Machining of Pure High Grade Titanium: Effect on the Subsurface Microstructure

This study has been made to characterize the plastically subsurface layer after orthogonal cutting of on high grade Ti-5N unalloyed titanium with a mean grain size of about 0.5 to 1.8mm. A home-made sample holder has been specially developed for these experiments and SEM EBSD technique is used to characterized the subsurface layer. In function of the cutting conditions, we have found in subsurface glide (when the cutting speed is low) and when the cutting speed is high some compression twins but also some tension twins which indicated that we have tensile stress state ahead of the tool tip.