Volume 42, Issue 9 pp. 1937-1949
SPECIAL ISSUE CONTRIBUTION

Ratcheting-fatigue behaviour of bainite 2.25Cr1MoV steel with tensile and compressed hold loading at 455°C

Z. Zhao

Z. Zhao

School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 China

School of Mechanical & Automotive Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353 China

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D. Yu

D. Yu

School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 China

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G. Chen

G. Chen

School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 China

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X. Chen

Corresponding Author

X. Chen

School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 China

Correspondence

X. Chen, School of Chemical Engineering and Technology, Tianjin University. Tianjin 300072, China.

Email: [email protected]

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First published: 22 May 2019
Citations: 7

Abstract

The ratcheting behaviour of a bainite 2.25Cr1MoV steel was studied with various hold periods at 455°C. Particular attention was paid to the effect of stress hold on whole-life ratcheting deformation, fatigue life, and failure mechanism. Results indicate that longer peak hold periods stimulate a faster accumulation of ratcheting strain by contribution of creep strain, while double hold at peak and valley stress has an even stronger influence. Creep strains produced in peak and valley hold periods are noticeable and result in higher cyclic strain amplitudes. Dimples and acquired defects are found in failed specimen by microstructure observation, and their number and size increase under creep-fatigue loading. Enlarged cyclic strain amplitude and material deterioration caused by creep lead to fatigue life reduction under creep-fatigue loading. A life prediction model suitable for asymmetric cycling is proposed based on the linear damage summation rule.

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