(湖南大學(xué) 汽車車身先進(jìn)設(shè)計制造國家重點實驗室，長沙 410082)
摘 要: 為了抑制或減少鍍鋅鋼/6016鋁合金在激光焊過程中生成Fe/Al脆性金屬間化合物，采用光纖激光器，不添加任何釬料，對汽車車身用鍍鋅鋼與6016鋁合金平板試件進(jìn)行激光搭接焊試驗。利用ANSYS有限元分析軟件，建立鋼/鋁激光焊熱源模型。基于模擬計算與溫度同步測量，獲取不同工藝條件下焊接熔深，將其作為訓(xùn)練樣本，利用BP神經(jīng)網(wǎng)絡(luò)，建立激光焊條件下焊接功率、焊接速度、離焦量與焊接熔深之間的非線性映射關(guān)系，優(yōu)化焊接工藝參數(shù)。采用臥式金相顯微鏡、掃描電鏡、X射線衍射儀、微機(jī)控制電子萬能試驗機(jī)等手段對優(yōu)化工藝條件下焊接接頭各區(qū)域的金相組織、斷口形貌、界面元素分布、主要物相和接頭力學(xué)性能進(jìn)行研究。結(jié)果表明：模擬計算獲得工件表面距焊縫中心不同位置溫度與實驗同步測量溫度基本吻合，所建熱源模型能反映激光焊實際過程特點；通過神經(jīng)網(wǎng)絡(luò)方法建立模型預(yù)測不同工藝參數(shù)下焊接熔池深度的相對誤差控制在10%以內(nèi)；優(yōu)化工藝條件下，焊縫橫截面鋁熔化，鋼少量熔化，液態(tài)鋁在鋼表面潤濕鋪展良好，鋼/鋁界面層形成厚度約為9 μm、由FeAl和Fe3Al組成的金屬間化合物層，焊接接頭平均抗剪強(qiáng)度為27.70 MPa，斷裂形貌表現(xiàn)為準(zhǔn)解理和韌性的混合型斷裂特征。
關(guān)鍵字: 6016鋁合金；鍍鋅鋼；激光焊；模擬計算；BP神經(jīng)網(wǎng)絡(luò)；組織；性能
（State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University, Changsha 410082, China）
Abstract:The laser lap welding test on the galvanized steel and the 6016 aluminum alloy with tie fiber laser and no brazing filler metal addition was carried out in order to inhibit or reduce the formation of Fe/Al brittle intermetallic compound. The laser welding heat source model of steel and aluminum was established by using ANSYS software. The penetration depths under different process parameters were given based on the simulation and experiment results, the nonlinear relationship between the process parameters, such as laser power, welding velocity and focal position and the penetration depth was established by the BP network, the welding parameters were also optimized. The microstructure, fracture morphology, element distribution, the main phase of the welded joint regional and mechanical properties of welded joints were studied by optical microscopy, scanning electron microscopy, X-ray diffractometry and microcomputer tensile testing machine. The results show that the simulation temperatures are consistent with the measured temperatures of different positions on the workpiece surface and the heat source model can be applied to the actual laser welding process, the relative error of the penetration depth under different process parameters can be controlled within 10% according to the trained network forecast. Under the optimal process conditions, aluminum melting and steel melting with a little amount on the weld cross-section take place, the wetting and spreading of the liquid aluminum on the steel surface are seen to keep good conditions. The thickness of intermetallic compounds layer is about 9 μm, which are composed of FeAl and Fe3Al. The average shear strength is 27.70 MPa, and the fracture morphology of welding joint is in a ductile and quasi-cleavage mixing mode.
Key words: 6016 aluminum alloy; galvanized steel; laser welding; simulation calculation; BP neural network; microstructure; mechanical properties
