焊接裂纹磁场模拟及磁光成像检测

研究交变磁场下的焊缝裂纹磁化规律，针对碳钢（Q235）焊缝裂纹，进行交变电磁场励磁下焊缝磁光成像无损检测的仿真和试验. 基于交变励磁下焊缝励磁规律的仿真模型，研究裂纹间隙分别为0.03，0.05，0.07和0.1 mm的焊缝表面磁通密度（磁感应强度）模曲线分布差异. 钢板对接间隙分别限定为0.03，0.05，0.07和0.1 mm后，通过激光焊接钢板两端来模拟仿真试验中的裂纹. 进行磁光成像无损检测试验，并将试验结果与仿真结果进行对比. 结果表明，在仿真试验与工艺试验中，焊接裂纹感应磁场的变化规律基本相同，磁感应强度不会因采样起始点不同出现较大的差异.

Magnetic field characteristic simulation and magneto-optical imaging detection of weld cracks

Simulation and experiment of magneto-optical imaging non-destructive testing of weld under alternating electromagnetic field were carried out. The weld crack magnetization under the alternating magnetic field of carbon steel (Q235) was studied. Based on a simulation model of alternating magnetic field excitation, the magnetic field density (magnetic flux density) curve distribution of the weld crack with 0.03, 0.05, 0.07 and 0.1 mm gaps were analyzed. Simulation results were verified by the magneto-optical imaging nondestructive testing system. Experimental results show that the weld cracks of different gaps have the same shape of the flux density mode curve, and there is significant difference between N pole and S pole. The amplitude of the flux density curve and the transition area will decrease as the crack gap decreases.