JPH05202442A - Aluminum alloy sheet having superior formability - Google Patents

Abstract

PURPOSE:To improve the sliding characteristics of the surface and to improve the press formability of an Al-Mg alloy sheet by specifying the average roughness of surface ruggedness of an Al-Mg alloy sheet, the average value of the spaces between the recessed parts, respectively. CONSTITUTION:In an Al-Mg alloy sheet containing 4-10wt.% Al and having >=25% elongation, the average roughness Ra of the surface ruggedness, the average value Lv of the spaces Lvi between the recessed parts represented by equation I (where n means an integer >=2), and the regularity parameter S showing the regularity of the surface roughness and represented by equation II are regulated so that, at least with respect to one direction of the Al alloy sheet surface, they satisfy the following conditions, respectively: 0.5mum<=Ra<=3.0mum; 50mum<=Lv<=500mum; S<=0.20. Because the Al-Mg alloy sheet having such surface conditions has superior sliding characteristics, press formability affected by sliding characteristics can remarkably be improved. Moreover, the press formability of this Al-Mg alloy sheet can be improved to a greater extent by forming a iron-group plating layer or a solid lubricant layer on the surface by 1-20g/m<2>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy sheet having good formability, and more particularly to an aluminum alloy sheet suitable as a lightweight material for automobiles due to its excellent press formability.

[0002]

_2. Description of the Related Art From the viewpoint of protecting the global environment in connection with the problem of global warming due to effective use of resources and increase of CO _{2 in} the atmosphere, there is an increasing need for automobiles to reduce the weight of their bodies which leads to fuel saving. As a material applicable to this, reduction of plate thickness due to higher strength is being studied for steel materials. However, from the viewpoint of vehicle noise control and vehicle rigidity,
There is a limit to how thin the plate thickness can be, and it is necessary to consider the use of light metals instead of steel materials for further weight reduction of the vehicle body. Under such circumstances, aluminum or an aluminum alloy plate has been spotlighted, and in recent years, it has been widely used as a material for automobiles.

However, the aluminum alloy sheet has many problems in its application to the automobile body because it has different characteristics from the conventional steel sheet, which is the main constituent material of the automobile body, during the forming process. For example, taking press formability as an example, in the typical steel plate SPCC, elongation 45
%, The Rank Ford value (r value) is 1.4, and the limiting aperture value (LDR) reaches 2.15. However, in the typical aluminum alloy sheet A5182, the elongation is 30% and the Rank Ford value is 0.7. The limit aperture value (LDR) is 1.
Only reaches 8. As described above, since the aluminum alloy plate is extremely inferior in press formability, it is conventionally limited to application to a lid member such as a hood and a trunk lid, which is relatively light in forming, except for some special cars. However, it was difficult to apply it to more complicated members that require strong working.
In order to improve the formability of this aluminum alloy plate,
Heretofore, attempts have been made to improve elongation from the viewpoint of alloy composition.

[0004]

However, even if the material such as elongation is improved, the moldability may not be improved in some cases. That is, the formability of the aluminum alloy plate is
It depends on the material such as elongation and the quality of the sliding property of the surface. Therefore, conventionally, in order to improve the sliding characteristics of the surface during molding, methods such as selecting an appropriate lubricating oil and attaching a synthetic resin film such as vinyl to the surface have been proposed. However, the aluminum alloy plate subjected to these methods has problems in handling property and degreasing processability in continuous press molding.

Therefore, an object of the present invention is to provide an aluminum alloy sheet suitable as a lightweight material for automobiles because it has excellent formability that can withstand automated continuous press forming.

[0006]

In order to solve the above problems, the present invention is an aluminum alloy plate having a Mg content of 4 to 10% by weight and an elongation of 25% or more, the average roughness Ra of the surface irregularities, Average value of the interval Lv _i of the recesses expressed by the equation (1)

[Equation 3] And a regularity parameter S, which indicates the regularity of the surface roughness represented by the following formula (2), has the following condition in at least one direction of the surface:

[Equation 4] And an aluminum alloy sheet having good formability, which satisfies the above requirements.

It is preferable that the surface of the aluminum alloy plate has a Fe-based plating layer or a solid lubricant layer of 1 to 20 g / m ² .

