JP5792088B2 - Copper alloy tube - Google Patents

Description

  The present invention relates to a copper alloy tube suitable for a heat transfer tube for a water flow tube that constitutes a gas cooler in Ecocute (registered trademark), and in particular, while maintaining a function of suppressing a scale mainly composed of calcium carbonate, The present invention relates to a copper alloy tube excellent in workability for performance.

  Mainly, the gas cooler is manufactured by a phosphorus deoxidized copper pipe (JIS H3300 C1220). In addition, there are various types of gas coolers, and in order to improve the performance, many water flow pipes are processed as follows and combined with a heat radiating pipe (Patent Documents 1 to 5).

  The eco-cute structure requires hot water to be stored in the hot water storage tank at as high a temperature as possible. Depending on the operation mode controlled from the climate, etc., especially in the winter when the temperature is low, the water is circulated in the gas cooler in the process of 90 There are also cases where the water is discharged at over ℃.

Depending on the quality of the water used, the hardness often varies, and in the case of water quality with a high calcium carbonate hardness in the water quality items (generally 100 mg _{CaCO 3} / L or more), the higher the water temperature, the calcium carbonate scale To precipitate.

  When the gas cooler is operated in a mode in which the hot water is discharged at a high temperature, calcium carbonate scale deposits and accumulates in the water flow pipe at the high temperature portion in the gas cooler, eventually clogging the water flow pipe, Problems that make it impossible to use may occur.

  Especially in ordinary households, the number of households who prefer to use groundwater is increasing due to the recent saving-oriented influence, but groundwater has a lot of water with a high calcium hardness component, which hinders future sales expansion of Ecocute. There is an urgent need to solve the problem of calcium carbonate scale.

  A technique for preventing this calcium carbonate scale is disclosed in Patent Document 1. Phosphorus deoxidized copper pipes (JIS H3300 C1220) used in ordinary gas cooler water pipes are sold to users mainly as straight pipes or level-wound coils (LWC) of smooth pipes or internally grooved pipes. Delivered. Further, in order to efficiently transfer heat from the heat radiating pipe to the water flowing through the water flow pipe, it is preferable that the water flow through the water flow pipe while being stirred in a turbulent state. In the case of EcoCute, the flow rate is as slow as 1 liter (L) per minute, so in order to produce a stirring effect, the disk is pressed spirally from the outer surface of the tube to form a continuous mountain on the inner surface of the tube. Corrugating (Patent Document 2), dimple processing (Patent Document 6), and the like, in which a dent is made from the outer surface and discontinuous protrusions are formed on the inner surface, are performed.

  By applying the corrugating or dimple processing described above to the water flow tube manufactured with the alloy composition disclosed in the above prior art, it is possible to obtain an eco-cute gas cooler with excellent heat exchange performance and excellent scale adhesion suppression effect. it can.

JP 2008-274421 A JP 2010-112565 A JP 2005-147466 A JP 2003-097898 A JP 2004-360974 A JP 2004-190923 A

  In consideration of workability, it is considered that a soft material softened by heat annealing is suitable for the tempering of the material when performing the above-described processing. In addition, it is also known that the effect of increasing the scale adhesion suppressing action by adding additional elements to the material surface by heat annealing is obtained (Patent Document 1).

  However, considering the workability, if the copper tube is heated excessively, the crystal grains become coarse. The additive elements concentrated on the surface by heating are more likely to gather at the crystal grain boundaries, and the surface was viewed macroscopically (macroscopically) from the concentration difference between the crystal grain boundaries and the additive elements within the crystal grains. In some cases, a non-uniform state of the additive element may be formed.

  When the additive element is in a non-uniform state, there are non-uniform portions that are effective in suppressing scale adhesion and non-uniform portions, resulting in a portion where the scale adheres and a portion where the scale does not adhere. As shown in FIG. 4, in the case of a coarse crystal grain, a region having a relatively high concentration of the additive element is formed with a certain width from the crystal grain boundary due to the additive element accumulated in the vicinity of the crystal grain boundary. In addition, as shown in FIG. 5, even in the case of fine crystal grains, a region where the concentration of the additive element is relatively high is formed from the crystal grain boundary with a certain width due to the additive elements gathered in the crystal grains. This is the same as in the case of coarse crystal grains. Therefore, in the case of fine crystal grains, there are few regions where the concentration of the additive element is low, and the degree of non-uniformity of the concentration of the additive element is low. Appears clearly, and the non-uniform state of the additive element becomes clear.

