US3787205A - Forging metal powders - Google Patents

Forging metal powders Download PDF

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Publication number
US3787205A
US3787205A US00257793A US3787205DA US3787205A US 3787205 A US3787205 A US 3787205A US 00257793 A US00257793 A US 00257793A US 3787205D A US3787205D A US 3787205DA US 3787205 A US3787205 A US 3787205A
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percent
alloy
accordance
forging
nickel
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US00257793A
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English (en)
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N Church
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Huntington Alloys Corp
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International Nickel Co Inc
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/17—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces by forging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy

Definitions

  • powder metallurgy has for some time played a prominent role in the production of a number of useful structural components. This has been particularly evident in respect of products not readily responsive to the more conventional meltingcasting-working type processing,'notably the production of intricately shaped products, certain refractory metals and alloys, various dispersion hardened materials, etc.
  • a primary objective of the present invention is to facilitate or otherwide advance powder forging in terms of processing technique and/or providing particularly useful forged prodnets.
  • the present invention involves the forging of powder alloys characterized at the temperature of forging by a microstructure in which the alloy powder particles contain at least two metallic phases, e.g., austenite and ferrite in the case of stainless steels or alpha and beta in the case of copper-zinc alloys, which mutually coact such that grain growth is retarded during recrystallization.
  • each of the phases is present in a volume percentage of at least about percent with their respective grains not exceeding a grain size of about ASTM 10 on average, the grain size most advantageously being not greater than about ASTM 12.
  • any one or more of a number of benefits follow, e.g., improved die filling, lower forging loads for a given configuration, less oxidation, the likelihood of decreased die wear, distortion, or breakage, reduced cost, etc.
  • lower flow stresses less resistance to flow
  • a significantly lower forging temperature can be used as opposed to the necessity of using one much higher.
  • the volume percentage of one or more such phases may be as low as 4 percent or 5 percent, (it being understood that one other such phases constitutes essentially the balance), in striving for an overall good combination of physical and/or mechanical properties, at least 10 percent, and most preferably about 15 percent or 20 percent or more, of at least two such phases should be present at the forging temperature.
  • the microstructures will, in most instances, be comprised of but two phases at the forging temperature. Thus, if one were present in an amount of but 1 percent or 2 percent, this would be unsuitable since, inter alia, there would be an insufficient percentage of the low volume phase to prevent undesirable grain growth in the other and, depending on composition, a higher flow strength than desired could obtain.
  • the grains of the phases at the temperature of forging should be at least about ASTM grain size 10 or finer.
  • the grains can be larger, e.g., ASTM 8, but generally at the expense of some mechanical or physical property.
  • pre-alloyed powder While elemental powders may be blended and sintered to the desired composition, it is deemed preferable to use pre-alloyed powder. This can, for example, be accomplished through atomization in which a liquid melt of desired composition is formed and directly converted to powder by using air, steam, inert gas, vacuum or water to bring about atomization. Water atomization, with or without an inert gaseous stream, is considered appropriate since it is commonly employed and is relatively inexpensive. Prealloying and atomization also provide for small particle size and grain size. Moreover, it is preferred that the particles as alloyed be of irregular shape as opposed to, say, spherical. This enhances particle interlocking.
  • the alloy powders should not exceed about 500 microns, (including oxide film) preferably being less than 275 microns, an advantageous powder mix being one containing not more than about 25 percent of powder less than about 40 microns, the remainder being up to 225 or 275 microns.
  • the surface of the particles is substantially, if not completely, comprised of an oxide film but this is beneficial in accordance herewith. This film inhibits grain growth within each particle as well as inhibiting growth across interparticle boundaries.
  • oxygen level should not exceed about 0.15 percent or 0.25 percent and the oxide film should be less than about 5 or 10 microns thick.
  • the prealloyed powder particles are thereafter compacted to a preform, the shape of which will often, though not necessarily, depend on the shape of the final product.
  • the prealloyed preform is heated to obtain the desired multiplex microstructure whereupon it is forged to shape, and full or nearly full density.
  • an appropriate lubricant can be added to the prealloy powder before pressing to the preform.
  • the preform can be heated (sintered) prior to forging in accordance with usual practice.
  • the product may, if desired and depending on composition, be further treated, e.g., ma-
  • preconditioning treatments are unnecessary as a prerequisite to obtaining a fine grain.
  • prior art wrought alloy processing it is common to significantly cold work a given alloy at room temperature and then heat into a plural phase region above the recrystallizationtemperature or work the alloy while cooling down to and into such region.
  • This preconditioning is largely responsible for the fine grain; otherwise, a coarse grain results.
  • Forging as contemplated herein involves virtually an isothermal operation during which continuous recrystallization takes place. This contributes together with other aspects such as atomization to maintaining a fine grain structure but without need of preconditioning.
  • a melt of a nickel-base alloy nominally containing 37 percent chromium, 18 percent iron, 0.5 percent titanium, 0.05 percent carbon, 0.5 percent silicon, and the balance essentially nickel and impurities is prepared using conventional melt processing; The use of relatively pure materials is preferred together with vacuum melting.
  • the melt is then atomized using gas, vacuum or high pressure water atomization to produce powder particles with sizes ranging from "-40 to 325 mesh. Each powder particle has substantially the composition of the parent alloy.
  • High pressure water atomization is excellent for producing powder because it'is relatively inexpensive, produces an irregular particle shape which is readily compactable and is capable of producing powder with reasonably low oxygen content, e.g., less than about 0.15 percent oxygen by weight.
  • the resulting powders can be compacted into preforms (using a binder, if necessary, which is burned off by heating to a moderate temperature, e.g., 1,000 F), and then heated to a temperature as low as 1,800 F and up to about 2,200 F, although the temperature preferable is from 1,900-2,l00 F.
  • a moderate temperature e.g., 1,000 F
  • the preforms may be held for some time at this temperature to provide some sintering of the particles or they may be placed into the forging die as soon as they reach the forging temperature. This forging step will provide densification of the preform and metal flow to fill the die cavity, to produce an accurate essentially completed product with nearly 100 percent density and mechanical and corrosion properties similar to those expected of the alloy it were in the wrought condition.
