JP6034765B2 - Aluminum alloy plate for electrical connection parts and method for producing the same - Google Patents

Description

  The present invention electrically connects between electric devices (batteries, inverters, motors, etc.) mounted on various electric transportation devices using electricity as a power source such as an electric vehicle or between components inside the electric device. The present invention relates to an aluminum alloy plate used for electrical connection parts such as a bus bar to be connected and a manufacturing method thereof.

  Various electric devices such as a battery group, an inverter, and a motor are mounted on various electric transport devices (such as hybrid vehicles, fuel cell vehicles, and electric locomotives) that use electricity as a power source, including electric vehicles. An electrical connection component called a bus-bar is used to electrically connect between these electrical devices or between components inside the electrical device.

When this bus bar is connected by a connecting tool such as a bolt, deformation (creep deformation) of the connecting part 1a (see FIG. 1) of the bus bar 1 due to heat generation during energization causes a reduction in tightening torque of the connecting tool, A situation occurs in which the coupler is loosened or disconnected. Therefore, the bus bar 1 needs to have high creep resistance.
Further, in order to satisfy the demand for space saving (miniaturization) of electrical equipment, the bus bar 1 is often designed in a shape having a curved portion with a small bending radius (R). Therefore, the bus bar 1 needs to be excellent in bending workability.

Further, the bus bar 1 may need to be bonded to a member such as a bonding wire. In this case, a method such as ultrasonic welding in which ultrasonic waves are applied while pressing the bus bar 1 and the end of the bonding wire is used. It has been adopted. Here, in order to firmly weld the bus bar 1 and the bonding wire, it is only necessary to increase the pressure to be applied and the power of the applied ultrasonic wave. However, if these are increased, there is a problem that the bus bar 1 and the bonding wire are deformed. It will occur. That is, there is a limit to improving the weldability only by controlling the welding conditions of ultrasonic welding. Therefore, the bus bar 1 itself needs to have excellent weldability.
In addition, since the bus bar 1 must conduct electricity, it is naturally necessary to have excellent conductivity.

Up to now, copper-based materials have been studied for electrical connection parts such as bus bars that satisfy the above conditions.
However, in recent years, in order to reduce the fuel consumption of automobiles, it is required to reduce the weight of automobiles and to reduce the weight of electrical devices mounted on automobiles.
In view of the above circumstances, an electrical connection component made of an aluminum alloy that is lighter than copper has been proposed.

  For example, Patent Document 1 discloses an aluminum alloy for an electrical connection component in which a component composition is specified and conductivity and tempering conditions are specified. Patent Document 1 describes that the aluminum alloy has excellent conductivity and excellent creep resistance.

  Patent Document 2 discloses a technique related to an aluminum alloy plate for a heat radiating component, not for an electrical connection component. However, a homogenized heat treatment, hot rolling, A method for producing an aluminum alloy sheet that is subjected to rolling and final annealing is disclosed. And in patent document 2, it describes that the aluminum alloy plate manufactured with the said manufacturing method has the bending workability requested | required of a printed circuit board.

  Further, in Patent Documents 3 and 4, although it is a technique related to an aluminum alloy plate for an automobile panel, not for an electrical connection component, the bending workability of an Al—Mg—Si based alloy (JIS6000 based Al alloy) is improved. Therefore, a technique (Patent Document 3) in which the texture is controlled and the Cube orientation distribution density is set to a predetermined value, or a crystal whose orientation difference is 20 ° or less with respect to the total grain boundary length between all crystal grains. A technique for specifying the grain boundary length between grains (Patent Document 4) is disclosed.

Japanese Patent No. 3557116 JP 2009-242813 A JP 2005-298922 A Japanese Patent No. 3749687

  However, although the technique disclosed in Patent Document 1 is a technique that focuses on the improvement of creep resistance, it is a technique that does not consider bending workability at all (see paragraph 0010 of Patent Document 1). Naturally, the bending workability required for electrical connection parts could not be satisfied. Therefore, when the technique disclosed in Patent Document 1 is applied to an electrical connection component, a bending crack may occur on the surface during molding.

  Further, although the technique disclosed in Patent Document 2 is a technique that focuses on the improvement of bending workability, it is a technique that does not consider creep resistance at all (see paragraph 0001 and the like in Patent Document 2). Naturally, the creep resistance required for electrical connection parts could not be satisfied. Therefore, when the technique disclosed in Patent Document 2 is applied to an electrical connection component, the coupling portion 1a (see FIG. 1) of the bus bar 1 (electrical connection component 1) is deformed due to heat generation during energization, so that the coupling portion 1a. May come off the part.

  The techniques disclosed in Patent Documents 3 and 4 are similar to Patent Document 2 in that bending workability is considered, but creep resistance is not considered at all, and for electrical connection parts. It is a technology for automobile panels. Therefore, the techniques disclosed in Patent Documents 3 and 4 do not satisfy the creep resistance required for electrical connection parts.

As can be seen from the descriptions in Patent Documents 1 to 4, there is no technology that achieves both the creep resistance and the bending workability required for the electrical connection parts for the aluminum alloy plate.
In addition, this situation is technical common sense (in order to improve the creep resistance of a plate made of metal, it is necessary to improve the strength, but if the strength is improved, the bending workability of the plate will be reduced, that is, The creep resistance and the bending workability are in a trade-off relationship) and have been considered as a matter of course.

  Furthermore, since the technologies disclosed in Patent Documents 1 to 4 are technologies that do not consider weldability between the electrical connection component and a member such as a bonding wire, these technologies are applied to the electrical connection component. However, there is a possibility that excellent weldability cannot be obtained.

  Then, this invention makes it a subject to provide the aluminum alloy plate for electrical connection components which is excellent in creep resistance and bending workability, and also excellent in weldability, and its manufacturing method, hold | maintaining electroconductivity.

  In order to solve the above-mentioned problems, the inventors of the present invention determined that the average crystal grain size in the rolling direction on the plate surface of the aluminum alloy plate for electrical connection parts, the component composition, etc. are creep resistance, bending workability, conductivity. The present invention was created by finding that the ten-point average roughness (Rzjis) of the aluminum alloy plate for electrical connection parts affects the weldability.

