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Title: Precursor evolution and SCC initiation of cold-worked alloy 690 in simulated PWR primary water

Abstract

Stress corrosion crack initiation of two thermally-treated, cold-worked (CW) alloy 690 materials was investigated in 360oC simulated PWR primary water using constant load tensile (CLT) tests and blunt notch compact tension (BNCT) tests equipped with direct current potential drop (DCPD) for in-situ detection of cracking. SCC initiation was not detected by DCPD for the 21% and 31%CW CLT specimens loaded at their yield stress after ~9,220 h, however intergranular (IG) precursor damage and isolated surface cracks were observed on the specimens. The two 31%CW BNCT specimens loaded at moderate stress intensity after several cyclic loading ramps showed DCPD-indicated crack initiation after 10,400h exposure at constant stress intensity, which resulted from significant growth of IG cracks. The 21%CW BNCT specimens only exhibited isolated small IG surface cracks and showed no apparent DCPD change throughout the test. Interestingly, post-test cross-section examinations revealed many grain boundary (GB) nano-cavities in the bulk of all the CLT and BNCT specimens particularly for the 31%CW materials. Cavities were also found along GBs extending to the surface suggesting an important role in crack nucleation. This paper provides an overview of the evolution of GB cavities and will discuss their effects on crack initiation in CW alloy 690.

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1358515
Report Number(s):
PNNL-SA-121146
Journal ID: ISSN 0010--9312; 49159; 830403000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: CORROSION 2017, March 29-30, 2017, New Orleans, Louisiana, Paper No. NACE-2017-9475
Country of Publication:
United States
Language:
English
Subject:
intergranular stress corrosion cracking; crack initiation; alloy 690; cold work; creep cavities; Environmental Molecular Sciences Laboratory

Citation Formats

Zhai, Ziqing, Kruska, Karen, Toloczko, Mychailo B., and Bruemmer, Stephen M. Precursor evolution and SCC initiation of cold-worked alloy 690 in simulated PWR primary water. United States: N. p., 2017. Web. doi:10.5006/2470.
Zhai, Ziqing, Kruska, Karen, Toloczko, Mychailo B., & Bruemmer, Stephen M. Precursor evolution and SCC initiation of cold-worked alloy 690 in simulated PWR primary water. United States. doi:10.5006/2470.
Zhai, Ziqing, Kruska, Karen, Toloczko, Mychailo B., and Bruemmer, Stephen M. Mon . "Precursor evolution and SCC initiation of cold-worked alloy 690 in simulated PWR primary water". United States. doi:10.5006/2470.
@article{osti_1358515,
title = {Precursor evolution and SCC initiation of cold-worked alloy 690 in simulated PWR primary water},
author = {Zhai, Ziqing and Kruska, Karen and Toloczko, Mychailo B. and Bruemmer, Stephen M.},
abstractNote = {Stress corrosion crack initiation of two thermally-treated, cold-worked (CW) alloy 690 materials was investigated in 360oC simulated PWR primary water using constant load tensile (CLT) tests and blunt notch compact tension (BNCT) tests equipped with direct current potential drop (DCPD) for in-situ detection of cracking. SCC initiation was not detected by DCPD for the 21% and 31%CW CLT specimens loaded at their yield stress after ~9,220 h, however intergranular (IG) precursor damage and isolated surface cracks were observed on the specimens. The two 31%CW BNCT specimens loaded at moderate stress intensity after several cyclic loading ramps showed DCPD-indicated crack initiation after 10,400h exposure at constant stress intensity, which resulted from significant growth of IG cracks. The 21%CW BNCT specimens only exhibited isolated small IG surface cracks and showed no apparent DCPD change throughout the test. Interestingly, post-test cross-section examinations revealed many grain boundary (GB) nano-cavities in the bulk of all the CLT and BNCT specimens particularly for the 31%CW materials. Cavities were also found along GBs extending to the surface suggesting an important role in crack nucleation. This paper provides an overview of the evolution of GB cavities and will discuss their effects on crack initiation in CW alloy 690.},
doi = {10.5006/2470},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Mar 27 00:00:00 EDT 2017},
month = {Mon Mar 27 00:00:00 EDT 2017}
}

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