JP2000207940A - Conductor of al alloy for automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductor of Al alloy superior in electrical characteristics and corrosion resistance, without reducing creep resistance to less than that of steel at a high temperature caused due to fastening of a bolt. SOLUTION: This conductor is made of an Al alloy containing 3-0.8% (wt.% and it is applicable to those in the following) of Si, 0.35-1.0% of Mg. one kind or at least two kinds selected from among 0.1-0.6% of Fe, 0.02-0.1% of Cu and 0.01-0.08% of Mn, and its remaining part comprises Al and unavoidable impurities. Its refining is a T6 material, a T8 material or a T5 material. It has a Ni plated coating with a thickness of 3-10 μm as a first layer on its surface, and has a Sn plated coating with a thickness of 2-10 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for electrically connecting a battery group of an electric vehicle and electric devices (inverters, motors, etc.), connecting between batteries, and supplying a large current to a circuit in the inverter. The present invention relates to a conductor made of an Al alloy, which is used to perform the following. In this specification, all the Al alloy compositions mean wt%, but this is simply described as%.

[0002]

2. Description of the Related Art Electric vehicles include a battery group, an inverter,
Various electric devices such as motors are used. Conventionally, pure copper material is often used as a conductive base material (a conductor having a rectangular shape or a plate shape and hereinafter referred to as a conductor) for electrically connecting the battery group and electric devices, between batteries, circuits in an inverter, and the like. They are connected mainly by bolting.

[0003] However, in recent years, there has been a demand for a reduction in the weight of automobiles due to the need to reduce fuel consumption, and there is a strong demand that the above-mentioned conventional copper conductor be made of lightweight Al or Al alloy. On the other hand, as the conductive Al and Al alloy materials for power distribution facilities on the ground, conventionally, 1060 (Al
Min. 99.60% pure Al), 6101 (Al-0.5% Si-0.5% Mg)
Alloy), 6063 (Al-0.4% Si-0.7% Mg alloy), 6061
(Al-0.6% Si-1.0% Mg-0.3% Cu-0.2% Cr alloy) is known (JIS H 4180). Table 1 shows the composition and conductivity of these alloys.
Shown in

[0004]

[Table 1]

When the conventional copper conductor is replaced with aluminum, the specific gravity of copper is 8.89, the specific gravity of aluminum is 2.70, and the conductivity of pure copper is 100% IACS. Since the conductivity of pure aluminum 1060 in this case is 61% IACS or more, when a conductor having the same electrical resistance as copper is used, the cross-sectional area increases to 160% of copper, but the weight is 50%, which is large. Decrease. Also,
When a conductor having the same current as copper is used, the cross-sectional area is 125% but the weight is only 40%. From these facts, if aluminum is used for a conductor under the same electrical conditions as copper, it will suffice to weigh 1/2 or less than copper.

Table 2 shows that 1060 (pure Al), 6101,
Fig. 4 shows typical mechanical properties of copper (pure copper) at room temperature.

[Table 2]

As shown in Tables 1 and 2, pure aluminum 1060 has the highest conductivity among aluminum conductors, but has low mechanical strength at room temperature. Alloy (Al-Mg
-Si-based conductor 6101-T6 has the same mechanical strength at room temperature as copper-1 / 2H and a conductivity of 55-T6.
The highest among Al alloys at% IACS or higher. Therefore, it is considered that a material equivalent to 6101 alloy having excellent strength and electrical conductivity is most suitable as an aluminum conductor instead of copper.

Conventionally, most of the above Al and Al alloy conductors used for power distribution facilities on the ground are mostly used without any surface treatment. In electrical equipment that requires
Ag plating or Sn-Zn alloy solder (friction solder) plating may be used.

[0009]

SUMMARY OF THE INVENTION A conductor for automobiles has
When pure Al or an Al alloy is used in place of the copper conductor, pure Al has a high electrical conductivity of 61% IACS or more, but low mechanical strength, and alloys 6063 and 6061 have relatively high mechanical strength but high electrical conductivity. The rate is low at less than 55% IACS. Accordingly, as a conductor made of an Al alloy for an automobile, a material equivalent to the 6101 alloy is considered to be appropriate in terms of strength and electrical conductivity (55% IACS or more). Consideration is needed.

