT 1500~F FOR BAR STOCK ROLLED AS INDICATED AND THEN SOLUTION TREATED AT 2200'F, 1 HOUR, AND WATER QUENCHED Initial R upture Rupture Reduction I Minimum Rupture Strength Interpolated Rupture Minimum Creep Rate Rolling Conditions Stress Time Elongation of Area C Rate (si) Elongation (% in 1 inch) %/hour x 10_ (psi) (hrs.) (o i in Tinch /hour 100 hour 1000 hour 100 hours 1000 hours 15,000psi 8,000 psi X5 percent at 1600F 18,000 158 48 52 0.11 18,500 - 48 _ r 15 percent at 1800~F 18,000 108 41 29 - 18,000 - 41 - - 65 percent at 1800~F 18,000 127 51 52 0.13 18,500 13,000 50 30 - - 14,000 637, 29 36 - 15 percent at 2000F 18,000 134 51 50 - 18,500 - -. 65 percent at 2000'F 18,000 85 51 49 0.250 17,500 14, 000* 50 45* 1,700 - l: __ _ _15,000 460 55 56 0.017 |15 percent at 2200'F 18,000 86 47 53 -- 17,500 - 50 - - * Extrapolated

TABLE XVI RUPTURE AND CREEP TEST RESULTS AT 1200~F FOR BAR STOCK ROLLED AS INDICATED AND THEN SOLUTION TREATED AT 2200'F, 1 HOUR, WATER QUENCHED AND AGED AT 1400~F FOR 24 HOURS,Initial Rupture Rupture Reduction Minimum Rupture Strength Interpolated Rupture Minimum Creep Rate Rolling Conditions Stress Time -Elongation of Area Creep Rate (psi) Elongation (%/ in 1 inch) %/hour x 105 {si) (hrs. ) (o in 1 inch) (o%) a o/hour 100 hour 1000 hour 100 hours 1000 hours 50, 0si 5, 000 psi 25 percent at 1800'F 49, 000 62 12 11 0. 075 47,000 39, 500 10 10 9, 000 35 45, 000 194 11 12 0. 032 40,000 841 11 13 0.0076 25. 000 1036 (Creep Test) 0. 00035 40 percent at 1800'F 47, 000 116 13 15 0. 075 47, 000 40, 000 12 15 6, 000 43 45, 000 238 7 12 0.027 41,000 646 21 21 0.012 25, 000 986 (Creep Test) 0. 00043 25 percent at 2000'F 49, 000 62 19 13 0.16 47, 000 41,000* 20 10* 7, 000 45,000 268 12 13 0.36 42,000 470 12 14 0.017 40 percent at 2000'F 48, 000 145 13 12 0. 044 49, 000 39, 000 15 10 6, 000 45,000 226 11 12 41,000 605 10 12 0.01 25 percent at 2200~F 50, 000 61 11 10 0. 085 48, 000 38, 000* 11 8* 8, 500 36 47,000 148 11 9 - 40,000 425 8 9 0. 007 25,000 1007 (Creep Test) 0. 00036 40 percent at 2200~F 50, 000 87 - - - 49,000 38,000 10 14 8,500 45,000 195 8 1 1 0.035 40,000 580 14 14 0. 016 15 percent at 2200~F 48, 000 112 9 14 0. 057 48, 000 40, 000 10 15 5,000 42 plus 25 percent at 45, 000 163 11 13 0. 038 1800~F 40,000 1168 20 20 0.0052 25, 000 1657 (Creep Test 0. 00042 * Extrapolated TABLE XVI I RUPTURE AND CREEP TEST RESULTS AT 1500~F FOR BAR STOCK ROLLED AS INDICATED AND THEN SOLUTION TREATED AT 2200~F, 1 HOUR, WATER QUENCHED AND AGED AT 1400~F FOR 24 HOURS Initial Rupture Rupture Reduction Minimum Rupture Strength Interpolated Rupture Minimurn Creep Rate Rolling Conditions Stress Time Elong ation of Area Creep Rate (psi) Elongation ("%/ in 1 inch) l%/hour x 105 (pi) hrs.) ( in I inch) 1 hour 10 our 00 hour 100ours 1000 hours 15,000 psi,000 ps 25 percent at 1800~F 18,000 110 29 33 0.065 18,000 12,500 30 12 1,400 10 15,000 336 25 27 0.016 12, 000 1254 12 9 0.0012 8, 000 1118 (Creep Test) 0. 0001 7, 000 986 (Creep Test) 0. 00003 40 percent at 1800~F 18, 500 53 22 23 0. 220 17, 000 13, 500* 23 25* 2,200 16, 000 241 24 28 0. 033 l~_____ _ _ 14,500 449 26 28 0.013 25 percent at 2000~F 18,000 132 22 26 0.064 18,500 12,500 25 15 2,000 16,000 250 19 22 0.038 12,500 444 - 0.0064 10, 000 >1526 (Turned Off) 0. 0002 40 percent at 2000'F 19,000 72 34 29 - 18,000 13,000 30 24 2, 000 16,000 256 28 31 0. 028 13,000 987 24 30 0.0075 25 percent at 2200~F 18,000 109 28 29 0.11 18,000 13, 000 28 10 1,300 15,500 278 14 20 0.018 14,000 549 12 17 0.006 40 percent at 22000F 18,000 100 30 27 0.08 18,000 13,000 30 - 1,400 15,000 336 27 26 0.014 13, 000 >1087 (Turned Off) 0. 0034 25 percent at 2200~F 18,000 86 36 39 0. 175 17,500 12,500 35 30 1, 500 plus 15 percent at 16,000 225 32 21 0.04 1800~F 13,000 857 30 19 0.004 * Extrapolated

