Investigation of Cast Iron Matrix Constituents by Magnetic Adaptive Testing

Two types of cast iron materials - flake graphite cast iron and ductile cast iron - were investigated by the method of magnetic adaptive testing, which is based on the systematic measurement and the evaluation of minor magnetic hysteresis loops. In all cases, even within the same type of material rather big differences existed considering both the chemical composition and the material structure of the investigated sample series. The matrix structure was determined by traditional metallographic examination, and these values were compared with the non-destructively measured magnetic parameters. It was shown that the relative pearlite volume fraction of the metallic matrix of cast iron samples could be determined by this method with a good reliability. The same is true also for the relative chill content of the matrix, as long as the samples contain chill at all. A general expression was found to characterize those correlations, which do not depend on the actual sample and neither on the applied parameters of the concrete magnetic measurement.