That is, when the above-mentioned Al alloy material is applied to an application for automobiles, the temperature rise during energization (for example, 100
℃) and its temperature decreases, and it is used for a long period of time, so the material of the bolted part is not easily deformed, that is, the creep resistance is equal to or higher than the conventional copper material It is necessary to satisfy requirements such as that the corrosion resistance is good in the connection part and the parts other than the connection part, and that the electrical characteristics (contact resistance) of the connection part are good. Therefore, it is desirable that the Al alloy material for electric conductivity has a creep resistance at a high temperature equal to or higher than that of a conventional copper material and has an electric conductivity as high as possible (55% IACS or more).
In addition, the corrosion resistance as a conductor and the electrical characteristics of the connection portion are A
It is necessary to solve the problem by performing a preferable surface treatment on the alloy material. An object of the present invention is to find a preferable Al alloy material that satisfies the above requirements, and to find a preferable surface treatment method on an Al alloy member.

[0011]

According to a first aspect of the present invention, there is provided a semiconductor device comprising: 0.3% to 0.8% of Si;
0.35 to 1.0%, and 0.1 to 0.1% Fe.
6%, Cu 0.02-0.1%, Mn 0.01-0.0
8%, one or more of which are Al alloys with the balance being Al and unavoidable impurities.
Material or T8 material or T5 material, and the first surface
An Al alloy automotive conductor characterized by having a Ni plating film having a thickness of 3 to 10 μm as a layer and a Sn plating film having a thickness of 2 to 10 μm as a second layer thereon.

Further, the invention according to claim 2 has a Ni plating film having a thickness of 3 to 7 μm as a first layer on the surface of the Al alloy material, and a Sn plating having a thickness of 2 to 8 μm as a second layer. 2. The Al according to claim 1, having a plating film.
It is an alloy conductor for automobiles.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration, operation and effect of the present invention and specific embodiments will be described below in detail. The reason why the Al alloy material used in the present invention is limited in this way is as follows.

The alloy element Si of the Al alloy according to the present invention,
Mg has the effect of increasing the material strength and preventing deformation when used as a conductive material. One of the functions of Si and Mg to increase the material strength is solid solution hardening due to solid solution mainly in an aluminum matrix. When added below the lower limit of each component range, a sufficient effect cannot be obtained because the amount of solid solution is small, and when added beyond the upper limit of the component range, the conductivity is reduced and the conductive material is used. Performance is reduced. Further, Si and Mg are finely precipitated as Mg ₂ Si particles, and have an effect of precipitation hardening. Si
If each of Mg and Mg is less than the specified values, the precipitation of Mg ₂ Si particles is so small that sufficient strength cannot be obtained. On the other hand, if too much is added, the size of the Mg ₂ Si particles becomes large and the formability is reduced.

Next, in addition to the above-mentioned Si and Mg, the Al alloy according to the present invention further includes a predetermined amount of Fe, Cu, Mn.
Or one or more of these. Fe, Mn
Forms an intermetallic compound with Al and improves the strength of the material by dispersion strengthening. When the amount is small, the effect cannot be obtained, and when the amount is large, the moldability decreases. In addition, the finely precipitated intermetallic compounds stabilize the sub-crystal grain structure and the recrystallized grain structure, and improve the creep resistance by inhibiting the recovery of strain in the structure due to heat generation during energization. Although Cu strengthens the material by forming a solid solution in the aluminum matrix, Cu improves the creep resistance of the material during energization. Below the lower limit of the component range,
The effect is not sufficiently exhibited, and if it exceeds the upper limit, the moldability is reduced.

