US3649378A - Monocarbide precipitation-strengthened nickel base alloys and method for producing same - Google Patents

Monocarbide precipitation-strengthened nickel base alloys and method for producing same Download PDF

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Publication number
US3649378A
US3649378A US835201A US3649378DA US3649378A US 3649378 A US3649378 A US 3649378A US 835201 A US835201 A US 835201A US 3649378D A US3649378D A US 3649378DA US 3649378 A US3649378 A US 3649378A
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alloy
precipitation
monocarbide
nickel
monocarbides
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Peshotan Sohrab Kotval
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Haynes International Inc
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Cabot Corp
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    • 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
    • C22C19/055—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 20% but less than 30%

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  • This invention relates to precipitation strengthened nickel base alloys and more particularly to alloys of this type which are strengthened by monocarbides.
  • the invention also relates to a method for producing monocarbide precipitation strengthened nickel base alloys.
  • Prior art wrought nickel base alloys are strengthened by two principal mechanisms: (a) solution strengthening which has also been described as matrix stiffening and (b) precipitation strengthening.
  • solute element In solution strengthening, a solute element, usually of large atomic size, strengthens the nickel-chromium matrix by its being in solid solution therewith. Molybdenum and tungsten solute atoms typically are used to produce this eifect in nickel base alloys. This type of strengthening is seriously limited by the natural limits of solubility of the strengthening atom in the nickel base matrix.
  • precipitation strengthening the solid solution matrix is usually super-saturated with respect to two or more solute elements and therefore, upon appropriate heat treatments, an aging reaction can occur causing the precipitation of phases (which are combinations of solute elements) which strengthen the alloy.
  • a strengthening precipitate should have coherency with the matrix, be well distributed within the body of the grain and be reasonably thermally stable.
  • Typical examples of precipitation strengthening elements are aluminum and titanium which alone or in combination with other elements such as columbium and tantalum result in the formation of precipitation strengthening phases.
  • Both solution strengthened and precipitation strengthened nickel base alloys contain suflicient carbon so as to form monocarbides of a simple face centered cubic structure whenever monocarbide forming elements such as Ti, Ta, Cb, V, Zr and Hf are present. 'It follows that since one or more of these elements are usually present in precipitation strengthened alloys, and are sometimes present in solution strengthened alloys, that the monocarbides will be present. It is important to note that these monocarbides are usually in the form of undissolved primary particles present in the alloy matrix but which do not effectively strengthen the same. Typically, primary monocarbide particles have particle diameters of between 10 and 20 microns in nickel base alloys.
  • the amounts of monocarbide-forming elements are usually at low enough levels so as to be in solid-solution in the alloy matrix after a portion of the monocarbide-forming element has combined with the available carbon present in the alloy to form the monocarbide.
  • the main object of the invention is to provide a nickel base alloy composition and method of making same wherein the heretofore latent strengthening characteristics of the monocarbides are utilized in such manner that the monocarbides serve as precipitation strengthening phases.
  • Another object of the invention is to utilize nickel base alloy compositions having monocarbide-forming elements at levels which heretofore were such as to permit only solid solution strengthening, as precipitation strengthening compositions.
  • a more specific object is to provide a nickel base alloy having dispersed therein primary monocarbides having less than 5 microns particle diameter and also having precipitated monocarbide particles of less than 250 angstroms 1n size.
  • FIGS. 1 and 2 are schematic representations of the microstructure of the alloys of the present invention.
  • FIG. 3 is a diagrammatic process flow chart outlining the steps required for making the alloys of the invention.
  • nickel-base alloy compositions having a new microstructure.
  • This microstructure is comprised of primary monocarbides having less than 5 micron particles size in addition to uniformly dispersed precipitated monocarbide particles of less than 250 angstroms particles size.
  • These alloy compositions are precipitation-strengthened by uniformly dispersed monocarbides and consist essentially by weight of 1522% Cr, 312% M0, at least one member selected from the group consisting of 6-9% Ta, 35% Cb and 36% V; the total content of Ta, Cb and V not exceeding 9%, and 0.030.l5% C., the balance being nickel and residual impurities.
  • the impurities should consist of not more than 7% Fe and not more than 8% Co.
  • the ability to produce the abovementioned nickel base alloy results from the discovery that by controlling the level of certain impurties in the nickel base alloy, (i.e. Fe) it is possible to solution heat treat the alloy at temperatures of about 2280 F. without causing liquation and melting. Although, ideally, higher temperatures would normally be required to dissolve monocarbides, it is possible to achieve partial dissolution thereof by progressively subjecting the material to an alternating sequence of high temperature solution heat treatments of about 2280 F. and quenching together with controlled cold working steps.
  • certain impurties in the nickel base alloy i.e. Fe
  • Chromium is required in the alloy within the range disclosed above to provide strengthening and corrosion resistance. Less than Cr yields an alloy with minimal corrosion resistance; over 22% Cr yields an alloy with reduced ductility.
  • Molybdenum is present in the alloy within the ranges shown above to provide further solution strengthening and corrosion resistance as required. Molybdenum is preferred in the alloy, although tungsten may replace molybdenum in whole or in part. Tungsten may be present in greater quantities than molybdenum, i.e. up to a maximum of 16%, but preferably about 12% nominally. Carbon must be present in the alloy within the range of about 0.03 to 0.15% by weight to promote the formation of carbides in the alloy. Less than 0.03% carbon is insufiicient to produce the carbides while over 0.15% carbon tends to yield a more brittle alloy. Alloys containing over 0.15% carbon are more difficult to work.
