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US3864809A - Process of producing by powder metallurgy techniques a ferritic hot forging of low flow stress - Google Patents

Process of producing by powder metallurgy techniques a ferritic hot forging of low flow stress Download PDF

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Publication number
US3864809A
US3864809A US345981A US34598173A US3864809A US 3864809 A US3864809 A US 3864809A US 345981 A US345981 A US 345981A US 34598173 A US34598173 A US 34598173A US 3864809 A US3864809 A US 3864809A
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United States
Prior art keywords
percent
hot forging
powder
preform
forging
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US345981A
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English (en)
Inventor
Stephen James Donachie
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Huntington Alloys Corp
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International Nickel Co Inc
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Publication date
Application filed by International Nickel Co Inc filed Critical International Nickel Co Inc
Priority to US345981A priority Critical patent/US3864809A/en
Priority to CA172,775A priority patent/CA987516A/en
Priority to JP48085051A priority patent/JPS49123104A/ja
Priority to US05/448,883 priority patent/US4049429A/en
Priority to GB1118074A priority patent/GB1469655A/en
Priority to FR7410499A priority patent/FR2230440A1/fr
Priority to NL7404219A priority patent/NL7404219A/xx
Priority to DE2414909A priority patent/DE2414909A1/de
Priority to BE142617A priority patent/BE813030A/xx
Priority to ES424762A priority patent/ES424762A1/es
Priority to IT49836/74A priority patent/IT1005890B/it
Application granted granted Critical
Publication of US3864809A publication Critical patent/US3864809A/en
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0264—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements the maximum content of each alloying element not exceeding 5%
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S72/00—Metal deforming
    • Y10S72/70—Deforming specified alloys or uncommon metal or bimetallic work

