JP6309259B2 - Phosphorus-deoxidized copper plate excellent in brazing and press workability and method for producing the same - Google Patents

Description

  The present invention relates to a phosphorous deoxidized copper plate and a method for producing the same, and more particularly to a phosphorous deoxidized copper plate excellent in brazing and press workability suitable for use as a body part of a heat exchanger and a method for producing the same.

In a water heater or a water heater, a material having excellent thermal conductivity is used for a fin material of a heat exchanger part, a body part (casing) serving as a combustion chamber, a water pipe part, and the like. In addition to thermal conductivity, the properties required for members used in such areas include workability, heat resistance against heat applied during assembly and actual use, corrosion resistance against exposure to combustion gases, and long-term use. Phosphorus deoxidized copper and oxygen-free copper, which are durability against applied thermal fatigue, etc. and excellent in thermal conductivity and workability, are frequently used as main members.
Phosphorus deoxidized copper and oxygen-free copper are heated at a temperature of 800 ° C or higher in the brazing process with other members, so the material softens and may be deformed during the subsequent assembly process or transportation. In addition, it has been pointed out that the crystal structure is coarsened and the thermal fatigue applied during actual use is likely to cause grain boundary cracking. As another member, Patent Document 1 discloses that Ni is 1.5 to 5%. A brazing process having a composition of 0.0 wt%, Si of 0.3 to 1.0 wt%, the balance of Cu, and a weight ratio of Ni to Si (Ni / Si) of 4.5 to 5.5 A Cu—Ni—Si alloy is disclosed in which the crystal structure does not become coarse due to heating, and intergranular cracking is likely to occur.
However, as for the body that becomes the combustion chamber of the water heater, it is often used by machining (mainly pressing) a phosphorous deoxidized copper plate from the viewpoint of thermal conductivity, workability, and price. In order to reduce costs and improve reliability, a phosphorus-deoxidized copper plate having excellent brazing properties and press workability is further required.

Usually, pure copper plates such as phosphorous-deoxidized copper plates are subjected to hot rolling or hot forging of pure copper ingots, followed by cold rolling or cold forging, and then heat treatment for strain relief or recrystallization. In general, the crystal grain size is uniform and the residual stress in the crystal structure is required to be small.
In Patent Document 2, a copper slab of 99% by weight or more is heated to 800 ° C. or more, hot-worked at a processing rate of 50% or more, and then cooled to 350 ° C. or less at a cooling rate of 1 ° C./min or more. Later, by warm working at a processing rate of 5 to 80% at a temperature of 150 to 350 ° C., it is less likely to cause deformation due to the thermal effect of sputtering and thermal strain during repeated use, and brazeability with the target material An excellent backing plate material is disclosed.
In Patent Document 3, a pure copper ingot having a purity of 99.96 wt% or more is heated to 550 ° C. to 800 ° C., the total rolling rate is 85% or more, and the temperature at the end of rolling is 500 to 700 ° C. Workability with a small and uniform residual stress produced by performing rapid rolling at a cooling rate of 200 to 1000 ° C./min from the end rolling temperature to a temperature of 200 ° C. or less after the hot rolling. In particular, a pure copper plate suitable for a sputtering target material for sputtering is disclosed.

JP 9-296239 A Japanese Patent Laid-Open No. 10-110226 JP 2011-132557 A

Conventional phosphorous deoxidized copper plates, especially phosphorous deoxidized copper plates used in the body part that serves as the combustion chamber of the heat exchanger, can be said to have sufficient brazing and press workability, especially flatness after punching. There wasn't.
The present invention provides a phosphorous deoxidized copper plate that improves the above-mentioned drawbacks and is excellent in brazing and press workability, and a method for producing the same.

