EP3335817A1 - Giessverfahren und gussartikel - Google Patents

Giessverfahren und gussartikel Download PDF

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Publication number
EP3335817A1
EP3335817A1 EP17205764.8A EP17205764A EP3335817A1 EP 3335817 A1 EP3335817 A1 EP 3335817A1 EP 17205764 A EP17205764 A EP 17205764A EP 3335817 A1 EP3335817 A1 EP 3335817A1
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EP
European Patent Office
Prior art keywords
partially
mold
withdrawal
withdrawing
casting method
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Withdrawn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
EP17205764.8A
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English (en)
French (fr)
Inventor
Jian Zheng
Arthur S. Peck
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.)
General Electric Co
Original Assignee
General Electric Co
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
Priority claimed from US15/383,384 external-priority patent/US10265764B2/en
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP3335817A1 publication Critical patent/EP3335817A1/de
Withdrawn legal-status Critical Current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
    • B22D27/045—Directionally solidified castings
    • 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
    • B22D27/20—Measures not previously mentioned for influencing the grain structure or texture; Selection of compositions therefor

Definitions

  • the present invention is directed to a casting method and cast article. More specifically, the present invention is directed to a casting method for reducing or eliminating freckle grains and a cast article formed therefrom.
  • Various components such as turbine buckets for gas turbine engines, are often formed by directional solidification (DS)/single crystal (SC) casting techniques. More specifically, many components are often formed by a casting "withdrawal" technique where a melt-filled investment mold is withdrawn from a casting furnace. Withdrawing the melt-filled investment mold from the casting furnace permits a molten metal or alloy in the mold to cool and solidify, forming the component within the mold.
  • DS solidification
  • SC single crystal
  • Freckle grains are formed due to interdendritic fluid flow, which may result in equiaxed phases surrounded by eutectic phases. Freckle grains are considered undesirable features and may have unacceptable weakness, particularly in the form of reduced fatigue strength.
  • a casting method including providing a casting furnace, the casting furnace comprising a withdrawal region in a lower end, positioning a mold within the casting furnace, positioning a molten material in the mold, partially withdrawing the mold a withdrawal distance through the withdrawal region in the casting furnace, the withdrawal distance providing a partially withdrawn portion, at least partially solidifying the partially withdrawn portion, then reinserting at least a portion of the partially withdrawn portion into the casting furnace through the withdrawal region, at least partially re-melting the partially withdrawn portion, and then completely withdrawing the mold from the casting furnace through the withdrawal region to produce a directionally solidified or single crystal cast article.
  • the at least partially re-melting the partially withdrawn portion reduces or eliminates freckle grains from the partially withdrawn portion.
  • a casting method includes providing a casting furnace, the casting furnace comprising a withdrawal region in a lower end, positioning a mold within the casting furnace, positioning a molten material in the mold, partially withdrawing the mold through the withdrawal region in the casting furnace for a withdrawal time to provide a partially withdrawn portion, at least partially solidifying the partially withdrawn portion, reinserting at least a portion of the partially withdrawn portion into the casting furnace through the withdrawal region, at least partially re-melting the partially withdrawn portion, and then completely withdrawing the mold from the casting furnace through the withdrawal region to produce a directionally solidified or single crystal cast article.
  • the at least partially re-melting the partially withdrawn portion reduces or eliminates freckle grains from the partially withdrawn portion.
  • a directionally solidified or single crystal cast article includes a directionally solidified or single crystal microstructure and an occurrence of freckle grains corresponding to being formed by a process comprising partially withdrawing to solidify a portion of a withdrawn portion, reinserting to at least partially re-melt the withdrawn portion, and completely withdrawing a mold from a casting furnace to form the directionally solidified or single crystal cast article.
  • Embodiments of the present disclosure in comparison to casting methods and cast articles not using one or more of the features disclosed herein, decrease or eliminate freckle grains in cast articles, increase efficiency of casting article, decrease casting costs, or a combination thereof.
  • a casting method 100 includes providing a casting furnace 200 (step 110), positioning a mold 210 within the casting furnace 200 (step 120), and positioning a molten material 220 in the mold 210 (step 130).
  • step 140 partially withdrawing the mold 210 including the molten material 220 a withdrawal distance 217 through a withdrawal region 205, for example, according to one embodiment, in a lower end 201 of the casting furnace 200, provides a partially withdrawn portion 213.
  • the molten material 220 in the partially withdrawn portion 213 at least partially solidifies to form a solidified portion 215.
  • the casting method 100 includes holding the mold 210 at the withdrawal distance 217 for a partial withdrawal hold time, then reinserting (step 150) at least a portion of the partially withdrawn portion 213 into the casting furnace 200 through the withdrawal region 205 to form a reinserted portion.
  • the partial withdrawal hold time includes any suitable duration, such as, but not limited to, up to about 5 minutes, between about 15 seconds and about 5 minutes, between about 30 seconds and about 5 minutes, or any combination, sub-combination, range, or sub-range thereof.
