JPH0478710B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a rolled aluminum alloy plate for forming with good corrosion resistance and weldability, and a method for manufacturing the same, and particularly for applications where strength is required and where baking is applied, such as automobiles. The present invention relates to a rolled aluminum alloy plate for forming processing suitable for automobile bodies, etc., and a method for manufacturing the same. [Prior Art] In the past, cold-rolled steel plates were often used for the body sheets of automobile bodies, but recently, due to the demand for lighter vehicle bodies, consideration has been given to using rolled aluminum alloy plates. . Since body sheets for automobile bodies are used after being press-formed, they are required to have excellent molding properties, especially excellent elongation and extrusion properties, and no reuders marks during the molding process. It is also essential to have high strength.
In particular, since baking is applied, high strength is required after baking. 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 system. (a) O material of 5052 alloy (Mg 2.2-2.8%, Cr 0.15-0.35%, remainder Al and unavoidable impurities), which is a non-heat-treated Al-Mg alloy, or 5182
Alloy (Mn0.20~0.50%, Mg1.0~5.0%, balance
Al and inevitable impurities) O material. (b) 2036 alloy, which is a heat-treatable Al-Cu alloy (Cu2.2-3.0%, Mn0.1-0.4%, Mg0.3-0.6%,
(Remaining Al and unavoidable impurities) T4 treated material. (c) T4 treated material of heat-treated Al-Mg-Zn-Cu alloy. Examples of this type of aluminum alloy include the alloy of JP-A-52-141409, the alloy of JP-A-53-141409,
There are alloys such as No. 103914 and JP-A No. 57-98648. Also, Nikkei New Material, 1986, 4-
7, No. 8, pages 63-72, especially Al−4.5Mg−0.38Cu−1.46Zn−0.18Fe− introduced on page 64.
0.09Si is also available. (d) 6009 alloy, which is a heat-treatable Al-Mg-Si alloy (Mg0.4-0.8%, Si0.6-1.0%, Cu0.15-0.6%,
Mn0.2~0.8%, balance Al and unavoidable impurities)
T4 treated material and 6010 alloy (Mg0.6~1.0%,
Si0.8~1.2%, Cu0.15~0.6%, Mn0.2~0.8%,
(Remaining Al and unavoidable impurities) T4 treated material.
According to Japanese Patent Publication No. 59-39499, which proposes these alloys, 0.4-1.2% Si, 0.4-1.1% Mg, 0.05-
0.35%Fe, 0.1~0.6%Cu, plus 0.2~0.8
T4 or T6 with a composition containing at least one of %Mn, 0.1 to 0.3% Cr, and 0.05 to 0.15% Zr
A treated material is disclosed. Furthermore, (A) 1 proposed in Special Publication No. 61-15148
%Si, 0.6%Mg, (B) 1.8%Si, 0.6%Mg, (C) 1.8%
It has a Si, Mg composition surrounded by four points: Si, 0.2%Mg, (D) 1.2%Si, 0.6%Mg, and 0.3% or less Cr,
AC120 standard material containing Mn, Zr, or/and Ti. 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. In other words, alloy (a) has insufficient strength;
Furthermore, there was a problem in that reuders marks were likely to occur during the molding process, and furthermore, there was a problem in that the strength was reduced due to the paint baking process. Furthermore, the alloy (b) had problems of poor formability and reduced strength due to the paint baking process. Furthermore, the alloy (c) had insufficient formability, especially bendability, and also had the problem of reduced strength during the paint baking process. The alloy (d) has features such as being less likely to generate Lyuders' marks and having the same strength as cold-rolled steel sheets due to its bake hardenability, but its elongation, which is a measure of formability, is significantly lower than that of cold-rolled steel sheets. It is known. As mentioned above, aluminum alloys have traditionally had the properties required for automobile body sheets, namely excellent formability, especially excellent elongation and stretch formability, and no occurrence of reuders marks. Furthermore, research and development has been carried out to satisfy all the requirements for strength, especially high strength after paint baking, and excellent corrosion resistance and weldability. [Problems to be solved by the invention] Al-Si-Mg alloys to which the present invention belongs are known, which satisfy the above requirements to a considerable extent, but they are not commonly used in body sheets for automobiles. The performance requirements for aluminum alloy rolled sheets, which are disadvantageous in price than conventional steel sheets, must become stricter, and no aluminum alloy rolled sheet has yet been provided that satisfactorily meets these requirements. Specifically, first, the elongation, which is an index of moldability, is low, and therefore the moldability is still insufficient. In addition, regarding the corrosion resistance of aluminum alloys used for automobile body sheets, it has traditionally been the opinion that, as long as there are no paint defects, the corrosion resistance of aluminum alloys themselves is superior to steel sheets, so there is no problem (Nikkei New Materials cited above). )or,
Corrosion resistance against blistering defects in chrome-plated films
