Corrosion of Stainless Steel and Aluminum Alloys in Fuming Nitric Acid by Beth Cook Hillig approved by John S. Amneus Project MX- 794 USAF Contract W33-038-ac-14222 Willow Run Research Center Engineering Research Institute University of Michigan UMM-77. February 1951 /R\<^\nn~n=^r paTh n This document contains information affecting the national defense of fP~c. n Q X He United States within the meaning of the Espionage Act, 50 U.S. G., \fl T ti1 31 And 32. Its transmission or the revelation of its contents in any JX:.._ U bU~~l vU~~ UluLJammaer to an mauthoized person is prohibited by law

CONFIDENTIAL WXILL OW RUN RESEARCH CENTER -UNIVERSITY OF MICHIGAN UMM-77 TABLE OF CONTENTS Section Page I. Introduction and Summary 1 II. Experimental 5 A. Alloys Investigated 3 B. Testing Procedure 3 C. Experimental Results 4 1. Calculations 4 2. Physical Appearance of Test Samples 4 3. Comparison of Alloys Tested 6 a. Steels 6 b. Aluminum Alloys 7 III. Discussion of Literature Data 8 A. Selection of Data 8 B. Effect of Heat Treatment and Welding on Corrosion 8 Resistance C. Effect of Acid Composition on Corrosion Resistance 10 D. Effect of Temperature on Corrosion Resistance 11 E. Recommended Alloys 12 Appendix 13 Bibliography 14 Figures 15 Tables 21 CONFIDENTIAL

CONFIDENTIAL WILLOWI RUN RESEARCH CENTER-UNIVERSITY OF MICHIGAN UMM-77 LIST OF FIGURES Page 1. Series I. Corrosion of Stainless Steels. Continuous Exposure to 6 1/2% RFNA. 15 2. Series I. Corrosion of Aluminum Alloys. Continuous Exposure to 6 1/2% RFNA. 15 3. Series II. Corrosion of Stainless Steels. Continuous Exposure to both Liquid and Fumes of 6 1/2% RFNA. 16 4. Series II. Corrosion of Aluminum Alloys. Continuous Exposure to both Liquid and Fumes of 6 1/2% RFNA. 16 5. Series III. Corrosion of Stainless Steels. Alternate Exposure to 6 1/2% RFNA and Dilute HNO3. 17 6. Series III. Corrosion of Aluminum Alloys. Alternate Exposure to 6 1/2% RFNA and Dilute HN03. 17 7. Series IV. Corrosion of Stainless Steels. Alternate Exposure to 6 1/2% RFNA and to Air after Water Rinse. 18 8. Series IV. Corrosion of Aluminum Alloys. Alternate Exposure to 6 1/2% RFNA and to Air after Water Rinse. 18 9. Series V. Corrosion of Stainless Steels. Alternate Exposure to 6 1/2% RFNA and to Air (without Rinsing or Drying). 19 10. Series V. Corrosion of Aluminum Alloys. Alternate Exposure to 6 1/2% RFNA and to Air (without Rinsing or Drying). 19 11. Steel and Aluminum Samples after Ninety-Day Corrosion Tests. 20 ii CONFIDENTIAL

CONFIDENTIAL WILLOW RUN RESEARCH CENTER- UNIVERSITY OF MICHIGAN -UMM-77 LIST OF TABLES Page I. Average Corrosion Rates in ipm of Stainless Steel and Aluminum Alloys in RFNA. 21 II. Average Corrosion Rates of Type 304 Steel in WFNA. 22 III. Average Corrosion Rates of Type 304 Steel in WFNA. 23 IV. Average Corrosion Rates of Type 304 Steel in WFNA. 24 V. Average Corrosion Rates of Type 304 Steel in RFNA. 26 VI. Average Corrosion Rates of Types 309 and 310 Steel in WFNA. 27 VII. Average Corrosion Rates of Type 347 Steel in WFNA. 28 VIII. Average Corrosion Rates of Type 347 Steel in WFNA. 29 IX. Average Corrosion Rates of Type 347 Steel in RFNA. 30 X. Average Corrosion Rates of Type 430 Steel in RFNA. 31 XI. Average Corrosion Rates of Stainless Steels in RFNA at Elevated Temperature. 32 XII. Average Corrosion Rates of 2S. Aluminum in WFNA. 33 XIII. Average Corrosion Rates of 2S-0 Aluminum in WFNA. 34 XIV. Average Corrosion Rates of 2S-0 Aluminum in FRNA. 35 XV. Average Corrosion Rates of 2S Aluminum in RFNA. 36 XVI. Average Corrosion Rates of 3S Aluminum in RFNA. 37 XVII. Average Corrosion Rates of Alclad 24S-T Aluminum Alloy in WFNA. 38 XVIII. Average Corrosion Rates of Alclad 24S-T Aluminum Alloy in RFNA. 39 XIX. Average Corrosion Rates of Aluminum Alloys in Fuming Nitric Acid. 41 XX. Average Corrosion Rates of Aluminum Alloys in RFNA at Elevated Temperature. 42 iii CONFIDENTIAL

CONFIDENTIAL WILLOW RUN RESEARCH CENTER - UNIVERSITY OF MICHIGAN UMM-77 I. INTRODUCTION AND SUMMARY This investigation was prompted by corrosion problems which arose in rocket motor test installations during the course of propulsion research under Army Air Forces Contract W33-038-ac-14222. A laboratory study of the corrosion of various stainless steel and aluminum alloys by fuming nitric acid has been carried out, together with a critical survey of the literature on this subject. The degree to which actual field experience will substantiate the results of laboratory tests is always questionable; however, the conclusions summarized here should provide at least a starting point for the selection of alloys for fuming nitric acid service. Laboratory corrosion tests of three months duration were conducted on types 303 (cold-rolled), 316 (cold-rolled), and 347 (forged billet) stainless steels, and on types 2S-0, 3S-0, 17S-T, and 24S-T aluminum alloys. In five series of tests corrosion rates were determined for each alloy under the following conditions, designed to duplicate these encountered at the rocket test facility: continuous exposure to commercial 6 1/2% red fuming nitric acid (RFNA); continuous exposure to both RFNA and its vapor; alternate exposure to RFNA and to dilute acid; alternate exposure to RFNA and to the atmosphere; alternate exposure to RFNA and to the atmosphere after water rinsing. The results of these experiments, correlated with the best literature data, lead to the following conclusions: 1. Aluminum alloys are definitely superior to stainless steels for long-term continuous exposure or for intermittent exposure at ambient temperature to fuming nitric acid and its vapor. The corrosion rates of aluminum alloys in fuming nitric acid remain fairly constant with time, while those for stainless steels increase. 2. The aluminum alloys 2S-0, 3S-0, 17S-T, 24S-T, Alclad 24S-T, 53S, 61S-T, and 75S-T are practically equivalent in their resistance to fuming nitric acids. 3. Aluminum alloys should never be exposed to dilute nitric acid for any appreciable time, e.g., by draining of fuming nitric acid and leaving in water or air without very thorough rinsing, since aluminum is readily attacked by dilute acid. CONFIDENTIAL