  • the reinserting (step 150) at least partially re-melts the solidified portion 215 to reduce or eliminate freckle grains 214 (see FIG.
  • the reinserting (step 150) is followed by holding the reinserted portion within the casting furnace 200 for a reinsertion hold time, then completely withdrawing (step 160) the mold 210 from the casting furnace 200 to crystallize the molten material 220 and form a cast article 300.
  • the reinsertion hold time includes any suitable duration, such as, but not limited to, up to about 5 minutes, between about 15 seconds and about 5 minutes, between about 30 seconds and about 5 minutes, or any combination, sub-combination, range, or sub-range thereof.
  • the partial withdrawal hold time and the reinsertion hold time are the same, similar, substantially similar, or different.
  • the casting furnace 200 includes any suitable casting furnace for receiving the mold 210 (see FIG. 2 ), and maintaining a temperature of the molten material 220 (see FIG. 3 ) at or above a molten material crystallization temperature.
  • One suitable casting furnace includes, but is not limited to, a directional solidification casting furnace.
  • the casting furnace 200 receives and/or pre-heats the mold 210 prior to positioning the molten material 220 in the mold 210 (step 130).
  • the casting furnace 200 receives and/or pre-heats a plurality of molds 210.
  • gaps are formed between the plurality of molds 210 within the casting furnace 200.
  • positioning of the molds 210 includes, but is not limited to, vertical indexing, calculated guiding, thermally semi-insulating the gaps, or a combination thereof.
  • the molten material 220 is then introduced into the mold 210 through an aperture 206 in the casting furnace 200.
  • the aperture 206 includes any suitable aperture, such as, but not limited to, a hole in an upper end 202 of the furnace 200, a pipe, a funnel, or a combination thereof.
  • the mold 210 includes any suitable mold for receiving the molten material 220 and forming the cast article 300.
  • the mold 210 includes a ceramic investment shell mold having a pour cup in communication with one or more cavities corresponding to a shape of the cast article 300.
  • the molten material 220 includes any material suitable for casting, and is selected based upon the cast article 300 to be formed.
  • the molten material 220 for forming a turbine bucket includes any material capable of directional solidification and/or single crystal formation. Suitable materials include, but are not limited to, metals, superalloys (for example, nickel, cobalt, or iron base superalloys), or a combination thereof.
  • the molten material 220 has a composition, by weight, of about 9.8% Cr, about 7.5% Co, about 1.5% Mo, about 6% W, about 4.8% Ta, about 0.5% Nb, about 4.2% Al, about 3.6% Ti, about 0.08% C, about 0.01% B, about 0.1% Hf, and a balance of Ni.
  • the partially withdrawing (step 140) of the mold 210 the withdrawal distance 217 exposes the molten material 220 in the partially withdrawn portion 213 to reduced temperatures outside of the casting furnace 200.
  • the reduced temperatures outside the casting furnace 200 cool the molten material 220 within the partially withdrawn portion 213.
  • Cooling the molten material 220 at least partially solidifies the molten material 220 to form the solidified portion 215 within the partially withdrawn portion 213.
  • the solidification shrinks the molten material 220, increasing a density of the solidified material and forming the freckle grains 214 within the solidified portion 215.
  • interdendritic fluid flow forms the freckle grains 214.
  • Various characteristics, such as, but not limited to, size and/or shape of the mold 210 facilitate increases or decreases in the occurrence of freckle grains 214 in the solidified portion 215.
  • the withdrawal distance 217 is selected to correspond with at least one area of the cast article 300 that includes increased freckle grain forming characteristics, such as, but not limited to, initially withdrawn sections, sections including increased thickness, uninterrupted sections, or a combination thereof.
  • the withdrawal distance 217 corresponds to a bucket tip shroud of the turbine bucket.
  • the withdrawal distance 217 includes, but is not limited to, between about 0.250 inches (about 0.635 cm) and about 6 inches (about 15.24 cm), between about 0.250 inches (about 0.635 cm) and about 3 inches (about 7.62 cm), between about 0.250 inches (about 0.635 cm) and about 1 inch
  • the partially withdrawn portion 213 is reinserted (step 150) into the casting furnace 200.
  • the reinserting (step 150) of the partially withdrawn portion 213 at least partially re-melts the solidified material formed in the solidified portion 215 to reduce or eliminate the freckle grains 214.
  • the molten material 220 which previously had formed the freckle grains 214 solidifies during the completely withdrawing (step 160) of the mold 210 so as to reduce or eliminate the occurrence of freckle grains 214 in the cast article 300.
  • the casting method 100 reduces or eliminates the occurrence of freckle grains 214 without post casting freckle grain treatments, such as, but not limited to, blending away the freckle grains 214.
  • Suitable partial withdrawal rates include, but are not limited to, between about 1 inch/hour (about 2.54 cm/hour) and about 30 inches/hour (about 76.2 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 15 inches/hour (about 38.1 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 10 inches/hour (about 25.4 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 7 inches/hour (about 17.8 cm/hour), or any combination, sub-combination, range, or sub-range thereof.
  • the partial withdrawal rate facilitates a type and/or amount of crystallization formed during the solidification of the solidified portion 215.
  • decreasing the partial withdrawal rate increases a duration for exposure of the partially withdrawn portion 213 to the reduced temperature outside of the casting furnace 200. The increased exposure increases the amount of crystallization formed during the solidification of the solidified portion 215.
  • the mold 210 is withdrawn from the casting furnace 200 at a complete withdrawal rate.
