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采用与母材同质的焊丝对AZ31B镁合金板材进行手工钨极氩弧焊,利用专门设计的模具对镁合金熔焊接头进行423K弯曲变形试验,通过光学显微镜、扫描电镜及拉伸试验机等手段,研究了弯曲前、后的AZ31B镁合金熔焊接头的微观组织及力学性能。结果表明:AZ31B镁合金熔焊接头经423K弯曲变形后,焊缝区和热影响区都出现了一定的孪晶,接头热影响区铸态枝晶组织转变为细小的孪晶组织,孪生成为接头主要的变形机制;焊缝近表面处孪晶密度比中部密度大,焊缝及热影响区晶粒明显得到细化;接头抗拉强度由原先的178MPa增加至216MPa,伸长率由7%提高到9%。
Using the welding wire with the same base material on the AZ31B magnesium alloy plate for the manual TIG welding, the use of specially designed mold for welding of magnesium alloy 423K bending deformation test, through optical microscopy, scanning electron microscopy and tensile testing machine The microstructure and mechanical properties of AZ31B magnesium alloy fusion welded joints before and after bending were studied. The results show that some twins occur in the weld zone and the heat affected zone when the welded joint of AZ31B magnesium alloy is bent and deformed at 423K. The as-cast dendritic structure in the heat affected zone of the joint changes into fine twins and the twin becomes a joint The main deformation mechanism; twins density near the weld surface than the central density, weld and heat affected zone significantly refined grains; joint tensile strength from the original 178MPa increased 216MPa, elongation increased from 7% To 9%.