Effect of rotational velocity of tool on mechanical properties of stationary shoulder friction stir welding

Stationary shoulder friction stir welding (SSFSW) of 6005A-T6 aluminum alloy was investigated on basis of a self-designed stationary shoulder equipment. The results show that tensile strength and elongation of defect-free SSFSW joint with gloss surface both increase and then decrease with increasing rotational velocity of tool, and no cracks appear at the bending degree of 180°. At a constant welding speed of 200 mm/min and the rotational velocity of 1800 r/min, the tensile strength of joint reaches the maximum value of 234 MPa and the strength factor is 79%. The distribution of hardness of SSFSW joint presents W-shape and the minimum hardness appears in heat affected zone. The softening degree of joint increases with the increase of rotational velocity of tool. Fracture position of SSFSW occurs in thermo-mechanically affected zone and the fracture surface presents the typical ductile fracture.