Fatigue behavior of AISI 8620 steel exposed to magnetic field

Highlights: • AISI 8620 steels were used for evaluating the microstructural and mechanical properties, and the fatigue lifetime. • Exposure to 10 T magnetic field was applied to simulate the material changes in the power systems. • The exposure caused precipitations and releases of compressive residual stress. • Exposed steels showed higher yield and tensile strengths and longer fatigue lifetime. In this study, the effect of magnetic field on AISI 8620 steel, which is commonly used in essential machinery components, was investigated in microstructural and mechanical aspects, and fatigue lifetime was finally evaluated. To prepare the steel exposed to magnetic field, cryo-cooled superconducting magnet system that generates a 10-T magnetic field was used in this study. The samples were exposed to 10-T magnetic field for 0 d, 10 d, and 20 d. The magnetic exposure induced the additional nucleation of cementite and the reduction of the compressive residual stress in the steel. This exposure resulted in extension of the fatigue lifetime by increments in yield strength, tensile strength and elongation, and the reduction of elastic modulus. This could occur because of the changes in mechanical properties induced by the additional precipitation of cementite and the relief of the compressive residual stress under magnetic field.