为了研究磁场激励下焊接缺陷磁光成像特征, 以激光焊低碳钢板为试验对象, 采用恒定磁场和50Hz交变磁场对焊接缺陷进行励磁, 并由磁光成像传感器实时获取焊接缺陷区域磁场分布, 进行了理论分析和实验验证。取得了恒定磁场和交变磁场励磁下厚度分别为1mm, 2mm和3mm低碳钢(Q235)焊接缺陷的磁光图像, 并与COMSOL模拟结果进行对比;通过加权平均图像融合技术将交变磁场中获得的焊接缺陷磁光图像进行融合。结果表明, 与恒定磁场励磁相比, 采用交变励磁获得的焊接缺陷信息更加准确、快速和完整, 并且有效避免了焊接缺陷信息的遗漏。此研究为提高焊接缺陷检测效率提供了依据。

In order to study the characteristics of magnetic-optical images of weld defects excited by magnetic field, low carbon steel of laser welding was used as test object and the welding defects were excited by constant magnetic field and 50Hz alternating magnetic field. Real-time magnetic field distribution of welding defect area was obtained by magnetic-optical imaging sensor. Through theoretical analysis and experimental verification, the magneto-optic images of welding defects of low carbon steel (Q235) of thickness of 1mm, 2mm and 3mm with constant magnetic field and alternating magnetic field were obtained, and then, were compared with COMSOL simulation results. The weighted average image fusion technique was used to fuse the magnetic-optical images of welding defects in the alternating magnetic field. The results show that, compared with the excitation of constant magnetic field, the welding defect information obtained by the alternating excitation is more accurate, fast and complete, and avoids the omission of welding defect information effectively. This study provides the basis for improving the detection efficiency of welding defects.