TW201441389A - Cold/hot water supply copper alloy seamless tube - Google Patents

Abstract

A cold/hot water supply copper alloy seamless tube is obtained by working a copper alloy, the copper alloy including 0.45 to 0.90 mass% of Sn, 0.01 to 0.08 mass% of Zr, and 0.004 to 0.04 mass% of P, with the balance being Cu and unavoidable impurities, the copper alloy, seamless tube having an electrical conductivity that satisfies the expression (1): ρ 2- ρ 1 ≥ 0.3 (%IACS)(where, ρ 1 is the electrical conductivity (%IACS) after solution treatment, and ρ 2 is the electrical conductivity (%IACS) after aging treatment). The copper alloy seamless tube exhibits high strength, shows only a small decrease in strength due to brazing, exhibits high creep deformation resistance, and has a high intermediate temperature embrittlement suppression effect.

Description

Copper alloy seamless pipe for water supply and hot water supply

The present invention relates to a seamless pipe made of a copper alloy, which is used for water supply and hot water supply in a pipe, and can be used for piping heating in a circulating hot water supply system such as a hotel, a hospital, an apartment, or the like. Water flow pipe for heat exchangers for water machines.

From the past, the water flow pipe for the heat exchanger for the hot water supply used in the circulating hot water supply system such as hotels, hospitals, apartments, etc., mostly uses copper alloy seamless pipes.

In recent years, in these heat exchangers, it is necessary to reduce the thickness of the seamless pipe or to reduce the cost. However, the strength of the prior phosphorus deoxidizing copper pipe is low, so that it is difficult to thin the wall, and development is required. Instead of its copper alloy seamless pipe.

Therefore, as a solid solution-strengthened copper alloy, Patent Document 1 proposes a copper alloy to which Sn is added. Further, as a solid solution strengthening and precipitation strengthening type copper alloy, Patent Document 2 and Patent Document 3 propose a copper alloy to which Sn and Zr are added.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2003-268467 (Application No.)

Patent Document 2: WO2008/041777 (Application Patent Range)

Patent Document 3: Japanese Patent Laid-Open Publication No. 2011-94174 (Application No.)

The copper alloy seamless pipe for water supply and hot water supply in the pipe has a risk of fatigue cracking due to thermal fatigue accompanying the repetition of thermal expansion and heat shrinkage. Further, the tension of the seamless pipe occurs due to thermal expansion, and there is a risk that the creeping deformation occurs due to the use temperature.

Therefore, in addition to the requirement of "higher strength" and "less reduction in strength due to welding", the copper alloy seamless pipe for water supply and hot water supply in the pipe is required to have heat-resistant fatigue cracking characteristics and Resistance to creep deformation.

However, the seamless tube made of a solid solution-strengthened copper alloy to which Sn is added as described in Document 1 has intermediate temperature brittleness, and is susceptible to thermal fatigue and creeping damage in a brittle temperature region. When the heat exchanger is manufactured, heating such as welding is performed in a state in which the tension in the seamless pipe acts, and intermediate temperature brittleness occurs, and embrittlement and cracking easily occur.

The factors for improving the brittleness of the intermediate temperature are S and H. By reducing the contents of S and H to the limit, the intermediate temperature brittleness can be suppressed to some extent, but it is not sufficient. Further, in order to lower the content of S to the limit, it is necessary to use a high-purity base metal, which is not preferable in terms of cost. Further, in order to lower the content of H to the limit, it takes a long time to melt-treat, and it is required to be subjected to environmentally controlled melting casting, etc., which is not preferable in terms of cost.

Therefore, even if it is the content of S and H of a normal grade (the grade which does not fall to a limit), it is expectable to suppress the intermediate temperature brittleness effectively. Further, the content of S and H in the normal level (the level which is not lowered to the limit) is about 0.0005 to 0.0008 mass%, and H is about 0.0002 to 0.0010 mass%.

