WO2015141191A1 - Compressor impeller cast from al alloy and method for producing same - Google Patents

Compressor impeller cast from al alloy and method for producing same Download PDF

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Publication number
WO2015141191A1
WO2015141191A1 PCT/JP2015/001340 JP2015001340W WO2015141191A1 WO 2015141191 A1 WO2015141191 A1 WO 2015141191A1 JP 2015001340 W JP2015001340 W JP 2015001340W WO 2015141191 A1 WO2015141191 A1 WO 2015141191A1
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Prior art keywords
alloy
mass
casting
molten metal
compressor impeller
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PCT/JP2015/001340
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French (fr)
Japanese (ja)
Inventor
貴司 久保
高橋　功一
俊男 牛山
石川　宣仁
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株式会社Uacj
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Application filed by 株式会社Uacj filed Critical 株式会社Uacj
Priority to US15/125,185 priority Critical patent/US20170107600A1/en
Priority to JP2016508521A priority patent/JPWO2015141191A1/en
Priority to CN201580014056.5A priority patent/CN106170572A/en
Priority to EP15764543.3A priority patent/EP3121303B1/en
Publication of WO2015141191A1 publication Critical patent/WO2015141191A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/057—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with copper as the next major constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/02—Sand moulds or like moulds for shaped castings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/22—Moulds for peculiarly-shaped castings
    • B22C9/28—Moulds for peculiarly-shaped castings for wheels, rolls, or rollers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
    • B22D15/005—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor of rolls, wheels or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • B22D17/20—Accessories: Details
    • B22D17/2015—Means for forcing the molten metal into the die
    • B22D17/203—Injection pistons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D18/00—Pressure casting; Vacuum casting
    • B22D18/04—Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D18/00—Pressure casting; Vacuum casting
    • B22D18/06—Vacuum casting, i.e. making use of vacuum to fill 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
    • B22D21/002—Castings of light metals
    • B22D21/007—Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
    • 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
    • B22D21/04—Casting aluminium or magnesium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D25/00—Special casting characterised by the nature of the product
    • B22D25/02—Special casting characterised by the nature of the product by its peculiarity of shape; of works of art
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/12—Alloys based on aluminium with copper as the next major constituent
    • C22C21/16—Alloys based on aluminium with copper as the next major constituent with magnesium
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/02—Selection of particular materials
    • F04D29/023—Selection of particular materials especially adapted for elastic fluid pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/26—Rotors specially for elastic fluids
    • F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
    • F04D29/284—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps for compressors
    • 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
    • F05D2300/17—Alloys
    • F05D2300/173—Aluminium alloys, e.g. AlCuMgPb

Definitions

  • the present invention relates to a compressor impeller made of an aluminum alloy casting used for a turbocharger for an internal combustion engine of an automobile or a ship, and a manufacturing method thereof.
  • Turbochargers used in internal combustion engines for automobiles and ships are provided with a compressor impeller for compressing air by high speed rotation and supplying the compressed air to the internal combustion engine.
  • This compressor impeller reaches a high temperature of about 150 ° C. during high-speed rotation, and high stress is generated in the vicinity of the rotation center, particularly in the disk portion due to torsional stress or centrifugal force from the rotating shaft.
  • Compressor impellers are made of various materials according to the required performance of the turbocharger. For large-scale applications such as for ships, an aluminum alloy hot forging material cut into an impeller shape is usually used. For relatively small vehicles such as passenger cars and trucks, and small ships, mass productivity and cost are important.
  • JIS-AC4CH Al-7% Si-0.3% Mg alloy
  • ASTM-354.0 Al-9% Si-1.8% Cu-0.5% Mg alloy
  • ASTM-C355.0 Al-5% Si-1.3% Cu-0.5% Mg alloy
  • a gypsum mold plaster mold
  • the composition of the aluminum alloy to, for example, JIS-AC1B (Al-5% Cu-0.3% Mg alloy) having superior high-temperature strength.
  • JIS-AC1B Al-5% Cu-0.3% Mg alloy
  • Patent Document 2 in the case of a complicated shape such as a compressor impeller and a thin blade portion, an alloy such as JIS-AC1B lacks good fluidity of the molten metal, There was a problem in that poor hot water filling (filling failure) was likely to occur in the thin wall portion.
  • Patent Document 2 in order to solve the above-mentioned problem, an Al—Si based easily castable alloy such as AC4CH is used for the blade portion regarded as having a hot water property, and is coupled to a rotating shaft that requires strength.
  • a method has been proposed in which a high-strength alloy such as AC1B, such as AC1B, is used from the boss portion to the disk portion, and these are poured in two portions and combined to form a compressor impeller.
  • Patent Document 3 an alloy having good castability is used for the blade part, and aluminum is impregnated with a reinforcing material such as an aluminum whisker containing 25% B from the boss part to which stress is applied to the center part of the disk part.
  • a reinforcing material such as an aluminum whisker containing 25% B from the boss part to which stress is applied to the center part of the disk part.
  • Patent Document 4 proposes a method of joining a blade part and a boss part (and a disk part) by friction welding.
  • the method in which different materials are used in combination with each part still has the problem that the productivity is inferior and the cost increases, and industrialization has not yet been achieved.
  • Patent Document 5 discloses that a single alloy can be cast by optimizing the range of elements contained in an Al—Cu—Mg based alloy and the combination thereof.
  • a compressor impeller having a proof stress at 250 ° C. of 250 MPa or more has been proposed.
  • Patent Document 6 discloses that the yield of casting at 200 ° C. is improved to 260 MPa or more by further improving the range of elements contained in the Al—Cu—Mg based alloy and the combination thereof to control the crystal grain size to improve the casting yield. Compressor impellers have been proposed.
  • the present invention has been made in view of the above-mentioned problems, and an aluminum alloy (hereinafter referred to as “Al alloy”) that has a stable strength over a long period of time even at a use temperature of about 200 ° C. and has excellent productivity. It is an object of the present invention to provide a cast compressor impeller and a manufacturing method thereof.
  • the present inventors have focused on the disk portion of the compressor impeller to which high stress is applied, and found that the strength of the disk portion is dramatically improved when the intermetallic compound at the end of the disk portion is finely dispersed. It was.
  • the manufacturing method for finely dispersing the intermetallic compound is intensively studied, and it is important for the fine dispersion of the intermetallic compound to refine the primary crystal grains. For this purpose, the cooling rate of the molten Al alloy is controlled.
  • the inventors have obtained the knowledge that it is important to control the distribution of fine particles in the compressor impeller and have completed the present invention.
  • the disk portion excluding the boss portion, the plurality of blade portions, and the end portion is Cu: 1.4.
  • Mg 1.0 to 2.0 mass%
  • Ni 0.5 to 2.0 mass%
  • Fe 0.5 to 2.0 mass%
  • Ti 0.01 to 0.35 mass%
  • B 0.002 to 0.070 mass%
  • the end of the disk portion has Cu: 1.4 to 3.2 mass%, Mg: 1.
  • the compressor impeller made of an Al alloy casting according to the first aspect of the present invention is used for a large-sized ship application, and the height of the boss portion, the diameter of the disk portion, and the height of the blade portion are 200 to 80 mm, 300 to 100 mm, and 180 to 60 mm, the blade tip thickness was 4.0 to 0.4 mm, and the number of blades was 30 to 10.
  • the compressor impeller made of an Al alloy casting according to the first aspect of the present invention is used for small applications such as automobiles, and the height of the boss portion, the diameter of the disk portion, and the height of the blade portion are 100 It is assumed that the blade tip thickness is 3.0 to 0.1 mm, and the number of blades is 20 to 4 mm.
  • Cu 1.4-3.2 mass%
  • Mg 1.0-2.0 mass%
  • Ni 0.5-2.0 mass%
  • Fe 0.5-2.0 mass 720 to 780 ° C.
  • a melt preparation step further containing 0.01 to 0.35 mass%
  • B 0.002 to 0.070 mass%; cooling at 100 to 250 ° C.
  • the prepared Al is passed through the molten metal inflow hole.
  • a casting process for casting an Al alloy casting by a pressure casting method for press-fitting wherein a casting flow rate of the molten metal in the molten metal inflow hole into the space is 0.12 to 1.00 m / second;
  • the cooling rate of the end of the disk portion is 0.1 to 200 ° C./second in the casting step.
  • the present invention is that in claim 6 or claim 4 or 5, in the solution treatment step, the Al alloy casting is heat-treated at a temperature lower by 5 to 25 ° C. than the solidus temperature of the Al alloy for 2 hours or more. In the aging treatment step, the solution-treated Al alloy casting was heat treated at 180 to 230 ° C. for 3 to 30 hours.
  • an aluminum alloy cast compressor impeller that exhibits stable heat resistance over a long period of time even in a high temperature region around 200 ° C. and is excellent in productivity such as casting yield.
  • the heat resistance strength is stable and excellent over a long period of time means that deformation and fatigue failure do not occur over a long period of time even at a use temperature of about 200 ° C. Specifically, it is assumed that there is no damage due to a turbo assembling durability test at 200 ° C. and 150,000 rpm ⁇ 200 hours.
  • FIG. 1 shows an example of the shape of an aluminum alloy cast compressor impeller (hereinafter simply referred to as “compressor impeller”) according to the present embodiment.
  • the compressor impeller 1 includes a rotation center shaft (boss part) 2, a disk part 3 integrally connected to the rotation center shaft 2, and a plurality of thin blades 4 protruding from the disk part 3.
  • the temperature of the compressor impeller 1 reaches a high temperature of about 200 ° C. during high speed rotation, and a large repetitive stress is generated in the vertical direction particularly at the end of the disk portion.
  • Cu, Mg Cu and Mg are dissolved in the Al matrix and have the effect of improving mechanical strength by solid solution strengthening. Further, the coexistence of Cu and Mg contributes to an improvement in strength by precipitation strengthening of Al 2 Cu, Al 2 CuMg and the like. However, since these two elements are elements that expand the solidification temperature range, excessive inclusion deteriorates the castability.
  • the Cu content is less than 1.4 mass% (hereinafter simply referred to as “%”) and / or when the Mg content is less than 1.0%, the machine required at a high temperature of 200 ° C. Strength cannot be obtained.
  • the Cu content exceeds 3.2% and / or when the Mg content exceeds 2.0%, the castability as a compressor impeller is inferior, and particularly, the hot water around the blade tip is reduced. Insufficient thickness is likely to occur.
  • the Cu content is set to 1.4 to 3.2%, and the Mg content is set to 1.0 to 2.0%.
  • the Cu content is set to 1.7. It is preferable that the content is 2.8% and the Mg content is 1.3-1.8%.
  • Ni, Fe Ni and Fe form an intermetallic compound together with Al, which is dispersed in the Al matrix, and has the effect of improving the high temperature strength of the Al alloy.
  • the Ni content is 0.5% or more
  • the Fe content is also 0.5% or more.
  • both elements are contained excessively, not only the intermetallic compound becomes coarse, but also Cu 2 FeAl 7 and Cu 3 NiAl 6 are formed at a high temperature to reduce the amount of solid solution Cu in the Al matrix. Will reduce the strength.
  • these intermetallic compounds are coarse at the end of the disk portion, the compressor impeller is damaged starting from these intermetallic compounds due to repeated stress applied to the end of the disk portion.
  • the Ni content is 2.0% or less and the Fe content is 2.0% or less.
  • the Ni content is 0.5 to 2.0% and the Fe content is 0.5 to 2.0%. It is preferable that the Ni content is 0.5 to 1.4% and the Fe content is 0.7 to 1.5%.
  • the lower limit value of the above preferred range is a guide value for industrially stable mass production by reducing variation during production, and the upper limit value is a content that is saturated and the content beyond this is wasted This is a guideline for the amount.
  • Ti, B Ti and B are added to exert the effect of suppressing the growth of primary aluminum crystal grains during casting, so that the solidification structure during casting is refined to improve the replenishability of the molten metal and the effect of improving the meltability.
  • the Ti content is less than 0.01% and / or B content is less than 0.002% in the disk part excluding the boss part, the plurality of blade parts, and the end part, and Ti content in the end part of the disk part. Is less than 0.005% and / or when the B content is less than 0.001%, the above effects cannot be obtained sufficiently.
  • the Ti content exceeds 0.35% and / or the B content exceeds 0.070% in the disk part excluding the boss part, the plurality of blade parts, and the end part, and the end of the disk part
  • the Ti content exceeds 0.175% and / or the B content exceeds 0.035% in the part
  • aggregates of finer particles are generated, and fatigue cracks start from the aggregates. Will occur.
  • the Ti content in each part exceeds 0.35%, a coarse intermetallic compound with a size of several tens to several hundreds of ⁇ m is formed together with Al, which becomes a starting point of fatigue cracks during rotation, and reliability as a compressor impeller Reduce.
  • the Ti content is 0.01 to 0.35% and the B content is 0.002 to 0.070%, preferably Has a Ti content of 0.15 to 0.30% and a B content of 0.003 to 0.060%. Further, at the end of the disk portion, the Ti content is 0.005 to 0.175% and the B content is 0.001 to 0.035%, preferably the Ti content is 0.010 to 0%. 165% and B content is 0.002 to 0.033%.
  • the aluminum alloy used in the present invention is a pressure casting method (low pressure casting method, reduced pressure casting method or differential pressure method) using a gypsum mold (plaster mold) in accordance with a conventional method for producing an Al—Si aluminum alloy casting. By casting method) into a compressor impeller shape.
  • the pressure casting method using a gypsum mold relates the distribution of the intermetallic compounds within each casting, at the end of the disk portion, there was intermetallic compounds with a circle equivalent diameter of 1 ⁇ 6 [mu] m is 10000 / mm 2 or more and, it is necessary to control the production conditions so that the intermetallic compound having a circle equivalent diameter of greater than 6 ⁇ m exists 500 / mm 2 or less.
  • the present inventors have applied a high repetitive vertical stress generated by the acceleration / deceleration of the rotation of the compressor impeller to the end of the disk part, and the circle exceeding 6 ⁇ m existing at the end of the disk part. It was found that a coarse intermetallic compound having an equivalent diameter becomes a starting point of cracks and breaks as these cracks progress. Further, when the surface density of the intermetallic compound having a circle-equivalent diameter exceeding 6 ⁇ m is 500 pieces / mm 2 or less at the end of the disk portion by further study, cracks originating from these intermetallic compounds It has been found that the occurrence is suppressed and that the propagation is suppressed even if a crack occurs.
  • any intermetallic compounds with a circle equivalent diameter of 1 ⁇ 6 [mu] m is 10000 / mm 2 or more, it has also been found that the generation of the coarse intermetallic compound is suppressed.
  • the amount of intermetallic compound produced is determined by the composition under general casting conditions.
  • “General casting conditions” refers to a cooling rate by low-pressure casting, specifically 0.1 to 200 ° C./second.
  • generated at the time of casting is not influenced greatly by subsequent heat processing. Therefore, by producing a large amount of fine intermetallic compounds at the time of casting, it is possible to suppress the formation of coarse intermetallic compounds by subsequent heat treatment.
  • the reason why the surface density of the intermetallic compound having a circle-equivalent diameter of 1 to 6 ⁇ m is 10,000 pieces / mm 2 or more is as follows. An intermetallic compound having an equivalent circle diameter of less than 1 ⁇ m does not affect the compressor impeller strength. In addition, when the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 ⁇ m is less than 10,000 / mm 2 , the production of the intermetallic compound having an equivalent circle diameter exceeding 6 ⁇ m is promoted and exceeds 6 ⁇ m to be generated. Cracks start from an intermetallic compound having an equivalent circle diameter.
  • the upper limit value of the surface density is not particularly limited, but is determined by the composition of Al alloy and manufacturing conditions. In the present invention, the upper limit value is 30000 pieces / mm 2 .
  • the reason why the surface density of the intermetallic compound having a circle-equivalent diameter exceeding 6 ⁇ m is 500 pieces / mm 2 or less is as follows. As described above, an intermetallic compound having an equivalent circle diameter exceeding 6 ⁇ m is targeted. Moreover, when this areal density exceeds 500 piece / mm ⁇ 2 >, the separation distance of these intermetallic compounds becomes close, and propagation of a crack advances.
  • the lower limit value of the surface density is not particularly limited, and is determined by the composition and production conditions of the Al alloy. In the present invention, 100 pieces / mm 2 is preferable, and 0 pieces / mm 2 is most preferable. .
  • intermetallic compound produced in the present invention examples include Al—Fe—Ni—Cu, Al—Fe—Cu—Ni—Mg, Al—Cu—Mg, Al—Cu, and Al—Cu—Mg—Si. And intermetallic compounds such as Al—Cu—Fe, Al—Ni, Al—Mg, and Mg—Si.
  • the equivalent circle diameter of the intermetallic compound to be generated varies in the range of 0.1 to 20.0 ⁇ m, although it varies depending on the composition of Al alloy and the manufacturing conditions.
  • the equivalent circle diameter means the equivalent circle diameter.
  • Control of the component amount of the micronizing agent at the end of the disk part In controlling the distribution of the intermetallic compound, it is important to control the size of the primary aluminum crystal grains. This is because the intermetallic compound is generated at the grain boundary of primary aluminum crystal grains. In order to control the size of primary aluminum crystal grains, the component amount of the micronizing agent and the cooling rate described later are important control factors.
  • Appropriate component amounts of Ti and B at the end of the disk portion are Ti: 0.005 to 0.175% and B: 0.001 to 0.035%.
  • a refiner composed of Al, Ti and B is added during the melt preparation step, and the Ti and B component amounts in the molten aluminum alloy after the melt preparation step are set to Ti: 0. 0.01 to 0.35%, B: 0.002 to 0.070%.
  • the product-shaped space composed of the gypsum mold and the cooling metal is configured such that the gypsum mold with the molten metal inflow hole provided in the lower part is disposed below and the cooling metal is disposed above.
  • the prepared Al alloy molten metal is press-fitted into the space through the molten metal inflow hole. Furthermore, the inflow speed of the molten metal in the molten metal inflow hole into this space is set to 0.12 to 1.00 m / sec.
  • a casting process for casting an Al alloy casting by a pressure casting method in which the adjusted molten metal is press-fitted into the space so as to satisfy the above requirements is employed.
  • a refiner composed of Al, Ti, and B is added as a refiner during the melt preparation step, but the Ti component amount in the molten aluminum alloy after the melt adjustment step is less than 0.01% and / or the B component amount is 0. If it is less than 0.002%, the primary aluminum crystal grains become coarse, and the intermetallic compounds at the grain boundaries also become coarse, thereby reducing the strength of the Al alloy material. Further, when the Ti component amount in the molten aluminum alloy after the molten metal adjustment step exceeds 0.35% and / or the B component amount exceeds 0.070%, coarse TiB 2 aggregates are generated, which It becomes the starting point of destruction. Therefore, the component amounts of Ti and B in the molten aluminum alloy after the step of adjusting the molten metal by adding the micronizing agent are set to Ti: 0.01 to 0.35% and B: 0.002 to 0.070%.
