Flake graphite cast iron investigated by a magnetic method

The method of magnetic adaptive testing (MAT) was applied for the investigation of flake graphite cast iron samples having various metallic matrix and graphite structures. MAT is typical by its low required magnetization of samples, because it is based on the measurement of families of minor magnetic hysteresis loops. The flat samples were magnetized by an attached yoke and sensitive descriptors of their magnetic/structural state were obtained from the evaluation of the measured data. Metallographic examination of the matrix and graphite structures was performed and results of the nondestructive magnetic tests were compared with these data. A very good correlation was found between the magnetic descriptors and the graphite morphology. With these results, MAT is suggested as a highly promising nondestructive alternative of destructive tests for monitoring structural changes in cast iron and other ferromagnetic objects.