JPH05195133A - Aluminum alloy sheet having satisfactory formability - Google Patents

Abstract

PURPOSE:To provide an Al alloy sheet suitable for use as weight reducing stock for an automobile because of satisfactory formability, especially excellent press formability. CONSTITUTION:This Al alloy sheet having satisfactory formability has 4-10wt.% Mg content, >=25% elongation and such surface roughness shape as <=10mum ten-point average roughness Rz and <=100 PPI on one side and >=15mum ten-point average roughness Rz and >=150 PPI on the other side.

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 vehicle noise control and vehicle rigidity, and it is necessary to consider the use of light metal instead of steel material 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 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 elongation property is improved, the formability may not be improved in some cases. That is, the formability of the aluminum alloy plate depends on the quality of sliding properties of the surface as well as the material such as elongation. 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. Further, in press molding, particularly deep drawing, the material undergoes strong work deformation, and therefore further improvement in moldability is desired.

Therefore, an object of the present invention is to provide an aluminum alloy sheet which is suitable as a lightweight material for automobiles because it is excellent in press formability, particularly deep draw formability.

[0006]

The sliding behavior between the plate material and the mold at the time of molding is different between the surface contacting the punch and the surface contacting the die, and different sliding characteristics are required on the front and back sides. I paid attention. That is, it has been noted that the sliding resistance is large on the surface in contact with the punch, whereas if the sliding resistance can be reduced on the surface in contact with the die, good deep drawing formability can be obtained. Therefore, the influence of surface roughness control on the punch surface or the die surface side was investigated using the front and back surface difference dull aluminum plates that were produced in the laboratory. The results are shown in FIGS. 1 and 2. The relationship between LDR and Rz when one surface is set to Rz 12 μm and the parameter of the other surface is changed as shown in FIG. 1 is shown. Further, it can be seen that the LDR is improved as shown in FIG. 2 by controlling the roughness of the punch surface and the die surface.

In other words, in order to solve the above-mentioned 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 a surface roughness profile having a ten-point average roughness on one side. Rz ≦ 10 μm and PPI ≦ 10
0 and the ten-point average roughness Rz ≧ 15 μ on the other surface.
The object is to provide an aluminum alloy plate having a good mouldability, in which m and PPI ≧ 150.

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 plate of the present invention has an elongation of 25.
% Or more, preferably 30% or more, more preferably 35
% Or more. If the elongation is less than 25%, there is a problem that the basic deformability required at the time of molding is insufficient, and even if the sliding property is improved, it cannot be reflected in the improvement of the moldability.

The Al alloy sheet of the present invention has two front and back surfaces having different surface roughness forms. The ten-point average roughness Rz on one surface (hereinafter referred to as “A surface”) is Rz ≦ 10 μm, preferably 5 μm ≦ R.
z ≦ 8 μm. The PPI is PPI ≦ 100, preferably 50 ≦ PPI ≦ 90. The ten-point average roughness Rz on the other surface (hereinafter referred to as “B surface”) is Rz ≧ 15 μm, preferably 15 μm ≦ R.
z ≦ 20 μm. The PPI is PPI ≧ 150, preferably 150 ≦ PPI ≦ 180. Here, in the present invention, the ten-point average roughness Rz means JIS.
A value based on the method specified in B 0610,
It is the average roughness based on the 5th highest peak and the 5th deepest valley bottom. Moreover, PPI means the number of peaks of the convex portion per inch. The ten-point average roughness Rz and PPI are measured by a two-dimensional roughness meter, but can be measured by a three-dimensional roughness meter.

As described above, the Al alloy plate of the present invention is
In the press forming of the Al alloy plate having the surface A and the surface B, which have different surface roughness shapes, for example, when the deep drawing is mainly performed, the surface is If molding is performed with the surface A having a small roughness on the punch side and the surface B having a large surface roughness on the die side, sliding resistance with the punch on the surface A increases. Since the surface roughness is large on the surfaces B and B, the amount of oil retained is large and the sliding resistance is small. As a result, during press forming, particularly deep drawing, the movement of the material on the punch side is prevented and the inflow movement of the material on the die side is made smooth, and the fracture of the Al alloy plate at the shoulder of the punch is suppressed. You can Therefore, the Al alloy sheet of the present invention can exhibit excellent deep drawing formability. Further, in the stretch forming, if the forming process is performed on the B side having a large surface roughness and the punch side, the sliding resistance on the punch face becomes small, and it becomes possible to prevent the localization of strain. It is possible to improve the property.