  • a product-shaped space composed of a plaster mold and a chiller will be described.
  • the plaster mold 7 is cooled downward, and the metal 6 is placed upward to form a product-shaped space 10 constituted by these.
  • the molten metal inflow hole 8 for making a molten metal flow in into the space 10 is provided in the lower part by the side of the gypsum mold 7.
  • the molten metal flows into the space 10 from the molten metal inflow hole 8 along the molten metal inflow direction 9 from the lower side to the upper side in the figure and is filled in the space 10.
  • the molten metal flowing into the space 10 is solidified while being filled from the lower side to the upper side of the space 10. Therefore, in the circumferential direction of the compressor impeller, the circumferential portion below the space 10 is solidified early, and the circumferential portion located above is solidified later, and a uniform solidification state in the circumferential direction is obtained. I can't get it. In a compressor impeller, uneven solidification in the circumferential direction causes bending of the shaft portion, resulting in poor balance when rotated at high speed.
  • the flow rate of the molten metal in the molten metal inflow hole is an important factor in controlling the content of the micronizing agent at the end of the disk portion.
  • the content of the finer particles composed of Ti and B reaching the end of the disk portion is reduced as compared with the content of the finer particles in the melt preparation step. This is because the movement of the finer particles does not follow the molten metal that moves during pressure casting in accordance with the law of inertia.
  • the molten metal inflow speed in the molten metal inflow hole exceeds 1.00 m / sec, the molten metal inflow speed is too high, and the degree of movement of the finer particles that move by inertia cannot follow the molten metal inflow speed increases.
  • the inflow speed of the melt in the melt inflow hole is less than 0.12 m / sec, the inflow speed of the melt is too slow, and the time until the melt reaches the gypsum mold through the stalk becomes longer. Lowers and causes poor coagulation.
  • the molten metal inflow rate in the molten metal inflow hole is preferably 0.20 to 0.85 m / sec.
  • the cooling rate at the end of the disk part is adjusted to a suitable range of 0.1 to 200 ° C./second.
  • cooling rate When the cooling rate is less than 0.1 ° C./second, primary aluminum crystal grains become coarse, and intermetallic compounds generated at the grain boundaries become coarse. Further, shrinkage nests are generated due to a decrease in cooling rate, and productivity is reduced. On the other hand, when the cooling rate exceeds 200 ° C./sec, the product shape cannot be ensured because a hot water defect occurs due to early solidification in the product shape space.
  • a more preferable range of the cooling rate at the end of the disk portion is 3 to 150 ° C./second.
  • the temperature of the molten metal is less than 720 ° C., the molten metal that has been injected solidifies in the product shape space at an early stage, resulting in poor hot water production and the product shape cannot be secured.
  • the temperature of the molten metal exceeds 780 ° C., the oxidation of the molten metal progresses, the increase in the number of generated porosity due to the absorption of hydrogen gas and the increase in the oxide deteriorate the molten metal quality, and it is difficult to ensure the product strength. Become.
  • the temperature of the cooling metal is less than 100 ° C.
  • the progress of solidification is too fast, resulting in poor hot water.
  • the temperature of the chilled metal exceeds 250 ° C.
  • solidification from the chilled metal is delayed, and the primary aluminum crystal grains become coarse due to a decrease in the cooling rate, resulting in coarse intermetallic compounds generated at the grain boundaries.
  • a so-called burr defect occurs in which hot water is inserted between the gypsum mold and the cooling metal.
  • the preheating temperature of the gypsum mold is not particularly limited, but it is preferably controlled to 200 to 350 ° C. If the preheating temperature of the gypsum mold is less than 200 ° C., solidification proceeds before the molten metal is filled at the tip of the mold, resulting in poor hot water and a product shape cannot be secured. On the other hand, when the preheating temperature of the gypsum mold exceeds 350 ° C., solidification in the gypsum mold is delayed and a shrinkage defect is generated.
  • the material of the cooling metal is preferably copper or copper alloy having high thermal conductivity, but iron, stainless steel, etc. can also be used.
  • a mechanism that suppresses overheating during casting through a cooling medium such as water inside the cooling metal.
  • This manufacturing method includes a melt preparation process, a casting process, and a heat treatment process.
  • each component element is added and melted by heating so as to achieve the above-described Al alloy composition, and molten metal treatment such as dehydrogenation gas treatment and inclusion removal treatment is performed. Then, the temperature is adjusted so that the final molten metal temperature is 720 to 780 ° C. Also, the amount of hydrogen gas in the molten metal is adjusted. As a method for adjusting the amount of hydrogen gas in the molten metal, a rotary gas blowing device is used, but is not limited thereto.
  • Casting process In the casting process, the molten metal whose temperature is adjusted to 720 to 780 ° C. is cast into a compressor impeller shape by a pressure casting method using a gypsum mold. As described above, the temperature of the cooling metal disposed on the surface in contact with the disk surface is adjusted to 100 ° C. to 250 ° C. As shown in FIG. 3, the product-shaped space composed of the gypsum mold and the cooling metal is arranged with the gypsum mold downward and the cooling metal disposed upward to form a product-shaped space composed of these. To do.
  • the molten metal inflow hole for making a molten metal flow in into a space along a molten metal inflow direction is provided in the lower part by the side of the gypsum mold 7.
  • the inflow speed of the molten metal in the molten metal inflow hole to the space is adjusted to 0.12 to 1.00 m / sec.
  • an Al alloy casting is cast by the pressure casting method in which the prepared molten Al alloy is press-fitted into the space.
  • Heat treatment process The cast Al alloy casting is subjected to a heat treatment process.
  • the heat treatment step includes a solution treatment step and an aging treatment step.
  • solid solution strengthening by Cu; precipitation strengthening by Cu and Mg; dispersion strengthening by an intermetallic compound formed by Al and Fe and by Al and Ni can be effectively utilized.
  • the solution treatment is preferably performed in a temperature range 5 to 25 ° C. lower than the solidus temperature.
  • the temperature range 5 to 25 ° C. lower than the solidus temperature is 510 to 530 ° C. If the temperature exceeds a temperature range lower by 5 to 25 ° C. than the solidus temperature, the risk of melting the second phase of the crystal grain boundary increases, and it becomes difficult to ensure the strength. On the other hand, at temperatures below this temperature range, element diffusion does not proceed sufficiently and sufficient solution is not achieved.
  • the solution treatment time is preferably 2 hours or longer. If it is less than 2 hours, element diffusion does not proceed sufficiently and sufficient solution is not achieved.
  • the solution time by element diffusion is not particularly limited as long as it is 2 hours or longer, but is preferably 30 hours or less in consideration of mass production.
  • the aging treatment is preferably heat treatment at 180 to 230 ° C. for 3 to 30 hours, more preferably heat treatment at 190 to 210 ° C. for 5 to 20 hours.
  • the treatment temperature is less than 180 ° C. or when the treatment time is less than 3 hours, precipitation strengthening for improving the strength may be insufficient.
  • the processing temperature exceeds 230 ° C. or when the processing time exceeds 30 hours, the formed precipitated phase becomes coarse (over-aged) and a sufficient strengthening action cannot be obtained. The solution strengthening ability decreases.
  • the shape and dimensions of the compressor impeller according to the present invention and the number of blades are not particularly limited, and can be applied to many uses such as large ships for ships and small applications such as automobiles. it can.
  • the height of the boss part, the diameter of the disk part and the height of the blade part are 200 to 80 mm, 300 to 100 mm, 180 to 60 mm, preferably 180 to 100 mm, respectively.
  • the blade tip thickness is 4.0 to 0.4 mm, preferably 3.0 to 0.6 mm.
  • the number of blades is 30 to 10, preferably 26 to 12.
  • the height of the boss, the diameter of the disk and the height of the blades are 100 to 20 mm, 120 to 25 mm, 90 to 5 mm, preferably 90 to 25 mm, respectively.
  • the blade tip thickness is 3.0 to 0.1 mm, preferably 2.0 to 0.2 mm.
  • the number of blades is 20 to 4, preferably 18 to 6.
  • the Al alloy molten metal prepared in the molten metal preparing step is a predetermined structure constituted by a gypsum mold adjusted to 250 ° C. and a copper cooling metal that is arranged on the surface in contact with the impeller disk surface and adjusted to the temperature shown in Table 1.
  • Low pressure that is injected into the space through a molten metal inflow hole provided in the lower part of the lower plaster mold (FIG. 3), the lateral part of the lateral plaster mold (FIG. 4) or the upper part of the upper plaster mold (FIG. 5).
  • An Al alloy casting was produced by a casting method.
  • This Al alloy cast compressor impeller is a compressor impeller for a passenger car turbocharger having a disk part diameter of 40 mm, a boss part height of 40 mm, 12 blades, a blade part height of 35 mm, and a blade tip thickness of 0.3 mm.
  • the direction of the molten metal flowing into the space composed of the plaster mold and the cooling metal is shown in Table 1, and the molten metal inflow rate into the space is shown in Table 1.
  • the molten metal is injected into the space under pressure. The pressure was maintained until solidification of the entire Al alloy casting was completed.
  • Density, amount of component of finer (Ti, B) at the end of the disk part, amount of component of finer (Ti, B) at a part other than the end of the disk part, high temperature characteristics (durability test evaluation), and The productivity (casting yield evaluation) was evaluated as follows.
  • FIG. 2 shows a cross section of one side of the central shaft 5 of the compressor impeller.
  • the end 31 of the disk portion was cut out and then polished, and imaged with an optical microscope at a magnification of 100 times.
  • the end portion 31 of the disk portion refers to a disk portion that is 20% from the outer periphery in the length from the outer periphery of the disk portion of the compressor impeller to the central axis 5 along the radial direction.
  • the surface density of an intermetallic compound having an equivalent circle diameter of 1 to 6 ⁇ m and the surface density of an intermetallic compound having an equivalent circle diameter exceeding 6 ⁇ m were measured.
  • 10 measurement locations were arbitrarily selected, and the arithmetic average value was used as the surface density.
  • the measurement field area of each measurement point was 1 mm 2. The results are shown in Table 2.
  • High-temperature fatigue strength was evaluated by an endurance test (turbo assembly, 150,000 rpm ⁇ 200 hours, outlet temperature 200 ° C.). The results are shown in Table 2.
  • “ ⁇ ” indicates that the sample was broken during the test, “ ⁇ ” indicates that the sample was not broken but cracked, and the sample was not broken or cracked and remained in a healthy state. In this case, “ ⁇ ” was assigned.
  • Comparative Example 1 the surface density of the intermetallic compound having a high temperature of the cooling metal, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 ⁇ m at the end of the disk portion is small, and the surface density of the intermetallic compound having an equivalent circle diameter exceeding 6 ⁇ m was big. As a result, the disk portion was broken at the end portion and inferior in the high temperature characteristics. Further, the shrinkage defect in the boss portion was frequently generated, and the casting yield was greatly reduced.
  • Comparative Example 5 there were few Cu components and the high temperature characteristics were good, but poor hot water in the blades occurred frequently, resulting in a decrease in casting yield.
  • Comparative Example 11 there were many Mg components and the high temperature characteristics were good, but poor hot water in the blades occurred frequently, resulting in a decrease in casting yield.
  • Comparative Example 12 the surface density of the intermetallic compound having a large amount of Fe component and having a circle-equivalent diameter exceeding 6 ⁇ m was large. As a result, cracks occurred in the disk portion and the high temperature characteristics were inferior.
  • Comparative Example 13 the surface density of the intermetallic compound having a large Ni component and having an equivalent circle diameter exceeding 6 ⁇ m was large. As a result, the disk portion cracked and the high temperature characteristics were inferior.
  • Second Example (Invention Examples 8 to 18 and Comparative Examples 21 to 26)
  • the Al alloy having the composition shown in the component column of Table 3 was melted by performing a normal molten metal treatment, and subjected to a molten metal preparation step in which the molten metal was adjusted to the temperature shown in Table 3.
  • a molten metal preparation step 150 kg of an Al alloy having the composition shown in the component column of Table 3 was melted to obtain a molten metal.
  • degassing was performed by blowing argon gas into the molten metal for 20 minutes under the conditions of a rotor rotation speed of 400 rpm and a gas flow rate of 2.5 Nm 3 / h using a rotating gas blowing device. Thereafter, the entire molten metal was sedated for 1 hour and removed.
  • a refiner composed of Ti and B shown in the component amount column of the refiner after preparation of the melt in Table 3 was added to the melt.
  • the Al alloy molten metal prepared in the molten metal preparing step is a predetermined structure composed of a gypsum mold adjusted to 220 ° C. and a copper chiller arranged on the surface in contact with the impeller disk surface and adjusted to the temperature shown in Table 3.
  • An Al alloy casting was produced by a low pressure casting method in which pressure was injected into the space.
  • This Al alloy casting compressor impeller is a compressor impeller for a truck turbocharger having a disk portion diameter of 80 mm, a boss portion height of 70 mm, a blade number of 14 pieces, a blade portion height of 60 mm, and a blade tip thickness of 0.4 mm. As shown in FIG.
  • the space constituted by the gypsum mold and the cooling metal is configured such that the gypsum mold in which the molten metal inflow hole is provided in the lower part is disposed below and the cooling metal is disposed above,
  • the direction of the molten metal flowing into the space was upward.
  • the molten metal inflow rate into the space was set to 0.75 m / second, and the molten metal was pressurized and injected into the space, and the pressure was maintained until solidification of the entire Al alloy casting was completed.
  • Comparative Example 25 no solution treatment step was performed, and in Comparative Example 26, an aging treatment step was not performed. As a result, all of them were broken at the disk portion and inferior in high temperature characteristics.
  • the Al alloy molten metal prepared in the molten metal preparing step is a predetermined structure composed of a gypsum mold adjusted to 220 ° C. and a copper chiller arranged on the surface in contact with the impeller disk surface and adjusted to the temperature shown in Table 5.
  • An Al alloy casting was produced by a low pressure casting method in which pressure was injected into the space.
  • This Al alloy casting compressor impeller is a compressor impeller for a marine turbocharger having a disk portion diameter of 150 mm, a boss portion height of 160 mm, a blade number of 16 pieces, a blade portion height of 120 mm, and a blade tip thickness of 0.6 mm. As shown in FIG.
  • the space constituted by the gypsum mold and the cooling metal is configured such that the gypsum mold in which the molten metal inflow hole is provided in the lower part is disposed below and the cooling metal is disposed above,
  • the direction of the molten metal flowing into the space was upward.
  • the molten metal inflow rate into the space was 0.95 m / second, and the molten metal was pressurized and injected into the space, and the pressure was maintained until solidification of the entire Al alloy casting was completed.
  • Density, amount of component of finer (Ti, B) at the end of the disk part, amount of component of finer (Ti, B) at a part other than the end of the disk part, high temperature characteristics (durability test evaluation), and The productivity (casting yield evaluation) was evaluated in the same manner as in the first example. The results are shown in Table 6.
  • Comparative Example 27 the melt temperature was high and the cooling rate was lowered, so that the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 ⁇ m at the end of the disk portion was small, and the equivalent circle diameter exceeding 6 ⁇ m.
  • the surface density of the intermetallic compound was large. As a result, the appearance defect of the shrinkage cavity in the boss part frequently occurred, the casting yield was greatly reduced, and the disk part was broken and inferior in high temperature characteristics.
  • Comparative Example 28 the molten metal temperature was low, the appearance of hot water around the blade portion was frequent, the casting yield was lowered, and cracks were generated in the blade portion, resulting in poor high temperature characteristics.
  • Comparative Example 31 the solution treatment process was not performed, and in Comparative Example 32, the aging process was not performed. As a result, all of them were broken at the disk portion and inferior in high temperature characteristics.
  • the present invention it is possible to supply at low cost an Al alloy compressor impeller having excellent heat resistance and capable of stably withstanding an increase in temperature accompanying an increase in the rotational speed over a long period of time.
  • the present invention has an industrially significant effect that it can contribute to improving the output of the internal combustion engine by increasing the charging capability of the turbocharger.

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Abstract

The present invention provides: a compressor impeller that is cast from an aluminum alloy, has superior production characteristics, and exhibits stable high-temperature strength when used at temperatures around 200°; and a method for producing same. The compressor impeller that is cast from an Al alloy is provided with a boss section, a plurality of vane sections, and a disc section; the boss section, the plurality of vane sections, and the disc section excluding the end section comprise an Al alloy comprising a predetermined metal composition; and at the end section of the disc section, there are at least 10,000/mm2 of intermetallic compounds having a circle-equivalent diameter of 1-6 μm, and there are no greater than 500/mm2 of intermetallic compounds having a circle-equivalent diameter exceeding 6 μm.

Description

Ａｌ合金鋳物製コンプレッサーインペラー及びその製造方法Compressor impeller made of Al alloy casting and manufacturing method thereof
　本発明は、自動車や船舶の内燃機関用のターボチャージャーに使用される、アルミニウム合金鋳物製のコンプレッサーインペラー及びその製造方法に関する。 The present invention relates to a compressor impeller made of an aluminum alloy casting used for a turbocharger for an internal combustion engine of an automobile or a ship, and a manufacturing method thereof.
　自動車や船舶用の内燃機関に用いられるターボチャージャーには、高速回転によって空気を圧縮して内燃機関に供給するためのコンプレッサーインペラーが設けられている。このコンプレッサーインペラーは、高速回転中には１５０℃程度の高温に達し、さらに回転中心近傍、特にディスク部には回転軸からのねじり応力や遠心力などによる高い応力が発生する。 2. Description of the Related Art Turbochargers used in internal combustion engines for automobiles and ships are provided with a compressor impeller for compressing air by high speed rotation and supplying the compressed air to the internal combustion engine. This compressor impeller reaches a high temperature of about 150 ° C. during high-speed rotation, and high stress is generated in the vicinity of the rotation center, particularly in the disk portion due to torsional stress or centrifugal force from the rotating shaft.
