Microstructural effects in wear of hardened sintered steels produced by diffusion bonded and prealloyed powders

Abstract

The influence of the microstructure on the wear behaviour of some hardened sintered steels produced with diffusion bonded powders and subjected to through hardening, carburising and sinterhardening was investigated. In dry sliding, wear was oxidative in nature and the localised surface deformation caused delamination, which further reduce the wear resistance. In these conditions, the harder the microstructure, the better the resistance to plastic strain. In lubricated rolling–sliding, wear occurs by rolling contact fatigue. Cracks nucleation was caused by the stress localisation at the pores edges. In this case, a brittle virgin martensite has a negative effect. Tempering reduces martensite brittleness, and makes its resistance to nucleation and propagation of the rolling contact fatigue comparable to that of Fe–Ni austenite.

Keywords:

• THROUGH HARDENING
• CARBURISING
• SINTERHARDENING
• DRY SLIDING
• LUBRICATED ROLLING–SLIDING