Micromechanism of cyclic plastic deformation of alloy IN 718 at 600 °C

In the present investigation, an attempt was made to understand the cyclic deformation micromechanism of gas turbine alloy Inconel 718 at 600 °C (i) by conducting low cycle fatigue and creep–fatigue interaction tests and (ii) by studying the microstructure evolution in the material during fatigue te...

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Bibliographic Details
Published in:Fatigue & fracture of engineering materials & structures 2016-07, Vol.39 (7), p.877-885
Main Authors: Banerjee, A., Sahu, J. K., Paulose, N., Fernando, C. D., Ghosh, R. N.
Format: Article
Language:English
Subjects:
Alloys
creep-fatigue interaction
Deformation
IN 718
low cycle fatigue
Materials creep
Materials fatigue
microtwinning
Plastics
slip bands
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Summary:In the present investigation, an attempt was made to understand the cyclic deformation micromechanism of gas turbine alloy Inconel 718 at 600 °C (i) by conducting low cycle fatigue and creep–fatigue interaction tests and (ii) by studying the microstructure evolution in the material during fatigue tests through extensive electron microscopy. Bilinear slope was obtained in the Coffin–Manson plot for all low cycle fatigue tests, and it was confirmed through transmission electron microscopic examination that microtwinning was the predominant mode of deformation at low plastic strain values, whereas slip and shearing of γ″ precipitates were the predominant mode of deformation at higher plastic strain values. Fatigue life was adversely affected when hold time was introduced at peak tensile strain during creep–fatigue interaction tests. Formation of stepped interface at microtwin boundaries and coarsening of niobium carbide precipitates were observed to be the major microsturctural changes during creep–fatigue interaction tests.
ISSN:8756-758X
1460-2695
DOI:10.1111/ffe.12406