That is, the aluminum alloy plate for electrical connection parts according to the present invention contains Si: 0.3 to 1.5% by mass, Mg: 0.3 to 1.0% by mass, and the remainder from Al and inevitable impurities. made is made of aluminum alloy, than the mean crystal grain size 150μm in the rolling direction of the plate surface, the average roughness ten points Ri der less 4.0 .mu.m, conductivity is 45% or more, the residual stress ratio is less than 65% characterized in that there.

According to this aluminum alloy plate for electrical connection parts, since the content of Si and Mg is specified within a predetermined range, creep resistance can be improved, and bending workability and electrical connection parts are required. Conductivity can also be ensured. Moreover, since the average crystal grain size in the rolling direction on the plate surface is specified to be a predetermined value or less, the bending workability can be improved.
Furthermore, according to the aluminum alloy plate for electrical connection parts, since the ten-point average roughness (Rzjis) is specified to be a predetermined value or less, the surface in contact with a member such as a bonding wire becomes sufficiently smooth. Excellent weldability can be ensured.

  In the aluminum alloy plate for electrical connection parts according to the present invention, the Cube orientation distribution density on the plate surface by crystal orientation distribution function analysis is preferably 20 or more with respect to the random orientation.

  According to the aluminum alloy plate for electrical connection parts, since the Cube orientation distribution density on the plate surface is specified to be a predetermined value or more, the creep resistance is improved more reliably and the bending workability is improved. Can do.

  Moreover, the aluminum alloy plate for electrical connection parts according to the present invention contains at least one of Cu: 0.10% by mass or less, Fe: 0.50% by mass or less, and Ti: 0.10% by mass or less. Also good.

  According to this aluminum alloy plate for electrical connection parts, since the content of Cu, Fe, Ti is regulated to a predetermined value or less, it is said that the creep resistance is improved while ensuring the effect of improving the bending workability. The effect can be further ensured.

The method for producing an aluminum alloy plate for electrical connection parts according to the present invention is a method for producing an aluminum alloy plate for electrical connection parts as described above , wherein Si: 0.3 to 1.5 mass%, Mg: 0.3 to A casting process for producing an ingot by melting and casting an aluminum alloy containing 1.0% by mass and the balance being Al and inevitable impurities, and homogeneity at 500 to 570 ° C. for 1 to 24 hours in the ingot A homogenization heat treatment step for performing a heat treatment, a hot rolling step for subjecting the ingot subjected to the homogenization heat treatment to rolling comprising a plurality of passes at a rolling start temperature of 350 to 450 ° C., 500 to 570 ° C., 100 A solution heat treatment step of performing a solution heat treatment for holding for less than a second, in order, a method of manufacturing an aluminum alloy plate for electrical connection parts, between the hot rolling step and the solution heat treatment step, and Melting Including a cold rolling step of performing cold rolling in at least one of the body heat treatment step, wherein the total cold working rate of the cold rolling is 35% or less.
Moreover, it is preferable that the total cold work rate of the said cold rolling is 20% or less as for the manufacturing method of the aluminum alloy plate for electrical connection components which concerns on this invention.

  According to this method for producing an aluminum alloy plate for electrical connection parts, the component composition of the aluminum alloy to be used is specified, the conditions for homogenization heat treatment, hot rolling and solution heat treatment are specified, and predetermined total cold working is performed. Cube orientation distribution density on the plate surface of the aluminum alloy plate for electrical connection parts manufactured by the manufacturing method is higher than a predetermined value, average crystal grain size and ten-point average roughness (Rzjis) Can be less than or equal to a predetermined value.

Moreover, the manufacturing method of the aluminum alloy plate for electrical connection parts which concerns on this invention may include the artificial aging treatment process of performing an artificial aging treatment after the last process among the said each process.
Moreover, the manufacturing method of the aluminum alloy plate for electrical connection components which concerns on this invention is the said aluminum alloy, Cu: 0.10 mass% or less, Fe: 0.50 mass% or less, Ti: 0.10 mass% or less. You may contain at least 1 sort (s) among them.

  According to this method for manufacturing an aluminum alloy plate for electrical connection parts, the content of Cu, Fe, Ti in the aluminum alloy to be used is regulated to a predetermined value or less, whereby aluminum for electrical connection parts manufactured by the manufacturing method is used. While ensuring the effect of improving the bending workability of the alloy plate, the effect of improving the creep resistance can be further ensured.

  The aluminum alloy plate for electrical connection parts according to the present invention specifies the content of Si and Mg within a predetermined range, and specifies the average crystal grain size and ten-point average roughness (Rzjis) of the plate surface to be below a predetermined value. Therefore, while maintaining conductivity, it is excellent in creep resistance and bending workability, and is also excellent in weldability, so that it can be suitably used as an electrical connection component.

  Further, according to the method for manufacturing an aluminum alloy plate for electrical connection parts according to the present invention, the composition of the aluminum alloy to be used is specified, the conditions for the homogenization heat treatment, hot rolling and solution heat treatment are specified, By performing cold rolling at the total cold work rate, it is possible to produce an aluminum alloy plate for electrical connection parts that has excellent creep resistance and bending workability while maintaining conductivity, and also has excellent weldability. .

It is a perspective view of the electrical connection component which concerns on this invention. (A)-(c) is a flowchart of the manufacturing method of the aluminum alloy plate for electrical connection components which concerns on this invention. It is a schematic diagram explaining the method of the bending test in the Example of this invention.

  Hereinafter, the form for implementing the aluminum alloy plate for electrical connection components which concerns on this invention, and its manufacturing method is demonstrated in detail.

[Aluminum alloy plate for electrical connection parts]
The aluminum alloy plate for electrical connection parts according to the present invention (hereinafter, appropriately referred to as “aluminum alloy plate”) contains a predetermined amount of Si and Mg, and the balance is composed of an aluminum alloy composed of Al and inevitable impurities, The average crystal grain size and ten-point average roughness (Rzjis) of the plate surface are not more than predetermined values.
In the aluminum alloy plate for electrical connection parts according to the present invention, the Cube orientation distribution density on the plate surface is preferably a predetermined value or more with respect to the random orientation, and the contents of Cu, Fe, and Ti are not more than the predetermined value. Preferably there is.

