EP2818264A1 - Procédé de fusion d'une partie d'alliage - Google Patents

Procédé de fusion d'une partie d'alliage Download PDF

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Publication number
EP2818264A1
EP2818264A1 EP13382238.7A EP13382238A EP2818264A1 EP 2818264 A1 EP2818264 A1 EP 2818264A1 EP 13382238 A EP13382238 A EP 13382238A EP 2818264 A1 EP2818264 A1 EP 2818264A1
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EP
European Patent Office
Prior art keywords
mold
alloy
melting
process according
cooling
Prior art date
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.)
Withdrawn
Application number
EP13382238.7A
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German (de)
English (en)
Inventor
Iñaki Vicario Markiegi
Ignacio Dominguez Barrios
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Precicast Bilbao SA
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Precicast Bilbao SA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Precicast Bilbao SA filed Critical Precicast Bilbao SA
Priority to EP13382238.7A priority Critical patent/EP2818264A1/fr
Publication of EP2818264A1 publication Critical patent/EP2818264A1/fr
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
    • B22D21/02—Casting exceedingly oxidisable non-ferrous metals, e.g. in inert atmosphere
    • B22D21/025—Casting heavy metals with high melting point, i.e. 1000 - 1600 degrees C, e.g. Co 1490 degrees C, Ni 1450 degrees C, Mn 1240 degrees C, Cu 1083 degrees C

Definitions

  • the present invention refers to lost-wax melting methods ( investment casting ), a manufacturing technology for Nickel and Cobalt based superalloy parts, mainly intended for the aviation industry.
  • Lost-wax ( investment casting ) melting methods are applied to the manufacture of Nickel and Cobalt based superalloy parts, mainly intended for the aviation industry. These methods entail various processes, amongst which the melting process is the fundamental core process, given that this is when the metal is melted and is introduced into the interior of the ceramic mold.
  • the melting process in turn entails five different consecutive stages: isolating the mold, preheating, vacuum melting, cooling or solidification, knock out the mold and cutting.
  • the mold isolation stage entails applying various layers of ceramic blanket on to the exterior of the ceramic mold. It serves to control and direct the various thermal gradients throughout the solidification stage.
  • the position and number of isolation layers is determined by the arrangement and number of gates and sprues forming the part's supply system.
  • the isolation stage is basically designed in such a way that the part is firstly solidified, then the gates which supply it and finally, the main sprue and shell.
  • the preheating stage is carried out in gas furnaces, within which the ceramic mold is introduced at a certain temperature and for a determined length of time.
  • the main aim of this stage is to increase the temperature of the ceramic mold in order to reduce thermal shock with the metal that will be introduced into it later on.
  • the vacuum melting stage is carried out in vacuum furnaces, this type of furnace being necessary so the physicochemical properties of superalloys remain intact.
  • the alloy is supplied in the form of cylindrical ingots, which are introduced into a ceramic container, referred to as the "liner", usually made of SiO 2 .
  • this container is situated within another, larger container named the coil, which is responsible for creating a magnetic induction field through which the ingot is fused in the crucible or liner.
  • the temperature of the molten metal is one of the fundamental parameters at the fusion stage, which is why optical pyrometers are used.
  • the pressure or vacuum level is another significant variable to be considered throughout the entire process, the vacuum furnace being therefore provided with various chambers separated from one another and having watertight valves. These valves make it possible to introduce the preheated mold into the mold chamber at atmospheric pressure, bringing it to vacuum level, wherein the metal will be found in a molten state in the fusion chamber.
  • the ingots are charged by means of the charging chambers whilst the temperature is measured by the pyrometer.
  • the metal Once the metal has been melted and the mold preheated (ready to be extracted), it is introduced into the mold chamber of the vacuum furnace. Once in position, the molten metal flows into the mold interior automatically and the mold is extracted in order to carry out the next stage (cooling).
  • the cooling or solidification stage is initiated.
  • exothermic material a powdered substance known as "exothermic material" to the ceramic cup.
  • the exothermic material is composed of SiO 2 Al, NO 3 Na and Na 2 SiF 6 . This material is of a combustion nature in that it reacts with the still incandescent metal, triggering a strong reaction which releases a lot of heat.
  • the removal from the mold and the cutting process can be carried out, wherein the ceramic surrounding the metal is removed. Once the ceramic is completely removed, the parts in the supply system are separated.
  • Various cutting techniques are employed to facilitate this separation, depending on the shape to be cut. Plasma cutting is henceforth the most common technique, although abrasive disc cutting systems and high pressure water-jet cutters also exist.
  • the resulting supply system is recycled.
  • the ceramic cup that have been contaminated with the exothermic powder are cut at a certain distance using an abrasive disk and the contaminated material is recycled as scrap.
  • the rest forms what is commonly referred to as a "revert" which, mixed with virgin Nickel, serves to manufacture the following master heat cast.
  • the problem posed by this technique is providing an alloy cooling or solidification method which does not contaminate said alloy.
  • the present invention proposes a solution to this technical problem.
  • the "revert" material which is recycled to manufacture the following master heat cast is not contaminated, thereby allowing a greater alloy recovery of approximately 1 kg of revert per mold, the alloy serving to generate the following master heat cast also being of higher quality owing to the fact that it does not contain any form of contaminant.
  • 6 minutes per manufactured mold are saved, corresponding to the average time usually needed to cut the upper portion of the contaminated ceramic cup.
  • the melting operator is not exposed to dangerous elements such as toxic fumes, to the intense light given off when the exothermic reacts with the metal or to potential risks associated with handling a material as flammable as the exothermic. Furthermore, these fumes and suspended particle pollutants are prevented from being released into the atmosphere.
  • One embodiment is a method for melting an alloy part in a mold, characterized in that when cooling or solidifying said alloy part by cooling it in air, Vermiculite is added to the ceramic cup of said mold (henceforth referred to as the method of the invention).
  • Vermiculite shall be referred to as "the material of the invention”.
  • directionality is ensured throughout the cooling stage, in turn guaranteeing the metallurgical quality of the part.
  • the material of the invention is made up of hydrated phyllosilicate and has the following formula: (Mg, Ca) 0.7 (Mg, Fe, Al) 6.0 [(Al, Si) 8 O 20 )] (OH) 4.8 H 2 O
  • the mineral is composed of 30% SiO 2 , 15% Al 2 O 3 , 10% Fe 2 O 3 , 25% MgO and very slight traces of other minerals.
  • the material of the invention does not produce combustion; in other words, it does not react with the molten metal.
  • Another embodiment is the method of the invention, wherein before said cooling in air stage, the following stages are carried out:
  • An additional embodiment is the method of the invention, wherein after said cooling in air stage, said alloy piece is removed from the mold and cut.
  • a further embodiment is the method of the invention, wherein said alloy comprises at least one metal from the Nickel, Cobalt and Titanium group.
  • a further additional embodiment is the method of the invention, wherein said alloy comprises Nickel and Cobalt. More specifically, said alloy comprising Nickel and Cobalt, comprises at least one of the metals selected from the Hafnium, Chrome, Rhenium and Tungsten group.
  • a further additional embodiment is the method of the invention, wherein said mold is a ceramic mold.
  • a further additional embodiment is the method of the invention, wherein the particles of the material of the invention are between 0.5 mm and 5 mm in size.
  • a further additional embodiment is the method of the invention, wherein on average, said particles are between 0.8 mm and 1.2 mm in size. More specifically, said average size is 1mm.
  • Measurements were taken using thermocouples in actual molds, whilst these measurements were compared with the simulation.
  • the measuring point of the part's temperature was located right in the middle of an intersection plane, between one part and its gate.
  • Type S thermocouples with an alumina jacket were used in order to prevent them from deteriorating as measurements were being taken. The measurements were made once the mold had been placed, starting right from the moment when the exothermic was added (approximately 40 seconds after the mold had been taken out of the furnace). The measuring point was identical and was located 25 mm below the molten metal line.
  • the process simulation was carried out using Procast, a specific software on melting (Unigraphics NX 6, Visual-Mesh 8.0, Procast 2011.0, Rev 4.0, Visual- Viewer 8.0, number of elements 1699768, CPU calculation time: 26 hours).
  • the actual validation trials consisted in carrying out the melting process of 3 identical molds to which the exothermic, the material of the invention, or no material at all was applied for the cooling process.
  • the material of the invention added was very fine grade and in flake form.
  • the average size of the particles was approximately 1 mm although there were particles measuring between 0.5 mm and 5 mm.
  • the alloy INCO718 (11 kg) was used, the mold temperature was 1100 °C and the metal temperature was 1440 °C.
  • Mold 1 was cooled in air with the material of the invention. Mold 2 was cooled in air, without adding any compound. Mold 3 was cooled in air with exothermic.
  • Figures 1 and 2 show the average temperature evolution, measured with the thermocouples of the ceramic cup in the 3 cases set out above.
EP13382238.7A 2013-06-24 2013-06-24 Procédé de fusion d'une partie d'alliage Withdrawn EP2818264A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP13382238.7A EP2818264A1 (fr) 2013-06-24 2013-06-24 Procédé de fusion d'une partie d'alliage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP13382238.7A EP2818264A1 (fr) 2013-06-24 2013-06-24 Procédé de fusion d'une partie d'alliage