　コンプレッサーインペラーは、ターボチャージャーの要求性能に応じて種々の素材によって形成される。船舶用などの大型の用途には通常アルミニウム合金の熱間鍛造材からインペラー形状に削り出したものが使用されている。乗用車、トラックなどの自動車用や小型船舶用などの比較的小型なものは、大量生産性やコストが重視される。そのため、鋳造性の良好なＪＩＳ－ＡＣ４ＣＨ（Ａｌ－７％Ｓｉ－０．３％Ｍｇ合金）、ＡＳＴＭ－３５４．０（Ａｌ－９％Ｓｉ－１．８％Ｃｕ－０．５％Ｍｇ合金）、ＡＳＴＭ－Ｃ３５５．０（Ａｌ－５％Ｓｉ－１．３％Ｃｕ－０．５％Ｍｇ合金）等、Ｓｉを主要含有元素とした易鋳造性アルミニウム合金を、石膏型（プラスターモールド）を用いて低圧鋳造法、減圧鋳造法又は重力鋳造法などによって鋳造し、これを溶体化処理や時効処理により強化したものが広く使用されている。この基本的な製造方法は、特許文献１に詳細に開示されている。 Compressor impellers are made of various materials according to the required performance of the turbocharger. For large-scale applications such as for ships, an aluminum alloy hot forging material cut into an impeller shape is usually used. For relatively small vehicles such as passenger cars and trucks, and small ships, mass productivity and cost are important. Therefore, JIS-AC4CH (Al-7% Si-0.3% Mg alloy) with good castability, ASTM-354.0 (Al-9% Si-1.8% Cu-0.5% Mg alloy) , ASTM-C355.0 (Al-5% Si-1.3% Cu-0.5% Mg alloy), etc., using a gypsum mold (plaster mold) for easily cast aluminum alloys containing Si as the main element For example, a low-pressure casting method, a reduced pressure casting method, or a gravity casting method, which is reinforced by solution treatment or aging treatment, is widely used. This basic manufacturing method is disclosed in detail in Patent Document 1.
　近年になって、エンジンの小型化、高出力化や排気再循環量増加に伴う空気の高圧縮比化が要求される中、ターボチャージャーのより高速な回転が指向されている。しかしながら、回転数の増大によって空気の圧縮による発熱量が増加し、また排気側のタービンインペラーも同時に高温化するため、その発熱に基づく伝熱によりコンプレッサーインペラーの温度は増大する。このため、上述の従来用いられていたＳｉを主要含有元素とした易鋳造性アルミニウム合金製のコンプレッサーインペラーでは使用中に変形したり、更には疲労破壊したりする不具合が発生し易く、正常な回転の継続が不可能となることが判明した。具体的には、これらの既存のコンプレッサーインペラーでは１５０℃程度が使用可能な温度の上限であるが、上述の高速回転指向のため、２００℃程度でも使用可能なコンプレッサーインペラーの開発が強く望まれている。 In recent years, the turbocharger has been driven to rotate at higher speeds in response to demands for higher compression ratios of air accompanying the downsizing, higher output, and increased exhaust gas recirculation amount of the engine. However, since the amount of heat generated by the compression of the air increases due to the increase in the number of revolutions, and the turbine impeller on the exhaust side also increases in temperature at the same time, the temperature of the compressor impeller increases due to heat transfer based on the generated heat. For this reason, a compressor impeller made of a readily castable aluminum alloy containing Si as a main element, which has been used in the past, is likely to be deformed during use or to be subject to fatigue failure, and normal rotation. It became clear that it was impossible to continue. Specifically, these existing compressor impellers have a maximum usable temperature of about 150 ° C. However, because of the high-speed rotation orientation described above, the development of compressor impellers that can be used even at about 200 ° C. is strongly desired. Yes.
　そこで、アルミニウム合金組成をより高温強度の優れた、例えばＪＩＳ－ＡＣ１Ｂ（Ａｌ－５％Ｃｕ－０．３％Ｍｇ合金）などに変更することが考えられる。しかしながら、特許文献２に記載されているように、コンプレッサーインペラーのように複雑形状で、かつ薄肉の羽根の部分を有する場合には、ＪＩＳ－ＡＣ１Ｂなどの合金では溶湯の良好な流動性に欠け、薄肉部への湯回り不良（充填不良）が発生し易い問題点があった。 Therefore, it is conceivable to change the composition of the aluminum alloy to, for example, JIS-AC1B (Al-5% Cu-0.3% Mg alloy) having superior high-temperature strength. However, as described in Patent Document 2, in the case of a complicated shape such as a compressor impeller and a thin blade portion, an alloy such as JIS-AC1B lacks good fluidity of the molten metal, There was a problem in that poor hot water filling (filling failure) was likely to occur in the thin wall portion.
　特許文献２では上記問題点を解消すべく、湯回り性の重要視される羽根部にはＡＣ４ＣＨなどのＡｌ－Ｓｉ系の易鋳造性の合金を用い、強度の必要な回転軸に結合されるボス部からディスク部にかけてはＡＣ１ＢなどのＡｌ－Ｃｕ系の高強度の合金を用いて、これらを２回に分けて注湯して合体させ、コンプレッサーインペラーを形成する方法が提案されている。 In Patent Document 2, in order to solve the above-mentioned problem, an Al—Si based easily castable alloy such as AC4CH is used for the blade portion regarded as having a hot water property, and is coupled to a rotating shaft that requires strength. A method has been proposed in which a high-strength alloy such as AC1B, such as AC1B, is used from the boss portion to the disk portion, and these are poured in two portions and combined to form a compressor impeller.
　また、特許文献３には、羽根部には鋳造性の良好な合金を用い、応力が加わるボス部からディスク部中央部にかけては２５％Ｂを含有するアルミニウムウィスカーなどの強化材にアルミニウムを含浸させて強化した強化複合材を別途製造して用い、これらを接合してコンプレッサーインペラーを形成する方法が提案されている。 Further, in Patent Document 3, an alloy having good castability is used for the blade part, and aluminum is impregnated with a reinforcing material such as an aluminum whisker containing 25% B from the boss part to which stress is applied to the center part of the disk part. There has been proposed a method of separately manufacturing and using a reinforced composite material that has been reinforced and joining them to form a compressor impeller.
　特許文献４には、羽根部とボス部（及びディスク部）を摩擦圧接によって接合する方法が提案されている。しかしながら、これら各部に異なる材料を併用する方法では、生産性が劣りコスト増加となる問題点が残り、未だに工業化は達成されていない。 Patent Document 4 proposes a method of joining a blade part and a boss part (and a disk part) by friction welding. However, the method in which different materials are used in combination with each part still has the problem that the productivity is inferior and the cost increases, and industrialization has not yet been achieved.
　このような異なる材料を用いる問題点に鑑み、特許文献５には、Ａｌ－Ｃｕ－Ｍｇ基合金の含有元素とその組み合わせの範囲を適正化することで単一合金での鋳造を可能とし、１８０℃での耐力値を２５０ＭＰａ以上としたコンプレッサーインペラーが提案されている。特許文献６には、Ａｌ－Ｃｕ－Ｍｇ基合金の含有元素とその組み合わせの範囲を更に適正化して結晶粒径を制御することで鋳造歩留まりを改善し、２００℃での耐力値を２６０ＭＰａ以上としたコンプレッサーインペラーが提案されている。 In view of the problem of using such different materials, Patent Document 5 discloses that a single alloy can be cast by optimizing the range of elements contained in an Al—Cu—Mg based alloy and the combination thereof. A compressor impeller having a proof stress at 250 ° C. of 250 MPa or more has been proposed. Patent Document 6 discloses that the yield of casting at 200 ° C. is improved to 260 MPa or more by further improving the range of elements contained in the Al—Cu—Mg based alloy and the combination thereof to control the crystal grain size to improve the casting yield. Compressor impellers have been proposed.
　しかしながら、上記Ａｌ－Ｃｕ－Ｍｇ基合金の単一合金鋳造においては、ターボチャージャーの更なる高速回転化に伴い、２００℃付近での高温使用に対して長期間にわたって安定して耐えられることが課題となっている。また、安定した生産性の確保のために、鋳造歩留の向上も課題として残っている。 However, in the single alloy casting of the Al—Cu—Mg based alloy, it is difficult to stably withstand high temperature use near 200 ° C. for a long period of time as the turbocharger is further rotated at high speed. It has become. In addition, improvement of casting yield remains a problem in order to ensure stable productivity.
米国特許第４，５５６，５２８号明細書US Pat. No. 4,556,528 特開平１０－５８１１９号公報Japanese Patent Laid-Open No. 10-58119 特開平１０－２１２９６７号公報JP-A-10-212967 特開平１１－３４３８５８号公報Japanese Patent Laid-Open No. 11-343858 特開２００５－２０６９２７号公報JP 2005-206927 A 特開２０１２－２５９８６号公報JP 2012-25986 A
　本発明は、上記課題に鑑みてなされたものであって、２００℃程度の使用温度においても長期間にわたって安定した強度が得られ、かつ生産性に優れたアルミニウム合金（以下、「Ａｌ合金」と記す）鋳物製コンプレッサーインペラー及びその製造方法を提供することを目的とするものである。 The present invention has been made in view of the above-mentioned problems, and an aluminum alloy (hereinafter referred to as “Al alloy”) that has a stable strength over a long period of time even at a use temperature of about 200 ° C. and has excellent productivity. It is an object of the present invention to provide a cast compressor impeller and a manufacturing method thereof.
　本発明者等は、上記課題について、高い応力が加わるコンプレッサーインペラーのディスク部に着目し、ディスク部の端部における金属間化合物が微細分散する場合にディスク部強度が飛躍的に向上することを見出した。また、金属間化合物を微細分散させる製造方法を鋭意検討し、初晶アルミニウム結晶粒を微細化することが金属間化合物の微細分散にとって重要であり、このためにはＡｌ合金溶湯の冷却速度を制御すること、ならびに、コンプレッサーインペラー内における微細化粒子の分布を制御することが重要であるとの知見を得て本発明を完成するに至った。 With regard to the above problems, the present inventors have focused on the disk portion of the compressor impeller to which high stress is applied, and found that the strength of the disk portion is dramatically improved when the intermetallic compound at the end of the disk portion is finely dispersed. It was. In addition, the manufacturing method for finely dispersing the intermetallic compound is intensively studied, and it is important for the fine dispersion of the intermetallic compound to refine the primary crystal grains. For this purpose, the cooling rate of the molten Al alloy is controlled. As a result, the inventors have obtained the knowledge that it is important to control the distribution of fine particles in the compressor impeller and have completed the present invention.
　本発明は請求項１において、ボス部、複数の羽根部及びディスク部を備えるＡｌ合金鋳物製コンプレッサーインペラーにおいて、前記ボス部、複数の羽根部及び端部を除くディスク部が、Ｃｕ：１．４～３．２ｍａｓｓ％、Ｍｇ：１．０～２．０ｍａｓｓ％、Ｎｉ：０．５～２．０ｍａｓｓ％、Ｆｅ：０．５～２．０ｍａｓｓ％、Ｔｉ：０．０１～０．３５ｍａｓｓ％、Ｂ：０．００２～０．０７０ｍａｓｓ％を含有し、残部Ａｌ及び不可避的不純物からなるＡｌ合金からなり、前記ディスク部の端部が、Ｃｕ：１．４～３．２ｍａｓｓ％、Ｍｇ：１．０～２．０ｍａｓｓ％、Ｎｉ：０．５～２．０ｍａｓｓ％、Ｆｅ：０．５～２．０ｍａｓｓ％、Ｔｉ：０．００５～０．１７５ｍａｓｓ％、Ｂ：０．００１～０．０３５ｍａｓｓ％を含有し、残部Ａｌ及び不可避的不純物からなるＡｌ合金からなり、前記ディスク部の端部において、１～６μｍの円相当径を有する金属間化合物が１００００個／ｍｍ２以上存在し、且つ、６μｍを超える円相当径を有する金属間化合物が５００個／ｍｍ２以下存在することを特徴とするＡｌ合金鋳物製コンプレッサーインペラーとした。 In the first aspect of the present invention, in the compressor impeller made of an Al alloy casting including the boss portion, the plurality of blade portions, and the disk portion, the disk portion excluding the boss portion, the plurality of blade portions, and the end portion is Cu: 1.4. To 3.2 mass%, Mg: 1.0 to 2.0 mass%, Ni: 0.5 to 2.0 mass%, Fe: 0.5 to 2.0 mass%, Ti: 0.01 to 0.35 mass%, B: 0.002 to 0.070 mass%, Al alloy composed of the balance Al and inevitable impurities. The end of the disk portion has Cu: 1.4 to 3.2 mass%, Mg: 1. 0 to 2.0 mass%, Ni: 0.5 to 2.0 mass%, Fe: 0.5 to 2.0 mass%, Ti: 0.005 to 0.175 mass%, B: 0.001 to 0.035 mass% Contains Made of Al alloy and the balance Al and unavoidable impurities, at the end of the disk portion, there intermetallic compound having a circle equivalent diameter of 1 ~ 6 [mu] m is 10000 / mm 2 or more and a circle equivalent in excess of 6 [mu] m intermetallic compound having a diameter was Al alloy cast iron compressor wheel, characterized in that there 500 / mm 2 or less.
　本発明は請求項２では請求項１におけるＡｌ合金鋳物製コンプレッサーインペラーが、船舶用の大型用途に用いられ、前記ボス部の高さ、ディスク部の直径及び羽根部の高さがそれぞれ、２００～８０ｍｍ、３００～１００ｍｍ及び１８０～６０ｍｍであり、羽根先端肉厚が４．０～０．４ｍｍであり、羽根の枚数が３０～１０枚であるものとした。 According to a second aspect of the present invention, the compressor impeller made of an Al alloy casting according to the first aspect of the present invention is used for a large-sized ship application, and the height of the boss portion, the diameter of the disk portion, and the height of the blade portion are 200 to 80 mm, 300 to 100 mm, and 180 to 60 mm, the blade tip thickness was 4.0 to 0.4 mm, and the number of blades was 30 to 10.
　本発明は請求項３では請求項１におけるＡｌ合金鋳物製コンプレッサーインペラーが、自動車用などの小型用途に用いられ、前記ボス部の高さ、ディスク部の直径及び羽根部の高さがそれぞれ、１００～２０ｍｍ、１２０～２５ｍｍ、９０～５ｍｍであり、羽根先端肉厚が３．０～０．１ｍｍであり、羽根の枚数が２０～４枚であるものとした。 According to a third aspect of the present invention, the compressor impeller made of an Al alloy casting according to the first aspect of the present invention is used for small applications such as automobiles, and the height of the boss portion, the diameter of the disk portion, and the height of the blade portion are 100 It is assumed that the blade tip thickness is 3.0 to 0.1 mm, and the number of blades is 20 to 4 mm.
　本発明は請求項４では、Ｃｕ：１．４～３．２ｍａｓｓ％、Ｍｇ：１．０～２．０ｍａｓｓ％、Ｎｉ：０．５～２．０ｍａｓｓ％、Ｆｅ：０．５～２．０ｍａｓｓ％を含有し、残部Ａｌ及び不可避的不純物からなるＡｌ合金からなる７２０～７８０℃のＡｌ合金溶湯を調製し、当該Ａｌ合金溶湯に微細化剤を添加して、前記合金組成に加えてＴｉ：０．０１～０．３５ｍａｓｓ％、Ｂ：０．００２～０．０７０ｍａｓｓ％を更に含有するようにした溶湯調製工程と；石膏型とインペラーディスク面に接する面に配置された１００～２５０℃の冷やし金とで構成される製品形状を有し、溶湯流入孔が下部に設けられた石膏型が下方に、且つ、冷し金が上方に配置されるように構成される空間に、前記調製したＡｌ合金溶湯を前記溶湯流入孔から圧入する圧力鋳造法によりＡｌ合金鋳物を鋳造する鋳造工程であって、前記空間への溶湯流入孔における溶湯の流入速度を０．１２～１．００ｍ／秒とする鋳造工程と；当該Ａｌ合金鋳物を溶体化処理する溶体化処理工程と；溶体化処理したＡｌ合金鋳物を時効処理する時効処理工程と；を備えることを特徴とするＡｌ合金鋳物製コンプレッサーインペラーの製造方法とした。 According to the present invention, in claim 4, Cu: 1.4-3.2 mass%, Mg: 1.0-2.0 mass%, Ni: 0.5-2.0 mass%, Fe: 0.5-2.0 mass 720 to 780 ° C. made of an Al alloy composed of the remaining Al and inevitable impurities, and a finer is added to the molten Al alloy to add Ti: A melt preparation step further containing 0.01 to 0.35 mass%, B: 0.002 to 0.070 mass%; cooling at 100 to 250 ° C. disposed on the surface in contact with the plaster mold and the impeller disk surface In the space configured so that the gypsum mold having a product shape composed of gold and a molten metal inflow hole provided in the lower part is arranged downward and the cooling metal is arranged in the upper part, the prepared Al The molten alloy is passed through the molten metal inflow hole. A casting process for casting an Al alloy casting by a pressure casting method for press-fitting, wherein a casting flow rate of the molten metal in the molten metal inflow hole into the space is 0.12 to 1.00 m / second; A solution impregnation treatment step of solution-treating the solution; and an aging treatment step of aging treatment of the solution treatment-treated Al alloy casting.
　本発明は請求項５では請求項４において、前記鋳造工程において、ディスク部の端部の冷却速度が０．１～２００℃／秒であるものとした。 In the fifth aspect of the present invention, the cooling rate of the end of the disk portion is 0.1 to 200 ° C./second in the casting step.
　本発明は請求項６では請求項４又は５において、前記溶体化処理工程において、前記Ａｌ合金鋳物をＡｌ合金の固相線温度から５～２５℃低い温度で２時間以上熱処理するものとし、前記時効処理工程において、前記溶体化処理したＡｌ合金鋳物を１８０～２３０℃で３～３０時間熱処理するものとした。 The present invention is that in claim 6 or claim 4 or 5, in the solution treatment step, the Al alloy casting is heat-treated at a temperature lower by 5 to 25 ° C. than the solidus temperature of the Al alloy for 2 hours or more. In the aging treatment step, the solution-treated Al alloy casting was heat treated at 180 to 230 ° C. for 3 to 30 hours.
　本発明によれば、２００℃付近での高温領域においても長期間にわたって安定した耐熱強度を示し、かつ、鋳造歩留などの生産性に優れたアルミニウム合金鋳物製コンプレッサーインペラーを得ることができる。 According to the present invention, it is possible to obtain an aluminum alloy cast compressor impeller that exhibits stable heat resistance over a long period of time even in a high temperature region around 200 ° C. and is excellent in productivity such as casting yield.
本発明に係るＡｌ合金鋳物製コンプレッサーインペラーの構造の一例を示す斜視図である。It is a perspective view which shows an example of the structure of the compressor impeller made from Al alloy casting which concerns on this invention. 本発明に係るＡｌ合金鋳物製コンプレッサーインペラーの金属間化合物分布の測定箇所を示す説明図である。It is explanatory drawing which shows the measurement location of the intermetallic compound distribution of the compressor impeller made from Al alloy casting which concerns on this invention. 本発明に係るＡｌ合金鋳物製コンプレッサーインペラーの製造方法において、石膏型と冷やし金の配置、ならびに、石膏型と冷やし金とで構成される空間内に上向きに流入する溶湯の流入方向を示す説明図である。Explanatory drawing which shows the inflow direction of the molten metal which flows in upwards in the space comprised by the gypsum type | mold and cooling metal arrangement | positioning in the manufacturing method of the compressor impeller made from Al alloy casting which concerns on this invention, and a gypsum type | mold and cooling metal It is. 石膏型と冷やし金の配置、ならびに、石膏型と冷やし金とで構成される空間内に横向きに流入する溶湯の流入方向を示す説明図である。It is explanatory drawing which shows the inflow direction of the molten metal which flows into the space comprised by arrangement | positioning of a plaster mold and a cooling metal, and the space comprised by a plaster mold and a cooling metal. 石膏型と冷やし金の配置、ならびに、石膏型と冷やし金とで構成される空間内に下向きに流入する溶湯の流入方向を示す説明図である。It is explanatory drawing which shows arrangement | positioning of a plaster mold and a cooling metal, and the inflow direction of the molten metal which flows downward into the space comprised by a plaster mold and a cooling metal.
