Inner grooved pipe and its manufacturing method

Abstract

To provide an internally grooved tube made of a copper alloy heat-treated at 650°C ± 100°C after cold working, and made of a Cu-Ni-P-based copper alloy with high strength and excellent workability.SOLUTION: An internally grooved tube made of a copper alloy containing 0.40 to 1.50 mass% of Ni and 0.10 to 0.50 mass% of P, the balance being Cu and inevitable impurities, the inner grooved tube includes a solution treatment for solution treating the copper alloy, after the solution treatment, an intermediate annealing treatment for heating at 550±150°C, and a rolling process following the intermediate annealing treatment, and after the rolling processing, the first heat treatment (A1) heating at 650±100°C, and the second heat treatment (A2) heating at 850±100°C, and in cooling after performing the second heat treatment (A2), an average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C is 1°C / sec or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an internally grooved tube having high strength and excellent workability, and a method for manufacturing the same.

Background Art

[0002] Conventionally, copper alloys containing trace elements have been proposed for the purpose of increasing the strength of copper materials. One of them is a Cu-Ni-P based copper alloy. (For example, Patent Document 1: Japanese Patent Laid-Open No. 4-218631).

[0003] As a high-strength copper alloy tube, in claim 4 of Patent Document 2, a copper alloy material (A) containing 0.40 to 3.5% by mass of Ni and 0.1 to 0.5% by mass of P, with the balance being Cu and unavoidable impurities, is subjected to a first heat treatment at 650°C ± 100°C to obtain a copper alloy material (B) having a tensile strength (σ2) of 270 to 370 MPa. A copper alloy material (C) having a tensile strength (σ2) of 300 MPa or more and an elongation (δ) of 30% or more, which is obtained by performing a second heat treatment on the copper alloy material (B) by heating at 850°C ± 100°C, is disclosed.

[0004] In its examples (Examples 11 to 12), a copper tube having a chemical composition consisting of 0.41 to 3.30% by mass of Ni, 0.12 to 0.40% by mass of P, and the balance being Cu and unavoidable impurities, which is cast - heated to 900°C - hot extruded - heated to 900°C and then water-cooled (corresponding to solution treatment) - cold drawn - first heat treated at 650°C - second heat treated at 850°C, is disclosed.

[0005] Also, it is described that the cooling rate after the first heat treatment at 650°C is not particularly limited, but is preferably 2 to 10°C / min, and the cooling rate after the second heat treatment at 850°C is not particularly limited, but is preferably 2 to 20°C / sec.

[0006] Furthermore, claim 1 of Patent Document 3 discloses a method for producing a copper alloy tube, which comprises casting a copper alloy ingot containing 0.4 to 1.5 mass% Ni, 0.1 to 0.5 mass% P, with the balance being Cu and unavoidable impurities, and hot working and cold working the ingot, the method comprising a first heat treatment of heating the ingot at 550 to 750°C after solution treatment, and a second heat treatment of heating the ingot at 750 to 950°C and cooling from the heating temperature to 300°C at an average cooling rate of 5°C / second or less. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 4-218631 [Patent Document 2] International Publication No. 2015 / 122423 [Patent Document 3] Japanese Patent Application Publication No. 2017-82301 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0008] Internally grooved pipes, which have a plurality of ridges and grooves on the inner surface, are often used as heat transfer pipes for air conditioner heat exchangers such as room air conditioners and packaged air conditioners, or for refrigerators, etc. Air conditioner heat exchangers or refrigerators, etc. are manufactured by assembling a pipe material with other components and then brazing the pipe material to the other components through brazing heat, and this brazing heat can be the second heat treatment in Patent Documents 2 and 3 (850°C±100°C heat treatment in Patent Document 2).

[0009] However, in this case, the strength of the copper alloy pipe after the second heat treatment and cooling is not sufficiently high, and therefore, there is a demand for further improvement in the strength of Cu-Ni-P based copper alloy pipes.

[0010] In addition, in the production of copper alloy pipes, in consideration of workability in subsequent processes, heat treatment is required after cold working to remove distortion from copper pipes that have been work-hardened by cold working, by heating them at a temperature of approximately 650°C ± 100°C.

[0011] Therefore, an object of the present invention is to provide an internally grooved pipe made of a copper alloy that has been subjected to heat treatment at 650°C±100°C after cold working, and that is made of a Cu-Ni-P based copper alloy that has high strength and excellent workability. [Means for solving the problem]

[0012]

[0009] Based on the above technical background, the present inventors have conducted extensive research and have found that it is possible to increase the strength of an internally grooved pipe by setting the Ni and P contents of a copper alloy within a specific range, cold working the copper alloy, subjecting it to heat treatment at a temperature of about 650°C±100°C, and then slowly cooling it from a high-temperature heat treatment at 850°C±100°C, and further increasing the strength of a copper alloy pipe by optimizing the cooling rate after the 850°C±100°C heat treatment or by performing aging treatment at a predetermined temperature, thereby completing the present invention.