As a result of intensive studies, the inventors of the present invention contain 0.004 to 0.040 mass% of P, the balance is made of copper and inevitable impurities, and the crystal orientation on the plate surface is the X-ray diffraction intensity of the {200} crystal plane. Is I {200}, the X-ray diffraction intensity of the {220} crystal plane is I {220}, and the X-ray diffraction intensity of the {420} crystal plane is I {420}, I {200} / ( I {220} + I {420}) is 1.3 to 2.3, the surface roughness Ra on the plate surface is 0.1 to 0.3 μm, and the steepness on the plate surface is 0.4%. Ri der below, the absolute value of the residual stress at a depth of 1μm from the plate surface is not more than 300 MPa, the plate 0.04 g (± 0.005 g) of phosphorus copper brazing on the surface, so that flow wax BadWay direction Set temperature is 850 ° C with 2.9 ° inclination Was placed in a continuous furnace in a hydrogen atmosphere, after the continuous furnace is passed through for 20 minutes, phosphorus deoxidized copper plate distance of the phosphorus copper solder flows through the plate upper surface is greater than or equal to 16.5mm is excellent It has been found that it has brazeability and press workability.
The above-mentioned phosphorus-deoxidized copper plate is considered to have a small residual stress and a uniform distribution, and the flatness of the plate after press punching is good, and brazing at a high temperature of about 800 ° C. in a continuous furnace. In this case, the directionality of the warp of the plate due to heating is also constant, and since the surface roughness Ra is 0.1 to 0.3 μm, the directionality of the flow of the brazing material is stabilized, and other materials Exhibits excellent brazing properties.

In addition, as a result of intensive studies, the inventors of the present invention include phosphorus deoxidized copper containing 0.004 to 0.040 mass% of melt-cast P and the balance of copper and inevitable impurities, a hot rolling step, While manufacturing in the process including the cold rolling process and the finish annealing process in this order, in the cold rolling process, the average rolling rate for each pass in the first cold rolling is 20 to 30%, the second The average rolling rate for each pass in cold rolling is 20 to 35%, the total rolling rate of the first cold rolling and the second cold rolling is 95% or more, and the first cold When the total rolling rate in rolling is α and the total rolling rate in the second cold rolling is β, the cold rolling process is performed so that 1.2 ≦ α / β ≦ 1.9 is satisfied. In the annealing process, when the maximum temperature reached is Tmax (° C.), the holding time is tm (seconds), and the total cold rolling rate is RE (%),
570 <{T _max −60 × tm ^−1/2 −50 × (1-RE / 100) ^1/2 } <670
It has also been found that the above-described phosphorous deoxidized copper plate is optimally manufactured by performing the finish annealing so as to satisfy the above.

That is, the phosphorus-deoxidized copper plate excellent in brazing and press workability of the present invention contains 0.004 to 0.040 mass% of P, the balance is made of copper and inevitable impurities, and the crystal orientation on the plate surface is , {200} crystal plane X-ray diffraction intensity is I {200}, {220} crystal plane X-ray diffraction intensity is I {220}, {420} crystal plane X-ray diffraction intensity is I {420} In this case, the numerical value of I {200} / (I {220} + I {420}) is 1.3 to 2.3, and the surface roughness Ra on the plate surface is 0.1 to 0.3 μm. There state, and are less 0.4% steepness of the plate surface, the absolute value of the residual stress at a depth of 1μm from the plate surface is not more than 300 MPa, the phosphorus copper brazing to the plate surface 0.04 g (± 0.005g), so that wax flows in the BadWay direction 2. Installed in a continuous furnace in a hydrogen atmosphere with a set temperature of 850 ° C. with an inclination of 2.9 °, passed through the continuous furnace for 20 minutes, and then the phosphor copper braze that flowed on the plate surface The distance is 16.5 mm or more .
Furthermore, the heat exchanger body of the present invention is characterized by being manufactured using the above-described phosphorous deoxidized copper plate having excellent brazing properties and press workability.

