The influence of work hardening on the rolling contact fatigue strength of high manganese austenitic steel.

The rolling contact fatigue tests were carried out on high manganese austenitic steel to investigate the influence of the work hardening phenomenon generated by repeated contact stress on the rolling contact fatigue strength by using a Nishihara-type wear testing machine under a lubricated state with a relative slip ratio of -9%.The results obtained are summarized as follows:(1) In the cases that carbon contents were about 1.0 and 1.2%, high manganese austenitic steel had the same fatigue endurance limit (2035MPa), regardless of carbon content.(2) The rolling contact fatigue endurance limit of high manganese austenitic steel increased remarkably with work hardening generated by repeated contact stress.(3) The rolling contact fatigue endurance limit of high manganese austenitic steel increased remarkably compared with the austenitic stainless steel (SUS304) having the same matrix structure as that of high manganese austenitic steel.(4) A crack of high manganese austenitic steel propagated along the boundary of the work hardening zone and the unwork hardening zone. The depth of crack propagation, at which the crack front became almost parallel to the contact surface, was fairly deeper than the maximum stress region calculated according to the maximum shearing stress theory.