At present, there are few researches on laser -MIG arc hybrid welding with a large butt gap. In this paper, laser-MIG arc hybrid welding is used to weld low-alloy high-strength steel with a thickness of 3 mm, and a laser-MIG arc hybrid welding process under large gap conditions is developed. This paper studies the effects of arc voltage, laser-wire distance, and wire feed speed on the gap bridging capability of hybrid welding under different butting gaps. Under the condition of the 1 mm butt gap, the influence mechanism of laser-wire distance on weld the weld formation of hybrid welding is analyzed by combining high-speed photography, welding current and voltage waveform, the macroscopic and microscopic morphology of the weld. The results show that there are optimal process parameter values for the effects of arc voltage and laser-wire distance on the gap bridging capability of hybrid welding. Adjusting the laser-wire distance can optimize the energy distribution of laser on the welding wire and weld pool, thus controlling the arc current, voltage, and droplet transition mode, and finally affecting the weld penetration and forming. When the laser-wire distance is 0 mm, the droplet transition frequency is the fastest, and the droplet transition is a mixture of short circuit transition and liquid bridge transition. At this point, the welding rate is the fastest and the welding process is the most stable. However, by comprehensively integrating factors such as the gap bridging capability and the weld penetration, the optimal processing parameters are obtained when the laser-wire distance is 0.5 mm.

目前，对接间隙大的激光-MIG电弧混合焊接的研究很少。本文采用激光-MIG电弧混合焊接技术焊接厚度为3mm的低合金高强度钢，并发展了大间隙条件下的激光-MIG电弧混合焊接工艺。本文研究了电弧电压，激光焊丝距离和送丝速度对不同对接间隙下混合焊接间隙桥接能力的影响。在对接间隙为1mm的条件下，结合高速摄影，焊接电流和电压波形，焊缝的宏观和微观形态，分析了激光焊丝距离对焊缝形成的影响机理。结果表明，对于电弧电压和激光线距离对混合焊接间隙桥接能力的影响，存在最佳的工艺参数值。调整激光丝距离可以优化激光在焊丝和焊池上的能量分布，从而控制电弧电流，电压和熔滴过渡模式，最终影响焊缝熔深和成形。当激光线距离为0mm时，液滴过渡频率最快，并且液滴过渡是短路过渡和液桥过渡的混合。此时，焊接速度最快，焊接过程最稳定。但是，通过综合考虑间隙桥接能力和焊缝熔深等因素，