News/Press Release

Japan Atomic Energy Agency (JAEA)
J-PARC
Northeastern University, People's Republic of China
Kyoto University

Discovery of a mechanism that drastically improves stainless steel strength at low temperatures using neutrons
— Strength enhancement without loss of ductility through ultrafine grain refinement —

[Summary of announcement]
  • Generally, metallic materials gain strength at low temperatures but lose ductility. To ensure safety and performance in low temperature environments, materials with both excellent strength and ductility under such conditions are essential.
  • This research discovered that refining the grain size of conventional stainless steel (SUS304) to below 1 micron significantly enhances strength at low temperatures without a notable reduction in ductility. This process does not require special facilities.
  • Neutron diffraction analysis revealed that the excellent strength and ductility at low temperatures of ultrafine-grained SUS304 arise from multiple deformation mechanisms, including gradual changes in crystal structures and defect activity.
  • This finding demonstrates that ultrafine grain refinement could enhance the low temperature mechanical performance of various metallic materials, contributing to the development of advanced structural materials for extreme environments.
[Information on article]
Name of journal: Acta Materialia
Title of article: Martensitic transformation-governed Lüders deformation enables large ductility and late-stage strain hardening in ultrafine-grained austenitic stainless steel at low temperatures
Names of authors (and their organizations): Wenqi Mao a b , Si Gao c , Wu Gong b , Takuro Kawasaki b , Tatsuya Ito b , Stefanus Harjo b , Nobuhiro Tsuji c
Organization of affiliation:
a
Key Laboratory of Electromagnetic Processing of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China
b
J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
c
Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan