JPH05195134A - Aluminum alloy sheet excellent in formability - Google Patents

Abstract

PURPOSE:To obtain an Al alloy sheet excellent in formability by specifying the roughness, protrusion height and recess depth of the surface of the Al alloy sheet having specified Mg content and elongation. CONSTITUTION:This Al alloy sheet contains 4-10wt.% Mg and has >=25%, preferably >=30%, elongation, and the 10-point mean roughness Rz of the surface is controlled to 2 to 20mum. The regularity parameter Sp shown by equation 2 and indicating the regularity of the protrusion height of the surface is controlled to <=0.30, and the regularity parameter Sv shown by equation 4 and indicating the regularity of the recess depth is controlled to <=0.30. The surface shape is formed by using a roll applied with a specified dull finishing when the sheet is rolled before and after annealing. An Fe-base alloy plating layer or a solid lubricant layer is provided, as required, on at least one side of the sheet at 1-20g/m<2>. Consequently, an Al alloy sheet which is not strained and cracked when press-formed is obtained.

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 global environment protection in connection with the problem of global warming caused by 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 the plate thickness by increasing the tensile strength of steel materials has been studied. However, there is a limit to reducing the thickness of the plate from the viewpoint of measures against automobile noise and rigidity of the vehicle body, and in order to further reduce the weight of the vehicle body, it is necessary to consider the use of a light metal instead of the steel material. Under these circumstances, aluminum or aluminum alloy plates have been spotlighted, and in recent years, they have been widely used as materials for automobiles.

However, the aluminum alloy sheet has many problems in its application to the automobile body because it has different characteristics from the steel plate which is the main constituent material of the automobile body in the past. 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.
Therefore, in order to improve the formability of this aluminum alloy sheet, it has been attempted to improve the material such as 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
Along with the material such as elongation, it depends on the quality of the sliding characteristics 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. Also, A
Since the l-alloy plate has a small local elongation, there is a problem that if strain locally occurs during forming, cracking easily occurs.

Therefore, an object of the present invention is excellent in moldability, and in particular, it is possible to prevent the occurrence of local strain which causes non-uniform deformation at the time of press molding and suppress cracking, so that it is a lightweight material for automobiles. It is to provide an aluminum alloy plate suitable as.

[0006]

Means for Solving the Problems As a result of various studies on the cause of localized strain in the deformation of the Al alloy plate during press forming, the inventors found that the surface of the Al alloy plate with a small local elongation is It was found that a minute change in plate thickness corresponding to the unevenness causes nonuniform deformation. Therefore,
Laboratory-wise, the ten-point average roughness (Rz) is set to 15 μm, and the regularity parameter (S _V ) indicating the regularity of the depth of the concave portion by laser dull, shot dull, etc., and the regularity of the peak height of the convex portion are shown. Various samples with different order parameter ( _SP ) were prepared. 100mmφ using this sample
The limit forming height LDHo was measured when the overhang forming was performed using the above ball head punch, and the results are shown in FIG. Also,
FIG. 1 also shows the case where the surface is plated with Fe—Zn at 5 g / m ² . As a result, both Sv and Sp
It has been found that LDHo is improved with the decrease of The present invention was made based on this finding.

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, and the ten-point average roughness Rz on the surface is 2 μm ≦ Rz ≦. 20 μm, and the regularity parameter S _P indicating the regularity of the peak heights of the convex portions represented by the following formula (2) is S _P ≦ 0.30, and the following formula (4)
It provides an aluminum alloy plate having good formability, in which the order parameter S _V , which indicates the regularity of the depth of the recesses, is S _V ≦ 0.30.

[0008]

[Equation 2]

An Fe-based plating layer or a solid lubricant layer is formed on at least one surface of the aluminum alloy plate in an amount of 1 to 20 g / m.
Having ² is preferable.

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 sheet 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 molding is insufficient and the effect of uniformizing the strain by controlling the surface roughness cannot be reflected in the improvement of the moldability. ..

The ten-point average roughness Rz on the surface of the Al alloy plate of the present invention is 2 μm ≦ Rz ≦ 20 μm, preferably 10 μm ≦ Rz ≦ 15 μm. If Rz is less than 2 μm, the amount of oil retained is insufficient and mold galling may occur during molding. When it exceeds 20 μm, not only the retained oil does not effectively contribute to the improvement of the slidability, but also the strain during molding is localized early and the fracture may be accelerated. Here, in the present invention, the ten-point average roughness Rz means JIS.
It is a value based on the method specified in B 0610, and refers to an average roughness based on the top 5th peak and the bottom 5th valley bottom. The ten-point average roughness Rz is measured with a two-dimensional roughness meter, but it can also be measured with a three-dimensional roughness meter.

Further, the regularity parameter S _P represented by the above formula (2) showing the regularity of the convex peak height Pi on the surface of the Al alloy plate of the present invention is S _P ≦ 0.30,
Preferably, 0.05 ≦ S _P ≦ 0.15. When the order parameter S _P exceeds 0.30, there is a locally thick portion, which hinders uniform strain during molding and may cause strain to concentrate early. Here, in the present invention, the center plane peak height Pi of the protrusion means the height of the protrusion from the center face in the surface unevenness profile measured by a three-dimensional roughness meter. Further, the center plane is a plane in which the volume of the concave portion and the convex portion are equal. N in the formula (1) is an integer of 2 or more, and is the number of convex portions on the measurement surface.

