JP2019178366A - Copper alloy sheet material and manufacturing method therefor - Google Patents

Abstract

To provide a copper alloy sheet material small in load of a manufacturing process and excellent in stress relaxation resistance, and to provide a manufacturing method therefor.SOLUTION: There is provided a copper alloy sheet material consisting of, by mass%, Cr:0.3 to 0.7%, Ti:0.03 to 0.15%, Si:0.03 to 0.15%, Fe:0.03 to 0.20%, total content of Mg, P, Mn, Co, Ag, Ni, Zn, Ca, B:0 to 0.50%, and the balance Cu with inevitable impurities, satisfying the following (Formula 1), and having a deposit containing Si in 400 μmwhen a rolling surface is observed of 50 or more and tensile strength of 500 MPa or more. (Formula 1) [Ti]<1.32[Cr]-6[Si], wherein [Ti] is content of Ti (mass%), [Cr] is content of Cr (mass%), and [Si] is content of Si (mass%).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a Cu-Cr-Ti-Si-based copper alloy sheet material having good press punching properties suitable as a material for a current-carrying member such as a high-voltage terminal and a bus bar, and a method for producing the same.

  Cu-Cr-Ti-Si-based copper alloy sheet has a high electrical conductivity of 75% IACS or higher, and is particularly useful as a current-carrying member around power supply circuits such as high-voltage terminals and bus bars. It can be used suitably. In order to use this type of current-carrying member, for example, cracks do not occur in a 90 ° W bending test in which the tensile strength in the rolling direction is 500 MPa or more and the bending axis is parallel to the rolling direction (BW). It is desirable to have a bending workability in which the value of the ratio MBR / t between the minimum bending radius MBR and the sheet thickness t is 0.5 or less. In addition, in order to maintain the reliability of the component in a high temperature environment, it is also desired to have a stress relaxation resistance characteristic such that the stress relaxation rate is 20% or less after 1000 hours at 200 ° C., for example. Conventionally, it has been possible to adjust the conductivity and strength of a copper alloy sheet to the desired levels by optimizing the aging conditions and the final workability. However, at present, it is not always easy to adjust the bending workability and the stress relaxation resistance to the desired ranges at the same time.

Here, Patent Document 1 includes mass%, Cr: 0.10 to 0.50%, Ti: 0.005 to 0.50, Si: 0.005 to 0.20% (Fe: 0.10%). And the balance is Cu, and the compound containing Cr and Si or other elements has a particle size of 5 μm or less and 30 or less in 500 μm ² , and is observed by cross-sectional SEM (scanning electron microscope) observation A copper alloy material having a metal structure with an average crystal grain size in the rolling direction of 15 μm or less and an average crystal grain size in the plate thickness direction of 10 μm or less is shown. It is disclosed that this copper alloy material has a conductivity of 70% IACS or more, a yield strength of 500 MPa or more, and excellent stress relaxation characteristics. Moreover, this copper alloy material is manufactured by cold-rolling a hot-rolled material that has been water-cooled after hot rolling, and further performing a heat treatment for precipitation aging.

  Patent Document 2 contains 0.005 to 0.5% by mass of Cr: 0.1 to 0.8%, one or more of Mg, Ti, Zr, Zn, Fe, Sn, Ag, and Si. The remainder is Cu, the average crystal grain size is 15 to 80 μm, the tensile strength is 400 MPa or more, the electrical conductivity is 75% IACS or more, the stress relaxation rate is 25% or less after 1000 ° C. and 1000 hours, the bending workability R / t A copper alloy material of 1 or less is shown. This copper alloy material is produced by subjecting a cold-rolled material obtained by hot rolling and cold rolling to recrystallization heat treatment and solution heat treatment at 850 to 1025 ° C.

  Furthermore, in Patent Document 3, Cr: 0.15-0.7%, Ag: 0.005-0.3%, Ti: 0.01-0.15%, Si: 0.01- Compared to 0.1%, Fe: 0.2% or less, Sn: 0.5% or less, the balance being Cu, yield strength of 75% IACS or more and 550MPa or more, and no silver A copper alloy material with improved stress relaxation resistance is shown. This copper alloy material is manufactured by solution annealing the cold-rolled material obtained by hot rolling and cold rolling.

Japanese Patent Laying-Open No. 2006-20543 JP2013-129889A JP 2008-57046 A

  The copper alloy material of Patent Document 1 has insufficient bending workability, and large wrinkles are generated at R / t = 0.5 (BW). Further, in order to obtain a high strength of 550 MPa or more, a large amount of Ti is required, and it is impossible to achieve both conductivity. Moreover, the copper alloy material of patent document 2 has high load of a manufacturing process, such as sandwiching recrystallization annealing in an intermediate process. Further, the copper alloy material of Patent Document 3 has insufficient stress relaxation resistance and a high manufacturing process load.

