WO2017006838A1 - 鋳造材及び鋳造材の製造方法 - Google Patents
鋳造材及び鋳造材の製造方法 Download PDFInfo
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- WO2017006838A1 WO2017006838A1 PCT/JP2016/069500 JP2016069500W WO2017006838A1 WO 2017006838 A1 WO2017006838 A1 WO 2017006838A1 JP 2016069500 W JP2016069500 W JP 2016069500W WO 2017006838 A1 WO2017006838 A1 WO 2017006838A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/047—Making non-ferrous alloys by powder metallurgy comprising intermetallic compounds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/14—Casting in, on, or around objects which form part of the product the objects being filamentary or particulate in form
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D19/00—Casting in, on, or around objects which form part of the product
- B22D19/02—Casting in, on, or around objects which form part of the product for making reinforced articles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D30/00—Cooling castings, not restricted to casting processes covered by a single main group
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0433—Nickel- or cobalt-based alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
- C22C19/058—Alloys based on nickel or cobalt based on nickel with chromium without Mo and W
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
- C22C29/14—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on borides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
Definitions
- the present invention relates to a cast material and a method for producing the cast material.
- a cermet material which is a composite material of ceramic and metal has been studied conventionally.
- a method for producing such a cermet material for example, a method is known in which powder as a raw material is mixed by powder metallurgy and fired at a temperature equal to or lower than the melting point of the raw material in a state of being molded by stamping.
- the obtained cermet material may have insufficient density because voids remain inside.
- Patent Document 1 discloses a method of obtaining a cast material made of cermet containing Mo (molybdenum), Ni (nickel), B (boron), etc. by a casting method.
- the cermet cast material obtained by the casting method described in Patent Document 1 described above has an increased density, while the dendritic structure tends to grow inside. As a result, the cast material obtained by the casting method described in Patent Document 1 may be easily damaged starting from the grown dendritic structure. For this reason, it is difficult to use the cast material obtained by the casting method described in Patent Document 1 for an application that particularly requires a bending strength.
- An object of the present invention is to provide a casting material that is excellent in corrosion resistance and wear resistance, and that has achieved high hardness and high bending strength.
- the average particle size of the hard phase particles In the casting material comprising hard phase particles mainly composed of boride or carbide, and a binder phase containing an alloy containing Co and / or Ni as a main component, the average particle size of the hard phase particles, It has been found that the above object can be achieved by controlling the average aspect ratio of the hard phase particles, the content of the hard phase particles having a major axis exceeding 5 ⁇ m, and the contact ratio between the hard phase particles within a predetermined range. The invention has been completed.
- a cast material comprising hard phase particles mainly composed of boride and / or carbide and a binder phase containing an alloy containing Co and / or Ni as a main component, the hard material
- the average particle diameter of the phase particles is 3 ⁇ m or less
- the average aspect ratio of the hard phase particles is 2.3 or less
- the content of the hard phase particles whose major axis is more than 5 ⁇ m is 3450 or less per 2450 ⁇ m 2
- the hard phase A casting material having a contact ratio between particles of 40% or less is provided.
- the hard phase particles are borides and / or carbides comprising at least one of Ni, Co, Cr, Mo, Mn, Cu, W, Fe and Si and B and / or C.
- the binder phase is preferably an alloy of at least one metal selected from Cr, Mo, Mn, Cu, W, Fe, and Si and Co and / or Ni.
- the B content in the cast material is preferably 1 to 6% by weight
- the C content in the cast material is preferably 0 to 2.5% by weight.
- the hard phase particles are made of a double boride represented by Mo 2 NiB 2 or Mo 2 (Ni, Cr) B 2
- the binder phase is made of a Ni-based alloy. preferable.
- a method for producing a cast material comprising hard phase particles mainly composed of boride and / or carbide and a binder phase containing an alloy containing Co and / or Ni as a main component.
- a method for producing a cast material including a process of continuously cooling the dissolution mixture at the above cooling rate.
- the dissolution mixture is preferably cooled by pouring the dissolution mixture into a mold at room temperature to 1100 ° C.
- FIG. 1 is a diagram for explaining a method for measuring the microstructure of a cast material according to the present invention.
- FIG. 2 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Example 1.
- FIG. 3 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Example 2.
- FIG. 4 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Example 3.
- FIG. 5 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Example 4.
- FIG. 2 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Example 1.
- SEM scanning electron microscope
- FIG. 6 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Example 5.
- FIG. 7 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Comparative Example 1.
- FIG. 8 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Comparative Example 2.
- FIG. 9 is a photograph showing a reflected electron image taken with a scanning electron microscope (SEM) of the cross section of the cast material of Comparative Example 3.
- the cast material of the present invention comprises hard phase particles mainly composed of boride or carbide and a binder phase containing an alloy containing Co and / or Ni as a main component, and the average particle size of the hard phase particles is 3 ⁇ m or less.
- the average value of the aspect ratio of the hard phase particles is 2.3 or less, the content of the hard phase particles having a major axis exceeding 5 ⁇ m is 3 or less per 2450 ⁇ m 2 , and the contact ratio between the hard phase particles is 40% or less. It is characterized by that.
- the hard phase particles constituting the cast material of the present invention mainly contain borides and / or carbides and contribute to the hardness and wear resistance of the cast material.
- the hard phase particles are present in a dispersed state in a matrix of a binder phase described later.
- the boride or carbide constituting the hard phase particles is not particularly limited, but is a precipitate composed of at least one of Ni, Co, Cr, Mo, Mn, Cu, W, Fe and Si, and B and / or C. Particles.
- the hard phase particles may be a mixture of particles having different compositions.
- the borides are not particularly limited, but borides of MB type, MB 2 type, M 2 B type, M 2 B 5 type, M 2 M′B 2 type (M and M ′ are Ni, Co, Cr, Mo, Mn, Cu, W, Fe and Si represent at least one metal, and M ′ represents a metal atom different from M.), and specific examples thereof include CrB, MoB, Examples thereof include borides of Cr 2 B, Mo 2 B, Mo 2 B 5 , Mo 2 FeB 2 , Mo 2 CrB 2 , and Mo 2 NiB 2 .
- the carbide is not particularly limited.
- the content ratio of the above-mentioned hard phase particles in the cast material of the present invention is preferably 10 to 50 vol%, more preferably 20 to 45 vol%.
- a method of controlling the content ratio of the hard phase particles in the cast material a method of adjusting the content of B contained in the cast material or the content of C contained in the cast material is used. it can.
- the cast material of the present invention can be highly balanced in corrosion resistance, wear resistance, and mechanical strength such as hardness and bending strength.
- the content ratio of the hard phase particles within the above range, the contact rate between the hard phase particles is prevented from becoming too large, and a reduction in the bending strength of the cast material due to the aggregation of the hard phase particles is prevented. it can.
- the content ratio of the hard phase particles in the above range the temperature required for melting the raw material of the hard phase particles can be lowered, the thermal energy required for melting can be suppressed, and the cost becomes advantageous.
- the binder phase constituting the cast material of the present invention is a phase that includes an alloy containing Co and / or Ni as a main component and forms a matrix for binding the above-described hard phase particles.
- Specific examples of the alloy constituting the binder phase include a Co-based alloy and / or a Ni-based alloy including at least one selected from Cr, Mo, Mn, Cu, W, Fe, and Si. Can be mentioned.
