KR102500630B1 - Mold materials for casting and Cu-Cr-Zr-Al alloy materials - Google Patents

Abstract

A casting mold material used when casting metal materials, containing 0.3 mass% or more and less than 0.5 mass% of Cr, 0.01 mass% or more and 0.15 mass% or less of Zr, and 0.1 mass% or more and less than 2.0 mass% of Al, It has a composition consisting of additive Cu and unavoidable impurities, and is characterized by having acicular precipitates or plate-like precipitates.

Description

Mold materials for casting and Cu-Cr-Zr-Al alloy materials

The present invention relates to, for example, a casting mold material used when casting metal such as steel material, and a Cu-Cr-Zr-Al alloy material suitable for the above-mentioned mold material for casting.

This application claims priority based on Japanese Patent Application No. 2015-203581 for which it applied to Japan on October 15, 2015, and uses the content here.

Conventionally, casting mold materials used when casting steel materials and the like are required to have excellent properties such as high-temperature strength to withstand large thermal stress, high-temperature elongation to withstand severe thermal fatigue environments, and high-temperature wear resistance (hardness). . Therefore, Cu-Cr-Zr-based alloys having excellent properties are used as mold materials for continuous casting. In the Cu-Cr-Zr-based alloys described above, it is known that the above-described characteristics are improved by further adding additive elements.

In addition, in the mold material for electromagnetic stirring, the penetration depth (δ) of the magnetic field is expressed by the following formula when the magnetic permeability (μ), the frequency (f) of the applied magnetic field, and the conductivity (σ) are used.

δ = (1/π μ f σ) ^0.5

As can be seen from this equation, in order to increase the magnetic field depth δ, it is preferable that the conductivity σ of the mold material is low. However, if the conductivity σ is too low, the thermal conductivity may decrease and cooling may become insufficient.

For this reason, in the mold material, it is proposed to adjust the conductivity σ to about 30 to 60% IACS by adding additive elements other than Cr and Zr.

For example, in Patent Document 1, a precipitation hardening type continuous casting containing 0.3 to 1.5% Cr and 0.03 to 0.6% Zr by weight ratio and further adding elements such as Al and Si, Ni, Sn, Zn, Mn, etc. A quiet mold material is disclosed.

Further, in Patent Document 2, a casting material for metal casting containing 0.3 to 1.2 wt% of Cr and 0.05 to 0.25 wt% of Zr and further adding Sn, Al, Ag, Ni, Ti, Co, Fe, etc. has been initiated.

In the Cu-Cr-Zr-based alloys described in Patent Literatures 1 and 2 described above, a non-equilibrium supersaturated solid solution of Cr and Zr is formed by solution treatment, and then Cr and Zr are dispersed by aging treatment By precipitating, mechanical properties such as high-temperature strength, high-temperature elongation, wear resistance (hardness), electrical conductivity, and thermal conductivity are improved. In addition, in order to form the above-mentioned supersaturated solid solution, it is necessary to perform rapid cooling after the solution heat treatment.

Japanese Patent Publication No. 62-041302 (A) Japanese Unexamined Patent Publication No. Hei 05-339688 (A)

However, in a mold material for casting, it is common to spray a Ni-Cr alloy or the like excellent in heat resistance and wear resistance on the surface to improve durability. When the thermal spraying treatment described above is performed, for example, after performing heat treatment in a high temperature range of about 1000 ° C., it is slowly cooled without performing water cooling, so even if aging treatment is performed after thermal spraying, strength (hardness) and electrical conductivity There was a problem that this did not improve enough.

More specifically, after heat treatment in a high temperature range of about 1000 ° C., for example, when slow cooling is performed at a cooling rate of 25 ° C./min or less to 800 ° C., precipitates having granular Cr during slow cooling ( Cr-based precipitates) and Zr-containing precipitates (Zr-based precipitates) are precipitated. In the subsequent aging treatment, Cr and Zr dissolved in solid solution using these granular precipitates as nuclei precipitate, which causes the precipitates to grow and coarsen, making it impossible to sufficiently secure fine precipitates contributing to the precipitation strengthening mechanism. , it becomes impossible to achieve improvement in strength (hardness).

