Effect of welding current on welding joint of AZ31 magnesium alloy

In order to study the weldability of AZ31 magnesium alloy,AC tungsten inert gas welding (TIG) was conducted for the AZ31 magnesium alloy plate. The microstructure of the welding seam was analyzed using x-ray diffractometer,scanning electron microscope and optical microscope. In addition,the hardness and ultimate tensile strength of the samples obtained with different welding current were determined. The results show that with an increase in welding current,the formability of welding seam becomes worse and the grains get coarsed. At the same time,both gas porosity and crack are easy to generate,which will reduce the properties of the joint. The microstructure of the welding seam is composed of α-Mg matrix and β-Al12Mg17phase. It is also noted that the welding current significantly influences the shape of molten pool and the welding quality of welding joint.