镀锌钢激光焊接锌烧损研究

锌烧损是镀锌钢板激光焊接过程中的关键问题之一.本文通过测量焊后上下层锌烧损宽度、中间层锌的相对含量及腐蚀前后增重比,实验研究了激光搭接焊接工艺参数与焊接过程中光致等离子体谱线信息与锌烧损的相关性.研究结果表明:锌烧损的主要影响工艺因素主次顺序为焊接速度、激光功率、辅助气体流量和离焦量;锌的烧损量随着锌谱线Zn I 328.2nm和Zn I 330.3nm的平均强度的增大而增大;气孔因镀层锌的蒸发而产生,直径越大,局域锌元素含量越高.锌谱线强度可用于在线监测镀锌钢激光焊接时气孔的产生及锌烧损量的动态变化.

Study of the Zinc Burnout in Laser Welding of Galvanized Steel

The burnout of zinc is one of the key problems in laser welding of galvanized steel. In this paper, the burnout width of the zinc layer on both the top and the bottom of the weld and the zinc content in the middle layer of the weld zone were measured, and the weight gain ratio after the corrosion tests was obtained. The relationships between process parameters and the spectral signals of the laser-induced plasma as well as the burnout of the zinc were experimentally studied in laser lap welding of galvanized steel. The results have shown that: 1) the important order of the relevant factors affecting the burnout of the zinc is welding speed>laser power>auxiliary gas flow> defocus; 2) the burnout rate of the zinc is increased with the increase of the intensity of zinc line Zn I 328.2 nm and Zn I 330.3 nm; and 3) pores are generated because of the evaporation of the zinc. The more zinc content exists around the pore wall, the larger the diameter of the pore is. The intensity of the zinc line can be used for the on-line monitoring of the dynamic rate of the zinc burnout and the pore produced in the laser welding process.