JPH11236639A - Aluminum-magnesium-silicon series aluminum alloy sheet for forming excellent in surface property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an Al-Mg-Si series aluminum alloy for forming in which ridging marks are suppressed. SOLUTION: In an Al-Mg-Si series alloy sheet contg., by weight, 0.2 to 1.0% Mg and 0.2 to 1.5% Si, as to the texture, the orientation distributed density in the Goss orientation is regulated to <=3, the orientation distributed density in the PP orientation is regulated to <=3, and the orientation distributed density in the Brass orientation is regulated to <=3. As the alloy components, one or more kinds among, by weight, <=1.0% Mn, <=0.3% Cr, <=1.0% Fe, <=0.3% Zr, <=0.3% V and 0.1% Ti by 0.01 to 1.5% in total and moreover one or >= two kinds among <=1.0% Cu, <=0.2% Ag, <=1.0% Zn and <=0.2% Sn by 0.01 to 1.5% in total may be contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Al-Mg-Si-based aluminum alloy plate (hereinafter abbreviated as "aluminum") having excellent press formability, particularly excellent surface properties. Suitable for materials such as building materials such as walls, equipment, electrical parts, optical equipment, transportation equipment such as automobiles, railway vehicles and aircraft, and general mechanical parts.
The present invention relates to an l-Mg-Si alloy plate.

[0002]

2. Description of the Related Art Al-Mg alloys have been mainly used as aluminum plates and aluminum alloys having excellent formability. However, they have poor paint bake hardenability and have stretcher strain marks during press molding. As an alternative to this alloy, Al
-Mg-Si based alloys have been attracting attention. Al-Mg-Si alloys have the advantages of being excellent in formability and corrosion resistance at room temperature and of obtaining high strength by aging treatment.

[0003] However, when an Al-Mg-Si alloy sheet material is formed and processed, as described in JP-A-7-228956 and JP-A-8-232052,
The problem is that surface roughness called ridging marks occurs on the surface of the plate material. The ridging mark is a streak-like unevenness newly generated in a direction parallel to the rolling direction when a sheet material is used for forming, and is particularly 90 ° in the rolling direction.
In the case of processing to ゜, for example, pulling processing, ironing processing, deep drawing processing, and overhanging processing, remarkable occurrence occurs. When this ridging mark occurs, the interior, camera case,
Products that require particularly beautiful surfaces, such as automotive outer panels, cannot be used as poor appearance.

Japanese Patent Application Laid-Open Nos. Hei 7-228956 and Hei 8-23205 disclose a method of preventing the formation of lysine marks on an Al-Mg-Si alloy sheet material by using hot rolling conditions and other steps. By controlling the processing conditions strictly and generating crystal grains having a fine and random crystallographic orientation, it is intended to prevent the occurrence of lysine marks. However, these prior arts do not elucidate the configuration of the plate material itself in which lysine marks do not occur, and thus these requirements alone were insufficient for the recent strict requirements for surface quality.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in consideration of the conventional Al-Mg-S
An object of the present invention is to provide an Al-Mg-Si-based aluminum alloy sheet for forming processing in which lysine marks generated in an i-based alloy sheet material are suppressed.

[0006]

Means for Solving the Problems The present inventors have proposed Al-M
In order to suppress the generation of lysine marks in the g-Si alloy sheet material, precise texture control beyond the conventional technology is performed, and the Goss orientation, P
It has been found that it is effective to suppress the generation of the P direction and the Brass direction. That is, the Al-Mg-Si alloy sheet for forming process excellent in surface properties according to the present invention is A
An l-Mg-Si alloy plate, wherein the texture is G
The orientation distribution density of the oss orientation is 3 or less, the location distribution density of the PP orientation is 3 or less, and the orientation distribution density of the Brass orientation is 3
It is characterized by the following.

