Abstract
A family of creep-resistant, alumina-forming austenitic (AFA) stainless steel alloys is under development for structural use in fossil energy conversion and combustion system applications. The AFA alloys developed to date exhibit comparable creep-rupture lives to state-of-the-art advanced austenitic alloys, and superior oxidation resistance in the ∼923 K to 1173 K (650 °C to 900 °C) temperature range due to the formation of a protective Al 2O3 scale rather than the Cr2O3 scales that form on conventional stainless steel alloys. This article overviews the alloy design approaches used to obtain high-temperature creep strength in AFA alloys via considerations of phase equilibrium from thermodynamic calculations as well as microstructure characterization. Strengthening precipitates under evaluation include MC-type carbides or intermetallic phases such as NiAl-B2, Fe2(Mo,Nb)-Laves, Ni3Al-L12, etc. in the austenitic single-phase matrix. Creep, tensile, and oxidation properties of the AFA alloys are discussed relative to compositional and microstructural factors.
Original language | English |
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Pages (from-to) | 922-931 |
Number of pages | 10 |
Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
Volume | 42 |
Issue number | 4 |
DOIs | |
State | Published - Apr 2011 |
Funding
The authors thank Drs. S. Dryepondt, R.R. Unocic, and P.F. Tortorelli for helpful comments on this manuscript. This research was sponsored by the U.S. Department of Energy (US-DOE), Fossil Energy Advanced Research Materials program, and US-DOE, Office of Energy Efficiency and Renewable Energy, Industrial Technologies Program, under Contract No. DE-AC05-00OR22725 with UT–Batelle, LLC. Part of the research was conducted at the Shared Research Equipment (SHaRE) user facility, which is sponsored at Oak Ridge National Laboratory by the Division of Scientific User Facilities, US-DOE.