The AZ31 and AZ61 plates in 3 mm thick plates are welded with AZ31 and AZ61 welding wires by TIG method. The influence of welding wires on the strength of welded joints of AZ31 and AZ61 magnesium alloy plates was investigated. The appearance shape, microstructure and patterns of welded joints were analyzed as well as the mechanical properties test by means of OM, SEM, X-ray diffraction and etc. The result showed that the appearance shape was good with weather AZ31 or AZ61 welding wire. The welded zone was identified to be composed of α-Mg and β-Mg17Al12 phases.The heat affected zones exist both in AZ31 and AZ61 joints, with grains coarser than base metal. Relative to AZ61 welding wire, using the AZ31 welding wire tends to get a coarse grain region of little width, and a fracture point closer to the center line of welding seam, with tensile fracture strength of 161MPa leading to a 64％ strength of the AZ31 base metal. With the AZ61welding wire, a coarse grain region of more width and a fracture point a little far from the center line are happened, the strength of the joints reaches to 210MPa, 84％ of that of its AZ31 base metal.%采用TIG焊对AZ31与AZ61镁合金薄板进行连接,分别采用了AZ31和AZ61焊丝,比较焊接效果的影响.通过显微镜、扫描电镜、X-ray物相检测等实验方法,分析了两种焊丝焊接接头的外观形貌、显微组织、焊缝析出相及力学性能等差异.研究结果表明:采用AZ31和AZ61两种焊丝都能完成AZ31与AZ61镁合金薄板的对焊,获得无缺陷的焊接接头;焊缝区均存在α-Mg和β-Mg17Al12两种相,两侧母材存在热影响区,靠近焊缝处晶粒粗化,但AZ31侧晶粒粗化比AZ61侧明显.采用AZ31焊丝与采用AZ61焊丝相比,AZ31母材侧的粗晶区宽度更窄,断裂处更靠近中心线,强度为161MPa,达到AZ31挤压板母材的64%左右;AZ61焊丝的焊接接头平均强度为210MPa,可达到AZ31母材的84%.
展开▼