[0007] When the Al-Mg-Si alloy has the above-mentioned texture, the generation of ridging marks is uniformly suppressed, but the Al-Mg-Si alloy particularly suitable for the present invention is:
This is an Al-Mg-Si alloy containing 0.2 to 1.5% Mg and 0.2 to 1.5% Si. This is because, if necessary, Mn: 1.0 wt% or less, Cr: 0.
3 wt% or less, Fe: 1.0 wt% or less, Zr: 0.3
wt% or less, V: 0.3 wt% or less, Ti: 0.1 wt%
% Or less, and a total of 0.01 to 1.
5 wt%, Cu: 1.0 wt% or less, Ag: 0.2 w
t% or less, Zn: 1.0 wt% or less, Sn: 0.2 wt%
% Or less, and a total of 0.01 to 1.
5 wt%, or a combination of both.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted various studies to elucidate the cause of the formation of lysine marks during conventional aluminum alloy press forming, and as a result, the texture was not sufficiently controlled. It became clear that marks occurred. Here, the texture of the aluminum alloy will be described. In the case of an aluminum alloy, the following textures called Cube orientation, RW orientation, CR orientation, Brass orientation, Goss orientation, PP orientation, C orientation, and S orientation exist. Cube azimuth... {001} <100> RW azimuth ......... {001} <110> CR azimuth ....... {001} <520> Brass azimuth. ｝ <221> Goss direction... {011} <100> PP direction... {011} <122> C direction... {112} <111> S azimuth..., {123} <634> In the present invention, azimuth deviations within ± 10 degrees from these azimuths are basically defined as belonging to the same azimuth factor. . However, ± 8 for Brass direction and PP direction
Orientation deviations within degrees are defined as belonging to the same orientation factor.

[0009] The texture of a normal aluminum alloy is established from these orientation factors, and when these composition ratios change, the plastic anisotropy (described later) of the sheet material changes, and the press formability becomes good or bad. . As a quantitative evaluation method of these orientations, there is an orientation distribution density. This is expressed as a ratio of the intensity of each direction to a random direction, and is obtained by measuring a perfect positive electrode diagram of at least three planes using a normal X-ray diffraction method and then using a crystal orientation distribution function [ See References 1 and 2 below]. Alternatively, electron diffraction, SEM (Sc
anning-Electron-Microscopy) -ECP (Electron-Cha)
nneling-Pattern method, SEM-EBSP (Electron-Ba)
The orientation distribution density can be obtained by using a crystal orientation distribution function based on data measured using the ck-Scattered-Pattern method or the like. Further, since these azimuth distributions change in the thickness direction, they are determined by averaging some points in the thickness direction. Reference 1: edited by Shinichi Nagashima, “Texture” (Maruzen Co., Ltd.) 1984, pp.8-44 Reference 2: Seminar of the Institute of Metals, “Texture” (edited by The Japan Institute of Metals) 1981, pp.3-7

[0010] The present inventors have changed the texture of A
The presence / absence of ridging marks in the l-Mg-Si alloy sheet was examined, and the mechanism of the generation was studied. As a result, Goss orientation, PP orientation, Bra with strong in-plane plastic anisotropy
We found that the ss direction was the culprit of the ridging mark. More specifically, Goss direction, PP direction, Bra
In the ss orientation, the in-plane anisotropy of the r value (Rankford value) is much larger than in other orientations.
In the oss direction, the width direction, and in the PP direction, 20 from the rolling direction.
° Rotation direction, Brass orientation 55 degrees from rolling direction
° Thickness hardly decreases when pulled in the direction of rotation, whereas other orientations cause thickness reduction, and the remarkable difference in the thickness reduction rate is due to the unevenness of the surface (ridging mark). I found that it was the cause.

Therefore, Goss direction, PP direction, Bra
It is effective to reduce the ss azimuth to suppress the ridging mark. In particular, the azimuth distribution density of the Goss azimuth is 3 or less, the azimuth distribution density of the PP azimuth is 3 or less, and Brass.
When the azimuth distribution density of the azimuth is set to 3 or less, ridging marks can be suppressed, and when each azimuth distribution density exceeds this, ridging marks are remarkably generated and the surface quality is deteriorated.
More preferably, the distribution density of the Goss orientation is 2 or less, the distribution density of the PP orientation is 2 or less, and the distribution density of the Brass orientation is 2 or less.

