Experimental studies on electrical discharge wire cutting of Ni-rich NiTi shape memory alloy

The experimental investigation explores the effect of electrical discharge wire cutting (EDWC) variable parameters such as spark gap voltage, wire tension, pulse off time, wire feed rate, and pulse on time on the surface roughness, average cutting rate, and metallographic changes of Ni_55.95Ti_44.05 shape memory alloy (SMA). The spark gap voltage, pulse off time, and pulse on time have the significant effect on the surface roughness and average cutting rate, whereas wire tension and wire feed rate have the trifling effect. Ni_55.95Ti_44.05 SMA’s surface after EDWC is characterized by many discharge craters, microcracks, voids, and white layer of resolidified molten material. The elemental composition analysis of white layer using energy-dispersive spectroscopy divulges the deposition of the foreign element from the brass wire as well as the dielectric on the surface after EDWC. The machined surface as well as the wire electrode surface consists of various compounds of Ti, Ni, Zn, and Cu which have been identified by X-ray diffraction peak analysis.