WELD ROOT CLOSURE METHOD FOR FRICTION STIR WELDS

摘要

A method of root closure of friction stir welds in all types of stir weldablematerials, especially difficult to weld materials, such as non-extrudablealuminumalloy 2024, 2014, 2090 and 7075. The method includes providing a backingdevicethat has a recess, such as a groove or channel, sized to receive the tip ofthe pin of thewelding tool and to contain the bead of the weld being formed. The workpiecerestson the backing device, with the proposed weld line aligned with the recess.Thus, asthe weld is formed, material is extruded into the recess, completing closureof theweld root, and forming a small bead on the rear side of the workpiece.Optionally,this bead may be removed by a machining process. In one embodiment, thebackingdevice is a plate with a channel machined in its surface so that the workpiecemay betemporarily affixed to the plate, with weld line aligned with the channel, forwelding.In an alternative embodiment, the backing device is a roller, mounted beneaththerotating pin of the friction stir welding tool, with a circumferential groveon itsexterior surface, sized to receive the pin tip and contain the weld bead asthe weld isbeing formed.