JPH0688177A - Production of copper alloy pipe - Google Patents

Abstract

PURPOSE:To provide a method for producing a copper alloy pipe with high productivity in the method for producing a copper alloy pipe suitable as a heat transfer pipe for a heat exchanger and a building piping material. CONSTITUTION:At first, a copper alloy sheet contg., by weight, 0.01 to 0.25% Fe and <=0.1% P (or only Fe by 0.01 to 0.25%) is subjected to heat treatment to allow Fe and P (or Fe) to enter into solid solution. In this way, the electric conductivity and thermal conductivity of the sheet are reduced, and its weldability is improved. Next, the sheet is worked to form its shape into a prescribed pipe one, and its joint part is, e.g. subjected to resistance welding. Then, aging heat treatment is executed to precipitate Fe and P (or Fe). In this way, the electric conductivity and thermal conductivity of the copper alloy pipe can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for producing a copper alloy pipe used as a heat transfer pipe for a heat exchanger used in an air conditioner refrigerator or the like and a construction pipe such as a hot water supply / water supply pipe.
In particular, the present invention relates to a method for manufacturing a copper alloy tube manufactured by processing a copper alloy sheet material into a tube shape and welding a joint portion thereof.

[0002]

2. Description of the Related Art Conventionally, heat transfer pipes for heat exchangers used in air conditioners and other construction pipes such as hot water supply / water supply pipes have good heat conductivity, workability and brazing property. Therefore, a seamless tube of phosphorus-deoxidized copper or oxygen-free copper is mainly used. However, since the seamless pipe has a high manufacturing cost,
In recent years, welded pipes manufactured by processing a plate material made of phosphorus-deoxidized copper or oxygen-free copper into a pipe shape and welding the joint portion have been used for these purposes.

[0003]

However, the conventional welded pipe made of phosphorus-deoxidized copper or oxygen-free copper has a problem of low productivity. The reason will be described below.

Generally, when welding metals, a fusion welding method or a pressure welding method is used. The fusion welding method includes arc welding and gas welding, and the pressure welding method includes high frequency welding and resistance welding. Generally, a pressure welding method is used for welding copper or a copper alloy.

The pressure welding method is a method of welding by converting electric energy into heat energy (Joule heat), and it is well known that a material having lower electric conductivity and heat conductivity is easier to weld. Since phosphorus deoxidized copper and oxygen-free copper have high electric conductivity and high thermal conductivity as described above, they have the advantage of being excellent as materials for heat transfer tubes and the like, but have the drawback of being difficult to weld.

The present invention has been made in view of the above problems, and has high productivity as a welded pipe, and a copper alloy pipe suitable for a heat transfer pipe for a heat exchanger and a pipe for construction can be manufactured. An object is to provide a method for manufacturing an alloy pipe.

[0007]

A method of manufacturing a copper alloy tube according to the present invention comprises 0.01 to 0.25 wt% Fe and 0.1 wt%.
A heat treatment step of heat-treating a copper alloy sheet containing P (or 0.01 to 0.25% by weight of Fe only) with the balance being Cu and unavoidable impurities to form a solid solution of Fe and P; And a welding step of welding the joint portion into a predetermined pipe shape.

After the welding process, an aging heat treatment process of precipitating Fe and P (or Fe) by performing an aging heat treatment may be provided. Further, a grooving step of providing a groove on the surface of the copper alloy sheet may be provided between the heat treatment step and the welding step.

[0009]

The present inventors have conducted various experimental studies in order to obtain a copper alloy welded pipe which is easy to weld at the time of seam welding and has high thermal conductivity and electrical conductivity when used as a product. As a result, the following was revealed. That is, when a copper alloy containing a predetermined amount of Fe and P (or only Fe) is heat-treated, Fe and P form a solid solution to reduce the electrical conductivity and thermal conductivity of the copper alloy material, resulting in good weldability. become. Further, when this copper alloy material is subjected to an aging heat treatment, Fe and P are precipitated as Fe ₂ P, and the electrical conductivity and thermal conductivity are improved to the same extent as phosphorus deoxidized copper. The present invention has been made based on such experimental results.

