KR101082823B1 - A method for manufacturing copper alloy with improved strength and electrical comductivity - Google Patents

Abstract

Copper alloy with improved strength and electrical conductivity according to the present invention, 2.1 to 2.6% by weight of iron (Fe), 0.015 to 0.15% by weight of phosphorus (P), 0.05 to 0.2% by weight of zinc (Zn ), A casting step of mixing and casting a copper alloy made of lead (Pb) of 0.03% or less by weight and cast iron or pig iron, and a hot rolling step of rolling the cast alloy at a multiple of 70% hot working rate; The first cold rolling step of cold rolling the hot-rolled alloy, the cold-rolled alloy to have a fine cast grain state, and the solution step to be composed of fine precipitates, the solution-treated alloy 450 ℃ and 500 And a second cold rolling step of cold-rolling the heat-treated alloy and a plurality of heat treatment steps sequentially several times at the same time.

Description

A method for manufacturing copper alloy with improved strength and electrical comductivity

The present invention achieves thermal stabilization of metastable precipitated phase that matches copper matrix by adding carbon (C) by mixing cast iron or pig iron to a copper (Cu) -iron (Fe) -phosphorus (P) alloy to achieve strength and electrical conductivity. It relates to a method for producing a copper alloy to improve the.

Copper is widely applied to electrical / electronic circuits because of its high electrical conductivity. However, copper is exposed to high currents and voltages when applied to electrical / electronic circuits due to high integration and light weight of telecommunication components.

In addition, when applied as a conductive material is exposed to the harsh environment has been required for high strength, electrical conductivity and excellent thermal stability.

That is, copper alloys are widely used as connectors for connecting connectors, accumulators, or controllers to various electrical components, actuators, sensors, and the like in automobiles equipped with more electric devices, and miniaturization of such connectors is urgently required.

In particular, the connector installed close to the engine is exposed to the engine's heat and vibration environment, and when a large amount of current is sent to the connector, the connector generates heat and rises to a high temperature. Therefore, such a connector is required to have high reliability under the above-mentioned environment.

Accordingly, Cu-Fe-P alloy (CDA19400) or Cu-Mg-P alloy is known as a material of a copper alloy connector for a conventional automobile or the like. The former alloy is an alloy whose strength is improved by precipitation of Fe—P compounds based on the simultaneous addition of Fe and P.

In addition, alloys having improved mobility resistance by addition of Zn (Japanese Patent Laid-Open No. 168830), alloys having improved stress relaxation resistance by addition of Mg (Japanese Patent Laid-Open No. 358033), and the like Known.

The latter alloy is an alloy that improves tensile strength, electrical conductivity and stress relaxation resistance by adding Mg and P to improve strength and thermal creeping characteristics.

In order to miniaturize and maintain the reliability of wiring connectors for automotive electrical parts, it is essential to increase the strength and elastic properties of the material of the connectors. Even when the connector is kept at a high temperature for a long time, it is essential to improve its stress relaxation resistance so that decomposition does not occur, that is, the fitting power does not decrease with time.

Looking at the tensile strength, elongation and hardness of the C19400 alloy (comparative example) with reference to the accompanying Figure 1, C19400 alloy is a representative Cu-Fe-P alloy, 2.1 to 2.6% by weight of iron (Fe) and 0.015 ~ 0.15 It comprises a weight percent phosphorus (P), 0.05 to 0.20 weight percent zinc (Zn), 0.03 weight percent or less lead (Pb) and the balance copper (Cu).

However, Cu-Fe-P copper alloy, which is a conventional material of a connector, has excellent moldability, but has a problem of low elasticity limit and poor stress relaxation resistance.

An object of the present invention is to achieve a strength by thermally stabilizing a metastable precipitated phase that matches a copper matrix by adding a carbon (C) by mixing a copper (Cu) -iron (Fe) -phosphorus (P) alloy and cast iron or pig iron. And a method for producing a copper alloy to improve softening resistance.

The method for producing a copper alloy with improved strength and electrical conductivity according to the present invention comprises 3.14 wt% carbon (C), 2.52 wt% silicon (Si), 0.35 wt% manganese (Mn) and 0.026 wt% Cast iron consisting of phosphorus (P), 0.014% by weight of sulfur (S), balance iron (Fe) or 4.30% by weight of carbon (C), 0.14% by weight of silicon (Si), 0.02 Pig iron consisting of wt% manganese (Mn), 0.028 wt% phosphorus (P), 0.014 wt% sulfur (S), balance iron (Fe), and 2.1 to 2.6 wt% iron ( Fe), 0.015 to 0.15 wt% phosphorus (P), 0.05 to 0.2 wt% zinc (Zn), 0.03 wt% or less lead (Pb), and the balance copper (Cu) A casting step of mixing and casting a copper alloy, a hot rolling step of rolling the cast alloy at a hot working rate of 70% over a plurality of times, a first cold rolling step of cold rolling of the hot rolled alloy, and cold rolling Alloys to have a fine cast grain state In the solution treatment step to be composed of fine precipitates, the heat treatment step of sequentially heat treatment the solution-treated alloy at 450 ℃ and 500 ℃ a plurality of times for the same time, and the second cold rolling step of cold rolling the heat treated alloy Characterized in that made.

