JP5050226B2 - Manufacturing method of copper alloy material - Google Patents

Description

The present invention is strength to be used as electric and electronic parts materials such as connectors, elastic, a good copper alloy material of the conductive relates to a process for the preparation of a copper alloy sheet material as specifically improving press-punching properties.

  In recent years, with the development of electronics, the electrical wiring of various machines has become complicated and highly integrated, and accordingly, the demand for copper products is increasing as a material for manufacturing electrical and electronic parts such as connectors. Since these copper products are often punched by high-speed pressing using a mold, the materials for electric and electronic parts are excellent in press punchability in addition to strength and conductivity. Desired. At the time of pressing, the material undergoes shear deformation by a punch of a mold, and then breaks due to generation of a crack from the blade edge and is punched into a predetermined shape.

  However, it is difficult to obtain the desired shape with high accuracy due to deformation of the material due to press impact or anisotropy in the material, and good dimensional accuracy has been achieved by various measures in the pressing method. Yes. In general, the press punched surface is not smooth, and a level difference is caused by a sag portion, a sheared portion, and a broken portion. However, improving the smoothness of the press surface is also an important issue. For example, in the case of a tuning fork terminal or a connection pin, it is used in such a manner that the punched surface becomes a contact portion (current-carrying portion). Problems such as insufficient holding power occur.

Conventionally, as measures to improve the dimensional accuracy of press-formed products, we have responded by improving the lubricity by punch and die material and shape, press speed, press lubricant, and setting the appropriate clearance for each copper alloy. . However, there are many cases where good dimensional accuracy cannot be obtained even if these measures are taken, and efforts to improve press workability from the material side are also important.
Patent Document 1 describes that press formability is improved by controlling the crystal orientation of a material.

JP 2002-180165 A

  According to the method of Patent Document 1, the level of press formability is improved from the material surface, and particularly, an excellent effect in reducing wear of the press mold is exhibited. However, sufficient attention has not yet been given to the “dimensional accuracy” of the punched parts, and no fundamental improvement has been achieved. In view of such a current situation, an object of the present invention is to stably improve the dimensional accuracy particularly after punching in a copper alloy sheet material used for a current-carrying part such as a connector.

The above-mentioned purpose is to sequentially apply the processing and thermal history of “[1] cold rolling before finishing, [2] heat treatment before finishing, [3] cold rolling after finishing, [4] finishing heat treatment” to the intermediate product of copper alloy sheet material. Te upon finishing the sheet material, [2] and [4] are step a is thus achieved to the preparation of the copper alloy material carried out in each of the following conditions.
[2] Pre-finish heat treatment: Vickers hardness after cold rolling before finish of [1] is set to H ₀ (HV), and the material having the hardness H ₀ is heated and held for holding time A (min). When the heating holding temperature at which _0.8 H ₀ (HV) is set to T _0.8 (° C.),
Holding temperature: T _0.8 +20 (° C.) or more, T _0.8 +60 (° C.) or less,
Holding time: A (min),
Perform under conditions that satisfy
[4] Finish heat treatment: Performed at a holding temperature and holding time at which the Y value defined by the following formula (1) is 10 or less.
Y = | Young modulus in the L direction / 0.2% yield strength in the L direction−Young's modulus in the T direction / 0.2% yield strength in the T direction |
However, the L direction means a direction parallel to the rolling direction, and the T direction means a direction perpendicular to the rolling direction. The unit of Young's modulus and 0.2% proof stress is N / mm ² .

Here, as the copper alloy sheet material intermediate product, a copper alloy having any of the following compositions is employed.
A composition comprising , by mass%, Sn: 0.01 to 10%, Zn: 8 to 30%, and satisfying the total content of each element: 30% or less, and the balance Cu and inevitable impurities.
-By mass%, Sn: 0.01 to 10%, Zn: 8 to 30%, P: 0.01 to 0.2%, and one or more of Ni, Fe, Mg, and Co in total 0 A composition comprising 0.01 to 3% and a total content of each of the above elements: 30% or less, the balance being Cu and inevitable impurities.
-By mass%, Sn: 0.01 to 10%, Zn: 8 to 30%, P: 0.01 to 0.2%, Ni: 0.01 to 3%, and the total content of each of the above elements Amount: A composition satisfying 30% or less and composed of the balance Cu and inevitable impurities.
-By mass%, Sn: 0.01 to 10%, P: 0.01 to 0.2%, and one or more of Ni, Fe, Mg, Co are contained in a total of 0.01 to 3%. And the total content of said each element: The composition which satisfy | fills 30% or less, and consists of remainder Cu and an unavoidable impurity.
-By mass%, Sn: 0.01 to 10%, P: 0.01 to 0.2%, Ni: 0.01 to 3%, and the total content of the above elements: 30% or less , Balance Cu and inevitable impurities.

