Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
• • 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
  • C22C19/053—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 30% but less than 40%

Definitions

• the alloys also encompassed from 0.02 to 0.2% carbon, up to 0.6% zirconium, up to 1.2% hafnium, with the value of Zr 0.5 Hf) being not more than 0.6%, up to 0.02% boron, and up to 0.2% in total of yttrium and/or lanthanum, the balance being essentially nickel.
• the present invention contemplates articles and parts cast from alloys containing, by weight, from 26 to 35% chromium, about 10 to 25% 2 cobalt, about 0.1 to 0.6% niobium, about 0.3 to 1.5% tungsten, about 1 to 3% tantalum, about 2.5 to 5% titanium, about 1 to 2.5% aluminum, the titanium and aluminum being found in a total amount of about 4.3 to 5.75% and with the provisos that the ratio of titanium to aluminum be from 1.411 to 4:1 by weight and that be from 54.5 to 61.3, about 0.05 to 0.15% carbon, about 0.02 to 0.5% zirconium, about 0.002 to 0.05% boron, from 0 to 2% hafnium, and from 0 to 0.2% in total of yttrium and/or lanthanum, the balance, apart from impurities, being essentially nickel, the nickel preferably being present in an amount of at least 35%.
• the alloys from which articles and parts are cast contain from 27 to 33% chromium, from 10 to 20% cobalt, from 0.1 to 0.6% niobium, from 0.5 to 1.0% tungsten, from 1.5 to 2.8% tantalum, from 2.5 to 4.0% titanium, from 1.3 to 2.2% aluminum, both titanium and aluminum in a total amount of 4.3 to 5.75%, from 0.06 to 0.12% carbon, from 0.03 to 0.2% zirconium, from 0.003 to 0.02% boron, and the balance nickel.
• a particularly useful alloy for cast articles and parts, according to the invention contains about 28.6% chromium, about 14.7% cobalt, about 0.6% tungsten, about 0.3% niobium, about 2.66% tantalum, about 3.59% titanium, about 1.96% aluminum, about 0.1% carbon, about 0.1 1% zirconium, about 0.015% boron, the balance being nickel.
• articles and parts according to the invention were cast from Alloys 1 to 8 and compared in stress-rupture and impact strength tests with articles and parts outside the scope of the invention cast from Alloys A to L with the results being set forth in Table 1.
• All the alloys were vacuum melted and test pieces were machined from cast blanks of the particular alloys which had been treated by heating for 4 hours at 1150C., air-cooled, heated at 850C. for 16 hours and air cooled.
• Stress-rupture values are given in Table 1 obtained under a stress of 139 N/mm (Newtons per square millimeter) at 870C. together with impact strength values obtained by a Charpy test after 1000 hours at 850C.
• Articles outside the invention cast from Alloys A to L had stress-rupture lives at 139 N/mm and 870C. of less than 1520 hours and typically of the order of 740 to 1516 hours. Such articles cast from Alloys A to L had impact strengths after 1000 hours at 850C. up to J and typically of the order of 7 to 25 J. Thus articles of the invention have a high stress-rupture life coupled with a consistently good impact strength in comparison with similar articles outside the invention which have poorer stress-rupture lives coupled with inconsistent impact strength.
• Alloy E which contained 2.56% tantalum, 0.30% niobium that is a [%Nb /(%Ta)] value of 1.58%, and 0.73% tungsten
• Alloy l which contained 1.60% niobium and no tantalum or tungsten
• Alloy E had a stress-rupture life of 1154 hours and Alloy I a stress-rupture life of 1282 hours.
• Alloy E only had a value of 53.4 and Alloy l a value of 52.8 as given by the relationship:
• alloys with a relationship value in the range 54.5 to 61.3 had poorer stress-rupture lives as can be seen from Alloy L (relationship value 54.5 and stress-rupture life 843 hours) and Alloy H (relationship value 56.2 and stressrupture life 740 hours). Alloys L and A had impact strengths of 8 J and 7 J, respectively, indicating embrittlement due to sigma phase formation.
• articles and parts according to the invention are cast from alloys containing, about 28 to 29% chromium, about 14.5 to 15.5% cobalt, about 0.22 to 0.48% niobium, about 0.58 to 0.88% tungsten, about 1.7 to about 2.58% tantalum, about 3.3 to 3.48% titanium, about 1.75 to 2% aluminum, about 5 to 5.5% titanium plus aluminum, with the ratio of titanium to aluminum from 1.77:1 to 2.09:1,
