JPH0517885A - Aluminum base metallic material excellent in corrosion resistance - Google Patents

Abstract

PURPOSE:To manufacture an aluminum base metallic material remarkably excellent in corrosion resistance, enduring pitting corrosion and filmform rust in a salt water environment and furthermore good in workability and spot weldability. CONSTITUTION:An aluminum base metallic material in which at least one side of an aluminum material or an aluminum alloy material has an aluminum- manganese alloy film of 0.1 to 50g/m<2> coating weight having 1 to 50wt.% manganese content is prepd. The alloy film may furthermore be incorporated with at least one kind among Cu, Ag, Fe, Co, Ni, Mg, Ca, Sr, Ba, Zn, Cd, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Re. An oxidized film or a chemically converted film may be formed on the alloy film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated aluminum-based metal material suitable for use in automobiles, aircrafts, home appliances, building materials, etc., which has excellent corrosion resistance, workability and weldability.

[0002]

2. Description of the Related Art Aluminum materials and aluminum alloy materials
In the present specification, these are collectively referred to as aluminum-based materials, and since they are light and have excellent corrosion resistance, they have been increasingly used in various applications in recent years.
Taking automobiles as an example, aluminum-based materials are starting to be used to reduce the weight of vehicle bodies as a measure to improve fuel efficiency. Also in the field of building materials, especially in coastal areas exposed to salt water environment.
For conventional (so-called waterfront) structures, aluminum-based materials are used as building materials because conventional zinc-based plated steel materials do not have sufficient corrosion resistance.

However, aluminum-based materials are prone to pitting corrosion and thread rust under salt water environment, and their corrosion resistance in such environment is still insufficient. In snowy areas, snowmelt salts are often sprayed on roads and runways in winter, and in such cases automobiles and aircraft are also exposed to severe corrosive environments. Therefore, an aluminum-based material for an automobile body or an aircraft body is also required to exhibit excellent corrosion resistance to withstand pitting corrosion and thread rust in a salt water environment, like the aluminum-based material for building materials.

When an aluminum-based material is used for automobiles, it is assembled by welding, but there is also a drawback that the weldability of the aluminum-based material, especially the continuous spotting property of spot welding is significantly inferior to that of a zinc-plated steel material. is there. Further, the aluminum-based material is generally poor in workability, and it has been considered difficult to press-form a particularly complicated shape.

It has been proposed in the past to improve the properties of aluminum-based materials by surface treatment. For example, in JP-A-61-157693, Zn, Zn-based alloy or
An aluminum plate having a Fe-based alloy plating layer and excellent in phosphatability, and in JP-A-3-146693, a lower layer
A surface-treated aluminum plate having a Ni plating layer and an upper Zn or Zn-based alloy plating layer, which is excellent in weldability and phosphatability, is described.

However, the properties of aluminum-based materials have not been improved so far by coating the surface of an aluminum-based alloy film. For example, aluminum
The excellent corrosion resistance of manganese alloy plating is known in Japanese Examined Patent Publication (Kokoku) No. 43-18245 and Japanese Patent Laid-Open No. 61-213393, and the alloy plating coating is made of steel, stainless steel, titanium, etc. It has only been applied to non-aluminum based materials.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aluminum-based metallic material which is suitable for automobiles, aircrafts, home electric appliances and building materials, and which solves the above problems. That is, an object of the present invention is to provide an aluminum-based metal material having excellent corrosion resistance, which has sufficient corrosion resistance to withstand pitting corrosion and thread rust in a severe corrosive environment such as salt water environment. Another object of the present invention is to provide an aluminum-based metal material having excellent weldability and workability.

[0008]

Means for Solving the Problems The present inventors have found that when an aluminum-based material (that is, an aluminum material or an aluminum alloy material) is surface-treated with an aluminum-manganese alloy film, pitting corrosion and thread rust are suppressed and corrosion resistance is improved. It is remarkably improved, and by adding a third element to the aluminum-manganese alloy film, the properties such as corrosion resistance, weldability and workability can be further improved, and an oxide film or a chemical conversion treatment is applied on the aluminum-manganese alloy film. It has been found that the corrosion resistance is further enhanced by forming a film.

According to the present invention, the amount of adhesion is 0.1 to 50 g / m on at least one surface of an aluminum material or an aluminum alloy material.
^2. An aluminum-based metal material having excellent corrosion resistance, characterized by having an aluminum-manganese alloy film having a manganese content of 1 to 50% by weight.

