The effective boron diffusion coefficient in Fe2B layers with the presence of chemical stresses

Abstract

In this study the effective boron diffusion coefficient (D eff ) was estimated in the Fe2B layer in the presence of chemical stresses. Boride layers were created at the surface of AISI 1018 borided steels by the paste boriding process, in which a 4-mm-thick layer of boron carbide paste was applied to the material surface. The treatment was carried out at 1123, 1173, 1223 and 1273 K with different exposure times for each temperature. The effective boron diffusion coefficients in the Fe2B layer were estimated by combining an expression that considers the stresses in the boride layer and the flux equation. In addition, an expression to evaluate the boride layer thickness was developed, and the calculated results were compared with the experimental data and the empirical models proposed in the literature. K e y w o r d s : boriding, growth kinetics, boride layers, effective boron diffusion coefficient, chemical stress

Investigation of boriding kinetics of AISI D2 steel

“…To ensure the reproducibility of the measured layers thicknesses, 50 measurements were collected in different sections of the borided AISI D2 steel samples to estimate the Fe 2 B layer thickness; defined as an average value of the long boride teeth. [25][26][27][28][29] X-ray diffraction studies used an (Equinox 2000) diffractometer with Co K a radiation of wavelength 0?179 nm for determining the the different borides. The elemental distribution within the cross-section of boride layer was determined by electron dispersive spectroscopy (EDS) equipment (JEOL JSM 6300 LV) from the surface.…”

Boriding kinetics of Fe2B layers formed on AISI 1045 steel

“…The OM observations revealed the formation of Fe,B layers with a saw tooth morphology. This particular morphology is observed in the boride layers formed on low-carbon steels [25][26][27][28][29][30] and Armco iron [4,12,15,16] due to the absence of alloying elements in the substrate.…”

Boriding kinetics and mechanical behaviour of AISI O1 steel

“…10 The most frequently used method is pack boriding because of its technical advantages and cost effectiveness. 11,12 In a kinetic point of view, several mathematical models concerning the growth kinetics of Fe 2 B layers on different substrates 9,[13][14][15][16][17][18][19][20][21][22][23][24][25][26] were suggested in the literature. These approaches are considered as a tool to select the adequate boride layers thicknesses for practical applications.…”