Impact spot welding of Al/Cu dissimilar metals using gas mixture detonation technique: An experimental investigation and finite element simulation

In this paper, the gas mixture detonation technique was utilized for impact spot welding of dissimilar metallic plates. The gas detonation produces shock waves to accelerate a high-strength projectile towards a long smooth barrel. After the collision, the flyer plate accelerates towards the base plate and spot joining is obtained. In this series of experiments, Al-6061-T6 and OFHC copper were used as the flyer and base plates, respectively. The effect of different process parameters such as flyer plate thickness, standoff distance, and nose geometry on the weld interface characteristics was investigated experimentally. Two different nose shapes, flat and spherical were tested while the mass of the projectile was considered constant (16.5 g). To inspect and analyze the weld quality at the interface, SEM tests were carried out. The experimental results show that the standoff distance and nose geometry have considerable effects on the surface morphology and dimension of the weld spot. Furthermore, a rigorous numerical parametric study was performed by using Abaqus/Explicit software. The numerical model was validated against a selected experiment in terms of the deformation profile of both flyer and base plates. To numerically evaluate the weld quality at the interface, two well-known criteria in the literature, i.e., the PEEQ value at high strain-rates and opposite direction of the shear stress at the collision point, were employed. The rigorous numerical parametric study results show that the flyer plate thickness and standoff distance have a considerable effect on the radius of welded and unwelded regions, the rate of contact growth, bulge depth, and bulge diameter.