Effect of electropulsing on springback during V-bending of Ti-6Al-4V titanium alloy sheet

Abstract

Effect of frequency and peak current density of electropulsing on springback behaviors of Ti-6Al-4V titanium alloy was investigated during electrically assisted V-bending tests. The experiments were carried out by controlling variable parameters with a frequency of 0–450 Hz and peak current density of 0–62.5 A/mm2. The results show that springback angle and V-bending load value decrease with increasing frequency and peak current density. Springback can almost be eliminated at 450 Hz and 43.1 A/mm2. Based on neutral layer offset and microstructure analysis, it demonstrates that the reductions of neutral layer radius, bending moment, and residual stress are responsible for the springback reduction. In addition, the refined β phase particles, dissolution of clustered β phase, the reduction of β particle spacing at outer layer, and enhancement of β particle spacing at inner layer contribute to the balance of tensile and compression residual stress, contributing to springback reduction. Effect of peak current densities on the springback behavior under similar RMS current density was carried out and it was found that athermal effect could promote the dislocation motion and unraveling of dislocation pile-ups, further promoting to the springback reduction.