JP2013155407A - Copper alloy and cast product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy of a Cu-Zn based alloy superior particularly in mechanical properties and castability, in which crystal grains can be refined reliably; and a cast product formed of the copper alloy.SOLUTION: The copper alloy has a composition including 60-90 mass% of Cu, 0.001-0.5 mass% of P, 1-100 mass ppm of S, 10-2,000 mass ppm of Zr, 5-2,000 mass ppm of one or more elements of Ca and Sr, and the balance Zn with unavoidable impurities.

Description

 The present invention relates to a copper alloy having excellent castability and mechanical properties, and a cast product made of the copper alloy.

  In copper alloys such as Cu-Zn alloys, it is known that mechanical properties are improved by refining crystal grains. For example, the strength of a copper alloy is improved in proportion to the 1/2 power of the reciprocal of the crystal grain size according to Hall Petch's law.

Further, it is known that in the cast product made of the above-described copper alloy, a large shrinkage cavity is generated because the molten metal is not sufficiently supplied to the space generated by the solidification shrinkage in the final solidified portion. For example, when gravity casting is performed, the shrinkage nest has a funnel shape, and small shrinkage holes are dotted on the lower side thereof.
In order to suppress such casting defects, it is effective to secure the fluidity of the molten metal even in the final stage of solidification by refining crystal grains that crystallize during solidification.

  Therefore, Patent Documents 1 and 2 propose a technique for refining crystal grains by co-adding Zr and P to a Cu-Zn alloy. That is, the crystal grains are refined by dispersing the Zr—P compound particles and generating primary crystals using the Zr—P compound particles as seed nuclei.

Japanese Patent No. 3964930 Japanese Patent No. 4095666

  However, as shown in Patent Documents 1 and 2, even when Zr-P compound particles are used as inoculation nuclei, there are cases where the refinement of crystal grains is insufficient. In particular, when the cooling rate during solidification is low, there is a problem that the crystal grains cannot be sufficiently refined.

  The present invention has been made in view of the above-described circumstances, and in a Cu-Zn alloy, a crystal grain can be reliably refined, and a copper alloy particularly excellent in mechanical properties and castability, and An object of the present invention is to provide a casting made of this copper alloy.

  In order to solve the above problems, the copper alloy of the present invention includes Cu; 60% by mass or more and 90% by mass or less, P; 0.001% by mass or more and 0.5% by mass or less, S; having a composition consisting of Zn and inevitable impurities, including: ppm or less, Zr; 10 mass ppm or more and 2000 mass ppm or less, at least one of Ca and Sr; 5 mass ppm or more and 2000 mass ppm or less. It is a feature.

  In the copper alloy having such a structure, P: 0.001 mass% to 0.5 mass%, S: 1 mass ppm to 100 mass ppm, Zr: 10 mass ppm to 2000 mass ppm, Ca and Sr Therefore, the α phase crystallized at the time of solidification becomes equiaxed dendrite and granular crystallization.

  Thereby, the fluidity of the molten metal is ensured even in the final stage of solidification, and the molten metal is sufficiently supplied to the space generated by the solidification shrinkage in the final solidified portion, thereby suppressing the generation of a large shrinkage nest. Therefore, there are fewer parts for cutting and removing the ingot to remove the shrinkage cavity, and the yield during casting can be greatly improved.

Furthermore, when the α phase to be crystallized is converted into equiaxed dendrites and granular crystallization, the solidified structure in the resulting ingot and casting (cast product) is also refined.
When the solidified structure is fine, mechanical properties such as strength and ductility are improved. Therefore, the workability of ingots and castings (cast products) is greatly improved, and it is possible to suppress the occurrence of defects such as cracks during hot working and cold working, thereby greatly improving production efficiency. it can.
In addition, since the solidification structure of the ingot and the casting (casting product) is refined, it is suppressed that the crystal grains are coarsened in the subsequent processing, and the crystal grains are refined in the processed product. Will be. Therefore, it is possible to improve mechanical properties such as strength and ductility in the processed product.

Here, in the above-mentioned copper alloy, it is preferable to further contain Mg; 5 mass ppm or more and 2000 mass ppm or less.
In this case, the dispersion of the Zr—P compound is promoted by the addition of Mg, and the crystal grains can be more reliably refined.

