JPS62278245A - Aluminum-alloy rolled plate for forming and its production - Google Patents

Abstract

PURPOSE:To manufacture an Al-alloy rolled plate for forming combining superior formability with high strength, by applying specific heat treatments to an Al-alloy ingot having a specific composition consisting of Si, Mg, Fe, and Al and the hot-rolled plate of the above. CONSTITUTION:The Al-alloy ingot consisting of, by weight, 0.4-2.5% Si, 0.1-0.4% (in case of 0.4-1.0% Si) or 0.1-0.25% (in case of 1.0-2.5% Si) Mg, 0.05-0.4% Fe, and the balance Al with inevitable impurities and further containing, if necessary, one or more kinds among 0.05-0.6% Mn, 0.05-0.3% Cr, and 0.05-0.15% Zr or/and 0.10-1.5% Cu is subjected to homogenizing treatment at 450-580 deg.C for 1-48hr. Subsequently, the ingot is rolled to the desired thickness and held at 500-580 deg.C for >=5sec. Succeedingly, the plate is rapidly cooled and then aged at room temp. In this way, the Al-alloy rolled plate excellent in bulge formability and bendability, free from occurrence of Luder's marks, and keeping strength even after subjected to baking finish can be obtained.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention Field of Industrial Application This invention relates to a rolled aluminum alloy plate for forming processing and a method for manufacturing the same. The present invention relates to a rolled aluminum alloy plate suitable for forming, such as automobile bodies, and a method for manufacturing the same.

BACKGROUND OF THE INVENTION Conventionally, cold-rolled steel sheets have been mainly used for body sheets of automobile bodies, but recently, due to the demand for lighter vehicle bodies, consideration has been given to using rolled aluminum alloy sheets. Since body sheets for automobile bodies are used after being press-formed, they are required to have excellent molding properties, in particular, to have excellent elongation and extrusion properties, and to avoid the appearance of Lüders marks during the molding process. Moreover, it is also essential to have high strength, and in particular, since baking coating is applied, it is required that the strength after baking coating is high.

By the way, there have been various types of aluminum alloy plates used for forming products that require strength, but the main ones can be classified as follows depending on the alloy composition.

(A) 5052 alloy, which is a non-heat treatment type Al-MCJ alloy (Mg 2.2~2.8%, Cr0.15~0°35
%, balance A! and unavoidable impurities) or the same <5182 alloy (MnO, 20-0.50%, MCJ
4.0 to 5.0%, the balance being Al and unavoidable impurities) O material.

(b) Heat treatment type A, 2036 alloy which is a 2-Cu alloy (Cu 2.2-3.0%, MnO, 1-0.4%, M
T4 treated material (Cl 0.3-0.6%, balance Al and unavoidable impurities).

(c) Tl material of heat treatment type A1-MQ-Zn-Cu alloy. Examples of this type of aluminum alloy include the alloy of JP-A No. 52-141409 and the alloy of JP-A No. 53-10391.
There are alloys such as No. 4 alloy or the alloy of JP-A No. 57-98648.

(d) 600, which is a heat treatment type Al-Mq-s r-based alloy
9 alloy (MgO, 4-0.8%, S: 0.6-1.0%
, Qu O, 15-0.6%, Mn 0.2-0.8%,
The remaining Af and unavoidable impurities) of the T4 treated material and the same <
6010 alloy (MgO, 6~1.0%, Si0.8~1
．． 2%, CuO, 15~0.8%, MrlO, 2~
0.8% to the remainder! and unavoidable impurities) T4 treated material.

However, with these conventional aluminum alloys, it has been difficult to fully satisfy all of the above-mentioned characteristics required for body sheets of automobile bodies.

That is, the alloy (a) has insufficient strength, has the problem of easily generating Lüders marks during molding, and further has the problem of reduced strength due to the paint baking process. In addition, the alloy described above has poor formability and also has the problem of reduced strength due to the paint baking process. Furthermore, the alloy (c) has a problem in that the formability, especially the bendability, is not sufficient, and the strength decreases during the paint baking process. In addition, for the alloy of the (2) system, for example, 6009
The alloy had insufficient strength, while the 6010 alloy had insufficient elongation and bendability.