CONFIDENTIAL WILLOW RUN RESEARCH CENTER -UNIVERSITY OF MICHIGAN UMM-77 4. Types 304 and 347 are the most resistant of the stainless steels to fuming nitric acid. Low carbon 304 is recommended as the better choice in view of current restrictions on columbium needed for 347. 5. Stainless steel for which only intermittent contact with fuming nitric acid is required should be drained and rinsed between exposures. 6. The corrosion resistance of aluminum alloys is practically independent of heat treatment before or after welding. Unwelded stainless steel in contact with fuming nitric acid should be from hot-rolled, fully annealed stock, while welded samples should be heat-treated at 20000 F. and rapidly cooled for maximum corrosion resistance. 7. Red fuming nitric acid is more corrosive than white fuming nitric acid to stainless steel and aluminum alloys. Traces of chlorides, salts of heavy metals, and sulfuric acid promote the attack on these alloys. CONFIDENTIAL

WILLOWf RUN RESEARCH CENTER-UNIVERSITY OF MICHIGAN UMM-77 II. EXPERIMENTAL A. Alloys Investigated Stainless steel types 304, 316 and 347, and aluminum alloys 2S-0, 3S-0, 17S-T, and 24S-T were studied. The 347 sample was cut from a forged billet, while the 303 and 316 were from cold-rolled stock. Samples of 303 and 316 and of 17S-T and 24S-T were cut from round bar stock and given a smooth machine finish. Samples of 2S-0 and 3S-0 were cut from 1/8" sheet. None of the samples received further surface treatment. Commercial 6 1/2% RFNA was used in all tests. B. Testing Procedures Five series of tests were conducted for a period of three months. Series I and II simulated conditions in drums or other containers totally or partially filled with PFNA. The cycles in Series III, IV, and V were designed to show whether parts of the rocket motor facility which must be exposed intermittently to RFNA should be drained and left in air or drained, rinsed and left in air or water during the periods between exposures to acid. Series I: The samples were immersed continuously in PFNA. Series II: Approximately half the surface area of each sample was immersed in RFNA, the remainder being exposed to the acid vapor. Series III: The samples were immersed in RFNA during the first phase of each cycle. After determining weight loss, the samples were immersed momentarily in RFNA, dipped quickly into water, and all placed together but not touching each other, in 100 ml. water (actually dilute acid because of incomplete rinsing of samples). The samples were reweighed at the end of each phase. Eleven cycles involving phase times of one to ten days were completed. Series IV: The samples were immersed in RFNA during the first phase of each cycle. After weighing, the samples were redipped in EFNA, incompletely rinsed by a quick dip in water, and left in air. Eleven cycles were completed. 3

WILLOVW RUN RESEARCH CENTER-UNIVERSITY OF MICHIGAN UMM-77 shiny appearance for about four days. At the end of twelve days all three samples were covered with a shiny black film. After thirty-three days, the surfaces of 303 and 347 were becoming slightly rough, while 316 was already very rough. After 50 days the weight loss of the 316 sample amounted to nearly 50%, and it could not be dried without rubbing large particles from the surface; hence the test on this sample was discontinued. At the end of three months, the 303 sample had lost 30% of its original weight, and the surface showed very serious attack. After one day in RFNA the aluminum samples bore vari-colored tarnishes, the colors changing and darkening with time. After three months the 2S-0 and 3S-0 were a dull grey, while the 17S-T and 24S-T were dull black. Slight pitting was apparent. Series II: After twelve days exposure to RFNA and its vapor, each steel sample had darkened slightly and uniformly, and a week later all were black. The surfaces were noticeably rough after thirty-six days, the roughness increasing thereafter and becoming particularly bad in the case of the 516 sample. The aluminum samples bore vari-colored tarnishes after one day. The colors deepened and at some weighing periods were darker on that part of a sample immersed in the acid. At the end of three months, the 2S-0, and 3S-0 were dull grey, the 17S-T and 24S-T dull black. During the first few days of the tests, white crystals assumed to be Al(N03)3 * 9H2'0 formed on the vapor-exposed surface of each sample. Slight pitting occurred. No preferential attack at liquid-vapor interfaces was apparent on either the steel or aluminum samples. Series III: The steel samples were still clean after one cycle, but started to darken after the second exposure to RFNA and were completely black after the fourth exposure to the acid. All had rough surfaces after thirty-six days, the 316 sample deteriorating most rapidly so that the test on it was discontinued after seventy-five days. As in all the other series, the aluminum samples were tarnished after one day in RFNA and heavily tarnished after three months. During exposure to dilute acid in one of the later cycles, 4 —

WILLOVW RUN RESEARCH CENTER -UNIVERSITY OF MICHIGAN UMM-77 Series V: The samples were immersed in RFNA during the first phase of each cycle. After weighing, they were redipped in RFNA and left in air. They were reweighed at the end of this phase. Eleven cycles were completed. At the start of the tests the samples, measuring 1/2" x 1/2" x 1/8", were washed with acetone, dried, and weighed. One sample of each alloy was included in each series. During the first ten days of testing, individual samples were immersed continuously or at intervals, as described above, in 7-8 ml. PFNA contained in 30 ml. test tubes. The test tubes were closed with rubber stoppers protected by aluminum foil. Thereafter, all samples of a given test series were immersed together, continuously or at intervals, in 75 ml. RFNA in a 250 ml. glass-stoppered Erlenmeyer flask, taking care that the samples did not touch each other. The acid was changed at approximately weekly intervals. No effort was made to control the temperature, ambient temperature varying in the range 50~ - 100~ F. and averaging about 80~ F. Weight losses of the samples in Series I and II were determined at intervals of one to ten days. Each sample was rinsed quickly and thoroughly with water and dried and rubbed with a chamois before weighing. C. Experimental Results 1. Calculations Average corrosion rates for the three months period were calculated in inches per month (ipm) for the samples in Series I and II. Average corrosion rates were calculated for each phase of the testing cycle for samples in Series III-V. These rates are given in Table I. Corrosion rates in ipm calculated for the intervals between weighings (i.e., the phase times in Series III-V) are plotted for the five series in Figures 1-10. 2. Physical Appearance of Test Samples. Series I: The sample of 516 steel had started to blacken after one day in RFNA, while 303 and 347 retained their original 5

