JP5639025B2 - Copper alloy tube - Google Patents

Description

  The present invention relates to a copper alloy tube that prevents melting cracks due to heating during brazing of a copper alloy tube for piping and a copper alloy tube for heat exchanger.

  Phosphorus deoxidized copper pipe (JISH3300C1220T) is widely used in room air conditioners, packaged air conditioners, carbon dioxide refrigerant heat pump water heaters, refrigerators, showcases, heat exchangers such as vending machines, and in-machine piping and parts around compressors. It is used.

  For example, a heat exchanger of a room air conditioner uses a U-shaped copper tube bent into a hairpin shape (hereinafter referred to as a copper tube including a copper alloy tube) through a through-hole of an aluminum fin, and the copper tube is used with a jig. By expanding the pipe, the copper pipe and the aluminum fin are brought into close contact with each other, the open end of the copper pipe is further expanded, and a copper return bend pipe bent into a U-shape is inserted into the expanded section, and a brazing material such as phosphor copper braze The heat exchanger is manufactured by joining the expanded pipe part and the return bend pipe by connecting the hairpin-shaped copper pipe and the return bend pipe.

  In addition, in the in-machine piping connecting the compressor and the heat exchanger, a material obtained by arbitrarily bending a copper pipe is prepared, and if necessary, the pipe end is expanded or contracted, and the compressor and the heat exchanger are The room air conditioner is assembled by connecting with in-machine piping with brazing material such as phosphor copper brazing.

  On the other hand, HCFC (hydrochlorofluorocarbon) -based fluorocarbons have been widely used as refrigerants for room air conditioners and the like, but HCFC has a high ozone depletion coefficient, so HFC has a small value from the viewpoint of environmental protection. (Hydrofluorocarbon) fluorocarbons have been used. Furthermore, carbon dioxide, which is a natural refrigerant that is more environmentally friendly than HFC, has been used in heat pump water heaters and vending machines. For example, the design pressure of the refrigerant gas specified in the high pressure gas safety law refrigeration safety rule related example standard is 1.6 MPa in the HCFC R22 when the standard condensation temperature of the high pressure part is 43 ° C. HFC R410A increases to 2.6 MPa and carbon dioxide increases to 8.3 MPa.

  If the design pressure increases, it is necessary to increase the thickness of the copper tube of the heat exchanger or in-machine piping so that it can withstand the strength. However, from the viewpoint of effective use of resources and from the viewpoint of cost, there is a problem with increasing the thickness of the copper tube and increasing the amount of copper used. In order to solve this problem, a high-strength copper tube whose strength is increased by adding Sn, Co, etc., instead of the conventional phosphorous-deoxidized copper tube, has been developed and put on the market. This high-strength copper pipe has higher strength than conventional copper pipes, and accordingly, the thickness can be reduced, and the amount of copper used can be reduced, saving resources and reducing product costs. it can. In addition, this high-strength copper pipe is additionally registered in the Japanese Industrial Standard JISH3300 (July 20, 2009), and is expected as a new material to replace the conventional phosphorous deoxidized copper pipe.

For example, the applicant of the present application described in Patent Document 1 includes Sn: 0.1 to 1.0 mass%, P: 0.005 to 0.1 mass%, O: 0.005 mass% or less, and H: 0.00. A copper tube for a heat exchanger was proposed, which contains 0002 mass% or less, the balance being Cu and inevitable impurities, and an average crystal grain size of 30 μm or less. Further, the applicant of the present application described in Patent Document 2 is Sn: 0.1 to 2.0 mass%, P: 0.005 to 0.1 mass%, S: 0.005 mass% or less, O: 0.0. 005% by mass or less and H: 0.0002% by mass or less, with the balance being composed of Cu and unavoidable impurities, with a tensile strength of 255 N / mm ² or more, A copper alloy tube having an average crystal grain size measured in the direction perpendicular to the thickness direction of 30 μm or less, wherein the tensile strength of the copper alloy tube is αa, the breaking pressure is PFa, the same outer diameter as the copper alloy tube, and A copper alloy tube for a heat exchanger was proposed, where (PFa) / (σa)> (PFd) / (σd) where αd is the tensile strength of the thick phosphorous deoxidized copper tube and PFd is the breaking pressure.

JP 2003-268467 A JP 2008-174785 A

  However, although the copper alloys disclosed in Patent Document 1 and Patent Document 2 achieve their intended purpose and the strength is improved by solid solution strengthening of Sn, the pipes and the like are brazed with phosphor copper brazing. On the other hand (800 to 950 ° C.), if a tensile stress is applied, a crack may occur very rarely.