  On the other hand, when a copper alloy plate is processed into a current-carrying member, a press punching process is generally performed. FIG. 1 schematically shows the shape of the cut formed when a copper alloy sheet is punched out. A sag, a shear surface, a fracture surface and a flash are usually formed at the cut end. The shear surface has a linear shape substantially parallel to the punch axis direction. In this specification, the ratio of the fracture surface to the plate thickness in the cross section parallel to the punch axis direction and the shear plane normal direction is referred to as “ratio of fracture surface”. When the punch-to-die clearance is appropriate, if the fracture surface ratio is too small or too large, the amount of so-called “punching debris” generated during press punching increases, the die life and the dimensional accuracy of the product Adversely affect. In the conventional Cu-Cr-Ti-Si based copper alloy sheet material, the approach from the material side to make the ratio of the fractured surface to an appropriate range has not been made sufficiently, and there is still room for improvement in terms of press punchability. ing.

  In other words, the copper alloy containing Cr as in Patent Documents 1 to 3 has problems such as unstable shearing / breaking interface (powder is generated) and burr formation during press working, and from the problem of mold life and surface quality. Applications have been limited.

  The present invention has been made in view of the above circumstances, and is a copper alloy sheet material that has a small manufacturing process load, simultaneously improves conductivity, strength, bending workability, and stress relaxation resistance, and is excellent in press punchability. And it aims at providing the manufacturing method.

In the present invention, a copper alloy sheet material having a specific composition in which Fe is added to a Cu-Cr-Ti-Si-based copper alloy, the homogenization conditions after casting, the temperature between passes during hot rolling, etc. are controlled. It has been found that a copper alloy sheet material having high strength and excellent press workability can be provided by setting 50 or more precipitates containing Si, which is the starting point of fracture at the time of press work, within 400 μm ² in the observation of the rolled surface. The invention has been completed.

According to the invention of the copper alloy sheet of the present invention, in mass%, Cr: 0.3-0.7%, Ti: 0.03-0.15%, Si: 0.03-0.15%, Fe : 0.03 to 0.20%, Mg, P, Mn, Co, Ag, Ni, Zn, Ca, B total content: 0 to 0.50%, the balance consists of Cu and inevitable impurities, and There is provided a copper alloy sheet material satisfying (Formula 1) and having 50 or more precipitates containing Si in 400 μm ² and having a tensile strength of 500 MPa or more when the rolled surface is observed.
(Formula 1) [Ti] <1.32 [Cr] -6 [Si]
However, [Ti] is the Ti content (mass%)
[Cr] is the Cr content (% by mass)
[Si] is the Si content (% by mass)

The copper alloy sheet preferably has an electrical conductivity of 75% IACS or more, and preferably has a fracture surface ratio of 40% to 60% in the pressed surface when pressed. B. W. It is preferable that the ratio MBR / t ≦ 0.5 between the minimum bending radius MBR and the sheet thickness t in 90 ° W bending in the direction, and the stress relaxation rate after holding at 200 ° C. × 1000 h is preferably 20% or less. Furthermore, it is preferable that the following (Formula 2) is satisfied.
(Formula 2) [Fe]> 2.6 [Ti] -0.143-0.5 [Si]
However, [Fe] is the Fe content (mass%)
[Ti] is the Ti content (mass%)
[Si] is the Si content (% by mass)

Moreover, according to the invention of the method for producing a copper alloy sheet material of the present invention, Cr: 0.3-0.7%, Ti: 0.03-0.15%, Si: 0.03-0. 15%, Fe: 0.03 to 0.20%, Mg, P, Mn, Co, Ag, Ni, Zn, Ca, B total content: 0 to 0.50%, the remainder from Cu and inevitable impurities And a slab of copper alloy satisfying the following (formula 1) is heated to 850 to 950 ° C., held for 0.5 h or more, hot rolling is started, and the final rolling pass temperature is set to 750 ° C. or more, A hot rolling step of obtaining a hot rolled material under a condition that the rolling ratio in a temperature range of less than 800 ° C. is 50% or less with respect to the total rolling rate of the hot rolling; A cold rolling step of performing cold rolling to obtain a cold rolled material, and subjecting the cold rolled material to an aging treatment at 350 ° C. or higher for 2 hours or longer Having aging treatment step, the manufacturing method of the copper alloy sheet is provided.
(Formula 1) [Ti] <1.32 [Cr] -6 [Si]
However, [Ti] is the Ti content (mass%)
[Cr] is the Cr content (% by mass)
[Si] is the Si content (% by mass)

This manufacturing method may have intermediate annealing at a temperature and time at which intermediate rolling and recrystallization do not occur between the hot rolling process and the cold rolling process. Moreover, it is preferable to satisfy the following (Formula 2).
(Formula 2) [Fe]> 2.6 [Ti] -0.143-0.5 [Si]
However, [Fe] is the Fe content (mass%)
[Ti] is the Ti content (mass%)
[Si] is the Si content (% by mass)

  ADVANTAGE OF THE INVENTION According to this invention, the copper alloy board | plate material with the small load of a manufacturing process and excellent in intensity | strength and press punching property, and its manufacturing method can be provided.