TABLE XVIII RUPTURE AND CREEP TEST RESULTS AT 1200~F FOR BAR STOCK ROLLED AS INDICATED AND THEN SOLUTION TREATED AT 2050~F, 2 HOURS, WATER QUENCHED PLUS 15 PERCENT HOT-COLD WORK AT 1200~F Initial Rupture Rupture Reduction | Minimum Rupture Strength Interpolated Rupture Minimum Creep Rate Rolling Conditions Stress Time Elongation of Area Creep Rate (psi) Elongation (%/ in 1 inch) %/hour x 10l 5 (psi) (hrs.T) o in inch) ( o/hour 100 hours 1000 hours 50, 000 psi 25, 000 psi Heat to 1800'F, 1/2 hr, roll 60,000 36 2 1 0. 048 57,000 51, 500 4 4 70 8 5%, cool to 1500~F, roll 5%, 55,000 343 4 4 0.0011 hold 2 hrs, reheat to 1800~F. 50, 000 1517 5 5 0. 0007 Repeat cycle 3 more times. 25, 000 1001 (Creep Test) 0. 00008 Heat to 20000F, 1/2 hr, roll 55, 000 90 4 5 0. 0055 55, 000 49, 000 4 - 56 4 5%, cool to 1500'F, roll 5%, 50,000 540 2 10 0.0056 hold 2 hrs, reheat to 2000'F. 40,000 >1025 (Turned Off) 0.0005 Repeat cycle 3 more times. 25, 000 1028 (Creep Test) 0. 00004 Heat to 2200'F, 1/2 hr, roll 60, 000 14 (Broke in Threads) - 56, 000 50, 000 4 4 80 4. 5 5%, cool to 1500'F, roll 5%, 55, 000 207 2 3 0.004 hold 2 hrs, reheat to 2200~F. 50,000 954 4 5 0. 0008 Repeat cycle 3 more times. 25,000 1050 (Creep Test) 0. 000045 _ TABLE XIX RUPTURE AND CREEP TEST RESULTS AT 15000F FOR BAR STOCK ROLLED AS INDICATED AND THEN SOLUTION TREATED AT 20500F, 2 HOURS, WATER QUENCHED PLUS 15 PERCENT HOT-COLD WORK AT 1200~F Initial Rupture Rupture Reduction Minimum Rupture Strength Interpolated Rupture Minimum CreelRate Rolling Conditions Stress Time Elongation of Area Creep Rate (i) Eonation ( in 1 inch) %/hour x 103 vi(_hr, (% in 1 inch) %) /o/hour 100 hours 1000 hours 100hours 1000 hours 15, 000i Heat to 1800"F, 1/2 hr, roll 26,000 54 21 34 23,500 16,000 20 10 100 5 5%9, cool to 1500*F, roll 5%, 22, 000 204 16 19 0. 011 hold 2 hrs, reheat to 1800~F. 18, 000 585 11 12 0. 005 Repeat cycle 3 more times. 8, 000 1125 (Cree Test 0. 00005 Heat to 2000-F, 1/2 hr, roll 26,000 50 16 30 0.150 24,000 18,000 10 7 100 7 5%, cool to 15000F, roll 5%, 22,000 315 9 19 0. 0078 hold 2 hrs, reheat to 2000'F. 19, 000 787 7 9 0.i0024 Repeat cycle 3 more times. 8,000 1028 (Creep Test) 0. 00007 Heat to 2200~F, 1/2 hr. roll 26,000 65 15 28 - 24,000 17,500 12 10 70 4.4 5%, cool to 15000F, roll 5%, 22, 000 186 10 16 0. 016 hold 2 hrs, reheat to 22000F. 18,000 784 9 9 0. 0015 i Repeat cycle 3 more times. 8, 000 984 (Creep Test) 0.000044

TABLE XX COMPARATIVE DATA ON RESPONSE TO HEAT TREATMENT Rupture Strength Rupture Elongation Secondary Creep Rate (% per hour) Heat Temp. 100-hour l00-hour 100-hour 1000-hour 12000F 1500~F Refp No. (OF) (%) (%) (%) (%) 50, 00(psi) 25,000(psi) 15,000(psi) 8,000(psi)erence 20500F, 2 hours, Water Quenched 30276 1200 45,500 39,000 10 20- -- -- 1 A1726 1200 43,000/ 38,000/ 48,000 42,000 7-15 8-20- -- -- -- (1) 2050~F, 2 Hours, Water Quenched + 15 percent Hot-Cold Work at 1200~F 30276 1200 62,000 53,500 1 5 0.0009.000015 -- -- 1,6 A1726 1200 55,000 48,000 3 1.5.0007/.00004/.001.00007 -- -- 6 A1726 1200 55,000/ 59,000/ 57,000 5 1,500 4 4 - - - (1) 30276 1500 22,000 12,500 16 12 -- -- -- -- 6 A1726 1500 24,000 17,000 14 6 -- --.0008 -- 6 A1726 1500 23,500/ 16,000/.0006/ 24,000 18,000 10-20 7-10 -- --.0008 -- (1) 2Z00~F, 1 hour, Water Quenched 30276 1200 42,000 38,000 4 6 -- -- - 1,6 A1726 1200 42,000/ 37,000/ 45,000 40,000 8-12 6-12..... (1) 30276 1500 19,000 14,500 50 36 -- -- -- -- 6 A1726 1500 17,500/ 13,000/ 18,500 14,000 41-50 35-45 -- -- -- (1) 2200~F, 1 hour, Water Quenched +-24 hours at 1400~F 30276 1200 50,000 42,000 14 21 -- -- -- - 1,6 A1726 1200 47,000 42,000 10 10.09.00025 -- -- 6 A1726 1200 47,000/ 38,000/.00035/ 49,000 40,000 10-20 8-15.05/. 09.00043 -- -- (1) (1) Data from this report.

TABLE XX (continued) COMPARATIVE DATA ON RESPONSE TO HEAT TREATMENT Rupture Strength Rupture Elongation Secondary Creep Rate (% per hour) Heat Temp. 100-hour 1000-hour 100-hour 1000-hour iZOO" 1500F ReferNo. (OF) (%) (%) (%) (%) 50, 000(psi) 25, 000(psi)pence 22000F, 1 hour, -Water Quenched + 24 hours at 14000F 30276 1500 21,000 14,000 50 23 -, -- 6 A1726 1500 21,000 14,500 35 33.004.000033 6 A1726 1500 17,500/ 12,500/ 23-35 10-30 --.0131,022.0001 (1) 18,000 13,500 (1) Data from this report.

As-Received 7/811 Bar Stock Sniation Treated (2200'F, 1 hr., W.Q.) Rolled Isothermally at Indicated Temperature 1 000F 18 0OF 2 00 OF 222 00F Rolled 0, 5, Rolled 0, 5, Rolled 0, 5, Rolled 0, 5, Rolled 0, 3, 109 15 25* 101 15t 25*1 lot 15t 259 10, 12, 15, 25, 5, 7, 10, 12, and 40%. 40* and 65*%o. 40* and 65*% o and 40*% 15, 18, 20, 25, 1 ______________ _____________ 1 ~~~40* and 65*%., Rolled 15, 25 and 65*%o Rolled 15 and 25% in closed passes. in closed passes. *Reductions required one or more reheats. Figure 1 - Flow Sheet of the Rolling Program. Reductions were Made in Open Passes Unless Otherwise Indicated.

l_____a) Tested at 1200F a Tested at 1200|~F 41001 hour 30 3 1000~~1 huhour 1000 hour 0 Reduction, percent Reduction, percent Figure 2 - Influence of Isothermal Reductions at 2200ZF on the As-Rolled Figure 3 - Influence of Isothermal Reductions at 2l00~F on the As100 and 1000-Hour Rupture Strengths at 1200 and1500F. Rolled 00 and 1000-Hour Rupture Strengths at 12 a Reductions Larger than 25 Percent Require One or More Re- 1500'F. A Reduction of 40 Percent Required One Reheat heats During Rolling. During Rolling. heats During Rolling. During Rolling.

