JP5426936B2 - Copper alloy manufacturing method and copper alloy - Google Patents

Description

  The present invention relates to a copper alloy manufacturing method and a copper alloy. In particular, the present invention relates to a method for producing a copper alloy used for electric / electronic parts and a copper alloy.

  Materials used for electrical and electronic parts such as connectors, relays, switches, etc. have sufficient strength to obtain high contact pressure as a spring material, and stress relaxation that can maintain contact pressure even after long-term use at high temperatures Characteristics, such as high conductivity necessary to suppress the generation of Joule heat during energization and make it easy to dissipate the generated heat, and bending workability that does not cause cracking even if complicated bending work is required. . In recent years, as electric / electronic devices have become smaller, thinner, and lighter, components used in electric / electronic devices have also been reduced in size. Due to the miniaturization of such parts, the current density in electrodes and the like used for various parts is increasing, and there is an increasing demand for using a material having better conductivity than before. In addition, in-vehicle components are required to withstand use in a higher temperature environment, so there is an increasing demand for materials having high stress relaxation resistance. Cu-Cr-Zr alloy materials and the like have been proposed as materials that can meet such demands for high conductivity and stress relaxation resistance.

  Conventionally, as a Cu—Cr—Zr alloy material, 0.05 to 0.40% Cr, 0.03 to 0.25% Zr, 0.10 to 1.80% Fe, 10 to 0.80% Ti, Fe / Ti weight ratio is 0.66 to 2.6 in the range of 0.10% ≦ Ti ≦ 0.60%, and 0.60% < In the range of Ti ≦ 0.80%, the Fe / Ti weight ratio is 1.1 to 2.6, the balance is made of Cu and inevitable impurities, and the solution treatment at a temperature of less than 950 ° C. This includes cold working at a working degree of 90%, aging treatment at a temperature of 300 to 580 ° C., cold working at a working degree of 16 to 83%, and annealing at a temperature of 350 to 700 ° C. A manufacturing method of a copper alloy manufactured by sequentially performing manufacturing is known (see, for example, Patent Document 1).

  Since the manufacturing method of the copper alloy described in Patent Document 1 includes the above-described configuration, a copper alloy having excellent properties such as tensile strength, elongation, and electrical conductivity can be provided.

JP 7-258805 A

  However, since the copper alloy manufacturing method described in Patent Document 1 performs solution treatment at a high temperature, the metal structure of the parent phase may be coarsened, and the coarsening of the metal structure occurs. In some cases, partial softening of the copper alloy and deterioration of bending workability may occur.

  Accordingly, an object of the present invention is to provide a copper alloy manufacturing method and a copper alloy capable of manufacturing a copper alloy excellent in strength and bending workability while maintaining the electrical conductivity and stress relaxation resistance of the Cu-Cr-Zr-based copper alloy. Is to provide.

  In order to achieve the above object, the present invention casts a copper alloy material by melting copper (Cu), chromium (Cr) added to copper, zirconium (Zr), and tin (Sn). 80% or more and 90% of the melting process, the hot working process for forming a plate material having a rolled structure by hot working the copper alloy material, the heat treatment process for heat treating the plate material, and the heat treated plate material. An intermediate rolling process in which an intermediate plate is formed by cold rolling with a working degree of less than, an aging treatment process in which the intermediate plate is subjected to an aging treatment, and a workability of 20% to 40% in the intermediate plate having been subjected to the aging treatment There is provided a method for producing a copper alloy comprising a finish rolling step for performing cold rolling and a strain relief annealing step for subjecting the intermediate plate subjected to cold rolling to a heat treatment.

  Further, in the above copper alloy manufacturing method, the heat treatment step is a heat treatment at a temperature that reduces the rolling structure by generating recrystallization in the rolling structure while suppressing the coarsening of the crystal grain size of the crystals in the plate material. It can be applied to the plate material.

  In the copper alloy manufacturing method, in the heat treatment step, the plate material may be subjected to heat treatment at a temperature at which the crystal grain size of the copper alloy contained in the copper alloy is 50 μm or less.

  Moreover, it is preferable that the temperature of the heat processing is 700 degreeC or more and less than 950 degreeC in the manufacturing method of the said copper alloy.

  Moreover, the manufacturing method of the said copper alloy can perform an aging treatment process at the temperature of 390 degreeC or more and 450 degrees C or less to an intermediate board material.

  Moreover, the manufacturing method of the said copper alloy can perform the heat processing of the temperature of 400 degreeC or more and 600 degrees C or less to an intermediate | middle board | plate material at a strain relief annealing process.