Next, the reason for adding each component and the reason for limiting the composition thereof will be described.

Fe (iron) By adding Fe and subjecting it to heat treatment, Fe is solid-dissolved in copper to lower the electrical conductivity and thermal conductivity of the copper alloy material,
The weldability of the copper alloy material is improved. However, the Fe content is 0.
If it is less than 01% by weight, the effect of lowering the electrical conductivity and thermal conductivity cannot be sufficiently obtained. On the other hand, if the Fe content exceeds 0.25% by weight, the strength of the welded portion will decrease. It is considered that this decrease in the strength of the weld is due to the inhibition of the oxide. Therefore, the Fe content is 0.01 to 0.25
Weight% The more preferable range of Fe content is
0.05 to 0.15% by weight.

Similar to Fe, P (phosphorus) P also has the effect of forming a solid solution in copper to reduce the electrical conductivity and thermal conductivity of the copper alloy material. Further, by co-adding P, it becomes possible to easily manufacture the copper alloy material by melting it in the air. Furthermore, by aging heat treatment, Fe
_{Since 2} P is precipitated and the solid solution P concentration is reduced, there is also an effect that stress corrosion cracking resistance is improved. Therefore, it is preferable to add P together with Fe. However, the P content is 0.1
When it exceeds the weight%, the stress corrosion cracking resistance decreases. Therefore, when P is contained, the P content is set to 0.1% by weight or less. In addition, considering the actual operation, the P content is 0.0
More preferably, it is from 0.05 to 0.05% by weight.

In the present invention, first, within the above range, F
The copper alloy plate added with e and P (or only Fe) is heat-treated. As a result, Fe and P form a solid solution, the electrical conductivity and thermal conductivity of the copper alloy plate are reduced, and the weldability is improved. Next, this copper alloy plate is processed into a predetermined tube shape, and its joint is welded to obtain a copper alloy tube.

In the present invention, since the electrical conductivity and thermal conductivity of the copper alloy plate are reduced in this way, the copper alloy plate material is processed into a tubular shape and the joints thereof are welded, so that welding is easy. Therefore, the productivity of the copper alloy tube is improved.

When a copper alloy tube is used as a heat transfer tube for a heat exchanger, Fe and P (or Fe) are deposited by subjecting the tube after welding to an aging heat treatment, so that the electrical conductivity of the copper alloy tube is increased. The conductivity and thermal conductivity are improved. Thereby, a copper alloy tube suitable as a heat exchanger tube for a heat exchanger can be obtained.

In this case, it is preferable to provide a groove forming step for forming a groove on the surface of the plate material between the heat treatment step and the welding step. As a result, the surface area of the tube is increased, and the thermal conductivity of the heat transfer tube can be significantly improved.

[0017]

EXAMPLES Next, the results of actually producing a copper alloy tube by the method of the present invention and examining its performance will be described in comparison with a comparative example which is out of the scope of the claims of the present application.

First, a copper alloy having the composition shown in Table 1 below was melted and a plate material having a thickness of 50 mm was cast. Next, 850 each plate
Hot rolling was performed at a temperature of ° C to obtain a plate material having a thickness of 10 mm, and further cold rolling was performed to obtain a copper alloy plate material having a thickness of 1 mm. In addition, F
In order to keep e and P in a solid solution state, the rolled material is water-cooled immediately after completion of hot rolling. Also, when heat treatment is performed immediately before the grooving process for grooving, 600 to 90
Fe and P are kept in a solid solution state by performing a heat treatment for 10 seconds to 5 minutes at a temperature of 0 ° C. for a short time and immediately thereafter water cooling.