Ia Tested at 1200~F (a) Tested at IZ006F ~ 100 hour 35,35 _______(b) Tested at 1500F _ (b) Tested at 1500'F 5 25 so L |1 000 hour | 1000 ho ur I0 5 S | 5 Bo b r 1 5, 0 10 20 30 40 50 60 10 20 30 40 60 Reduction, percent Reduction, percent Figure 4 - Influence of Isothermal Reductions at 2000F on the As-Rolled Figure 5 - Influence of Isothermal Reductions 100 and 1000-Hour Rupture Strengths at 1200~ and 1500'F. Hour As-Rolled Rupture Strengths at e200 and 100~F. Reductions Reductions Larger than 25 Percent Required One or More RehPats Larger than 25 Percent Required One or More Reheats During RollDuring Rolling. ing.

(a) Tested at 1200~F 60. 100 hour 55 50 45 D 1000 hour 40 Reduction, percent Figure 6 - Influence of Isothermal Reductions at 1600F on the AsRolled 100 and 1000-Hour Rupture Strengths at 12000 and 1500~F. Reductions Larger than 15 Percent Required One or More Reheats During Rolling.

60 (a) Rupture Strengths at 1200~F Code Reduction 55_ __ _ 0 15 A5 50 a -um Stren AIr 65 (clos':'d pas 45F igur 2 51p(b) Rupture Stren ths at 15000F 40 2 0: 35 _ __ _15 _ _ __ _ -.. - 100 Hours 50 10 1000 Hour 45 20 1000 Hours 40 4 35 10 30! 5 1600 1800 2000 2200 1600 1800 2000 2200 Rolling Temperature, ~F Rolling Temperature, ~F Figure 7 - Influence of Temperature of Hot-Working on the Rupture Strengths for 100 and 1000 Hours at 12000 and 1500~F.

I-(eductions for Maximum Rupture Streng 25X O 100 Hours 0 20 P4IF: 1000 Hour Mxmum Rupture Str ength 5 I Maximum Rupture Strengths Z5 25 15 1600 1800 2000 2200 Rolling Temperature, ~F Figure 8 - Reduction by Rolling for Maximum Rupture Strength at 1500~F.

60 50 U 40 to 0 01 4) J! j 4 ws~~t|__be/TDC ~Aj | O loo hr Elongation 1200F.XD 0 l00 hr Elongation 11000 hr Elongation 0 0 10 20 30 40 50 60 70 80 Reduction, percent Figure 9 - Influence of Isothermal Reductions at 2Z00"F on the As-Rolled 100 and 1000-Hour Interpolated Rupture Elongations at 1200~ and 15000F. Reductions Larger than 25 Percent Required One or More Reheats During Rolling. 60 O 100 hr Elongation 1200F 5 1000 hr Elongation 50.~ I~ DI I I /I 1~~~~ 100 hr Elongation CE:~~~~~~~~~~~~~~~~ ~~1500"F a | l l l | B 11000 hr Elongation - 40 0 30 20 0 10 / 0 10 20 30 40 50 60 70 80 Reduction, percent Figure 10 - Influence of Isothermal Reductions at 2100~F on the As-Rolled 100 and 1000-Hour Interpolated Rupture Elongations at 12000 and 1500~F. The Reduction of 40 Percent Required One Reheat During Rolling.

60,, O 100 hr Elongation 1200~F * 1000 hr Elongation 50 O 100 hr Elongation -d~~ ~15000F - 1000 hr Elongation 40 30 20 0 10 Z0 30 40 50 60 70 80 Reduction, percent Figure 11 - Influence of Isothermal Reductions at 2000~F on the As-Rolled 100 and 1000-Hour Interpolated Rupture Elongations at 1200~ and 1500~F. Reductions Larger than 25 Percent Required One or More Reheats During Rolling. O 100 hr Elongation 1200"F 1000 hr Elongation Sc 0 100 hr Elongation 1500OF 0000 hr Elongation 40 0 0 o ) 30 r 2 4.1 10 0 10 20 30 40 50 60 70 80 Reduction, percent Figure 12 - Influence of Isothermal Reductions at 1800"F on the As-Rolled 100 and 1000-Hour Interpolated Rupture Elongations at 1200' and 1500'F. Reductions Larger than 25 Percent Required One or More Reheats During Rolling.

70 o - 100-hr. Elongation 1200~F -1000-hr. Elongation 60 - - 100-hr. Elongation 1500O~F * -1000-hr. Elongation U 0 Ad 20 1-I 0 10 20 30 40 50 6 Reduction, percent Figure 13 - Influence of Isothermal Reduction at 1600'F on the 100 and 1000-Hour Interpolated Rupture Elongations at 12000 and 1500'F. The Reduction of 40 Percent Required One Reheat During Rolling.

70 100 Hours 60 _ k 0% Reduction o 50 0 i Elongation 40 I1 40 ~4 30 Minimum 30 u lEneducation for I o' e/dtMinimum Elongatio n c~ 1W 20 202 I olling T e mp e ratur e, F-) 10__ 14 _ _i __ Rolling Rp0 In 10 a 0 4-) Minimum Elong tion o 0 40 1000 Hours 4I 0t 30 30 0% Reductio k Cg Elongati n C 0 4 20 20 Reduction for Minimum Elon ation 1W01 10 1600 1800 2000 2200 Rolling Temperature, ~F Figure 14 - Relationships Between Rolling Temperature and Elongation for Rupture in 100 and 1000 Hours at 1500~F for No Reduction and the Reduction giving Minimum Elongation.

100( Lf) I _ ~~ ~~~~~ ~~~~~~~~~~~~~~~~~~~~~~............... _ L., _. o10~ j 10 100F x~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 U k ~~~~~~~~~~~~~~~~~~~~~~d~~~~~~ IV U a~ ~ ~ ~ ~~~~~~~~~~ ~)~~~~~~~~~~~~~~~~~~~5.... F 0)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~eo 0)~ __________ _ _ CI,'' /,/ V 0) c0)~ 0)0" 40 5 0 60~~~~~~~~~~~~0 0506 L, r a I r I I~ ~~ ~ 1',, I \ I I I I I I I d~~~~~~~~~~~~~............ 0 10 20 30 i050 - - 30 40 300 Reduction, percent Reduction, percent Fijure 15 - Influence of Isothermal Reductions at Indicated Temperature on Figure 15 Influence of Isothermal Reductions at the Indicated Rolling the As-Rolled Minimum Creep Rates for 50,000 psi at 1200~F. Temperature on the As-Rolled Minimum Creep Rates in 1000 Reductions Larger than 15 Percent at 1600*F, or Lar'2er than Hours for 25,000 psi at 1200F. Reductions Larger than 15 25 Percent at 1800*F and Above, Required One or More Reheats Percent at 1600~F or Larger than 25 Percent at 1800~F and Durin-g Rollintl. Above, Required One or More Reheats During Rolling.