On the other hand, as disclosed in Patent Document 2 and Patent Document 3, Sn is added. And Zr solid solution strengthening and precipitation strengthening copper alloy seamless pipe, by adding Zr, in addition to high strength and less strength due to welding, it can also suppress the performance of intermediate temperature brittleness to some extent .

However, further improvement in heat-resistant fatigue crack generation characteristics and improvement in resistance to creep deformation characteristics are required.

Accordingly, an object of the present invention is to provide a copper alloy seamless tube for a heat transfer tube which has high strength, low strength reduction due to welding, high latent deformation resistance, and high intermediate temperature brittleness.

The inventors of the present invention have conducted intensive studies to solve the problems in the above-mentioned conventional techniques, and as a result, it has been found that the strength can be obtained by causing the copper alloy to contain Sn and Zr in a specific content and further present Zr in an appropriate state in the copper alloy. The present invention has been completed in a copper alloy seamless pipe for water supply and hot water supply which has a high strength, a low strength reduction due to welding, a high resistance to creep deformation, and a high suppression effect of intermediate temperature brittleness.

That is, the present invention (1) provides a copper alloy seamless pipe for water supply and hot water supply, which is obtained by processing a copper alloy, and is characterized in that the copper alloy contains 0.45 to 0.90% by mass of Sn, 0.01 to 0.08. Zr of % by mass, and P of 0.004 to 0.04% by mass, and the balance includes Cu and unavoidable impurities, and the conductivity of the copper alloy seamless pipe for water supply and hot water supply satisfies the following formula (1): (1) Ρ2-ρ1≧0.3 (%IACS)

(In the formula, ρ1 means the conductivity after the solution treatment (% IACS), and ρ2 means the conductivity after the aging treatment (% IACS)).

Further, the present invention (2) provides a copper alloy seamless pipe for water supply and hot water supply, which is obtained by processing a copper alloy, and is characterized in that: The copper alloy contains 0.45 to 0.90% by mass of Sn, 0.01 to 0.08% by mass of Zr, and 0.004 to 0.04% by mass of P, and the balance contains Cu and unavoidable impurities, and the copper alloy for water supply and hot water supply is seamless. The conductivity of the tube satisfies the following formula (2): (2) ρ4-ρ3 ≧ 0.3 (% IACS)

(In the formula, ρ3 means the electrical conductivity after the heating-water cooling test at 950 ° C for 10 minutes (% IACS), and ρ4 means the electrical conductivity (% IACS) after the heating-water cooling test at 550 ° C for 60 minutes).

According to the present invention, it is possible to provide a copper alloy seamless tube for a heat transfer tube which has high strength, low strength reduction due to welding, high latent deformation resistance, and high intermediate temperature brittleness.

A copper alloy seamless pipe for water supply and hot water supply according to a first aspect of the present invention (hereinafter also referred to as a copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention) is obtained by processing a copper alloy, and The copper alloy is characterized in that it contains 0.45 to 0.90% by mass of Sn, 0.01 to 0.08% by mass of Zr, and 0.004 to 0.04% by mass of P, and the balance contains Cu and unavoidable impurities. The conductivity of the alloy seamless tube satisfies the following formula (1): (1) ρ2 - ρ1 ≧ 0.3 (% IACS)

(In the formula, ρ1 means the conductivity after the solution treatment (% IACS), and ρ2 means the conductivity after the aging treatment (% IACS)).

A copper alloy seamless pipe for water supply and hot water supply according to a second aspect of the present invention The copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention is obtained by processing a copper alloy, and is characterized in that the copper alloy contains 0.45 to 0.90% by mass of Sn and 0.01 to 0.08. Zr of % by mass, and P of 0.004 to 0.04% by mass, and the balance includes Cu and unavoidable impurities, and the conductivity of the copper alloy seamless pipe for water supply and hot water supply satisfies the following formula (2): (2) 4-4-ρ3≧0.3 (%IACS)

(In the formula, ρ3 means the electrical conductivity after the heating-water cooling test at 950 ° C for 10 minutes (% IACS), and ρ4 means the electrical conductivity (% IACS) after the heating-water cooling test at 550 ° C for 60 minutes).

A copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention and a copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention, and a copper alloy seamless pipe for water supply and hot water supply according to the present invention (1) The conductivity of the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention satisfies the formula (2), and is the same except for the difference.

The copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention and the copper alloy seamless pipe (2) for water supply and hot water according to the present invention are used as, for example, a recirculating hot water supply system for hotels, hospitals, apartments, and the like. A seamless pipe of a water flow pipe for water supply and hot water supply, such as a water flow pipe of a heat exchanger for a hot water heater, is a seamless pipe made of a copper alloy containing a copper alloy. It is a seamless tube made of copper alloy for water supply and hot water supply.

The copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention or the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention contains Sn, Zr and P as essential elements, and the balance Contains Cu and inevitable impurities.

In the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention or the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention, Sn has been improved by solid solution strengthening. The effect of the strength of the copper alloy and the effect of improving the ductility at normal temperature. Moreover, in the case of these elements, it can be alloyed at a relatively low temperature, and thus it is advantageous in terms of production.

In the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention or the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention, Zr has an effect of increasing the strength of the copper alloy by precipitation strengthening. . Further, Zr has an effect of reducing the strength reduction by retaining the Zr precipitate and suppressing the coarsening of the crystal grains before the welding temperature is too high.

In the copper alloy seamless pipe (1) for water supply and hot water supply of the present invention or the copper alloy seamless pipe (2) for water supply and hot water supply of the present invention, the content of Sn is 0.45 to 0.90% by mass. When the content of Sn in the copper alloy is less than 0.45 mass%, even if the solid solution strengthening of Sn is combined with the precipitation strengthening of Zr, the strengthening of the copper alloy is insufficient, and if it exceeds 0.90 mass%, the work hardening becomes Significantly, workability, particularly cold drawing workability, is deteriorated, and it is easy to cause intermediate temperature brittleness.

In the copper alloy seamless pipe (1) for water supply and hot water supply of the present invention or the copper alloy seamless pipe (2) for water supply and hot water supply of the present invention, the content of Zr is 0.01 to 0.08% by mass. When the content of Zr in the copper alloy is less than 0.01% by mass, the effect of suppressing coarsening of crystal grains is reduced, and the strength reduction due to welding is increased, and even if solid solution strengthening of Sn is combined with precipitation strengthening of Zr, The strengthening of copper alloys is also insufficient. On the other hand, when the content of Zr in the copper alloy exceeds 0.08% by mass, excessive precipitation hardening occurs, and workability is lowered. In particular, the cold rolling processability is deteriorated. As a result, the transfer of the spiral groove shape on the inner surface of the tube becomes insufficient, and it is difficult to obtain heat transfer performance as obtained by C1220.

In the copper alloy seamless pipe (1) for water supply and hot water supply of the present invention or the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention, the content of P is 0.004 to 0.04% by mass, preferably It is 0.015 to 0.030% by mass. By copper alloy containing 0.004% by mass The above P element, and the deoxidation in the display material is sufficiently performed. Further, when the content of P in the copper alloy is too large, the thermal conductivity of the copper alloy is lowered, so the content of P in the copper alloy is 0.040% by mass or less.

The conductivity of the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention satisfies ρ2-ρ1 of 0.3 or more, that is, the following formula (1) is satisfied: (1) ρ2 - ρ1 ≧ 0.3 (% IACS)

(wherein ρ1 means the conductivity after the solution treatment (% IACS), and ρ2 means the conductivity after the aging treatment (% IACS)), and preferably ρ2-ρ1 is 0.5 or more and 20 or less, that is, The following formula (1a) is satisfied: (1a) 0.5 ≦ ρ2 - ρ1 ≦ 20.

