(1. 湖南大學 汽車車身先進設計制造國家重點實驗室，長沙 410082；
2. 湖南經(jīng)閣鋁業(yè)科技股份有限公司，長沙 410082)
摘 要: 針對6061-T6鋁合金薄板T型接頭的雙脈沖MIG焊，采用彈塑性有限元方法對其溫度場與應力-應變場進行模擬，并將熱輸入簡化為以低頻脈沖頻率在強、弱脈沖之間周期性轉換的熱源，同時運用生死單元技術模擬焊絲的填充過程。結果表明：焊后T型接頭的殘余應力主要集中在焊縫處，其最大值為273 MPa，導致受熱側翼板產(chǎn)生了1.61°的角變形。焊接過程中的溫度場和應力場均以低頻脈沖頻率周期性變化，與強脈沖群相比，弱脈沖群階段的熔池溫度較低且體積較小，而熔池及周邊金屬的受力較大。強、弱脈沖之間的周期性轉換引起熔池尺寸及受力的周期性變化，有利于魚鱗狀焊縫和細小均勻的焊縫組織的形成。熔池尺寸、焊接熱循環(huán)曲線以及T型接頭焊接變形的模擬結果與實驗結果吻合較好，驗證了模擬的可靠性。
關鍵字: 鋁合金；雙脈沖MIG焊；數(shù)值模擬； T型接頭；焊接應力
（1. State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University, Changsha 410082, China;
2. Hunan JinGe Aluminum Technology Co., Ltd., Changsha 410082, China）
Abstract:Based on thermo-elastic-plastic model, a three-dimensional finite element model was applied to simulating the temperature, residual stress and deformation fields of 6061-T6 T-joint weld during double pulsed MIG (DP-MIG) welding process. During describing the heat source of DP-MIG, the heat input was simplified to change between thermal pulse and thermal base at the cycle of low pulse. The technique of element birth and death was employed to simulate the weld filler in T-joint fillet welds. The simulation results show that the stress located at fusion zone reaches 273 MPa, which induces a 1.61° angular distortion. Besides, temperature and stress fields will change with the cycle of low pulse. The temperature of weld pool is lower and the weld pool size is smaller during thermal base compared with that in thermal pulse, while the stress of weld pool shows an opposite tendency. The cyclic change of temperature and stress between thermal pulse and thermal base during welding process results in the formation of typical ripples appearance on the weld joints, as well as enhances the flow of weld pool to produce more uniform and finer microstructure. The comparison between the experiment and simulation results shows a good agreement, which verifies the precision of welding simulation.
Key words: aluminum alloy; double pulsed MIG welding; numerical simulation; T-joint; temperature; welding stress
