JPH06299279A - Aluminum alloy material for blind and its production - Google Patents

Abstract

PURPOSE:To obtain a material increased in a final cold working ratio, high in strength after coating and baking treatment and small in deterioration in proof stress after coating and baking treatment. CONSTITUTION:This aluminum alloy has a compsn. contg., by mass, 0.5 to 1.5% Si, 0.3 to 0.8% Mn, 0.3 to 0.8% Mg, 0.25 to 0.5% Cu, 0.3 to 0.8% Zn and 0.05 to 0.20% Ti, in which the content of Fe as impurities is limited to <=0.30%, and the balance Al with inevitable impurities. In the allay, electric resistance value is regulated to >=1.3muOMEGA.cm, tensile strength is regulate to >=180MPa, the tensile strength is working ratio is executed and the proof stress after coating and baking treatment at <=230 deg.C for >=50sec is regulated to >=350MPa. It is subjected to solution treatment of heating to 500 to 550 deg.C in a continuous annealing furnace and is subjected to final cold rolling of 70 to 85%.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aluminum alloy material for blinds and a method for producing the same, and in particular, it is excellent in cold rolling property after solution treatment, and after being subjected to coating baking treatment at 230 ° C. or less for a total of 50 s or more. Also relates to an aluminum alloy material for blinds with little strength reduction and a method for producing the same.

[0002]

2. Description of the Related Art Since a blind material is required to have a certain level of strength and corrosion resistance, a thin plate of aluminum alloy is often used, and conventional AA5052 (Al-2.5).
% Mg-0.25% Cr type), 5086 (Al-4% Mg-0.5% Mn-0.15%
Cr-based), 5182 (Al-4.5% Mg-0.35% Mn-based), etc.
Rolled sheets of Mg-based aluminum alloy having a thickness of 0.1 to 0.2 mm have been used. In general, since the blind is used by finishing the coating, as the aluminum alloy material for the blind, a material that is not softened by the baking treatment after coating is desired, but the above-mentioned aluminum alloy is usually used. The strength of the coating, particularly the yield strength, is likely to decrease in the coating baking process in which the temperature is maintained at 230 ° C for 40 to 50 seconds, and the performance as a blind is often reduced.

As an aluminum alloy material for blinds having improved strength characteristics, an Al alloy containing 4% Mg and 1% Zn (Japanese Patent Laid-Open No. 60-251245) and an Al alloy in which 1% Cu is further added (Japanese Patent Laid-Open No. 60-251245). (Sho 61-15937), 2% Cu, 1%
Al alloy containing Mg and 1% Si (JP-A-61-15938),
An alloy based on Al-Mg-Mn-Fe (JP-A-1-
205050, 205051, 205052), 2% Mg, 1% Mn, 0.
An Al alloy containing 35% Cu (Japanese Patent Laid-Open No. 4-88145) has been developed, and the manufacturing method is 2% Mg, 1% Mn, 0.1%.
After hot rolling an Al alloy containing 35% Cu, a solution treatment was performed during the cold rolling to increase the final rolling workability to increase the strength (Japanese Patent Laid-Open No. 4-88145). A method to give strength by performing primary and secondary cold rolling before and after the intermediate heat treatment using thin slabs and increasing the workability
(JP-A-2-25546) has been proposed.

However, in these aluminum alloys, when the cold working rate is increased to secure the strength,
For example, when 70% or more of rolling is performed, since the final plate thickness is thin, cracks at the plate edges tend to occur, the yield of the material may decrease, and rolling may not be possible. In addition, there is a problem that when the degree of rolling is increased, the number of rolling passes is increased and the work efficiency is reduced.

Recently, in order to improve the habitability, colorful blinds have been demanded, and the first and second coats
Aluminum alloys for blinds are more likely to undergo a large decrease in strength because the number of coating bakings is performed twice (2 coats and 2 bake) with the color of the coat changed, and the decrease in strength after heat treatment is even smaller. Material development is required.