  The situation in such coarse crystal grains is not only preferable because the portion to which the scale adheres cannot be suppressed, but the exposed portion can be a starting point of local corrosion such as pitting corrosion because the surface is unevenly exposed. Absent.

  This invention is made | formed in view of this problem, Comprising: It aims at providing the copper alloy pipe | tube with which scale adhesion was suppressed and heat transfer performance was excellent.

The copper alloy tube according to the first invention of this application is:
Sn: 0.05 to 3.0% by mass,
P: 0.004 to 0.2% by mass,
Zr (contained as solid solution, simple substance and / or compound in matrix): 0.005 to 0.2% by mass (in the case of compound, converted to Zr)
Containing
A copper alloy tube having a composition in which the balance is made of Cu and inevitable impurities,
The difference P _peak -P ₂₀₀₀ between the maximum value P _peak of the mass ratio of P from the outermost surface of the copper alloy tube to a depth of 250 nm and the average concentration P ₂₀₀₀ of P at a depth of 1900 to ₂₀₀₀ nm is determined by glow discharge luminescence surface analysis. 0.50 mass% or more and 25 mass% or less,
Difference between the maximum value Sn _peak of Sn mass from the outermost surface of the copper alloy tube to a depth of 250 nm and the average Sn concentration Sn ₂₀₀₀ at a depth of 1900 to ₂₀₀₀ nm by the glow discharge luminescence surface analysis Sn _peak −Sn ₂₀₀₀ Is 0.30 mass% or more and 15 mass% or less,
Difference _Zr peak _{-Zr 2000} the average density _{Zr 2000} of Zr in maximum _{Zr peak} and depth 1900~2000nm the weight ratio of Zr to a depth of 250nm from the outermost surface of the copper alloy tube according to the glow discharge emission surface analysis Is 0.010 mass% or more and 3.0 mass% or less,
The average grain size is 5-25 μm,
Tensile strength σ is 260 to 450 MPa
It is characterized by being.

The copper alloy according to the second invention of the present application is
Sn and at least one element selected from the group consisting of Zn and Al: the total value is 0.05 to 3.0% by mass , and the ratio of Sn in Sn, Zn and Al is 77.5% that's all,
P: 0.004 to 0.2% by mass,
Zr (contained as solid solution, simple substance and / or compound in matrix): 0.005 to 0.2% by mass (in the case of compound, converted to Zr)
Containing
A copper alloy tube having a composition in which the balance is made of Cu and inevitable impurities,
The difference P _peak -P ₂₀₀₀ between the maximum value P _peak of the mass ratio of P from the outermost surface of the copper alloy tube to a depth of 250 nm and the average concentration P ₂₀₀₀ of P at a depth of 1900 to ₂₀₀₀ nm is determined by glow discharge luminescence surface analysis. 0.50 mass% or more and 25 mass% or less,
With respect to at least one selected element selected from the group consisting of Sn and Zn and Al, the total of the Sn and selected elements from the outermost surface of the copper alloy tube to a depth of 250 nm by the glow discharge luminescence surface analysis. The difference SZA _peak -SZA ₂₀₀₀ between the maximum value SZA _peak of the mass ratio and the average concentration SZA ₂₀₀₀ of the Sn and the selected element at a depth of 1900 to ₂₀₀₀ nm is 0.30% by mass or more and 15% by mass or less.
Difference _Zr peak _{-Zr 2000} the average density _{Zr 2000} of Zr in maximum _{Zr peak} and depth 1900~2000nm the weight ratio of Zr to a depth of 250nm from the outermost surface of the copper alloy tube according to the glow discharge emission surface analysis Is 0.010 mass% or more and 3.0 mass% or less,
The average grain size is 5-25 μm,
Tensile strength σ is 260 to 450 MPa
It is characterized by being.

In these copper alloy tubes, the ratio (yield ratio) σ _0.5 / σ of the proof stress σ _0.5 and the tensile strength σ is preferably 0.850 ≦ σ _0.5 /σ≦0.985. . Further, these copper alloy tubes are, for example, inner surface grooved tubes in which a plurality of grooves are formed on the inner surface.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesion of the scale of the surface which contacts the water flow in a copper alloy pipe | tube can be suppressed, and a copper alloy pipe | tube with a long life as a heat transfer pipe | tube and excellent in heat transfer performance can be obtained.

It is a graph which shows the analysis result of P by glow discharge luminescence surface analysis. It is a graph which shows the analysis result of Sn by a glow discharge luminescence surface analysis. It is a graph which shows the analysis result of Zr by glow discharge luminescence surface analysis. It is a figure which shows the concentration to the crystal grain boundary of the additive element in the case of a coarse crystal grain. It is a figure which shows the concentration to the crystal grain boundary of the addition element in the case of a fine crystal grain.

