In order to study the burning loss of magnesium element in laser welding aluminum alloy, a specially-designed device was first used to collect the spectral signals emitted from the keyhole plasma in deep penetration laser welding aluminum alloy 5052. Then, the content of magnesium element in the welds was tested by an electron probe micro analyzer. Under the experimental conditions, the welding parameters heavily affect the spectral intensity of magnesium element plasma. The spectral intensity is not uniformly distributed in the keyhole region. In the radial direction, the spectral intensity of Mg I decreases from the center to the edge of the keyhole; in the depth direction, from the top to the bottom of the keyhole, the spectral intensity of Mg I increases first and then decreases. The Mg content changes inversely with the spectral intensity in the keyhole region. Therefore, spectral analysis technology can be used to monitor the burning loss of magnesium element in laser welding aluminum. It can be concluded that Mg loss in the keyhole region is determined by laser intensity absorbed there. The higher the absorbed laser intensity, the bigger the Mg loss.%为了研究铝合金激光焊接过程中镁元素的蒸发烧损,采用特殊设计的实验装置采集了激光深熔焊接5052铝合金过程中孔内等离子体的光谱信号,并用电子探针显微分析仪检测了焊缝中的镁元素.发现激光焊接工艺参量对工件表面的镁元素等离子体信号强度的影响很大,小孔中各位置的光谱强度是变化的,在小孔的径向方向Mg I的相对强度逐渐减小,而在小孔的深度方向先增加后降低;焊缝区镁元素含量的变化趋势与光谱强度的变化趋势相反.结果表明,采用光谱仪能够监测激光焊接铝合金过程中镁元素的烧损;小孔中不同位置处镁元素的烧损主要由各位置吸收的激光能量决定,材料吸收的激光能量越高,镁元素的烧损越大.
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