Effect of rotational direction and holding time of friction stir spot welding on Shape and Strength of Al-2024 alloy

In this study, friction stir spot welding was used to make lap joints on strips of 2024 aluminum alloy. The effects of tool rotational direction (clockwise and counter clockwise) and holding time on bond formation and tensile shear strength of the resulting joints was determined. Macro structure of stir zone was monitored by optical microscopy and it was indicated that interface of sheet metals near the pin hole (Hook) was determined. Also with increasing of the holding time, width of the stir zone and tensile shear failure load increased. An optimum combination of parameters that maximizes joints tensile shear strength was identified.