JPH0748693A - Al alloy sheet excellent in press formability and corrosion resistance - Google Patents

Abstract

PURPOSE:To obtain a plated Al alloy sheet excellent in press formability and corrosion resistance by providing the surface of an Al alloy sheet with a galvannealing film contg. a specified amt. of fine MoS2. CONSTITUTION:At least either surface of an Al alloy sheet is provided with a galvannealing film to obtain a plated Al alloy sheet. At this time, the galvannealing film is incorporated with MoS2 having <=1mum average grain size by 0.2-20wt. Concerning the galvannealing film, preferably, it contains 40-95% Fe, and its coating weight is regulated to 0.5-3g/m<2>. Regarding its ordinary general application, it may have a compsn. constituted of Zn alone or essentially consisting of Zn and contg. 1-30% of one or more kinds among Fe, Ni, Cr, Co and Mn, and its coating weight may be regulated to 1-60g/m<2>. Thus, the Al alloy sheet standing high speed and shocking press working such as bending, shearing and blanking and excellent in corrosion resistance can be obtd.

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 Zn-based alloy plating film, and more specifically, it has excellent press formability and corrosion resistance, and is suitable for various applications such as automobiles. The present invention relates to a system alloy plating coated Al alloy plate.

[0002]

2. Description of the Related Art In recent years, automobile manufacturers have been trying to reduce the weight of automobile bodies in consideration of exhaust gas regulations related to global environmental problems. As a material therefor, in place of various steel sheets that have been conventionally used, a lighter weight Al alloy sheet has attracted attention, and the amount used has a tendency 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. In particular, since the Al alloy plate is a material superior to the steel plate in terms of corrosion resistance, improving the press formability is a major issue.

As a method for improving the press formability of an Al alloy sheet, there are a method of making the material of the Al alloy suitable for press forming, and a method of applying plating to the surface used in the field of steel sheets. It is common. As an example in which the material of the Al alloy is changed to one suitable for press molding, there is JP-A-5-33107. This limits the composition of the Al alloy and improves the formability. 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.

On the other hand, examples of plating the surface of an Al alloy plate include Japanese Patent Laid-Open No. 25656/1993 and Japanese Patent Laid-Open No. 5-25656.
There are 25657 and JP-A-5-25658. Each of these attempts to improve press formability by applying a Fe-based hard plating on the surface of Al. 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 a Zn-based alloy plating-coated Al alloy plate having sufficient press formability and corrosion resistance for automobiles.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors have studied in detail the corrosion resistance and press formability of various Zn-based alloy plated Al alloy plates. As a result, MoS
It was found that the press formability and corrosion resistance were improved by incorporating ₂ into the Zn-based alloy plating film, and the present invention was completed. The gist of the present invention is: (1) In a plating-coated Al alloy plate having a Zn-based alloy plating film on at least one surface of an Al alloy plate, MoS having an average particle size of 1 μm or less in the Zn-based alloy plating film.
An Al alloy plate excellent in press formability and corrosion resistance, characterized by containing 0.2 to 20 wt% of ₂ . (2) In the description of (1), the Zn-based alloy plating film is F
An Al alloy plate having excellent press formability and corrosion resistance, which is characterized by containing 40 to 95% of e and having an adhesion amount of 0.5 to 3 g / m ² . (3) In the description of (1), the Zn-based alloy plating film is Z
Fe, Ni, Cr, C mainly composed of n alone or Zn
1 to 3 of one or more alloy elements selected from o and Mn
It is an Al alloy plate excellent in press formability and corrosion resistance, characterized by containing 0 wt% and having an adhesion amount of 1 to 60 g / m ² .

The present invention will be described in detail below. MoS ₂ added to the Zn-based alloy plating layer is an inorganic compound mainly used as a solid lubricant, has a hexagonal crystal structure, and a plane hexagonal layer of Mo atoms has two sulfur atoms. It has a layered structure sandwiched between layers. 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 inventors of the present invention measured MoF ₂ by adding MoS ₂ during Zn-Fe alloy plating, and found that even MoS ₂ added during plating showed a decrease in friction coefficient and an improvement in press formability as compared with plating alone. confirmed. The conventional technique is to improve press formability by applying Fe-based hard plating on the surface of an Al alloy plate. On the contrary,
The present invention provides MoS ₂ having lubricity in and on the plating.
Is added to improve the press formability of the Al alloy plate by the synergistic effect of the lubricity of the plating and the lubricity of MoS ₂ , so it is considered that the press formability superior to that of the prior art can be imparted. .