The present invention has been made in view of the above circumstances, and a mold material for casting, which can sufficiently improve strength (hardness) and conductivity by a subsequent aging treatment even when annealed after thermal spray treatment, and this mold material for casting It is an object of the present invention to provide a Cu-Cr-Zr-Al alloy material suitable for

In order to solve the above problems, a mold material for casting according to one aspect of the present invention (hereinafter referred to as "the mold material for casting of the present invention") is a mold material for casting used when casting a metal material, and contains Cr It has a composition containing 0.3 mass% or more and less than 0.5 mass%, 0.01 mass% or more and 0.15 mass% or less of Zr, 0.1 mass% or more and less than 2.0 mass% of Al, the balance being Cu and unavoidable impurities, and needle-like precipitates or plate-like precipitates. It is characterized by having

In the mold material for casting having this configuration, Cr is 0.3 mass% or more and less than 0.5 mass%, Zr is 0.01 mass% or more and 0.15 mass% or less, Al is 0.1 mass% or more and less than 2.0 mass%, and the balance is Cu and unavoidable. Since it is composed of impurities, the strength (hardness) and electrical conductivity can be improved by precipitating fine precipitates through aging treatment. In addition, the conductivity can be adjusted to about 30 to 60% IACS, and it is particularly suitable as a mold material for electromagnetic stirring.

In addition, since the mold material for casting of the present invention has acicular precipitates or plate-like precipitates containing Cr, the formation of granular precipitates during slow cooling after thermal spraying is suppressed. For this reason, during the aging treatment after the thermal spray treatment, the precipitation of Cr and Zr using the granular precipitates as nuclei is suppressed, the fine precipitates can be sufficiently dispersed, and the strength (hardness) and electrical conductivity are sufficiently improved by the precipitation strengthening mechanism. can improve

Here, in the mold material for casting of the present invention, it is preferable that the maximum size of the acicular precipitates or the plate-like precipitates is 100 μm or less. In addition, the maximum size of the acicular precipitate or the plate-like precipitate was the diameter of the observed precipitate when the minimum circumscribed circle was drawn.

In this case, since the maximum size of the needle-like precipitates or the plate-like precipitates is relatively small, such as 100 μm or less, Cr is sufficiently dissolved in the Cu mother phase, and the fine precipitates can be sufficiently dispersed during the subsequent aging treatment. Strength (hardness) and conductivity can be sufficiently improved by the strengthening mechanism.

Further, in the mold material for casting of the present invention, it is preferable to further contain one or more elements selected from Fe, Si, Co, and P in a total amount of 0.01 mass% or more and 0.15 mass% or less.

In this case, since elements such as Fe, Si, Co, and P are contained within the above-mentioned range, the formation of granular precipitates is suppressed during slow cooling after thermal spray treatment, and the formation of needle-like precipitates or plate-like precipitates containing Cr creation is stimulated. Therefore, by the aging treatment after the thermal spray treatment, fine Cr-based and Zr-based precipitates can be sufficiently precipitated, and the strength (hardness) and electrical conductivity can be surely improved.

The Cu-Cr-Zr-Al alloy material of the present invention contains 0.3 mass% or more and less than 0.5 mass% of Cr, 0.01 mass% or more and 0.15 mass% or less of Zr, and 0.1 mass% or more and less than 2.0 mass% of Al, It has a composition consisting of additional Cu and unavoidable impurities, and the conductivity (%IACS) after cooling at 1000 °C to 600 °C at a cooling rate of 10 °C/min after holding at 1000 °C for 1 hour was A, and then 3 at 500 °C It is characterized by having a relationship of B/A > 1.1 when B is the electrical conductivity (%IACS) after holding the time.

In the Cu-Cr-Zr-Al alloy material having this configuration, after holding at 1000 ° C. for 1 hour, the cooling rate from 1000 ° C. to 600 ° C. was cooled at 10 ° C./min, and the conductivity (% IACS) was A, When the conductivity (%IACS) after holding at 500°C for 3 hours is B, the relationship is B/A > 1.1, so when the cooling rate from 1000°C to 600°C is slowly cooled at 10°C/min Even after that, the conductivity is improved by heat treatment at 500°C for 3 hours, and it is possible to improve the strength by precipitation hardening.

