Improved creep-resistance of austenitic stainless steel for compact gas turbine recuperators

AbstractPrimary surface recuperators (PSRs) are compact heat-exchangers made from thin-foil type 347 austenitic stainless steel, which boost the efficiency of land-based gas turbine engines. Compact recuperators are also an essential technology for some new microturbines. Solar turbines uses foil folded into a unique corrugated pattern to maximize the primary surface area for efficient heat transfer between hot exhaust gas on one side, and the compressor discharge air on the other side of the foil. Allegheny-Ludlum produces 0.003–0.004 inches thick foil for a range of current turbine engines using PSRs that operate up to 660°C. One goal of this team-effort project is to modify the processing to enable improved creep resistance of such 347 stainless steel foils at 650–700°C. Laboratory-scale processing modification experiments recently have demonstrated that dramatic improvements can be achieved in the creep resistance of such typical 347 stainless steel foils. The modified processing enables fine NbC carb...