In particular, a method for producing a copper alloy material in which the steps [1] and [3] are performed under the following conditions is provided.
[1] Cold rolling before finishing: Cold rolling is performed at a rolling rate of 60% or more.
[3] Finish cold rolling: Cold rolling is performed at a rolling rate of 50% or more.
“Processing / thermal history” is a process that brings about changes in the metallographic state and various physical and mechanical properties. Therefore, a process that does not change the metallographic state and physical / mechanical characteristics, such as pickling, may be appropriately inserted during or after the processes [1] to [4].

  According to the present invention, it is possible to provide a copper alloy having strength, elasticity, and conductivity required for a current-carrying member such as a connector, which is extremely excellent in dimensional accuracy after press punching. In particular, it was possible to improve the smoothness of the shear surface and the punching roundness by reducing the anisotropy. Therefore, the present invention contributes to improving the quality and performance of current-carrying parts from the material aspect.

To improve dimensional accuracy after press punching (hereinafter referred to as “press punch dimensional accuracy”)
i) increase the smoothness of the press shear surface;
ii) increasing the roundness of the punched circle formed by circular punching,
is important.

As a result of studying various measures for realizing i) ii) from the viewpoint of materials, the inventors have found that i) refines crystal grains to 10 μm or less, and has 0.2% proof stress on various plate surfaces. In ii), in addition to crystal refinement and 0.2% yield strength improvement, it is extremely effective to optimize the balance of 0.2% yield strength and Young's modulus. I found out.
Hereinafter, matters for specifying the present invention will be described.

[Average crystal grain size]
At the time of pressing, the material undergoes “shear deformation” by the punch of the die, and then “breaking deformation” due to generation of a crack from the blade edge, and is punched into a predetermined shape.

Shear deformation proceeds mainly by intragranular slip, but the direction of shear slip is determined crystallographically, and the press surface generated by shear deformation is constituted by the slip surface of each crystal grain. Since the orientation of crystal grains is not uniform, the press surface generated by shear deformation is not smooth, and irregularities depending on the crystal grain size are formed.
The fracture deformation proceeds by intragranular fracture, but intragranular fracture is likely to occur on the slip surface. For this reason, the unevenness of the press surface caused by fracture deformation also depends on the crystal grain size as in the case of shear slip.

  For these reasons, it is necessary to refine the crystal grain size in order to improve the smoothness of the press shear surface. Detailed investigations by the inventors have revealed that it is extremely effective to set the average crystal grain size to 10 μm or less in the copper alloy sheet material subjected to press punching.

[0.2% yield strength]
During the pressing process, the material is compressed before shear deformation, and a sag portion is formed by tensile stress. If the 0.2% proof stress is small, the resistance to compressive stress will be small and the amount of sag will be large. As a result, the smoothness of the press shear surface is deteriorated. Also, if the 0.2% proof stress is small, the material will be greatly deformed by the impact during pressing, resulting in poor dimensional accuracy.

  In a copper alloy that is often manufactured and tempered by rolling, 0.2% yield strength generally shows anisotropy, and in an orientation with a low 0.2% yield strength, sagging and deformation amount increase. Therefore, in order to obtain excellent dimensional accuracy, it is necessary to have a sufficiently large 0.2% proof stress in various directions with respect to the rolling direction. In the case of a copper alloy manufactured and tempered by rolling, the 0.2% proof stress value is the minimum value in the direction parallel to the rolling direction (L direction) or perpendicular to the rolling direction (T direction). If the 0.2% yield strength of the direction is high, it can be said that the 0.2% yield strength is high in all directions with respect to the rolling direction. That is, in order to obtain good press punching dimensional accuracy, it is important that both the 0.2% proof stress in the L direction and the T direction show high values.

According to the research by the inventors, in order to stably obtain the press punching dimensional accuracy desired for the copper alloy for current-carrying parts, at least 0.2% proof stress, the values in both the L direction and the T direction are both 650 N / mm. It is necessary to be ² or more.

