Examination of Electromagnetic Inspection of Retained Austenite in the High Chromium Cast Iron—3-D Nonlinear FEM Analysis Considering Nonuniform Permeability

The inspection of volume fraction of retained austenite in the high chromium cast iron is important in keeping the quality and hardness of abrasion proof components as a steel of hot-rolling etc. The permeability and the conductivity of the cast iron are decreased when the volume fraction of retained austenite is increased. Therefore, the inspection of the retained austenite is possible by detecting the difference of the electromagnetic characteristic. However, the inspection is not easy, because the permeability of the cast iron is usually nonuniform. As a result, the signal of the electromagnetic inspection has a magnetic noise. In this paper, the inspection technique for reducing the effect of the nonuniformity of the permeability on the large magnetic noise, and that for measuring the retained austenite is examined using 3-D edge-based hexahedral nonlinear finite element method (FEM). In addition, the experimental verification is also carried out.