Prediction of Boride Thickness on Tool Steels AISI D2 and AISI H13 Using Boriding Kinetics

Cold and hot work tool steels AISI D2 and AISI H13, respectively, were borided using a packed boriding process. Boriding temperature range of 1123 1223 K was performed with different boriding time up to 6 hr, afterwards, near-surface properties of the borided tool steels AISI D2 and H13 were characterized. Boride layer thicknesses were measured using an optical microscope with an image analyzer program. An X-ray diffraction (XRD) was performed to identify the boride coating layer. Kinetics of boriding process was analyzed using diffusion and Arrhenius equations. Activation energies and empirical data of the boriding process can be finally determined. It was found that the thickness of the boride coating increases with increasing boriding temperature and time taking into account the diffusion and Arrhenius equations. Activation energies of 177.4 and 185.7 kJ/mol were determined for cold and hot work tool steels AISI D2 and AISI H13, respectively. Thus, empirical relationships of boride thickness as a function of boriding temperature and time will be presented. Finally, predicted boride thickness diagram of cold and hot work tool steels AISI D2 and AISI H13, respectively can be established.