Experimental study of processing γ-TiAl by blasting erosion arc machining

Abstract

γ-TiAl alloy is an ideal material for aerospace components due to its low density, high specific strength and outstanding oxidation resistance at high temperature. However, γ-TiAl is difficult to cut because of its high temperature strength, poor plastic toughness as well as low thermal conductivity. Blasting Erosion Arc Machining (BEAM) has an excellent performance in processing difficult-to-cut materials such as nickel-based superalloy and titanium alloy. Thermal machining model simulated in COMSOL Multiphysics shows the feasibility of processing γ-TiAl by BEAM. Machining experiments are designed to study the effects of different machining parameters (open circuit voltage, electrode diameter, cutting depth) on the machining performance. The experimental results show that the maximum material removal rate can reach up to 4,484.9 mm3/min, the tool wear ratio being 2.74%, and the surface roughness Sa is 74.14 μm, when the peak current is 400 A. Material removal rate is mainly affected by cutting depth. Tool wear ratio is mainly affected by electrode diameter. Surface quality is sensitive to all three parameters. Suitable processing parameters should be selected when different processing objectives are pursued. Considering the recasting cutting depth (< 50 μm) and residual stress influence depth (about 400 μm) after BEAM, it is recommended to reserve at least 500 μm thickness allowance for subsequent processing.