Microstructural Evolution and hardening of Subsurface of Mg-3Al-1Zn Alloy during Dry Sliding Wear

Abstract

Dry sliding tests were performed on as-cast AZ31 alloy using a pin-on-disc configuration within a load range of 5-360N at a sliding velocity of 0.8 m/s. Worn surface morphologies were examined using scanning electron microscopy. Wear mechanisms, namely abrasion, oxidation, delamination, thermal softening and melting, have been observed in different load ranges. Surface hardness, subsurface plastic deformation and worn surface temperature were used to characterize the microstructure evolution and hardness change in subsurface. The results reveal that in the lower load range of 5-120N, surface hardening originating from large plastic deformation plays the important role in keeping a mild wear, in the higher load range of 120-360N, surface softening originating from dynamic recrystallization and surface melting are responsible for severe wear.