• a ratio of titanium to aluminum of less than 1.4:1 reduces the stress-rupture life to an undesirable extent even when the alloy contains an otherwise acceptable total amount of titanium and aluminum.
• This can be seen from Table l by comparing Alloy D (life of 1366 hours at Ti/Al of 1.29:1) and Alloy E (life of 1154 hours at Ti/Al of 1.20:1) with Alloy 8 (life of 1591 hours at Ti/Al of 1.59:1 Indeed Alloy E which contains 2.36% titanium also shows that titanium contents of less than 2.5% undesirably reduce the stress-rupture life.
• a niobium content of less than 0.1% or the absence of niobium reduces the stress-rupture life as can be seen from the results of Alloy F in Table 1.
• articles and parts according to the invention are cast from alloys containing from 0.22 to 0.48% niobium.
• the zirconium content should be in the range of from 0.03 to 0.2%, and more preferably, in the range 0.04 to 0.11%.
• Articles and parts according to the invention may be blades and other components of gas turbine engines, and are also suitable for other applications where good stress-rupture life at high temperatures in corrosive environments is required.
• a cast alloy consisting essentially of, by weight, from 26 to 35% chromium, from 10 to 25% cobalt, from 0.1 to 0.6% niobium, from 0.3 to 1.5% tungsten, from 1 to 3% tantalum, from 2.5 to 5% titanium, from 1 to 2.5% aluminum, both titanium and aluminum in a total amount from 4.3 to 5.75% with the provisos that the ratio of titanium to aluminum is from 1.4:1 to 4:1 by weight and that the sum 5 [%Nb+ memo 6 (%Ti %Al) as (%Cr) is from 54.5 to 61.3, from 0.05 to 0.15% carbon, from 0.02 to 0.5% zirconium, from 0.002 to 0.05% boron, from 0 to 2% hafnium, and from 0 to 0.2% in total of yttrium and/or lanthanum, the balance, apart from impurities, being nickel.
• a cast alloy according to claim 1 containing 27 to 33% chromium, 10 to 20% cobalt, 0.5 to 1.0% tungsten, 1.5 to 2.8% tantalum, 2.5 to 4.0% titanium, 1.3 to 2.2% aluminum, 0.06 to 0.12% carbon, 0.03 to 0.2% zirconium, 0.003 to 0.02% boron, the nickel being at least 35%.
• a cast alloy according to claim 2 containing 28.2 to 30.4% chromium, 14.6 to 15.5% cobalt, 0.22 to 0.48% niobium, 0.6 to 0.94% tungsten, 1.7 to 2.58% tantalum, 2.7 to 3.68% titanium, 1.7 to 2.01% aluminum, 4.4 to 5.69% titanium plus aluminum, ratio of titanium to aluminum from 1.59:1 to 2.09:1 sum of 5 [%Nb+ A (%Tall 6 (%Ti %A1) as 1%Cr) being in the range of from 55 to 61.2, 0.08 to 0.10% carbon, 0.04 to 0.11% zirconium and 0.011 to 0.015% boron.
• a cast alloy according to claim 2 containing 28 to 29% chromium, 14.5 to 15.5% cobalt, 0.22 to 0.48% niobium, 0.58 to 0.88% tungsten, 1.70 to 2.58% tantalum, 3.30 to 3.48% titanium, 1.75 to 2% aluminum, 5.0 to 5.5% titanium plus aluminum, ratio titanium to am minum from 1.77:1 to 2.09:1, sum of 51%Nb+ I: (m-.111 6 (%Ti +%A1) ts 1%0] being in the range of from 56 to 60, 0.08 to 0.10% carbon, 0.04 to 0.11% zirconium and 0.011 to 0.015% b0- ron.
• a cast alloy according to claim 2 containing 28.6% chromium, 14.7% cobalt, 0.6% tungsten, 0.3% niobium, 2.66% tantalum, 3.59% titanium, 1.96% aluminum, 0.1% carbon, 0.1 1% zirconium and 0.015% boron.
• a cast component of the composition set forth in claim 2 which has been heat treated at 1 C, for 4 hours and air cooled followed by heat treatment at 850C for 16 hours and air cooled.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Turbine Rotor Nozzle Sealing (AREA)

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Citations (1)

• 1973
  • 1973-04-13 GB GB1795173A patent/GB1416375A/en not_active Expired
• 1974
  • 1974-04-09 IT IT50256/74A patent/IT1004176B/it active
  • 1974-04-10 FR FR7412657A patent/FR2225533B3/fr not_active Expired
  • 1974-04-10 JP JP49040068A patent/JPS5041716A/ja active Pending
  • 1974-04-12 US US460460A patent/US3925072A/en not_active Expired - Lifetime
  • 1974-04-13 DE DE2418219A patent/DE2418219A1/de active Pending

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