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对3mm厚铸态镁合金进行TIG焊研究,采用交流、双面焊接,其正面焊接电流为120A,背面焊接电流分别为80、90、100A,焊接速度和保护气体流量不变,焊接完成后按照标准程序对焊缝取样,用光学显微镜观察焊接接头的微观组织。分析表明:焊缝表面成形不好,焊缝表面存在明显缺陷;随着背面焊接电流的增加,焊缝中网状β-Mg17Al12相减少,而颗粒状的β-Mg17Al12相增多。
TIG welding of 3mm thick as-cast magnesium alloy was carried out. The front welding current was 120A and the back welding current was 80, 90 and 100A respectively. The welding speed and shielding gas flow rate were unchanged. After the welding was completed, The standard procedure was to sample the weld and observe the microstructure of the welded joint with a light microscope. The results show that the weld surface is not well formed and there are obvious defects on the weld surface. With the increase of welding current on the back surface, the amount of β-Mg17Al12 phase decreases and the amount of granular β-Mg17Al12 phase increases.