US3639179A - Method of making large grain-sized superalloys - Google Patents

Method of making large grain-sized superalloys Download PDF

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US3639179A
US3639179A US7895A US3639179DA US3639179A US 3639179 A US3639179 A US 3639179A US 7895 A US7895 A US 7895A US 3639179D A US3639179D A US 3639179DA US 3639179 A US3639179 A US 3639179A
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temperature
billet
percent
cold
powder
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Steven H Reichman
John W Smythe
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ALLEGHENY INTERNATIONAL ACCEPTANCE Corp
Federal Mogul LLC
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Federal Mogul LLC
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Assigned to HELLER FINANCIAL, INC. reassignment HELLER FINANCIAL, INC. SECURITY INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: SPECIAL METALS CORPORATION
Assigned to SPECIAL METALS CORPORATION reassignment SPECIAL METALS CORPORATION RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: CITICORP INDUSTRIAL CREDIT, INC.
Assigned to SPECIAL METALS CORPORATION reassignment SPECIAL METALS CORPORATION RELEASED BY SECURED PARTY (SEE DOCUMENT FOR DETAILS). Assignors: AL-INDUSTRIAL PRODUCTS, INC., A CORP. OF PA, ALLEGHENY INTERNATIONAL, INC., A CORP. OF PA
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/10Changing 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
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C1/00Making non-ferrous alloys
    • C22C1/04Making non-ferrous alloys by powder metallurgy
    • C22C1/0433Nickel- or cobalt-based alloys