  Hereinafter, the reason why the respective alloy components, the average crystal grain size, the ten-point average roughness (Rzjis), and the Cube orientation distribution density on the plate surface are numerically limited will be described.

(Si: 0.3-1.5% by mass)
Si forms aging precipitates together with Mg during the artificial aging treatment after solution heat treatment. Since Si inhibits the movement of dislocations in a high temperature environment and improves creep resistance, Si is an essential element in the aluminum alloy plate for electrical connection parts according to the present invention.
If the Si content is less than 0.3% by mass, desired creep resistance cannot be obtained. On the other hand, if the Si content exceeds 1.5% by mass, coarse crystallized substances and precipitates are formed, and particularly bending workability is deteriorated or conductivity is deteriorated.
Therefore, the Si content is 0.3 to 1.5 mass%.
The Si content is preferably 0.4 to 1.5% by mass in order to ensure the effects of improving bending workability and creep resistance and ensuring conductivity. More preferably, it is -1.3 mass%.

(Mg: 0.3-1.0% by mass)
Mg forms an aging precipitate during the artificial aging treatment after solution heat treatment with Si. Since Mg inhibits the movement of dislocations under a high temperature environment and improves creep resistance, Mg is an essential element for the aluminum alloy plate for electrical connection parts according to the present invention.
If the Mg content is less than 0.3% by mass, desired creep resistance cannot be obtained. On the other hand, when the Mg content exceeds 1.0% by mass, coarse crystallized substances and precipitates are formed, and bending workability is particularly deteriorated.
Therefore, the Mg content is 0.3 to 1.0 mass%.
In addition, in order to make the effect of improvement of bending workability and creep resistance more reliable, the content of Mg is preferably 0.5 to 0.8% by mass.

(Inevitable impurities)
As an unavoidable impurity, Cu, Fe, Ti, or the like may be contained within a range that does not hinder the effects of the present invention. In detail, you may contain at least 1 sort (s) among Cu: 0.10 mass% or less, Fe: 0.50 mass% or less, and Ti: 0.10 mass% or less.
The reason is that if the Cu content exceeds 0.10% by mass, the bending workability deteriorates. Moreover, it is because bending workability or corrosion resistance will fall when content of Fe exceeds 0.50 mass%. Moreover, it is because electroconductivity will fall when content of Ti exceeds 0.10 mass%.
In addition, about Cu, Fe, and Ti, if it does not exceed the above-mentioned predetermined content, not only the case where it is contained as an unavoidable impurity but also the case where it is actively added, the effect of the present invention is achieved. I do not disturb.

Cu, Fe, and Ti are contained to some extent in scrap and recycled metal (for example, scraps of aluminum alloy material for clad materials such as brazing sheets). Gold can be blended to such an extent that the content of Cu, Fe, and Ti in the aluminum alloy plate is not more than the above range (or less), and the raw material cost can be reduced.
Further, as unavoidable impurities, elements other than Cu, Fe, and Ti (for example, Cr, Zn, Zr, V, Ni, Sn, In, Mn, Ga, etc.) are 0 to the extent that the effects of the present invention are not hindered. .05% by mass or less may be included.

(Average grain size in rolling direction: 150 μm or less)
The aluminum alloy plate for electrical connection parts according to the present invention has an average crystal grain size in the rolling direction on the plate surface of 150 μm or less.
When the average crystal grain size in the rolling direction is 150 μm or less, the bending workability can be improved, and the surface quality during bending can be improved. On the other hand, if the average crystal grain size in the rolling direction exceeds 150 μm, the possibility of rough skin and cracks on the surface during bending increases.
The average crystal grain size in the rolling direction is preferably 100 μm or less, and more preferably 50 μm or less in order to ensure the effect of improving the bending workability. Further, the average crystal grain size in the rolling direction is preferably 10 μm or more because manufacturing conditions become stricter and productivity is lowered when trying to make it excessively small.

The average crystal grain size in the rolling direction can be measured by the following method.
The surface of the aluminum alloy plate is mechanically polished by 0.05 to 0.1 mm, electrolytically etched, washed with water and dried, and then photographed at 100 times with an optical microscope. And the value of an average crystal grain diameter is computed from this micrograph using the intercept method in the rolling direction. In the measurement using the intercept method, one measurement line length is 0.95 mm, and the total measurement line length is 0.95 × 15 mm by observing a total of five fields per three fields. .

  The average grain size in the rolling direction is achieved by controlling the hot rolling start temperature, the rolling end temperature, etc. in the production process of the aluminum alloy sheet.

(10-point average roughness: 4.0 μm or less)
The aluminum alloy plate for electrical connection parts according to the present invention has a ten-point average roughness (Rzjis) of 4.0 μm or less. The ten-point average roughness is a roughness parameter defined in JIS B0601: 2001, and is the average of the absolute values of the altitudes (Yp) of the highest peak to the fifth peak in the reference length, This is a value obtained by summing up the absolute values of the elevations (Yv) of the bottom valley from the lowest valley bottom to the fifth.

When the ten-point average roughness (Rzjis) is 4.0 μm or less, the surface must be sufficiently smooth when welding electrical connection parts such as bus bars and members such as bonding wires by a welding method such as ultrasonic welding. Therefore, generation of voids at the joint interface after welding is suppressed and joint strength does not decrease, so that excellent weldability can be ensured. On the other hand, if the ten-point average roughness (Rzjis) exceeds 4.0 μm, voids are generated at the joint interface when welding electrical connection parts such as bus bars and members such as bonding wires, leading to a reduction in joint strength. , Will deteriorate the weldability.
In addition, about 10-point average roughness (Rzjis), in order to make the effect of the improvement of weldability more reliable, it is preferably 3.0 μm or less. Further, the ten-point average roughness (Rzjis) is preferably as small as possible.

