Study on weld defect testing technology based on the method of magnetic memory

To study on the changes of magnetic memory signals of defects in the weld seam, a magnetic dipole model of weld seam in earth magnetic field was established. The change curves with defect and without defect in the weld seam were simulated. According to the changes of curves, the law of magnetic field changes when there were defects in the weld seam was obtained. The magnetic memory signals of the self made weld samples were tested to compare with the model. The testing curves with defects in the weld seam and the simulated curves matched each other well. The magnetic dipole model established can reflect the real situation of magnetic memory signals in the weld seam, and can be used to estimate the defects in the weld seam.