  There are two types of embrittlement cracking in copper alloy pipes during brazing: brittle cracking due to a decrease in ductility (elongation, squeezing) of copper alloy pipes at high temperatures and melting cracking due to melting of grain boundaries in copper alloy pipes at high temperatures is there. It is estimated that embrittlement cracking occurs by the following mechanism. In other words, Cu-Sn-based high-strength copper tubes have a lower ductility than phosphorous-deoxidized copper at temperatures of 800 ° C. or higher, and therefore can be sufficiently deformed when a tensile stress is applied. It is thought that it is not possible to lead to a crack. The applicant of the present application has applied for a copper alloy tube that prevents this embrittlement crack (Japanese Patent Application No. 2010-080825).

  On the other hand, if the temperature is higher than 950 ° C. during brazing, there is a risk that melt cracking may occur in the copper alloy tube in the temperature range from 950 ° C. to just below the melting point. When the Cu—Sn based copper alloy tube is heated to a temperature exceeding 950 ° C., the grain boundary is melted at a temperature lower than that of the phosphorous deoxidized copper, and is likely to be melted.

  Under such special circumstances, measures such as changing the manufacturing process so that tensile stress is not applied or adjusting the heating power during brazing for each pipe shape are realistic from the viewpoint of productivity. is not.

  The present invention has been made in view of such problems, and reduces the possibility of melting cracks even when heated excessively to a temperature exceeding 950 ° C. during heating such as brazing. An object of the present invention is to provide a copper alloy tube.

The copper alloy tube according to the present invention has Sn: 0.1 to 1.0% by mass, P: 0.001 to 0.100% by mass, Zr: 0.01 to 0.30% by mass , S: 0.0003. To 0.0020% by mass and Al: 0.0001 to 0.0050 % by mass , O : 0.0050% by mass or less, H: 0.0002% by mass or less, the remainder being Cu and inevitable impurities A copper alloy tube material having a composition comprising: a cross-section including a tube axis, wherein an average crystal grain size in a thickness direction is 30 μm or less, and a drawing value at 1000 ° C. is 20% or more. To do.

  Furthermore, each above-mentioned copper alloy tube can be used for a heat exchanger.

  The average crystal grain size is determined by measuring the average crystal grain size in the thickness direction by a cutting method defined in JISH0501 in the cross section including the pipe axis of the copper alloy. It is measured at 10 points at 100 mm intervals in the direction, and the average value is obtained.

  According to the present invention, the possibility of melting cracks can be remarkably reduced even when excessively heated to a high temperature exceeding 950 ° C. during brazing with phosphor copper brazing.

It is a schematic diagram which shows the method of a crack test.

  Hereinafter, the present invention will be described in detail. As a result of various experiments conducted by the present inventors to develop copper alloy tubes for heat exchangers that can improve ductility and toughness (drawing value, elongation) at high temperatures and prevent melting cracks, the Sn content of copper alloy tubes By appropriately defining the amount, P content, Zr content, Al content and other alloy element content, and the average crystal grain size, melting cracks when heated to an excessively high temperature were prevented. It has been found that a copper alloy tube can be obtained.

  Hereinafter, the reason for adding components and the reason for limiting the numerical values of the composition of the copper alloy tube of the present invention will be described.

“Sn: 0.1 to 1.0 mass%”
Sn improves the tensile strength by solid solution hardening and suppresses the coarsening of crystal grains against the thermal effects of brazing such as phosphor copper brazing, thereby improving the heat resistance of the copper alloy tube. However, it has been found that when heated at high temperatures, the Sn-containing alloy shows a decrease in ductility at high temperatures as the Sn content increases. The mechanism by which Sn lowers the high temperature ductility is not clear, but it seems that cracking has occurred by reducing the strength or ductility of the grain boundaries at or near the grain boundaries at high temperatures. When the Sn content exceeds 1.0% by mass, the ductility drop at high temperatures becomes large, and solidification segregation in the ingot becomes severe, and segregation is not completely eliminated by normal hot extrusion and / or processing heat treatment. In some cases, the structure, mechanical properties, bending workability of the copper alloy tube, unevenness of the structure and mechanical properties after brazing, deterioration of corrosion resistance, and the like are caused. Moreover, when Sn content exceeds 1.0 mass%, a required extrusion pressure will become high, and when it is going to extrude with the same extrusion pressure as a copper alloy whose Sn content is 1.0 mass% or less, extrusion temperature , Thereby increasing the surface oxidation of the extruded material, reducing the productivity and increasing the surface defects of the copper alloy tube. Further, when the Sn content in the copper alloy of the present invention is less than 0.1% by mass, it becomes impossible to obtain sufficient tensile strength and fine crystal grain size after annealing and brazing heating. The effect of suppressing strength reduction during brazing heating with copper brazing and the like and the effect of preventing grain coarsening will be insufficient. Therefore, it is necessary that the Sn content be 0.1 to 1.0 mass%.

