Machinability of a near beta titanium alloy

In this paper, the machinability of a near beta Ti25Nb3Mo3Zr2Sn titanium alloy with different heat treatment histories has been investigated in terms of cutting force, chip temperature and chip formation. A solution treatment was performed followed by ageing at different temperatures for the near beta alloy. It has been shown that the same alloy behaves differently during machining at various cutting speeds after different heat treatments. The observations have been explained in terms of friction effects and the hardness of the materials. It has been concluded that the ductility of a workpiece plays a significant role in determining its machinability. High friction at the tool–chip interface in a ductile workpiece resulted in a higher degree of chip segmentation and a larger undeformed surface length in each chip.