100 II I I 22Dn'~~22-0F LOI u 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ lot~ ~ ~ ~ ~~~~~~~~~~~ 102100) 4) 2100OF 0 0 /1 $4 8/00' 4)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~4 cok P4 x000116 04~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~' 4)u 4) 0'4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 d I I I I 2000'F I~~~600O 0 0030 064)102 Figure 17- Infunc f stera Rdciosatte niatdRoln Fgre1 Ifunc f stera Rdc r ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~U O io 20 30 4 50 - -60~- -- ~ o 10 ) __________6 Temperature on the As -Rolled Minimum Creep Rate for 15, 000 Temperatures an the As-Rolle Mnm Ce Rt 10 psi at 1500'F. Reductions Larger than 15 Percent at 1600'F or Hours for 8, 000 psi at 1500'F eutin are ha 5Pecn Larger than 25 Percent at 1800'F and Above, Required One or at 1800'F and Above, Require O o r Rha Din lMore Reheats Dtiring Rolling. ing.

(a) 1200'F 40 50, 000 psi 30 30 [ (b) 150'F 15,ooo -,si 0 1 600 1800 2000 2200 Rollin-, Temperature, ~F -- Minimum Creep Rate at Indicated Stress _- - Maximum R upture Strenoth Figure 19 - Lifluence of Rolling Temperature on the Percent Reduction for Optimum Creep and Rupture Properties at 1200' and 1500'F for the Indicated Conditions.

300 1600OF 280 260 240 F 220 2 I00 IF 200 NW 22C0" 180 10 20 30 40 50 60 8 Reduction, percent Figure 20 - Influence of Isothermal Reductions at 16000, 18000, 20000, 21000 or 22000F on the As-Rolled Hardness. Reductions Larger than 15 Percent at 16000 F, or Larger than 25 Percent at 18000 F and Above, Required One or More Reheats During Rolling.

/t ~~~~~~~~~~~i' 3 0 ~ ~';.." —. I i-~~~~~ ~~~~~~~~~~ ~~~~ "~,'~ z-,.',-.I.. Rolled~~~ 0' pecn Role 15~: percent. ". 5.... i~~~~~~~~~~~ 0 )I c~~~~~~~~~~~I ",~ t~~~~~~~~~~~~~~i',~ j~~~~~~~~~~~~~~~~~~~~~~~~:~~~~~~~~~~~~~~~.''',x'>,r~~~~~~~~~~~~~~~~~~i:~'lrA X100 X1000 Rolled 40 percent Figue 2 - ffet o IsthemalRedctios a l~o0Fon he icrstrctues.Bar Stock was Solution Treated at 2200~0F, 1 Hour, and Water Quenched, Prior to Rolling. (Electrolytically Etched in 10 Percent Chromic Acid.)

i~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~,;,..:.,-,,, ~ ~ ~ ~'.I -~...,o,,-~~~~~~~~~~~~~~~~~~~~~~~~~~-.,~~~~~~~~~~~~~~~~~~~~-,~1V. ~- ~ ~'-".'4~':-...... w:! ~',~ i"!~';li'~-'~.7 *~~~~~~< 7: ~~~~~~~~~~~~~ ~'0 -*,.."" 1' ~' fM.~ ~~~~~~~~ Y~~~~~~~~~~~~~~~~~~~~i'I''(~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~',"I1';: "~ *."'.-" ~ "i,0 / p4 1 i,.,:.".'B.*.'..~ X1000 p4. q *Qr~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Rolle 40pecntRlld65prcn Figure 22 ~~~~~~~~~~-'Efc of Istera Reutin at" ~800 on~ th Microtrctre.:' Ba Stoc wa Solutio Treated at.~;... 2200 0F,1 Hourand Watr Quenchd Priorto Rollng. (Eletrolytially Ethed in.1 Percen.Chromi Acid.)

to.~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.. ~..-.'p.i \ A1?(~~~~~~~~~~~~~~ j.,.x \ ~~~~~~~~~~~~~~~~~~~~.-.~...0 01.:-'l P.... Rolled 40 percent Rolled~~~~~~~~~ 65 er Acid.: ~~~~~~~~~~~~~~v~~~~~~~~~~~ ~~-'" ~ 4 -'.';*',..'.,!,...-~,A.XW.. -~~~~~~~~~ ~~~~..' ~,'LA.~~~~~~~~~~~~~~~~'. " - ~.j~.7, *.q ~ X100 X1000 X100 X1000 Rolled 40 percent Rolled 65 percent Figure. 23...~.' - Efec of " —:, Istera Reutin at "0'0 on the Micosructre... Bar. Stoc was Souto Trae at 22000F 1 Hour and Water~~~~~~~~.. Qunce Prio to. Rollin.'' (Eetoyial Ethe in 10.Percent:Chromi Acid.)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.' —.','~ -~)\'. ~.' 0,.~ /~.Ii'~~~ ~~~-c A" ~~~~~~~~~~~. I *o~~~~,, /. ~,, ~ ~ ~ ~ f..:,( / -v'K,''~ /o~ r~~~~ ~ ~~~''' "..'...' "''/ 0,P - ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~...: /.~.~'~,' F'f ~.~ ~ ~ ~ ~.e-';',:,-?,N:~ ~~~~~~.; -~' -.''.J " ". ~'q..,''',. ". t''i "! "-1 i-,''~' r~~~~- /~'~ ~~~~~~~~~~~~~~~~~~~~~~'..... ~'....-"',.'-' ".,.:"r-". ~;, "';''' ( ",' -...,',,~...~-. A~ ~~ ~~~~~~~~~~~~~~~~~~~~~~,,~,,,N. X1' X-000 X100 X_1000. Acid.)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

:'. ~'f'(,'' ~...'L —-"' 1''' ":'~ ~.,~ ~ >a">~~:.-" —.~~,' *,.. ~~~~~~-k ~ ~ ~ ~ ~ ~ ~ r......' 0'",'.. *~~~~~~~~~~~~~~~~'~~~ ~... 1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~'17> Ai' y ~ ~~~~~~~~~~~~~~~~~~~~~ w.'4'' " A'0.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~:':.~.'.:'.::',"''4' *'~'~,"'\ -'....k'. -'.~''~ t "',...~.'.... ".''.' "'' "' "s)'....~:"~"'~'"'~"" "'........,..." ~~:~, -,..-," —?'"4:z''~0'~.: x10 xloo x'0 Role.1 pe,~:'.~~rcen Rolled' 40~ percent:''~..~: "''".igur 25',.:;:., ~ - Mcrotrctues.ftr Creep Tesin for 1000- Hour at. 1.0 with a,.. Stes of 25,000 psi."-d'.;~. Prio toTesting, Bar Stock was Solution Treated at 2200 0F, 1 Hour, Water Quenched, and Rolled at 16000F as~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Indicated~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~." (Eletroytiall Ethe in1.ecn Chrm' Acid::.)

Ilk,~~~~~~~~~~~ 1ole 5 pecet ole 10 pye>/ce * A..A.~. I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"~ "'. "~ -~:'' " %~; 0.? Ike,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 4.?:~~ ~.~.'',.'nf~~~~~~~~f )'..... ~_1 "T -...' ~~~ 4 ( 4j~' ~~~~~~~~~~~~~~~~~~~'''~ XIOO XlOOO Xl 00 X 0 Rolled 15 percent Rolled 40 percent ]Figure 26 - Microstructures after Creep Testing for 1000 Hours at 1200'F with a Stress of 25, 000pi Pirt Testing Bar Stock was Solution Treated at 2200 0F, 1 Hour, Water Quenched, and thenRleat20F As Indicated. (Electrolytically Etched in 10 Percent Chromic Acid.)