  • Suitable complete withdrawal rates include, but are not limited to, between about 1 inch/hour (about 2.54 cm/hour) and about 30 inches/hour (about 76.2 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 15 inches/hour (about 38.1 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 10 inches/hour (about 25.4 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 7 inches/hour (about 17.8 cm/hour), or any combination, sub-combination, range, or sub-range thereof.
  • the complete withdrawal rate facilitates a type and/or rate of crystallization in the cast article 300.
  • the complete withdrawal rate facilitates increased amounts of either directional or single-crystal solidification.
  • the reinsertion rate is equivalent to any of the suitable partial or complete withdrawal rates disclosed herein.
  • the rate of reinsertion is less than the suitable partial or complete withdrawal rates disclosed herein.
  • the rate of reinsertion is greater than the suitable partial or complete withdrawal rates disclosed herein.
  • suitable reinsertion rates include, but are not limited to, between about 1 inch/hour (about 2.54 cm/hour) and about 30 inches/hour (about 76.2 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 15 inches/hour (about 38.1 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 10 inches/hour (about 25.4 cm/hour), between about 1 inch/hour (about 2.54 cm/hour) and about 7 inches/hour (about 17.8 cm/hour), or any combination, sub-combination, range, or sub-range thereof.
  • the partial withdrawal rate, the complete withdrawal rate, and/or the reinsertion rate are automated by any suitable technique throughout the casting method 100.
  • Suitable techniques of the automation include, but are not limited to, providing transitions between the partially withdrawing (step 140), the reinserting (step 150), and/or the completely withdrawing (step 160), automatically reversing the partially withdrawing (step 140) to provide the reinserting (step 150), automatically reversing the reinserting (step 150) to provide the completely withdrawing (step 160), varying the partial withdrawal rate, the reinsertion rate, and/or the complete withdrawal rate, adjusting for variations in temperature within the casting furnace 200, adjusting for the area of the cast article 300 that includes increased freckle grain 214 forming characteristics, or a combination thereof.
  • the partial withdrawal rate, the reinsertion rate, and/or the complete withdrawal rate are maintained throughout each step (with the exception of an acceleration to begin each step and a deceleration to end each step).
  • the partial withdrawal rate, the reinsertion rate, and the complete withdrawal rate are about 5 inches/hour (about 12.7 cm).
  • at least one of the partial withdrawal rate, the reinsertion rate, and the complete withdrawal rate is varied throughout the casting method 100.
  • Varying throughout the casting method 100 includes, but is not limited to, between steps (for example, between the partially withdrawing (step 140), the reinserting (step 150), and/or the completely withdrawing (step 160)), during at least one step, corresponding to the area of the cast article 300 that includes increased freckle grain 214 forming characteristics, or a combination thereof.
  • the partial withdrawal rate and the complete withdrawal rate are about 3 inches/hour (about 7.6 cm/hour), while the reinsertion rate is about 10 inches/hour (about 25.4 cm/hour).
  • the casting method 100 includes repeating (step 155) of the partially withdrawing (step 140) and/or the reinserting (step 150) of the mold 210.
  • the partially withdrawing (step 140) exposes a previously-unexposed portion 413
  • the reinserting (step 150) at least partially re-melts the solidified portion 215 within a reinsertion segment of the previously-unexposed portion 413.
  • the reinsertion segment includes, but is not limited to, all, or substantially all, of the previously-unexposed portion 413, less than the entire previously-unexposed portion 413, the area of the cast article 300 that includes increased freckle grain 214 forming characteristics, or a combination thereof.
  • the partially withdrawing (step 140) exposes the previously-unexposed portion 413 of about 1 inch (about 2.54 cm), including the reinsertion segment of about 0.5 inches (about 1.27 cm) corresponding to an area of increased thickness.
  • the re-melting of solidified portion 215 within the reinsertion segment reduces or eliminates the freckle grains 214 formed therein.
  • the partially withdrawing (step 140) exposes the partially withdrawn portion 213 of about 0.5 inches (about 1.27 cm), and the reinserting (step 150) partially re-melts the solidified portion 215 within the partially withdrawn portion 213.
  • the repeating (step 155) of the partially withdrawing (step 140) exposes the partially withdrawn portion 213 of about 0.5 inches (about 1.27 cm), including the solidified portion 215 that has been partially re-melted, as well as the previously-unexposed portion 413 of about 0.5 inches (about 1.27 cm).
  • step 155) of the reinserting (step 150) then re-melts the solidified portion 215 formed within the previously-unexposed portion 413 without re-melting the solidified portion 215 within the partially withdrawn portion 213 that has been partially re-melted.
  • the casting method 100 includes partially withdrawing (step 140) the mold 210 with the molten material 220 for a withdrawal time.
  • the withdrawal time includes any suitable amount of time corresponding to formation of the solidified portion 215. Suitable amounts of time include, but are not limited to, up to about 2 hours, up to about 1.5 hours, up to about 1 hour, between about 1 hour and about 2 hours, up to about 0.5 hours, or any combination, sub-combination, range, or sub-range thereof.
  • the partial withdrawal rate during the withdrawal time includes any suitable partial withdrawal rate disclosed herein.
  • the partial withdrawal rate during the withdrawal time includes, but is not limited to, a constant rate, a pre-set variation in the rate of withdrawal, a progressive rate, or a combination thereof.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Mold Materials And Core Materials (AREA)
  • Supercharger (AREA)
EP17205764.8A 2016-12-19 2017-12-06 Giessverfahren und gussartikel Withdrawn EP3335817A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US15/383,384 US10265764B2 (en) 2014-01-28 2016-12-19 Casting method and cast article

