激光焊机退火功率对DP780带钢焊缝质量的影响

Effect of annealing power of laser welder on welding seam quality of DP780 strip

为了研究CO_(2)气体激光焊机退火功率对DP780带钢焊缝质量的影响,通过焊缝在线监测系统(Quality Control Date System,QCDS)、杯突试验、冷轧连续产线实际生产试验的方法,测试了不同退火功率下DP780带钢的焊缝质量。结果表明:焊接后退火功率为0 kW时,焊缝区域杯突试验裂纹沿焊缝方向展开,焊缝质量不合格;焊接后退火功率为10、15 kW时,杯突试验结果表明焊缝区域裂纹垂直于焊缝方向,焊缝质量合格;然而实际生产得到退火功率为10 kW的焊缝在生产过程中出现断带,退火功率为15 kW的焊缝无断带现象。为此,通过电子显微镜观察了退火功率为10 kW与15 kW时DP780带钢焊缝区域金相组织,并测试了其显微硬度。结果表明:焊焊缝区域组织均为马氏体+贝氏体组织,但退火功率为10 kW的焊缝区域存在裂纹缺陷,是其断带的主要原因。因此,实际生产中应将退火功率控制为15 kW,此时焊缝区域硬度略有下降,但是韧性得到了提高,能够满足冷轧连续产线正常运行的需要。

In order to study the effect of annealing power of CO_(2) gas laser welder on the quality of DP780 strip, the welding seam quality of DP780 strip under different annealing powers was tested by the methods of welding seam on-line monitoring system(Quality Control Date System, QCDS), cupping test and actual production test of cold rolling continuous production line. The results show that when the annealing power after welding is 0 kW, the cupping test crack in the welding seam area develops along the direction of the welding seam, and the quality of the welding seam is unqualified. When the annealing power after welding is 10 kW and 15 kW, the cupping test results show that the crack in the welding seam area is perpendicular to the direction of the welding seam, and the quality of the welding seam is qualified. However, the welding seam with an annealing power of 10 kW in actual production has broken in the production process, and the welding seam with an annealing power of 15 kW has no broken. Therefore, the metallographic structure of the welding seam area of DP780 strip with annealing power of 10 kW and 15 kW was observed by electron microscope, and its microhardness was tested. The results show that the microstructure of the welding seam area is martensite + bainite, but the crack defect exists in the welding seam area with an annealing power of 10 kW, which is the main reason for the fracture. Therefore, the annealing power should be controlled to 15 kW in actual production.The hardness of the welding seam area decreases slightly, but the toughness is improved, which can meet the needs of the normal operation of the cold rolling continuous production line.