This aluminum-manganese alloy coating is
It may further contain at least one additional alloy element selected from the following items, whereby various characteristics such as workability, corrosion resistance, and weldability can be further improved. Cu, Ag, Fe, in a total amount of 0.005-10 atom%,
At least one metal selected from Co and Ni, and Mg, Ca, Sr, Ba, Zn, Cd, I in a total amount of 0.002 to 3 atomic%
at least one metal selected from n, Tl, Si, Ge, Sn, Pb, As, Sb and Bi, and Ti, Zr, Hf, V, Nb, Ta in a total amount of 0.005 to 5 atomic%, Cr, Mo, W and Re
At least one metal selected from.

When two or more additional alloying elements are added,
Even if these are selected from the metals belonging to the same number of ~,
Alternatively, it may be selected from metals belonging to different numbers.

Further, the surface-treated aluminum-based metal material of the present invention may further have an oxide film or a chemical conversion treatment film on the aluminum-manganese alloy film, which further improves the corrosion resistance.

[0013]

The structure of the present invention will be described in detail below together with its operation. In the present invention, the base aluminum material or aluminum alloy material (that is, aluminum base material) may be any shape such as a plate material, a panel material, a bar material, a pipe material, a wire material, or various molded or cast materials. . When the base material is an aluminum alloy, its composition is not particularly limited. Examples of aluminum alloys suitable for the base material include Al
-Cu, Al-Mn, Al-Mg, Al-Mg-Si, Al-Zn, Al-Cu-
Mg-Mn, etc. Specifically, JIS 5000 series, 6000 series Al-Mg alloys, which are often used recently as a weight-saving measure for improving automobile fuel economy, and JI, which is often used for building materials, are used.
Al-Mn alloys in the S 3000 series, as well as aluminum alloy castings, die castings, JIS 7000 series used in aircraft, duralumin, etc. can be used as the base aluminum alloy.

In the aluminum-based metal material of the present invention, at least one surface of the aluminum-based base material is coated with a film of an aluminum-manganese alloy. This alloy film is formed by electroplating, thermal spraying, molten metal quenching, CVD
Method, a PVD method, an ion plating method, an ion sputtering method, or any other suitable method can be easily formed on the surface of the base material. The electroplating method can be easily carried out using a molten salt bath.

In order to enhance the adhesion between the aluminum-manganese alloy coating and the aluminum-based base material, good adhesion is exhibited on both the base material and the aluminum-manganese alloy coating.
The base material may be pretreated so that a base layer of a metal such as Zn or Ni is formed on the surface of the base material in advance. Such an underlayer is
For example, it can be formed by a conventional zincate treatment, Ni plating treatment, or anodic dissolution treatment.

The aluminum-manganese alloy coating for coating the base material may be an Al-Mn binary alloy or a ternary or higher Al-Mn-X alloy containing at least one additional element X. In either case, the Mn content of the alloy is in the range of 1-50% by weight.

When the aluminum base material having the aluminum-manganese alloy film is exposed to a corrosive environment, Mn in the alloy film is preferentially dissolved, and the corrosion product of Al ₂ O ₃ covers the surface of the material. To prevent corrosion, the corrosion resistance is significantly improved compared to the aluminum base material as it is.

In particular, in a ternary or more aluminum-manganese alloy coating in which at least one additional element X is added to Al and Mn, various characteristics are further improved depending on the type of the additional element. For example, at least one of Cu, Ag, Fe, Co and Ni
When seeds are added to the above alloy coating, the coating becomes hard, slidability is improved, and workability is further improved.

Mg, Ca, Sr, Ba, Zn, Cd, In, Tl, Si, G
When at least one of e, Sn, Pb, As, Sb and Bi is added to the alloy film, the film becomes more base in terms of potential and the ionization tendency is increased, so that the sacrificial anticorrosive ability of the film is increased.
Therefore, even if the film is scratched and the base material is exposed,
The pitting corrosion of the base material can be protected and the pitting corrosion resistance is further improved.

Although the reason is not clear, with aluminum alone, the electrode is greatly worn during spot welding,
The nugget shape becomes bad. However, if a coating film of manganese added to aluminum is provided, the continuous spotting property during spot welding is improved. In addition to aluminum and manganese, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo,
When at least one metal of W and Re is added, the melting point of the coating rises, the continuous spotting property is markedly improved, and the current during welding is also small, which brings about an economic advantage.

