焊接电流对双脉冲MIG焊铝合金T型接头形貌和显微组织的影响

摘要

通过模拟和实验研究电流对T型接头铝合金双脉冲惰性气体保护(MIG)焊的影响。通过建立三维有限元模型和双椭球模型来模拟不同焊接条件下的温度场和应力场。此外，还通过实验对相应电流下合金的宏观和微观形貌进行观察。结果表明：最优焊接条件为平均电流为90 A，且强弱脉冲电流差值为40 A，此时熔池最高温度比熔点高200°C，且强脉冲阶段和弱脉冲阶段温度差和应力差值分别为100°C和10 MPa时，该条件下熔合较好的铝合金T型接头具有平滑的鱼鳞纹状焊缝和良好的显微组织。此外，实验和模拟得到的温度曲线和应力分布曲线吻合较好，验证了焊接模拟的准确性。%The effect of current on the morphology of Al alloy T-joint in double-pulsed metal inert gas (DP-MIG) welding process was investigated by simulation and experiment. A three-dimensional finite element model and the DP-MIG heat source of double-ellipsoidal volumetric model were developed to simulate the temperature and stress fields under different welding conditions. The macro-morphology and microstructure of welding joints at the corresponding currents were observed in the experiment. The results show that the best condition is at an average current of 90 A and current difference of 40 A, when the maximum temperature is 200 °C higher than the fusion points, with the temperature difference of about 100 °C and stress change of 10 MPa between thermal pulse and thermal base. Under these conditions, Al alloy T-joint with proper fusion condition has smooth fish-scale welding appearance and finer microstructure. Furthermore, the thermal curves and stress distribution in the experiment are consistent with those in the simulation, verifying the precision of the welding simulation.