The Microstructures, Properties And Welding Experiment Of Welding Wires Prepared From Mg-Al Eutectic And AZ91D Magnesium Alloys

In this paper the Mg-Al eutectic and AZ91D magnesium alloy welding wires were prepared by Ohno Continuous Casting (OCC) equipment and extrusion device, respectively. The effect of processing parameters on the wires preparing processes were investigated and moreover, rational parameters to prepare the wires were obtained. The mechanical properties and thermal expansion coefficient of wires were tested by tensile and thermal mechanical analysis apparatus. The microstructure and fractography of wires were investigated by optical microscope and scanning electronic microscope (SEM). The Mg-Al eutectic and AZ91D magnesium alloy welding wires as padding were used to weld magnesium plates by using TIG (Gas Tungsten Arc Welding-GTAW) method. The results indicate that the Mg-Al eutectic magnesium alloy welding wires with columnar eutectic (α-Mg+β-Mg17Al12) microstructure and smooth mirror-like surface are prepared at follow condition, i.e. fusant temperature 580℃, the outlet mould temperature 440℃,drawing velocity with 10mm/min, the cooling distance with 20mm, the flowmeter water with 30L/h, the height of liquid level with 8mm. Theφ3mm,φ4mm AZ91D magnesium alloy welding wires prepared at different extrusion temperatures with 420℃,440℃,460℃and 475℃are consisted ofα-Mg solid solution and eutectic (α-Mg+β-Mg17Al12) with smooth surface. With those weld wires, sound welding joints are achieved with refined microstructure and good properties.