JP6822889B2 - Copper alloy material, manufacturing method of copper alloy material and cage rotor - Google Patents

Description

The present invention relates to a copper alloy material, a method for producing a copper alloy material, and a cage rotor.

Conventionally, in a squirrel-cage rotor (squirrel-cage motor) having a rotor bar and an end ring (rotor core), from the viewpoint of improving the efficiency of the squirrel-cage motor, the study of forming the rotor bar and the end ring from a copper alloy material. Is underway. As such a copper alloy material, for example, a copper alloy material made of a copper alloy obtained by adding zirconium (Zr) or the like to copper (Cu) (see, for example, Patent Documents 1 and 2) may be used.

Japanese Unexamined Patent Publication No. 2011-94175 Japanese Unexamined Patent Publication No. 2014-173156

When the rotor bar and the end ring are made of a copper alloy material, they are usually bonded by a brazing method or the like. However, since the above-mentioned copper alloy material has a low Zr content, its strength decreases when it is heated at a high temperature for brazing or the like. As a result, the rotor bar and end ring may be deformed due to the centrifugal force acting during the rotation of the cage motor. Further, the above-mentioned copper alloy material has low conductivity because it contains a large amount of aluminum (Al), tin (Sn), phosphorus (P) and the like in addition to Zr and is solid-solved in Cu. When used in a motor or the like that flows a large current, there is also a problem that the loss due to electric resistance becomes large.

An object of the present invention is to provide a copper alloy material capable of maintaining high strength and high conductivity even when heated at a high temperature, and related techniques thereof.

According to one aspect of the invention
It contains Zr of 0.1% by mass or more and 0.2% by mass or less, and the balance is formed of a copper alloy composed of Cu and unavoidable impurities.
A precipitate of Cu ₅ Zr, which is a compound of Zr and Cu, is precipitated in the matrix phase.
When observing the cross section in the direction orthogonal to the stretching direction, the copper alloy material having 5000 pieces / mm ² or more of the precipitates having a diameter of 0.2 μm or more, and the copper alloy material are the end ring and the rotor bar. A cage-type rotor used in the above is provided.

According to another aspect of the invention
A step of casting an ingot containing Zr of 0.1% by mass or more and 0.2% by mass or less and the balance of which is Cu and unavoidable impurities.
A step of hot-stretching the heated ingot to form a stretched material, and
Water cooling is started within 60 seconds after the formation of the stretched material is completed to cool the stretched material, or the temperature of the stretched material is equal to or higher than the heating temperature of the ingot in the step of forming the stretched material. A step of cooling the stretched material by starting water cooling within 60 seconds after heating the stretched material to a temperature.
Provided is a method for producing a copper alloy material, which comprises a step of performing an aging heat treatment in which the cooled stretched material is heated at a temperature of 350 ° C. or higher and 550 ° C. or lower for 30 minutes or longer.

According to the present invention, high strength and high conductivity can be maintained even when the copper alloy material is heated to a high temperature for brazing or the like.

<Knowledge obtained by inventors>
Prior to the description of the embodiment of the present invention, the findings obtained by the present inventor will be described.

Conventionally, an aluminum material or an aluminum alloy material (hereinafter, also referred to as an aluminum alloy material) has been used as a material for forming the above-mentioned rotor bar and end ring (hereinafter, also referred to as a rotor bar or the like). However, in recent years, from the viewpoint of improving the efficiency of the squirrel-cage motor, studies on forming a rotor bar or the like with a copper alloy material as described above have been advanced. Since Cu has a lower electrical resistance than Al, it is said that the efficiency of the motor is improved by several percent when the rotor bar or the like is formed of a copper alloy material or the like as compared with the case where the rotor bar or the like is formed of an aluminum alloy material or the like.

When the rotor bar or the like is formed of an aluminum alloy material or the like, the melting point of Al is relatively low at about 660 ° C. Therefore, a method of pouring aluminum or an aluminum alloy into a predetermined mold and forming the rotor bar and the end ring at once. (Die casting method) is used.

On the other hand, when the rotor bar or the like is formed of a copper alloy material, it is difficult to use the above-mentioned die casting method. This is because the melting point of Cu is as high as about 1085 ° C., and there are problems such as shortening the life of the mold. Therefore, in this case, a rotor bar and an end ring having a plurality of slots formed are prepared, and after inserting the rotor bar into the slot of the end ring, for example, brazing or welding (brazing, etc.) is performed on this insertion point. Is used to integrate the rotor bar and the endling.

From the viewpoint of preventing deformation of the rotor bar or the like even when a strong centrifugal force acts on the rotor bar or the like due to the rotation of the motor, the rotor bar or the like is required to have high strength. Therefore, a work-hardened copper alloy material (work-hardened material) is used as a material for forming the rotor bar and the like. The work-hardened material is a copper alloy material that is work-hardened by accumulating strain by performing plastic working such as drawing. For this reason, the work-hardened material has a higher strength than, for example, an annealed material. For example, the tensile strength of the oxygen-free copper annealing material (O material) is 230 N / mm ² , whereas the tensile strength of the work-hardened material (H material) is 360 N / mm ^2, which means that the H material is better. Is stronger than O material.