“P: 0.001 to 0.100 mass%”
P, like Sn, reduces the hot ductility of the copper alloy tube, and promotes the reduction of hot ductility due to Sn. When the P content exceeds 0.100% by mass, the ductility drop of the copper alloy of the present invention becomes particularly high, the electrical conductivity is lowered, and hot workability and cold workability are hindered. . On the other hand, when the P content is less than 0.001% by mass, the predetermined strength cannot be obtained, and deoxidation becomes insufficient, and the oxide is caught in the ingot, and the soundness of the ingot is lowered. At the same time, the bending workability of the manufactured pipe tends to decrease. Therefore, it is necessary to make the P content 0.001 to 0.100 mass%.

“Zr: 0.01 to 0.30 mass%”
When brazing pipes or the like with phosphor copper brazing, the brazing temperature is usually 800 to 950 ° C. If this pipe or the like is carelessly heated to a temperature exceeding 950 ° C., the material In the case of a Cu—Sn-based copper alloy tube, the Sn concentration in the crystal grain boundary is higher than in the crystal grain, so the melting point of the grain boundary is lower than in the grain, and as a result, the grain boundary melts first. Can not support the stress. This is the phenomenon of melting and cracking.

  This melting crack can be remarkably reduced by adding Zr to the Cu—Sn based copper alloy tube. The mechanism by which the occurrence of melting cracks is reduced is not clear, but when the temperature rises due to brazing heating in a state where stress is applied, even if the ultimate temperature does not exceed 950 ° C., a Cu—Sn based copper alloy that does not contain Zr In the tube, the stress acting on the grain boundary exceeds the strength of the grain boundary, and fracture occurs. On the other hand, it is presumed that the inclusion of Zr improves the grain boundary strength or develops a phenomenon such as relaxation of stress concentration near the grain boundary. As a result, the starting point of cracks at the grain boundaries is reduced, cracks are suppressed at temperatures below 950 ° C., and stress near the grain boundaries is reduced even when the heating temperature exceeds 950 ° C. The occurrence of melting cracks is greatly reduced. Thus, by appropriately setting the content of Zr, not only cracking when heated to less than 950 ° C. but also melting cracking due to excessive heating exceeding 950 ° C. can be prevented. For this purpose, it is necessary to add 0.01 to 0.30 mass% of Zr. When Zr is less than 0.01% by mass, there is an effect of recovering ductility at 800 to 950 ° C., and there is an effect for preventing cracking at less than 950 ° C., but sufficient countermeasures for melt cracking when the temperature exceeds 950 ° C. It will not be. Therefore, in order to stably prevent melting and cracking, it is necessary to add 0.01% by mass or more of Zr. On the other hand, when the Zr content exceeds 0.30% by mass, a coarse crystallized product of Zr is generated, and the bending workability of the tube is lowered. Therefore, the Zr content is set to 0.01 to 0.30 mass%.

“Al: 0.0001 to 0.0050 mass%”
S, which is an inevitable impurity, has a low melting point, and even a trace amount is concentrated at the grain boundary to lower the strength of the grain boundary and promote embrittlement of the copper alloy tube at a high temperature. Al has an action of separating and removing S as a stable Al sulfide (Al ₂ S ₃ or the like) during melting in the melting and casting process. In addition, Al has the effect of detoxifying S that still exists at the grain boundary as a stable Al sulfide (Al ₂ S ₃ or the like) in the subsequent heat treatment step. If the Al content is less than 0.0001% by mass, the effect of separating and removing S is not sufficient, S remains in the ingot, promotes embrittlement of the material at high temperature, Cause cracking during processing. On the other hand, if the Al content exceeds 0.0050% by mass, the decrease in conductivity increases, and the inclusion of Al oxide causes surface flaws in the alloy tube, resulting in a decrease in bending workability. Degrading properties. Therefore, the Al content is 0.0001 to 0.0050 mass%.

