EP3533897A1 - Améliorations relatives à des composants d'alliage métallique et leur fabrication - Google Patents

Améliorations relatives à des composants d'alliage métallique et leur fabrication Download PDF

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EP3533897A1
EP3533897A1 EP18159319.5A EP18159319A EP3533897A1 EP 3533897 A1 EP3533897 A1 EP 3533897A1 EP 18159319 A EP18159319 A EP 18159319A EP 3533897 A1 EP3533897 A1 EP 3533897A1
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EP
European Patent Office
Prior art keywords
component
iron
metal alloy
based composition
suitably
Prior art date
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EP18159319.5A
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German (de)
English (en)
Inventor
Manu Mathai
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Siemens AG
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Siemens AG
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Priority to EP18159319.5A priority Critical patent/EP3533897A1/fr
Priority to PCT/EP2019/053857 priority patent/WO2019166244A1/fr
Publication of EP3533897A1 publication Critical patent/EP3533897A1/fr
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/52—Ferrous alloys, e.g. steel alloys containing chromium with nickel with cobalt
    • 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
    • B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
    • B22F3/225—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip by injection molding
    • 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
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/04—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of turbine blades
    • 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
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
    • F01D5/12—Blades
    • F01D5/28—Selecting particular materials; Particular measures relating thereto; Measures against erosion or corrosion
    • 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
    • B22F2998/10—Processes characterised by the sequence of their steps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2230/00—Manufacture
    • F05D2230/20—Manufacture essentially without removing material
    • F05D2230/21—Manufacture essentially without removing material by casting
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2230/00—Manufacture
    • F05D2230/20—Manufacture essentially without removing material
    • F05D2230/22—Manufacture essentially without removing material by sintering
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2300/00—Materials; Properties thereof
    • F05D2300/10—Metals, alloys or intermetallic compounds
    • F05D2300/11—Iron
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2300/00—Materials; Properties thereof
    • F05D2300/10—Metals, alloys or intermetallic compounds
    • F05D2300/13—Refractory metals, i.e. Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W
    • F05D2300/132—Chromium

Definitions

  • the present disclosure relates to components manufactured from metal alloys, the components comprising different metal alloy compositions in different regions of the component, which may provide improved pitting corrosion resistance and mechanical properties.
  • the present disclosure also relates to methods of providing said components and to apparatus for carrying out said methods.
  • compressor aerofoils formed from different iron-based compositions which are tailored to meet specific requirements in specific regions of the component and to reduce delta ferrite formation.
  • pitting corrosion is a type of localized corrosion of a metal that results in the formation of pits (small holes) in the metal.
  • a cause of pitting corrosion is depassivation of a typically small surface area of the metal, which becomes anodic while the remainder of the surface becomes cathodic, thereby resulting localised galvanic corrosion. This corrosion penetrates the surface of metal.
  • Pitting corrosion typically occurs in alloys, for example stainless steels, nickel alloys and aluminium alloys, that are normally protected by passivation surface layers, for example oxide layers, in environments that contain aggressive species, for example chloride ions, are at elevated temperatures, have increased concentrations of oxidants and/or are acidic.
  • gas turbine components for example rotating and stationary compressor blades (also known as aerofoils or airfoils), require at least a combination of high strength, toughness and fatigue resistance to withstand static and/or dynamic stresses, for example centripetal stresses and/or stress cycling, at operational temperatures.
  • Stainless steels for example ASTM P91, ASTM P92, GTD 450, SAE 400 series, SAE 600 series such as SAE type 630 (also known as 17-4 or 17-4PH; also known as UNS 17400), may meet these requirements.
  • SAE type 630 also known as 17-4 or 17-4PH; also known as UNS 17400
  • such components may also be susceptible to pitting corrosion, which may initiate fatigue cracking during high cycle fatigue, for example. Growth of such fatigue cracks may result in catastrophic failure of the components.