Furthermore, in the aforementioned copper alloy, a total of 15% by mass or less of one or more elements selected from Sn, Pb, Bi, Se, Fe, Ni, Al, Mn, Si, As, Sb, and Te. It may be contained within the range.
Since these elements are elements having the effect of improving various characteristics of the copper alloy, it is preferable to add these elements as appropriate according to the required characteristics.
Here, by limiting the total content of these elements to 15% by mass or less, the effect of crystal grain refinement can be reliably achieved. That is, when the total content of these elements exceeds 15% by mass, a non-α phase such as a β phase and a γ phase is crystallized, and the effect of refining crystal grains is reduced. In addition, if the total content of these elements exceeds 15% by mass, the electrical conductivity decreases, which is not preferable.

Moreover, in the above-mentioned copper alloy, at least one or more of a Ca—S compound containing Ca and S and a Sr—S compound containing Sr and S, the Ca—S compound and the Sr—S. It is preferable that there are composite compound particles (compound particles containing two or more phases) including Zr and P containing Zr and P in contact with the outside of the compound.
In this case, at least one of the Ca-S compound containing Ca and S and the Sr-S compound containing Sr and S are dispersed, and the Ca-S compound and the Sr-S compound are dispersed. Since the Zr-P compound containing Zr and P is disposed on the outside, the number of inoculated nuclei is ensured, and the α phase crystallized during solidification is surely converted into equiaxed dendrites and granular crystals. Can be realized. That is, compared with the case where only Zr and P are added, by adding at least one of Ca and Sr and S, at least one of at least one of the Ca-S compound and the Sr-S compound is added. The compound will promote the dispersion of the Zr-P compound.

The cast product of the present invention is a cast product made of the above-mentioned copper alloy, and is characterized in that the columnar crystal region is 10% or less of the cross section in the macro structure observation of the cross section.
Here, the cast product may include all of the casting start part and end part, and the intermediate part thereof. Usually, the cast product is obtained by removing part or all of the start part and end part. is there. The ratio may be a cross section parallel to the casting direction or a cross section perpendicular to the casting direction. The parallel or vertical cross section is selected to include the center of gravity of the casting.

Since the cast product having this configuration is composed of the above-described copper alloy, the α phase that crystallizes is converted into an equiaxed dendrite and granular crystallization, so that the solidification structure is refined and the columnar crystal region is reduced. Become. Here, when the columnar crystal region is 10% or less of the cross section, the equiaxed dendrite and granular crystallization of the α phase to be crystallized are sufficiently performed, and the strength of this cast product, Mechanical properties such as ductility are improved. Therefore, the workability of the cast product is greatly improved, and it is possible to prevent the occurrence of defects such as cracks during hot working and cold working.
Furthermore, the α phase that crystallizes is converted into equiaxed dendrites and granular crystallization, which improves the fluidity of the molten metal during casting, suppresses the formation of large shrinkage cavities, and greatly improves the yield during casting. Is possible.

Here, in the aforementioned cast product, in the observation of the microstructure of the cross section,
(Number of granular crystals) / (number of granular crystals + number of equiaxed dendrites) is preferably 50% or more. In addition, the part for observing the microstructure is a cross section parallel or perpendicular to the casting direction including the center of gravity of the cast product, and the center of gravity (when the center of gravity is a copper alloy) or the part with the slowest cooling rate. Observe (when the center of gravity becomes space).
In this case, the α phase crystallized is sufficiently refined, and mechanical properties such as strength and ductility of the cast product are improved. This is because granular crystals are finer than equiaxed dendrites. Therefore, the workability of the cast product is greatly improved, and it is possible to prevent the occurrence of defects such as cracks during hot working and cold working.

  According to the present invention, in a Cu-Zn alloy, it is possible to reliably refine crystal grains, and to provide a copper alloy particularly excellent in mechanical properties and castability, and a cast product made of this copper alloy. be able to.