[0016] That is, , the present invention ( 1 ) includes a casting step of casting a copper alloy ingot containing 0.40 to 1.50 mass% of Ni, 0.10 to 0.50 mass% of P, and the remainder being Cu and unavoidable impurities; a hot working step of hot working the copper alloy ingot; a cold working step of performing cold working after the hot working step; and a solution treatment for solutionizing the copper alloy tube after the hot working step, before the cold working step, or after the cold working step; After the solution treatment, an intermediate annealing treatment is performed by heating at 550±150°C, and the intermediate annealing treatment is performed Cold working A rolling process; After the rolling process, a first heat treatment (A1) is performed in which the copper alloy pipe is heated at 650±100°C; After the first heat treatment (A1), a second heat treatment (A2) is performed in which the copper alloy tube is heated at 850±100°C. In the cooling process after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C is 1°C / second or less. The present invention provides a method for manufacturing an internally grooved pipe, characterized by the above-mentioned.

[0017] In addition, the present invention ( 2 ) is characterized in that after the second heat treatment (A2), an aging treatment (A3) is further performed by heating at 225±100°C ( 1 ) A method for manufacturing an internally grooved pipe is provided.

[0018] In addition, the present invention ( 3 ) includes a casting step of casting a copper alloy ingot containing 0.40 to 1.50 mass% of Ni, 0.10 to 0.50 mass% of P, and the remainder being Cu and unavoidable impurities; a hot working step of hot working the copper alloy ingot; a cold working step of performing cold working after the hot working step; and a solution treatment for solutionizing the copper alloy tube after the hot working step, before the cold working step, or after the cold working step; After the solution treatment, an intermediate annealing treatment is performed by heating at 550±150°C, and the intermediate annealing treatment is performed Cold working A rolling process; After the rolling process, a first heat treatment (A1) is performed in which the copper alloy pipe is heated at 650±100°C; After the first heat treatment (A1), a second heat treatment (A2) is performed in which the copper alloy tube is heated at 850±100°C; After the second heat treatment (A2), an aging treatment (A3) is performed by heating the copper alloy tube at 225°C ± 100°C. To carry out the following: The present invention provides a method for manufacturing an internally grooved pipe, characterized by the above-mentioned. [Effects of the Invention]

[0019] According to the present invention, there is provided a copper alloy tube that has been heat-treated at 650°C ± 100°C after cold working, and is a Cu-Ni-P-based copper alloy tube having high strength and excellent workability.

Embodiments for Carrying Out the Invention

[0020] The internally grooved tube of the first embodiment of the present invention is an internally grooved tube made of a copper alloy containing 0.40 to 1.50% by mass of Ni and 0.10 to 0.50% by mass of P, with the balance being Cu and unavoidable impurities, wherein the internally grooved tube is subjected to a solution treatment for solutionizing the copper alloy, an intermediate annealing treatment for heating at 550 ± 150°C after the solution treatment and a forging process following the intermediate annealing treatment, a first heat treatment (A1) for heating at 650 ± 100°C after the forging process, and a second heat treatment (A2) for heating at 850 ± 100°C after the first heat treatment (A1), and in the cooling after performing the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C is 1°C / second or less, characterizing the internally grooved tube. Further, the internally grooved tube of the first embodiment of the present invention may be one that is further subjected to an aging treatment (A3) for heating at 225 ± 100°C after the second heat treatment (A2).

[0021] The internally grooved tube of the second embodiment of the present invention is an internally grooved tube made of a copper alloy containing 0.40 to 1.50% by mass of Ni and 0.10 to 0.50% by mass of P, with the balance being Cu and unavoidable impurities, wherein the internally grooved tube is subjected to a solution treatment for solutionizing the copper alloy, an intermediate annealing treatment for heating at 550 ± 150°C after the solution treatment and a forging process following the intermediate annealing treatment, a first heat treatment (A1) for heating at 650 ± 100°C after the forging process, a second heat treatment (A2) for heating at 850 ± 100°C after the first heat treatment (A1), and an aging treatment (A3) for heating at 225 ± 100°C after the second heat treatment (A2), It is a pipe with an inner groove, characterized by the above. In the pipe with an inner groove according to the second aspect of the present invention, in the cooling after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225 °C exceeds 1 °C / second.

[0022] That is, the pipe with an inner groove according to the first aspect of the present invention and the pipe with an inner groove according to the second aspect of the present invention are different in that the former has (i) an average cooling rate from the heating temperature of the second heat treatment (A2) to 225 °C of 1 °C / second or less in the cooling after the second heat treatment (A2), while the latter has (ii) an aging treatment (A3) of heating at 225 ± 100 °C after the second heat treatment (A2), but the others are the same. Hereinafter, the common points of the pipe with an inner groove according to the first aspect of the present invention and the pipe with an inner groove according to the second aspect of the invention will be described by collectively referring to the pipe with an inner groove according to the first aspect of the present invention and the pipe with an inner groove according to the second aspect of the present invention as the pipe with an inner groove of the present invention.

