【摘要】 从ＣＯ＿２激光焊接时等离子体产生的机理出发，针对厚板焊接，采用一套精密调节装置对辅助气体控制等离子体的主要工艺参数进行了试验研究，并对焊接时等离子体行为、小孔及熔池的运动进行观察。结果表明：无论采用何种常用气体，只要其压力稍高于金属蒸气压力，等离子体被压缩和控制，就可获得最佳的深穿透焊缝。更多还原

【Abstract】 Based on the mechanism of plasma formation during CO2 laser welding,the main tech-nological parameters,including the nozzle diameter,nozzle angle,nozzle height,the assistgas used and its pressure for plasma control with assist gas,have been experimentally stud-ied.The plasma behavior,key-hole and molten pool motion have been observed.The resultsobtained show that the optimal value of the nozzle diameter is d=1.8 mm,that of the nozzleangle is a= 35°,and that of the nozzle height is h= 3mm. No matter what kind of assist gasis used,as long as the gas pressure is slightly higher than the metallic vapor pressure and theplasma can be compressed and blown away from the rear wall of the keyhole,the weldbeads with optimal ratio of penetration depth to width can be obtained.Should the pressureof the assist gas be higher than the surface tension of the liquid metal surrounding the key-hole,the penetration depth would increase with the increase of the gas pressure,Humpingbeads will result if the gas pressure is unduly high.更多还原