Properties of Dissimilar Aluminum Alloy Friction Stir Welded Joint Prepared by Tool Pin with Different Shapes

Friction stir welding was conducted on 2024-T3 and 7075-T6 aluminum alloys with threaded cylindrical and threaded triangular prism stir heads, and the macrograph and hardness of the weld seam, tensile properties and tensile fracture morphology of the joint were analyzed. The results show that there was a good fusion in the weld seam without any tunnel defects welded with threaded triangular prism stir head under the parameters of 1 100 r·min-1 and 80 mm·min-1, which made the tensile strength of the joint with material collocation method of AS(2024)-RS(7075) reached 260 MPa and fractured in the thermal-mechanically affected zone (TMAZ) area of 2024-T3 alloy; the minimum hardness of 107 HV appeared in the joint welded with threaded cylindrical stir head under the parameters of 1 100 r·min-1 and 120 mm·min-1 and material collocation method of AS(2024)-RS(7075), fewer and shallower dimples reduced its tensile strength to the minimum of 78 MPa.