Ten-point average roughness (Rzjis) can be measured using a commercially available measuring instrument in accordance with the provisions of JIS B0601: 2001.
The ten-point average roughness is achieved by controlling the ten-point average roughness and the total cold working rate on the surface of the cold rolling roll in the cold rolling process.

(Cube orientation distribution density: 20 or more)
The Cube orientation distribution density on the plate surface of the aluminum alloy plate for electrical connection parts according to the present invention is preferably 20 or more with respect to the random orientation.
When the Cube orientation distribution density on the surface of the plate is 20 or more, the creep resistance and the bending workability required for the electrical connection component can be reliably achieved. On the other hand, if the Cube orientation distribution density on the plate surface is less than 20, the bending workability is slightly lowered.
Note that the Cube orientation distribution density is preferably 30 or more in order to ensure the effect of improving creep resistance and bending workability.

According to a general manufacturing method, the Cube orientation distribution density is less than 20, which indicates that the crystal orientation of the plate surface is relatively random.
On the other hand, as specified by the present invention, when the Cube orientation distribution density is 20 or more, that is, when the Cube orientation is accumulated more than a certain amount, the proportion of small-angle grain boundaries having a small orientation difference between adjacent crystal grains increases. Reduce or eliminate grain boundary step during deformation.
In addition, in the Cube orientation, since a uniform slip deformation is possible compared to other orientations, formation of a shear band is suppressed.
As a result, since the formation of a shear boundary in the grain boundary step and the crystal grain which becomes the starting point or propagation path of the crack during bending is suppressed, the bending workability can be improved by setting the Cube orientation distribution density to 20 or more. Can improve (improve).
If the Cube orientation distribution density is excessively increased, the manufacturing conditions become severe and the productivity is lowered. Therefore, the Cube orientation distribution density is preferably 100 or less.

  Further, by setting the Cube orientation distribution density to 20 or more, even when compared with the same level of proof stress, the creep resistance required for the electrical connection component can be improved. The reason for this is not necessarily clear, but the Cube orientation is known to have a small Taylor factor and a small amount of dislocation momentum (Tatsumi et al .: Light Metals, 49 (1999), P. 583). It is presumed that the recovery during holding is suppressed.

  In the present invention, the Cube orientation distribution density is defined by the Cube orientation distribution density by crystal orientation distribution function analysis (hereinafter referred to as “ODF analysis” as appropriate).

  The Cube orientation distribution density by ODF analysis can express a wide range quantitatively because the Cube orientation is represented by a ratio (dimensionalless) from a random orientation (non-oriented Al powder sample of a standard sample). On the other hand, in the measurement based on the integrated intensity, since the in-plane (100 plane) rotational orientation cannot be separated, only a pure Cube orientation cannot be extracted.

  The measurement of the Cube orientation distribution density by ODF analysis on the plate surface of this aluminum alloy plate is performed using, for example, an X-ray diffractometer manufactured by Rigaku Corporation [model “Rigaku RAD-rX” (Ru-200B)]. This is done by measuring. The X-ray diffractometer can perform ODF analysis with an incomplete pole figure. That is, incomplete pole figures of {100} plane and {111} plane are created by schluz reflection method, ODF analysis is performed by applying Bunge's iterative series expansion method (positivity method), and Cube orientation distribution density Can be requested.

The relationship between the bending direction and the Cube orientation (orientation direction) when bending the aluminum alloy plate is set so that the Cube orientation of the plate is parallel to the bending direction of the plate (the bending direction of the plate is the material plate). When the material is bent (parallel or perpendicular to the rolling direction), the Cube orientation during deformation becomes stable, and good bending workability is obtained. Since the Cube orientation of the plate has the same structure even when rotated 90 degrees, there is no distinction between 0 degrees and 90 degrees. For this reason, even if the bending direction of the plate is parallel or perpendicular to the rolling direction of the material plate, the Cube orientation has the same structure, and good bending workability can be obtained.
However, in the relationship between the bending direction of the plate other than the above two directions and the Cube orientation (distribution direction) of the plate, such as the rolling direction of the plate being 45 degrees with the bending direction of the plate, the Cube orientation is being deformed. Since the crystal orientation is randomized and the bending workability may be inferior, it is preferable that the bending direction of the plate when bending is the above two directions.

  In addition, adjustment of the Cube orientation distribution density on the plate surface is performed by adjusting the Si content in the aluminum alloy plate, the Mg content, the hot rolling conditions in the manufacturing process of the aluminum alloy plate, and the total cold work rate of the cold rolling. Achieved by regulation.

(Conductivity: 45.0% IACS or higher)
The electrical conductivity of the aluminum alloy plate for electrical connection parts according to the present invention is preferably 45.0% IACS or more.
When the electrical conductivity is 45.0% IACS or more, the electrical conductivity as an electrical connection component can be ensured. On the other hand, if the electrical resistance is high, that is, the conductivity is less than 45.0% IACS, it is necessary to increase the cross-sectional area of the electrical connection component in order to pass a desired current, leading to an increase in the component weight.
The conductivity is preferably as high as possible, preferably 47.0% IACS or more, and more preferably 50.0% IACS or more.

The adjustment of conductivity is achieved by controlling the Si content, Mg content, homogenization heat treatment conditions, solution heat treatment conditions, and artificial aging conditions in the aluminum alloy sheet manufacturing process. The
If the conductivity is too high, that is, the creep resistance tends to decrease due to excessive decrease in the amount of solid solution and coarsening of precipitates, the conductivity is preferably 60% IACS or less.

(Yield strength: 130 MPa or more)
The proof stress (0.2% proof stress) of the aluminum alloy plate for electrical connection parts according to the present invention is preferably 130 MPa or more.
When the proof stress is 130 MPa or more, the creep resistance required for the electrical connection parts can be ensured. On the other hand, when the yield strength is less than 130 MPa, the creep resistance is lowered.
In order to secure the effect of ensuring creep resistance, the yield strength is preferably 175 MPa or more, and more preferably 180 MPa or more.

  The adjustment of the proof stress is achieved by the Si content in the aluminum alloy plate, the Mg content, the homogenization heat treatment condition, the solution treatment condition and the artificial aging treatment condition in the production process of the aluminum alloy sheet.