The aluminum alloy plate of the present invention having good formability (hereinafter referred to as "Al alloy plate of the present invention") will be described in detail below.

The Al alloy plate of the present invention has a Mg content of 4
10 to 10% by weight, preferably 4 to 7% by weight.
If the Mg content is less than 4% by weight, a sufficient balance between strength and elongation cannot be obtained, so that the effect of controlling the surface irregularities cannot be exhibited. On the other hand, if it exceeds 10% by weight, cracking during the production of the Al alloy sheet, particularly during hot rolling, becomes a problem, and the production becomes difficult.

The Al alloy plate of the present invention has an elongation of 25.
% Or more, preferably 30% or more, more preferably 35
% Or more is required. If the elongation is less than 25%, there is a problem that the basic deformability required at the time of forming is insufficient, and the effect of improving the sliding characteristics cannot be exhibited at the time of forming the obtained Al alloy plate. ..

The average roughness Ra of the surface irregularities of the Al alloy plate of the present invention is 0.5 μm in that the sliding property becomes good because the oil is appropriately retained on the surface during the molding of the Al alloy plate.
≦ Ra ≦ 3.0 μm, preferably 0.7 μm ≦ R
a ≦ 1.8 μm. This average roughness Ra is 0.5 μm
If it is less than the above range, the amount of oil itself is insufficient and mold scuffing may occur during molding. On the other hand, if the average roughness Ra exceeds 3.0 μm, not only the retained oil does not contribute effectively to the sliding characteristics, but also the strain during molding is localized early.
There is a risk of premature rupture.

Further, the surface morphology of the Al alloy plate of the present invention has concave portions at regular intervals, and the regularly arranged concave portions retain oil during molding, so that sliding characteristics are improved. The average value of the intervals Lv _i of the concave portions is good:

[0013]

[Equation 5]

However, the condition represented by the above formula is satisfied in at least one direction of the surface. If the average value of the interval Lv _i between the recesses is less than 50 μm, the recesses are crushed when the sliding surface pressure is low, and the effect of improving the formability is reduced. On the other hand, when it exceeds 500 μm, the oil supply interval to the sliding surface becomes large, which may cause galling due to oil shortage. Here, the interval Lv _i between the concave portions is measured by a three-dimensional roughness meter. Further, the smaller the parameter S indicating the regularity of the intervals of the concave portions on the surface of the Al alloy plate, the higher the regularity of the irregularities on the surface of the Al alloy plate, and in the Al alloy plate of the present invention, S is 0.2 or less. , Preferably 0.10 to 0.15. On the surface where S exceeds 0.2, there is a large variation in the interval between the recesses, and if this variation is large, there is a possibility that there is a wide interval between the recesses that causes galling during molding.

The Al alloy plate of the present invention is manufactured by melting the Al base metal and alloy components, and the Mg content is 4% by weight.
Above, 10% by weight or less of the Al alloy plate, before or after annealing, the surface average roughness Ra, the average value of the interval of the recesses,
According to the regularity parameter S, a roll having a surface on which a roughness pattern is formed by laser dull processing is used to roll at a predetermined rolling reduction to obtain a surface morphology of the roll of Al.
A method of transferring to the surface of an alloy plate, or a method of performing a dulling by a roll using other laser or discharge energy, and a method of satisfying the roughness limiting requirement on the surface of the Al alloy plate of the present invention. Therefore, it can be done.

Further, the Al alloy plate of the present invention preferably has an Fe-based plating layer or a solid lubricant layer on the surface thereof. In the present invention, the Fe-based plating is a general term for Fe-based alloy plating such as Fe plating, Fe-P plating, Fe-C plating, Fe-B plating, Fe-Zn plating, and Fe-Ni plating.

The Fe-based plating layer may be formed by any means such as electroplating, chemical plating, vapor deposition plating or cladding, and the means is not particularly limited.

The solid lubricant layer is a layer made of a water-based or solvent-based resin, a coating, and a solid lubricant such as wax.