　以下に本発明の実施形態について詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail.
Ａ．本発明に係るアルミニウム合金鋳物製コンプレッサーインペラーの特徴
　本発明者等は上述の課題を解決するために種々実験検討を重ねた結果、コンプレッサーインペラーのディスク部の端部における金属間化合物の大きさ及び面密度を適正化することで２００℃程度の高温使用時においても、ディスク部の破損なく耐熱強度が長期間にわたって安定して優れるコンプレッサーインペラーが得られることを見出した。そして、Ａｌ合金組成の適正化、溶湯温度及び冷し金温度の調整による鋳造時の冷却速度の制御、コンプレッサーインペラー成形型への溶湯の流入速度の制御により、コンプレッサーインペラーのディスク部の端部における金属間化合物の大きさ及び面密度を適正化し、且つ、従来以上の鋳造歩留を達成できることを見出した。 A. Features of Compressor Impeller Made of Aluminum Alloy Casting According to the Present Invention As a result of various experiments and studies conducted by the present inventors to solve the above-mentioned problems, the size and surface of the intermetallic compound at the end of the disk portion of the compressor impeller It has been found that by optimizing the density, a compressor impeller having stable and excellent heat-resistant strength over a long period of time can be obtained even when used at a high temperature of about 200 ° C. And by optimizing the Al alloy composition, controlling the cooling speed during casting by adjusting the molten metal temperature and the cooling metal temperature, and controlling the flow rate of the molten metal into the compressor impeller mold, at the end of the disk portion of the compressor impeller It has been found that the size and surface density of the intermetallic compound can be optimized and a casting yield higher than the conventional one can be achieved.
　なお、本発明において「耐熱強度が長期間にわたって安定して優れる」とは２００℃程度での使用温度でも、変形や疲労破壊が長期間にわたって発生しないことを意味する。具体的には、２００℃、１５万ｒｐｍ×２００時間でのターボ組み付け耐久試験による破損が無いこととする。 In the present invention, “the heat resistance strength is stable and excellent over a long period of time” means that deformation and fatigue failure do not occur over a long period of time even at a use temperature of about 200 ° C. Specifically, it is assumed that there is no damage due to a turbo assembling durability test at 200 ° C. and 150,000 rpm × 200 hours.
Ｂ．Ａｌ合金鋳物製コンプレッサーインペラーの形状
　図１に本実施形態に係るアルミニウム合金鋳物製コンプレッサーインペラー（以下、単に「コンプレッサーインペラー」と記す）の形状の一例を示す。コンプレッサーインペラー１は、回転中心軸（ボス部）２と、これに一体に連なるディスク部３と、このディスク部３から突出する複数枚の薄肉の羽根４を有する。このコンプレッサーインペラー１の温度は、高速回転中には２００℃程度の高温に達し、特にディスク部端には垂直方向に大きな繰り返し応力が発生する。 B. 1. Shape of Al alloy cast compressor impeller FIG. 1 shows an example of the shape of an aluminum alloy cast compressor impeller (hereinafter simply referred to as “compressor impeller”) according to the present embodiment. The compressor impeller 1 includes a rotation center shaft (boss part) 2, a disk part 3 integrally connected to the rotation center shaft 2, and a plurality of thin blades 4 protruding from the disk part 3. The temperature of the compressor impeller 1 reaches a high temperature of about 200 ° C. during high speed rotation, and a large repetitive stress is generated in the vertical direction particularly at the end of the disk portion.
Ｃ．Ａｌ合金の組成
　次に、本発明で用いるＡｌ合金の成分組成とその限定理由について説明する。 C. Next, the composition of the Al alloy used in the present invention and the reason for its limitation will be described.
Ｃ－１．Ｃｕ、Ｍｇ：
　ＣｕとＭｇはＡｌ母相中に固溶し、固溶強化によって機械的強度を向上させる効果を有する。また、ＣｕとＭｇが共存することによって、Ａｌ２Ｃｕ、Ａｌ２ＣｕＭｇ等の析出強化による強度向上にも寄与する。但し、これらの２種の元素は凝固温度範囲を拡大する元素であるため、過剰な含有は鋳造性を劣化させる。 C-1. Cu, Mg:
Cu and Mg are dissolved in the Al matrix and have the effect of improving mechanical strength by solid solution strengthening. Further, the coexistence of Cu and Mg contributes to an improvement in strength by precipitation strengthening of Al 2 Cu, Al 2 CuMg and the like. However, since these two elements are elements that expand the solidification temperature range, excessive inclusion deteriorates the castability.
　Ｃｕ含有量が１．４ｍａｓｓ％（以下、単に「％」と記す）未満の場合、及び／又は、Ｍｇ含有量が１．０％未満の場合には、２００℃の高温において必要とされる機械的強度が得られない。一方、Ｃｕ含有量が３．２％を超える場合、及び／又は、Ｍｇ含有量が２．０％を超える場合には、コンプレッサーインペラーとしての鋳造性が劣り、特に羽根先端部への湯回りが不十分となって欠肉が発生し易くなる。以上により、Ｃｕ含有量を１．４～３．２％、かつ、Ｍｇ含有量を１．０～２．０％とする。なお、使用中の変形などの不具合を確実に防止し、かつ、鋳造時の欠肉発生を可及的に防止して工業的に好適な歩留まりを得るためには、Ｃｕ含有量を１．７～２．８％、かつ、Ｍｇ含有量を１．３～１．８％とするのが好ましい。 When the Cu content is less than 1.4 mass% (hereinafter simply referred to as “%”) and / or when the Mg content is less than 1.0%, the machine required at a high temperature of 200 ° C. Strength cannot be obtained. On the other hand, when the Cu content exceeds 3.2% and / or when the Mg content exceeds 2.0%, the castability as a compressor impeller is inferior, and particularly, the hot water around the blade tip is reduced. Insufficient thickness is likely to occur. As described above, the Cu content is set to 1.4 to 3.2%, and the Mg content is set to 1.0 to 2.0%. In order to reliably prevent defects such as deformation during use, and to prevent the occurrence of thinning during casting as much as possible to obtain an industrially suitable yield, the Cu content is set to 1.7. It is preferable that the content is 2.8% and the Mg content is 1.3-1.8%.
Ｃ－２．Ｎｉ、Ｆｅ：
　ＮｉとＦｅは、Ａｌと共に金属間化合物を形成してこれがＡｌ母相中に分散し、Ａｌ合金の高温強度を向上させる効果を奏する。そのためには、Ｎｉ含有量を０．５％以上とし、Ｆｅ含有量も０．５％以上とする。しかしながら、両元素は共に過剰に含有されると、金属間化合物が粗大化してしまうだけでなく、高温においてＣｕ２ＦｅＡｌ７やＣｕ３ＮｉＡｌ６を形成してＡｌ母相中の固溶Ｃｕ量を低減させ、かえって強度を低下させてしまう。また後述するが、これら金属間化合物の粗大物がディスク部の端部に存在すると、ディスク部の端部に加わる繰り返し応力によってこれら金属間化合物を起点としてコンプレッサーインペラーが破損する。そのため、Ｎｉ含有量を２．０％以下、かつ、Ｆｅ含有量も２．０％以下とする。以上により、Ｎｉ含有量を０．５～２．０％、かつ、Ｆｅ含有量を０．５～２．０％とするものである。なお、Ｎｉ含有量を０．５～１．４％、Ｆｅ含有量を０．７～１．５％とするのが好ましい。上記好ましい範囲の下限値は製造の際のバラツキを低減させることにより工業的に安定的な量産をする上での目安値であり、上限値は効果が飽和しこれ以上の含有は無駄となる含有量の目安値である。 C-2. Ni, Fe:
Ni and Fe form an intermetallic compound together with Al, which is dispersed in the Al matrix, and has the effect of improving the high temperature strength of the Al alloy. For that purpose, the Ni content is 0.5% or more, and the Fe content is also 0.5% or more. However, when both elements are contained excessively, not only the intermetallic compound becomes coarse, but also Cu 2 FeAl 7 and Cu 3 NiAl 6 are formed at a high temperature to reduce the amount of solid solution Cu in the Al matrix. Will reduce the strength. As will be described later, if these intermetallic compounds are coarse at the end of the disk portion, the compressor impeller is damaged starting from these intermetallic compounds due to repeated stress applied to the end of the disk portion. Therefore, the Ni content is 2.0% or less and the Fe content is 2.0% or less. As described above, the Ni content is 0.5 to 2.0% and the Fe content is 0.5 to 2.0%. It is preferable that the Ni content is 0.5 to 1.4% and the Fe content is 0.7 to 1.5%. The lower limit value of the above preferred range is a guide value for industrially stable mass production by reducing variation during production, and the upper limit value is a content that is saturated and the content beyond this is wasted This is a guideline for the amount.
Ｃ－３．Ｔｉ、Ｂ：
　ＴｉおよびＢは、鋳造時の初晶アルミニウム結晶粒の成長抑制効果を奏するため、鋳造中の凝固組織を微細化して溶湯補給性を改善し、湯回り性を改善する効果を発揮するため添加される。ボス部、複数の羽根部、端部を除くディスク部においてＴｉ含有量が０．０１％未満、及び／又は、Ｂ含有量が０．００２％未満、また、ディスク部の端部においてＴｉ含有量が０．００５％未満、及び／又は、Ｂ含有量が０．００１％未満の場合には、上記効果が十分に得られない。一方、ボス部、複数の羽根部、端部を除くディスク部においてＴｉ含有量が０．３５％を超え、及び／又は、Ｂ含有量が０．０７０％超を超え、また、ディスク部の端部においてＴｉ含有量が０．１７５％を超え、及び／又は、Ｂ含有量が０．０３５％を超える場合には、微細化剤粒子の凝集体が発生し、この凝集体を起点として疲労亀裂が発生する。なお、各部におけるＴｉ含有量が０．３５％を超えると、Ａｌと共に数１０～数１００μｍの大きさの粗大な金属間化合物を形成して回転時に疲労亀裂の起点となり、コンプレッサーインペラーとしての信頼性を低下させる。以上により、ボス部、複数の羽根部、端部を除くディスク部においては、Ｔｉ含有量を０．０１～０．３５％、かつ、Ｂ含有量を０．００２～０．０７０％とし、好ましくはＴｉ含有量を０．１５～０．３０％、かつ、Ｂ含有量を０．００３～０．０６０％とする。また、ディスク部の端部においては、Ｔｉ含有量を０．００５～０．１７５％、かつ、Ｂ含有量を０．００１～０．０３５％とし、好ましくはＴｉ含有量を０．０１０～０．１６５％、かつ、Ｂ含有量を０．００２～０．０３３％とする。 C-3. Ti, B:
Ti and B are added to exert the effect of suppressing the growth of primary aluminum crystal grains during casting, so that the solidification structure during casting is refined to improve the replenishability of the molten metal and the effect of improving the meltability. The Ti content is less than 0.01% and / or B content is less than 0.002% in the disk part excluding the boss part, the plurality of blade parts, and the end part, and Ti content in the end part of the disk part. Is less than 0.005% and / or when the B content is less than 0.001%, the above effects cannot be obtained sufficiently. On the other hand, the Ti content exceeds 0.35% and / or the B content exceeds 0.070% in the disk part excluding the boss part, the plurality of blade parts, and the end part, and the end of the disk part When the Ti content exceeds 0.175% and / or the B content exceeds 0.035% in the part, aggregates of finer particles are generated, and fatigue cracks start from the aggregates. Will occur. When the Ti content in each part exceeds 0.35%, a coarse intermetallic compound with a size of several tens to several hundreds of μm is formed together with Al, which becomes a starting point of fatigue cracks during rotation, and reliability as a compressor impeller Reduce. As described above, in the disk part excluding the boss part, the plurality of blade parts, and the end part, the Ti content is 0.01 to 0.35% and the B content is 0.002 to 0.070%, preferably Has a Ti content of 0.15 to 0.30% and a B content of 0.003 to 0.060%. Further, at the end of the disk portion, the Ti content is 0.005 to 0.175% and the B content is 0.001 to 0.035%, preferably the Ti content is 0.010 to 0%. 165% and B content is 0.002 to 0.033%.
　Ａｌ合金の不可避的不純物として、０．３０％程度以下のＳｉ、ならびに、それぞれが０．２０％程度以下のＺｎ、Ｍｎ、Ｃｒなどが含有されていても、コンプレッサーインペラーの特性を損なうことがないので許容される。 Even if Si of about 0.30% or less and Zn, Mn, Cr or the like of about 0.20% or less are contained as inevitable impurities of the Al alloy, the characteristics of the compressor impeller are not impaired. So acceptable.
Ｄ．金属間化合物
　本発明で用いるアルミニウム合金は、従来のＡｌ－Ｓｉ系アルミニウム合金鋳物の製造方法に準じて、石膏型（プラスターモールド）を使用し圧力鋳造法（低圧鋳造法、減圧鋳造法又は差圧鋳造法）によってコンプレッサーインペラー形状に鋳造される。 D. Intermetallic compound The aluminum alloy used in the present invention is a pressure casting method (low pressure casting method, reduced pressure casting method or differential pressure method) using a gypsum mold (plaster mold) in accordance with a conventional method for producing an Al—Si aluminum alloy casting. By casting method) into a compressor impeller shape.
　この石膏型を使用した圧力鋳造法では、各鋳物内部の金属間化合物の分布に関し、ディスク部の端部において、１～６μｍの円相当径を有する金属間化合物が１００００個／ｍｍ２以上存在し、且つ、６μｍを超える円相当径を有する金属間化合物が５００個／ｍｍ２以下存在するように製造条件を制御する必要がある。 The pressure casting method using a gypsum mold, relates the distribution of the intermetallic compounds within each casting, at the end of the disk portion, there was intermetallic compounds with a circle equivalent diameter of 1 ~ 6 [mu] m is 10000 / mm 2 or more and, it is necessary to control the production conditions so that the intermetallic compound having a circle equivalent diameter of greater than 6μm exists 500 / mm 2 or less.
　本発明者等はコンプレッサーインペラーの破損挙動について検討した結果、コンプレッサーインペラーの回転の加減速により発生する高い繰り返し垂直応力がディスク部の端部に加わり、ディスク部の端部に存在する６μｍを超える円相当径を有する粗大金属間化合物が亀裂の起点となりこれら亀裂が進展することで破損することを見出した。また、更なる検討により、ディスク部の端部において、６μｍを超える円相当径を有する金属間化合物の面密度が５００個／ｍｍ２以下である場合には、これら金属間化合物を起点とした亀裂発生が抑制されること、ならびに、例え亀裂が発生してもその伝播が抑制されることが判明した。また、ディスク部の端部において、１～６μｍの円相当径を有する金属間化合物が１００００個／ｍｍ２以上存在すれば、上記粗大金属間化合物の生成が抑制されることも判明した。 As a result of examining the failure behavior of the compressor impeller, the present inventors have applied a high repetitive vertical stress generated by the acceleration / deceleration of the rotation of the compressor impeller to the end of the disk part, and the circle exceeding 6 μm existing at the end of the disk part. It was found that a coarse intermetallic compound having an equivalent diameter becomes a starting point of cracks and breaks as these cracks progress. Further, when the surface density of the intermetallic compound having a circle-equivalent diameter exceeding 6 μm is 500 pieces / mm 2 or less at the end of the disk portion by further study, cracks originating from these intermetallic compounds It has been found that the occurrence is suppressed and that the propagation is suppressed even if a crack occurs. Also, at the end of the disk portion, if any intermetallic compounds with a circle equivalent diameter of 1 ~ 6 [mu] m is 10000 / mm 2 or more, it has also been found that the generation of the coarse intermetallic compound is suppressed.
　ここで、金属間化合物の生成量は一般的な鋳造条件下においては組成によって決定される。「一般的な鋳造条件下」とは、低圧鋳造による冷却速度であり、具体的には０．１～２００℃／秒である。また、鋳造後の熱処理による金属間化合物の変化について検討したところ、鋳造時に生成する金属間化合物の大きさはその後の熱処理に大きく影響を受けないことが判明した。従って、鋳造時において微細な金属間化合物を多量に生成させることにより、その後の熱処理によっても粗大金属間化合物の生成を抑制可能となる。 Here, the amount of intermetallic compound produced is determined by the composition under general casting conditions. “General casting conditions” refers to a cooling rate by low-pressure casting, specifically 0.1 to 200 ° C./second. Moreover, when the change of the intermetallic compound by the heat processing after casting was examined, it turned out that the magnitude | size of the intermetallic compound produced | generated at the time of casting is not influenced greatly by subsequent heat processing. Therefore, by producing a large amount of fine intermetallic compounds at the time of casting, it is possible to suppress the formation of coarse intermetallic compounds by subsequent heat treatment.
　１～６μｍの円相当径を有する金属間化合物の面密度を１００００個／ｍｍ２以上とする理由は、以下の通りである。１μｍ未満の円相当径を有する金属間化合物は、コンプレッサーインペラー強度に影響を与えない。また、１～６μｍの円相当径を有する金属間化合物の面密度が１００００個／ｍｍ２未満の場合は、６μｍを超える円相当径を有する金属間化合物の生成が促進され、生成する６μｍを超える円相当径を有する金属間化合物を起点に亀裂が発生してしまう。なお、上記面密度の上限値は特に限定するものではないが、Ａｌ合金の組成や製造条件によって定まるものであり、本発明においては３００００個／ｍｍ２を上限値とする。 The reason why the surface density of the intermetallic compound having a circle-equivalent diameter of 1 to 6 μm is 10,000 pieces / mm 2 or more is as follows. An intermetallic compound having an equivalent circle diameter of less than 1 μm does not affect the compressor impeller strength. In addition, when the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm is less than 10,000 / mm 2 , the production of the intermetallic compound having an equivalent circle diameter exceeding 6 μm is promoted and exceeds 6 μm to be generated. Cracks start from an intermetallic compound having an equivalent circle diameter. The upper limit value of the surface density is not particularly limited, but is determined by the composition of Al alloy and manufacturing conditions. In the present invention, the upper limit value is 30000 pieces / mm 2 .