It is explanatory drawing which shows typically the shape of the cut formed when a copper alloy board | plate material is pierce | punched.

(Component composition)
First, the component composition of the copper alloy sheet material of the present invention will be described. In addition,% about a component composition is the mass%.

Cr: 0.3-0.7%
Cr contributes to stress relaxation resistance and strength improvement by solid solution and precipitation in a Cu matrix that is a matrix (metal substrate). Cr is an effective element for forming a Cr—Si based precipitate together with Si, improving the strength by precipitation hardening, and reducing the solid solution amount of Si in the Cu matrix to increase the conductivity. Cr also has the effect of forming Cr—Ti-based precipitates together with Ti, improving the strength by precipitation hardening, and reducing the solid solution amount of Ti in the Cu matrix to increase the conductivity. If the Cr content is less than 0.3%, sufficient strength cannot be improved by precipitation hardening. On the other hand, if the Cr content exceeds 0.7%, the electrical conductivity is lowered, the precipitates are coarsened, the stress relaxation resistance of the copper alloy material is lowered, and coarse inclusions are formed. By being formed, bending workability is lowered. Therefore, the Cr content is set to 0.3 to 0.7%.

Ti: 0.03-0.15%
Ti is an effective element for improving the stress relaxation resistance by solid solution in the Cu matrix. Ti is an effective element for forming a precipitate with Cr and Si and improving the strength by precipitation hardening, and reducing the solid solution amount of Cr and Si in the Cu matrix to increase the conductivity. It is. Moreover, bending workability can be improved by reducing the amount of Ti solid solution. When the Ti content is less than 0.03%, the stress relaxation resistance cannot be sufficiently improved. On the other hand, if it exceeds 0.15%, the solid solution amount of Ti in the Cu matrix increases, leading to a decrease in conductivity and bending workability. In addition, when the Ti content is high, a large amount of Ti oxide sticks to the furnace wall of the melting furnace, and there is a risk of ingot quality deterioration in the next casting process. There is also the problem of reduced efficiency. Therefore, the Ti content is 0.03 to 0.15%.

Si: 0.03-0.15%
Si forms Cr—Si based precipitates together with Cr, and Ti—Si based precipitates together with Ti, increasing the strength by precipitation hardening, and decreasing the solid solution amount of Cr and Ti in the Cu matrix. It is an effective element for increasing conductivity. Si also forms Cr—Si—Ti precipitates together with Cr and Ti, but according to the study by the inventors, the effect of improving the strength by precipitation hardening could not be confirmed. If the Si content is less than 0.03%, sufficient improvement in strength due to Cr—Si based precipitates and Ti—Si based precipitates cannot be obtained. On the other hand, when the Si content exceeds 0.15%, the solid solution amount of Si in the Cu matrix increases and the electrical conductivity decreases. In addition, Cr—Si based precipitates, Ti—Si based precipitates, and Cr—Ti—Si based precipitates are coarsened, and the stress relaxation resistance of the copper alloy material is reduced. Accordingly, the Si content is set to 0.03 to 0.15%.

Fe: 0.03 to 0.20%
In the present invention, Fe is added to a Cu-Cr-Ti-Si alloy, and Ti is excessive (even within the Ti composition range of the present invention, Ti does not become Cr and Si and precipitates, that is, in the Cu matrix). In a relatively large amount of Ti that dissolves in the solution). Fe is an effective element for forming Ti—Fe-based precipitates together with Ti, increasing the strength by precipitation hardening, and decreasing the amount of Ti solid solution in the Cu matrix to increase the conductivity. When the Fe content is less than 0.03%, it is not possible to sufficiently obtain the effect of suppressing the decrease in conductivity and improving the strength by precipitation. On the other hand, if the Fe content exceeds 0.20%, the amount of solid solution in the Cu matrix increases, causing a decrease in conductivity and coarsening the precipitates, thereby preventing an increase in strength due to precipitation hardening. . Therefore, the Fe content is 0.03 to 0.20%.