Experiments investigated in the CASS test
39499) etc. However, recently, the requirements for corrosion resistance of rolled aluminum alloy sheets for forming have become more clear, and specific properties that have not been considered in the past are required. i.e.
Unpainted plate corrosion resistance related to the properties of the Al alloy itself,
In addition to pit resistance, it is required that the paint film does not peel off (blister), filiform corrosion, etc. occur after baking painting. However, there is no known aluminum alloy rolled sheet for forming that has such excellent corrosion resistance and also has both strength and formability. Most of the welding of automobile body seats is done by spot welding.
Depending on the location, so-called arc welding using MIG or TIG welding is performed. Since relatively thin plates with a thickness of 2.0 mm or less are generally arc welded, welding is generally difficult, so rolled plates with good weldability are required. This invention was made against the background of the above-mentioned circumstances, and has excellent molding processability, especially elongation and stretchability, no generation of reuders marks during molding, and high strength, especially after molding. An aluminum alloy that does not reduce its strength during the paint baking process, but rather increases its strength through the paint baking process after forming, making it possible to obtain molded products with high strength, and with improved corrosion resistance and weldability. The object of the present invention is to provide a rolled plate and a method for manufacturing the same. [Means for Solving the Problems] The first aspect of the present invention is that Si is more than 1.8% and less than 2.5%,
Contains Mg0.25-1.1% and Fe0.05%-0.5%, and if necessary, Mn0.6% or less, Cr0.3% or less,
Contains one or more of the three components of Zr0.3% or less, with the remainder essentially consisting of unavoidable impurities and Al, and has excellent formability, corrosion resistance, and weldability. Al-Si-Mg aluminum alloy rolled plate for forming processing. The second aspect of the present invention is to cast a molten alloy having the above-mentioned composition by semi-continuous casting or continuous casting, and to roll the obtained ingot, and to process the rolled plate in a temperature range of 450-590°C. and quenching at a cooling rate of 5°C/sec or more,
The present invention provides a method for manufacturing an Al-Si-Mg aluminum alloy rolled sheet for forming process, which has excellent corrosion resistance and weldability. First, the reason for limiting the composition of the present invention will be explained. Si: Si is partially present in the Al alloy as metallic Si particles and improves formability, particularly elongation properties.
In addition, some other Si coexists with Mg to produce Mg ₂ Si, which contributes to improving strength through precipitation hardening. In particular, the Mg ₂ Si stoichiometry that produces Mg ₂ Si
It is important for strength improvement to have a sufficient excess of Si particles and to generate metal Si particles. In addition, although the mechanism is unknown, Si
It also improves the weldability of arc welding such as MIG and TIG. When the Si content is less than 1.8%, these strengths,
The effect of improving formability and weldability is insufficient,
If the content exceeds 2.5%, no deterioration in weldability occurs, but the amount of metal Si particles increases too much, which is undesirable because formability, especially bendability, decreases. In addition, it has been recognized that in conventional Al-Si-Mg alloy rolled sheets for forming, if a large amount of Si is used as in the present invention, the forming processability is reduced. Indeed, Si
There is a general tendency that formability deteriorates as the amount of Mg ₂ Si increases, but
By increasing the relative amount of excess Si as the amount increases, increasing the ratio of Si metal particles/Mg ₂ Si particles, the elongation and bending radius decrease while keeping the Erichsen value, limit drawing ratio (LDR), etc. almost the same. It was found that the overall moldability was improved. Here, the excess Si amount (ΔSi) is expressed by the following formula: ΔSi=Si (wt%)−0.58Mg (wt%). When this ΔSi is set to 1.2 to 2.4%, particularly 1.2 to 1.8%, good moldability can be obtained. Mg: As already mentioned, Mg coexists with Si to generate Mg ₂ Si and impart strength. Mg is 0.25
If the Mg content is less than 1.1%, the strength will be insufficient, while if it exceeds 1.1%, the elongation will decrease.
It was set at 0.1-1.1%. Fe: Fe contributes to improving strength by making crystal grains finer, but if it is less than 0.05%, crystal grains become coarser,
On the other hand, if it exceeds 0.4%, formability will decrease, so Fe
The content was within the range of 0.05% to 0.5%. Mn, Cr, Zr: All of these elements refine the recrystallized grains, stabilize the structure, and
