2219铝合金双轴肩搅拌摩擦焊与熔焊交叉接头的组织及性能

Microstructure and Mechanical Properties of 2219 Aluminum Alloy Cross-Welded Joints Made by Self-Reacting Friction Stir Welding and TIG Welding

文摘对2219C10S铝合金进行双轴肩搅拌摩擦焊接,之后沿垂直于双轴肩搅拌摩擦焊方向进行变极性TIG焊接制备交叉接头,并对比分析了交叉接头与单一TIG接头的组织和力学性能。交叉接头与单一TIG接头的组织特征既有相同之处也存在差异。相同之处为焊缝区均由直流氦弧焊作用下的柱状区和交流脉冲氩弧焊作用下的碗状区组成;不同之处在于两者的母材区分别为细小等轴晶和轧制板条晶粒,而热影响区都是在母材晶粒上发生粗化长大。显微硬度测试结果表明,两类接头的横截面显微硬度分布均呈"W"型,单一TIG接头的的显微硬度分布梯度大于交叉接头,但交叉接头的软化区宽度更窄。拉伸测试结果得出,两类接头均断裂于接头的热影响区。沿SR-FSW焊缝方向的交叉接头的抗拉强度系数为66.14%,略低于单一TIG接头,但接头延伸率比单一TIG接头高约30%。断口形貌研究表明,交叉接头的断口形貌为典型的韧性断裂,而单一TIG接头还可观察到部分脆性断裂特征。

The 2219C10S aluminium alloy is first subjected to self-reacting friction stir welding,followed by TIG welding in the direction perpendicular to the friction stir welding,and then the cross-weld joint is made. In this paper the microstructure and mechanical properties of the cross-welded joint and TIG joint are comparatively analyzed. The microstructural characteristics of the two kinds of joints present similarities and differences. The similarities are that the weld zone of the two kinds of joints are all composed of the column section by the direct helium arc welding and the bowl area by AC pulse argon arc welding. The differences are that both the parent metal zones respectively are the small isometric grains and rolling plate strip grains,and the heat affected zones are coarsening on the basis of the parent metal zone. Microhardness test results show that the micohardness distribution trend of the two kinds of joints is ＂W＂type,and the microhardness distribution gradient of the TIG joints is greater than that of the cross joint which has a relatively narrower softened area. Tensile test results reveal that two types of joints are broken in the heat affected zone. The tensile strength factor of the cross joint in the SR-FSW direction is 66.14% which is slightly lower than the TIG joints,while the elongation rate of the former is about 30% higher than that of the latter. The fracture surface of the cross joint is typically ductile fracture,and the TIG joint has some brittle fracture characteristics besides the ductile fracture characteristics.