Effect of tool geometry and process parameters on strength of various friction stir spot welded lap joints

Abstract

Friction stir welding (FSW) is widely used in aerospace and automotive industries but this process can also be use to join various metals, which are for daily use. As aluminium alloys are used to manufacture most of the kitchen utensils but rivets are most commonly used to join them. For such type of joints, friction stir spot welding (FSSW) can be a good replacement or alternative to rivets. In the present study, FSSW lap joint is been carried out in a bench-drilling machine (spindle speed range of 750 RPM-1341 RPM) to investigate the feasibility of such type of joints in small machine. The aim of this study is to investigate the effects of tool geometry and spindle speed on strength of friction stir welding at different joint. Two different types of tools i.e. circular probe tool and square probe tool are taken into consideration. The variation of welding strength with numbers of spot weld in the joint is also been discussed. The welding process is carried out for two types of joints, i.e., single spot FSW and double spot FSW lap joints. The welding material chosen for the process is aluminium alloy. The temperature recorded at the thermomechanical effected zone signifies that the welding is faster by square probe tool, which takes 20 to 25 seconds to get weld and reaches the highest temperature. The improvement of the process can make FSSW easier to use as a substitute of rivets.