JPH08108502A - Aluminum alloy plate with excellent pressing processability and spot weldability - Google Patents

Abstract

PURPOSE: To provide an aluminum alloy plate covered with an organic lubricating resin in which its spot weldability is remarkably improved without impairing the improving effect of pressing processability of the plate by organic lubricating resin treatment and both the characteristics are improved to a level available at a present steel plate manufacturing line. CONSTITUTION: An original aluminum alloy plate has a chromate film of 1.0-20.0mg/m<2> as a first layer on the surface in terms of metal Cr, an organic resin film containing 60-90wt.% of organic lubricant as a second layer thereon as a dry film having a thickness of 0.05-0.90μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy plate treated with an organic resin, which has excellent spot weldability and press workability and is suitable for automobile bodies and the like.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for reducing the weight of automobile bodies due to global environmental problems. Therefore, utilization of an aluminum alloy plate having high strength against weight has been studied, and it has already been put to practical use for some parts. However, aluminum alloy sheets have extremely poor formability compared to steel sheets, so their use in automobile bodies is limited to lightly machined parts such as bonnets, and to more complex and strong machined door materials. Is said to be difficult to use.

The poor formability of aluminum alloy sheets is due to
In addition to the poor formability of the aluminum alloy plate itself, which is a raw material, because aluminum has a low melting point and is soft, it has a strong affinity with cast iron, which is widely used in press dies, and is easily adhered to dies. This is due to the poor slidability.

Further, since the aluminum alloy plate has a shorter electrode life during spot welding than the steel plate, it deteriorates the production efficiency of the vehicle body using this. That is, in spot welding of an aluminum alloy plate, the welding phenomenon between the electrode and the aluminum alloy plate is likely to occur, and the number of continuous points where an appropriate shear strength of the nugget portion can be obtained with the same electrode is extremely short. Therefore, the electrode tip shape is often dressed or replaced with a new electrode before welding occurs or before a proper nugget cannot be formed. Therefore, the current situation is that the production efficiency is significantly reduced. As described above, various efforts have been made to improve the formability and spot resistance weldability of aluminum alloy sheets, which have been low in the past.

First, as a technique for improving the composition and structure of the aluminum alloy sheet, for example, Japanese Patent Laid-Open No. 61-1 / 1986 is proposed.
Japanese Patent No. 30452 and Japanese Patent Laid-Open No. 3-287739 disclose a manufacturing method for improving the elongation property and improving the workability by limiting the upper limits of the amounts of Fe and Si and increasing the addition amount of Mg, and There is a technique disclosed in JP-A-4-123879, which improves the electrode life by controlling the thickness of the oxide film on the surface of the aluminum alloy plate to an appropriate electric resistance value.

However, as described in JP-A-61-130452 and JP-A-3-287739, it is indispensable to use expensive high-purity metal as a raw material in order to obtain a high-ductility alloy. There is a problem that performance is markedly reduced and there is no significant improvement in workability commensurate with the price increase. On the other hand, JP-A-4-12
Although the control of the surface electric resistance value is effective for improving the weldability as described in Japanese Patent No. 3879, there is a problem that the improvement of the workability cannot be expected at all.

Considering the priority in the manufacturing process of automobiles, it is considered that it is necessary to improve the workability of the aluminum alloy sheet. From this point of view, the formability of the aluminum alloy sheet is determined by the lubricating resin coating. Attempts have been made to improve by applying. For example, JP-A-6-184
No. 587 and No. 6-305074, a water-soluble organic lubricating resin treatment, that is, a defilming type (a film is dissolved and removed in a degreasing process in a phosphate chemical conversion treatment step after pressing) solid lubricant is provided. The improvement technique by this is disclosed.
However, the deterioration of weldability is unavoidable with these film-removing type lubricating resin coatings, and the resin removal is incomplete, which tends to cause defects in phosphate chemical conversion treatment, and corrosion resistance (resistance to corrosion) higher than that of bare aluminum alloy sheets. There is a problem that it is not possible to add (corrosion of thread rust).