The effect of improving the corrosion resistance of the aluminum base material by the aluminum-manganese alloy film cannot be obtained unless the adhered amount and manganese content are appropriate. Therefore, the adhesion amount is 0.1 to 50 g / m ² , and the manganese content is 1
Within 50% by weight. When the adhesion amount is less than 0.1 g / m ² , the corrosion resistance of the aluminum-manganese alloy coating is poor,
If it exceeds 50 g / m ² , not only the alloy film becomes too thick and the workability deteriorates, but also the corrosion resistance decreases. If the manganese content is less than 1% by weight, the corrosion resistance is poor and 50% by weight
If it exceeds, workability deteriorates.

The preferred coverage is 2 to 30 g / m ² . Compared with the adhesion amount of less than ² g / m ² , it can withstand more severe corrosive environment, and further improves weldability and workability compared with more than 30 g / m ² . The preferred manganese content is 15-35% by weight
Is. Compared to less than 15% by weight or more than 35% by weight, workability and film appearance are improved.

A more preferable adhesion amount is 5 to 20 g / m ² . Compared with an adhesion amount of less than 5 g / m ² , it can withstand a more severe corrosive environment, and even if the film is scratched, it becomes difficult to reach the base material and the base material can be protected more effectively. In addition, compared to more than 20 g / m ² , weldability and workability are remarkably improved, and the adhesion amount is small, making it more economical. A more preferable manganese content is 25 to 35% by weight. Less than 25% or 35% by weight
Compared to the super type, the processability is further improved, the appearance of the film is silver white with gloss, and the designability is improved.

The aluminum-manganese alloy coating includes Al, Mn, Cu, Ag, Fe, Co, Ni, Mg, Ca, Sr, Ba,
Zn, Cd, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi, Ti, Z
It may further contain at least one alloy element selected from the group consisting of r, Hf, V, Nb, Ta, Cr, Mo, W and Re. From the viewpoint of easy control of the alloy composition, a ternary alloy with one additional element is preferable, but it is possible to add two or more additional elements.

When the additional alloying element is at least one metal selected from Cu, Ag, Fe, Co and Ni, the total content of these elements is 0.005 to 10 atomic% (at%), more preferably The range of 0.5 to 7 atomic% is preferable. 0.005 atom%
If it is less than the above, the hardness of the coating is not so different from that of the Al-Mn binary alloy, and the workability is not improved so much. If it exceeds 10 atomic%, the corrosion resistance becomes poor.

The additional alloy elements are Mg, Ca, Sr, Ba, Zn and C.
When it is at least one metal selected from d, In, Tl, Si, Ge, Sn, Pb, As, Sb and Bi, the total content of these elements is 0.002 to 3 atom%, more preferably 0.1 to 3 atom%. ~
The range of 2 atomic% is preferable. If it is less than 0.002 atomic%, the potential of the coating is not so different from that of the Al-Mn binary alloy, and it is difficult to further improve the effect of preventing pitting corrosion of the base material. If it exceeds 3 atomic%, the corrosion resistance becomes poor.

Additional alloying elements are Ti, Zr, Hf, V, Nb, Ta,
When it is at least one metal selected from Cr, Mo, W and Re, the total content of these elements is preferably 0.005 to 5 atom%, more preferably 0.5 to 3 atom%.
If it is less than 0.005 atomic%, the melting point of the coating is almost the same as that of the Al-Mn binary alloy, and no further improvement in weldability is observed. If it exceeds 5 atomic%, the corrosion resistance deteriorates.

The aluminum-based metal material having the aluminum-manganese alloy coating on the aluminum-based base material of the present invention is excellent in corrosion resistance as shown in the examples described later, but on the aluminum-manganese alloy coating, Further, when an oxide film is formed or a chemical conversion treatment film is formed by a chromate treatment or a zinc phosphate treatment, the corrosion resistance is further improved.

It is considered that the oxide film covers the alloy film as a barrier layer to make it difficult for the corrosion current to flow, and the corrosion product of Al improves the corrosion resistance. The oxide film is
For example, it can be formed by electrolytic oxidation, dipping treatment, etc., and the adhesion amount is preferably within a range of 0.1 to 1 μm as a film thickness. If it is less than 0.01 μm, the insulation of the film is poor and the corrosion resistance is not so improved. If the film thickness exceeds 1 μm, the weldability deteriorates.

