Correlation of stress concentration degree with residual magnetic field of ferromagnetic steel subjected to tensile stress

Abstract

The goal of this research was to correlate the residual magnetic field (RMF) with the residual stress and the stress concentration degree of ferromagnetic steels subjected to tensile stress. Tensile tests were carried out to measure the RMF signals on the surface of Q345 steel specimens with different stress concentration degrees. The residual stress in the defective specimens was numerically simulated using the finite element method. The impact of the residual stress on the distribution of the RMF components was systematically investigated. Verification of the qualitative relationship between the distributions of the residual stress and the gradients of the RMF components was subsequently performed on three defective specimens. The quantitative correlation between the maximum gradient of the RMF components and the stress concentration factor was further studied. A linear correlation was found which can be used to make a quantitative evaluation of the stress concentration degree based on the maximum gradient of the RMF components. The results obtained in this research will be a complement to the metal magnetic memory (MMM) technique.