Improves formability. Mn less than 0.05%, Cr
If the Zr content is less than 0.05%, the above effects cannot be obtained sufficiently, so in order to actively utilize the effects of these elements, it is necessary to add 0.05% or more. On the other hand, if Mn exceeds 0.6%, formability decreases and Cr
If Zr exceeds 0.3% and Zr exceeds 0.3%, giant intermetallic compounds are formed and elongation decreases, so Mn should be 0.05~
The content was 0.6% or less, Cr was 0.3% or less, and Zr was 0.3% or less. These Mn, Cr, and Zr are effective elements for grain refinement, but the heating rate during solution treatment is 5℃/
sec or more, fine crystal grains can be formed without necessarily adding these elements. The remainder of each of the above components may be Al and inevitable impurities. Cu in impurities significantly deteriorates the corrosion resistance of the material and also impairs weldability.
Limit Cu to less than 0.1%. In addition, in ordinary aluminum alloys, a small amount of Ti or Ti and B may be added to refine the ingot crystal grains, and in the rolled aluminum alloy plate of the present invention, trace amounts of Al, alloy components, and impurities are added. may contain Ti, or Ti and B. However, when adding Ti, if it is less than 0.01%, the effect cannot be obtained, and if it is more than 0.15%, primary TiAl ₃ crystallizes and impairs the formability, so Ti is preferably in the range of 0.01 to 0.15%. In addition, when B is added together with Ti, 1ppm
If it is less than 500ppm, it has no effect, and if it exceeds 500ppm,
Coarse particles of TiB ₂ are mixed in and impair formability.
B is preferably within the range of 1 to 500 ppm. Next, a method for manufacturing an aluminum alloy rolled plate of the present invention will be explained. In order to fully exhibit the characteristics of the above alloy composition of the present invention, an aluminum alloy rolled plate is solution-treated at 450°C to 590°C, and
It is necessary to cool at a cooling rate of ℃/sec or higher. Through this solution treatment, solid solution Mg and Si are obtained in the amount necessary to obtain predetermined strength and formability. If the temperature is less than 450°C, solution treatment will be insufficient and sufficient strength will not be obtained after cooling and after baking. On the other hand, if the temperature exceeds 590°C, there is a risk of eutectic melting. Further, if the quenching rate (cooling rate) is slower than 5° C./sec, not only the strength will be insufficient, but also the corrosion resistance such as intergranular corrosion will deteriorate. Therefore, 5℃/
A quenching speed of sec or higher is required. Furthermore, in order to further improve the characteristics of the above-mentioned alloy composition, it is desirable to use a manufacturing method according to the following methods and conditions. The casting speed when semi-continuously casting a molten metal having the above alloy composition into an ingot with a rectangular cross section is not particularly determined as long as a rectangular ingot can be cast, but it is usually 25
It is cast in the range of mm/min to 250mm/min.
This ingot is heated at 450-590° C. for 1 to 48 hours prior to hot rolling in order to eliminate non-uniformity of the ingot and improve formability. If the heating temperature is less than 450℃ or the heating time is less than 1 hour, homogenization is insufficient and the heating temperature is
If the temperature exceeds 590℃, local melting will occur and the heating time will be reduced.
If the time exceeds 48 hours, the economical efficiency will decrease and the homogenization effect will be saturated. Note that instead of a large semi-continuously cast ingot, a continuously cast plate obtained by continuously supplying molten metal between two rolls may be used. In this case, there is no particular restriction on the casting speed, and cold rolling is usually performed without hot rolling. Preheating for 1 to 48 hours at ℃ is more effective. The aluminum alloy plate hot-rolled as described above is then cold-rolled to a thickness of 0.5 to 3.0.
Let it be mm. During cold rolling or during cold rolling,
If intermediate annealing is inserted between hot rolling and cold rolling,
The recrystallization effect further improves the properties of the aluminum alloy plate, particularly its strength and formability. That is, if coarse grains occur during hot rolling, the hot rolled sheet is cold rolled without intermediate annealing,
When solution treatment is performed, bands corresponding to coarse crystal grains are generated in the rolling direction, and during molding, undulations called ridging or flow lines occur, deteriorating the appearance of the molded product. Here, once recrystallization is caused by intermediate annealing, the influence of coarse grains during hot rolling can be eliminated. Here, if the intermediate annealing temperature is less than 280°C, recrystallization does not occur, and if the temperature exceeds 450°C, coarsening of crystal grains tends to occur. Also, the retention time