It is considered that the chemical conversion treatment film contributes to the improvement of corrosion resistance due to corrosion products such as Al, Cr and Zn.
For that purpose, the amount of adhesion is 5 to 20 in the case of chromate treatment.
0 mg / m ² (Cr equivalent), when treated with zinc phosphate
It is preferably 0.1 to 5 g / m ² . If the amount of adhesion is less than this range, the corrosion resistance will not be improved so much, and if it is more than this range, the corrosion resistance after coating will be poor. The chemical conversion coating is
It can be formed by any conventional chromate treatment method or zinc phosphate treatment method.

[0031]

Example An aluminum-manganese alloy film was formed on both surfaces of a pure aluminum plate and an aluminum alloy plate having a plate thickness of 1 mm by molten salt electrolytic plating under the following conditions. After that, as a post-treatment, some of the plated materials were subjected to electrolytic oxidation treatment or chemical conversion treatment (chromate treatment or zinc phosphate treatment) under the following conditions to form an oxide film or chemical conversion treatment film on the plating film.

[Aluminum-manganese alloy molten salt electroplating conditions] Basic bath composition: AlCl ₃ 62 mol%, NaCl 20 mol%, KCl
18 mol% mixed molten salt, bath temperature: 200 ° C, additive: MnCl ₂ (50 to 6000 ppm), chloride of other additive elements (50 to 6000 ppm) as required (concentrations are all ionic concentration in bath) ), Current density: 60 A / dm ² .

[Electrolytic oxidation treatment conditions] Treatment liquid: 10% boric acid aqueous solution, Liquid temperature: 20 ℃, Bath voltage: AC 60 V, Processing time: 1 minute, Film thickness: about 1 μm.

[Chromate treatment conditions] Cr ₂ O ₃ : 3.5 to 4.0 g / l, Na ₂ Cr ₃ O ₇ : 3.0 to 3.5 g / l, NaF: 0.8 g / l, pH: 1.5, treatment temperature: 30 ° C. , Treatment time: 3 minutes (immersion), Adhesion amount: 10 to 30 mg / m ² (Cr equivalent).

[Zinc Phosphate Treatment Condition] Treatment liquid: PBL 3020 made by Nippon Parker + fluoride ion addition, treatment temperature: 45 ° C., treatment time: 2 minutes (immersion), adhesion amount: 1-3 g / m ² .

Tables 1 to 8 collectively show the composition of the base material, the amount of the aluminum-manganese alloy coating deposited, its basic Al-Mn alloy composition and the content of additional alloying elements, and the types of post-treatments. Test pieces were cut out from the aluminum-based metal material thus obtained, and corrosion resistance, forming workability, and spot weldability were examined by the following procedures by a corrosion test, an impact test, a press forming test, and a spot welding test. The test results are also shown in Tables 1 to 8.

[Test method] Corrosion resistance: 2000 salt spray test (according to JIS Z2371)
It was carried out for a time, the corrosion weight loss was measured, and the corrosion resistance was evaluated on the basis of the corrosion weight loss rate in the following five stages. 5: Corrosion weight loss rate is 0.1 mg / m ² -hr or less, 4: Corrosion weight loss rate is more than 0.1 mg / m ² -hr, 1 mg / m ² -hr or less, 3: Corrosion weight loss rate is 1 mg / m ² -hr More than 5 mg / m ² -hr or less, 2: Corrosion weight loss rate is more than 5 mg / m ² -hr, 10 mg / m ² -hr or less, 1: Corrosion weight loss rate is more than 10 mg / m ² -hr.

Pitting corrosion resistance: The aluminum-manganese alloy film was removed from the test piece after the salt spray test described above, and the pitting corrosion state of the exposed base material surface was visually observed to determine the pitting corrosion resistance of the base material. It was evaluated in four stages. ⊚: No pitting corrosion, ◯: Small pitting corrosion is slightly observed, Δ: Pitting corrosion is present, ×: Many pitting corrosions are present.

Spot weldability: Two test pieces made of the same surface-treated aluminum-based metal material were welded with a single spot welder equipped with a Cu-Cr electrode and a welding current: 90.
Continuous spot welding was performed under the conditions of 00A, energization time: 12 cycles, pressure: 1960N, and welding speed: 1 spot / sec. The spot weldability was evaluated according to the following 5 grades by the number of continuous dots until the nugget shape was deformed by the consumption of the electrode. 5: 5,000 points or more, 4: 5,000 points
Less than points, 3500 points or more, 3: RBI points less than 3500 points, 2000 points or more, 3: RBI points 2000
Less than 500 points, 500 points or more, 1: Less than 500 points.

