CO_2激光深熔焊接光致等离子体吸收及其控制

Laser_induced Plasma Absorption and Control for CO_2 Laser Deep-penetration Welding

研究高功率密度 CO2 激光焊接过程中光致等离子体对入射激光的吸收以及侧吹辅助气体对等离子体控制的影响。采用准基模 CO2 激光束在 1 Cr1 8Ni9Ti不锈钢表面进行扫描焊缝 ,通过光谱检测装置检测等离子体辐射谱线强度 ,从而计算等离子体对激光的吸收系数 ;采用侧吹喷嘴分别通CO2 、N2 、Ar、He4种气体压缩等离子体。研究结果表明 ,光致等离子体对入射激光能量的吸收损失高达 2 0 % ;随着侧吹辅助气体流量的增加 ,焊缝呈现3个区间 :当气体压力低于金属蒸汽压力时 ,焊缝为“酒杯”状 ,深宽比很小 ;当辅助气体操作压力稍高于金属蒸汽压力 ,等离子体可被有效控制从而获得最佳焊缝。

The paper aims at systematically studying the influence of laser-induced plasma on absorption loss of laser energy and the influence of assist-gas pressure on the plasma control in high power CO 2 laser welding. A device is used to detect the light intensity of the plasma radiation during the welding of the material 1Cr18Ni9Ti(stainless steel) in order to calculate the absorption loss. Four kinds of declined-blowing assist-gases of CO 2, N 2, Ar, He are also used to suppress the plasma. The results show that the laser energy loss is up to 20% due to plasma absorption, and the weld-beam showed three regions with the increase of the pressure of assist-gas, if the gas pressure is lower than the vapor pressure of welded metal, the section of weld-beam showed the shape like 'wine-cup' with small ratio of penetration to width. No matter what kind of gas is used, only the operating pressure of assist gas is slightly higher than that of the vapor pressure of welded metal, plasma could be effectively controlled, sound weld-seam can be obtained.