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Resistance against Creep-Fatigue Realized by Anisotropic and Composite Structure

Research Project

Project/Area Number 08455059
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Materials/Mechanics of materials
Research InstitutionKYOTO UNIVERSITY

Principal Investigator

OHTANI Ryuichi  Kyoto Univ., Eng., Professor, 工学研究科, 教授 (50025946)

Co-Investigator(Kenkyū-buntansha) TSUTSUMI Mitsuyoshi  Kyoto Univ., Energy Sci., Instructor, エネルギー科学研究科, 助手 (70293925)
TADA Naoya  Kyoto Univ., Eng., Instructor, 工学研究科, 助手 (70243053)
KITAMURA Takayuki  Kyoto Univ., Eng., Associate Professor, 工学研究科, 助教授 (20169882)
Project Period (FY) 1996 – 1997
Project Status Completed (Fiscal Year 1997)
Budget Amount *help
¥8,300,000 (Direct Cost: ¥8,300,000)
Fiscal Year 1997: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1996: ¥5,700,000 (Direct Cost: ¥5,700,000)
KeywordsAnisotropic and composite structure / Fatigue / Creep-fatigue / Intermetallic compound / Ni-based superalloy / Microcrack / Macrocrack / 高温強度 / 微小き裂
Research Abstract

In order to examine a method for attaining higher resistance of heat-resisting alloys against fatigue and creep-fatigue at high temperatures, fatigue and creep-fatigue tests were carried out for an intermetallic compound TiAl and a unidirectianally solidified Ni-based superalloy Mar-M247LC.Both alloys are composed of anisotropic structure, such as lamellate structure of gamma and alpha2 phases, and columnar(or elongated)grains. The followings are the results obtainde for TiAl. (1)In the early stage of fatigue at high temperature, microcracks were initiated on the surface of the specimen both at casting defects and at lamellar interfaces in the grain. (2)As most of the microcracks initiated at lamellar interfaces were arrested, the main crack was formed by one of the cracks initiated at relatively large casting defects. (3)While the growth rate of the microcracs was scattered widely, the aberage rate agreed with the fracture mechanics law which was obtained by propagation tests of macro … More rack using notched specimens. It is therefore possible to estimate the fatigue life of TiAl by fracture mechanics.
The followings were clarified by the creep-fatigue tests for unidirectionally solidified Mar-M247LC.(1)In creep-fatigue with uniaxial loading parallel to the solidification direction(i.e., O degree-specimen), microcracks were initiated at small segments of wavy grain boundary where the grain boundary was locally perpendicular to the stress axis direction. (2)Most of the cracks were arrested when the crack tips reached the end of the perpendicular segment. The crack, which grew into the grain out of the grain boundary, became one of the largest cracks and brought about the final fracture of the specimen. (3)Creep-fatigue tests were also carried out changing the loading direction against solidification direction(i.e., using 45 degree-and 90 degree-specimens). Independent of the loading direction, microcracks were always initiated at the perpendicular segments. As the proportion of the perpendicular segments becomes the largest, the number of cracks was maximum in 90 degree-specimen, and this specimen showed the minimum life among three specimens under the same creep-fatigue condition. Less

Report

(3 results)
  • 1997 Annual Research Report   Final Research Report Summary
  • 1996 Annual Research Report
  • Research Products

    (8 results)

All Other

All Publications (8 results)

  • [Publications] M.Tsutsumi: "Microcracking Behavior and Life Law of Fatigue in a Cast TiAl Intermetallic Compound at High Temperature" Material Science Research International. 3. 37-43 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] 堤 三佳: "一方向凝固超合金Mar-M247の高温クリープ疲労と室温疲労の相違" 日本材料学会第46期学術講演会講演論文集. 213-214 (1997)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] M.Tsutsumi: ""Microcracking Behavior and Life Law of Fatigue in a Cast TiAl Intermetallic Compound at High Temperature"" Material Science Research International, The Society of Materials Science, Japan. Vol.3. 37-43 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] M.Tsutsumi: ""Difference between Creep-Fatigue and Fatigue at Room Temperature in Uni-directionally Solidified Mar M-247"" Preprint of the 46th JSMS Anual Meeting. 213-214 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1997 Final Research Report Summary
  • [Publications] M.Tsutsumi: "Microracking Behavior and Life Law of Fatigue in a Cast TiAl Intermetallic Compound at High Temperature" Material Science Research International. 3. 37-43 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] 堤三佳: "一方向凝固超合金Mar-M247の高温クリープ疲労と室温疲労の相違" 日本材料学会第46期学術講演会講演論文集. 213-214 (1997)

    • Related Report
      1997 Annual Research Report
  • [Publications] R.Ohtani: "Room and high temperature low cycle fatigue in cast TiAl" Proceedingsof Asian Pacific Conference for FRACTURE and STRENGTH'96. 271-276 (1996)

    • Related Report
      1996 Annual Research Report
  • [Publications] R.Ohtani: "Fatigue crack propagation in a cast TiAl intermetallic compound at high temperature" Intermetallics. 4・1. 77-83 (1996)

    • Related Report
      1996 Annual Research Report

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Published: 1996-04-01   Modified: 2016-04-21  

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