Surface Residual Stresses Induced by Shot Blast Peening after EDM of AISI D2 Die Steel using two types of Electrode

Abstract

Electrical discharge machining (EDM) is one of most popular nonconventional machining processes used for creating complex shapes within the parts and assemblies in the manufacturing industry. The present work deals with studying the effect of EDM input parameters (peak current, pulse-on time and the type of electrode) and the shot blast peening time on the induced surface residual stresses. The response surface methodology (RSM) has been used to plan the experiments. To verify the experimental results, analysis of variance (ANOVA) was used and regression models were built to predict the EDM output performance characteristics for the residual stresses for AISI D2 die steel in terms of input parameters. The results showed that maximum compressive surface residual stresses obtained when using the copper and graphite electrodes with minimum values of pulse current (8 A), pulse on duration (120 μs) and shooting time (60 min.), reaches (-847.636 MPa) and (-637.073 MPa), respectively. These results indicated that the copper electrodes improve the residual stresses by about (33%) compared with graphite.