JPH0770760A - Al alloy plate with excellent press formability and corrosion resistance - Google Patents

Abstract

(57) [Summary] [Purpose] The present invention is intended to provide excellent corrosion resistance and press formability.
l alloy plate is provided. [Structure] A chromate film containing 0.2 to 10 wt% of MoS ₂ having an average particle size of 2 μm or less is directly attached to one or both surfaces of an Al alloy plate in the range of 30 to 100 mg / m ^{2 in} terms of Cr, or Alternatively, as the lower layer, Zn or Zn containing Zn as a main component and 1 to 30 wt% of one or more alloy elements of Fe, Ni, and Cr is contained.
The MoS ₂ -containing chromate film is deposited on the Al-based alloy plating through the deposition amount of 1 to 60 g / m ² to improve the formability and corrosion resistance of the Al alloy sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al alloy plate having a chromate film and having excellent press formability and corrosion resistance.

[0002]

2. Description of the Related Art In recent years, in order to cope with global environmental problems such as global warming and acid rain, improvement of fuel efficiency of automobiles and regulation of exhaust gas have been studied. The most effective way to improve fuel efficiency and reduce exhaust gas of automobiles is to reduce the weight of automobile bodies. As a material for this, the amount of lighter Al alloy sheets used instead of the various types of steel sheets that have been conventionally used. It tends to increase. Al alloy sheets used for automobile bodies have not only corrosion resistance in consideration of the operating environment of automobiles, but also high-speed and impact bending, shearing, punching, etc. during the manufacturing process, which results in good press formability. Is required to have. As a method of improving the press formability of the Al alloy plate, a method of making the material of the Al alloy plate suitable for press forming, and a method of applying plating to the surface used in the field of steel sheet are generally used. Is.

As an example in which the material of the Al alloy plate is changed to one suitable for press molding, there is JP-A-5-33107. This is Mn: 1.0 to 1.5 wt%, Mg:
1.0 to 1.5 wt%, Cu: 0.10 to 0.30 wt
%, Si: 0.15 to 0.30 wt%, Fe: 0.25
~ 0.55 wt%, Ti: 0.01-0.04 wt%,
B: 0.0001 to 0.0010 wt% and balance A
It is an Al alloy plate composed of 1 and unavoidable impurities. Although it is possible to improve formability by this method, the composition of the alloy is limited, so it can be applied to can materials but is applied to Al alloy plates that are generally used for automobiles. Is difficult.

As an example of plating the surface of an Al alloy plate, Japanese Patent Laid-Open No. 25656/1993 and Japanese Patent Laid-Open No. 2566-256 are known.
57 and JP-A-5-25658. Each of these attempts to improve the press formability by applying Fe-based hard plating to the surface of the Al alloy plate.
However, since the Al alloy plate is a material which is inferior in formability as compared with the steel plate, sufficient press formability cannot be obtained only by applying Fe-based plating, and further measures for improving formability are needed. ing. Further, thickly depositing Fe-based plating has a problem in terms of corrosion resistance. As described above, there is no current Al alloy sheet having sufficient corrosion resistance and press formability for automobiles.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides an Al alloy plate with the ability to withstand press working such as high-speed and impact bending, shearing, punching and the like, and the corrosion resistance capable of withstanding the use environment of automobiles. It is an object of the present invention to provide an Al alloy plate having sufficient press formability and corrosion resistance for automobiles.

[0006]

In order to solve the above problems, the present inventors have studied in detail the effects of various lubricants, chromate films, and plating on the corrosion resistance and press formability of Al alloy sheets. As a result, they have found that the press formability and corrosion resistance are improved by applying a chromate film containing MoS ₂ directly on the surface of the Al alloy plate or on the lower layer plating, and completed the present invention.

The gist of the present invention is that 0.2 to 10 MoS ₂ having an average particle size of 2 μm or less is provided on one side or both sides of an Al alloy plate.
Chromate film containing wt% is 30 to 10 in terms of Cr
In order to make it adhere in the range of 0 mg / m ² or to further improve the corrosion resistance, Zn alone or Z as the lower layer is used.
Zn containing n as a main component and 1 to 30 wt% of one or more alloy elements selected from Fe, Ni and Cr
Through the system alloy plating within the range of coating weight ^{1~60g / m 2, 30~100mg / m} 2 of chromate film containing 0.2-10% of MoS ₂ below the average particle diameter of 2μm as an upper layer of Cr terms It is an Al alloy plate having excellent corrosion resistance and press formability in the range.

The present invention will be described in detail below. In the present invention, a chromate film containing MoS ₂ is applied for the purpose of improving the corrosion resistance and press formability of the Al alloy plate. MoS ₂ added to the chromate film is an inorganic compound mainly used as a solid lubricant, has a hexagonal crystal structure, and a plane hexagonal layer of Mo atoms is between two layers of sulfur atoms. It has a layered structure sandwiched between. Since the bonding force between the sulfur atoms in this structure is very weak, it is said that even a slight force causes a slip between the layers, resulting in low friction resistance.