  • such components may be susceptible to water droplet erosion (WDE) which may be caused by impingement of liquid water droplets sprayed on the components to provide cooling. WDE may also contribute towards fatigue of the components and ultimately failure. Leading edges of compressor blades may be particularly susceptible to pitting corrosion and/or WDE.
  • WDE water droplet erosion
  • 17-4PH is a precipitation hardened martensitic stainless steel.
  • the composition of 17-4PH is as follows:
  • 17-4PH is prone to delta ferrite formation predominantly in the longitudinal direction of the aerofoil which results in anisotropy in mechanical properties and a significant drop in the mechanical properties in the longitudinal direction. This drop in mechanical properties is believed to have caused numerous tip failures in compressor aerofoils manufactured from 17-4PH. The issues with delta ferrite formation and various corrosion issues due to pitting corrosion are observed in such compressor aerofoils.
  • Figure 1 shows the microstructure of a section taken in the longitudinal direction in a compressor aerofoil manufactured from 17-4PH. This image was produced after etching the section with 20% NaOH and processing the image to highlight the delta ferrite streaks (1).
  • Figure 1 shows that the delta ferrite streaks are clearly visible in the sections taken in the longitudinal direction i.e. in the direction of deformation expected in use.
  • the delta ferrite is typically seen to be aligned in the direction of working during manufacture of the compressor aerofoils from a rolled bar. It is evident based on the microstructure shown in Figure 1 , that the delta-ferrite is elongated in the martensite matrix of the aerofoil.
  • the percentage of delta ferrite at various locations was between 5.5 and 6 % which is above a desired level of free ferrite for maintaining acceptable mechanical performance. Although a small amount of delta ferrite can be beneficial for increasing tensile properties and resistance to stress-corrosion cracking, the levels of delta ferrite observed in Figure 1 are believed to significantly reduce toughness during use of the aerofoil and therefore risk failures of the aerofoil.
  • a component such as a compressor aerofoil, having a leading edge with improved resistance to pitting corrosion compared to prior art components.
  • a component comprising a first iron-based composition in at least a first region of the component, the first iron-based composition comprising:
  • the iron-based composition is suitably a metal alloy comprising mainly iron with the specified alloying elements and optionally other alloying elements.
  • the iron-based composition is suitably a steel.
  • the inventor has found that the addition of the specified alloying elements to the first iron-based composition may reduce delta ferrite formation in the component compared to a similar component formed of an iron-based composition of the prior art, such as 17-4PH, and therefore may improve the mechanical properties of the component.
  • the addition of the specified alloying elements to the first iron-based composition may also improve the pitting corrosion resistance of the first region of the component compared to a similar region of a component formed of an iron-based composition of the prior art, such as 17-4PH.
  • an iron-based composition of the prior art such as 17-4PH.
  • nickel and cobalt are austenite formers, the amount of nickel is lower in the first iron-based composition compared to 17-4PH to accommodate the cobalt in the first iron-based composition without increasing the austenite forming potential of the first iron-based composition whilst increasing pitting corrosion resistance.
  • the inventor has also found that the addition of the specified alloying elements to the first iron-based composition may also improve the resistance of the first region of the component to impacts of foreign objects compared to a similar region of a component formed of an iron-based composition of the prior art, such as 17-4PH. This may be particularly useful when the first region is a region of the component exposed to the outside environment in use, such as a leading edge region of a compressor aerofoil. This improvement may be at least partially due to the cobalt content of the first iron-based composition.
  • the first iron-based composition comprises 2.0-6.0 wt% copper, suitably 3.0-5.0 wt% copper.
  • the first iron-based composition comprises 4.0-7.0 wt% molybdenum.
  • the first iron-based composition comprises 5.0-6.0 wt% molybdenum, suitably 5.5-6.0 wt%.
  • the first iron-based composition comprises:
  • the first iron-based composition comprises:
  • the inventor has found that the addition of molybdenum to the first iron-based composition may further improve the pitting corrosion resistance compared to a similar component formed of an iron-based composition of the prior art, such as 17-4PH.