Problems to be Solved by the Invention As mentioned above, conventional aluminum alloys have the characteristics required for automobile body sheets, namely excellent moldability, particularly excellent elongation and stretch formability, and the Luders mark. There is no occurrence of
In particular, it has been difficult to fully satisfy requirements such as high strength after baking the paint.

In order to solve the above-mentioned problems, the present inventors have already filed Japanese Patent Application Nos. 60-43367 and 60-43368.
In this issue, we propose an aluminum alloy rolled sheet for forming work that has an excellent balance between strength and formability and does not generate Duders marks, and a method for manufacturing the same.

On the other hand, the rigidity of an automobile body is largely determined by the elastic modulus of the material, so A1 has a lower elastic modulus than cold-rolled steel sheets.
When alloy materials are used in automobile bodies, even if the strength of the material is increased, there are some areas where there is a limit to the reduction in plate thickness. If the yield strength is secured to be about 15 kg/7 or more, it is more advantageous to further improve the formability than to further increase the strength when applying it to the complex design of automobile bodies. In other words, if strength can be secured to the extent that it can be made even though it cannot be obtained in the case of the two proposals mentioned above, it will be possible to cope with the increasing complexity of automobile body design by further improving moldability rather than strength. It is thought that it will be possible to expand the field of application. Of course, even in that case, it is of course necessary that no Lüders marks occur during the molding process.

This invention was made in view of the above circumstances, and has excellent moldability, especially stretchability, bendability, and elongation, and has a yield strength of at least 15 to 3/3 after molding and baking coating.
The object of the present invention is to provide an aluminum alloy rolled sheet containing at least m, rA and which does not generate Lueders during forming hO processing, and a method for manufacturing the same.

Means for Solving the Problems The aluminum alloy rolled plate for forming of the first invention contains Si in a range of 0.4 to 2.5% by weight, and contains Mg and 0.4% Si. 0 within the range of 1.0% or more
．． 1% or more and less than 0.4%, Si in the range of 1.0% or more and 2.5% or less contains 0.1% or more and less than 0.25%, further contains FeO, 05 to 0.4%, and the remainder is characterized by consisting of Al and inevitable impurities. Here, the range of Si and Mg contents is from point A (0.4%Si, 0.4%Mg) to point B in the attached Figure 1, which represents Si content - Mg content in two-dimensional coordinates. (
1.0%Si, 0.4%Mc+), point C (1.0%Si
, 0.25%MG>, point D (2°5%Si, 0.25%
Mg), point E (2,5%3i', 0.1%Mg),
It is drawn in the hatched area surrounded by point F (0.4%S i , 0.1%Mg>).

However, among the boundaries of this area, the straight part is S i ,
1VtQ content range, and the broken line portion is excluded from the Si1Mq content range.

Moreover, the aluminum alloy rolled plate for forming processing of the second invention is
In addition to Si, Mc+, and Fe specified in the first invention, MnO, 05 to 0.6%, and Oro, 05 to 0.3%.
, Z r 1 selected from 0.05-0.15%
It is characterized by containing one species or two or more species.

Further, the aluminum alloy rolled plate for forming processing of the third invention is
In addition to Si, Mg, and Fe defined in the first invention, the material is characterized by containing 0.10 to 1.5% of Cu.

Further, the rolled aluminum alloy plate for forming according to the fourth invention contains -MnO, 05 to 0.6%, (
:, r O, 05-0.3%, Zr 0,05-0.1
It is characterized by containing one or more of 5% of the above.

On the other hand, in the method for producing a rolled aluminum alloy plate for forming according to the fifth invention, an aluminum alloy ingot having the composition according to the first invention is heated to 1 to 4
It is characterized by subjecting it to homogenization treatment for 8 hours, then rolling it to the required thickness, holding it at a temperature within the range of 500 to 580 °C for 5 seconds or more, followed by rapid cooling and aging at room temperature. It's something.