- the binder phase includes an alloy containing Co and / or Ni as a main component, for example, when the binder phase contains an alloy containing a Fe-based alloy as a main component. In comparison, the corrosion resistance of the resulting cast material is improved.
- the hard phase particles and the binder phase constituting the cast material of the present invention are made of a double boride represented by Mo 2 NiB 2 , and the binder phase is made of a Ni-based alloy. It is preferable to become.
- the cast material of the present invention has a fine structure, specifically, an average particle size of hard phase particles, an average aspect ratio of hard phase particles, a content of hard phase particles having a major axis of more than 5 ⁇ m, and a hard phase.
- the contact rate between the particles is controlled within a predetermined range described later. According to the present invention, by controlling these within a predetermined range, which will be described later, it is possible to provide excellent corrosion resistance and wear resistance, as well as high hardness and high bending strength.
- the above-mentioned hard phase particles have an average particle size of 3 ⁇ m or less, preferably 2.8 ⁇ m or less, more preferably 2.5 ⁇ m or less.
- the average particle diameter of the hard phase particles By setting the average particle diameter of the hard phase particles in the above range, the hardness and bending strength of the obtained cast material can be made sufficient. If the average particle size of the hard phase particles exceeds 3 ⁇ m, the hard phase particles become a starting point of fracture, which causes a problem that the bending strength of the cast material is significantly reduced.
- the lower limit of the average particle size of the hard phase particles is not particularly limited, but is preferably 0.5 ⁇ m. In order to make the average particle size of the hard phase particles less than 0.5 ⁇ m, it is necessary to make the cooling rate very large, which is difficult to realize by ordinary water cooling or the like.
- the average particle diameter of the hard phase particles can be measured, for example, by calculating the equivalent circle diameter of the hard phase particles and calculating the average value of the calculated equivalent circle diameters. Specifically, first, a backscattered electron image is taken of a cross-section of a cast material using a scanning electron microscope (SEM), and a fullman's formula (the following formula (1) is used using the obtained backscattered electron image. )), The average particle size of the hard phase particles can be calculated.
- d m (4 / ⁇ ) ⁇ (N L / N S ) (1) In the above formula (1), d m is the mean particle diameter of the hard phase particles. ⁇ is the circumference ratio.
- N L is hit by an arbitrary straight line on the cross-sectional texture (when an arbitrary straight line is drawn, it touches or intersects the arbitrary straight line), and the number of hard phase particles per unit length of the arbitrary straight line Specifically, it is a value calculated by dividing the number of particles hit by an arbitrary straight line having a length L on the cross-sectional structure by the length L of the arbitrary straight line.
- N S in this section of the specification indicates the number of the hard phase particles contained in arbitrary units in the area, the number of particles contained in any of the measurement area of the measurement region range S, the arbitrary measurement region The value divided by the range S is represented.
- the length of the straight line L may be a length at which a sufficient number of hard phase particles intersect to measure the average particle diameter, and is preferably 20 ⁇ m or more. In the example described later, the length of the straight line L is 42 ⁇ m.
- the measurement region range S may be a range in which a sufficient number of hard phase particles are included for the measurement of the average particle diameter, and is preferably a range having a length of 20 ⁇ m or more and a width of 20 ⁇ m or more. In the example described later, the length of the measurement region range S is 57 ⁇ m and the width is 43 ⁇ m (that is, 2450 ⁇ m 2 ).
- the cast material of the present invention preferably has an average value of the aspect ratio of the hard phase particles, that is, an average value of the ratio of the major axis to the minor axis of the hard phase particles (major axis / minor axis) is 2.3 or less, preferably Is 2.2 or less, more preferably 2.1 or less.
- the average value of the aspect ratio of the hard phase particles within the above range, the bending strength of the cast material can be remarkably improved.
- the average value of the aspect ratio of the hard phase particles becomes too large due to the growth of the dendritic structure (columnar crystals) of the hard phase particles, the bending strength of the cast material decreases in the dendritic structure portion. The cast material is easily damaged.
- the average aspect ratio of the hard phase particles can be determined, for example, in accordance with JIS R1670 as follows. First, the cast material is cut, and the cut surface is photographed with a scanning electron microscope (SEM) to obtain a reflected electron image. Next, a predetermined number of hard phase particles are arbitrarily selected from the measurement region range S (length range of 20 ⁇ m or more and width of 20 ⁇ m or more) in the same manner as the measurement of the average particle diameter described above for the obtained reflected electron image. The length (major axis) of the longest part of each hard phase particle and the length (minor axis) of the longest part in the direction orthogonal to the major axis are measured.
- S scanning electron microscope
- the ratio of the major axis to the minor axis can be determined as the aspect ratio of the hard phase particles.
- an average value of the aspect ratios of the hard phase particles can be obtained by obtaining such an aspect ratio for a predetermined number (for example, 10 or more) of hard phase particles and calculating the average value thereof. it can.
- the content of hard phase particles having a major axis exceeding 5 ⁇ m is 3 or less per 2450 ⁇ m 2 , preferably 2 or less, more preferably 1 or less.
- the bending strength of the cast material is controlled in the same manner as controlling the average value of the aspect ratio of the hard phase particles described above. It can be significantly improved.
- the number of hard phase particles having a major axis exceeding 5 ⁇ m is the same as the measurement of the aspect ratio of the hard phase particles described above, and the measurement region range S (length of 20 ⁇ m or more in the SEM reflected electron image) in an arbitrary cross section.
- the range of 20 ⁇ m or more in width it can be obtained by calculating hard phase particles having a major axis exceeding 5 ⁇ m.
- the content of hard phase particles having a major axis of more than 5 ⁇ m is defined by the number per 2450 ⁇ m 2 which is the measurement region range S actually measured in the examples described later.
- actual measurement is not particularly limited to such an area range, and when measurement is performed using a reflected electron image in a different area range, it may be obtained by proportional calculation.
- the content of the hard phase particles having a major axis of more than 5 ⁇ m per area area of 5000 ⁇ m 2 may be controlled, and in this case, the major axis per 5000 ⁇ m 2 is more than 5 ⁇ m.
- the content of the hard phase particles is 6 or less, preferably 4 or less, more preferably 2 or less.
- the cast material of the present invention has a contact ratio between hard phase particles of 40% or less, preferably 39% or less, more preferably 38% or less.
- the contact rate between the hard phase particles is an index representing the dispersibility of the hard phase particles, and the lower the contact rate, the better the dispersibility, and thereby the strength can be improved. If the contact ratio between the hard phase particles is too high, coarse aggregates may be generated due to the contact between the hard phase particles, or particle growth may occur due to the bonding between the hard phase particles.
- the developed part becomes a starting point of breakage and causes a problem that the bending strength of the cast material is reduced.
- the contact rate between the hard phase particles can be measured, for example, as follows. That is, first, using a scanning electron microscope (SEM), a backscattered electron image was taken on the surface of the cast material, and as shown in FIG. A line L for measurement having a predetermined length is arbitrarily drawn on the image, and the hard phase interface existing on the line L is observed.
- FIG. 1 is a figure for demonstrating the measuring method of the microstructure of the cast material of this invention. Specifically, the hard phase particle interface is observed, and the interface where the hard phase particles are in contact with each other is defined as the hard phase-hard phase interface I HH , and the hard phase particles and the binder phase are in contact with each other.