Next, alloy elements of the Al-Mg-Si alloy will be described. (Mg, Si) These elements are important elements that form aggregates (clusters) or intermediate phases of Mg ₂ Si composition called GP zones and contribute to hardening by baking treatment. Further, it serves to improve the work hardening characteristics of the sheet material and to increase the breaking limit during press forming. further,
The Mg ₂ Si stable phase generated during the soaking treatment acts as a preferential nucleation site for the recrystallization orientation, and is an element that has a great influence on the texture formation of the sheet material. If the respective contents of Mg and Si are less than 0.2 wt%, sufficient strength cannot be obtained during the baking treatment, and if each exceeds 1.5 wt%, the curing characteristics deteriorate during baking treatment and coarse compounds are formed. Deterioration of formability as a starting point of destruction is caused, and further, formation of a desired texture is inhibited. More preferably, the content of Mg is 0.8% or less and the content of Si is 1.3% or less.

(Mn, Cr, Fe, Zr, V, Ti) M
n, Cr, Zr, V, and Ti are 4 hours at a high temperature of 530 ° C. or higher.
By performing the homogenizing heat treatment for a long time of r or more, many fine precipitates are formed. The precipitate functions as a preferential nucleation site for the recrystallization orientation and is effective for obtaining a suitable texture. It is also effective in reducing the crystal grain size and raising the limit of forming cracks. Furthermore, Mn and Cr are important elements that contribute to hardening by baking. But M
n, Cr, Zr, V, or Ti is 1.
0 wt%, 0.3 wt%, 0.3 wt%, 0.3 wt
% Or more than 0.1 wt%, the formation of a coarse compound becomes a starting point of destruction, so that the moldability is remarkably deteriorated and the formation of a desired texture is inhibited. Fe is Al
₇ Cu ₂ Fe, Al ₁₂ (Fe, Mn) ₃ Cu ₁₂ , (Fe,
Mn) Crystallized substances such as Al ₆ , α-AlFeSi, β-AlFeSi are formed, and these crystallized substances act as preferential nucleation sites for recrystallization orientation and are effective for obtaining a suitable texture. . However, if the content exceeds 1.0 wt%, formation of a coarse compound becomes a starting point of destruction, so that the formability is remarkably deteriorated and the formation of a desired texture is inhibited. The sum of these elements is 0.0
If the amount is less than 1 wt%, the above-mentioned effect is not obtained. If the amount exceeds 1.5 wt%, a coarse compound is formed, which becomes a starting point of destruction, so that the formability is remarkably deteriorated and the formation of a desired texture is inhibited. Particularly preferred ranges of these elements are as follows: Mn: 0.5 wt% or less, Cr: 0.2 wt%.
%, Fe: 0.5 wt% or less, Zr: 0.2 wt%
Hereinafter, V: 0.2 wt% or less, Ti: 0.05 wt% or less.

(Cu, Ag, Zn, Sn) These elements are elements that promote the formation of an aggregate (cluster) or an intermediate phase having a Mg ₂ Si composition called a GP zone. Further, Cu, Ag, and Zn have a function of accelerating the curing speed at the time of baking treatment, and Sn has a function of suppressing aging at room temperature in a stage before baking and promoting aging at the time of baking. However, the sum of these elements is 0.01
When the content is less than wt%, the above effect is not obtained.
Zn and Sn contents are 1.0 wt% and 0.2 wt%, respectively.
%, 1.0 wt%, 0.2 wt%, or the sum of them exceeds 1.5%, it becomes a starting point of destruction by forming a coarse compound. Inhibits tissue formation. Particularly preferred ranges of these elements are Cu: 0.5 wt% or less, and Ag:
0.1 wt% or less, Zn: 0.5 wt% or less, Sn:
0.1 wt% or less.