However, when the work-hardened material described above is exposed to a high temperature, the work-hardened copper crystals recrystallize and release the strain, so that the strength is lowered. For example, when the rotor bar and the endling are integrated by brazing with silver wax, the rotor bar and the like are exposed to a high temperature of 800 ° C. or higher. Therefore, even when the rotor bar or the like is formed of a work-hardened material, the strength of the rotor bar or the like may decrease due to high-temperature heating during brazing, and the rotor bar or the like may be deformed by the above-mentioned centrifugal force.

Therefore, in order to suppress the decrease in strength due to high-temperature heating, a copper alloy material (mainly Cu-Zr) formed by adding Zr or the like to Cu and precipitating Zr precipitates in the copper matrix (matrix). It is considered to use a copper alloy material (Cu—Zr-based alloy material) as used for a rotor bar or the like. The Zr precipitate means a precipitate produced by the reaction of Cu and Zr. Further, since the Cu—Zr-based alloy material has an extremely low solid solution limit of Zr, the amount of Zr that is solid-solved in the matrix phase by high-temperature heating during brazing is extremely small. Therefore, the Cu-Zr-based alloy material has a significantly smaller decrease in conductivity due to heating than the copper alloy material whose main component is a component other than Cu-Zr. From this, it can be said that the Cu—Zr-based alloy material is a suitable material for forming a rotor bar or the like.

However, even in the case of Cu—Zr-based alloy materials, if the Zr content is too large, the amount of Zr that is solid-dissolved in the matrix due to high-temperature heating increases, and the decrease in conductivity becomes large. On the other hand, if the content of Zr in the Cu—Zr alloy material is small, the decrease in strength due to high temperature heating during brazing cannot be sufficiently suppressed. It is considered that this is because the number of the above-mentioned Zr precipitates required for suppressing the decrease in strength due to high-temperature heating is small, or even if the number of Zr precipitates is sufficient, the size is insufficient.

Therefore, the present inventors have conducted diligent research in order to suppress a decrease in strength and a decrease in conductivity due to high-temperature heating in a copper alloy material made of a Cu—Zr-based alloy. As a result, it has been found that the above-mentioned problems can be solved by appropriately adjusting the size and number of Cu ₅ Zr precipitates among the Zr precipitates precipitated in the matrix in this copper alloy material. It was. The present invention is based on the above findings found by the present inventors.

<One Embodiment of the present invention>
(1) Configuration of Squirrel-Cage Rotor First, a configuration of a squirrel-cage rotor (cage-type induction motor, squirrel-cage motor) according to an embodiment of the present invention will be described.

The cage rotor according to the present embodiment includes two annular endlings and a plurality of rotor bars. End rings are provided at both ends of each rotor bar. Each end ring is provided with a plurality of slots into which the end portion of the rotor bar can be inserted, and the rotor bar and the end ring are joined by inserting the end portion of the rotor bar into each slot. Then, the joint portion is brazed, welded, or the like, and the rotor bar and the endling are integrated. The rotor bar and end ring are made of a copper alloy material.

(2) Composition of Copper Alloy Material The composition of the copper alloy material preferably used for the rotor bar and end ring of the above-mentioned cage rotor will be described below.

The copper alloy material according to this embodiment contains a predetermined amount of zirconium (Zr), and the balance is composed of copper (Cu) and unavoidable impurities. The copper alloy material is stretched in a predetermined direction and formed into a rod shape by, for example, stretching.

As Cu, which is the base material of the copper alloy material, oxygen-free copper (OFC: Oxygen Free) having an oxygen (O) concentration of 0.0005% by mass or less, for example, from the viewpoint of suppressing a decrease in conductivity (conductivity). It is preferable to use Copper) or the like.

By containing Zr in the copper alloy material, Zr reacts with Cu, and as a result, a precipitate of Cu ₅ Zr, which is one of the compounds of Zr and Cu, is contained in the copper alloy material (matrix). Precipitate. Depending on the content of Zr in the copper alloy material, the size and number (number of precipitates) of Cu ₅ Zr precipitates (hereinafter, also simply referred to as “Cu ₅ Zr”) precipitated in the matrix change, and high temperature heating is performed. The amount of Zr that dissolves in the matrix of the subsequent copper alloy material changes. Therefore, it is desirable that the content of Zr in the copper alloy material is, for example, 0.1% by mass or more and 0.2% by mass or less, preferably 0.12% by mass or more and 0.16% by mass or less.

If the Zr content is less than 0.1% by mass, the size of Cu ₅ Zr precipitated in the matrix phase of the copper alloy material may be small, or the number of precipitates may be small. By setting the Zr content to 0.1% by mass or more, this problem can be solved, and a predetermined size and a predetermined number of Cu ₅ Zr can be precipitated in the matrix phase. For example, in a cross section in a direction orthogonal to the stretching direction of the copper alloy material (hereinafter, also referred to as “cross section of the copper alloy material”), 5000 Cu ₅ Zr having a diameter (minimum width across the board) of 0.2 μm or more is 5000 pieces / mm. Cu ₅ Zr can be precipitated so that there are ^two or more. By setting the Zr content to 0.12% by mass or more, a predetermined size and a predetermined number of Cu ₅ Zr can be reliably precipitated.

