高氮钢激光-电弧复合焊接熔池表面流动行为

焊接熔池流动行为是影响焊缝成形和接头质量的关键因素之一，其特征难以直接获取。试验采用ZrO₂颗粒作为示踪粒子，利用高速相机观察示踪粒子运动轨迹，开展高氮钢激光-电弧复合热源焊接熔池表面流动行为的研究。研究结果表明：单独激光焊接时，其熔池的流动主要受匙孔尺寸变化的影响；单独电弧焊接时，其熔池的流动则主要受电弧压力和熔滴进入熔池时所产生的冲击力的影响；而激光-电弧复合焊接时，其熔池的流动既受电弧压力和熔滴进入熔池时所产生的冲击力的影响，同时，匙孔的存在也会影响其熔池的流动。在激光-电弧复合焊接过程中，示踪粒子的直线移动距离随着焊接电流和电弧电压的增加而增加；而激光功率的改变对其直线移动距离的影响并不显著。研究结果揭示了不同焊接工艺及其参数对高氮钢焊接熔池表面流动行为的影响规律，为高氮钢焊接工艺的选择提供了理论依据。

Surface Flow Behavior of Laser-arc Hybrid Welding Pool of High Nitrogen Steel

The results of the study reveal the effect of welding process parameters on theflow state of the molten pool surface. The flow behavior of the molten pool is one of the critical factors which affect the weld forming and the quality of the joints, while its characteristics are difficult to obtain directly. The ZrO₂ particles are used as tracers, and high-speed camera is used to observe the trajectories of tracer particles. Several experiments with laser-arc hybrid welding are carried out to investigate the flow behavior of the molten pool of high nitrogen steel. The results show that the flow of the molten pool is mainly affected by the change of the size of the keyhole during laser welding. However, the flow of the molten pool during the process of arc welding is mainly influenced by the arc pressure and the impact force generated when the droplet enters the bath. In the process of laser-arc hybrid welding, the molten pool flow is not only affected by the arc pressure and the impact force generated when the droplet enters the molten pool, but the presence of the keyhole will also affect the flow of the molten pool. During laser-arc hybrid welding, the moving line distance of tracer particles increases with the increase of welding current and arc voltage, while the change of laser power does not affect significantly. The results of this study reveal the effect of different weldingprocesses and their parameters on the flow behavior of the molten pool surfaceof high nitrogen steels,which provides a theoretical basis for the selection of high nitrogen steel welding process.