EVALUATION OF CARBURIZATION DEPTH IN-SERVICE EXPOSED FERRITIC STEEL USING MAGNETIC BARKHAUSEN NOISE-ANALYSIS

The feasibility of using magnetic barkhausen noise (MEN) measurement f or the evaluation of carburization depth in ferritic steels is discuss ed in this paper MBN measurements were carried out on samples from exp osed in service 0.5Cr-0.5Mo ferritic steel tube at different depths (c ross section) from carburized ID surface to simulate the variation in carbon concentration gradient within the skin depth of MBN with increa sing time of exposure to carburization. It has been observed that the MBN level increases with increasing depth of measurement. An inverse r elation between MBN level and carbon content/hardness value has been o bserved. This study suggests that the MBN measurements on the carburiz ed surface can be correlated with the concentration gradient within th e skin depth of the MBN which (with proper prior calibration) would he lp in predicting the approximate depth of the carburized layer.