〔Young's modulus〕
Young's modulus has a great influence on press punching dimensional accuracy as well as 0.2% proof stress. The stress generated by the compression in the initial stage of the press is determined by the Young's modulus. When the Young's modulus is high, the stress is high, and when the Young's modulus is low, the stress is low. The amount of deformation due to the stress generated here is determined by the balance between Young's modulus and 0.2% proof stress. In addition, since the transition from compressive deformation to shear deformation is initiated by the yielding of the material at the punch edge, the balance between Young's modulus and 0.2% proof stress is important for the start of shear deformation (end of the sag portion). Become.

  The value of Young's modulus is mainly determined by the alloy composition, but the Young's modulus of copper alloys, which are often affected by the manufacturing process and are often manufactured and tempered by rolling, shows anisotropy. It is. As described above, the 0.2% proof stress also exhibits anisotropy, but since the degree is not the same as the Young's modulus, the balance between the Young's modulus and the 0.2% proof stress also exhibits anisotropy. In other words, it has been found that the press punching dimensional accuracy cannot always be improved sufficiently merely by the fact that the 0.2% yield strength anisotropy is small and the Young's modulus anisotropy is small. The material deformation due to pressing is determined by the balance between Young's modulus and 0.2% proof stress. To obtain excellent dimensional accuracy by press molding, "Anisotropy in the balance between Young's modulus and 0.2% proof stress" Is small.

As a result of various studies, when the absolute value of the difference between “Young's modulus / 0.2% proof stress” in the L direction and the T direction is defined as Y as anisotropy in the balance, the Y value is 10 or less. In such a copper alloy material, it has been found that press punching dimensional accuracy (particularly roundness) can be stably improved. That is, it is important to give the characteristic that the Y value defined by the following formula (1) is 10 or less. The provision of this characteristic can be realized by a manufacturing method described later.
Y = | Young modulus in the L direction / 0.2% yield strength in the L direction−Young's modulus in the T direction / 0.2% yield strength in the T direction |
Here, the value of the same unit system (for example, N / mm ² ) is adopted for each Young's modulus and 0.2% proof stress value.

[Chemical composition]
Maintaining the basic characteristics (conductivity, tensile strength, 0.2% proof stress, elongation, etc.) required for current-carrying members such as connectors, and then the Young's modulus as shown in the above formula (1) and 0. In order to achieve a good balance of 2% yield strength, the present invention contains one or more of Sn, Ni, P, Zn, Fe, Mg, and Co in a total range of 0.01 to 30% by mass. A copper alloy having a chemical composition consisting of Cu and inevitable impurities is adopted as the balance. If the total amount of Sn, Ni, P, Zn, Fe, Mg, and Co is less than 0.01% by mass, the electrical conductivity increases, but it is difficult to obtain properties such as tensile strength and 0.2% proof stress. Conversely, if the total amount exceeds 30% by mass, the tensile strength and the 0.2% proof stress are improved, but the conductivity is lowered. Therefore, the total amount of Sn, Ni, P, Zn, Fe, Mg, and Co needs to be in the range of 0.01 to 30% by mass. However, each element shall be the amount in the following range.

Sn is dissolved in the Cu matrix to improve strength and elasticity. Further, since the Young's modulus has a great influence and the Young's modulus can be reduced by adding Sn, the addition of Sn is advantageous in obtaining good press punchability. In order to sufficiently bring out such an effect, it is desirable to secure an Sn content of 0.01% by mass or more. On the other hand, if the Sn content exceeds 10% by mass, the electrical conductivity is remarkably lowered, and the castability and hot workability are adversely affected. Thus the addition of Sn must be in a range of 10 wt% or less, shall be the 0.01 to 10 mass% in the present invention. 0.1-4.5 mass% is still more preferable.

Zn is dissolved in the Cu matrix to improve strength and elasticity. Moreover, in addition to the effect | action which raises the deoxidation effect of a molten metal and reduces the solute oxygen element in Cu matrix, the effect | action which improves solder weather resistance and migration resistance is exhibited . However, there is a decline in the conductivity when the Zn content exceeds 30% by weight is an issue, also with solderability becomes poor, even in combination with other elements stress corrosion cracking susceptibility becomes high It is not preferable. In the present invention, it intends rows in the range of 8-30% by weight when adding Zn. It is more preferable to ensure the Zn content of 8 to 28% by mass.