(Electrical connection parts)
The electrical connection component is a component that electrically connects a plurality of members. Specifically, an electrical connection component is an electrical connection between various electrical devices such as battery groups, inverters, motors, etc., or between components within an electrical device, which are mounted on various electric transportation devices that use electricity as a power source. It is a bus bar that is connected to each other. The electrical connection component is also a component required to bond a member such as a bonding wire to the surface.
And although an electrical connection component is not specifically limited about a shape, while it has predetermined thickness, it is a component which exhibits plate shape and square material shape. For example, the electrical connection component is a component having a shape as shown in FIG.

Here, since aluminum has a lower electrical conductivity than copper, in order to ensure conductive performance, the electrical connection component made of aluminum alloy must have a larger cross-sectional area than the electrical connection component made of copper. When considering the installation area of the component, it is often difficult to increase the width of the component, and the plate thickness increases. In general, when the plate thickness is increased, the amount of deformation on the bending surface increases, so that there is a problem of occurrence of bending cracks during bending in electrical connection parts made of aluminum alloys. The problem that the bending workability must be improved clearly appears.
In other words, the aluminum alloy plate for electrical connection parts according to the present invention is preferably applied to an electrical connection part having a thickness of 1.5 mm or more, in particular, 1.8 to 5.0 mm. Effect of achieving both compatibility and bending workability).

[Aluminum alloy plate for electrical connection parts before artificial aging treatment]
Up to this point, an aluminum alloy plate in a state after being subjected to artificial aging treatment (hereinafter referred to as “aluminum alloy plate after artificial aging treatment” as appropriate) has been described. Of course, the values of the average crystal grain size, the ten-point average roughness, and the Cube orientation are hardly changed.
Therefore, even if it is an aluminum alloy plate in a state before being subjected to artificial aging treatment (hereinafter referred to as “aluminum alloy plate before artificial aging treatment” as appropriate), if the above-mentioned requirements are satisfied, after the artificial aging treatment, The effect similar to the effect shown as the aluminum alloy plate can be obtained.
In addition, since the aluminum alloy plate before the artificial aging treatment is easier to form than the aluminum alloy plate after the artificial aging treatment, the user who purchased the aluminum alloy plate before the artificial aging treatment has performed the desired forming treatment. A use mode in which an artificial aging treatment described later is performed can be considered.

Next, the manufacturing method of the aluminum alloy plate for electrical connection parts according to the present invention will be described with reference to FIG.
[Method for producing aluminum alloy sheet for electrical connection parts]
The method for producing an aluminum alloy plate for electrical connection parts according to the present invention includes a casting step S1, a homogenization heat treatment step S2, a hot rolling step S3, and a solution heat treatment step S4, and a cold rolling step. SR (SR1, SR2) is included in at least one of between the hot rolling step S3 and the solution heat treatment step S4 and after the solution heat treatment step S4. Moreover, it is preferable that the manufacturing method of the aluminum alloy plate for electrical connection components which concerns on this invention further includes artificial aging treatment process S5.
Hereinafter, the respective steps will be mainly described.

(Casting process)
In the casting step S1, an aluminum alloy having the above component composition is melted, cast by a known casting method such as a DC forging method, cooled to below the solidus temperature of the aluminum alloy, and cast to a thickness of about 400 to 600 mm. Make a lump and chamfer as necessary.

(Homogenization heat treatment process)
In the homogenization heat treatment step S2, homogenization heat treatment (soaking) is performed at a predetermined temperature before rolling the ingot cast in the casting step S1. By subjecting the ingot to homogenization heat treatment, internal stress is removed, solute elements segregated at the time of casting are homogenized, and intermetallic compounds precipitated at the time of casting cooling and thereafter grow.
The heat treatment temperature (ingot temperature) in the homogenization heat treatment step S2 is 500 to 570 ° C. When the heat treatment temperature is less than 500 ° C., Si or Mg crystallized during casting remains undissolved, and an appropriate precipitate distribution cannot be obtained after solution heat treatment and artificial aging treatment, yield strength and creep resistance. Decreases. On the other hand, when it exceeds 570 ° C., local melting (burning) occurs on the surface of the ingot. More preferably, it is 560 degrees C or less.
The heat treatment time (holding time) in the homogenization heat treatment step S2 may be 1 hour or longer in order to complete the homogenization, and may be 24 hours or less from the viewpoint of production efficiency.

(Hot rolling process)
In the hot rolling step S3, the homogenized ingot is hot rolled. The rolling start temperature at this time shall be 350-450 degreeC. And it is set as the hot rolled sheet (hot coil) of desired plate | board thickness by performing the hot rolling which consists of a several path | pass.

(Mode of cooling after homogenization heat treatment)
Here, after the homogenization heat treatment, the mode when cooling to a temperature range of 350 to 450 ° C. where the hot rolling is started may be directly cooled to this temperature range and the hot rolling may be started within this temperature range. (Hereinafter also referred to as two-stage soaking). Moreover, it may be cooled to a temperature range of 350 ° C. or lower, and then further reheated to a temperature range of 350 to 450 ° C. at which hot rolling is started to start hot rolling in this temperature range (hereinafter, Also called twice soaking).

  When the hot rolling start temperature exceeds 450 ° C., it causes rough skin during bending. Moreover, if the hot rolling start temperature is less than 350 ° C., the hot rolling itself becomes difficult.

As will be described later, the present invention is characterized in that cold rolling is performed at a low processing rate (total cold working rate) after hot rolling (or after solution heat treatment). Is very important. In particular, the present inventors have found that recrystallized grains generated during hot rolling tend to be coarse and this structure is maintained even after solution heat treatment, which causes rough skin during bending. By setting the hot rolling start temperature to 450 ° C. or less, recrystallization during hot rolling can be suppressed, and the crystal grain size after the subsequent solution heat treatment can be set to a predetermined value or less. In addition, after the homogenization heat treatment, during cooling to the hot rolling start temperature, an Mg ₂ Si compound is formed in the ingot, and this Mg ₂ Si compound is recrystallized during hot rolling and solution heat treatment. Since it functions as a nucleation site for grains, the crystal grain size can be reduced.

