Effect of parameters on microstructure and mechanical properties of friction stir spot welded joint

Refill friction stir spot welding joint of a 1.0 mm thickness 6016-T4 aluminum alloy was prepared by different parameters.The comprehensive properties of 6016-T4 aluminum alloy joint by different parameters was studied through the analysis of its surface formation,shear tensile,crossing tensile and micro-hardness by using orthogonal test.The results show that the optimum parameters are with the welding time of 4.5 s,the rotation speed of 1 600 rpm and the depth of 1.4 mm.The shear tensile force and cross tensile strength of the joint are respectively 4.02 kN and 1.32 kN.The micro-hardness of the action area of the pin is more uniform,and the micro-hardness value is higher than that of the base metal area.The joints do not show any looseness during the peeling tensile test,indicating that the joints are firm and qualified.