Cyclic wear behavior (fretting) of a tempered martensite steel

Abstract

Cyclic wear experiments were conducted on a 4130 steel with a tempered martensitic structure in laboratory air and in flowing argon. Temperatures of the sliding interfaces were measured and were of the order of + 10 K above the ambient. The interface temperatures were observed to be cyclic and correlated with maxima in sliding velocities between the surfaces. Microhardness measurements and optical and electron metallographic observations of fretted surfaces indicated selective surface hardening and the formation of large numbers of thin metallic flakes. The thickness of the flakes corresponded to the thickness of the hardened layer and were formed from subsurface crack initiation processes. The results of this investigation do not support many previously proposed models for fretting damage. Rather a micromechanical cracking model is proposed which appears to explain observed results in terms of a delamination model.