Next, the Al alloy material (rolled material, extruded material) according to the present invention has a temper of T6 material, T8 material or T5 material.
Material. This is to obtain a predetermined strength. By using a T6 material, a T8 material, or a T5 material for the refining, a predetermined strength and a predetermined creep resistance (high-temperature strength) can be obtained. This refining will be described later in detail as a preferred production method, but T6 and T8 are applied to both rolled and extruded materials. T6 is for performing an age hardening treatment following the solution treatment (quenching) in the manufacturing process at the end of the material, and T8 is for performing an age hardening treatment after the solution treatment and cold working. Further, the temper T5 is applied only to the extruded material, and is subjected to cooling (quenching) after hot extrusion to a predetermined cross-sectional dimension, followed by age hardening treatment without a special solution treatment (quenching) step. Things.

The mechanical strength at room temperature of each tempering material is as follows. Tensile strength (kgf / mm ²⁾ yield strength (kgf / mm ²⁾ elongation (%) T5 material 16-22 14-20 8% or more T6 material 18-24 16-22 10% or more T8 material 24-30 22-28 6% or more

The Al alloy conductor of the present invention is characterized in that
An alloy having a thickness of 3 to 10 μm as a first layer on the surface of an Al alloy material whose tempering is T6 material, T8 material or T5 material.
m, and a 2-10 μm thick Sn plating film as a second layer thereon. A
By performing such two-layer plating on the surface of the alloy material, a conductor having excellent corrosion resistance and electrical characteristics (electrical contact resistance of the connection portion) can be obtained. The Ni plating in the present invention is for improving the corrosion resistance of the entire surface of the conductor made of an Al alloy, and the Sn plating is for ensuring the electrical characteristics particularly of the connection part.

In the present invention, the thickness of the Ni plating is
3 to 10 μm. If the thickness is as thin as less than 3 μm, sufficient corrosion resistance cannot be maintained, and 10 μm
When the thickness exceeds 0.1 mm, the Ni plating is easily broken and the plating cost is increased. The thickness of the Sn plating is 2 to 10 μm. If the thickness is less than 2 μm, sufficient electrical contact cannot be ensured. If the thickness is more than 10 μm, the characteristics will not be affected. A more preferable range of the plating film thickness is 3 to 7 μm in thickness of Ni plating and 2 to 8 μm in thickness of Sn plating in view of the above characteristics and cost (claim 2).

As described above, the Al alloy automobile conductor according to the present invention is mainly used for electric connection between various electric devices such as battery groups of electric vehicles, inverters, motors, etc., between batteries, and circuits in the inverter. Etc. are used as conductors for electrical connection. Therefore, the shape of the conductor to be used is a rectangular material (for example, a cross section of 2 mm × 20 mm or the like) or a plate material (for example, a thickness of 2 mm × 200 mm × 200 mm).
Etc.), which are cut, punched, bent, perforated, or the like into a shape suitable for use, and further subjected to the above-mentioned plating to become conductors for connection to electrical equipment and the like.

The above flat material or plate material can be manufactured by rolling or extruding an AL alloy. Hereinafter, this preferred manufacturing method will be described in detail. First, when the above-mentioned Al alloy material is manufactured by rolling, an Al alloy ingot having the above-described alloy composition is manufactured by a normal method such as a semi-continuous casting method, and is manufactured by a method of 500 to 54 mm.
Hot rolling is performed after holding at a temperature of 0 ° C., and then cold rolling is performed to a predetermined plate thickness.At that time, before the cold rolling or during or after the cold rolling,
After maintaining at a temperature of 500 ° C. or higher, cooling (cooling at a cooling rate of 1 ° C./sec or higher up to 200 ° C.) [solution treatment]. Subsequently, predetermined cold rolling is performed as necessary, and finally, a heat treatment of artificial age hardening maintained at 150 to 250 ° C. is performed. In other words, hot rolling or cold rolling → solution treatment (quenching) →
A process of cold rolling → artificial age hardening (T8 treatment) or a process of cold rolling → solution treatment (quenching) → artificial age hardening (T6 treatment).