WILLOWV RUN RESEARCH CENTER - UNIVERSITY OF MICHIGAN UMM-77 the 3S-0 sample was deeply but smoothly corroded at one corner (see Figure 11), suggesting that electrochemical action had resulted from its accidently touching another sample. Series IV: The appearance of both the steel and aluminum samples was essentially the same as in Series III. The 316 sample was removed from the test after seventy-five days. In many cases, the tarnish on the aluminum samples lightened during exposure to air and darkened again in acid. Series V: The appearance of the steel samples was similar to that in Series III. The 316 sample was removed from the test after seventy-five days. The aluminum samples were tarnished after exposures to acid, but in general regained silvery satin finishes during exposure to air. Crystals like those observed in Series II formed on the surfaces of the 2S-0 and 3S-0 samples during exposure to air. The appearance of all the steel and aluminum samples at the beginning and at the end of the test period is shown in Figure 11. 3. Comparison of Alloys Tested. a. Steels. The 303, 316, and 347 stainless steel samples showed no significant differences in corrosion resistance for about the first two weeks. Thereafter until the conclusion of three months testing, the 347 samples were definitely Superior to the other two types under all test conditions. Samples of each steel exhibited considerably smaller corrosion rates when exposed simultaneously to both liquid RFNA and its vapor (Series II) than when exposed to liquid RFNA alone. There was a general tendency in both the oontinuous exposure and the cyclic tests for corrosion rates in PFNA and its vapor to increase with time, this tendency being least pronounced with the 347 and most serious with the 316 samples. The corrosion rates of the steel samples during the RFNA phases of the cycling tests were of the same order of magnitude as those of samples exposed continuously to PFNA. Corrosion rates in the alternate phases, i.e., water after rinsing in Series III, air after rinsing in Series IV, and air ------------------- ~~6 —--------

WILLOW RUN RESEARCH CENTER -UNIVERSITY OF MICHIGAN IUM-77 without rinsing in Series V, were much smaller than in RFNA. The cycle RFNA-rinse-water of Series III was least corrosive for the 303 and 316 samples, while for the 347 samples the RFNA-air cycle of Series V was just as good as RFNA-rinsewater. b. Aluminum Alloys. The 2S-0, 3S-0, 17S-T, and 24S-T alloys investigated were considerably superior to the stainless steels in their resistance to RFNA and its vapor. The corrosion rates of samples exposed simultaneously to both liquid and vapor were higher by 4-6% than those of samples exposed to liquid RFNA only. Differences among the four alloys in the various tests were small, the 17S-T being slightly more resistant to liquid RFNA than the others while the 24S-T suffered the greatest attack. When the aluminum alloy samples were taken from RFNA and left in air or rinsed and left in water or air, their corrosion rates increased on the average about five-fold. This was to be expected, since it is well known that aluminum is attacked by dilute nitric acid. 7

MWILLOW RUN RESEARCH CENTER -UNIVERSITY OF MICHIGAN UMM-77 III. DISCUSSION OF LITERATURE DATA A. Selection of Data Published data concerning the corrosion resistance of steel and aluminum alloys to red and white fuming nitric acids are scattered and incomplete. Those tabulated in Tables II to XX in the Appendix of this report have been critically selected from the chemical literature, from classified reports available to us, and from private communications from several steel and aluminum companies. Comparison of data from different sources is difficult because of the large number of factors which influence experimentally determined corrosion rates. One of the most important considerations in the evaluation of data was the length of test periods. Tests covering a few hours or a few days may be necessary and valid in certain cases, e.g., in tests conducted at high temperatures. However, the present investigation has shown that in the case of the corrosion of stainless steels by RFNA at ambient temperature, the corrosion rates suddenly start to climb after about two weeks exposure and increase with time thereafter up to ninety days. Furthermore, tests of 32 months duration conducted by the Allegheny Ludlum Steel Corporation revealed several definite breaks in the corrosion rate vs. time curves for types 304 and 347 stainless steel1. For this reason corrosion rates for steels in RFNA calculated from the results of e.g. forty-eight hour tests at ambient temperature have significance for that period only and cannot be used validly for predictions about longer periods. Other factors which must be considered in interpreting corrosion data include heat treatment of the sample, presence of welds and treatment after welding, stresses in the sample, preparation of the test surface, ratio of edge length to surface area of the sample, presence of impurities in the corroding agent, and the temperature at which the tests are conducted. B. Effect of Heat Treatment and Welding on Corrosion Resistance There seems to be almost general agreement that both welded and non-welded stainless steels, except perhaps for the columbium stabilized type 347, require "proper" heat treatment in order to exhibit maximum corrosion resistance to fuming nitric acid. Apparently this conviction is based mainly on practical experience, since it is not borne out in some cases by the meager data available from laboratory studies. The 8

WILLOW RUN RESEARCH CENTER-UNIVERSITY OF MICHIGAN UMIM-77 following results summarize various laboratory tests lasting from three to eight months: Corrosion rates in 95% and 99% WFNA of type 430 steel which, after welding, had been heated. two hours at 1425~0 F., furnace-cooled. to 1200~ F., and then air cooled, were lower by 3-35% than those of welded, non-heat treated 430. (Sands2, Table X.) Corrosion rates in 99% WFNA of welded samples of type 304 steel which had been heated fifteen minutes at 1925~0F. and air cooled were lower by 15% than those of welded, non-heat treated samples, but in 93% WFNA this heat treatment was of no advantage. (Sands2, Table II.) Welded, non-heat treated type 304 steel did not exhibit significantly higher corrosion rates than non-welded, annealed (conditions unspecified) 304 in either RFNA or WFNA at ambient temperature or at 120~ F. However, the average corrosion rates of welded type 304 which had been held at 1650~ F. for twenty-four hours and air cooled were about six times higher than those of welded, non-annealed 304 in RENA and WFNA at ambient temperature, and about twice as high at 120~ F. (M. W. Kellogg Company3, Tables IV and V). Several other stabilizing treatments at 16500 for shorter periods with various methods of cooling were no more successful in reducing corrosion (CarnegieIllinois Steel Corporation4). Heating type 347 steel for 15 minutes at 1925~ F. and air cooling resulted in an average 7% increase in corrosion rates in 95-99% WFNA at 1300, as compared with welded, non-heat treated 347 (Sands2, Table VII). The corrosion rate of welded, non-annealed type 347 in RFNA at ambient. temperature was slightly higher than that of annealed (conditions unspecified) 347 containing no weld. However, the rates for welded, non-annealed samples were lower in WFNA at ambient temperature and in RFNA and WFNA at 120 F. than the rates for non-welded samples (M. W. Kellogg Company3, Tables VIII and IX). The M. W. Kellogg Company3 found that cold-working of stainless steel caused a serious increase in corrosion rates in fuming nitric acid, particularly if some heat was required as in bending stainless steel pipe. In such a case, solution treatment for fifteen minutes at 2000~ F. was recommended. 9'-I

