The Effect of Fe Content on the Microstructure and Tensile Properties of Friction-Stir-Welded Joints in Recycled Cast Aluminum Alloy

The presence of the impurity element Fe significantly influences the overall performance of recycled aluminum alloy. This study aims to elucidate the impact of Fe content on the microstructure and tensile properties of friction-stir-welded (FSW) joints in recycled cast A356 aluminum alloy. Three samples with varying Fe content were prepared for FSW joints. The quality of the weld zone was meticulously assessed through macrostructure and microstructure analyses. The tensile strengths of the joints were carefully evaluated and correlated with the microhardness and microstructure of the weld zone. The research findings reveal that, among the three fabricated joints, the one with an Fe content of 0.3 wt.% demonstrates the most favorable tensile performance. This particular joint exhibits the highest tensile strength of 153 MPa, commendable yield strength of 90 MPa, and a favorable elongation of 5.7%. The mechanisms responsible for grain refinement in the weld nugget zone involve plastic deformation and dynamic recrystallization. Significantly, the disruptive effects of friction-stir action on eutectic silicon phases and rich iron phases emerge as crucial factors contributing to the enhanced performance of the weld nugget zone in the welded joint.