Simulation de la forge d'alliage biphase par la methode des automates cellulaires.

摘要

To understand the phenomena which occur during the forging of two-phase alloys, mathematical models, based on the Eshlby theory and using the cellular automata method (CA), were conceived.; The material studied in this project is a titanium alloy, mainly used in high pressure parts of axial compressors for advanced gas turbine engines. It is quasi alpha, i.e., two-phase with a very small proportion of beta phase has a bimodal structure (equiaxed and lamellar alpha), this alloy combines good properties in creep and fatigue in high temperatures.; Initially, experimental data of hot compression were exploited in the pure beta field and alpha + beta field of titanium alloy IMI 834. To highlight hot deformation behaviour using viscoplastic law, numerical results obtained by CA model were presented.; Calculations by finite element (FE) were proposed to cure certain CA gaps of Eshelby approach by introducing corrective factors. This approach will end up taking into consideration the morphology of the involved phases.; Thus, it proves that the cellular automata method has a good capacity for predicting the mechanical behaviour of two-phase material. These CA show the influence of the forging conditions on the local and global mechanical characteristics of the involved microstructures.