Al-0.6Mg-0.6Si铝合金MIG焊接接头显微组织与微区成分研究

Research on Microstructure and Micro-area Composition MIG Joint of Al-0.6Mg-0.6Si Aluminum Alloy

对轨道车辆用新型Al-0.6Mg-0.6Si铝合金进行了熔化极隋性气体保护(MIG)焊接,利用光学金相(OM)、能谱(EDAX)分析等测试手段,对焊接接头的显微组织与微区成分(质量分数)进行了分析.结果表明:采用MIG焊接方法能够获得成形良好的接头,焊缝中心结晶形成典型铸态组织,但易于偏聚形成显微夹杂,靠近熔合线的焊缝逐渐由焊缝边缘的柱状晶过渡到枝状晶.熔合线附近的焊缝边缘易于形成Si偏析带,Al-0.6Mg-0.6Si基体组织的质量比m(Mg)∶m(Si)≈1.04∶1,焊缝中心Mg元素受电弧高温烧损,Mg含量(质量分数)为3.08%.

The Al-0.6 Mg-0.6Si alloy used in the rail vehicle was welded by MIG welding. The micro- structure and micro-area compositions of the welding joint were analyzed and characterized by OM and EDAX methods. The results of the experiment show that a good appearance of the welding joint can be obtained by MIG. There are typical as-cast microstructures in the center area of welding seam. The micro-inclusions are easy to cluster in the welding seam. The columnar dendritic grains transform gradually into eguiaxial structure from near the fusion line to the welding seam center. The Si segragation zone are easy to form in the edge of welding seam near the fusion line. The mass ratio Mg/Si is about 1.04 in the matrix structure of Al-0.6Mg-0.6Si alloy. Because some Mg element was lost due to high arc temperature,the Mg content in the welding metal is 3.08%.