[0023] The pipe with an inner groove of the present invention is first manufactured by casting a copper alloy ingot having a predetermined chemical composition and then performing various processing and treatments. However, the inventors, during various processing and treatments of the copper alloy, performed a solution treatment on a copper alloy having a specific chemical composition, that is, a copper alloy containing 0.40 to 1.50% by mass of Ni, preferably 0.70 to 1.20% by mass of Ni, and 0.10 to 0.50% by mass of P, preferably 0.20 to 0.40% by mass of P. After the solution treatment, an intermediate annealing treatment of heating at 550 ± 150 °C and a hot rolling process following the intermediate annealing treatment are performed, and then as heat treatments, (i) a first heat treatment (A1) of heating at 650 ± 100 °C and a second heat treatment (A2) of heating at 850 ± 100 °C after the first heat treatment (A1) are performed, and in the cooling after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225 °C is set to 1 °C / second or less, or (ii) a first heat treatment (A1) of heating at 650 ± 100 °C, a second heat treatment (A2) of heating at 850 ± 100 °C after the first heat treatment (A1), and an aging treatment (A3) of heating at 225 °C ± 100 °C after the second heat treatment (A2) are performed, whereby Ni is present in the copper alloy forming the pipe with an inner groove. 12It has been found that precipitates having a composition of P5 and / or Ni5P4 can be precipitated, and the strength of the copper alloy material can be improved by precipitation strengthening.

[0024] The inner-grooved tube of the present invention is formed of a copper alloy containing 0.40 to 1.50% by mass of Ni and 0.10 to 0.50% by mass of P, with the balance being Cu and unavoidable impurities. In the present invention, the contents of the above Ni and P refer to the contents of Ni and P in the copper alloy forming the inner-grooved tube after cooling after the second heat treatment (A2) in the inner-grooved tube of the first embodiment of the present invention, and also refer to the contents of Ni and P in the copper alloy forming the inner-grooved tube after the aging treatment (A3) in the inner-grooved tube of the second embodiment of the present invention.

[0025] The Ni content of the copper alloy forming the inner-grooved tube of the present invention is 0.40 to 1.50% by mass. When the copper alloy is heated at 225°C ± 100°C, Ni 12 forms precipitates having a composition of P5 and / or Ni5P4 and is a component that improves the tensile strength. When the Ni content is within the above range, the tensile strength of the inner-grooved tube increases. On the other hand, when the Ni content exceeds the above range, the elongation decreases, and the hairpin bending processability and expandability decrease. Also, when the Ni content is less than the above range, the strength of the inner-grooved tube decreases. In particular, in terms of high strength and excellent processability, the Ni content of the copper alloy forming the inner-grooved tube of the present invention is preferably 0.70 to 1.20% by mass.

[0026] The P content of the copper alloy forming the inner-grooved tube of the present invention is 0.10 to 0.50% by mass. When the copper alloy is heated at 225°C ± 100°C, P 12It is a component that forms precipitates having a composition of P5 and / or Ni5P4 to improve strength. When the P content is within the above range, the strength of the internally grooved tube becomes high. On the other hand, when the P content exceeds the above range, the workability decreases, and there is a risk of cracking in hot working and cold working. Also, when the P content is less than the above range, the amount of precipitates precipitated decreases, resulting in a decrease in the strength of the copper alloy material. In particular, in terms of high strength and excellent workability, the P content of the copper alloy forming the internally grooved tube of the present invention is preferably 0.20 to 0.40% by mass.

[0027] The internally grooved tube of the present invention contains 0.40 to 1.50% by mass of Ni, preferably 0.70 to 1.20% by mass of Ni, and 0.10 to 0.50% by mass of P, preferably 0.20 to 0.40% by mass of P, and after casting a copper alloy composed of the balance Cu and inevitable impurities, in the process of performing various processes (for example, hot working such as hot extrusion, cold rolling, cold working such as cold drawing), and various heat treatments, the copper alloy is heated and solutionized by rapid cooling. After the solutionizing treatment, an intermediate annealing treatment of heating at 550 ± 150 °C and a forging process following the intermediate annealing treatment are performed. As the heat treatment performed after the forging process, (i) a first heat treatment (A1) of heating at 650 ± 100 °C and a second heat treatment (A2) of heating at 850 ± 100 °C after the first heat treatment (A1) are performed, and in the cooling after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225 °C is set to 1 °C / second or less, or (ii) a first heat treatment (A1) of heating at 650 ± 100 °C, a second heat treatment (A2) of heating at 850 ± 100 °C after the first heat treatment (A1), and an aging treatment (A3) of heating at 225 ± 100 °C after the second heat treatment (A2) are performed.