Further, in JP-A-4-268038 and JP-A-6-55137, an organic lubricating resin coating applied to a Zn-plated steel sheet, that is, a chromate-treated aluminum alloy sheet, is coated with a base resin. Discloses a technique in which a non-film-removing type resin for a lubricating steel sheet, which is obtained by adding an organic lubricant such as wax or a fluorine-based resin, is directly used for an aluminum alloy sheet. However, all of these techniques are intended only to improve the corrosion resistance and press workability, the spot weldability is not taken into consideration at all, and compared with the aluminum alloy plate before forming the organic resin coating, the spot is remarkably spotted. It has a drawback that the weldability deteriorates.

As a technique for improving this drawback, it is conceivable to thin the resin and add a conductive auxiliary agent to the resin. For example, Japanese Laid-Open Patent Publication No. 3-18936 discloses an improvement technique by forming a thin organic resin film on the surface of an original aluminum alloy plate by limiting the film thickness to a very small thickness. Since the resin does not contain an organic lubricant, naturally there is a problem that sufficient press formability cannot be obtained. In addition, JP-A-5-30933
Each of Japanese Patent Nos. 1 and 311544 discloses a technique of adding a conductive auxiliary agent such as iron phosphide (for example, Japanese Examined Patent Publication No. 62-73938), which is also used in lubricating steel sheets, to a lubricating resin. However, the effect of improving the weldability due to the addition of such a conductive additive is not sufficient, and some of the inorganic conductive additives to be added deteriorate the workability and hinder the coating property of the lubricating resin (for roping). There is a problem to occur.

In the techniques disclosed in JP-A-5-309331 and JP-A-3115445, the inclusion of an organic lubricant (though it is considered that fluororesins are targeted especially from the examples) in order to further enhance the processability. There is a feature that the amount is higher than usual. However, although not disclosed in the present technology, although improvement in weldability due to this is expected, there is a problem that the improvement effect is extremely small in the addition range of the present technology.

When an aluminum alloy sheet is used as a vehicle body sheet of an automobile, it is important to have excellent spot weldability as well as press formability. In particular, when an organic coating is formed on an aluminum alloy plate to improve press formability, the conventional organic coating for lubricating steel plates has a high electric resistance, so that the spot weldability is at a level that cannot be practically used. The problem of deterioration occurs. This is a problem peculiar to aluminum alloy plates due to the extremely small electric resistance (about 1/4) compared to steel plates, but with the application or slight modification of conventional organic coatings for lubricating steel plates, aluminum alloy plates Under the present circumstances, it is extremely difficult to improve both the press workability and the spot weldability of the plate at a high level.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and the effect of improving the favorable press workability of an aluminum alloy sheet by the organic lubricating resin treatment is not impaired. An aluminum alloy sheet coated with a non-film-removing organic lubricating resin that has improved spot weldability significantly without the addition of an inorganic conductive additive and has improved the properties of both to the level that can be used in existing steel sheet production lines. To provide.

[0013]

Means for Solving the Problems The inventors of the present invention have diligently studied the problem of spot weldability in using an aluminum alloy sheet having an organic lubricating resin treatment and improved press formability for an automobile body. The present invention has been completed based on the following knowledge.

The organic lubricating resin coating (hereinafter referred to as an organic coating) formed on the lubricated steel sheet usually contains about 10% of an organic lubricant. An aluminum alloy plate having such an organic coating has an extremely high electric resistance of the organic coating,
The organic coating usually has a volume resistivity of around 10 ¹⁵ Ω · cm. Further, even if the organic coating is a thin film of about 1 μm, the interlayer resistance of 10 ¹⁰ Ω or more is still generated, so that the heat generated in the resin layer is excessive, which causes a problem that the spot weldability is significantly deteriorated. As a result of a more detailed study on this point, it is extremely effective to reduce the spot welding resistance by making the film thickness of the organic coating smaller than before and by significantly increasing the content of the organic lubricant in the organic coating as compared with the conventional one. We obtained a new finding that

Moreover, in addition to the improvement of the above organic coating, the thickness of the oxide coating on the surface of the aluminum alloy plate, which is a factor of resistance to spot welding as with the organic resin, and the thickness of the chromate coating applied as the base treatment are less than the specified value. It was found that the spot weldability can be further improved by limiting the amount to 10%. Further, reducing the film thickness of the organic coating may reduce the press workability improving effect of forming the coating, but the content of the organic lubricant in the above-mentioned organic coating should be significantly increased. With the improvement of the weldability, the press workability can be improved because the effect of the organic lubricant is increased. As a result, it was found that the press workability and the spot weldability can be better achieved at the same time.