Next, preferable manufacturing conditions will be described. After performing normal casting, a homogenizing heat treatment is performed.
When a transition metal such as r, Fe, Zr, or V is added, a large number of fine precipitates can be deposited by performing a homogenizing heat treatment at a high temperature of 530 ° C. or higher for 4 hours or longer. These precipitates are effective for obtaining a suitable texture, and are also effective for reducing the crystal grain size. Next, hot rolling and cold rolling are performed. The hot rolling start temperature exceeds 450 ° C., the hot rolling end temperature exceeds 360 ° C., and the final cold rolling reduction is 85% or less. In some cases, a desired texture can be obtained. In addition,
Annealing may be performed after hot rolling.

What is particularly important for obtaining a desired texture is the texture before the solution treatment, and the Brass orientation from the Goss orientation is important.
When the α-orientation group [see Reference 3 below] to which the <110> axis is parallel to the rolling surface normal up to the ss orientation develops, it may cause the development of the Goss orientation, PP orientation, etc. after the solution treatment. Become. Therefore, it is necessary to suppress the development of the α-orientation group before the solution treatment. The α-orientation group develops during the hot rolling process, or also develops during the cold rolling as the rolling reduction becomes higher. Therefore, in order to suppress the α-orientation group, the α-orientation group at the time of hot rolling is reduced by increasing the hot-rolling end temperature and recrystallizing, or the α-orientation at the time of cold rolling is reduced by reducing the cold rolling rate. It is necessary to reduce or reduce groups. For this purpose, the end temperature during hot rolling is set to 3
It is desirable that the temperature be 60 ° C. or more and the final cold rolling reduction be 85% or less. Further, when hot rolling is started at 450 ° C. or higher, recrystallization tends to occur during rolling, and other orientations than the α-orientation group formed during rolling are formed, and the α-orientation group decreases. As a result, the α-orientation group in the structure before the solution treatment becomes weak, and Goss, Brass, PP after the solution treatment are weakened.
The azimuth is reduced, contributing to the suppression of ridging marks. In addition,
After the completion of hot rolling, recrystallization may be performed by annealing to reduce the α-orientation group in hot rolling. Finally, a solution treatment is performed, but it is desirable to keep the temperature at 530 ° C. or higher. Reference 3: Kunio Ito, "Light Metals", Vol. 43 (1993), No. 5,
P.285-293

[0017]

EXAMPLES (Example 1) Al-0.6% Mg-1.0%
Si alloy (hereinafter referred to as base alloy), Al-0.6%
Mg-1.0% Si-0.1% Mn alloy (hereinafter referred to as Mn-added alloy), Al-0.6% Mg-1.0% Si-
An alloy of three compositions of 0.1% Fe alloy (hereinafter referred to as Fe-added alloy) was cast by a usual method, and subjected to a homogenizing heat treatment at 550 ° C. for 8 hours. Then hot rolling (starting at 500 ° C)
To make a plate having a thickness of 500 mm to 10 to 1.5 mm. The end temperature of the hot rolling was changed, the presence or absence of annealing after hot rolling (referred to as roughening in the present invention), and further, the cold rolling start plate pressure was changed to obtain a 1 mm thick plate by cold rolling. Later, 55
A solution treatment was performed at 0 ° C. for 1 minute.

These plates were subjected to a 15% tensile deformation, and thereafter, the surfaces of the plates were subjected to a coating treatment to determine the presence or absence of lysine marks (the characteristic that the ridging marks became noticeable after coating and were found. Yes). In addition, as an index of formability, an overhang test in a state of plane strain tension was performed to measure a crack limit height. The texture was measured by using a Cu target as a target by a normal X-ray diffraction method, using a tube voltage of 50 kV, a tube current of three surfaces of the plate after solution treatment, a quarter thickness, and a central portion of the plate thickness. The (100), (110), and (111) perfect cathode spot diagrams were measured under the condition of 200 mA, and then the orientation distribution density of each orientation for each sheet thickness portion was calculated using the crystal orientation distribution function, and the average thereof was calculated. And the orientation distribution density of the entire plate was determined. Table 1 shows the results. It is apparent that the material of the present invention suppresses the generation of ridging marks and is excellent in moldability.