  Hereinafter, embodiments of the present invention will be described in detail. First, the reason for adding the component and the reason for limiting the composition in the composition of the copper alloy tube of the first invention of the present application will be described.

“Sn: 0.05 to 3.0 mass%”
Sn has a function of preventing the scale from adhering to the copper alloy tube by adding it to the copper alloy tube. When the Sn content is less than 0.05% by mass, even if a heat treatment for concentrating the additive element on the surface is performed, the function of suppressing the adhesion of scale due to Sn becomes insufficient. When Sn exceeds 3.0 mass%, tensile strength will rise more than necessary and workability, such as corrugating, will deteriorate. Further, the amount of Sn oxide present on the surface of the copper alloy tube is increased, and the wettability of the brazing material is lowered. Therefore, Sn is contained in an amount of 0.05 to 3.0% by mass.

“P: 0.004 to 0.2 mass%”
P is usually added as a deoxidizer in the melting process and the casting process, but by adding P, P is considered to negatively charge the surface of the copper alloy tube, and the surface of the copper alloy tube There is an effect of suppressing the generation and adhesion of scale to the surface. However, if P exceeds 0.2% by mass, defects are generated in the casting process, and the quality cannot be maintained even after the subsequent process. On the other hand, when P exceeds 0.2% by mass, the corrosion resistance of the copper alloy tube starts to be affected in a state of being concentrated on the surface after the heat treatment. When P is less than 0.004% by mass, the effect of suppressing the scale cannot be expected even if heat treatment for concentrating the additive element on the surface is performed.

“Zr (contained as solid solution, simple substance and / or compound in the matrix): 0.005 to 0.2% by mass (in the case of a compound, converted to Zr)”
Zr also has an effect of preventing scale adhesion to the copper alloy tube, but if the content of Zr is less than 0.005% by mass, the effect of preventing scale adhesion cannot be obtained. On the other hand, if the Zr content exceeds 0.2% by mass, the tensile strength increases more than necessary, and workability such as corrugating is deteriorated. In addition, the amount of Zr oxide present on the surface of the copper alloy tube is increased, and the wettability of the brazing material is lowered.

“Difference between the maximum value P _Peak of the mass ratio of P from the outermost surface to a depth of 250 nm and the average concentration P ₂₀₀₀ of P at a depth of 1900 to ₂₀₀₀ nm in glow discharge light emitting surface analysis from the surface of the copper alloy member P _Peak -P ₂₀₀₀ is 0.50 mass% or more and 25 mass% or less "
Regardless of the amount of P added in the above composition range, the peak P _{Peak of the} P distribution appearing in the region from the outermost surface to a depth of 250 nm is the average concentration P of P at 1900 to 200 nm, which is regarded as the base concentration of the bulk. _If the difference from ₂₀₀₀ is 0.50% by mass or more, the effect of suppressing scale adhesion is sufficiently obtained. If this difference is less than 0.50% by mass, the effect becomes insufficient. On the other hand, when the difference exceeds 25% by mass, the corrosion resistance against corrosion (for example, pitting corrosion) due to the surface state deteriorates.

In glow discharge emission surface analysis from "copper alloy member surface, the difference between _{Sn Peak} of the maximum value _{Sn Peak} mass ratio of Sn to a depth of 250nm from the outermost surface, and the average concentration _{Sn 2000} of Sn in depth 1900~2000nm -Sn ₂₀₀₀ is 0.30 mass% or more and 15 mass% or less "
Regardless of the amount of Sn added in the composition range described above, the Sn distribution peak Sn _Peak appearing in the region from the outermost surface to a depth of 250 nm is the average Sn Sn concentration at 1900 to 200 nm regarded as the bulk base concentration. _If the difference from ₂₀₀₀ is 0.30% by mass or more, the effect of suppressing scale adhesion can be sufficiently obtained. If this difference is less than 0.30% by mass, the effect becomes insufficient. Moreover, when the said difference exceeds 15 mass%, when brazing and joining in a heat exchanger manufacturing process, the wetting spreadability of a brazing material will fall.