MoS₂The average particle size of 1 μm or less
When the average particle size exceeds 1 μm, MoS₂
This is because of the adherence and deterioration of the appearance. In particular
This tendency is large under conditions where the coating weight is small. MoS
₂The content in the plating of 0.2 to 20 wt% is preferable.
Yes. MoS₂Is less than 0.2 wt%, MoS
₂The effect of improving press formability due to the addition of
If it is more than wt%, the corrosion resistance will decrease. Considering the above points
MoS₂The average particle size and the addition amount were limited.

Next, the press formability can be remarkably improved by selecting a Zn--Fe alloy as the plating layer containing MoS ₂ dispersed therein. The reason is that the plating is hard and has excellent lubricity. Zn-Fe
The Fe content in the alloy plating is preferably 40 to 95 wt%, and the adhesion amount is preferably 0.5 to 3 g / m ² . The lower limit of the Fe content is set to 40 wt% because the press formability tends to be improved by adding even a small amount of Fe.
This is because if it is less than 40 wt%, sufficient moldability cannot be obtained, and the upper limit is set to 95% because if it exceeds 95 wt%, there is a problem in corrosion resistance. The lower limit of the coating weight is 0.
5 g / m ² is because MoS is less than 0.5 g / m ^2.
_This is because sufficient moldability cannot be obtained due to the small amount of retained ₂ and the upper limit was set to 3 g / m ² because there is a problem in corrosion resistance due to the large amount of plating remaining after zinc phosphate treatment. is there. Considering the above points, the composition and the amount of Zn-Fe alloy plating were limited.

Although the Zn--Fe alloy plating can improve the formability, it has a high Fe content, which may cause red rust and has a problem in corrosion resistance. Therefore, in the present invention, by controlling the Zn-Fe alloy plating deposition amount to a small amount, the Zn phosphate treatment in the automobile manufacturing process enables
-Fe alloy plating turns into a form that improves the adhesiveness of the coating film by becoming houpite or phosphophyllite, and at the same time,
The residual amount of the Zn—Fe alloy plating is zero or small, which is a feature that causes of occurrence of red rust are reduced. Also F
e Rich plating layer tends to preferentially generate phosphophyllite, which has excellent coating adhesion, and has excellent corrosion resistance. M
selecting a Zn-Fe alloy as the plating layer containing oS _2, since the press-formability with excellent as described above is obtained, it is well tolerated in the molding of demanding complicated shape.

On the other hand, the lubricating effect of MoS ₂ is MoS
_Since it is derived from the slip in the crystal of No. ₂ , even if the improvement of the press formability cannot be expected because it is soft like Zn single plating, it is usually obtained by adding MoS _2. Sufficient press moldability can be secured. Therefore, A used in such applications
In the case of the 1-alloy plate, iron-based plating having a high iron content is not necessarily required, and as a Zn-based alloy plating layer containing MoS ₂ dispersed therein, Zn alone or Zn containing Fe, Ni A material containing 1 to 30 wt% of one or more alloy elements such as Co, Cr and Mn is preferable from the viewpoint of corrosion resistance. For example, Zn, Zn-Fe, Zn-Ni, Zn
-Co, Zn-Cr, Zn-Mn, Zn-Cr-Ni etc. can be mentioned.

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, and if it exceeds 30 wt%, the corrosion resistance decreases. . The amount of Zn-based alloy plating deposited is limited to 0.1 to 60 g / m ² . The reason is 0.
Can not be obtained sufficient press formability because a small amount retained MoS ₂ in the plating layer is less than ^{1g / m 2, 60g / m} 2
This is because if the content exceeds the above range, the amount of coating adhered will be excessive, resulting in plating peeling and insufficient press formability.

The Zn-based alloy plating of the present invention 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, the zincate method, which is displacement plating using an alkali zinc bath, A
A known anodic oxidation method is to form an anodic oxide film on the surface. Each of these methods forms an extremely small amount of underlayer at the interface between plating and Al.
Alternatively, it has no adverse effect on Zn-based alloy plating and can be sufficiently applied.

As the electrolytic plating method after the base plating treatment, for example, an aqueous solution containing zinc sulfate alone or zinc sulfate, and further containing one or more sulfates of iron sulfate, nickel sulfate, chromium sulfate, cobalt sulfate, and manganese sulfate. Inside,
Various alloy plating can be performed by performing cathodic electrolysis at a current density of 5 to 200 A / dm ² using Pb as an anode and an aluminum alloy plate as a cathode. The plating of the present invention can be produced by the above method. Zn-Fe containing MoS ₂
For alloy plating, Mo in an aqueous solution of zinc sulfate and iron sulfate.
The fine particles of S ₂ can be dispersed, and thereafter, the same method as in the plating described above can be used for production. The concentration of MoS ₂ dispersed and present in the plating is determined by the amount of MoS ₂ in the sulfate aqueous solution.
It can be controlled by the concentration of S ₂ . Hereinafter, the effects of the present invention will be described in detail with reference to Examples.