  • an iron-based composition of the prior art such as 17-4PH.
  • chromium and molybdenum are ferrite and martensite formers
  • the amount of chromium is lower in the first iron-based composition compared to 17-4PH, to accommodate the molybdenum in the first iron-based composition without increasing the ferrite and martensite forming potential of the first iron-based composition whilst increasing pitting corrosion resistance.
  • Molybdenum is considered to have a more significant effect on the pitting corrosion resistance of the first iron-based composition than chromium.
  • the first iron-based composition comprises one or more of niobium, manganese, silicon, and phosphorous, suitably in an amount of up to 1.0 wt%.
  • the first iron-based composition comprises niobium, suitably in an amount of up to 0.3 wt%, suitably approximately 0.3 wt%, suitably 0.3 wt%.
  • niobium may have the advantage of providing an increase in strength of the component, for example an increase in the resistance to foreign object impacts.
  • the phosphorous when present, is present in the first iron-based composition in an amount of up to 0.03 wt%.
  • the first iron-based composition comprises:
  • the first iron-based composition comprises niobium in an amount of at least 0.2 wt%.
  • the first iron-based composition comprises manganese in an amount of at least 0.2 wt%.
  • the first iron-based composition comprises silicon in amount of at least 0.8 wt%.
  • the first iron-based composition comprises phosphorous in an amount of at least 0.02 wt%.
  • the first iron-based composition comprises:
  • the first region of the component comprises an edge of the component.
  • the edge of the component is exposed to the environment during use of the component and is therefore susceptible to pitting corrosion and to impacts from foreign objects.
  • the first iron-based composition of the component of this first aspect provides the first region with particular properties which would be advantageous at such an edge region.
  • the component is an iron-based component.
  • the component is entirely formed from iron-based compositions, the compositions being different in the first region of the component compared to other regions of the component.
  • the component is formed of a steel.
  • the component is a compressor aerofoil and the first region is a leading edge region of the compressor aerofoil.
  • the component is a compressor aerofoil, suitably intended to operate at a temperature of 350 °C.
  • the component of this first aspect comprises a second iron-based composition in a second region of the component, the second iron-based composition comprising:
  • the second iron-based composition comprises 2.0-6.0 wt% copper, suitably 3.0-5.0 wt% copper.
  • the second iron-based composition does not comprise molybdenum.
  • the second iron-based composition does not comprise niobium.
  • the second iron-based composition does not comprise molybdenum or niobium.
  • the second iron-based composition comprises a lower amount of cobalt compared to the first iron-based composition.
  • the second iron-based composition comprises a higher amount of nickel compared to the first iron-based composition. Therefore the second iron-based composition is different to the first iron-based composition.
  • the second region is suitably a trailing edge of the compressor aerofoil.
  • the trailing edge of such a compressor aerofoil does not require the same level of pitting corrosion resistance and strength to resist foreign object impacts as required of the leading edge of the compressor aerofoil. Therefore, the second iron-based composition may advantageously comprise less of the expensive cobalt alloying element to save on the overall cost of manufacturing the component.
  • the second iron-based composition comprises:
  • the second iron-based composition comprises:
  • the second iron-based composition comprises:
  • the second iron-based composition comprises:
  • the second iron-based composition comprises:
  • first and second regions of the component are shaped to interlock with adjacent regions of the component.
  • the first and second regions being shaped in this way may improve the mechanical properties of the join between the first and second regions and the adjacent regions and therefore improve the mechanical properties of the component.
  • the component of this first aspect comprises a third iron-based composition in a third region of the component, the third iron-based composition comprising:
  • the third iron-based composition comprises 2.0-6.0 wt% copper, suitably 3.0-5.0 wt% copper.
  • the third iron-based composition does not comprise molybdenum.
  • the third iron-based composition comprises a lower amount of cobalt compared to the first iron-based composition and a higher amount of cobalt than the second iron-based composition.
