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Publication

A comprehensive study of the effects of long-term thermal aging on the fracture resistance of cast austenitic stainless steel...

by David A Collins, Emily Carter, Timothy G Lach, Thak Sang Byun
Publication Type
Journal
Journal Name
Nuclear Engineering and Technology
Publication Date
Page Numbers
709 to 731
Volume
54
Issue
2

Loss of fracture resistance due to thermal aging degradation is a potential limiting factor affecting the long-term (80+ year) viability of nuclear reactors. To evaluate the effects of decades of aging in a practical time frame, accelerated aging must be employed prior to mechanical characterization. In this study, a variety of chemically and microstructurally diverse austenitic stainless steels were aged between 0 and 30,000 h at 290–400 °C to simulate 0–80+ years of operation. Over 600 static fracture tests were carried out between room temperature and 400 °C. The results presented include selected J-R curves of each material as well as K0.2mm fracture toughness values mapped against aging condition and ferrite content in order to display any trends related to those variables. Results regarding differences in processing, optimal ferrite content under light aging, and the relationship between test temperature and Mo content were observed. Overall, it was found that both the ferrite volume fraction and molybdenum content had significant effects on thermal degradation susceptibility. It was determined that materials with >25 vol% ferrite are unlikely to be viable for 80 years, particularly if they have high Mo contents (>2 wt%), while materials less than 15 vol% ferrite are viable regardless of Mo content.