[0006]

SUMMARY OF THE INVENTION In order to solve the conventional problems of aluminum alloy materials for blinds and to meet the above-mentioned development demands, the present invention provides a combination of strength and component elements after baking treatment and these elements. As a result of research on the combination of precipitation elements, cold workability and additive elements at the coating baking temperature,
By adjusting the amounts of i, Mg and Cu, all of the precipitated Mg during the baking treatment for coating is Mg ₂ Si phase or Al-Mg-Cu.
Cold workability by precipitating as a system compound, increasing the strength of the alloy by containing excess Si and Cu, and further suppressing the content of Mg to the necessary minimum, and adding Ti in the combination of these components. It was made based on the finding that it is possible to increase the rolling rate, and even if the final cold rolling process rate is increased, cracks do not occur at the plate edge, and the reduction amount in one pass of rolling is reduced. It can be made large and avoids an increase in the number of rolling passes. Paint baking treatment, for example 200 to 230 ℃
It is an object of the present invention to provide an aluminum alloy material for blinds, in which the strength is not significantly reduced even after the coating baking treatment is performed twice.

[0007]

The aluminum alloy material for blinds and the method for producing the same according to the present invention for achieving the above object are composed of Si 0.5 to 1.5% (mass%, hereinafter the same), Mg 0.3 to 0.8. %, Mn 0.3 to 0.8%, Cu 0.
25-0.5%, Zn0.3-0.8% and Ti0.05-0.20
%, Fe as an impurity is limited to 0.30% or less, an aluminum alloy consisting of the balance Al and unavoidable impurities, having an electrical resistivity of 1.3 μΩ · cm or more and a tensile strength of 180 MPa or more, The tensile strength is 400 MPa or less even after the final cold rolling with a working rate of 95% or less, and 23
The yield strength is 350 MPa or more even after the coating baking treatment for 50 s or more at 0 ° C. or less, and Si 0.5 to
1.5%, Mg0.3-0.8%, Mn0.3-0.8%, Cu0.2
5 to 0.5%, Zn 0.3 to 0.8% and Ti 0.05 to 0.20
%, Fe as an impurity is limited to 0.30% or less, and an aluminum alloy consisting of the balance Al and unavoidable impurities is hot-rolled and cold-rolled, and heated to 500 to 550 ° C. in a continuous annealing furnace. After solution heat treatment, final cold rolling with a working rate of 70-85% is performed to reduce the electrical resistivity to 1.3.
μΩ · cm or more, tensile strength of 400 MPa or less, and 23
The structural feature is that the proof stress after the baking treatment for 50 s or more at 0 ° C. or less is 350 MPa or more.

Explaining the reason for limiting the components of the aluminum alloy in the present invention, Si is an alloy after the coating baking treatment is carried out by precipitating the Mg ₂ Si phase together with Mg at the coating baking treatment temperature (200 to 230 ° C.). It is effective in reducing the decrease in strength. The preferred content range is 0.5-
1.5%, and if less than 0.5%, the Mg content of the present invention is
Since it is as small as 0.3 to 0.8%, the formation of Mg ₂ Si phase is reduced and the strength after coating baking is lowered. If it exceeds 1.5%, the ductility of the alloy is lowered, and cracks are likely to occur at the plate edges during cold rolling.

Mg, together with Si and Cu, has the effect of precipitating the Mg ₂ Si phase and the Al--Mg--Cu compound at the coating baking temperature, and reducing the decrease in strength of the alloy after the coating baking treatment. is there. The preferred content range is 0.3-0.
8% and less than 0.3%, Mg ₂ Si phase and Al
-The amount of Mg-Cu-based compound is small and the strength is lowered after the baking treatment. If it exceeds 0.8%, work hardening in cold rolling becomes large and the amount of reduction in one pass decreases, which causes an increase in the number of rolling passes and cracks at the edges of the rolled plate.

Mn has the effect of precipitating an Al--Mn compound in the solution heat treatment and coating baking treatment, imparting heat resistance to the alloy material, and reducing the strength reduction after coating baking treatment. It is contained in the range. If it is less than 0.3%, the effect is small due to the small amount of Mg, and
If the content exceeds 8%, the work hardening in cold rolling increases and the reduction amount in one pass cannot be increased.
The number of rolling passes increases, and cracks easily occur at the edges of the rolled plate. Furthermore, it forms coarse Al—Fe—Mn crystallized substances, which easily causes cracks during hot rolling or cold rolling, and also causes defects such as pinholes.