“S: 0.0020 mass% or less”
Since S does not dissolve, it is easy to concentrate at the grain boundary and has a low melting point, so that the strength of the grain boundary is remarkably lowered and the ductility of the copper alloy of the present invention at high temperature is lowered. S is present in the matrix by forming a compound with Cu in the copper alloy of the present invention. When the S content increases, ingot cracking during casting and hot extrusion cracking in the hot extrusion process increase. Also, even if hot extrusion cracking does not occur, when the extruded material is cold-rolled and drawn, the Cu-S compound inside the material expands in the axial direction of the tube and cracks occur at the interface of the Cu-S compound. In the product during and after the product processing, surface flaws, cracks, etc. occur and the product yield is reduced. Moreover, even when a crack does not generate | occur | produce at a Cu-S compound interface, when bending the copper alloy pipe | tube of this invention, it becomes a starting point of a crack generation and the frequency that a crack generate | occur | produces in a bending part becomes high. In order to improve such a problem, it is necessary to regulate the S content in the copper alloy of the present invention to 0.0020% by mass or less, desirably 0.0010% by mass or less.

  S is relatively easy from copper bullion and raw materials such as scrap, oil adhering to scrap, melting casting atmosphere (charcoal / flux covering molten metal, SOx gas in furnace atmosphere, furnace material, etc.) In order to make the S content 0.0020% by mass or less because it is taken into the molten metal, the amount of low-grade Cu ingot and scrap is reduced, the SOx gas in the melting atmosphere is reduced, and an appropriate furnace It is effective to select a material and add a trace amount of an element having strong affinity for S, such as Mg and Ca, to the molten metal.

“O: 0.0050 mass% or less (50 ppm or less)”
In the copper alloy tube of the present invention, Zr is added as an element that suppresses melting cracking. However, if the Zr is oxidized, the effect of adding Zr disappears. For this reason, O is made into 0.0050 mass% or less. On the other hand, if the O content exceeds 0.0050% by mass, oxides of Cu and Sn are entrained in the ingot, reducing the soundness of the ingot, and reducing the bending workability of the manufactured pipe. It becomes easy. Moreover, when content of O exceeds 0.0050 mass%, the danger of causing hydrogen embrittlement will increase. For this reason, it is necessary to make content of O into 0.0050 mass% or less. In order to further improve the bending workability, the O content is desirably 0.003% by mass or less, and more desirably 0.0015% or less.

“H: 0.0002 mass% or less (2 ppm or less)”
When more hydrogen is taken into the molten metal at the time of melting and casting, the hydrogen collects at the grain boundary, and it becomes easy to promote a decrease in ductility at high temperatures. Further, when the amount of hydrogen taken into the molten metal increases, pinholes are likely to be generated, and when hydrogen is concentrated in the grain boundary and present in the ingot, cracks during hot extrusion are likely to occur. If hydrogen is excessive, blistering due to hydrogen tends to occur at the grain boundaries during annealing even after extrusion, resulting in a decrease in product yield. For this reason, in the copper alloy pipe | tube of this invention, it is necessary to make content of H 0.0002 mass% or less. In order to further improve the product yield, the H content is desirably 0.0001% by mass or less.

  In addition, in order to make the H content 0.0002% by mass or less, the raw material at the time of melting and casting is dried, the molten metal is heated red, and the dew point of the atmosphere in contact with the molten metal is kept low. It is effective to take measures such as making the molten metal before adding phosphorus and oxidizing.

“Crystal grain size: average crystal grain size is 30 μm or less”
The grain size plays an important role in the strength of the material and workability such as bending. Generally, if the crystal grain size is small, the strength is high and the bending workability is improved. When the crystal grain size is large, the strength is lowered. When the crystal grain size exceeds 30 μm, the strength decreases, the pressure resistance when incorporated in a heat exchanger such as an air conditioner becomes insufficient, and the strength after brazing cannot be sufficiently maintained. Therefore, the average crystal grain size is preferably 30 μm or less, more preferably 15 μm or less.

  In a state where tensile stress is applied at a high temperature, a smaller crystal grain size is advantageous for suppressing a decrease in hot ductility. In the alloy of the present invention, the crystal grain size after heating at 800 ° C. for 10 minutes is desirably 70 μm or less.