Furthermore, the method for producing a phosphorous deoxidized copper sheet excellent in brazing property and press workability of the present invention includes a hot rolling step, a cold rolling step, and a finish annealing step in this order, and the cold rolling step. In the process, the average rolling rate per pass in the first cold rolling is 20 to 30%, the average rolling rate per pass in the second cold rolling is 20 to 35%, and the first cold rolling is performed. The total rolling ratio of the cold rolling and the second cold rolling is 95% or more, the total rolling ratio in the first cold rolling is α, and the total rolling ratio in the second cold rolling is β In this case, the cold rolling step is performed so as to satisfy 1.2 ≦ α / β ≦ 1.9, and in the finish annealing step, the maximum temperature reached is Tmax (° C.) and the holding time is tm ( Second), when the total cold rolling rate is RE (%),
570 <{T _max −60 × tm ^−1/2 −50 × (1-RE / 100) ^1/2 } <670
The finish annealing step is performed so as to satisfy the above condition.

  INDUSTRIAL APPLICABILITY According to the present invention, a phosphorous deoxidized copper plate excellent in brazing property and press workability and particularly suitable for use as a body portion of a heat exchanger and a method for producing the same are provided.

  The phosphorus-deoxidized copper plate excellent in brazing property and press workability of the present invention contains 0.004 to 0.040 mass% of P, the balance is made of copper and inevitable impurities, and the crystal orientation on the plate surface is {200 } When the X-ray diffraction intensity of the crystal plane is I {200}, the X-ray diffraction intensity of the {220} crystal plane is I {220}, and the X-ray diffraction intensity of the {420} crystal plane is I {420} The numerical value of I {200} / (I {220} + I {420}) is 1.3 to 2.3, the surface roughness Ra on the plate surface is 0.1 to 0.3 μm, and the plate surface The steepness at is 0.4% or less.

Phosphorus deoxidized copper is pure copper that has taken measures against hydrogen embrittlement that tough pitch copper has, and is deoxidized with phosphorous, which is inferior in conductivity to tough pitch, but oxygen remains because phosphorus remains. Even when heated, it reacts with hydrogen and does not produce water vapor from the inside, so that it does not cause hydrogen embrittlement, heat resistance is slightly improved, and it softens at 180 to 200 ° C.
The composition of the phosphorous deoxidized copper plate of the present invention contains 0.004 to 0.040 mass% of P, and the balance is made of copper and inevitable impurities, and corresponds to any of JIS C1201, JIS C1220, and JIS C1221.

In the phosphorous deoxidized copper plate of the present invention, the crystal orientation on the plate surface is such that the X-ray diffraction intensity of the {200} crystal plane is I {200}, the X-ray diffraction intensity of the {220} crystal plane is I {220}, When the X-ray diffraction intensity of the {420} crystal plane is I {420}, the numerical value of I {200} / (I {220} + I {420}) is 1.3 to 2.3. Residual stress is small, its distribution is homogenized, press punching processability is improved, and the direction of warping of the plate due to heat when brazing at a high temperature of about 800 ° C. in a continuous furnace is made constant. , Brazing improves.
Residual stress is stress that exists in the material without external force or thermal gradient, and is generated as a result of non-uniform deformation due to heat treatment or cold working. If the residual stress remains, it becomes difficult to obtain a flat strip or plate, and if the flatness is impaired, the dimensional accuracy when pressed is adversely affected. Generally, the residual stress is widely distributed inside the rolled material, and in the case of the rolled material, the gradient of the residual stress in the vicinity of the surface layer is often high.
When the value of I {200} / (I {220} + I {420}) is less than 1.3 or exceeds 2.3, press punching workability and brazing performance are deteriorated.

Further, since the phosphorus-deoxidized copper plate of the present invention has a small residual stress and a uniform distribution, the steepness is 0.4% or less, the press punching processability is improved, and further, about 800 ° C. in a continuous furnace. The direction of warping of the plate due to heat during brazing at a high temperature is made constant, and brazing performance is improved.
When the steepness is 0.4% or more, press punching workability and brazing performance are deteriorated.
In addition, since the phosphorous deoxidized copper plate of the present invention has a surface roughness Ra of 0.1 to 0.3 μm, the directionality of the brazing material flow during brazing is stable and exhibits excellent brazing properties. Can do.
When the surface roughness Ra is less than 0.1 μm or exceeds 0.3 μm, the brazing property is lowered.
The other member to be brazed to the phosphorous deoxidized copper plate of the present invention is not particularly limited as long as the material is a metal material, but is preferably a copper or copper alloy member having various shapes.
The phosphorous deoxidized copper plate of the present invention is particularly preferably used as a heat exchanger barrel that is pressed and brazed to other members of various shapes, thereby reducing the cost of the heat exchanger barrel. In addition, reliability can be improved.