[0028] The solution treatment is carried out by heating the copper alloy to 800 - 1000 °C, preferably 800 - 950 °C, and then rapidly cooling it. The location of the solution treatment during the manufacturing process can be appropriately selected between before hot working and after cold working. The rapid cooling is carried out, for example, by water-cooling the heated copper alloy. Also, when cold working is carried out multiple times, after hot working and before all cold working, between cold working and cold working, or after all cold working, the copper alloy is heated to 800 - 1000 °C, preferably 800 - 950 °C, and then a solution treatment with rapid cooling is carried out. Further, after hot working, a solution treatment can also be carried out by rapidly cooling the hot-worked copper alloy. Note that rapid cooling refers to cooling with an average cooling rate of 100 °C / second or more from the heating temperature to 225 °C.

[0029] The intermediate annealing treatment is carried out by heating the copper alloy at 550 ± 150 °C, preferably 550 ± 100 °C, after the solution treatment. The intermediate annealing treatment is carried out before the rotary forging process to remove the processing strain before intermediate annealing and to obtain a quality suitable for rotary forging. By having the heating temperature of the intermediate annealing treatment within the above range, a raw tube suitable for rotary forging can be obtained. On the other hand, if the heating temperature of the intermediate annealing treatment is less than the above range, the softening of the material is insufficient, resulting in a large deformation resistance and difficulty in rotary forging. Also, if it exceeds the above range, the crystal grain size becomes large, hindering the inflow of the material into the groove plug and making groove formation difficult.

[0030] The rotary forging process is carried out following the intermediate annealing treatment. The rotary forging is a process of forming an inner surface groove on the inner surface of the copper alloy tube. After the intermediate annealing treatment, a rotary plug with a helical groove on the outer surface is placed inside the copper alloy tube, and it is pressed from the outside of the tube by a plurality of rotary balls rotating at high speed to transfer the groove of the rotary plug to the inner surface of the tube. Usually, after the intermediate annealing treatment, a diameter reduction process is carried out and then the rotary forging is carried out.

[0031] A first heat treatment (A1) is carried out after the forging process. In the first heat treatment (A1), the copper alloy is heated at 650 ± 100 °C. When the heating temperature of the first heat treatment (A1) is within the above range, in case (i), after cooling after the second heat treatment (A2), and in case (ii), after the aging treatment (A3), compounds of Ni and P in the copper alloy form precipitates having a composition of Ni 12 P5 and / or Ni5P4, resulting in a fine and uniform precipitation state and high strength. On the other hand, if the heating temperature of the first heat treatment (A1) is less than the above range, the processed structure after cold working remains, recrystallization is insufficient, the yield strength value is high and the elongation is low, and the workability when performing subsequent highly processed or complex processing becomes low. Also, if it exceeds the above range, the precipitates coarsen after the first heat treatment (A1), and in case (i), after cooling after the second heat treatment (A2), and in case (ii), do not contribute to the high strength after the aging treatment (A3).

[0032] The heat treatment time in the first heat treatment (A1) is preferably 10 to 600 minutes, particularly preferably 30 to 120 minutes. When the heat treatment time in the first heat treatment (A1) is within the above range, in case (i), after cooling after the second heat treatment (A2), and in case (ii), after the aging treatment (A3), a sufficient amount of Ni 12 precipitates having a composition of P5 and / or Ni5P4 can be precipitated. On the other hand, if the heat treatment time in the first heat treatment (A1) is less than the above range, in case (i), after cooling after the second heat treatment (A2), and in case (ii), after the aging treatment (A3), the precipitation amount of precipitates having a composition of Ni 12 P5 and / or Ni5P4 tends to decrease, and it becomes difficult to obtain the effect of improving the strength of the copper alloy tube. Also, if it exceeds the above range, the precipitates after the first heat treatment (A1) become large, and the strength of the copper alloy tube tends to decrease.

[0033] In the cooling after the first heat treatment (A1), the average cooling rate from the heating temperature of the first heat treatment (A1) to 300°C can be selected arbitrarily, but is preferably 1°C / second or less. When the average cooling rate from the heating temperature of the first heat treatment (A1) to 300°C in the cooling after the first heat treatment (A1) is within the above range, the formation of precipitates having a composition of NiP is promoted, strength is increased, and deformation and scratches that occur during processing steps between the first heat treatment (A1) and the second heat treatment (A2), for example, during processing steps for assembling the copper alloy pipe into a heat exchanger, and during handling, are prevented.

