Three-dimensional material flow during friction stir welding of AA5083

Abstract

Three-dimensional material flow during friction stir welding (FSW) was investigated using a tracer insertion technique. The tracer material is none other than the substrate material used as a strip and anodized to visualize the flow characteristics during FSW. The three-dimensional material flow behaviour is studied by embedding tracers in three orientations; transverse, longitudinal, and parallel to the welding direction. Three prominent material movements were deduced from this study. First, the material is plasticized and flows from the retreating side (RS) to the advancing side (AS) by pin and shoulder driven mechanism. Second, the vertical material movement from the advancing side in the cavity was created at the traversing tool back. This flow occurred under the constraint imposed by the rotating shoulder, pin, and relatively hard surroundings. The constraint imposed by different bodies exerted a torque on the soft material and forced it to flow downward in AS and upward in RS. Third, extrusion and layer-by-layer deposition of the material from the leading side to the trailing side.