异种铝合金电阻点焊接头的组织及性能

Microstructure and properties of resistance spot welded joint of dissimilar aluminum alloys

采用电阻点焊工艺对厚度为2 mm的5182铝合金和5754铝合金进行搭接焊,并使用金相显微镜观察其显微组织特点,使用拉伸试验机和维氏显微硬度仪测试焊接接头的力学性能。结果表明,焊接接头由3个典型区域组成:母材区、热影响区和熔核区;熔核区主要由边缘柱状晶和中心等轴晶组成,中心等轴晶区体积约占整个熔核区的90%。5182铝合金侧的热影响区出现较多大颗粒析出物,并出现液化裂纹,5754铝合金侧的热影响区无明显的析出物与液化裂纹产生。焊接接头的断裂形式为纽扣型断裂,均为5754铝合金侧的熔核被剥离。熔核中柱状晶区硬度高于等轴晶区,位于两种铝合金侧的热影响区硬度均高于其对应的母材硬度。

The resistance spot welding process was used to overlap weld 5182 aluminum alloy and 5754 aluminum alloy with a thickness of 2 mm.The metallurgical characteristics were observed with a metallurgical microscope.And the mechanical properties are tested by the tensile tester and the microhardness tester.The results showed that the welded joint was composed of three typical zones,base metal,heat affected zone and nugget zone.The nugget zone of the welded joints mainly consisted of edge columnar grains and central equiaxed grains,and the volume of central equiaxed crystal zone accounts for about 90%of the entire nugget zone.In the heat affected zone of 5182 aluminum alloy,there appeared many large precipitates and liquefied cracks.However,there existed no obvious precipitates and liquefied cracks in the heat affected zone of 5754 aluminum alloy.The fracture form of the welded joint was a button fracture,and the nuggets on the 5754 aluminum alloy side were peeled off.The hardness of the columnar zone in the nugget was higher than that of the equiaxed crystal zone,and the hardness of the heat-affected zone on both aluminum alloys was higher than that of the corresponding base metal.