Intermediate annealing for more than 48 hours is not economical. In the above solution treatment, it is preferable that the coil is subjected to continuous solution quenching treatment in consideration of mass productivity and the like. The holding time shall be 0 seconds (cooling at the same time as the predetermined temperature is reached) or more and 5 minutes or less. If the coil is solution hardened continuously, from an economic point of view, the holding time should be 5
minutes is the upper limit. When this continuous solution quenching is used, a heating rate of 5° C./sec or higher is usually obtained, so crystal grains are refined and formability is improved. Next, among the various conditions of the production method of the present invention, incomplete solution treatment conditions applicable only when the Mg content exceeds 0.6% will be described. The original purpose of solution treatment was to sufficiently redissolve alloying elements that contribute to strengthening, such as Mg and Si. Therefore, in order to obtain the necessary strength, it is necessary to re-dissolve the alloying elements that contribute to the strengthening in the amount necessary to obtain that strength. A so-called complete solution treatment is performed. However, especially when used for molding automobiles, depending on the part of the vehicle body, it may be necessary to emphasize moldability over strength. In this case, the Mg content may be increased to 0.6% or more, and a so-called incomplete solution treatment may be performed in which Mg and Si are redissolved in an amount necessary for strengthening during the solution treatment. Specifically, the time or temperature may be reduced during solution treatment. In particular, when a continuous solution hardening device is used, it is possible to shorten the holding time, thereby increasing the line speed during continuous solution treatment, which provides an economical advantage. When performing incomplete solution treatment, Mg and
When the existing state of Si changes, the amount of Mg and Si that are re-dissolved changes accordingly, and the mechanical properties change. Therefore, Mg and Si before solution treatment
The key point is to keep the state of existence constant.
In order to control the state of Mg and Si before solution treatment, it is necessary to strictly control the heating conditions before hot rolling and the hot rolling conditions, but it becomes even more difficult when intermediate annealing is included in the manufacturing process. preferable. When subjected to intermediate annealing at the temperature described above, the state of existence of Mg and Si determined by the thermal history before intermediate annealing is stabilized and constant, and as a result, the regeneration of Mg and Si due to incomplete solution treatment is The amount of solid solution is stabilized, making it easier to stabilize mechanical performance. Note that solution-treated aluminum alloy rolled plates are often distorted, so the distortion is straightened. After that, surface cleaning, chemical conversion treatment, molding, welding, painting, baking hardening, etc. are performed. [Function] Typical properties of the aluminum alloy rolled sheet of the present invention in the artificially aged (T ₄ ) state after solution treatment are as follows. Mechanical properties: proof stress (σ _0.2 ) −13Kg/mm ² or more, tensile strength (σ _B ) − approximately 26Kg/mm ² or more, and elongation approximately 30% or more. Formability: Erichsen value - equivalent to or better than 6009 and 6010 alloys, minimum bending (180) - equivalent to or better than 5182 and 6009 alloys, Limit drawing ratio (LDR) - equivalent to conventional aluminum alloy plates for forming process, Lyuders mark - None. Bake hardenability: cold workability 10 assuming molding
% or less, assuming paint baking
Heat treatment at 175℃ for 1 hour increases yield strength by 1Kg/mm2 ^or more, maximum of approximately 2Kg/mm2.
^mm2 . Equivalent to or better than 6009 alloy. Corrosion resistance: The corrosion resistance of the painted plate after the usual 3-coat coating for automobile bodies consisting of electrodeposited undercoat, intermediate coat, and topcoat is superior to 6009 and 6010 alloys, and equivalent to 5182 alloy. Weldability: Weldability is better compared to conventional TIG or MIG welding, such as 6009 alloy thin plates. The aluminum alloy rolled sheet for forming according to the present invention having the above properties has a better balance of properties and is significantly more suitable as a body sheet material for automobile bodies than conventional rolled sheets. Hereinafter, the present invention will be explained in more detail with reference to Examples. [Example] Example 1 Molten aluminum alloy having the composition shown in Table 1 was
Casting speed 60mm/ for a slab with a cross section of 500 x 1000mm
Semi-continuous casting was performed at min.

