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Title: Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models

Abstract

The Ford/Andresen slip dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material condition. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxidemore » which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Knolls Atomic Power Lab. (KAPL), Niskayuna, NY (United States)
Sponsoring Org.:
USDOE Assistant Secretary for Nuclear Energy, Washington, DC (United States)
OSTI Identifier:
353195
Report Number(s):
KAPL-P-000005; CONF-9505318-; CONF-9504307-; K-95040
ON: DE99002812; TRN: AHC29923%%26
DOE Contract Number:  
AC12-76SN00052
Resource Type:
Technical Report
Resource Relation:
Conference: IAEA specialists meeting on cracking in LWR RPV head penetrations, Philadelphia, PA (United States); Palo Alto, CA (United States), 2-4 May 1995; 27-28 Apr 1995; Other Information: PBD: 22 Feb 1995
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 21 NUCLEAR POWER REACTORS AND ASSOCIATED PLANTS; INCONEL 600; NICKEL BASE ALLOYS; STRESS CORROSION; CRACK PROPAGATION; MATHEMATICAL MODELS; BWR TYPE REACTORS; CHROMIUM ALLOYS; IRON ALLOYS; TITANIUM ALLOYS; THEORETICAL DATA

Citation Formats

Thompson, C D, Krasodomski, H T, Lewis, N, and Makar, G L. Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models. United States: N. p., 1995. Web. doi:10.2172/353195.
Thompson, C D, Krasodomski, H T, Lewis, N, & Makar, G L. Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models. United States. https://doi.org/10.2172/353195
Thompson, C D, Krasodomski, H T, Lewis, N, and Makar, G L. 1995. "Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models". United States. https://doi.org/10.2172/353195. https://www.osti.gov/servlets/purl/353195.
@article{osti_353195,
title = {Prediction of pure water stress corrosion cracking (PWSCC) in nickel base alloys using crack growth rate models},
author = {Thompson, C D and Krasodomski, H T and Lewis, N and Makar, G L},
abstractNote = {The Ford/Andresen slip dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material condition. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxide which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.},
doi = {10.2172/353195},
url = {https://www.osti.gov/biblio/353195}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Feb 22 00:00:00 EST 1995},
month = {Wed Feb 22 00:00:00 EST 1995}
}