P acts as a deoxidizer for molten metal during melting and casting, and has the effect of increasing conductivity by further forming a compound with Ni, Fe, Mg, or Co and dispersing it, and further improving hardness and elasticity. . In order to sufficiently obtain such an action, it is desirable to ensure a P content of 0.01% by mass or more. However, if the P content exceeds 0.2% by mass, the decrease in conductivity will increase even in the presence of Ni, Fe, Mg, or Co, and the solder weather resistance and hot workability will be deteriorated. Become. When adding P is thus shall be the 0.01 to 0.2 wt%.
It is desirable.

Ni, Fe, Mg, and Co are precipitated together with P to form a compound and improve strength, elasticity, and heat resistance. Further, the pinning effect by the precipitate is exhibited, and the growth of crystal grains is hindered, so that fine crystal grains can be easily obtained. For example, in the case of Ni, the above effect can be obtained by precipitation of the Ni—P compound, but the same effect can be obtained even if Ni is replaced by Fe, Mg, Co. In order to sufficiently exhibit such effects, it is desirable that the total content of Ni, Fe, Mg, and Co is 0.01% by mass or more. However, in order to maintain conductivity and prevent an appropriate heat treatment temperature from being increased during production, all of these elements need to be in a range of 3% by mass or less. In the present invention Ni, Fe, Mg, when adding Co is you N i, Fe, Mg, and 0.01 to 3 wt% of the total content of Co.

[Production method]
In general, copper alloy materials for energized parts used in electrical and electronic equipment are usually melted, cast, and hot-rolled, and then the process of “cold-rolling and heat treatment” is repeated to finish a plate material with a predetermined thickness. Used for molding such as pressing. The copper alloy material excellent in press punching dimensional accuracy of the present invention can basically be manufactured in such a flow. However, in the production of the copper alloy material of the present invention, in order to realize the above-mentioned structure (crystal grain refinement) and characteristics (improvement of 0.2% yield strength, balance optimization between Young's modulus and 0.2% yield strength). Need some ingenuity.

As a result of detailed studies, the inventors have found that the desired structure and characteristics can be industrially sufficiently realized by controlling the production conditions in the process of repeating “cold rolling and heat treatment”. That is, among the “cold rolling and heat treatment” processes, the heat treatment conditions are particularly strictly controlled in the last two “cold rolling and heat treatment” processes. Further, it is desirable to appropriately control the rolling rate even in the cold rolling prior to the heat treatment.
Specifically, when finishing the plate by sequentially applying the processing and thermal history of “[1] cold rolling before finishing, [2] heat treatment before finishing, [3] cold rolling finishing, [4] finishing heat treatment”, The heat treatment conditions [2] and [4] or the cold rolling conditions [1] and [3] are devised.

  About the melting | dissolving of an upper process, casting, hot rolling, and the cold rolling and heat processing in the intermediate | middle stage performed as needed, what is necessary is just to follow the manufacturing method of a conventionally general copper alloy. In addition, a process without processing / heat history such as pickling can be appropriately inserted.

In the present specification, the last two “cold rolling and heat treatment” steps are referred to as “[1] pre-finish cold rolling, [2] pre-finish heat treatment, [3] finish cold rolling, and [4] finish heat treatment”. It is described.
Among these, in the cold rolling before finishing of [1], it is desirable to secure a relatively large cold rolling rate so that a fine grain structure can be obtained by the heat treatment of [2]. A rolling texture is formed by increasing the cold rolling rate, and a recrystallized texture can be obtained by the heat treatment [2]. By imparting anisotropy to the material such as a rolled texture or a recrystallized texture, [4] the difference in L direction and T direction in the amount of change in Young's modulus and 0.2% proof stress during heat treatment increases. A Y value of 10 or less is easily obtained. The finish rolling of [1] is desirably performed at a cold rolling rate of 60% or more, and may be a cold rolling rate of 60 to 90%, for example.

  In the pre-finish heat treatment of [2], a fine crystal grain structure having an average grain size of 10 μm or less is obtained by recrystallization. Further, coarsening of recrystallized grains is prevented and a recrystallized texture is maintained. The crystal grain size after recrystallization generally becomes smaller as the processing rate before recrystallization annealing becomes larger, and becomes smaller as the annealing temperature becomes lower and the annealing time becomes shorter. However, adjusting to fine crystal grains by finishing the heat treatment in a short time at a temperature at which the crystal grain growth rate is high is not a good measure for obtaining a stable structure. Therefore, it is desirable to secure a heat treatment time of at least 10 seconds.