[Table] Subsequently, after performing the homogenization treatment shown in Table 2, hot rolling was performed to a plate thickness of 4 mm, cold rolling to a plate thickness of 1 mm, and finally the final heat treatment shown in Table 2 was performed.

【table】

[Table] It was.
After the final heat treatment shown in Table 2, the mechanical properties and molding properties after being left at room temperature for 7 days are shown in Table 3. or,
Table 4 shows the strength after 5% and 10% cold working by stretching, assuming forming processing, and the strength after heating at 175°C for 1 hour, assuming the strength after paint baking. Ta. Note that proof stress and tensile strength are expressed in Kg/mm ² , elongation in %, and Erichsen value and minimum bending in mm.

【table】

【table】

[Table] In addition, a fishbone crack test piece was TIG welded and the cracking rate was investigated. The TIG welding conditions were: TIG automatic welding (no build-up); current 60A; advancing speed 25 cm/min; tungsten electrode 2.4 mmφ; Ar air flow; arc length 3 mm. The dimensions of the fishbone test piece are shown in Figure 1.

[Table] Here, the cracking rate is expressed by the following formula. Cracking rate = bead length with cracks/total weld bead length x
100 It can be seen that the invention alloy has excellent weldability. Summarizing the above results, we find the following. Comparative Examples 7 and 9, which have compositions of low Si and high Mg, have strength, but have poor formability and poor weldability.
Comparative example Alloy 8, which has a Cu-containing composition, has corrosion resistance,
Poor weldability. In Comparative Example 10, which has a lower Si content than Comparative Examples 7 and 9, the moldability is inferior and the strength increase after baking is also slightly inferior. Also, other characteristics are not excellent. Comparative Example 11, which contained more Mg than Comparative Examples 7 and 9, had excellent strength properties, but other properties, particularly formability, were poor. Conventional examples 13 to 16 are typical materials for molding. The materials of the invention are superior to these in terms of overall properties. That is, the material of the present invention is 2036 (No.
13) in terms of workability, elongation, bake hardenability, and weldability, 6009 (No. 14) in terms of strength and weldability, and No. 15 in terms of bake hardenability. In terms of hardenability and weldability, it is superior to 6010 (No. 16) in terms of elongation and weldability. Example 2 Hot-rolled plates having a thickness of 4 mm were obtained using Alloys 1, 4, 5, and 6 in Table 1 in the same manner as in Example 1 (however, the solution treatment will be described later). Furthermore, the plate was cold-rolled to a thickness of 3mm, and at this thickness the plate was heated at 350℃×2Hr.
Intermediate annealing was performed, followed by cooling at an average rate of 30° C./hr, followed by cold rolling to a thickness of 1 mm and winding into a coil. Note that for Alloys 1 and 6, cold rolled coils were manufactured by the same method except that intermediate annealing was omitted for comparison. These coils were heated using a continuous solution quenching furnace, heated at a temperature increase rate of 30°C/sec, held at 560°C for the time shown in Table 7, and quenched at a quenching rate of 30°C/sec. Aging was carried out for two weeks at room temperature (T ₄ condition), and then the same test as in Example 1 was carried out. Also,
Conducted a 100φ ball head extension test and observed the appearance.
Molding processability was evaluated according to the following criteria. ○: No flow lines at all △: Flow lines observed (cannot be used for applications with severe appearance) ×: Strong flow lines The results are shown in Table 6.