The present invention has been completed based on the above findings, that is, 1.0 to 50.0 mg / m ^{2 in} terms of metallic Cr as the first layer on the surface of an aluminum alloy original plate.
The organic resin film containing the organic lubricant in an amount of more than 60% by weight and 95% by weight or less as the second layer on the upper surface of the chromate film of 0.02 to 0.90 μm. It is intended to provide an aluminum alloy sheet having excellent press workability and spot weldability.

Here, the thickness of the oxide film on the surface of the aluminum alloy plate is preferably 100 Å or less. Also,
The organic lubricant has an average molecular weight of 900 to 15,000,
High density polyethylene having a density of 0.93 or more is preferable.

[0018]

The present invention will be described below in more detail. The aluminum alloy original plate used for the aluminum alloy plate having excellent press workability and spot weldability of the present invention (hereinafter referred to as aluminum alloy plate) is not particularly limited, and various known aluminum alloy plates can be used. Is. Above all, the JIS 5000 series and JIS 6000 series aluminum alloy plates currently used for automobiles or being considered for use are preferably used, and various aluminum alloy plates specified in JIS H4000 are also suitable. It is preferably used.

The aluminum alloy original plate (hereinafter referred to as original plate) used in the present invention has a surface roughness of Ra.
(Center line average roughness specified in JIS B0601) 0.8 μm
The following is desirable.

The press workability of the aluminum alloy plate can be improved by improving the slidability of its surface. To improve the slidability, an organic coating containing an organic lubricant is formed on the surface of the aluminum alloy plate. Is extremely effective. In the present invention, the effectiveness of the organic coating is such that the smaller the surface roughness is, the more the press workability can be improved with a smaller film thickness (coating amount of the organic coating) than before.

Further, in order to improve the deterioration of the spot weldability, it is usually effective to reduce the film thickness of the organic coating to be formed, but this causes deterioration of the press workability. However, in the present invention, the deterioration can be prevented by increasing the content of the organic lubricant contained in the organic coating.

In the aluminum alloy plate of the present invention,
By setting Ra of the original plate to 0.8 μm or less, more preferably, Ra of the original plate is set to 0.5 μm or less,
It is preferable because the film thickness can be reduced to further improve the spot weldability and the press workability.

Further, in the aluminum alloy sheet of the present invention, in order to reduce the welding resistance to improve the spot weldability and to form a uniform chromate layer, in the production process of the original sheet by etching or the like, It is preferable to remove a part or most of the non-uniform oxide layer formed on the surface of the oxide film so that the thickness is 100 Å or less. By setting the thickness of the oxide film on the surface of the original plate to 100 Å or less, more preferably 50 Å or less, the spot weldability can be further improved.

As the etching treatment, an alkali etching treatment for removing the alumina (Al ₂ O ₃ ) layer on the surface with an alkali aqueous solution, a pickling treatment for mainly removing the magnesia (MgO) layer in an acidic aqueous solution, or an alkali etching treatment Any one of the post-pickling treatments may be used. The alkali etching treatment and the pickling treatment may be the methods generally used for treating aluminum alloys, and a commercially available treatment solution can be used. For example, caustic soda, caustic potash, etc. can be used for the alkali etching treatment, and sulfuric acid, phosphoric acid, nitric acid, hydrofluoric acid, a mixed solution of nitric acid and hydrofluoric acid, etc. can be used for the pickling treatment.

In the aluminum alloy plate, especially A
The surface oxide film is mainly composed of acid-soluble MgO in the 1-Mg-based alloy, and MgO is dissolved and removed in the chromate treatment process with a strongly acidic chromate solution described later, and the thickness of the oxide film is 100 Å or less. In some cases, it is possible to omit the oxide film removing process.

Further, when an oxidation suppressing element such as Be is added to the original plate, the formation of an oxide film in the annealing process is suppressed, so that the oxide film may have a thickness of 100 Å or less in such an original plate. In this case as well, it is possible to omit the above-mentioned oxide film removal processing.

In the present invention, such an original plate is subjected to chromate treatment to form a chromate film. The method of chromate treatment may be a commonly used treatment method, for example, reactive chromate treatment, coating chromate treatment, electrolytic chromate treatment or the like, but from the viewpoint of ease of treatment, reactive chromate treatment or coating. Type chromate treatment is preferred.

