Boride layer growth kinetics of the borided hypoeutectoid plain carbon steels by the powder-pack method

In the present work, kinetics of boriding of hypoeutectoid plain carbon steels has been studied. Boriding of the AISI 1010, 1020, 1040 and 1060 test materials has been performed by means of a powder-pack method using EKabor 2 R powders. Boriding heat treatments were performed at 1173 K, 1223 K, 1273 K and 1323 K for 2, 4 and 6 In. The borided materials were characterised by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and optical microscopy in order to determine the phase contents (FeB and Fe2B). Boride layer thickness was determined by optical microscopy and hardness by microhardness testing. The thickness of borided layers measured ranged from 71 to 362 mu m. It was found that the effect of boriding time and temperature on the increasing boride layer thickness was more significant than the effect of increasing the carbon content. The hardness of the boride layers ranged from 1243 to 1740 HV. The kinetics of the reactions, K= K(0)exp(-Q/RT), were determined by varying the boriding temperature and time for the materials. A correlation between the C content and activation energy has been established by this study.