Author/Authors :
Fournier، نويسنده , , B. and Steckmeyer، نويسنده , , A. and Rouffie، نويسنده , , A.-L. and Malaplate، نويسنده , , J. F. Garnier، نويسنده , , J. and Ratti، نويسنده , , M. and Wident، نويسنده , , P. and Ziolek، نويسنده , , L. and Tournie، نويسنده , , I. and Rabeau، نويسنده , , V. and Gentzbittel، نويسنده , , J.M. and Kruml، نويسنده , , T. and Kubena، نويسنده , , I.، نويسنده ,
Abstract :
Ferritic 14%Cr and 18%Cr ODS steels produced at CEA in round bars or plates were tested mechanically. The present paper reports results obtained in tension, impact, fatigue, creep and toughness tests. These tests were carried out at various temperatures and in different directions. These materials show a pronounced anisotropy at all tested temperatures. No matter the loading, the transversal direction is always found to be far less resistant than the longitudinal one. This anisotropy is mainly observed in terms of damage mechanisms, with intergranular fracture preferentially occurring along the extrusion direction. This intergranular fracture mode leads to very low and anisotropic toughness values and to the absence of tertiairy creep stage, pointing out the unstable nature of fracture, even at high temperature. The unrealistically high values of the Norton exponent measured in creep suggests the existence of a threshold stress, which is consistent with the mainly kinematic nature of the stress as revealed by fatigue tests.