The phosphorous deoxidized copper plate of the present invention contains 0.004 to 0.040 mass% of melt-cast P, and the remainder is composed of copper and inevitable impurities. And a final annealing step in this order, and in the cold rolling step, the average rolling rate per pass in the first cold rolling is 20 to 30%, in the second cold rolling The average rolling rate for each pass is 20 to 35%, the total rolling rate of the first cold rolling and the second cold rolling is 95% or more, and the total in the first cold rolling is When the rolling rate is α and the total rolling rate in the second cold rolling is β, the cold rolling process is carried out so as to satisfy 1.2 ≦ α / β ≦ 1.9, and in the final annealing step When the maximum temperature reached is Tmax (° C.), the holding time is tm (seconds), and the total cold rolling rate is RE (%),
570 <{T _max −60 × tm ^−1/2 −50 × (1-RE / 100) ^1/2 } <670
It is manufactured optimally by performing finish annealing to satisfy the above.

By carrying out the above-mentioned various rolling conditions in the cold rolling process within the specified range values, the crystal orientation on the plate surface is set to {200} crystal plane X-ray diffraction intensity I {200}, and {220} crystals Numerical value of I {200} / (I {220} + I {420}) where X-ray diffraction intensity of the plane is I {220} and X-ray diffraction intensity of the {420} crystal plane is I {420} A base having a thickness of 1.3 to 2.3 is prepared, and annealing in the final annealing step is performed with a maximum temperature: Tmax (° C.), a holding time: tm (seconds), and a total cold rolling rate: RE (%). By implementing the above relationship within the range of the above formula, the crystal orientation on the plate surface is such that the X-ray diffraction intensity of the {200} crystal plane is I {200}, and the X-ray diffraction of the {220} crystal plane When the intensity is I {220} and the X-ray diffraction intensity of the {420} crystal plane is I {420} , I {200} / (I {220} + I {420}) is 1.3 to 2.3, the surface roughness Ra on the plate surface is 0.1 to 0.3 μm, and the steepness is 0. 4% or less.
If the above conditions in the cold rolling process and the annealing process deviate from the specified range values of the present invention, the residual stress increases and the distribution becomes inhomogeneous, with excellent brazeability and press workability, especially heat exchangers. The phosphorus-deoxidized copper plate of the present invention suitable for use as a body portion of the steel cannot be produced.
In the manufacturing method of the present invention, the final tempering is performed by annealing instead of rolling, and further, cold rolling is performed in two stages, and annealing is not performed in the middle, thereby simplifying the process and reducing manufacturing costs. Also contributes.

A JIS C1220 ingot of phosphorous deoxidized copper was heated to 900 ° C., hot-rolled to a plate thickness of 12.0 mm, then face-cut to a plate with a thickness of 11.2 mm, The average rolling rate per pass in the first cold rolling shown in Table 1, the average rolling rate per pass in the second cold rolling, and the first cold rolling and the second cold rolling were combined. After carrying out the cold rolling step at the total rolling rate (α / β), the finish annealing step is further carried out at the annealing index shown in Table 1, and the phosphorus removal in Examples 1 to 10 and Comparative Examples 1 to 10 An acid copper plate was prepared.
Here, the annealing index means that the maximum temperature reached is Tmax (° C.), the holding time is tm (seconds), and the total cold rolling rate is RE (%).
T _max −60 × tm ^−1/2 −50 × (1-RE / 100) ^1/2
Is a value calculated from the following formula.

