Finite Element modeling of the carburizing-quenching process in steels

Carburizing-quenching is a thermochemical surface treatment designed to harden the surface of steels and make them more resistant to friction, wear, and corrosion. It involves the diffusion of carbon atoms at high temperature, followed by rapid cooling to induce a phase transformation from austenite to martensite. This process therefore combines a diffusion process, possibly assisted by stress fields, a heat transfer process, and metallurgical transformations, which interact and induce residual stresses, linked to various deformations connected to the coupled processes involved. The objective of this work is to develop a finite element model to capture these residual stresses, together with composition gradients in the material. This model, based on the Abaqus finite element software, relies on numerous user subroutine, allowing the highly coupled resolution of the physics associated with carburizing-quenching. This model is applied to a simple structure inspired by previous works in the literature, the results highlight that mechanical fields have a significant influence on both diffusion and residual stress profiles, particularly near the surface. Neglecting these effects can lead to substantial errors in the prediction of local composition and mechanical performance.