Estimation of Anomalous Portion in Gray Cast Iron Using Non-Contacting Electromagnetic Sensor

Gray cast iron is used in many mechanical parts due to its excellent damping force, wear resistance, and castability. Inspection of the tensile strength of this cast iron is important for the quality assurance of the machine products. The areas of reduced tensile strength in the cast iron are defined as abnormal areas in the cast iron. The tensile strength of gray cast iron is affected by its microstructure. The gray cast irons with low tensile strength contain a high percentage of ferrite and a low percentage of pearlite. The electromagnetic properties of cast iron are affected by the content of these components. In this article, an electromagnetic sensor is proposed in which the tensile strength of the gray cast iron is measured from changes in these electromagnetic properties. The electromagnetic finite element method (FEM) analysis using a play model method and the verification experiment show that the abnormal part of the tensile strength can be estimated from the difference in the hysteresis magnetic curve and conductivity in the cast iron.