Research On Production Process And Welding Property Of Al-12.7Si-0.7Mg Aluminium Welding Wire

Mg-containing Al-Si alloy is a novel wrought aluminium-silicon alloy with high strength and toughness. However, little research has been carried out on the weldability and special welding wire of it.Al-12.7Si-0.7Mg welding wire is prepared by semi-continuous casting, hot extrusion, and cold drawing processes in this thesis. Then we investigate microstructure and mechanical properties of these welded joints using the selfmade welding wire by microstructure observation, microhardness measurement and tensile test. All of these analysis and investigation provide the basis for improving production processes of aluminium welding wire and optimizing heat treatment parameters of welded joints.The results show that:1. All of selfmade Al-12.7Si-0.7Mg welding wires((?)3.1mm,(?)2.5mm,(?)1.6mm and (?)1.2mm) have a smooth finish, uniform composition and homogeneous microstructure by semi-continuous casting, hot extrusion and cold drawing processes.2. Before heat treatment, tensile strength and elongation of Al-12.7Si-0.7Mg welded joints are189MPa and7.73%, respectively. While that of ER4047welded joints are187MPa and7.84%. All properties reach over90%of that of the base material and are certainly excellent.3. The microhardness of welded joints using both Al-12.7Si-0.7Mg and ER4047welding wires increases significantly after solid solution and the following artifical aging heat treatment, and the microhardness in the welding zone of Al-12.7Si-0.7Mg welded joints is higher than that of ER4047welded joints.4. The best tensile property of Al-12.7Si-0.7Mg welded joints appear after solid-solution at540℃for1.5hour and artificial aging at180℃for3hours, the tensile strength is376MPa and elongation is7.73%. while that of ER4047welded joints appeare after solid-solution at520℃for1.5hour and aging at180℃for3hours, the tensile strength is347MPa and elongation is4.11%. The properties of Al-12.7Si-0.7Mg welded joints are much better than that of ER4047welded joints after solid-solution and artificial aging heat treatment.