Mechanical performance of dissimilar friction stir welded lap-joint between aluminium alloy 6061 and 316 stainless steel

Abstract

Abstract The dissimilar lap-joint of the AA6061 to 316 stainless steel was produced by friction stir welding. Changing microstructure, joint interface, and mechanical performances via welding rate were revealed. A wave interface pattern was found at the low welding rate with a free oxide layer. The interface became flat at the high welding rate with the oxide film formation. The diffusion and intermetallic compounds (IMCs) layers were formed on the interface and their thickness decreased via increasing the welding rate. The highest joint strength was obtained at the welding rate of 75 mm/min but strongly reduced with growing the welding rate. The strength was dramatically correlated with the bonding area, diffusion thickness and interface morphology instead of the IMCs layer thickness. At the low welding rate, the joint was fractured via ductile behaviour with a lot of dimples found on the fracture surface of 316 stainless steel.