Although the cooling rate to the hot rolling start temperature range after the homogenization heat treatment is not particularly specified, it is preferably in the range of 20 to 200 ° C./h. When the cooling rate is less than 20 ° C./h, the Mg ₂ Si compound becomes coarse. Therefore, in order to obtain a desired strength, a solution heat treatment is required for a long time, and productivity is increased. descend.
On the other hand, when the cooling rate exceeds 200 ° C./h, the temperature distribution in the ingot becomes non-uniform, and there is a possibility that a new problem in which an abnormality such as deformation or warping due to heat shrinkage occurs.

On the other hand, if the cooling rate is too high, the average size of the Mg ₂ Si compound formed while cooling to the hot rolling start temperature range after the homogenization heat treatment becomes too small, and it is necessary as a nucleation site for recrystallized grains. In addition, there is a possibility that an appropriate number of relatively coarse Mg ₂ Si compounds having a diameter of 2 μm or more cannot be distributed.

(Cooling means after homogenization heat treatment)
As a method for cooling the ingot, there are, for example, forced fan air cooling in the soaking furnace or outside the furnace, contact cooling, and cooling by mist or spray.

  The hot rolling end temperature is not particularly defined. However, the Cube orientation distribution density on the surface after the subsequent solution treatment can be increased by raising the hot rolling end temperature to 300 ° C. or more.

(Solution heat treatment process)
In the solution heat treatment step S4, solution rolling heat treatment is performed on the rolled plate manufactured in the hot rolling step S3 or the rolled plate manufactured in the cold rolling step SR1 described later. Here, the heat treatment temperature (ingot temperature) in the solution heat treatment step S4 is 500 to 570 ° C. When the heat treatment temperature is less than 500 ° C., undissolved Si or Mg remains, so that an appropriate precipitate distribution cannot be obtained after solution heat treatment and artificial aging treatment, and desired proof stress and creep resistance can be obtained. I can't. On the other hand, when it exceeds 570 ° C., local melting (burning) occurs on the plate surface. More preferably, it is 520-550 degreeC.
The holding time at the heat treatment temperature in the solution heat treatment step S4 is within 100 seconds (may be 0 seconds). This is because when the time exceeds 100 seconds, the effect is saturated and the productivity is lowered.

In the solution heat treatment step S4, the rate of temperature increase from 200 ° C. to the heat treatment temperature is preferably 5 ° C./s or more, and the rate of temperature decrease from the heat treatment temperature to 200 ° C. is 10 ° C./s or more. preferable.
By setting the temperature rising rate to be equal to or higher than the above rate, it is possible to ensure that the Cube orientation is appropriately developed. Moreover, desired intensity | strength can be acquired reliably by making temperature-fall rate more than the said speed | rate.

(Cold rolling process)
As shown in FIG. 2A, the cold rolling process SR may be performed twice in the order of the hot rolling process S3 → the cold rolling process SR1 → the solution heat treatment process S4 → the cold rolling process SR2 →. However, as shown in FIG. 2B, it may be performed once in the order of hot rolling step S3 → cold rolling step SR1 → solution heat treatment step S4 → as shown in FIG. 2C. The hot rolling step S3, the solution heat treatment step S4, the cold rolling step SR2, and the like may be performed once.
In the cold rolling process SR (SR1, SR2), the rolled sheet is rolled at a recrystallization temperature or lower (for example, room temperature) after the hot rolling process S3 or after the solution heat treatment process S4.

The total cold working rate in the cold rolling process SR is 35% or less. When the total cold work rate exceeds 35%, the bending workability is lowered.
In particular, when the total cold work rate becomes 20% or less, the Cube orientation distribution density of the manufactured aluminum alloy plate becomes 20 or more with respect to the random orientation, and the creep resistance and bending workability required for electrical connection parts Can be reliably achieved.
Therefore, the total cold working rate in the cold rolling step SR is preferably 20% or less.
If the 10-point average roughness of the surface of the aluminum alloy plate can be reduced to a desired value, the total cold work rate may be 0%, but it is preferable to ensure the 10-point average roughness. Is 1% or more, more preferably 5% or more.

  Note that the surface of the cold rolling roll used in the cold rolling step SR is a factor that affects the ten-point average roughness of the aluminum alloy sheet. Specifically, in order to reduce the ten-point average roughness of the aluminum alloy sheet, the ten-point average roughness of the surface of the cold rolling roll is preferably as small as possible.

Here, the total cold work rate is the total reduction rate in the cold rolling process SR (SR1, SR2), and “total cold work rate (%) = (sheet thickness after the hot rolling process S3− The thickness after the artificial aging treatment step S5) / the thickness after the hot rolling step S3 × 100 ”.
In the above formula, “plate thickness before artificial aging treatment step S5” may be used as “plate thickness after artificial aging treatment step S5”.

(Artificial aging treatment process)
In the artificial aging treatment step S5, the artificial aging treatment is performed at a predetermined temperature and a predetermined time on the rolled plate subjected to the solution heat treatment in the solution heat treatment step S4 or the cold rolled sheet SR2 in the cold rolling step SR2. Apply.
Although it does not specifically limit about the heat processing temperature in artificial aging treatment process S5, It is preferable that it is 150-250 degreeC. When the temperature is lower than 150 ° C., desired proof stress and creep resistance cannot be obtained, and when the temperature exceeds 250 ° C., precipitates are coarsened and the proof strength and creep resistance are lowered. Further, the heat treatment time is not particularly limited, but is preferably 1 to 30 hours. If the time is less than 1 hour, particularly when mass production is assumed, a non-uniform temperature distribution occurs in the coil or the sheet, and the material characteristics tend to become unstable. In consideration of productivity, the upper limit is 30 hours.

  The manufacturing method of the aluminum alloy plate for electrical connection parts according to the present invention is as described above, but in performing the present invention, within the range that does not adversely affect the respective steps, before or after each step, Other steps may be included. For example, after the artificial aging treatment step S5, a cutting step for cutting the aluminum alloy plate into a predetermined size and a processing step for processing into a predetermined shape as shown in FIG. 1 (bending, punching, etc.) are included. May be. Moreover, you may include a cutting process and a process process before artificial aging treatment process S5.