WILLOW RUN RESEARCH CENTER-UNIVERSITY OF MICHIGAN lUMM-77 On the basis of these scattered data and the experience of the Carnegie-Illinois Steel Corporation4, heat treatment of stainless steels after welding appears more likely to cause a decrease rather than an increase in corrosion resistance, unless the heat treating is done at about 2000~ F., followed by rapid cooling. In the latter case the chances of increasing corrosion resistance seem to be considerably better. Unwelded stainless steel in contact with fuming nitric acid should be from hot-rolled, fully annealed stock. According to Sands2, corrosion of heat-treated steel samples is largely confined to the edges. He suggests that this may account for some variation between plant and laboratory experience, since drums and welded containers do not have edges exposed to attack. Excessive corrosion at edges and corners was not observed in the present tests on types 303 and 316 steel cut from cold-rolled bar stock, or on type 347 cut from a forged billet. Aluminum alloys, welded or non-welded, appear not to require heat treatment before exposure to fuming nitric acid. Heat treatment is not particularly detrimental to corrosion resistance, however. These conclusions follow from the data for 2S, 3S, and Alclad 24S-T alloys in Tables XII-XIV and XVI-XVIII. Localized corrosion around welds in aluminum alloys has not been observed. C. Effect of Acid Composition on Corrosion Resistance Few data have been found in the literature which will permit reliable direct comparison of the corrosive action of 6.5% RFNA, 16% RFNA, and WFNA on stainless steel and aluminum alloys. Kaplan and Andrus5 state that corrosion rates are not significantly different in these acids, although other sources indicate, without furnishing data, that WFNA is less corrosive than the red fuming acids. The M. W. Kellogg Company3 reports the following: For types 504 and 347 steel, WFNA and RFNA (of unspecified compositions) are about equally corrosive at ambient temperature (Tables IV and V, VIII and IX). At 120~ F. corrosion rates of these steels are about two to four times as high in RFNA as in WFNA, depending on the presence of welds and heat treatment of the samples. For 2S-0 and Alclad 24S-T aluminum, corrosion rates in RFNA are about 1.5 times those in WFNA at ambient temperature. At 120~ F. the. rates in EFNA are usually slightly smaller than those in WFNA (Tables XIII and XIV, XVII and XVIII). 10

WILLOW RUN RESEARCH CENTER -UNIVERSITY OF MICHIGAN UMM-77 Sands2 shows that stainless steels (Tables II, III, VI, VII, and X) are generally more susceptible to attack by 97-99% WFNA than by 93-95% WFNA, while aluminum (Tables XII and XVI) is slightly more resistant to attack by the more concentrated acid. It is also apparent from these tables that the vapor phase of WFNA is generally more corrosive to both stainless and aluminum alloys than is the liquid phase. In the present investigation, the aluminum alloys were more severely attacked by the vapor of RFNA than by the liquid acid; however the liquid RFNA was more corrosive than the vapor to the stainless steel samples. Little is known concerning the accelerating or decelerating effects of impurities in fuming nitric acids on corrosion rates. According to Seligman and Williams6, up to 0.05% chloride in the acid has no effect on the corrosion of aluminum, while traces of sulfuric acid promote the attack. Chlorides and salts of heavy metals in fuming nitric acids have been mentioned as harmful to aluminum7 as well as to stainless steel, while traces of sulfuric acid also increase the corrosion of stainless steel4. Kaplan and Andrus found in 3-7 hour tests, however, that at 250-3000 F. both aluminum and stainless steel are attacked much less severely by an 88-12 mixture of WFNA and fuming sulfuric acid ("mixed acid") than by RFNA,8. D. Effect of Temperature on Corrosion Resistance. The corrosion rates of both stainless steel and aluminum alloys in fuming nitric acid increase with increasing temperature, but few quantitative data concerning the temperature effect are available. Results of the M. W. Kellogg Company3, summarized in Tables IV and V, VIII and IX, indicate that increasing the temperature from ambient to 120~ F. causes the corrosion rates of types 304 and 347 steel to increase about twice as much in RFNA as in WFNA. On the other hand, the corrosion rates of 2S-0 and Alclad 24S-T aluminum increase about equally in RFNA and WFNA for the same temperature increase (Tables XIII and XIV, XVII and XVIII). Corrosion rates for type 304 stainless steel and 2S and 3S aluminum alloys kept in 93% and 99% WFNA for ninety days at 90~, 110~ and 130~ F. are given in Tables III, XII and XVI as reported by Sands. The rates show an average two-fold increase for each 100 rise in temperature over this range. If this rate of increase were assumed to hold with RFNA up to e.g. 270~ F., corrosion rates of the order of 10-100 ipm might be expected at this higher temperature. However, 11

WILLOWN RUN RESEARCH CENTER -UNIVERSITY OF MICHIGAN UMM-77 rates amounting to only 0.06-0.6 ipm were obtained by Kaplan and Andrus5,8 for 304 and other stainless and aluminum alloys from tests in RFNA lasting three to seven hours at 250-300~ F. (Table XI). Moreover, there is evidence that at this temperature corrosion is most severe during the first few hours of exposure, so that longer test periods would show lower average corrosion rates: Kaplan and Andrus calculated rates of 0.1 and 0.06 ipm for 304 stainless steel from tests of 3.3 and 6.6 hours respectively. E. Recommended Alloys The quantitative experimental data which are collected in the Appendix of this report, together with actual field experience reported by various handlers of fuming nitric acids; e.g., E. I. duPont de Nemours and Company9, indicate that types 304 and 347 are the most resistant of the stainless steels to these acids. Low carbon 304 (carbon 0.03% maximum instead of 0.08% maximum) has been reported4 to be more corrosion resistant than ordinary type 304 and is recommended4,7 as the best choice for fuming nitric acid service, particularly in view of current restrictions on the columbium needed for 347. Aluminum alloys in general are more satisfactory for service in fuming nitric acid than are the stainless steels. According to data available, there is little choice among the types 2S-0, 3S-0, 17S-T, 24S-T, Alclad 24S-T, 53S, 61S-T, and 75S-T as far as corrosion resistance is concerned. 12

WILLOW RUN RESEARCH CENTER -UNIVERSITY OF MICHIGAN UMM-77 ADDENDUM - JUIE, 1951 No reliable exhaustive study of corrosion by fuming nitric acid has been carried out. The conclusions reached in this report were based on our own simple laboratory tests and on the best published data available to us in January, 1951. These conclusions are not altered by the following additional information brought to our attention since that time: 1. M. W. Kellogg Company Report SPD 121, Appendix E, March 19, 1948. 2. Progress Reports 1 through 4, dated May 31, August 21, October 6, and December 11, 1950, by the Ohio State Research Foundation, Columbus, Ohio, on "Investigation of Materials for Handling Fuming Nitric Acid". It is suggested that Dr. M. G. Fontana, supervisor of this project, be contacted for possible further information. In contrast to aluminum alloys, the corrosion resistance of stainless steels to fuming nitric acid is greatly dependent on welding and heat treatment processes. It is possible that some suitably heat-treated stainless steels may be nearly as corrosion resistant as aluminum alloys, but the fact that the heat treatment is critical cannot be over emphasized. As stated in this report, scattered laboratory tests have shown that white fuming nitric acid is less corrosive than red fuming nitric acid. However, experience at our rocket test facility indicates the reverse to be the case. We are now duplicating with the white acid the laboratory tests which we conducted with the red acid. The possibility of galvanic corrosion resulting from the coupling of dissimilar materials must always be given serious consideration. For instance, recent experience at our rocket test facility shows that aluminum immersed in fuming nitric acid in contact with certain stainless steels is rapidly corroded. 13