The present inventors have found that MoS ₂ is contained in the chromate film.
When the coefficient of friction was measured by adding, the reduction of the coefficient of friction and the improvement of press formability were confirmed even with MoS ₂ added in the chromate film as compared with the chromate film alone. From the observation with a scanning electron microscope, MoS ₂ was present on the surface of the chromate film in a form of revealing a face, and M exposed on this surface was exposed.
It is estimated that the press moldability was improved by the cleavage of oS ₂ .

The prior art is to improve the press formability by subjecting the surface of an Al alloy plate to hard Fe-based plating and changing the components to those suitable for formability. On the other hand, the present invention improves the press formability of the Al alloy plate by adding MoS ₂ having lubricity to the chromate and improving the press formability of the Al alloy plate by the lubricity of MoS _2. It is considered that moldability can be imparted.

The average particle size of MoS ₂ is set to 2 μm or less, because the average particle size of MoS ₂ is larger than 2 μm, MoS ₂ is added to the mold.
This is because of the adherence and deterioration of the appearance. Mo
The content of S _{2 in} the chromate film is 0.2 to 10 wt%
Is preferred. The MoS less than the content of ₂ 0.2 wt%, not appear the effect of improving the press-formability with the addition of MoS _2, decrease in corrosion resistance occurs at 10 wt% greater. Considering the above points, the average particle size and the addition amount of MoS ₂ are limited.
On the other hand, the adhesion amount of the chromate film containing MoS ₂ dispersed therein is limited to 30 to 100 mg / m ^{2 because} it is 30 m.
If it is less than g / m ² , since MoS ₂ cannot be sufficiently retained, press formability is not improved, and 100 mg / m ²
This is because if it exceeds the above range, problems such as a coloring phenomenon due to Cr ⁶⁺ and a decrease in adhesion occur.

The chromate film containing MoS ₂ of the present invention comprises a known chromate treatment liquid containing MoS ₂ dispersed therein, and a reactive chromate treatment, a coating chromate treatment,
It can be produced by any of the electrolytic chromate treatments. The content of MoS _{2 in} the chromate film can control the content of MoS _{2 in} the chromate treatment liquid.

When it is necessary to further improve the corrosion resistance of the Al alloy plate, Zn or a Zn-based alloy plating may be applied to the lower layer of the chromate film. For the lower layer plating, Zn alone or Fe, Ni, C containing Zn as a main component is used.
A material containing 1 to 30 wt% of one or more alloy elements of r is preferable from the viewpoint of corrosion resistance. For example, Z
n, Zn-Fe, Zn-Ni, Zn-Cr, Zn-Cr
-Ni etc. can be mentioned. Note that the addition amount of the alloying element is limited to 1 to 30 wt% because if it is less than 1 wt%, the effect of improving the corrosion resistance due to the addition of the alloy cannot be obtained.
This is because if it exceeds 30 wt%, the corrosion resistance is deteriorated. Z
The amount of n or Zn alloy plating applied is 1 to 60 g / m ²
The reason is that if the amount is less than 1 g / m ² , the sufficient effect of plating cannot be obtained, and if the amount exceeds 60 g / m ² , the plating adhesion amount becomes excessive, resulting in plating peeling and sufficient press molding. This is because the sex cannot be obtained.

The Zn or Zn-based alloy plating for the lower layer plating can be produced by a known plating treatment method, and is generally produced by an electrolytic method. However, since the Al alloy plate is generally inferior in plating adhesion, it is common to perform a base plating treatment prior to the electrolysis method. As the undercoating treatment, there are known a zincate method, which is displacement plating using an alkaline zinc bath, and an anodizing method, which forms an anodic oxide film on the surface of an Al alloy plate. Each of these methods forms an extremely small amount of underlayer at the interface between the plating and the Al alloy plate, and has no adverse effect on the Zn or Zn-based alloy plating of the present invention, and is sufficiently applicable.

As the electrolytic plating method after the undercoating treatment, for example, zinc sulfate alone or containing zinc sulfate, and further selected from the group consisting of iron sulfate, nickel sulfate, and chromium sulfate, or two of them.
Pb in the aqueous solution containing one or more sulfates, A
Various alloy platings can be performed by performing cathodic electrolysis at a current density of 5 to 200 A / dm ^{2 using} the l alloy plate as a cathode. The lower layer plating of the present invention can be produced by the above method. Hereinafter, the effects of the present invention will be described in detail with reference to Examples.

[0016]

Example As the Al alloy plate, a JIS-5182 Al alloy plate having a plate thickness of 1.0 mm, which is generally used for automobiles, was used. The test material in which the chromate film containing MoS ₂ was directly applied to the Al alloy plate was degreased on the Al alloy plate, and then Alchrome 713 (manufactured by Nippon Parkerizing Co., Ltd.) was used as the chromate treatment liquid. Particle size 0.
Chromate treatment was performed after dispersing and containing MoS ₂ (made by Mori Powder PA Sumiko Lubricant) of 5 μm or less. The composition of the prepared chromate film has a Cr content of 30, 50, 80
mg / m ² , MoS ₂ content 0, ² , 5, 10 wt%. Alternatively, as a comparative example, an untreated Al alloy plate and a test material having a Cr amount of 50 mg / m ² and not containing MoS ₂ were used.

