C. P. Stinner, J. Rakowski, ATI Allegheny Ludlum, Brackenridge, PA; P. J. Maziasz, Oak Ridge National Laboratory, Oak Ridge, TN; P. Montague, Solar Turbines, Inc, San Diego, CA
Heat exchangers and recuperators operate at high temperatures and pressures, and thus, require an alloy with good high temperature oxidation and creep resistance. Resistance to oxidation in the presence of water vapor has been found to be a critical factor in many applications, where breakaway oxidation may occur. AL20-25+NbTM (20 wt% Cr, 25 wt% Ni, + Nb) alloy has been found to have excellent resistance to oxidation in water vapor and has improved creep resistance compared to other stainless steels. The subject of this presentation is to discuss the oxidation and high temperature properties of this alloy as they relate to recuperator applications. The results of a joint program with ATI Allegheny Ludlum and Oak Ridge National Laboratory to optimize processing for creep resistance will also be discussed.
Summary: The properties of AL20-25+Nb alloy will be discussed with regard to high temperature applications. The alloy possesses excellent resistance to creep and oxidation in water vapor, which makes it ideal for recuperator air cells. A joint Allegheny Ludlum - ORNL project to optimize creep resistance will also be discussed.
