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2000 Fiscal Year Final Research Report Summary

Development of Nondestructive Assessment Methodology for Residual Life of Martensitic Heat Resistant Steel

Research Project

Project/Area Number 10555225
Research Category

Grant-in-Aid for Scientific Research (B).

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 Engineering, Professor, 大学院・工学研究科, 教授 (90108465)

Co-Investigator(Kenkyū-buntansha) NONAKA Osamu  IHI Co., Ltd., Research Institute, Section Chief, 技術研究所・材料研究部・材料評価グループ, 材料評価グループ課長(研究職)
KOIKE Jun-ichi  Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (10261588)
Project Period (FY) 1998 – 2000
KeywordsStructure Materials for High Temperature Use / High Cr Heat Resistant Steel / High Temperature Creep / Martensitic Lath Structure / Recovery of Lath Structure / Nondestructive Residual Life Evaluation / Hardness
Research Abstract

High Cr ferritic heat resistant steel is widely applied to the thick section components of power plants to be used in creep regime. In this research, nondestructive residual life assessment of such high Cr steel with tempered martensitic lath structure was examined, and the results are summarized as follows :
1.There are four factors that may control creep deformation and fracture of the high Cr ferritic heat resistant steels. They are dislocation(lath)structure, precipitates on grain- and sub-boundaries, fine particles within subgrains, and solute atoms such as W and Mo.Among these factors, the lath structure in the most important obstacle that determines yield stress of the steel. Its recovery is closely related to the progress of creep deformation and the subsequent failure. Therefore, this recovery of lath structure should be taken as the measure of life assessment.
2.As a result of the recovery of martensitic lath structure, lath width increases with increasing creep strain. The relative increase in lath width Δλ/Δλ^* is linearly related to creep strain. Δλ is the change in lath width from the original value, and Δλ^* is the value of Δλ at rupture. The coefficient of linear relation does not change with creep condition or alloy composition.
3.Based on the linear relation between lath width and creep strain, we can evaluate creep strain of a component of engineering plants. Creep curve under any creep condition can readily predict with the aid of creep database. Residual life can be assessed from the estimated creep strain and the creep curve predicated.
4.The residual life assessment based on the measurement of lath width is applicable to rotor steel tempered at low temperature. However, in boiler steel(such as HCM12A)tempered at higher temperature, brittle fracture takes place by the coalescence of grain boundary cavities. Life assessment based on cavity growth should be employed in this case.

  • Research Products

    (14 results)

All Other

All Publications (14 results)

  • [Publications] 澤田浩太: "改良9Cr-1Mo鋼のマルテンサイト組織変化によるクリープ余寿命評価"鉄と鋼. 84・8. 580-585 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Sawada: "Dislocation Substructure Degradation during Creep of Martensitic Heat-resisting Steels with and without W"Materials for Advanced Power Engineering 1998. 575-583 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Sawada: "Effect of W on Recovery of Lath Structure during Creep of High Martensitic Steels"Materials Science and Engineering, A. 267. 19-25 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Sawada: "Creep life Assessment of high Chromium Ferritic Steels by Recovery of Martensitic Lath Structure"Key Engineering Materials. 171・174. 109-114 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 佐藤誠: "W含有高Crフェライト系耐熱鋼のクリープ挙動とサブグレイン組織安定性の相関"日本金属学会誌. 64・5. 371-374 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Maruyama: "Strengthening Mechanisms of Creep Resistant Tempered Martensitic Steel"ISIJ International. 41・6(印刷中). (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 丸山公一: "金属便覧(5.4.2クリープ変形,5.4.3クリープ破壊)"丸善. 348-358 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Sawada: "Residual Creep Life Assessment by Change of Martensitic Lath Structural in Modified 9Cr-1Mo Steels"Journal of Iron & Steel Inst.Japan. vol.84, No.8. 580-585 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Sawada: "Dislocation Substructure Degradation during Creep of Martensitic Heat-resisting Steels with and without W"Materials for Advanced Power Engineering 1998. vol.1. 575-583 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Sawada: "Effect of W on Recovery of Lath Structure during Creep of High Chromium Martensitic Steels"Materials Science and Engineering. vol.A267. 19-25 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Sawada: "Creep life Assessment of high Chromium Ferritic Steels by Recovery of Martensitic Lath Structure"Key Engineering Materials. vol.171-174. 109-114 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] M.Sato: "Correlation between Creep Strength and Stability of Subgrain Structure in High Chromium Heat Resistant Steel with Tungsten"Journal of Japan Institute of Metals. vol.64, No.5. 371-374 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Maruyama: "Strengthening Mechanisms of Creep Resistant Tempered Martensitic Steel"ISIJ International. vol.41, No.6(In press). (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K.Maruyama: "Metallurgical Hnndbook : 5.4.2 Creep Deformation, 5.4.3 Creep Fracture"Maruzen. 348-358 (2000)

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

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Published: 2002-03-26  

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