Optimization of HPVP-GTAW process parameters for Al-Mg aluminum alloy welded joints

Optimization of hybrid ultrahigh frequency pulse variable polarity gas tungsten arc welding (HPVP-GTAW) process was carried out to obtain the optimum weld characteristics of 5A06-HX4 aluminum-magnesium alloy sheets of 3 mm thickness. The square butt joints were produced by HPVP-GTAW process, the microstructure and mechanical properties were systematically investigated. It is observed that the process parameters influence the weld microstructure and mechanical properties significantly. Weld microstructure is mainly composed of grid α(Al) solid solution, with a large number of intermetallic β(Mg₂Al₃) precipitates distributed in the matrix. The amount of β(Mg₂Al₃) precipitates has an obvious difference with different parameters. Compared with that of the base material, tensile strength of 5A06-HX4 alloy welded joints has a certain reduction, as well as the elongation and reduction of area. The optimized welding process parameters for 5A06-HX4 alloy sheets are presented.