Electrochemical Machining of High-temperature Titanium Alloy Ti60

The high-temperature titanium alloy Ti60 (Ti–5.6Al–4.8Sn–2Zr–1Mo–0.35Si–0.7Nd) is often used for manufacturing critical components of aero-engines. The use of this alloy has made it possible to increase the service temperature to up to 600 °C. However, machining such alloys by conventional methods is difficult, often resulting in low process efficiency, high tool wear, reduced precision, and poor surface integrity. Electrochemical machining (ECM) is an effective method to machine titanium alloys but the electrochemical dissolution behavior of titanium alloys is different from those of other difficult-to-cut materials such as nickel alloys. This study focuses on the ECM of the high-temperature titanium alloy Ti60. The anodic polarization curve, open circuit potential, and actual volume electrochemical equivalent–current density curve of Ti60 are obtained. The electrochemical dissolution behavior of Ti60 is analyzed, and the composition, concentration, and temperature of the electrolyte used for ECM are optimized. Dissolution experiments are performed at different current densities, and results show that the surface roughness of Ti60 undergoing ECM deteriorates when the current density is small. Finally, electrochemical parameters are optimized and a blisk sector made of Ti60, which is to be used in an aero-engine compressor, is machined by ECM. The process is stable and efficient. The maximum machining rate of the channels is more than 1.2 mm/min. The best surface roughness is Ra 0.6 μm, and the machining accuracy of the blade profile is 0.05–0.07 mm.