Development of Adapted Material Testing for Cold Pilgering Process of ODS Tubes

Abstract

Development of fast-neutron sodium-cooled Generation IV reactors is resulting in extremely severe environment conditions for cladding tubes [1]. Both temperature and irradiation level will increase compared to the nowadays conditions. Due to their characteristics in irradiated environment, the oxide dispersion strengthened (ODS) ferritic and martensitic steels are natural candidate cladding materials[2]. However, they exhibit low deformation capabilities at room temperature, leading to problematic issues for forming such as pilgering. In order to improve the fabrication route for tubes, both metallurgical and numerical approaches can be conducted [3,4,5]. To reach predictive description of damage location and evolution, an adapated Latham and Cockoft model has been developed. This model is, of course, highly depending on the stress and strain prediction of the numerical model which itself is linked to the behavior law. In this work, we will describe an adapted material test developed in order to reproduce the cyclic, non uniform loading of the material during pilgering. An advanced cyclic beahvior law is introduced in the software. The model of Chaboche using 2 isotropic and 2 kinematic variables is chosen[6]. An inverse analysis procedure is used to identify both isotropic and kinematic hardening parameters. The results obtained using the identified behavior law are compared to both experimental observation and to other models including monotonic or cyclic laws identified on traditional test.