Non-weld-thinning friction stir welding

Weld thinning has been an inherent issue of friction stir welding, which is detrimental to the joint integrity and mechanical properties especially for thin structures. In this paper, a novel method named non-weld-thinning friction stir welding was proposed. The welding tool contained an inner shoulder and an outer shoulder, and it was adjustable to control the protrusion of inner shoulder relative to outer shoulder. The outer shoulder could accumulate and refill the overflowing materials to eliminate weld thinning. The ultimate tensile strength reached 91% of base metal, which indicated that non-weld-thinning friction stir welding had the feasible and potential to realize high quality joint without weld thinning. (C) 2019 Elsevier B.V. All rights reserved.