Numerical Simulation of Full Carburizing Process of an Automotive Gear
Because of the nature of the carburizing process, which mostly treats a thin area under the surface of the product, the mesh must be adapted accordingly in an efficient manner. Consequently, anisotropic mesh and re-meshing are used. Additionally, the temporal discretization, also named time step must be adapted accordingly to follow carbon diffusion and thermal evolution.
The material model represents metallurgical phenomena during the complete carburizing process, consisting of austenization, carburizing, and cooling. The model takes into account the phases evolution using phase transformation diagrams locally adapted to chemical compositions and grain sizes.
The objective of this type of simulation is to predict the in-use properties of the gear at the end of the carburizing process. Other important results are the assessment of distortion and residual stresses. Phases evolution induces volume variation and transformation plasticity. During the complete process, the material is modelled with an elasto-viscoplastic behavior and mixing methods are applied to consider the relative contribution of each phase.