[Table] 175, which corresponds to the baking of paint, on the alloy plate in the _T4 state.
Table 7 shows the results of aging treatment (no stretching) at ℃×1 hour and measuring the strength.

[Table] From the above results for alloys 1 and 6 of this example, it is clear that they have excellent performance even when manufactured using a highly productive continuous annealing furnace, and that by incorporating intermediate annealing into the manufacturing process, Flowlines have been improved and have proven to be more suitable for aesthetically demanding applications such as automobiles. The solution heat retention process of 15 seconds or less applied to Alloys 4 and 5 re-dissolved the amount of Mg and Si necessary for strengthening through relatively short solution treatment, but the remaining Mg and Si were This is an example of leaving it as a precipitate, and it is a process with extremely high productivity. Although the strength of this alloy is slightly inferior to that of the complete solution treatment shown in Example 1, it has the strength required to replace automotive steel sheets, especially 12 kg/kg.
A yield strength that sufficiently exceeds the level of yield strength of mm ² or higher has been obtained. Moreover, since the material of the present invention has bake hardenability, it can be further strengthened. Moreover, it has excellent moldability (flow line). In this way, by effectively utilizing incomplete solution treatment, we can improve strength, formability, and weldability.
It becomes possible to obtain a material with excellent corrosion resistance. Example 3 Invention alloys 1, 2, 3, 4, in Example 1
5, 6, comparative alloys 7, 8, 9, 10, 11 and conventional alloys 12, 13, 14, 15, 16 (thickness 1
mm) was cut into 70 mm x 150 mm. Experiment 1: Corrosion resistance test of unpainted plate The surface of the rolled plate was coated with a 10% NaOH aqueous solution (50℃)
After degreasing for 1 minute with
The smuts were removed and washed using aqueous HNO ₃ solution. About the rolled plate treated in this way
A salt spray test was conducted according to JIS _Z 2371. Spraying time is 1000 hours. Evaluation of corrosion resistance was based on visual observation according to the following criteria. ◎ No pits at all ○ Several pits △ Considerable pits × Pits all over

[Table] Experiment 2: Blisters and filamentous corrosion after painting The above-mentioned cut and rolled plate was degreased with alkali, washed with water, and then treated with zinc phosphate. After washing with water and drying, apply cationic electrodeposition of epoxy paint to a thickness of 20 μm as an undercoat.
Thereafter, baking was performed at 160°C for 30 minutes. Melamine alkyd paint is applied as an intermediate coat to this electrodeposited paint in a thick film.
It was coated with a thickness of 30 μm and baked at 140° C. for 25 minutes. Then, a melamine alkyd paint was applied as a top coat with a thickness of 35 μm and baked at 145° C. for 25 minutes. Next, a cross cut was made on the surface of each test piece, and a salt spray test was conducted for 48 hours in accordance with JIS 2371. Next, a humidity test was conducted at a temperature of 45°C and a humidity of 95% for 30 days, and the results of evaluating surface blisters and filamentous corrosion (or thread rust) using the following criteria are shown. (Table 10)

