Disappearance of martensitic strengthened-micro-texture in modified 9Cr-1Mo steel caused by stress-induced acceleration of atomic diffusion at elevated temperatures

Taichi Shinozaki, Ken Suzuki, Hideo Miura

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Modified 9Cr-1Mo steel is a heat-resistant steel developed for a steam generator in FBR (Fast Breeder Reactor) and it has been applied to various thermal power plants. Recently, it was found that the fatigue limit of this steel did not appear up to 108 cycles at temperatures higher than 500ºC. The reason for the disappearance of the fatigue limit was attributed to the change of the initially designed microstructure of the alloy. The initially dispersed fine lath martensitic texture disappeared at temperatures higher than 500oC, when the amplitude of the applied stress exceeded a certain critical value. In order to explicate the dominant factors of this change quantitatively, the change of the microstructure and the strength of the alloy were continuously observed by applying an intermittent fatigue and creep tests at elevated temperatures and EBSD analysis. It was found that there was a critical stress which caused the microstructure change at each test temperature higher than 500oC, and the activation energy of the change was determined as a function of temperature and the applied tensile stress. The dominant factor of the micro structure change was the stress-induced acceleration of the atomic diffusion of the component element of the alloy.

Original languageEnglish
Title of host publicationAdvances in Fracture and Damage Mechanics XVII
EditorsLuis Rodriguez-Tembleque, Jaime Dominguez, Ferri M.H. Aliabadi
PublisherTrans Tech Publications Ltd
Pages31-35
Number of pages5
ISBN (Print)9783035713503
DOIs
Publication statusPublished - 2018 Jan 1
Event17th International Conference on Fracture and Damage Mechanics, FDM 2018 - Bangkok, Thailand
Duration: 2018 Sep 42018 Sep 6

Publication series

NameKey Engineering Materials
Volume774 KEM
ISSN (Print)1013-9826
ISSN (Electronic)1662-9795

Other

Other17th International Conference on Fracture and Damage Mechanics, FDM 2018
CountryThailand
CityBangkok
Period18/9/418/9/6

Keywords

  • Cr-Mo steel
  • Creep-fatigue damage
  • Diffusion
  • EBSD analysis
  • Micro texture
  • Stress

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

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  • Cite this

    Shinozaki, T., Suzuki, K., & Miura, H. (2018). Disappearance of martensitic strengthened-micro-texture in modified 9Cr-1Mo steel caused by stress-induced acceleration of atomic diffusion at elevated temperatures. In L. Rodriguez-Tembleque, J. Dominguez, & F. M. H. Aliabadi (Eds.), Advances in Fracture and Damage Mechanics XVII (pp. 31-35). (Key Engineering Materials; Vol. 774 KEM). Trans Tech Publications Ltd. https://doi.org/10.4028/www.scientific.net/KEM.774.31