  • the third iron-based composition comprises a higher amount of nickel compared to the first iron-based composition and a lower amount of nickel compared to the second iron-based composition. Therefore the third iron-based composition is different to the first iron-based composition and the second iron-based composition.
  • the variation in these alloying elements described above provides a gradual transition in chemical composition which may advantageously provide a gradual transition in mechanical properties from the first iron-based composition through the third iron-based composition to the second iron-based composition. Such a gradual transition may provide an improved bond between the different regions of the component which avoids a mechanical weakness seen in prior art components formed from more significantly different iron-based compositions, for example by joining different regions of a component having different compositions together by brazing.
  • the third region of the component is arranged between and in contact with the first region and the second region of the component.
  • the third region is suitably an intermediate region arranged between and in contact with the leading edge and the trailing edge regions.
  • the intermediate region of such a compressor aerofoil does not require the same level of pitting corrosion resistance and strength to resist foreign object impacts as required of the leading edge of the compressor aerofoil. Therefore, the third iron-based composition may advantageously comprise less of the expensive cobalt alloying element to save on the overall cost of manufacturing the component.
  • the third iron-based composition comprises:
  • the third iron-based composition comprises:
  • the third iron-based composition comprises:
  • the third iron-based composition comprises:
  • the third iron-based composition comprises:
  • first, second and third regions of the component are shaped so that the third region interlocks with the first and second regions of the component.
  • a component comprising:
  • the component, first iron-based composition and second iron-based composition of this second aspect may have any of the suitable features and advantages described in relation to the first aspect.
  • a method of forming a component comprising a first metal alloy composition in at least a first region of the component and a second metal alloy composition in at least a second region of the component, the method comprising the steps of:
  • the method of this third aspect is a metal injection moulding (MIM) process.
  • MIM metal injection moulding
  • Steps a) and b) may be carried out in any order or simultaneously.
  • steps a) and b) are carried out simultaneously.
  • the remaining steps c)-e) are carried out after steps a) and b) in the order of step c) followed by step d) followed by step e).
  • Using the method of this third aspect to form the component may advantageously allow the manufacture of such a component with a reduced amount of material wastage compared to prior art methods.
  • the method may also advantageously provide a component, such as a compressor aerofoil, formed from different metal alloy compositions in different regions of the component without requiring a joining process for forming a bond between said regions. Such a component may therefore have improved mechanical properties compared to a similar component formed using a joining process.
  • step a) is carried out by extruding the first metal alloy composition into the first section of the mould.
  • step b) is carried out by extruding the second metal alloy composition into the second section of the mould.
  • steps a) and b) are carried out by extruding the first and second metal alloy compositions into the first and second sections of the mould through a die.
  • steps a) and b) are carried out by extruding the first and second metal alloy compositions into the first and second sections of the mould through a die, wherein the die shapes the first and second metal alloy compositions to interlock with adjacent regions of the component.
  • the die may impart a profile on the first and second metal alloy compositions which defines interlocking male and female parts which resist the first and second regions being pulled away from their adjacent regions.
  • sliding cores, ejectors and other moving components can be used to divide the mould into said sections to facilitate formation of the component in this method of the third aspect.
  • a removable core can be used to form a female interlocking profile in the first section of the mould.
  • the first metal alloy composition is injected into the first section of the mould and allowed to solidify.
  • the removable core is then removed.
  • the second metal alloy composition is then injected into the second section of the mould to form the male interlocking profile cavity against the female interlocking profile of the first metal alloy composition.
  • This sequence may be repeated for any number of different metal alloy compositions, for example a third metal alloy composition as described above.
  • the injection unit along with the individual mould sections and/or removable cores can all be rotated or moved in a desired sequence to inject and solidify the various material compositions.
  • step a) may be preceded by a step of placing a first removable core into the mould to define and provide the first section of the mould.
  • step a) may be followed by a step of removing the removable core from the mould before step b) is carried out, suitably after the first metal alloy composition has solidified. Therefore step c) may involve allowing the second metal alloy composition to solidify, the first metal alloy composition having already solidified.
