Effect of hardness on rolling–sliding damage mechanisms in PM alloys

Abstract

The lubricated rolling–sliding damage in two classes of PM alloys, namely iron and Fe–1·5Mo based materials in the as sintered as well as case hardened and carbonitrided conditions and with a density of about 7 g cm⁻³, was investigated. Four interrelated damage mechanisms were identified: macroscopic spalling, formation of surface microcracks by plastic shearing, surface densification, and formation of a population of microcracks at the pore edges in the surface as well as subsurface regions. The effect of hardness on the acting damage mechanisms was investigated. Simple equations to model each damage mechanism were developed and used, together with the experimental results, to understand the damage mechanisms and reveal their interrelations.