“Difference between the maximum value Zr _Peak of the mass ratio of Zr from the outermost surface to a depth of 250 nm and the average concentration Zr ₂₀₀₀ of Zr at a depth of 1900 to ₂₀₀₀ nm in the glow discharge emission surface analysis from the surface of the copper alloy member Zr _Peak -Zr ₂₀₀₀ is 0.010 mass% or more and 3.0 mass% or less. "
Regardless of the amount of Zr added in the composition range described above, the peak _{Zr Peak} of Zr distribution appearing in the region to a depth of 250nm from the outermost surface, the average concentration of Zr Zr in 1900~200nm regarded as base density of bulk If it is 0.010 mass% or more in the difference with ₂₀₀₀ , the effect which suppresses scale adhesion is fully acquired. If this difference is less than 0.010% by mass, the effect is insufficient. When the difference exceeds 3% by mass, the amount of Zr oxide increases and the wetting and spreading property of the brazing material decreases.

“Average crystal grain size is 5-25 μm”
Additive elements added to copper generally exhibit different concentration distributions near the grain boundaries and within the crystal grains. When the surface of the material is viewed macroscopically, if the average crystal grain size exceeds 25 μm, the non-uniform distribution of the origin of addition between the crystal grain boundaries and the crystal grains becomes prominent, and the desired scale adhesion suppression function is obtained. Disappear. On the other hand, if the average crystal grain size exceeds 25 μm, the material strength becomes too soft, and the secondary workability such as corrugating is deteriorated. On the other hand, when the average crystal grain size is less than 5 μm, it is difficult to suppress the tensile strength, and similarly, secondary workability such as corrugating is deteriorated.

“Tensile strength σ is 260 to 450 MPa”
When the tensile strength σ of the copper alloy tube is less than 260 MPa, secondary workability such as corrugating is deteriorated. If the tensile strength σ exceeds 450 MPa, for example, the material is too hard and difficult to process, and it is impossible to ensure sufficient dimensions such as the height of the processed portion, for example, the height of the inner surface of the pipe in corrugating.

  Next, the reason for adding the component and the reason for limiting the composition in the composition of the copper alloy tube of the second invention of the present application will be described. In the second invention, in addition to the additive element Sn of the first invention, at least one element selected from the group consisting of Zn and Al is added to the copper alloy tube.

“At least one element selected from the group consisting of Sn, Zn and Al: 0.05 to 3.0 mass% in total”
Zn and Al, like Sn, impart a scale adhesion inhibiting function to the copper alloy tube. If the total content of Zn and / or Al in addition to Sn is less than 0.05% by mass, even if a heat treatment is performed to concentrate the additive elements on the surface of the copper alloy tube, the function of inhibiting scale adhesion is insufficient. Become. When the total value of Sn and Zn and / or Al exceeds 3.0% by mass, the tensile strength increases more than necessary, and the workability such as corrugating is deteriorated, and Sn existing on the surface of the copper alloy tube is present. , Zn and Al oxides increase and the wetting and spreading properties of the brazing material decrease.

“When at least one of Zn and Al is added in addition to Sn (hereinafter, the total of Sn, Zn and / or Al is referred to as SZA), in the glow discharge emission surface analysis from the surface of the copper alloy member, The difference SZA _Peak- SZA ₂₀₀₀ between the maximum value SZA _Peak of the mass ratio of SZA from the surface to a depth of 250 nm and the average concentration SZA ₂₀₀₀ of SZA at a depth of 1900 to ₂₀₀₀ nm is 0.30 mass% or more and 25 mass% or less.
Regardless of the total amount of SZA added in the aforementioned composition range, the peak SZA _Peak of the total distribution of SZA appearing in the region from the outermost surface to a depth of 250 nm is considered to be a bulk base concentration at 1900 to 200 nm. If the difference from the average concentration of SZA SZA ₂₀₀₀ is 0.30% by mass or more, the effect of suppressing the scale adhesion is sufficiently obtained. If the difference is less than 0.30% by mass, the effect is insufficient. When the difference exceeds 25% by mass, the corrosion resistance against corrosion (for example, pitting corrosion) due to the surface state is affected.

  Other configurations in the second invention of the present application are the same as those of the first invention of the present application. Next, a preferable configuration will be described.

“Yield ratio σ _0.5 / σ is 0.850 ≦ σ _0.5 /σ≦0.985”
In secondary processing such as corrugation processing and dimple processing, processing may be performed with a cored bar inserted in order to ensure a flow path for water. When the yield ratio σ _0.5 / σ obtained as a ratio of the proof stress value σ _0.5 and the tensile strength σ is within a certain range, the spring back of the material after processing can be used, and the core metal is copper. This is preferable because the metal core is not squeezed in the alloy tube and the cored bar is easily removed. If the proof stress σ _0.5 is less than a certain value and the yield ratio σ _0.5 / σ is less than 0.850, the processed copper tube will be squeezed into the core bar, causing a problem that the core bar will not come off. It becomes easy. If the yield ratio σ _0.5 / σ exceeds 0.985, the spring back at the time of secondary processing becomes large, and the necessary dimensions may not be ensured.

