Research on the Electric-Pulse-Assisted Turning Behavior of TC27 Alloy

Abstract

As a difficult-to-machine material widely used in the aerospace industry, the high-quality and efficient cutting of titanium alloys has been a hot issue in the field of machining. This work performed electric-pulse-assisted turning (EPT) and conventional turning (CT) for Ti5Al4Mo6V2Nb1Fe (TC27) alloy with two kinds of cutters. The results showed that electric pulses significantly improved the machining performance and surface finish quality. With the help of the electric pulse, the cutting force of TiAlN-coated cemented carbide insert (CCI) and uncoated carbide insert (UCI) tools during turning was reduced by more than 20%, and the surface roughness decreased by about 30% with a root mean square of the current density of 0.9 A/mm2, because the larger current led to a more obvious electro-plasticity effect. Compared with CT, the surface microhardness of the EPT samples processed with different current densities decreased; this is because the hardened surface was softened by both thermal and athermal effects under the continuous pulse current. However, the microhardness of the EPT samples was still higher than the matrix. At the same time, EPT reduces the wear of the cutting tool, thus helping to extend the tool’s service life. Finally, the electric pulse parameters recommended to assist turning are as follows: an electro-pulsing frequency of 600 Hz, a root mean square of the current density in the cross-section of 0.57 A/mm2, and a lasting time of the current per circle of 100 μs.