'~~~~~~~~~&~~~.. # \ \ ~~~~~~~~~~~~~~~~~' ~ /...:.. ":~~~~~~~~~~~~~~~~~~~~~~~~~~' ~': ~: - "' "~:."''':"'~ "' ""''"::':;, ~~~~~~~~~~~~~~~~~~~~~~~~e:"::: ~,,,~,.,''!',.'....-... i..,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~?....~~~~~':, "" r,.:. XlOO~~ ~~ ~~~~~~~ "~''~ at "80'.,,..i ~ ~ ~ x00 x_~. xl.o','.oo. ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~',,. -''.I. C'.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i'~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~I''~~~~~~~~~~~~~ - -'. -'",s:.,.,..... I...,.:'.>,..-.:..,-, ~~,....:ri..%:,,.:o.. ~_.. ~.......:~'i:"~~~~~~~~~~~~~~~~~~~~~~~~~1 X100~~~~~~~~~. X.00 X.1....0:0 X.1000...,....-,:....,.~.,.~,......_.'.~... Rolled~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~,,., 15 pecn at..:,0".F.Rolled 40.'., percent: at. 2."F Figure..27.-'TpclMcotutrsatrCepTsiga'50 wih a Stes of 8,0'sfr10 hor..Prio to; TetnBrSokwsSluinTetda 20 Hour.,, Wtr.uncen Role as...... Indiated (Electrolytically Etched in 10 Percent~~~~~~~~~~~~~~~~~~, Chromi Acid.)

*-Rolled at 2000'.F X-Rolled at 1800'F 3. 5900 3. 5890 _____ 3. 5880 Cs 3. 5870 3. 5 8 6 0 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 3.585 10 I'5 20 25 30 35 40 65 Reduction, percent ]Figure 28.Influence of Isothermal Reductions at 18000 or 20000F on the Lattice Parameter of As-Rolled Bar Stock. Reductions Larger than 25 Percent Required One or More Reheats During Rolling. All Specimens are Transverse to Rolling Direction Unless Indicated Otherwise. 3. 5900 3. 5890 3.5S880 3. 5870 3. 5850205

3. 5910 3. 590 3. 5890 4) 4.' 43. 5880 3. 86 3. 5870 0 5 10 15 20 25 30 3540 Reduction, percent Figure 30 Influence of Isothermal Reductions at 22000 F on the Lattice Parameter of As -RoldBrSckTh Reduction of 40 Percent Required One Reheat During Rolling.

3. 589 0 Air Cooled 3. 5880 - 3. 5870 3. 58,60 3. 5850 Water Quenched 3. 5840 3. 5830 1625 1725 1825 1925 2025 2125 2225 Reheat Temperature, 0EF Figure 31 -Influence of Cooling Rate from Reheat Temperature on Lattice Parameter. Specimens Solution Treated at 2200'F, 1 Hour, Water Quenched, Reheated to Indicated Reheat Temperature for 1/2 Hour, andA Cooled as Indiated.4,n

3. 5890 Air Goole4 3. 5880 3. 587C0 -- - - _ __- _ _- -'3. 5860 __'4 ns dt Compoind pi3. 5850 Oil Q enched Water QL enched 3. 5840 - - I _ _- - - _ _- - urnace Coced 3. 5830 __- — ~- - 0.1 I1. Cooling Rate at 1IZOOF,'F/Sec. Figure 32 - Influence of Cooling Rate from 2025'F on the Lattice Parameter. After Solution Treating at 2200'F, 1 Hour, Water Quenched, Specimens were Reheated to 20Z5'F, 1/2 Hour, and Cooled as Indicated. 70 (a) LT.este at 1200OF ______25 (b) Tested at 1500'F ____ 005 _ _ 0 ( 40 I 0 160 10 00 2010 80 00 20 Fia4oln)epraue FFnlRlln eprtr,' 0 - 21o at2,~0-F + 576 a indcatedtempeatur 5) ~ ~ ~ ~ ~ 0-156a 20" 5% tidctd eprt 1600 1800 200-0% a220020' 00' 1600'an 1800 20 20

600 ~ —zzz_ 50. 000 psi 42 5,O0O psi I20001jF 12001F 100 _ _ - _ - 100 _ _ - _ - - _ _.0~~~~~~~~~~~~~~~ 1 0 I I U~~~~~~~~~~ 1600 1800 2000 2200 1600 1800 2000 2200 FinalRollng Teperaure, F Fial RolingTemperature, *F O-25%/ at 2200-F + 15% at indicated temperature 0I- 15% at 2200-F + 25% at indicated temperature A- 10% each at 2200', 2000', 1800', and 1600'F'X- 25% at 2000"F + 15% at indicated temnecrature 4- 25% at 1800'F + 15% at indicated temperature U-40% isothermally at indicated temperature 0- 15% isothermally at indicated temperature Figure 34 -Effect of Rolling Temperature on Creep Rate at 1200'F for Various Amounts and Methods of Deformation. 100 ___100 8, 000 psi 15, 000 psi 1500IF1500'F _ 0.0~~~~~~~~~~~~~~1 1600 1800 2000 2200 1600 1800 2000 2200 Fi;nal RolngTmprtue F inal PRollingy Tempera%.-ture, *F1

/.I"-,I.... 10- ~ ~ ~ ~ ~,..4' 4~~~~~~~~~~~~~~~~~~~~~~~~3 e a so.',.,.:.,.. A,,; - ~..~,. J~t': ~.:.:.~A. ~: ~,.~.' & ~' /'';,.:,',..... -.:.'i~......~~'.,~ A''"'A'. ~~~~~~~~~~~~~~~~~. ~ 0 -, ~. xl00 xl000 xI00x10 R olled 25 percent at 2200'F plus 15 percent at 20000F R olled 25 percent at 2200'F plus 15pecn at10 F I~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~~~~ I..-.. 4..'A 7/i V 4 ~~~~~~~~~~~~~O I 4;~~~~~~~~~~' ~',/'~....',.~,~ ~ ~ ~ ~:.:-,-,~.*:, *'.'.,.4'~~~,. /~~~~~~~~~~~~~~~~ ~.>.4......g~~..;.~.,......~~'~. D, ~ ~ ~ ~ ~ ~ ~ ~ I X100 Xl000 Xl00 Xl000 1Rolled 10 percent eahat -22000, 20000 1800 aecnd at6000FF Rolled 2-5 percent at 22000~F plus 15 percent at 1600~F F i g u r e 3 6...,-:,, r -.,':'.- E f f e c t o f N o n - I s o t h e r m a l R e d u c t i o n s o t h e M i c r oe s. B r S k w s S T, 1 H u a W ater Quenched a d t n R d as Id.-n Cc A.) t" — ~~' ~,' ~,...","~' "' "' "'...... ": -,:-.[- i,;.,.:/~,..,.,.........'-'../'..~1 >..-,.,.. \ ~~~~~~~~~~~~~~~~~ 441 ~ ~ ~ ~ ~ ~ ~ ~,',q'.~. "'""i.~,',..., *f',..:..~'.]-.';..", X100~~~~~~~~~~~~~~~~~~~~~~~~~~:,.;.,''t':'..'.4,J~'' %.~'~~. ~'......,.,..."0 eren eac at~' 220'",~ 200:0.'\: 18 0 and 10',F R.ol.e. 25 percen at 2....plus,5,... Pigure 36 - Effect of Non-Isothermal Reductions on the Microstructures. Bar Stock. was.,,,,; So.l.u.t.,ion. ~.. ~..~.... Water Quenched and then Rolled as Indicated. (Electrolytically Etched in 10 Percent,

- " ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~j..,,~~ ~~~:~' ".,/ 10~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ xlo lo 100 xl000 X0 R olled 2 5 percent at 2200'F plus 15 percent at 2000'F Rolled 25 percent at 2200'F plus1pecnat80F (1125 hours) (1 175 hours ~oe?,,).' N~~~~ IT~~~~~~~~~~~~~~~~~~~~~~~,~~~~~~~~~~~~~~~~~~~~~~~~x.,, X100 X1000 X100 X1000 Rolled 10 percent each at 22000, 20000, 18000, and 1600~F Rolled 25 percent at 2000~F plus 15 percent at 1600~F (1155 hours) (1178 hours) Figure 37 - Microstructures after Creep Testing for 1000 Hours at 1200' with a Stress of 25,0. Testing, Bar Stock was Solution Treated at 22000F 1 Hour, Water Quenched and R. (Electrolytically Etched in 10 Percent Chromic Acid. )

60 2 (a) Tested at 1200'F (b) Tesed at100z 55 2 100 hr~00 h 5n "-4 ~45 0'0 4-j 40 35 O O 1900 2100 2100 2200 1800 1900 2000 1020 Final Rolling Temperature,'F Final Rolling Temperaue,0 o - Heat to 1800'F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%, hold 2 hrs, reheat to 180F Repeat cycle 3 more times. 0- Heat to 20000F, 1/2 hr, roll 5%, cool to 1500'F,, roll 5%, hold 2 hrs, reheat to 2000F Repeat cycle 3 more times. X- Heat to 2200'F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%, hold 2 hrs, reheat to 2200F Repeat cycle 3 more times. Figure 38") - Effect of Cyclic Rolling on the 100 and 1000-Hour Rupture Strengths at 12000 n'50F

Testing Temperature Rolling Conditions 12 00 0 1 500 0 * 0 Heat to 1800 0F, 1/2 hr, roll 5%, cool to 15000F, roll 5%, hold 2 hrs, reheat to 1800'F. Repeat cycle 3 more times. A A ~Heat to 20000F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%, hold 2. hrs, reheat to 20000F. Repeat cycle 3 more times. 0. 01 U 0 ~~~~~Heat to 2200 0F, 1/2 hr, roll 5%, cool 0 ~~~~~~~~~~to 15000F, roll 5%, hold 2 hrs, reheat to 22000F. Repeat cycle 3 more times..4-, U 0. 001 0. 0001 25, 000 psi 0. 00004 ______ _ _ _ _ _ _ _ _ _ _ _____ 1800 2000 2200

14~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0. KYK\,Y / - xl00 x1000 xl00x10 Heated to 2200'F, 1/2 hr rolled 5%, cooled to 15000F, Heated to 20000'F 1/2 hr, rolld5 oldt 50F rolled 5%6 held 2 hrs, reheated to 2200 0F. Repeated rolled 5%, held 2 hrs, rcheatedt 000.Rpae cycle three more times, three more times. CL.~~~~~7 1A r 400* Pe,7~ V S~~~~~~~~~~~~~~C XlOO X1000 Heat to 18000F, 1/2 hr, rolled 5%, cooled to 1500 0F, rolled 5%6, held 2 hrs, reheated to 18000F. Repeated cycle three more times. Figure 40- Effect of Cyclic Rolling on the Microstructures. Bar Stock was Solution Treated at200P1Hor Water Quenched and Rolled as Indicated. (Electrolytically Etched in 10 Percent Chroii Ai.

100.. 80 60... 1200~F 40 1 20 1500"F 0 8 Reduction Rolling Temperature,'F 1600 1800 2000 2200 6 15 ) 0, + 25 L0 A 65 A 10 20 40 60 80 100 200 400 600 8001000 2000 Rupture Time, hours Figure 41 - Influence of Rolling Temperature and Amount of Reduction on the Response to Heat Treatment. After Rolling as Indicated, Bars were Solution-Treated at 2200'F, 1 Hour, Water Quenched, and then Rupture Tested at 1200' or 1500'F. 100 80 60 12004 40 20 10 Reduction Rolling Temperature,'F 8 Percent 1800' 2000' 2200' 25 0 A 0 40. A. 4 25180 at 2200~F + 15% at 1800'F.- X 10 20 40 60 80 0 Z 400 160 8d0 1(00 z000 Rupture Time, hours Figure 42 - Influence of Percent Reduction and Rolling Temperature on Response to Heat Treatment. After Rolling As Indicated, Bars were Solution Treated at 22000F, 1 Hour, Water Quenched, Plus 14800F, 24 Hours, Air Cooled, and then Rupture Tested at 1200' or 1500~F.

100 80 60 As A 1200~F.Reduction Rolling Temperature,'F 8 Percent 1600 1800 2000 2200 lll l l 6 40 ~.. 65 v 2o511 at 2200~F + 1.5.. at 600~.F + ~~~~~~~~~~~~~~4 -_ ~ ~ ~ ~ ~ ~ ~ 0 2 10 R eduction Rolling Temperature, 2F000, 1800, 3 and 1600 ~F-' 10 20 40 60 80 100 200 400 Percent 1600 1800 2000 2000 Rupture Time, hours Figure 43 -Influence of Rolling Temrperature and Amount of Reduction on the Response to Heat Treatment. After Rolling as Indicated, Bars were Solution Treated at 2050'F, 2 Hours, Water Quenched,'~ 15 x O ~ 0 40 O I......... 65 V z 5 d at 1200~ + 10at 60. ~~~~~~~~~~~~~~~~~101 SONS 10 each at to 22000~, /2000 hr, 1800, ol andto 1600F, roll 5%, hold hr. 4(Repeat cycle 3 more times), A- IHeat to tF, l/2 hr. roll 5%, cool| to 1500'F, roll 5%6, hold 2 -hro. 3 (Repeat cycle 3 more times). l 10 20 40 60 80 100 200 400 600 8001000 2000 Rupture Time, hours Figure 43 - Influence of Rolling Temperature and Amount of Reduction on the Response to Heat Treatment. After Rolling as Indicated, Bars were Solution Treated at 2050~F, 2 Hours, Water Quenched, and then Rupture Tested at 1200~ or 1500~F. i00F BO......... lZOO'F' —r —-— I'"'-' j 10............. ~ - Heat to 1800'F, 1/2 hr, roll 5~/o0, cool....... 4O to 1500~F, roll 5%l, hold k hrs, ~.~ ~(Repeat cycle 3 more times), ~ - Heat to Z000~F, 1/2 hr. roll 5~0, cool to 1500~F. roll 5%J, hold 2 hrs. (Repeat cycle 3 more times). Ar - Heat to ZZ00~F, 1/2 hr, roll 5%j, cool to 1500~FE, roll 5%1, hold 2 -hrs. ( Rep~eat cycle 3 more times) 10 Z0 40 60 -80 100 200 400 )00 800 1000 —- Z000 Rupture Time, hours Figure 44 - Influence o~ Rolling Temperature and Amount of Reduction on the Response to Heat Treatnlent.. After Rolling as Indicated, Bars were Solution Treated at 2050'F, Z Hours, Water Quenched, Hot-Cold Worked 15% at 1200~F, and then Rupture Tested at 1200' or 1500~F.

