Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/10—Alloys containing non-metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
  • C22C32/001—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides
  • C22C32/0015—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides with only single oxides as main non-metallic constituents
  • C22C32/0026—Matrix based on Ni, Co, Cr or alloys thereof

Definitions

• the particles are then treated in an atmosphere which provides on the particle a film of from a small but elfective amount up to about 6 volume percent of the particle of a compound of the alloy selected from the compounds, nitrides, carbides and oxides.
• the particles so treated are then consolidated into an article, which can be a mill form, during which the film is fragmented and the fragments are dispersed throughout the matrix of the article. Further improved properties are obtained by additional working such as by ordinary means as rolling, forming, swaging, etc. to provide a deformation texture while preferably avoiding recrystallization during working.
• the nickel base superalloys In particularly wide use are the nickel base superalloys because they can be made to have good surface stability and high strength to temperatures up to about 80% of their absolute melting temperature. Iron and cobalt alloys continue to be used because of their excellent surface stability or hot corrosion resistance, although they are somewhat weaker than the nickel base superalloys. In any event, to meet various advancing design requirements, met-allurgists not only are seeking to find new compositions for such superalloys to provide them with improved mechanical properties along with surface stability but also they are seeking to improve the mechanical properties of known alloys by thermomechanical processing techniques.
• Another object is to provide such a method for making a gamma prime strengthened nickel base superalloy article, the mechanical strength properties of which are enhanced through improved dispersion strengthening.
• the present invention includes first treating the surface of an alloy particle, in the size range of about 0.0015- 0.03 and of the alloy to be strengthened, to provide a film, of a compound of elements of the alloy and selected from the compounds, oxides, nitrides, carbides and their combinations.
• particles can be oxidized, nitrided or carburized by methods currently used and known in the art.
• the amount of such film produced is an effective amount of about 0.1-6 volume percent of the particle. Above about 6 volume percent, the resulting alloy is too brittle whereas below about 0.1 volume percent microstructural control is more difficult and insufiicient strengthening is achieved.
• the particles are consolidated into an article, which as used herein can be a mill stock form or shape, in a manner well known in the art.
• they were placed in a steel container which then was provided with a vacuum.
• the container was heated and then worked by extrusion to consolidate the particles into a bar.
• One type of container which has been used successfully is about 5" in diameter and about 18" long of mild steel having a wall thickness of about 0.1".
• EXAMPLE 1 One alloy used in the evaluation of the present invention was an iron base alloy consisting norminally of, by weight, 25% Cr, 4% Al, 1% Y with the balance essentially iron and incidental impurities. Such an alloy has good ductility and excellent oxidation resistance to temperatures as high as 2600 F. However, it has relatively low tensile and creep properties at temperatures above about 50% of its absolute melting temperature. Therefore, it was considered an excellent example with which to show the improvement obtainable through the present invention without degradation of the excellent surface stability of this alloy system.
• Vacuum melted ingots of such iron base alloy were argon atomized and screened under argon to 60 mesh powder.
• the atomized powder was provided with a thin skin of oxide by heating in air in the range of from 1100- 1600 F.
• the resulting oxide was predominantly A1 but also included small amounts of such oxides as Fe, A1 0 and Cr O
• the volume fraction of oxide skin on the powder particle in this example was about 1 volume percent.
• the preoxidized powder particles were placed in a mild steel extrusion jacket which was sealed under vacuum. Extrusion was conducted at about 1800 F. to produce a final billet 1.6" by 0.5" by 8'.
• the surface stability characteristics of the alloy powder was substantially unaffected by its being oxidized prior to compaction and extrusion. However, its mechanical pronerties were greatly improved as a result of the combination of such preliminary oxidation and subsequent thermomechanical processing.
• the data of Table II compares the ordinary cast and wrought form of the alloy listed as Condition A with the alloy resulting from the present invention listed as Condition B and Condition C.
• the condition of Example B is the alloy in the as-extruded form previously described.
• the condition of Example C is the alloy after extrusion (primary working) and rolling (secondary working) at 1800 F. with multiple passes and intermediate soaks at 1200" F. until a total reduction from secondary working of at least 75% had been attained.
• the tensile specimens were heat treated in air at 2200 F. for 2 hours prior to testing.
• Condition D The ordinary condition and tensile properties for this alloy in its wrought condition is shown as Condition D.
• the alloy was worked at about 2050 F. to reduce it, without control of recrystallization. Therefore, the alloy was generally recrystallized between working steps.
• the alloy conditions resulting from practice of the present invention are shown by wrought forms E and F. These forms were extruded in steps to a 128/1 ratio in the range of 1900-2000 F., taking care during steps not to recrystallize. Then, after working, these forms were recrystallized at about 2200 F. Thus, aside from such care during working, the heat treatments for all conditions of Table III were the same.
• this Example 2 alloy is greatl improved by the combination of oxides or carbides or both, included through pretreatment, with thermomechanical processing which avoids recrystallization during working. Both the ultimate and 0.2% yield strengths are improved at least about 3 times.
• the alloy of this example currently used in production parts for gas turbine engines, is typical of the gamma prime strengthened, nickel base superalloys which are sensitive to recrystallization during working.
• a preferred form of this invention particularly as it relates to such Ni-base superalloys, includes the combination of compound addition and control of recrystallization during working.
• heating of the particles is conducted in the range of about 1100-1600 F.; the film is in an amount of about 1-3 volume percent; the consolidation is conducted in the range of about 1800-2000 F.; the article is secondarily worked in the range of about 1900-2000 F.; and recrystallization is conducted in the range of about References Cited UNITED STATES PATENTS 6 3,026,200 3/ 1962 Gregory 75206 3,315,342 4/ 1967 Roberts 75206 3,189,989 6/1965 Ebdon 75-206 3,343,952 9/1967 Delgrosso et al 75212 3,322,536 5/1967 Stoddard et a1 75212 3,216,824 11/1965 Boghen et al 75212 3,073,698 1/ 1963 Arbiter 75--212 FOREIGN PATENTS 866,082 4/ 1961 Great Britain 75206 CARL D. QUARFORTH, Primary Examiner B. HUNT, Assistant Examiner U.S. C1. X.R.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Powder Metallurgy (AREA)
• Manufacture Of Alloys Or Alloy Compounds (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=21723328

Family Applications (1)

Country Status (6)

Cited By (9)

Families Citing this family (3)

• 0
  • BE BE756885D patent/BE756885A/xx unknown
• 1970
  • 1970-01-29 US US00006931A patent/US3720551A/en not_active Expired - Lifetime
  • 1970-08-26 GB GB41082/70A patent/GB1285098A/en not_active Expired
  • 1970-08-31 JP JP45075634A patent/JPS5014206B1/ja active Pending
  • 1970-10-09 DE DE2049546A patent/DE2049546C3/de not_active Expired
  • 1970-10-28 FR FR7038895A patent/FR2074904A5/fr not_active Expired

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