Total content of Mg, P, Mn, Co, Ag, Ni, Zn, Ca, B: 0 to 0.50%
Mg, Mn, Ag, and Zn have the effect of improving the strength and stress relaxation resistance by solid solution in the Cu matrix, and can be contained as necessary. In that case, it is more effective to set the Mg, Mn, and Ag contents in the range of 0.01 to 0.50%. Moreover, it is effective that Zn content shall be 0.01 to 0.30% of range.
Ni, P and Co form precipitates with Si and Ti and contribute to strength improvement, and can be contained as necessary. In that case, the Ni content is preferably in the range of 0.03 to 0.20%. The P content is preferably in the range of 0.01 to 0.10%. The Co content is preferably in the range of 0.01 to 0.50%.
Ca and B precipitate with a simple substance or a Cu parent phase and contribute to improvement of bending workability and strength, and can be contained as necessary. It is more effective to set the Ca and B contents in the range of 0.01 to 0.20%.
The total content of these elements is preferably 0 to 0.50%. If it exceeds 0.50%, the conductivity is lowered.

(Formula 1) [Ti] <1.32 [Cr] -6 [Si]
However, [Ti] is the Ti content (mass%)
[Cr] is the Cr content (% by mass)
[Si] is the Si content (% by mass)
(Formula 2) [Fe]> 2.6 [Ti] -0.143-0.5 [Si]
However, [Fe] is the Fe content (mass%)
[Ti] is the Ti content (mass%)
[Si] is the Si content (% by mass)
When the content (mass%) of each element of Cr, Ti, Si, and Fe satisfies (Formula 1) and (Formula 2), the strength, conductivity, and stress relaxation resistance of the copper alloy sheet of the present invention The balance is determined.

  When the content (mass%) of each element of Cr, Ti, and Si satisfies (Formula 1), the balance of strength, electrical conductivity, and stress relaxation resistance is suitable, and the present invention is excellent in press punchability. The copper alloy sheet can be obtained. Even if the content (mass%) of each element of Cr, Ti, Si, and Fe is within the scope of the present invention, if this (Equation 1) is not satisfied, for example, conductivity, stress relaxation characteristics, bending work, etc. At least one characteristic of the sex is inferior. Moreover, it is more preferable that the content (mass%) of each element of Fe, Ti, and Si satisfies (Formula 2). (Equation 1) and (Equation 2) are equations that were experimentally derived when the inventors studied diligently and investigated the composition ratio.

  Cr-Si-based precipitates and Ti-Si-based precipitates are effective for exhibiting the characteristics of this alloy, but when Ti content exceeds (Equation 1), Cr-Ti- is hardly contributed to the expression of characteristics. Si-based precipitates are generated. If the amount of this precipitate is too large, Cr—Si-based precipitates and Ti—Si-based precipitates that are effective in developing the characteristics will decrease, leading to characteristic deterioration (particularly stress relaxation resistance). It is necessary to satisfy.

  Fe has the function of stabilizing the conductivity by forming precipitates with Ti, that is, the function of lowering the manufacturing difficulty of the copper alloy of the present invention. However, if added excessively, the conductivity decreases due to the solid solution of Fe. The effect (action) becomes larger and no merit can be obtained. Since Ti difference lost due to precipitation of Ti-Si-based precipitates having an effect of improving the characteristics of Ti content decreases as residual Ti, (Equation 2) defines the amount of Fe that can be precipitated with the remaining Ti. It is a thing.

Balance: Cu and inevitable impurities In addition to the above essential elements and optional additional elements, the balance consists of Cu and inevitable impurities. Inevitable impurities include, for example, C, S, O, N, H, and other furnace bodies and those mixed from the atmosphere.

(Metal structure)
Next, the metal structure of the copper alloy sheet material of the present invention will be described.

When the rolled surface of the copper alloy sheet of the present invention is observed with EPMA (electron beam microanalyzer), 50 or more precipitates containing Si are present in 400 μm ² . The copper alloy material of the present invention can stabilize the shear / rupture interface due to the presence of a large amount of Si-containing precipitates such as Cr—Si-based precipitates that are the starting points of fracture during pressing. That is, it is considered that the presence of 50 or more precipitates containing Si in 400 μm ² creates a state in which precipitates containing Si are highly dispersed in the Cu matrix and improves the press working characteristics. . If the number of precipitates containing Si within 400 μm ² is less than 50, such an effect cannot be obtained. The calculation of the precipitate containing Si can be performed by observing 1000 times with EPMA (or SEM).

  Specifically, when the rolling surface of the copper alloy sheet is observed with EPMA, the area where Si of 10% or more of the maximum detected intensity of Si in the observation area is detected is white, and the other areas are black and image processing. Binarization was performed, and a white area of 1 pixel or more was determined as one precipitate containing Si, and the number was counted. Note that the Ti—Si-based precipitates are very fine and are usually not detected at about 1000 times.

(Characteristic)
Next, the characteristics of the copper alloy sheet of the present invention will be described.

