(1．中南大學(xué) 材料科學(xué)與工程學(xué)院，長沙 410083；
2．中南大學(xué) 有色金屬材料科學(xué)與工程教育部重點實驗室，長沙 410083；
3．中南大學(xué) 粉末冶金國家重點實驗室，長沙 410083)
摘 要: 采用硬度測試、金相顯微、透射電鏡、慢應(yīng)變速率拉伸、掃描電鏡和極化曲線對2 mm厚Al-Mg-Mn-Sc-Zr冷軋-退火板材攪拌摩擦焊接頭的顯微組織、力學(xué)性能及腐蝕性能進行了研究。結(jié)果表明：焊接接頭的硬度相比母材有所降低，硬度最低值出現(xiàn)在前進側(cè)攪拌區(qū)與熱機影響區(qū)的交界處；焊接接頭在空氣中和3.5% NaCl(質(zhì)量分數(shù))溶液中的抗拉強度和伸長率均低于母材的，且應(yīng)力腐蝕敏感性增加。此外，在焊接接頭中，熱機影響區(qū)是耐蝕性最差的區(qū)域，但是在空氣和3.5% NaCl溶液中的拉伸試樣均斷裂在厚度最薄的攪拌區(qū)而不是耐蝕性最差的熱機影響區(qū)，可見應(yīng)力腐蝕對試樣斷裂的影響有限，說明Al-Mg-Mn-Sc-Zr合金攪拌摩擦焊接頭具有較好的抗應(yīng)力腐蝕性。
關(guān)鍵字: Al-Mg-Mn-Sc-Zr合金；攪拌摩擦焊；應(yīng)力腐蝕；顯微組織；力學(xué)性能
（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, Central South University, Changsha 410083, China;
3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The microstructure, mechanical properties and corrosion properties of friction stir welded (FSW) Al-Mg-Mn-Sc-Zr alloy were studied by hardness test, optical microscope (OM) analysis，transmission electron microscope (TEM) analysis，slow-strain-rate tensile (SSRT) test, scanning electron microscope (SEM) analysis and polarisation curve testing. The results show that the microhardness of FSW joint is lower than that of the base metal (BM), and the lowest hardness appears in the thermo-mechanical affected zone (TMAZ). Moreover, according to the SSRT test, the tensile strength and elongation of FSW joint are lower than those of the BM both in air and in 3.5%NaCl (mass fraction) solution. The polarization curve results reveal that the TMAZ exhibits lowest corrosion resistance, the samples are subjected to slow strain rate stretching in air or in 3.5% NaCl (mass fraction) solution, the fracture area is always observed in the thinnest stirred zone (SZ) rather than the TMAZ with worst corrosion resistance. It can be concluded that the stress corrosion does not dominant the cracking, and the friction stir welded Al-Zn-Mg-Sc-Zr alloy exhibits preferable stress corrosion resistance.
Key words: Al-Mg-Mn-Sc-Zr alloy; friction stir welding; stress corrosion cracking; microstructure; mechanical property