For this reason, it is particularly suitable as a material for the mold material for casting described above.

Here, in the Cu-Cr-Zr-Al alloy material of the present invention, one or more elements selected from Fe, Si, Co, and P are further included in a total amount of 0.01 mass% or more and 0.15 mass% or less. desirable.

In this case, since elements such as Fe, Si, Co, and P are contained within the above range, unnecessary precipitation of Cr and Zr is suppressed even when slowly cooled after heating to a high temperature region of, for example, about 1000 ° C. Thus, a high capacity of Cr and Zr can be secured. Therefore, fine precipitates can be sufficiently precipitated by the aging treatment after slow cooling, and the strength (hardness) and electrical conductivity can be surely improved.

According to the present invention, a casting mold material capable of sufficiently improving strength (hardness) and electrical conductivity by subsequent aging treatment even when annealed after thermal spray treatment, and Cu-Cr-Zr- suitable for this casting mold material Al alloy material can be provided.

1 is a flowchart of a method for manufacturing a mold material for casting, which is an embodiment of the present invention.
2 is tissue observation photographs of Example 2 and Comparative Example 4 of the present invention.
Fig. 3A is a diagram showing acicular precipitates or plate-like precipitates observed by SEM images in Example 2 of the present invention.
Fig. 3B is a diagram showing the result of elemental mapping of acicular precipitates or plate-like precipitates observed with EPMA (Cr) in Example 2 of the present invention.
Fig. 3C is a diagram showing the elemental mapping results of acicular precipitates or plate-like precipitates observed with EPMA (Zr) in Example 2 of the present invention.
Fig. 4 is an explanatory diagram showing a Vickers hardness measurement position in an example.

Hereinafter, a mold material for casting and a Cu-Cr-Zr-Al alloy material, which are one embodiment of the present invention, will be described.

The mold material for casting according to the present embodiment is used for a mold for continuous casting when continuously casting a steel material or the like. Further, in the present embodiment, the Cu-Cr-Zr-Al alloy material is used as a material for the mold material for casting described above.

In the mold material for casting and the Cu-Cr-Zr-Al alloy material according to the present embodiment, Cr is 0.3 mass% or more and less than 0.5 mass%, Zr is 0.01 mass% or more and 0.15 mass% or less, and Al is 0.1 mass% or more and 2.0 mass%. It has a composition of less than %, the remainder being Cu and unavoidable impurities, and further containing one or more elements selected from Fe, Si, Co, and P in a total amount of 0.01 mass% or more and 0.15 mass% or less.

Here, as described above, the reason for defining the component composition of the mold material for casting and the Cu-Cr-Zr-Al alloy material will be described below.

(Cr: 0.3 mass% or more and less than 0.5 mass%)

Cr is an element that has an effect of improving strength (hardness) and electrical conductivity by finely precipitating Cr-based precipitates in crystal grains of the parent phase by aging treatment.

Here, when the content of Cr is less than 0.3 mass%, the amount of precipitation in the aging treatment becomes insufficient, and there is a possibility that the effect of improving strength (hardness) cannot be sufficiently obtained. In addition, when the Cr content is 0.5 mass% or more, for example, when slow cooling is performed in which the cooling rate from a high temperature range of about 1000°C to a temperature of 800°C or less is 25°C/min or less, the granular Cr system And Zr-based precipitates precipitate, and these granular precipitates further grow in the aging treatment after slow cooling, so there is a risk that fine precipitates contributing to the precipitation strengthening mechanism cannot be secured.

From the above, in this embodiment, the content of Cr is set within the range of 0.3 mass% or more and less than 0.5 mass%. In addition, in order to reliably exhibit the above-mentioned effects, the lower limit of the Cr content is preferably 0.35 mass% or more, and the upper limit of the Cr content is preferably 0.45 mass% or less.

(Zr: 0.01 mass% or more and 0.15 mass% or less)

Zr is an element having an effect of improving strength (hardness) and electrical conductivity by finely precipitating Zr-based precipitates at the grain boundaries of the parent phase by aging treatment.