  • the alloy system of this invention must contain at least one of the group including tantalum, columbium, and vanadium. At least one of these elements must be present in the alloy together with carbon to provide the metal monocarbides that are precipitated in the nickelchromium (molybdenum) matrix. The presence of these precipitated carbides together with the critical processing steps that promote the controlled precipitation are the heart of the present invention.
  • Each element in this group must be present within the ranges stated above when that element is the principal carbide former. In some cases it may be desirable to substitute Hf, Zr or Ti for the element selected from the group consisting of Ta, Cb and V. The total content of elements in these groups must not exceed 9%. Iron may be present up to a maximum of 7%.
  • Boron, silicon, maganese, magnesium, and copper up to a total of about 2.5% may be present in the alloy within the ranges known in the art to be effective to enhance certain characteristics associated with these elements; i.e. the deoxidation step, casting fluidity, ductility and the like.
  • the balance of the alloy is nickel and adventitious impurities generally known to be present in this class of alloys.
  • FIG. 1 is a threedimensional representation of the microstructure as would be observed in a thin foil sample using transmission electron microscopy.
  • FIG. 2 is a representation of microstructure as would be observed by a replica of the surface of the specimen. It should be understood that this type of structure cannot be observed and resolved by normal optical metallographic techniques.
  • the microstructure of the alloys of the invention as shown consists of the usual grain structure with some precipitation of the chromium rich M C carbide phase at the grain boundaries.
  • Unique to this microstructure is the highly refined particles of the primary MC monocarbides P.
  • the actual size of the primary MC monocarbides P shown is about 12 microns.
  • the unique structure further has dispersed within it, fine precipitates of MC monocarbides K which are associated with sheets of planar lattice defects.
  • the precipitates K are of about 250 angstroms or less in size and being coherent with the matrix substantially strengthen it.
  • the alloys of the invention can be made by providing an alloy material with 1522% Cr, 312% M0, at least one member selected from the group consisting of 69% Ta, 3-5% Cb and 36% V, the total of Ta+Cb+V not exceeding 9%, and 0.03- 0.15 C, the balance being nickel and residual impurities, said impurities consisting of not more than 7% Fe and not more than 8% Co, said alloy being in a form capable of being cold-worked.
  • the material is solution heat-treated at a temperature within the range of 2250-2300 F. for a period of about 24 hours to at least partially dissolve the primary" monocarbide particles and thereby causing the monocarbideforming element and the carbon to be put into solid solution in the alloy matrix. Following this solution-heattreatment the material is water-quenched and cold worked. Until the final desired dimensions of the product are achieved, the above mentioned sequence of solution-heattreatment followed by quenching and cold-working is repeated. Thereafter, the cold-worked material is annealed for a period not exceeding one hour within the solution heat-treatment temperature range of 2250-2300 F.
  • the material After annealing, the material is water-quenched to about ambient temperature and is thereafter aged at a temperature within the range of 1100 F.1350 F. for a period of 24 to hours whereby a sufiicient volume fraction of the strength-giving precipitated fine monocarbides will occur.
  • EXAMPLE I A 5 1b. heat of material consisting of, by weight, 21.9% Cr, 8.83% M0, .067% C, 3.86% Cb, 4.9% Fe, the balance being nickel; was electron-beam melted and cast into a 1.5 round bar. This bar was solution heat treated at a temperature of 2282 F. for a period of 24 hours and water-quenched. Thereafter, the material was sequentially cold-worked, solution-heat-treated at 2282 F. and quenched. After the process was repeated five times, the resultant 0.025 sheet produced was solution heat treated (annealed) for a period of 1 hour at 2282" F. and quenched.
  • the material was cut into various specimens, each of which was aged at a diiferent temperature and time.
  • the range of aging temperatures was 1100 F.1350 F. and the range of aging times was 0.5 hour to 1500 hours.
  • thin foil transmission electron microscopy revealed that the requisite structure, as depicted in FIGS. 1 and 2, was established in the alloys.
  • the average yield 0.2% offset) stress for the aged material was 76,000 p.s.i. This represents an increase of about 100% from the average yield (0.2% offset) stress of the as-solution heat-treated and quenched material which at room temperature was 38,000 p.s.i.
  • the average yield (0.2% offset) stress of the aged material was 46,000 p.s.i. as compared to an average yield (0.2% oifset) stress of 34,000 p.s.i. for the as-solution heat treated and quenched material at 1300" F.
  • Ductility values for all these specimens were found to be in the range of 15-20% elongation.
  • EXAMPLE II A 5 1b. heat of material consisting of (by weight) 20.34% Cr, 8.90% Mo, 0.11% C, 8.58% Ta and 4.80% Fe, the balance being nickel was melted and processed in the same manner as described in connection with Example I. The material was thereafter structurally analyzed by electron microscopy which verified the formation of pre* cipitated monocarbides as described in Example 1.-
  • EXAMPLE III A 5 lb. heat of material consisting of (by weight) 22.2% Cr, 9.28% Mo, 0.04% C, 3.93% V and 4.75% Fe, the balance being nickel was melted and processed in the same manner as described in Example I. Analysis by electron microscopy verified the formation of precipitated monocarbides as described in Example 1.
  • a method of producing a precipitation-strengthend nickel-base alloy comprising the steps of:
  • step (a) A method as defined in claim 5 wherein W is used in place of at least part of the Mo content and Zr, Ti or HE is used in place of at least part of the content of elements from the group consisting of 6 to 9% Ta, 3 to 5% Cb and 3 to 6% V specified in step (a).