According to the research by the inventors, in order to stably obtain a fine recrystallized structure having an average crystal grain size of 10 μm or less, the heat treatment temperature of [2] is set so that the Vickers hardness after the heat treatment is 80% before the heat treatment. It was found that the temperature should be set in the range of + 20 ° C. to + 60 ° C. with _{respect to the} heat treatment temperature T _0.8 (° C.). However, the heating holding time is the same as when _T0.8 is set. That is, the pre-finish heat treatment [2] may be performed under the following conditions.
[2] Pre-finish heat treatment: Vickers hardness after cold rolling before finish of [1] is set to H ₀ (HV), and the material having the hardness H ₀ is heated and held for holding time A (min). When the heating holding temperature at which _0.8 H ₀ (HV) is set to T _0.8 (° C.),
Holding temperature: T _0.8 +20 (° C.) or more, T _0.8 +60 (° C.) or less,
Holding time: A (min),
Perform under conditions that satisfy

Such proper heat treatment conditions vary depending on the chemical composition and the cold rolling rate of [1]. Actually, a simulation experiment using a copper alloy having a target composition is performed in advance to collect softening curve data for various rolling rates, heat treatment temperatures, and heat treatment times. Based on the data, the above T _0.8 and A And control to appropriate heat treatment conditions. For example, a material having a hardness H ₀ is heat-treated at a holding time A (min) of 200 to 700 ° C. at intervals of 50 ° C. to create a softening curve, and the heating holding temperature at which the softening curve becomes 0.8H ₀ Expect. Next, the H ₀ material is subjected to a heat treatment at the expected temperature for a holding time A, and the hardness after the heat treatment is measured. Compare the measured value with the value of 0.8H ₀ , and if the difference is large, correct the expected value of the heated holding temperature, and again heat-treat the material with the hardness H _{0 under} the corrected condition to obtain the hardness Confirm. By repeating such as required operation, the heat treatment conditions for providing the hardness of 0.8H ₀ to the material hardness H ₀ can be set accurately. In actual operation, a sample is taken from the material after cold rolling before finishing in [1], the actual H ₀ is measured, and the above-mentioned heat treatment condition data obtained in advance is used to calculate T _0.8 +20 to T Heat treatment for holding time A may be performed within a range of _0.8 + 60 (° C.).
In general, the heating and holding time A of [2] can be set between 10 sec and 500 min, and the heating and holding temperature is about 300 to 600 ° C. in the case of a Cu-28% Zn-1Sn alloy, for example. Can be set within the range.

  In the finish cold rolling of [3], while adjusting to the target plate thickness, an appropriate working strain is introduced into the material, aiming to improve the 0.2% proof stress. Further, by increasing the processing rate, the material is rendered anisotropic, and a Y value of 10 or less is easily obtained by the heat treatment [4]. Therefore, it is desirable to secure a cold rolling rate of [3] of 50% or more. Usually, good results can be obtained with a rolling rate of about 50 to 95%.

In the finish heat treatment of [4], the anisotropic balance of Young's modulus and 0.2% proof stress is optimized. That is, the Y value defined by the equation (1) is 10 or less. The Y value has a complex influence on the chemical composition, the cold rolling rate of [3], and the heating and holding temperature / time of [4]. Therefore, even if the alloy has the same composition, the condition [4] cannot be set uniformly, and it is necessary to strictly control it according to the operating conditions. Actually, as in the case of the condition setting of [2], a simulation experiment using a copper alloy having a target composition is performed in advance to collect data applicable to various operating conditions, and based on the data, [4] The heating temperature and time may be set. For example, the finish cold-rolled material of [3] is subjected to a heat treatment with a holding time B (min) in the range of 50 to 500 ° C., Y after the heat treatment is obtained by the equation (1), and the relationship between Y and the heat treatment temperature. Create a curve that represents. From this curve, the heat treatment temperature range in which Y is 10 or less is predicted for the finished cold rolled material. Next, the finish cold-rolled material is heat-treated at time B in the expected temperature range, and the value of Y is confirmed. By repeating such operations as necessary, the accuracy of the data is improved. However, in the heat treatment of [4], the result varies depending on the history before [3] (that is, the state of the texture). Therefore, it is desirable to accumulate data in regular business production to improve data accuracy.
As a guideline, when the temperature at which the 0.2% proof stress is highest is T _M (° C.), the condition that the Y value is 10 or less in the range of −30 to + 60 ° C. with respect to T _M can be found. There are many cases where this is possible. Generally, the heating and holding time of [4] can be set between 5 sec and 500 min, and the heating and holding temperature is within a range of about 150 to 450 ° C. in the case of a Cu-28% Zn-1Sn alloy, for example. Can be set.