Here, when the content of Zr is less than 0.01 mass%, the amount of precipitation in the aging treatment becomes insufficient, and there is a risk that the effect of improving strength (hardness) cannot be sufficiently obtained. In addition, when the content of Zr exceeds 0.15 mass%, there is a possibility that electrical conductivity and thermal conductivity may decrease. In addition, even if Zr is contained in an amount exceeding 0.15 mass%, there is a possibility that an additional strength improving effect may not be obtained.

From the above, in the present embodiment, the content of Zr is set within the range of 0.01 mass% or more and 0.15 mass% or less. In addition, in order to reliably exhibit the above-mentioned effects, the lower limit of the Zr content is preferably 0.05 mass% or more, and the upper limit of the Zr content is preferably 0.13 mass% or less.

(Al: 0.1 mass% or more and less than 2.0 mass%)

Al is an element that has an effect of reducing electrical conductivity by dissolving into a copper alloy. Therefore, by controlling the addition amount of Al, the conductivity of the mold material for casting can be adjusted to about 30 to 60% IACS, making it particularly suitable as a mold material for electromagnetic stirring.

Here, when the content of Al is less than 0.1 mass%, it becomes difficult to suppress the electrical conductivity to a low level, and there is a possibility that the penetration depth of the magnetic field cannot be secured. In addition, when the content of Al is 2.0 mass% or more, there is a possibility that the electrical conductivity greatly decreases and the thermal conductivity becomes insufficient.

From the above, in this embodiment, the content of Al is set within the range of 0.1 mass% or more and less than 2.0 mass%. In addition, in order to reliably exhibit the above-mentioned effects, the lower limit of the Al content is preferably 0.5 mass% or more, and the upper limit of the Al content is preferably 1.5 mass% or less.

(One or two or more elements selected from Fe, Si, Co, and P: 0.01 mass% or more and 0.15 mass% or less in total)

Elements such as Fe, Si, Co, and P are, for example, granular Cr-based and It has the effect of suppressing the precipitation of Zr-based precipitates and promoting the precipitation of Cr-containing acicular precipitates or plate-like precipitates.

Here, when the total content of one or two or more elements selected from Fe, Si, Co, and P is less than 0.01 mass%, there is a risk that the above-described action and effect may not be exhibited. On the other hand, when the total content of one or two or more elements selected from Fe, Si, Co, and P exceeds 0.15 mass%, electrical conductivity and thermal conductivity may decrease.

From the above, in the present embodiment, the total content of one or more elements selected from Fe, Si, Co, and P is set within the range of 0.01 mass% or more and 0.15 mass% or less. In addition, in order to reliably exhibit the above-mentioned effects, it is preferable to set the lower limit of the total content of one or two or more elements selected from Fe, Si, Co, and P to 0.02 mass% or more, and Fe and Si The upper limit of the total content of one or more elements selected from , Co, and P is preferably 0.1 mass% or less.

(Other unavoidable impurities: 0.05 mass% or less)

In addition, other unavoidable impurities other than Cr, Zr, Al, P, Fe, Si, and Co described above include B, Ag, Sn, Zn, Ti, Ca, Te, Mn, Ni, Sr, Ba, Sc, Y, Ti, Hf, V, Nb, Ta, Mo, W, Re, Ru, Os, Se, Rh, Ir, Pd, Pt, Au, Cd, Ga, In, Li, Ge, As, Sb, Tl, Pb, Be, N, H, Hg, Tc, Na, K, Rb, Cs, Po, Bi, lanthanoids, O, S, C and the like. Since these unavoidable impurities may reduce electrical conductivity and thermal conductivity, it is preferable to set the total amount to 0.05 mass% or less.

And, the mold material for casting of this embodiment has acicular precipitates or plate-like precipitates containing Cr in the parent phase of Cu. The maximum size of these acicular precipitates or plate-like precipitates is 100 μm or less.

Whether it "has acicular precipitates or plate-like precipitates containing Cr" is judged based on the criteria described below.

A sample for observation is taken from the mold material for casting, and a structure is observed with a scanning electron microscope for the polished cross section after polishing, and the presence or absence of needle-like precipitates or plate-like precipitates containing Cr is confirmed. .

Whether or not "containing Cr" can be known from analysis of the composition by EPMA.