When the Zr content exceeds 0.2% by mass, the amount of Zr that dissolves in the matrix of the copper alloy material after high-temperature heating (for example, after heating for 10 minutes under a temperature condition of 830 ° C.) increases. .. This is because Cu ₅ Zr precipitated in the copper alloy material is solid-solved in the matrix phase when the copper alloy material is heated at a high temperature. By setting the Zr content to 0.2% by mass or less, this problem can be solved, and by setting the Zr content to 0.16% by mass or less, this problem can be surely solved. As a result, it is possible to suppress a decrease in the conductivity of the copper alloy material after heating at a high temperature.

In addition to the above-mentioned Zr, the copper alloy material includes magnesium (Mg), titanium (Ti), zinc (Zn), iron (Fe), cobalt (Co), manganese (Mn), silver (Ag), and silicon (Si). ), Chromium (Cr) and tin (Sn), one or more components (subcomponents) selected from the group are preferably contained in the range of, for example, 0.1% by mass or less. When two or more kinds selected from the above-mentioned group consisting of Mg and the like are contained in the copper alloy material, the total amount (total content) of the two or more kinds of components is preferably within the above range.

Since the above-mentioned Mg and the like have the property of improving the strength of the copper alloy material, the strength of the copper alloy material (copper alloy material before high-temperature heating) can be increased by containing Mg and the like in the copper alloy material. It can be improved, and as a result, the strength of the copper alloy material after high temperature heating is also increased. For example, in the case of a copper alloy material having the same number of Cu ₅ Zr precipitated in the matrix phase, the copper alloy material containing Mg or the like is more than the copper alloy material containing no Mg or the like. The strength of the copper alloy material after high-temperature heating increases.

When the content of Mg or the like exceeds 0.1% by mass, the amount of the compound produced by the reaction of Zr and Mg or the like increases. As a result, the amount of Zr consumed in the formation of the compound of Zr and Mg or the like increases, so that a predetermined number of Cu ₅ Zr cannot be precipitated in the matrix unless the Zr content is increased. Further, if the content of Mg or the like is increased too much, it may become one of the factors for lowering the conductivity of the copper alloy material (copper alloy material after high temperature heating).

(3) Method for Producing Copper Alloy Material Next, the method for producing the copper alloy material according to the present embodiment will be described by exemplifying a continuous casting method.

(Casting process)
An electrolytic copper as a raw material is melted using a high-frequency melting furnace or the like to produce a copper solution. At this time, it is preferable to coat the surface of the electrolytic copper or the surface of the generated copper solution with charcoal (carbon). As a result, carbon (C) contained in charcoal and oxygen (O) in electrolytic copper (copper solution) can be reacted to convert O into CO gas and remove it from the solution. That is, the copper solution can be deoxidized. As a result, a molten copper (oxygen-free copper) having an O concentration of 0.0005% by mass or less can be obtained.

A predetermined amount of Zr is added to the molten metal of oxygen-free copper to melt a copper alloy (melted copper alloy). At this time, the amount of Zr added is adjusted so that the content of Zr in the finally formed copper alloy material is 0.1 to 0.2% by mass, preferably 0.12 to 0.16% by mass. adjust. Further, if necessary, the above-mentioned Mg or the like may be added to the molten copper alloy (melted oxygen-free copper), and in this case, the content of Mg or the like in the finally formed copper alloy material. Adjust the amount of Mg or the like added so that is 0.1% by mass or less. The molten copper alloy thus produced is poured into a mold (out of hot water) and cooled to solidify, and an ingot having a predetermined composition and a predetermined shape is cast. In the present embodiment, an example of producing a billet having a circular cross-sectional shape in the width direction and a predetermined diameter as an ingot will be described.

In the billet immediately after casting, a large number of coarse crystallized products (Cu ₅ Zr) crystallized in the copper alloy in the process of solidifying the molten copper alloy are present.

(Extending process)
After the casting process is completed, the casting material is stretched (hot working, hot extrusion) using a stretching machine such as an extruder or a drawing machine. In this embodiment, a case where an extrusion die, which is a kind of extruder, is used as the extruder is illustrated. That is, here, the billet is hot-stretched (hot-extruded) using an extruded die to form a stretched material (extruded material). By performing hot stretching, the coarse Cu ₅ Zr existing in the billet can be divided and the Cu ₅ Zr can be miniaturized.

In this stretching step, after heating the billet so that the temperature of the billet becomes a predetermined temperature (for example, 850 ° C. or higher), the reduction rate is, for example, 60% or more, preferably 80% or more, with respect to the billet. Perform hot extension. As a result, the billet is stretched to become a stretched material having a predetermined shape (for example, a rod shape). The surface reduction rate is represented by the following (Equation 1).
(Equation 1)
Surface reduction rate (%) = {(cross-sectional area of billet-cross-sectional area of stretched material) / cross-sectional area of billet} x 100

In the above (Equation 1), the "cross-sectional area of the billet" means the cross-sectional area of the billet in the width direction before stretching. Further, the "cross-sectional area of the stretched material" means the cross-sectional area of the stretched material obtained by stretching in the width direction (direction orthogonal to the stretching (extruding) direction).