- the interface is the hard phase-bonded phase interface I HB, and these numbers are counted.
- the number N per unit length of L1 of the hard phase-hard phase interface I HH (I HH ) and the number N per unit length of L1 of the hard phase-bond phase interface I HB ( I HB ), the contact ratio Cont (unit:%) between the hard phase particles can be calculated according to the following formula (2).
- Cont 2N (I HH ) / ⁇ 2N (I HH ) + N (I HB ) ⁇ ⁇ 100
- a measurement line L different from the above is drawn on the SEM photograph so as to pass through a place different from the above, and similarly.
- the operation of counting the number of the hard phase-hard phase interface I HH and the number of the hard phase-bond phase interface I HB was performed a total of 6 times, and the measurement results of the 6 times in total were averaged to obtain It is preferable to calculate the contact rate.
- the average particle diameter of the hard phase particles, the average value of the aspect ratio of the hard phase particles, the content of the hard phase particles having a major axis exceeding 5 ⁇ m, and the contact ratio between the hard phase particles are within the above ranges.
- the following method is mentioned. That is, when producing a cast material, first, a raw material for forming hard phase particles and a binder phase is melted to obtain a dissolved mixture, and then, when the obtained dissolved mixture is cooled, a cooling start temperature To 400 ° C., 100 ° C./min. The method of including the process of cooling continuously with the above cooling rate is mentioned.
- the contact ratio between the hard phase particles can be controlled, for example, by adjusting the composition of the cast material to be within a specific range.
- the composition of the cast material of the present invention is not particularly limited, but when the binder phase is a Ni-based alloy containing Ni as a main component, B: 1 to 6% by weight, C: 0 to 2.5% by weight, Preferably, Co is 0 to 30% by weight, Si is 0 to 5% by weight, Cr is 0 to 20% by weight, Mo is 5 to 40% by weight, Fe is 0 to 25% by weight, and Ni is the balance.
- the binder phase is a Co-based alloy containing Co as a main component
- B 1 to 6 wt%
- C 0 to 2.5 wt%
- Ni 0 to 5 wt%
- Si 0 to 5 wt%
- Cr 0 to 25 wt%
- Mo 5 to 40 wt%
- Fe 0 to 25 wt%
- Co balance
- B (boron) is an element for forming a boride that becomes hard phase particles.
- the content ratio of the hard phase particles in the cast material can be made moderate, and thereby the wear resistance of the cast material is improved.
- grains can be made into the range mentioned above, and the hardness and bending strength of a cast material can be improved.
- the content of B in the cast material is preferably 1 to 6% by weight, more preferably 2 to 5% by weight, regardless of whether the binder phase is mainly composed of Ni or Co. It is.
- the content of C in the cast material is preferably 0.15% by weight to 2.5% by weight, more preferably the binder phase in which the main component is Ni or the main component is Co. Is 0.2 to 1% by weight. In the case where it is contained as an inevitable impurity without forming a carbide, for example, 0.06% or less is preferable.
- Ni nickel is an element that can form hard phase particles and an element that can form a binder phase when a Ni-based alloy is used as the binder phase of the cast material. It has the effect
- Co is an element that can form hard phase particles and an element that can form a binder phase when a Ni-based alloy is used as the binder phase of the cast material. It has the effect
- Si is an element that can constitute the binder phase of the cast material, and has the effect of lowering the melting temperature of the raw material for forming the cast material. In addition to being able to lower the melting temperature by making the Si content ratio appropriate, it suppresses the decrease in the bending strength of the cast material due to an increase in the content of silicide in the cast material. be able to.
- Cr is an element that can form hard phase particles and an element that can form a binder phase, and improves the corrosion resistance, wear resistance, high temperature characteristics, hardness and bending strength of the cast material.
- the content ratio of the hard phase particles in the cast material is in the above-described range, and the bending strength of the cast material can be improved.
- Mo mobdenum
- Mo is an element that can form hard phase particles and an element that can form a binder phase, and has the effect of improving the corrosion resistance of the cast material.
- a part of Mo is dissolved in the binder phase, thereby improving the corrosion resistance of the cast material.
- the wear resistance and corrosion resistance of the cast material can be improved.
- raw material powder for forming the cast material of the present invention is prepared. What is necessary is just to prepare as raw material powder so that the content rate of each element which forms a cast material may become a desired composition ratio.
- the raw material powder may contain hard phase particles mainly composed of boride and / or carbide in advance, or the raw material powder may not contain hard phase particles.
- hard phase particles mainly composed of boride and / or carbide are formed in the cast material due to boron or carbon contained in the raw material powder. May be.
- a binder and an organic solvent are added to the raw material powder, if necessary, and then mixed and pulverized using a pulverizer such as a ball mill. I do.
- Binder is added for the purpose of improving moldability during molding and preventing powder oxidation.
- the binder is not particularly limited, and known ones can be used, and examples thereof include paraffin.
- the amount of the binder added is not particularly limited, but is preferably 3 to 6 parts by weight with respect to 100 parts by weight of the raw material powder.
- the organic solvent is not particularly limited, but a low boiling point solvent such as acetone can be used.
- the pulverization and mixing time is not particularly limited, and may be selected such that the average particle size of the hard phase particles formed in the obtained cast material falls within the above range, but is usually 15 to 30 hours. .
- the melting temperature at this time may be determined according to the raw material to be used, but is preferably 1100 to 1300 ° C., more preferably 1200 to 1250 ° C.
- the melted mixture thus obtained is poured into a mold such as a mold corresponding to a desired shape, cooled, and cast, whereby a cast material can be obtained.
- a mold such as a mold corresponding to a desired shape
- a cast material can be obtained.
- the dissolved mixture when the dissolved mixture is cooled, in the temperature range from the cooling start temperature to 400 ° C., 100 ° C./min.
- a process of continuously cooling the dissolved mixture at the above cooling rate is included.
- 100 ° C./min. In order to include the process of continuously cooling the dissolved mixture at the above cooling rate, it is continued for a certain amount of time at 100 ° C./min. This means that the cooling rate may be set to the above-mentioned cooling rate, and preferably 100 minutes / min.
- the process of cooling at the above cooling rate is included, for example, instantaneously 100 ° C./min.
- a mode in which the above cooling rate is obtained (for example, a mode in which the cooling rate is 100 ° C./min. Or more for only 1 second or less) is not included.
- the cooling rate at this time is preferably 200 ° C./min. Or more, more preferably 400 ° C./min. That's it.
- the obtained cast material has an average particle size of the hard phase particles, an average value of the aspect ratio of the hard phase particles, an average value of the long diameter of the hard phase particles, and the hard phase particles
- the contact ratio can be controlled within the above-described range.
- the method for cooling the dissolution mixture under the above conditions is not particularly limited, but the dissolution mixture is preferably poured into a mold at room temperature to 1100 ° C., more preferably 300 to 1100 ° C.
- the method of cooling is mentioned. Examples of room temperature include 1 to 30 ° C.
- the casting method is not particularly limited, but from the viewpoint that a cast material having a complicated shape can be formed, and from the viewpoint that a thick-walled material can be formed, a die casting method, a lost wax, a continuous casting method, It is preferable to use a centrifugal casting method.
- the casting material of the present invention is manufactured.
