Magnetic field-assisted ultra-high-speed friction stir welding

Poor metal flow in ultrathin plates, which is detrimental to the integrity and mechanical properties of the joint, is an inherent problem of stir friction welding. In this paper a novel method, based on magnetic field-assisted ultrahigh-speed friction stir welding where the magnetic field dictates the simultaneous rotation of the stirring head, is proposed. The magnitude and position of magnetic field strength also can be adjusted to finely tune the thickness of sheets, allowing the magnetic lines of force to concentrate and penetrate the weld area. The results reveal that, after welding 1 mm-thick 6061-T6 aluminum alloy, the grain refinement in the weld core area is obvious and the tensile strength reaches 81.4 % of the base metal. This indicates that magnetic field-assisted ultra-high-speed friction stir welding has the potential to achieve high-quality welding, which can contribute to the plasticization process of non-magnetic metals and provide novel ideas for the development of applied energy-assisted stir friction welding technology.