Study on Effect of Heat Treatment on Chips Formation And Forces in Drilling Titanium Alloy 6AL-2SN-4ZR-6MO

Abstract

This paper focusses on effect of heat treatment on chips formation and forces resulted during drilling titanium 6246. Aim of the research is to improve drillability of this material. The heat treatment steps were heating at a certain temperature for three hours followed by different cooling methods. Three heat treatments were chosen out of several trials: (i) at 595°C, (ii) at 870°C and (iii) at 985°C. Optic microscope and scanning electron microscope (SEM) were employed for observing the microstructure of the chips before and after drilling. Quantitative analysis of chips is based on degree of serration measurement. The Kistler dynamometer was used for recording the forces during drilling. It was evident that heat treatment at 985oC followed by furnace cooling resulted in the highest degree of serration which indicate that chips are easier to brake. This heat treatment also resulted in the lowest thrust force and torque. It may be related to extremely bigger grain boundary compared to other heat treatments and the as-received one.