7075铝合金MIG焊接头金相组织、力学性能和耐蚀性的应力敏感性

作为航空航天和轨道交通领域有竞争力的一类高强高硬铝合金,7系铝合金的焊接及其性能研究引发关注.以单面焊和双面焊7075铝合金为研究对象,对接头的金相组织、力学性能进行研究,并对其在不同应力下3.5％NaCl溶液中的耐蚀性进行对比分析.结果表明,与单面焊工艺相比,双面MIG焊接7075铝合金焊缝的金相组织更均匀细小,但两...

Microstructure,mechanical properties and stress dependence of corrosion resistance for MIG welded 7075 aluminum joint

As a competitive high-strength and high-hardness aluminum alloy in field of aerospace and rail transit, 7 series aluminum alloy and its welding performance have attracted attention. The microstructure and mechanical properties of single-side and double-side welded 7075 aluminum alloy joints were studied, and the corrosion resistance of the joints under different stresses in 3.5% NaCl solution was compared and analyzed. The result shows that, double-side MIG welding of 7075 aluminum alloy brings about more uniform microstructure and finer grain, but equivalent mechanical properties with the fracture at the weld in comparison with single-side MIG welding. The corrosion resistance of the near-weld zone for both single-side and double-side welding is higher than that of the weld and far away from the weld. In addition, double-side welding improves the corrosion resistance of the joint. Under the action of the applied stress, the steady-state passivation and activation processes of the specimen are destroyed, which results in the multiple anodic polarization actions in the process of potentiodynamic polarization. The corrosion process is thus affected by the coupling effects of stress, corrosion potential and other factors.