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Title: Long-term-aging embrittlement of cast duplex stainless steels: Mechanism and kinetics

Abstract

Microstructural characteristics of long-term-aged cast duplex stainless steel specimens including one from a BWR, have been investigated by SEM, TEM, SANS, and APFIM techniques. Three precipitate phases, Cr-rich ..cap alpha..' and the Ni- and Si-rich G phase, and ..gamma../sub 2/ austenite, have been identified in the ferrite matrix of the aged specimens. For CF-8 grade materials, M/sub 23/C/sub 6/ carbides were identified on the austenite-ferrite boundaries as well as in the ferrite matrix for aging at greater than or equal to450/sup 0/C. The Si, C, and Mo contents influenced the kinetics of the G-phase precipitation. However, TEM, and APFIM analyses indicate that the embrittlement during aging at less than or equal to400/sup 0/C is primarily associated with Fe and Cr segregation in ferrite by spinodal decomposition. For extended aging, e.g., 6-8 y at 350-400/sup 0/C, large platelike ..cap alpha..' formed by nucleation and growth from the structure produced by the spinodal decomposition. The Cr content appears to either promote the platelike ..cap alpha..' (high Cr content) or to suppress the ..cap alpha..' in favor of ..gamma../sub 2/ precipitation (low Cr). 21 refs., 10 figs., 2 tabs.

Authors:
;
Publication Date:
Research Org.:
Argonne National Lab., IL (USA)
OSTI Identifier:
5682948
Report Number(s):
CONF-871232-1
ON: DE88002929
DOE Contract Number:  
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: Symposium on properties of stainless steels in elevated temperature service, Boston, MA, USA, 13 Dec 1987; Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; STAINLESS STEELS; AGE HARDENING; EMBRITTLEMENT; MICROSTRUCTURE; AUSTENITE; BWR TYPE REACTORS; CARBIDES; CARBON; CHROMIUM; FERRITE; HEAT TREATMENTS; IRON; MOLYBDENUM; NICKEL; PHASE TRANSFORMATIONS; REACTION KINETICS; SEGREGATION; SILICON; STRESS CORROSION; ALLOYS; CARBON ADDITIONS; CARBON COMPOUNDS; CHEMICAL REACTIONS; CHROMIUM ALLOYS; CORROSION; CORROSION RESISTANT ALLOYS; CRYSTAL STRUCTURE; ELEMENTS; HARDENING; IRON ALLOYS; IRON BASE ALLOYS; KINETICS; METALS; NONMETALS; REACTORS; SEMIMETALS; STEELS; TRANSITION ELEMENTS; WATER COOLED REACTORS; WATER MODERATED REACTORS; 360103* - Metals & Alloys- Mechanical Properties; 360102 - Metals & Alloys- Structure & Phase Studies; 210100 - Power Reactors, Nonbreeding, Light-Water Moderated, Boiling Water Cooled

Citation Formats

Chung, H M, and Chopra, O K. Long-term-aging embrittlement of cast duplex stainless steels: Mechanism and kinetics. United States: N. p., 1987. Web.
Chung, H M, & Chopra, O K. Long-term-aging embrittlement of cast duplex stainless steels: Mechanism and kinetics. United States.
Chung, H M, and Chopra, O K. 1987. "Long-term-aging embrittlement of cast duplex stainless steels: Mechanism and kinetics". United States.
@article{osti_5682948,
title = {Long-term-aging embrittlement of cast duplex stainless steels: Mechanism and kinetics},
author = {Chung, H M and Chopra, O K},
abstractNote = {Microstructural characteristics of long-term-aged cast duplex stainless steel specimens including one from a BWR, have been investigated by SEM, TEM, SANS, and APFIM techniques. Three precipitate phases, Cr-rich ..cap alpha..' and the Ni- and Si-rich G phase, and ..gamma../sub 2/ austenite, have been identified in the ferrite matrix of the aged specimens. For CF-8 grade materials, M/sub 23/C/sub 6/ carbides were identified on the austenite-ferrite boundaries as well as in the ferrite matrix for aging at greater than or equal to450/sup 0/C. The Si, C, and Mo contents influenced the kinetics of the G-phase precipitation. However, TEM, and APFIM analyses indicate that the embrittlement during aging at less than or equal to400/sup 0/C is primarily associated with Fe and Cr segregation in ferrite by spinodal decomposition. For extended aging, e.g., 6-8 y at 350-400/sup 0/C, large platelike ..cap alpha..' formed by nucleation and growth from the structure produced by the spinodal decomposition. The Cr content appears to either promote the platelike ..cap alpha..' (high Cr content) or to suppress the ..cap alpha..' in favor of ..gamma../sub 2/ precipitation (low Cr). 21 refs., 10 figs., 2 tabs.},
doi = {},
url = {https://www.osti.gov/biblio/5682948}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jul 01 00:00:00 EDT 1987},
month = {Wed Jul 01 00:00:00 EDT 1987}
}

Conference:
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