Graphite structure and magnetic parameters of flake graphite cast iron

Different matrix and graphite morphologies were generated by a special heat treatment in three chemically different series of flake graphite cast iron samples. As cast, furnace cooled and air cooled samples were investigated. The length of graphite particles and the pearlite volume of samples were determined by metallographic examination and these parameters were compared with the nondestructively measured magnetic parameters. Magnetic measurements were performed by the method of Magnetic Adaptive Testing, which is based on systematic measurement and evaluation of minor magnetic hysteresis loops. It was shown that linear correlation existed between the magnetic quantities and the graphite length, and also between the magnetic quantities and the relative pearlite content in the investigated cast iron. A numerical expression was also determined between magnetic descriptors and relative pearlite content, which does not depend on the detailed experimental conditions.