- the cast material of the present invention comprises hard phase particles mainly composed of boride and / or carbide and a binder phase containing an alloy containing Co and / or Ni as a main component, and the average particle size of the hard phase particles is 3 ⁇ m or less, the average aspect ratio of the hard phase particles is 2.3 or less, the content of the hard phase particles whose major axis is more than 5 ⁇ m is 3 or less per 2450 ⁇ m 2 , and the contact ratio between the hard phase particles is 40% or less. Each of them is controlled. Therefore, the cast material of the present invention is excellent in corrosion resistance and wear resistance, and realizes high hardness and high bending resistance.
- the cast material of the present invention is excellent in corrosion resistance and wear resistance and realizes high hardness and high bending resistance, for example, high loads such as rolls, cylinders, bearings, industrial pump parts, etc. It can be suitably used as a wear-resistant material capable of realizing excellent durability even under an applied environment.
- the length of the straight line L when performing each measurement was 42 ⁇ m, and the measurement region range S was 2450 ⁇ m 2 .
- ⁇ Drag strength> By cutting the cast material so as to have a size of 4 mm ⁇ 7 mm ⁇ 24 mm, a test piece is obtained, and the obtained test piece has a bending strength (three-point bending test) in accordance with CIS 026. Was measured.
- Example 1 20% by weight of Mo 2 NiB 2 type double boride and a Ni-based self-fluxing alloy (composition: Cr: 10% by weight, B: 2% by weight, Si: 2.7% by weight, C: 0.4% by weight) Fe: 2% by weight, Ni: the balance.) 80% by weight was dry-mixed to obtain a mixed powder. Next, the obtained mixed powder is put in a crucible and melted by raising the temperature to 1200 ° C. in a high-frequency melting furnace using a vacuum casting machine (TCP-5250 manufactured by Tanabe Kenden Co., Ltd.). The resulting molten mixture at 1200 ° C.
- a vacuum casting machine TCP-5250 manufactured by Tanabe Kenden Co., Ltd.
- the dissolution mixture was in the range from 1200 ° C. to 400 ° C. at 400 ° C./min. It can be said that it was continuously cooled at a cooling rate of about.
- the average particle size of the hard phase particles, the average value of the aspect ratio of the hard phase particles, the number of hard phase particles having a major axis of more than 5 ⁇ m, between the hard phase particles Each measurement of a contact rate, hardness, and bending strength was performed.
- 2A and 2B show reflected electron images taken by a scanning electron microscope (SEM) taken for each measurement.
- SEM scanning electron microscope
- FIG. 2B is an enlarged view of a part of FIG.
- the white area is boride (hard phase particles)
- the black area is carbide
- the remaining gray area is Ni-based alloy.
- the average particle size of the hard phase particles is 2.2 ⁇ m
- the average value of the aspect ratio of the hard phase particles is 2.0
- the contact ratio of the hard phase particles is 37%
- the hardness (HRC) was 54.8
- the bending strength was 1143 MPa.
- the measured value of the long diameter of any 10 particles extracted from the hard phase particles used for calculating the aspect ratio is 2.4 ⁇ m, 3.0 ⁇ m, 3.5 ⁇ m, 3.8 ⁇ m, 3
- the average diameter of the major axis was 3.89 ⁇ m
- the average value of the major axis was 0.99 ⁇ m, 3.9 ⁇ m, 4.0 ⁇ m, 4.4 ⁇ m, 4.9 ⁇ m, and 5.1 ⁇ m.
- the major axis of all the hard phase particles existing in the measurement region range S (that is, the range of 2450 ⁇ m 2 ) was measured.
- the number of particles having a major axis exceeding 5 ⁇ m was one.
- the number of particles having a major axis exceeding 5 ⁇ m was measured in five measuring ranges while changing the measuring range. In all cases, the number of particles having a major axis exceeding 5 ⁇ m was 0 to 1. It was.
- the number of particles diameter exceeds 5 ⁇ m was two.
- Example 2 10% by weight of Mo 2 NiB 2 type double boride and a Ni-based self-fluxing alloy (composition: B: 2.3% by weight, Si: 7.1% by weight, C: 0.06% by weight or less, Fe: 1.5 wt%, Ni: the balance.) 90 wt% was dry-mixed to obtain a mixed powder. Next, the obtained mixed powder was baked and hardened in a vacuum at 1160 ° C. for 30 minutes using a vacuum furnace to obtain an ingot. Thereafter, the ingot is heated up to 1200 ° C. in the atmosphere using an atmospheric furnace and dissolved to obtain a dissolved mixture, and the obtained 1200 ° C. molten mixture is poured into a mold at room temperature of 20 ° C.
- a Ni-based self-fluxing alloy composition: B: 2.3% by weight, Si: 7.1% by weight, C: 0.06% by weight or less, Fe: 1.5 wt%, Ni: the balance.
- the cast material was obtained by air cooling.
- the temperature of the dissolved mixture was measured about 1 minute after removal from the atmospheric furnace, the temperature was 400 to 500 ° C. That is, the dissolved mixture was cooled from 1200 ° C. to 400 to 500 ° C. in one minute after being taken out from the atmospheric furnace, and the cooling rate of the dissolved mixture at this time was 700 to 800 ° C./min. From this result, it can be seen that the dissolved mixture is 700 to 800 ° C./min. It can be said that a process of continuous cooling at a cooling rate of about a degree was passed.
- the average particle size of the hard phase particles, the average value of the aspect ratio of the hard phase particles, the number of hard phase particles having a major axis of more than 5 ⁇ m, between the hard phase particles Each measurement of a contact rate, hardness, and bending strength was performed. Reflected electron images taken by a scanning electron microscope (SEM) taken for each measurement are shown in FIGS. 3 (A) and 3 (B). Here, FIG. 3B is an enlarged view of a part of FIG. In the reflected electron images of FIGS. 3A and 3B, the white region is a boride (hard phase particle), the black region is an impurity, and the remaining gray region is a Ni-based alloy.
- the average particle diameter of the hard phase particles is 2.8 ⁇ m
- the average value of the aspect ratio of the hard phase particles is 1.5
- the contact ratio of the hard phase particles is 14%
- the hardness (HRC) was 64 and the bending strength was 1101 MPa.
- the measured value of a long diameter is illustrated about arbitrary 10 particle
- the measurement region ranges S i.e., 2450Myuemu range of 2 for all the hard phase particles present in, the measured major axis, the number of particles diameter exceeds 5 ⁇ m was two.
- the number of particles having a major axis exceeding 5 ⁇ m was measured in five measuring ranges while changing the measuring range. In all cases, the number of particles having a major axis exceeding 5 ⁇ m was 0-2. It was. Also, for all the hard phase particles present in the range of 5000 .mu.m 2, was measured major axis, the number of particles diameter exceeds 5 ⁇ m was four.
- Example 3 As a mixed powder, 15% by weight of Mo 2 NiB 2 type double boride and a Ni-based self-fluxing alloy (composition: B: 2.3% by weight, Si: 7.1% by weight, C: 0.06% by weight) (Fe: 1.5% by weight, Ni: balance)) A cast material was obtained in the same manner as in Example 2 except that 85% by weight was dry-mixed. It was. 4A and 4B show reflected electron images taken by a scanning electron microscope (SEM) taken for each measurement. Here, FIG. 4B is an enlarged view of a part of FIG. In the reflected electron images of FIGS.
- SEM scanning electron microscope
- the white region is boride (hard phase particles)
- the black region is an impurity
- the remaining gray region is a Ni-based alloy.