The reactive chromate treatment involves dipping, washing with water and drying in a strongly acidic solution containing chromic acid, phosphoric acid, nitric acid, hydrofluoric acid, etc. It is necessary to increase the activity of the aluminum alloy plate by including 1 to 20% by weight. The chromate film formed by the reactive chromate treatment includes a chromate chromate film, a phosphoric acid chromate film, and the like, but there is no difference in characteristics in any case.

On the other hand, the chromate film formed by the coating type chromate treatment is a direct roll coater using an aqueous solution containing partially reduced chromic acid as a main component and at least one kind of phosphoric acid, acrylic resin, silica particles and the like. Method, or by dipping or spraying the original plate in this aqueous solution, adjusting the amount of adhesion by the air knife method or roll squeezing method, and then baking and drying at 100 to 200 ° C without washing with water. You can

Since the coating type chromate coating has a characteristic that the adhesion form is unevenly distributed (larger in the concave portions), it is preferable to increase the adhesion amount. Further, there is a feature that the content rate of alkali-soluble chromium in the chromate film is large, which is advantageous for corrosion resistance, but if the amount is too large, elution of chromium may become a problem in the painting process of automobiles. Therefore, it is desirable that the amount of chromium that does not dissolve in the alkaline solution due to degreasing or the like be 70% by weight or more of the total amount of chromium deposited.

Further, in the coating type chromate, it is possible to add a conductive auxiliary agent such as fine metal powder (zinc, aluminum, etc.), iron phosphide, tin oxide, carbon black, etc.
Weldability can be improved by increasing the conductivity of the chromate layer, and by adding silica, alumina, molybdenum salt, tungsten salt, etc., it is possible to improve the corrosion resistance and the adhesiveness of the lubricating resin coating. The above pigment can be appropriately added if necessary.

The amount of the chromate film deposited is 1.0 to 50.0 mg / m ^{2 in} terms of metal Cr, preferably 5 to 25 m.
g / m ² . Chromate coating amount 1.0mg
When it is / m ² or more, the elution of the base aluminum during the zinc phosphate chemical conversion treatment can be preferably prevented, and the adhesiveness of the upper organic film can be made sufficient. Further, when the amount of the chromate coating adhered increases, the spot weldability tends to decrease, but the amount of adherence is 50.0.
By setting the content to be mg / m ² or less, sufficient spot weldability can be stably ensured.

In the aluminum alloy plate of the present invention,
Over 60% by weight of organic lubricant on top of the chromate coating,
An organic coating containing 95% by weight or less is formed to a dry film thickness of 0.02 to 0.90 μm.

The organic coating basically comprises a base resin and an organic lubricant. As the base resin, various known solvent-based and water-based resins for lubricating steel plates can be used, for example, epoxy resin, alkyd resin, acrylic resin, urethane resin, phenol resin, melamine resin, polyvinyl butyral resin, polyester resin and One or more kinds of these modified resins (for example, urethane modified epoxy resin, acrylic modified urethane resin, etc.) are used. From the viewpoint of weldability and adhesion of electrodeposition coating, epoxy resin, urethane resin, acrylic resin,
Polyester resins or mixed resins thereof are preferred. Various commercially available products can be suitably used as these base resins.

The organic lubricant added to the base resin is generally called wax, and is an organic substance that melts at room temperature to 200 ° C. and has a low melt viscosity. A mineral-based natural wax or petroleum wax, a synthetic hydrocarbon-based synthetic wax, and an oxidized and / or modified wax thereof can be used. For example, montan wax, paraffin wax,
Examples thereof include natural waxes such as microcrystalline wax and synthetic waxes such as Fischer-Tropsch wax, polyethylene wax and polypropylene wax. Here, as a synthetic wax, there is also Teflon (fluorine-based resin, for example, polytetrafluoroethylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin) wax, but although Teflon wax has a great effect on improving processability, It is not preferable to use it alone because it does not melt during welding and adversely affects the weldability.

Of these, polyethylene wax is particularly preferable because it is highly effective in improving press workability and is inexpensive, and has a chemically stable molecular weight of 900 which is unlikely to dissolve or swell in press washing oil. ~ 150
A high density polyethylene having a density of 0.9 and a density of 0.93 or more is more preferable. Various commercially available products can be preferably used as the organic lubricant.

