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A Study on the Micro-mechanisms for the Crack Initiation and Growth Ductile Fracture.

Research Project

Project/Area Number 15360458
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Naval and maritime engineering
Research InstitutionThe University of Tokyo

Principal Investigator

KANEDA Shigehiro  The University of Tokyo, Graduate School of Engineering, Research Associate, 大学院・工学系研究科, 助手 (90010892)

Co-Investigator(Kenkyū-buntansha) TAKAHASHI Jun  The University of Tokyo, Graduate School of Engineering, Associate Professor, 大学院・工学系研究科, 助教授 (10222085)
Project Period (FY) 2003 – 2005
Project Status Completed (Fiscal Year 2005)
Budget Amount *help
¥10,800,000 (Direct Cost: ¥10,800,000)
Fiscal Year 2005: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2004: ¥5,400,000 (Direct Cost: ¥5,400,000)
Fiscal Year 2003: ¥4,700,000 (Direct Cost: ¥4,700,000)
Keywordsductile fracture / stress triaxiality / SM490B / prestrain / AE / dimple / cleavage / 脆性破壊 / 予ひずみ / 応力三軸度 / 相当塑性ひずみ / 柱・梁部材 / 予歪み / 結晶方位 / 粒界 / 相当塑性歪み
Research Abstract

Relations between equivalent plastic strain and stress triaxiality were studied by fracture tests of round notched bar tensile specimens. The critical ductility curves represented by above-described relationship were constructed by fracture test results and FEM analyses.
Base material used in the tests is as received SM490B steel. The yield and ultimate strength at room temperature were 353 and 543 MPa respectively. Compressive prestrain up to 30% plastic strain was given in some specimens. The effects of prestrain and notch radius on ductile fracture initiation behavior were investigated and observed the fractured surface by scanning electron microscope (SEM).
Damage initiation behavior during the tests was detected by use of AE sensors attached to the specimens. It is shown that prestrain leads to cleavage micro-cracking and reduces ductility. From SEM-fractographs, it is found that fractured surface is 100% dimple in as-received material, in the meantime, tiny amounts of cleavage in 10% prestrain material, up to 100% cleavage in 30% prestrain material, respectively.

Report

(4 results)
  • 2005 Annual Research Report   Final Research Report Summary
  • 2004 Annual Research Report
  • 2003 Annual Research Report
  • Research Products

    (2 results)

All 2005

All Journal Article (2 results)

  • [Journal Article] 鋼材の延性破壊発生挙動に及ぼす予ひずみの影響2005

    • Author(s)
      吉成仁志, 榎並啓太郎, 菅 満春, 金田重裕
    • Journal Title

      材料 第54巻

      Pages: 296-301

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2005 Final Research Report Summary
  • [Journal Article] The Effect of Prestrain on ductile Fracture Initiation of Steel2005

    • Author(s)
      Hitoshi Yoshinari, Keitaro Enami, Mitsuharu Kan, Shigehiro Kaneda
    • Journal Title

      Journal of Materials Science JAPAN Vol.54, No3

      Pages: 296-301

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2005 Final Research Report Summary

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Published: 2003-04-01   Modified: 2016-04-21  

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