  • each powder particle will consist of a rapidly quenched gamma (face-centered-cubic, nickel-chromium solid solution with or without iron) phase.
  • gamma face-centered-cubic, nickel-chromium solid solution with or without iron
  • fine particles of alpha phase body-centered-cubic, chromium-rich
  • the alloy may be forged with various benefits. It is considered low flow stress will result at least in part from the dispersion of the lower strength (at 1,800 2.200 F.) alpha phase in the gamma matrix. This should enhance die filling, require less forging load, etc. The resulting forged product will have a desirable fine-grained, two-phase structure.
  • Illustrative of those systems are'nickel-chromium-iron alloys of the type described in the above example or a high chromium (24-26 percent) nickel-containing (5-7 percent) stainless steels.
  • a high chromium (24-26 percent) nickel-containing (5-7 percent) stainless steels There are systems in which the higher forging temperatures bring on the lowest flow stresses. A good balance can nonetheless be struck and a fine grained product of excellent strength, for example, can be derived, although the forging temperature is on the high side.
  • a suitable powder stainless steel contains about 15 percent to 35 percent chromium; up to about 12 percent, e.g., 2 percent to 10 percent nickel; up to 1 percent or 1.5 percent titanium; up to 1 percent vanadium; up to 0.5 percent and preferably from 0.025 percent to 0.15 percent or 0.25 percent, oxygen; up to about 0.25 percent carbon, up to 1 percent silicon, up to 1 percent manganese, up to 3 percent or 4 percent molybdenum, up to 2 percent cobalt, up to 2.5 percent or 3 percent copper.
  • Such steels can be forged at l,700 to 2,000 F but a lower forging temperature of 1,750 F. to l,850 F. is preferred, the alloy structure being comprised of a ferritic matrix throughout which austenite is dispersed.
  • a particularly satisfactory stainless steel contains from 25 percent to 31 percent chromium and from 5.5 percent to 7 percent nickel.
  • Other high chromium (10 percent or more) iron-base alloys can be employed.
  • a suitable nickel-chromium alloy contains from about 25 percent to 50 percent, e.g., 32 percent to 40 percent, chromium; up to 25 percent, e.g., about 14 percent to 22 percent,iron; up to about 1 percent, e.g.,
  • the alloy used in the above described example responds to this compositional range and the preferred forging temperature is from l,900 to 2,100 F.
  • Multiplex copper-base alloys include those containing from about 8 percent to 14 percent aluminum with or without up to 6 percent, e.g., 3 percent to 5 percent iron.
  • Other illustrative copper alloys are those formed using substantial amounts of zinc, e. g., from 35 percent to 50 percent zinc, or magnesium in percentages from 8 percent to 12 percent.
  • a particularly suitable nickelzinc-copper alloy contains from 4 percent to 71 percent, preferably 8 percent to 40 percent nickel, 29 percent to 40 percent zinc, balance copper and small amounts of other elements. These latter alloys can be forged from 900 to 1,050" F. where they have an alpha (face-centered-cubic) matrix with a dispersed beta phase (body-centered-cubic or body-centeredtetragonal).
  • the straight 38 percent to 50 percent 'zinc, balance essentially copper also have a face-centeredcubic alpha and body-centered-cubic beta (the higher temperature phase) structure.
  • a suitable forging range is from 850 to l,200 F.
  • Appropriate aluminum-base powder alloys can contain about 30 percent to 35 percent copper (forgeable at about 430 to 540 C.) or 8 percent to 15 percent silicon with up to 6 percent copper (can be forged from about 475 to 525 C.).
  • the aluminum-copper structure is composed of an equiaxed aggregate of an aluminum solid solution and CuAl
  • magnesium powder alloys they may be comprised of from percent to percent nickel,(forgeable at 425 to 475 C.) or from 27 percent to 33 percent copper (also forgeable at 425 475 C.) or from percent to 35 percent aluminum. Alloys having from 4 percent to 8 percent zinc, zirconium up to 1 percent, e.g., 0.4 percent to 0.8 percent, balance essentially magnesium can be employed.
  • a titanium alloy consisting of from 4.percent to 8 percent aluminum, 2 percent to 6 percent vanadium, balance essentially titanium and impurities, an alloy forgeable within the range of 875 to 1,000 C. and having an alpha plus beta structure, is also within the invention.
  • Illustrative zinc alloys include those with alu minum in varying percentages such as 0.3 percent to 0.7 percent; 3 percent to 8 percent; 20 percent to 25 percent; and from 37 percent to 42 percent. These four groups of alloys can be forged at about 15 to 25 C., 200 to 300 C., 210 to 260 C. and about 240 to 260 C., respectively.
  • the invention is deemed useful for producing a variety of forged products, including pump gears, pipe and valve fittings, diffusion vanes, grooved pulleys, various surgical instruments, musical instrument keys, etc.
  • the microstructures may contain one or more transformation products of at least one of the metallic phases.
  • the improvement of facilitating the forging process in terms of reduced forging pressure and/or temperature as a result of achieving lower flow stress conditions during forging while providing for a forged product having good mechanical properties which comprises, hot forging an alloy powder preform of an alloy base selected from the group consisting of nickel, copper, aluminum, titanium, zinc, magnesium, zirconium and iron containing above about 10 percent chromium at a temperature at which the alloy is characterized by a microstructure consisting essentially of at least two metallic phases with each of the phases being present in a volume percentage of at least about 10 percent with the average grain size of each of the phases being at least about ASTM 10, the volume of the phases and grain sizes thereof mutually coacting to retard grain growth during recrystallization.
  • an alloy powder preform of an alloy base selected from the group consisting of nickel, copper, aluminum, titanium, zinc, magnesium, zirconium and iron containing above about 10 percent chromium at a temperature at which the alloy is characterized by a microstructure consisting essentially of at least two metallic phases with
  • the stainless steel contains from 15 to 35 percent chromium, about 2 to 12 percent nickel, about 0.025 to 0.25 percent oxygen, up to 0.25 percent carbon, up to 1.5 percent titanium, up to 1 percent vanadium, up to 1 percent each of silicon and manganese, up to 4 percent molybdenum, up to 2 percent cobalt, up to 3 percent copper, the balance being essentially iron.
  • the alloy is a nickel-chromium alloy having from 25 to 50 percent chromium, 14 to 22 percent iron, up to 1 percent titanium, about 0.025 to 0.25 percent oxygen, carbon up to about 0.1 percent, up to 1 percent silicon, up to 1 percent manganese, and the balance essential nickel.
  • the copper-base alloy contains up to 6 percent iron and one metal from the group consisting of zinc and aluminum, the zinc being from 35 to 50 percent and the aluminum being from 8 to 14 percent.
  • alloy powders used in forming the preform are of a particle size not greater than about 275 microns with their outer surfaces being substantially enveloped by an oxide film not greater than about 10 microns in thickness, the particles being of irregular shape.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Powder Metallurgy (AREA)
  • Forging (AREA)
US00257793A 1972-05-30 1972-05-30 Forging metal powders Expired - Lifetime US3787205A (en)