  In addition, as for conditions that are not clearly shown in the respective steps, it is sufficient to use conventionally known conditions, and it is needless to say that the conditions can be appropriately changed as long as the effects obtained by the processing in the respective steps are exhibited.

Next, the aluminum alloy plate for electrical connection parts and the manufacturing method thereof according to the present invention will be specifically described by comparing an example satisfying the requirements of the present invention with a comparative example not satisfying the requirements of the present invention.
[Production of test materials]
Aluminum alloys (alloys 1 to 19) having the compositions shown in Table 1 were melted, ingots were produced by semi-continuous casting, and surface treatment was performed. The ingot was subjected to homogenization heat treatment under the conditions shown in Table 2, and then hot rolled at a rolling rate of 99% to obtain a hot rolled sheet. Thereafter, cold rolling was performed (except for some test materials), and solution heat treatment was performed under the conditions shown in Table 2. Then, after the solution heat treatment, it is cold-rolled (except for some sample materials), and is subjected to an artificial aging treatment that is held at 200 ° C. for 4 hours (the sample material 27 is not applied). (Thickness 2.0 mm) was produced.
In addition, about sample materials 1-6 and 16-20, soaking is performed by two-stage soaking, and about sample materials 7-15, 21, 22, and 24-26, soaking is performed twice soaking. went.

[Evaluation]
(10-point average roughness)
The ten-point average roughness (Rzjis) was measured according to the provisions of JIS B0601: 2001 using a contact roughness measuring machine (Surfcom 480A) manufactured by Tokyo Seimitsu Co., Ltd. The measurement conditions were a cut-off value of 0.8 mm, an evaluation length of 8.0 mm, a measurement speed of 0.6 mm / s, and a contact needle tip radius of 2 μmR. Ten points average roughness (Rzjis) was determined from each of the obtained roughness curves, and the average value was taken as the ten point average roughness (Rzjis) of the test material.

(Measurement of average crystal grain size)
The surface of the test material was mechanically polished by 0.05 to 0.1 mm, electrolytically etched, washed with water and dried, and then photographed with an optical microscope at 100 times. And the value of the average crystal grain diameter was computed from this micrograph using the intercept method in the rolling direction. In the measurement using the intercept method, one measurement line length was 0.95 mm, and a total of five fields were observed with three lines per field, so that the total measurement line length was 0.95 × 15 mm. .

(Cube orientation distribution density)
By measuring the surface of the prepared specimen using an X-ray diffractometer manufactured by Rigaku Corporation [model “Rigaku RAD-rX” (Ru-200B)], the Cube orientation distribution density with respect to the random orientation was determined. . ODF analysis was performed using an incomplete pole figure using the X-ray diffractometer. In detail, the incomplete pole figure of {100} plane and {111} plane is created by schluz reflection method, ODF analysis is performed by applying Bunge's iterative series expansion method (positivity method), and Cube orientation The distribution density was determined.

(Tensile test)
A test piece of JIS No. 5 was cut out from the specimen so that the tensile direction was parallel to the rolling direction. Using this test piece, a tensile test was performed according to JISZ2241: 2011, and tensile strength, yield strength (0.2% yield strength), and elongation were measured.
The crosshead speed was 5 mm / min, and the test was performed at a constant speed until the test piece broke.

(conductivity)
The conductivity was measured by an eddy current conductivity measuring device [model “Sigma Test D2.068”] manufactured by Nippon Ferster Co., Ltd. In addition, the measurement of the conductivity was performed at any five locations on the surface of the test material with a space of 100 mm or more between each other. The electrical conductivity in the present invention is obtained by averaging the measured electrical conductivities. When the value of this conductivity was 45.0% IACS or more, it was evaluated that the conductive performance as an electrical connection component could be secured.

(Bending workability)
A test piece of JIS No. 3 (JISZ2204) was cut out from the specimen so that the longitudinal direction of the test piece coincided with the rolling direction. The test piece was subjected to a bending test by the V block method in accordance with JISZ2248: 2006 (see FIG. 3), and the bending workability was evaluated. The bending test was performed under the conditions of θ (bending angle): 90 °, r (inner bending radius): 0 mm, and t (test material plate thickness): 2 mm.
Observe the occurrence of cracks in the bent part (curved part, width: 30 mm) after the bending test, and among the five test pieces, all of the test pieces that did not generate rough skin or cracks were very good (○ ), One having at least one acceptable level of rough skin or cracking is good (△), remarkable skin roughness or cracking with a crack length of 2 mm or more occurring in one or more sheets (×), or A crack having a crack length of 2 mm or more in all five sheets (XX) was evaluated as defective.

(Residual stress ratio)
The residual stress ratio was measured by the cantilever method described in the Japan Electronic Materials Manufacturers Association Standard EMAS-3003.
Specifically, a strip-shaped test piece (sample thickness: 2 mm) having a width of 10 mm and a length of 250 mm was cut out so that the longitudinal direction of the test piece was perpendicular to the rolling direction. One end of the test piece was fixed to a rigid test table. The test piece was given a span of 150 mm and an initial deformation amount (δ0 = 10 mm), held in that state at 120 ° C. for 100 hours, and then the stress was removed to measure the deformation amount (ε) of the test piece. The residual stress ratio was determined by “residual stress ratio = (δ0−ε) ÷ δ0 × 100”. This residual stress ratio value of 65% or more has the ability to withstand the phenomenon (creep) that is deformed by continuous stress at high temperatures, that is, has the creep resistance required for electrical connection parts. Then I evaluated.

(Weldability)
When the 10-point average roughness (Rzjis) of the surface of the specimen shows a large value, when welding the specimen (electrical connection part) and a member such as a bonding wire by a welding method such as ultrasonic welding, at the joint interface Voids are generated, resulting in a decrease in bonding strength and weldability.
Here, when the ten-point average roughness (Rzjis) on the surface of the test material is 4.0 μm or less, the generation of voids can be sufficiently suppressed and the decrease in bonding strength can be avoided, so that the Rzjis is 4.0 μm or less. The weldability was evaluated as good (◯), and the weldability of Rzjis exceeding 4.0 μm was evaluated as poor (×).