By stretching Cu ₅ Zr so that the surface reduction rate is 60% or more and dividing Cu ₅ Zr, Cu ₅ Zr precipitated in the finally formed copper alloy material is reduced to a predetermined size and a predetermined number. can do. For example, in the cross section of the copper alloy material, 5000 pieces / mm ² or more of Cu ₅ Zr having a diameter of 0.2 μm or more can be present. By stretching so that the surface reduction rate is 80% or more, Cu ₅ Zr can be sufficiently divided, and the above effect can be obtained more reliably. On the other hand, if the reduction rate of elongation is less than 60%, the division of Cu ₅ Zr becomes insufficient, and the size and number of Cu ₅ Zr precipitated in the finally formed copper alloy material. May not be the specified size and number.

(Cooling process)
After the stretching step is completed, the stretched material is cooled by water cooling until it reaches at least 100 ° C. or lower. This water cooling is performed within 60 seconds (after extruding the extruded material from the extruded die), preferably within 10 seconds, and more preferably immediately after forming the extruded material (immediately after extruding the extruded material from the extruded die). It is desirable to start (immediately after extrusion, that is, immediately after stretching)).

By starting water cooling within 60 seconds after forming the stretched material (hereinafter, also simply referred to as “after stretching”) to cool the stretched material, Cu ₅ Zr divided in the above-mentioned stretching step is aggregated by residual heat. It is possible to prevent it from becoming coarse again. By starting water cooling of the stretched material within 10 seconds after stretching, more preferably immediately after stretching, aggregation and coarsening of Cu ₅ Zr due to residual heat can be reliably prevented. This makes it possible to increase the amount of Zr that dissolves in the matrix (copper) of the stretched material after cooling is completed.

If it is not possible to start water cooling of the stretched material within 60 seconds after stretching, the stretched material may be subjected to a predetermined solution heat treatment (solution heat treatment). Specifically, the process of heating (reheating) the stretched material and the temperature of the stretched material so that the temperature of the stretched material becomes higher than the heating temperature of the ingot (for example, 850 ° C.) in the above-mentioned stretching step. Before the temperature is lowered, the stretched material may be cooled by water cooling and a solution treatment may be performed.

Even in such a solution treatment, when the stretched material is cooled by water cooling, water cooling of the stretched material is started within 60 seconds, preferably within 10 seconds, more preferably immediately after heating the stretched material. As a result, after the stretching process is completed, the Cu ₅ Zr that has aggregated and coarsened due to the residual heat is decomposed, and the amount of Zr that is solid-solved in the matrix phase of the stretched material after the completion of cooling is determined as in the above case. Can be increased.

(Aging heat treatment process)
After the cooling step is completed, the stretched material is subjected to aging heat treatment by heating it at a predetermined temperature for a predetermined time to precipitate Cu ₅ Zr in the matrix phase. The treatment temperature (heating temperature) of the aging heat treatment is, for example, 350 ° C. or higher and 550 ° C. or lower, and the treatment time (heating time) of the aging heat treatment is, for example, 30 minutes or more.

If the above-mentioned heating temperature is less than 350 ° C., the precipitation rate of Cu ₅ Zr becomes slow, so that a predetermined number of Cu ₅ Zr may not be precipitated unless the above-mentioned heating time is lengthened. For this reason, there are problems such as a decrease in productivity and an increase in manufacturing cost, which makes industrial application difficult. By setting the heating temperature to 350 ° C. or higher, this problem can be solved and Cu ₅ Zr having a predetermined size and a predetermined number can be precipitated in the matrix phase.

When the above-mentioned heating temperature exceeds 550 ° C., Cu ₅ Zr precipitated in the matrix aggregates and becomes coarse, so that the size of Cu ₅ Zr can be set to a predetermined size, but a predetermined number of Cu ₅ Zr cannot be deposited in the matrix. By setting the heating temperature to 550 ° C. or lower, this problem can be solved, and a predetermined size and a predetermined number of Cu ₅ Zr can be precipitated in the matrix phase.

Further, if the above-mentioned heating time is less than 30 minutes, Cu ₅ Zr cannot be sufficiently precipitated even when the heating temperature of the aging heat treatment is within the above-mentioned range, and as a result, a predetermined number Cu ₅ Zr cannot be precipitated in the matrix. By setting the heating time to 30 minutes or more, this problem can be solved and a predetermined number of Cu ₅ Zr can be precipitated in the matrix phase.

(Cold processing process)
After the aging heat treatment process is completed, the stretched material is subjected to cold working (plastic working, cold plastic working) such as drawing and rolling. As a result, the stretched material is processed (stretched) to a predetermined size, and a copper alloy material having a predetermined shape is obtained. By performing plastic working on the stretched material in this way, strain is accumulated in the work material (stretched material), the work material is work-hardened, and the strength of the copper alloy material can be increased.

Incidentally, if after the above cooling step, the cold working step may be performed before performing the above aging heat treatment step, which also, predetermined size, a predetermined number of Cu ₅ Zr can be precipitated in the matrix. The order of execution of the aging heat treatment step and the cold working step can be arbitrary.

(4) Effects of the present embodiment According to the present embodiment, one or more of the following effects are exhibited.

