Creep Crack Growth of 316H Stainless Steel in a Simulated Advanced Gas-Cooled Reactor Environment
Year: 2026
Type: article
Abstract: This study investigates the role of environmental exposure on creep crack growth in AISI 316H stainless steel, a material widely used in advanced gas-cooled reactors (AGRs). Notched specimens subjected to sustained loading under simulated AGR conditions (CO2 with 1% CO, 500 ppm H2O, 300 ppm CH4, and 100 ppm H2) revealed enhanced intergranular cracking at stress intensity factors above 13 MPa√m, accompanied by grain boundary cavitation and crack branching. To distinguish the individual contributions of creep, oxidation, and carburization, comparative tests were conducted in inert argon and hydrogenated steam environments. The inert atmosphere was used to isolate the mechanical effects of creep alone, while the hydrogenated steam environment allowed oxidation to be studied independently of carbon ingress. Both conditions resulted in significantly reduced crack growth compared to AGR exposure, indicating that carburization plays a critical role in accelerating damage. Electron probe microanalysis suggests elevated carbon concentrations along cavitated grain boundaries, suggesting that carbon segregation contributes to embrittlement and facilitates crack propagation under creep conditions. These findings provide insights into the environmental degradation mechanisms affecting reactor-grade stainless steels. Importantly, the insights gained from this study are directly relevant to high-temperature gas-cooled reactors, where similar alloy-environment interactions may influence long-term structural integrity under service conditions.
Source: CORROSION
DOI: 10.5006/4880
Authors: James Rafferty, Fabio Scenini
Institutions: University of Manchester, Henry Royce Institute
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7147341504
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