Influence of cutting speed and tool wear on the surface integrity of the titanium alloy Ti-1023 during milling

This study focuses on the machined surface integrity of the titanium alloy Ti-10V-2Fe-3Al (Ti-1023) during face milling. Surface roughness, machining defect, microhardness, and microstructure variations are investigated at different cutting speeds and tool average flank wear (VB) values. Experimental results show that surface roughness increases when cutting speed is increased from 40 to 100 m min(-1) and decreases when cutting speed is increased from 100 to 300 m min(-1) by using a new tool. Moreover, surface roughness values are stable when cutting speed is increased by using a worn tool at VB = 0.2 mm and increases when VB is increased. As for defects, the machining defect is determined to be dependent on cutting speed and tool wear directions. Microhardness is decreased to 35 mu m beneath the machined surface at different cutting speeds by using a new tool. The influence of tool wear on hardening is significant, with the depth of hardening being less than 55 mu m by using a worn tool at VB = 0.2 mm and reaching 130 mu m at VB = 0.35 mm. No significant phase transformation or evident deformation can be observed at different cutting speeds by using a new tool (initial wear). Severe plastic deformation and deep alteration of the microstructure in the machined surface are produced with VB from initial wear to VB = 0.35 mm. VB is best maintained at less than 0.2 mm for finish machining of Ti-1023.