Low expansion alloys
AssigneeThe International Nickel Company, Inc.
InventorsDavid Francis Lupton, John Jefferson Mason, Peter John Penrice
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Abstract
A carbidic low expansion alloy which is especially useful as a cast structure requiring close dimensional tolerances is comprised of about 21 to about 55% nickel, up to about 18% cobalt, from about 0.3 to about 2.5% carbon, up to about 3% chromium, from about 0.2 to about 1.2% vanadium, up to about 3% molybdenum, up to about 2% zirconium, niobium and tungsten, and the balance essentially iron, with the provisos: % Ni + 0.75 (% Co) = 30.5 to 55, Cr + Mo + V + Zr + Nb + W = 1 to 4 Ni : Fe .gtorsim. 0.4:1.
Claims24
A dimensionally stable casting being in the as-cast heat treated condition and made from a high-strength, low expansion carbidic alloy consisting essentially of, by weight, from about 21 to about 43% nickel, up to about 18% cobalt, from about 0.3 to about 1.0% carbon, from about 0.1 to about 1% chromium, from about 0.2 to about 1.2% vanadium, up to about 2% molybdenum, up to about 0.5% aluminum, up to about 0.5% silicon, up to about 2% manganese, up to about 2% zirconium, up to about 2% niobium, up to about 2% tungsten, up to about 0.1% magnesium, up to about 0.05% calcium and up to about 0.2% in total of at least one of the group consisting of yttrium, lanthanum and the lanthanides, with the provisos that the sum of the chromium, molybdenum, vanadium, zirconium, niobium and tungsten contents is in the range of from 1 to 4, the sum of %Ni + 0.75 (%Co) = 31.5 to 43 and the nickel to iron ratio is equal to or greater than 0.4:1, the balance, apart from impurities, being essentially iron, said casting exhibiting at room temperature a predominantly austenitic structure and having a 0.2% proof stress at 500.degree.C greater than 200 N/mm.sup.2 and a coefficient of thermal expansion over the temperature range 20.degree. to 250.degree.C not greater than 6.5 .times. 10.sup.-.sup.6 /.degree. c.
A dimensionally stable casting being in the as-cast, heat treated condition and made from a high-strength low expansion carbidic alloy consisting essentially of, by weight, from about 21 to about 35 nickel, from about 5 to about 18% cobalt, from about 0.3 to about 2.5% carbon, up to about 3% chromium, from about 0.2 to about 1.2% vanadium, up to about 3% molybdenum, up to about 0.5% aluminum, up to about 0.5% silicon, up to about 2% manganese, up to about 2% zirconium, up to about 2% niobium, up to about 2% tungsten, up to about 0.1% magnesium, up to about 0.05% calcium, and up to about 0.2% in total of at least one of the group consisting of yttrium, lanthanum and the lanthanides, with the provisos that the sum of the chromium, molybdenum, vanadium, zirconium, niobium and tungsten contents is in the range of from 1 to 4, the sum of % Ni + 0.75 (%Co) = 30.5 to 55, and the nickel to iron ratio is equal to or greater than 0.4:1, the balance, apart from impurities, being essentially iron and said casting exhibiting at room temperature a predominantly austenitic structure.
A precision cast rotor having adjoining thick and thin sections which are resistant to hot tearing at the junctures, said rotor being subjected in use to high centrifugal stresses, thermal cycling, temperature gradients, and simultaneously to oxidizing and hydrocarbon combustion product atmospheres, said rotor being made of a low expansion alloy cast at elevated temperatures and cooled, the alloy having a composition consisting essentially of, by weight, from about 21% to about 43% nickel, up to about 18% cobalt, from about 0.3 to about 2.5% carbon, up to about 3% chromium, from about 0.2 to about 1.2% vanadium, up to about 3% molybdenum, up to about 0.5% aluminum, up to about 0.5% silicon, up to about 2% manganese, up to about 2% zirconium, up to about 2% niobium, up to about 2% tungsten, up to about 0.1% magnesium, up to about 0.05% calcium, and up to about 0.2% in total of at least one of the group consisting of yttrium, lanthanum and the lanthanides, with the provisos that the sum of the chromium, molybdenum, vanadium, zirconium, niobium and tungsten contents is in the range of from 1 to 4, the sum of % Ni + 0.75 (% Co) = 30.5 to 55, and the nickel to iron ratio is equal to or greater than 0.4:1, the balance, apart from impurities, being essentially iron.
Dependencies are inferred from the claim text.