Cooling effect on microstructure and mechanical properties during friction stir welding of Al-Mg-Si aluminum alloys

Strength drop after welding of Al-Mg-Si aluminum alloys has been a crucial issue in industrial applications. Friction stir welding combined with a cooling system was carried out, and microstructure and mechanical properties of the welded Al-Mg-Si alloys were examined. Welding with cooling increased yield strength and decreased elongation of Al-Mg-Si alloys. Tensile strength and overall grain size of the welded zone varied with welding speed. The width of the welded zone based on hardness distribution clearly depended on welding speed. Overall, hardness dropped with coolant.