Microstructural anisotropy effect on the mechanical properties of a 14Cr ODS steel

During the last years in the field of materials for energy production, oxide dispersion strengthened (ODS) alloys have been reintroduced as candidate materials for high temperature and aggressive operating conditions. In particular, the Fe-ODS alloys developed in the 1970s for fast reactor cladding are being improved under various national and international projects. One of the main open issues in the use of ODS alloys as fuel cladding is their anisotropy, characteristic of extruded alloys. The aim of this work is to investigate the effect of the anisotropy of an extruded bar of a14Cr ODS on the tensile properties. The microstructure in longitudinal direction (L, parallel to the extrusion direction) is characterized by grains elongated along the extrusion direction, while in the transverse direction (T, perpendicular to the direction of extrusion) grains are smaller and more equiaxed. This microstructural anisotropy is reflected in a loss of ductility in the transverse direction. Furthermore, after tensile tests different fracture mode are observed depending on the orientation under study.