Effect of tool rotational and welding speeds on microstructural and mechanical characteristics of friction stir welded A319 cast Al alloy

The effect of the friction stir welding (FSW) parameters on the microstructure and mechanical characteristics of A319 cast Al alloy has been investigated. Plates from the investigated alloy were welded together under different tool rotational (omega) and welding (upsilon) speeds. The results showed the possibility of welding and obtaining sound joints from A319 cast Al alloy using FSW. The welded zones exhibited many advantages over the base material (BM) such as, lower porosity content, extra fine non-dendritic alpha-Al grains, and extra fine more homogeneously dispersed Si particles. The size of both alpha-Al grains and Si particles was found to be increase by increasing both tool rotational and welding speeds. The welded joints showed better mechanical properties than the BM. It has been found that increasing the tool rotational speed and/or the welding speed reduces both the tensile and yield strengths of the welded joints, however, they still higher than of the BM. In contrast, increasing the aforementioned speeds tends to increase the ductility of the welded joints.