(A) The copper alloy material was heated at a high temperature by containing a predetermined amount (0.1 to 0.2% by mass) of Zr as in the present embodiment (the copper alloy material was exposed to a high temperature). ) Even in this case, a decrease in strength and a decrease in conductivity can be suppressed, and a copper alloy material having both high strength and high conductivity can be obtained. This is because, by containing a predetermined amount of Zr, a predetermined size and a predetermined number of Cu ₅ Zr are precipitated in (mother phase) of the copper alloy material, and the parent phase of the copper alloy material heated at a high temperature. This is because it is possible to suppress an increase in the amount of Zr that dissolves in the solid solution.

(B) Specifically, according to the present embodiment, Cu ₅ Zr is precipitated so that 5000 Cu ₅ Zr having a diameter of 0.2 μm or more is present at 5000 pieces / mm ² or more in the cross section of the copper alloy material. I'm letting you. In this way, by precipitating a predetermined size and a predetermined number of Cu ₅ Zr in the copper alloy material, the Cu ₅ Zr functions to suppress the release of strain due to heating. That is, Cu ₅ Zr functions like a pin that suppresses plastic deformation of the copper alloy material due to heating. As a result, even when the copper alloy material is heated at a high temperature, it is possible to suppress a decrease in its strength. For example, even when the copper alloy material is heated at a temperature of 830 ° C. for 10 minutes, the 0.2% proof stress of the heated copper alloy material can be maintained at 80 N / mm ² or more.

(C) Further, as described above, by suppressing an increase in the amount of Zr that dissolves in the matrix phase of the copper alloy material heated at a high temperature, even when the copper alloy material is heated at a high temperature, It is possible to suppress the decrease in the conductivity. For example, even when the copper alloy material is heated at a temperature of 830 ° C. for 10 minutes, the conductivity of the heated copper alloy material can be maintained at 80% IACS or more.

(D) By containing Mg or the like in the copper alloy material within a range of 0.1% by mass or less, a predetermined size and a predetermined number of Cu ₅ Zr can be reliably precipitated in the matrix phase. At the same time, the strength of the copper alloy material (before being heated to a high temperature) can be increased. In addition, the influence of the addition of Mg or the like on the conductivity (conductivity) of the copper alloy material can be minimized.

(E) In the present embodiment, by starting the water cooling of the stretched material within 60 seconds after the stretching (after extruding the stretched material from the extruded die), the stretched material is subjected to the cooling process and before the aging heat treatment. The amount of Zr that dissolves in the matrix is increased. When such a stretched material is subjected to aging heat treatment, a predetermined size and a predetermined number of Cu ₅ Zr can be reliably precipitated in the matrix phase of the copper alloy material. This effect can be surely obtained by starting water cooling of the stretched material within 10 seconds after stretching, preferably immediately after stretching. This is a finding found by the present inventors and the like.

On the other hand, when water cooling of the stretched material is started after 60 seconds have passed after the stretching, Cu ₅ Zr aggregates due to the residual heat and becomes coarse, and Zr solid-solves in the matrix of the stretched material after the cooling is completed. The amount cannot be increased sufficiently. As a result, it may not be possible to deposit a predetermined size and a predetermined number of Cu ₅ Zr in the matrix phase of the copper alloy material.

(F) By performing the aging heat treatment within the above-mentioned condition range, a predetermined size and a predetermined number of Cu ₅ Zr can be put into the matrix phase of the copper alloy material without causing a decrease in productivity and an increase in production cost. It can be reliably deposited.

(G) As described above, the copper alloy material according to the present embodiment can maintain high strength and high conductivity even when heated at a high temperature, so that the rotor bar constituting the cage rotor and the rotor bar It is especially effective when used for end rings. By using the copper alloy material according to this embodiment for the rotor bar or the like, even when brazing or the like is performed on the joint portion between the rotor bar and the end ring when forming the cage rotor. It is possible to suppress a decrease in strength at a portion of the copper alloy material heated for brazing or the like. As a result, even when a centrifugal force acts on the rotor bar or the like due to the rotation of the cage rotor, it is possible to prevent the rotor bar or the like from being deformed or broken.

(Other Embodiments of the present invention)
Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-described embodiment and can be appropriately modified without departing from the gist thereof.

In the above-described embodiment, the case where an extrusion die is used as the stretching machine in the stretching step has been described as an example, but the present invention is not limited to this. For example, in the stretching process, hot forging (forging press) using a forging press machine or the like divides the coarse Cu ₅ Zr existing in the billet to form a stretched material in which the Cu ₅ Zr is made finer. You may. In the stretching step, when a forging press machine is used, as in the case of using an extrusion die, within 60 seconds after the forging press (after stretching), preferably within 10 seconds, and more preferably immediately after the forging press is performed. It is desirable to start water cooling immediately (immediately after stretching). Also by this, the Cu ₅ Zr can be made into a predetermined size and a predetermined number as in the case of using the extrusion die, and the same effect as that of the above-described embodiment can be obtained.

In the above-described embodiment, a molten metal (melted copper, molten copper alloy) is produced using a high-frequency melting furnace, but the present invention is not limited to this. For example, various melting furnaces capable of heating and melting the raw material to produce a molten metal can be used.

In the above-described embodiment, the case where the above-mentioned copper alloy material is used for the rotor bar and the end ring of the squirrel-cage rotor has been described, but the present invention is not limited thereto.

Next, examples of the present invention will be described, but the present invention is not limited thereto.