The method for manufacturing an aluminum alloy rolled plate for forming according to the sixth invention, the seventh invention, and the eighth invention is based on the aluminum alloy ingot having the composition according to the second invention, the third invention, and the fourth invention, The same homogenization treatment, rolling, and heat treatment as in the invention are performed.

Function First, the reason for limiting the components in the aluminum alloy rolled plate of the present invention will be explained.

Si: Si is effective in coexisting with MC2 to produce MO2Si and imparting strength through precipitation hardening, and at the same time is effective in improving formability, particularly elongation.

If the Si content is 0.4% or less, the strength is insufficient, and the Si content is 2.5%.
If it exceeds this amount, the effect of Si addition will be saturated, and on the contrary, the moldability will tend to decrease. Therefore, Sil, tO, 4% or more2.
It was set within the range of 5% or less.

Mg: As mentioned above, MO coexists with Si and becomes Mg2S.
It is an element that generates i and gives strength, but when Mg is 0
．． If it is less than 1%, the effect cannot be obtained.

On the other hand, although MQ is effective in improving strength, if the amount added is too large, it deteriorates moldability. This formability is also related to the amount of Si. When Si is 0.4% or more and less than 1.0%, M(j
If Si is 0.4% or more, formability decreases, and Si is 1.0% or more.
% or more and less than 2.5%, if Mg is 0.25% or more, the moldability decreases. Therefore, the Mg content is 0.1% in the range of Si 0.4% or more and less than 1.0% in relation to the Si content.
In the range of 1.0% to 2.5%, Si is set to 0.1% to less than 0.125%.

Fe: Fe improves strength through the refinement of crystal grains, but
If it is less than 0.05%, the crystal grains will become coarse, while if it exceeds 0.4%, the formability will deteriorate, so it was set within the range of 0.05 to 0.4%.

The remainder of the above components may be Al and inevitable impurities in the case of the aluminum alloy rolled plate of the first invention.

On the other hand, in the case of the aluminum alloy rolled sheets of the second invention and the fourth invention, in addition to the above-mentioned components, Mn, Cr, z
It shall contain one or more of r.

All of these elements make recrystallized grains finer, stabilize the structure, and improve formability. Mn is 0
．． Less than 0.05%, Crtfio less than 05%, Zr 0.
If Mn is less than 0.05%, the above effect cannot be obtained; on the other hand, if Mn is less than 0.05%,
If it exceeds 6%, the formability decreases, and Cr is 0.3%, Zr
If it exceeds 0.15%, giant intermetallic compounds are formed and the elongation decreases, so Mn is 0.05 to 0.6%, Qr
was within the range of 0.05 to 0.3%, and Zr was within the range of 0.05 to 0.15%.

Furthermore, in the case of the third invention and the fourth invention, Cu is contained. Addition of CU is effective in improving strength and formability, especially bendability, but if it is less than o,io%, the effect cannot be sufficiently obtained, while if it exceeds 1.5%, strength will improve. However, since moldability deteriorates, the Cu content was set within the range of 0.10 to 1.5%.

6 In ordinary aluminum alloys, trace amounts of T1 or T1 and B are sometimes added to refine the ingot crystal grains, and the rolled aluminum alloy plate of the present invention also contains trace amounts of Tr, S, T1 and B. It may contain B. However, when adding Ti, the effect cannot be obtained if the amount is less than 0.15%, and if it is more than 0.15%, the primary crystal T!
Since Ai'3 crystallizes and impedes formability, Ti is 0.
It is preferably within the range of 0.01 to 0.15%. Also, when adding B together with Ti, there is no effect if it is less than 1 pI), and if it exceeds 500 ppm, Ti
Since coarse particles of 82 are mixed in and impair the moldability, B is 1.
It is preferably within the range of ~500 ppm.

