Tool wear mechanisms in machining of three titanium alloys with increasing beta-phase fraction

Mechanical and microstructural properties of titanium alloys change with beta-phase fraction. This in turn influences the dominant tool wear mechanisms in their machining. This work therefore involves turning experimentation on three titanium alloys with varying beta-phase fraction, namely, alpha, alpha + beta and beta-rich alloys using coated carbide tools, to identify dominant wear mechanisms, which hitherto have not been adequately investigated. The dominant wear mechanisms were investigated using scanning electron microscopy and energy-dispersive X-ray analysis of worn tool surfaces and were also correlated with the cutting forces during machining. Abrasion, abrasion with built-up edge and plastic deformation of cutting edge appeared to be the dominant tool wear mechanisms in alpha, alpha+ beta and beta-rich alloy, respectively. At the same time, diffusion of Sn, V and Mo from alpha, alpha+ beta and beta-rich alloys to tool face, respectively, was observed. The chip-tool contact length predicted using the analytical models from the literature matched closely with the experimental values