Influence of Process Parameters on Surface Crack Density in Electrical Discharge Machining of Ni35Ti35Zr15Cu10Sn5 Shape Memory Alloy

Abstract

The importance of Surface Crack Density (SCD) in Electrical Discharge Machining (EDM) of high-temperature high-entropy shape memory alloy (HT-HE-SMA) lies in its direct effect on mechanical traits and overall efficiency. A higher SCD can compromise the alloy's durability, fatigue resistance, creep resistance, and shape memory, which is significant in aerospace, medical, automotive, and other industrial domains. This research delves into the study of the effect of three input variables, namely discharge current (Ip), Pulse-on time (Ton), and pulse-off time (Toff), on SCD using the central composite design based on Response Surface Methodology (RSM) to optimize machining parameters in EDM. Experiments used a copper electrode and samples of Ni35Ti35Zr15Cu10Sn5 (at%) HT-HE-SMA that were synthesized via the powder metallurgy method utilizing mechanical alloying and sintering techniques. The results indicate that Ton exerted the highest influence, followed closely by Ip. Under keeping the other parameters at median values, decreasing Ton to 50 µs reduced SCD to 0.0008209 µm/µm2, whereas increasing it to 150 µs resulted in SCD peak at 0.0054961 µm/µm2. Using RSM, the results were modelled, showing all coefficients as significant in the ANOVA at a 5% level. A robust R2 value of 95.55% underscores the model's adequacy.