Furthermore, although not particularly limited, the melting point (or softening point) of the organic lubricant used is preferably in the range of 60 to 150 ° C. When the melting point is less than 60 ° C., it is under extreme pressure during press working. Since the fluidity of the organic lubricant becomes too high, the effect of improving the workability decreases, and conversely, when it exceeds 150 ° C, the spot welding resistance increases, which is not preferable. Also, in the press processing of automobiles, the mold temperature changes during continuous pressing, which may change the wax performance. Therefore, it is effective to use two or more waxes with different melting points (or softening points) together as a countermeasure. Is.

In the aluminum alloy plate of the present invention,
The content of the organic lubricant in the organic coating is extremely important from the viewpoint of improving spot weldability.
It is an essential condition that the content be less than or equal to wt%. The mechanism of action is currently unclear, but it is presumed as follows. That is, an organic lubricant, particularly an organic lubricant having a low melting point represented by polyethylene, melts and volatilizes in the initial stage of spot welding, and easily forms a current-carrying point, so that it does not contribute to welding resistance. This fact was confirmed in the study by the present inventors from the heretofore unknown result that the welding resistance value correlates only with the film thickness of the base resin regardless of the content of the organic lubricant in the organic coating. ing. Therefore, by reducing the film thickness of the organic coating and greatly increasing the content of the organic lubricant in the organic coating, it is possible to realize an aluminum alloy plate having both spot weldability and formability.

The content of the organic lubricant in the organic coating is 6
If it is 0% by weight or less, the effect of improving spot weldability is small, and if it exceeds 95% by weight, the applied organic coating is likely to fall off during press working, and the adhesion of electrodeposition coating is adversely affected, which is preferable. Absent. Therefore, in the present invention, the content of the organic lubricant is limited to more than 60% by weight and 95% by weight or less. The preferable content of the organic lubricant is 65 to 90% by weight.

In the aluminum alloy plate of the present invention, the organic lubricant is an essential addition component to the organic coating (base resin), but in addition, if necessary, an extender pigment (carbonate, silicate, etc.), Anticorrosion pigment (silica, chromate, phosphate,
Lead salts, etc., rust inhibitors (amine compounds, phenolic carboxylic acids, etc.), conductive pigments (carbon, iron phosphide, tin oxide, etc.), color pigments (titanium oxide, carbon, etc.), dispersion stabilizers, etc. You may mix | blend 1 or more types of additives. In addition,
When these additives are added, the content of the organic lubricant may be more than 60% by weight and 95% by weight or less in the whole organic coating.

The dry thickness of the organic coating containing these organic lubricants is 0.02 to 0.90 μm, more preferably 0.10 to 0.50 μm. If the thickness of the organic coating is less than 0.02 μm, the effect of improving press workability is not sufficient, and if it exceeds 0.90 μm, the spot weldability deteriorates, so the range was 0.02 to 0.90 μm.

The above-mentioned workability of the aluminum alloy sheet treated with an organic coating of the present invention is premised on the case where a press cleaning oil is applied, but it is also effective when no oil is applied, and a high viscosity and The processability can be further improved by applying an oil of high lubricity to which an extreme pressure agent (eg, calcium stearate) is added.

The method for forming these organic coatings is not particularly limited, and the base resin and the organic lubricant are dissolved (or dispersed) in a suitable solvent, and if necessary, additives are added to the organic lubricant resin. Prepare a paint, apply by a known method such as roll coating method, curtain flow coating method,
Just bake it. The conditions for baking the coating film after coating are not particularly limited, but the maximum temperature reached is 80 to 18
The range of 0 ° C. is preferable because an aluminum alloy plate having good performance can be produced and the treatment can be performed with good thermal efficiency in a short time.

The aluminum alloy sheet of the present invention usually has the above organic coating on both sides, but if necessary, one side may be coated with the above resin coating and the other side may be untreated aluminum. It is also possible to form the alloy plate as it is, or to form only the etching surface or the chromate film.

The aluminum alloy sheet of the present invention and the method for producing the same have been described above in detail. However, the present invention is not limited to this, and various improvements and changes can be made without departing from the gist of the present invention. Of course it is good.

