(1. 浙江工業(yè)大學(xué) 機械工程學(xué)院，杭州 310023；
2. 北京航空航天大學(xué) 固體力學(xué)研究所，北京 100191；
3. 愛勵鋁業(yè)有限公司，鎮(zhèn)江 212000)
摘 要: 在自然冷卻和壓縮空氣強制冷卻條件下，攪拌摩擦對接焊接5A06-H112和6061-T651異種鋁合金，借助單軸拉伸、納米壓入和顯微觀測手段，研究熱輸入對接頭拉伸斷裂特征的影響規(guī)律，揭示其影響機制。結(jié)果表明：當(dāng)轉(zhuǎn)速焊速比(γ)為1.5 r/mm(熱輸入過低)時，焊核區(qū)材料因混合不充分形成S線缺陷，導(dǎo)致接頭沿此缺陷在焊核區(qū)發(fā)生脆性斷裂；當(dāng)轉(zhuǎn)速焊速比達到3.0 r/mm后，焊核區(qū)材料混合充分，韌性斷裂均發(fā)生在6061側(cè)的熱影響區(qū)。隨著熱輸入增加，斷裂角度由41°逐漸減小至3°，斷裂類型由切斷斷裂演化成正斷斷裂。納米壓入硬度分布顯示6061側(cè)的熱影響區(qū)為接頭的弱化區(qū)域，該區(qū)域的寬度和傾角直接影響斷裂角度。斷口微觀形貌分析表明，抑制熱輸入有助于增大斷裂角度，使接頭以切斷斷裂為主，從而產(chǎn)生更多剪切韌窩，提高接頭的斷裂伸長率。
關(guān)鍵字: 5A06鋁合金；6061鋁合金；攪拌摩擦焊；熱輸入；斷裂角度
（1. College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou 310023, China;
2. Institute of Solid Mechanics, Beihang University, Beijing 100191, China;
3. Aleris Co., Ltd., Zhenjiang 212000, China）
Abstract:To investigate the influence of heat input on the fracture behavior of the joints, the 5A06-H112 and 6061-T651 aluminum alloys were friction stir welded in both nature cooling and forced air cooling. When the ratio of rotational speed to transverse speed is 1.5 r/mm, the materials in the nugget zone were insufficiently mixed to form a kissing bond, resulting in brittle fracture along this defect. As the ratio reaches 3.0 r/mm, the materials in the nugget zone were well mixed, and ductile fracture occurs in the heat affected zone of 6061 aluminum alloy. With the increase of heat input, the fracture angle gradually decreases from 41° to 3°, and the fracture mechanism changes from shear fracture to normal fracture. The distribution of nanoindentation hardness of the FSW joints indicates that the heat affected zone of 6061 aluminum alloy is the weakest area, and the fracture angle of the joint is directly influenced by the width and angle of this weakened area. SEM images of the fracture surface reveal that supressing the heat input could increase the fracture angle and cause shear fracture, which is conducive to form more shear dimples on the fracture surfaces to improve the elongation of the joints.
Key words: 5A06 aluminum alloy; 6061 aluminum; friction stir welding; heat input; fracture angle