Next, from each plate material, the width is 25 mm and the length is 100 mm.
Two test materials having a size of 2 mm were cut out, the two test materials were abutted in the longitudinal direction, and their joints were welded by resistance welding.

Then, an aging heat treatment was performed at a temperature of 450 to 550 ° C. for about 30 minutes to 5 hours.

The electrical conductivity of each test material of Examples and Comparative Examples was examined during welding and after aging treatment. After welding, the tensile strength of the welded portion of each test material was also examined by a tensile test in the longitudinal direction. Furthermore, the elongation of the test material after heat treatment was also examined. The results are summarized in Table 2 below. However, the elongation depends on the grain size of each test material by 20 to 30μ by heat treatment.
After adjusting to m, a JIS No. 13B test piece was prepared and examined by a tensile test. It should be noted that the higher the tensile strength of the welded portion, the less the welding defects and the higher the welding speed. Further, all the breakage points by the tensile test were in the vicinity of the welded portion.

[0022]

[Table 1]

[0023]

[Table 2]

As is clear from Table 2, all of Examples 1 to 8 have a high tensile strength of 22 kgf / mm ² or more at the welded portion, have good weldability, and have an elongation of the material after heat treatment. 40
%, Which is good. On the other hand, Comparative Examples 1, 2, 4, 5
In both cases, the tensile strength of the weld is low and the weldability is poor. In Comparative Example 3 in which the tensile strength of the welded portion is relatively high, although the weldability is good, the elongation after heat treatment is as small as 38%, and the P content is high, so the stress corrosion cracking resistance is low.
Poor practicality as a heat transfer tube for heat exchangers or piping for construction.

When a copper alloy tube is used as a heat exchanger tube for a heat exchanger, the larger the surface area, the higher the thermal conductivity. Therefore, when manufacturing a copper alloy tube used as a heat transfer tube for a heat exchanger, it is preferable to provide a grooving step of providing a groove on the surface of the plate material before processing into a tube shape.
Thereby, a copper alloy tube having a large surface area and excellent thermal conductivity can be obtained.

[0026]

As described above, according to the present invention, a copper alloy plate material containing a predetermined amount of Fe and P (or only Fe) is heat-treated to form a solid solution of Fe and P (or Fe). Since the electrical conductivity and the thermal conductivity are reduced, the pipe shape is processed and the joint portion is welded, the welding is easy and the productivity of the copper alloy pipe is high. Moreover, since electrical conductivity and thermal conductivity can be improved by performing an aging treatment after welding, it is possible to obtain a copper alloy tube suitable as a heat transfer tube for heat exchangers and a piping material for construction.

Claims (6)

[Claims] 1. A heat treatment step of heat treating a copper alloy sheet containing 0.01 to 0.25% by weight of Fe with the balance being Cu and unavoidable impurities to form a solid solution of Fe, and forming the copper alloy sheet into a predetermined tube shape. A method of manufacturing a copper alloy pipe, comprising a welding step of processing and welding the seam portion. 2. The method for producing a copper alloy pipe according to claim 1, further comprising an aging heat treatment step of performing an aging heat treatment to precipitate Fe after the welding step. 3. The method for producing a copper alloy pipe according to claim 2, further comprising a grooving step of providing a groove on the surface of the copper alloy sheet between the heat treatment step and the welding step. 4. A heat treatment step of heat treating a copper alloy sheet containing 0.01 to 0.25% by weight of Fe and 0.1% by weight or less of P and the balance of Cu and inevitable impurities to form a solid solution of Fe and P. And a welding step of welding a copper alloy plate material into a predetermined pipe shape and welding a joint portion thereof. 5. The method for producing a copper alloy tube according to claim 4, further comprising an aging heat treatment step of precipitating Fe and P by performing an aging heat treatment after the welding step. 6. The method for producing a copper alloy tube according to claim 5, further comprising a grooving step of providing a groove on the surface of the copper alloy sheet between the heat treatment step and the welding step.