<Preparation of sample>
(Sample 1)
First, a billet having a predetermined shape was cast by a continuous casting method. Specifically, an electrolytic copper as a raw material was melted using a melting furnace to produce a copper solution. At this time, the surface of the electrolytic copper or the copper solution was covered with carbon to deoxidize the copper solution. A predetermined amount so that the content of Zr in the copper alloy material finally formed in the dissolved copper solution that has been sufficiently deoxidized, that is, the molten metal of oxygen-free copper, is 0.15% by mass. Zr was added to melt the molten copper alloy. The molten copper alloy was poured into a mold having a predetermined shape to cast a billet having a diameter of 200 mm and a length of 600 mm.

The obtained billet was stretched (hot processed). Specifically, after the billet was heated to 950 ° C., the billet before the temperature was lowered was inserted into the extrusion die and passed through the extrusion die. The billet was stretched (extruded) using an extrusion die by pressurizing it with a hydraulic press. As a result, a stretched material having a diameter of 20 mm was obtained.

The extruded material extruded from the extruded die is prepared on the downstream side of the extruded die and placed (carried) in a water tank containing cooling water for water cooling (cooling). After the extruded material was extruded from the extruded die (after stretching and hot working), it took 10 seconds to start water cooling.

After cooling the stretched material until the temperature of the stretched material reaches a predetermined temperature, the stretched material is taken out from the water tank. Subsequently, using an electric furnace, aging heat treatment (heat treatment at 450 ° C. × 1 hour) of heating under the temperature condition of 450 ° C. for 1 hour in an inert gas atmosphere was performed on the stretched material after cooling. After the aging heat treatment was completed, cold plastic working was performed by a drawing method to prepare a copper alloy material having a diameter of 16 mm. This copper alloy material was used as sample 1.

The composition of the copper alloy material of Sample 1 and Samples 2 to 18 described later, the production method and conditions of Sample 1 and Samples 2 to 18 described later are summarized in Table 1 below.

(Samples 2-11)
In Samples 2 to 11, the addition amounts of the sub-components of Mg, Ti, Zn, Fe, Co, Mn, Ag, Si, Cr, and Sn were adjusted so that the composition of the copper alloy material was as shown in Table 1. .. Other than that, a copper alloy material was prepared under the same manufacturing method and conditions as in Sample 1 described above. These were used as samples 2 to 11, respectively.

(Sample 12)
In sample 12, the extruded material extruded from the extruded die was left for 120 seconds without being placed in a water tank. After 120 seconds had passed, the stretched material was placed in a water tank and the stretched material was water-cooled to lower the temperature of the stretched material to a predetermined temperature. Then, after reheating the stretched material in an electric furnace until the temperature of the stretched material reaches 950 ° C., the stretched material is taken out from the electric furnace, and then the stretched material is placed in a water tank containing cooling water within 10 seconds. A solution treatment (solution heat treatment) was performed to cool the stretched material with water. Other than that, a copper alloy material was prepared under the same composition, manufacturing method and conditions as in Sample 1 described above. This was used as sample 12. The time from hot working to water cooling in Table 1 above represents the time from reheating to water cooling in the solution treatment in Sample 12.

(Samples 13 and 14)
In Samples 13 and 14, the amount of Zr added was adjusted so that the composition of the copper alloy material was as shown in Table 1. Other than that, a copper alloy material was prepared under the same manufacturing method and conditions as in Sample 1 described above. These were used as samples 13 and 14, respectively.

(Sample 15)
In sample 15, the stretched material extruded from the extruded die was left for 120 seconds without being put in the water tank, and then the stretched material was put in the water tank and water-cooled. Other than that, a copper alloy material was prepared under the same composition, manufacturing method and conditions as in Sample 1 described above. This was used as sample 15.

(Samples 16 and 17)
In the samples 16 and 17, the temperature conditions during the aging heat treatment were changed as shown in Table 1 below. The conditions other than the composition of the copper alloy material, the manufacturing method, and the temperature conditions at the time of the aging heat treatment were the same as those of Sample 1 described above.

(Sample 18)
In Sample 18, the amount of Mg added was adjusted so that the composition of the copper alloy material was as shown in Table 1. Other than that, a copper alloy material was prepared under the same manufacturing method and conditions as in Sample 1 described above. This was used as sample 18.

<Evaluation>
For each of Samples 1 to 18, the number of Cu ₅ Zr having a diameter of 0.2 μm or more, the strength after high-temperature heating, and the conductivity after high-temperature heating were evaluated.

(Number of Cu ₅ Zr with a diameter of 0.2 μm or more)
The "number of diameter 0.2 [mu] m or more _Cu 5 Zr", and deposited in cross section (cross section) in the direction orthogonal to the extrusion (distraction) direction of each sample, the diameter is more than 0.2 [mu] m _Cu 5 Zr of It is a number. The number of Cu ₅ Zr (precipitation number) was measured by the following procedure. First, after polishing the cross section of each sample, etching was performed with aqueous ammonia containing hydrogen peroxide to dissolve only copper, and Cu ₅ Zr was exposed on the cross section. Then, this cross section is observed with an SEM (scanning electron microscope) at a magnification of 600 times, and the number of Cu ₅ Zr having a diameter of 0.2 μm or more observed in a range of 1.7 mm × 2.2 mm is counted. By calculation, the number of Cu ₅ Zr having a diameter of 0.2 μm or more existing in the range of 1 mm ² was determined.

