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2003 Fiscal Year Final Research Report Summary

Elucidation and modeling of nano-scale mechanisms of early fatigue damage based on analysis of crystal orientation

Research Project

Project/Area Number 14550074
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Materials/Mechanics of materials
Research InstitutionNagoya University

Principal Investigator

AKINIWA Yoshiaki  Nagoya University, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (00212431)

Co-Investigator(Kenkyū-buntansha) KIMURA Hidehiko  Nagoya University, Graduate School of Engineering, Assistant Professor, 工学研究科, 助手 (60345923)
TANAKA Keisuke  Nagoya University, Graduate School of Engineering, Professor, 工学研究科, 教授 (80026244)
Project Period (FY) 2002 – 2003
KeywordsFatigue / Crack initiation / Crystal orientation / Crack propagation / Slip / Crack closure
Research Abstract

In this study, initiation and propagation behaviors of fatigue cracks were investigated on the basis of the results of the nano-scale observations of slip deformation concern with the crystal orientation. There is a fiber texture of 100 on the rolling plane macroscopically. For the case of the location of crack initiation, the colony which has a 110 fiber texture was observed. In this region, 32 slip systems for [111] directions were activated. The largest Schmid factor is 0.412 for {321}<111> and {132}<111>. These slips can be observed as a line with 70.5 degree from the loading axis on the specimen surface. The slip angle agreed very well with the experimental result. For the ultrafine-grained steels, the cross slips due to those 32 slip systems acted as a very important role for crack initiation. Secondly, mechanism of the propagation behavior of fatigue cracks was investigated on the basis of the slip deformation near the crack-tip and the propagation direction. The slip factor, which was corresponding to the Schmid factor for smooth specimens was proposed by considering the stress singularity near the crack-tip. For the ultrafine-grained steels, large resistance of crack propagation due to crack bifurcation is very important. The mechanism of the bifurcation was investigated. The bifurcation was formed in the direction of the maximum value of the slip factor. For the bifurcation within the grain, when the many slip systems existed on the same slip line, the bifurcation was formed in the grain whose slip direction exists on the specimen surface.

  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] Yoshiaki Akiniwa: "Fatigue crack propagation behavior in ultrafine-grained steel"Proc. 8th Int. Fatigue Cong., FATIGUE 2002. 1. 473-480 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 秋庭 義明: "超細粒鋼(SUF鋼)における疲労き裂発生過程のナノスケール観察"日本機械学会2002年度年次大会講演論文集. 2. 401-402 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 木村英彦: "超細粒鋼(SUF鋼)の疲労き裂伝ぱにおよぼす結晶方位および組織の影響"日本機械学会2003年度年次大会講演論文集. 1. 117-118 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yoshiaki Akiniwa: "Microstructural Effects on Initiation and Propagation of small Fatigue Cracks in Ultrafine-Grained Steel"Abstructs of 2nd International ASTM/ESIS Symposium on Fatigue and Fracture. 39-39 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Hidehiko Kimura: "Investigation of Fatigue Crack Propagation Behavior in Ultrafine-GraineSteel by AFM and EBSP"Proceedings of Advanced Technology in Experimental Mechanics. WS0460 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yoshiaki Akiniwa: "Fatigue crack propagation behavior in ultrafine-grained steel"Proceedings of the 8th International Fatigue Congress, FATIGUE 2002. 1. 473-480 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yoshiaki Akiniwa: "Nanoscopic Observation of Fatigue Crack Initiation Behavior in Ultrafine-Grained Steel"Proceedings of Mechanical Engineering Congress 2002. 2. 401-402 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hidehiko Kimura: "Effect of Crystallographic Orientation and Microstructure on Fatigue Crack Propagation Behavior in Ultrafine-Grained Steel"Proceedings of Mechanical Engineering Congress 2003. 1. 117-118 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yoshiaki Akiniwa: "Microstructural Effects on Initiation and Propagation of small Fatigue Cracks in Ultrafine-Grained Steel"Abstracts of 2nd International ASTM/ESIS Symposium on Fatigue and Fracture. 39 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Hidehiko Kimura: "Investigation of Fatigue Crack Propagation Behavior in Ultrafine-Graine Steel by AFM and EBSP"Proceedings of Advanced Technology in Experimental Mechanics. WS0460. (2003)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2005-04-19  

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