  • a second removable core may be placed into the mould to define the second section of the mould and a third section of the mould. The second removable core may then be removed after depositing and solidifying of the third metal alloy composition in the third section of the mould before the second metal alloy composition is deposited and solidified in the second section of the mould.
  • first metal alloy composition and the second metal alloy composition are admixed with a binder before steps a) and b) are carried out.
  • the binder is suitably a material that is chemically compatible with the metallic powder and allows the required processing, i.e. mixing, injection, solidification and finally leaching to be carried out.
  • the binder may be a thermoplastic resin.
  • the binder may be selected from a polyacrylate, a polyethylene or a polypropylene. In some embodiments the binder may be water, oil or wax.
  • the admixtures of metal alloy composition and binder may comprise up to 70 wt% binder, suitably from 30 to 50 wt% binder.
  • step e) involves removing the binder from the preform of the component.
  • step e) involves removing the binder from the preform of the component with a solvent.
  • step e) involves sintering the preform of the component, suitably after the solvent has been removed from the preform of the component.
  • Sintering may be carried out at a temperature of from 950 °C and 1,800 °C.
  • step e the component may then be removed from the apparatus used to carry out the injection moulding and allowed to cool.
  • the method of this third aspect may involve, after step e), a step f) of heat treating the component.
  • step f) involves heating the component at a temperature greater than 1,000 °C for at least 2 hours.
  • step f) involves heating the component in a solution at a temperature of at least 800 °C, suitably followed by quenching, suitably in a salt bath.
  • step f) involves ageing the component at a temperature of between 400 and 600 °C for at least 1 hour.
  • step f) involves each of the heating and ageing steps discussed above.
  • the component comprises a third metal alloy composition in a third region of the component and the method comprises a step of depositing the third metal alloy composition into a third section of the mould.
  • the third region of the component is arranged between and in contact with the first region and the second region of the component.
  • steps a) and b) are carried out by extruding the first, second and third metal alloy compositions into the first, second and third sections of the mould through a die, wherein the die shapes the first, second and third metal alloy compositions so that the third region interlocks with the first and second regions of the component.
  • the die may impart a profile on the first, second and third metal alloy compositions which defines interlocking male and female parts which resist the first, second and third regions being pulled apart.
  • the component and the first, second and third metal alloy compositions of this third aspect may have any of the suitable features and advantages described in relation to the component and the first, second and third iron-based compositions of the first aspect.
  • the method of this third aspect provides a method of forming a component according to the first or second aspects, wherein the first metal alloy composition is the first iron-based composition and the second metal alloy composition is the second iron-based composition.
  • an apparatus for forming a metal alloy component comprising:
  • the mould is formed from separable mould parts to enable the mould to be opened to remove said component.
  • the depositing mechanisms with separate feeds are extruders, suitably rotating screw extruders.
  • the extruders comprise hoppers for receiving said metal alloy compositions.
  • the hoppers are heated.
  • the apparatus comprises a die arranged between the depositing mechanisms and the opening, for shaping said metal alloy compositions.
  • the die has a profile adapted to impart an interlocking shape on said metal alloy compositions passing through the die from the adjacent at least two depositing mechanisms.
  • the apparatus of this fourth aspect is a metal injection moulding apparatus.
  • Figure 2 shows component (100) which is a compressor aerofoil formed of a steel with a different composition in different regions of the aerofoil (100).
  • the component (100) comprises a first region (110) which is a leading edge region of the aerofoil, a second region (120) which is a trailing edge region of the aerofoil, a third region (130) which is an intermediate region of the aerofoil between the leading and trailing edge regions and a platform (140), which are common parts of such compressor aerofoils with known functions.