[0019]

[Table 1]

Example 2 Mg, Si, M shown in Table 2
Various alloys containing alloying components such as n, Cr, Fe, Zr, V, and Ti are cast by a usual method, and are heated at 550 ° C. for 8 hours.
r was homogenized. Then hot rolling (starting temperature:
500 ° C.), changing the end temperature to 10 to 1.5 m
m-thick plate. Then, a plate having a thickness of 1 mm was formed by cold rolling without roughening, and then subjected to a solution treatment at 550 ° C. for 1 minute.

[0021]

[Table 2]

With respect to these sheet materials, the determination of the occurrence of lysine marks, the measurement of the crack limit height by the overhang test, and the measurement of the texture were performed in the same manner as in Example 1. Table 3 shows the results. It is apparent that the material of the present invention suppresses the generation of ridging marks and is excellent in moldability.

[0023]

[Table 3]

Example 3 Mg, Si, M shown in Table 4
n, Cr, Fe, Zr, V, Ti, Cu, Ag, Zn,
Various alloys containing alloy components such as Sn were cast by a usual method and homogenized at 550 ° C. for 8 hours. Thereafter, hot rolling (start temperature: 500 ° C.) was performed, and the end temperature was changed to obtain a plate having a thickness of 10 to 1.5 mm. And rough
After making a 1mm thick plate by cold rolling without dulling,
A solution treatment was performed at 550 ° C. for 1 minute.

[0025]

[Table 4]

For these sheet materials, the determination of the presence or absence of lysine marks, the measurement of the crack limit height by the overhang test, and the measurement of the texture were performed in the same manner as in Example 1. Table 5 shows the results. It is apparent that the material of the present invention suppresses the generation of ridging marks and is excellent in moldability.

[0027]

[Table 5]

[0028]

According to the present invention, it is possible to obtain an Al-Mg-Si-based aluminum alloy sheet for forming with suppressed lysine marks.

Continued on the front page (72) Inventor Yasuo Takagi 15 Kinugaoka, Moka-shi, Tochigi Pref. Kobe Steel, Ltd.Moka Works

Claims (4)

[Claims] 1. An Al—Mg—Si-based aluminum alloy sheet, wherein the texture has an orientation distribution density of 3 or less in Goss orientation, 3 or less in PP orientation, and B
An Al-Mg-Si-based aluminum alloy sheet for forming excellent in surface properties, wherein the orientation distribution density of the ras orientation is 3 or less. 2. The Al-Mg-Si according to claim 1.
Aluminum alloy plate, wherein the alloy component is M
g: 0.2 to 1.5 wt%, Si: 0.2 to 1.5 wt%
% Of an Al-Mg-Si-based aluminum alloy sheet for forming and processing having excellent surface properties. 3. The Al-Mg-Si according to claim 2,
Aluminum alloy plate, wherein the alloy component is M
n: 1.0 wt% or less, Cr: 0.3 wt% or less, F
e: 1.0 wt% or less, Zr: 0.3 wt% or less, V:
Al-Mg- for forming and processing excellent in surface properties, characterized in that one or two or more of Ti: 0.1 wt% or less are contained in a total of 0.01 to 1.5 wt%.
Si-based aluminum alloy plate. 4. Al-Mg according to claim 2 or 3
A Si-based aluminum alloy plate, wherein one or more of Cu: 1.0 wt% or less, Ag: 0.2 wt% or less, Zn: 1.0 wt% or less, and Sn: 0.2 wt% or less; Two or more kinds in total of 0.01 to 1.5 wt
% Al-Mg-Si based aluminum alloy sheet for forming and processing having excellent surface properties.