A High Strength Nickel-Base Alloy With Improved Oxidation Resistance up to 2200 deg F

Abstract

A high strength nickel-base alloy has been developed which compares favorably in oxidation resistance with known high strength nickel-base alloys. The alloy, although basically a cast material, also possesses workability potential. After 310 hr exposure to air at 1900 deg F, the alloy had a weight gain of 1.8 mg/cm2 . The total affected zone, oxidized material plus depletion zone, was 0.4 mil. This compares with a weight gain of 3.0 mg/cm2 and a total affected zone depth of 3.3 mils for René 41 after 100 hr exposure at 1900 deg F. In sheet form after 8 hr at 2200 deg F, its oxidation resistance was approximately the same as that of René 41 at 1900 deg F. Tensile strengths of the alloy after rolling and heat-treatment ranged from an average of 185,000 psi at 1400 deg F to 3000 psi at 2200 deg F. Maximum elongation was 55 percent and occurred at the latter temperature. At 1900 deg F, average tensile strength was 64,500 psi in the as-cast condition, and 54,000 psi after rolling and heat-treatment. Stress rupture data for low and intermediate stress levels were obtained. In the as-cast condition, use temperatures for 500, 100, and 10-hr life at 15,000 psi are 1815, 1895, and 2010 deg F, respectively. At 8000 psi and 2125 deg F, rupture life was 13 hr and compared favorably with some of the strongest known nickel and cobalt-base alloys. The very good high temperature oxidation resistance, good high temperature strength, and at least limited workability of this alloy suggest that it may be applicable for use in advanced gas turbine engine components.