Molding processability (1): DuPont impact test (ball head diameter 1/2 inch, energy 0.8 kgf-m) was conducted, and the adhesive tape peeling test of the test piece after impact revealed that the peeled piece adhered to the tape. Check the adhesion of the alloy film from the situation and
Molding workability was evaluated according to the criteria of stages. ⊚: No peeling, ◯: There is powder-like minute peeling, but there is no practical problem, Δ: Small peeling, ×: Large peeling.

Molding Workability (2) A test piece was press-molded in a hat shape by a press molding machine with beads shown in FIG. 1 to examine the molding workability. The test piece 6 was placed on a plate holding holder 10 with a bead 9, held by a die 11 and press-molded by a punch 12 into a hat (height 55 mm). The flaking resistance of the alloy film was examined from the state of the peeled pieces adhered to the tape by the adhesive tape peeling test on the surface of the press-molded test piece on the holder side, and the molding processability was evaluated according to the following four-stage criteria. ⊚: No peeling piece, ◯: Very small amount of peeling piece, Δ: There is peeling piece, ×: There is a large amount of peeling piece.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Table 5]

[0047]

[Table 6]

[0048]

[Table 7]

[0049]

[Table 8]

As is clear from the test results shown in the above table, the aluminum-based metal material of the present invention on which the aluminum-manganese alloy film is formed has a small amount of corrosion loss and excellent corrosion resistance. The moldability is also good. Those with an oxide film or chemical conversion film (chromate film or zinc phosphate film) further formed,
The corrosion weight loss is particularly small and the corrosion resistance is further improved. In addition, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W in the alloy film
Those containing Re or Re were particularly excellent in spot weldability.

On the other hand, an aluminum-based metal material having an aluminum-manganese alloy coating film as a comparative example whose alloy composition or deposition amount is outside the scope of the present invention has at least one of corrosion resistance, spot weldability and formability. Inferior in characteristics. Incidentally, when the aluminum base material is used as it is without being provided with an alloy coating, and a salt spray test similar to the above is carried out, the corrosion weight loss is remarkably large in both the pure aluminum plate and the aluminum alloy plate. Eating occurred.

[0052]

EFFECTS OF THE INVENTION The aluminum-based metal material having the aluminum-manganese alloy coating formed on the aluminum-based material of the present invention is said to be in a salt water environment even though the base material and the coating are aluminum-based materials of the same kind. It is possible to remarkably enhance the corrosion resistance of the aluminum-based material under a severe harsh corrosive environment. In addition, workability and weldability are also good. Therefore, cars that may be used in salt water environments,
It is extremely suitable for applications such as aircraft and building materials.

[Brief description of drawings]

FIG. 1 is an explanatory view of a press molding tester used for evaluation of molding workability in Examples.

[Explanation of symbols]

6 test pieces, 9 beads, 10 holders, 11 dies, 12 punches

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirohisa Seto             Sumitomo Kin 4-3-33 Kitahama, Chuo-ku, Osaka             Inside the industry

Claims (5)

[Claims] 1. Corrosion resistance, characterized by having an aluminum-manganese alloy film having an adhesion amount of 0.1 to 50 g / m ² and a manganese content of 1 to 50% by weight on at least one surface of an aluminum material or an aluminum alloy material. Excellent aluminum-based metal material. 2. The aluminum-manganese alloy coating further contains at least one metal selected from Cu, Ag, Fe, Co and Ni in an amount such that the total content is 0.005 to 10 atomic%. The aluminum-based metal material according to claim 1. 3. The aluminum-manganese alloy coating further comprises Mg, Ca, Sr, Ba, Zn, Cd, In, Tl, Si, Ge,
The aluminum-based metal material according to claim 1 or 2, which contains at least one metal selected from Sn, Pb, As, Sb and Bi in an amount such that the total content thereof is 0.002 to 3 atom%. 4. The aluminum-manganese alloy coating further comprises Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and
The aluminum-based metal material according to any one of claims 1 to 3, which contains at least one metal selected from Re in an amount such that the total content thereof is 0.005 to 5 atom%. 5. The aluminum-based metal material according to claim 1, further comprising an oxide film or a chemical conversion film on the aluminum-manganese alloy film.