Creep-Resistant, Al2O3-Forming Austenitic Stainless Steels
Y. Yamamoto,*
M. P. Brady,
Z. P. Lu,
P. J. Maziasz,
C. T. Liu,
B. A. Pint,
K. L. More,
H. M. Meyer,
E. A. Payzant
A family of inexpensive, Al
2O
3-forming, high–creep strength
austenitic stainless steels has been developed. The alloys are
based on Fe-20Ni-14Cr-2.5Al weight percent, with strengthening
achieved through nanodispersions of NbC. These alloys offer
the potential to substantially increase the operating temperatures
of structural components and can be used under the aggressive
oxidizing conditions encountered in energy-conversion systems.
Protective Al
2O
3 scale formation was achieved with smaller amounts
of aluminum in austenitic alloys than previously used, provided
that the titanium and vanadium alloying additions frequently
used for strengthening were eliminated. The smaller amounts
of aluminum permitted stabilization of the austenitic matrix
structure and made it possible to obtain excellent creep resistance.
Creep-rupture lifetime exceeding 2000 hours at 750°C and
100 megapascals in air, and resistance to oxidation in air with
10% water vapor at 650° and 800°C, were demonstrated.
* To whom correspondence should be addressed. E-mail: bradymp{at}ornl.gov