Moreover, the conductivity of the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention satisfies ρ4 - ρ3 of 0.3 or more, that is, the following formula (2) is satisfied: (2) ρ4 - ρ3 ≧ 0.3 (% IACS)

(In the formula, ρ3 means the conductivity after 10 minutes of heating at 950 ° C - water cooling test (% IACS), and ρ4 means the conductivity after heating-water cooling test at 550 ° C for 60 minutes (% IACS)) Preferably, ρ4-ρ3 is 0.5 or more and 20 or less, that is, the following formula (2a): (2a) 0.5 ≦ ρ4 - ρ3 ≦ 20 is satisfied.

In the present invention, the term "solution treatment" refers to a treatment for sufficiently solidifying a Zr-based intermetallic compound crystallized during cooling in the melting and casting steps, and the so-called aging treatment means that the Zr-based metal is used. Interphase compound precipitation treatment. The copper alloy seamless pipe for water supply and hot water supply according to the present invention is produced in the order of "melting and casting step → hot extrusion step → cold working step → intermediate annealing treatment and rolling step → aging treatment as needed". Moreover, in this manufacturing step, the hot extrusion step The heating is a solution treatment for sufficiently solidifying the Zr-based intermetallic compound crystallized during the cooling and casting steps.

In the copper alloy seamless pipe, if the Zr crystallized during the melting and casting process is not sufficiently dissolved in the solution treatment, the aging treatment for obtaining the strength commensurate with the content of Zr is obtained. The amount and distribution of the fine precipitates precipitated in the middle became inappropriate. Further, the Zr-based crystal material which is not solid-solved in the solution treatment does not contribute to the improvement of the strength, and also hinders the subsequent cold working step, the rolling step, and the workability in the bending processing step in the production of the heat exchanger. Further, in the solidification process or the solution treatment at the time of casting, the solid solution Zr captures S by forming a compound with S, and captures H which forms a grain boundary void during hot extrusion, thereby improving the creep resistance. Deformation characteristics, suppressing intermediate temperature brittleness. Therefore, Zr which is solid-solved after the solution treatment not only contributes to the precipitation strengthening by the subsequent step of the immediate treatment, but also contributes to the improvement of the latent deformation resistance and the suppression of the intermediate temperature brittleness. Further, by suppressing the precipitation state of Zr in the aging treatment, the effect of suppressing the intermediate temperature brittleness is improved.

However, it is difficult to quantify the precipitation state of Zr in the solid solution state of Zr in the solution treatment. Therefore, the inventors of the present invention repeatedly conducted intensive studies and found that Zr in the solution treatment can be grasped by the difference between the conductivity after the solution treatment and the conductivity after the aging treatment (ρ2-ρ1). The precipitation state of Zr in the solid solution state and the aging treatment, and ρ2-ρ1 is defined as a specific range, whereby the resistance to creep deformation can be improved, and the intermediate temperature brittleness can be suppressed. That is, the conductivity of the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention satisfies ρ2-ρ1 of 0.3 or more, that is, the following formula (1) is satisfied: (1) ρ2 - ρ1 ≧ 0.3 (% IACS) Preferably, it is satisfied that ρ2-ρ1 is 0.5 or more and 20 or less, that is, the following formula (1a) is satisfied: (1a) 0.5≦ρ2-ρ1≦20.

When ρ2-ρ1 is in the above range, the creep deformation resistance characteristic can be improved, and the intermediate temperature brittleness can be suppressed.

