Oxide Dispersion Strengthened Eurofer Research Articles

Applicability Study of Pulsed Laser Beam Welding on Ferritic–Martensitic ODS Eurofer Steel

Pulsed laser beam welding was used successfully to join the oxide dispersion-strengthened (ODS) Eurofer steel. The joining was conducted with a laser power of 2500 W and a pulsed duration of 4 ms. With the filler material being used, a minor material loss and microvoids were observed in the joint. The microstructure of the fusion zone consists of dual phase elongated structures. The heat-affected zone has a width of around 0.06 mm with finer grains. The transmission electron microscopy observation reveals that nanoprecipitates are finely distributed in the fusion zone. The tensile strength, yield strength and elongation of the joint are slightly inferior to the base material. The fractography results reveal a typical ductile fracture. The experimental results indicate a reasonable joint from the perspective of both the microstructure and mechanical behaviour.

Joining of oxide dispersion strengthened Eurofer steel via spark plasma sintering

Abstract This paper studies the joining of an oxide dispersion strengthened (ODS) steel without destroying the microstructure and thereby deteriorating the mechanical performance. ODS Eurofer was successfully joined by spark plasma sintering (SPS) at 1373 K with a heating rate of 100 K/min and a pressure of 80 MPa. An almost defect-free joint was obtained with a holding time of 40 min and a powder layer between the steel disks. The fine-grained microstructure and homogeneously distributed nanoparticles in the material show no significant change after the joining process. The tensile properties of the joint material are comparable to the base material. SPS has been proven to be a promising technique to join ODS steels due to the good mechanical properties of the joints.

Transmission electron microscopy study of the heavy-ion-irradiation-induced changes in the nanostructure of oxide dispersion strengthened steels

Transmission electron microscopy was used to study the effect of heavy-ion irradiation on the structure and the phase state of three oxide dispersion strengthened (ODS) steels: ODS Eurofer, ODS 13.5Cr, and ODS 13.5Cr–0.3Ti (wt %). Samples were irradiated with iron and titanium ions to fluences of 1015 and ~3 × 1015 cm–2 at 300, 573, and 773 K. The study of the region of maximum radiation damage shows that irradiation increases the number density of oxide particles in all samples. The fraction of fine inclusions increases in the particle size distribution. This effect is most pronounced in the ODS 13.5Cr steel irradiated with titanium ions at 300 K to a fluence of 3 × 1015 cm–2. It is demonstrated that oxide inclusions in ODS 13.5Cr–0.3Ti and ODS 13.5Cr steels are more stable upon irradiation at 573 and 773 K than upon irradiation at 300 K.

Irradiation hardening of Fe–9Cr-based alloys and ODS Eurofer: Effect of helium implantation and iron-ion irradiation at 300 °C including sequence effects

Single-beam, dual-beam and sequential iron- and/or helium-ion irradiations are widely accepted to emulate more application-relevant but hardly accessible irradiation conditions of generation-IV fission and fusion candidate materials for certain purposes such as material pre-selection, identification of basic mechanisms or model calibration. However, systematic investigations of sequence effects capable to critically question individual approaches are largely missing. In the present study, sequence effects of iron-ion irradiations at 300 °C up to 5 dpa and helium implantations up to 100 appm He are investigated by means of post-irradiation nanoindentation of an Fe9%Cr model alloy, ferritic/martensitic 9%Cr steels T91 and Eurofer97 and oxide dispersion strengthened (ODS) Eurofer. Different types of sequence effects, both synergistic and antagonistic, are identified and tentative interpretations are suggested. It is found that different accelerated irradiation approaches have a great impact on the mechanical hardening. This stresses the importance of experimental design in attempts to emulate in-reactor conditions.