Roles of Friction-Induced Strain Hardening and Recrystallization in Dry Sliding Wear of AZ31 Magnesium Alloy

Dry sliding wear tests were performed on AZ31 alloy using a pin-on-disc configuration under the loads of 5-360 N and sliding speeds of 0.1-1.5 m/s. Friction and wear characteristics of AZ31 alloy were investigated as a function of the load and sliding speed. Wear mechanisms for AZ31 alloy were characterized by scanning electron microscopy. The wear behavior in mild and severe wear regimes was described in terms of plastic deformation and microstructure evolution in subsurface, and surface hardness change and temperature rise of worn surfaces. The results revealed that surface strain hardening caused by large plastic deformation played an important role in maintaining a low slope of wear rate in mild wear regime, while surface thermal softening originating from dynamic recrystallization and surface melting were responsible for a rapid wear in severe wear regime.