100 Hour Rupture Streng:ths 50 4. o 180 1000 Hour Rupture n-: thds. 45 40 0 1800 A 2 000 0 2100 Ad 2200 Temperatures on the 100 and 1000-Hour Rupture Strengths at 1200'F.

25 100 Hour Ru -ture S'ren.:ths 20 0 l 10 1000 Hour Ru'?ture Stren: ~ths 15 c 0 10 20 30 40 50 60 7 Percent Reduction at Indicated Temperature Code Temperature of Reduction('F) * 1600 0 1800 A 2000 0 2100 2200 Figure 46 - Effect of Amount of Isothermal Reduction in Open Passes at Various Temperatures on the 100 and 1000-Hour Rupture Strengths at 1500~F.

______ 50 55 A sA So - 1804200 220 240 260 200 30 050~ 0.~ I 40 30 35. 180 200 220 240 260 280 300 180 200 220 240 260 280 300 Brinell Hardness Brinell Hardness X- Rolled at 2200 ~F A- Rolled at 2000'F x- Rolled at 2200 ~F A- Rolled at 2000~ F B- Rolled at 2100~F O- Rolled at 1800~F I- Rolled at 21J?2,F O- Rolled at 1800F 0- Rolled at 16000F 0- Rolled at 16000F A- 25 percent at 2200~F plus 15 percent at 20000F A- 25 percent at 2200~F plus 15 percent at 2000~F 0- 25 percent at 2200~F plus 15 percent at 1800 ~F 0- 25 percent at 2200 ~F plus 15 percent at 18000F +- 15 percent at 22000F plus 25 percent at 1800~F +- 15 percent at 22000F plus 25 percent at 1800~F A- 25 percent at 2200~F plus 15 percent at 1600~F A- 25 percent at 22000F plus 15 percent at 1600~F v- 10 percent each at 2200~, 20002, 1800 ~, and 16000F Q- 10 percent each at 2200~, 200C0, 18001, and 16000F V7- 25 percent at 20000F plus 15 percent at 1600~F 7- 25 percent at 2000~F plus 15 percent at 1600~F o- 25 percent at 1800~F plus 15 percent at 1600~F 4- 25 percent at 1800F plus 15 percent at 1600F d- Heat to 18000F, 1/2 hr, roll 5%, cool to 1500~F, roll 5%, Q- Heat to 18000F, 1/2 hr, roll 5%, cool to 15000F, roll 5%, hold 2 hrs, reheat to 18000F. Repeat cycle 4 times. hold 2 hrs, reheat to 18000F. Repeat cycle 4 times. 69- Heat to 20000F, 1/2 hr, roll 5%, cool to 1500~F, roll 5%o, i5- Heat to 2000~F, 1/2 hr, roll 5%, cool to 1500~F, roll 5%, hold 2 hrs, reheat to 2000~F. Repeat cycle 4 times. hold 2 hrs, reheat to 2000F. Repeat cycle 4 times. E- Heat to 22000F, 1/2 hr, roll 5%, cool to 15000F, roll 5%, *- Heat to 22000F, 1/2 hr, roll 5%, coolto 1500F, roll 5%, hold 2 hrs, reheat to 22000F. Repeat cycle 4 times. hold 2 hrs, reheat to 22000F. Repeat cycle 4 times. Figure 47 - Correlation of the 100-Hour Rupture Strength at 1200~F with Figure 48 - Correlation of the 1000-Hour Rupture Strength at 12000F with the As-Rolled Brinell Hardness. the As-Rolled Brinell Hardness.

x 100 100 x en A,, L I I 0 x~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 10 A a) 5d o) S 10 180 200 220 240 260 2z0 300 180 200 220 240 260 280 300 Brinell Hardness Brinell Hardness X- Rolled at 2200'F A- Rolled at 2000'F X- Rolled at 2200'F A- Rolled at 2000F U- Rolled at 2100"F 0- Rolled at 1800'F U-Rolled at 2100F 0- Rolled at 1800"F *- Rolled at 1600'F 0- Rolled at 1600"F A- 25 p. rcent at 2200'F plus 15 percent at 2000'F A- 25 percent at 2200'F plus 15 percent at 2000lF 0- 25 percent at 2200'F plus 15 percent at 1800'F 0- 25 percent at 2200'F plus 15 percent at 1800IF +- 15 percent at 2200'F plus 25 percent at 1800'F +- 15 percent at 2200'F plus 25 percint at 1800"F A- 25 percent at 2200'F plus 15 percent at 1600'F A- 25 percent at 2200'F plus 15 percent at 1600IF i- 10 percent each at 2200', 2000', 1800', and 1600'F 0- 10 percent each at 2200', 2000( 1800% and 1600"F V- 25 percent at 2000'F plus 15 percent at 1600'F V- 25 percent at 2000'F plus 15 percent at 16000F 0- 25 percent at l800'F plus 15 percent at 1600'F 0- 25 percent at 1800'F plus 15 percent at I6000F Q- Heat to 1800'F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%6, - Heat to 1800'F, 1/2 hr, roll 5%, cool to l500"F, roll 5%, hold 2 hrs, reheat to 1800'F. Repeat cycle 4 times hold 2 hrs, reheat to 1800'F. Repeat cycle 4 times. I- Heat tp 2000'F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%, 0- Heat to 2000'F, 1/2 hr, roll 5%, cool to 1500W, roll 5%, hold 2 hrs. reheat to 2000'F. Repeat cycle 4 times. hold 2 hrs, reheat to 2000F. Repeat cycle 4 times. C- Heat to 2200'F, 1/2 hr, roll 5%6, cool to 1500WF, roll 5o, b- Heat to 2200WF, 1/2 hr, roll 5%, cool to 1500., roll 5%, hold 2 hrs, reheat to 2200WF. Repeat cycle 4 times. hold 2 hrs. reheat to 2200 W. Repeat cycle 4 times. Figure 49 - Correlation of Mininum Creep Rate for an Initial Stress of Figure 50 - Correlation of Minimum Creep Rate in 1000 Hours for an 50,000 psi at 1200WF with the As-Rolled Brinell Hardness. Initial Stress of 25,000 psi at 1200W with the As-Rolled Brinell Hardness.