For these phosphorous deoxidized copper plates, the X-ray diffraction intensity of {200} crystal plane, the X-ray diffraction intensity of {220} crystal plane, and the X-ray diffraction intensity of {420} crystal plane on the plate surface were measured, and I { A numerical value of 200} / (I {220} + I {420}) was obtained.
X-ray diffraction intensity is measured using the EBSD (manufactured by TSL Solutions Inc.) method using a scanning electron microscope with a backscattered electron diffraction image system (Hitachi model: SU-70). I {200} / (I {220} + I {420}) was calculated from the X-ray diffraction intensities of the {200} plane, {220} plane, and {420} plane. As the measurement control software, OIM Data Collection Ver.5 (manufactured by TSL Solutions Inc.) was used.
The measurement results are shown in Table 2.

Moreover, surface roughness Ra in the plate surface was measured about these phosphorus deoxidation copper plates.
The surface roughness was based on JIS B 0601, and the arithmetic average roughness (Ra) of the test material surface was measured. The measurement distance was 4 mm and the measurement was performed in the direction perpendicular to the rolling direction.
The measurement results are shown in Table 2.
Further, the steepness of these phosphorous deoxidized copper plates was measured.
The steepness was calculated by the following calculation formula using a surface displacement / waviness / steepness measuring device (FA Systems model: XY-23705l).
Steepness = {(height of ear wave or medium elongation) / (pitch of ear wave or medium elongation)} × 100
The measurement results are shown in Table 2.

Next, press workability was evaluated for these phosphorous deoxidized copper plates.
Residual stress is stress that exists in the material without external force or thermal gradient. If residual stress remains, it becomes difficult to obtain flat strips and plates, and if flatness is impaired, press It adversely affects the dimensional accuracy when processed.
Therefore, the press workability was evaluated by the absolute value of the residual stress at a depth of 1 μm from the surface. The absolute value of this residual stress was measured as follows.
First, a test piece having a width of 20 mm and a length of 200 mm with the rolling direction as the longitudinal direction was cut out, and while removing the surface layer on one side of the test piece gradually using an etching solution, the length direction of the remaining test piece at each depth Curvatures φx and φy in (x) and width direction (y) were measured. This was repeated until the plate thickness was halved. The curvature was obtained by measuring the warp of the test piece. The curvature of the specimen was considered as a part of the circumference, and the reciprocal of the radius corresponding to this circle was taken as the curvature (the curvature can be easily obtained mathematically by measuring the length and height of the string). Thereafter, the relationship between the etching depth a and the curvature was plotted in the figure, and the absolute value σx (a) of the residual stress in the rolling direction (x) at the etching depth a = 1 μm from the surface was measured by the following formula.

Table 3 shows the measurement results.
Next, these phosphorous deoxidized copper plates are subjected to press punching to produce phosphorous deoxidized copper plates after press punching in a shape of length 100 mm × width 50 mm. Brazing property was evaluated by the following tests (a) and (b).
(A) Brazing property test method 0.04 g (± 0.005 g) of phosphor copper brazing (BCUP2) as a brazing material was placed on a phosphorous deoxidized copper plate so that the brazing would flow in the Bad Way direction. The phosphorus deoxidized copper plate was installed in a continuous furnace in a hydrogen atmosphere with an inclination of 2.9 °, and after passing through the continuous furnace for 20 minutes, the distance of BCUP2 flowing on the phosphorus deoxidized copper plate was measured. The inside of the continuous furnace was a hydrogen atmosphere, the set temperature was 850 ° C., the maximum temperature reached was 825 ° C., and the retention time at 800 ° C. or higher was 8 minutes 30 seconds.
Table 3 shows the measurement results.
(B) Brazing property test method.
The phosphorous deoxidized copper plate was degreased with acetone, pickled with 5% H ₂ SO ₄ , immersed in an In bath for 5 minutes, and visually observed whether the wax was evenly wetted. A sample was marked with ◯, and a sample that was not uniformly wet was marked with ×.
Table 3 shows the measurement results.
Moreover, about the phosphorus deoxidation copper plate after these press processes, the curvature shape at the time of brazing temperature was evaluated by the following method.
Without inclining the phosphorous deoxidized copper plate and without using BCUP2, after heating and holding in a continuous furnace under the same conditions as in (a), both ends of the phosphorous deoxidized copper plate warped on the surface plate face upward The height of each corner was measured with a height gauge. The difference between the maximum and minimum height of warped at each corner is 0.1 mm, the difference between 0.1 mm and 0.3 mm is Δ, and the difference between 0.3 mm and 0.3 mm is X.
Table 3 shows the measurement results.