Publications (1)

Publication Number Publication Date
EP3335817A1 true EP3335817A1 (de) 2018-06-20

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EP17205764.8A Withdrawn EP3335817A1 (de) 2016-12-19 2017-12-06 Giessverfahren und gussartikel

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EP (1) EP3335817A1 (de)
JP (1) JP6986945B2 (de)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1076118A1 (de) * 1999-08-13 2001-02-14 ABB (Schweiz) AG Verfahren und Vorrichtung zur Herstellung eines gerichtet erstarrten Giesskörpers
US20130022803A1 (en) * 2008-09-25 2013-01-24 General Electric Company Unidirectionally-solidification process and castings formed thereby
EP2902135A2 (de) * 2014-01-28 2015-08-05 General Electric Company Gießverfahren und gegossener Gegenstand
WO2015130371A2 (en) * 2013-12-30 2015-09-03 United Technologies Corporation Directional solidification apparatus and related methods

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5275227A (en) * 1990-09-21 1994-01-04 Sulzer Brothers Limited Casting process for the production of castings by directional or monocrystalline solidification
US6217286B1 (en) * 1998-06-26 2001-04-17 General Electric Company Unidirectionally solidified cast article and method of making
WO2007122736A1 (ja) * 2006-04-25 2007-11-01 Ebis Corporation 鋳造方法及び装置
US20100034692A1 (en) * 2008-08-06 2010-02-11 General Electric Company Nickel-base superalloy, unidirectional-solidification process therefor, and castings formed therefrom
US20100071812A1 (en) * 2008-09-25 2010-03-25 General Electric Company Unidirectionally-solidification process and castings formed thereby
US10082032B2 (en) * 2012-11-06 2018-09-25 Howmet Corporation Casting method, apparatus, and product

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1076118A1 (de) * 1999-08-13 2001-02-14 ABB (Schweiz) AG Verfahren und Vorrichtung zur Herstellung eines gerichtet erstarrten Giesskörpers
US20130022803A1 (en) * 2008-09-25 2013-01-24 General Electric Company Unidirectionally-solidification process and castings formed thereby
WO2015130371A2 (en) * 2013-12-30 2015-09-03 United Technologies Corporation Directional solidification apparatus and related methods
EP2902135A2 (de) * 2014-01-28 2015-08-05 General Electric Company Gießverfahren und gegossener Gegenstand

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JP2018122355A (ja) 2018-08-09
JP6986945B2 (ja) 2021-12-22

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