Corrosion fatigue crack growth behavior of oil-grade nickel-base alloy 718. Part 2: Effect of aging treatment

•Aging treatments increase the grain size of oil-grade alloy 718.•Two-step aged sample shows much finer γ″ precipitates than that of one-step ones.•Aging treatment leads to lower corrosion fatigue crack growth rates (CFGR).•No visible difference of CFGR between one-step aged and two-step aged alloys...

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Bibliographic Details
Published in:Corrosion science 2015-09, Vol.98 (C), p.280-290
Main Authors: Chen, Ting, Nutter, Jared, Bai, Jingsheng, Hawk, Jeffrey, Liu, Xingbo
Format: Article
Language:English
Subjects:
A. Superalloys
B. Polarization
B. SEM
B. TEM
C. Corrosion fatigue
C. Pitting corrosion
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Summary:•Aging treatments increase the grain size of oil-grade alloy 718.•Two-step aged sample shows much finer γ″ precipitates than that of one-step ones.•Aging treatment leads to lower corrosion fatigue crack growth rates (CFGR).•No visible difference of CFGR between one-step aged and two-step aged alloys. The influence of aging treatment on microstructure and corrosion fatigue crack growth (CFCG) behavior of oil-grade nickel-base alloy 718 is investigated. The average grain size of alloy 718 increases after aging treatment. Isolated platelet δ phases are precipitated at some of the grain boundaries in aged specimens. The one-step aged specimen shows a uniform distribution of fine spherical γ′ and elongated γ″ precipitates. However, the two-step aged sample shows much finer γ″ precipitates. Aging treatment leads to lower CFCG rates of alloy 718. Nevertheless, no visible difference of CFCG rates is observed between one-step aged and two-step aged specimens.
ISSN:0010-938X
1879-0496
DOI:10.1016/j.corsci.2015.05.033