A copper alloy shown in Table 1 was melted in a high-frequency induction melting furnace and cast into a size of 300 × 200 × 40 (mm) and cut into a size of 40 × 200 × 40 (mm) to obtain a test material. The atmosphere during melting and casting was an Ar gas atmosphere, and water cooling was performed immediately after casting. Thereafter, each slab was hot-rolled, and cold rolling and heat treatment were repeated to obtain an intermediate product having a thickness of 5.0 mm. Using this intermediate product as a starting material, in steps A to C below, [1] pre-finish cold rolling, [2] pre-finish heat treatment, [3] finish cold rolling, or further [4] finish heat treatment, A specimen having a thickness of 0.5 mm was obtained. Of these, steps A 1 and D are examples of the present invention, and B, C 1 , E, and F are comparative examples.

[Process A]
[1] Cold rolling before finishing: It was performed at a rolling rate of 71%.
[2] Pre-finishing heat treatment: For each alloy, a softening curve by heat treatment for 60 minutes is obtained in advance for the cold-rolled material obtained under the cold rolling conditions of [1], and the Vickers hardness is 80% before the heat treatment. A temperature T _0.8 was determined. And it carried out on the conditions of heating temperature: _T0.8 + 30 degreeC and holding time: 60min. For example, in the example of No. 1, _T0.8 was 440 ° C.
[3] Finish cold rolling: Rolled to 0.5 mm at a rolling rate of 65%.
[4] Finish heat treatment: For each alloy, the cold-rolled material obtained in advance under the cold rolling conditions of [3] was subjected to heat treatment for 10 minutes and held at various temperatures, and then 0.2% proof stress and Young's modulus were obtained by the method described below. A Y value was obtained by measurement, and a temperature T _Y (° C.) at which the Y value was minimized was determined based on the data. And it carried out on the conditions of heating temperature: _TY (degreeC) and holding time: 10min. For example, in the example of No. 1, _TY was 280 ° C.

[Process B]
[1] to [3] were carried out under the same conditions as in step A, and [4] was not carried out to obtain a material as finished cold rolled.

[Process C]
[1] Cold rolling before finishing: Same as step A.
[2] Pre-finish heat treatment: T _0.8 (° C.) was determined in the same manner as in step A. And it carried out on the conditions of heating temperature: _T0.8 + 100 degreeC and holding time: 60min.
[3] Finish cold rolling: Same as step A.
[4] Finish heat treatment: Not implemented.

[Process D]
[1] Cold rolling before finishing: It was performed at a rolling rate of 73%.
[2] Pre-finishing heat treatment: For each alloy, a softening curve by heat treatment for 60 minutes is obtained in advance for the cold-rolled material obtained under the cold rolling conditions of [1], and the Vickers hardness is 80% before the heat treatment. A temperature T _0.8 was determined. And it carried out on the conditions of heating temperature: _T0.8 + 30 degreeC and holding time: 60min. For example, in the example of No. 6, _T0.8 was 500 ° C.
[3] Finish cold rolling: Rolled to 0.5 mm at a rolling rate of 80%.
[4] Finish heat treatment: For each alloy, the cold-rolled material obtained in advance under the cold rolling conditions of [3] was subjected to heat treatment for 10 minutes and held at various temperatures, and then 0.2% proof stress and Young's modulus were obtained by the method described below. A Y value was obtained by measurement, and a temperature T _Y (° C.) at which the Y value was minimized was determined based on the data. Then, heating temperature: T _Y (° C.), retention time: was performed in the conditions of 10min. For example, in the example No.6 T _Y was 300 ° C..

[Process E]
[1] to [3] were carried out under the same conditions as in Step D, and [4] was not carried out to obtain a material as finished cold rolled.

[Process F]
[1] Cold rolling before finishing: Same as step D.
[2] Pre-finish heat treatment: T _0.8 (° C.) was determined in the same manner as in Step D. And it carried out on the conditions of heating temperature: _T0.8 + 100 degreeC and holding time: 60min.
[3] Finish cold rolling: Same as step D.
[4] Finish heat treatment: Not implemented.

