An experimental and numerical investigation on impact spot welding of metallic plates using gas mixture detonation technique

Abstract

In this paper, the impact spot welding of metallic plates was investigated both experimentally and numerically using a single-stage gas mixture detonation apparatus. The impact spot welding process was carried out on aluminum alloy and steel materials using rigid steel projectiles. In this process, the mixture of oxygen and acetylene was detonated in a combustion chamber to launch the projectile. The masses of flat- and spherical-nosed projectiles were 270 and 230 g, respectively. The impact velocity was measured in all experiments. The cross-sections of the weld spots were inspired by a scanning electron microscope to assess the quality of welding. For several experiments, wavy interfaces were observed showing there is a good bonding. For numerical simulation of the process, Abaqus/Explicit software was used and the deformation and failure mechanisms of impact spot-welded specimens were further investigated. The Johnson–Cook thermoplasticity model along with its failure model was utilized to predict the behavior of metallic materials. The numerical simulation results were in good agreement with those obtained from experiments in terms of the deformation mode and failure pattern. The propagation of the wave on the surface of the flyer plate was further studied. The results showed that the stress waves start from the center and propagate to the corners of the plate. To numerically evaluate the welding quality, two parameters of the shear stress at the collision point as well as the equivalent plastic strain for the flyer and target plates were obtained in the numerical simulation. The numerical results showed opposite directions of shear stress for flyer and base plates at the contact point, which can be used as proof for good bonding. Besides, the magnitudes of the equivalent plastic strain for both flyer and base plates were higher than those reported values in the open literature that confirms successful welding.