Boride Layers on Sverker 3 Steel: Kinetic Modeling, Experimental Characterization, and Validation

The kinetic modeling, based on solving the mass balance equations at the two diffusion fronts, was considered to investigate boron diffusion and the formation of dual boride layers (FeB + Fe₂B) on Sverker 3 steel. Experimentally, the morphology of the boride layers was examined using scanning electron microscopy (SEM), allowing measurement of the layers' thicknesses. Phase analysis was performed using X-ray diffraction (XRD) to identify the nature of the phases. To analyze the layers’ growth kinetics over the treatment time at a given temperature, two unitless parameters were sought. The boron diffusion coefficients in both phases were evaluated in the range of 900 to 1000°C, and the values of boron activation energies in FeB and Fe₂B were deduced. This model was experimentally verified by considering three boriding conditions: 975°C for 10 h, and 1050°C for 5 and 7 h.