Towards the full modeling of microstructure evolutions during metal forming industrial processes

The mechanical and thermal properties of metallic materials are strongly related to their microstructure. The understanding and the modeling of the microstructural evolution mechanisms is then crucial when it comes to optimize the forming process and the final in-use properties of the materials. Macroscopic and homogenized models, also called mean-field models are widely used in the industry, mainly due to their low computational cost. They are generally based on empirical laws and thus require many fitting parameters which must be calibrated through experimental testing or lower-scale simulations. Furthermore, given the complexity of modern metallurgical problems, these models may not be accurate enough to capture local but significant events. Thanks to the explosion of computer capacities, finer modeling techniques are now available. These lower scale approaches, the so-called full field models, are based on a full description of the microstructure topology and are used for a wide range of metallurgical mechanisms (recrystallization, grain growth, Smith-Zener pinning, solid/solid phase tranformations and more globally diffusion mechanisms,...). One major difficulty, which will be discussed in this presentation, is to propose an efficient and precise global numerical framework allowing to take into account the principal and concommitant mechanisms at work during metal forming. This objective becomes crucial when industrial applications with realistic thermomechanical paths are considered. The capabilities of recent developments, based on a finite element - levet set numerical framework, to model, at a representative volume element scale, microstructure evolutions during industrial thermomechanical paths and for differents materials will be illustrated.