Dependence of deformation-induced magnetic field on plastic deformation for SUS304 stainless steel

In this paper, the correlation between plastic deformation and the deformation-induced magnetic field was exper- imentally investigated for the SUS304 austenitic stainless steel. Test-pieces with different shapes were fabricated to produce different strain distribution. Various plastic tensile loads were imposed into the specimens to introduce plastic deformations of different levels. The residual strain distributions at the surfaces of the specimens were measured by an optical 2D strain measurement system during loading process while the distributions of the deformation-induced magnetic fields above the specimens were measured by using a fluxgate magnetometer after each loading cycle. The experimental results show that the amplitudes of the magnetic field have a clear and repeatable relationship with the maximum residual strains for all the specimens, and the relationship is independent of the strain distribution. Based on the experimental results, the mechanism of the deformation-induced magnetic field was discussed, and a NonDestructive Evaluation (NDE) method was proposed for the quantitative evaluation of plastic deformation in the SUS304 stainless steel.