  The copper alloy tubes of the first and second inventions of the present application can be internally grooved tubes in which spiral grooves having a constant twist angle are formed on the inner surface.

  Next, a method for manufacturing the above-described copper alloy tube will be described. As an annealing method that promotes concentration to the surface where the additive element works effectively and does not grow crystal grains, for example, reducing gas mixed with 2% by volume of carbon monoxide, 4% by volume of hydrogen and 93.999% by volume of nitrogen. Or in a gas atmosphere in which 40 ppm of oxygen is mixed with an inert gas of 99.999% nitrogen, the temperature of the atmosphere is set to 450 to 550 ° C., and the heating time is set to 20 to 600 minutes. can do. Alternatively, according to the heat treatment at a high temperature and in a short time, the annealing can be performed without growing the crystal grains while promoting the concentration action on the surface where the additive element works effectively. Specifically, in the same gas atmosphere as described above, the heating voltage is selected so that the workpiece temperature becomes 700 to 950 ° C. by the high frequency induction heating method or the current heating method, and the heating time is 1 to 30 seconds. Heat treatment is possible. According to this method, since the copper alloy tube material can be softened to a certain degree of hardness without coarsening the crystal grains, the secondary processing described above can be performed without causing non-uniform concentration of the additive elements on the surface. Even if it does, the favorable workability can be ensured.

  Furthermore, if the material requires a certain degree of hardness in the above-described processing, the crystal grain size can be reduced unnecessarily by performing another drawing step with a processing rate (section reduction rate) of about 10 to 20%. However, the strength can be improved by work hardening. Corrugation is a process that requires a certain degree of hardness in this material. In this corrugating process, three spiral grooves (helical peaks on the surface) are formed while pressing a rolling disk from three directions, for example, in a direction perpendicular to the tube axis and rotating the planet. At this time, if the tempering of the material is too soft, the material will bend when the disc is pressed against the material, and if you proceed with processing, the material will swell and you will not be able to process it in the middle Occurs.

  Next, test results for demonstrating the effects of the present invention will be described. First, a method for measuring the distribution in the depth direction in the vicinity of the surface of the base material of the additive element will be described. This distribution in the depth direction can be performed by GD-OES analysis (Glow Discharge Optical Emission Spectrometry).

  GD-OES (Glow Discharge Optical Emission Spectrometer) is the latest analyzer that can analyze the region from several tens of μm deep region to the extreme surface (several nm to several tens of nm) in a short time. is there. Since the analyzer uses light emission, it has high sensitivity and can analyze light elements such as H, C, N, and O.

  The atomic concentration was measured with a GD-OES apparatus (GD-PROFILER 2 type GD-OES manufactured by Horiba), and the obtained mass concentration was measured in advance using standard samples (C: 0.403 mass% and 0.837 mass%, O: 47.07 mass%, P: 0.0044 mass% and 0.0595 mass%, Cu: 0.36 mass% and 99.99 mass%, Zr: 0.0029 mass% and 0.0051 mass%, (Sn: 0.0067 mass% and 0.0041 mass%) atomic concentration and mass concentration are converted into atomic concentrations.

  The measurement depth was measured with a GD-OES apparatus (GD-PROFILER 2 type GD-OES manufactured by Horiba), and the sputter time obtained was measured with a pre-measured standard sample sputter time and a surface roughness meter. Convert to measurement depth by crater depth. Note that a surface roughness meter calibrated with a step standard sample (9090 ± 5%) is used.

The analysis conditions using a GD-OES apparatus (GD-PROFILER type 2 GD-OES manufactured by Horiba) are as follows.
Analysis mode: Normal sputter anode diameter (analysis area): φ4mm
Discharge power: 35W
Ar gas pressure: 600 Pa

  GD-OES analysis was performed using the GD-OES apparatus. First, it contains 0.06% by mass of P, 0.03% by mass of Zr and 0.66% by mass of Sn, and the balance is composed of Cu and inevitable impurities, the outer diameter is 12.7 mm, A copper alloy tube (tempered 3 / 4H material) having a wall thickness of 0.8 mm and a length of 50 mm was produced. The material drawn to the specified size is mixed with a reducing gas containing 2% by volume of carbon monoxide, 4% by volume of hydrogen and 93.999% by volume of nitrogen in an induction heating furnace with 40ppm oxygen. In the atmosphere, after annealing at a constant heating voltage output, drawing was performed at a predetermined processing rate (cross-sectional reduction rate) so that a tempered material having a tensile strength of 350 MPa was obtained. The average crystal grain size of the copper alloy tube is obtained by vertically dividing the tube so that a cross section passing through the tube axis appears. After the cross section including this tube axis is polished to a mirror surface, a crystal structure appears by etching. Observe, JIS H0501-6. When evaluated by a comparative method, it was 10 μm.