  Further, in the method for producing the copper alloy, in the melting step, 0.1 wt% or more and 0.4 wt% or less of Cr, 0.02 wt% or more and 0.2 wt% or less of Zr, It is preferable to cast a copper alloy material containing not less than 0.3% and not more than 0.3% by weight of Sn.

  Moreover, the manufacturing method of the said copper alloy is further equipped with the rough rolling process which cold-rolls to a board | plate material, and the heat processing process can heat-process the board | plate material which passed through the rough rolling process.

  In the method for producing a copper alloy, in the heat treatment step, the plate material may be subjected to a heat treatment at a temperature at which the crystal grain size of the copper alloy contained in the copper alloy is 30 μm or less.

  Moreover, it is preferable that the temperature of the heat processing is 700 degreeC or more and less than 850 degreeC in the manufacturing method of the said copper alloy.

  In order to achieve the above object, the present invention provides chromium (Cr) of 0.1 wt% or more and 0.4 wt% or less, and zirconium (Zr) of 0.02 wt% or more and 0.2 wt% or less. A copper alloy containing 0.01 wt% or more and 0.3 wt% or less of tin (Sn), with the balance being copper (Cu) and unavoidable impurities is provided.

  The copper alloy preferably has a conductivity of 80% IACS or higher and a strength of 550 MPa or higher.

  According to the copper alloy manufacturing method and copper alloy according to the present invention, a copper alloy excellent in strength and bending workability can be manufactured while maintaining the electrical conductivity and stress relaxation resistance of the Cu-Cr-Zr copper alloy. A method for producing a copper alloy and a copper alloy can be provided.

It is a figure which shows the flow of the manufacturing process of the copper alloy which concerns on embodiment of this invention.

[Embodiment]
(Copper alloy)
The copper alloy which concerns on embodiment of this invention is a copper alloy used for electrical / electronic components, such as a connector, as an example. Specifically, the copper alloy according to the present embodiment includes 0.1 wt% or more and 0.4 wt% or less of chromium (Cr) and 0.02 wt% or more and 0.2 wt% or less of zirconium (Zr). And 0.01 wt% or more and 0.3 wt% or less of tin (Sn), with the balance being copper (Cu) and inevitable impurities.

  Cr has a function of improving the strength and heat resistance of the copper alloy by being present in a state where Cr alone precipitates in the parent phase of the copper alloy. Zr forms a compound with Cu. And the said compound has the function to improve the intensity | strength and heat resistance of a copper alloy by existing in the state which precipitated in the parent phase of a copper alloy. Further, Sn has a function of improving the strength of the copper alloy, and when added to copper together with Cr and Zr, the strength of the copper alloy is further improved.

  And the copper alloy which concerns on this Embodiment has the electrical conductivity of 80% IACS or more, and the intensity | strength of 550 Mpa or more.

(Copper alloy manufacturing method)
FIG. 1 shows an example of the flow of manufacturing a copper alloy according to an embodiment of the present invention.

  First, copper, a predetermined amount of Cr added to copper, a predetermined amount of Zr, and a predetermined amount of Sn are melted using a low-frequency melting furnace to cast an ingot as a copper alloy material (melting). Manufacturing process: Step 10, hereinafter, the step is referred to as “S”). Specifically, the melting step includes 0.1 wt% or more and 0.4 wt% or less of Cr, 0.02 wt% or more and 0.2 wt% or less of Zr, and 0.01 wt% or more and 0.3 wt% or less. A copper alloy material containing Sn or less of Sn is cast. As copper, oxygen-free copper can be used.

  Next, the ingot is subjected to hot working (for example, hot rolling) at a temperature of about 900 ° C. to form a plate material having a rolled structure (hot working step: S20). Here, the processing in the hot working step has a solutioning function in which the precipitates of Cr and Zr in the ingot obtained in the melting step are once dissolved in the matrix. The solution forming function in this hot working process makes it possible to make the distribution state of the Cr and Zr precipitates produced in the aging treatment process, which will be described later, in the copper alloy more uniform, and the precipitates to be in a fine state. Can be.

  Next, the plate material is cold-rolled (rough rolling step: S30). Subsequently, an annealing treatment as a heat treatment is performed on the cold-rolled plate material (heat treatment step: S40). The heat treatment step is a step of rapidly cooling the plate material after subjecting the plate material to a heat treatment at a temperature that reduces the rolled structure by generating recrystallization in the rolled structure while suppressing the coarsening of the crystal grain size of the crystals in the plate material. Including. Specifically, in the heat treatment step, the plate material is subjected to heat treatment at a temperature at which the crystal grain size of the copper alloy contained in the copper alloy is 50 μm or less, preferably 30 μm or less, and then rapidly cooled. The value of the crystal grain size is a value after quenching after heat treatment. By the heat treatment in the heat treatment step, the distortion generated in the hot working step can be eliminated and the bending workability can be improved.

