Numerical Simulation of the Crystallographic Texture Evolution during Hot Extrusion of Oxides Dispersed Strengthened Steels
Résumé
Oxides Dispersed Strengthened (ODS) stainless steels are foreseen for fuel cladding tubes in the coming generation of fission nuclear reactors. In spite of a bcc matrix, those steels present a convenient creep behavior thanks to very fine oxides dispersion. Those grades are currently obtained by Powder Metallurgy (PM). After mechanical alloying with the oxide, the powder is commonly consolidated as seamless tube. On CEA facilities, new ferritic ODS stainless steels are produced by Hot Extrusion (HE). The control of the microstructure after extrusion is a key issue for this grade regarding service conditions. In order to explain the microstructure induced by hot processing, the thermo-mechanical history applied to the material must be taken into account. In this study, the strain and thermal histories are obtained from Finite Element Method simulation. Thus, crystallographic texture development during hot extrusion of ODS ferritic steels is simulated using a Visco-Plastic Self-Consistent (VPSC) model. By comparing the texture predictions with the experimental observations, it is shown that self-consistent model reproduces the extrusion texture, α-fiber, very well in the case of monotonic loading. However, for complexes strain path observed during HE, VPSC results differ from the experimental deformation texture.