Definitions

  • powder metallurgy (often herein P/M) has continued to assume a more prominent position in many areas as a viable alternative to conventional melting-casting-working processing. This has been notably evident in respect of applications where the risks inherent in the uncertainties of segregation problems could not be entertained and, of course, in respect of those applications involving the production of intricately shaped components.
  • centages of nickel, copper, molybdenum, carbon, etc. can be forged at most dramatically reduced pressures and/or temperatures. It is considered that the flow stress of certain of such steels is so low as to be the virtual equivalent of pure iron at corresponding forging temperatures. These characteristics greatly promote improved die filling and bring about reduced die wear, lending to significant economic benefits.
  • the present invention contemplates the hot forging of age-hardenable ferritic steel powders which most advantageously contain about 0.7 to l or 1.25 percent nickel, about 1.4 to 2 or 2.25 percent copper, about 0.l5 to 0.35 percent molybdenum, up to 0.02 percent carbon, up to 0.05 or 0.1 percent silicon (if any), up to 0.15 percent manganese, the balance being essentially iron.
  • Forging temperatures as low as 1300F. can be used, yet the densities of the forgings produced are at full density without recourse to excessive pressures.
  • a proper balance in chemistry must be struck to assure obtaining a iferritic (body-centered-cubic) structure.
  • the alloying constituents should be correlated such that lthe Ac, critical temperature of the steels afford a substantially, if not completely, ferritic structure up to a jtemperature of 1400F. and most preferably to l550F., this to minimize the presence of the facecentered-cubic austenite.
  • the presence of austenite is not only unnecessary but undesirable since it impedes flow stress. It should preferably not exceed 2 or 3 percent by volume, although higher percentages might be tolerated, say up to less than 10 percent or possibly in some instances up to 20 percent.
  • alloying constituents should be balanced such that solid solution strengthening is maintained to a minimum during forging. Solid solution strengthening effects offset low flow stress.
  • the foregoing alloying ranges are designed to achieve these characteristics. However, departures therefrom can be made using the following guides.
  • Nickel is an austenite former, lowers Ac contributes to aged tensile strength and impact energy and while it can be as high as 1.5 percent such higher percentages tend to unnecessarily decrease Ac, and this renders it more difficult to achieve the desired ferritic structure and lower flow stresses.
  • the nickel level can extend down to 0.4 or 0.25 percent, but at the sacrifice of ,toughness and strength.
  • the element copper has but a moderate detracting influence with respect to the Ac, temperature. its main role is of imparting strength through precipitation hardening, although it does not appreciably contribute to solid solution strengthening during forging.
  • the copper content can be as low as about 0.75 percent, but in striving for optimum results it should be at least 1.5 percent. Not much is gained by copper percentages above 2 or 2.25 percent. A range of 1.5 to 1.8 percent is very beneficial.
  • Molybdenum enhances the intensity of the copper age hardening reaction and raises the critical temperatures; however, it should not exceed 0.6 percent. High levels can introduce a solid solution strengthening problem during forging at low temperatures. I have found, for example, that an amount of molybdenum slightly above 1 percent did significantly increase tensile strength. But this solid solution hardening was achieved at the expense of flow stress and impact strength. And on balance the gain in strength neither warranted the increase in flow stress nor the loss of impact resistance. Molybdenum is also deemed to resist embrittlement. A range of 0.1 to 0.4 percent is satisfactory with a range of about 0.15 or 0.2 percent to 0.25 or 0.3 percent being considered the most advantageous.
  • the subject steels are of the low carbon type even to the point of being carbon-free. Carbon confers strength, but at the same time raises flow stress and it is deemed that the fatigue ratio (ratio of fatigue limit to tensile strength) is also needlessly decreased as well as the ability of the steels to absorb impact energy. For special purposes where relatively poor properties would be acceptable, carbon up to 0.1 percent might be tolerated in a carefully balanced alloy, but as a practical matter it should not exceed 0.03 to 0.05 percent. It is difficult to avoid the presence of carbon altogether, but notwithstanding this an upper level of 0.02 percent should be maintained.
  • Silicon is a ferrite stabilizer and contributes to strength through solid solution hardening. It is a strong oxide former and detracts from toughness. Thus, it should be held to impurity levels, if any. Up to 0.3 percent can probably be tolerated where a lesser combination of properties can be accepted. Even here it should be held to less than 0.2 percent if at all possible.
  • boron can be employed, though it need not exceed 0.02 or 0.01 percent.
  • Aluminum is unnecessary and should be controlled to a minimum, say 0.1 percent or lower.
  • Phosphorus and sulfur should be held to not more than 0.04 percent, preferably to not more than 0.02 percent, each. Oxygen will be present and should be maintained, for reasons given above, to