Further, after the copper alloy tube was divided in half in the tube axis direction, the copper tube was flattened using a hydraulic press, and the inner surface of the tube was subjected to analysis to perform GD-OES analysis. The analysis results are shown in FIGS. Designated elements for GD-OES analysis were Cu, P, Sn and Zr. FIG. 1 shows the analysis result of P, FIG. 2 shows the analysis result of Sn, and FIG. 3 shows the analysis result of Zr. 1 to 3, rising of P concentration, Sn concentration and Zr concentration is recognized from a portion having a depth of about 200 to 250 nm to the outermost surface, and the maximum value X _{peak of the} mass concentration recognized from the outermost surface to a depth of 250 nm is observed. X is an element symbol of each additive element. P was 16.03 mass%, Sn was 2.72 mass%, and Zr was 0.081 mass%. The average concentration X ₂₀₀₀ at a depth of 1900 to ₂₀₀₀ nm (X is an element symbol of each additive element) was 0.062 mass% for P, 0.66 mass% for Sn, and 0.029 mass% for Zr. . At this time, the difference between the X _peak and the X ₂₀₀₀ was 15.96 mass% for P, 2.06 mass% for Sn, and 0.052 mass% for Zr, respectively. In this way, the element distribution from the surface of the copper alloy tube can be obtained.

Hereinafter, in order to demonstrate the effect of the present invention, the characteristics of the examples of the present invention will be described in comparison with comparative examples that are out of the scope of the present invention. Difference between X _peak and X ₂₀₀₀ (X: various additive elements) read from GD-OES analysis, X _peak −X ₂₀₀₀ value is more than the value specified for each element, ○, less than specified value In the case of, “x” is indicated, and the result is described in the column of the reading value from the GD-OES analysis result of each element.

  The measuring method of the crystal grain size is JIS H0501-6. Relying on comparative methods.

<Scale adhesion evaluation method>
The scale adherence evaluation method uses a commercially available eco-cute machine system for home use, and the actual machine for about 6 months using tap water from Hadano City, Kanagawa Prefecture, which is actually easy to attach scale and has a relatively high water quality. Driving was carried out. Table 1 below shows the results of water quality analysis of Hadano City water used for evaluation.

  Commercially available EcoCute is divided into a tank unit and a heat pump unit. For evaluation, tap water is not directly passed through the tank unit, but piped directly to the heat pump unit. The operating conditions were set by computer control.

  A self-made double pipe heat exchanger was manufactured in the heat exchanger part, and water flow and refrigerant piping were changed so that a heat exchanger could be arranged outside the heat pump unit body. In addition, water and refrigerant pipes were connected by mechanical joints so that the heat exchanger could be replaced for each test, and high airtight and high pressure resistant valves were provided where necessary.

  The heat exchanger has a double-pipe structure with a total length of 15 m in which an inner tube with an outer diameter of 12.7 mm and a wall thickness of 1.5 mm is inserted into an outer tube with an outer diameter of 15.88 mm and a wall thickness of 1.0 mm. This is a double pipe heat exchanger. The refrigerant was passed through the annular part between the outer pipe and the inner pipe of the double pipe heat exchanger, and the test water was passed through the inner pipe. The characteristics of the inner tube, which becomes the wetted part to which the scale adheres, were evaluated as test materials for Examples and Comparative Examples.

  The driving pattern was controlled by a timer. The operation was continued for a fixed time of 8 hours per day and continued for 180 days (6 months).

  The evaluation method of the amount of scale adhesion was performed by weight measurement before and after the test of the double pipe heat exchanger. Before the test, the weight was measured in a state before being connected to the heat pump unit, and after connecting and carrying out the test, the weight was measured again after being removed and sufficiently dried. The difference in weight before and after the test was evaluated as the amount of scale attached during the test.