The reason why the ingot is kept at a temperature of 500 to 540 ° C. before hot rolling is to increase the amount of the added element in solid solution.
If the temperature is lower than 500 ° C., the solid solution is not sufficiently formed. If the temperature exceeds 540 ° C., the ingot may be partially melted.
Further, the temperature is maintained at 500 ° C. or more before cold rolling, during cold rolling or after cold rolling, and then cooled (200 ° C.).
Cooling at a cooling rate of 1 ° C./sec or more until
This is because, even when the holding temperature is less than 500 ° C. and the cooling rate is less than 1 ° C./sec, the solid solution of the added element becomes insufficient. The subsequent holding at 150 to 250 ° C. is for the purpose of further improving the strength of the conductive material by causing the Mg, Si, and Cu component elements excessively dissolved to precipitate out as Mg ₂ Si and Cu compounds. If the treatment temperature is lower than 150 ° C., sufficient strength cannot be obtained due to insufficient precipitation, and if it is higher than 250 ° C., coarse precipitates are generated, and sufficient strength cannot be obtained. Therefore, in the production of the Al alloy material according to the present invention by rolling, it is preferable to employ the above-described production method.

Next, when this Al alloy material is manufactured by extrusion, an Al alloy ingot (a billet) having the above-mentioned alloy composition is manufactured by a conventional method such as a semi-continuous casting method, and is manufactured by a conventional method.
After holding at a temperature of 00 to 540 ° C., hot extrusion is performed, and then cold drawing is performed to a predetermined cross-sectional dimension. At this time, 500 mm before or during or after the cold drawing. After the temperature is maintained at a temperature of not less than 200 ° C., cooling (cooling is performed at a cooling rate of 1 ° C./sec or more up to 200 ° C.) Subsequently, predetermined cold drawing is performed as necessary, and finally 150 to 25
The heat treatment for artificial age hardening is carried out at 0 ° C. In other words, the above manufacturing method is a step of hot extrusion or cold drawing → solution treatment (quenching) → cold drawing → artificial age hardening treatment (T8 treatment) or hot extrusion or cold drawing. It is a process of thinning → solution treatment (quenching) → artificial age hardening treatment (T6 treatment). In addition, a special solution treatment (quenching) step is omitted, and after hot extrusion to a predetermined cross-sectional dimension, cooling (cooling at a cooling rate of 1 ° C./sec or more up to 200 ° C.) → artificial age hardening. (T5 processing) can also be performed.

The reason why the ingot is kept at a temperature of 500 to 540 ° C. before hot extrusion as a homogenization treatment of the ingot, and the solution treatment (quenching) is kept at a temperature of 500 ° C. or more and then cooled ( The reason for cooling at a cooling rate of 1 ° C./sec or more up to 200 ° C.) and the reason for keeping the artificial aging hardening treatment at 150 to 250 ° C. are the same as the reasons described in the method for producing a rolled plate.

By manufacturing the Al alloy material according to the present invention as described above, excellent conductivity, strength, and creep resistance can be obtained. In addition, a conductor having excellent corrosion resistance and electrical characteristics can be obtained by further plating the surface of the Al alloy material thus manufactured with the two layers of Ni plating and Sn plating.

[0026]

EXAMPLES Examples of the present invention will be described below in more detail together with comparative examples. [Example 1] A plate material for a conductor was produced for an Al alloy material within the alloy composition range according to the present invention shown in Table 3 and a comparative Al alloy material outside the range. That is, after melting and casting to the alloy composition shown in Table 3, this ingot was subjected to a homogenizing heat treatment (soaking) at 540 ° C., and this was hot-rolled and subsequently cold-rolled to obtain a sheet material having a sheet thickness of 5 mm. This sheet material was subjected to a solution treatment at 540 ° C., then cooled to 200 ° C. at a cooling rate of 20 ° C./sec, and then subjected to an age hardening treatment at 200 ° C. for 2 hours, thereby obtaining test pieces No. 1 and No. .3 to No.12 (T6 material). The test material No. 2 was hot-rolled, then cold-rolled to a thickness of 7 mm, subjected to the solution treatment described above, and then processed to a thickness of 5 mm.
Cold-rolled and subjected to the above age hardening treatment to obtain a test material (T8 material).