[0046]

EXAMPLES The present invention will be specifically described below based on examples.

(Example 1) JIS A5182-O material and JIS A6
Using the 111-T4 material, an aluminum alloy original plate with a plate thickness of 1 mm was prepared, in which the surface roughness was variously adjusted by changing the roll roughness during rolling. The original plate was subjected to an etching treatment to adjust the thickness of the oxide film on the surface of the original plate, and then subjected to a reactive chromate treatment to form a chromate film.

On the upper layer, an organic lubricating resin coating material containing various base resins and organic lubricants shown below is applied by a roll coating method, and baking is performed at a plate temperature maximum reaching temperature of 150 ° C. A resin) coating was prepared. For various aluminum alloy plates produced in this way,
The press workability, spot weldability, and post paint adhesion were investigated.

The surface roughness measurement method (1) of the original aluminum alloy plate, the etching treatment condition and the oxide film thickness measurement method (2), the chromate treatment condition and the adhesion amount measurement method (3), Organic coating composition and dry film thickness measurement method (4), press workability measurement method and evaluation method (5), spot weldability measurement method and evaluation method (6), and post-coating adhesion ( The coating method) and its evaluation method (7) are as follows. Table 1 shows each condition and its evaluation result.

(1) Measurement of surface roughness (center line average roughness (Ra)) The surface roughness of the aluminum alloy original plate was measured by a three-dimensional roughness meter in accordance with JIS B0601. Ra (three-dimensional) in this case is expressed by the following equation.

[0051]

[Equation 1] Here, S = L × L, and f (x, y) is a function indicating a surface roughness curve.

(2) Etching processing conditions In order to remove and control the oxide film on the surface of the original aluminum alloy plate, etching processing was performed under the following processing conditions. Further, the thickness of the oxide film after the treatment was measured from the oxygen intensity by a fluorescent X-ray analysis method. Treatment method A: Degreasing + 25 ° C, 10% sulfuric acid immersion treatment

(3) Chromate Treatment Conditions The etched aluminum alloy original plate was immediately subjected to chromate treatment under the following conditions. The amount of the chromate coating after the treatment was measured from the chromium intensity by the fluorescent X-ray analysis method, and the amount of the chromate deposit was expressed in terms of metallic chromium. Treatment condition A: Reactive chromate chromate treatment (Alchrom 713 manufactured by Nihon Parkerizing Co., Ltd.)

(4) Composition of Organic (Lubricating Resin) Film and Dry Film Thickness The dry film thickness of the organic film was measured from the carbon intensity by fluorescent X-ray analysis. Further, the symbols showing the composition of the organic coating in Table 1 are as follows. Base resin A; Epoxy resin (Epicote 1007 manufactured by Yuka Shell Epoxy Co., Ltd.) Organic lubricant A; Polyethylene (Sun Wax 1 manufactured by Sanyo Kasei Co., Ltd.)
51-P) (molecular weight: 1000, density: 0.93)

(5) Press workability test and its evaluation method Press cleaning oil (R303P manufactured by Sugimura Chemical Co., Ltd.) was applied to the sample surface.
After coating, each sample punched to a diameter of 70 mmφ was punched at a high speed with a punch diameter of 33 mmφ (processing speed 50
0 mm / sec). As for the evaluation of formability, those with cracks on the side surface of the cylindrical sample after processing were evaluated as bad (x), those without cracks but with galling were rated as normal (○), and those without these defects were evaluated as good ( ◎).

(6) Spot Weldability Test and Evaluation Method The electrode life of the treated aluminum alloy plate was evaluated using a single-phase AC welding machine under the following electrodes and welding conditions. For the evaluation, the effect was judged by either the number of hitting points until welding or the number of hitting points until the shear strength of the nugget falls below 143 kgf, whichever is smaller. As the evaluation criteria, the number of hit points was less than 500 points (poor), 500 to 1500 points were normal (◯), and 1501 points or more were good (⊚). [Electrode] -Shape: Dome (DR) type-Tip diameter: 6.0mmφ-Tip curvature: 40mmR-Material: Cu-Cr [Welding condition] -Pressure: 300kgf-Initial pressurization time: 30/50 seconds・ Electrification time: 3/50 seconds ・ Holding time: 1/50 seconds ・ Welding current: 25 kA