Tensile strength: 500 MPa or more and 0.2% proof stress: 450 MPa or more The copper alloy sheet material of the present invention has a tensile strength in the rolling parallel direction (LD) of 500 MPa or more and a 0.2% proof stress of 450 MPa or more. Any material having this strength level can be widely applied to various current-carrying members such as high-voltage terminals and bus bars. Those having a tensile strength of 510 MPa or more and a 0.2% proof stress of 480 MPa or more are more suitable targets. Tensile strength and 0.2% proof stress are measured and calculated according to JIS Z 2241.

Ratio of fracture interface of press punched surface (cut): 40% to 60%
As described above, in this specification, regarding the cut surface (shown in FIG. 1) that appears when a copper alloy sheet material is punched with a press die, the fracture surface relative to the sheet thickness in the section parallel to the punch axis direction and the shear plane normal direction. The ratio occupied by is defined as “ratio of fractured surface” and is obtained by the following formula.
Fracture surface ratio (%) = fracture surface thickness (mm) / plate thickness (mm) × 100
When the punch-to-die clearance is appropriate (for example, the clearance / plate thickness ratio is about 3 to 10%), if the fracture surface ratio is too small or too large, so-called “punching” will occur during press punching. In order to increase the amount of production and to adversely affect the mold life and dimensional accuracy of the product, the fracture surface ratio is preferably 40 to 60%.

Conductivity: 75% IACS or more In consideration of securing practical conductivity as a current-carrying member around a power circuit such as a high-voltage terminal or bus bar, the conductivity is preferably 75% IACS or more, and 80% IACS or more. More preferably. The conductivity can be measured according to JIS H 0505.

Bending workability: MBR / t ≦ 0.5
The copper alloy material of the present invention has a minimum bending radius MBR and a sheet thickness t that do not generate cracks when the bending axis is the rolling parallel direction (BW) in the 90 ° W bending test described in JIS H3130. The value of the ratio MBR / t is preferably 0.5 or less. If MBR / t is 0.5 or less in this bending test, it is evaluated that it has excellent bending workability in processing of current-carrying members such as high-voltage terminals and bus bars. It is more preferable that MBR / t is 0.3 or less.

Stress relaxation rate characteristic: 25% or less The copper alloy material of the present invention preferably has a stress relaxation rate of 25% or less, more preferably 20% or less after being held at 200 ° C. for 1000 hours by LD. As for the stress relaxation resistance (stress relaxation rate), a test piece having an LD length of 60 mm and a TD width of 10 mm was cut out from the test material, and this was cantilevered as shown in the Japan Electronic Materials Manufacturers Association Standard EMAS-1011. It calculated | required by performing the test based on the stress relaxation test of a beam block type. The test piece was set in a state where a load stress corresponding to 80% of 0.2% proof stress was applied so that the deflection displacement was in the plate thickness direction, and the deflection displacement after being held at 200 ° C. for 1000 hours was measured. The stress relaxation rate (%) was calculated from the change rate of the displacement.

(Production method)
Next, the manufacturing method of the copper alloy sheet | seat material of this invention is demonstrated.

(Melting / Casting)
What is necessary is just to manufacture the slab of the copper alloy which satisfies the said component composition by continuous casting, semi-continuous casting, etc. In order to prevent oxidation of Ti or the like, it is preferably performed in an inert gas atmosphere or a vacuum melting furnace.

(Hot rolling process)
A slab of copper alloy satisfying the above component composition was charged into a heating furnace and heated to 850 to 950 ° C., and the holding time (time during which the material temperature was in the above temperature range) was 0.5 h or more, The slab is taken out from the heating furnace and hot rolling is started. The rolling start temperature of hot rolling is 950 to 850 ° C., the final rolling pass temperature is 750 ° C. or higher, and the total rolling rate of hot rolling is preferably 20 to 95%, preferably 30 to 90%. Is more preferable. Moreover, the rolling ratio in the temperature range below 800 ° C. with respect to the total rolling rate of hot rolling is set to 50% or less, and more preferably 45% or less. In addition, the said rolling ratio may be called the rolling ratio below 800 degreeC, or the rolling ratio in the temperature range below 800 degreeC.
For example, when the thickness of the copper alloy sheet before the start of hot rolling is 20 mm, the total rolling rate of hot rolling is 70%, and the rolling ratio in the temperature range below 800 ° C. is 25%, The plate thickness after the end of rolling (after the final rolling pass) is 6 mm, and the thickness rolled in the temperature range below 800 ° C. is (20 mm−6 mm) × 25/100 = 3.5 mm.
The rolling start temperature and the final rolling pass temperature of the hot rolling can be measured for each pass using a radiation thermometer or a contact thermometer before the hot rolling pass.

