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Mechanism of delayed fracture in fail-safe steel with an ultrafine elongated grain structure

Research Project

Project/Area Number 19H02468
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Review Section Basic Section 26040:Structural materials and functional materials-related
Research InstitutionNational Institute for Materials Science

Principal Investigator

KIMURA Yuuji  国立研究開発法人物質・材料研究機構, 構造材料研究センター, 主席研究員 (80253483)

Project Period (FY) 2019-04-01 – 2024-03-31
Project Status Completed (Fiscal Year 2023)
Budget Amount *help
¥17,420,000 (Direct Cost: ¥13,400,000、Indirect Cost: ¥4,020,000)
Fiscal Year 2023: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2022: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2021: ¥3,770,000 (Direct Cost: ¥2,900,000、Indirect Cost: ¥870,000)
Fiscal Year 2020: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2019: ¥7,280,000 (Direct Cost: ¥5,600,000、Indirect Cost: ¥1,680,000)
Keywords構造材料 / 鉄鋼 / 加工熱処理 / 水素脆化 / 遅れ破壊 / 構造・機能材料 / 材料加工・処理 / 鉄鋼材料
Outline of Research at the Start

本研究では、引張強さが1800~2000MPa級の超高強度鋼およびボルトなどの超高強度部品の社会実装に向けての最重要課題である耐遅れ破壊特性を担保するための基盤研究を行う。 超微細繊維状結晶粒組織の制御によって「部材の一部が破壊・破損しても所定の荷重以下であれば部材そのものは完全に破断しない」というフェールセーフ機能を有する鋼(フェールセーフ鋼)の遅れ破壊挙動を水素侵入挙動と関連付けて調査し、実使用環境での遅れ破壊機構を解明する。その結果、超高強度部材の遅れ破壊を克服するための指針を得る。

Outline of Final Research Achievements

In this study, 1800-2000 MPa-class ultra-high strength low-alloy steels with ultrafine elongated grain structures were created by a thermomechanical treatment. The notched round-bar specimens and ultra-high strength bolts that were fabricated from the ultra-high strength low-alloy steels were fastened and subjected to outdoor exposure tests at the exposure site in National Institute for Materials Science, and at the in Miyako Island test site of Japan Weathering Test Center, respectively. Delayed fracture behavior of the ultra-high strength low-alloy steels was clarified in association with the ultrafine elongated grain structures, hydrogen uptake and the data obtained by accelerated delayed fracture tests.

Academic Significance and Societal Importance of the Research Achievements

次世代の新鋼構造物の実現や自動車等のさらなる軽量化で必要とされる超高強度鋼の社会実装では、材料および部材がその使用中に突然、破断するという遅れ破壊の克服が大きな課題となっている。本研究では、超高強度鋼が遅れ破壊しやすいことに着目して、つくば市のマイルドな大気腐食環境下でも応力負荷条件等の制御により数か月程度の短期間で遅れ破壊を発生させ、その挙動を観察したことは学術的意義が高い。さらに様々な金属組織を有する超高強度鋼材に今回開発した手法を展開してデータを収集することで遅れ破壊を克服した超高強度鋼材開発への貢献が期待できる。

Report

(6 results)
  • 2023 Annual Research Report   Final Research Report ( PDF )
  • 2022 Annual Research Report
  • 2021 Annual Research Report
  • 2020 Annual Research Report
  • 2019 Annual Research Report
  • Research Products

    (18 results)

All 2024 2023 2022 2021 2020 2019 Other

All Journal Article (7 results) (of which Peer Reviewed: 6 results,  Open Access: 5 results) Presentation (8 results) (of which Int'l Joint Research: 5 results,  Invited: 4 results) Remarks (3 results)

  • [Journal Article] MASS PRODUCTION TRIAL OF 1700 MPA CLASS ULTRA-HIGH-STRENGTH BOLTS AND SLIP RESISTANCE OF FRICTION TYPE BOLTED JOINTS WITH THEM2024

    • Author(s)
      森山 仁志、木村 勇次、山口 隆司、津﨑 兼彰、増田 浩志、長崎 英二、秦 子策
    • Journal Title

      Kou kouzou rombunshuu

      Volume: 30 Issue: 120 Pages: 120_115-120_127

    • DOI

      10.11273/jssc.30.120_115

    • ISSN
      1880-9928, 1884-0329
    • Year and Date
      2024-01-26
    • Related Report
      2023 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Influence of Annealing on Delamination Toughening of Mo-Bearing Medium-Carbon Steel with Ultrafine Elongated Grain Structure Processed by Warm Tempforming2022

    • Author(s)
      Kimura Yuuji、Inoue Tadanobu
    • Journal Title

      ISIJ International

      Volume: 62 Issue: 2 Pages: 402-404

    • DOI

      10.2355/isijinternational.ISIJINT-2021-068

    • NAID

      130008160450

    • ISSN
      0915-1559, 1347-5460
    • Year and Date
      2022-02-15
    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Influence of Thermomechanical Treatment on Delayed Fracture Property of Mo-Bearing Medium-Carbon Steel2022