Cu has the effect of precipitating an Al-Mg-Cu-based compound together with Mg at the coating baking temperature and reducing the decrease in strength of the alloy. The preferred content range is 0.
It is 25 to 0.5%, and if it is less than 0.25%, the amount of precipitation of the Al-Mg-Cu-based compound is small, and the effect of reducing strength reduction is small. If it exceeds 0.5%, the ductility of the alloy decreases, and cracks are likely to occur at the plate edge during cold rolling.

[0012] Zn has the effect of forming a fine MgZn ₂ phase together with Mg at the coating baking temperature and reducing the decrease in strength of the alloy. The preferred content range is 0.3-0.
8%, and if it is less than 0.3%, this effect is small, and a yield strength of 350 MPa or more cannot be obtained after baking. If it exceeds 0.8%, the work hardening in the cold working becomes large, the ductility of the material also deteriorates, and cracks are likely to occur at the plate end portion in the cold rolling.

Ti refines the ingot structure of the alloy and forms a fine crystal grain structure during hot rolling and solution treatment,
Without causing cracks at the plate edge in cold rolling,
It is possible to increase the final cold rolling rate. A preferable addition range is 0.05 to 0.20%, and if less than 0.05%, its effect is small, and if it exceeds 0.20%, a coarse compound of Al ₃ Ti is formed, and cracks are likely to occur during hot rolling or cold rolling. It also causes defects such as pinholes in the rolled plate material.

Fe forms a coarse Al—Fe—Mn crystallized product, which easily causes cracks during hot rolling or cold rolling, and causes defects such as pinholes in the final rolled sheet material. Therefore, it is desirable to keep the Fe content as low as possible in order to obtain the effect of reducing the strength reduction after the coating baking treatment by Mn. However, in order to reduce the Fe content, it is necessary to use high pure aluminum ingots. In consideration of the fact that the manufacturing cost becomes large, the alloy composition of the present invention has a content of 0.3%
Is the upper limit.

The aluminum alloy material for blinds of the present invention has the above composition, and it is essential that the electrical resistance is 1.3 μΩ · cm or more and the tensile strength is 180 MPa or more. The electrical resistivity affects the softening resistance of the alloy during the baking process of paint. In order to improve the softening resistance, in order to generate fine intermetallic compounds of alloying elements such as Si, Mg and Cu at the time of baking treatment, it is necessary to use a material in which these alloying elements are solid-dissolved, The electrical resistivity increases with the amount of solid solution. The solid solution state for giving the alloy sufficient softening resistance during paint baking is
It can be obtained by setting the electrical resistivity to 1.3 μΩ · cm or more. If the tensile strength is less than 180 MPa, the strength as a blind is insufficient. Further, when the tensile strength of the material exceeds 400 MPa in the final cold rolling process, cracks are likely to occur at the plate end during the process, which lowers the yield and makes rolling unfavorable.

Explaining the manufacturing conditions, the aluminum alloy of the present invention is formed into an ingot by, for example, continuous casting,
After ingot homogenization treatment, hot rolling according to the usual method,
After cold rolling to the specified thickness, 500-55 in a continuous annealing furnace.
Perform solution treatment by heating to 0 ° C. The continuous annealing furnace performs heat treatment by continuously passing through a heating zone while rewinding a metal plate coil, and is well known as an equipment for annealing an aluminum plate.

By performing solution treatment in a continuous annealing furnace,
Mg ₂ Si phase or Al-Mg-C precipitated by hot rolling
By re-dissolving the u-based compound in the matrix and re-precipitating these by coating baking treatment, the recovery of the worked structure is delayed and the decrease in strength after coating baking treatment is reduced. The solution treatment is performed by heating to 500 to 550 ° C. If the heating temperature is less than 500 ° C, the Mg ₂ Si phase or Al-M
If a sufficient re-solid solution of g-Cu compound cannot be obtained and the heating temperature exceeds 550 ° C, the eutectic formed in the alloy will melt and crack into the plate during annealing or final cold rolling. May occur. The rate of temperature increase until the solution treatment temperature is reached is not required to be specified, but the cooling rate from the solution treatment temperature is preferably maintained at 10 ° C./s or higher. If the cooling rate is slow, Mg ₂ Si
The phases and Al-Mg-Cu-based compounds coarsely precipitate, and these fine precipitates are reduced during the coating baking treatment, resulting in a large decrease in strength after the coating baking treatment.

