6005A-T6铝合金搅拌摩擦焊接头微观组织及耐应力腐蚀性能

利用光学显微镜、透射电镜以及四点弯曲应力腐蚀方法研究6005A-T6铝合金搅拌摩擦焊接头的微观组织及其应力腐蚀性能。结果表明,6005A-T6铝合金搅拌摩擦焊接头硬度分布呈“W”型,其中热影响区的硬度最低,焊核区的硬度有所升高,母材硬度最高;铝合金母材的主要强化相为含铜Q'相,而焊核区大部分强化相消失,存在大量位错,主要强化机制为细晶强化、位错强化和固溶强化;搅拌摩擦焊接头表现出良好的抗应力腐蚀性能,但仍出现点蚀现象,其中热影响区为接头耐蚀性的薄弱部位。

Microstructure and stress corrosion resistance of 6005A-T6 aluminum alloy joints by friction stir welding

The microstructure and stress corrosion resistance of 6005A-T6 aluminum alloy joints by friction stir welding were studied using optical microscope,scanning electron microscope and four points bending stress corrosion methods. The results show that the hardness distribution of the joint is W-shape,the lowest hardness appears at the heat affected zone,and the hardness is improved at the weld nugget zone,and the highest hardness appears at the base metal. The main strengthening phase of the base metal is Q' phase,most of which is disappeared at the weld nugget zone,and where exists lots of dislocation and the main strengthening mechanism is fine grain strengthening,dislocation strengthening and solid solution strengthening. Friction stir welded joint shows good stress corrosion resista-nce,however corrosive pitting is also happened,and the weakest part of the welded joint is in the heat affected zone.