Wire-feeding friction stir welding for large-gap width tolerances

A novel method, named wire-feeding friction stir welding, was proposed for welding large-gap-width joints. Continuous wire feeding and welding systems were designed. AA6082-T6 aluminium alloy plates with a gap width of 2 mm were welded using Al–Si alloy wires as the filler materials. Sound joints were obtained even if the gap width reached over 2/3 thickness of the base materials. Fine microstructures were obtained via dynamic recrystallisation induced by severe plastic deformation. The ultimate tensile strength of the joints reached 253.4 ± 1.3 MPa. The adaptability to working conditions of friction stir welding was improved for long welds of high-speed railway, ship and aircraft.