Structural and magnetic characterization of a carburized cast austenitic steel

A magnetic flux measurement technique was used to correlate the magnetic response of carburized cast austenitic steel tubes with the volumetric fraction of chromium carbides in the tube wall. Two different types of chromium carbides were identified by backscattered electron diffraction: Cr23C6 in the outer part and Cr7C3 in the inner part of the tubes. Magnetic force microscopy and energy-dispersive X-ray analysis reveal a correlation between the ferromagnetic behavior of the tubes and chromium depletion in the matrix.