Estimation of the Deterioration of Structural Materials on the Basis of Changes in Their Magnetization Properties during the Application of Tensile Stress

Abstract

In order to establish a nondestructive method of estimating residual strains induced in structural components for buildings, the magnetization properties of stress-imposed SS400 steel were measured, using a tensile tester equipped with a single sheet tester. In the elastic region, the permeability increases with increasing tensile stress and reaches a peak at the beginning of the plastic deformation, whereas the coercive force decreases with increasing stress. In the plastic region, as the applied stress increases, the permeability decreases, while the coercive force increases. Monotonic decrease and increase as functions of the tensile strain are observed in the permeability and the coercive force, respectively. These findings suggest that changes in the permeability and the coercive force with strains can be used for nondestructive estimation of deterioration of structural materials.