铝合金激光-电弧双面焊接激光稳定、压缩电弧的机制分析

Mechanism of Laser Induced Stabilization and Compression of Arc during Laser-arc Double-sided Welding for Aluminium Alloy

为了阐释铝合金激光-电弧双面焊激光稳定、压缩电弧的物理机理,采用对比试验的研究方法和红外测温、电弧光谱分析的技术手段,分析激光对电弧作用的物理本质。结果表明,在激光匙孔未穿透条件下,激光形成的大梯度温度场为电弧提供阳极斑点是铝合金激光-电弧双面焊电弧稳定、收缩的根本原因,高能量密度的激光热源和高热导率的材料二者不可或缺;而在激光匙孔穿透条件下,光谱分析显示常规钨极惰性气体保护(Tungsten inert gas arc,TIG)焊电弧的Ar谱线强度最高,不锈钢激光-电弧双面焊电弧次之,而铝合金激光-电弧双面焊电弧Ar谱线最弱,这表明铝合金较高的饱和蒸汽压使得激光在匙孔底部产生较多的激光等离子体,为电弧提供了更加容易的导电通道,因而电弧弧根作用于此。

In order to study the mechanism of laser induced stabilization and compression of arc during laser-arc double-sided welding（LADSW） for aluminium alloy, the method of comparative study and the technique of infrared temperature-measuring and arc spectroscopic measurement are dedicated to investigate the physical essence of the laser effect on arc plasma. The results show that laser supplying arc with the anode spot which is caused by the high temperature gradient of laser is the ultimate reason for the laser induced stabilization and compression of arc when the keyhole is not fully penetrated, and the high energy density of laser and high thermal conductivity of aluminium alloy are indispensable. While the keyhole is fully penetrated, the arc spectral intensities of Ar lines during conventional are welding are strongest, much weaker during LADSW for stainless steel and weakest during LADSW for aluminium alloy. It is indicated that the laser produces more laser plasma at the bottoms of the keyhole due to the higher saturated vapor pressure, which offers the easier electric channel for the arc. Therefore, the arc roots the laser induced plasma.