As shown in the examples below, the aluminum alloy rolled sheet with the above-mentioned composition has excellent formability such as elongation, stretchability, and bendability, does not generate Luders marks during forming, and has excellent strength. Also make the proof stress 15'j
/7 or more can be obtained. In particular, not only is there no decrease in strength in the baking process after forming 7JO, but the strength increases in the painting baking process, and as a result, the baking-painted molded product with a yield strength of 15'J/7 or more can be reliably produced. It becomes possible to obtain.

Next, the fifth to eighth inventions of the present application, that is, the method for manufacturing an aluminum alloy rolled plate, will be explained together with the reasons for limiting each process condition.

First, an aluminum alloy ingot having the composition defined in the first to fourth inventions as described above is prepared by a continuous casting method, a semi-continuous casting method, or an ingot forming method in accordance with a conventional method.

Next, the ingot is subjected to a homogenization treatment to improve formability and to make the crystal grains fine and uniform. If the heating temperature for this homogenization treatment is less than 450°C, the effect will not be sufficiently obtained, while if it exceeds 580°C, there is a risk of eutectic melting. Moreover, if the heating time for homogenization treatment is less than 1 hour, there is no effect, whereas if the heating time is longer than 48 hours, the effect of homogenization treatment will not increase any further, and the cost will increase unnecessarily. Therefore, the homogenization process is 45
The test was carried out in a temperature range of 0 to 580''C for 1 to 4 hours.

Note that this homogenization treatment may also be performed as a heat treatment prior to hot rolling.

The ingot after the homogenization treatment is rolled according to a conventional method to obtain the required thickness. This rolling may be performed only by hot rolling, or may be a combination of hot rolling and cold rolling.

After rolling, the plate is subjected to solution treatment and rapidly cooled (quenched). If the solution treatment temperature is less than 500℃, the solution treatment will be insufficient and sufficient strength will not be obtained;
If the temperature exceeds this temperature, there is a risk of eutectic melting, so the solution treatment temperature was set at 500 to 580°C. Further, if the holding time at the solution treatment temperature is less than 5 seconds, the solution treatment may not be completed, so it is necessary to hold the temperature for 5 seconds or more, but preferably for 30 seconds or more. Rapid cooling m (quenching) after solution treatment temperature maintenance is sufficient if the cooling rate is at least forced air cooling, specifically 500°C.
A cooling rate of /man or more is appropriate. Although water quenching is appropriate from the standpoint of cooling rate alone, forced air cooling allows quenching without distortion. Although the rate of heating up to the solution treatment temperature is not particularly limited, rapid heating is preferable in order to make the crystal grains finer, and therefore it is preferable to use a rapid continuous heat treatment furnace.

After performing the solution treatment and quenching as described above, aging may be performed at room temperature according to a conventional method.

In order to actually use the aluminum alloy rolled sheet obtained in this way, it is usual to perform forming processing such as press working, but as already mentioned, it has good formability and the Lüders mark. Since there is no occurrence of defects, there is extremely little possibility that defective products will be produced during molding, resulting in high yield and good productivity. Further, when baking is performed after molding, the coating is usually baked by heating at about 150 to 250° C., although this varies depending on the coating. In this paint baking process, as already mentioned, the strength is further increased, and finally a high strength baked painted molded product can be obtained.

Examples [Example 1] Inventive alloys with alloy numbers 1 to 6 and comparative alloys with alloy numbers 7 to 15 having the compositions shown in Table 1 were melted and semi-continuously cast according to a conventional method. The obtained ingots were subjected to the homogenization treatment shown in Table 2. Next, after hot rolling to a thickness of 4 mm, cold rolling to a thickness of 1.0 mm, and a second
Solution treatment or final annealing as shown in the final heat treatment column in the table was performed, and then the specimens were allowed to stand at room temperature for two weeks to age at room temperature. Table 3 shows the results of examining the mechanical properties and moldability after aging at room temperature.

In addition, in order to investigate the change in strength due to the paint baking process after forming, the plate after room temperature aging was subjected to 5% cold working or 10% cold working corresponding to the forming process, and then paint baking (baking). Heat treatment at 200°C for 1 hour corresponding to We investigated the strength of The results are shown in Table 4.