Further, the inventors of the present invention found that the difference between the electrical conductivity after the heating-water cooling test at 950 ° C for 10 minutes and the electrical conductivity after the heating-water cooling test at 550 ° C for 60 minutes can be grasped. In the solution state of Zr in the solution treatment, the precipitation state of Zr in the aging treatment, and ρ4-ρ3 are defined as a specific range, whereby the creep resistance deformation can be improved, and the intermediate temperature brittleness can be suppressed. That is, the conductivity of the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention satisfies ρ4 - ρ3 of 0.3 or more, that is, the following formula (2) is satisfied: (2) ρ4 - ρ3 ≧ 0.3 (% IACS) Preferably, ρ4-ρ3 is satisfied to be 0.5 or more and 20 or less, that is, the following formula (2a): (2a) 0.5 ≦ ρ4 - ρ3 ≦ 20 is satisfied.

When ρ4 - ρ3 is in the above range, the creep deformation resistance characteristic can be improved, and the intermediate temperature brittleness can be suppressed.

Further, in the present invention, the heating-water cooling test at 950 ° C for 10 minutes is a test in which a copper alloy seamless pipe to be tested is heated at 950 ° C ± 25 ° C for 10 minutes and then subjected to water cooling. The method is as follows: First, the test object is placed in an electric furnace set to a nitrogen atmosphere at 950 ± 25 ° C, and after the temperature in the furnace is restored to 950 ° C, it is maintained at 950 ° C ± 25 ° C for 10 minutes, and then, from 950 ° C. Directly water cooled. Then, the electrical conductivity (% IACS) of the test object after the heating-water cooling test at 950 ° C for 10 minutes was measured, and ρ3 was obtained.

Further, in the present invention, the heating-water cooling test at 550 ° C for 60 minutes is performed by heating and water-cooling a copper alloy seamless pipe to be tested at 950 ° C for 10 minutes, followed by 550 ° C ± 10 ° C. Water cooling after 60 minutes of heating The test was carried out by first heating the test object at 950 ° C ± 25 ° C for 10 minutes in the same manner as the heating-water cooling test at 950 ° C for 10 minutes, and then directly performing water cooling from 950 ° C, and then, The test object which was subjected to heating and water cooling at 950 ° C for 10 minutes was placed in a salt bath furnace, and kept at 550 ° C ± 10 ° C for 60 minutes, and then directly subjected to water cooling. Then, the electrical conductivity (% IACS) of the test object after the heating-water cooling test at 550 ° C ± 10 ° C for 60 minutes was measured to obtain ρ4.

The copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention or the copper alloy seamless pipe (2) for water supply and hot water supply of the present invention may further contain S atoms. In the case where the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention or the copper alloy of the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention further contains S, the S in the copper alloy The content is 0.0005 to 0.0010% by mass. Further, the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention or the copper alloy of the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention may further contain H. In the case where the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention or the copper alloy of the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention further contains H, the H in the copper alloy The content is 0.0002 to 0.0020% by mass. When the content of S or the content of H in the copper alloy exceeds the above range, S or H cannot be sufficiently captured by the solid solution of Zr, and the effect of improving the resistance to latent deformation and suppressing the brittleness of the intermediate temperature cannot be obtained. On the other hand, when the content of S or the content of H in the copper alloy is less than the above range, the effect of improving the creep deformation resistance and suppressing the intermediate temperature brittleness can be obtained, but the cost is easily increased.

The copper alloy seamless pipe for water supply and hot water supply according to the present invention is sequentially subjected to melting, casting and cooling, hot extrusion and cooling, cold working, intermediate annealing treatment as needed, and rolling to aging treatment.

First, melting, casting, and cooling are performed. In melting and casting, based on The conventional method is melted and casted to obtain a billet in which a specific element is blended at a specific content. For example, the base metal of the copper base metal and the copper alloy seamless pipe of the water supply and hot water supply of the present invention is blended in such a manner that the content of the copper alloy seamless pipe for water supply and hot water supply of the present invention reaches a specific content or The alloy containing the element and the copper is adjusted to the composition, and then a cast material such as a high-frequency melting furnace is used. The billet is then cooled after casting.