[0015]

【Example】

Example 1 As an Al alloy plate, a plate thickness of 1.
A 0 mm JIS-5182 aluminum alloy plate was used. First, the surface of the Al alloy plate was degreased (FC315, 20 g / l, 7 manufactured by Nippon Parkerizing Co., Ltd.).
(0 ° C., 20 seconds), and then anodizing treatment. After pretreatment described above, include zinc sulfate ferrous sulfate, further in sulfuric acid aqueous solution containing MoS _2, by cathode electrolysis the aluminum alloy plate as the cathode, various shown in Table 1 MoS ₂ containing Zn-Fe alloy plating Was produced.
MoS ₂ having an average particle size of 0.5 μm or less was used (Mori Powder PA Sumiko Lubricant). The composition of Zn—Fe alloy plating and the content of MoS ₂ were the same as those in the zinc sulfate in the plating bath. It was controlled from the ratio of iron sulfate, the amount of MoS ₂ added, and the cathode electrolysis time. About the produced Zn-Fe alloy plated Al alloy plate, flat plate pull-out test (friction coefficient measurement) and salt spray (35 ° C, 24 hours) → wet (40 ° C, 80% R)
H, 120 hours)-> Lefting indoors (room temperature, 24 hours) was set as one cycle, and after performing 8 cycles, a thread rust resistance test (thread rust occurrence) was performed. The test conditions are shown below.

(Conditions for flat 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)

(Thread rust test) Specimen size: 150 mm (L) x 70 mm (W) x 1 m
m (T) Test piece adjustment: For Zn-Fe alloy plated aluminum plate,
After zinc phosphate treatment, electrodeposition coating, intermediate coating and top coating, scratches reaching the groundwork were made. Table 1 shows the obtained evaluation test results.

[0018]

[Table 1]

The moldability was evaluated in three stages of good (⊚), acceptable (∘) and bad (Δ). Good formability (◎): Equivalent to cold-rolled steel sheet Possible (○): Slightly inferior to cold-rolled steel sheet (△): Inferior to cold-rolled steel sheet

In addition, the corrosion resistance was evaluated by good corrosion resistance (⊚),
The test was conducted in three stages: good (○) and bad (△). Good corrosion resistance (◎): Maximum thread rust length of less than 1 mm Possible (◯): Maximum thread rust length of 1 to 3 mm Bad (△): Maximum thread rust length of 3 mm or more Comprehensive evaluation shows that both moldability and corrosion resistance are ◎ Goods were rated as good (◎), combinations of ◎ and 〇, combinations of 〇 and 〇 were acceptable (○), and those with either △ were not acceptable (△). From Table 1, MoS ₂ was added under the conditions of the present invention, and Zn-Fe
It is clear that the press formability and the corrosion resistance are improved by controlling the amount and composition of the alloy plating.

Example 2 Using an Al alloy plate anodized in the same manner as in Example 1, zinc sulfate alone or zinc sulfate was further added, and iron sulfate, nickel sulfate, chromium sulfate, cobalt sulfate and manganese sulfate were added. Various Zn-based alloy platings shown in Table 2 were prepared by dispersing the same MoS ₂ as in Example 1 in an aqueous sulfuric acid solution containing at least one of the above and subjecting the aluminum alloy plate to cathodic electrolysis. The obtained Zn-based alloy plated Al alloy plate was subjected to a flat plate drawing test under the same conditions as in Example 1 to evaluate the press formability. Table 2
As is clearer, the effect of improving press formability was observed by adding MoS ₂ to the Zn-based alloy plating.

[0022]

[Table 2]

[0023]

As described above, the Al alloy sheet coated with the Zn-based alloy plating containing MoS ₂ of the present invention has excellent press formability and corrosion resistance and is suitable as a lightweight material for automobiles. It has a great industrial value.

Claims (3)

[Claims] 1. Z is formed on at least one surface of an Al alloy plate.
In a plating-coated Al alloy plate having an n-based alloy plating film, the Zn-based alloy plating film contains 0.2 to 20 wt% of MoS ₂ having an average particle size of 1 μm or less. Excellent Al alloy plate. 2. The Zn-based alloy plating film according to claim 1, containing 40 to 95% of Fe and 0.5 to 3 g / m.
An Al alloy plate having excellent press formability and corrosion resistance, which is characterized by having an adhesion amount of ² . 3. The Zn-based alloy plating film according to claim 1, wherein the Zn-based alloy plating film contains Zn alone or Zn and Fe as a main component.
1 to 30 wt% of one or more alloying elements selected from i, Cr, Co and Mn, and an adhesion amount of 1 to 60 g / m ² , which is excellent in press formability and corrosion resistance. Al alloy plate.