Experimental investigation on the deformation behaviors of Ti-6Al-4V sheet in electropulsing-assisted incremental forming

A self-built experiment platform was employed to carry out electropulsing-assisted incremental forming of Ti-6Al-4V alloy sheet. The influences of electropulsing on the deformation behaviors, deformation force, friction coefficient, strain distribution, and microstructures of Ti-6Al-4V alloy were investigated. The temperature field distribution of the deformed sheet under electropulsing was analyzed through finite element simulation. In this work, the experiments were conducted with the frequencies of 0–450 Hz and peak current densities of 0–881 A/mm2. The strain distributions of the formed groove parts were obtained and the influences of electropulsing parameters on the fracture forming strains were studied. It was found that the major strain and thickness strain enhanced, and fracture forming lines moved up with the increasing electropulsing parameters, indicating the formability enhancement. Moreover, the maximum fracture depth of groove rose to 7.0 mm, which increased by 52.2% compared with conventional ambient incremental forming. The results presented that the frequency and peak current density of electropulsing could decrease the deformation force. The vertical and horizontal forces were measured to analyze the friction condition. It was suggested that the friction reduction between tool and alloy sheet contributed to the formability enhancement. In addition, the analysis of microstructure evolution showed that the β grain became elongated due to dynamic recovery and some coarse uneven α grain tended to homogenize, contributing to the formability enhancement of Ti-6Al-4V sheet.