Finite Element Modelling Of Tensile Test For Micro-Alloyed Low Carbon Steel At High Temperature
Résumé
In view of the numerical inverse identification of constitutive models, a forward numerical modelling of Gleeble tension tests is conducted. A coupled electrical--thermal--mechanical model is proposed for the resolution of electrical, energy and momentum conservation equations by means of finite element method. In momentum equation, the mixed rheological model in multi--phase region (e.g. δ--ferrite and γ austenite (δ+γ mixture)) is developed to consider the δ/γ phase transformation phenomenon for micro--alloyed low carbon steel at high temperature. Experimental and numerical results reveal that significant thermal gradients exist in specimen along longitudinal and radial directions. Such thermal gradients will lead to phase fraction gradient in specimen at high temperature, such as δ fraction gradient or liquid fraction gradient. All these gradients will contribute to the heterogeneous deformation of specimen and severe stress non--uniform distribution, which is the major difficulty for the identification of constitutive models, especially for the simple identification method based on nominal stress--strain. The proposed model can be viewed as an important achievement for further inverse identification methods, which should be used to identify constitutive parameters for steel at high temperature in the presence of thermal gradients.
Domaines
Matériaux
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