Three-dimensional numerical simulation of the nitriding process

This paper presents a three-dimensional numerical simulation of a nitriding process applied to an industrial component. The aim of the simulation is to predict the residual stresses and distortions due to Volume changes induced by chromium nitride (CrN) and carbides (M23C6 et M4C3) formation. The simulation is performed in two steps. The diffusion of nitrogen and the precipitation of chronic nitride and carbides are first simulated. Then stresses and strains are calculated, assuming ail elastic behaviour of the component, and using a volume expansion due to the precipitate concentration. The proposed approach is applied on a gear tooth. Small holes and details were neglected. For symmetry reasons, only half a tooth is taken into account. As the main phenomena take place through the first millimetre from the outer surface, a special attention was paid on meshing. The mesh used for the diffusion and precipitation analysis is composed of 1130000 nodes and 1110000 elements. For the mechanical analysis, a coarser mesh including only 165000 nodes and 290000 elements was used.