[0034] Regarding the second heat treatment (A2), after the first heat treatment (A1), the copper alloy is heated to 850±100°C. By setting the heating temperature of the second heat treatment (A2) within the above range, Cu-Ni-P-based precipitates containing at least a portion of precipitates having a NiP composition are obtained, resulting in increased strength. On the other hand, if the heating temperature of the second heat treatment (A2) is below the above range, precipitates having a NiP composition are unlikely to precipitate during the cooling process after the second heat treatment (A2). Also, if the heating temperature of the second heat treatment (A2) is above the above range, sufficient time for precipitation during the cooling process cannot be ensured. On the other hand, if the heating temperature of the second heat treatment (A2) is below the above range, a crystalline structure with excessively coarse crystal grains is obtained.

[0035] The heating time in the second heat treatment (A2) is preferably 10 to 1800 seconds.

[0036] In the internally grooved pipe of the first embodiment of the present invention, in the cooling after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C is 1°C / second or less. By having the average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C being 1°C / second or less, the strength of the internally grooved pipe is increased.

[0037] In the second embodiment of the present invention, the inner grooved pipe is subjected to an aging treatment (A3) at 225±100° C. after the second heat treatment (A2). By setting the heating temperature of the aging treatment (A3) within the above range, Ni12 A Cu-Ni-P-based precipitate containing at least a part of a precipitate having a composition of P5 and / or Ni5P4 is obtained, and the strength is increased. On the other hand, if the heating temperature of the aging treatment (A3) is less than the above range, Ni 12 it is difficult for a precipitate having a composition of P5 and / or Ni5P4 to precipitate, and even if it exceeds the above range, Ni 12 it is difficult for a precipitate having a composition of P5 and / or Ni5P4 to precipitate.

[0038] When the internally grooved tube of the present invention is a heat exchanger for an air conditioner such as a room air conditioner or a package air conditioner or a heat transfer tube such as a refrigerator, the heat exchanger for an air conditioner or a refrigerator, etc. is brazed and heated after assembling the pipe material with other members, whereby the pipe material and other members are brazed and manufactured. This brazing heating can be the second heat treatment (A2) according to the internally grooved tube of the present invention. That is, using an ingot of a copper alloy containing 0.40 to 1.50% by mass of Ni, preferably 0.70 to 1.20% by mass of Ni, 0.10 to 0.50% by mass of P, preferably 0.20 to 0.40% by mass of P, and the balance being Cu and inevitable impurities, hot working and cold working are performed to process it into the shape of a pipe material, and a pipe material that has been subjected to a solution treatment, an intermediate annealing treatment, a forging process, and a first heat treatment (A1) is assembled with other members constituting a heat exchanger for an air conditioner or a refrigerator, and then heated at 850 °C ± 100 °C and cooled to braze the pipe material and other members, whereby the second heat treatment (A2) can also be performed. As the cooling method in the cooling after the second heat treatment (A2), for example, when the average cooling rate from the heating temperature to 225 °C is 25 to 50 °C / second, a cooling method such as forced air cooling can be mentioned, and when the average cooling rate from the heating temperature to 225 °C is 20 °C / second or less, a cooling method such as natural air cooling can be mentioned, and further when the average cooling rate from the heating temperature to 225 °C is 1 °C / second or less, a cooling method such as furnace cooling can be mentioned. In the case of in-furnace brazing, the heating time in the second heat treatment (A2) is often 600 seconds or more.

[0039] Regarding the aging treatment (A3), after the second heat treatment (A2), the copper alloy is heated at 225±100°C as the aging heat treatment (A3). By setting the heating temperature of the aging treatment (A3) within the above range, Ni 12 On the other hand, if the heating temperature of the aging treatment (A3) is below the above range, the Ni 12 Precipitates having a composition of NiP5 and / or Ni5P4 are unlikely to precipitate. 12 Precipitates having a composition of P5 and / or Ni5P4 are unlikely to precipitate.

[0040] The heating time in the aging treatment (A3) is preferably 10 to 2000 minutes, particularly preferably 30 to 1000 minutes. By keeping the heating time in the aging treatment (A3) within the above range, a sufficient amount of Ni can be obtained to obtain the effect of improving the strength of the copper alloy pipe. 12 On the other hand, if the heating time in the aging treatment (A3) is less than the above range, precipitates having a composition of NiP5 and / or Ni5P4 can be precipitated. 12 The amount of precipitates having a composition of P5 and / or Ni5P4 tends to decrease, making it difficult to obtain the effect of improving the strength of the copper alloy tube. Furthermore, if the content exceeds the above range, the precipitates become large, making it easy for the strength of the copper alloy tube to decrease.

[0041] The internally grooved pipe of the first embodiment of the present invention may be further subjected to aging treatment (A3) by heating at 225±100° C. after the second heat treatment (A2). The aging treatment (A3) for the internally grooved pipe of the first embodiment of the present invention is the same as the aging treatment (A3) for the internally grooved pipe of the second embodiment of the present invention.

