变形镁合金TIG焊接头组织和力学性能研究
Microstructure and Mechanical Properties of TIG Welded Joints of AZ31B Magnesium Alloy
初雅杰1，2， 李晓泉2， 吴申庆1
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作者单位：（1.东南大学 材料科学与工程学院，江苏 南京 211189； 2.南京工程学院材料 工程学院，江苏 南京 211167）
中文关键字： 镁合金；接头组织；力学性能
英文关键字：magnesium alloy； welded joint； mechanical property
中文摘要：采用TIG焊、使用与母材同质的焊丝对4.6 mm厚的AZ31B变形镁合金进行焊接，利用金相显微镜、扫描电镜、显微硬度计、电子拉伸试验机等手段对焊接接头的显微组织、元素分布、断口形貌、接头硬度和强度等进行了分析。结果表明：焊缝区为细小的等轴晶，组织为 ?琢-Mg固溶体和网状分布的?茁-Mg17Al12金属间化合物；接头硬度分布不均匀，焊缝区最高，热影响区最低；焊缝区Mg元素烧损，Al含量较高；接头抗拉强度达到220 MPa，是母材的93%，断裂发生在热影响区，断口形貌为韧-脆混合断裂。
英文摘要：The AZ31B magnesium alloy with 4.6 mm thickness was welded with the same material by TIG welding. The microstructure feature, element distribution, appearance of the fracture, hardness and strength of welding joint were analyzed by OM, SEM, microhardness tester, tensile testing. The results show that there is a finely equiaxed crystal in the welded zone, consisting of solid solution and intermetallic compound. The hardness distribution of the welded joint is uniform, the welded zone is highest and the affected zone is lowest. Mg content decrease in the welding zone and the proportion of Al content increase. The strength of the welded joint is 220 MPa, 93% of the base metal. Tensile samples always fracture in heat affected zones and the microstructure is mixed fracture of ductility and brittle.