Al-Cu-Mg硬铝合金TIG焊焊接接头的组织与力学性能

为了研究Al-Cu-Mg硬铝合金TIG焊焊接接头的组织与力学性能,采用ER4043焊丝对2A12硬铝合金进行了焊接实验.利用光学显微镜、扫描电子显微镜、透射电子显微镜、能谱分析仪和硬度计对Al-Cu-Mg硬铝合金的组织和力学性能进行了表征.结果表明,焊缝的强度和塑性较低,焊缝边缘为柱状晶,中心为枝晶组织,晶界存在大量低熔点共晶体.近缝区存在明显的晶界液化现象,晶粒为圆润的等轴晶,焊缝的硬度大幅度下降.固溶区焊缝的硬度和母材相近,基体中存在大量的针状S'相,可对该区域起到强化作用.过时效区基体软化现象比较严重,存在很多S(Al2Cu M g)相.

Microstructure and mechanical properties of TIG welded joint of Al-Cu-Mg aluminum alloy

In order to study the microstructure and mechanical properties of TIG welded joint of Al-Cu-Mg aluminum alloy, the welding tests for 2A12 aluminum alloy were performed with ER4043 welding wire. The mechanical properties of Al-Cu-Mg aluminum alloy were characterized with optical microscope(OM), scanning electron microscope(SEM), transmission electron microscope(TEM), energy dispersive spectrometer(EDS)and hardness tester. The results show that the strength and plasticity of welding seam is low, the grains in the edge of welding seam are columnar while the grains in the center are isometric, and there are a large number of low-melting-point eutectics at the gain boundaries. In the zone close to the welding seam, the obvious grain boundary liquation phenomenon appears, the grains are rounded isometric ones, and the hardness of welding seam greatly reduces. In the solid solution zone, the hardness of welding seam is close to that of base metal, and there are a lot of acicular S′ phase in the matrix which can play a strengthening role for the zone. In the overaging zone, the matrix softening phenomenon is serious, and there are a lot of S(Al₂CuMg)phase.