WILLOW RUN RESEARCH CENTER- UNIVERSITY OF MICHIGAN UMM1- 77 BIBLIOGRAPHY 1. Allegheny Ludlum Steel Corporation, Brackinridge, Pa. Private Communication from Mr. J. B. Henry, Jr. 2. Sands, G. A. "Transportation and Storage of Strong Nitric Acid", Industrial and Engineering Chemistry, Vol. 40, p. 1937, 1948. 3. M. W. Kellogg Company, Special Projects Department, Jersey City, New Jersey. Preliminary Experimental Studies of Liquid Fuel Systems, Final Report, SPD 236, May 20, 1949. 4. Carnegie-Illinois Steel Corporation, Stainless Division —Sales Department, Chicago, Illinois. Private conversation with Mr. J. Markley and Mr. E. W. Reid. 5. Kaplan, N. and R. J. Andrus. "Corrosion of Metals in Red Fuming Nitric Acid and in Mixed Acid", Industrial and Engineering Chemistry, Vol. 40, p. 1946, 1948. 6. Seligman, R. and P. J. Williams. "The Action of HNO on Aluminum", Journal of the Society of Chemical Industry, Vol. 35, p. 665, 1916. 7. Aluminum Company of America, New Kensington, Pa. Private communication from Mr. H. W. Fritts. 8. Kaplan, N. and R. J. Andrus. Corrosion, Bearing Surface Materials, and Sealing Studies with Red Fuming Nitric Acid and with Mixed Acid, Jet Propulsion Laboratory, California Institute of Technology, GALCIT Project No. 1, Report No. 23, May 4, 1944. 9. E. I. du Pont de Nemours and Company, Wilmington, Delaware. Nitric Acid, Tank Car Unloading and Storage, Technical Service Bulletin. 10. Bethlehem Steel Company, Shipbuilding Division. Development of Prototype System for Shipboard Storage and Handling of Liquid Propellants for Guided Missiles, Report No. S-2015-12, June 15, 1949. 14

WILLOW RUN RESEARCH CENTER UNIVERSITY OF MICHIGAN UMM-77.040 303 ------ I' I 316 I. 030. \ I o!' i ~ / %%% - -- --- -- ~,,-,-. 0 10 20 30 40 50 60 70 80 90 TOTAL TIME, DAYS FIG. 1 SERIES I: CORROSION OF STAINLESS STEELS Continuous exposure to 6.5% RFNA.0008 i.0006 FIG. 2 SERIES1:CORROSIONOFALUMINMALL =-I I II II 1 3 S —---!7i'i z i!.4 i^ _ \ _ __ __/ _.0002. TOTAL TIME, DAYS FIG. 2 SERIES I: CORROSION OF ALUMINUM ALLOYS Continuous exposure to 6.5% RFNA

WILLOW RUN RESEARCH CENTER-UNIVERSITY OF MICHIGAN UMM-77.016 - /\ 303 ---------- 316 ---- \.012 347 \ I \ Lr: /3 S 1 z.0086 - 0x.004 o /L7I 0 10 20 30 40 50 60 70 80 90.0016 V S-C"'... 1 S-T —._. h I _ _ _,. _ _ ____ / - 0 10 20 30 40 50 60 70 80 90 TOTAL TIME, DAYS FIG- 3 SERIES II: CORROSION OF STALUMINUMLESS STEELS Continuous exposure to both liquid and fumes of 6.5% R F N A Z.000816 3 S-O.000412 24S-T FIG. 4 SERIES 11: CORROSION OF ALUMINUM ALLOYS Continuous exposure to both liquid and fumes of 6.5% RFNA 16

WILLOW RUN RESEARCH CENTER-UNIVERSITY OF MICHIGAN UMM-77 024' ~ 303 — i I -', 3476 —-- -1-1- 347 0- I.018 La __' o - \I i\ i1/.i. —- - -- I-I —---- _- _.0064 TOTAL TIME, DAYS FIG. 5 SERIES III: CORROSION OF STAINLESS STEELS Alternate exposure to 6.5% R F N A and dilute HN03 (Higher rates in RFNA).004 - 3 S-0 —----- / 17 S-T —-----------.003- -- - - - - 24 S-T —- ---- z.002 ---- 0 ___ 001, 0 0 10 20 30 40 50 60 70 80 90 TOTAL TIME, DAYS FIG. 6 SERIES II1: CORROSION OF ALUMINUM ALLOYS Alternate exposure to 6.5% R F N A and dilute HNO3 (Higher rates in dilute acid.) 17

WILLOW RUN RESEARCH CENTER UNIVERSITY OF MICHIGAN UMM-77 I.040 I 303 ---- 347 I _ I I I I I I I I I I I I s020-A" I 0.01c 0- - - I__v.,^- -.../ - 0 10 20 30 40 50 60 70 80 90 TOTAL TIME, DAYS FIG. 7 SERIES IV: CORROSION OF STAINLESS STEELS Alternate exposure to 6.5 R F N A and to air after water rinse (Higher rates in R F NA.).0016 -- - 2 S-0 — --- 3 S-0 —---- 24 S-T —---— *.00120 I \ I / FIG. 8 SERIES IV: CORROSION OF ALUMINUM ALLOYS | after water rinse. (_Higher rates in air) l -------------------- 18 —---------------—'I.0004 v,.. 0 10 20 30 40 50 60 70 80 90 TOTAL TIME, DAYS FIG. 8 SERIES IV: CORROSION OF ALUMISNUM ALLOYS Alternate exposure to 6.5% R F N A and to air after water rinse. (Higher rates in air) ~~~.0004~ ~18 I - - 2 0 05 0 089

WILLOW RUN RESEARCH CENTER- UNIVERSITY OF MICHIGAN UMM-77 303. —------- 316 ---- -.030 I!" e/I I C- I- W I A- 1I.oo \,' I 0 10 20 30 40 50 60 70 80 90 TOTAL TIME, DAYS FIG. 9 SERIES V: CORROSION OF STAINLESS STEELS Alternate exposure to 6.5% R F NA and to air without rinsing or drying. (Higher rates in RFNA) 3 S-0 —--- 17 ST- - ~.003~24 —-- -- -- -- -- -- -- -- - 24 S-T -----------.0024 ^ k-A_ z.0016 0 A g T I \i I 0 10 20 30 40 50 60 70 80 90 FIG. 10 SERIES V: CORROSION OF ALUMINUM ALLOYS Alternate exposure to 6.5% RFNA and to air without rinsing or drying. (Higher rates in air) 19

