Research progress on numerical simulation of vacuum carburization of steel

Vacuum carburizing is an advanced surface-treatment process used for gears and other high-duty steel components because it provides a uniform case, controllable case depth, and limited oxidation. This review summarizes numerical methods for vacuum carburizing, with emphasis on process parameters, surface carbon transfer, carbon diffusion, carbon-concentration fields, phase transformation, residual stress, and distortion. Early calculations based on Fick's law and empirical diffusivity relations have developed into coupled finite-element models of carburizing and quenching. Recent studies from 2024 to 2026 further introduced carbon-level-dependent diffusion calibration, full-process multiphysics simulation, and machine-learning surrogate models for rapid carbon-field prediction. Across these approaches, predictive accuracy depends primarily on realistic carbon-flux boundary conditions, alloy- and concentration-dependent diffusivity, internally consistent material data, and geometry-resolved experimental validation. Future work should combine physically based models, uncertainty analysis, and reduced-order prediction to support robust process optimization and closed-loop control.