为了研究光纤激光焊接奥氏体不锈钢过程中侧吹气体对焊缝组织和耐腐蚀性能的影响，建立了一种侧吹气体和金属蒸气的流体模型，分析了不同侧吹气体及其流量对金属蒸气温度场和速度矢量场的影响，提出了一种通过侧吹气体增加焊缝金属中氮元素含量的方法。试验结果表明，在不影响焊缝成形的前提下，该方法有效提高了上层焊缝金属中氮元素的含量，抑制了焊缝金属中铁素体的含量，增强了奥氏体不锈钢激光焊焊缝的耐点蚀性能。

In order to study the influence of side assist gas on the microstructure and the corrosion resistance of welds of austenitic stainless steels in the process of fiber laser welding, a fluid model of side assist gas and metal vapor is established. The influences of different kinds of side assist gases and their flow rates on the metal vapor temperature field and velocity vector are analyzed, and a method to increase the nitrogen content in the weld metals by means of side assist gas is proposed. The experimental results show that, on the premise of keeping the weld formation unaffected, the proposed method can effectively improve the nitrogen content in the upper layer of weld metals, restrain the ratio of ferrite in the weld metals, and enhance the pitting corrosion resistance of the austenitic stainless steel.