It is a cooling curve of the carbon casting_mold | template in an Example. It is a cooling curve of the fireproof heat insulation material casting_mold | template in an Example. It is a photograph which shows an example of the macro structure observation result of the casting using a carbon casting_mold | template in an Example. It is a photograph which shows an example of the macro structure observation result of the casting using a carbon casting_mold | template in an Example. It is a photograph which shows an example of the macro structure observation result of the casting using a refractory heat insulation material casting_mold | template in an Example. It is a photograph which shows an example of the macro structure observation result of the casting using a refractory heat insulation material casting_mold | template in an Example. It is a photograph which shows an example of the microstructure observation result of the cast product using a carbon casting_mold | template in an Example. It is a photograph which shows an example of the microstructure observation result of the cast product using a carbon casting_mold | template in an Example. It is a photograph which shows an example of the microstructure observation result of the cast product using a carbon casting_mold | template in an Example. It is a photograph which shows an example of the microstructure observation result of the casting using a refractory heat insulation material casting_mold | template in an Example. It is a photograph which shows an example of the microstructure observation result of the casting using a refractory heat insulation material casting_mold | template in an Example. It is a photograph which shows an example of the microstructure observation result of the casting using a refractory heat insulation material casting_mold | template in an Example. In an Example, it is a figure which shows the Auger analysis result of the crystallization thing which exists in a granular crystal. In an Example, it is a figure which shows the Auger analysis result of the crystallization thing which exists in a granular crystal.

Below, the copper alloy which is embodiment of this invention, and the castings which consist of this copper alloy are demonstrated.
In the copper alloy of this embodiment, at least one or more of a Ca—S compound containing Ca and S and a Sr—S compound containing Sr and S, the Ca—S compound, and the Sr There are composite compound particles (compound particles containing two or more phases) including Zr and P containing Zr and P in contact with the outside of the -S compound. The composite compound particles are used as inoculum nuclei to form a primary α phase.

  Here, the copper alloy according to the present embodiment is Cu: 60 mass% or more and 90 mass% or less, P: 0.001 mass% or more and 0.5 mass% or less, S: 1 mass ppm or more and 100 mass ppm or less, Zr Including 10 mass ppm or more and 2000 mass ppm or less, at least one of Ca and Sr; 5 mass ppm or more and 2000 mass ppm or less, with the balance being composed of Zn and inevitable impurities.

Furthermore, Mg; 5 mass ppm or more and 2000 mass ppm or less may be included.
Furthermore, it contains one or more elements selected from Sn, Pb, Bi, Se, Fe, Ni, Al, Mn, Si, As, Sb, and Te within a total range of 15% by mass or less. May be.

  The reason why the contents of these elements are set in the above-described range will be described below.

(Cu, Zn)
The copper alloy which is this embodiment has Cu and Zn as main components.
Here, when the Cu content is less than 60% by mass, that is, when the Cu content is small with respect to Zn or the like, the primary crystal becomes the β phase, and the crystal grains can be refined. There is a risk of disappearing. In addition, properties such as ductility, cold workability, discoloration resistance, stress corrosion cracking resistance, and pressability are deteriorated.
On the other hand, when the Cu content exceeds 90 mass%, that is, when the Cu content is large relative to Zn or the like, the strength and wear resistance are reduced, and the effect of refining crystal grains is reduced. There is a fear.
For these reasons, the Cu content is set to 60% by mass or more and 90% by mass or less.
Zn is an element that affects mechanical properties such as tensile strength and proof stress, but its content is defined as the balance of other elements such as Cu from the relationship with other contained elements.

(Zr, P)
Zr and P are elements having an effect of making crystal grains finer by being co-added.
Here, when the content of Zr is less than 10 mass ppm and the content of P is less than 0.001 mass%, the above-described crystal grain refining effect cannot be sufficiently achieved.
Also, since Zr has a strong affinity for oxygen, Zr oxides and the like are likely to be generated, the viscosity of the molten metal is increased, and entrainment defects such as oxides during casting are likely to occur. In addition, blow holes and microporosity are likely to occur. Moreover, when it exceeds 2000 mass ppm, the effect which refines | miniaturizes a crystal grain will also weaken. In consideration of these, the Zr content is preferably set to 2000 mass ppm or less.
Furthermore, since P is an element that affects corrosion resistance, castability, and the like, the P content is preferably 0.5% by mass or less.
From the above, in this embodiment, the content of Zr is set in the range of 10 ppm to 2000 ppm by mass. In addition, in order to make the above-mentioned effect effective, it is preferable to set the content of Zr within a range of 15 ppm to 200 ppm by mass.
Further, the P content is set in a range of 0.001% by mass to 0.5% by mass.

