AZ31B镁合金电子束焊接接头组织及性能分析

Microstructure and properties of electron beam welded joints of AZ31B magnesium alloy

关键词:  电子束焊  AZ31B镁合金  力学性能  显微组织

Key words:  electron beam welding  AZ31B magnesium alloy  mechanical property  microstructure

摘要:

采用电子束焊接方法对10 mm厚的AZ31B镁合金进行焊接。利用光学显微镜、扫描电镜、射线衍射仪等手段分析了电子束焊接接头的外观和截面的特征、显微组织、元素分布、焊缝物相和断口形貌等,并利用维氏硬度仪和拉伸仪检测了接头区域硬度和接头强度。结果表明,采用电子束焊接AZ31B镁合金获得的焊缝正面成形美观,而背部存在轻微的凹陷,焊缝深宽比在8:1以上;与基体相比,焊缝中Mg,Zn比例下降,Al,Mn比例上升;焊缝中主要物相为Mg,Al和少量的Mg₁₇Al₁₂相;焊缝热影响区窄,焊缝组织为8~18μm的细小等轴晶粒;焊接接头硬度值均匀;焊缝抗拉强度均值为223 MPa,断裂部位为焊缝区,断口为混合断裂形貌。

Abstract:

10 mm thick AZ31B magnesium alloy was welded by the electron beam welding.The appearance, the macrophotograph, the microstructure, the alloy elements profile, the patterns and etc of welded joint were analyzed by means of OM, SEM, X-ray diffraction and etc.The results show that the appearance in the face of weld is perfect and the appearance in the back of weld has many tiny cupped hole.The ratio of the depth of fusion to the weld width is 8:1.The proportion of Al and Mn element has increased, and Mg, Zn has decreased in the welding zone.There are Mg, Al and a little Mg₁₇Al₁₂ in the welding zonewhere there are columnar grains of 8-18 μm.Hardness of the welding joint is almost uniformity.The strenghth of welding joint is 223 MPa.