25 20 0 0 1 0 - 15 A___ _ 4 54 4)'4 180 200 220 240 260 280 300 80 200 0 20 280 3 Brinell Hardness Brinell Hardness X- Rolled at 2200'F A - Rolled at 2000~F X- Rolled at 20002F I- Rolled at 2100WF 0- Rolled at 1800~F X- Rolled at 22000F - Rolled at 18000F R0- Rolled at 2100F - Rolled at 1800"F ~leat FF *- Rolled at 1600W *- Rolled at 16005 F *- Rolled at 1600F 0- 25 percent at 22000F plus 15 percent at 2000~F A- 25 percent at 2200Z F plus 15 percent at 2000~F 0- 25 percent at 2200~F plus 15 percent at 1800'F 0- 25 percent at 2200F plus 15 percent at 1800F +- 15 percent at 2200'F plus 25 percent at 18000F - 15 percent at 2200F plus 25 percent at 1800(F - 25percent at 2200F plus 15 plus 15 at 21 600*F A- 25 percent at 2200'F plus 15 percent at 1600(F 0- 10 percent each at 2200~, 20000, 1800~, and 1600*F -10 percent each at 2200, 2,1600F V- 25 percent at 2000'F plus 15 percent at 1600~F 1- 10 percent each at 2200 2000 1 800, and 1600'F O- 25 percent at 1800'F plus 15 percent at 1600'F V- 25 percent at 2000'F plus 15 percent at 1600(F Q- Heat to 1800'F, 1/2 hr,. roll 5%, cool to 1500'F, roll 5%, O- 25 percent at 1800'F plus 15 percent at 1600(F hold 2 hrs, reheat to 1800'F. Repeat cycle 4 times Q- Heat to 1800'F, 1/2 hr, roll 5%, cool to 1500F, roll 5%, hold 2 hrs, reheat to hold 2 hrs, reheat to 1800F. Repeat cycle 4 times. e- Heat tp 2000WF, 1/2 hr, roll 5%, cool to 1500'F, roll 5%, ~- Heat to 2000~F, 1/2 hr, roll 5%, cool to 1500~F, roll 5%, hold 2 hrs, reheat to 20000F. Repeat cycle 4 times. hold 2 hrs, reheat to 2000WF. Repeat cycle 4 times. 0- Heat to 22000F, 1/2 hr, roll 5%/0, cool to 1500~F, roll 5%, L- Heat to 2200'F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%, hold 2 hrs, reheat to 2200~F. Repeat cycle 4 times, hold 2 hrs, reheat to 2000'F. Repeat cycle 4 times. Figure 51 - Correlation of the 100-Hour Rupture Strengths at 15000F with Figure 52 - Correlations of the 1000-Hour Rupture Strength at 15000F with the As-Rolled Brinell Hardness. the As-Rolled Brinell Hardness.

100 1 10 x~~~ 10 W4~~~~~~~~~~~~~~~~~~~~~~~ (d ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ _ _ _0,'R F, ~~~~180 zoo 220 2402b2830 Brinell Hardnes 180 200 220 240 260 Z80 300 X - Rolled at 2200'F A olda 0 Brinell Hardness R-oRolledtat 1600'F A- 25 percent at 2200'F plus 15 pecnL t20' X-Rolled at 2200'F A- Rolled at 2000'1F 0- 25 percent at 2200'F pilus 1 5 -Pereta 0 URolled at 2,100'F 0- Rolled at 1800F 4- 15 percent at 2200'F -plus 25 pecnat10F *-Rolled at 1500'F A-25 percent at 2200'F -)ilus 1 5 pecnta 10' 10 percent each at 2200', 200 ~-25 percent at 22-00'F plus l. percent at 2000'F 7-25 percent at 2000'F p1wlus, 1 5 rcnat10F 0- 25 -percent at 2200'F plus 1 5 percent at 1800'F ~-25 percent at i800'F plus 1 5pecnat10F 4-15 percent at 2~_OO'F Plus 25 jpercent at 1800'F 0 Heat to 1800'F, 1/2 hr, roll 5,colt15 Frl5, A - 25 percent at 22,0C'F plus 15 percent at 1600'F hold 2 hrs, reheat to 1800'F.Reatcle4ims GI- 10 percent each at 2 200', 2000", 1800', and 1600'F ~ Heat to 2000'F, 1/2 hr, roll 5%,co o10',rl % 7- 25 percent at 2000'F plus 15 percent at 1600'F hold 2 hrs, reheat to 2000'F.Reatcle4ims 25 percent at 1300'F Plus 15 percent at 1600'F 1 % hl Hea tors0', 1/2ea hr, rol % colt01,rol % ~-Heat to 2000'F, 1/2 hr, roll 5%6, cool to 1500'F, roll5,hd2hreeato20F Rpatcle4ims hold 2 hrs, reheat to 2000'F. Repeat cycle 4 times. ~-Heat tu 2200'F, 1/2 hr, roll 5%, cool to 1500'F, roll 5%6, hold 2 hrs, reheat to 2000'F. Repeat cycle 4 times. Figure 54- Correlation of Miidniurrm CreepRaei100Husfra Initial Stress of 8, 000 psi at w BPrinell Hardness. Fip'ure 53 - Correlation of Minimum Creep,, Rate for an Initial Stress of 15,O000 p-si at 1500'F with the As-Rolled Briniell Hardness.

300 280 W 260 "0 240 22 200 180 -,, 3Heat1 1 \4%7 ( 25 0 o N"~~~~~~~~~~~~~~~ II IdOOJ 504i o 5 45 —o ] 1000 1200 1400 1600 1800 2000 2200 Temperature of 15-Percent Reduction,'F Heat 30276 (ref. 1) This Investigation 1000 Hour Rupture Stren-,th A X 100 Hour Rupture SLre-rngth 0 O 1000 Hour Rupture Elongation A X 100 Hour Rupture Elongation 0 O O Brinell Hardness X 0 O 2200'F Solution Treat before Reduction 2050~F Solution Treat before Reduction Figure 55. Comparison of 1200~F Rupture Strengths and Ru;?ture Elongation, and Brinell Hardrxess after 15-Percent reduction at Various Temperatures for This Investigation ad Another Heat of the Same Alloy (Heat 30276, ref. 1).

to 5 15005F --— 4 _ — 5 01 - 5 100 Hou Percent Reduction at Indicated Tern- -erature Code Temnerature of Reduction (0F) o 1800 A 2000 o 2100) 2 <200 Figure 56 - Effect of Amount of Isothermal Reduction in Open Passes at Various Temperatures on the Change in the 100 and 1000-Hour Rupture Strengths at 1200~ and 15001F.

UNIVERSITY OF MICHIGAN 111111II051 I028l1 1127l11 1121116 8 3 9015 02827 2568