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1997 Fiscal Year Final Research Report Summary

Development of Alloy Design and Evaluation Systems for High Temperature Materials Based on Non-Steady-State Creep Concept

Research Project

Project/Area Number 07555653
Research Category

Grant-in-Aid for Scientific Research (A)

Allocation TypeSingle-year Grants
Section展開研究
Research Field Structural/Functional materials
Research InstitutionTOHOKU UNIVERSITY

Principal Investigator

MARUYAMA Kouichi  Tohoku University, Graduate School of Engireering, Professor, 大学院・工学研究科, 教授 (90108465)

Co-Investigator(Kenkyū-buntansha) SUZUKI Mayumi  Tohoku University, Graduate School of Engineering, Research Associate, 大学院・工学研究科, 助手 (20292245)
ONO Noboru  Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (40111249)
MASUYAMA Fujimitsu  Mitsubishi Heavy Industries Ltd., Nagasaki R&D Center, Maneger, 長崎研究所, 主査(研究職)
YAGI Koichi  National Research Institute for Metals, Environment Performance Devision, Divisi, 環境性能研究部, 部長(研究職)
Project Period (FY) 1995 – 1997
KeywordsStructural Materials / High Temperature Creep / Long Term Properties / Alloy Design / Constitutive Creep Equation / Creep Defects / Materials Database / Deformation Mechanism
Research Abstract

Long term creep properties of high temperature materials are evaluated from short term creep tests. The objective of the present research is to improve ways of formulation of short term creep data and evaluation of long term properties. The results are summarized as follows :
1.Improvement of rupture life prediction : The following creep equation was proposed based on OMEGA method :
epsilon=(1/OMEGA){In(1+zetat)-In(1-etat)} (1)
where epsilon is the creep strain, t is the time, and OMEGA, zeta and eta are material constants. This equation can predict more accurate rupture life from shorter creep tests.
2.Relevant condition of short term tests : Short term test conditions are selected based on deformation mechanism maps so that creep mechanism does not change from service condition of engineering plant. Long term creep data of 2.25Cr-lMo steel was analyzed to clarify how to select the test conditions. It was found that deformation mechanism maps presently available have several misunderstandings. A correct mechanism map of the steel was proposed.
3.Examination of prediction methodology : Several methods proposed for rupture life prediction were examined by long term creep date over 10^5h. More relevant methods were suggested among the proposed methods. Another finding to be mentioned is the concept of inherent creep strength. Namely, all the low alloy steels gives similar creep rupture strength when test duration is long enough.
4.Correlation between microstructural degradation and creep life consumption : Degradation of martensitic lath structure was studied in detail during creep of martensitic steels. A linear relation was found between relative growth of lath width and creep strain. A nondestructive life assessment method was proposed based on the linear relation.
5.Modification of database system : An object-oriented database system was modified to the form applicable to creep data.

  • Research Products

    (14 results)

All Other

All Publications (14 results)

  • [Publications] 木村 一弘: "炭素鋼の複雑なクリープ変形挙動に及ぼす高温時効の影響と基底クリープ強度" 鉄と鋼. 82・8. 713-718 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 増山 不二光: "火力発電プラントにおけるクリープ損傷の評価・診断" 非破壊検査. 46・3. 163-171 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Maruyama: "Improvement of Omega for Creep Life Prediction" ISIJ International. 37・4. 419-423 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] N.Ono: "An Experiment on Internet Material Database Service with MOOD-SX" ASTM.-STP. 1311. 63-74 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Maruyama: "Examination of Deformation Mechanism Maps in 2.25Cr-lMo Steel by Creep Tests at Strain Rates of 10^<11>s^1TO 10^6s^1" Mater.Sci.Eng. A224. 166-172 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 澤田 浩太: "改良9Cr-lMo鋼のクリープ変形中の組織変化と寿命評価" 鉄と鋼. 83・7. 466-471 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 丸山 公一: "高温強度の材料科学・クリープ理論と実用材料への適用" 内田老鶴圃, 329 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Kimura: ""Effect of Thermal Aging on the Complex Creep Deformation Behavior of Carbon Steel and Its Inherent Creep Strength"" J.Iron Steel Inst.Japan. vol.82, No.8. 713-718 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] F.Masuyama: ""Assessment and Diagnosis of Creep Damage in Thermal Power Plants"" Nondestructive Testing. vol.46, No.3. 163-171 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Maruyama: ""Improvement of Omega Method for Creep Life Prediction"" ISIJ International. vol.37, No.4. 419-423 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] N.Ono: ""An Experiment on Internet Material Database Service with MOOD-SX"" Computerization and Networking of Materials Databases, ASTM-STP. vol.1311. 63-74 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Maruyama: ""Examination of Deformation Mechanism Maps in 2.25Cr-lMo Steel by Creep Tests at strain Rates of 10^<-11> to 10^<-6>s^<-1>"" Mater.Sci.Eng.vol.A224. 166-172 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Sawada: ""Microstructural Changes during Creep and Life Assessment of Mod.9Cr-1Mo Steel"" J.Iron Steel Inst.Japan. vol.83, No.7. 466-471 (1997)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Maruyama: ""Materials Science of High Temperature Strength-Creep Theories and its Practical Applications"" Uchida Rokakuho. 329 (1997)

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

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Published: 1999-03-16  

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