Drillability of Titanium 6246 Alloy

Abstract

This article describes the chips formation during drilling of Ti-6246 titanium alloy using TiAIN coating carbide insert drill. At the early stage of drilling, the chips had a conical spiral shapes regardless the parameters used and heat treatment conditions. However, as the depth increases different types of chips were observed depending on the parameters used. Drilling with high feed rates, lower cutting speed and with coolant resulted in segmented-type. On the contrary, low feed rate and high cutting speed result in long-curly chips. Furthermore, when the depth of drilling was around 10 mm or deeper, a zigzag form of chips was observed regardless the machining parameters applied. Though the chips fOlIDSwere different, cross sectional observation using optical microscopy and scanning electron microscopy shows that all the chips had a serrated type. These chips experienced microstructural elongation at the shear band area. Micro Vickers hardness tests showed that the hardness of the chips was higher compared to the hardness of the original material prior to drilling.