In Table 3, for the comprehensive evaluation of moldability, those with Erichsen fa (Er) of 9.5 or more, bending (180' bending radius) of 0.5 or less, and elongation of 30% or more are marked with an O mark. However, if any one of these was not satisfied, it was marked with an "X" as defective. In addition, as a comprehensive evaluation of strength in Table 4, the strength after baking equivalent treatment (strength after heating for 200'' cxi hours) is 15 K'j / 0.2% proof stress.
Items that may be less than - are marked with an X, and other items are marked with an ○.

As is clear from Table 3, all of the alloys 1 to 6 of the present invention have excellent stretchability and bendability, and no Lüders marks occur, indicating that they have excellent moldability. Furthermore, from Table 4, it is clear that the strength of the alloys of the present invention is improved in the baking step after forming, and baked-painted molded products having a yield strength of 15 kM or more are finally obtained.

[Example 2] Inventive alloys 1 to 6 in Table 1 were subjected to semi-continuous casting, homogenization treatment, hot rolling, and cold rolling in the same manner as in Example 1 to obtain cold rolled sheets with a thickness of 1.0 mm. Obtained. For the cold-rolled plate,
Solution treatment - as quenching, rapidly heated to 540 °C for 6
After holding for 0 seconds, forced air cooling was performed at a cooling rate of 1200° C./1200° C. Table 5 shows the results of examining the mechanical properties and moldability after being kept at room temperature for two weeks and aging at room temperature.

From Table 5, it is clear that in the case of the alloy of the present invention, excellent mechanical properties and moldability can be obtained even when the solution treatment is performed by forced air cooling.

Table 1: Chemical composition of the alloy (wt%) Table 2: Heat treatment conditions Table 3: Mechanical property values, moldability Table 5: Mechanical property values, moldability (Example 2) Effects of the invention As is clear from the above examples, the molding 7J of this invention
[Rolled aluminum alloy plates for I-engineering have excellent formability, such as excellent stretchability and bendability, and no Lüders marks, and the strength after baking and coating after forming is even higher than the yield strength. Therefore, it is particularly suitable for use in high-strength molded products such as automobile body sheets that are molded into complex shapes and subjected to baking coating. The aluminum alloy rolled plate of this invention contains Si and M, which are most widely used in ordinary rolled plates, extruded materials, castings, etc., as the main elements.
Since it only contains g, it is easy to use scraps of other alloys, and conversely, it is also easy to use scraps of the rolled plate of this invention for other alloys and other uses. , it has good scrap disposal properties and is economically advantageous.

The aluminum alloy rolled sheet of the present invention is ideal for body sheets of automobile bodies as mentioned above, but it can also be used for other molded products, such as automobile parts such as wheels, oil tanks, air cleaners, etc. Of course, it can also exhibit excellent performance when used in caps, blinds, aluminum cans, household utensils, instrument covers, chassis of electrical equipment, etc.

[Brief explanation of the drawing]

FIG. 1 is a coordinate diagram showing the content range of s; and Mg in the present invention.

Claims (8)