Whether it is a "acicular precipitate or a plate-like precipitate" is judged from the shape of the precipitate in a cross-section as an object of tissue observation. First, the longest diameter of the precipitate is obtained as a longitudinal direction size from the shape of the precipitate. Then, among the diameters in the direction orthogonal to the diameter in the longitudinal direction, the longest diameter among the precipitates is obtained as a diameter in the transverse direction (traverse direction size). If the value of the aspect ratio (diameter in the longitudinal direction/diameter in the width direction) is 5 or more, the precipitate is judged to be "acicular precipitate or plate-like precipitate".

Further, in the mold material for casting according to the present embodiment, fine Cr-based and Zr-based precipitates having a grain size of, for example, 5 μm or less are dispersed. In addition, these fine Cr-based and Zr-based precipitates precipitated in the aging treatment after slow cooling.

The needle-like precipitates or plate-like precipitates described above are formed during slow cooling after thermal spraying of a Ni-Cr alloy excellent in heat resistance and wear resistance when producing a mold material for casting. More specifically, in the present embodiment, Cr is 0.3 mass% or more and less than 0.5 mass%, Zr is 0.01 mass% or more and 0.15 mass% or less, and Al is 0.1 mass% or more and less than 2.0 mass%, the balance being Cu and unavoidable impurities. For a copper alloy made of, after being heated to, for example, 1000 ° C. or higher during thermal spray treatment, slow cooling is performed so that the cooling rate from a high temperature range of about 1000 ° C. to a temperature of 600 ° C. or lower is 10 ° C./min or less. At this time, acicular precipitates or plate-like precipitates containing Cr are precipitated. This suppresses the precipitation of granular Cr-based and Zr-based precipitates during slow cooling.

In addition, the Cu-Cr-Zr-Al alloy material of the present embodiment has the same composition as the above-mentioned mold material for casting, and after holding at 1000 ° C. for 1 hour, the cooling rate from 1000 ° C. to 600 ° C. is 10 ° C./ When the conductivity (%IACS) after cooling to min is A and the conductivity (%IACS) after holding at 500°C for 3 hours is B, the relationship is B/A > 1.1.

That is, in the Cu-Cr-Zr-Al alloy material of the present embodiment, after holding at 1000 ° C. for 1 hour, even when the cooling rate from 1000 ° C. to 600 ° C. is slowly cooled at 10 ° C./min, thereafter 500 ° C. , the conductivity is improved by the heat treatment held for 3 hours.

Next, a method for manufacturing a mold material for casting according to an embodiment of the present invention will be described with reference to a flowchart of FIG. 1 .

(Melt and casting process S01)

First, a copper raw material made of oxygen-free copper having a copper purity of 99.99 mass% or more is charged into a carbon crucible and melted using a vacuum melting furnace to obtain molten copper. Then, to the obtained molten metal, the above additive elements are added so as to have a predetermined concentration, component preparation is performed, and a copper alloy molten metal is obtained.

Here, materials of high purity are used as raw materials for Cr, Zr, and Al, which are additive elements. , A raw material of Al having a purity of 99.95 mass% or higher is used. Moreover, Fe, Si, Co, and P are added as needed. In addition, you may use a master alloy with Cu as a raw material of Cr, Zr, Fe, Si, Co, and P.

Then, the molten copper alloy whose ingredients have been prepared is poured into a mold to obtain an ingot.

(Homogenization treatment step S02)

Next, heat treatment is performed for homogenization of the obtained ingot.

Specifically, the ingot is subjected to a homogenization treatment under conditions of 950 ° C. or more and 1050 ° C. or less for 1 hour or more in an air atmosphere.

(Hot working process S03)

Next, the ingot is subjected to hot rolling at a working rate of 50% or more and 99% or less in a temperature range of 900°C or more and 1000°C or less to obtain a rolled material. In addition, hot forging may be sufficient as the hot working method. After this hot working, it is immediately cooled by water cooling.

(Solution Treatment Step S04)

Next, the rolled material obtained in the hot working step S03 is subjected to a heat treatment under the conditions of 920°C or more and 1050°C or less for 0.5 hours or more and 5 hours or less, followed by solution heat treatment. Heat treatment is performed, for example, in air or an inert gas atmosphere, and cooling after heating is performed by water cooling.

