JP2002363676A - Aluminum alloy conductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight, inexpensive Al alloy conductor which has required strength and electrical conductivity, has good creep resistance and excellent electrical connecting characteristics and also has excellent corrosion resistance. SOLUTION: This aluminum alloy conductor is obtained by providing an Al alloy treated material obtained by subjecting an Al alloy material having a composition containing, by mass, 0.3 to 0.8% Si and 0.35 to 1.0% Mg, and further containing one or more kinds selected from 0.1 to 0.6% Fe, 0.02 to 0.1% Cu and 0.01 to 0.08% Mn, and the balance Al with inevitable impurities to T6, T8 or T5 tratment with an Ni-P alloy plating film having a thickness of 0.1 to 3 μm, or an Ni-B alloy plating film having a thickness of 0.3 to 3 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor for automobiles, and more particularly to an aluminum alloy conductor for high-current application suitable for conductors for electric vehicles including hybrid cars.

[0002]

2. Description of the Related Art Conventionally, in an electric vehicle, electric connection between a group of batteries and electric equipment (an inverter, a motor, etc.), electric connection between each battery, circuits in the inverter, etc. are made of pure copper suitable for large current application. (A conductor having a rectangular shape, a plate shape, or the like, and hereinafter referred to as a conductor) is used, and the conductor is connected to the electric device or the like by bolting. However, in recent years, there has been a strong demand for reducing the weight of automobiles for the purpose of reducing fuel consumption, and there has been an active movement to replace the copper conductor with lightweight aluminum (hereinafter appropriately referred to as Al) or Al alloy.

When the copper conductor is replaced with an Al or Al alloy conductor (hereinafter, appropriately referred to as an Al conductor),
The specific gravity of copper is 8.89 and the specific gravity of Al is 2.70.
Since the electrical conductivity of 0) is 61% IACS, when the electrical resistance is the same, the cross section of the Al conductor increases to 160% of the copper conductor, but the weight decreases to 50%. When the current is the same, the cross section of the Al conductor increases to 125% of that of the copper conductor, but the weight decreases to 40%. From these facts, if the electrical use conditions are the same, A
The 1 conductor will weigh less than half the copper conductor.

Incidentally, Al conductors such as power distribution facilities on the ground include 1060 (pure Al of 99.60% or more 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) or an Al alloy is used (JIS H 4180). The Al
Table 1 shows the component (composition) and conductivity of the Al alloy.
Table 2 shows the mechanical properties of the 1060, 6101 and copper at room temperature.

[0005]

[Table 1]

[0006]

[Table 2]

As can be seen from Tables 1 and 2, pure Al
No. 1060 hardwood has high conductivity but low strength. Al-S
The 6101-T6 treated material of the i-Mg alloy has the same strength as the semi-hard material (1 / 2H) of copper, has a conductivity of 55% IACS or more, and is the highest among Al alloys. Therefore, it is considered that a material equivalent to the 6101 alloy is optimal as the Al conductor instead of the copper conductor. However, the following problems need to be cleared in order to use the conductor for electric vehicles.

That is, since a heat cycle of an automotive conductor is repeated for a long period of time with a temperature rise (around 100 ° C.) during use, the Al conductor has (1) excellent creep resistance and bolts during use. It is required that good electrical connection characteristics can be stably obtained without loosening of the fastening portion, and (2) excellent corrosion resistance especially at the connection portion.

[0009] By the way, in the distribution equipment on the ground, the Al conductor is usually used without any surface treatment, but the electric equipment which has a severe corrosive environment and requires corrosion resistance is made of Cu and Ag.
It may be used after being subjected to layer plating or Sn-Zn alloy solder (friction solder) plating. For this reason, the present inventors
We have proposed an Al alloy conductor for automobiles in which Ni and Sn are plated in two layers on the surface of the Al alloy, the heat resistance is improved by Ni plating, and the electrical connectivity is improved by forming a two-layer plating (Japanese Patent Application No. Hei 10-26370). 11-9136). However, two-layer plating is costly and requires a lot of work for plating.
The plating layer is preferably a single layer, in which case Ni plating with good corrosion resistance is recommended. However, the conventional Ni plating has a problem in that when it is strongly tightened with a bolt, the plating film is peeled off, and the corrosion resistance and oxidation resistance of that portion are reduced, and the electrical connection characteristics required for the conductor cannot be obtained.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an aluminum alloy which is lightweight, has the required strength and conductivity, has good creep resistance, has excellent electrical connection characteristics, has excellent corrosion resistance, and is inexpensive. It is to provide a conductor.

