Determination of the Diffusion Coefficients of Boron in the FeB and Fe₂B Layers Formed on AISI D2 Steel

Abstract

In the present work, a diusion model was applied to estimate the boron diusion coecients in the FeB and Fe2B layers during the pack-boriding of AISI D2 steel in the temperature range of 12231323 K during a variable exposure time between 1 and 8 h. The mass balance equations were formulated at each growing interface by considering the eect of boride incubation times. The estimated values of boron activation energies in the FeB and Fe2B layers were compared with the literature data. Validation of the present model was made by comparing the experimental thickness of each boride layer, taken from the literature data, with the predicted values. In addition, a simple equation was suggested to estimate the required time to obtain a single Fe2B layer by diusion annealing.

Oxygen Induced Phase Transformation in TC21 Alloy with a Lamellar Microstructure

“…Figure 11 indicates that the thickness of the compound layer of TC21 alloy with a lamellar microstructure after oxygen uptake at 960 °C is 1 μm, while it is 1.8 μm at 1000 °C. Secondly, as the temperature increases, the incubation time of the compound decreases, thereby inhibiting the further ingress of oxygen [26]. Thirdly, as the temperature increases, the recrystallization decrease the density of dislocations.…”

Diffusion Model for Simulating the Kinetics of Boronizing Process in the Case of FeB/Fe2B Bilayer Configuration

“…The boron diffusion coefficients in the iron borides and the Fe phase were taken from references [2,20] which are given by the following expressions: With R=8.314 J/mol K The value of the boron concentration at the surface used in the simulation is Cs=16.48(wt%). For the two interfaces (FeB/Fe2B) and (Fe2B/Fe), we used the values taken from the literatures [20,21] which are the following:…”

Application of integral method for investigating the boriding kinetics of AISI 316 steel

“…For these reasons, the modeling of boriding kinetics is crucial for optimizing the desired boride layer thickness that matches the practical utilization of borided steels at industrial scale. To reach this objective, several studies were devoted in the literature for modeling the boriding kinetics of ferrous alloys: (Armco iron [3][4][5][6], steels [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] and cast irons [25][26][27][28]) by using different approaches.…”

“…Finally, the present model was experimentally verified for two additional boriding conditions (1243 K for 3 and 5 h) by comparing the predicted results with the experimental values. [10,22,24]. C DZ up (= 35 Â 10 À4 wt.%B) and C DZ low (= 0.00 wt.% B) represent the upper and lower boron concentrations in the diffusion zone [23].…”