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TABLE I: AVERAGE CORROSION RATES IN IPM OF STAINLESS STEEL AND ALUMINUM ALLOYS IN RFNA RFNA: Comm. 6 1/2% Temperature: Ambient Test Period: 90 days Stainless Steels Aluminum Alloys Z Series 5|303 316 347 2S-0 3S-0 17S-T 24S-T I RFNA liq..00455.01280*.0oo156..00026 027. 00015.00026 II RFNA liq..00113.00461**.00036.00031.00028.00025.00030 and vap. O_____ ______ III RFNA.00276.00505**.00106.00009.0.00001.00015 (eleven (rinse) o X cycles) Water.00002.00043**.00001.00070.00085.00073.00081 IV RFNA.00395.01490**.00139.00020.00016.00017.00027 (eleven (rinse) cycles) Air.00002.ooo00076**.00001.ooo60.00077 00.00058 V RFNA.00398.01480.00109.00015.00013.00019.00020 (eleven cycles) Air.00001.000 63. 00005.00075.00081.00084.00082 *After 50 days. **After 75 days total. M I. > @~~~~~~~~~~~~~~~~~~~

TABLE II: AVERAGE CORROSION RATES OF TYPE 304 STEEL IN WFNA O Temp. Time, Corrosion Steel %WFNA F. Days Rate, ipm Reference z 304, welded, annealed 95, liquid 80-90 0-120.00009x* Allegheny (conditions 120-240.00003 Ludlum (1) unspecified) 240-375.00001 375-495.00015 495-615.oooo6 0 615-960.00001 0-960.00005 o ro 3504, welded., annealed 95, vapor 80-90 0-255. 00004* (conditions 255-420.0001 - unspecified) 420-510.0008 510-960.00003 0-960.00012 304, welded 93, liquid 90 90.00005 Sands (2) It It.93, vapor "t.00003 304, welded, heat treated* 93, liquid " ".00005,..,. I.. | 93, vapor ".00003 | 304, welded 99, liquid 90 90.00220 " 0 "t "| 99, vapor " ".00397 304, welded, heat treated* 99, liquid " I".00191 t_" " " " 99, vapor " ".005333 * 10 minutes at 1925~ F., air cooled. ** Calculated from graphs of total penetration vs. time..., -.. z

TABLE III: AVERAGE CORROSION PATES OF TYPE 504 STEEL IN w1FNA Temp. Time, Corrosion 0 Steel % WFTHA F. Days Pate, ipm Reference o04, welded., heat treated.* 95, liquid. 90 90.00005 Sands (2) ITr T ~ IT TI II TI.~110 ".00017 o "I TI", IT I I I I 150 I.00070 504, weld.ed., heat treated* 95, vapor 90 90.00005 " i ru^~ ~~I TI TI II II II 110 I.00019 ITI TI II~ I IT I ~ 150 II.00045 504, welded., heat treated.* 99, liquid. 90 90.00191 II,TI TI TI IT~ II, i110 I.0055339 II i t I IT IT II 3150 I".oo00410 504, welded., heat treated.* 99, vapor 90 90.0033555 " II IT TI r~TI I "~Io T It.00555 i IT tI II IT III II 150 ".00485 *10 minutes at 19250 F., air cooled. 0

TABLE IV: AVERAGE CORROSION RATES OF TYPE 504 STEEL IN WFNA Temp. Time, Corrosion0 Steel Acid- ~ F. Days Bate, ipm* Reference 504, annealed WFTA ambient 65-128.00001 M. W. Kellogg (5) C (conditions 128-189.00001Z unspecified) 189-217.00004 217-256.00008 256-527.00010(/) 504, welded WIFNA ambient 65-156.00001 1t 156-217.00002 217-255.00004 255-526.00007 n^ ~504, welded, annealed WFNTA ambient 45-77.00002 P. (24 hours at 16500 F. 77-108.00015 air cooled) 108-170.00018 t 170-200.000 55 200-217.00049 ____~~e________________________ 217-248.00055 _____3_ 504, annealed WTNA 120 25-50.00018 (conditions 50-79.00028 rinsp cified) 79-110.00047 110-141.00065M 141-181.00067 504, welded WvNA 120 25-50.00025 50-79.00055 79-110.00042 110-141.00057 141-181.00080 _ _ _ * * 111 i 1-1~~~~~~~~~

TABLE IV: AVERAGE CORROSION RATES OF TYPE 304 STEEL IN WFNA (CONT'D) r Temp. Time, Corrosion Steel Acid ~F. Days Rate, ipm* Reference 304, welded, annealed WFNA 120 23-50.00025 M. W. Kellogg (3) Z (24 hours at 1650~ F. 50-79.00038 air cooled) 79-110.00057 79-110.00057 110-141.00104 ( 141-181.00150 * Calculated from graphs of corrosion rates in inches per year (ipy) vs. time. o 0 k~. t1 C) z I o

TABLE V: AVERAGE CORROSION RATES OF'TYPE 304 STEEL IN\ RFNA 0 Temp. Time, Corrosion Steel Acid. F. Days Rate, ipm** Reference 504, annealed RENA Ambient 54-157.00001 M. W. Kellogg (5) Z (conditions.- 003 unspecified) 157-165.00005 165-196.oooo00006 196-225.00010 C) 225-500.00012 504, welded RFNA Ambient 54-157.00001 157-165.00005 165-196.00004 196-225.00006 t^ro~ ~225-247.00009I 504, welded, annealed RFNA Ambient 46-128.00001 tT *(24 hours at 16500 F. 128-157.00005 air cooled.) 157-190.00022 190-217.00049 C 217-240.000ooo54 504, annealed RENA 120 25-50.0015 3I (conditions 50-140.0010 unspecified) 140-182.0016 182-242.0010 504, welded. RENA 120 25-50.0020 I 0 50-140.0015 l 140-182.0017 182-242.0014 504, welded, annealed RENA 120 24-50.0040 I See above 5 0-7.0050 0 Caculatedfrom graphs of corrosion rates in 0py vs. time. Z1 _____^'ACalc-ulated7 from graphs of corrosion rates in ipy vs. time.