(7) Post-coating adhesion (coating property) test and its evaluation method The electrodeposition coating adhesion was evaluated by zinc phosphate chemical conversion treatment of various aluminum alloy plates (PB-L30 manufactured by Japan Parkerizing Co., Ltd.).
20; aluminum specification) process, followed by cation electrodeposition coating (U-600 manufactured by Nippon Paint Co., Ltd.) to 20 μm, and 1
After baking and curing at 70 ° C. for 20 minutes, immersion in pure water at 40 ° C. for 10 days, a 2 mm cross-cut tape peeling test (100 mesh) was performed, and the number of remaining coating films was evaluated. The evaluation standard of the adhesiveness is that the number of remaining coating films is 100 (good), 80 to 99.
Was evaluated as normal (◯), and 79 or less as defective (x).

[0058]

[Table 1]

As is clear from the results shown in Table 1, each of the examples of the present invention has excellent spot weldability because the content of the organic lubricant in the organic resin film is high. However, the comparative example has a drawback that the post-coating adhesion is poor because the content of the organic lubricant is too high. In addition, No. No. 4 has a surface roughness (Ra) of more than 0.8 μm and thus is somewhat poor in workability, but there is no problem in normal use except for applications requiring high characteristics.

(Example 2) JIS A5182-O material and JIS A6
Using the 111-T4 material, various organic resin-coated aluminum alloy plates were prepared and evaluated under the conditions shown in Table 2 in substantially the same manner as in Example 1. Table 2 shows each condition and its evaluation result. Further, only the conditions different from those of the first embodiment will be described in detail.

(2) Etching condition In Example 2, in addition to the etching in Example 1 (processing method A), the following conditions were also applied. Treatment method B: Degreasing + 70 ° C, 5% NaOH immersion treatment +25
℃, 10% nitric acid immersion treatment Treatment C: Degreasing + 25 ° C, 10% phosphoric acid immersion treatment Treatment D: Degreasing only

(3) Chromate Treatment Conditions In Example 2, in addition to the chromate treatment in Example 1 (treatment condition A), the following conditions were also used. Treatment condition B: Coating type chromate chromate treatment (Zinchrome R1415A manufactured by Japan Parkerizing Co., Ltd.) Treatment condition C: Reactive phosphate chromate treatment (Alchrome K702 manufactured by Japan Parkerizing Co., Ltd.)

(4) Composition of Organic (Lubricating Resin) Coating and Dry Film Thickness In Example 2, the organic coating (base resin A,
In addition to the organic lubricant A), the following organic coatings were also used. Base resin B; Urethane resin (MITSUBISHI KASEI MITEC BL
-100) C: Acrylic resin (Dynal manufactured by Mitsubishi Rayon Co., Ltd.
BR106) D: Polyester resin (Mitsui Toatsu Kagaku KK Almatex P646) E: Phenolic resin (Dainippon Ink and Chemicals Super Becker Sight) F: Polyvinyl butyral resin (Denki Kagaku Kogyo KK)
Denka Butyral) Organic Lubricant B; Polyethylene (Mitsui Petrochemical Industry Co., Ltd. High Wax 800P) (Molecular Weight; 8000, Density; 0.96) C; Polyethylene (Mitsui Petrochemical Industry Co., Ltd. High Wax 100P) (Molecular Weight; 8000, Density; 0.96) D; B + C (mixing ratio 50:50) E; B + Teflon (Lubron LP-10 manufactured by Asahi Glass Co., Ltd.
0) F: polyethylene (homemade, molecular weight; 18000, density; 0.92) G; polyethylene (homemade, molecular weight; 800, density;
0.80) H: Polypropylene (Viscole 5 manufactured by Sanyo Kasei Co., Ltd.)
50P)

(5) Press workability test and its evaluation method Press washing oil (R303P manufactured by Sugimura Chemical Co., Ltd.) was applied to the sample surface.
After coating, each sample punched to a diameter of 95 mmφ is punched with a punch diameter of 50 mmφ (shoulder R; 8 mm), and a pressing pressure (B
High-speed cylindrical drawing with different HF (processing speed 500 mm
/ Sec). As for the evaluation of formability, in the A5182 alloy plate, BHF exceeding 5 ton and being drawn out was good (⊚), 2 to 5 ton was normal (∘), and less than 2 ton was poor (x). Also, 4ton for A6111 alloy plate
Those that passed through above were rated as good (⊚), 2 to 4 tons were rated as normal (◯), and less than 2 tons were rated as bad (x).