[0011]

According to the first aspect of the present invention,
Si 0.3 to 0.8 mass% (hereinafter abbreviated as% as appropriate),
Contains 0.35 to 1.0% of Mg, and further contains 0.1 to 0.1% of Fe
0.6%, Cu 0.02-0.1%, Mn 0.01-
An Al alloy material containing one or more of 0.08% and the balance consisting of Al and inevitable impurities is T6, T
8 or T5 treated Al alloy treated material with a thickness of 0.1
~ 3μm Ni-P alloy plating film or thickness 0.3 ~
An aluminum alloy conductor provided with a 3 μm Ni—B alloy plating film.

According to a second aspect of the present invention, there is provided the aluminum alloy conductor according to the first aspect, wherein the Ni-P alloy plating film or the Ni-B alloy plating film has a Vickers hardness of 500 to 1200 Hv. is there.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The structure, operation, effects and embodiments of the present invention will be described in detail below. The Al alloy used in the present invention has Si and Mg as main alloy elements. These elements are dissolved in Al matrix or Mg ₂
It precipitates finely as Si particles to increase the strength and prevent deformation of the conductor. Even if any of Si or Mg is less than the lower limit of the specified value of the present invention, the amount of solid solution or the amount of Mg ₂ Si particles is reduced and sufficient strength cannot be obtained. The amount of solid solution increases and the electrical conductivity decreases, and the Mg ₂ Si particles become coarse and the formability decreases.

The subcomponents Fe, Mn and Cu enhance the strength and creep resistance of the conductor. Of these, Fe, Mn
Forms an intermetallic compound with Al and improves strength by dispersion strengthening. Further, the intermetallic compound is finely precipitated to stabilize the sub-crystal grain structure and the recrystallized grain structure, and prevents the recovery of the strain generated in the structure due to the heat generated during energization, thereby improving the creep resistance. Cu forms a solid solution to improve the strength and creep resistance of the conductor. If any of the subcomponents is less than the lower limit of the present invention, the effect cannot be sufficiently obtained, and if it exceeds the upper limit, the moldability decreases.

After the Al alloy used in the present invention is processed into a conductor shape, any one of T6, T8 and T5 is applied to adjust the strength and creep resistance. The mechanical properties at room temperature of the Al alloy treated material after the T6, T8 or T5 treatment are as shown in Table 3.

[0016]

[Table 3]

The Al alloy-treated material has a Ni—
By providing a P alloy plating film or a Ni-B alloy plating film, corrosion resistance and electric characteristics (electrical contact resistance of the connection portion) are improved. In the present invention, the thickness of the Ni—P alloy plating film is set to 0.1 to 3 μm, and the thickness of the Ni—B alloy plating film is set to 0.3 to 3 μm. This is because the effect cannot be sufficiently obtained, and if it exceeds the upper limit (3 μm), the plating film is easily peeled off and the plating cost becomes high. The thickness of the film is more preferably from 1 to 3 μm in view of characteristics and cost.

The Ni-P alloy plating film or Ni-
The Vickers hardness (hereinafter abbreviated as hardness) of the B alloy plating film is preferably from 500 to 1200 Hv. The hardness is 5
If it is lower than 00Hv, the surface is damaged when the conductor is electrically connected and the like, resulting in poor appearance and deterioration of the electrical connection characteristics,
Further, corrosion progresses from the wound. On the other hand, hardness is 12
If it is higher than 00 Hv, cracks occur at the time of bolt tightening, and the corrosion resistance and the electrical connection characteristics decrease. The hardness is controlled mainly by the alloy element concentration, the pH of the plating bath,
Fine adjustment is made according to the current density and the amount of sulfamic acid added. For both Ni-P alloy plating and Ni-B alloy plating, an alloy concentration of 3 to 8 mass% is appropriate.

The Al alloy conductor of the present invention can be formed by cutting, punching, or bending an Al rolled material or an Al extruded material into a flat rectangular material (for example, 2 × 20 × 200 mm) or a plate material (for example, 2 × 200 × 200 mm). ), A bolt hole is formed in the rectangular material or the plate material, and then Ni-P alloy plating or Ni-B alloy plating is performed.