　次に、６μｍを超える円相当径を有する金属間化合物の面密度を５００個／ｍｍ２以下とする理由は、以下の通りである。６μｍを超える円相当径を有する金属間化合物を対象とするのは、上述の通りである。また、この面密度が５００個／ｍｍ２を超える場合には、これらの金属間化合物同士の離間距離が近くなり、亀裂の伝播が進行する。なお、上記面密度の下限値は特に限定するものではなく、Ａｌ合金の組成や製造条件によって定まるものであるが、本発明においては１００個／ｍｍ２が好ましく、０個／ｍｍ２が最も好ましい。 Next, the reason why the surface density of the intermetallic compound having a circle-equivalent diameter exceeding 6 μm is 500 pieces / mm 2 or less is as follows. As described above, an intermetallic compound having an equivalent circle diameter exceeding 6 μm is targeted. Moreover, when this areal density exceeds 500 piece / mm < 2 >, the separation distance of these intermetallic compounds becomes close, and propagation of a crack advances. The lower limit value of the surface density is not particularly limited, and is determined by the composition and production conditions of the Al alloy. In the present invention, 100 pieces / mm 2 is preferable, and 0 pieces / mm 2 is most preferable. .
　本発明において生成する金属間化合物としては、Ａｌ－Ｆｅ－Ｎｉ－Ｃｕ系、Ａｌ－Ｆｅ－Ｃｕ－Ｎｉ－Ｍｇ系、Ａｌ－Ｃｕ－Ｍｇ系、Ａｌ－Ｃｕ系、Ａｌ－Ｃｕ－Ｍｇ－Ｓｉ系、Ａｌ－Ｃｕ－Ｆｅ系、Ａｌ－Ｎｉ系、Ａｌ－Ｍｇ系、Ｍｇ－Ｓｉ系などの金属間化合物が挙げられる。また、生成する金属間化合物の円相当径は、Ａｌ合金の組成や製造条件によって異なるが、０．１～２０．０μｍの範囲に分布する。なお、円相当径とは円相当直径をいう。 Examples of the intermetallic compound produced in the present invention include Al—Fe—Ni—Cu, Al—Fe—Cu—Ni—Mg, Al—Cu—Mg, Al—Cu, and Al—Cu—Mg—Si. And intermetallic compounds such as Al—Cu—Fe, Al—Ni, Al—Mg, and Mg—Si. Further, the equivalent circle diameter of the intermetallic compound to be generated varies in the range of 0.1 to 20.0 μm, although it varies depending on the composition of Al alloy and the manufacturing conditions. The equivalent circle diameter means the equivalent circle diameter.
Ｅ．ディスク部の端部における微細化剤の成分量の制御
　上記の金属間化合物の分布を制御する上で、初晶アルミニウム結晶粒の大きさを制御することは重要である。この理由として、上記金属間化合物は初晶アルミニウム結晶粒の粒界にて発生するためである。初晶アルミニウム結晶粒の大きさを制御するためには、微細化剤の成分量及び後述する冷却速度が重要な制御因子となる。 E. Control of the component amount of the micronizing agent at the end of the disk part In controlling the distribution of the intermetallic compound, it is important to control the size of the primary aluminum crystal grains. This is because the intermetallic compound is generated at the grain boundary of primary aluminum crystal grains. In order to control the size of primary aluminum crystal grains, the component amount of the micronizing agent and the cooling rate described later are important control factors.
　ディスク部の端部におけるＴｉ及びＢの適切な成分量としては、Ｔｉ：０．００５～０．１７５％、Ｂ：０．００１～０．０３５％である。この微細化剤含有量を達成するためには、溶湯調製工程時にＡｌ、Ｔｉ及びＢから成る微細化剤を添加し、溶湯調整工程後のアルミニウム合金溶湯におけるＴｉ及びＢの成分量をＴｉ：０．０１～０．３５％、Ｂ：０．００２～０．０７０％とする。また、石膏型と冷やし金とで構成される製品形状の空間を、溶湯流入孔が下部に設けられた石膏型が下方に、且つ、冷し金が上方に配置されるように構成する。そして、調製したＡｌ合金溶湯は、溶湯流入孔から前記空間に圧入される。更に、この空間への溶湯流入孔における溶湯の流入速度を０．１２～１．００ｍ／秒とする。以上の要件を満たすように、調整した溶湯を上記空間に圧入する圧力鋳造法によりＡｌ合金鋳物を鋳造する鋳造工程が採用される。 Appropriate component amounts of Ti and B at the end of the disk portion are Ti: 0.005 to 0.175% and B: 0.001 to 0.035%. In order to achieve this refiner content, a refiner composed of Al, Ti and B is added during the melt preparation step, and the Ti and B component amounts in the molten aluminum alloy after the melt preparation step are set to Ti: 0. 0.01 to 0.35%, B: 0.002 to 0.070%. Further, the product-shaped space composed of the gypsum mold and the cooling metal is configured such that the gypsum mold with the molten metal inflow hole provided in the lower part is disposed below and the cooling metal is disposed above. And the prepared Al alloy molten metal is press-fitted into the space through the molten metal inflow hole. Furthermore, the inflow speed of the molten metal in the molten metal inflow hole into this space is set to 0.12 to 1.00 m / sec. A casting process for casting an Al alloy casting by a pressure casting method in which the adjusted molten metal is press-fitted into the space so as to satisfy the above requirements is employed.
　上記各要件を規定する理由として、上記空間内における溶湯流動の影響により溶湯調製工程時の微細化剤量の一部のみがディスク部の端部に到達することが挙げられる。これは、慣性の法則に従い圧力鋳造時において移動する溶湯に、微細化剤粒子の移動が追従しないことに起因することが本発明者等によって確認されている。この点に関して、下記に詳述する。 The reason for prescribing each of the above requirements is that only a part of the amount of the micronizing agent during the melt preparation process reaches the end of the disk part due to the influence of the melt flow in the space. It has been confirmed by the present inventors that this is caused by the movement of the finer particles not following the molten metal that moves during pressure casting in accordance with the law of inertia. This will be described in detail below.
　溶湯調製工程時に微細化剤としてＡｌ、Ｔｉ及びＢから成る微細化剤を添加するが、溶湯調整工程後のアルミニウム合金溶湯におけるＴｉ成分量が０．０１％未満、及び又は、Ｂ成分量が０．００２％未満の場合には、初晶アルミニウム結晶粒が粗大化し、それにより粒界の金属間化合物も粗大化して、Ａｌ合金材の強度が低下する。また、溶湯調整工程後のアルミニウム合金溶湯におけるＴｉ成分量が０．３５％を超え、及び又は、Ｂ成分量が０．０７０％を超える場合には、粗大なＴｉＢ２凝集体が発生し、これが破壊起点となる。従って、微細化剤添加による溶湯調整工程後におけるアルミニウム合金溶湯のＴｉ及びＢの成分量はＴｉ：０．０１～０．３５％、かつ、Ｂ：０．００２～０．０７０％とする。 A refiner composed of Al, Ti, and B is added as a refiner during the melt preparation step, but the Ti component amount in the molten aluminum alloy after the melt adjustment step is less than 0.01% and / or the B component amount is 0. If it is less than 0.002%, the primary aluminum crystal grains become coarse, and the intermetallic compounds at the grain boundaries also become coarse, thereby reducing the strength of the Al alloy material. Further, when the Ti component amount in the molten aluminum alloy after the molten metal adjustment step exceeds 0.35% and / or the B component amount exceeds 0.070%, coarse TiB 2 aggregates are generated, which It becomes the starting point of destruction. Therefore, the component amounts of Ti and B in the molten aluminum alloy after the step of adjusting the molten metal by adding the micronizing agent are set to Ti: 0.01 to 0.35% and B: 0.002 to 0.070%.
　次に、石膏型と冷やし金とで構成される製品形状の空間について説明する。図３に示すように、石膏型７を下方に冷やし金６を上方に配置して、これらによって構成される製品形状の空間１０を形成する。そして、空間１０へ溶湯を流入させるための溶湯流入孔８を、石膏型７側の下部に設けるものである。溶湯は、溶湯流入方向９に沿って図中下側から上側に向かって溶湯流入孔８から空間１０に流入して空間１０内に充填される。 Next, a product-shaped space composed of a plaster mold and a chiller will be described. As shown in FIG. 3, the plaster mold 7 is cooled downward, and the metal 6 is placed upward to form a product-shaped space 10 constituted by these. And the molten metal inflow hole 8 for making a molten metal flow in into the space 10 is provided in the lower part by the side of the gypsum mold 7. The molten metal flows into the space 10 from the molten metal inflow hole 8 along the molten metal inflow direction 9 from the lower side to the upper side in the figure and is filled in the space 10.
　空間１０をこのような構成としない場合には、コンプレッサーインペラーの円周方向における不均一な凝固に起因するコンプレッサーインペラー高速回転時のバランス性が悪化し、また、鋳造機の複雑化に伴う操業上の装置制約が生じる。例えば、図４に示すように、石膏型７と冷やし金６を水平に配置して、これらによって構成される製品形状の空間１０を形成する場合には、溶湯は、溶湯流入方向９に沿って図中右側から左側に向かって溶湯流入孔８から横向きに空間１０に流入して空間１０内に充填される。この場合には、空間１０内に流入した溶湯は、空間１０の下側から上側へと充填されていきながら凝固が進行する。従って、コンプレッサーインペラーの周方向において、空間１０の下側にあった周方向部分は早期に凝固し、上側にあった周方向部分は遅れて凝固することになり、周方向における均一な凝固状態が得られない。コンプレッサーインペラーにおいて周方向の不均一凝固は軸部の曲がりを発生させ、高速回転させた際のバランス不良となる。 When the space 10 is not configured as described above, the balance at the time of high speed rotation of the compressor impeller due to non-uniform solidification in the circumferential direction of the compressor impeller is deteriorated, and operation due to the complexity of the casting machine is deteriorated. This causes device restrictions. For example, as shown in FIG. 4, when the gypsum mold 7 and the cooling metal 6 are arranged horizontally to form a product-shaped space 10 constituted by these, the molten metal is along the molten metal inflow direction 9. From the right side to the left side of the figure, the molten metal inflow hole 8 flows laterally into the space 10 and fills the space 10. In this case, the molten metal flowing into the space 10 is solidified while being filled from the lower side to the upper side of the space 10. Therefore, in the circumferential direction of the compressor impeller, the circumferential portion below the space 10 is solidified early, and the circumferential portion located above is solidified later, and a uniform solidification state in the circumferential direction is obtained. I can't get it. In a compressor impeller, uneven solidification in the circumferential direction causes bending of the shaft portion, resulting in poor balance when rotated at high speed.
　これに代わって、例えば、図５に示すように、石膏型７を上方に冷やし金６を下方に配置して、これらによって構成される製品形状の空間１０を形成する場合は、溶湯は、溶湯流入方向９に沿って図中上側から下側に向かって溶湯流入孔８から空間１０に流入して空間１０内に充填される。この場合には、炉内の溶湯を空間１０内へ充填するための管（ストーク）の配管が複雑化する。すなわち、圧力鋳造法による炉内より鉛直上向きに排出された溶湯が鉛直下向きに流れるようにストークを配管する必要が生じる。この場合には、ストークの配管が複雑化するのを避けられない。更に、ストークの距離が長尺化するため、溶湯温度の低下や溶湯流の圧損増加により鋳造が困難となる。 Instead of this, for example, as shown in FIG. 5, when the gypsum mold 7 is cooled upward and the metal 6 is disposed downward to form a product-shaped space 10 constituted by these, Along the inflow direction 9 from the upper side to the lower side in the figure, the molten metal inflow hole 8 flows into the space 10 and fills the space 10. In this case, the piping of the pipe (stalk) for filling the molten metal in the furnace into the space 10 becomes complicated. That is, it is necessary to pipe the stalk so that the molten metal discharged vertically upward from the inside of the furnace by the pressure casting method flows vertically downward. In this case, it is inevitable that the Stoke piping is complicated. Further, since the distance of the stalk becomes longer, casting becomes difficult due to a decrease in the melt temperature and an increase in the pressure loss of the melt flow.
　図３に示すように石膏型７と冷やし金６を配置して製品形状の空間１０を形成する場合には、図４の配置の場合のような周方向における不均一な凝固状態や、図５の配置の場合のようなストークの複雑化、溶湯温度の低下、溶湯流の圧損増加の不具合が発生しない。 When the gypsum mold 7 and the cooling metal 6 are arranged to form the product-shaped space 10 as shown in FIG. 3, the uneven solidified state in the circumferential direction as in the arrangement of FIG. The problem of complication of stalk, lowering of the molten metal temperature, and increased pressure loss of the molten metal flow as in the case of the arrangement of is not generated.
　更に、溶湯流入孔における溶湯の流入速度は、ディスク部端における微細化剤の含有量を制御する上で重要な因子である。前述の通り、ディスク部の端部に到達するＴｉ及びＢから成る微細化剤粒子の含有量は溶湯調製工程時における微細化剤粒子の含有量に比べて減少する。これは、慣性の法則に従い、圧力鋳造時において移動する溶湯に微細化剤粒子の移動が追従しないことに起因する。溶湯流入孔における溶湯の流入速度が１．００ｍ／秒を超える場合には、溶湯の流入速度が速すぎて、慣性で移動する微細化剤粒子の移動が溶湯の流入速度に追従できない程度が増すため、結晶粒微細化に必要な量の微細化剤粒子がディスク部の端部に到達できない。一方、溶湯流入孔における溶湯の流入速度が０．１２ｍ／秒未満の場合には、溶湯の流入速度が遅すぎて、溶湯がストークを通って石膏型に到達するまでの時間が長くなり溶湯温度が低下して凝固不良を引き起こす。なお、溶湯流入孔における溶湯の流入速度は、好ましくは０．２０～０．８５ｍ／秒である。 Furthermore, the flow rate of the molten metal in the molten metal inflow hole is an important factor in controlling the content of the micronizing agent at the end of the disk portion. As described above, the content of the finer particles composed of Ti and B reaching the end of the disk portion is reduced as compared with the content of the finer particles in the melt preparation step. This is because the movement of the finer particles does not follow the molten metal that moves during pressure casting in accordance with the law of inertia. When the molten metal inflow speed in the molten metal inflow hole exceeds 1.00 m / sec, the molten metal inflow speed is too high, and the degree of movement of the finer particles that move by inertia cannot follow the molten metal inflow speed increases. For this reason, the amount of finer particles necessary for crystal grain refinement cannot reach the end of the disk portion. On the other hand, when the inflow speed of the melt in the melt inflow hole is less than 0.12 m / sec, the inflow speed of the melt is too slow, and the time until the melt reaches the gypsum mold through the stalk becomes longer. Lowers and causes poor coagulation. The molten metal inflow rate in the molten metal inflow hole is preferably 0.20 to 0.85 m / sec.
Ｆ．ディスク部の端部における冷却速度の制御
　更に、上述のような金属間化合物分布を得るためには、コンプレッサーホイールにおけるディスク部の端部における冷却速度の制御が必要となる。具体的には、溶湯温度を７２０～７８０℃に制御し、コンプレッサーディスク面に接する面に配置された冷やし金（チルプレート）の温度を１００～２５０℃に制御するものである。このように、溶湯温度と冷やし金の温度を規定することにより、ディスク部の端部の冷却速度が０．１～２００℃／秒の好適な範囲に調整される。冷却速度が０．１℃／秒未満では、初晶アルミニウム結晶粒が粗大となって、粒界に生成する金属間化合物が粗大となる。また、冷却速度の低下によって引け巣が発生し、生産性が低下する。一方、冷却速度が２００℃／秒を超えると、製品形状の空間内で早期に凝固することから湯回り不良が生じて製品形状が確保できなくなる。ディスク部の端部における冷却速度の更に好ましい範囲は３～１５０℃／秒である。 F. Control of the cooling rate at the end of the disk part Further, in order to obtain the intermetallic compound distribution as described above, it is necessary to control the cooling rate at the end of the disk part in the compressor wheel. Specifically, the molten metal temperature is controlled to 720 to 780 ° C., and the temperature of a chill plate (chill plate) disposed on the surface in contact with the compressor disk surface is controlled to 100 to 250 ° C. In this way, by regulating the temperature of the molten metal and the temperature of the cooling metal, the cooling rate at the end of the disk portion is adjusted to a suitable range of 0.1 to 200 ° C./second. When the cooling rate is less than 0.1 ° C./second, primary aluminum crystal grains become coarse, and intermetallic compounds generated at the grain boundaries become coarse. Further, shrinkage nests are generated due to a decrease in cooling rate, and productivity is reduced. On the other hand, when the cooling rate exceeds 200 ° C./sec, the product shape cannot be ensured because a hot water defect occurs due to early solidification in the product shape space. A more preferable range of the cooling rate at the end of the disk portion is 3 to 150 ° C./second.
　溶湯の温度が７２０℃未満では、圧入された溶湯が製品形状の空間内で早期に凝固することから湯回り不良が生じて製品形状が確保できなくなる。一方、溶湯の温度が７８０℃を超えると、溶湯の酸化が進行して水素ガスの吸収によるポロシティ発生数の増大及び酸化物の増加により溶湯品質が悪化し、製品強度を確保することが困難となる。 If the temperature of the molten metal is less than 720 ° C., the molten metal that has been injected solidifies in the product shape space at an early stage, resulting in poor hot water production and the product shape cannot be secured. On the other hand, when the temperature of the molten metal exceeds 780 ° C., the oxidation of the molten metal progresses, the increase in the number of generated porosity due to the absorption of hydrogen gas and the increase in the oxide deteriorate the molten metal quality, and it is difficult to ensure the product strength. Become.
　また、冷やし金の温度が１００℃未満では、凝固の進行が速すぎて湯回り不良が生じることとなる。一方、冷やし金の温度が２５０℃を超えると、冷やし金からの凝固が遅くなり冷却速度の低下によって初晶アルミニウム結晶粒が粗大となって、粒界に生成する金属間化合物が粗大となる。また、冷し金の温度が２５０℃を超えると、石膏型と冷し金の間に湯が差し込む、所謂バリ不良も発生する。 Also, if the temperature of the cooling metal is less than 100 ° C., the progress of solidification is too fast, resulting in poor hot water. On the other hand, when the temperature of the chilled metal exceeds 250 ° C., solidification from the chilled metal is delayed, and the primary aluminum crystal grains become coarse due to a decrease in the cooling rate, resulting in coarse intermetallic compounds generated at the grain boundaries. In addition, when the temperature of the cooling metal exceeds 250 ° C., a so-called burr defect occurs in which hot water is inserted between the gypsum mold and the cooling metal.
　本発明では石膏型の予熱温度は特に限定するものではないが、２００～３５０℃に制御するのが好ましい。石膏型の予熱温度が２００℃未満では、型の先端に溶湯が充填される前に凝固が進行してしまうため湯回り不良が生じて製品形状が確保できなくなる。一方、石膏型の予熱温度が３５０℃を超えると、石膏型内での凝固が遅くなり引け巣不良が発生することとなる。 In the present invention, the preheating temperature of the gypsum mold is not particularly limited, but it is preferably controlled to 200 to 350 ° C. If the preheating temperature of the gypsum mold is less than 200 ° C., solidification proceeds before the molten metal is filled at the tip of the mold, resulting in poor hot water and a product shape cannot be secured. On the other hand, when the preheating temperature of the gypsum mold exceeds 350 ° C., solidification in the gypsum mold is delayed and a shrinkage defect is generated.