  Detailed aluminum alloy components, production conditions for the test materials, and material properties (test results) are shown in Table 1 or Table 2. In Tables 1 and 2, numerical values that do not satisfy the configuration of the present invention are underlined.

[Examination of results]
About the test materials 1-15, since the requirements prescribed | regulated by this invention are satisfy | filled, even when it is set as very severe bending process conditions with internal bending R = 0mm, it is said that bending workability is favorable ((triangle | delta)) or more. In addition to the evaluation, the creep resistance required for electrical connection parts was evaluated. Furthermore, about the test materials 1-15, while being excellent in weldability, it became evaluation that the electrical conductivity also satisfy | fills the level requested | required of an electrical connection component.
Among them, the specimens 1 to 10, 14, and 15 have a total cold working rate of 20% or less and satisfy the requirements defined by the present invention for the Cube orientation distribution density, so that the bending workability is extremely high. The result was good (◯).

  In the test material 16 (alloy 11), the Si content was less than the lower limit of the numerical range defined in the present invention, and the average crystal grain size was large, so that the bending workability was poor and the proof stress was low. As a result, the evaluation was that the creep resistance was not excellent.

Since the sample material 17 (alloy 12) had an Si content exceeding the upper limit of the numerical range defined in the present invention, the electrical conductivity was low and the creep resistance was not excellent.
In the test material 18 (alloy 13), the Mg content was less than the lower limit of the numerical range defined in the present invention, and the average crystal grain size was large, so that the bending workability was poor and the proof stress was low. As a result, the evaluation was that the creep resistance was not excellent.

The specimen 19 (alloy 14) had a poor bending workability because the Mg content exceeded the upper limit of the numerical range specified in the present invention.
The test material 20 (alloy 15) had a poor bending workability because the Cu content exceeded the upper limit of the numerical range defined in the present invention.

The specimen 21 (alloy 16) had a poor bending workability because the Fe content exceeded the upper limit of the numerical range specified in the present invention.
In the test material 22 (alloy 17), the Ti content exceeded the upper limit of the numerical range defined in the present invention, so that the conductivity was less than 45.0% IACS, resulting in poor conductivity. .

  Since the heat treatment temperature of the homogenization heat treatment exceeded the upper limit value of the numerical value range defined in the present invention, the test material 23 was burned and could not be manufactured and tested thereafter.

Since the heat treatment temperature of the solution heat treatment exceeded the upper limit value of the numerical range defined in the present invention, burning occurred in the test material 24, and the subsequent manufacturing and testing could not be performed.
Since the sample material 25 had a large average crystal grain size, the bending workability was poor.

  Since the test material 26 was not cold-rolled, the ten-point average roughness exceeded the upper limit of the numerical range defined by the present invention, resulting in poor weldability.

The test material 27 (alloy 18) had a Cu content exceeding the upper limit of the numerical range defined in the present invention, and the average crystal grain size was large, resulting in poor bending workability (XX). It became.
Moreover, since the specimen 28 (alloy 19) had a Cu content exceeding the upper limit of the numerical range defined in the present invention, the bending workability was poor (xx).

  The test material 27 is assumed to be an aluminum alloy plate described in Patent Document 2, and the test material 28 is assumed to be an aluminum alloy plate described in Patent Document 1.

  For some specimens, Rzjis, average crystal grain size, and Cube orientation distribution density were measured not only after the artificial aging treatment but also before the artificial aging treatment. The measured values were almost the same.

1 Busbar (electrical connection parts)
1a Connecting part

Claims (7)

Si: 0.3-1.5% by mass, Mg: 0.3-1.0% by mass, the balance is composed of an aluminum alloy consisting of Al and inevitable impurities,
The average grain size in the rolling direction of the plate surface 150μm or less, an average roughness ten points Ri der less 4.0 .mu.m,
An aluminum alloy plate for electrical connection parts, wherein the electrical conductivity is 45% or more and the residual stress ratio is 65% or more .   The aluminum alloy plate for electrical connection parts according to claim 1, wherein the Cube orientation distribution density on the surface of the plate by crystal orientation distribution function analysis is 20 or more with respect to the random orientation.   3. The electricity according to claim 1, comprising at least one of Cu: 0.10 mass% or less, Fe: 0.50 mass% or less, and Ti: 0.10 mass% or less. Aluminum alloy plate for connecting parts. It is a manufacturing method of the aluminum alloy plate for electrical connection parts according to claim 1 or 2,
Casting for producing an ingot by melting and casting an aluminum alloy containing Si: 0.3 to 1.5 mass%, Mg: 0.3 to 1.0 mass% with the balance being Al and inevitable impurities Process,
A homogenization heat treatment step of subjecting the ingot to a homogenization heat treatment at 500 to 570 ° C. for 1 to 24 hours;
A hot rolling step of rolling the ingot subjected to the homogenization heat treatment to form a plurality of passes at a rolling start temperature of 350 to 450 ° C .;
A solution heat treatment step of applying a solution heat treatment to hold at 500 to 570 ° C. for 100 seconds or less;
A method for producing an aluminum alloy plate for electrical connection parts in order,
Including a cold rolling step of performing cold rolling between the hot rolling step and the solution heat treatment step and at least one after the solution heat treatment step, and the total cold working rate of the cold rolling Is 35% or less, The manufacturing method of the aluminum alloy plate for electrical connection components characterized by the above-mentioned.   The method for producing an aluminum alloy plate for electrical connection parts according to claim 4, wherein a total cold working rate of the cold rolling is 20% or less.   The method for producing an aluminum alloy plate for electrical connection parts according to claim 4 or 5, further comprising an artificial aging treatment step of performing an artificial aging treatment after the last step among the respective steps.   The said aluminum alloy contains at least 1 sort (s) among Cu: 0.10 mass% or less, Fe: 0.50 mass% or less, and Ti: 0.10 mass% or less. 6. The method for producing an aluminum alloy plate for electrical connection parts according to claim 1.

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