Effect of milling parameters on microhardness and microstructure during dry and flood milling of Ti-6Al-4V

The current study focuses on investigating the effect of milling parameters on the microhardness during dry and flood milling of Ti-6Al-4V. Dry and flood milling were performed while varying spindle speed (120, 150, and 180 rev/min), depth of cut (1, 1.5 and 2 mm), as the feed rate (4.6 mm/min) was kept constant. Subsequent to milling, milled surfaces microhardness were measured and microstructure evolution was analysed using an optical microscope. It was established that the deformation of beta phase increased with increase of spindle speed during dry milling while during flood milling there was no microstructural change associated to the increase of the spindle speed. On the other hand, the hardness increased as result of increase of spindle speed during both dry and flood milling. Flood milling generated a maximum hardness of 338.44 HV at 180 rev/min which is superior to maximum hardness of 336.36 HV produced during dry milling. Dry milling at 1.5 mm depth of cut generated maximum deformation of beta phase while during flood milling maximum deformation was recorded at 2 mm depth of cut. The hardness increased with increment of depth of cut during flood milling while it decreased with increase of depth of cut during dry milling.