Each test material obtained in Steps A to F was examined for 0.2% proof stress, Young's modulus, Y value, average crystal grain size, roundness after punching, and height difference of shear plane.
The 0.2% proof stress and Young's modulus were obtained by conducting a tensile test according to JIS Z2241 using a JIS No. 5 tensile test piece in the L direction and T direction of the specimen.
The Y value was calculated by the above formula (1) based on the measured values of 0.2% proof stress and Young's modulus.
The average crystal grain size was determined by image processing using a crystal grain size measuring device by observing the structure with an optical microscope for a cross section (L cross section) parallel to the rolling direction and the plate thickness direction.

  The roundness after punching was determined as follows. Circular punching with a diameter of 5 mm was performed with a clearance of 3%, and the roundness was measured along the inner periphery of the circular hole of the punched sample. The roundness was measured by 12-point measurement using SMART SCOPE manufactured by OGP.

The height difference of the shear plane was determined as follows. A total of 8 positions (45 ° intervals) in the L direction position, T direction position and 45 ° direction position are determined along the inner periphery of the circular hole of the sample subjected to the circular punching. The maximum height difference at each position is obtained by measuring the height change of the cross-section (surface including the sag portion, shear deformation portion and fracture deformation portion) in the thickness direction, and the value obtained by averaging the maximum height difference values at eight locations. Was adopted as the height difference of the shear plane of the material.
The results are shown in Table 1.

As can be seen from Table 1, the copper alloy material of the example of the present invention produced by steps A and D has an average crystal grain size of 10 μm or less, a 0.2% proof stress in the L direction and the T direction of 650 N / mm ² or more, and a Y value. By satisfying the requirement of 10 or less, extremely good press punching dimensional accuracy of a roundness of 0.01 mm or less and a shear surface height difference of 9.3 μm or less was stably achieved.

  On the other hand, Comparative Examples Nos. 10 to 18 produced by the processes B and E do not undergo the finish heat treatment of [4], so the Y value increases, and as a result, the roundness and the difference in height of the shear surface Both were inferior to the inventive examples.

  In Comparative Examples Nos. 19 to 27 produced by Steps C and F, the temperature of the heat treatment before finishing in [2] was too high, so the average crystal grain size was increased and the 0.2% yield strength was reduced. Furthermore, since the finish heat treatment [4] was not performed, the Y value also increased. As a result, both the roundness and the difference in height of the shear surface were inferior to those of Steps B and E.

  Based on the example No. 10 shown in Table 1 of Example 1 (those not subjected to the finish heat treatment of [4]), the finish heat treatment corresponding to [4] is performed at various temperatures for a holding time of 10 minutes, In the same manner as in Example 1, 0.2% proof stress, Young's modulus, Y value, average crystal grain size, roundness after punching, and difference in height of the shear plane were examined. The results are shown in Table 2.

  As can be seen from Table 2, in the material obtained by subjecting the copper alloy having the above composition to the treatments [1] to [3] in step A, about -30 with respect to the heat treatment temperature at which the 0.2% proof stress becomes maximum. By performing a finish heat treatment at a temperature of ˜ + 60 ° C. and a holding time of 10 minutes, a characteristic having a Y value of 10 or less can be imparted, and a significant improvement in press punching dimensional accuracy can be achieved.

Claims (6)

