Effect of friction stir spot welding parameters on the shear fracture load of AA8011/structural steel for automotive applications

Abstract AA8011 and mild steel are the most suitable candidates for several structural applications due to their unique properties. However, joining these two materials with fusion welding poses challenges for manufacturing engineers. As a result, it often leads to issues such as hot cracking, porosity, and alloy segregation due to incompatibilities in metallurgical factors. An alternative method, friction stir welding, is used to join these materials. While lap joint configuration is common in many sectors for joining different thicknesses, traditionally it has been performed using rivets, bolts, and fusion welding processes. In this investigation, friction stir spot welding is employed to eliminate the need for rivets. To analyse the influence of major process parameters on shear fracture load, a systematic analysis is conducted. From the experimental results, it is detected that the joint welded with a tool rotational speed of 1,000 rpm, plunge rate of 4 mm.min −1 , dwell time of 5 s, and a tool shoulder to pin diameter ratio of 3.0 exhibited peak load carrying capabilities of 9.46 kN. This can be attributed to the optimum levels of hook width, hook height and balanced material flow.