Abbasi, Majid Park, Ihho Ro, Yunjo Ji, Youngsu Ayer, Raghavan Shim, Jae-Hyeok 2024-01-19T21:00:58Z 2024-01-19T21:00:58Z 2021-09-02 2019-02 1044-5803 https://pubs.kist.re.kr/handle/201004/120400 HP50M heat-resistant cast austenitic steel tubes are exposed to high temperatures (i.e. 900 degrees C) for long periods (10 years or longer) in petrochemical reforming plants. Twenty-years aged tubes exhibit microstructural changes such as primary carbide transformation and growth, MC carbide transition to G-phase, and fine secondary M23C6 precipitation. Analytical electron microscopy reveals that silicon tends to segregate at austenite inter-dendritic boundaries in fresh as-cast tubes. Thermo-kinetic simulation of long-term precipitate evolution of the steel is carried out together with Si segregation compositions. The experimentally observed general trend that G-phase forms at the expense of MC carbide is successfully predicted for the Si segregation compositions after a few thousand hours of aging in a temperature range between 700 and 900 degrees C. This study demonstrates that the Si segregation plays a crucial role in the formation of G-phase in this type of heat-resistant cast steels. Additional heat-treatment experiment confirms that G-phase becomes unstable above 900 degrees C and the reverse transition to MC occurs. English ELSEVIER SCIENCE INC MULTICOMPONENT MULTIPHASE SYSTEMS REMAINING LIFE ASSESSMENT CENTRIFUGALLY CAST PRECIPITATE EVOLUTION NUMERICAL-SIMULATION STAINLESS-STEELS MICROSTRUCTURE KINETICS CARBIDE NB G-phase formation in twenty-years aged heat-resistant cast austenitic steel reformer tube Article 10.1016/j.matchar.2019.01.003 1 MATERIALS CHARACTERIZATION, v.148, pp.297 - 306 MATERIALS CHARACTERIZATION 148 297 306 scie scopus 000458228100034 2-s2.0-85059628370 Materials Science, Multidisciplinary Metallurgy & Metallurgical Engineering Materials Science, Characterization & Testing Materials Science Metallurgy & Metallurgical Engineering Article MULTICOMPONENT MULTIPHASE SYSTEMS REMAINING LIFE ASSESSMENT CENTRIFUGALLY CAST PRECIPITATE EVOLUTION NUMERICAL-SIMULATION STAINLESS-STEELS MICROSTRUCTURE KINETICS CARBIDE NB Heat-resistant austenitic steel Reformer tube Precipitate G-phase Kinetic simulation