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Title: Microstructure and stress corrosion resistance of alloys X-750, 718, and A-286 in LWR environments: Final report

Technical Report ·
OSTI ID:6054269

The results of microstructural characterization and stress corrosion cracking test are presented for several heat treatment conditions of age-hardenable alloys X-750, 718, and A-286 used for in-core components in light-water reactors. Resistance to intergranular stress corrosion cracking was evaluated using slow-strain-rate tests in pressurized-water-reactor primary water, and microstructural etch and rising-load quality assurance tests. Detailed microstructural characterization of these alloys was performed, and stress corrosion cracking susceptibility is related to microstructural features. Alloy X-750 microstructures with heavy grain boundary coverage by Cr/sub 23/C/sub 6/ show better resistance to stress corrosion cracking in primary water, despite grain boundary chromium depletion. Alloys 718 and A-286 have good resistance to cracking in the slow-strain-rate and quality assurance tests, although neither is immune to cracking in reactor service. Results are compared with those of a related program, including crack initiation and crack growth tests in pressurized-water and boiling-water reactor environments. Recommendations are made for improvements in the quality assurance tests and in heat treatment for alloy 718. 29 refs., 15 figs., 9 tabs.

Research Organization:
Electric Power Research Inst., Palo Alto, CA (USA); Babcock and Wilcox Co., Alliance, OH (USA). Research Center
OSTI ID:
6054269
Report Number(s):
EPRI-NP-6392-M
Country of Publication:
United States
Language:
English