Effects of workpiece mating variations on 2219 Al alloy friction stir welding process

The faying surface gap and misalignment in 2219 Al alloy friction stir welding were investigated. The microstructure and mechanical properties of the joint were discussed. Results show that the joint tensile strength decreases with the increase of faying surface gap under the optimized parameters of rotation speed 800 r/min, welding speed 200 mm/min and shoulder plunging depth of 0.3 mm. Especially when faying surface gap width reaches 0.5 mm, the joint tensile properties remarkably decrease. With the increase of pin tool offset from faying surface, the joint tensile properties decrease gradually, but the differences exist with the offset direction. The defects are formed at the bottom of the joint with pin tool offset of 2.0 mm from faying surface, which results in significant decrease of tensile properties.