  For the water flow part, the above test was carried out using a pipe heat exchanger manufactured using a phosphorus deoxidized copper pipe (JIS H3300 C1220) annealed material. When the amount of scale attached was measured, it was about 300 g. In comparison with this water flow part, the scale adhesion amount of the copper alloy pipe of the example of the present invention and the comparative example was evaluated, and the case where the scale adhesion quantity was 100 g or less (1/3 or less) of the water flow part. Effective (O), and the case of exceeding 100 g (exceeding 1/3) was regarded as insufficient effect (x).

<Workability evaluation test 1>
Corrugation processing was performed using the copper alloy tube test materials (outer diameter 12.7 mm, wall thickness 0.8 mm, length 3000 mm) of Examples and Comparative Examples, and the workability was evaluated. In the rolling process, the rotating specimen was excessively deformed to cause crushing or undulation of the tube, causing fluttering and sag, and the processing could not be continued. When the rolling process was completed to the end, it was judged by the shape survey whether the corrugated peak on the inner surface of the pipe had come out as specified. The specifications of the corrugated pipe to be manufactured are as shown in Table 2 below. The processed specimen was halved in the tube axis direction, embedded in resin, polished to # 2000 with emery paper, the tube axis parallel section was observed, and the dimensions of the corrugated portion were measured using an optical microscope. . In the machining process work, when the adjustment was within the range of the dimensional tolerance shown in the specification, a “good” judgment was made, and when the adjustment was not made within the dimensional tolerance range shown in the specification, a “poor” judgment was made.

<Workability evaluation test 2>
Corrugation processing was performed using the copper alloy tube test materials (outer diameter 12.7 mm, wall thickness 0.8 mm, length 3000 mm) of the same example and comparative example as the processing evaluation test 1. Before starting corrugating, corrugating was performed in a state where the inner diameter was limited by putting a core metal made of S45C steel with a thickness of 10.1 mm into the test material. In the range where force is applied to the extent that the test material is not subject to excessive deformation, ○ if the metal core is pulled out, x if the metal core is not pulled out if force is not applied to the extent that the test material is deformed. Judged.

“Test Example 1”
First, the test results of the first invention will be described. Table 3 below shows the composition and annealing conditions of the copper alloy tube. Table 4 below shows the GD-OES analysis results, average crystal grain size, tensile strength, scale adhesion test results, and corrugation processing test results of this copper alloy tube. Note that IH of the heating means is heat-annealed by induction heating, and RH is heat-annealed by atmosphere heating.

  As shown in Tables 3 and 4, Comparative Example 1 is a conventional JIS H3300C1220 alloy, which has a large amount of scale adhesion. In Comparative Example 2, the crystal grain size was large and the tensile strength was low. Moreover, since the component composition of Comparative Examples 3 to 5 deviates from the scope of the present invention, the amount of scale adhesion is large, and Comparative Example 8 has a corrugated processing test result because the crystal grains are coarsened. Concentration was insufficient and the amount of scale adhered was large. In Comparative Examples 11, 14, and 15, since the crystal grains became coarse, the corrugation processing test result was x. Since the comparative example 16 was too high in tensile strength, a predetermined shape could not be obtained in corrugating.

  On the other hand, in Examples 6, 7, 10, 12, and 13 of the present invention, the adhesion amount of the scale was small and the result of the corrugation processing test was also good.

  Next, the test results of the second invention of the present application will be described. Table 5 below shows the composition and annealing conditions of the copper alloy tube. Table 6 below shows the GD-OES analysis results, average crystal grain size, tensile strength, scale adhesion test results, and corrugation processing test results of this copper alloy tube.

  As shown in Tables 5 and 6, all of Examples 17 to 28 that satisfy the condition of claim 2 of the present application had a small amount of scale adhesion, and the result of the corrugation processing test was also good (◯). In Tables 5 and 6, Examples 7, 10, 12, and 13 of the first invention of Table 3 and Table 4 are also shown for comparison.

  Next, examples and comparative examples of the yield ratio of claim 3 of the present application will be described. Table 7 below shows the composition and annealing conditions of the copper alloy tube. Table 8 below shows GD-OES analysis results, average crystal grain size, tensile strength, scale adhesion test results, and corrugation processing test results of this copper alloy tube. In Tables 7 and 8, Comparative Examples 2 and 16 and Examples 6, 7, 10, 12, and 13 in Tables 3 and 4 are also shown for comparison of the yield ratio. The comparative example 34 is the same composition as the comparative example 2, Comprising: The annealing conditions were changed from the conditions of Table 1. In Comparative Examples 2 and 34, Example 6 and Examples 29 to 33, the yield ratio deviated from the range defined in claim 3 of the present invention, so that there was a problem that the cored bar could not be removed in the corrugating test. In Examples 6, 7, 10, 12, and 13, the yield ratio satisfied Claim 3, so the results of the corrugating test were also good. On the other hand, although Examples 29-33 satisfy | filled Claim 1, since the yield ratio of Claim 3 was not satisfy | filled, the result of the corrugation processing test containing a metal core was x. However, Examples 29 to 33 also have a small amount of scale and satisfy the effect of claim 1 of the present application.

