A Novel Method of Evaluating the Mild to Severe Wear Transition Loads for Magnesium Alloys

This paper describes a novel method for predicting the mild to severe wear transition loads for AZ31 and AZ61 alloys at various sliding velocities. Morphologies and hardness of worn surfaces and microstructures in subsurfaces of AZ31 alloy were analyzed. A criterion of mild to severe wear transition is proposed, i.e., the mild to severe wear transition is controlled by a critical surface dynamic recrystallization (DRX) temperature. DRX temperatures in surface layers at transition loads are determined using recrystallization kinetics. Correlation between DRX temperature and transition load is established by introducing a constant cDRX that is associated with testing equipment and material properties of pin and disk in the critical DRX state. The transition loads are well predicted in a sliding velocity range of 0.5-4.0 m/s for AZ31 alloy, and 0.8-2.0 m/s for AZ61 alloy.