“Aperture value at 1000 ° C is 20% or more”
Aperture at 1000 ° C., which corresponds to the filtrate cormorants with temperature is less than 20%, when the tensile stress at the time of brazing is applied, it was found that there is a risk of cracking may occur. For this reason, the aperture value at 1000 ° C. needs to be 20% or more. It is more desirable that the aperture value at 900 ° C. is 25% or more and the aperture value at 950 ° C. is 20% or more. Even when the copper alloy pipe of the present invention is used for piping of a heat exchanger or the like and brazed in a state where tensile stress is applied, the drawing value at 1000 ° C. is 20% or more. The ductility at a high temperature is extremely excellent, and cracking can be prevented even when heated to a high temperature exceeding 850 ° C. The term “drawing” refers to a ratio obtained by dividing the cross-sectional area of the fractured portion after the tensile test of the pipe by the cross-sectional area before the test. The higher this value, the higher the ductility.

  Hereinafter, an example of the manufacturing method of the copper alloy pipe of the present invention will be described. The manufacturing method shown below is for a smooth tube, but in the case of an internally grooved tube, a well-known internal grooved process is added.

  First, the raw electrolytic copper is dissolved under the charcoal coating. After the copper is dissolved, a predetermined amount of Sn and necessary additional elements are added. Add P. At this time, it is desirable that an additive element such as Zr that is easily oxidized be added as an intermediate alloy in order to add a predetermined amount uniformly and appropriately. After the component adjustment is completed, a billet having a predetermined size is produced by semi-continuous casting. The obtained billet is heated in a heating furnace and homogenized. Prior to hot extrusion, the billet is held at 750 to 950 ° C. for about 1 minute to 2 hours to improve segregation by homogenization. Thereafter, the billet is perforated by piercing and hot extruded at 750-950 ° C.

  In order to manufacture the copper alloy tube of the present invention, it is an essential requirement to suppress subsequent segregation of Sn by eliminating Sn segregation or by dissolving Zr after extrusion. For this reason, the cross-sectional reduction rate by hot extrusion is 88% or more, preferably 93% or more, and the raw tube after hot extrusion is cooled to a surface temperature of 300 ° C. by a method such as water cooling. It is preferable to cool so that the speed is 10 ° C./second or more, desirably 15 ° C./second or more, and more desirably 20 ° C./second or more. However, the cross-sectional reduction rate is determined as [drilled billet donut area-cross-sectional area of raw tube after hot extrusion] / [drilled billet donut area] × 100%.

  Thereafter, the extruded element tube is rolled. By setting the processing rate at this time to 92% or less in terms of the cross-section reduction rate, product defects during rolling can be reduced. Subsequently, the rolling raw tube is subjected to a drawing process to manufacture a raw tube having a predetermined size. Usually, drawing is performed using a plurality of drawing machines, but surface defects and internal cracks in the raw pipe can be reduced by reducing the processing rate (cross-sectional reduction rate) by each drawing machine to 35% or less. .

  If necessary, the drawing tube is annealed. In order to manufacture the copper alloy tube of the present invention, the body temperature of the drawing tube is heated to 400 to 700 ° C. by continuous annealing with a roller hearth furnace, and the temperature is maintained for about 10 minutes to 1 hour. It is desirable to anneal. Moreover, it is desirable to heat so that the average rate of temperature increase from room temperature to a predetermined temperature is 5 ° C./min or more, preferably 10 ° C./min or more. In place of the continuous annealing by the roller hearth furnace, a high-frequency induction heating furnace may be used to perform rapid heating, rapid cooling, and short-time heating annealing.

  Next, the effect of the Example of the copper alloy of this invention is demonstrated compared with the comparative example which remove | deviates from the scope of the present invention.

  In order to obtain copper alloy materials having the compositions shown in Tables 1 to 6 in Examples 1 to 14 and Comparative Examples 1 to 9 and Conventional Example 1, Sn and Zr were added to the molten metal in which electrolytic copper was dissolved. After that, a Cu—P master alloy was added, and further Al was added to prepare a molten metal having a predetermined composition, which was cast into a billet having a diameter of 300 mm. Next, after the billet was heated to 850 to 950 ° C., the billet center was pierced, and an extruded element tube having an outer diameter of 100 mm and a wall thickness of 10 mm was produced by hot extrusion. This cross-sectional reduction rate was 90% or more. The raw tube after extrusion was rapidly cooled, and the average cooling rate up to 300 ° C. was estimated to be 20 ° C./second or more from the time from immediately after extrusion to water cooling and the surface temperature of the extruded raw tube after water cooling. The extruded element tube was rolled and drawn to produce an element tube having an outer diameter of 9.52 mm and a wall thickness of 0.80 mm. The cross-sectional reduction rate in rolling was 90% or less, and the processing rate per pass in drawing was 40% or less. In a roller hearth furnace in a reducing gas atmosphere, the drawing tube was heated to 550 to 650 ° C. (substance temperature) (average heating rate of 10 to 25 ° C./min) and held at that temperature for 30 to 80 minutes. The specimen was cooled to room temperature.

