The Study of Structural Change due to Abrading in Carbon Steel

Abstract

In Carbon steel, quenching method is used frequently to obtain the wear resistibility of sliding surface because of its convenience. However it can be considered that the structural change due to frictional heating under severe sliding condition have not a little influence on wear behavior.
Then in this paper, the structural change of quenched and tempered S45C carbon steel due to abrading was studied in a point of view of hardness change and microstructure, and moreover the relation between the structural change and wear behavior was discussed.
Main results obtained for quenched materials were as follows.
1) As sliding load increased, the hardness just under sliding surface decreased, and the minimum point that appeared in hardness distribution curve in the vicinity of sliding surface shifted to deep point decreasing its value.
2) It was found that the martensite in the vicinity of sliding surface disappeared and spheroidal cementit precipitated under heavy sliding load.
3) Wear resistibility was very favorable when sliding load was slight, however the effect of quenching became weak extremely due to softening of surface layer when sliding load was heavy.
4) When the material which was softened by abrading was abraded again, the wear decreased under heavy sliding load, but increased under light sliding load.
Above results indicate that the hardening method by quenching is available only when the sliding condition is always mild.