Mild wear and severe wear behavior of Ti-6Al-4V alloy at low, intermediate and high sliding speeds

Abstract

This paper described the mild and severe wear behavior of Ti-6Al-4V alloy and revealed the mechanisms for mild-severe wear transitions (MSWTs) under low, intermediate and high speeds. Under each speed, wear rate was measured as a function of applied load, from which mild wear and severe wear were identified. Morphologies and chemical compositions were analyzed on worn surfaces using SEM and EDS to determine the wear mechanisms and their relation with wear transition. Analyses of microstructural evolution and hardness change in subsurfaces were performed to explore the mechanisms for MSWTs. Results showed that two different types of MSWTs were found: one was controlled by large-scale spallation of mechanically mixed layer (MML) under 0.2 m s−1; the other one was dominated by severe plastic deformation (SPD) under 0.8 and 2.0 m s−1. The former mechanism for MSWT was the enhanced fragility of MML with an incompact structure owing to high content iron oxide, while the latter mechanism for MSWT was the softening of surface material deriving from dynamic recrystallization during sliding wear testing. The results of this investigation shed new insight into the relationship between experimental parameters, wear mechanism, microstructure and property in subsurface and MSWT for Ti-6Al-4V alloy.