激光-电弧复合焊接中激光脉冲对电弧正-负半波作用

摘要

Coupling effect between laser and arc plasma was studied when laser acting at the positive and negative wave-form of the arc discharge during laser-arc hybrid welding of magnesium alloy. By the methods of direct observation, high speed imaging and spectral analysis, the surface status of weld seams after welding, the welding penetration depths, the plasma behav-iors and the spectral characteristics of welding plasma were investigated gradually. Results show that compared with the situa-tion of laser pulse acting at the negative waveform the arc plasma discharge, better weld seam formation can be achieved when laser pulse acts at the positive waveform of the arc discharge. At the same time, the radiation intensity of Mg atoms in arc plasma greatly increases, and however, the welding penetration depth is much weaker. After analysis, it is found that when laser pulse acting at the negative waveform the arc plasma discharge, the position of arc plasma discharge on workpiece can be restrained by the laser acting point, which improves the energy density of the welding arc.%本论文研究了激光-电弧复合热源焊接镁合金过程中激光脉冲作用于交流电弧放电的正、负半波时激光与电弧的耦合作用。本文采用直接观察焊缝表面状态、高速摄像和光谱分析相结合的方式，研究了激光脉冲分别作用于电弧正、负半波时焊缝的成型特点、熔化深度、等离子体行为以及光辐射特性。结果表明，激光脉冲作用于电弧放电正、负半波时，均能实现连续焊接，电弧体积均发生膨胀。相比于激光脉冲作用于电弧放电负半波，激光脉冲作用于正半波时的焊缝成型较好，电弧等离子体中镁原子辐射强度的增加程度较大，但焊接熔深较小。通过分析，发现激光脉冲作用于电弧放电负半波可以固定电弧在板材的放电位置，提高电弧的能量密度。