TABLE VI: AVERAGE CORROSION RATES OF TYPES 309 AND 310 STEEL IN WFNA Temp. Time, Corrosion Steel % WFNA O~F. Days Rate, ipm Reference 309, flash weld 95, liquid 130 90.00006 Sands (2) 95, vapor ".00105 Z 309, flash weld 97, liquid 130 90.0027 it ft it |97, vapor t.o046 310, flash weld 95, liquid 130 90.00008 95, vapor ".00024 310, flash weld 97, liquid 130 90.0008 " " " 97, vapor excessive | 310, welded, annealed 95, liquid 80-90 0-180.0000| Allegheny (conditions 180-375.00000 Ludlum (1) unspecified) 375-960.00001 0-960.oooo4 310, welded, annealed 95, vapor 80-90 0-255.00002 * (conditions 255-375.0003 unspecified) 375-510.0005 510-960.0002 0-960.00025 1 _ *Calculated from graphs of total penetration vs. time. a) z

TABLE VII: AVERAGE CORROSION RATES OF TYPE 347 STEEL TN WFNAr Temp. Time, Corrosion Steel %WFNA OF. Days Rate, ipm Reference 347, flash weld 95, liquid. 130 go90.00004 Sands(2), heat treated.* I " t.00004 347, flash weld 95, vapor 130 90.00186 ft, heat treated.* " " " ".00200 347, flash weld 97, liquid 130 go90.0027, i heat treated.* ".0051 347, flash weld 97, vapor 130 90.0053 0 heat treated.* f" ".0059 347, flash weld 99, liquid 130 90.0050 " co " ", heat treated.*.0053 347, flash weld 99, vapor 130 90.0059 - Y heat treated.* t" " t" ".0065 347 welded. 95, liquid 80-90 0-90.00004** Allegheny 90-135.00008 Lud-lum (1) 135-375.00002 375-465.00022 465-675.00007 675-960.ooo00000oo 0-960.oooo00005 347, welded 95, vapor 80-90 0-255.00000** " 0 255-540.0004 540-960.oool ______________________________~0-960.00018______ 0 *15 min. at 19250 F., air cooled. **Calculated from graphs of total penetration vs. time.

TABLE VIII: AVERAGE CORROSION RATES OF TYPE 347 STEEL IN WFNA Temp. Time, Corrosion Steel Acid OF. | Days Rate, ipm* Reference 347, annealed WFNA ambient 23-54.00007 M. W. Kellogg(3 (conditions 54-86.00014 unspecified) 86-118.00017 118-149.00028 149-234.00047 347, welded WFNA ambient 31-60.00004 " t 60-86.00010 0 86-118.00017 118-149.00028 0 o ___ ____ ____ 149-244.0004o 2 347, annealed WFNA 120 23-49.00032 - (conditions 49-78.00040 unspecified) 78-110.00044 110-141.00087 141-182.00113 182-244.00152 1 347, welded WFNA 120 23-49.00015 " 49-78 00018 78-110.00022 110-141.00033 141-182.00045 *Calculated from graphs of corrosion rates in ipy vs. time. 0......

TABLE IX: AVERAGE CORROSION BATES OF TYPE 547 STEEL IN RFNA Temp. Time, Corrosion Steel Acid OF. Days Rate, ipm Reference 547, annealed RFNA amb'ient 28-100.00010* M. W. Kellogg (5) (conditions 100-152.00017 z unspecified) 152-160.00025 160-245.00050 547, welded RFNA ambient 28-88.00026* ii 88-150.00052 150-244.00054 547, annealed RFNA 120 25-49.0015 * (conditions 49-79.0015 unspecified) 79-140.0012 ^ ~140-181.0015 3 181-242.0014 - 547, welded. RFNA 120 25-79.0010 " ft 79-140.0009 140-181.0010 181-242.0012 z 547 BFNA ambient 29.00025 Bethlehem Steel (10) * Calculated from graphs of corrosion rates in ipy vs. time. H 0 0 0 z

0 Z TABLE X: AVERAGE CORROSION RATES OF TYPE 430 STEEL IN RFNA Temp. Time Corrosion Steel %WFNA OF. Days Rate, ipm Reference 430, flash weld., 95, liquid 130 9o.00036 Sands (2) | ft "t ", heat treated " ",.000355 430, flash weld 95, vapor 130 90.00075 tf f t ".,."heat treated " ",. 00067 430, flash weld 99, liquid 130 90.0068 " "t " f"1, heat treated " " " ".0044 430, flash weld 99, vapor 130 90.0063, heat treated ".0053 z I I..-,

TABLE XI: AVERAGE CORROSION RATES OF STAINLESS STEELS IN RFNA AT ELEVATED TEMPERATURE Temp. Time, Corrosion Steel | Acid O~F. Hours Rate, ipm Reference 304 6.5% RFNA 250-300 3.3 0.1 Kaplan and. Z Andrus (5,8) o04 ", 6.6 0.06 " r 316 " 7 0.2 410, heat treated " 7 0.4 0 0 (conditions unspecified) ___ _ 414 7 0.3 r7" otr 416 " " 7 0.25 420 16% RFNA 7 0.3 " 440 "7 0.2 446 7 0.25 " 0 2 0 0

TABLE XII: AVERAGE CORROSION RATES OF 2S ALUMTNUM IN WFNA _________________________ ___________________________ ____________0 Temp. Time, Corrosion 0 Aluminum % WFNA F. Days Rate, ipm Referencei 2S, welded., heat treated * 95, liquid 90 90 oool.00016 Sands (2) Z t i t it t 110.00088 ft ft ftft ftf13 0 o o o.000 61 2S, welded, heat treated * 95, vapor 90 90.00008 it it t ft If ft 110 II.00009 t II fIt If i150 l.00014 2S, welded, heat treated* 99, liquid 90 90.00002 110.,00008 WI " r " r "~ "~ "~f f 150.00055 ft~~~~~~~~~~r 2S, welded, heat treated* 99, vapor 90 90.00010 Z ft " " ""110.00025 f f130.00025C 2S, welded 95, liquid 90 90.00001 It If 95, vapor.00008 2S, welded, heat treated* 95, liquid.00001 If It ft 95, vapor.00007 2S, welded 99, liquid 90 90.00002 0 ty II 99, vapor ".00007 2S, welded, heat treated* 99, liquid ".00001 II f t ft 99, vapor I I.00010 * 5 hours at 9400 F., air cooled

C TABLE XIII: AVERAGE CORROSION RATES OF 2S-0 ALUMINUM IN WFNA Temp. Time Corrosion Aluminum Acid. F. Days Rate, ipm* Reference 2S-0, annealed WFNA ambient 31-49.00016 M. W. Kellogg Z (conditions 49-149.00025 (3) unspecified) 149-183.00020 28-0, welded. WFNA ambient 52-62.00027 62-123.00031 123-153.00028 o 153-189.00036 2S-0, annealed WFNA 120 24-49.00052 " C W^- ~ (conditions 49-181.00035 unspecified) 3 2S-0, welded WFNA 120 24-49.00058 " 49-80.00043 C 80-110.00038 110o-141.00041 141-181.00045 * Calculated from graphs of corrosion rates in ipy vs. time. H 0 -i1

TABLE XIV: AVERAGE CORROSION RATES OF 2S-0 ALUMINUM IN RFNA Temp. Time, Corrosion Aluminum Acid OF. Days Rate, ipm* Reference Z 2S-0 annealed RFNA ambient 28-59.00031 M. W. Kellogg (conditions 59-88.00034 (3) 0 unspecified) 88-149.00036 149-183.00030 2S-0, welded RFNA ambient 53-186.00027 " 2S-0, annealed RFNA 120 24-50.00051 0 k ^ (conditions 50-79.00042 unspecified) 79-139.00040 - 139-180.00044 2S-0, welded RFNA 120 24-48.00067 48-140.00051 140-180.00054 * Calculated from graphs of corrosion rates in ipy vs. time. 0 Ch) z

TABLE XV: AVERAGE CORROSION RATES OF 2S ALUMINUM IN RFNA r Temp. Time, Corrosion Aluminum Acid O~F. Days Rate, ipm Reference 2S-0 RFNA ambient 2.00001 Bethlehem Z 4.00005 Steel (10) 6.00004 8.00005 10.00008 12 oooo84 12.00004 14.00002 16.00002 2S, as machined RFNA ambient 15.00007 " | ^iwm~~~~~~ W l |29.00004 ~~~~~~~~~~~~~~~~~~ONh I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2S, polished RFNA ambient 15.00007 29.00003 29.00002 28, fine tool finish RFNA * ambient 18.00009 "f 2S, fine tool finish RFNA ** ambient 10.00012 " 2S, cut from weld RFNA ambient 28.00003" 2S, adjacent to weld RFNA ambient 28.00005 * Contaminated Acid From Stainless Steel Drum. ** Acid Contained 4% Water.