(First Aging Treatment Step S05)

Next, after the solution heat treatment step S04, a first aging treatment is performed to finely precipitate precipitates such as Cr-based precipitates and Zr-based precipitates to obtain a first aging-treated material.

Here, the first aging treatment is performed under conditions of, for example, 400°C or more and 530°C or less, and 0.5 hour or more and 5 hours or less.

In addition, although the heat treatment method at the time of aging treatment is not specifically limited, It is preferable to carry out in an inert gas atmosphere. In addition, although the cooling method after heat treatment is not specifically limited, It is preferable to carry out water cooling.

Through such a process, the Cu-Cr-Zr-Al alloy material of the present embodiment is manufactured.

(thermal spray treatment process S06)

Subsequently, after the first aging treatment step S05, a Ni-Cr alloy or the like is thermally sprayed on a predetermined point on the surface of the Cu-Cr-Zr-Al alloy material, and a coating layer is formed on a predetermined point on the surface of the Cu-Cr-Zr-Al alloy material. form And, after this thermal spraying, the Cu-Cr-Zr-Al alloy material on which the coating layer is formed is subjected to heat treatment at 900 ° C. or more and 1000 ° C. or less for 15 minutes or more and 180 minutes or less. This heat treatment is performed for diffusion bonding between the Cu-Cr-Zr-Al alloy material and the coating layer.

Cooling after the heat treatment after this spraying is performed is performed by, for example, slow cooling with a relatively low cooling rate such as furnace cooling. Here, the cooling rate of the slow cooling is, for example, a cooling rate in the range of 800°C or less from the heat treatment temperature of 5°C/min or more and 70°C/min or less.

(Second aging treatment step S07)

Next, after the thermal spray treatment step S06, a second aging treatment is performed to finely precipitate precipitates such as Cr-based precipitates and Zr-based precipitates.

Here, the aging treatment is performed under conditions of, for example, 400°C or more and 530°C or less, and 0.5 hours or more and 5 hours or less.

In addition, although the heat treatment method at the time of aging treatment is not specifically limited, It is preferable to carry out in an inert gas atmosphere. In addition, the cooling method after heat treatment is not particularly limited, but it is preferable to perform water cooling.

Through such a process, a mold material for casting according to the present embodiment is manufactured.

According to the mold material for casting according to the present embodiment configured as described above, Cr is 0.3 mass% or more and less than 0.5 mass%, Zr is 0.01 mass% or more and 0.15 mass% or less, and Al is 0.1 mass% or more and less than 2.0 mass%. Since the composition is composed of Cu and unavoidable impurities, the strength (hardness) and conductivity can be improved by finely precipitating Cr-based and Zr-based precipitates in the second aging treatment step S07. In addition, since Al is contained in the range of 0.1 mass% or more and less than 2.0 mass%, the conductivity can be adjusted to about 30 to 60% IACS, and is particularly suitable as a mold material for electromagnetic stirring applications.

And, since the mold material for casting according to the present embodiment has acicular precipitates or plate-like precipitates containing Cr, the formation of granular precipitates during slow cooling after the thermal spray treatment step S06 is suppressed, and the thermal spray treatment step S06 Fine precipitates can be sufficiently dispersed by the later second aging treatment step S07, and the strength (hardness) can be sufficiently improved by the precipitation strengthening mechanism.

Further, in the mold material for casting according to the present embodiment, since the maximum size of the Cr-containing acicular precipitates or plate-like precipitates is relatively small, such as 100 μm or less, Cr is sufficiently dissolved in the Cu mother phase, and thermal spray treatment By the second aging treatment step S07 after step S06, fine precipitates can be sufficiently dispersed, and strength (hardness) and electrical conductivity can be sufficiently improved by the precipitation strengthening mechanism.

Further, since the mold material for casting according to the present embodiment further contains one or two or more elements selected from Fe, Si, Co, and P in a total amount of 0.01 mass% or more and 0.15 mass% or less, thermal spray treatment Formation of granular precipitates is suppressed during slow cooling after step S06, and production of acicular precipitates or plate-like precipitates containing Cr is promoted. Therefore, by the second aging treatment step S07 after the thermal spray treatment step S06, fine precipitates can be sufficiently precipitated, and the strength (hardness) and electrical conductivity can be reliably improved.