  • prealloyed powder This can be accomplished through atomization in which a liquid melt is converted to powder by using air, inert gas, water, etc., to bring about atomization. Water atomization is considered appropriate since it is commonly employed, is relatively inexpensive, and provides particles of irregular shape. Prealloying and atomization also provide for small particle size and grain size.
  • the alloy powders should not exceed about 500 or 600 microns (including oxide film), preferably being less than 250-300 microns.
  • the prealloyed powder particles are thereafter compacted to a preform, the shape of which will be often governed by the shape of the final product.
  • the preform is heated to obtain the desired ferritic structure whereupon it is forged to shape and to full or nearly full density.
  • an appropriate lubricant can be added to the powder before pressing to the preform.
  • the preform can, indeed should, be heated (sintered) prior to forging in accordance with usual practice.
  • the product may, if desired and depending on composition, be further processed, e.g., machined, prior to aging.
  • Steels in accordance herewith should be aged at about 900 to 1050F., e.g., 925 to 1000F., for about 1 to 5 hours. Above about 1000F. the alloys tend to overage, i.e., lose strength and gain in toughness.
  • Various steels, A, 1 and B in Table l were prepared using electrolytic iron, nickel shot, ferromolybdenum percent Mo) and copper shot.
  • the melt procedure involved forming an initial charge (45 kg) of iron, nickel and copper, heating to 3000F., adding the ferromolybdenum, and pouring at 3000F. into a heated tundish.
  • the molten metal was water atomized at the bottom orifice of the tundish, the powder thereafter being dried and reduced at 1800F. (to obtain a good oxygen reduction) in a cracked ammonia atmosphere (dewpoint about minus 50F.).
  • the powder was pulverized and heated for one hour at 1400F. (to remove strain from pulverization) under a cracked ammonia atmosphere.
  • the powders were admixed with a lubricant before compaction, in this case 0.5 percent by weight of Acrawax.
  • the powders were blended with carbon, poured into a die and compressed cold. These green compacts were heated to 1200F. in cracked ammonia to dispel the Acrawax and cooled to ambient temperature. They were reheated to 2050F., again in cracked ammonia, and held thereat for one-half hour to effect sintering (approximately 6.79 gm/cm density).
  • Alloy A shows that percent carbon addition, (b) AlSl 1050 (Fe 0.5 C) obtaining a ferrite structure per se is not necessarily an and Alloy A. answer. in this particular instance the high molybde- against atheoretical maximum density of 7.84 -7.86, num content introduced excessive solid solution Alloy 1 had a density of 7.78 at l500F. versus only strengthening. This is in marked contrast with Alloy l, 7.55, 7.58, and 7.63 for the 46F2, 4600 and Alloy A an alloy within the invention. It will also be observed steels, respectively.
  • the ton force was Mechanical properties were determined in respect of deliberately selected so as to determine the ease by Alloys A and 1. In this connection, a preform specimen 30 which full density, if possible, could be reached.
  • a steel designated ing and tempering is obviated and since minimum muchining is one of the principal economic advantages of hot forging-preforms, no machining is required to correct quenched induced distortion, an otherwise severe drawback. This provides for retention of closer part tolerances.
  • the low oxygen content and clean structures greatly contribute to the overall combination of properties. Simply heating, e.g., sintering at 1900 to 2100F. in dissociated ammonia or equivalent is all that is required. Because the concentration of strong oxide formers is low in the subject steels, such a treatment results in very low oxygen contents, e.g., 0.01 or 0.02 percent and less. Of course, the oxygen content is low prior to the burn-off treatment, e.g, 0.2 percent or less due to initial low oxide content. Fatigue and impact resistance particularly benefit from such low oxygen clean forged structures. Such factors enable the steels to compete as a structural material at the given strength levels.
  • compositions within the invention have been prepared by melting-casting-working procedures and exhibit useful properties for mill products though their structures are not as clean and they contain higher oxygen levels.
  • the process of producing by powder metallurgy techniques a steel hot forging wherein die wear is reduced comprises forming a preform from a ferritic alloy steel powder, and hot forging said preform at a temperature not greater than about 1550F., said powder consisting essentially of about 0.7 to about 1 percent nickel, 1.4 to 2 percent copper, 0. l 5 to 0.35 percent molybdenum, up to 0.02 percent carbon, up to 0.1 percent silicon, up to 0.15 percent manganese, the balance essentially iron, the forging being able to be carried out at such temperature largely by reason of the low flow stress characteristics of the steel composition.
  • hot forging temperature is from about 1400F. to less than about 1550F.
  • a steel hot forging wherein die wear is reduced which process comprises forming a preform from a ferritic alloy steel powder, and hot forging said preform at a temperature not greater than about 1550F., said powder consisting essentially of from 0.25 to less than 1.5 percent nickel, 0.75 to 2.25 percent copper, 0.1 to 0.6 percent molybdenum, up to 0.5 percent manganese, up to 0.3 percent silicon, up to 0.5 percent chromium, up to 0.02 percent boron, up to 0.05 percent carbon and the balance essentially iron.