Then, hot extrusion and cooling are performed. In hot extrusion, a billet obtained by casting is heated at a specific temperature to perform hot extrusion. Hot extrusion is carried out by mandrel extrusion. That is, hot extrusion is performed in a state in which a blank which is previously cold-punched before heating or a blank which is thermally perforated before extrusion is inserted into a mandrel. Then, after hot extrusion, it was rapidly cooled to obtain a hot extrusion roughing tube.

Then, cold working is carried out. In the cold working, the hot-extruded rough-processed pipe obtained by hot extrusion is subjected to cold working such as cold rolling or cold drawing, and the outer diameter and wall thickness of the pipe are reduced to obtain a seamless rough-worked pipe.

When obtaining the inner smooth tube (baked tube) in which the inner groove is not formed, after the cold working, the seamless roughing tube obtained by the cold working is heated at 400 to 600 ° C, and then the aging treatment is performed. . Then, by performing aging treatment, the copper alloy seamless pipe (1) for water supply and hot water supply of the present invention or the copper alloy seamless pipe (2) for water supply and hot water supply of the present invention is obtained.

In the case of obtaining a tube having an inner surface groove with an inner groove, after the cold working, the intermediate annealing of the seamless roughing tube obtained by cold working is performed at 400 to 600 ° C, and then rolling is performed. . The rolling system is carried out by arranging a rolling insert having a spiral groove processing on the outer surface of the seamless roughing pipe, and pressing a plurality of rolling balls at a high speed to push from the outside of the pipe to make the rolling The slot of the insert is transferred to the inner surface of the tube. Then, the seamless tube that has been rolled is subjected to aging treatment. Time The treatment is carried out by heating the rolled seamless tube at 400 to 600 ° C and cooling it. Then, by performing aging treatment, the copper alloy seamless pipe (1) for water supply and hot water according to the present invention or the copper alloy seamless pipe (2) for water supply and hot water according to the present invention is obtained.

Further, the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention has a conductivity of the formula (1): ρ2 - ρ1 ≧ 0.3 (% IACS), preferably a formula (1a): 0.5 ≦. The method of ρ2-ρ1≦20, in addition, as the copper alloy seamless pipe (2) for water supply and hot water supply of the present invention, the conductivity is expressed by the formula (2): ρ4 - ρ3 ≧ 0.3 (% IACS), preferably The method of the formula (2a): 0.5≦ρ4-ρ3≦20, for example, may be a method of adjusting the cooling rate of the billet during melting and cooling after casting. The present inventors have found that the existence state of Zr in the copper alloy varies depending on the cooling rate of the billet during melting and casting, and the existence state of Zr after melting and casting is different, and "ρ2-ρ1" and The value of "ρ4-ρ3" has an effect. Further, it is suitable to adjust the conductivity to the formula (1), preferably the formula (1a), depending on the diameter of the billet, the cooling method after casting, the cooling condition after casting, the solution treatment conditions, the aging treatment conditions, and the like. Cooling rate; or suitable for adjusting the cooling rate of formula (2), preferably formula (2a), so the cooling rate of the billet in the cooling after melting and casting can be based on the diameter of the billet, the cooling method, and the cooling condition after casting. The solution treatment conditions, the aging treatment conditions, and the like are appropriately selected. Moreover, the conductivity of the copper alloy seamless pipe (1) for water supply and hot water supply according to the present invention satisfies the formula (1) by appropriately adjusting the diameter of the blank, the cooling conditions after casting, the solution treatment conditions, the aging treatment conditions, and the like. The conductivity of the copper alloy seamless pipe (2) for water supply and hot water supply according to the present invention satisfies the formula (2), preferably the formula (2a). The way to adjust.

The copper alloy seamless pipe for water supply and hot water supply of the present invention is wound into a coil shape as a heat transfer tube for a heat exchanger, and is supplied to a heat exchanger (cross finned tube type heat exchanger). The cross finned tube heat exchanger uses aluminum fins on the air side The heat transfer tubes on the refrigerant side are assembled and integrated.