TABLE XVI: AVERAGE CORROSION RATES OF 5S ALUTRINIUM ALLOY IN WFNA F Temp. Time, Corrosion Aluminum % WFNA OF. Days Rate, ipm Reference 5S, welded, heat treated.* 93, liquid 90 90.00017 Sands (2) It It It ft ft ft 110 "t.00092 "t t 150.00152 3S, welded, heat treated * 935, vapor 90 90.00008 C, It ft ft It f9t ft 110.00012 "130 I".00136 3, welded, heat treated * 99, liquid 90 90.00002 110.0003312 130.00185 3S, welded, heat treated * 99, vapor 90 90.00016 " ft it 110.00051 t It t150 t.00oo89 3S, welded. 95, liquid 90 o90.00001 3S, welded, heat treated * 95, liquidvapor 90.00001" I I If95, vapor I " ".00010 3S, welded 99, liquid 90 90.00002 99, vapor ".00016 09 3S, welded, heat treated* 99, liquid..00001 99, vapor.00015 *5 hours at 9400 F., air cooled 0

TABLE XVII: AVERAGE CORROSION RATES OF ALCLAD 24S-T ALUMITNUM ALLOY IN WFNA Temp. Time, Corrosion Aluminum Acid. 0F. Days Rate, ipm* Reference Alclad., 24S-T, annealed. WFNA ambient 45-76.00017 M. W. Kellogg(I5) Z (conditions 76-108.00012: unspecified.) 108-158.00010 138-198.00008 198-250.00010 Alclad, 24S-T, welded WFNA ambient 18-45.00021 45-77.00024 77-107.00018 107-167.00014 w^~~~ I I I I ~~~~~~~~167-226.00016 I cb r I I,., I I i I ~~~~~~~~~~~~~~~~~I~I M Alclad 24S-T, welded., annealed WFNA ambient 51-61.00026 (solution treated 15 min. 61-89.00050 at 9200 F, water quenched) 89-124.00054 124-152.00050 Z 152-186.00052 Alclad 24S-T, annealed. WFNA 120 25-49.00082 " 49-79.00074 79-182.00081 Alclad 24S-T, welded, annealed WFNA 120 25-79.00087' 7 (solution treated 15 min. 79-110.00095 at 9200 F., water quenched) 110-140.00112 _________________________________140-182.00125 ________ __ * Calculated from graphs of corrosion rates in ipy vs. time.

h^ TABLE XVIII: AVERAGE CORROSION RATES OF ALCLAD 24S-T ALUMINUM ALLOY IN RPFNA Temp. Time, Corrosion Aluminum Acid _ F. Days Pate, ipm Reference r Alclad 24s-T annealed PRFNA ambient 46-109.00051 M. W. Kellogg() (conditions 109-158.00019 unspecified) 159-199.00015 199-250 ooo.00018 Alclad 24S-T, welded PFNA ambient 77-106.00052 " o106-188.00025 0 188-217.00021 w Alclad 24S-T, welded, annealed RFNA ambient 55-59.00042 (solution treated 15 min. 59-88.00049 at 9200 F., water quenched) 88-119.00041 P 119-149.00038 149-185.00044 *Calculated from graphs of corrosion rates in ipy vs. time. CI) H 0 0

TABLE XVIII: AVERAGE CORROSION RATES OF ALCLAD 24S-T ALUMINUM ALLOY IN RFNA (CONT'D) E Temp. Time, Corrosion 0 o I i~ Aluminum Acid F. Days Rate, ipm* Reference __ Alclad 24S-T, annealed RFNA 120 25-49.00080 M. W. Kellogg(5) (conditions. 49-78.00061 unspecified) 78-111.00058 111-142.000ooo65 142-181.00072 Alclad 24S-T, welded RFNA 120 25-49.000o65 " 0 49-78 ooo.00042 78-110.00045 0 110-142,00050 0 142-181.00055 Alclad 24S-T, welded, annealed RFNA 120 25-48.00078 " (solution treated 15 min. 48-78.00059 at 9200 F., water quenched) 78-110.00062 110-181.00067 *Calculated from graphs of corrosion rates In ipy vs. time. H C 0

TABLE XIX: AVERAGE CORROSION RATES OF ALUMTNUM ALLOYS IN FUMING NITRIC ACID O Temp. Time Corrosion Aluminum Acid OF. Days Rate, ipm Reference 3S-O RFNA ambient 28.00007 Bethlehem Steel (10) z 14S-T6 RFNA ambient 50-84.00025* M. W. Kellogg (3) 84-105.00029 105-164.00036 164-196.00038 1 43 RFNA ambient 33-64.00039*, 64-93.00043 93-126.00047.,t-F~ ~ I~ l 1 ~126-147.00051 H LII1147-174.00047 43 WFNA ambient 30-89.00045* " 89-120.00059 C 120-200.00069 Z 53S RFNA ambient 21.00009 Bethlehem Steel (10) 61S-T RFNA ambient 27.00001 " 653-T RFNA ambient 28.00003 75S-T RFNA ambient 28.00002 * Calculated from graphs of corrosion rates in ipy vs. time. )..... _.. &~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

C TABLE XX: AVERAGE CORROSION RATES OF ALUMINUM ALLOYS INT RFNA AT ELEVATED TEMPERATURE Temp. Time, Corrosion z Aluminum % RFNA OF. Hours Rate, 1pm Reference 17S-T 16 250-500 7 0.6 Kaplan and Andrus (5,8) C,) 17S-T 6.5 1 7 0.5 1 24~-T 6.5 "W 6 0.5 " 0 C,) ru~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ P'71 0 cC 2; r C3 w:

CONFIDENTIAL WILLOW RUN RESEARCH CENTER-UNIVERSITY OF MICHIGAN UMM-77 DISTRIBUTION Distribution of this report is made in accordance with ANAF-GM Mailing List No. 14, dated 15 January 1951, to include Part A, Part B and Part C. CONFIDENTIAL