(1．中南大学材料科学与工程学院，长沙 410083；
2．中南大学材料科学与工程学院有色金属材料科学与工程教育部重点实验室，长沙 410083；
3．中南大学粉末冶金研究院粉末冶金国家重点实验室，长沙 410083)
摘 要: 通过硬度测试、极化曲线测试、腐蚀浸泡和慢应变速率拉伸方法研究Al-Zn-Mg-Sc-Zr合金板材搅拌摩擦焊接接头的力学性能和局部腐蚀性能，并利用金相显微镜和透射电镜对焊接接头的显微组织进行分析。结果表明：焊接接头的硬度曲线呈现W型，硬度最低值出现在热影响区与热机影响区的交界处；和母材相比，焊接接头的局部抗腐蚀性能降低，应力腐蚀敏感性增大。热机影响区的腐蚀电位最低，腐蚀电流密度最高，晶间腐蚀深度最大，抗腐蚀性能最差。热机影响区的硬度和腐蚀性能的降低，主要是由于该区的晶粒发生变形，大部分η′沉淀强化相溶解，晶界上分布着大量的η相。
关键字: Al-Zn-Mg-Sc-Zr合金；搅拌摩擦焊接；显微组织；力学性能；局部腐蚀
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education,
School of Material Science and Engineering, Central South University, Changsha 410083, China;
3. State Key Laboratory of Powder Metallurgy, Research Institute of Powder Metallurgy,
Central South University, Changsha 410083, China）
Abstract:The mechanical properties and localized corrosion of Al-Zn-Mg-Sc-Zr alloy friction stir welded joint were investigated by hardness testing, polarization curve testing, corrosion immersion testing and slow strain rate tensile testing. Moreover, the microstructure of the welded joint was characterized by optical microscopy and the transmission electron microscopy. The results show that the hardness curve of the welded joint exhibits “W” shape, and the lowest hardness appears in the transition zone between heat affected zone(HAZ) and thermo-mechanical affected zone (TMAZ). Compared with the base material, the localized corrosion resistance of the welded joint decreases, and the stress corrosion cracking susceptibility increases. The TMAZ exhibits the lowest corrosion potential, the highest current density, the largest intergranular corrosion depth and the lowest corrosion resistance. During welding, mostη′phase dissolves and a number of ηphase is located at grain boundaries in the grains of TMAZ, which leads to the decrease of hardness and corrosion resistance.
Key words: Al-Zn-Mg-Sc-Zr alloy; friction stir welding; microstructure; mechanical property; localized corrosion
