Nondestructive Evaluation of Deformation Substructure in Fatigued SM49OYA Steel Using Magnetic Measurement

Abstract

Relation between magnetic properties and fatigue substructure in fatigued SM490YA steel was investigated. Coercive field H_c was sensitive to dislocation density, rapidly increased with increasing number of fatigue cycles at the initial stage and reached in a saturation at the middle and last stages of metal fatigue. Coefficient of magnetic susceptibility, c, increased over all stages of the fatigue tests and was sensitive to degradation in comparison with H_c. These magnetic-structure-sensitive properties would be useful for nondestructive evaluation of fatigue damage in low carbon steels.