On the other hand, the test material having Zn or Zn-based alloy plating as the lower layer contains a pretreatment liquid for degreasing and anodizing treatment, zinc sulfate alone or zinc sulfate, and further contains iron sulfate, nickel sulfate, and chromium sulfate. Various Zn or Zn-based alloy platings were prepared by performing cathodic electrolysis using an Al alloy plate as a cathode in a sulfuric acid acidic aqueous solution containing at least one kind.
The prepared plating is Zn plating, Fe content is 12 wt%
Zn-Fe plating, Zn-N with Ni content of 12 wt%
i plating, Zn-Cr plating with Cr content of 12 wt%,
Zn with a Cr content of 10 wt% -Ni content of 1.2 wt%
-Cr-Ni plating. The adhesion amount was 20 g / m ² . Adhesion amount 8 in Zn-Fe alloy plating as a comparison agent
A test material of 0 g / m ² was also prepared. The chromate film containing MoS ₂ was adhered to these by the above method. The composition of the prepared chromate film is 50 mg of Cr /
The content of m ² and MoS ₂ is 5 wt%.

Flat plate pull-out test (friction coefficient measurement), yarn rust resistance test (thread rust occurrence) for various Al alloy sheets produced
I went. The test conditions are shown below. (Plate pull-out test) Specimen size: 300 mm (L) x 30 mm (W) x 1 m
m (T) Pressing force: 450 kgf Pulling speed: 200 mm / min Tool contact area: 900 mm ² (30 mm x 30 mm)

(Yarn rust resistance test) Test piece size: 150 mm (L) x 70 mm (W) x 1 m
Preparation of m (T) test piece: Three coats of electrodeposition coating, intermediate coating and top coating were performed, and then scratches reaching the groundwork were added. Test environment: Salt spray (JIS Z2371) + wet environment

The obtained flat plate pull-out test (moldability test)
Tables 1 and 2 show the evaluation results of the corrosion resistance test and the comprehensive evaluation results. As for the evaluation of formability, those equivalent to cold-rolled steel sheets have good formability (◎), those that are slightly inferior to cold-rolled steel sheets but can be used (○), and those that are considerably inferior to cold-rolled steel sheet (△). It went in three steps. The corrosion resistance was evaluated in three stages: no thread rust, good corrosion resistance (⊚), thread rust length of 1 mm or less is acceptable (◯), and thread rust length of more than 1 mm is bad (Δ). The overall evaluation is that the moldability and the corrosion resistance are both good (◎), the combination of ◎ and ○ is good, the combination of ○ and ○ is good (○), and the one that is △ is bad (△). did.

In Tables 1 and 2, Mo is contained in the chromate film.
It is shown that the formability is improved by the inclusion of S _{2, and} that the chromate-treated one is superior to the Al alloy plate alone in corrosion resistance, and the plating of the lower layer further improves the corrosion resistance. There is. On the other hand, in the case of the comparison agent to which MoS ₂ is not added or the comparison agent with a large amount of plating adhered, the moldability is deteriorated.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

Industrial Applicability As described above, the Al alloy sheet of the present invention has excellent press formability and corrosion resistance, is suitable as a lightweight material for automobiles, and has a great industrial value. .

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[Procedure amendment]

[Submission date] September 22, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

The present invention will be described in detail below. In the present invention, a chromate film containing MoS ₂ is applied for the purpose of improving the corrosion resistance and press formability of the Al alloy plate. MoS ₂ added to the chromate film is an inorganic compound that is mainly used as a solid lubricant, has a hexagonal crystal structure, and the plane hexagonal layer of Mo atoms is between two layers of sulfur atoms. It has a layered structure sandwiched between. Since the bonding force between the sulfur atoms in this structure is very weak, it is said that even a slight force causes a slip between the layers, resulting in low friction resistance.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

The chromate film containing MoS ₂ of the present invention comprises a known chromate treatment liquid containing MoS ₂ dispersed therein, and a reactive chromate treatment, a coating chromate treatment,
It can be produced by any of the electrolytic chromate treatments. Content in the chromate coating MoS ₂ can be controlled by the amount of MoS ₂ in the chromating solution.

Claims (2)

[Claims] 1. A chromate film containing 0.2 to 10 wt% of MoS ₂ having an average particle diameter of 2 μm or less in an amount of 30 to 100 mg / m ^{2 in} terms of Cr on one side or both sides of an Al alloy plate.
Al alloy plate having excellent press formability and corrosion resistance, which is characterized by having a range of 2. A single layer or both sides of an Al alloy plate, Zn alone or as a main component of Zn as a lower layer, Fe, Ni,
1 to 2 or more alloy elements selected from Cr
Adhesion amount of Zn-based alloy plating containing 30 wt% is 1 to 60
It is characterized in that it has a chromate film in the range of g / m ² and an upper layer containing 0.2 to 10 wt% of MoS ₂ having an average particle size of 2 μm or less in the range of 30 to 100 mg / m ^{2 in} terms of Cr. Al alloy plate with excellent press formability and corrosion resistance.