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
  • C22C19/07—Alloys based on nickel or cobalt based on cobalt

Definitions

• hightemperature oxidation and corrosion-resistant alloys having a percent by weight content of carbon 0.] to 0.7, chromium 24 to 35, tungsten 6 to 9, nickel 8.5 to 11.5, boron an effective amount of about 0.005 up to 0.05, zirconium 0.1 to 1.7, yttrium 0.03 to 1, iron up to 2 maximum as added with other alloying constituents, with the remainder cobalt except for incidental impurities such as sulfur and phosphorous both less than 0.04 percent, along with silicon, manganese, copper, titanium and the like which should be held to less than about 0.1 percent. It has been found that alloys having the above balanced composition are characterized by substantial increases in corrosion resistance at elevated temperatures, at the same time having improved physical characteristics such as high tensile and rupture strength and ductility.
• Nickel serves as a matrix stabilizer to maintain the FCC alloy matrix structure, and decreases the tendency toward'formation of embrittling stacking faults. Nickel fails in this role in lesser amounts than those set forth. Higher than prescribed amounts of nickel reduce the high-temperature strength and hot corrosion and oxidation resistance. Boron, which serves as a strengthener, results in embrittlement when used in excess due to the precipitation of metal 'borides at the alloy grain boundaries, and in poor high-temperature strength when used in too small amounts. lron, as pointed out above, is added with other alloying compounds and is not harmful up to the amount allowed, but when present in greater amounts than those prescribed reduces the strength and hot corrosion resistance of the final alloy. Zirconium serves as a strong carbide former, contributing to the high-temperature strength.
• ZrC and Cr C Yttrium is particularly critical to the hot corrosion resistance including both oxidation and corrosion caused by sodium, sulfur and the like.
• yttrium interacts during the oxidation process with the predominant (Ir- 0 oxide scale, enhancing its adherence to the underlying substrate as well as reducing Cr diffusion, therefore reducing oxidation kinetics.
• an alloy consisting of, by weight percent, carbon 0.5, chromium 29, tungsten 7, nickel l0, boron 0.01, iron 1, zirconium 1.5, and yttrium 0.15, the remainder being cobalt except for impurities such as Mn and Si, 01, and S and P, 0.04.
• example 2 there was prepared an alloy consisting essentially of, by weight percent, carbon 0.46, chromium 27.2, tungsten 6.7, nickel l0, boron 0.01 iron 0.71, zirconium 1.29, and yttrium 0.21, with the remainder essentially cobalt except for impurities such as titanium, manganese and silicon, which were present in amounts of less than 0.1 each.
• alloys which are suitable as materials of construction which combine superior high-temperature rupture stress with good resistance to hot corrosive influences.
• a cobalt base alloy characterized by good high-temperature strength, ductility, and corrosion resistance consisting essentially of about, by weight, carbon 0.1 to 0.7%, chromium 24 to 35%, tungsten 6 to 9%, nickel 8.5 to l 1.5%, boron an effective amount up to 0.5%, iron, up to 2%, zirconium 0.1 to
• a cobalt base alloy as in claim 1 consisting essentially of about, by weight, carbon 0.5%, chromium 29%, tungsten 7%, nickel 10%, boron 0.10%, iron 1%, zirconium 1.5%, yttrium 0.15%, with the remainder essentially cobalt except for impurities.
• a cobalt base alloy as in claim .1 consisting essentially of about, by weight, carbon 0.46%, chromium 27.2%, tungsten 6.7%, nickel 10%, boron 0.01%, iron 0.71%, zirconium 1.29%, yttrium 0.21%, with the remainder essentially cobalt except for impurities.
• a cobalt base alloy as in claim 1 consisting essentially of about, by weight, carbon 0.51%, chromium 28.3%, tungsten 7.23%, nickel 10%, boron 0.10%, iron 0.68%, zirconium 1.23%, yttrium 0.24%, with the remainder essentially cobalt except for impurities.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Turbine Rotor Nozzle Sealing (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=21698271

Family Applications (1)

Country Status (5)

Cited By (3)

Families Citing this family (1)

• 1970
  • 1970-01-09 US US1884A patent/US3615375A/en not_active Expired - Lifetime
  • 1970-12-18 GB GB6013570A patent/GB1309308A/en not_active Expired
• 1971
  • 1971-01-07 DE DE2100477A patent/DE2100477C3/de not_active Expired
  • 1971-01-08 FR FR7100546A patent/FR2075359A5/fr not_active Expired
  • 1971-01-08 CH CH25571A patent/CH551490A/xx not_active IP Right Cessation

Also Published As

Similar Documents

Legal Events