Aging degradation of cast stainless steels: Effects on mechanical properties
A program is being conducted to investigate the significance of in-service embrittlement of cast duplex stainless steels under light-water operating conditions. Mechanical property data are presented from Charpy-impact, tensile, and J-R curve tests for several heats of cast stainless steel aged up to 10,000 h at 450, 400, 350, 320, and 290/sup 0/C. The results indicate that thermal aging increases the tensile strength and decreases the impact energy, J/sub IC/, and tearing modulus of the steels. Also, the ductile-to-brittle transition curve shifts to higher temperatures. The fracture toughness results are consistent with the Charpy-impact data, i.e., the relative reduction in J/sub IC/ is similar to the relative decrease in impact energy. The ferrite content and concentration of C in the steel have a strong effect on the overall process of low-temperature embrittlement. The low-carbon CF-3 steels are the most resistant and Mo-containing CF-8M steels are most susceptible to embrittlement. Weakening of the ferrite/austenite phase boundaries by carbide precipitates has a significant effect on the kinetics and extent of embrittlement of the high-carbon CF-8 and CF-8M steels, particularly after aging at temperatures greater than or equal to400/sup 0/C. The influence of N content and distribution of ferrite on loss of toughness are discussed. The data also indicate that existing correlations do not accurately represent the embrittlement behavior over the temperature range 280 to 450/sup 0/C, i.e., extrapolation of high-temperature data to reactor temperatures may not be valid for some compositions of cast stainless steel.
- Research Organization:
- Argonne National Lab., IL (USA)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 5808257
- Report Number(s):
- CONF-870839-8; ON: DE88003053; TRN: 88-002659
- Resource Relation:
- Conference: 3. international symposium on environmental degradation of materials in nuclear power systems: water reactors, Traverse City, MI, USA, 30 Aug 1987; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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REACTOR MATERIALS
MATERIALS TESTING
STAINLESS STEELS
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TENSILE PROPERTIES
CARBON
CHARPY TEST
DUCTILE-BRITTLE TRANSITIONS
EXPERIMENTAL DATA
MICROSTRUCTURE
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MECHANICAL PROPERTIES
MECHANICAL TESTS
NONMETALS
NUMERICAL DATA
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360103 - Metals & Alloys- Mechanical Properties