　なお、冷やし金の材質は、熱伝導率が高い銅及び銅合金が好ましいが、鉄、ステンレス鋼なども使用できる。また、冷やし金の温度調整には、冷やし金内部に水などの冷却媒体を通して鋳造中の過熱を抑制する機構を用いるのが好ましい。 The material of the cooling metal is preferably copper or copper alloy having high thermal conductivity, but iron, stainless steel, etc. can also be used. In order to adjust the temperature of the cooling metal, it is preferable to use a mechanism that suppresses overheating during casting through a cooling medium such as water inside the cooling metal.
Ｇ．製造方法
　次に、本発明に係るＡｌ合金鋳物製コンプレッサーインペラーの製造方法について説明する。この製造方法は、溶湯調製工程、鋳造工程及び熱処理工程から構成される。 G. Manufacturing Method Next, a manufacturing method of the Al alloy casting compressor impeller according to the present invention will be described. This manufacturing method includes a melt preparation process, a casting process, and a heat treatment process.
溶湯調製工程：
　通常の方法に従って、上述のＡｌ合金組成となるように各成分元素を加えて加熱溶解し、脱水素ガス処理及び介在物除去処理などの溶湯処理を行なう。そして、最終的な溶湯温度が７２０～７８０℃となるように温度が調整される。また、溶湯中の水素ガス量を調整する。溶湯中の水素ガス量の調整方法としては、回転ガス吹込み装置が用いられるが、これに限定されるものではない。 Melt preparation process:
In accordance with a normal method, each component element is added and melted by heating so as to achieve the above-described Al alloy composition, and molten metal treatment such as dehydrogenation gas treatment and inclusion removal treatment is performed. Then, the temperature is adjusted so that the final molten metal temperature is 720 to 780 ° C. Also, the amount of hydrogen gas in the molten metal is adjusted. As a method for adjusting the amount of hydrogen gas in the molten metal, a rotary gas blowing device is used, but is not limited thereto.
鋳造工程：
　鋳造工程では、７２０～７８０℃に温度調整された溶湯を、石膏型を用いた圧力鋳造法によってコンプレッサーインペラー形状に鋳造する。上述のように、ディスク面に接する面に配置する冷やし金の温度は１００℃～２５０℃に調整される。石膏型と冷し金とで構成される製品形状の空間については、図３に示すように、石膏型を下方に冷やし金を上方に配置して、これらによって構成される製品形状の空間を形成する。そして、空間へ溶湯を溶湯流入方向に沿って流入させるための溶湯流入孔を、石膏型７側の下部に設ける。空間への溶湯流入孔における溶湯の流入速度は、０．１２～１．００ｍ／秒に調整される。このようにして、調製したＡｌ合金溶湯を空間に圧入する圧力鋳造法によりＡｌ合金鋳物を鋳造する。 Casting process:
In the casting process, the molten metal whose temperature is adjusted to 720 to 780 ° C. is cast into a compressor impeller shape by a pressure casting method using a gypsum mold. As described above, the temperature of the cooling metal disposed on the surface in contact with the disk surface is adjusted to 100 ° C. to 250 ° C. As shown in FIG. 3, the product-shaped space composed of the gypsum mold and the cooling metal is arranged with the gypsum mold downward and the cooling metal disposed upward to form a product-shaped space composed of these. To do. And the molten metal inflow hole for making a molten metal flow in into a space along a molten metal inflow direction is provided in the lower part by the side of the gypsum mold 7. The inflow speed of the molten metal in the molten metal inflow hole to the space is adjusted to 0.12 to 1.00 m / sec. Thus, an Al alloy casting is cast by the pressure casting method in which the prepared molten Al alloy is press-fitted into the space.
熱処理工程：
　鋳造されたＡｌ合金鋳物は、熱処理工程にかけられる。熱処理工程は、溶体化処理工程と時効処理工程とで構成される。熱処理工程により、Ｃｕによる固溶強化；ＣｕとＭｇによる析出強化；ＡｌとＦｅとによって、ならびに、ＡｌとＮｉとによって形成される金属間化合物による分散強化；を有効に活用することができる。 Heat treatment process:
The cast Al alloy casting is subjected to a heat treatment process. The heat treatment step includes a solution treatment step and an aging treatment step. By the heat treatment step, solid solution strengthening by Cu; precipitation strengthening by Cu and Mg; dispersion strengthening by an intermetallic compound formed by Al and Fe and by Al and Ni can be effectively utilized.
溶体化処理工程：
　溶体化処理は、固相線温度から５～２５℃低い温度範囲で行うのが好ましい。本発明において好適に用いられるＡｌ合金においては、固相線温度から５～２５℃低い温度範囲は５１０～５３０℃となる。固相線温度から５～２５℃低い温度範囲を超える温度では、結晶粒界の第２相が溶融する危険性が高まり、強度確保が困難となる。一方、この温度範囲未満の温度では、元素拡散が十分に進まずに十分な溶体化が行われないこととなる。また、溶体化処理時間は２時間以上とするのが好ましい。２時間未満では元素拡散が十分に進まずに十分な溶体化が行われないこととなる。元素拡散による溶体化には２時間以上あれば特に時間を定めないが、量産を考慮すると３０時間以下とすることが好ましい。 Solution treatment process:
The solution treatment is preferably performed in a temperature range 5 to 25 ° C. lower than the solidus temperature. In the Al alloy preferably used in the present invention, the temperature range 5 to 25 ° C. lower than the solidus temperature is 510 to 530 ° C. If the temperature exceeds a temperature range lower by 5 to 25 ° C. than the solidus temperature, the risk of melting the second phase of the crystal grain boundary increases, and it becomes difficult to ensure the strength. On the other hand, at temperatures below this temperature range, element diffusion does not proceed sufficiently and sufficient solution is not achieved. The solution treatment time is preferably 2 hours or longer. If it is less than 2 hours, element diffusion does not proceed sufficiently and sufficient solution is not achieved. The solution time by element diffusion is not particularly limited as long as it is 2 hours or longer, but is preferably 30 hours or less in consideration of mass production.
時効処理：
　時効処理は、１８０～２３０℃で３～３０時間熱処理するのが好ましく、１９０～２１０℃で５～２０時間熱処理するのがより好ましい。処理温度が１８０℃未満の場合や、処理時間が３時間未満の場合には、強度向上のための析出強化が不十分な場合がある。一方、処理温度が２３０℃を超える場合や、処理時間が３０時間を超える場合には、形成された析出相が粗大化（過時効）して十分な強化作用が得られないとともに、Ｃｕの固溶強化能が低下する。 Aging treatment:
The aging treatment is preferably heat treatment at 180 to 230 ° C. for 3 to 30 hours, more preferably heat treatment at 190 to 210 ° C. for 5 to 20 hours. When the treatment temperature is less than 180 ° C. or when the treatment time is less than 3 hours, precipitation strengthening for improving the strength may be insufficient. On the other hand, when the processing temperature exceeds 230 ° C. or when the processing time exceeds 30 hours, the formed precipitated phase becomes coarse (over-aged) and a sufficient strengthening action cannot be obtained. The solution strengthening ability decreases.
Ｈ．コンプレッサーホイール形状
　本発明に係るコンプレッサーインペラーの形状や寸法、ならびに、羽根の枚数は特に限定されるものではなく、船舶用の大型用途や自動車などの小型用途など多くの用途のものに適用することができる。例えば、船舶用の大型用途の場合には、ボス部の高さ、ディスク部の直径及び羽根部の高さは、それぞれ、２００～８０ｍｍ、３００～１００ｍｍ、１８０～６０ｍｍ、好ましくは１８０～１００ｍｍ、２６０～１２０ｍｍ、１６０～９０ｍｍであり、羽根先端肉厚は４．０～０．４ｍｍ、好ましくは３．０～０．６ｍｍである。羽根の枚数は、３０～１０枚、好ましくは２６～１２枚である。また、自動車などの小型用途の場合には、ボス部の高さ、ディスク部の直径及び羽根部の高さは、それぞれ、１００～２０ｍｍ、１２０～２５ｍｍ、９０～５ｍｍ、好ましくは９０～２５ｍｍ、１００～３０ｍｍ、８０～８ｍｍであり、羽根先端肉厚は３．０～０．１ｍｍ、好ましくは２．０～０．２ｍｍである。羽根の枚数は、２０～４枚、好ましくは１８～６枚である。 H. Compressor wheel shape The shape and dimensions of the compressor impeller according to the present invention and the number of blades are not particularly limited, and can be applied to many uses such as large ships for ships and small applications such as automobiles. it can. For example, in the case of large-scale applications for ships, the height of the boss part, the diameter of the disk part and the height of the blade part are 200 to 80 mm, 300 to 100 mm, 180 to 60 mm, preferably 180 to 100 mm, respectively. 260 to 120 mm and 160 to 90 mm, and the blade tip thickness is 4.0 to 0.4 mm, preferably 3.0 to 0.6 mm. The number of blades is 30 to 10, preferably 26 to 12. In the case of small applications such as automobiles, the height of the boss, the diameter of the disk and the height of the blades are 100 to 20 mm, 120 to 25 mm, 90 to 5 mm, preferably 90 to 25 mm, respectively. The blade tip thickness is 3.0 to 0.1 mm, preferably 2.0 to 0.2 mm. The number of blades is 20 to 4, preferably 18 to 6.
　以下において、実施例により本発明を更に詳細に説明する。 Hereinafter, the present invention will be described in more detail with reference to examples.
第１の実施例（本発明例１～７及び比較例１～２０）
　表１の成分欄に示す組成のＡｌ合金を、通常の溶湯処理を施して溶解し、溶湯を表１に示す温度に調整した溶湯調製工程にかけた。溶湯調製工程では、表１の成分欄に示す組成のＡｌ合金１５０ｋｇを溶解して溶湯を得た。次いで、回転ガス吹込み装置を用いてローター回転数４００ｒｐｍ、気体流量２．５Ｎｍ３／時間の条件にて、アルゴンガスを溶湯中に３０分間吹き込み脱ガス処理を実施した。その後、溶湯全体を１時間鎮静保持し除滓した。除滓後に、表１の溶湯調製後における微細化剤の成分量欄に示すＴｉ及びＢの成分量となるよう、溶湯調整工程時に微細化剤を溶湯中に添加した。 First Example (Invention Examples 1 to 7 and Comparative Examples 1 to 20)
The Al alloy having the composition shown in the component column of Table 1 was melted by performing a normal molten metal treatment, and subjected to a molten metal preparation step in which the molten metal was adjusted to the temperature shown in Table 1. In the melt preparation step, 150 kg of an Al alloy having the composition shown in the component column of Table 1 was melted to obtain a melt. Subsequently, degassing was performed by blowing argon gas into the molten metal for 30 minutes under the conditions of a rotor rotation speed of 400 rpm and a gas flow rate of 2.5 Nm 3 / hour using a rotating gas blowing device. Thereafter, the entire molten metal was sedated for 1 hour and removed. After stripping, the micronizing agent was added to the molten metal during the melt adjustment step so that the amounts of Ti and B shown in the component amount column of the micronizing agent after the melt preparation in Table 1 were obtained.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　次いで、溶湯調製工程で調製したＡｌ合金溶湯は、２５０℃に調整された石膏型と、インペラーディスク面に接する面に配置され、表１の温度に調整された銅製冷やし金とで構成される所定空間に、下方の石膏型の下部（図３）、横方の石膏型の横部（図４）又は上方の石膏型の上部（図５）に設けられた溶湯流入孔から加圧注入する低圧鋳造法によりＡｌ合金鋳物を作製した。このＡｌ合金鋳物コンプレッサーインペラーは、ディスク部直径４０ｍｍ、ボス部高さ４０ｍｍ、羽根数１２枚、羽根部高さ３５ｍｍ、羽根先端肉厚０．３ｍｍの形状を有する乗用車ターボチャージャー用コンプレッサーインペラーである。石膏型と冷やし金により構成される空間への溶湯流入方向は表１で示すものとし、空間への溶湯流入孔における溶湯の流入速度を表１に示すものとして、溶湯を該空間へ加圧注入し、Ａｌ合金鋳物全体の凝固が完了するまで加圧保持した。 Next, the Al alloy molten metal prepared in the molten metal preparing step is a predetermined structure constituted by a gypsum mold adjusted to 250 ° C. and a copper cooling metal that is arranged on the surface in contact with the impeller disk surface and adjusted to the temperature shown in Table 1. Low pressure that is injected into the space through a molten metal inflow hole provided in the lower part of the lower plaster mold (FIG. 3), the lateral part of the lateral plaster mold (FIG. 4) or the upper part of the upper plaster mold (FIG. 5). An Al alloy casting was produced by a casting method. This Al alloy cast compressor impeller is a compressor impeller for a passenger car turbocharger having a disk part diameter of 40 mm, a boss part height of 40 mm, 12 blades, a blade part height of 35 mm, and a blade tip thickness of 0.3 mm. The direction of the molten metal flowing into the space composed of the plaster mold and the cooling metal is shown in Table 1, and the molten metal inflow rate into the space is shown in Table 1. The molten metal is injected into the space under pressure. The pressure was maintained until solidification of the entire Al alloy casting was completed.
　上記Ａｌ合金鋳物を石膏型から取り外した後、５３０℃で８時間の溶体化処理を施し、その後、２００℃で２０時間の時効処理を施した。以上のようにして、Ａｌ合金鋳物製コンプレッサーインペラー試料を作製した。 After the Al alloy casting was removed from the gypsum mold, a solution treatment was performed at 530 ° C. for 8 hours, and then an aging treatment was performed at 200 ° C. for 20 hours. As described above, a compressor impeller sample made of an Al alloy casting was produced.
　上記のようにして作製した各試料について、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度、同端部における６μｍを超える円相当径を有する金属間化合物の面密度、ディスク部の端部における微細化剤（Ｔｉ、Ｂ）の成分量、ディスク部の端部以外の部位における微細化剤（Ｔｉ、Ｂ）の成分量、高温特性（耐久試験評価）、ならびに、生産性（鋳造歩留評価）を、以下のようにして評価した。 For each sample produced as described above, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion, the surface of the intermetallic compound having an equivalent circle diameter exceeding 6 μm at the end. Density, amount of component of finer (Ti, B) at the end of the disk part, amount of component of finer (Ti, B) at a part other than the end of the disk part, high temperature characteristics (durability test evaluation), and The productivity (casting yield evaluation) was evaluated as follows.
１．金属間化合物の面密度の測定
　ディスク部の端部における金属間化合物の大きさと面密度を求めるため、試料を中心軸に沿って線で切断した。図２に、コンプレッサーインペラーの中心軸５の片側の断面を示す。この断面において、ディスク部の端部３１を切り出した後に研磨し、光学顕微鏡により倍率１００倍で撮像した。なお、ディスク部の端部３１とは、コンプレッサーインペラーのディスク部の外周より半径方向に沿った中心軸５までの長さにおける外周から２０％までのディスク部を指す。前記の撮像画像を画像解析装置に取り込んだ後に、１～６μｍの円相当径を有する金属間化合物の面密度、ならびに、６μｍを超える円相当径を有する金属間化合物の面密度を測定した。なお、測定箇所は任意に１０箇所を選択し、これらの算術平均値をもって面密度とした。また、各測定箇所の測定視野面積は１ｍｍ２とした。結果を表２に示す。 1. Measurement of surface density of intermetallic compound In order to obtain the size and surface density of the intermetallic compound at the end of the disk portion, the sample was cut along a line along the central axis. FIG. 2 shows a cross section of one side of the central shaft 5 of the compressor impeller. In this cross section, the end 31 of the disk portion was cut out and then polished, and imaged with an optical microscope at a magnification of 100 times. The end portion 31 of the disk portion refers to a disk portion that is 20% from the outer periphery in the length from the outer periphery of the disk portion of the compressor impeller to the central axis 5 along the radial direction. After capturing the captured image in an image analyzer, the surface density of an intermetallic compound having an equivalent circle diameter of 1 to 6 μm and the surface density of an intermetallic compound having an equivalent circle diameter exceeding 6 μm were measured. In addition, 10 measurement locations were arbitrarily selected, and the arithmetic average value was used as the surface density. The measurement field area of each measurement point was 1 mm 2. The results are shown in Table 2.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
２．微細化剤の成分量の測定
　ディスク部の端部、ならびに、当該端部以外の部位における微細化剤含有量を測定した。図２に示すディスク部の端部３１、ボス部２、羽根部４、端部を除くディスク部３２より分析試料をそれぞれ５ｇ採取し、ＩＣＰ発光分析装置にてＴｉ量及びＢ量を分析した。表２におけるディスク部の端部以外の部位における微細化剤成分量とは、ボス部、羽根部、端部を除くディスク部における各微細化剤成分量を求め、これらの平均値として算出した。これらの結果を表２に示す。 2. Measurement of component amount of finer agent The finer agent content at the end of the disk part and at parts other than the end part was measured. 5 g of each sample was collected from the end 31 of the disk part, the boss part 2, the blade part 4, and the disk part 32 excluding the end part shown in FIG. 2, and the Ti amount and B amount were analyzed by an ICP emission analyzer. The amount of the finer component in the part other than the end of the disk part in Table 2 was calculated as an average value of the respective finerizer components in the disk part excluding the boss part, the blade part, and the end part. These results are shown in Table 2.
３．高温特性
　耐久試験（ターボ組み付け、１５００００ｒｐｍ×２００時間、出側温度２００℃）により高温疲労強度を評価した。結果を表２に示す。表２に記載の耐久性試験評価では、試験中に破断した場合を「×」、破断はしなかったが亀裂が発生した場合を「△」、破断も亀裂も発生せず健全な状態のままの場合を「○」とした。 3. High-temperature fatigue strength was evaluated by an endurance test (turbo assembly, 150,000 rpm × 200 hours, outlet temperature 200 ° C.). The results are shown in Table 2. In the durability test evaluation shown in Table 2, “×” indicates that the sample was broken during the test, “△” indicates that the sample was not broken but cracked, and the sample was not broken or cracked and remained in a healthy state. In this case, “○” was assigned.
