Mechanical and Corrosion Response of 316SS in Supercritical CO₂

Journal Article · Fri May 14 00:00:00 EDT 2021 · Oxidation of Metals

DOI:https://doi.org/10.1007/s11085-021-10026-x· OSTI ID:1787519

Brittan, Andrew ^[1]; Mahaffey, Jacob Thomas ^[2]; Adam, David ^[3]; Anderson, Mark ^[3]

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1. Univ. of Wisconsin-Madison, WI (United States); Kairos Power, Alameda, CA (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. Univ. of Wisconsin-Madison, WI (United States)

The supercritical carbon dioxide (s-CO₂) Brayton cycle is currently being explored as a replacement for the steam Rankine cycle due to its potential for higher efficiency and lower cycle cost. 316 stainless steel is a candidate alloy for use in s-CO₂ up to roughly 600 °C, but the mechanical effects of prolonged exposure of base and welded material in s-CO₂ have not been analyzed. The potential for carburization makes this an important concern for the implementation of 316 and similar austenitic stainless steels in the s-CO₂ environment. In this study, welded and base material of two types of 316–316L and 316H–were exposed in either s-CO₂ or argon at 550 °C or 750 °C for 1000 h. 550 °C s-CO₂ exposure yielded a thin (< 1 µm) Cr oxide with occasional nodules of duplex Fe oxide and Fe–Cr spinel that were up to 5 microns thick. However, tensile results from s-CO_–2 exposure matched those of 550 °C thermal aging in Ar, indicating that no mechanically detrimental carburization occurred in either 316 variant after 1000 h exposure. Conversely, 750 °C s-CO₂ exposure produced roughly 10 × the oxide thickness, with a more substantial Fe oxide (3–5 µm) on the majority of the surface and nodules of up to 40 µm thick. In comparison to aged samples, tensile testing of 750 °C CO₂-exposed samples revealed ductility loss attributed to carburization. As a result, projections of 316L performance in s-CO₂ indicate that mechanically detrimental carburization—equal to that shown here for 750 °C, 1000 h—will likely be present after 7–14 years of service at 550 °C.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000; NA0003525
• OSTI ID: 1787519
• Report Number(s): SAND-2021-3789J; 695180
• Journal Information: Oxidation of Metals, Vol. 95, Issue 5-6; ISSN 0030-770X
• Publisher: Springer
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
316 stainless steel
Supercritical carbon dioxide
Mechanical properties
Oxidation
Carburization