ＡＺ３１マグネシウム合金ＴＩＧ溶接継手の諸性質

Abstract

AZ31 magnesium alloy plates 4mm in thickness were welded without addition of filler wire using a pulsed AC TIG welding machine. Microstructural observations have been carried out together with the mechanical tests on the welded joints, with the special reference to the effects of pulse frequency on the optimum welding conditions. In case of the pulse frequency of 20Hz, the crystal grains of the fusion zone are most fine. The hardness of the fusion zone of welded joints are nearly equal to that of the base metal. The welded joints without pulse have the same tensile strength and elongation as those of the base metal. The highest tensile strength and elongation of pulsed welded joints can be obtained with the pulse frequency of 20Hz, but they are inferior to those of the base metal. All the welded joints are fractured at the center of the fusion zone regardless of the pulse frequency. The bending angle of welded joints is smaller than that of the base metal. Fatigue limit of the welded joints with the pulse frequency of 20Hz is 92% of the base metal. And the fatigue limit of the pulse welded joints depends on the grain size of the fusion zone.