Ortiz-Domínguez, M., Elias-Espinosa, M., Keddam, M., Gómez-Vargas, O A., Lewis, R., Vera-Cárdenas, E. E.,Zuno-Silva, J. (2015), Growth kinetics and mechanical properties of Fe2B layers formed on AISI D2 steel. Indian Journal of Engineering and Materials Sciences 22(2), 231-243.
In the present study, the growth kinetics and mechanical properties of Fe2B layers formed on the AISI D2 steel are investigated. A mathematical model for studying the growth kinetics of Fe2B layers on the AISI D2 steel is proposed for the powder-pack boriding. This process is carried out in the temperature range of 1123-1273 K for treatment time ranging from 2 to 8 h. This kinetic model is based on solving the mass balance equation at the (Fe2B/ substrate) interface to evaluate the boron diffusion coefficients through the Fe2B layers in the temperature range of 1123-1273 K. The formed boride layers are characterized by different experimental techniques such as light optical microscopy, scanning electron microscopy, XRD analysis and the Daimler-Benz Rockwell-C indentation technique. A tribological characterization is also performed using a Plint TE77 tribometer under dry sliding conditions. The boron activation energy for the AISI D2 steel is estimated as 201.5 kJ mol-1 based on our experimental results. This kinetic model is also validated by comparing the experimental Fe2B layer thickness with the predicted value at 1243 K for 5 h of treatment. A contour diagram relating the layer boride thickness to the boriding parameters is suggested to be used in practical applications.