Study on crater depth during material removal in WEDC of Ni-rich nickel–titanium shape memory alloy

Abstract

The objective of this experimental investigation is to reveal the individual effect of wire electrical discharge cutting (WEDC) process parameters, namely discharge energy density, wire feed rate, spark frequency, wire tension, and spark gap voltage on average crater depth, material removal rate (MRR), and metallographic changes of Ni55.95Ti44.05 shape memory alloy (SMA). The analysis of crater size during material removal in WEDC has been also discussed in this study. The three-dimensional surface topography at higher discharge energy density divulges the formation of deeper and wider craters with high surface roughness on the machined surface compared to lower discharge energy density. MRR and average crater depth increase with the increase in discharge energy density and decrease with the increase in spark frequency and spark gap voltage, whereas wire feed rate and wire tension have the trivial effect. The analysis of X-ray diffraction peaks of the machined surface shows the presence of various compounds such as NiTi, TiO, TiO2, Ni4Ti3, CuZn, Cu2NiZn, NiTiO3, and NiZn and tensile residual stress.