【table】

〔Effect of the invention〕

As is clear from the above examples, the aluminum alloy rolled sheet for forming of the present invention has excellent formability, such as excellent stretchability and bendability, and no generation of reuders marks, and also has high strength. In particular, when baking is applied after molding, the strength increases during the baking process and a baking-coated molded product with extremely high strength can be obtained. Since it has excellent MIG weldability, it is particularly suitable for use in high-strength molded products that are welded and baked and used, such as automobile body sheets. The aluminum alloy rolled plate of this invention only contains Si, which is most widely used in ordinary rolled plates, extruded materials, castings, etc., as a main element, so scraps of other alloys can be easily used. On the other hand, the scrap of the rolled plate of the present invention can be easily used for other alloys and other uses, has good scrap processing 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 applications where strength is required, such as wheels, oil tanks, air cleaners, etc. Of course, it can also exhibit excellent performance when used in automobile parts, various caps and blinds, aluminum cans, household appliances, instrument covers, chassis for electrical equipment, etc.

[Brief explanation of the drawing]

Figure 1 is a drawing of a fishbone test piece (numbers are in mm).

Claims (1)

[Claims] 1. Si more than 1.8% and less than 2.5%, Mg 0.25% to 1.1%,
It contains 0.05% to 0.5% Fe, with the remainder essentially consisting of unavoidable impurities (however, less than 0.1% Cu) and Al, and has excellent formability, corrosion resistance, and weldability. Aluminum alloy rolled plate for Si-Mg forming process. 2 Si over 1.8% and 2.5% or less, Mg 0.25% to 1.1%,
Contains Fe0.05% to 0.5%, and one or more of the following three components: Mn0.6% or less, Cr0.3% or less, and Zr0.3% or less, with the remainder being virtually unavoidable. An Al-Si-Mg aluminum alloy rolled sheet for forming process, which has a composition consisting of impurities (Cu: less than 0.1%) and Al, and has excellent formability, corrosion resistance, and weldability. 3 Si over 1.8% and 2.5% or less, Mg 0.25% to 1.1%,
and Fe0.05% to 0.5%, as required.
It further contains one or two of the three components Mn 0.6% or less, Cr 0.3% or less, and Zr 0.3% or less, and the remainder is substantially unavoidable impurities (however, Cu
(less than 0.1%) and Al by semi-continuous casting or continuous casting,
A rolled plate obtained by rolling the obtained ingot was heated at 450℃ to 590℃.
Al-Si-Mg aluminum alloy rolled sheet for forming process, which has excellent formability, corrosion resistance, and weldability, and is characterized by solution treatment in the temperature range of ℃ and quenching at a cooling rate of 5℃/sec or more. manufacturing method. 4. A semi-continuously cast ingot is heated within a temperature range of 450°C to 590°C for 1 to 48 hours to perform homogenization treatment that also serves as rolling heating, and then hot rolling is performed. The method described in Scope No. 3. 5 Obtain a coiled ingot of the above alloy by continuous casting, and heat it at a temperature of 1 to 48°C within a temperature range of 300°C to 590°C.
4. A method according to claim 3, characterized in that homogenization is performed by heating for a period of time, and then hot rolling is performed. 6 Immediately after hot rolling or in the middle of cold rolling,
Claims 3 to 5 are characterized in that intermediate annealing is performed at a holding temperature range of 260°C to 450°C for a holding time of 48 hours or less, and the solution treatment is performed after subsequent cold rolling. The method described in any one of the paragraphs. 7. The solution treatment is carried out in a continuous solution heat treatment device using a coil, and the coil is cooled as soon as the temperature of the coil reaches the solution treatment temperature range, or the coil is heated within the solution treatment temperature range for 5 minutes or less. 7. The method according to any one of claims 3 to 6, characterized in that holding and performing the process are carried out.