2024 IMS Henry Clifton Sorby Lecture: Luiz Henrique de Almeida, Federal University of Rio de Janeiro, Brazil
2024 IMS Henry Clifton Sorby Lecture
Luiz Henrique de Almeida
Federal University of Rio de Janeiro, Brazil
“HP GRADE HEAT RESISTANT AUSTENITIC STAINLESS STEELS: 30 years of microstructural evolution and significant performance increase for hydrogen production in steam reforming furnaces.”
Since the 1990s, when HP-grade heat-resistant austenitic stainless steels began to be extensively used in the petrochemical industry, their in-service performance has increased significantly due to improvements in composition and microstructure design. For example, steam reforming furnaces for large-scale hydrogen production can now operate with larger loads at higher temperatures, circa 1000oC, without compromising the design criteria of a 100,000h service life. Currently, under these conditions, service times close to 200,000h are not uncommon. The effect of Nb, Ti and Y additions, the fragmentation of the interdendritic primary carbide network and the transformation of NbC to G-phase (Ni16Nb6Si7) during aging will be addressed. The effect of short time in-service overheating, promoting in situ G-phase dissolution and subsequent precipitation of small fragmented NbC particles upon cooling, will be characterized. Practical consequences of these transformations are discussed based on the study of HP tubes decommissioned after 40,000 to 143,000h of operation.