Publications (1)

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EP2818264A1 true EP2818264A1 (fr) 2014-12-31

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EP13382238.7A Withdrawn EP2818264A1 (fr) 2013-06-24 2013-06-24 Procédé de fusion d'une partie d'alliage

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10493523B1 (en) 2016-02-04 2019-12-03 Williams International Co., L.L.C. Method of producing a cast component

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2186309A1 (en) * 1972-06-01 1974-01-11 Kingscliffe Super Refractories Fly ash cenospheres as melt covering - in casting moulds, ladles, portable liquid metal transporters
FR2432351A1 (fr) * 1978-08-04 1980-02-29 Creusot Loire Procede d'elaboration d'un lingot de forge
US20020124984A1 (en) * 2001-03-12 2002-09-12 Soderstrom Mark L. Investment casting with exothermic material

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2186309A1 (en) * 1972-06-01 1974-01-11 Kingscliffe Super Refractories Fly ash cenospheres as melt covering - in casting moulds, ladles, portable liquid metal transporters
FR2432351A1 (fr) * 1978-08-04 1980-02-29 Creusot Loire Procede d'elaboration d'un lingot de forge
US20020124984A1 (en) * 2001-03-12 2002-09-12 Soderstrom Mark L. Investment casting with exothermic material

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10493523B1 (en) 2016-02-04 2019-12-03 Williams International Co., L.L.C. Method of producing a cast component

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