  • the leading edge region (110) of the aerofoil (100) has the following iron-based composition:
  • the trailing edge region (120) of the aerofoil (100) has the following iron-based composition:
  • the intermediate region (130) of the aerofoil (100) has the following iron-based composition:
  • the leading edge region (110) is adjacent to and in contact with the intermediate region (130) at a first interface (113) which runs through aerofoil (100) in a longitudinal direction.
  • the trailing edge region (120) is adjacent to and in contact with the intermediate region (130) at a second interface (123) which runs through aerofoil (100) in a longitudinal direction.
  • the first and second interfaces (113 and 123) are shaped to provide an interlocking of the respective regions.
  • the first interface (113) defines a female profile in the leading edge region (110) and a complementary male profile in the intermediate region (130).
  • the second interface (123) defines a female profile in the intermediate region (130) and a complementary male profile in the trailing edge region (120).
  • Said male and female profiles interlock in the aerofoil (100) to provide resistance to the adjacent regions separating in a transverse direction (i.e. in a direction between the leading and trailing edges) to improve the mechanical integrity of the aerofoil (100) comprising the different regions having different compositions.
  • the different compositions of the leading edge region (110), the intermediate region (130) and the trailing edge region (120) may provide the aerofoil (100) with improved mechanical properties compared to a similar aerofoil formed from a single known iron-based composition such as 17-4PH.
  • the leading edge region (110) may provide the leading edge of the aerofoil (100) with improved pitting corrosion resistance and improved resistance to impacts from foreign objects which may strike the aerofoil (100) in use, due to the optimised amounts of alloying elements.
  • the composition of the trailing edge region (120) may provide a cost saving due to the lower amount of expensive alloying elements such as cobalt compared to the leading edge region (110).
  • the composition of the intermediate region (130) may provide a more gradual change in composition between the leading edge region (110) and the trailing edge region (120) than may otherwise be possible if only two different iron-based compositions were used to form the aerofoil (100). This gradual change in composition may avoid the negative effects on mechanical properties observed with prior art components which have used significantly different compositions in adjacent regions of such components.
  • the compositions of each of the leading edge region (110), the intermediate region (130) and the trailing edge region (120) may provide a reduced tendency to form delta ferrite structures in the aerofoil (100) compared with prior art aerofoils, due to the optimised amounts of alloying elements in each iron-based composition, in particular the amounts of nickel, cobalt and copper.
  • the aerofoil (100) is essentially free of delta ferrite.
  • Figure 3 shows an apparatus (200) for forming a component such as a compressor aerofoil (100) by metal injection moulding.
  • the apparatus (200) comprises a first, second and third extruder (210, 220 and 230), each comprising a hopper (211, 221 and 231) for receiving metal alloy compositions and feeding said metal alloy compositions into the extruders (210, 220 and 230).
  • Each extruder may be a rotating screw extruder.
  • Each extruder (210, 220 and 230) is provided with a die (212, 222 and 232) for shaping the metal alloy composition from the extruders into the interlocking shape discussed in relation to Figure 2 .
  • the extruders (210, 220 and 230) are arranged above and adjacent to the mould (240).
  • the mould (240) has a shape which corresponds to a component, such as an aerofoil (100), and is formed of two mould parts (242 and 243).
  • a component such as an aerofoil (100)
  • the mould (240) as shown in Figure 3 is divided into the two mould parts (242 and 243) horizontally, the mould may alternatively be divided vertically which may improve the ease of removal of the component from the mould.
  • the mould (240) comprises a cavity (250) into which the extruders (210, 220 and 230) deposit metal alloy compositions, in use.
  • the cavity can be nominally divided into a first, second and third cavity section (251, 251 and 253) divided by the dotted lines shown in Figure 3 .
  • Fine metallic powders of first, second and third metal alloy compositions which correspond to the compositions of the leading edge region (110), the trailing edge region (120) and the intermediate region (130) of aerofoil (100) are each thoroughly mixed with a binder to provide first, second and third metal alloy and binder mixtures which are then separately charged into the first, second and third hoppers (211, 221 and 231) respectively.
  • inert gas atomisation is a preferred method for the production of spherical powder particles.