The cross-fin tube type heat exchanger is produced by first forming an aluminum plate fin formed with a plurality of specific assembly holes by press working or the like, and then laminating the obtained aluminum plate fins. The copper alloy seamless pipe for water supply and hot water supply (1) of the present invention after the hairpin is bent and cut into a specific size and shape inside the assembly hole, or the copper alloy for water supply and hot water supply of the present invention The tube (2) is then expanded, and the tube is expanded and fixed to the aluminum plate fin, and the U-bend is welded to the end of the seamless tube opposite to the side on which the bending process has been performed.

[Examples]

The invention is further illustrated by the following examples, which are merely illustrative and not limiting of the invention.

(Examples and Comparative Examples) <Copper alloy seamless pipe for water supply and hot water> (melting, casting and cooling)

A billet having an outer diameter of 254 mm containing the chemical components shown in Table 1 was cast by semi-continuous casting, followed by cooling. The amount of water of the cooling water of the billet at this time is set as described below. Further, in Table 1, the balance is Cu and unavoidable impurities.

Cooling condition A: Cooling water volume 1,000 L/min

Cooling condition B: cooling water volume 600L/min

(hot extrusion and cooling)

The billet obtained in the above manner was heated by holding it at 950 ° C (± 25 ° C) for 10 minutes or more in a continuous heating furnace, and then extruding an outer diameter of 81 mm × a wall thickness of 8 mm at an extrusion temperature of 950 ° C. Tube, extruded directly into water for cooling, obtained Hot extrusion of the roughing tube. At this time, the solution is also subjected to a solution treatment.

A sample for measuring the conductivity of the sample at the head and tail of the obtained hot-extruded rough-processed tube (Sample 1).

(cold processing)

The hot-extruded seamless rough-worked tube obtained in the above manner was subjected to cold rolling and cold drawing to obtain a seamless rough-processed pipe having an outer diameter of 9.52 mm and a wall thickness of 0.8 mm.

(aging treatment)

The seamless rough-worked tube obtained in the above manner was heated in a non-oxidizing atmosphere at 550 ° C for 60 minutes in a batch furnace to obtain a copper alloy seamless pipe for water supply and hot water supply.

Sample 2 for copper alloy seamless pipe from the obtained water supply and hot water supply was used for conductivity measurement. Also, samples 3 and 4 were sampled for the heating-water cooling test.

<heating-water cooling test>

The so-called heating-water-cooling test at 950 ° C for 10 minutes is a test in which the copper alloy seamless tube to be tested is heated at 950 ° C ± 25 ° C for 10 minutes and then subjected to water cooling by the following method: First, the test is carried out. The object was placed in an electric furnace set to a nitrogen atmosphere at 950 ± 25 ° C, and after the temperature in the furnace was restored to 950 ° C, it was kept at 950 ° C ± 25 ° C for 10 minutes, and then directly water-cooled from 950 ° C. Then, the electrical conductivity (% IACS) of the test object after the heating-water cooling test at 950 ° C for 10 minutes was measured, and ρ3 was obtained.

In addition, the heating-water cooling test at 550 ° C for 60 minutes is performed by heating and water-cooling the copper alloy seamless tube to be tested at 950 ° C for 10 minutes, followed by heating at 550 ° C ± 10 ° C for 60 minutes. The water cooling test was carried out by first heating the test object at 950 ° C ± 25 ° C for 10 minutes and then directly from 950 ° C in the same manner as the heating-water cooling test at 950 ° C for 10 minutes. , Then, the test object which was subjected to heating and water cooling at 950 ° C for 10 minutes was placed in a salt bath furnace, and kept at 550 ° C ± 10 ° C for 60 minutes, and then directly subjected to water cooling. Then, the electrical conductivity (% IACS) of the test object after the heating-water cooling test at 550 ° C ± 10 ° C for 60 minutes was measured to obtain ρ4.