- the elongated part (the part indicated by the arrow in FIG. 4B) is colored more than the other part of the Ni-based alloy due to the difference in crystallinity in the Ni-based alloy. It is considered to be dark and is a Ni-based alloy to the last, and is not considered to constitute hard phase particles.
- the average particle diameter of the hard phase particles is 2.1 ⁇ m
- the average value of the aspect ratio of the hard phase particles is 1.8
- the contact ratio of the hard phase particles is 13%
- the hardness (HRC) was 65
- the bending strength was 993 MPa.
- the measured value of the long diameter of any 10 particles extracted from the hard phase particles used for calculating the aspect ratio is 2.2 ⁇ m, 3.1 ⁇ m, 3.2 ⁇ m, 3.2 ⁇ m, 2
- the average diameter of the major axis was 3.20 ⁇ m, which was an average value of these, and was 0.6 ⁇ m, 4.3 ⁇ m, 3.7 ⁇ m, 3.7 ⁇ m, 2.8 ⁇ m, and 3.2 ⁇ m.
- the major axis was measured for all of the hard phase particles existing in the measurement region range S (that is, the range of 2450 ⁇ m 2 ).
- the number of particles having a major axis exceeding 5 ⁇ m was zero.
- the number of particles having a major axis exceeding 5 ⁇ m was measured in five measuring ranges while changing the measuring range. In all cases, the number of particles having a major axis exceeding 5 ⁇ m was 0 to 1. It was.
- the number of particles diameter exceeds 5 ⁇ m was two.
- Example 4 As mixed powder, 20% by weight of Mo 2 NiB 2 type double boride and a Ni-based self-fluxing alloy (compositions were B: 2.3% by weight, Si: 7.1% by weight, C: 0.06% by weight) (Fe: 1.5 wt%, Ni: balance)) A cast material was obtained in the same manner as in Example 2 except that 80 wt% was dry-mixed. It was. Reflected electron images taken by a scanning electron microscope (SEM) taken for each measurement are shown in FIGS. 5 (A) and 5 (B). Here, FIG. 5B is an enlarged view of a part of FIG. In the reflected electron images of FIGS.
- SEM scanning electron microscope
- the white region is boride (hard phase particles)
- the black region is an impurity
- the remaining gray region is a Ni-based alloy.
- the elongated part (the part indicated by the arrow in FIG. 5B) has a color different from that of the other part of the Ni-based alloy due to the difference in crystallinity in the Ni-based alloy. It is considered to be dark and is a Ni-based alloy to the last, and is not considered to constitute hard phase particles.
- the average particle diameter of the hard phase particles is 2.1 ⁇ m
- the average value of the aspect ratio of the hard phase particles is 1.8
- the contact ratio of the hard phase particles is 13%
- the hardness (HRC) was 65
- the bending strength was 1198 MPa.
- the measured value of the long diameter of any 10 particles extracted from the hard phase particles used for calculating the aspect ratio 3.2 ⁇ m, 4.0 ⁇ m, 3.4 ⁇ m, 3.2 ⁇ m, 3
- the average value of the major axis which is the average value of these, was 3.31 ⁇ m. 0.2 ⁇ m, 3.7 ⁇ m, 3.2 ⁇ m, 3.0 ⁇ m, 3.2 ⁇ m, and 3.2 ⁇ m.
- the measurement region ranges S (i.e., 2450Myuemu range of 2) for all the hard phase particles present in, the measured major axis, the number of particles diameter exceeds 5 ⁇ m was two.
- the number of particles having a major axis exceeding 5 ⁇ m was measured in five measuring ranges while changing the measuring range. In all cases, the number of particles having a major axis exceeding 5 ⁇ m was 0-2. It was. Also, for all the hard phase particles present in the range of 5000 .mu.m 2, was measured major axis, the number of particles diameter exceeds 5 ⁇ m was four.
- Example 5 Instead of the mixed powder, a Ni-based self-fluxing alloy (composition is Cr: 10 wt%, B: 2 wt%, Si: 2.7 wt%, C: 0.4 wt%, Fe: 2 wt%, Ni : Remaining part.) Except for using only the same, a cast material was obtained in the same manner as in Example 2, and each measurement was performed in the same manner. Reflected electron images taken by a scanning electron microscope (SEM) taken for each measurement are shown in FIGS. 6 (A) and 6 (B). Here, FIG. 6B is an enlarged view of a part of FIG. In the reflected electron images of FIGS.
- SEM scanning electron microscope
- the black region is carbide (hard phase particles), and the remaining gray region is a Ni-based alloy.
- the carbide is considered to be formed by reacting carbon in the Ni-based self-fluxing alloy with a metal element (Ni, Cr or Fe).
- the average particle diameter of the hard phase particles is 1.1 ⁇ m
- the average value of the aspect ratio of the hard phase particles is 2.4
- the contact ratio of the hard phase particles is 18.7%
- the hardness (HRC) was 44.7
- the bending strength was 1118 MPa.
- the measured value of the long diameter of any 10 particles extracted from the hard phase particles used for calculating the aspect ratio is 1.5 ⁇ m, 2 ⁇ m, 1.5 ⁇ m, 4.5 ⁇ m, 4 ⁇ m, 2 ⁇ m. They were 2 ⁇ m, 1.75 ⁇ m, 2 ⁇ m, and 2 ⁇ m, and the average value of the major axis, which is the average value of these, was 2.4 ⁇ m.
- the major axis was measured for all of the hard phase particles existing in the measurement region range S (that is, the range of 2450 ⁇ m 2 ), the number of particles having a major axis exceeding 5 ⁇ m was zero. The number of particles having a major axis exceeding 5 ⁇ m was measured in five measuring ranges while changing the measuring range. In all cases, the number of particles having a major axis exceeding 5 ⁇ m was 0 to 1. It was. Also, for all the hard phase particles present in the range of 5000 .mu.m 2, was measured major axis, the number of particles diameter exceeds 5 ⁇ m was one.
- Example 1 The mixed powder obtained in the same manner as in Example 1 was placed in a crucible, and the melted mixture heated to 1200 ° C. using a vacuum heat treatment furnace (PVSGgr 20/20 manufactured by Shimadzu Corporation) was melted at high frequency. In the furnace, it was gradually cooled to 400 ° C. over about 1 hour to obtain a cast material. Next, each measurement was performed on the obtained cast material in the same manner as in Example 1. Reflected electron images taken by a scanning electron microscope (SEM) taken for each measurement are shown in FIGS. Here, FIG. 7B is an enlarged view of a part of FIG. In the reflected electron images of FIGS. 7A and 7B, the white region is boride (hard phase particles), the black region is carbide, and the remaining gray region is Ni-based alloy.
- SEM scanning electron microscope
- the average particle diameter of the hard phase particles is 3.5 ⁇ m
- the average value of the aspect ratio of the hard phase particles is 2.4
- the contact ratio of the hard phase particles is 43%
- the hardness (HRC) was 49.4
- the bending strength was 664 MPa.
- the measured value of the long diameter of any 10 particles extracted from the hard phase particles used for calculating the aspect ratio is 3.4 ⁇ m, 3.6 ⁇ m, 4.1 ⁇ m, 4.2 ⁇ m, 4 0.7 ⁇ m, 5.1 ⁇ m, 5.1 ⁇ m, 5.1 ⁇ m, 5.6 ⁇ m, and 6.4 ⁇ m, and the average value of the major axis, which is the average value of these, was 4.73 ⁇ m.
