The law of crack growth life under load controlled creep-fatigue conditions for W-added 12% Cr steel

Yoshiko Nagumo, A. Toshimitsu Yokobori, Takahiro Fukuda, Yoshiki Takahashi, Ryuji Sugiura

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

Abstract

W-added 12% Cr ferritic heat resistant steel has been used as a steam turbine rotor material. The turbine rotor material is damaged by high temperature creep and fatigue due to starts and stops and changing load of power generation, which results in crack initiation and growth. In the studies done before, the law of crack growth life under creep-fatigue conditions was characterized and clarified that the characteristics of crack growth life of various load frequencies under different temperatures change from fatigue to creep behavior through an inflection region. The law of crack growth life under creep-fatigue interactive conditions has been reported and evaluated by monotonous linear law. On the other hand, it has been indicated that the characteristics of crack growth life under creep-fatigue condition can be represented mathematically by a three dimensional characteristic curved surface based on non-equilibrium science. In this study, crack growth tests using standardized C(T) specimens of W-added 12% Cr ferritic heat resistant steel were conducted under various conditions of stress holding time, applied stress and temperature. To evaluate the effect of cycle dependent and time dependent mechanisms on crack growth life, a method of separate estimation of cycle dependent mechanism from the time dependent mechanism based on the concept of three dimensional characteristic curved surface based on non-equilibrium science were used. As a result, the effect of load frequency on crack growth life was characterized and the predictive law of crack growth life for W-added 12% Cr ferritic heat resistant steel under creep-fatigue interactive conditions based on the concept of Q with the transition function of crack growth life was estimated.

Original languageEnglish
Title of host publicationMaterials and Fabrication
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791850428
DOIs
Publication statusPublished - 2016 Jan 1
Externally publishedYes
EventASME 2016 Pressure Vessels and Piping Conference, PVP 2016 - Vancouver, Canada
Duration: 2016 Jul 172016 Jul 21

Publication series

NameAmerican Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
Volume6A-2016
ISSN (Print)0277-027X

Other

OtherASME 2016 Pressure Vessels and Piping Conference, PVP 2016
CountryCanada
CityVancouver
Period16/7/1716/7/21

ASJC Scopus subject areas

  • Mechanical Engineering

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  • Cite this

    Nagumo, Y., Toshimitsu Yokobori, A., Fukuda, T., Takahashi, Y., & Sugiura, R. (2016). The law of crack growth life under load controlled creep-fatigue conditions for W-added 12% Cr steel. In Materials and Fabrication (American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP; Vol. 6A-2016). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/PVP2016-63484