(heating-water cooling test 1) 950 ° C ± 25 ° C × 10 minutes

First, the sample 3 was placed in an electric furnace set to a nitrogen atmosphere at 950 ± 25 ° C. After the temperature in the furnace was restored to 950 ° C, it was kept at 950 ± 25 ° C for 10 minutes, and then directly water-cooled from 950 ° C. Heating - water cooling test 1.

(heating-water cooling test 2) 550 ° C ± 10 ° C × 60 minutes

First, in the same manner as in the heating-water cooling test 1, the sample 4 was heated and water-cooled at 950 ± 25 ° C for 10 minutes, and then, the same sample of heating and water cooling as in the heating-water cooling test 1 was carried out. The mixture was placed in a salt bath furnace at 550 ° C ± 10 ° C for 60 minutes, and then directly subjected to water cooling, and subjected to a heating-water cooling test 2.

<evaluation> (mechanical properties)

The torch was brazed using a solder (JIS Z3264 BCuP-2) and an oxygen-propane mixed gas to prepare a sample for measuring the withstand voltage after soldering. At this time, soldering is performed until the solder flows into the joint portion. The cooling system was air-cooled, and after cooling, a fracture test by water pressure was performed, and the tensile strength was estimated by the following formula *1 according to the breaking strength, and the mechanical properties (tensile strength and elongation) before and after the welding were evaluated.

The mechanical properties before welding were evaluated by a tensile test, and the tensile test was carried out in accordance with JIS Z2241. Strength and elongation. The results are shown in Table 3.

<Formula *1> KHK type: bursting pressure = 2 × tensile strength × wall thickness / (outer diameter - 0.8 × wall thickness)

(Conductivity)

The conductivity was measured by a method according to JIS H0505, that is, a four-terminal method, and the value obtained by dividing by 0.15328 was expressed as a percentage.

(Intermediate temperature brittleness test)

The copper alloy seamless tube was subjected to a tensile test at a tensile speed of 10 ^-4 at 350 °C. The elongation (δ) was 30% or more, and it was set as pass.

(thermal fatigue test)

The copper alloy seamless pipe was loaded with 100,000 times of repeated internal pressure of 0 to 15 MPa in a thermostatic chamber at 100 ° C to conduct a thermal fatigue test. Those who did not produce cracks in the test were deemed to be qualified.

Claims (3)

A copper alloy seamless pipe for water supply and hot water supply, which is obtained by processing a copper alloy, and is characterized in that the copper alloy contains 0.45 to 0.90% by mass of Sn, 0.01 to 0.08% by mass of Zr, and 0.004~ 0.04% by mass of P, and the balance contains Cu and unavoidable impurities. The conductivity of the copper alloy seamless pipe for water supply and hot water supply satisfies the following formula (1): (1) ρ2 - ρ1 ≧ 0.3 (% IACS) (wherein ρ1 means the conductivity after the solution treatment (% IACS), and ρ2 means the conductivity after the aging treatment (% IACS)). A copper alloy seamless pipe for water supply and hot water supply, which is obtained by processing a copper alloy, and is characterized in that the copper alloy contains 0.45 to 0.90% by mass of Sn, 0.01 to 0.08% by mass of Zr, and 0.004~ 0.04% by mass of P, and the balance contains Cu and unavoidable impurities. The conductivity of the copper alloy seamless pipe for water supply and hot water supply satisfies the following formula (2): (2) ρ4 - ρ3 ≧ 0.3 (% IACS) (wherein ρ3 means the electrical conductivity after the heating-water cooling test at 950 ° C for 10 minutes (% IACS), and ρ4 means the electrical conductivity after the heating-water cooling test at 550 ° C for 60 minutes (% IACS)). The copper alloy seamless pipe for water supply and hot water supply according to claim 1 or 2, wherein the copper alloy further contains 0.005 to 0.0010% by mass of S and 0.0002 to 0.0020% by mass of H.