(Ca and Sr, S)
Ca and S or Sr and S are elements having an effect of refining crystal grains by co-addition.
Here, when the content of at least one of Ca and Sr is less than 5 ppm by mass and the content of S is less than 1 ppm by mass, the above-described crystal grain refining effect can be sufficiently achieved. Can not.
Further, since Ca and Sr have a strong affinity for oxygen, Ca and Sr oxides are likely to be generated, the viscosity of the molten metal is increased, and entrapment defects such as oxides during casting are likely to occur. . On the other hand, if it exceeds 2000 ppm by mass, the non-α phase, which is presumed to be a β phase or a γ phase, is increased, so that ductility is lowered and the effect of refining crystal grains is also lowered. In consideration of this, the content of at least one of Ca and Sr is preferably 2000 mass ppm or less.
Furthermore, since S is an element which affects hot workability, it is preferable to set it as 100 mass ppm or less.
From the above, in this embodiment, the content of at least one of Ca and Sr is set in the range of 5 mass ppm to 2000 mass ppm.
Further, the content of S is set within a range of 1 mass ppm to 100 mass ppm. In addition, in order to make the above-mentioned effect effective, it is preferable to set the content of S within a range of 1 ppm to 30 ppm by mass.

Here, in this embodiment, the mass ratio Zr / (Ca + Sr) between Zr and at least one of Ca and Sr is in the range of 0.05 ≦ Zr / (Ca + Sr) ≦ 5. It is desirable.
When the mass ratio Zr / (Ca + Sr) is less than 0.05, the Zr—P compound is relatively small, and thus there is a possibility that the effect of refining crystal grains cannot be sufficiently achieved.
When the mass ratio Zr / (Ca + Sr) exceeds 5, since the Ca—S compound and the Sr—S compound are relatively reduced, the effect of refining crystal grains may be reduced.
The crystal grain refinement effect by the compound compound particles (compound particles containing two or more phases) including at least one of a Ca-S compound and a Sr-S compound and a Zr-P compound is reliably achieved. In order to cause this, the mass ratio Zr / (Ca + Sr) is more preferably in the range of 0.1 ≦ Zr / (Ca + Sr) ≦ 3.5.

(Mg)
Mg is an element having the effect of making crystal grains finer by being co-added with S.
Here, when the content of Mg is less than 5 ppm by mass, the effect of refining crystal grains cannot be sufficiently achieved.
On the other hand, if the Mg content exceeds 2000 ppm by mass, the non-α phase, which is presumed to be a β phase or a γ phase, increases, resulting in a decrease in ductility and a reduction in crystal grain refining effect. Furthermore, since Mg has a strong affinity for oxygen, Mg oxide and the like are likely to be generated, the viscosity of the molten metal is increased, and entrainment defects such as oxide during casting are likely to occur.
Therefore, when adding Mg, it is preferable to make Mg content into 5 mass ppm or more and 2000 mass ppm or less.

(Sn, Pb, Bi, Se, Fe, Ni, Al, Mn, Si, As, Sb, Te)
These elements have the effect of improving various properties of the copper alloy. For example, elements such as Sn, Fe, Mn, Si, and Al have the effect of improving the strength. Further, elements such as Sn, Ni, Al, Si, As, and Sb have an effect of improving the corrosion resistance. Furthermore, elements such as Pb, Bi, Se, and Te have an effect of improving machinability. Therefore, it is preferable to appropriately add these elements according to required characteristics.
Here, when the total content of these elements exceeds 15% by mass, a non-α phase such as a β phase or a γ phase is crystallized, which may reduce the effect of refining crystal grains. . Moreover, there exists a possibility that electrical conductivity may fall large. Therefore, when these elements are contained, the total amount is set to 15% by mass or less.

  Other inevitable impurities include Ti, Hf, C, Ba, Sc, Y, rare earth elements, V, Nb, Ta, Cr, Mo, W, Re, Ru, Os, Rh, Ir, Pd, Pt, Examples include Au, Cd, Ga, In, Li, Ge, Tl, O, Co, Ag, B, Be, N, H, and Hg. These inevitable impurities are preferably 0.3% by mass or less in total.