４．鋳造歩留評価
　各例について１０００個の試料を作製して、鋳造歩留評価を行なった。各試料における検査項目は、湯回り及び引け巣の外観不良検査と、Ｘ線検査によって内部のブローホールを検出する内部不良検査とした。全試料のうち湯回り不良品の割合（％）、引け巣不良品の割合（％）及び内部不良品の割合（％）を求めた。そして、１００％からこれら不良品の割合の合計を差し引いた割合を良品割合（％）とした。良品割合が、９０％未満である場合を「×」（現行品以下）、９０％以上９５％未満である場合を「△」（現行品同等）、９５％以上１００％以下である場合を「○」（現行品より大幅改善）とした。結果を表２に示す。 4). Casting Yield Evaluation 1000 samples were prepared for each example, and the casting yield was evaluated. The inspection items in each sample were an external defect inspection of the hot water and shrinkage nest and an internal defect inspection in which an internal blowhole was detected by X-ray inspection. Of all the samples, the ratio (%) of defective hot water, the ratio (%) of defective shrinkage nests, and the ratio (%) of internal defective products were determined. And the ratio which deducted the sum total of the ratio of these inferior goods from 100% was made into the non-defective product ratio (%). The case where the non-defective product ratio is less than 90% is “x” (current product or less), the case of 90% or more and less than 95% is “△” (equivalent to the current product), and the case of 95% or more and 100% or less is “ ○ ”(significant improvement over the current product). The results are shown in Table 2.
　本発明例１～７では、ディスク部の端部における、１～６μｍの円相当径を有する金属間化合物及び６μｍを超える円相当径を有する金属間化合物の面密度、ならびに、ディスク部の端部と当該端部以外の部位における微細化剤含有量が、規定の範囲内であることから、高温特性及び鋳造歩留が共に良好であった。 In Invention Examples 1 to 7, the surface density of the intermetallic compound having a circle-equivalent diameter of 1 to 6 μm and the intermetallic compound having a circle-equivalent diameter exceeding 6 μm at the end of the disk portion, and the end of the disk portion Since the finer agent content in the region other than the end portion is within the specified range, both the high temperature characteristics and the casting yield were good.
　比較例１では、冷やし金の温度が高く、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度が小さく、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、ディスク部の端部で破断して高温特性に劣り、また、また、ボス部における引け巣不良が多発し鋳造歩留が大きく低下した。 In Comparative Example 1, the surface density of the intermetallic compound having a high temperature of the cooling metal, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion is small, and the surface density of the intermetallic compound having an equivalent circle diameter exceeding 6 μm Was big. As a result, the disk portion was broken at the end portion and inferior in the high temperature characteristics. Further, the shrinkage defect in the boss portion was frequently generated, and the casting yield was greatly reduced.
　比較例２では、冷やし金の温度が低く、ディスク部における湯回りの外観不良が多発し鋳造歩留が低下した。 In Comparative Example 2, the temperature of the cooling metal was low, the appearance of hot water around the disk portion frequently occurred, and the casting yield decreased.
　比較例３では、溶湯温度が低くなった。その結果、羽根部における湯回りの外観不良と引け巣の外観不良が多発して鋳造歩留が大幅に低下し、また、羽根部にて亀裂が発生して高温特性に劣った。 In Comparative Example 3, the molten metal temperature was low. As a result, poor appearance around the hot water in the blade portion and poor appearance of the shrinkage nest occurred frequently, and the casting yield was greatly reduced, and cracks occurred in the blade portion, resulting in poor high temperature characteristics.
　比較例４では、溶湯温度が高く冷却速度が低下したため、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度が小さくなった。その結果、ボス部における引け巣の外観不良が多発して鋳造歩留が大幅に低下し、また、ディスク部の端部にて亀裂が発生して高温特性に劣った。 In Comparative Example 4, since the molten metal temperature was high and the cooling rate was reduced, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion was reduced. As a result, the appearance defect of the shrinkage cavities frequently occurred in the boss portion, the casting yield was greatly reduced, and cracks occurred at the end of the disk portion, resulting in poor high temperature characteristics.
　比較例５では、Ｃｕ成分が少なく高温特性は良好であるが、羽根部における湯回り不良が多発し鋳造歩留が低下した。 In Comparative Example 5, there were few Cu components and the high temperature characteristics were good, but poor hot water in the blades occurred frequently, resulting in a decrease in casting yield.
　比較例６では、Ｍｇ成分が少なく、ボス部で亀裂が発生して高温特性に劣った。 In Comparative Example 6, the Mg component was small, cracks occurred at the boss portion, and the high temperature characteristics were inferior.
　比較例７では、Ｆｅ成分が少なく、羽根部で亀裂が発生して高温特性に劣った。 In Comparative Example 7, the Fe component was small, cracks occurred in the blade portion, and the high temperature characteristics were inferior.
　比較例８では、Ｎｉ成分が少なく、ディスク部で破断して高温特性に劣った。 In Comparative Example 8, the Ni component was small, and the disk portion was broken and inferior in high temperature characteristics.
　比較例９では、溶湯調製時における微細化剤（Ｂ）の成分量が少ないため、ディスク部の端部、ディスク部の端部以外の部位におけるＴｉ及びＢの成分量が低下した。このため、結晶粒微細化効果が不十分となり、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度が小さく、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、羽根部における湯回りの外観不良が多発して鋳造歩留が大幅に低下し、また、ディスク部で破断して高温特性に劣った。 In Comparative Example 9, since the component amount of the micronizing agent (B) at the time of preparing the molten metal was small, the component amounts of Ti and B at the end portion of the disk portion and the portions other than the end portion of the disk portion were reduced. For this reason, the crystal grain refining effect becomes insufficient, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion is small, and the surface of the intermetallic compound having an equivalent circle diameter exceeding 6 μm. The density was great. As a result, the appearance of hot water around the blades frequently occurred, the casting yield was greatly reduced, and the discs were broken and inferior in high temperature characteristics.
　比較例１０では、Ｃｕ成分が多く、ディスク部で破断して高温特性に劣った。 In Comparative Example 10, the Cu component was large, and the disk portion was broken and inferior in high temperature characteristics.
　比較例１１では、Ｍｇ成分が多く高温特性は良好であるが、羽根部における湯回り不良が多発し鋳造歩留が低下した。 In Comparative Example 11, there were many Mg components and the high temperature characteristics were good, but poor hot water in the blades occurred frequently, resulting in a decrease in casting yield.
　比較例１２では、Ｆｅ成分が多く、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、ディスク部で亀裂が発生して高温特性に劣った。 In Comparative Example 12, the surface density of the intermetallic compound having a large amount of Fe component and having a circle-equivalent diameter exceeding 6 μm was large. As a result, cracks occurred in the disk portion and the high temperature characteristics were inferior.
　比較例１３では、Ｎｉ成分が多く、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、ディスク部亀裂が発生して高温特性に劣った。 In Comparative Example 13, the surface density of the intermetallic compound having a large Ni component and having an equivalent circle diameter exceeding 6 μm was large. As a result, the disk portion cracked and the high temperature characteristics were inferior.
　比較例１４では、溶湯調製時におけるＴｉ及びＢの成分量が多く、且つ、空間型（石膏型と冷やし金とで構成される製品形状を有する空間をいう、以下同じ）への溶湯の流入速度が速いため、ディスク部の端部以外の部位におけるＴｉ及びＢの成分量が多くなった。その結果、ボス部において破断して高温特性に劣り、また、空間型内での溶湯が乱流化し、内部不良が多発して鋳造歩留が大幅に低下した。 In Comparative Example 14, the flow rate of the molten metal into the space type (a space having a product shape composed of a gypsum mold and a chiller, the same applies hereinafter) at the time of preparing the molten metal is large. , The amount of components of Ti and B in parts other than the end of the disk part increased. As a result, the boss part was broken and inferior in high temperature characteristics, and the molten metal in the space mold became turbulent, resulting in frequent internal defects and a significant reduction in casting yield.
　比較例１５では、溶湯調製時におけるＴｉ及びＢの成分量は規定範囲内だが、空間型への溶湯の流入速度が速いため、ディスク部の端部におけるＴｉ及びＢの成分量が少なかった（０％）。このため、結晶粒微細化効果が不十分となり、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度が小さく、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、ディスク部において破断して高温特性に劣り、また、空間型内での溶湯が乱流化し、内部不良が多発して鋳造歩留が大幅に低下した。 In Comparative Example 15, the amounts of Ti and B components at the time of preparing the molten metal were within the specified range, but the amount of Ti and B components at the end of the disk portion was small because the flow rate of the molten metal into the space type was fast (0 %). For this reason, the crystal grain refining effect becomes insufficient, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion is small, and the surface of the intermetallic compound having an equivalent circle diameter exceeding 6 μm. The density was great. As a result, the disk portion was broken and inferior in high temperature characteristics, and the molten metal in the space mold became turbulent, resulting in frequent internal defects and a significant reduction in casting yield.
　比較例１６では、溶湯調製時におけるＴｉ及びＢの成分量が多いため、ディク部の端部及びディスク部の端部以外の部位におけるＴｉ及びＢの成分量が多くなった。その結果、微細化剤粒子の凝集体が発生し、ディスク部で破断して高温特性に劣った。 In Comparative Example 16, the amount of Ti and B components at the time of preparing the molten metal was large, so the amount of Ti and B components in the portions other than the end of the disc portion and the end of the disc portion increased. As a result, an agglomerate of finer agent particles was generated, which was broken at the disk portion and inferior in high temperature characteristics.
　比較例１７では、石膏型への溶湯の流入速度が遅く、石膏型に溶湯が到達する過程にて溶湯温度が低下した。その結果、羽根部における湯回りの外観不良が多発して鋳造歩留が大幅に低下し、また、羽根部にて亀裂が発生して高温特性に劣った。 In Comparative Example 17, the flow rate of the molten metal into the gypsum mold was slow, and the melt temperature decreased in the process of reaching the gypsum mold. As a result, the appearance defect of the hot water around the blades frequently occurred, the casting yield was greatly reduced, and cracks occurred at the blades, resulting in poor high temperature characteristics.
　比較例１８では、石膏型への溶湯の流入速度が速く、慣性で移動する微細化剤粒子の移動が溶湯の流入速度に追従できない程度が増した。そのため、ディスク部の端部におけるＴｉの含有量が少なく、ディスク部の端部に十分な微細化剤粒子が到達しなかった。その結果、結晶粒が微細化せず、金属間化合物が粗大となり、ディスク部の端部で亀裂が発生し高温特性に劣った。また、空間型内での溶湯が乱流化し、内部不良が多発して鋳造歩留が大幅に低下した。 In Comparative Example 18, the inflow rate of the molten metal into the gypsum mold was fast, and the degree to which the movement of the micronizer particles moving by inertia could not follow the inflow rate of the molten metal increased. For this reason, the Ti content at the end of the disk portion is small, and sufficient finer particles do not reach the end of the disk portion. As a result, the crystal grains were not refined, the intermetallic compound became coarse, cracks occurred at the end of the disk portion, and the high temperature characteristics were inferior. Moreover, the molten metal in the space mold became turbulent, resulting in frequent internal defects and a significant reduction in casting yield.
　比較例１９では、空間型への溶湯流入方向が横向きであり、コンプレッサーインペラーの周方向において不均一凝固が発生した。その結果、軸ブレの起因によってボス部で亀裂が発生して高温特性に劣った。また、空間型内への溶湯充填が不均一となり、内部不良が多発して鋳造歩留が大幅に低下した。 In Comparative Example 19, the molten metal inflow direction into the space type was horizontal, and non-uniform solidification occurred in the circumferential direction of the compressor impeller. As a result, cracks occurred at the boss due to shaft blurring, resulting in poor high temperature characteristics. Moreover, the filling of the molten metal into the space mold became non-uniform, resulting in frequent internal defects, and the casting yield was greatly reduced.
　比較例２０では、空間型への溶湯流入方向が下向き、石膏型に溶湯が到達する過程にて溶湯温度が低下した。その結果、ディスク部における湯回りの外観不良が多発して鋳造歩留が大幅に低下し、また、ディスク部にて亀裂が発生して高温特性に劣った。 In Comparative Example 20, the melt flow direction into the space mold was downward, and the melt temperature decreased in the process of reaching the gypsum mold. As a result, the appearance of hot water in the disk portion frequently occurred and the casting yield was greatly reduced, and cracks occurred in the disk portion, resulting in poor high temperature characteristics.
第２の実施例（本発明例８～１８及び比較例２１～２６）
　表３の成分欄に示す組成のＡｌ合金を、通常の溶湯処理を施して溶解し、溶湯を表３に示す温度に調整した溶湯調製工程にかけた。溶湯調製工程では、表３の成分欄に示す組成のＡｌ合金１５０ｋｇを溶解して溶湯を得た。次いで、回転ガス吹込み装置を用いてローター回転数４００ｒｐｍ、気体流量２．５Ｎｍ３／ｈの条件にて、アルゴンガスを溶湯中に２０分間吹き込み脱ガス処理を実施した。その後、溶湯全体を１時間鎮静保持し除滓した。除滓後に、表３の溶湯調製後における微細化剤の成分量欄に示すＴｉ及びＢから成る微細化剤を溶湯中に添加した。 Second Example (Invention Examples 8 to 18 and Comparative Examples 21 to 26)
The Al alloy having the composition shown in the component column of Table 3 was melted by performing a normal molten metal treatment, and subjected to a molten metal preparation step in which the molten metal was adjusted to the temperature shown in Table 3. In the molten metal preparation step, 150 kg of an Al alloy having the composition shown in the component column of Table 3 was melted to obtain a molten metal. Subsequently, degassing was performed by blowing argon gas into the molten metal for 20 minutes under the conditions of a rotor rotation speed of 400 rpm and a gas flow rate of 2.5 Nm 3 / h using a rotating gas blowing device. Thereafter, the entire molten metal was sedated for 1 hour and removed. After stripping, a refiner composed of Ti and B shown in the component amount column of the refiner after preparation of the melt in Table 3 was added to the melt.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　次いで、溶湯調製工程で調製したＡｌ合金溶湯は、２２０℃に調整された石膏型と、インペラーディスク面に接する面に配置され、表３の温度に調整された銅製冷やし金とで構成される所定空間に加圧注入する低圧鋳造法によりＡｌ合金鋳物を作製した。このＡｌ合金鋳物コンプレッサーインペラーは、ディスク部直径８０ｍｍ、ボス部高さ７０ｍｍ、羽根数１４枚、羽根部高さ６０ｍｍ、羽根先端肉厚０．４ｍｍの形状を有するトラックターボチャージャー用コンプレッサーインペラーである。図３に示すように、石膏型と冷やし金により構成される空間は、溶湯流入孔が下部に設けられた石膏型が下方に、且つ、冷し金が上方に配置されるように構成され、空間への溶湯流入方向は上方向とした。また、空間への溶湯流入孔における溶湯流入速度を０．７５ｍ／秒として溶湯を空間内に加圧注入し、Ａｌ合金鋳物全体の凝固が完了するまで加圧保持した。 Next, the Al alloy molten metal prepared in the molten metal preparing step is a predetermined structure composed of a gypsum mold adjusted to 220 ° C. and a copper chiller arranged on the surface in contact with the impeller disk surface and adjusted to the temperature shown in Table 3. An Al alloy casting was produced by a low pressure casting method in which pressure was injected into the space. This Al alloy casting compressor impeller is a compressor impeller for a truck turbocharger having a disk portion diameter of 80 mm, a boss portion height of 70 mm, a blade number of 14 pieces, a blade portion height of 60 mm, and a blade tip thickness of 0.4 mm. As shown in FIG. 3, the space constituted by the gypsum mold and the cooling metal is configured such that the gypsum mold in which the molten metal inflow hole is provided in the lower part is disposed below and the cooling metal is disposed above, The direction of the molten metal flowing into the space was upward. Further, the molten metal inflow rate into the space was set to 0.75 m / second, and the molten metal was pressurized and injected into the space, and the pressure was maintained until solidification of the entire Al alloy casting was completed.
　上記Ａｌ合金鋳物を石膏型から取り外した後、表３に示す条件で溶体化処理を施し、その後、同じく表３に示す条件で時効処理を施した。以上のようにして、Ａｌ合金鋳物製コンプレッサーインペラー試料を作製した。 After the Al alloy casting was removed from the gypsum mold, it was subjected to a solution treatment under the conditions shown in Table 3, and then subjected to an aging treatment under the same conditions as shown in Table 3. As described above, a compressor impeller sample made of an Al alloy casting was produced.
　上記のようにして作製した各試料について、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度、同端部における６μｍを超える円相当径を有する金属間化合物の面密度、ディスク部の端部における微細化剤（Ｔｉ、Ｂ）の成分量、ディスク部の端部以外の部位における微細化剤（Ｔｉ、Ｂ）の成分量、高温特性（耐久試験評価）、ならびに、生産性（鋳造歩留評価）を、第１の実施例と同じに評価した。結果を表４に示す。なお、高温特性については、第１の実施例における評価にて健全（○）だったものについて、同じ条件で（ターボ組み付け、１５００００ｒｐｍ、出側温度２００℃）、更に１００時間試験して全３００時間までの試験を実施した。このような３００時間までの試験においても健全だったものを「◎」とした。 For each sample produced as described above, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion, the surface of the intermetallic compound having an equivalent circle diameter exceeding 6 μm at the end. Density, amount of component of finer (Ti, B) at the end of the disk part, amount of component of finer (Ti, B) at a part other than the end of the disk part, high temperature characteristics (durability test evaluation), and The productivity (casting yield evaluation) was evaluated in the same manner as in the first example. The results are shown in Table 4. In addition, about the high temperature characteristic, about what was healthy ((circle)) in the evaluation in a 1st Example on the same conditions (turbo assembly | attachment, 150,000 rpm, outlet temperature 200 degreeC), and also tested for 100 hours, all 300 hours Tests up to were carried out. In this test up to 300 hours, what was sound was designated as “◎”.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　本発明例８～１８では、ディスク部の端部における、１～６μｍの円相当径を有する金属間化合物及び６μｍを超える円相当径を有する金属間化合物の面密度、ならびに、ディスク部の端部と当該端部以外の部位における微細化剤の成分量が、規定の範囲内であることから、高温特性及び鋳造歩留が共に良好であった。 In Examples 8 to 18 of the present invention, the surface density of the intermetallic compound having a circle-equivalent diameter of 1 to 6 μm and the intermetallic compound having a circle-equivalent diameter exceeding 6 μm at the end of the disk portion, and the end of the disk portion Since the component amount of the micronizing agent in the region other than the end portion is within the specified range, both the high temperature characteristics and the casting yield were good.
　これに対して比較例２１では、溶湯温度が低く、羽根部における湯回り外観不良が多発し鋳造歩留が低下し、また、羽根部にて亀裂が発生し高温特性に劣った。 On the other hand, in Comparative Example 21, the molten metal temperature was low, the appearance of hot water around the blade portion was frequently generated, the casting yield was lowered, and cracks were generated at the blade portion, resulting in poor high temperature characteristics.
　比較例２２では、溶湯温度が高く冷却速度が低下したため、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度が小さく、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、ボス部における引け巣の外観不良が多発して鋳造歩留が大幅に低下し、また、ディスク部で破断して高温特性に劣った。 In Comparative Example 22, since the molten metal temperature was high and the cooling rate was reduced, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion was small, and the intermetallic compound having an equivalent circle diameter exceeding 6 μm The surface density of was large. As a result, the appearance defect of the shrinkage cavity in the boss part frequently occurred, the casting yield was greatly reduced, and the disk part was broken and inferior in high temperature characteristics.