The first cold rolling step is characterized in that the hot rolled sheet material is a process of rolling at a cold rolling rate of 75%.

The heat treatment step is characterized by consisting of a first heat treatment for heat treatment at 450 ℃ for 5 hours, and a second heat treatment for heat treatment at 500 ℃ for 5 hours.

The second cold rolling step is characterized in that the process of rolling the heat-treated plate at a cold rolling rate of 75%.

As described in detail above, according to the copper alloy with improved strength and electrical conductivity according to the present invention, a copper (Cu) -iron (Fe) -phosphorus (P) alloy is mixed with cast iron or pig iron to add carbon (C). .

Therefore, there is an advantage of improving the strength and softening resistance by thermally stabilizing the metastable precipitated phase matching the copper matrix.

In addition, in the method for producing a copper alloy with improved strength and electrical conductivity according to the present invention, the solution solution is configured to selectively perform the carbon content.

Therefore, there is an advantage that the production of a copper alloy exhibiting optimum physical properties by changing the electrical conductivity, hardness and strength according to the use of the copper alloy.

1 is a table showing the physical properties of the conventional C19400 alloy.
Figure 2 is a table showing the compositions of Examples and Comparative Examples of the copper alloy with improved strength and electrical conductivity according to the present invention.
Figure 3 is a table showing the composition of cast iron and pig iron added to the copper alloy with improved strength and electrical conductivity according to the present invention.
Figure 4 is a process flow chart showing a method for producing a copper alloy with improved strength and electrical conductivity according to the present invention.
5 is a real picture showing a change in appearance of the processed plate material according to the production method of the copper alloy with improved strength and electrical conductivity according to the present invention.
Figure 6 is an enlarged photograph showing the structure of a preferred embodiment and comparative example of the copper alloy with improved strength and electrical conductivity according to the present invention.
7 is a data comparing the tensile strength and electrical conductivity of the copper alloy with improved strength and electrical conductivity according to the present invention compared with the comparative example.
8 is a comparative graph showing the data of FIG. 7;
Figure 9 is a graph comparing the change in softening resistance according to the implementation of the solution step in the copper alloy with improved strength and electrical conductivity according to the present invention.
10 is a graph comparing the stress relaxation resistance of a preferred embodiment of the copper alloy with improved strength and electrical conductivity according to the present invention and a comparative example.
11 is a graph comparing the hardness and electrical conductivity of the preferred embodiment and comparative example of the copper alloy with improved strength and electrical conductivity according to the present invention.

Hereinafter, a configuration of a copper alloy (hereinafter, referred to as “copper alloy”) with improved strength and electrical conductivity according to the present invention will be described with reference to FIGS. 2 and 3.

2 is a table showing the composition of the examples and comparative examples of the copper alloy with improved strength and electrical conductivity according to the present invention, Figure 3 is cast iron and pig iron added to the copper alloy with improved strength and electrical conductivity according to the present invention A table showing the composition of is shown.

As shown in these figures, the copper alloy according to the present invention contains copper (Cu), iron (Fe), phosphorus (P) and, unlike the comparative example, further contains carbon (C).

More specifically, the iron (Fe) is 2.5 to 4.0% by weight, phosphorus (P) is 0.1% by weight, carbon (C) comprises 0.02 to 0.5% by weight, the balance (殘部) is copper (Cu), The carbon is contained by incorporating either carbon-containing cast iron or pig iron into the copper alloy.
At this time, the cast iron and pig iron is configured as shown in FIG. That is, the cast iron is 3.14% by weight of carbon (C), 2.52% by weight of silicon (Si), 0.35% by weight of manganese (Mn), 0.026% by weight of phosphorus (P), 0.014% by weight of sulfur ( S) and the balance iron (Fe), the pig iron is 4.30% by weight of carbon (C), 0.14% by weight of silicon (Si), 0.02% by weight of manganese (Mn) and 0.028 It consists of a weight% phosphorus (P), 0.014 weight% sulfur (S), and the remainder iron (Fe).

Carbon added to the copper alloy serves to improve the strength and softening resistance by thermal stabilization of the metastable precipitated phase to match the copper base to have an average particle size of 70㎛ or less. In addition, as described in the manufacturing method to be described below, the carbon can increase the tensile strength of 483 to 608 MPa and the electrical conductivity of 64.7% IACS or less through the heat treatment step (S500).