Further, the order parameter S _V represented by the above formula (4), which shows the regularity of the depth of the recesses on the surface of the Al alloy plate of the present invention, is S _V ≦ 0.30, and preferably 0.05 ≦ S _V ≦ 0.15. If the order parameter S _V exceeds 0.30, there is a portion where the plate thickness is locally reduced, and there is a risk that strain will concentrate at this portion early during molding. Here, in the present invention, the central surface valley depth Vi of the concave portion refers to the concave depth from the central surface in the surface unevenness profile measured by a three-dimensional roughness meter. Further, m in the formula (3) is an integer of 2 or more.

As described above, the Al alloy sheet of the present invention is
The point average roughness Rz is in a specific range, and the surface projection
Parameter indicating the regularity of the center plane peak height Pi of
Ta S _P, And the regularity of the central surface valley depth Vi of the surface recesses
Degree of regularity parameter S_VSurface roughness where is in a specific range
It has a shape and has such a surface roughness shape.
By doing so, the height and valley of the peaks (projections) on the surface
Since the depth of the (recess) is uniform, this unevenness on the surface is uniform.
As a result, minute changes in plate thickness are suppressed. for that reason,
Distortion is not locally concentrated during molding, resulting in uniform deformation.
It is considered that cracking due to local elongation is suppressed.

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 to 10
An Al alloy plate having a weight percentage of 25% or more and an elongation of 25% or more is laser-cut in a step corresponding to the ten-point average roughness Rz, the order parameter S _P , and the order parameter S _V in any step before and after annealing. Al having a predetermined surface morphology by rolling with a roll having a surface layer formed by dull
It can be carried out according to a method of producing an alloy plate or a method other than laser dull, in which the roll is dulled, and which can satisfy the requirements for limiting the surface roughness of the present invention.

Further, the Al alloy plate of the present invention preferably has an Fe-based plating layer or a solid lubricant layer on at least one surface thereof. More preferably, it is preferable to have the Fe-based plating layer or the solid lubricant layer on the surface in contact with the punch surface because the strain is not localized.

In the present invention, Fe-based plating means Fe
Fe-based alloy plating such as plating, Fe-P plating, Fe-C plating, Fe-B plating, Fe-Zn plating, and Fe-Ni plating is collectively referred to.

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. It may cause starburst and adversely affect the subsequent painting process.

As a method for 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.

[0024]

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 the cold rolling process or the skin pass process after annealing of this Al alloy plate, roll processing is performed using various rolls having different ten-point average roughnesses Rz, S _P and S _V on the surface, as shown in Table 1. , different Rz, having S _P and S _V, 1.0
An Al alloy plate having a width of 1000 mm was manufactured. Obtained A
Mechanical properties of alloy sheet (elongation, YP (kgf / m
m ² ), TS (kgf / mm ² )) and press formability were measured or evaluated according to the following methods. The results are shown in Table 1.

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 (LDH ₀ measuring method) A ball head punch having a punch diameter of 100 mmφ (dp) was used.
1.0 x 160 x 160 Al alloy plate, drawing speed 1 m
LDH with m / s and wrinkle pressing pressure of 10 tonf and normal rust preventive oil as lubricating lubricant
₀ was measured and used as an index of press formability.

[0028]

[Table 1]

[0029]

The Al alloy sheet of the present invention has excellent formability,
In particular, it is possible to prevent the occurrence of local strain that causes non-uniform deformation during press molding and obtain a molded product without cracks. Therefore, the Al alloy plate of the present invention is suitable as a lightweight material for automobiles.

[Brief description of drawings]

FIG. 1 shows S _P and S _V and (LD
Diagram showing the relationship between the H _0).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Hira 1 Kawasaki-cho, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Technical Research Headquarters (72) Inventor Yoshihiro Matsumoto 1 Kawasaki-cho, Chiba-shi Kawasaki (72) Inventor Koichi Hashiguchi, 1st Kawasaki-cho, Chiba-shi, Chiba Steel Technology Co. Ltd. (72) Inventor, Toshiyuki Kato 1st Kawasaki-cho, Chiba-shi Kawasaki Inside Steel Engineering Co., Ltd.

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, a ten-point average roughness Rz on the surface of 2 μm ≦ Rz ≦ 20 μm, and the following formula (2): The regularity parameter S _P indicating the regularity of the peak heights of the convex portions is S _P ≦ 0.30, and the regularity parameter S _V indicating the regularity of the depth of the concave portions represented by the following formula (4). Is an aluminum alloy plate having good formability, with S _V ≦ 0.30. [Equation 1] 2. An aluminum alloy plate having a good formability, having an Fe-based alloy plating layer or a solid lubricant layer of 1 to 20 g / m ^{2 on} at least one surface of the aluminum alloy plate of claim 1.