The Al alloy plate of the present invention is manufactured by melting the Al base metal and alloy components, and the manufactured Mg content is 4-10.
In the process of cold rolling an Al alloy plate of wt%, corresponding to the ten-point average roughness Rz and PPI of the A surface and the B surface,
A method for producing an Al alloy plate having a predetermined surface morphology by rolling with two rolls having surface layers formed by laser dull machining method, shot dull machining method, electric discharge dull machining method, etc. Roughness can be controlled by performing the rolling process of (1) after annealing. The elongation of the Al alloy plate can be 25% or more by controlling the material in the annealing process.

Further, the Al alloy plate of the present invention preferably has a Fe-based plating layer or a solid lubricant layer on at least one surface thereof. More preferably, when a Fe-based plating layer or a solid lubricant layer is provided on the B side, which has a high surface roughness,
It is desirable because it reduces the sliding resistance more effectively, facilitates material movement during molding, and improves moldability.

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 are 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 if the sliding conditions in continuous press molding become severe, mold scuffing may occur. 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 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 the cold rolling process or the skin pass process after annealing of this Al alloy plate, two rolls having different ten-point average roughness Rz and PPI of the surface are used for roll processing, and as shown in Table 1, 1.0 × 1000, having a ten-point average roughness Rz and PPI corresponding to the roll abutted on each
An Al alloy plate having a width of mm was manufactured. Mechanical properties (elongation, YP (kgf / mm ² ), TS (k
gf / 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 (1) Deep Drawing Punch Using a cylindrical punch having a diameter of 33 mmφ (dp), A
l The front side of the alloy plate is the die side and the back side is the punch side,
Stop speed 1 mm / s and blank holding load 500 kg, attempts to deep drawing by using a conventional rust-preventive oil as a lubricating oil, to measure the maximum workpiece diameter Do _max capable deep drawing, the limit drawing ratio from the following formula (LDR) was determined and used as an index of press formability. LDR = Do _max / dp (2) Overhang forming Punch Using a ball head punch with a diameter of 100 mm, the wrinkle holding part has a bead over the entire circumference, and punches the surface of the QAl alloy plate that completely prevents material inflow As the side, the punch speed is 1 mm / sec, and the wrinkle holding load is 10
Ton, using normal rust preventive oil as lubricating oil, attempting overhang molding, limit overhang height LDH until cracking occurs LDH
₀ was measured and used as an index of bulging formability.

[0025]

[Table 1]

[0026]

The Al alloy sheet of the present invention is excellent in press formability, particularly deep drawability, because it has excellent sliding properties and an adequate amount of oil is retained on the sliding surface. is there. 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 a ten-point average roughness Rz and a limit drawing ratio (LDR) in an Al alloy plate which is PPI120 obtained in an experimental example.

FIG. 2 is a diagram showing a relationship between PPI and a limit drawing ratio (LDR) in an Al alloy plate having a ten-point average roughness Rz of 10 μm obtained in an experimental example.

Front Page Continuation (72) Inventor Takaaki Hira 1 Kawasaki-cho, Chiba-shi, Chiba Inside the Technical Research Division, Kawasaki Steel Co., Ltd. (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., Ltd. 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, and a surface roughness profile having a ten-point average roughness Rz ≦ 10 μm on one surface and a PPI.
≦ 100 and ten-point average roughness Rz ≧ on the other surface
An aluminum alloy plate having a good formability of 15 μm and PPI ≧ 150. 2. An Fe-based plating layer or a solid lubricant layer is formed on at least one surface of the aluminum alloy plate of claim 1 in an amount of 1 to 1.
An aluminum alloy plate having a good formability of 20 g / m ² .