Modelling of the Boronizing Kinetics of Vanadis 6 Steel by the Integral Diffusion Model

In this work, the Vanadis 6 steel was subjected to the solid boronizing treatment in the range of 950–1050°C, and for the durations between 0.75 and 10 h. The cross-sectional microstructures of boronized samples were investigated by scanning electron microscope, and the crystalline nature of phases present inside the boride layers was analysed by X-ray diffraction analysis. A kinetic approach basing on the integral diffusion model has been proposed for investigating the diffusion phenomena during the boronizing of examined steel. An adequate change of variables made in the derived system of differential algebraic equations (DAE) was employed to assess the values of boron diffusion coefficients in FeB and Fe2B. Boronizing within the temperature range 950–1050°C produced two-phase layers. These layers manifest less pronounced sawtooth morphology than what is typical for low-alloyed steels or for pure iron. The values of boron activation energies in FeB and Fe2B were 219.70 and 192.88 kJ mol–1.