Microstructural Characterization of Ti-6Al-4V Subjected to Fretting

Abstract

This study is focused on characterization of microstructural changes linked to deformation and crack formation mechanisms in duplex Ti-6Al-4V specimens used in displacement controlled fretting-only experiments. In particular, the effect of slip displacement amplitude and number of fretting cycles on the evolution of grain morphology, grain orientation, misorientation distribution, composition, and microhardness is investigated using electron backscatter diffraction (EBSD), energy dispersive X-ray analysis (EDX), and nanoindentation. A strong basal microtexture and significant oxygen diffusion were observed in the Ti-6Al-4V specimen that exhibited the most significant cracking. A critical slip amplitude threshold may exist for which a combination of mechanisms, such as plastic deformation, grain reorientation, and oxygen diffusion, occur during fretting that make conditions ideal for crack formation. The results provide insights for development and validation of computational crystal plasticity models with application to fretting and sliding contact problems. New fretting damage-assessment measures have also been identified and have application for components that suffer from fretting wear and/or fatigue related failures.