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Nonferrous Metals Or Alloys (AREA)
  • Powder Metallurgy (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US835201A 1969-06-20 1969-06-20 Monocarbide precipitation-strengthened nickel base alloys and method for producing same Expired - Lifetime US3649378A (en)

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JP (1) JPS4932405B1 (enrdf_load_stackoverflow)
AT (1) AT305660B (enrdf_load_stackoverflow)
BE (1) BE752288A (enrdf_load_stackoverflow)
CA (1) CA930573A (enrdf_load_stackoverflow)
DE (1) DE2029964A1 (enrdf_load_stackoverflow)
FR (1) FR2052859A5 (enrdf_load_stackoverflow)
GB (1) GB1321458A (enrdf_load_stackoverflow)
NL (1) NL7009043A (enrdf_load_stackoverflow)
NO (1) NO129534B (enrdf_load_stackoverflow)
SE (1) SE364736B (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3985582A (en) * 1973-07-30 1976-10-12 Office National D'etudes Et De Recherches Aerospatiales (O.N.E.R.A.) Process for the improvement of refractory composite materials comprising a matrix consisting of a superalloy and reinforcing fibers consisting of a metal carbide
US4089466A (en) * 1977-03-30 1978-05-16 Lomax Donald P Lining alloy for bimetallic cylinders
US4207098A (en) * 1978-01-09 1980-06-10 The International Nickel Co., Inc. Nickel-base superalloys
US6428637B1 (en) 1974-07-17 2002-08-06 General Electric Company Method for producing large tear-free and crack-free nickel base superalloy gas turbine buckets
CN109070207A (zh) * 2016-04-28 2018-12-21 住友电气工业株式会社 合金粉末、烧结体、制造合金粉末的方法以及制造烧结体的方法

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3985582A (en) * 1973-07-30 1976-10-12 Office National D'etudes Et De Recherches Aerospatiales (O.N.E.R.A.) Process for the improvement of refractory composite materials comprising a matrix consisting of a superalloy and reinforcing fibers consisting of a metal carbide
US6428637B1 (en) 1974-07-17 2002-08-06 General Electric Company Method for producing large tear-free and crack-free nickel base superalloy gas turbine buckets
US4089466A (en) * 1977-03-30 1978-05-16 Lomax Donald P Lining alloy for bimetallic cylinders
US4207098A (en) * 1978-01-09 1980-06-10 The International Nickel Co., Inc. Nickel-base superalloys
CN109070207A (zh) * 2016-04-28 2018-12-21 住友电气工业株式会社 合金粉末、烧结体、制造合金粉末的方法以及制造烧结体的方法
US11045872B2 (en) 2016-04-28 2021-06-29 Sumitomo Electric Industries, Ltd. Alloy powder, sintered material, method for producing alloy powder, and method for producing sintered material

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AT305660B (de) 1973-03-12
SE364736B (enrdf_load_stackoverflow) 1974-03-04
NL7009043A (enrdf_load_stackoverflow) 1970-12-22
BE752288A (fr) 1970-12-01
FR2052859A5 (enrdf_load_stackoverflow) 1971-04-09
DE2029964A1 (de) 1970-12-23
CA930573A (en) 1973-07-24
JPS4932405B1 (enrdf_load_stackoverflow) 1974-08-30
GB1321458A (en) 1973-06-27
NO129534B (enrdf_load_stackoverflow) 1974-04-22

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