Development of Creep-Resistant and Oxidation-Resistant Austenitic Stainless Steels for High Temperature Applications

Austenitic stainless steels are cost-effective materials for high-temperature applications if they have the oxidation and creep resistance to withstand prolonged exposure at such conditions. Since 1990, Oak Ridge National Laboratory (ORNL) has developed advanced austenitic stainless steels with creep resistance comparable to Ni-based superalloy 617 at 800–900°C based on specially designed “engineered microstructures” utilizing a microstructure/composition database derived from about 20 years of radiation effect data on steels. The wrought high temperature-ultrafine precipitate strengthened (HT-UPS) steels with outstanding creep resistance at 700–800°C were developed for supercritical boiler and superheater tubing for fossil power plants in the early 1990s, the cast CF8C-Plus steels were developed in 1999–2001 for land-based gas turbine casing and diesel engine exhaust manifold and turbocharger applications at 700–900°C, and, in 2015–2017, new Al-modified cast stainless steels with oxidation and creep resistance capabilities up to 950–1000°C were developed for automotive exhaust manifold and turbocharger applications. This article reviews and summarizes their development and their properties and applications.