Further, in the Cu-Cr-Zr-Al alloy material according to the present embodiment, after holding at 1000 ° C. for 1 hour, cooling from 1000 ° C. to 600 ° C. at a cooling rate of 10 ° C./min. Conductivity (% IACS) A, and then, when the conductivity (%IACS) after holding at 500 ° C. for 3 hours is B, it has a relationship of B / A > 1.1, so in the thermal spray treatment step S06, for example, a high temperature of about 1000 ° C. Even in the case of annealing after heating in reverse, the conductivity is improved in the second aging treatment step S07 after annealing, and the strength (hardness) can be improved by precipitation hardening.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical thought of the invention.

In the present embodiment, it has been described as containing 0.01 mass% or more and 0.15 mass% or less of one or two or more types of elements selected from Fe, Si, Co, and P in total, but it is not limited to this, and these elements are intentionally do not need to be added.

Example

The results of confirmation experiments conducted to confirm the effects of the present invention will be described below.

A copper raw material composed of oxygen-free copper having a purity of 99.99 mass% or more was prepared, charged into a carbon crucible, and melted in a vacuum melting furnace (vacuum degree of 10 ^-2 Pa or less) to obtain molten copper. Into the obtained molten copper, various additive elements were added to prepare the component composition shown in Table 1, and after holding for 5 minutes, the molten copper alloy was poured into a cast iron mold to obtain an ingot. The size of the ingot was about 80 mm in width, about 50 mm in thickness, and about 130 mm in length.

In addition, the raw material of Cr as an additive element was used with a purity of 99.99 mass% or higher, the raw material for Zr with a purity of 99.95 mass% or higher, and the raw material for Al with a purity of 99.99 mass% or higher.

Next, after performing the homogenization treatment on condition of 1000 degreeC for 1 hour in an air atmosphere, hot rolling was implemented. The rolling reduction at the time of hot rolling was 80%, and a hot-rolled material having a width of about 100 mm, a thickness of about 10 mm, and a length of about 520 mm was obtained.

Using this hot-rolled material, solution heat treatment was performed at 1000°C for 1.5 hours, and then it was cooled with water.

Next, the first aging treatment was performed at 500 (± 15) ° C. for 3 hours. Thus, a Cu-Cr-Zr-Al alloy material was obtained.

Next, with respect to the obtained Cu-Cr-Zr-Al alloy material, thermal spray treatment was simulated and heat treatment was performed at 1000 ° C. for 1 hour, and thereafter, a cooling rate of 10 ° C./min from 1000 ° C. to 600 ° C. cooled down with

Thereafter, a second aging treatment was performed at 500°C for 3 hours. Thus, a mold material for casting was obtained.

The obtained Cu-Cr-Zr-Al alloy material was evaluated for Vickers hardness (rolled surface) and electrical conductivity.

In addition, Vickers hardness (rolled surface) and electrical conductivity were evaluated for the casting mold material after the thermal spray treatment and the second aging treatment. In addition, the structure was observed and the presence or absence of Cr-containing acicular precipitates or plate-like precipitates was evaluated.

(composition analysis)

The component compositions of the obtained Cu-Cr-Zr-Al alloy material and mold material for casting were measured by ICP-MS analysis. Table 1 shows the measurement results.

(tissue observation)

A sample for observation was taken from the obtained mold material for casting, and after the polishing treatment, the structure was observed with a scanning electron microscope, and the presence or absence of acicular precipitates or plate-like precipitates containing Cr was confirmed. Table 2 shows the observation results. 2 shows the results of observing the structure of the samples of Example 3 of the present invention and Comparative Example 2 after the first aging treatment, the thermal spraying treatment and slow cooling, and the second aging treatment. Further, the enlarged observation results of Cr-containing acicular precipitates or plate-like precipitates observed in Example 3 of the present invention are shown in Figs. 3A to 3C.

(maximum size of precipitate)

For the acicular precipitates or plate-like precipitates observed as described above, a minimum circumscribed circle was drawn, and the diameter of the minimum circumscribed circle was taken as the maximum size of the precipitate.