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  • ABSTRACT A process for making nickel-base superalloys possessing superior high-temperature properties which employs powder metallurgical techniques and includes the steps of densifying the powdered alloy into a blank approaching 100 percent [52] U.S.Cl.
  • the superalloy is microcast or atomized to a powder state and then consolidated in a substantially oxygen-free environment to a blank of the desired size and configuration, which is substantially free from segregation.
  • a continuing problem experienced in superalloy components made by such powder metallurgical techniques has been the severe limitation in effecting any appreciable grain growth in the resultant densified component. It is believed that such grain growth restriction is in part attributable to oxides and other relatively insoluble impurities which are present on the surfaces of the powder particles.
  • Various precautions taken to reduce the presence of such insoluble impurities have not been successful since the problem in achieving such grain growth has been encountered even with powdered alloys containing as little as 30 parts per million (p.p.m.) oxygen.
  • the benefits of the present invention are achieved by an improved process for making large grain-sized nickel-base superalloys in which the alloy is initially microcast or otherwise subdivided into a powder form of controlled size and is thereafter confined and densified into a body or blank approaching substantially 100 percent theoretical density.
  • the dense body is subjected to cold working at a temperature below the recrystallization temperature of the alloy and thereafter is recrystallized at a temperature between the recrystallization temperature and the solvus of the gammaprime phase for a period of time sufficient to nucleate new grains.
  • the recrystallized body is thereafter heat treated at a temperature above the solvus of the gamma-prime phase and below the incipient melting temperature of the alloy for a period of time sufiicient to effect grain growth and the attainment of the desired ultimate grain size.
  • the nickel-based superalloys made in accordance with the process comprising the present invention are characterized as being of exceptionally large grain size and possessing superior tensile strength and stress rupture life at elevated temperatures, that is, temperatures in excess of about l,400 F. in comparison to similar-type alloys heretofore known.
  • FIG. I is a schematic flow sheet illustrating the sequence of steps in accordance with the preferred practice of the process comprising the present invention.
  • FIG. 2 is a photomicrograph of a Kallings etched sample taken at a magnification of 500 times of the grain structure of a superalloy after densification from loose powder to a density corresponding substantially to percent theoretical densiy;
  • FIG. 3 is a photomicrograph of the same alloy shown in FIG. 2 at the same magnification after being cold worked and subjected to recrystallization;
  • FIG. 4 is a photomicrograph of the grain structure of a Kallings etched tensile specimen taken at a magnification of 10 times prepared from the alloy shown in FIGS. 2 and 3 after heat treatment to effect grain growth.
  • the process comprising the present invention consists of five basic steps which are performed in the same sequence as illustrated in the flow sheet.
  • a nickel-based superalloy of the desired composition is initially comminuted or microcast so as to form a powder of the desired configuration and particle size which thereafter is confined and densified, forming a body or blank having a density approaching a 100 percent theoretical density.
  • the resultant blank is thereafter cold worked, that is, subjected to deformation at a temperature below the recrystallization temperature of the alloy, followed by a recrystallization step in which nucleation of new grain occurs.
  • the recrystallized blank is subjected to a heat treatment at a controlled temperature, during which a growth in the grain size is effected and by proper control, can be increased up to almost a single crystal structure.
  • each of the powder particles is of substantially the same nominal composition
  • microcasting such as achieved by atomization of a melt of the alloy
  • the microcasting of the molten alloy can be achieved, for example, by an atomization process employing an atomization nozzle and technique as described in US. Pat. No. 3,253,783, which is assigned to the same assignee as the present invention and is incorporated herein by reference.
  • the atomization of the superalloy and the collection of the powder particles is achieved under conditions whereby oxygen and oxygen-containing substances, including water, are not permitted to contact the powder particles for any appreciable time to minimize oxidation and/or oxygen entrapment.
  • the degree of precautions required to prevent oxidation of the superalloy during the atomization process is dependent to a large extent on the specific alloying constituents present in the alloy. For example, the presence of aluminum and titanium require particular precautions due to their susceptibility to oxidation attack at the high temperatures encountered in conventional microcasting techniques.
  • the interior of the equipment to be employed is initially evacuated and thereafter back-flooded with the substantially dry, nonoxidizing atmosphere prior to initiation of the atomization of the melt.
  • the oxygen content of the powder as finally densified is preferably controlled to a level of less than about I00 p.p.m.
  • the superalloy is transformed into a metallic powder in which the particles preferably are of a generally spherical configuration and wherein each powder particle is of substantially the same or similar alloy chemistry.
  • the metallic powder is thereafter recovered and is subjected to a screening operation so as to segregate the powder particles which are suitable for forming the densified body or billet of superalloy.
  • particles of a size less than about 60 mesh United States Standard Sieve Size (250 microns) can be satisfactorily employed down to a particle size as small as about 1 micron.
  • the powder particles range from about 100 mesh (150 microns) to about 10 microns, and wherein the particles are further randomly distributed over the aforementioned range. This provides for optimum packing density of the free-flowing powder, facilitating subsequent densification thereof.
  • the resultant superalloy powder having the desired composition and particle size, is thereafter confined and densified at elevated temperatures so as to form a body or billet approaching 100 percent theoretical density.
  • the densification of the metallic powder can be achieved by any one of the variety of techniques well known in the art, including extrusion, hot upsetting, vacuum die pressing, hot isostatic compaction, explosive compaction, etc.
  • the densification process is preferably done at an elevated temperature to facilitate a bond of the powder particles and to facilitate compaction and- 5 deformation thereof into a billet approaching substantially 100 percent theoretical density.
  • preheat temperatures ranging from 1,900 F. up to about 2,500 F. can be satisfactorily employed.
  • the specific temperature used within the aforementioned range is dictated by that temperature approaching the solidus or just below the incipient melting point of the powder particles.
  • the aforementioned explosive compaction technique in which the powder is subjected to violent densification is usually done without any appreciable preheat.
  • Optimum packing of the interior of such containers with the loose powder can be achieved by subjecting the containers to sonic or supersonic frequencies wherein packing densities ranging from about percent to about 70 percent of a theoretical 100 percent density can be attained.