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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)
US345981A 1973-03-29 1973-03-29 Process of producing by powder metallurgy techniques a ferritic hot forging of low flow stress Expired - Lifetime US3864809A (en)

Priority Applications (11)

Application Number Priority Date Filing Date Title
US345981A US3864809A (en) 1973-03-29 1973-03-29 Process of producing by powder metallurgy techniques a ferritic hot forging of low flow stress
CA172,775A CA987516A (en) 1973-03-29 1973-05-30 Ferritic alloys of low flow stress for p/m forgings
JP48085051A JPS49123104A (ja) 1973-03-29 1973-07-30
US05/448,883 US4049429A (en) 1973-03-29 1974-03-07 Ferritic alloys of low flow stress for P/M forgings
GB1118074A GB1469655A (en) 1973-03-29 1974-03-13 Powder metallurgy alloys
FR7410499A FR2230440A1 (ja) 1973-03-29 1974-03-27
NL7404219A NL7404219A (ja) 1973-03-29 1974-03-28
DE2414909A DE2414909A1 (de) 1973-03-29 1974-03-28 Stahlpulver
BE142617A BE813030A (fr) 1973-03-29 1974-03-29 Alliages pulverulents et leur utilisation
ES424762A ES424762A1 (es) 1973-03-29 1974-03-29 Un procedimiento para fabricar un acero pulvimetalurgico.
IT49836/74A IT1005890B (it) 1973-03-29 1974-03-29 Procedimento e composizione in polvere per produrre oggetti di acciaio

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Application Number Priority Date Filing Date Title
US345981A US3864809A (en) 1973-03-29 1973-03-29 Process of producing by powder metallurgy techniques a ferritic hot forging of low flow stress

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US05/448,883 Division US4049429A (en) 1973-03-29 1974-03-07 Ferritic alloys of low flow stress for P/M forgings

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US (1) US3864809A (ja)
JP (1) JPS49123104A (ja)
BE (1) BE813030A (ja)
CA (1) CA987516A (ja)
DE (1) DE2414909A1 (ja)
ES (1) ES424762A1 (ja)
FR (1) FR2230440A1 (ja)
GB (1) GB1469655A (ja)
IT (1) IT1005890B (ja)
NL (1) NL7404219A (ja)

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4077108A (en) * 1975-03-21 1978-03-07 Ugine Aciers Process for producing dense machinable alloys from particulate scrap
WO1979000833A1 (en) * 1978-03-24 1979-10-18 Iit Res Inst Method of and apparatus for hot pressing particulates
US4923674A (en) * 1988-02-27 1990-05-08 Sintermetallwerk Krebsoge Gmbh Method of producing powder forged components
US5594187A (en) * 1996-04-02 1997-01-14 Chrysler Corporation Forged powder metal connecting rod with stress riser crease formed in side thrust face
US5613182A (en) * 1996-04-02 1997-03-18 Chrysler Corporation Method of manufacturing a powder metal connecting rod with stress riser crease formed in the side face
US6770114B2 (en) * 2001-12-19 2004-08-03 Honeywell International Inc. Densified sintered powder and method
US20090129961A1 (en) * 2007-11-15 2009-05-21 Viper Technologies Llc, D.B.A. Thortex, Inc. Metal injection molding methods and feedstocks
US8124187B2 (en) 2009-09-08 2012-02-28 Viper Technologies Methods of forming porous coatings on substrates
US20180126649A1 (en) 2016-11-07 2018-05-10 Velo3D, Inc. Gas flow in three-dimensional printing
US20180186080A1 (en) * 2017-01-05 2018-07-05 Velo3D, Inc. Optics in three-dimensional printing
US10144176B1 (en) 2018-01-15 2018-12-04 Velo3D, Inc. Three-dimensional printing systems and methods of their use
US10183330B2 (en) 2015-12-10 2019-01-22 Vel03D, Inc. Skillful three-dimensional printing
US10195693B2 (en) 2014-06-20 2019-02-05 Vel03D, Inc. Apparatuses, systems and methods for three-dimensional printing
US10252336B2 (en) 2016-06-29 2019-04-09 Velo3D, Inc. Three-dimensional printing and three-dimensional printers
US10252335B2 (en) 2016-02-18 2019-04-09 Vel03D, Inc. Accurate three-dimensional printing
US10272525B1 (en) 2017-12-27 2019-04-30 Velo3D, Inc. Three-dimensional printing systems and methods of their use
US10315252B2 (en) 2017-03-02 2019-06-11 Velo3D, Inc. Three-dimensional printing of three-dimensional objects
US10357957B2 (en) 2015-11-06 2019-07-23 Velo3D, Inc. Adept three-dimensional printing
US10449696B2 (en) 2017-03-28 2019-10-22 Velo3D, Inc. Material manipulation in three-dimensional printing
CN110434324A (zh) * 2019-07-10 2019-11-12 西安交通大学 一种高性能粉末锻造合金材料及其制备方法
US11691343B2 (en) 2016-06-29 2023-07-04 Velo3D, Inc. Three-dimensional printing and three-dimensional printers
US11999110B2 (en) 2019-07-26 2024-06-04 Velo3D, Inc. Quality assurance in formation of three-dimensional objects
US12070907B2 (en) 2016-09-30 2024-08-27 Velo3D Three-dimensional objects and their formation

