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

Abstract

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.