The final cold rolling performed after the solution treatment is necessary to increase the strength of the alloy plate material by work hardening and maintain the strength of the plate material after the baking treatment. The preferable rolling working ratio is 70 to 85%, and if it is less than 70%, the yield strength of the alloy after the coating baking treatment, especially the treatment by 2 coat 2 bake cannot be made 350 MPa or more. When the cold rolling ratio exceeds 85%, the strength of the plate material increases, but dislocations accumulate and the strain energy inside the plate becomes too large.
Since the work structure is easily recovered during heating in the baking process, the yield strength after the baking process is less than 350 MPa. In addition, cracks are likely to occur at the edges of the plate during cold rolling.

[0019]

The present invention has the above-mentioned structure and contains S in the alloy components.
By adjusting the amounts of i, Mg, Mn, Cu and Zn, the intermetallic compounds between these elements or between these elements and Al are finely precipitated in the alloy matrix during the baking treatment by the interaction of these elements. By suppressing the decrease in strength of the alloy after coating baking treatment, limiting the Fe content and adding Ti, it is possible to perform cold rolling under high pressure without causing cracks at the edges of the rolled plate and improve the strength of the alloy. In order to secure a proof stress of 350 MPa or more after performing a heat treatment for 50 seconds or more at 230 ° C. or less, which is equivalent to a coating baking treatment.

[0020]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples. Example 1 The aluminum alloys shown in Table 1 were melted by a conventional method and made into an ingot by continuous casting. The ingot was homogenized at 500 ° C. for 8 hours and then hot-rolled to a plate thickness of 2.5 mm. The end temperature of hot rolling was adjusted to 290 to 330 ° C. Then, after cold rolling at a working ratio of 70%, solution treatment was performed using a continuous annealing furnace. The solution heat treatment was performed under the conditions that the temperature was raised to 500 ° C at a temperature rising rate of 10 ° C / s, held at this temperature for 10 seconds, and then cooled to room temperature at a cooling rate of 10 ° C / s. The final cold rolling after the solution treatment gave a working rate of 80% with 6 passes, and a test material with a plate thickness of 0.15 mm was obtained.

[0021]

[Table 1]

Regarding the test material, visually observing the degree of cracking at both ends of the final rolled plate, ○ indicates that no crack was detected, △ indicates crack length of 5 mm or less, △ indicates crack length exceeds 5 mm Was evaluated as x. In addition, a tensile test was conducted to measure tensile strength, proof stress, and elongation, and the test material was heated at 230 ° C for 100 seconds using an oil bath, assuming a coating baking treatment of 2 coats and 2 bake. about
Tensile performance was measured using JIS No. 5 tensile test pieces, and the rate of decrease in yield strength after heating was evaluated by the following formula. Yield reduction rate (%) = (Yield strength after final cold rolling-Yield strength after final heating) / (Yield strength after final cold rolling) x 100 Furthermore, the electrical resistance value (R) was measured at both ends of the test piece with current lead wires. Spot welding, connect the lead wire to a DC power supply and ammeter, and similarly spot weld voltage lead wires to both ends of the test piece, connect the voltmeter to the lead wire, and immerse the whole in liquid nitrogen. Then, a direct current was applied from a power source, and the current value (I) and the voltage value (V) were measured by the DC four-terminal method, and the electrical resistivity was determined by the following equation. Electrical resistivity (ρ) = R × S / L, where R = V / I,
Table 2 shows S: sectional area of the test piece, L: distance between voltage terminals, and evaluation results.

[0023]

[Table 2]

As shown in Table 2, none of the test materials prepared according to the present invention had cracks at the edges of the final cold-rolled sheet material and had a proof stress of 35 after heating at 230 ° C. for 100 seconds.
Above 3 MPa, the decrease in yield strength after heating was 7.1% or less, which is a good result.

