(1．中南大學材料科學與工程學院，長沙 410083；
2．中南大學材料科學與工程學院有色金屬材料科學與工程教育部重點實驗室，長沙 410083；
3．中南大學粉末冶金研究院粉末冶金國家重點實驗室，長沙 410083)
摘 要: 通過硬度測試、極化曲線測試、腐蝕浸泡和慢應變速率拉伸方法研究Al-Zn-Mg-Sc-Zr合金板材攪拌摩擦焊接接頭的力學性能和局部腐蝕性能，并利用金相顯微鏡和透射電鏡對焊接接頭的顯微組織進行分析。結果表明：焊接接頭的硬度曲線呈現W型，硬度最低值出現在熱影響區(qū)與熱機影響區(qū)的交界處；和母材相比，焊接接頭的局部抗腐蝕性能降低，應力腐蝕敏感性增大。熱機影響區(qū)的腐蝕電位最低，腐蝕電流密度最高，晶間腐蝕深度最大，抗腐蝕性能最差。熱機影響區(qū)的硬度和腐蝕性能的降低，主要是由于該區(qū)的晶粒發(fā)生變形，大部分η′沉淀強化相溶解，晶界上分布著大量的η相。
關鍵字: Al-Zn-Mg-Sc-Zr合金；攪拌摩擦焊接；顯微組織；力學性能；局部腐蝕
（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