- the major axis was measured for all the hard phase particles existing in the measurement region range S (that is, a range of 2450 ⁇ m 2 ), the number of particles having a major axis exceeding 5 ⁇ m was five. Also, for all the hard phase particles present in the range of 5000 .mu.m 2, was measured major axis, the number of particles diameter exceeds 5 ⁇ m was 10.
- Example 2 The mixed powder obtained in the same manner as in Example 1 was placed in a crucible, and the melted mixture heated to 1200 ° C. using a vacuum heat treatment furnace (PVSGgr 20/20 manufactured by Shimadzu Corporation) was melted at high frequency. In a furnace, it was gradually cooled to 800 ° C. over about 5 hours to obtain a cast material. Next, each measurement was performed on the obtained cast material in the same manner as in Example 1. Reflected electron images taken by a scanning electron microscope (SEM) taken for each measurement are shown in FIGS.
- FIG. 8B is a high-magnification electronic image of the same test piece as FIG.
- the white region is boride (hard phase particles)
- the black region is carbide
- the remaining gray region is Ni-based alloy.
- the average particle size of the hard phase particles is 3.68 ⁇ m
- the average value of the aspect ratio of the hard phase particles is 1.7
- the contact ratio of the hard phase particles is 21%
- the hardness (HRC) was 47.0
- the bending strength was 522 MPa.
- the measured value of the long diameter of any 10 particles extracted from the hard phase particles used for calculating the aspect ratio is 3.5 ⁇ m, 6 ⁇ m, 4 ⁇ m, 6 ⁇ m, 7.5 ⁇ m, 8.5 ⁇ m. 9.5 ⁇ m, 8.5 ⁇ m, 6.5 ⁇ m, 5.5 ⁇ m, and the average value of the major axis, which is the average value of these, was 6.6 ⁇ m.
- the major axis was measured for all of the hard phase particles existing in the measurement region range S (that is, the range of 2450 ⁇ m 2 ), the number of particles having a major axis exceeding 5 ⁇ m was 10. Also, for all the hard phase particles present in the range of 5000 .mu.m 2, was measured major axis, the number of particles diameter exceeds 5 ⁇ m was 20.
- a Ni-based self-fluxing alloy (composition is Cr: 10 wt%, B: 2 wt%, Si: 2.7 wt%, C: 0.4 wt%, Fe: 2 wt%, Ni : Remainder) Except for using only the same, a cast material was obtained in the same manner as in Comparative Example 2, and each measurement was performed in the same manner. Reflected electron images taken by a scanning electron microscope (SEM) photographed for each measurement are shown in FIGS. 9A and 9B. Here, FIG. 9B is an enlarged view of a part of FIG. 9A. In the reflected electron images of FIGS. 9A and 9B, the black region is carbide (hard phase particles), and the remaining gray region is a Ni-based alloy.
- Comparative Example 3 since the hard phase particles were combined to form a large lump, the average particle size, average aspect ratio, and contact rate of the hard phase particles could not be measured.
- the cast material of Comparative Example 3 had a hardness (HRC) of 38.0 and a bending strength of 519 MPa.
- the average particle size of the hard phase particles is 3 ⁇ m or less, the average aspect ratio of the hard phase particles is 2.3 or less, and the content of the hard phase particles having a major axis of more than 5 ⁇ m is 2450 ⁇ m.
- a cast material having 3 or less per 2 and a contact ratio between hard phase particles of 40% or less was a result of high bending strength and hardness. That is, from the results of Examples 1 to 5, the cast material having such a microstructure includes hard phase particles mainly composed of boride and / or carbide and an alloy mainly containing Co and / or Ni.
- the molten mixture was poured into a mold at room temperature, and then air-cooled to obtain a cast material.
- the mold was heated to 400 ° C. as in Example 1. Even when a mold is used, in the temperature range from the cooling start temperature to 400 ° C., 100 ° C./min. Since it is considered that the process of continuously cooling the dissolved mixture at the above cooling rate, the obtained cast material has high bending strength and hardness in addition to excellent corrosion resistance and wear resistance. It is considered to have characteristics.
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Abstract
Description
本発明の鋳造材において、前記結合相が、Cr,Mo,Mn,Cu,W,Fe及びSiのうち少なくとも1種の金属と、Co及び/又はNiとの合金であることが好ましい。
本発明の鋳造材において、鋳造材中におけるBの含有量が1~6重量%であり、前記鋳造材中におけるCの含有量が0~2.5重量%であることが好ましい。
本発明の鋳造材において、前記硬質相粒子がMo2NiB2またはMo2(Ni,Cr)B2で表される複硼化物からなり、前記結合相がNi基合金からなるものであることが好ましい。
本発明の鋳造材は、硼化物又は炭化物を主体とする硬質相粒子と、Co及び/又はNiを主成分として含有する合金を含む結合相とからなり、硬質相粒子の平均粒径が3μm以下、硬質相粒子のアスペクト比の平均値が2.3以下、長径が5μm超である前記硬質相粒子の含有量が2450μm2あたり3個以下、硬質相粒子同士の接触率が40%以下であることを特徴とする。
本発明の鋳造材を構成する硬質相粒子は、硼化物および/または炭化物を主として含み、鋳造材の硬度及び耐摩耗性に寄与する。本発明の鋳造材において、硬質相粒子は、後述する結合相のマトリックス中に分散された状態で存在している。
本発明の鋳造材を構成する結合相は、Co及び/又はNiを主成分として含有する合金を含み、上述した硬質相粒子を結合するためのマトリックスを形成する相である。結合相を構成する合金の具体例としては、Co基合金及び/又はNi基合金であって、Cr,Mo,Mn,Cu,W,Fe及びSiから選択される少なくとも1種を含む合金などが挙げられる。本発明の鋳造材では、結合相を、Co及び/又はNiを主成分として含有する合金を含むものとすることにより、例えば、結合相に、Fe基合金を主成分とする合金を含有させた場合と比較して、得られる鋳造材の耐食性が向上する。
本発明の鋳造材は、その微細構造、具体的には、硬質相粒子の平均粒径、硬質相粒子のアスペクト比の平均値、長径が5μm超である硬質相粒子の含有量、及び硬質相粒子同士の接触率が、後述する所定の範囲に制御されたものである。本発明によれば、これらを後述する所定の範囲に制御することにより、耐食性及び耐摩耗性に優れ、かつ、高硬度及び高抗折力を備えるものとすることができる。
dm=(4/π)×(NL/NS) …(1)
上記式(1)中、dmは、硬質相粒子の平均粒径である。πは、円周率である。NLは、断面組織上の任意の直線によってヒットされる(任意の直線を引いた場合に、該任意の直線と接触あるいは交差する)、該任意の直線の単位長さあたりの硬質相粒子の数であり、具体的には、断面組織上の長さLの任意の直線によってヒットされる粒子の数を、該任意の直線の長さLで除したものにより算出される値である。また、NSは、任意の単位面積内に含まれる硬質相粒子の数を表したものであって、測定領域範囲Sの任意の測定面積内に含まれる粒子の数を、該任意の測定領域範囲Sで除したものを表す。なお、この際においては、直線Lの長さは、平均粒径の測定に十分な数の硬質相粒子が交わる長さとすればよく、20μm以上とすることが好ましい。なお、後述する実施例では、直線Lの長さは42μmとしている。また、測定領域範囲Sは、平均粒径の測定に十分な数の硬質相粒子が含まれる範囲とすればよく、長さ20μm以上、幅20μm以上の範囲とすることが好ましい。なお、後述する実施例では、測定領域範囲Sの長さは57μm、幅は43μm(すなわち、2450μm2)としている。
Cont=2N(IHH)/{2N(IHH)+N(IHB)}×100 …(2)
なお、上記方法にしたがって、硬質相粒子同士の接触率を算出する際には、上記とは別の測定用のラインLを、上記とは異なる場所を通るようにSEM写真上に引き、同様にして、硬質相-硬質相界面IHH、および硬質相-結合相界面IHBの数をカウントする操作を、合計6回行い、合計6回の測定結果を平均することにより、硬質相粒子同士の接触率を算出することが好ましい。
本発明の鋳造材の組成は、特に限定されないが、結合相をNiを主成分とするNi基合金とする場合には、B:1~6重量%、C:0~2.5重量%、Co:0~30重量%、Si:0~5重量%、Cr:0~20重量%、Mo:5~40重量%、Fe:0~25重量%、Ni:残部であることが好ましい。あるいは、結合相をCoを主成分とするCo基合金とする場合には、B:1~6重量%、C:0~2.5重量%、Ni:0~5重量%、Si:0~5重量%、Cr:0~25重量%、Mo:5~40重量%、Fe:0~25重量%、Co:残部であることが好ましい。
次に、本発明の鋳造材の製造方法について、説明する。
まず、本発明の鋳造材を形成するための原料粉末を準備する。原料粉末としては、鋳造材を形成する各元素の含有割合が所望の組成比となるように、準備すればよい。なお、本発明においては、原料粉末中に、予め硼化物及び/又は炭化物を主体とする硬質相粒子を含有させるようにしてもよいし、原料粉末中には硬質相粒子を含有させずに、原料粉末を用いて鋳造材を作製する過程で、鋳造材中に、原料粉末に含まれるホウ素や炭素に由来して、硼化物及び/又は炭化物を主体とする硬質相粒子が形成されるようにしてもよい。
本発明では、溶解混合物を冷却する際には、冷却開始温度から400℃までの温度範囲において、100℃/min.以上の冷却速度で継続して溶解混合物を冷却する過程を含むようにする。本発明において、100℃/min.以上の冷却速度で継続して溶解混合物を冷却する過程を含むようにするとは、一定程度継続して、100℃/min.以上の冷却速度となるような態様とすればよいことを意味し、好ましくは1分以上、より好ましくは5分以上継続して、100℃/min.以上の冷却速度にて冷却を行う過程が含まれていればよく、たとえば、瞬間的に100℃/min.以上の冷却速度となるような態様(たとえば、1秒以下だけ、100℃/min.以上の冷却速度となるような態様)は含まれないものである。なお、溶解混合物を冷却する際には、冷却開始温度から400℃までの温度範囲において、100℃/min.以上の冷却速度で継続して溶解混合物を冷却する過程を含むようにすればよいが、この際の冷却速度は、好ましくは200℃/min.以上、より好ましくは400℃/min.以上である。溶解混合物の冷却を上記条件で行うことによって、得られる鋳造材について、硬質相粒子の平均粒径、硬質相粒子のアスペクト比の平均値、硬質相粒子の長径の平均値、及び硬質相粒子同士の接触率を、上述した範囲に制御することができる。
なお、各特性の定義および評価方法は、以下のとおりである。
走査型電子顕微鏡(SEM)を用いて、鋳造材の切断面について、反射電子像の撮影を行い、上述した方法に従い、硬質相粒子の平均粒径、硬質相粒子のアスペクト比の平均値、長径が5μm超である硬質相粒子の個数及び硬質相粒子同士の接触率の測定を行った。なお、本実施例では、各測定を行う際における、直線Lの長さは42μmとし、測定領域範囲Sは2450μm2とした。
鋳造材について、硬度(ロックウェルCスケール)の測定を行なった。
鋳造材を、4mm×7mm×24mmのサイズとなるように切削加工することで、試験片を得て、得られた試験片について、CIS 026に準拠して、抗折力(3点曲げ試験)の測定を行なった。
Mo2NiB2型の複硼化物20重量%と、Ni基自溶性合金(組成は、Cr:10重量%、B:2重量%、Si:2.7重量%、C:0.4重量%、Fe:2重量%、Ni:残部。)80重量%とを乾式混合して、混合粉末を得た。次いで、得られた混合粉末を、るつぼに入れて、真空鋳造機(田邊研電社製 TCP-5250)を用いて、高周波溶解炉で1200℃まで昇温して溶融させることで溶解混合物を得て、得られた1200℃の溶解混合物を、400℃に熱した金型に流し込み、その後室温まで空冷することで鋳造材を得た。このとき、溶解混合物の温度を、高周波溶解炉から取り出してから2分後に測定したところ、温度は400℃であった。すなわち、溶解混合物は、高周波溶解炉から取り出された後の2分間で、1200℃から400℃まで冷却されたこととなり、この際の溶解混合物の冷却速度は400℃/min.であり、この結果より、溶解混合物は、1200℃から400℃までの範囲において、400℃/min.程度の冷却速度にて継続して冷却されたといえる。