  • the powder particle sizes produced by this method are normally in the range from around 5 to 45 ⁇ m.
  • the initial average powder particle size, particle size distribution and the shape of the metal powder particles may influence the injection viscosity and subsequently the integrity of the final product.
  • the powders of first, second and third metal alloy compositions suitably have a range of both small and large particle sizes in order to obtain a high initial packing density.
  • the first, second and third metal alloy and binder mixtures are then heated to melt the binder components to provide first, second and third liquid metal alloy and binder mixtures which comprise metallic powders coated with binder.
  • the first, second and third liquid metal alloy and binder mixtures are then extruded through the first, second and third extruders respectively (210, 220 and 230), through the dies (212, 222 and 232) and into the cavity (250) of the mould (240).
  • the first liquid metal alloy and binder mixture is deposited into the first cavity section (251), the second liquid metal alloy and binder mixture into the second cavity section (252) and the third liquid metal alloy and binder mixture into the third cavity section (253).
  • the dies (212, 222 and 232) provide liquid metal alloy and binder mixtures with the interlocking profile discussed above and as shown in Figure 2 .
  • Each liquid metal alloy and binder mixture is in contact with the adjacent liquid metal alloy and binder mixture and in contact with walls of the mould which define the cavity (250).
  • the liquid metal alloy and binder mixtures retain the shape imparted on them by the dies (212, 222 and 232) after depositing into the cavity (250).
  • any number of said different metal alloy compositions, hoppers, extruders and cavity sections can be used as required to form specific components with different metal alloy compositions.
  • the first, second and third liquid metal alloy and binder mixtures are then solidified in the mould (240) to produce a component preform.
  • the mould (240) may be heated to avoid excessively rapid cooling and solidification of the binder which can subsequently result in a brittle component preform. Said heating of the mould (240) could be targeted at specific regions of the component likely to become brittle during solidification.
  • the two mould parts (242 and 243) are separated and the component preform is removed.
  • the term "green state” may alternatively be used to describe the component preform. Both of these terms are used in the art to denote a solidified mixture of metal alloy composition and binder having an approximate shape of a finished component after injection moulding. The component preform is brittle at this stage of the process.
  • the component preform is then washed with a suitable solvent known in the art to remove the binder from the metal alloy composition. Then the component preform is sintered by heating to a temperature in the range of 950 °C to 1,800°C and holding at that temperature for 2-6 hours.
  • the sintering increases the density of the component preform by the formation of bonding between metallic particles of the metal alloy compositions.
  • the sintering temperature is suitably selected to be a temperature below the solidus temperature of the powders of first, second and third metal alloy compositions. However, the sintering temperature needs to be high enough for the powders of first, second and third metal alloy compositions to fuse together and consolidate.
  • the use of the gradual variation in metal alloy compositions as described above enables the sintering process to achieve near perfect inter-particle bonding which may not have been possible with prior art components having significantly different metal alloy compositions.
  • This sintering process may provide an improved bond between the different regions of the component compared to a joining process of the prior art, such as a brazing process.
  • the component then undergoes a heat treatment step to improve the ultimate tensile strength of the component.
  • a heat treatment step is as follows:
  • the component produced by this method for example a compressor aerofoil, may have the desired strength in the appropriate regions of the component and may be free from delta ferrite.
  • the elimination of delta ferrite would result in uniform mechanical properties in both longitudinal and transverse directions and prevent tip failures observed in compressor aerofoils of the prior art.
  • This method may also provide the advantage that the amount of material wastage in the production of such components using prior art methods can be significantly reduced, improving the cost-effectiveness of the process.
  • a similar metal injection moulding process may be used to form other components, for example an aerofoil root.
  • a mould could be used which provides for the formation of an aerofoil root in combination with the aerofoil moulding described above, to avoid the need to bond these two parts together.
  • the present invention provides a component, such as a compressor aerofoil, having different optimised metallic compositions in different regions of the component which may provide improved mechanical properties and improved pitting corrosion resistance and may in particular eliminate the formation of delta ferrite in the component.
