Boride layer growth kinetics of the borided high alloyed steels

Abstract

In this study, the case properties and diffusion kinetics of high alloyed cold work tool steel borided in Ekabor-2 powder were investigated by conducting a series of experi-ments at temperatures of 1123, 1173 and 1223 K for 2, 4 and 6 h. The boride layer was characterised by optical microscopy, X-ray diffraction technique and micro-Vickers hardness tester. X-ray diffraction analysis of boride layers on the surface of the steels revealed the existence of FeB, Fe2B, CrB, Cr2B and MoB compounds.Depending on the chemical composition of substrates and boriding time, the boride layer thickness on the surface of the steel ranged from 13.14 and 120.82 μm. The hardness of the boride compounds formed on the surface of the steels ranged from 1806 to 2342 HV0.05, whereas the Vickers hardness value of the untreated steels was 428 HV0.05. The activation energy (Q) of the borided steel was 287.019 kJ/mol.