The case where the Al alloy conductor of the present invention is manufactured by hot rolling and the case where it is manufactured by hot extrusion will be specifically described below. In the case of manufacturing by hot rolling, the Al alloy of the component specified in the present invention is formed into an ingot by a normal method such as a semi-continuous casting method, and the ingot is formed into a 500 to 54
After homogenization (soaking) at a temperature of 0 ° C., hot rolling and cold rolling are performed in this order to obtain a predetermined thickness. After maintaining at a temperature of 500 ° C. or more before, during or after this cold rolling, a solution treatment for cooling (cooling at a cooling rate of 1 ° C./sec or more up to 200 ° C.) is performed. Cold rolling is performed, and finally, an age hardening treatment is performed at a temperature of 150 to 250 ° C. The T8 treatment is to perform the solution treatment before or during the cold rolling, and the T6 treatment is to perform the solution treatment after the cold rolling.

The ingot is homogenized at 500 to 540 ° C.
The temperature is adjusted to increase the amount of solid solution of alloying elements.
If the temperature is lower than 500 ° C., the alloy element does not form a solid solution, and the
This is because if it exceeds 300 mm, the ingot may be partially melted.

The solution treatment is carried out at a temperature of 500 ° C. or more and then cooling (cooling at a cooling rate of 200 ° C. or 1 ° C./sec or more). This is because the alloying element does not sufficiently form a solid solution even at less than 1 ° C./sec.

The above-mentioned aging treatment is carried out by using Mg, S
i, Cu element is deposited in order to further enhance the strength of the conductor by precipitating it as Mg ₂ Si or a Cu compound. The reason for setting the treatment temperature to 150 to 250 ° C. is that if the temperature is lower than 150 ° C., the amount of precipitation is insufficient, and if the temperature exceeds 250 ° C., the precipitates are coarsened, and any of them cannot obtain sufficient strength.

When the Al alloy conductor of the present invention is manufactured by hot extrusion, the ingot obtained in the same manner as in the hot rolling is homogenized at a temperature of 500 to 540 ° C.
Hot extrusion followed by cold drawing. After holding at a temperature of 500 ° C. or more before or after or during the cold drawing, cooling (20
(Cooling at a cooling rate of 1 ° C./sec or more to 0 ° C.), followed by predetermined cold drawing if necessary, and finally, age hardening at 150 to 250 ° C. .

The T8 treatment is to perform the solution treatment before or during the cold drawing, and the T6 treatment is to perform the solution treatment after the cold drawing. T5 treatment is to harden the material produced during hot extrusion as it is and then to perform age hardening treatment. In the T5 treatment, the solution treatment can be omitted.

The above homogenization treatment, solution treatment (quenching),
The conditions of the age hardening treatment are set for the same reason as in the case of hot rolling.

[0027]

The present invention will be described below in detail with reference to examples. (Example 1) An Al alloy (N
o. 1, 3, 4) is melt-cast and the obtained ingot is 540
After hot-rolled at 540 ° C., then cold-rolled to a thickness of 5 mm, and the cold-rolled material was subjected to solution treatment at 540 ° C.
It is cooled at a cooling rate of 20 ° C./sec to 00 ° C., and then subjected to an age hardening treatment at 200 ° C. for 2 hours (T6 treatment).
An alloy treated material was manufactured.

(Example 2) An aluminum alloy (No. 2) having the composition specified in the present invention shown in Table 4 was melt-cast, and 5
After homogenization at 40 ° C, hot rolling, then 7mm thick
After cold-rolled, the cold-rolled material is solution-treated at 540 ° C., cold-rolled again to a thickness of 5 mm, and the cold-rolled material is subjected to age hardening at 200 ° C. for 2 hours ( T8 processing)
An Al alloy treated material was manufactured.

Comparative Example 1 Example 1 was repeated except that an Al alloy (Nos. 5 to 12) not shown in Table 4 was used.
An Al alloy treated material was manufactured in the same manner as in the above.

With respect to each of the Al alloy-treated materials produced in Examples 1 and 2 and Comparative Example 1, the electrical conductivity at room temperature and the creep resistance (the creep resistance of the bolted connection in a high temperature state) were measured. The creep resistance characteristics were determined by applying a constant pressure load (1.2 ton / cm ² ) to the surface of a sheet material sample (5 mm × 20 mm × 20 mm), maintaining at 120 ° C. for 3 hours in this state, and cooling to room temperature to obtain a sheet thickness t. Was measured, and a thickness reduction ratio (([Tt] / T) × 100%) with respect to the original thickness (5 mm) T was obtained and evaluated.
For reference, conventional copper plate material (semi-hard) and pure Al
The plate (1060 semi-hard) was also tested in the same manner to evaluate the conductivity and the creep resistance. The results are shown in Table 4.

