(1. 蘭州理工大學(xué) 甘肅省有色金屬新材料國(guó)家重點(diǎn)實(shí)驗(yàn)室，蘭州 730050；
2. 蘭州理工大學(xué) 材料科學(xué)與工程學(xué)院，蘭州 730050)
摘 要: 對(duì)航空用厚5 mm的7075鋁合金攪拌摩擦焊試樣熱處理前后的焊縫微觀組織及性能進(jìn)行研究。結(jié)果表 明：當(dāng)攪拌頭旋轉(zhuǎn)速度為600 r/min、焊接速度為60 mm/min時(shí)，接頭抗拉強(qiáng)度達(dá)到381 MPa，是母材強(qiáng)度的84.6%；焊核區(qū)由6~7 μm等軸晶組成；經(jīng)熱處理后接頭抗拉強(qiáng)度達(dá)到415 MPa；硬度的最低處在前進(jìn)側(cè)熱機(jī)影響區(qū)；斷口的微觀形貌具有強(qiáng)化相的韌窩特征，且斷裂幾乎發(fā)生在前進(jìn)側(cè)的熱機(jī)影響區(qū)；7075鋁合金攪拌摩擦焊接頭的薄弱點(diǎn)在熱機(jī)影響區(qū)。
關(guān)鍵字: 7075鋁合金；攪拌摩擦焊；微觀組織
friction stir welding joints of high-strength aluminum alloy
（1. State Key Laboratory of Advanced Non-ferrous Metal Materials, Gansu Province,
Lanzhou University of Technology, Lanzhou 730050, China;
2. School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050, China）
Abstract: The microstructure and property before and after heat treatment of friction stir welded 5 mm aero 7075 aluminum alloy were investigated. The results show that when the rotating speed of stirring joint is 600 r/min and the welding speed is 60 mm/min, the tensile strength can reach 381 MPa that is 84.6% of the base metals, which are regarded as the most ideal parameters under experimental conditions. There are equiaxed grains with size of 6−7 μm in weld nugget. After heat treatment, the tensile strength can reach 415 MPa. The lowest hardness appears in thermomechanically affected zone (TMAZ) of advancing side. The fractography has a characteristic of dimples of strengthening phase and the strain fracture appears in TMAZ of advancing side of joints. The weak point of friction stir welding joint for 7075 aluminum alloy occurs in the TMAZ.
Key words: 7075 aluminum alloy; friction stir welding; microstructure