  • the component comprises at least two different iron-based compositions in different region of the component, including a first iron-based composition comprising 11.0-15.0 wt% chromium; 1.0-4.0 wt% nickel; 5.0-8.0wt% cobalt; and iron.
  • the first iron-based composition may also comprise comprises 2.0-6.0 wt% copper, 4.0-7.0 wt% molybdenum and one or more of niobium, manganese, silicon, and phosphorous.
  • a metal injection moulding method for forming a component and an apparatus for carrying out said method are also provided.
  • compositions consisting essentially of a set of components will comprise less than 5% by weight, typically less than 3% by weight, more typically less than 1% by weight of non-specified components.
  • the first iron-based composition comprises 11.0-15.0 wt% chromium
  • 11.0-15.0 wt% of the first iron-based composition is provided by chromium.

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  • Manufacturing & Machinery (AREA)
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  • Structures Of Non-Positive Displacement Pumps (AREA)
EP18159319.5A 2018-02-28 2018-02-28 Améliorations relatives à des composants d'alliage métallique et leur fabrication Withdrawn EP3533897A1 (fr)

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EP18159319.5A EP3533897A1 (fr) 2018-02-28 2018-02-28 Améliorations relatives à des composants d'alliage métallique et leur fabrication
PCT/EP2019/053857 WO2019166244A1 (fr) 2018-02-28 2019-02-15 Améliorations concernant les composants d'alliage métallique et leur fabrication

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CN116251950A (zh) * 2021-12-10 2023-06-13 东莞市逸昊金属材料科技有限公司 铁基粉末冶金材料、粉末冶金加工方法及制件

Citations (5)

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Publication number Priority date Publication date Assignee Title
JP2000192196A (ja) * 1998-12-22 2000-07-11 Sumitomo Metal Ind Ltd 油井用マルテンサイト系ステンレス鋼
US20070202000A1 (en) * 2004-08-24 2007-08-30 Gerhard Andrees Method For Manufacturing Components
EP2516107A1 (fr) * 2009-12-23 2012-10-31 Snecma Procede de realisation d'un renfort metallique d'aube de turbomachine
EP3061841A1 (fr) * 2015-02-26 2016-08-31 General Electric Company Acier inoxydable martensitique résistant aux piqûres de corrosion
US20160273587A1 (en) * 2015-03-16 2016-09-22 Aktiebolaget Skf Bearing steel

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US20030062660A1 (en) * 2001-10-03 2003-04-03 Beard Bradley D. Process of metal injection molding multiple dissimilar materials to form composite parts
US6607358B2 (en) * 2002-01-08 2003-08-19 General Electric Company Multi-component hybrid turbine blade
BR112018068914B1 (pt) * 2016-03-29 2022-02-15 Jfe Steel Corporation Tubo de aço inoxidável sem costura de alta resistência para poço de óleo
DE102016208761A1 (de) * 2016-05-20 2017-11-23 Rolls-Royce Deutschland Ltd & Co Kg Pulverspritzgießverfahren, Pulverspritzgießvorrichtung und Pulverspritzgussteil

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Publication number Priority date Publication date Assignee Title
JP2000192196A (ja) * 1998-12-22 2000-07-11 Sumitomo Metal Ind Ltd 油井用マルテンサイト系ステンレス鋼
US20070202000A1 (en) * 2004-08-24 2007-08-30 Gerhard Andrees Method For Manufacturing Components
EP2516107A1 (fr) * 2009-12-23 2012-10-31 Snecma Procede de realisation d'un renfort metallique d'aube de turbomachine
EP3061841A1 (fr) * 2015-02-26 2016-08-31 General Electric Company Acier inoxydable martensitique résistant aux piqûres de corrosion
US20160273587A1 (en) * 2015-03-16 2016-09-22 Aktiebolaget Skf Bearing steel

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