SUBSURFACE CRACK NUCLEATION DURING DRY SLIDING WEAR OF P/M STEEL POWDERS

摘要

When a porous powder metallurgy part is worn by a counterbody, intense shear stresses are exerted on the surface and subsurface owing to the both normal load and tangential load (i.e. friction). Hence, depending on the amount of loads the pores near the surface may be closed owing to intense plastic deformation in this area and a hardened densified layer may be formed. This densified layer has the thickness in which applied stresses are more than the yield stress of the matrix. In this research a porous Distaloy AE material, which is a partially alloyed steel powder, was worn by AISI 52100 steel in a reciprocating manner. Then subsurface stresses derived from normal and tangential load were calculated. The densified layer thickness was then calculated by comparing these stresses with the yield stress of the matrix. The results are then compared with the metallographic photos and the differences are discussed.