采用3.5 kW Slab CO2激光焊接不锈钢, 利用高速摄像观测焊接等离子体形态, 采用光谱仪探测等离子体光谱, 并利用相对强度法计算等离子体电子温度。结果表明: 在氦气保护下, 等离子体高度随时间周期性振荡, 振荡频率约为530 Hz; 熔池表面附近等离子体的温度为8 392 K左右。进一步分析表明, 等离子体对入射激光的吸收不足10％; 等离子体周期性振荡对焊接过程稳定性影响不明显。

In this paper, the laser-induced plasma was observed and detected separately by applying a high speed camera and a spectrometer in welding of stainless steel with a 3.5kW slab CO2 laser. Plasma temperature was obtained with the relative intensity method. The results show that, in the condition with helium as shielding gas, the laser-induced plasma fluctuates periodically with a frequency of about 530Hz, and the plasma temperature is about 8392K above the weld pool. Further analysis demonstrates that the plasma absorption to the incident laser beam is less than 10％, and the periodic fluctuation of the laser induced plasma seldom affects the welding process stability.