Estimation of Fe2B growth on low-carbon steel based on two diffusion models

Two different approaches are used in the evaluation of Fe2B growth and its kinetics over the surface of AISI 1018 steel. The first approach considers a diffusion model based on the mass balance at the growing Fe2B/substrate interface. In the second approach, the method of dimensional analysis was applied to obtain an expression for the boride layer thickness as a function of dependence parameters involved in the boriding process. The Fe2B layers were formed by the paste boriding process at temperatures of 1 123 to 1 273 K with 2, 4, 6, and 8 h of exposure using a boron carbide paste thickness of 4 mm over the surface of the steel. Another set of boriding temperatures with 5 h of exposure were used on the surface of the steel to compare the experimental values of Fe2B layer thicknesses with the results obtained by both diffusion models. The predicted values showed good agreement with the experimental boride layer thicknesses achieved in this work.