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采用CO2和Nd∶YAG激光器焊接A3钢,结合高速摄像和光谱分析,研究激光深熔焊接阈值的表征及特性。结果表明,以激光功率与光斑直径之比作为深熔焊接阈值的表征参量,深熔焊接阈值与光斑大小无关;而临界功率密度随光斑尺寸不同而变化。YAG激光焊接模式转变阈值明显大于材料蒸发的阈值,在模式转变前的热导焊接阶段,金属材料已出现显著蒸发,而焊接模式转变后,蒸气羽辉的光谱保持不变。CO2激光焊接模式转变前,金属仅发生微弱的蒸发。深熔焊接时,蒸发显著加强,且蒸气部分电离。分析表明,CO2激光焊接时,蒸气电离形成等离子体,增加金属对激光的吸收,促进深熔焊接过程的建立。
The CO2 and Nd:YAG laser welding A3 steel, combined with high-speed imaging and spectral analysis, laser welding characteristics of the threshold of the study. The results show that the ratio of laser power to spot diameter is the characteristic parameter of deep penetration welding threshold, and the threshold of deep penetration welding has nothing to do with the spot size. The critical power density changes with the spot size. YAG laser welding mode transition threshold is significantly greater than the material evaporation threshold, during the thermal conductivity welding mode before the mode transition, the metal material has been significantly evaporated, and the welding mode transition, the steam feather spectrum remains unchanged. Before the CO2 laser welding mode was changed, the metal only evaporated slightly. During deep-penetration welding, evaporation is significantly enhanced and the vapor is partially ionized. Analysis shows that CO2 laser welding, the vapor ionization plasma, increasing the absorption of metal on the laser to promote the establishment of deep-melt welding process.