[0031]

[Table 4]

As is clear from Table 4, the aluminum alloy treated materials (Nos. 1 to 4) of the present invention all have a conductivity of 55% I.
ACS or higher, and exhibited excellent creep resistance equivalent to that of a conventional pure copper material. On the other hand, (No.
12) had an electrical conductivity of less than 55% IACS or was inferior in creep resistance.

(Embodiment 3) 1
(See Table 4) Al alloy treated material (5 × 30 × 100 m)
m), after drilling an 8mm diameter bolt hole,
An Al alloy conductor was manufactured by plating Ni-P alloys or Ni-B alloys of various compositions. The plating film thickness was variously changed within the specified value of the present invention.

Comparative Example 2 An Al alloy conductor was manufactured in the same manner as in Example 3, except that the plating thickness was more than 3 μm.

(Comparative Example 3) Ni-P alloy plating or N
An Al alloy conductor was manufactured in the same manner as in Example 3, except that two layers of Ni and Sn were used instead of the iB alloy plating.

The Al alloy conductors produced in Example 3 and Comparative Examples 2 and 3 were examined for creep resistance and corrosion resistance. The processing costs were compared. For comparison, a similar test was performed on a conventional Al alloy conductor plated with two layers of Cu and Ag or subjected to friction solder plating, and evaluated.

The creep resistance characteristics were determined by cutting each of the Al alloy conductors to a predetermined size to obtain a test material, and laminating two test materials each (a length of a joining portion of 10 mm). With a flanged bolt / nut at a constant pressure load of 1.2 ton / cm ² (bolt tightening torque: 1.2 kg · m).
And a heat cycle test for 240 hours (10 cycles, 10 days), in which each cycle is a step of holding at room temperature for 12 hours.
And the electrical contact resistance before and after the test was measured and evaluated.
The flanged bolt / nut used was a Cr-plated stainless steel having a flange diameter of 12 mm and a bolt diameter of 6 mm.

The corrosion resistance was evaluated by subjecting the tightened body used in the heat cycle test to a salt spray test for 96 hours (4 days), and examining the corrosion state of the bolted portion of the bonded material after the test and other portions (other portions). Observed and evaluated. Table 5 shows the results.

[0039]

[Table 5]

As is apparent from Table 5, the N of the present invention example
o. All of Nos. 15 to 22 were excellent in creep resistance and corrosion resistance, and the processing cost was low. In particular, no. 16
Nos. 21 to 21 showed that the hardness of the plating film was appropriate and the contact resistance was more stable and lower. On the other hand, in Comparative Example No.
In Nos. 23 and 24, since the Ni plating layer was thick, the Ni plating layer was cracked at the time of bolt tightening, resulting in poor corrosion resistance. N
o. 25 is a two-layer plating, which requires time-consuming surface treatment.
The cost was high. In addition, the conventional two-layer plating material of Cu and Ag (No. 26) and the friction solder material (No. 27) all have high processing costs, and the latter has poor corrosion resistance. As described above, the conductor of the present invention has a stable and low contact resistance, is excellent in corrosion resistance, and has a low processing cost. Therefore, the overall evaluation as a product is very good or good.

[0041]

As described above, the Al alloy conductor of the present invention is lighter than conventional copper conductors, has the required strength and conductivity, has good creep resistance, and has good electrical properties. Excellent connection characteristics, excellent corrosion resistance, and low plating cost. Therefore, an industrially significant effect is achieved.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) // B21B 3/00 B21B 3/00 J

Claims (2)

[Claims] 1. Si 0.3 to 0.8 mass% (hereinafter referred to as%
Abbreviated as Mg), Mg 0.35 to 1.0%, Fe 0.1 to 0.6%, Cu 0.02 to 0.1%, M
n of an Al alloy material containing one or more of 0.01 to 0.08% and the balance consisting of Al and unavoidable impurities is subjected to T6, T8, or T5 treatment, and the thickness of the Al alloy material is set to 0.1 mm. An aluminum alloy conductor provided with a Ni-P alloy plating film having a thickness of 1 to 3 m or a Ni-B alloy plating film having a thickness of 0.3 to 3 m. 2. The Ni-P alloy plating film or Ni
Vickers hardness of -B alloy plating film is 500 to 120
2. The aluminum alloy conductor according to claim 1, wherein the aluminum alloy conductor is 0 Hv.