Evaluation of Electromagnetic Inspection of Hardened Depth of Spheroidal Graphite Cast Iron Using 3-D Nonlinear FEM

The inspection of the hardened depth of surface hardening spheroidal graphite cast iron is important in the maintenance of various mechanical parts, etc. There is a difference of the electromagnetic property in the layers with and without hardening. Therefore, the evaluation of the hardened depth is possible by detecting the difference of the electromagnetic characteristic. In this paper, the electromagnetic method for measuring the depth of a hardened layer using an alternating magnetic field is proposed. The flux density in the surface hardening spheroidal graphite cast iron is estimated by 3-D nonlinear FEM taking account of the electromagnetic property of the layers with and without hardening. In addition, the experimental verification is also carried out.