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4170474A (en) * 1978-10-23 1979-10-09 Pitney-Bowes Powder metal composition
JPS57164901A (en) * 1981-02-24 1982-10-09 Sumitomo Metal Ind Ltd Low alloy steel powder of superior compressibility, moldability and hardenability
JPS6075501A (ja) * 1983-09-29 1985-04-27 Kawasaki Steel Corp 高強度焼結部品用の合金鋼粉

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2402135A (en) * 1944-12-26 1946-06-18 Inland Steel Co Alloy steel
US3132025A (en) * 1962-12-03 1964-05-05 Int Nickel Co Alloy steel
US3303061A (en) * 1964-05-07 1967-02-07 American Metal Climax Inc Bainitic iron alloys
US3720512A (en) * 1970-05-06 1973-03-13 Mitsubishi Metal Mining Co Ltd Closed die forging method of making high density ferrous sintered alloys
US3795129A (en) * 1971-10-07 1974-03-05 S Goto Method of forging sintered articles of high density

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2402135A (en) * 1944-12-26 1946-06-18 Inland Steel Co Alloy steel
US3132025A (en) * 1962-12-03 1964-05-05 Int Nickel Co Alloy steel
US3303061A (en) * 1964-05-07 1967-02-07 American Metal Climax Inc Bainitic iron alloys
US3720512A (en) * 1970-05-06 1973-03-13 Mitsubishi Metal Mining Co Ltd Closed die forging method of making high density ferrous sintered alloys
US3795129A (en) * 1971-10-07 1974-03-05 S Goto Method of forging sintered articles of high density

