The newest of the high-performance superalloys invented by Special Metals Corporation, INCONEL? alloy 783 (UNS R30783/U.S. Patent 5,478,417), is an oxidation-resistant, low expansion, nickel-cobalt-iron alloy with aluminum, chromium, and niobium additions. The new alloy is of considerable interest to aircraft gas turbine engine designers and materials engineers for containment and clearance control components such as rings, casings, shrouds and seals for compressors, turbines and exhaust systems. The three-phase age hardenable alloy offers a range of improvements for these applications over alternative alloys in current use: A coefficient of thermal expansion approximately 20% lower than that of INCONEL alloy 718. Excellent resistance to oxidation, demonstrated in cyclic tests, at temperatures up to and beyond 1300°F (704°C). Resistance to SAGBO (stress accelerated grain boundary oxidation) comparable to that of INCONEL alloy 718, and significantly better than that of INCOLOY alloy 909. A density of 0.282 lb/in3 (7.81 g/cm3), 5% less than INCONEL alloy 718 or INCOLOY? alloy 909, contributing to an important potential improvement in strength-to-weight ratios. Manufacturing/processing characteristics comparable to those of INCONEL alloy 718, and less limiting than those of INCOLOY alloy 909. Special Metals’ INCONEL alloy 783 is available as forging billet (AMS 5940), rod and bar for machining, extruded section, and wire rod. Sheet product is currently under development. *In compliance with UNS R30783 Physical Properties *Mean coefficient of linear expansion between 70°F and the temperature shown. Inflection point = 780°F. Table 1 - Limiting Chemical Composition*, % Chromium...................................................................... 2.5-3.5 Nickel .........................................................................26.0-30.0 Iron ..............................................................................24.0-27.0 Niobium...........................................................................2.5-3.5 Aluminum........................................................................5.0-6.0 Cobalt........................................................................Remainder Boron.......................................................................0.003-0.012 Carbon........................................................................0.03 max. Manganese .................................................................0.50 max. Silicon .........................................................................0.50 max. Phosphorus..............................................................0.015 max. Sulfur .........................................................................0.005 max Titanium...........................................................................0.1-0.4 Copper.........................................................................0.50 max
