Machining performance of cryogenically treated Ti-5Al-2.5Sn titanium alloy in electric discharge machining: A comparative study

In the present study, the effect of cryogenic treatment on the machining performance of Ti-5Al-2.5Sn alpha titanium alloy was investigated during electric discharge machining. Untreated, shallow cryogenically treated (-110?), and deep cryogenically treated (-184?) titanium alloys were machined by varying current and pulse-on-time. The machining performance was measured in terms of higher material removal rate and microhardness and low tool wear rate and surface roughness. The results showed a significant improvement in the machining performance with deep cryogenically treated alloy when compared with shallow and untreated alloy. Current and pulse-on-time also affected the machinability of titanium alloy. Higher material removal rate and microhardness were observed when titanium alloy was machined at high current and pulse-on-time. During machining, carbon was deposited on the machined surface due to the breakdown of hydrocarbon dielectric at high temperature thereby, affecting its properties.