  In addition, the crystal grain diameter in a copper alloy can be refined | miniaturized by a heat treatment process, and the intensity | strength of the copper alloy manufactured can also be improved. Here, the heat treatment in the heat treatment step is performed in a temperature range of 700 ° C. or higher and lower than 950 ° C., preferably 700 ° C. or higher and lower than 850 ° C. By performing heat treatment in this temperature range, recrystallization occurs, and as described above, the rolled structure generated in the hot working process disappears, and the crystal grain size of the copper alloy is 50 μm or less (that is, the heat treatment temperature is 700 ° C. or more). (When it is lower than 950 ° C.), preferably 30 μm or less (that is, when the temperature of the heat treatment is 700 ° C. or higher and lower than 850 ° C.). Thereby, when bending is performed on the copper alloy to be manufactured, rough skin at the bent portion can be suppressed.

  Subsequently, the heat-treated plate material is cold-rolled with a working degree of 80% or more and less than 90% to form an intermediate plate material (intermediate rolling step: S50). Further, the intermediate plate material is subjected to an aging treatment at a temperature of 390 ° C. or more and 450 ° C. or less for a predetermined time, and then slowly cooled (aging treatment step: S60). Thereby, work hardening and precipitation hardening can be combined and characteristics, such as intensity | strength of a copper alloy manufactured and electrical conductivity, can be improved. Here, by controlling the workability to 80% or more in the intermediate rolling process, the intermediate plate material is work-hardened and the strength is improved. Further, a large number of lattice defects are introduced into the intermediate plate by cold rolling in the intermediate rolling process. These lattice defects function as a starting point for precipitation of precipitates having a size of several nanometers (for example, a compound of Cr and Cu, a compound of Zr and Cu) in the precipitation hardening in the aging treatment step. Has a function of promoting the uniform dispersion of precipitates (that is, precipitates of a compound of Cr and Cu, a compound of Zr and Cu, etc.) in the intermediate plate.

  Further, in the cold working in the intermediate rolling process, the ductility of the intermediate plate material is lowered, but the aging treatment process can recover the lowered ductility. Here, the temperature of the aging treatment is carried out at 390 ° C. or more for the purpose of sufficiently depositing the precipitate in the intermediate plate. Moreover, the temperature of an aging treatment is implemented at the temperature of 450 degrees C or less for the purpose of suppressing the fall of the intensity | strength by softening of an intermediate board material. In the aging treatment step, precipitates precipitate in the intermediate material while being maintained at a predetermined temperature. And the intensity | strength of the copper alloy manufactured and electrical conductivity can be improved by depositing a fine precipitate in an intermediate material by an aging treatment process.

  Next, cold rolling with a working degree of 20% or more and 40% or less is performed on the intermediate plate subjected to the aging treatment (finish rolling step: S70). The finish rolling step is carried out at a workability of 20% or more that can make work hardening sufficiently for the purpose of making the obtained copper alloy have a sufficient strength. In addition, the finish rolling step is performed at a workability of 40% or less for the purpose of suppressing a decrease in conductivity, a decrease in ductility, and a decrease in bending workability of the manufactured copper alloy. Through the finish rolling process, the intermediate plate subjected to the aging treatment is work-hardened to improve the strength.

  Subsequently, a heat treatment at a temperature of 400 ° C. or higher and 600 ° C. or lower is performed for a short time (for example, about 1 minute) on the intermediate plate that has been cold-rolled (distortion annealing step: S80). In the strain relief annealing process, a heat treatment at a temperature of 400 ° C. or higher is performed for the purpose of providing the produced copper alloy with sufficient springiness and ductility. In addition, the strain relief annealing step is performed at a temperature of 600 ° C. or lower for the purpose of preventing a decrease in strength of the copper alloy produced due to re-dissolution of precipitates in the copper alloy. Heat treatment is performed. The copper alloy according to the present embodiment in which the spring property is improved and the ductility reduced by the finish rolling process is recovered by the strain relief annealing process is obtained. Through the above steps, the copper alloy according to the present embodiment is manufactured.

(Effect of embodiment)
The copper alloy according to the embodiment of the present invention is manufactured through the above steps, and the rolled structure disappears by a heat treatment at 700 ° C. or more and less than 950 ° C., so that the crystal grain size has a crystal structure of 50 μm or less. Therefore, it has excellent conductivity, strength, bending workability, stress relaxation resistance, and well-balanced characteristics. Therefore, it provides a copper alloy that contributes to miniaturization and high integration of electrical and electronic parts. be able to.