The Al alloy plate of the present invention has the above-mentioned F on its surface.
In the case of having an e-based plating layer or a solid lubricant layer, its adhesion amount is usually preferably 1 to ²⁰ g / m ² ,
More preferably, it is 1 to 10 g / m ² . If this adhesion amount is less than 1 g / m ² , the lubrication effect will be insufficient and mold scuffing may occur if the sliding conditions in continuous press molding become severe. If it exceeds 20 g / m ² , the lubricant will peel off. There is a possibility that it may cause starburst and deteriorate the characteristics in the subsequent coating process.

As a method of forming the Fe-based plating layer on the surface of the Al alloy plate of the present invention, there is a method of performing electrochemical plating on the Al alloy plate using a predetermined Fe-based plating bath. Examples of the method for forming the solid lubricant layer on the surface of the Al alloy plate include a method of coating the surface of the Al alloy plate with a solution of the solid lubricant as it is or in a suitable solvent.

[0021]

EXAMPLES The present invention will be described more specifically below based on Examples of the present invention and Comparative Examples.

(Examples and Comparative Examples) Al having the composition shown in Table 1
The alloy raw material was melt | dissolved and the Al alloy plate was manufactured. In a cold rolling process or a skin pass process after annealing of this Al alloy plate, 1.0 × 100 is used by using rolls having different surface roughness regularity parameters S and roll surface roughness Ra.
It was formed into a 0 mm width and then annealed to produce an Al alloy plate. Mechanical properties of the obtained Al alloy plate (elongation, YP, T
S (kgf / mm ² )) and press formability were measured or evaluated according to the following methods. The results are shown in Table 1. Further, the order parameter S is 0.19, and the average value of the intervals of the recesses is different (100 μm (Example), 60
0 μm (comparative example) FIG. 1 shows the measurement results of the average roughness Ra and the friction coefficient of two types of Al alloy plates. Further, FIG. 2 shows the measurement results of S and the friction coefficient in the Al alloy plate in which the average value of the intervals of the recesses is 200 to 300 μm.

Measurement of Mechanical Properties A JIS No. 5 tensile test piece was prepared and subjected to a tensile test to measure tensile property values.

Evaluation of press formability Limit drawing ratio LDR in 33 mmφ cup forming test
Was measured to evaluate the moldability. A usual rust preventive oil was applied to the Al alloy plate used for the test. Friction resistance is measured by
The Al alloy plate is sandwiched from both sides with a compression force (P) of 100 kg,
The Al alloy plate is pulled out as it is, and the pulling force (2
F) was measured, and the friction coefficient (μ) was determined by μ = F / P.
When the frictional resistance is 0.1 or less, there is no fear of breakage during press working, and the press workability is excellent.

[0025]

[Table 1]

[0026]

EFFECT OF THE INVENTION The Al alloy sheet of the present invention has excellent sliding properties, and since an appropriate amount of oil retained on the sliding surface is secured, it has excellent formability, particularly press formability. Therefore, the Al alloy plate of the present invention is suitable as a lightweight material for automobiles.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an average roughness Ra and a friction coefficient in Al alloy plates of Examples and Comparative Examples.

FIG. 2 is a diagram showing a relationship between a regularity parameter S and a friction coefficient in Al alloy plates of Examples and Comparative Examples.

Front page continued (72) Inventor Takaaki Hira 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Yoshihiro Matsumoto 1 Kawasaki-cho, Chiba-shi Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Koichi Hashiguchi 1 Kawasaki-cho, Chiba City, Chiba Prefecture Kawasaki Steel Co., Ltd. Technical Research Division (72) Inventor Toshiyuki Kato 1 Kawasaki-cho, Chiba City Kawasaki Steel Co. Technical Research Division

Claims (2)

[Claims] 1. An aluminum alloy plate having a Mg content of 4 to 10% by weight and an elongation of 25% or more, the average roughness Ra of the surface irregularities, and the average of the intervals Lv _i of the concave portions represented by the following formula (1). Value [Equation 1] And the order parameter S, which indicates the regularity of the surface roughness expressed by the following equation (2), has the following condition for at least one direction of the surface: An aluminum alloy plate that satisfies the requirements and has good formability. 2. A Fe-based plating layer or a solid lubricant layer on the surface of the aluminum alloy plate according to claim 1 in an amount of 1 to 20 g / m 2.
An aluminum alloy plate having ^{2 and} good moldability.