Comparison of the sliding wear process of various cast irons in the laser-surface-melted and as-cast forms

Abstract

The sliding wear characteristics of cast irons having a range of compositions and initial graphite forms have been determined in both as-cast and laser-surface-melted conditions using a pin-on-ring test configuration. Observed differences in equilibrium wear behaviour between the as-cast alloys were principally in the mild-to-severe transition load and the nature of the severe wear process. Such effects are interpreted in terms of the mean interparticle spacing of graphite in the microstructure which determines the relative propensity for subsurface crack propagation during wear. The ledeburitic structures produced by laser surface melting of the cast iron substrates acted to stabilize a regime of mild equilibrium wear with substantially lower wear rates than for the mild oxidative wear of the as-cast microstructures. Metallographic observations of the laser-melted layer have identified a wear process consisting of fine polishing abrasion.