  The copper alloys according to Examples 1 to 3 manufactured based on the embodiment and the copper alloys according to Comparative Examples 1 to 4 will be described. Table 1 shows the processing conditions in the heat treatment process of the copper alloys according to Examples 1 to 3 and Comparative Examples 1 and 2, and the characteristics of the copper alloy obtained by manufacturing. The conditions in the intermediate rolling process of the copper alloy which concerns on Example 1, and the copper alloy which concerns on Comparative Examples 3-4, and each characteristic of the copper alloy obtained by manufacture are shown.

  A copper alloy containing 0.25% by mass of Cr, 0.1% by mass of Zr, and 0.15% by mass of Sn is melted in a low frequency melting furnace using oxygen-free copper as a base material. Cast into ingot (melting process). Next, the ingot was hot-worked (hot work process) to a thickness of 8 mm, and then cold-rolled (rough rolling process) to 2.5 mm. Next, an annealing treatment at 700 ° C. was performed on the cold-rolled alloy material (heat treatment step). And after implementing cold rolling (intermediate rolling process) with a workability of 83%, aging treatment was performed by heating at 430 ° C. for 2 hours (aging treatment process). After the aging treatment, the copper alloy according to Example 1 was subjected to cold rolling (finish rolling process) with a workability of 40% and strain relief annealing (strain relief annealing process) by heating at 450 ° C. for 60 seconds. Manufactured.

  A material having the same composition as in Example 1 is melted, and only the heat treatment conditions in the heat treatment process are changed, and the same process as in Example 1 is performed, and Example 2 and Example 3, and Comparative Examples 1 and 2 are involved. A copper alloy was produced.

  Moreover, the material of the same composition as Example 1 is melted, the working degree in the intermediate rolling process and the working degree in the finish rolling process are changed, and the same process as that in Example 1 is followed through Comparative Example 3 and Comparative Example 4 The copper alloy which concerns on was manufactured.

  Next, about the copper alloys which concern on Examples 1-3 and Comparative Examples 1-2, a part of copper alloy immediately after strain relief annealing was sampled, and it was set as the test piece. And the cross section perpendicular | vertical to the rolling direction of a test piece was grind | polished and etched. Using the test piece thus obtained, the presence or absence of a rolled structure was observed, and for the test piece where the rolled structure was not observed, the average value of the crystal grains in the plate width direction was calculated, and the average crystal grain was calculated. The diameter.

  Furthermore, the tensile test was implemented about the copper alloy which concerns on Examples 1-3 and Comparative Examples 1-4. In the tensile test, tensile strength and elongation in a direction parallel to the rolling direction were measured according to JIS Z 2201. Further, in accordance with JIS H 3130, a Bad Way (bending axis is the same direction as the rolling direction) was subjected to a W bending test, and the ratio of the minimum bending radius (MBR) to the plate thickness (t) at which no cracks occurred. The MBR / t value was calculated. The results of the above characteristics are shown in Tables 1 and 2.

  Referring to Tables 1 and 2, the copper alloys according to Examples 1 to 3 had a conductivity of 82% IACS or higher and a high strength of about 550 MPa. Furthermore, it was shown that the copper alloys according to Examples 1 to 3 did not generate cracks in the W bending test and had good bending workability.

  On the other hand, the copper alloy which concerns on the comparative example 1 is a copper alloy manufactured through the heat treatment process of temperature lower than the heat treatment conditions of the heat treatment process in Examples 1-3. The copper alloy according to Comparative Example 1 was observed to have a rolled structure remaining therein, indicating that sufficient bending workability could not be obtained due to work strain increased by cold rolling. Moreover, the copper alloy which concerns on the comparative example 2 is a copper alloy manufactured through the heat processing process of temperature higher than the heat processing conditions of the heat processing process in Examples 1-3. In the copper alloy according to Comparative Example 2, it was observed that the average crystal grain size after the heat treatment was coarsened, indicating that sufficient tensile strength and bending workability could not be obtained.

  The copper alloy which concerns on the comparative example 3 is a copper alloy manufactured by the degree of workability of the cold rolling before an aging treatment larger than the degree of work in manufacture of the copper alloy which concerns on Examples 1-3. The copper alloy according to Comparative Example 3 was found to have a low tensile strength and poor bending workability.

