Magnetic Diagnosis of Structural Materials and These Monte-Carlo Simulations

Many magnetic techniques were developed for nondestructive evaluations for iron-based materials such as SUS304, A533B, S25C etc in a tensile stress range up to each fracture state. Magnetic tools are composed of a triple-fold coil for ac resistivity detections, a small Hall element for leakage flux observations after polarizations of the material and a pickup coil of magnetic Barkhausen noises combined with the excitation yoke. The degree of degradations was expressed by an average field for the discontinuous magnetization. Magnetic noises were simulated by Monte-Carlo method under the non-equilibrium condition with limited trials.