Hereinafter, a method of manufacturing a copper alloy having the above configuration will be described with reference to FIGS. 4 and 5.

Figure 4 is a process flow chart showing a method for producing a copper alloy with improved strength and electrical conductivity according to the present invention, Figure 5 is a change in appearance of the processed plate material according to the manufacturing method of the copper alloy with improved strength and electrical conductivity according to the present invention. It is a real photograph shown.

First, the method for producing a copper alloy according to the present invention as shown in Figure 4, 2.1 to 2.6% by weight of iron (Fe), 0.015 to 0.15% by weight of phosphorus (P), 0.05 to 0.2% by weight of zinc (Zn ), And a casting step (S100) of mixing and casting a copper alloy and cast iron or pig iron made of lead (Pb) of 0.03% or less by weight, and hot rolling step (S200) of hot rolling the cast alloy, and hot rolled The first cold rolling step (S300) for cold rolling the alloy, the heat treatment step (S500) for heat treatment the cold rolled alloy multiple times at different temperature conditions, and the second cold rolling step (S700) for cold rolling the heat-treated alloy It characterized by consisting of).

The copper alloy cast in the casting step (S100) was adopted as an embodiment by mixing the above components in various ratios, as shown in the top photo of FIG.

And, the copper alloy was hot rolled as shown in the second picture from the top of the hot rolling step (S200) of FIG.

The condition of the hot rolling step (S200) was rolled at a hot working rate of 70% over 5 times at 980 ° C. for 1 hour, wherein the thickness was changed from 20 mm to 6 mm.

In addition, since the surface of the copper alloy is oxidized during the hot rolling step (S200), the copper alloy is in a state as shown in the third picture from the top of FIG. 5.

After the first cold rolling step (S300) is carried out. The first cold rolling step (S300) was cold rolled a little over six times to roll a 4 mm sheet at a cold processing rate of 75% to have a thickness of 1 mm.

At this time, the plate passed through the first cold rolling step (S300) is in a state as shown in the fourth picture from the top of FIG.

After the heat treatment step (S500) is carried out. The heat treatment step (S500) is a process of sequentially heating the cold rolled copper alloy at the same time at 450 ℃ and 500 ℃, an important step to increase the tensile strength and electrical conductivity of the copper alloy.

More specifically, the heat treatment step (S500) is the first heat treatment step (S520) for first heat-treating the cold-rolled copper alloy for 5 hours at 450 ℃, and the second heat treatment process for heating for 5 hours by raising the temperature to 500 ℃ ( S540 is performed sequentially.

After the heat treatment step S500, a water cooling step S600 is performed, and after the water cooling step S600, the second cold rolling step S700 is performed.

The second cold rolling step (S700) is a process of rolling the heat-treated copper alloy at 75% cold rolling rate, in the embodiment of the present invention was rolled copper alloy having a thickness of 1 mm to have a thickness of 0.25 mm, Figure 5 It is shown at the bottom of the picture.

The production of the copper alloy according to the present invention is completed through a plurality of steps as described above, and the solutionization step (S400) is selectively performed between the first cold rolling step (S300) and the heat treatment step (S500).

The solution step (S400) is a process for increasing the tensile strength and electrical conductivity of the cold-rolled copper alloy, the copper alloy has a fine cast granules state, it is a process to be composed of fine precipitates.

6 to 11 compares the experimental data and the comparative example of the preferred embodiment of the present invention.

6 is an enlarged photograph showing a structure of a preferred embodiment and a comparative example of the copper alloy with improved strength and electrical conductivity according to the present invention.

As shown in the figure, the crystal grains of the comparative example without the addition of carbon have an average particle size of 100 μm, but in the case of the preferred embodiment of the present invention to which carbon is added, it can be seen that the average particle size is 70 μm.

In addition, coarse Fe ₃ P particle fraction is slightly reduced by the addition of carbon, it can be seen that a large amount of fine Fe particles are formed.

Hereinafter, the changes in tensile strength and electrical conductivity of the copper alloy of the present invention and the copper alloy of the comparative example with or without solution treatment were examined.

7 is data comparing tensile strength and electrical conductivity of a copper alloy having improved strength and electrical conductivity according to the present invention with a comparative example, and FIG. 8 is a comparative graph showing data of FIG. 7.

As shown in these figures, the comparative example and the example were slightly reduced in tensile strength in the case of solution treatment, but it can be seen that the tensile strength of the example is relatively higher than the tensile strength of the comparative example.

In addition, the electrical conductivity of the comparative example was slightly increased from 53.1% IACS to 56.8% IAS when subjected to the solution treatment, but the electrical conductivity of the example increases or decreased depending on the carbon content regardless of the solution treatment. .