  • the loose powder particles can be confined in the cavity of a die, subjected to vacuum and compacted so as to make a preform approaching 85-90 percent theoretical density.
  • a preform can also be attained by compacting the powder in vacuum and sintering it at an elevated temperature, forming a self-sustaining body or billet which subsequently can be subjected to further compaction to attain substantially 100 percent density.
  • Such containers may comprise any metal having sufficient ductility to enable their deformation by extrusion at elevated temperatures without rupture of the sidewalls, thereby maintaining the sealed integrity of the powder particles therein.
  • Typical of such ductile metals which are compatible with the 60 superalloy powder and which can be satisfactorily employed for the practice of the present invention are various of the socalled conventional stainless steels such as AlSl-type 304 or an M81 1010 mild steel.
  • the resultant densified billet is allowed to cool and is thereafter cold worked by subjecting it to a mechanical deformation, such as by passing it between a pair of rolls or by subjecting it to a further extrusion operation.
  • the cold working of the densified billet can be achieved in one or more successive passes to impart he desired degree of cold work to the billet, which is dictated by that amount necessary to provide for a substantially complete recrystallization of the alloy at the specific temperature used during the following recrystallization step.
  • the magnitude of cold working expressed in terms of percentage reduction of the cross-sectional area of the densified body or billet during such cold working can range from only several percent up to about 50 percent or more.
  • the maximum degree of cold working imparted to the densified billet is dictated by practical considerations, including equipment limitations and time. Usually, 50 percent reductions in crosssectional area in one pass have been found satisfactory and cross-sectional area reductions or the equivalent cold working in a range of about 30 percent to about 50 percent at moderate temperatures ranging from about l,000 F. to about l,700 F. constitutes a preferred practice.
  • the densified blank or billet is preferably heated to facilitate deformation thereof and as previously indicated, can be heated to moderate temperatures which approach but are below the recrystallization temperature of the specific alloy.
  • the recrystallization temperature generally is in the range of from about 1,700 F. to about 2,l00 F. In view of this, it is preferred to heat the densified billet to a temperature of from about 1,000 F. to about l,700 F. during such cold reduction.
  • recrystallization temperature is defined as that temperature above which a nucleation and growth of new strain-free grains occurs accompanied by consumption of the cold-worked matrix as a result of the growth of such grains.
  • the resultant densified and cold-worked billet is thereafter subjected to recrystallization at a temperature above the minimum recrystallization temperature but below the gammaprime solvus temperature.
  • the gamma-prime solvus temperature is defined as the temperature at or above which the gamma-prime phase dissolves in the gamma phase matrix.
  • the gamma-prime phase in turn is defined as a variety of intermetallic compounds which are generally expressed by the formula Ni,,(X,Y,Z) in which X, Y and Z represent, for example, aluminum, titanium, cobalt, etc., and wherein a" and b" are integers. These intermetallic compounds at temperatures below the gamma-prime solvus temperature are dispersed throughout the gamma matrix and act as a strengthening agent.
  • recrystallization of the cold-worked and densified billet is achieved at a temperature generally ranging from about l,700 F. up to about 2,l00 F. for a period of time sufficient to effect a nucleation of new strain-free grains in the cold-worked billet. Recrystallization is continued for a period of time sufficient to effect substantially full recrystallization of the billet, which, for most nickel-based superalloys which are cold worked in an amount ranging from about 10 percent to about 50 percent in terms of reduction of cross-sectional area or the equivalent thereof at recrystallization temperatures of from l,700 F. up to about 2,100 F., requires about 2 to about 12 hours.
  • the recrystallization of a cold-worked billet can be performed at any time after the cold working and similarly, the heat-treating step can be performed at any time after the recrystallization step.
  • the absence of any criticality in time with respect to the performance of the several process steps provides further advantages in connection with the versatility and processing flexibility afforded.
  • the densified, cold-worked and recrystallized billet is subjected to a heat treatment in which grain growth occurs.
  • the heat-treating operation is carried out by heating the recrystallized billet to a temperature above the gamma-prime solution or solvus temperature and below the incipient melting point of the gamma matrix.
  • the incipient melting point of the gamma matrix for nickel-based superalloys of the general type to which the process is applicable conventionally ranges from about 2,200 F. up to about 2,500 F.
  • the duration of heat treatment can be varied so as to provide the desired degree of from about 2,l0O F. to about 2,400 F.
  • the billet was subjected to heat treatment at a temperature of 2,150 F. for a period of about 72 hours.
  • the heat treatment temperature employed is above the gamma-prime solvus temperature but below the incipient melting temperature of this alloy.
  • the large grain structure attained as a result of the heat treatment step is clearly evident in the photomicrograph comprising FIG. 4 of the drawings which comprises a Kalling's etched micrograph of a tensile specimen prepared from the billet and photographed at a magnification of 10 times.
  • the alloy processed in accordance with he present invention had a stress rupture life EXAMPLEI j to failure of 196 hours, whereas conventional cast-and- A millfel'based sljlperanoy correspondmg the nominal wrought U-700 alloy of the same composition had a life of composition of Udrmet 700, as set forth in table 1, was only 10 hours under these same conditions microcast into spherical powder particles and were screened while it will be apparent that the description f the Pmviding f 'f y Filed Powder ranging from 10 mlcmns preferred embodiments of the present invention is well calcu- P to micro!
  • the microstructure of the resultant densified billet is illusperalloy which comprises the steps of confining and densifying trated in FIG. 2.
  • the resultant extruded rod thereafter was a powder of said superalloy into a billet, cold working said bilpreheated to l,700 F., which is approximately 200 F. below let by effecting deformation thereof at a temperature below its recrystallization temperature.
  • the recrystallization temperature of the alloy, recrystallizing the billet was cold worked by passing it through a pair of rolls, the cold-worked said billet by heating; it to a temperature effecting approximately a 50 percent reduction in cross-secabove its recrystallization temperature and below the gammational area in one pass.
  • the resultant cold-worked billet was prime solvus temperature for a period of time sufficient to efthereafter recrystallized for a period of 2% hours at a temperafeet nucleation of new grains, and thereafter heat treating the ture at 2,100 R, which is a temperature above the recrystalrecrystallized said billet at a temperature above the gammalization temperature but below the gamma-prime solvus temprime solvus temperature and below the incipient melting perature for this alloy.
  • the resultant recrystallized structure of point of the gamma matrix for a period of time sufficient to efthe cold worked and recrystallized billet is illustrated in FIG. feet growth of the grain to the desired size.

