基于光谱诊断的脉冲GMAW焊金属蒸汽动态扩散行为研究

Experimental Study of the Diffusion Process of Pulsed-GMAW Plasma with Optical Emission Spectrometry

理解脉冲GMAW焊电弧物理的动态特性对解释这一焊接方法的内在机理及获取优化控制策略有重要意义,通过在高速摄影前加窄带滤波片的方法研究了脉冲GMAW焊接过程中不同粒子的扩散行为,同时采用光谱仪研究了不同状态下金属与蒸汽保护气氛谱线的强度分布信息,采用气体状态方程、等离子体准中性方程、和Saha方程计算了脉冲GMAW焊接峰值和基值两种不同状态下的金属蒸汽浓度分布。研究结果显示,在峰值时刻,金属蒸汽被约束在电弧中心1mm左右的范围内,当电流从峰值跳转到基值时刻,金属蒸汽从中心扩散到电弧外围区域,峰值时刻中心金属浓度约为75%,而基值仅为35%左右。

In case of GMAW-P application,the product quality is strongly dependent on the arc plasma performances.Therefore,in order to improve the application,it is important to understand and characterize the fundamental plasma properties.In this paper,different techniques（high speed camera,optical emission spectroscopy system,electrical data acquisition system,synchronous triggering device）were used to characterize the arc characteristic.The metal diffusion process from the peak time to the base time is discussed,as well as its physical characteristics.The results show that,in the peak time phase,a high concentration of metal vapor arc is concentrated in the plasma center of the range of about 1mm,during the transition from the peak to the base pulse periods,the diffusion leads to an iron vapor flux from regions in the arc core to the arc fringes.The iron mol fraction of the peak time was up to 75%,only taking up 35% of the base time.