  In the evaluation test, the temperature was raised from room temperature to 1000 ° C. over 15 minutes and held for 10 minutes, and then a high-temperature tensile test was performed at that temperature to measure tensile strength, elongation, and squeeze value, respectively. The tensile strength, elongation and drawing value were calculated based on the definitions described in JISZ2241. The drawing after high-temperature tension is {(cross-sectional area of the tube before the tensile test−cross-sectional area of the fractured surface after the tensile fracture) / (cross-sectional area of the pipe before the tensile test)} × 100%, The subsequent cross-sectional area was calculated by measuring the outer diameter and thickness of the fracture surface. Further, as a crack test for simulating brazing in a state where a tensile stress was applied, a fixed load crack test shown in FIG. 1 was performed. That is, a stainless steel pipe 2 having an outer diameter of 11 mm and an inner diameter of 9.8 mm is fixed to the fixing base 1 with its axial direction horizontal, and the outer diameter is 9.52 mm as described above. A test tube 3 having a wall thickness of 0.80 mm and a length of 300 mm was inserted. The insertion length of the test tube 3 was 150 mm. As shown in FIG. 1, a 1 kg weight 4 was attached to a position 50 mm from the end of the 150 mm portion protruding from the tube 2. Then, the portion of the test tube 3 near the tube 2 was heated to about 950 to 1000 ° C. by the acetylene oxygen burner 5. The distance between the acetylene oxygen burner and the tube 2 was 5 cm. A K thermocouple was spot welded to the position where the acetylene oxygen burner hits, and the temperature of the test tube during heating was measured. Heating with an acetylene oxygen burner was adjusted to 950 ° C. in 8 to 12 seconds after heating. The weight 4 applies a tensile stress of about 20 MPa to the test tube in the heating portion of the test tube 3.

  Tables 1 and 2 below show the compositions of Examples 1 to 14, Comparative Examples 1 to 9 and Conventional Example 1 of the present invention, and Table 3 shows the crystal grain size and the high-temperature tensile test (drawing) at 1000 ° C. The measured value and the test result of the melt crack test are shown.

  As described in Table 3, in Examples 1 to 14 of the present invention, no crack was generated in the crack test. On the other hand, Comparative Examples 2, 5, and 9 each had a large amount of Sn, a small amount of Zr, and a large amount of S. Further, since Conventional Example 1 does not contain Zr, melt cracking occurred.

  Since Comparative Example 1 had a small amount of Sn, the crystal grain size was large, and sufficient strength as a high-strength copper tube could not be obtained. In Comparative Example 3, since there was little P, O increased, oxides were involved in the ingot, and many flaws occurred on the outer surface of the tube. Since Comparative Example 4 had a large amount of P, cracks occurred in the ingot. Since the comparative example 6 had many Zr, the skin of the ingot was bad and there were many wrinkles on the surface of a copper alloy tube. In Comparative Example 7, since the amount of Al was small, S was increased and the aperture value was out of the range of the present invention. In Comparative Example 8, since there was a lot of Al, an oxide was caught in the ingot, and a lot of flaws were generated on the outer surface of the pipe.

1: Fixing base 2: Tube 3: Test tube 4: Weight 5: Acetylene oxygen burner

Claims (2)

Sn: 0.1 to 1.0 mass%, P: 0.001 to 0.100 mass%, Zr: 0.01 to 0.30 mass% , S: 0.0003 to 0.0020 mass%, and Al: Copper alloy pipe material containing 0.0001 to 0.0050 mass% , O 2 : 0.0050 mass% or less, H: 0.0002 mass% or less, and the balance being composed of Cu and inevitable impurities A copper alloy tube characterized by having an average crystal grain size in the thickness direction of 30 μm or less and a drawing value at 1000 ° C. of 20% or more in a cross section including the tube axis. The copper alloy pipe according to claim 1, wherein the copper alloy pipe is used for a pipe and a heat exchanger in which brazing heating at 950 ° C. or higher is performed .

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