[0042] In the present invention, "the first heat treatment (A1) was performed after the rolling process" does not only mean that the first heat treatment (A1) is performed immediately after the rolling process on the copper alloy pipe, but also means that a "treatment or step not involving heating" and / or a "treatment or step involving heating at a temperature exceeding 325°C" may be performed between the rolling process and the first heat treatment (A1). That is, the copper alloy pipe may be subjected to the first heat treatment (A1) immediately after the rolling process, or may be subjected to a "treatment or step not involving heating" and / or a "treatment or step involving heating at a temperature exceeding 325°C" after the rolling process, and then the first heat treatment (A1). Furthermore, after the solution treatment and before the first heat treatment (A1), the copper alloy may be exposed to a temperature in the range of 125 to 325°C for a short period of time that does not affect the effects of the present invention. For example, if a treatment or step involving heating at a temperature exceeding 325°C is carried out after the rolling process and before the first heat treatment (A1) is carried out, the temperature will pass through a temperature range of 125 to 325°C in order to raise the temperature to the predetermined temperature, but this is acceptable as long as the time spent passing through the temperature range of 125 to 325°C is short enough that it does not affect the effects of the present invention.

[0043] In the present invention, "the second heat treatment (A2) was performed after the first heat treatment (A1)" does not necessarily mean that the copper alloy is subjected to the second heat treatment (A2) immediately after the first heat treatment (A1). It also means that a "treatment or step not involving heating" and / or a "treatment or step involving heating at a temperature exceeding 325°C" may be performed between the first heat treatment (A1) and the second heat treatment (A2). That is, the copper alloy may be subjected to the second heat treatment (A2) immediately after the first heat treatment (A1). Alternatively, the copper alloy may be subjected to the first heat treatment (A1) followed by a "treatment or step not involving heating" and / or a "treatment or step involving heating at a temperature exceeding 325°C" and then the second heat treatment (A2). Furthermore, between the first heat treatment (A1) and the second heat treatment (A2), the copper alloy may be exposed to a temperature in the range of 125 to 325°C for a short period of time that does not affect the effects of the present invention. For example, if a treatment or step involving heating at a temperature exceeding 325°C is carried out between the first heat treatment (A1) and the second heat treatment (A2), the temperature will pass through a temperature range of 125 to 325°C in order to raise the temperature to the predetermined temperature. However, this is acceptable as long as the time required for passing through the temperature range of 125 to 325°C is short enough that it does not affect the effects of the present invention.

[0044] In the present invention, "ageing treatment (A3) is carried out after the second heat treatment (A2)" does not only mean that the ageing treatment (A3) is carried out immediately after the second heat treatment (A2) is carried out on the copper alloy, but also that a "treatment or process not involving heating" and / or a "treatment or process heated at a temperature exceeding 325°C" may be carried out between the second heat treatment (A2) and the ageing treatment (A3). That is, the ageing treatment (A3) may be carried out immediately after the second heat treatment (A2) is carried out on the copper alloy, or alternatively, after the second heat treatment (A2) is carried out, the "treatment or process not involving heating" and / or the "treatment or process heated at a temperature exceeding 325°C" may be carried out, and then the ageing treatment (A3) may be carried out. Further, after the second heat treatment (A2) is carried out and before the ageing treatment (A3) is carried out, if the time is short enough not to affect the effects of the present invention, the copper alloy may be exposed to a temperature in the range of 125 to 325°C. For example, in the case where a treatment or process heated at a temperature exceeding 325°C is carried out between the second heat treatment (A2) and the ageing treatment (A3), the temperature range of 125 to 325°C will be passed through for the temperature increase to a predetermined temperature, but if the time for passing through the temperature range of 125 to 325°C is short enough not to affect the effects of the present invention, it is acceptable.

[0045] The manufacturing method of the inner surface grooved tube according to the first aspect of the present invention includes a casting step of casting a copper alloy ingot containing 0.40 to 1.50% by mass of Ni and 0.10 to 0.50% by mass of P, with the balance being Cu and unavoidable impurities, a hot working step of hot working the copper alloy ingot, a cold working step of performing cold working after the hot working step, and has a solution treatment for solutionizing the copper alloy tube after the hot working step, before or after the cold working step, an intermediate annealing treatment of heating at 550 ± 150°C after the solution treatment and a rolling process following the intermediate annealing treatment, a first heat treatment (A1) of heating the copper alloy tube at 650 ± 100°C after the rolling process, After the first heat treatment (A1), a second heat treatment (A2) is performed in which the copper alloy tube is heated at 850±100°C. In the cooling process after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C is 1°C / second or less. This is a method for manufacturing an internally grooved pipe, characterized by the above. In addition, in the method for producing an internally grooved pipe of the first embodiment of the present invention, after the second heat treatment (A2), an aging treatment (A3) of heating at 225±100° C. can be further carried out.

