Failure Mechanism of Contact Fatigue of Surface Super-hardened M50NiL Steel

Abstract

Hardness gradient, residual stress gradient and the organization structure of surface super-hardened M50NiL steel roller and M50 steel roller were studied, the rolling contact fatigue life was measured, and the failure process was analyzed and compared by using surface profiler, Vickers hardness tester, X ray residual stress determinator, optical microscope, scanning electron microscope (SEM), rolling contact fatigue test machine and other equipment. The fatigue failure mechanism of surface super-hardened M50NiL steel was revealed. The results show that the fatigue failure mechanism of surface super-hardened M50Nil steel returns to the Hertz theory and shows typical contact fatigue characteristics. The high surface hardness, residual compressive stress and a good organization structure can completely inhibit the initiation of surface cracks; therefore, the failure mechanism is returned to the Hertz theory.

Keywords

• surface super-hardened
• M50NiL steel
• contact fatigue
• failure mechanism