Copper alloy having a composition of Sn: 0.01% to 10%, Zn: 8% to 30% and a total content of the above elements: 30% or less, the balance being Cu and inevitable impurities When finishing the plate by sequentially applying the processing and heat history of “[1] cold rolling before finishing, [2] heat treatment before finishing, [3] cold rolling after finishing, [4] finishing heat treatment” to the intermediate product of the plate, The manufacturing method of the copper alloy material which performs the process of said [2] and [4] on the following conditions, respectively.
[2] Pre-finish heat treatment: Vickers hardness after cold rolling before finish of [1] is set to H ₀ (HV), and the material having the hardness H ₀ is heated and held for holding time A (min). When the heating holding temperature at which _0.8 H ₀ (HV) is set to T _0.8 (° C.),
Holding temperature: T _0.8 +20 (° C.) or more, T _0.8 +60 (° C.) or less,
Holding time: A (min),
Perform under conditions that satisfy
[4] Finish heat treatment: Performed at a holding temperature and holding time at which the Y value defined by the following formula (1) is 10 or less.
Y = | Young modulus in the L direction / 0.2% yield strength in the L direction−Young's modulus in the T direction / 0.2% yield strength in the T direction |
However, the L direction means a direction parallel to the rolling direction, and the T direction means a direction perpendicular to the rolling direction. The unit of Young's modulus and 0.2% proof stress is N / mm ² . The copper alloy sheet material intermediate product contains Sn: 0.01 to 10%, Zn: 8 to 30%, P: 0.01 to 0.2% by mass%, and Ni, Fe, Mg, Co The total content of said each element: 30% or less is satisfied, and it has a composition which consists of remainder Cu and an unavoidable impurity. Manufacturing method of copper alloy material. The copper alloy sheet material intermediate product contains Sn: 0.01 to 10%, Zn: 8 to 30%, P: 0.01 to 0.2%, Ni: 0.01 to 3% by mass%, And the total content of said each element: The manufacturing method of the copper alloy material of Claim 1 which satisfy | fills 30% or less and has a composition which consists of remainder Cu and an unavoidable impurity. In mass%, Sn: 0.01 to 10%, P: 0.01 to 0.2%, further containing one or more of Ni, Fe, Mg, Co in a total of 0.01 to 3%, And the total content of each element: satisfying 30% or less , copper alloy sheet material intermediate composition having the balance Cu and unavoidable impurities , [[1] cold rolling before finishing, [2] heat treatment before finishing, [3 A process for producing a copper alloy material in which the steps [2] and [4] are each performed under the following conditions when finishing the plate by sequentially applying the processing and thermal history of “finish cold rolling and [4] finish heat treatment” .
[2] Pre-finish heat treatment: Vickers hardness after cold rolling before finish of [1] is set to H ₀ (HV), and the material having the hardness H ₀ is heated and held for holding time A (min). When the heating holding temperature at which _0.8 H ₀ (HV) is set to T _0.8 (° C.),
Holding temperature: T _0.8 +20 (° C.) or more, T _0.8 +60 (° C.) or less,
Holding time: A (min),
Perform under conditions that satisfy
[4] Finish heat treatment: Performed at a holding temperature and holding time at which the Y value defined by the following formula (1) is 10 or less.
Y = | Young modulus in the L direction / 0.2% yield strength in the L direction−Young's modulus in the T direction / 0.2% yield strength in the T direction |
However, the L direction means a direction parallel to the rolling direction, and the T direction means a direction perpendicular to the rolling direction. The unit of Young's modulus and 0.2% proof stress is N / mm ² . In mass%, Sn: 0.01 to 10%, P: 0.01 to 0.2%, Ni: 0.01 to 3%, and the total content of the above elements: 30% or less, Processing of “[1] cold rolling before finishing, [2] heat treatment before finishing, [3] cold rolling after finishing, [4] finishing heat treatment” on the intermediate product of the copper alloy sheet having the composition of the balance Cu and inevitable impurities A method for producing a copper alloy material, wherein the steps [2] and [4] are each performed under the following conditions when a thermal history is sequentially applied to finish a plate material.
[2] Pre-finish heat treatment: Vickers hardness after cold rolling before finish of [1] is set to H ₀ (HV), and the material having the hardness H ₀ is heated and held for holding time A (min). When the heating holding temperature at which _0.8 H ₀ (HV) is set to T _0.8 (° C.),
Holding temperature: T _0.8 +20 (° C.) or more, T _0.8 +60 (° C.) or less,
Holding time: A (min),
Perform under conditions that satisfy
[4] Finish heat treatment: Performed at a holding temperature and holding time at which the Y value defined by the following formula (1) is 10 or less.
Y = | Young modulus in the L direction / 0.2% yield strength in the L direction−Young's modulus in the T direction / 0.2% yield strength in the T direction |
However, the L direction means a direction parallel to the rolling direction, and the T direction means a direction perpendicular to the rolling direction. The unit of Young's modulus and 0.2% proof stress is N / mm ² . The method for producing a copper alloy material according to any one of claims 1 to 5, wherein the steps [1] and [3] are further performed under the following conditions.
[1] Cold rolling before finishing: Cold rolling is performed at a rolling rate of 60% or more.
[3] Finish cold rolling: Cold rolling is performed at a rolling rate of 50% or more.