Drilling-filling friction stir repairing of AZ31B magnesium alloy

Drilling and filling stages were successfully performed to produce a regular volume defect and then repair this fabricated defect. The microhardness distribution of the repaired joint was flat, and an excellent diffusion bonding occurred at the interface between the filler and the base material (BM) under the optimum combinations of a rotational velocity of 1600 rpm, dwell time of 20 s and plunge depth of 0.4 mm. A high-quality joint with the maximum tensile strength of 217 MPa was achieved. The fracture position of this joint was located at the thermo-mechanically affected zone rather than the interface between the filler and the BM of the joint with a low tensile strength.