  Moreover, the cast product which is this embodiment is comprised with the copper alloy made into the above-mentioned composition, and the columnar crystal area | region is 10% or less of the said cross section in the macro structure observation of a cross section. Further, in the cast product according to the present embodiment, (the number of granular crystals) / (the number of granular crystals + the number of equiaxed dendrites) is 50% or more in the observation of the microstructure of the cross section. In the cast product having such a macro structure and a microstructure, the refinement of the cast structure is sufficiently achieved.

That is, the α phase that crystallizes is converted into equiaxed dendrites and granular crystallization, thereby reducing the width and length of the columnar crystals and reducing the columnar crystal regions, and increasing the equiaxed crystal regions. Become. More preferably, there is no columnar crystal region and the entire surface is an equiaxed crystal region. However, when the diameter of the equiaxed crystal becomes very fine, the equiaxed crystal may not be confirmed with the naked eye.
When equiaxed dendrites or granular crystals are crystallized, the particle size of the α phase can be measured by the following observation of the microstructure. Here, the part for observing the microstructure is a cross section parallel or perpendicular to the casting direction including the center of gravity of the cast product, and the center of gravity (when the center of gravity is a copper alloy) or the slowest cooling rate. Observe the part (when the center of gravity is a space). When the crystal grain size of the cast product according to this embodiment is measured by the test method (cutting method) defined in JIS H 0501, the crystal grain size of the granular crystal is 0.3 mm or less, preferably 0.2 mm or less. More preferably, it is 0.1 mm or less.

This cast product is manufactured as follows.
First, the above-described elements are added to a molten copper obtained by melting a copper raw material to adjust the components, thereby producing a molten copper alloy. In addition, an element simple substance, a mother alloy, etc. can be used for the addition of an element. Moreover, you may melt | dissolve the raw material containing these elements with a copper raw material.
Here, the molten copper is preferably so-called 4NCu having a purity of 99.99% or more. Of course, recycled materials and scrap materials of this alloy may also be used.

Further, in the melting step, it is preferable to use a vacuum furnace or an atmosphere furnace having an inert gas atmosphere or a reducing atmosphere in order to suppress oxidation of Zr, Ca, Sr and the like. In the case of an atmospheric furnace, it may be added in consideration of the decrease due to oxidation.
Then, the copper alloy molten metal whose components are adjusted is poured into a mold to produce an ingot and a casting. When mass production is considered, it is preferable to use a continuous casting method or a semi-continuous casting method. Die casting, low pressure casting, and sand casting are also preferable.

According to the copper alloy of the present embodiment configured as described above and a cast product made of this copper alloy, P: 0.001 mass% or more and 0.5 mass% or less, S: 1 mass ppm or more 100 mass ppm or less, Zr; 10 mass ppm or more and 2000 mass ppm or less, at least one or more of Ca and Sr; 5 mass ppm or more and 2000 mass ppm or less, Zr-P containing Zr and P The compound, and at least one or more of a Ca—S compound containing Ca and S and a Ca—S compound containing Sr and S are sufficiently present.
Therefore, composite compound particles (compound particles containing two or more phases) including at least one of a Ca—S compound and a Sr—S compound and a Zr—P compound are dispersed. When the primary compound α phase is generated using the composite compound particles as inoculum nuclei, the α phase crystallized during solidification becomes equiaxed dendrite and granular crystallization.

Therefore, the fluidity of the molten metal is ensured even in the final stage of solidification, and the molten metal is sufficiently supplied to the space generated by the solidification shrinkage in the final solidified portion, and the generation of a large shrinkage can be suppressed. .
Furthermore, the α phase that crystallizes is converted into equiaxed dendrites and granular crystallization, whereby the solidification structure in the cast product (ingot and cast) is also refined. Specifically, the cast product according to the present embodiment has a columnar crystal region of 10% or less of the cross section in the macro structure observation of the cross section. In observation, (number of granular crystals) / (number of granular crystals + number of equiaxed dendrites) is preferably 50% or more.
Thus, since the solidified structure is fine in the cast product, mechanical properties such as strength and ductility are improved. Therefore, the workability of the cast product is greatly improved, and it is possible to prevent the occurrence of defects such as cracks during hot working and cold working.