(Evaluation of strength after high temperature heating)
The strength after heating at high temperature was evaluated by the following procedure. First, each sample was heated under heating conditions simulating brazing conditions. That is, each sample was heated at a temperature of 830 ° C. for 10 minutes. After that (after heat treatment at 830 ° C. × 10 minutes), the 0.2% proof stress of each sample was measured by performing a tensile test in accordance with JIS Z2214. The 0.2% proof stress value was used as the evaluation value of the strength of the copper alloy material after high-temperature heating because the strength at which the copper alloy material starts plastic deformation can be accurately grasped. ..

(Evaluation of conductivity after high temperature heating)
The conductivity after high temperature heating was evaluated by the following procedure. First, each sample was heated at a temperature of 830 ° C. for 10 minutes in the same manner as described above. After that (after heat treatment at 830 ° C. for 10 minutes), the conductivity was measured by a conductivity measuring method based on JIS H0505.

The evaluation results of the number of Cu ₅ Zr with a diameter of samples 1 to 18 of 0.2 μm or more, 0.2% proof stress after heat treatment at 830 ° C. × 10 minutes, and conductivity after heat treatment at 830 ° C. × 10 minutes are as follows. It is summarized in Table 2 of.

<Evaluation result>
From Samples 1 to 12, it was confirmed that by containing a predetermined amount of Zr in the copper alloy material, a predetermined size and a predetermined number of Cu ₅ Zr can be precipitated in the copper alloy material. Specifically, it is possible to deposit Cu ₅ Zr in the copper alloy material so that 5000 pieces / mm ² or more of Cu ₅ Zr having a diameter of 0.2 μm or more are present in the cross section of the copper alloy material. confirmed. Further, by precipitating a predetermined size and a predetermined number of Cu ₅ Zr in the copper alloy material in this way, even the copper alloy material after high temperature heating has both high strength and high conductivity. I confirmed that. That is, it was confirmed that the samples 1 to 12 can maintain a 0.2% proof stress of 80 N / mm ² or more and a conductivity of 80% IACS or more even after the heat treatment at 830 ° C. × 10 minutes.

If the stretched material cannot be water-cooled from the sample 12 within 60 seconds after stretching, a predetermined size and a predetermined number of Cu ₅ Zr can be put into the copper alloy material by performing a predetermined solution treatment. It was confirmed that it could be precipitated.

Further, from the sample 13, if the content of Zr in the copper alloy material is less than a predetermined amount, a predetermined size and a predetermined number of Cu ₅ Zr cannot be deposited in the copper alloy material, that is, the diameter is large. It was confirmed that the number of Cu ₅ Zr of 0.2 μm or more may be less than 5000 pieces / mm ² .

From Sample 14, it was confirmed that when the content of Zr in the copper alloy material exceeds a predetermined amount, the conductivity of the copper alloy material after high-temperature heating exceeds 80% IACS, and the conductivity may decrease.

Further, if the stretched material is not water-cooled from the sample 15 within 60 seconds after stretching, a predetermined size and a predetermined number of Cu ₅ Zr may not be deposited in the copper alloy material unless the solution treatment is performed. I confirmed that there was.

Further, from the sample 16, if the heating temperature of the aging heat treatment is too low, a predetermined size and a predetermined number of Cu ₅ Zr may not be precipitated in the copper alloy material even if the heating time of the aging treatment is 1 hour. confirmed.

From the sample 17, even if the heating temperature of the aging heat treatment is too high, the predetermined size and the predetermined number of Cu ₅ Zr may not be precipitated in the copper alloy material as in the case of the above-mentioned sample 16. confirmed.

From Sample 18, it was confirmed that when the Mg content exceeds a predetermined amount, a predetermined size and a predetermined number of Cu ₅ Zr may not be precipitated in the copper alloy material. It should be noted that even when the content of auxiliary components such as Ti other than Mg exceeds a predetermined amount, similarly, a predetermined size and a predetermined number of Cu ₅ Zr may not be precipitated in the copper alloy material. Has confirmed.

When a predetermined size and a predetermined number of Cu ₅ Zr are not deposited in the copper alloy material from the samples 13, 15 to 18, the strength of the copper alloy material decreases when the copper alloy material is heated at a high temperature. I confirmed that there is. That is, it was confirmed that the 0.2% proof stress of the samples 13, 15 to 18 could not be maintained at 80 N / mm ² or more by performing the heat treatment at 830 ° C. × 10 minutes.

<Preferable aspect>
Hereinafter, preferred embodiments of the present invention will be added.

[Appendix 1]
According to one aspect of the invention
A copper alloy containing Zr of 0.1% by mass or more and 0.2% by mass or less and the balance of which is composed of Cu and unavoidable impurities is stretched.
A precipitate of Cu ₅ Zr, which is a compound of Zr and Cu, is precipitated in the matrix phase.
Provided is a copper alloy material in which 5000 pieces / mm ² or more of the precipitates having a diameter of 0.2 μm or more are present when observing a cross section in a direction orthogonal to the stretching direction.