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  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
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  • Crystallography & Structural Chemistry (AREA)
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US7895A 1970-02-02 1970-02-02 Method of making large grain-sized superalloys Expired - Lifetime US3639179A (en)

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JP (1) JPS5338250B1 (de)
BE (1) BE762376A (de)
BR (1) BR7100768D0 (de)
CA (1) CA920397A (de)
CH (1) CH568397A5 (de)
DE (1) DE2103875C3 (de)
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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3865575A (en) * 1972-12-18 1975-02-11 Int Nickel Co Thermoplastic prealloyed powder
US3920489A (en) * 1970-03-02 1975-11-18 Gen Electric Method of making superalloy bodies
US3930841A (en) * 1972-12-18 1976-01-06 The International Nickel Company, Inc. Thermoplastic prealloyed powder
US3988524A (en) * 1973-01-15 1976-10-26 Cabot Corporation Powder metallurgy compacts and products of high performance alloys
US4062678A (en) * 1974-01-17 1977-12-13 Cabot Corporation Powder metallurgy compacts and products of high performance alloys
US4066449A (en) * 1974-09-26 1978-01-03 Havel Charles J Method for processing and densifying metal powder
US4073648A (en) * 1974-06-10 1978-02-14 The International Nickel Company, Inc. Thermoplastic prealloyed powder
US4081295A (en) * 1977-06-02 1978-03-28 United Technologies Corporation Fabricating process for high strength, low ductility nickel base alloys
US4497669A (en) * 1983-07-22 1985-02-05 Inco Alloys International, Inc. Process for making alloys having coarse, elongated grain structure
US5451244A (en) * 1994-04-06 1995-09-19 Special Metals Corporation High strain rate deformation of nickel-base superalloy compact
US5826160A (en) * 1995-08-14 1998-10-20 The United States Of America As Represented By The Secretary Of The Army Hot explosive consolidation of refractory metal and alloys
US6021174A (en) * 1998-10-26 2000-02-01 Picker International, Inc. Use of shaped charge explosives in the manufacture of x-ray tube targets
US6129795A (en) * 1997-08-04 2000-10-10 Integran Technologies Inc. Metallurgical method for processing nickel- and iron-based superalloys
US20050106056A1 (en) * 2003-11-18 2005-05-19 Dwa Technologies, Inc. Manufacturing method for high yield rate of metal matrix composite sheet production
US20180223388A1 (en) * 2015-02-17 2018-08-09 Sandvik Materials Technology Deutschland Gmbh Method for producing a strand from stainless steel and strand made of stainless steel
EP3772544A4 (de) * 2018-03-06 2021-12-08 Hitachi Metals, Ltd. Verfahren zur herstellung einer hochfeuerfesten legierung auf nickelbasis und hochfeuerfeste legierung auf nickelbasis

