Contact Fatigue Behaviour of Ni-Cu-Mo Alloyed PM Steels

摘要

The contact fatigue damage in a DistaloyAE-0.5%C P/M steel was found to be mainly due to subsurface cracks, located in the bainite/pearlite regions or, at the greatest depths, at the smallest necks, and surface cracks, which formed after asperity-scale friction induced plastic deformation. Steam-treatment was found very helpful in increasing the load-bearing capacity of the material and thus reduce the microstructural damage. Two other surface treatments were investigated, namely case-hardening and carbonitriding. No subsurface cracks were detected in both materials. In the case hardened material some surface pits were detected, which formed by asperity-scale fatigue. In the carbonitrided material some small surface cracks, which formed after asperity-scale plastic deformation, were also detected.