Author
Masayuki Fujiwara
Other affiliations: Japan Atomic Energy Agency, Japan Nuclear Cycle Development Institute
Bio: Masayuki Fujiwara is an academic researcher from Kobe Steel. The author has contributed to research in topics: Creep & Ferrite (iron). The author has an hindex of 20, co-authored 35 publications receiving 2428 citations. Previous affiliations of Masayuki Fujiwara include Japan Atomic Energy Agency & Japan Nuclear Cycle Development Institute.
Topics: Creep, Ferrite (iron), Oxide, Titanium, Flexural strength
Papers
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TL;DR: In this article, the authors reviewed the JNC activities on ODS steel development as "nano-composite materials" and concluded that the ODS-technology development achieved in the field of fast reactors should be effectively spun off to the fusion reactor first wall and blanket structural materials to allow for safe and economical reactor design.
673 citations
TL;DR: In this paper, the α to γ transformation in ODS martensitic steel has been successfully achieved by introducing the α-to-γ transformation in 13Cr-3W ODS ferritic steels.
288 citations
TL;DR: In this article, Fe-0.12C-9Cr-2W ODS martensitic steel claddings were developed by cold-rolling under the softened ferrite phase induced by slow cooling from austenite phase to break up substantially elongated grains produced by cold rolling at the final heat treatment.
Abstract: For use as fuel cladding of liquid metal fast reactors, Fe-0.12C-9Cr-2W ODS martensitic steel claddings were developed by cold-rolling under the softened ferrite phase induced by slow cooling from austenite phase, subsequently by ferrite to austenite phase transformation to break up substantially elongated grains produced by cold-rolling at the final heat-treatment. The produced claddings showed noticeable improvement in tensile and creep rupture strength that are considerably superior to PNC-FMS and even austenitic PNC316 at higher temperature and extended time to rupture. The strength improvement is mainly attributed to titanium addition in ODS martensitic steels through its reduction of Y2O3 particle size and shortening inter-particles spacing. The behavior of oxide particle size reduction is associated with stoichiometry between Y2O3 and TiO2.
184 citations
TL;DR: In this article, the high temperature strengthening mechanism of previously manufactured 12Cr-ODS ferritic steel claddings was clarified, and the grain boundary sliding associated with grain morphology was considered to be controlled by the near Σ11, Σ and Σ19 coincidence boundaries with a (110) common axis.
Abstract: The high temperature strengthening mechanism of previously manufactured 12Cr-ODS ferritic steel claddings was clarified. In the recrystallized 12Cr-2W-0.3Ti-0.24Y2O3-ODS ferritic steel cladding, αY2TiO5 type complex oxide formation was responsible for the drastic reduction of oxide particle size and the resulting shortened distance between particles, which led to superior internal creep rupture strength at 973 K because of the high resistance to gliding dislocation. Internal creep deformation was considered to be controlled by the grain boundary sliding associated with grain morphology: the near Σ11, Σ and Σ19 coincidence boundaries with a (110) common axis.
168 citations
Abstract: As to an oxide dispersion strengthened (ODs) ferritic steel cladding as the promising candidate for long-life core materials of the fast reactors, previously fabricated claddings had inferior internal creep rupture strength in hoop direction and inferior formability due to less ductility. Those unexpected features of ODs claddings are substantially ascribed to the needle-like grain structure excessively elongated along the forming direction. Controlling the grain morphology by applying the recrystallization method to ODs ferritic steel made possible to improve those inferior features. The ranges of Y2O3 and excessive oxygen contents for possibly cold-rolling and recrystallization were revealed, and the effects of extruded temperature and deformation texture on recrystallization characteristics were evaluated. The recrystallized ODs ferritic steel showed superior internal creep rupture strength and ductility. It was demonstrated from those results that cold-rolling manufacturing of ODs cladding at room tem...
143 citations
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TL;DR: The concept of high entropy introduces a new path of developing advanced materials with unique properties, which cannot be achieved by the conventional micro-alloying approach based on only one dominant element as mentioned in this paper.
4,394 citations
TL;DR: In this article, the three major materials challenges for the current and next generation of water-cooled fission reactors are centered on two structural materials aging degradation issues (corrosion and stress corrosion cracking of structural materials and neutron-induced embrittlement of reactor pressure vessels), along with improved fuel system reliability and accident tolerance issues.
1,633 citations
TL;DR: The dynamic recrystallization (DRX) phenomena occurring in different thermo-mechanical processing (TMP) conditions for various metallic materials are reviewed in this article.
1,177 citations
TL;DR: In this paper, an emerging class of nanostructured ferritic alloys (NFAs) have been proposed for high-performance structural alloys with outstanding properties that are sustained under long-term service in ultrasevere environments.
Abstract: Advanced fission and future fusion energy will require new high-performance structural alloys with outstanding properties that are sustained under long-term service in ultrasevere environments, including neutron damage producing up to 200 atomic displacements per atom and, for fusion, 2000 appm of He. Following a brief description of irradiation damage and damage resistance, we focus on an emerging class of nanostructured ferritic alloys (NFAs) that show promise for meeting these challenges. NFAs contain an ultrahigh density of Y-Ti-O-enriched dispersion-strengthening nanofeatures (NFs) that, along with fine grains and high dislocation densities, provide remarkably high tensile, creep, and fatigue strength. The NFs are stable under irradiation up to 800°C and trap He in fine-scale bubbles, suppressing void swelling and fast fracture embrittlement at lower temperatures and creep rupture embrittlement at high temperatures. The current state of the development and understanding of NFAs is described, along wi...
1,021 citations
TL;DR: In this article, a strategy for designing high-performance radiation-resistant materials is based on the introduction of a high, uniform density of nanoscale particles that simultaneously provide good high temperature strength and neutron radiation damage resistance.
844 citations