Corrosion and mechanical behavior of ion implanted bearing steels for improved fretting behavior

Abstract

Ion implantation of AISI 52100 and 1070 steels was conducted in order to improve the corrosion, wear and ultimately the fretting behavior of the steels. Implantations consisted of 1 x 1017 Ta+ cm-2, 3 x 1017 Ti+ cm-2 + 1.5 x 1017 C+ cm-2, and 3.1 x 1017 Ti+ cm-2 + 1.55 x 1017 N+2 cm-2. All implantations were successful in improving the corrosion resistance. On average, the peak anodic current was reduced by over 300 mV, the passivation potential was reduced, and the pitting potential was increased by over 1000 mV in 0.01 M NaCl. Ti + C and Ti + N implantations increased the load-carrying capacity in lubricated scuffing tests by 60% and 40% respectively. Ta produced no improvement in scuffing resistance. Ti + N implantation increased the hardness by 25% over the unimplanted steel and both Ti + C and Ta implantation reduced the surface hardness. Fretting wear was reduced only slightly in the Ta implanted sample and increased in both the Ti + C and Ti + N implanted samples with the latter showing 4-5 times the weight loss as the unimplanted sample. The correlation between fretting and hardness supports a mechanism in which the hard surface layer breaks into fine particles which act as an abrasive under the intense load of the balls.