(Cold rolling process)
The hot rolled material obtained under the conditions of the hot rolling step is not subjected to intermediate annealing or is subjected to one or more intermediate annealings at a temperature at which recrystallization does not occur, and a total (total) rolling ratio of 88% As described above, preferably, cold rolling of 90% or more is performed to obtain a cold rolled material. The heating temperature of the intermediate annealing is preferably 200 to 500 ° C, for example, and more preferably 200 to 350 ° C.

Also in the case where the intermediate annealing is performed, the total rolling ratio in the cold rolling process is set to 88% or more. For example the intermediate annealing was carried out once, cold rolled at a reduction rate of 75% (intermediate) cold rolling → annealing → reduction ratio of 80% (final) cold rolling step the thickness h ₀ to h1 In this case, since h ₁ = h ₀ × 0.25 × 0.2 = 0.05h ₀ , the total rolling ratio is (h ₀ −0.05h ₀ ) / h ₀ × 100 = 95%. From the viewpoint of manufacturing cost, it is preferable to apply a cold rolling process in which intermediate annealing is not performed.

(Aging process)
The cold rolled material obtained under the conditions of the cold rolling step is subjected to an aging treatment at 350 ° C. or higher for 2 hours or longer. Thereby, the copper alloy plate material of the present invention, which is an aging material having an electrical conductivity of 70% IACS or more and a tensile strength of 500 MPa or more, can be produced. From the above, copper alloy with high conductivity, high heat resistance, high strength, bending workability and press punchability improved at the same time, with a small number of processes with only component, component ratio definition, homogenization, and adjustment of hot rolling conditions A plate material can be obtained.

A copper alloy having the chemical composition shown in Table 1 was melted and cast in a high-frequency vacuum melting furnace. The obtained slab was cut out to a thickness of 20 mm, charged into a heating furnace, and heated and held at the heating temperature and holding time shown in Table 2. Table 1 shows the values calculated for the right side of the following (formula 1) and (formula 2).
(Formula 1) [Ti] <1.32 [Cr] -6 [Si]
However, [Ti] is the Ti content (mass%)
[Cr] is the Cr content (% by mass)
[Si] is the Si content (% by mass)
(Formula 2) [Fe]> 2.6 [Ti] -0.143-0.5 [Si]
However, [Fe] is the Fe content (mass%)
[Ti] is the Ti content (mass%)
[Si] is the Si content (% by mass)

  The heated slab was taken out of the furnace, and hot rolling was started at the heating temperature shown in Table 2 and finished at the final rolling pass temperature shown in Table 2. Table 2 shows the total rolling rate of hot rolling, the final rolling pass temperature, the rolling ratio of less than 800 ° C., and the thickness of the copper alloy sheet after hot rolling. The rolling temperature in each pass was monitored by measuring the material surface temperature on the work roll entering side of the hot rolling mill with a contact thermometer (thermocouple). After hot rolling, chamfering was performed to remove the oxide scale, and a hot rolled material for use in the next step was obtained.

  Each of the hot rolled materials was cold rolled at a rolling rate shown in Table 2. In some examples (Invention Example No. 4, Comparative Example No. 15), an intermediate annealing was performed once during the cold rolling process. Otherwise, the cold rolling process was completed without performing the intermediate annealing. About the example which implemented intermediate annealing, the metal structure after intermediate annealing was observed with the optical microscope, and the presence or absence of the recrystallized grain was confirmed.

  Subsequently, each cold-rolled material was subjected to an aging treatment under the conditions shown in Table 2. Here, a heat pattern was adopted in which the temperature was raised to the temperature shown in Table 2 and then the temperature was kept at that temperature for the time shown in Table 2 and then cooled. Some examples (Invention Nos. 2, 4 to 6, 8 and Comparative Examples No. 11, 13, 15, and 21) were subjected to twice aging treatment (two-stage aging). No. 15 was cold-rolled between two aging treatments. The atmosphere during heating was a hydrogen + nitrogen mixed gas atmosphere or an inert gas atmosphere. After the aging treatment, pickling was performed, and the obtained aging material was used as a test material. Table 2 shows the thickness of the test material.

