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

Conference · Wed Jul 01 00:00:00 EDT 1987

OSTI ID:5682948

Chung, H M; Chopra, O K

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.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 5682948
• Report Number(s): CONF-871232-1; ON: DE88002929
• 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

Related Subjects

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