[0046] A method for producing an internally grooved tube according to a second embodiment of the present invention includes a casting step of casting a copper alloy ingot containing 0.40 to 1.50 mass% of Ni, 0.10 to 0.50 mass% of P, the balance being Cu and unavoidable impurities; a hot working step of hot working the copper alloy ingot; a cold working step of performing cold working after the hot working step; and a solution treatment for solutionizing the copper alloy tube after the hot working step, before the cold working step, or after the cold working step; After the solution treatment, an intermediate annealing treatment is performed by heating at 550±150°C, and a rolling process is performed following the intermediate annealing treatment. After the rolling process, a first heat treatment (A1) is performed in which the copper alloy pipe is heated at 650±100°C; After the first heat treatment (A1), a second heat treatment (A2) is performed in which the copper alloy tube is heated at 850±100°C; After the second heat treatment (A2), an aging treatment (A3) is performed by heating the copper alloy tube at 225°C ± 100°C. To carry out the following: In the method for producing an internally grooved pipe of the second embodiment of the present invention, in the cooling after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C exceeds 1°C / sec.

[0047] That is, the manufacturing method of the inner-grooved pipe of the first aspect of the present invention and the manufacturing method of the inner-grooved pipe of the second aspect of the present invention are the same in other respects, except that in the former, in the cooling after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C is 1°C / second or less, while in the latter, after the second heat treatment (A2), an aging treatment (A3) of heating at 225 ± 100°C is performed. Hereinafter, the common points between the manufacturing method of the inner-grooved pipe of the first aspect of the present invention and the manufacturing method of the inner-grooved pipe of the second aspect of the invention will be collectively referred to as the manufacturing method of the inner-grooved pipe of the present invention and described.

[0048] The manufacturing method of the copper alloy pipe of the present invention includes a casting process, a hot working process, and a cold working process.

[0049] In the casting process, according to a conventional method, melting and casting are performed to obtain a copper alloy ingot (billet) containing 0.40 to 1.50% by mass of Ni and 0.10 to 0.50% by mass of P, with the balance being Cu and unavoidable impurities. In the casting process, for example, copper ingots, in-process recycled materials, Cu-Ni master alloys, Cu-P master alloys, etc. are blended, and the composition is adjusted so that the Ni and P contents become predetermined contents. Then, using a high-frequency melting furnace or the like, the billet is cast.

[0050] In the hot working process, the copper alloy ingot (billet) obtained by performing the casting process is hot extruded to hot work the copper alloy ingot. In hot extrusion, the billet is heated to a predetermined temperature before hot extrusion, and then hot extrusion processing is performed. Hot extrusion is performed by mandrel extrusion. That is, hot extrusion is performed with a mandrel inserted into a billet pre-perforated cold or a billet pre-perforated hot before extrusion to obtain a seamless copper alloy pipe.

[0051] In addition, in hot extrusion, the copper alloy pipe can be extruded into water for rapid cooling to perform a solution treatment.

[0052] In the cold working step, the cooled copper alloy tube after the hot working step is cold rolled or cold drawn to reduce the outer diameter and wall thickness of the tube. In the cold working step, cold working can be performed multiple times.

[0053] In the method for producing an internally grooved pipe of the present invention, a copper alloy containing 0.40 to 1.50 mass% of Ni, preferably 0.70 to 1.20 mass% of Ni, 0.10 to 0.50 mass% of P, preferably 0.20 to 0.40 mass% of P, with the balance being Cu and unavoidable impurities, is cast, and then subjected to various processes (for example, hot working such as hot extrusion, cold working such as cold rolling and cold drawing) and various heat treatments, during which the copper alloy is heated and quenched to perform a solution treatment, and after the solution treatment, an intermediate annealing process in which the copper alloy is heated at 550±150°C and a rolling process step subsequent to the intermediate annealing process are performed, and the rolling process step is performed. The heat treatment to be performed after the first heat treatment (A1) is (i) a first heat treatment (A1) in which the alloy is heated to 650±100°C, and (A2) a second heat treatment (A2) in which the alloy is heated to 850±100°C after the first heat treatment (A1), and in the cooling after the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225°C is 1°C / second or less; or (ii) a first heat treatment (A1) in which the alloy is heated to 650±100°C, and (A2) a second heat treatment (A2) in which the alloy is heated to 850±100°C after the first heat treatment (A1), and an aging treatment (A3) in which the alloy is heated to 225°C±100°C after the second heat treatment (A2).

[0054] The solution treatment, intermediate annealing treatment, rolling process step, first heat treatment (A1), second heat treatment (A2) and aging treatment (A3) in the manufacturing method of the internally grooved pipe of the present invention are the same as the solution treatment, intermediate annealing treatment, rolling process step, first heat treatment (A1), second heat treatment (A2) and aging treatment (A3) in the manufacturing method of the internally grooved pipe of the present invention.

