Properties of overlap joints welded by the Friction Stir Welding Method

摘要

This paper regards the problem of creating overlap joints made of aluminum alloys using the technology of friction stir welding, FSW. The structure of a joint was analyzed in the advancing zone, the heat affected zone and the retreating zone. It was shown that the joint is nonuniform and asymmetric. The nonuniformity and asymmetry of the joint are characterized by a distinct border between material that was recrystallized and thermomechanically deformed. Shear tests demonstrated the existence of the area in the retreating zone where bonding between joined elements occurs. This reduces the joint strength. In the advancing zone, the shape of the boundary line between joined materials is the factor determining the character of material failure. The work analyzes the impact of downward force and tool position on the auality of welds. It was shown that for the welding process the best results can be achieved by controlling downward force and maintaining appro-priate tilt angle and depth of tool penetration.