Electromagnetic Nondestructive Evaluation of Graphite Structures in Flake Graphite Cast Iron

Abstract

This paper discusses the feasibility of characterizing the shape and size of graphite in flake graphite cast iron based on electromagnetic nondestructive methods. Several flake graphite cast iron specimens containing graphite of various shapes and sizes were prepared and their electromagnetic properties such as conductivity and relative permeability were evaluated systematically. Both the conductivity and the relative permeability were found to mainly depend on the shape and size of graphite. The conductivity was specifically found to have a good correlation with the shape and size of graphite and this was independent of the pearlite area fraction of matrix. The conductivity also correlates well to the ultrasonic velocity which indicates the amount and size of the graphite. The DC potential drop method was used to evaluate the structure of graphite and its capability was evaluated.