分别采用气体保护焊(GMAW)和激光焊(LBW)焊接板厚为2.8 mm的Q345低合金高强钢对接接头，并测量了对接接头的面外变形。基于Abaqus软件平台，开发了同时考虑材料非线性与几何非线性的热-弹-塑性有限元算法。利用开发的算法计算了GMAW和LBW两种焊接方法的焊接温度场、焊接变形和残余应力。模拟温度场时，采用等密度椭球热源模拟GMAW的热输入，分别采用高斯分布锥形体热源、由等密度半椭球热源与锥形体热源组成的复合热源模拟LBW的热输入。数值模拟结果和试验结果表明，焊接2.8 mm厚的Q345钢板对接接头时，LBW产生的面外焊接变形明显小于GMAW；LBW在焊缝附近产生的纵向高拉伸应力区域范围明显小于GMAW，且两者的纵向与横向残余应力分布形态也有较大差异。此外，模拟激光焊时，虽然高斯分布锥形体热源与复合热源模型在板厚方向的热流密度分布不同，但两者产生的焊接变形差异很小，焊接残余应力分布也基本一致。数值模拟结果对两种激光热源模型并不十分敏感。

Gas metal arc welding (GMAW) and laser beam welding (LBW) were used to weld 2.8-mm-thick low-alloy high-strength Q345 steel butt joints. The out-of-plane deformation in the welded joints was measured experimentally. Meanwhile, based on the Abaqus software, a thermal-elastic-plastic property-based finite element method considering both material and geometrical nonlinearity is developed to calculate the welding temperature field, welding deformation and residual stress in the LBW and GMAW processes. In the simulation process of temperature field, an ellipsoid volumetric heat source model with uniform density flux was used to simulate the heat input induced by the GMAW process, while a conical heat source model with Gaussian distribution and a combined source model consisting of half ellipsoid volumetric heat source and conical heat source were used to model the heat input induced by the LBW process. The simulated and experimental results show that the out-of-plane deformation induced by the GMAW process is far larger than that produced by LBW. In addition, the area with high longitudinal tensile stress in the LBW joint is much smaller than that in the GMAW joint. Both longitudinal and transverse residual stress distributions in the LBW joint are notably different from those in the GMAW joint. In the simulation of LBW, welding deformation and residual stress distribution in the conical heat source model with Gaussian distribution and in the combined heat source model are similar, although the heat flux distribution in the thickness direction is different. The simulation results are not sensitive to the used heat source models.