Zhiming Huang, Yuhang Liu, Xuyang Zhao
To clarify the interfacial diffusion law and mechanism of a C276/Q370R explosion-welded clad plate during post-weld heat treatment, a molecular dynamics model was established and used to analyze atomic migration behavior at the interface. A simplified Fe/Cr/C interfacial system was adopted to capture the dominant thermally activated diffusion trends, and the effects of temperature on atomic distribution, mean square displacement (MSD), concentration profile, interdiffusion width, apparent diffusion coefficient, and activation energy were evaluated. The results show that Fe, Cr, and C atoms remain in a thermally activated diffusion state throughout the simulation, and their migration capability increases monotonically with temperature. As the temperature increases from 700 to 1200 °C, the terminal MSD values of Fe, Cr, and C rise from 1613.42 to 2615.60 Å2, from 1562.08 to 2498.75 Å2, and from 2556.53 to 4062.64 Å2, respectively. The corresponding apparent diffusion coefficients increase from 17.21 to 28.70, from 16.60 to 27.19, and from 27.54 to 44.69 {\times10}^{-7}m^2s^{-1}, respectively. The interdiffusion layer width expands from 73.191 to 84.120 Å, while the fraction of carbon redistributed to the Cr-side representative region increases from 14.358% to 18.807%. Arrhenius fitting indicates activation energies of 11.805 kJ\centerdot{mol}^{-1} for Fe, 11.804 kJ\centerdot{mol}^{-1} for Cr, and 11.402 kJ\centerdot{mol}^{-1} for C, confirming that carbon diffusion dominates the interfacial transport process. These results provide an atomistic basis for understanding carbide precipitation, decarburization-layer formation, and interfacial property evolution during heat treatment.
Explosion-welded clad plate; Molecular dynamics; Interfacial diffusion; Heat treatment; C276/Q370R; Carbon migration