The following investigation was conducted for each specimen.
〔conductivity〕
The electrical conductivity of each test material was measured according to JIS H0505.
[Tensile strength, 0.2% yield strength]
LD tensile specimens (JIS No. 5) were collected from each test material, JIS Z2241 tensile test was performed with the number of tests n = 3, and the tensile strength and 0.2% proof stress were determined by the average value of n = 3. . Moreover, the value of 0.2% proof stress was used for the stress relaxation rate evaluation test described later.
[Bending workability]
A 90 ° W bending test was performed when the bending axis was in the rolling parallel direction (BW) by the method described in JIS H3130. The ratio MBR / t between the minimum bending radius MBR and the thickness t where no cracks occurred was determined.
[Stress relaxation rate]
As for the stress relaxation rate, a test piece having a length of LD (parallel to the rolling direction) of 60 mm and a width of TD (direction perpendicular to the rolling parallel direction and the plate thickness direction) of 10 mm was cut out from the specimen. It calculated | required by performing the test based on the stress relaxation test of the cantilever block type | formula shown by the electronic material industry association standard EMAS-1011. Equivalent to 80% of 0.2% proof stress when the test piece is fixed at one end in the longitudinal direction and the deflection at the other end in the longitudinal direction is 5 mm so that the deflection is in the thickness direction. The span length was changed (by the deflection displacement adjustment block) so as to obtain a load stress to be set (fixed) with the stress applied. With respect to this test piece, the deflection displacement after holding at 200 ° C. for 1000 hours was measured, and the stress relaxation rate (%) was calculated from the change rate of the displacement.
[Rate of fracture surface]
Fracture surface ratio: 40-60%
As described above, in this specification, regarding the cut surface (shown in FIG. 1) that appears when a copper alloy sheet material is punched with a press die, the fracture surface relative to the sheet thickness in the section parallel to the punch axis direction and the shear plane normal direction. The ratio occupied by is defined as “ratio of fractured surface” and is obtained by the following formula.
Fracture surface ratio (%) = fracture surface thickness (mm) / plate thickness (mm) × 100
In the press punching test for determining the ratio of the fracture surface, the material is a use classification V20 (material type G3), and a substantially square shape in which R are rounded at four corners of a square of 15 mm length and 15 mm width. A die composed of a die having a perforated hole and a substantially square punch designed to have a clearance / thickness ratio of 4% and 9% with respect to the die was used.
Copper alloy sheet material so that the vertical side of the opening of this die is the LD (parallel direction of rolling) of the copper alloy sheet, and the horizontal side is TD (direction perpendicular to the parallel direction of rolling and the thickness direction) of the copper alloy sheet The copper alloy sheet was punched using a 35 t press at a press speed of 50 spm (shots per minute).
Observe the cross section of the central part of the four sides of the substantially square opening (cut) of the punched copper alloy sheet, measure the thickness of the four fracture surfaces, and determine the ratio of the fracture surface as described above. Calculated. Moreover, the average value of the ratio of the fracture surface was calculated by averaging the ratios of the four fracture surfaces obtained.
It is preferable that the ratio of the fracture surface is 40% to 60%.
[Number density of precipitates containing Si]
The rolling surface of the copper alloy sheet is identified as an element by mapping the element with a magnification of 1000 times using EPMA (JXA-8100 manufactured by JEOL Ltd.) with an acceleration voltage of 15 kV and a current of 5 × 10 ⁻⁸ A (50 nA). went. Si mapping is measured using spectral crystal PETJ, and the area where Si is detected at 10% or more of the maximum detection intensity of Si in the observation area (field of view) is binarized by white and the other areas are binarized by black. A white area of 1 pixel or more was determined as one precipitate containing Si, and the number was counted. Note that the total number of pixels in the observation area is 1280 × 1024 pixels. The number of precipitates containing Si within 400 μm ² was counted to obtain the number density of precipitates containing Si.
These results are shown in Table 3.

  In the example of the present invention, the electrical conductivity is 75% IACS or more, the tensile strength in the rolling parallel direction is 500 MPa or more, the 0.2% proof stress is 450 MPa or more, the stress relaxation rate of 200 ° C. × 1000 hours is 20% or less, and the 90 ° W bending test. A copper alloy sheet having an MBR / t of BW of 0.5 or less and good press properties with a fracture surface ratio of 40 to 60% can be obtained. It was. No recrystallization occurred after the intermediate annealing in the No. 4 cold rolling process.