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Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3897618A (en) * 1972-03-27 1975-08-05 Int Nickel Co Powder metallurgy forging
WO1979000833A1 (en) * 1978-03-24 1979-10-18 Iit Res Inst Method of and apparatus for hot pressing particulates
USRE30855E (en) * 1978-10-23 1982-01-26 Pitney Bowes Inc. Powder metal composition
US4484644A (en) * 1980-09-02 1984-11-27 Ingersoll-Rand Company Sintered and forged article, and method of forming same
US4518442A (en) * 1981-11-27 1985-05-21 United Technologies Corporation Method of producing columnar crystal superalloy material with controlled orientation and product
US4609526A (en) * 1984-05-14 1986-09-02 Crucible Materials Corporation Method for compacting alloy powder
DE3817350A1 (de) * 1987-05-23 1988-12-22 Sumitomo Electric Industries Verfahren zur herstellung von spiralfoermigen teilen sowie verfahren zur herstellung einer aluminiumpulverschmiedelegierung
US4919243A (en) * 1987-03-23 1990-04-24 Dana Corporation Clutch brake having segmented cover surfaces
US5110542A (en) * 1991-03-04 1992-05-05 Vital Force, Inc. Rapid densification of materials
US5199971A (en) * 1988-12-19 1993-04-06 Sumitomo Electric Industries, Ltd. Parts for use in rotary gear pump
US6223976B1 (en) * 1997-09-18 2001-05-01 Societe Nationale d'Etude et de Construction de Moteurs d'Aviation “SNECMA” Process for the assembly or refacing of titanium aluminide articles by diffusion brazing
US20040013558A1 (en) * 2002-07-17 2004-01-22 Kabushiki Kaisha Toyota Chuo Kenkyusho Green compact and process for compacting the same, metallic sintered body and process for producing the same, worked component part and method of working
US20040123697A1 (en) * 2002-10-22 2004-07-01 Mikhail Kejzelman Method of preparing iron-based components
CN111902556A (zh) * 2018-03-26 2020-11-06 杰富意钢铁株式会社 粉末冶金用合金钢粉及粉末冶金用铁基混合粉末

