Numerical Simulation of Heat Flow in Friction Stud Welding of Dissimilar Metals

Friction stud welding is a solid-state joining technique used for welding similar and dissimilar materials with high integrity. In friction stud welding, heat is generated by the conversion of mechanical energy into thermal energy at the interface of the work pieces during rotation under pressure. This complicated metallurgical process is accompanied by frictional heat generation, plastic deformation, cooling of high-temperature metal, and solid-state phase variation. Since the thermal cycle of friction stud welding is very short, simulation becomes a vital role to study the behaviour of materials. The simulations make it possible to observe the temperature distribution and heat transfer fields that take place during the process. In the present work, a three-dimensional nonlinear Finite Element-based heat flow model is developed for friction stud welding of aluminium and mild steel combination. The numerical model is validated with a temperature history at the weld interface measured using a non-contact-type infrared thermometer. During friction stud welding, temperature, temperature distribution, temperature gradient, heat transfer rate and their variations, govern welding parameters of a welding machine. Knowledge of them helps to determine optimum parameters and ways to improve the design and manufacture of welding machines. Hence, the developed numerical model could be used as a tool to study the thermal cycles during the process and it will be very much useful for the subsequent analysis of residual stress and distortion of welded joints.