(6) Spot Weldability Test and Evaluation Method The electrode life of the treated aluminum alloy sheet was evaluated using a single-phase AC welding machine under the following electrodes and welding conditions. Evaluation is the number of dots until welding or JIS Z3136
Shear strength (weld joint shear strength) of welded joints based on JI
Class A strength of 176 kgf / spo according to SZ3140 standard
The effect was judged by the number of RBIs which is smaller than the number of RBIs below t. The evaluation criteria were that the number of hit points was less than 1000 (poor), 1000 to 2000 was normal (◯), and 2001 or more was good (⊚). [Electrode] • Shape: Dome (DR) type • Tip curvature: 80 mmR • Material: Cu-Cr [Welding condition] • Pressurization: 400 kgf • Initial pressurization time: 30/50 seconds • Energization time: 3/50 Second ・ Holding time: 1/50 second ・ Welding current: 29kA

(7) Post-coating adhesion (coating property) test and its evaluation method The electrodeposition coating adhesion was evaluated by applying a press cleaning oil (R303P) to various aluminum alloy sheets and then applying a zinc phosphate chemical conversion treatment (Nippon Parkerizing). Company PB-L3020; aluminum specification, including degreasing step), followed by cationic electrodeposition coating (Nihon Paint Co. U-600) 20 μm, intermediate coating (Kansai Paint Co. KPX50) 35 μm, topcoat ( Kansai Paint Co., Ltd. B531) was applied to 35 μm and then immersed in pure water at 40 ° C. for 10 days, and then a 2 mm cross-cut tape peeling test (100 mesh) was performed to evaluate the number of remaining coating films. The evaluation standard for adhesion is 10 remaining coatings.
0 was evaluated as good (⊚), 80 to 99 was evaluated as normal (∘), and 79 or less was evaluated as poor (x).

[0067]

[Table 2]

[0068]

[Table 3]

[0069]

[Table 4]

[0070]

[Table 5]

[0071]

[Table 6]

As is clear from the results in Table 2, the examples of the present invention have both good press workability and spot weldability, whereas the comparative examples have press workability, spot weldability or post weldability. Poor coating adhesion. In this example, the surface roughness, the oxide film thickness, the chromate deposition amount, the base resin type, the organic lubrication type and the content thereof and the organic resin coating film thickness are out of the optimum ranges, so that the workability and the weldability are improved. Some of the paintability is of a normal level, but there is no problem in normal use unless the application requires high characteristics.

[0073]

As described in detail above, the aluminum alloy sheet of the present invention is an aluminum alloy sheet excellent in both press workability and spot weldability, and is suitable for automobile bodies and the like that are required to be lightweight. Can be used particularly preferably.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoki Nishiyama, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture Technical Research Institute, Kawasaki Steel Co., Ltd. Town No. 1 Kawasaki Steel Co., Ltd. Technical Research Institute (72) Inventor Koichi Hashiguchi No. 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Co., Ltd. Technical Research Center (72) Inventor Yoshimoto Matsumoto Chiba Chiba 1 Kawasaki-cho, Chuo-ku, Kawasaki Steel Co., Ltd. Technical Research Institute (72) Inventor Motohiro Namba 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Inside Furukawa Electric Co., Ltd. (72) Inventor Tadashi Kurihara Akira 2-6-1 Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (3)

[Claims] 1. A surface of an aluminum alloy original plate has a chromate coating of 1.0 to 50.0 mg / m ^{2 in} terms of metal Cr as a first layer, and an organic lubricant of 60% by weight as a second layer on the chromate coating. An aluminum alloy plate excellent in press workability and spot weldability, which is provided with an organic resin coating containing more than 95% by weight as a dry film thickness of 0.02 to 0.90 μm. 2. The aluminum alloy plate having excellent press workability and spot weldability according to claim 1, wherein the oxide film on the surface of the aluminum alloy plate has a thickness of 100 Å or less. 3. The organic lubricant has an average molecular weight of 900 to
It is a high-density polyethylene having a density of 15,000 and a density of 0.93 or more, and the aluminum alloy sheet excellent in press workability and spot weldability according to claim 1 or 2.