  As described above, the copper alloy tube of the example satisfying the first, second, or third aspect of the present invention has excellent resistance to scale adhesion, and has excellent characteristics as a copper alloy heat transfer tube for a water flow tube. In addition, when the yield ratio is in a predetermined range, good processing characteristics are obtained even in corrugated processing with a cored bar.

Claims (4)

Sn: 0.05 to 3.0% by mass,
P: 0.004 to 0.2% by mass,
Zr (contained as solid solution, simple substance and / or compound in matrix): 0.005 to 0.2% by mass (in the case of compound, converted to Zr)
Containing
A copper alloy tube having a composition in which the balance is made of Cu and inevitable impurities,
The difference P _peak -P ₂₀₀₀ between the maximum value P _peak of the mass ratio of P from the outermost surface of the copper alloy tube to a depth of 250 nm and the average concentration P ₂₀₀₀ of P at a depth of 1900 to ₂₀₀₀ nm is determined by glow discharge luminescence surface analysis. 0.50 mass% or more and 25 mass% or less,
Difference between the maximum value Sn _peak of Sn mass from the outermost surface of the copper alloy tube to a depth of 250 nm and the average Sn concentration Sn ₂₀₀₀ at a depth of 1900 to ₂₀₀₀ nm by the glow discharge luminescence surface analysis Sn _peak −Sn ₂₀₀₀ Is 0.30 mass% or more and 15 mass% or less,
Difference _Zr peak _{-Zr 2000} the average density _{Zr 2000} of Zr in maximum _{Zr peak} and depth 1900~2000nm the weight ratio of Zr to a depth of 250nm from the outermost surface of the copper alloy tube according to the glow discharge emission surface analysis Is 0.010 mass% or more and 3.0 mass% or less,
The average grain size is 5-25 μm,
Tensile strength σ is 260 to 450 MPa
A copper alloy tube characterized by Sn and at least one element selected from the group consisting of Zn and Al: the total value is 0.05 to 3.0% by mass , and the ratio of Sn in Sn, Zn and Al is 77.5% that's all,
P: 0.004 to 0.2% by mass,
Zr (contained as solid solution, simple substance and / or compound in matrix): 0.005 to 0.2% by mass (in the case of compound, converted to Zr)
Containing
A copper alloy tube having a composition in which the balance is made of Cu and inevitable impurities,
The difference P _peak -P ₂₀₀₀ between the maximum value P _peak of the mass ratio of P from the outermost surface of the copper alloy tube to a depth of 250 nm and the average concentration P ₂₀₀₀ of P at a depth of 1900 to ₂₀₀₀ nm is determined by glow discharge luminescence surface analysis. 0.50 mass% or more and 25 mass% or less,
With respect to at least one selected element selected from the group consisting of Sn and Zn and Al, the total of the Sn and selected elements from the outermost surface of the copper alloy tube to a depth of 250 nm by the glow discharge luminescence surface analysis. The difference SZA _peak -SZA ₂₀₀₀ between the maximum value SZA _peak of the mass ratio and the average concentration SZA ₂₀₀₀ of the Sn and the selected element at a depth of 1900 to ₂₀₀₀ nm is 0.30% by mass or more and 15% by mass or less.
Difference _Zr peak _{-Zr 2000} the average density _{Zr 2000} of Zr in maximum _{Zr peak} and depth 1900~2000nm the weight ratio of Zr to a depth of 250nm from the outermost surface of the copper alloy tube according to the glow discharge emission surface analysis Is 0.010 mass% or more and 3.0 mass% or less,
The average grain size is 5-25 μm,
Tensile strength σ is 260 to 450 MPa
A copper alloy tube characterized by The ratio (yield ratio) σ _0.5 / σ of the proof stress σ _0.5 and the tensile strength σ is 0.850 ≦ σ _0.5 /σ≦0.985, wherein: A copper alloy tube according to 1. The copper alloy tube according to any one of claims 1 to 3, wherein the copper alloy tube is an internally grooved tube having a plurality of grooves formed on an inner surface.

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