Therefore, by adjusting the content of carbon according to the physical properties required for the copper alloy and selectively performing the solution step (S400), it is possible to control the optimum electrical conductivity and tensile strength.

Hereinafter, with reference to the accompanying Figures 9 and 10 will be described the softening resistance and the stress relaxation resistance properties that are required when the preferred embodiment of the present invention is applied to the connector.

Figure 9 is a graph comparing the change in softening resistance according to the implementation of the solution in the copper alloy with improved strength and electrical conductivity according to the present invention, Figure 10 is a preferred copper alloy with improved strength and electrical conductivity according to the present invention It is a graph which compared the stress relaxation resistance of an Example and a comparative example.

As shown in these drawings, it can be seen that the embodiment prepared according to the present invention was restored to 98% level after hardness reduction of about 5% when exposed to 230 ° C.

And the hardness of the case without the solution treatment was found to be substantially higher than the solution treatment case, when the copper alloy according to the present invention is used as the material of the connector solution solution step (S400) It is preferable not to selectively carry out.

And before looking at the stress relaxation resistance of the embodiment of the present invention with reference to Figure 10, the test machine used a Slow Strain Rate Tester, and controlled the speed from 1.0 mm / sec to 0.0 mm / sec.

The standard length of 25 mm was applied, and the temperature was 120 ° C ± 3 ° C and soaked for 30 minutes.

As a result, the comparative example and the Example showed similar stress change over time, the Comparative Example showed a stress relaxation resistance of 36.9%, the Example shows a stress relaxation resistance of 39.5%, the stress relaxation resistance of the Example It can be seen that it appeared somewhat higher than this comparative example.

Hereinafter, with reference to the accompanying Figure 11 looks at the change in hardness according to the implementation of the solution step.

11 is a graph comparing the hardness and electrical conductivity of the preferred embodiment of the copper alloy with improved strength and electrical conductivity according to the present invention and the comparative example, the embodiment subjected to the solution step (S400) when compared with the electrical conductivity of the comparative example Various electrical conductivity was shown according to the carbon content.

In addition, the hardness was also subjected to the solution step (S400) Example showed a variety of hardness distribution according to the change in the content of carbon when compared with the hardness of the comparative example.

However, in the case of not performing the solution step, the hardness of the Example is significantly higher than that of the comparative example, and it can be seen that the electroconductivity is somewhat higher than that of the comparative example.

In view of these results, the solutionization step is carried out selectively, and by controlling the content of carbon it is possible to produce a copper alloy having an optimum electrical conductivity or hardness.

The scope of the present invention is not limited to the above-described embodiments, and many other modifications based on the present invention will be possible to those skilled in the art within the scope of the present invention.

S100. Casting step S200. Hot rolling stage
S300. First cold rolling step S400. Solution step
S500. Heat treatment step S520. First heat treatment process
S540. Second heat treatment process S600. Water cooling stage
S700. Second cold rolling stage

Claims (4)

3.14 wt% carbon (C), 2.52 wt% silicon (Si), 0.35 wt% manganese (Mn), 0.026 wt% phosphorus (P), 0.014 wt% sulfur (S), and the balance Cast iron made of iron (Fe) or 4.30 wt% carbon (C), 0.14 wt% silicon (Si), 0.02 wt% manganese (Mn) and 0.028 wt% phosphorus (P) , Pig iron consisting of 0.014% by weight of sulfur (S), balance iron (Fe), 2.1 to 2.6% by weight of iron (Fe), 0.015 to 0.15% by weight of phosphorus (P), and 0.05 A casting step of mixing and casting a copper alloy made of zinc (Zn), 0.2 wt% or less, 0.03 wt% or less of lead (Pb), and remainder copper (Cu);
A hot rolling step of rolling the cast alloy at a hot working rate of 70% over a plurality of times;
A first cold rolling step of cold rolling the hot rolled alloy,
A solution-forming step of allowing the cold rolled alloy to have a fine cast grain state and to be composed of fine precipitates;
A heat treatment step of sequentially heat treating the solution-treated alloy at 450 ° C. and 500 ° C. for the same time;
A method of manufacturing a copper alloy with improved strength and electrical conductivity, comprising a second cold rolling step of cold rolling the heat-treated alloy. The method of claim 1, wherein the first cold rolling step is a process of rolling a hot rolled sheet at a cold rolling rate of 75%. The method of claim 2, wherein the heat treatment step,
A first heat treatment process of heat treatment at 450 ° C. for 5 hours,
A method of manufacturing a copper alloy with improved strength and electrical conductivity, characterized in that the second heat treatment process is performed for 5 hours at 500 ℃. The method of claim 3, wherein the second cold rolling step,
A method of producing a copper alloy with improved strength and electrical conductivity, characterized in that the process of rolling the heat-treated plate at a cold rolling rate of 75%.

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