Evaluation of Tensile Property of Austenitic Alloys Exposed to High-Temperature S-CO 2 Environment

Super-critical CO2 (S-CO2) Brayton cycle has been considered to replace the current steam Rankine cycle in Sodium-cooled Fast Reactor (SFR) in order to improve the inherent safety and thermal efficiency. Several austenitic alloys are considered as the structural materials for high temperature S-CO2 environment.. Microstructural change after long-term exposure to high temperature S-CO2 environment could affect to the mechanical properties. In this study, candidate materials (austenitic stainless steels and Alloy 800HT) were exposed to S-CO2 to assess oxidation resistance and the change in tensile properties. Loss of ductility was observed for some austenitic stainless steels even after 250 h exposure. The contribution of S-CO2 environment on such changes was analyzed based on the characterization of the surface oxide and carburization of the materials in which 316H and 800H showed different oxidation behaviors. § 이 논문은 2014 년도 대한기계학회 재료 및 파괴부문 춘계 학술대회(2014. 4. 3.-4., 서귀포KAL호텔) 발표논문임 † Corresponding Author, chjang@kaist.ac.kr C 2014 The Korean Society of Mechanical Engineers