Is a comparative example No.11 heating temperature of the slab as high as 1000 ° C., No.12 short heating time of the slab, the number density of the precipitates containing Si is located less than 50/400 [mu] m ² Doo small It was. For this reason, press punchability was inferior and bending workability was also poor.
In No. 13, the temperature of the final rolling pass of hot rolling is too low. No. 14 had a rolling ratio of less than 800 ° C. in hot rolling exceeding 50%. Therefore, the tensile strength was small and the stress relaxation resistance was poor.
No. 15 was recrystallized because it was subjected to intermediate annealing at a high temperature during cold rolling. Further, cold rolling was performed between the primary aging treatment and the secondary aging treatment. Therefore, the number density of precipitates containing Si was less than 50/400 μm ² and was small. For this reason, the stress relaxation resistance and press punchability were inferior.
In No. 17, since the Cr content was too small, the number density of precipitates containing Si was less than 50 pieces / 400 μm ² and was small. Therefore, the tensile strength was small, and the stress relaxation resistance and press punchability were poor.
No. No. 18 had a poor conductivity because it contained too much Cr.
No. 19 had too little Ti content, so the tensile strength was small and the stress relaxation resistance was poor.
In No. 20, since the content of Si was too small, the number density of precipitates containing Si was less than 50/400 μm ² and was small. Therefore, the electrical conductivity was small, and the press punchability and bending workability were poor.
Since No. 21 had too little Fe content, the electrical conductivity was small and the bending workability was poor.
Since No. 22 had too much Fe content, the stress relaxation resistance was poor.
No. 23 did not satisfy the relationship of (Equation 1), so its conductivity was low and its stress relaxation resistance was poor.
In No. 24, since the Fe content was too small and the heating temperature of the slab was high, the number density of precipitates containing Si was less than 50 pieces / 400 μm ² and was small. For this reason, the electrical conductivity was low, the tensile strength was small, the stress relaxation resistance and the press punchability were poor.
In No. 25, the Ti content was too high and the composition did not satisfy the relationship of (Formula 1) and (Formula 2), so the electrical conductivity was low and the bending workability was poor.
No. 26 had too much Si content and the composition did not satisfy the relationship of (Equation 1), so the conductivity was small and the tensile strength was also small.

Claims (9)

% By mass
Cr: 0.3 to 0.7%,
Ti: 0.03-0.15%,
Si: 0.03 to 0.15%,
Fe: 0.03 to 0.20%,
Total content of Mg, P, Mn, Co, Ag, Ni, Zn, Ca, B: 0 to 0.50%,
The balance consists of Cu and inevitable impurities,
And the following (Formula 1) is satisfied,
When observing the rolled surface, there are 50 or more precipitates containing Si in 400 μm ² ,
A copper alloy sheet having a tensile strength of 500 MPa or more.
(Formula 1) [Ti] <1.32 [Cr] -6 [Si]
However, [Ti] is the Ti content (mass%)
[Cr] is the Cr content (% by mass)
[Si] is the Si content (% by mass)   The copper alloy sheet according to claim 1, wherein the conductivity is 75% IACS or more.   The copper alloy sheet material according to any one of claims 1 and 2, wherein a ratio of a fracture surface to a press surface when pressed is 40% to 60%.   B. W. The copper alloy sheet according to any one of claims 1 to 3, wherein a ratio MBR / t ≦ 0.5 of a minimum bending radius MBR and a sheet thickness t is obtained by 90 ° W bending in a direction.   The copper alloy sheet material according to any one of claims 1 to 4, wherein a stress relaxation rate after being held at 200 ° C for 1000 hours is 20% or less. The copper alloy sheet material according to any one of claims 1 to 5, which satisfies the following (Formula 2).
(Formula 2) [Fe]> 2.6 [Ti] -0.143-0.5 [Si]
However, [Fe] is the Fe content (mass%)
[Ti] is the Ti content (mass%)
[Si] is the Si content (% by mass) % By mass
Cr: 0.3 to 0.7%,
Ti: 0.03-0.15%,
Si: 0.03 to 0.15%,
Fe: 0.03 to 0.20%,
Total content of Mg, P, Mn, Co, Ag, Ni, Zn, Ca, B: 0 to 0.50%,
The balance consists of Cu and inevitable impurities,
And a slab of copper alloy satisfying the following (formula 1),
Heating to 850 to 950 ° C., holding hot for 0.5 h or more, then starting hot rolling, setting the final rolling pass temperature to 750 ° C. or more, and rolling ratio in a temperature range of less than 800 ° C. with respect to the total rolling rate of hot rolling A hot rolling step of obtaining a hot-rolled material under the condition of 50% or less,
A cold rolling step of obtaining a cold rolled material by subjecting the hot rolled material to a cold rolling with a total rolling rate of 88% or more;
The manufacturing method of a copper alloy board | plate material which has an aging treatment process which performs the aging treatment for 2 hours or more at 350 degreeC or more to the said cold-rolled material.
(Formula 1) [Ti] <1.32 [Cr] -6 [Si]
However, [Ti] is the Ti content (mass%)
[Cr] is the Cr content (% by mass)
[Si] is the Si content (% by mass)   The method for producing a copper alloy material according to claim 7, wherein intermediate annealing is performed between the hot rolling process and the cold rolling process at a temperature and time at which intermediate rolling and recrystallization do not occur. The manufacturing method of the copper alloy sheet | seat material as described in any one of Claim 7 or 8 which satisfies the following (Formula 2).
(Formula 2) [Fe]> 2.6 [Ti] -0.143-0.5 [Si]
However, [Fe] is the Fe content (mass%)
[Ti] is the Ti content (mass%)
[Si] is the Si content (% by mass)

Images