[0055] In the method for producing an internally grooved pipe of the first embodiment of the present invention, after the second heat treatment (A2), an aging treatment (A3) can be further performed in which the pipe is heated at 225±100° C. The aging treatment (A3) in the method for producing an internally grooved pipe of the first embodiment of the present invention is the same as the aging treatment (A3) in the method for producing an internally grooved pipe of the present invention.

[0056] The inner-grooved tube of the present invention is suitably used as a heat exchanger for air conditioners such as room air conditioners and package air conditioners, or as a heat transfer tube for refrigerators and the like.

Example

[0057] (Example) (1) A copper alloy ingot consisting of 0.93% by mass of Ni, 0.24% by mass of P, and the balance Cu and inevitable impurities was melted and cast to produce a billet for hot extrusion. (2) The above billet was heated and hot extruded at 900 °C to obtain an extruded tube blank. Subsequently, the hot extruded tube blank was extruded into water and rapidly cooled (solution treatment). · The inner diameter was pierced hot to about 75 mm before extrusion. · The outer diameter of the extruded tube blank was 102 mm and the inner diameter was 75 mm. (3) The above extruded tube blank was cold rolled to obtain a cold rolled tube blank. Subsequently, the cold rolled tube blank was drawn a plurality of times cold to obtain a drawn tube. · The outer diameter of the drawn tube was 7.0 mm and the wall thickness was 1.0 mm. (4) The above drawn tube was subjected to an intermediate annealing treatment, and an inner-grooved tube was obtained by ball forging. · The outer diameter of the inner-grooved tube was 7.0 mm and the bottom wall thickness was 0.34 mm. (5) The above inner-grooved tube was subjected to a first heat treatment (first heat treatment (A1)) and a second heat treatment (second heat treatment (A2)) to obtain an inner-grooved tube. In some examples, after the second heat treatment (second heat treatment (A2)), an aging treatment (A3) was further performed to obtain an inner-grooved tube. <Intermediate annealing treatment> · Heat treatment temperature: 550 °C <First heat treatment> · Heat treatment temperature: 700 °C · Heat treatment time: 1800 seconds <Cooling after the first heat treatment> · Average cooling rate from the heat treatment temperature of the first heat treatment to 300 °C: 0.2 °C / second <Second heat treatment> · Heat treatment temperature: 850 °C · Heat treatment time: The time shown in Table 1 <Cooling after the second heat treatment> Average cooling rate from the heat treatment temperature of the second heat treatment to 225°C: Rate shown in Table 1 <Aging treatment (A3)> Heat treatment temperature: 225℃ Heat treatment time: The time shown in Table 1 (the time until the hardness reaches its peak through aging treatment) (6) The Vickers hardness of the obtained inner grooved pipes was measured. In addition, tensile tests were conducted on the obtained inner grooved pipes to measure the tensile strength and yield strength. The results are shown in Table 1.

[0058] [Table 1] 1) Vickers hardness 2) Tensile test. Unit: MPa

Claims

1. A casting process for casting a copper alloy ingot containing 0.40 to 1.50% by mass of Ni and 0.10 to 0.50% by mass of P, with the balance being Cu and inevitable impurities; A hot working process for hot working the copper alloy ingot; A cold working process for performing cold working after the hot working process; having: After the hot working process, before or after the cold working process, a solution treatment for solutionizing the copper alloy tube; After the solution treatment, an intermediate annealing treatment for heating at 550 ± 150 °C and a rolling process by cold working following the intermediate annealing treatment; After the rolling process, a first heat treatment (A1) for heating the copper alloy tube at 650 ± 100 °C; After the first heat treatment (A1), a second heat treatment (A2) for heating the copper alloy tube at 850 ± 100 °C; and In the cooling after performing the second heat treatment (A2), the average cooling rate from the heating temperature of the second heat treatment (A2) to 225 °C is 1 °C / second or less; A method for manufacturing a tube with an internal groove, characterized by the above.

2. The method for manufacturing a tube with an internal groove according to Claim 1, further comprising performing an aging treatment (A3) for heating at 225 ± 100 °C after the second heat treatment (A2).

3. A casting process for casting a copper alloy ingot containing 0.40 to 1.50% by mass of Ni and 0.10 to 0.50% by mass of P, with the balance being Cu and inevitable impurities; A hot working process for hot working the copper alloy ingot; A cold working process for performing cold working after the hot working process; having: After the hot working process, before or after the cold working process, a solution treatment for solutionizing the copper alloy tube; After the solution treatment, an intermediate annealing treatment for heating at 550 ± 150 °C and a rolling process by cold working following the intermediate annealing treatment; After the rolling process, a first heat treatment (A1) for heating the copper alloy tube at 650 ± 1 ​ ​ ​ ​

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