From these results, the phosphorus-deoxidized copper plate of the example manufactured by the manufacturing method of the present invention is superior to the phosphorus-deoxidized copper plate of the comparative example in press workability and brazing, and warpage after heating is also possible. I understand that there are few. That is, the absolute value of the residual stress at a depth of 1 μm from the plate surface of the phosphorous deoxidized copper plate is 300 MPa or less, 0.04 g (± 0.005 g) of phosphorous copper brazing on the plate surface, and wax flows in the BadWay direction. It was placed in a continuous furnace in a hydrogen atmosphere with a set temperature of 850 ° C. with an inclination of 2.9 °, passed through the continuous furnace for 20 minutes, and then the phosphor copper braze that flowed on the plate surface. The phosphorous deoxidized copper plate having a distance of 16.5 mm or more is excellent in press workability and brazing property.

  As mentioned above, although the manufacturing method of embodiment of this invention was demonstrated, this invention is not limited to this description, A various change can be added in the range which does not deviate from the meaning of this invention.

Claims (3)

P contains 0.004 to 0.040% by mass, the balance is made of copper and inevitable impurities, the crystal orientation on the plate surface is X-ray diffraction intensity of {200} crystal plane is I {200}, and {220} crystal Numerical value of I {200} / (I {220} + I {420}) where X-ray diffraction intensity of the plane is I {220} and X-ray diffraction intensity of the {420} crystal plane is I {420} There is 1.3-2.3, a surface roughness Ra of 0.1~0.3μm in the plate surface state, and are less 0.4% steepness in the plate surface, from the plate surface The absolute value of residual stress at a depth of 1 μm is 300 MPa or less, and 0.04 g (± 0.005 g) of phosphor copper brazing is placed on the surface of the plate so that the wax flows in the BadWay direction, and the inclination is 2.9 ° A continuous furnace in a hydrogen atmosphere with a set temperature of 850 ° C Installed in, after the continuous furnace is passed through 20 minutes, excellent brazeability and press formability distance of the phosphorus copper solder flows through said plate upper surface, characterized in that at least 16.5mm Phosphorus deoxidized copper plate.   A heat exchanger body manufactured using the phosphorous deoxidized copper plate having excellent brazing properties and press workability according to claim 1. A method for producing a phosphorous-deoxidized copper sheet excellent in brazeability and press workability according to claim 1, comprising a hot rolling step, a cold rolling step, and a finish annealing step in this order, In the cold rolling step, the average rolling rate per pass in the first cold rolling is 20 to 30%, the average rolling rate per pass in the second cold rolling is 20 to 35%, The total cold rolling ratio combining the first cold rolling and the second cold rolling is performed at 95% or more, the total rolling ratio in the first cold rolling is α, and the second cold rolling is When the total rolling rate of β is β, the cold rolling step is performed so as to satisfy 1.2 ≦ α / β ≦ 1.9, and in the finish annealing step, the maximum temperature reached is Tmax (° C.). When the holding time is tm (seconds) and the total cold rolling rate is RE (%),
570 <{T _max −60 × tm ^−1/2 −50 × (1-RE / 100) ^1/2 } <670
The manufacturing method of the phosphorus deoxidation copper plate excellent in brazing property and press workability characterized by implementing the said finish annealing process so that it may satisfy | fill.