  The copper alloy which concerns on the comparative example 4 is a copper alloy manufactured by the workability of the cold rolling before an aging treatment with the workability smaller than the workability in manufacture of the copper alloy which concerns on Examples 1-3. In the copper alloy according to Comparative Example 4, the effect of the aging treatment is not sufficiently heard due to insufficient introduction of dislocations by cold rolling before the aging treatment, and the conductivity and tensile strength are small, and the bending It was shown that the processability is not good.

  While the embodiments and examples of the present invention have been described above, the embodiments and examples described above do not limit the invention according to the claims. It should be noted that not all combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention.

Claims (10)

Copper (Cu), chromium (Cr) added to the copper, zirconium (Zr), and tin (Sn) are melted , and 0.1 wt% or more and 0.4 wt% or less of chromium ( Cr), 0.02 wt% or more and 0.2 wt% or less of zirconium (Zr), and 0.01 wt% or more and 0.3 wt% or less of tin (Sn), with the balance being copper (Cu ) And an inevitable impurity, a melting process for casting a copper alloy material,
A hot working step of forming a plate material having a rolled structure by hot working the copper alloy material;
A heat treatment step of subjecting the plate material to a heat treatment at a temperature of 700 ° C. or higher and lower than 950 ° C . ;
An intermediate rolling step of forming an intermediate plate by subjecting the plate subjected to the heat treatment to cold rolling with a working degree of 80% or more and less than 90%;
An aging treatment step of applying an aging treatment to the intermediate plate;
A finish rolling step of subjecting the intermediate plate subjected to the aging treatment to cold rolling with a working degree of 20% or more and 40% or less;
The manufacturing method of a copper alloy provided with the distortion removal annealing process which heat-processes the said intermediate plate material in which the said cold rolling was given.   In the heat treatment step, the plate material is subjected to the heat treatment at a temperature that reduces the rolled structure by generating recrystallization in the rolled structure while suppressing the coarsening of the crystal grain size of the crystals in the plate material. Item 2. A method for producing a copper alloy according to Item 1.   The said heat processing process is a manufacturing method of the copper alloy of Claim 2 which performs the said heat processing of the temperature from which the crystal grain diameter of the copper alloy contained in a copper alloy becomes 50 micrometers or less. The said aging treatment process is a manufacturing method of the copper alloy of Claim 3 which performs the said aging treatment of the temperature of 390 degreeC or more and 450 degrees C or less to the said intermediate plate material. The said strain relief annealing process is a manufacturing method of the copper alloy of Claim 4 which performs the said heat processing of the temperature of 400 to 600 degreeC to the said intermediate plate material. It further comprises a rough rolling step for cold rolling the plate material,
The said heat processing process is a manufacturing method of the copper alloy of Claim 5 which performs the said heat processing to the said board | plate material which passed through the said rough rolling process. The said heat processing process is a manufacturing method of the copper alloy of Claim 6 which performs the said heat processing of the temperature from which the crystal grain diameter of the copper alloy contained in a copper alloy becomes 30 micrometers or less. The method for producing a copper alloy according to claim 7 , wherein a temperature of the heat treatment is 700 ° C or higher and lower than 850 ° C. Copper (Cu), chromium (Cr) added to the copper, zirconium (Zr), and tin (Sn) are melted, and 0.1 wt% or more and 0.4 wt% or less of chromium ( Cr), 0.02 wt% or more and 0.2 wt% or less of zirconium (Zr), and 0.01 wt% or more and 0.3 wt% or less of tin (Sn), with the balance being copper (Cu ) And an inevitable impurity, a melting process for casting a copper alloy material,
A hot working step of forming a plate material having a rolled structure by hot working the copper alloy material;
A heat treatment step of subjecting the plate material to a heat treatment at a temperature of 700 ° C. or higher and lower than 950 ° C .;
An intermediate rolling step of forming an intermediate plate by subjecting the plate subjected to the heat treatment to cold rolling with a working degree of 80% or more and less than 90%;
An aging treatment step of applying an aging treatment to the intermediate plate;
A finish rolling step of subjecting the intermediate plate subjected to the aging treatment to cold rolling with a working degree of 20% or more and 40% or less;
A strain relief annealing step of performing a heat treatment on the intermediate plate subjected to the cold rolling;
Manufactured by a copper alloy manufacturing method comprising:
0.1 wt% to 0.4 wt% chromium (Cr), 0.02 wt% to 0.2 wt% zirconium (Zr), 0.01 wt% to 0.3 wt% A copper alloy containing tin (Sn) and the balance being copper (Cu) and inevitable impurities. The copper alloy according to claim 9 , which has a conductivity of 80% IACS or more and a strength of 550MPa or more.

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