[Claims] (1) Contains Si in the range of 0.4 to 2.5% by weight, and Mg is 0.1% to 0.4% in the range of Si 0.4% to less than 1.0%. %, Si in the range of 1.0% to 2.5% contains 0.1% to less than 0.25%, further contains 0.05 to 0.4% of Fe, and the balance is Al and unavoidable impurities. An aluminum alloy rolled plate for forming processing, characterized by the following: (2) Contains Si in the range of 0.4 to 2.5% by weight, and Mg is 0.1% to 0.4% in the range of Si 0.4% to less than 1.0%. %, Si in the range of 1.0% to 2.5% is 0.1% to less than 0.25%, further contains Fe 0.05 to 0.4%, and Mn 0.05 to 0. 6%, Cr0.05-0.3
%, Zr in an amount of 0.05 to 0.15%, and the remainder being Al and unavoidable impurities. (3) Contains Si in the range of 0.4 to 2.5% by weight, and Mg in the range of 0.4% to 1.0% Si, 0.1% to 0.4% by weight. %, Si in the range of 1.0% to 2.5% contains 0.1% to less than 0.25%, and further Cu0.10 to 1.5%, Fe0.05
An aluminum alloy rolled sheet for forming processing, characterized in that the aluminum alloy contains up to 0.4%, with the remainder consisting of Al and unavoidable impurities. (4) Contains Si in the range of 0.4 to 2.5% by weight, and Mg in the range of 0.4% to 1.0% Si, 0.1% to 0.4% by weight. %, Si in the range of 1.0% to 2.5% contains 0.1% to less than 0.25%, and further Cu0.10 to 1.5%, Fe0.05
~0.4% and Mn0.05~0.6
%, Cr0.05-0.3%, Zr0.05-0.15
An aluminum alloy rolled sheet for forming processing, characterized in that the aluminum alloy contains one or more selected from the group consisting of Al and unavoidable impurities. (5) Contains Si in the range of 0.4 to 2.5% by weight, and Mg is 0.1% to 0.4% in the range of Si 0.4% to less than 1.0%. %, Si in the range of 1.0% to 2.5% contains 0.1% to less than 0.25%, further contains 0.05 to 0.4% of Fe, and the balance is Al and unavoidable impurities. 1 to 4 at a temperature within the range of 450 to 580℃ for an aluminum alloy ingot consisting of
It is characterized by subjecting it to homogenization treatment for 8 hours, then rolling it to the required thickness, holding it at a temperature within the range of 500 to 580°C for 5 seconds or more, followed by rapid cooling and aging at room temperature. A method of manufacturing an aluminum alloy rolled plate for forming processing. (6) Contains Si in the range of 0.4 to 2.5% by weight, and Mg in the range of 0.4% to 1.0% Si, 0.1% to 0.4% by weight. %, Si in the range of 1.0% to 2.5% is 0.1% to less than 0.25%, further contains Fe 0.05 to 0.4%, and Mn 0.05 to 0. 6%, Cr0.05-0.3
%, Zr of 0.05 to 0.15%, and the balance is Al and unavoidable impurities.
After homogenizing at a temperature within the range of 580°C for 1 to 48 hours and then rolling to the required thickness, 500 to 580°C
1. A method for producing a rolled aluminum alloy sheet for forming processing, which comprises holding the sheet at a temperature within the range of 50° C. for 5 seconds or more, followed by rapid cooling and aging at room temperature. (7) Contains Si in the range of 0.4 to 2.5% by weight, and Mg in the range of 0.4% to 1.0% Si, 0.1% to 0.4% by weight. %, Si in the range of 1.0% to 2.5% contains 0.1% to less than 0.25%, and further Cu0.10 to 1.5%, Fe0.05
450-580 for an aluminum alloy ingot containing ~0.4% and the remainder consisting of Al and inevitable impurities.
After homogenizing at a temperature in the range of 500 to 580 °C for 1 to 48 hours, then rolling to the required thickness, holding at a temperature in the range of 500 to 580 °C for 5 seconds or more, followed by rapid cooling, A method for producing a rolled aluminum alloy plate for forming processing, characterized by aging at room temperature. (8) Contains Si in the range of 0.4 to 2.5% by weight, and Mg is 0.1% or more and 0.4% in the range of Si 0.4% or more and less than 1.0%. %, Si in the range of 1.0% to 2.5% contains 0.1% to less than 0.25%, and further Cu0.10 to 1.5%, Fe0.05
~0.4% and Mn0.05~0.6
%, Cr0.05-0.3%, Zr0.05-0.15
%, and the remainder consists of Al and unavoidable impurities, at a temperature within the range of 450 to 580°C.
The material is homogenized for ~48 hours, then rolled to the required thickness, held at a temperature within the range of 500 to 580°C for 5 seconds or more, then rapidly cooled, and aged at room temperature. A method of manufacturing an aluminum alloy rolled plate for forming processing.