Cited By (39)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4077108A (en) * 1975-03-21 1978-03-07 Ugine Aciers Process for producing dense machinable alloys from particulate scrap
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
US4923674A (en) * 1988-02-27 1990-05-08 Sintermetallwerk Krebsoge Gmbh Method of producing powder forged components
US5594187A (en) * 1996-04-02 1997-01-14 Chrysler Corporation Forged powder metal connecting rod with stress riser crease formed in side thrust face
US5613182A (en) * 1996-04-02 1997-03-18 Chrysler Corporation Method of manufacturing a powder metal connecting rod with stress riser crease formed in the side face
US6770114B2 (en) * 2001-12-19 2004-08-03 Honeywell International Inc. Densified sintered powder and method
US20090129961A1 (en) * 2007-11-15 2009-05-21 Viper Technologies Llc, D.B.A. Thortex, Inc. Metal injection molding methods and feedstocks
US7883662B2 (en) 2007-11-15 2011-02-08 Viper Technologies Metal injection molding methods and feedstocks
US8124187B2 (en) 2009-09-08 2012-02-28 Viper Technologies Methods of forming porous coatings on substrates
US10507549B2 (en) 2014-06-20 2019-12-17 Velo3D, Inc. Apparatuses, systems and methods for three-dimensional printing
US10493564B2 (en) 2014-06-20 2019-12-03 Velo3D, Inc. Apparatuses, systems and methods for three-dimensional printing
US10195693B2 (en) 2014-06-20 2019-02-05 Vel03D, Inc. Apparatuses, systems and methods for three-dimensional printing
US10357957B2 (en) 2015-11-06 2019-07-23 Velo3D, Inc. Adept three-dimensional printing
US10688722B2 (en) 2015-12-10 2020-06-23 Velo3D, Inc. Skillful three-dimensional printing
US10207454B2 (en) 2015-12-10 2019-02-19 Velo3D, Inc. Systems for three-dimensional printing
US10183330B2 (en) 2015-12-10 2019-01-22 Vel03D, Inc. Skillful three-dimensional printing
US10286603B2 (en) 2015-12-10 2019-05-14 Velo3D, Inc. Skillful three-dimensional printing
US10434573B2 (en) 2016-02-18 2019-10-08 Velo3D, Inc. Accurate three-dimensional printing
US10252335B2 (en) 2016-02-18 2019-04-09 Vel03D, Inc. Accurate three-dimensional printing
US10259044B2 (en) 2016-06-29 2019-04-16 Velo3D, Inc. Three-dimensional printing and three-dimensional printers
US11691343B2 (en) 2016-06-29 2023-07-04 Velo3D, Inc. Three-dimensional printing and three-dimensional printers
US10286452B2 (en) 2016-06-29 2019-05-14 Velo3D, Inc. Three-dimensional printing and three-dimensional printers
US10252336B2 (en) 2016-06-29 2019-04-09 Velo3D, Inc. Three-dimensional printing and three-dimensional printers
US12070907B2 (en) 2016-09-30 2024-08-27 Velo3D Three-dimensional objects and their formation
US20180126649A1 (en) 2016-11-07 2018-05-10 Velo3D, Inc. Gas flow in three-dimensional printing
US10661341B2 (en) 2016-11-07 2020-05-26 Velo3D, Inc. Gas flow in three-dimensional printing
US20180186080A1 (en) * 2017-01-05 2018-07-05 Velo3D, Inc. Optics in three-dimensional printing
US10611092B2 (en) 2017-01-05 2020-04-07 Velo3D, Inc. Optics in three-dimensional printing
US10369629B2 (en) 2017-03-02 2019-08-06 Veo3D, Inc. Three-dimensional printing of three-dimensional objects
US10442003B2 (en) 2017-03-02 2019-10-15 Velo3D, Inc. Three-dimensional printing of three-dimensional objects
US10888925B2 (en) 2017-03-02 2021-01-12 Velo3D, Inc. Three-dimensional printing of three-dimensional objects
US10357829B2 (en) 2017-03-02 2019-07-23 Velo3D, Inc. Three-dimensional printing of three-dimensional objects
US10315252B2 (en) 2017-03-02 2019-06-11 Velo3D, Inc. Three-dimensional printing of three-dimensional objects
US10449696B2 (en) 2017-03-28 2019-10-22 Velo3D, Inc. Material manipulation in three-dimensional printing
US10272525B1 (en) 2017-12-27 2019-04-30 Velo3D, Inc. Three-dimensional printing systems and methods of their use
US10144176B1 (en) 2018-01-15 2018-12-04 Velo3D, Inc. Three-dimensional printing systems and methods of their use
CN110434324A (zh) * 2019-07-10 2019-11-12 西安交通大学 一种高性能粉末锻造合金材料及其制备方法
US11999110B2 (en) 2019-07-26 2024-06-04 Velo3D, Inc. Quality assurance in formation of three-dimensional objects

Also Published As

Publication number Publication date
NL7404219A (ja) 1974-10-01
FR2230440A1 (ja) 1974-12-20
CA987516A (en) 1976-04-20
GB1469655A (en) 1977-04-06
ES424762A1 (es) 1976-06-16
DE2414909A1 (de) 1974-10-03
IT1005890B (it) 1976-09-30
BE813030A (fr) 1974-09-30
JPS49123104A (ja) 1974-11-25

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