[0027]

[Table 3]

The electrical conductivity of these test materials was measured at room temperature and is shown in Table 3. In addition, in order to check the creep resistance of the bolted connection in the high temperature state of these test materials,
The following tests were performed. That is, a sheet material sample 5 mm x 20 m
A constant pressure load (1.2 ton / cm ² ) was applied to the surface of mx 20 mm, heated in this state, and kept at 120 ° C for 3 hours. Next, this was cooled to room temperature, and the change (decrease) of the original plate thickness of 5 mm was measured, the change rate (%) of the material was obtained, and the creep resistance of the material was evaluated. The results are shown in Table 3.

For reference, a conventional copper material (H14) and pure Al (1060-H14), which serve as references, were also tested in the same manner to evaluate their electrical conductivity and creep resistance. did. As is clear from Table 3, the amount of deformation of the Al alloy conductor according to the present invention in a high temperature state is as follows.
It is equal to or more than conventional copper material, and the electrical conductivity is 55% IACS.
It turns out that it is above. The comparative Al alloy material has a large deformation amount in a high temperature state or a conductivity of 5%.
Less than 5% IACS.

[Embodiment 2] No. 2 in Table 3 of Embodiment 1 5mm, which is an Al alloy material of No. 1 and has a bolt hole diameter of 8mm
(Thickness) × 30 mm × 100 mm plate material (T6) was subjected to various plating treatments as shown in Table 4 to obtain test materials. Table 4 shows a comparison of the processing costs for these various plating processes. In addition, these test materials were
Combine the sheets (joint part 10mm), constant pressure load is 1.2ton / c
The bolts were tightened so as to obtain m ² (the tightening torque of the bolts was 1.2 kg · m). The tightening bolt has a bolt diameter of 6 mm, a flanged bolt and a nut (diameter of the flange portion is 12 mm). This bolt is made of stainless steel and is plated with Cr.

For the test material thus tightened, 1
After holding at 20 ° C. for 12 hours, a heat cycle test of holding at room temperature for 12 hours (1 cycle) was performed for 240 hours (10 cycles,
10th). The electrical contact resistance before and after this test was measured, and the results are shown in Table 4. Further, the sample after the heat cycle test was subjected to a corrosion resistance test.
This test was performed for 96 hours (4 days) by a salt spray test. The corrosion state of the pressurized connection portion (including the vicinity thereof) with bolts and the corrosion state other than the connection portion was observed, and the results are shown in Table 4. .

[0032]

[Table 4]

As apparent from Table 4, the samples within the scope of the present invention (Ni plating thickness: 3 to 10 μm, Sn plating thickness: 2 to 10 μm) have the plating treatment cost, electrical contact resistance before and after the thermal cycle test, and corrosion resistance. Were good. It can be seen that samples outside the scope of the invention are inferior in processing cost, contact resistance and corrosion resistance.

[0034]

As described in detail above, A according to the present invention
The alloy conductor for automobiles can be considerably reduced in weight compared to conventional copper conductors, and has a creep resistance at a temperature rise equal to or higher than that of conventional copper conductors. Excellent electrical properties. In addition, it has excellent corrosion resistance in electrical equipment used for a long period of time, such as for automobiles, and in places with severe corrosive environments. From these facts, the conductor of the present invention has industrially remarkable effects as a conductor for automobiles.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G301 AA03 AA08 AA09 AA12 AA13 AA14 AA19 AA20 AB11 AB13 AB20 AD01 5G307 BA04 BB03 BC06 BC09

Claims (2)

[Claims] 1. Si 0.3-0.8 wt% (hereinafter simply referred to as%
), 0.35 to 1.0% of Mg, and F
e 0.1-0.6%, Cu 0.02-0.1%, Mn
An Al alloy containing one or more of 0.01 to 0.08%, with the balance being Al and unavoidable impurities, whose tempering is T6 material or T8 material or T5 material, On the surface thereof, a Ni plating film having a thickness of 3 to 10 μm is formed as a first layer, and a second layer having a thickness of 2 to 10 μm is formed thereon.
An Al alloy-made automotive conductor, characterized by having an Sn plating film of m. 2. An Al alloy material having a Ni plating film having a thickness of 3 to 7 μm as a first layer and a Sn plating film having a thickness of 2 to 8 μm as a second layer on a surface of the Al alloy material. 2. The Al alloy-made automotive conductor according to claim 1, wherein