　比較例２３では、冷やし金の温度が低く、ディスク部における湯回り不良が多発し鋳造歩留が低下し、また、湯回り不良部を起因とした亀裂がディスクに発生し高温特性に劣った。 In Comparative Example 23, the temperature of the cooling metal was low, hot water failure in the disk portion occurred frequently, the casting yield was lowered, and cracks due to the hot water failure portion were generated in the disk, resulting in poor high temperature characteristics.
　比較例２４では、冷やし金の温度が高く、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度が小さく、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、ディスク部にて破断が発生し、高温特性が劣った。 In Comparative Example 24, the surface density of the intermetallic compound having a high temperature of the cooling metal, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion is small, and the surface density of the intermetallic compound having an equivalent circle diameter exceeding 6 μm Was big. As a result, the disk portion was broken and the high temperature characteristics were inferior.
　比較例２５では溶体化処理工程が実施されず、比較例２６では時効処理工程が実施されなかった。その結果、いずれもディスク部で破断し高温特性に劣った。 In Comparative Example 25, no solution treatment step was performed, and in Comparative Example 26, an aging treatment step was not performed. As a result, all of them were broken at the disk portion and inferior in high temperature characteristics.
第３の実施例（本発明例１９～２８及び比較例２７～３２）
　表５の成分欄に示す組成のＡｌ合金を、通常の溶湯処理を施して溶解し、溶湯を表５に示す温度に調製する溶湯調製工程にかけた。溶湯調製工程では、表５の成分欄に示す組成のＡｌ合金２００ｋｇを溶解して溶湯を得た。次いで、回転ガス吹込み装置を用いてローター回転数４００ｒｐｍ、気体流量２．５Ｎｍ３／時間の条件にて、アルゴンガスを溶湯中に４０分間吹き込み脱ガス処理を実施した。その後、溶湯全体を１時間半鎮静保持し除滓した。除滓後に、表５の溶湯調製後における微細化剤の成分量欄に示すＴｉ及びＢから成る微細化剤を溶湯中に添加した。 Third Example (Invention Examples 19 to 28 and Comparative Examples 27 to 32)
The Al alloy having the composition shown in the component column of Table 5 was subjected to a normal molten metal treatment to be melted and subjected to a molten metal preparation step for preparing the molten metal at a temperature shown in Table 5. In the melt preparation step, 200 kg of an Al alloy having the composition shown in the component column of Table 5 was melted to obtain a melt. Next, degassing was performed by blowing argon gas into the molten metal for 40 minutes under the conditions of a rotor rotation speed of 400 rpm and a gas flow rate of 2.5 Nm 3 / hour using a rotating gas blowing device. Thereafter, the entire molten metal was sedated for 1 hour and a half, and then removed. After stripping, a refiner composed of Ti and B shown in the component amount column of the refiner after preparation of the melt in Table 5 was added to the melt.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　次いで、溶湯調製工程で調製したＡｌ合金溶湯は、２２０℃に調整された石膏型と、インペラーディスク面に接する面に配置され、表５の温度に調整された銅製冷やし金とで構成される所定空間に加圧注入する低圧鋳造法によりＡｌ合金鋳物を作製した。このＡｌ合金鋳物コンプレッサーインペラーは、ディスク部直径１５０ｍｍ、ボス部高さ１６０ｍｍ、羽根数１６枚、羽根部高さ１２０ｍｍ、羽根先端肉厚０．６ｍｍの形状を有する船舶ターボチャージャー用コンプレッサーインペラーである。図３に示すように、石膏型と冷やし金により構成される空間は、溶湯流入孔が下部に設けられた石膏型が下方に、且つ、冷し金が上方に配置されるように構成され、空間への溶湯流入方向は上方向とした。また、空間への溶湯流入孔における溶湯流入速度を０．９５ｍ／秒として溶湯を空間内に加圧注入し、Ａｌ合金鋳物全体の凝固が完了するまで加圧保持した。 Next, the Al alloy molten metal prepared in the molten metal preparing step is a predetermined structure composed of a gypsum mold adjusted to 220 ° C. and a copper chiller arranged on the surface in contact with the impeller disk surface and adjusted to the temperature shown in Table 5. An Al alloy casting was produced by a low pressure casting method in which pressure was injected into the space. This Al alloy casting compressor impeller is a compressor impeller for a marine turbocharger having a disk portion diameter of 150 mm, a boss portion height of 160 mm, a blade number of 16 pieces, a blade portion height of 120 mm, and a blade tip thickness of 0.6 mm. As shown in FIG. 3, the space constituted by the gypsum mold and the cooling metal is configured such that the gypsum mold in which the molten metal inflow hole is provided in the lower part is disposed below and the cooling metal is disposed above, The direction of the molten metal flowing into the space was upward. Further, the molten metal inflow rate into the space was 0.95 m / second, and the molten metal was pressurized and injected into the space, and the pressure was maintained until solidification of the entire Al alloy casting was completed.
　上記Ａｌ合金鋳物を石膏型から取り外した後、表５に示す条件で溶体化処理を施し、その後、同じく表５に示す条件で時効処理を施した。以上のようにして、Ａｌ合金鋳物製コンプレッサーインペラー試料を作製した。 After the Al alloy casting was removed from the gypsum mold, it was subjected to a solution treatment under the conditions shown in Table 5, and then an aging treatment was similarly performed under the conditions shown in Table 5. As described above, a compressor impeller sample made of an Al alloy casting was produced.
　上記のようにして作製した各試料について、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度、同端部における６μｍを超える円相当径を有する金属間化合物の面密度、ディスク部の端部における微細化剤（Ｔｉ、Ｂ）の成分量、ディスク部の端部以外の部位における微細化剤（Ｔｉ、Ｂ）の成分量、高温特性（耐久試験評価）、ならびに、生産性（鋳造歩留評価）を、第１の実施例と同じに評価した。結果を表６に示す。 For each sample produced as described above, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion, the surface of the intermetallic compound having an equivalent circle diameter exceeding 6 μm at the end. Density, amount of component of finer (Ti, B) at the end of the disk part, amount of component of finer (Ti, B) at a part other than the end of the disk part, high temperature characteristics (durability test evaluation), and The productivity (casting yield evaluation) was evaluated in the same manner as in the first example. The results are shown in Table 6.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　本発明例１９～２８では、ディスク部の端部における、１～６μｍの円相当径を有する金属間化合物及び６μｍを超える円相当径を有する金属間化合物の面密度、ならびに、ディスク部の端部と当該端部以外の部位における微細化剤の成分量が、規定の範囲内であることから、高温特性及び鋳造歩留が共に良好であった。 In Inventive Examples 19 to 28, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm and the equivalent metal diameter exceeding 6 μm at the end portion of the disc portion, and the end portion of the disc portion Since the component amount of the micronizing agent in the region other than the end portion is within the specified range, both the high temperature characteristics and the casting yield were good.
　これに対して比較例２７では、溶湯温度が高く冷却速度が低下したため、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度が小さく、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、ボス部における引け巣の外観不良が多発して鋳造歩留が大幅に低下し、また、ディスク部で破断して高温特性に劣った。 On the other hand, in Comparative Example 27, the melt temperature was high and the cooling rate was lowered, so that the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion was small, and the equivalent circle diameter exceeding 6 μm. The surface density of the intermetallic compound was large. As a result, the appearance defect of the shrinkage cavity in the boss part frequently occurred, the casting yield was greatly reduced, and the disk part was broken and inferior in high temperature characteristics.
　比較例２８では、溶湯温度が低く、羽根部における湯回り外観不良が多発し鋳造歩留まりが低下し、また、羽根部にて亀裂が発生し高温特性に劣った。 In Comparative Example 28, the molten metal temperature was low, the appearance of hot water around the blade portion was frequent, the casting yield was lowered, and cracks were generated in the blade portion, resulting in poor high temperature characteristics.
　比較例２９では、冷やし金の温度が低く、ディスク部における湯回り不良が多発し鋳造歩留が低下し、また、湯回り不良部を起因とした亀裂がディスクに発生し高温特性に劣った。 In Comparative Example 29, the temperature of the cooling metal was low, hot water failure in the disk portion occurred frequently, the casting yield was lowered, and cracks due to the hot water failure portion were generated in the disk, resulting in poor high temperature characteristics.
　比較例３０では、冷やし金の温度が高く、ディスク部の端部における１～６μｍの円相当径を有する金属間化合物の面密度が小さく、６μｍを超える円相当径を有する金属間化合物の面密度が大きかった。その結果、ディスク部にて破断し高温特性が劣った。 In Comparative Example 30, the surface density of the intermetallic compound having a high temperature of the cooling metal, the surface density of the intermetallic compound having an equivalent circle diameter of 1 to 6 μm at the end of the disk portion is small, and the surface density of the intermetallic compound having an equivalent circle diameter exceeding 6 μm Was big. As a result, the disk portion was broken and the high temperature characteristics were inferior.
　比較例３１では、溶体化処理工程が実施されず、比較例３２では時効処理工程が実施されなかった。その結果、いずれもディスク部で破断し高温特性に劣った。 In Comparative Example 31, the solution treatment process was not performed, and in Comparative Example 32, the aging process was not performed. As a result, all of them were broken at the disk portion and inferior in high temperature characteristics.
　本発明により、回転数の増大に伴う温度の増加に対して長期間にわたって安定して耐え得る、耐熱強度に優れたＡｌ合金製コンプレッサーインペラーを低コストで供給することが可能である。また、本発明は、ターボチャージャーの加給能力を増加して内燃機関の出力向上に寄与することができるという工業上顕著な効果を奏する。 According to the present invention, it is possible to supply at low cost an Al alloy compressor impeller having excellent heat resistance and capable of stably withstanding an increase in temperature accompanying an increase in the rotational speed over a long period of time. In addition, the present invention has an industrially significant effect that it can contribute to improving the output of the internal combustion engine by increasing the charging capability of the turbocharger.
　１・・・コンプレッサーインペラー
　２・・・ボス部
　３・・・ディスク部
　３１・・・ディスク部の端部
　３２・・・端部を除くディスク部
　４・・・羽根部
　５・・・中心軸
　６・・・冷やし金
　７・・・石膏型
　８・・・溶湯流入孔
　９・・・溶湯流入方向
　１０・・・石膏型と冷やし金とで構成される製品形状の空間 DESCRIPTION OF SYMBOLS 1 ... Compressor impeller 2 ... Boss part 3 ... Disc part 31 ... End part of a disk part 32 ... Disc part except an end part 4 ... Blade | wing part 5 ... Center axis 6 ... Cold metal 7 ... Gypsum mold 8 ... Melute inflow hole 9 ... Mix metal inflow direction 10 ... Product shaped space composed of gypsum mold and chill metal

Claims (6)

  1. 　ボス部、複数の羽根部及びディスク部を備えるＡｌ合金鋳物製コンプレッサーインペラーにおいて、前記ボス部、複数の羽根部及び端部を除くディスク部が、Ｃｕ：１．４～３．２ｍａｓｓ％、Ｍｇ：１．０～２．０ｍａｓｓ％、Ｎｉ：０．５～２．０ｍａｓｓ％、Ｆｅ：０．５～２．０ｍａｓｓ％、Ｔｉ：０．０１～０．３５ｍａｓｓ％、Ｂ：０．００２～０．０７０ｍａｓｓ％を含有し、残部Ａｌ及び不可避的不純物からなるＡｌ合金からなり、前記ディスク部の端部が、Ｃｕ：１．４～３．２ｍａｓｓ％、Ｍｇ：１．０～２．０ｍａｓｓ％、Ｎｉ：０．５～２．０ｍａｓｓ％、Ｆｅ：０．５～２．０ｍａｓｓ％、Ｔｉ：０．００５～０．１７５ｍａｓｓ％、Ｂ：０．００１～０．０３５ｍａｓｓ％を含有し、残部Ａｌ及び不可避的不純物からなるＡｌ合金からなり、前記ディスク部の端部において、１～６μｍの円相当径を有する金属間化合物が１００００個／ｍｍ２以上存在し、且つ、６μｍを超える円相当径を有する金属間化合物が５００個／ｍｍ２以下存在することを特徴とするＡｌ合金鋳物製コンプレッサーインペラー。 In the compressor impeller made of an Al alloy casting provided with a boss part, a plurality of blade parts, and a disk part, the disk part excluding the boss part, the plurality of blade parts, and the end part has Cu: 1.4 to 3.2 mass%, Mg: 1.0-2.0 mass%, Ni: 0.5-2.0 mass%, Fe: 0.5-2.0 mass%, Ti: 0.01-0.35 mass%, B: 0.002-0. It is made of an Al alloy containing 070 mass%, the balance being Al and inevitable impurities, and the end of the disk portion is Cu: 1.4 to 3.2 mass%, Mg: 1.0 to 2.0 mass%, Ni : 0.5 to 2.0 mass%, Fe: 0.5 to 2.0 mass%, Ti: 0.005 to 0.175 mass%, B: 0.001 to 0.035 mass%, balance Al and inevitable Impure Made of Al alloy consisting of, at the end of the disk portion, there intermetallic compound having a circle equivalent diameter of 1 ~ 6 [mu] m is 10000 / mm 2 or more, and intermetallic compounds with a circle equivalent diameter of greater than 6 [mu] m Is a compressor impeller made of an Al alloy casting, characterized in that there are 500 pieces / mm 2 or less.
  2. 　船舶用の大型用途に用いられ、前記ボス部の高さ、ディスク部の直径及び羽根部の高さがそれぞれ、２００～８０ｍｍ、３００～１００ｍｍ及び１８０～６０ｍｍであり、羽根先端肉厚が４．０～０．４ｍｍであり、羽根の枚数が３０～１０枚である、請求項１に記載のＡｌ合金鋳物製コンプレッサーインペラー。 Used for large-scale applications for ships, the height of the boss, the diameter of the disk and the height of the blades are 200 to 80 mm, 300 to 100 mm and 180 to 60 mm, respectively, and the blade tip thickness is 4. The compressor impeller made of Al alloy casting according to claim 1, wherein the impeller is 0 to 0.4 mm and the number of blades is 30 to 10.
  3. 　自動車用などの小型用途に用いられ、前記ボス部の高さ、ディスク部の直径及び羽根部の高さがそれぞれ、１００～２０ｍｍ、１２０～２５ｍｍ、９０～５ｍｍであり、羽根先端肉厚が３．０～０．１ｍｍであり、羽根の枚数が２０～４枚である、請求項１に記載のＡｌ合金鋳物製コンプレッサーインペラー。 Used for small applications such as for automobiles, the height of the boss, the diameter of the disk, and the height of the blade are 100 to 20 mm, 120 to 25 mm, and 90 to 5 mm, respectively, and the blade tip thickness is 3 The compressor impeller made of an Al alloy casting according to claim 1, wherein the compressor impeller is 0.0 to 0.1 mm and the number of blades is 20 to 4.
  4. 　Ｃｕ：１．４～３．２ｍａｓｓ％、Ｍｇ：１．０～２．０ｍａｓｓ％、Ｎｉ：０．５～２．０ｍａｓｓ％、Ｆｅ：０．５～２．０ｍａｓｓ％を含有し、残部Ａｌ及び不可避的不純物からなるＡｌ合金からなる７２０～７８０℃のＡｌ合金溶湯を調製し、当該Ａｌ合金溶湯に微細化剤を添加して、前記合金組成に加えてＴｉ：０．０１～０．３５ｍａｓｓ％、Ｂ：０．００２～０．０７０ｍａｓｓ％を更に含有するようにした溶湯調製工程と；石膏型とインペラーディスク面に接する面に配置された１００～２５０℃の冷やし金とで構成される製品形状を有し、溶湯流入孔が下部に設けられた石膏型が下方に、且つ、冷し金が上方に配置されるように構成される空間に、前記調製したＡｌ合金溶湯を前記溶湯流入孔から圧入する圧力鋳造法によりＡｌ合金鋳物を鋳造する鋳造工程であって、前記空間への溶湯流入孔における溶湯の流入速度を０．１２～１．００ｍ／秒とする鋳造工程と；当該Ａｌ合金鋳物を溶体化処理する溶体化処理工程と；溶体化処理したＡｌ合金鋳物を時効処理する時効処理工程と；を備えることを特徴とするＡｌ合金鋳物製コンプレッサーインペラーの製造方法。 Cu: 1.4-3.2 mass%, Mg: 1.0-2.0 mass%, Ni: 0.5-2.0 mass%, Fe: 0.5-2.0 mass%, the balance Al and An Al alloy molten alloy of 720 to 780 ° C. made of an Al alloy consisting of inevitable impurities is prepared, and a finer is added to the Al alloy molten metal. In addition to the alloy composition, Ti: 0.01 to 0.35 mass% B: Product shape comprising a molten metal preparation step further containing 0.002 to 0.070 mass%; and a 100 to 250 ° C. cooling metal disposed on the surface in contact with the gypsum mold and the impeller disk surface In the space where the gypsum mold in which the molten metal inflow hole is provided in the lower part is arranged downward and the cooling metal is arranged in the upper part, the prepared Al alloy molten metal is introduced from the molten metal inflow hole. For pressure casting to press fit A casting process for casting an Al alloy casting, wherein the casting speed of the molten metal inflowing into the space is 0.12 to 1.00 m / sec; and the Al alloy casting is solution-treated. An aluminum alloy casting compressor impeller manufacturing method comprising: a solution treatment step; and an aging treatment step of aging treatment of a solution-treated Al alloy casting.
  5. 　前記鋳造工程において、ディスク部の端部の冷却速度が０．１～２００℃／秒である、請求項４に記載のＡｌ合金鋳物製コンプレッサーインペラーの製造方法。 The method for producing a compressor impeller made of an Al alloy casting according to claim 4, wherein in the casting step, the cooling rate of the end of the disk portion is 0.1 to 200 ° C / second.
  6. 　前記溶体化処理工程において、前記Ａｌ合金鋳物をＡｌ合金の固相線温度から５～２５℃低い温度で２時間以上熱処理し、前記時効処理工程において、前記溶体化処理したＡｌ合金鋳物を１８０～２３０℃で３～３０時間熱処理する、請求項４又は５に記載のＡｌ合金鋳物製コンプレッサーインペラーの製造方法。 In the solution treatment step, the Al alloy casting is heat-treated for 2 hours or more at a temperature 5 to 25 ° C. lower than the solidus temperature of the Al alloy, and in the aging treatment step, the Al alloy casting subjected to the solution treatment is 180 to The method for producing a compressor impeller made of an Al alloy casting according to claim 4 or 5, wherein the heat treatment is performed at 230 ° C for 3 to 30 hours.
PCT/JP2015/001340 2014-03-15 2015-03-11 Compressor impeller cast from al alloy and method for producing same WO2015141191A1 (en)

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