Mo2NiB2型の複硼化物10重量%と、Ni基自溶性合金(組成は、B:2.3重量%、Si:7.1重量%、C:0.06重量%以下、Fe:1.5重量%、Ni:残部。)90重量%とを乾式混合して、混合粉末を得た。次いで、得られた混合粉末を、真空炉を用いて1160℃、30分間の条件で、真空中で焼き固めてインゴットを得た。その後、インゴットを、大気炉を用いて、大気中で1200℃まで昇温して溶解させることで溶解混合物を得て、得られた1200℃の溶解混合物を、20℃の室温の金型に流し込み、その後空冷することで鋳造材を得た。このとき、溶解混合物の温度を、大気炉から取り出してから約1分後に測定したところ、温度は400~500℃であった。すなわち、溶解混合物は、大気炉から取り出された後の1分間で、1200℃から400~500℃まで冷却されたこととなり、この際の溶解混合物の冷却速度は700~800℃/min.であり、この結果より、溶解混合物は、1200℃から400℃までの温度範囲において、700~800℃/min.程度の冷却速度にて継続して冷却される過程を経たといえる。
混合粉末として、Mo2NiB2型の複硼化物15重量%と、Ni基自溶性合金(組成は、B:2.3重量%、Si:7.1重量%、C:0.06重量%以下、Fe:1.5重量%、Ni:残部。)85重量%とを乾式混合したものを用いた以外は、実施例2と同様にして、鋳造材を得て、同様に各測定を行った。各測定のために撮影した走査型電子顕微鏡(SEM)による反射電子像を、図4(A)、図4(B)に示す。ここで、図4(B)は、図4(A)の一部を拡大した拡大図である。図4(A)、図4(B)の反射電子像では、白い領域が硼化物(硬質相粒子)であり、黒い領域が不純物であり、残りの灰色の領域がNi基合金である。なお、灰色の領域のうち、細長い形状をした部分(図4(B)において矢印で示した部分等)は、Ni基合金中の晶質の違いにより、Ni基合金の他の部分より色が濃く写っているものであって、あくまでNi基合金であり、硬質相粒子を構成するものではないと考えられる。
混合粉末として、Mo2NiB2型の複硼化物20重量%と、Ni基自溶性合金(組成は、B:2.3重量%、Si:7.1重量%、C:0.06重量%以下、Fe:1.5重量%、Ni:残部。)80重量%とを乾式混合したものを用いた以外は、実施例2と同様にして、鋳造材を得て、同様に各測定を行った。各測定のために撮影した走査型電子顕微鏡(SEM)による反射電子像を、図5(A)、図5(B)に示す。ここで、図5(B)は、図5(A)の一部を拡大した拡大図である。図5(A)、図5(B)の反射電子像では、白い領域が硼化物(硬質相粒子)であり、黒い領域が不純物であり、残りの灰色の領域がNi基合金である。なお、灰色の領域のうち、細長い形状をした部分(図5(B)において矢印で示した部分等)は、Ni基合金中の晶質の違いにより、Ni基合金の他の部分より色が濃く写っているものであって、あくまでNi基合金であり、硬質相粒子を構成するものではないと考えられる。
混合粉末に代えて、Ni基自溶性合金(組成は、Cr:10重量%、B:2重量%、Si:2.7重量%、C:0.4重量%、Fe:2重量%、Ni:残部。)のみを用いた以外は、実施例2と同様にして、鋳造材を得て、同様に各測定を行った。各測定のために撮影した走査型電子顕微鏡(SEM)による反射電子像を、図6(A)、図6(B)に示す。ここで、図6(B)は、図6(A)の一部を拡大した拡大図である。図6(A)、図6(B)の反射電子像では、黒い領域が炭化物(硬質相粒子)であり、残りの灰色の領域がNi基合金である。なお、炭化物は、Ni基自溶性合金中の炭素が、金属元素(Ni、CrまたはFe)と反応して形成されたものであると考えられる。
実施例1と同様にして得た混合粉末を、るつぼに入れて、真空熱処理炉(島津製作所社製 PVSGgr 20/20)を用いて1200℃まで昇温して溶融させた溶解混合物を、高周波溶解炉内で、約1時間かけて400℃まで徐冷して、鋳造材を得た。次いで、得られた鋳造材について、実施例1と同様に各測定を行った。各測定のために撮影した走査型電子顕微鏡(SEM)による反射電子像を、図7(A)、図7(B)に示す。ここで、図7(B)は、図7(A)の一部を拡大した拡大図である。図7(A)、図7(B)の反射電子像では、白い領域が硼化物(硬質相粒子)であり、黒い領域が炭化物であり、残りの灰色の領域がNi基合金である。
実施例1と同様にして得た混合粉末を、るつぼに入れて、真空熱処理炉(島津製作所社製 PVSGgr 20/20)を用いて1200℃まで昇温して溶融させた溶解混合物を、高周波溶解炉内で、約5時間かけて800℃まで徐冷して、鋳造材を得た。次いで、得られた鋳造材について、実施例1と同様に各測定を行った。各測定のために撮影した走査型電子顕微鏡(SEM)による反射電子像を、図8(A)、図8(B)に示す。ここで、図8(B)は、図8(A)と同じ試験片の高倍率電子像である。図8(A)、図8(B)の反射電子像では、白い領域が硼化物(硬質相粒子)であり、黒い領域が炭化物であり、残りの灰色の領域がNi基合金である。
混合粉末に代えて、Ni基自溶性合金(組成は、Cr:10重量%、B:2重量%、Si:2.7重量%、C:0.4重量%、Fe:2重量%、Ni:残部。)のみを用いた以外は、比較例2と同様にして、鋳造材を得て、同様に各測定を行った。各測定のために撮影した走査型電子顕微鏡(SEM)による反射電子像を、図9(A)、図9(B)に示す。ここで、図9(B)は、図9(A)の一部を拡大した拡大図である。図9(A)、図9(B)の反射電子像では、黒い領域が炭化物(硬質相粒子)であり、残りの灰色の領域がNi基合金である。
なお、上述した実施例2~5では、溶解混合物を、室温の金型に流し込み、その後空冷することで鋳造材を得たが、金型として、実施例1と同様に400℃に加熱された金型を用いた場合でも、冷却開始温度から400℃までの温度範囲において、100℃/min.以上の冷却速度で継続して溶解混合物を冷却する過程を経たものになると考えられるため、得られる鋳造材は、同様に、優れた耐食性及び耐摩耗性に加え、抗折力及び硬度が高いという特性を有するものになると考えられる。
また、比較例3の測定結果より、硬質相粒子同士が結合して大きな塊となってしまった鋳造材は、抗折力及び硬度が、いずれも低くなる結果であった。
Claims (7)
- 硼化物及び/又は炭化物を主体とする硬質相粒子と、Co及び/又はNiを主成分として含有する合金を含む結合相とからなる鋳造材であって、
前記硬質相粒子の平均粒径が3μm以下、前記硬質相粒子のアスペクト比の平均値が2.3以下、長径が5μm超である前記硬質相粒子の含有量が2450μm2あたり3個以下、前記硬質相粒子同士の接触率が40%以下である鋳造材。 - 前記硬質相粒子が、Ni,Co,Cr,Mo,Mn,Cu,W,Fe及びSiのうち少なくとも一種と、B及び/又はCとからなる硼化物及び/又は炭化物である請求項1に記載の鋳造材。
- 前記結合相が、Cr,Mo,Mn,Cu,W,Fe及びSiのうち少なくとも1種の金属と、Co及び/又はNiとの合金である請求項1又は2に記載の鋳造材。
- 前記鋳造材中におけるBの含有量が1~6重量%であり、前記鋳造材中におけるCの含有量が0~2.5重量%である請求項1~3のいずれかに記載の鋳造材。
- 前記硬質相粒子がMo2NiB2またはMo2(Ni,Cr)B2で表される複硼化物からなり、前記結合相がNi基合金からなる請求項1~4のいずれかに記載の鋳造材。
- 硼化物及び/又は炭化物を主体とする硬質相粒子と、Co及び/又はNiを主成分として含有する合金を含む結合相とからなる鋳造材の製造方法であって、
前記鋳造材を形成するための原料を混合させた状態で溶解させることで、溶解混合物を得る工程と、
前記溶解混合物を冷却する工程と、を有し、
前記溶解混合物を冷却する工程において、冷却開始温度から400℃までの温度範囲において、100℃/min.以上の冷却速度で継続して前記溶解混合物を冷却する過程を含む鋳造材の製造方法。 - 前記溶解混合物の冷却を、前記溶解混合物を、室温~1100℃の金型中に流し込むことにより行う請求項6に記載の鋳造材の製造方法。
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CN109128025A (zh) * | 2018-10-05 | 2019-01-04 | 重庆玛斯特机械制造有限公司 | 具有可控表面硬化层的凸轮轴铸件的制备方法 |
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CN109128025A (zh) * | 2018-10-05 | 2019-01-04 | 重庆玛斯特机械制造有限公司 | 具有可控表面硬化层的凸轮轴铸件的制备方法 |
CN109128025B (zh) * | 2018-10-05 | 2020-08-25 | 重庆玛斯特机械制造股份有限公司 | 具有可控表面硬化层的凸轮轴铸件的制备方法 |
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