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8519579D0 (en) * 1985-08-03 1985-09-11 Apsley Metals Ltd Pneumatic tyres
US4761190A (en) * 1985-12-11 1988-08-02 Inco Alloys International, Inc. Method of manufacture of a heat resistant alloy useful in heat recuperator applications and product
US4816084A (en) * 1986-09-15 1989-03-28 General Electric Company Method of forming fatigue crack resistant nickel base superalloys
US10245639B2 (en) * 2012-07-31 2019-04-02 United Technologies Corporation Powder metallurgy method for making components

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3524744A (en) * 1966-01-03 1970-08-18 Iit Res Inst Nickel base alloys and process for their manufacture

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3524744A (en) * 1966-01-03 1970-08-18 Iit Res Inst Nickel base alloys and process for their manufacture

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3920489A (en) * 1970-03-02 1975-11-18 Gen Electric Method of making superalloy bodies
US3865575A (en) * 1972-12-18 1975-02-11 Int Nickel Co Thermoplastic prealloyed powder
US3930841A (en) * 1972-12-18 1976-01-06 The International Nickel Company, Inc. Thermoplastic prealloyed powder
US3988524A (en) * 1973-01-15 1976-10-26 Cabot Corporation Powder metallurgy compacts and products of high performance alloys
US4062678A (en) * 1974-01-17 1977-12-13 Cabot Corporation Powder metallurgy compacts and products of high performance alloys
US4073648A (en) * 1974-06-10 1978-02-14 The International Nickel Company, Inc. Thermoplastic prealloyed powder
US4066449A (en) * 1974-09-26 1978-01-03 Havel Charles J Method for processing and densifying metal powder
US4081295A (en) * 1977-06-02 1978-03-28 United Technologies Corporation Fabricating process for high strength, low ductility nickel base alloys
US4497669A (en) * 1983-07-22 1985-02-05 Inco Alloys International, Inc. Process for making alloys having coarse, elongated grain structure
AU570059B2 (en) * 1983-07-22 1988-03-03 Inco Alloys International Inc. Non-ferrous ni-cr-fe alloys having a coarse elongated grain structure
US5451244A (en) * 1994-04-06 1995-09-19 Special Metals Corporation High strain rate deformation of nickel-base superalloy compact
EP0676483A1 (de) * 1994-04-06 1995-10-11 Special Metals Corporation Pressling aus Superlegierung auf Ni-Basis und deren Verformung mit hoher Umformgeschwindigkeit
US5826160A (en) * 1995-08-14 1998-10-20 The United States Of America As Represented By The Secretary Of The Army Hot explosive consolidation of refractory metal and alloys
US6129795A (en) * 1997-08-04 2000-10-10 Integran Technologies Inc. Metallurgical method for processing nickel- and iron-based superalloys
US6021174A (en) * 1998-10-26 2000-02-01 Picker International, Inc. Use of shaped charge explosives in the manufacture of x-ray tube targets
US20050106056A1 (en) * 2003-11-18 2005-05-19 Dwa Technologies, Inc. Manufacturing method for high yield rate of metal matrix composite sheet production
US7625520B2 (en) * 2003-11-18 2009-12-01 Dwa Technologies, Inc. Manufacturing method for high yield rate of metal matrix composite sheet production
US20180223388A1 (en) * 2015-02-17 2018-08-09 Sandvik Materials Technology Deutschland Gmbh Method for producing a strand from stainless steel and strand made of stainless steel
US10501820B2 (en) * 2015-02-17 2019-12-10 Sandvik Materials Technology Deutschland Gmbh Method for producing a strand from stainless steel and strand made of stainless steel
EP3772544A4 (de) * 2018-03-06 2021-12-08 Hitachi Metals, Ltd. Verfahren zur herstellung einer hochfeuerfesten legierung auf nickelbasis und hochfeuerfeste legierung auf nickelbasis

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CA920397A (en) 1973-02-06
DE2103875B2 (de) 1974-05-09
FR2080946B1 (de) 1973-06-08
BE762376A (fr) 1971-07-16
GB1302994A (de) 1973-01-10
ES387777A1 (es) 1974-02-01
DE2103875C3 (de) 1974-12-12
SE362900B (de) 1973-12-27
JPS5338250B1 (de) 1978-10-14
BR7100768D0 (pt) 1973-06-12
DE2103875A1 (de) 1972-01-27
NL7101367A (de) 1971-08-04
FR2080946A1 (de) 1971-11-26
CH568397A5 (de) 1975-10-31

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Effective date: 19870827

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