Boriding Kinetics of FeB and Fe2B Layers on AISI M2 Steel by the Integral Diffusion Model

Abstract

The purpose of this work is to investigate the boronizing kinetics of AISI M2 steel by using the integral diffusion model with consideration of boride incubation periods. This simulation model was established by solving the differential algebraic equations (DAE) resulting from the integral method in the temperature range of 1173 to 1323 K. By using a particular solution of the obtained DAE system, the values of boron diffusivities in the FeB and Fe2B layers were estimated. The estimated values of activation energies for boron diffusion in AISI M2 steel were respectively 228.06 kJ mol-1 and 212.10 for FeB and Fe2B. Finally, a comparison was made between the simulated thicknesses of FeB and Fe2B layers and the experimental values obtained at 1173, 1223, 1273 and 1323 K for 10 h. The findings of this research work may serve as a tool to simulate the boronizing kinetics of any steel with a microstructure consisting of FeB and Fe2B layers versus the boriding parameters (the time and the temperature).

Simulating the Growth of Dual-Phase Boride Layer on AISI M2 Steel by Two Kinetic Approaches

“…where R denotes the ideal gas constant (=8.314 J mol −1 K −1 ) and T the boriding temperature given in Kelvin. Table 5 gives a comparison between the reported values of boron activation energies for some steels with the present values found in this work [9,13,18,[22][23][24]26,32,[38][39][40][41][42][43][44]. At first glance, there are some differences in terms of activation energies.…”

“…This kinetic model [25,26] has been used to predict the layers' thicknesses of FeB and Fe 2 B formed on the surface of AISI M2 steel in case of a saturated matrix with boron atoms. Figure 1 shows in a schematic way the change in the boron concentrations across the FeB and Fe 2 B layers after a treatment time greater than the incubation period.…”

“…Figure 1 shows in a schematic way the change in the boron concentrations across the FeB and Fe 2 B layers after a treatment time greater than the incubation period. The terms [26]. The variable u(t) is the location of the (FeB/Fe 2 B) interface and v(t) that of the second interface (Fe 2 B/substrate).…”

“…Kinetically, different kinetic approaches have been established to control the growth kinetics of compact layers composed of Fe 2 B [15][16][17][18][19][20][21][22] or (FeB and Fe 2 B) [23][24][25][26][27][28][29][30][31][32][33][34][35] and formed on ferrous alloys. All these mathematical models help to select the optimum values of boride layers' thicknesses according to the requirements imposed by the utilization of these ferrous materials in the industry.…”

“…In this research paper, the integral method [25,26] with a new variable changes and the Dybkov model [25,28] were suggested for simulating the boronizing kinetics of AISI M2 steel in the range of 1173 to 1323 K by using the experimental results [23].…”