Review on the EFDA work programme on nano-structured ODS RAF steels

Abstract

The 2008 work programme of the European research project on nano-structured oxide dispersion strengthened (ODS) reduced activation ferritic (RAF) steels is being organized along the four following programmatic lines: (1) improve the present generation of nanostructured ODS RAF steels; (2) start the industrial fabrication of the present generation of nano-structured ODS RAF steels; (3) develop an optimised generation of nano-structured and nano-grained ODS RAF steels; (4) investigate the stability of present and optimised generation of nano-structured ODS RAF steels under creep and irradiation. This paper presents the main objectives of current R&D activities being performed within the European research project on nano-structured ODS RAF steels, the main obtained results and the main future activ-ities in the case of the four programmatic lines mentioned just above.

Positron and nanoindentation study of helium implanted high chromium ODS steels

“…The investigation of complex materials is quite difficult and sensitive task due to their complicate and inhomogeneous structure, thus the examination of model alloys has been mostly preferred round the world [4][5][6]. Therefore, there is only few papers comparing more commercial ODS steels at the same time in term of their radiation stability or only couple works with application of surface nondestructive techniques for their study.…”

Microstructural characterization of ODS ferritic steels at different processing stages

“…Their ultrafine grain matrix and the presence of a dispersion of oxide nanoclusters provide an exceptional combination of high strength at elevated temperatures and low DBTT [1][2][3]. ODS RAF steels are mainly produced with a composition in the range Fe- (12)(13)(14)Cr-(1-2)W-(0.3-0.5)Ti-0.3Y 2 O 3 (wt.%) [4]. Fe and Cr form the stainless steel matrix and W acts as solid solution reinforcement.…”

“…An increase above the optimum Ti content of 0.3 wt.% is not effective in particle refinement [7]. Moreover, it has been found that large TiO 2 particles appear on ODS-RAF materials with 0.5 wt.% Ti, increasing the risk of loss of ductility [4].…”

“…The standard route starts with mechanical alloying (MA) of elemental powders plus yttria, followed by canning and degassing of the alloyed powders, hot isostatic pressing (HIP) and thermomechanical treatments (TMTs) [4]. Unfortunately, the MA step involves several drawbacks such as contamination from grinding media and jars, increase of interstitials elements (O, N, C) associated to long milling times and E. Gil et al / Fusion Engineering and Design xxx (2015) xxx-xxx grinding atmosphere, and batch to batch heterogeneities.…”

Microstructure and mechanical behavior of ODS and non-ODS Fe–14Cr model alloys produced by spark plasma sintering

“…A nanosized dispersion of yttrium oxide in the steel matrix improves the mechanical strength, and the resistance to creep and irradiation induced swelling [4]. Presently, oxide dispersion strengthened reduced activation ferritic steels (ODS RAF steels) are the leading structural materials for nuclear applications under investigation in Europe, Japan and the US [1,[5][6][7]. In order to develop these alloys with the demanded mechanical properties and radiation resistance, the manufacturing route still needs to be optimized.…”