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2809891A (en) * 1954-10-12 1957-10-15 Aluminum Co Of America Method of making articles from aluminous metal powder
US3702791A (en) * 1970-04-20 1972-11-14 Nasa Method of forming superalloys

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2809891A (en) * 1954-10-12 1957-10-15 Aluminum Co Of America Method of making articles from aluminous metal powder
US3702791A (en) * 1970-04-20 1972-11-14 Nasa Method of forming superalloys

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Hirschorn, J. S. et al., The Forging of Powder Metallurgy Preforms, In Metal Forming, 37(II), p. 320 327, Nov. 1970, TN1.M36. *

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3897618A (en) * 1972-03-27 1975-08-05 Int Nickel Co Powder metallurgy forging
WO1979000833A1 (en) * 1978-03-24 1979-10-18 Iit Res Inst Method of and apparatus for hot pressing particulates
US4244738A (en) * 1978-03-24 1981-01-13 Samuel Storchheim Method of and apparatus for hot pressing particulates
USRE30855E (en) * 1978-10-23 1982-01-26 Pitney Bowes Inc. Powder metal composition
US4484644A (en) * 1980-09-02 1984-11-27 Ingersoll-Rand Company Sintered and forged article, and method of forming same
US4518442A (en) * 1981-11-27 1985-05-21 United Technologies Corporation Method of producing columnar crystal superalloy material with controlled orientation and product
US4609526A (en) * 1984-05-14 1986-09-02 Crucible Materials Corporation Method for compacting alloy powder
US4919243A (en) * 1987-03-23 1990-04-24 Dana Corporation Clutch brake having segmented cover surfaces
DE3817350A1 (de) * 1987-05-23 1988-12-22 Sumitomo Electric Industries Verfahren zur herstellung von spiralfoermigen teilen sowie verfahren zur herstellung einer aluminiumpulverschmiedelegierung
US5199971A (en) * 1988-12-19 1993-04-06 Sumitomo Electric Industries, Ltd. Parts for use in rotary gear pump
US5110542A (en) * 1991-03-04 1992-05-05 Vital Force, Inc. Rapid densification of materials
US6223976B1 (en) * 1997-09-18 2001-05-01 Societe Nationale d'Etude et de Construction de Moteurs d'Aviation “SNECMA” Process for the assembly or refacing of titanium aluminide articles by diffusion brazing
US20040013558A1 (en) * 2002-07-17 2004-01-22 Kabushiki Kaisha Toyota Chuo Kenkyusho Green compact and process for compacting the same, metallic sintered body and process for producing the same, worked component part and method of working
US20040123697A1 (en) * 2002-10-22 2004-07-01 Mikhail Kejzelman Method of preparing iron-based components
US7585459B2 (en) * 2002-10-22 2009-09-08 Höganäs Ab Method of preparing iron-based components
CN111902556A (zh) * 2018-03-26 2020-11-06 杰富意钢铁株式会社 粉末冶金用合金钢粉及粉末冶金用铁基混合粉末
CN111902556B (zh) * 2018-03-26 2021-11-19 杰富意钢铁株式会社 粉末冶金用合金钢粉及粉末冶金用铁基混合粉末
US11236411B2 (en) 2018-03-26 2022-02-01 Jfe Steel Corporation Alloyed steel powder for powder metallurgy and iron-based mixed powder for powder metallurgy

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Publication number Publication date
JPS4942508A (cs) 1974-04-22
CA990977A (en) 1976-06-15

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