(湖南大學(xué)汽車車身先進設(shè)計制造國家重點實驗室，長沙 410082)
摘 要: 對1.4 mm厚DP590雙相鋼和1.2 mm厚6016鋁合金平板試件進行有無膠層加入的激光搭接焊試驗，利用臥式金相顯微鏡、掃描電鏡(SEM)、背散射電子衍射技術(shù)(EBSD)、能譜儀(EDS)、顯微硬度分析儀和微機控制電子萬能試驗機等研究有無膠層輔助激光焊接頭焊縫區(qū)域的金相組織、斷口形貌、相分布及含量、晶粒大小、界面元素分布、顯微硬度與接頭力學(xué)性能。結(jié)果表明：在激光功率為1800 W、焊接速度為40 mm/s、離焦量為+2 mm、采用Ar為保護氣體且流量為15 L/min的條件下，添加膠層時，焊接試樣焊縫表面成形性良好，焊縫區(qū)無軟化組織生成，焊接接頭的平均剪切強度為41.33 MPa；與沒有添加膠層的相比，試樣的剪切強度提高1.44倍。添加膠層可增加焊縫熔深和熔寬，有利于鋼/鋁的焊合，鋼/鋁界面生成具有延性富Fe的Fe-Al化合物，均勻分布的晶粒有助于試件承受的外力均勻分布在焊接接頭的搭接區(qū)域，因而添加膠層對焊接接頭的力學(xué)性能有改善作用。
關(guān)鍵字: 激光焊接；鋼/鋁異種金屬；膠層；顯微組織；力學(xué)性能
（State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University, Changsha 410082, China）
Abstract:The fiber laser welding test with or without adhesive layer addition was carried out on the DP590 dual phase steel with thickness of 1.4mm and 6016 aluminum alloy with thickness of 1.2 mm. By horizontal metallographic microscopy, scanning electron microscopy, electron backscatter diffractometry, energy dispersive spectroscopy, the micro-hardness tester and microcomputer control electronic universal testing machine, the microstructure of the welded joint region, fracture morphology, distribution and content of phase, grain size, the distribution of interface elements and mechanical properties of welded joints were studied. The results show that the morphology of welding surface can be improved and softening microstructure of the weld zone does not form when the welding power is 1800 W, welding speed is 40 mm/s, the defocus distance is +2 mm, and Ar gas acts as the protection gas with flow rate of 15 L/min. The average shear strength of the welding sample with adhesive layer addition reaches 41.33 MPa. Compared with that without adhesive layer addition, the average shear strength of weld joint increases by 1.44 times. The increases of weld penetration and width by adding adhesive layer promote the combination of the steel and aluminum interface, Fe-rich Fe-Al intermetallic compounds has better ductility, the uniform size grains distribute in the region of the welded joint, which can improve the mechanical properties of welded joints with adhesive layer addition.
Key words: laser welding; steel/aluminum dissimilar metal; adhesive layer; microstructure; mechanical property