    • Author(s)
      Kimura Yuuji、Moronaga Taku、Inoue Tadanobu
    • Journal Title

      ISIJ International

      Volume: 62 Issue: 2 Pages: 377-388

    • DOI

      10.2355/isijinternational.ISIJINT-2021-407

    • NAID

      130008160458

    • ISSN
      0915-1559, 1347-5460
    • Year and Date
      2022-02-15
    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Preferable Resistance against Hydrogen Embrittlement of Pearlitic Steel Deformed by Caliber Rolling2022

    • Author(s)
      Ueji Rintaro、Kimura Yuuji、Inoue Tadanobu
    • Journal Title

      ISIJ International

      Volume: 62 Issue: 2 Pages: 368-376

    • DOI

      10.2355/isijinternational.ISIJINT-2021-429

    • NAID

      130008160461

    • ISSN
      0915-1559, 1347-5460
    • Year and Date
      2022-02-15
    • Related Report
      2021 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] 耐遅れ破壊特性に優れた超高強度フェールセーフボルトの創製2022

    • Author(s)
      木村勇次、井上忠信
    • Journal Title

      自動車技術

      Volume: 76 Pages: 24-29

    • Related Report
      2022 Annual Research Report
  • [Journal Article] Mechanical Property of Ultrafine Elongated Grain Structure Steel Processed by Warm Tempforming and Its Application to Ultra-High-Strength Bolt2020

    • Author(s)
      Kimura Yuuji、Inoue Tadanobu
    • Journal Title

      ISIJ International

      Volume: 60 Issue: 6 Pages: 1108-1126

    • DOI

      10.2355/isijinternational.ISIJINT-2019-726

    • NAID

      130007856002

    • ISSN
      0915-1559, 1347-5460
    • Year and Date
      2020-06-15
    • Related Report
      2020 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] 2000 MPa級超高強度ボルトの開発2019

    • Author(s)
      木村勇次、井上忠信
    • Journal Title

      橋梁と基礎

      Volume: 53 Pages: 109-112

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Presentation] Improvement of Delayed Fracture Property for Mo-bearing Ultra-high Strength Steel by Thermomechanical Treatments; Ausforming vs Warm Tempforming2023

    • Author(s)
      Yuuji Kimura, Taku Moronaga and Tadanobu Inoue
    • Organizer
      International Conference on PROCESSING & MANUFACTURING OF ADVANCED MATERIALS Processing, Fabrication, Properties, Applications; Thermec2023
    • Related Report
      2023 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Hydrogen-induced Delayed Fracture Properties for Ultra-high Strength Low-alloy Steels Processed by Thermomechanical Treatments; Ausforming vs Warm Tempforming2023

    • Author(s)
      Yuuji Kimura, Taku Moronaga and Tadanobu Inoue
    • Organizer
      28th IFHTSE Congress
    • Related Report
      2023 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Hydrogen Embrittlement of Ultrafine Elongated Grain Structure Steel2023

    • Author(s)
      Yuuji Kimura and Tadanobu Inoue
    • Organizer
      MRM2023/IUMRS-ICA2023
    • Related Report
      2023 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 温間テンプフォーミングで創製した超高強度ボルトの遅れ破壊2023

    • Author(s)
      木村勇次、井上忠信
    • Organizer
      日本熱処理技術協会 第96回(2023年秋季)講演大会
    • Related Report
      2023 Annual Research Report
  • [Presentation] Delayed Fracture Behavior of Ultra-High-Strength Low-Alloy Steel Processed by Warm Tempforming2022

    • Author(s)
      Yuuji Kimura and Tadanobu Inoue
    • Organizer
      ICAS2022
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research
  • [Presentation] Delayed Fracture Property of 1800-MPa-Class Ultra-high-Strength Steel with an Ultrafine Elongated Grain Structure2021

    • Author(s)
      Kimura.Yuuji、Inoue Tadanobu
    • Organizer
      THERMEC‘2021
    • Related Report
      2021 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] 温間テンプフォーミングによる超高強度鋼 およびボルトの開発2020

    • Author(s)
      木村勇次
    • Organizer
      2020年度第1回「水素脆化の基本要因と実用課題」フォーラム会合(日本鉄鋼協会)
    • Related Report
      2020 Annual Research Report
    • Invited
  • [Presentation] 温間加工による超高強度鋼の開発2020

    • Author(s)
      木村勇次
    • Organizer
      日本鉄鋼協会
    • Related Report
      2019 Annual Research Report
    • Invited
  • [Remarks] SAMURAI

    • URL

      https://samurai.nims.go.jp/profiles/kimura_yuuji/publications#article

    • Related Report
      2023 Annual Research Report
  • [Remarks]

    • URL

      https://samurai.nims.go.jp/profiles/kimura_yuuji/publications#article

    • Related Report
      2022 Annual Research Report
  • [Remarks] NIMS研究者総覧SAMURAI

    • URL

      https://samurai.nims.go.jp/profiles/kimura_yuuji

    • Related Report
      2021 Annual Research Report

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Published: 2019-04-18   Modified: 2025-01-30  

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