  Further, in addition to the above elements, Mg: 5 mass ppm or more and 2000 mass ppm or less will promote the dispersion of the Zr—P compound, and further refine the crystal grains more reliably. It becomes possible.

  Moreover, various characteristics can be improved by containing one or more elements selected from Sn, Pb, Bi, Se, Fe, Ni, Al, Mn, Si, As, Sb, and Te. It becomes possible. Moreover, since the total content of these elements is 15% by mass or less, non-α phase such as β phase and γ phase can be prevented from crystallizing, and the effect of crystal grain refinement can be surely achieved. Can do.

  Furthermore, Ti, Hf, C, Ba, Sc, Y, rare earth elements, V, Nb, Ta, Cr, Mo, W, Re, Ru, Os, Rh, Ir, Pd, Pt, Au, Cd, Ga, In , Li, Ge, Tl, O, Co, Ag, B, Be, N, H, Hg, etc., the total amount is 0.3 mass% or less, so the addition of Zr, P, Ca and Sr, S Thus, the effect of refining crystal grains can be surely achieved.

As mentioned above, although the copper alloy which is embodiment of this invention was demonstrated, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, elements other than Cu, Zn, P, S, Zr, Ca, and Sr may be added as necessary.

Further, since S is an element present as an inevitable impurity in the copper alloy, it is not necessary to add it positively during melt casting.
Furthermore, although an example of the manufacturing method of a copper alloy (cast product) has been described, the manufacturing method is not limited to this embodiment, and an existing manufacturing method may be selected as appropriate.

Below, the result of the confirmation experiment performed in order to confirm the effect of this invention is demonstrated.
A copper raw material composed of oxygen-free copper having a purity of 99.99% or more was prepared, charged in an alumina crucible, and high-frequency melted in an atmosphere furnace having an Ar gas atmosphere. Various additive elements were added to the obtained molten copper to prepare the component compositions shown in Table 1-8, and poured into a carbon mold and a refractory heat insulating material mold to produce an ingot. Isolite (registered trademark) was used as the refractory heat insulating material. The casting temperature was 1100 ° C. The size of the ingot was about 20 mm thick x about 20 mm wide x about 60-80 mm long for the carbon mold, and about 30 mm thick x about 30 mm wide x about 30-40 mm long for the refractory insulation mold.
The cooling rate from 900 ° C. to 800 ° C. is about 7 ° C./sec for the carbon mold and about 0.5 ° C./sec for the refractory heat insulating material mold, as shown in FIGS.

(Determination of coagulated tissue)
As shown in FIGS. 3 to 6, the ingot was cut in half along the longitudinal direction, this longitudinal section was polished, etched with nitric acid, and the macrostructure was observed.
Moreover, after cutting an ingot in half along the longitudinal direction, the observation sample was extract | collected from the predetermined location and the observation surface was grind | polished. Then, etching was performed using a mixed solution of sulfuric acid and nitric acid as a corrosive solution, and the microstructure was observed with an optical microscope. Note that the observation sample was collected from the center of gravity of the ingot, that is, the center of the length, width, and thickness unless otherwise specified.

Here, FIGS. 3 to 6 show examples in which the macro structure is observed. 3 and 4 are those using a carbon mold, and FIGS. 5 and 6 are those using a refractory heat insulating material mold.
As shown in FIGS. 3 and 5, when the columnar crystal region is 10% or more, the macro structure determination is “x”.
As shown in FIGS. 4 and 6, when the columnar crystal region is less than 10% and most of the cross section is composed of equiaxed crystals, the macro structure determination is “◯”.

7 to 12 show examples in which the microstructure is observed. FIGS. 7 to 9 use a carbon mold, and FIGS. 10 to 12 use a refractory heat insulating material mold.
When the columnar crystal region was more than 10% of the cross section in the macro structure observation, the columnar crystal region was micro-observed. As a result, columnar dendrites were observed as shown in FIGS. When such columnar dendrites were observed, the microstructure determination was “XX”.
When the columnar crystal region was 10% or less of the cross section in the macro structure observation, the above-mentioned microscopic observation of the center of gravity was performed. As a result, two types of equiaxed dendrites and granular crystals were observed. Therefore, as shown in FIG. 8 and FIG. 11, when (number of granular crystals) / (number of granular crystals + number of equiaxed dendrites) is less than 50%, the microstructure determination is “x”. As shown in FIG. 9 and FIG. 12, when (number of granular crystals) / (number of granular crystals + number of equiaxed dendrites) is 50% or more, the microstructure determination is “◯”.
The evaluation results are shown in Table 1-8.

