(1. 山東大學(xué) 材料液固結(jié)構(gòu)演變與加工教育部重點實驗室，濟南 250061；
2. 國網(wǎng)河南省電力公司 電力科學(xué)研究院，鄭州 450052；
3. 齊魯工業(yè)大學(xué)（山東省科學(xué)院） 機械與汽車工程學(xué)院，濟南 250353)
摘 要: 對12 mm厚的1060純鋁與T2紫銅進行了雙面攪拌摩擦焊接，研究了焊接速度對焊縫成形與接頭力學(xué)性能的影響。結(jié)果表明：在攪拌頭轉(zhuǎn)速為600 r/min的條件下，當(dāng)焊接速度為30~50 mm/min時，焊接速度對接頭力學(xué)性能影響較小，接頭均斷裂于鋁母材一側(cè)；當(dāng)焊接速度為30 mm/min時，獲得了無缺陷的焊接接頭；當(dāng)焊接速度為40~50 mm/min時，接頭出現(xiàn)扁平狀小孔洞缺陷，此時，由于攪入焊縫的銅與鋁混合形成復(fù)合材料結(jié)構(gòu)，增強了焊縫性能，因此，其接頭強度仍高于純鋁母材的；當(dāng)焊接速度超過60 mm/min時，熱輸入降低引起材料流動不足，在接頭內(nèi)形成貫穿焊縫的孔洞缺陷，使接頭承載面積減小，抗拉強度降低。攪拌區(qū)中部受到攪拌頭兩次熱力攪拌作用，硬度最高。此外，由于第一道焊縫引起工件變形，在相同下壓量的情況下，第二道焊縫相對于第一道焊縫壓力略低、熱輸入較小，使得焊縫底部(即第二道焊縫)的硬度低于焊縫上部(即第一道焊縫)的，且第二道焊縫更易出現(xiàn)孔洞缺陷。綜合考慮焊接效率和接頭性能，50 mm/min為最優(yōu)焊接速度，此時接頭性能與鋁母材的相當(dāng)，抗拉強度為75.6 MPa，伸長率為26%。
關(guān)鍵字: 鋁/銅異種焊接；雙面攪拌摩擦焊；焊縫成形；力學(xué)性能；焊接速度
（1. Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (MOE), Shandong University, Jinan 250061, China;
2. Electric Power Research Institute of State Grid Henan Electric Power Company, Zhengzhou 450052, China;
3. School of Mechanical & Automotive Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China）
Abstract:12 mm medium-thick pure aluminum and T2 copper were welded by double-side friction stir welding, and the effects of welding speeds on weld formation and mechanical properties of the joint were studied. The results show that the welding speed has little effect on the mechanical properties of the joints when the tool rotational speed is fixed at 600 r/min and the welding speed is 30-50 mm/min, all the joints are fractured on the base material of aluminum. The defect-free welded joints are obtained at the welding speed of 30 mm/min. While the welding speed is 40-50 mm/min, some flat small void defects appear in the joints. However, the joint properties are still higher than that of the pure aluminum due to the copper mixed with the aluminum in the weld which forms a composite structure and enhances the joint properties. When the welding speed is higher than 60 mm/min, the heat input is decreased, which causes the insufficient material flow and forms a void defect through the weld, reduces the load-bearing area of the joint and decreases the tensile strength of joint. The hardness is highest in the middle of the stirring zone, which is twice thermally stirred by the tool. Furthermore, due to the welding distortion caused by the first-pass welding, the second-pass weld has a slightly lower downforce and less heat input than the first-pass weld at the same plunge depth, making the hardness at the bottom of the weld (i.e. the second-pass weld) is less than that at the top of the weld (i.e. the first-pass weld), and the second-pass weld is more likely to form void defects. Considering both the welding efficiency and joint properties, the optimum welding speed is 50 mm/min. The joint performance is comparable to the base metal of aluminum, the optimum tensile strength of 75.6 MPa and elongation of 26% are achieved at the welding speed of 50 mm/min.
Key words: Al/Cu dissimilar welding; double-side friction stir welding; weld formation; mechanical property; welding speed