(Vickers hardness measurement)

In accordance with JIS Z 2244, Vickers hardness was measured at 9 points on the test piece as shown in Fig. 4 with a Vickers hardness tester manufactured by Akashi Co., Ltd., and the average value of 7 measured values excluding the maximum and minimum values was obtained. Table 2 shows the measurement results after the first aging treatment, the thermal spray treatment, and the second aging treatment.

(conductivity measurement)

Using SIGMA TEST D2.068 (probe diameter: φ6 mm) manufactured by Japan Foerster, the central portion of the cross section of the 10 × 15 mm sample was measured three times, and the average value was obtained. Table 2 shows the measurement results after the first aging treatment, the thermal spray treatment, and the second aging treatment.

As shown in Table 2, in the examples of the present invention, after holding at 1000 ° C. for 1 hour, cooling at a cooling rate from 1000 ° C. to 600 ° C. at 10 ° C./min (after thermal spray treatment), conductivity (% IACS) When A is set to A, and the conductivity (%IACS) after holding at 500°C for 3 hours (after the second aging treatment) is set to B, it is confirmed that B/A > 1.1 has a relationship.

Moreover, as shown in Table 2, in the examples of the present invention, it is confirmed that they have acicular precipitates or plate-like precipitates containing Cr. And in the examples of the present invention, compared to the comparative examples, it is confirmed that the Vickers hardness and electrical conductivity are greatly increased by the second aging heat treatment.

In addition, as a result of the observation of the structure, in Comparative Example 2, as shown in FIG. 2, no needle-like precipitates or plate-like precipitates containing Cr were observed in the test piece annealed after the thermal spray treatment, but granular precipitates were observed.

On the other hand, in Example 4 of the present invention, as shown in Fig. 2, needle-like precipitates or plate-like precipitates containing Cr were observed in the test piece annealed after the thermal spray treatment.

Further, as a result of enlarged observation of the precipitates of the test piece after the second aging heat treatment of Example 4 of the present invention, as shown in Figs. 3A to 3C, Cr was detected from the acicular precipitates or plate-like precipitates, and Cr and Zr is being detected.

Even if a mold material for casting made of a Cu-Cr-Zr-Al alloy material is thermally sprayed and then subjected to aging treatment, the strength (hardness) and conductivity of the mold material for casting can be sufficiently improved, and durability in a harsh environment can be achieved. A more excellent mold material for casting can be provided.

Claims (5)

As a casting mold material for electromagnetic stirring,
A composition containing 0.3 mass% or more and less than 0.5 mass% of Cr, 0.01 mass% or more of Zr and 0.15 mass% or less of Al, 0.1 mass% or more and less than 2.0 mass% of Al, the remainder being Cu and unavoidable impurities,
It has acicular precipitates or plate-like precipitates,
The aspect ratio of the acicular precipitate or the plate-like precipitate is 5 or more,
The mold material for casting, characterized in that the conductivity of the mold material for casting is 30 to 60% IACS. According to claim 1,
The mold material for casting, characterized in that the size of the acicular precipitates or the plate-like precipitates is 100 μm or less. According to claim 1 or 2,
A mold material for casting characterized by further containing 0.01 mass% or more and 0.15 mass% or less of one or more elements selected from Fe, Si, Co, and P in total. As a Cu-Cr-Zr-Al alloy material for producing the mold material for casting according to claim 1,
A composition containing 0.3 mass% or more and less than 0.5 mass% of Cr, 0.01 mass% or more of Zr and 0.15 mass% or less of Al, 0.1 mass% or more and less than 2.0 mass% of Al, the remainder being Cu and unavoidable impurities,
The conductivity (%IACS) after cooling at 10°C/min at a cooling rate of 10°C/min from 1000°C to 600°C after holding at 1000°C for 1 hour is A, and the conductivity (%IACS) after holding at 500°C for 3 hours thereafter is In the case of B, a Cu-Cr-Zr-Al alloy material characterized by having a relationship of B / A > 1.1. According to claim 4,
Further, a Cu-Cr-Zr-Al alloy material characterized by containing 0.01 mass% or more and 0.15 mass% or less of one or more elements selected from Fe, Si, Co, and P in total.

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