In Comparative Example 1-5, the macro structure evaluation and the micro structure evaluation of the carbon mold and the refractory heat insulating material mold were all “X” and “XX”. In Comparative Example 6 in which Zr exceeds the range of the present invention, the macro structure evaluation of the carbon template was “◯”, but otherwise “x” and “XX”.
In Comparative Example 7 in which appropriate amounts of Zr and P are added and at least one of Ca and Sr is not added, macro structure evaluation and micro structure evaluation of the carbon mold, and macro structure evaluation of the refractory heat insulating material mold Was “◯”, but the microstructure evaluation of the refractory insulation mold was “×”. That is, it was confirmed that when the cooling rate was low, a sufficient miniaturization effect could not be obtained.
In Comparative Example 8 in which the Ca content exceeds the range of the present invention and in Comparative Example 9 in which the Sr content exceeds the range of the present invention, the microstructure evaluation of the refractory heat insulating material mold was “x”. .

On the other hand, in the present invention example 1-86, which is within the composition range of the present invention, any one of the macro structure evaluation and the micro structure evaluation of the carbon mold, and the macro structure evaluation and the micro structure evaluation of the refractory heat insulating material mold Momo was “○”.
In the present invention examples 12-23 and 30-86 containing Sn, Pb, Bi, Se, Fe, Ni, Al, Mn, Si, As, Sb, and Te as additive elements, a sufficient miniaturization effect can be obtained. Was possible.

  In addition, Auger analysis was performed on the crystallized substance present in the center of the α-phase granular crystal of the cast product of the fireproof heat insulating material mold of Example 12 of the present invention. The results are shown in FIG. As a result, a composite compound particle comprising the Ca—S compound containing Ca and S and the Zr—P compound containing Zr and P in contact with the outside of the Ca—S compound (containing the above two phases). Compound particles were confirmed to be present. It is presumed that the composite compound particles became α phase inoculum nuclei and a high nucleation density was obtained.

  Furthermore, Auger analysis of the crystallized substance existing in the central part of the α-phase granular crystal of the cast product of the refractory heat insulating material mold of Example 3 of the present invention was performed. The results are shown in FIG. As a result, a composite compound particle (containing the above two phases) comprising a Sr-S compound containing Sr and S and a Zr-P compound containing Zr and P in contact with the outside of the Sr-S compound. Compound particles were confirmed to be present. It is presumed that the composite compound particles became α phase inoculum nuclei and a high nucleation density was obtained.

Claims (6)

Cu: 60% by mass or more and 90% by mass or less,
P; 0.001 mass% or more and 0.5 mass% or less,
S: 1 mass ppm or more and 100 mass ppm or less,
Zr: 10 mass ppm or more and 2000 mass ppm or less,
At least one of Ca and Sr; 5 mass ppm or more and 2000 mass ppm or less,
A copper alloy having a composition in which the balance is made of Zn and inevitable impurities. The copper alloy according to claim 1,
Furthermore, Mg; The copper alloy characterized by including 5 mass ppm or more and 2000 mass ppm or less. In the copper alloy according to claim 1 and claim 2,
Containing one or more elements selected from Sn, Pb, Bi, Se, Fe, Ni, Al, Mn, Si, As, Sb, and Te within a total range of 15% by mass or less. Characteristic copper alloy. In the copper alloy according to any one of claims 1 to 3,
At least one or more of a Ca—S compound containing Ca and S and a Sr—S compound containing Sr and S, Zr in contact with the outside of the Ca—S compound and the Sr—S compound, and The copper alloy characterized by the presence of composite compound particles comprising a Zr-P compound containing P. A cast product comprising the copper alloy according to any one of claims 1 to 4,
A cast product characterized in that a columnar crystal region is 10% or less of the cross section in the macro structure observation of the cross section. The casting according to claim 5,
In cross-sectional microstructure observation,
A cast product, wherein (number of granular crystals) / (number of granular crystals + number of equiaxed dendrites) is 50% or more.