Example 2 Test materials No. 1, No. 4 and No. 6 of Example 1 were subjected to solution heat treatment and final cold rolling under the conditions shown in Table 3, and the same method as in Example 1 was used. Various performances were evaluated. The results are shown in Table 4. The solution treated material had a plate thickness adjusted so that the final plate thickness was 0.15 mm, and was subjected to a predetermined cold rolling process. The temperature rising rate in the continuous annealing furnace was 10 ° C / s. As shown in the results of Table 4, all of the test materials produced by using the aluminum alloy of the present invention according to the conditions of the present invention have no cracks in the plate edge portion of the final cold rolled plate material, The yield strength after heating at 100 ° C for 100 seconds was 353 MPa or more, and the yield strength reduction rate was 7.1% or less, indicating good performance.

[0026]

[Table 3]

[0027]

[Table 4]

Comparative Example 1 An aluminum alloy having the composition shown in Table 5 was used in Example 1
In the same manner as described above, casting, homogenization treatment, hot rolling, cold rolling, solution treatment and final cold rolling were carried out to produce a test material having a plate thickness of 0.15 mm. Various performances of these test materials were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 6.
In Table 5, those that did not meet the component limitation of the present invention are underlined.

[0029]

[Table 5]

[0030]

[Table 6]

As shown in Table 6, in the test material made of the aluminum alloy which did not exceed the component limits of the present invention, cracking occurred at the plate end portion of the final cold rolled plate material or the yield strength after heating decreased. Since the test material No. 1 had a low Si content, cracking occurred at the plate edge, and the yield strength after heating at 230 ° C also decreased. No. 2 had a Si content of more than 1.5%, and No. 3 had a Fe content of more than 0.30%, so that cracks occurred at the plate edges. No. 4 had a small Cu content, so that the yield strength after heating was large, and No. 5 had a Cu content exceeding the limited range and cracked during the final cold rolling. No. 6 has a low Mn content and No. 8 has a low Mg content, so both are at 230 ° C.
The yield strength after heating is large, and No. 7 has a large amount of Mn.
Since No. 9 had a large amount of Mg, cracks occurred at the plate edge during the final cold rolling. No. 10 had a small Zn content, so the yield strength after heating was large, and No. 11 had a Zn content exceeding the limited range, so cracks occurred at the plate edges. In No. 12, the Ti content exceeds the limited range, so cracking occurred during cold rolling.

Comparative Example 2 Regarding the test materials No. 1, No. 4 and No. 6 produced in Example 1,
Solution treatment and final cold rolling were performed under the conditions shown in Table 7, and various performances were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 8. The solution treated material has a final plate thickness
It has a plate thickness adjusted to 0.15 mm and is subjected to predetermined cold rolling. Temperature rising rate in continuous annealing furnace is 10 ℃
/ s, the heating rate of the batch furnace was 50 ℃ / s.

[0033]

[Table 7]

[0034]

[Table 8]

As shown in Table 8, test materials prepared by solution treatment or final cold rolling that do not satisfy the conditions of the present invention (in Table 7, those outside the conditions of the present invention are underlined). No.), the yield strength was reduced, or the plate edge was cracked. The test materials No. 13 and No. 15 have low solution treatment temperature, so that re-solution of alloy elements becomes insufficient,
The yield strength decreased. Since No. 14 had a high solution treatment temperature, eutectic melting occurred partly and cracking occurred at the plate edge during final cold rolling. In No. 16, since the final cold rolling rate was below the lower limit, sufficient work hardening could not be obtained and the yield strength after heating was low. Since the final cold rolling rate of the test material No. 17 exceeds the limit range, cracks occur at the plate edge, and at the same time, the heat treatment at 230 ° C makes it easier to recover the work structure and the yield strength decreases significantly. . No.18, No.19, and No.20 were all solution heat treated in a batch furnace, in order to obtain fine precipitation of Mg ₂ Si phase and Al-Mg-Cu-based compound when heated at 230 ° C. Since the solid solution state of is not achieved, the yield strength after heating is low, and the yield strength is greatly reduced.

[0036]

EFFECTS OF THE INVENTION According to the present invention, an aluminum alloy material for blinds is provided, which has improved final cold workability and has a small decrease in strength after coating baking even when a coating baking treatment of 2 coats and 2 bake is performed. It 1 in cold rolling
Since the reduction rate per operation can be increased, the production efficiency is also improved.

Claims (2)

[Claims] 1. Si 0.5 to 1.5% (mass%, the same applies hereinafter), Mg 0.3 to 0.8%, