Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
  • C22C19/03—Alloys based on nickel or cobalt based on nickel
  • C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
  • C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
  • C22C19/057—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being less 10%

Definitions

• the present invention relates to nickel alloys suitable for use under stress at high temperature and, more particularly, to nickel-base alloys of a special and controlled composition such that the alloys are especially adapted for use at very high temperatures, e.g., 1100 C., for example, as stator and rotor blades for gas turbine engines.
• the present invention contemplates providing nickel-base alloys characterized by good stressrupture properties at exceptionally high temperatures, e.g., 1100 C., while under stress, the alloys containing (by weight), up to about 4% and preferably from 1% to 3.5% chromium, about 7% to 19.5% tungsten, up to 7% molybdenum, up to 4% columbium, the sum of the tungsten plus 1.2 times the molybdenum plus the columbium plus two thirds of chromium being from 16.5% to 22%, from 4.7% to 6.8% aluminum up to 22% cobalt, up to 0.5% carbon, up to 1.3% zirconium, up to 0.05 boron, the balance, apart from impurities, being nickel.
• the alloys containing (by weight), up to about 4% and preferably from 1% to 3.5% chromium, about 7% to 19.5% tungsten, up to 7% molybdenum, up to 4% columbium, the sum of the tungsten plus 1.2 times
• the expression balance or balance essentially in referring to the nickel content of the alloys does not exclude the presence of other elements commonly present as incidental elements, e. g., deoxidizing and cleansing elements, and impurities normally associated therewith in small amounts which do not adversely affect the novel characteristics of the alloys.
• the principal impurities that may be usually present are iron, silicon and manganese, and total amounts of these elements should be as low as possible and should not exceed 3%.
• the iron, silicon and manganese contents do not exceed 0.5%, 0.3% and 0.3%, respectively.
• a particularly advantageous alloy composition is as follows: about 2% to 3.5% chromium, about 12% to 18.5% tungsten, up to 4% and preferably not more than 3% molybdenum, e.g., up to 2% molybdenum, from 0.2% to 2% columbium and most preferably from 0.2% to less than 1.5% columbium, the sum of 1.2 times the percent molybdenum plus the percent tungsten plus the percent columbium plus /3 the percent chromium being from 18% to 21%, about 5.25% to 6.25% aluminum, up to 16% and preferably from 5% to about 16% cobalt, from 0.05 to 0.3% carbon, up to 0.035% boron, about 0.1% to 1% zirconium and the balance essentially nickel.
• the effect on the stress-rupture properties as a result of using chromium contents both within and without the invention is shown by the test results in Table I.
• the nominal composition (percent by weight) of the alloy base to which different chromium contents were added is as follows: 0.13% carbon, 18% tungsten, 1% columbium, 6% aluminum, 0.5% zirconium, with nickel constituting the balance.
• Alloys 1 to 4 are in accordance with the invention while Alloy 5 is not.
• the stress-rupture life in hours (hrs.) and percent tensile elongation (Elong) are reported in Table I, the test conditions being 1100 C. under a stress of 7 long tons per square inch (t.s.i.).
• the best properties are obtained when the chromium content is from 1 to 3.5%; however, if resistance to oxidation is of particular importance the chromium content is preferably at least 2%.
• the chromium content can be extended to 4% but as illustrated by Alloy 4, the stress-rupture life is considerably reduced.
• the stress-rupture properties are also critically dependent upon the contents of tungsten, molybdenum and columbium and the effect of variations in the proportions of these constituents is shown in Table II.
• the base alloy (nominal) in which the above-mentioned three elements were varied contained 0.13% carbon, 3% chromium, 6% aluminum, 0.5% zirconium, the balance being nickel. All the alloys except those indicated by an asterisk are in accordance with the invention.
• the impact properties of the alloys at high temperatures are improved by utilizing low carbon contents, and for the greatest impact strength the carbon content should not exceed 0.05% and can even be less than 0.3%.
• the carbon content is less than about 0.03%, the alloys should contain at least 0.01% boron for attaining optimum stress-rupture characteristics.
• Percent Zirconium and boron improve the stress-rupture lives of the alloys, and it is preferred that the alloys contain from 0.1% to 1.0% of zirconium.
• the quantities of zirconium and boron are preferably so correlated that the value of the expression Percent Zr+10 (Percent B) is from 0.1% to 1.2%.
• Percent B Percent Zr+10
• the alloys may be air-melted, but are preferably melted under vacuum. Whether or not they are vacuum-melted, the alloys are advantageously subjected to a vacuumrefining treatment comprising holding them in the molten state under high vacuum before casting the melt. It is preferred to hold the melt at a temperature of about 1400 C. to 1700 C. at not more than 100microns pressure for a period of at least about minutes and advantageously for 60 minutes or more. The duration of the treatment depends to some extent on the purity of the ingredients of the melt, a longer time being required when less pure ingredients are employed.
• the alloys are preferably cast under vacuum, but when making large castings from a melt that has been produced or refined under vacuum it makes little difference to the properties obtained Whether casting is carried out in vacuum, inert gas or air. All the stress-rupture test results given in this specification were obtained on test-pieces machined from specimens cast under vacuum at 1600 C. from vacuum-melted material that had been vacuum-refined for at least 15 minutes at 1550 C. under a pressure of less than 1 micron.
• Articles and parts cast from the alloys may be used in the as-cast condition for high-temperature service. If desired the alloys may be homogenized by heating in the temperature range 850 to 1250 C. before being put into service.
• articles and parts made from the alloys are preferably provided with a protective coating, for example, of aluminum.
• a nickel-base alloy characterized by good stressrupture characteristics at elevated temperatures of the order of about 1100 C. while under relatively high stress, said alloy consisting essentially of about 1% to 3.5% chromium, about 7% to 19.5% tungsten, up to 4% molybdenum, about 0.2% to 2% columbium, the sum of the tungsten plus 1.2 times the molybdenum plus the columbium plus two-thirds the chromium being from 16.5% to 22%, about 4.7% to 6.8% aluminum, up to 16% cobalt, up to 0.3% carbon, about 0.1% to 1% zirconium, up to 0.06% boron, the sum of the zirconium plus ten times the boron being from 0.1% to 1.2%, and the balance essentially nickel.
• a nickel-base alloy characterized by good stressrupture characteristics at elevated temperatures of the order of about 1100 C. while under relatively high stress, said alloy consisting essentially of 2% to 3.5% chromium, about 12% to 18.5% tungsten, up to 4% molybdenum, about 0.2 to 2% columbium, the sum of the tungsten plus 1.2 times the molybdenum plus the columbium plus twothirds the chromium being from 18% to 21%, about 5.25% to 6.25% aluminum, up to 16% cobalt, about 0.05% to 0.3% carbon, about 0.1% to 1% zirconium, up to 0.035% boron, the sum of the zirconium plus ten times the boron being from 0.1 to 1.2%, and the balance essentially nickel.
• a nickel-base alloy characterized by good stressrupture characteristics at elevated temperatures of the order of about 1100 C. while under relatively high stress, said alloy consisting essentially of up to 4% chromium, about 7% to 19.5% tungsten, up to 7% molybdenum, up to 4% columbium, the sum of the tungsten plus 1.2 times the molybdenum plus the columbium plus two-thirds the chromium being from about 16.5% to about 22%, about 4.7% to about 6.8% aluminum, up to 22% cobalt, up to 0.5% carbon, up to 1.3% zirconium, up to 0.5 boron, and the balance essentially nickel.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Inert Electrodes (AREA)
• Laminated Bodies (AREA)
• Catalysts (AREA)

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Citations (4)

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• 1964
  • 1964-10-20 GB GB42767/64A patent/GB1065770A/en not_active Expired
• 1965
  • 1965-10-14 US US496145A patent/US3389992A/en not_active Expired - Lifetime
  • 1965-10-15 NL NL6513374A patent/NL6513374A/xx unknown
  • 1965-10-16 DE DEJ29193A patent/DE1295848B/de active Pending
  • 1965-10-19 AT AT945365A patent/AT258591B/de active
  • 1965-10-19 FR FR35487A patent/FR1450310A/fr not_active Expired
  • 1965-10-20 CH CH1446665A patent/CH441772A/fr unknown
  • 1965-10-20 BE BE671159D patent/BE671159A/xx unknown

Patent Citations (4)

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