FRICTION STIR WELDING BACKING MEMBER AND METHOD OF USING SAME

摘要

A backing member (14) for a friction stir butt welding apparatus includes a groove (38) in the working surface of the backing member which supports the workpieces (20, 22) being butt welded. The backing member is positioned with the groove aligned directly beneath the butt joint (28) between the workpieces. A rotating friction stir welding pin (16) is introduced at the joint so as to plasticize the material of the workpieces on either side of the joint, and pressure is applied between the stir pin and the workpieces to create a forging pressure which forces plasticized material downward through the root zone of the weld and into the groove in the backing member. A visible bead is thus produced on the lower surfaces of the workpieces indicating total penetration of the weld. Lack of a bead indicates probable failure of the weld to totally penetrate through the root zone.