Microstructure and Mechanical Properties of Al-12.7Si-0.7Mg Alloy Welded Joints Using Homogeneous Welding Wire

A novel Al-12.7Si-0.7Mg welding wire was successfully produced via DC casting, extrusion, roll die drawing and hole die drawing. An investigation was performed on the microstructure and mechanical properties of the welded joints using the as-produced special filler wire in different solid solution and artificial aging treatment conditions. The results showed that the as-produced Al-12.7Si-0.7Mg welding wire was an ideal special wire of the Al-12.7Si-0.7Mg wrought alloy and the homogeneous welded joints proved to be heat-treatable. Solid solution treatment and artificial aging treatment had significant influence on the microstructure, microhardness and tensile properties of the as-welded joints. A transformation of microstructures from a coarse structure to a fine structure occurred in the welded joints after the heat treatment. The microhardness and the strength of the joints increased remarkably as the solution temperature and aging time increased.