Carbide Dissolution Kinetics during Partial and Full Austenitization in 100Cr6 Steel

In this work, cementite dissolution kinetics was studied in 100Cr6 steel during partial and full austenitization. The change in cementite volume fraction and size was determined from samples heat treated for different durations at 840 degrees C and 1050 degrees C. The SEM micrographs were analyzed by using ImageJ software to count size and volume fraction of carbides. The obtained statistical data were used to draw the dissolution curves with a nonlinear curve fitting method. It was found that the cementite dissolution rate is fast at the beginning of partial and full austenitization. A model was established and carbide dissolution was calculated using DICTRA software. The dissolution curves were obtained and compared with the DICTRA simulations. The calculation results are in good agreement with the dissolution curves from statistical results of SEM micrographs. According to the calculation results, the fast carbide dissolution is due to dissolution under non-partitioning local equilibrium (NPLE) mode controlled by diffusion of C atoms and neglecting diffusion of Cr.