Controllability of joint integrity and mechanical properties of friction stir welded 6061-T6 aluminum and AZ31B magnesium alloys based on stationary shoulder

In order to improve joint integrity and reduce the amount of intermetallic compounds (IMCs), 6061-T6 Al and AZ31B Mg alloys were successfully joined by stationary shoulder friction stir welding (SSFSW). The stationary shoulder effectively enhanced the joint surface integrity and reduced the thickness reduction of the Al/Mg joint. The elimination of pin adhesion was beneficial to increasing material transfer and then improving interfacial joining length of Al/Mg joint. Extremely thin IMCs layer could be achieved because of the heat sink induced by the stationary shoulder. The maximum tensile strength of the Al/Mg joint reached 137 MPa at a welding speed of 60 mm/min, rotating velocity of 1000 rpm and offset to Mg sheet of 0.3 mm, which was 130% higher than that of conventional joint. SSFSW is feasible and has the potential to join dissimilar materials with the formation of IMCs, such as Al/Mg alloys, Al/copper alloys, Al/titanium alloys and so on.