[Appendix 2]
The copper alloy material of Appendix 1, preferably
It contains 0.1% by mass or less in total of one or more selected from the group consisting of Mg, Ti, Zn, Fe, Co, Mn, Ag, Si, Cr and Sn.

[Appendix 3]
The copper alloy material of Appendix 1 or 2, preferably
The 0.2% proof stress after heating at a temperature of 830 ° C. for 10 minutes is 80 N / mm ² or more.
The conductivity after heating at a temperature of 830 ° C. for 10 minutes is 80% IACS or more.

[Appendix 4]
According to another aspect of the invention
A step of casting an ingot containing Zr of 0.1% by mass or more and 0.2% by mass or less and the balance of which is Cu and unavoidable impurities.
A step of hot-stretching the heated ingot to form a stretched material, and
Water cooling is started within 60 seconds after the stretched material is formed to cool the stretched material, or the temperature of the stretched material is equal to or higher than the heating temperature of the ingot in the step of forming the stretched material. A step of starting water cooling within 60 seconds after heating the stretched material so as to cool the stretched material, and
Provided is a method for producing a copper alloy material, which comprises a step of performing an aging heat treatment in which the cooled stretched material is heated at a temperature of 350 ° C. or higher and 550 ° C. or lower for 30 minutes or longer.

[Appendix 5]
The method of Appendix 4, preferably
In the step of forming the stretched material, hot stretching is performed so that the surface reduction rate is 60% or more.

[Appendix 6]
The method of Appendix 4 or 5, preferably
In the step of forming the stretched material, hot stretching is performed so that the surface reduction rate is 80% or more.

[Appendix 7]
Any of the methods of Appendix 4 to 6, preferably.
In the step of cooling the stretched material, the stretched material is set to a temperature within 10 seconds after the stretched material is formed, or the temperature of the stretched material is equal to or higher than the heating temperature of the ingot (for example, 850 ° C. or higher). Within 10 seconds after heating, water cooling of the stretched material is started. More preferably, the stretched material is formed immediately after the stretched material is formed, or immediately after the stretched material is heated so that the temperature of the stretched material becomes equal to or higher than the heating temperature of the ingot (for example, 850 ° C. or higher). Start water cooling of the material.

[Appendix 8]
Any of the methods of Appendix 4 to 7, preferably.
It further has a step of performing cold (plastic) working on the stretched material before the step of performing the aging heat treatment or after performing the step of performing the aging heat treatment.

[Appendix 9]
According to yet another aspect of the invention.
A copper alloy containing 0.1% by mass or more and 0.2% by mass or less of Zr and the balance of which is composed of Cu and unavoidable impurities is stretched and formed, and Cu ₅ Zr, which is a compound of Zr and Cu, is formed in the matrix phase. Precipitates are precipitated, and when observing the cross section in the direction orthogonal to the elongation direction, the end ring and the copper alloy material in which 5000 pieces / mm ² or more of the precipitates having a diameter of 0.2 μm or more are present are present. A cage-type rotor used for a rotor bar is provided.

Claims (5)

It contains Zr of 0.1% by mass or more and 0.2% by mass or less, and the balance is stretched with a copper alloy composed of Cu and unavoidable impurities.
A precipitate of Cu ₅ Zr, which is a compound of Zr and Cu, is precipitated in the matrix phase.
A copper alloy material in which 5000 pieces / mm ² or more of the precipitates having a diameter of 0.2 μm or more are present when observing a cross section in a direction orthogonal to the stretching direction. The copper alloy material according to claim 1, wherein one or more selected from the group consisting of Mg, Ti, Zn, Fe, Co, Mn, Ag, Si, Cr and Sn is contained in an amount of 0.1% by mass or less in total. The 0.2% proof stress after heating at a temperature of 830 ° C. for 10 minutes is 80 N / mm ² or more.
The copper alloy material according to claim 1 or 2, wherein the conductivity after heating at a temperature of 830 ° C. for 10 minutes is 80% IACS or more. A step of casting an ingot containing Zr of 0.1% by mass or more and 0.2% by mass or less and the balance of which is Cu and unavoidable impurities.
A step of hot-stretching the heated ingot to form a stretched material, and
Water cooling is started within 60 seconds after the formation of the stretched material is completed to cool the stretched material, or the temperature of the stretched material is equal to or higher than the heating temperature of the ingot in the step of forming the stretched material. A step of cooling the stretched material by starting water cooling within 60 seconds after heating the stretched material to a temperature.
There rows aging for heating the cooled the distraction member 3 50 ° C. or higher 550 ° C. 30 minutes or more under a temperature below precipitate _Cu 5 Zr which is a compound of Zr and Cu is diameter 0.2μm or more In the matrix phase so that 5000 pieces / mm ² or more are present in the cross section in the direction orthogonal to the stretching direction .
A method for manufacturing a copper alloy material having. A copper alloy containing 0.1% by mass or more and 0.2% by mass or less of Zr and the balance of which is composed of Cu and unavoidable impurities is stretched and formed, and Cu ₅ Zr, which is a compound of Zr and Cu, is formed in the matrix phase. Precipitates are precipitated, and when observing the cross section in the direction orthogonal to the elongation direction, the end ring and the copper alloy material in which 5000 pieces / mm ² or more of the precipitates having a diameter of 0.2 μm or more are present are present. A cage-type rotor used for rotor bars.