Machine Structural Steels. The Effect of Shot Peening and Heat Treatment on the Contact Rolling Fatigue Life.

Influence of heat treatment and hard shot peening on the contact rolling fatigue strength of case hardning steel JIS SCr 420 was studied. Carburized and carbonitrided specimens were tested. Hard shot peening treatment on the levels of 0.7mmA and 1.0mmA were carried out and their contact rolling fatigue strength were compared with the specimens without shot peening. The contact rolling fatigue strength of the carbonitrided specimens is higher than the carburized specimens. The shot peening treatments extremely increases contact rolling fatigue strength. The increment of the contact rolling fatigue strength for the carburized specimens is larger than that for the carbonitrided specimens. These results are explained by the variation of hardness and race track width which are related with beneficial effects of retained austenite and residual stress.