RETRACTED ARTICLE: An investigation on mechanical and metallurgical properties of 2024-T3 aluminum alloy spot friction welds

In this study, the spot friction welding of 2024-T3 aluminum alloy with 1.6 mm in thickness has been investigated. The effects of the tool rotational speed (630, 1000, and 1600 rpm), shoulder penetration depth (0.3 and 0.7 mm), and pin geometry (cylindrical and triangular shape) have been discussed on the metallurgical and mechanical properties. Results indicated that the pin geometry has a considerable effect on the shape of the stir zone. The results of tensile shear tests showed that the tensile shear load increased with increasing rotational speed in the shoulder penetration depth of 0.3 mm, while high shoulder penetration depth had a bilateral effect on the tensile shear load. In addition, the results showed that the tensile shear load of welds made with the triangular pin at a low rotational speed, and a low shoulder penetration depth was more than of welds made with the cylindrical one, which was attributed to a finer grain size generated in the stir zone. Observation of the failed specimens indicated two types of failure modes under tensile shear loading conditions including the fractures that occurred in the vicinity of keyhole (shear fracture) and the fractures that occurred in shoulder indentation (tensile shear-mixed fracture mode). The microhardness tests with both pins showed that the minimum hardness was measured in the heat-affected zone.