Tensile-Stress Dependence of Magnetic Hysteresis Properties Measured by the Acoustically Stimulated Electromagnetic Response in Steel

Magnetic hysteresis properties are sensitive to stress in ferromagnetic materials. This suggests that magnetic measurements are a potential method to evaluate residual stress in steel products. Nevertheless, nondestructive inspection of residual stress by using magnetic properties has been limited because bulk properties over the entire sample are usually obtained in conventional hysteresis curve measurements through electromagnetic induction; thus, local hysteresis properties are not measured. However, the spatial mapping of local hysteresis properties has been demonstrated recently by ultrasound focusing and scanning. This technique is based on the generation and detection of the acoustically stimulated electromagnetic (ASEM) response. In this study, we investigate the stress dependence of local hysteresis loops through the ASEM response using a tensile testing machine and provide conversion coefficients to estimate tensile stress from the values of local hysteresis properties. The results indicate that hysteresis properties associated with coercivity, remanent magnetization, and hysteresis loss are promising parameters as an index for evaluating residual stress.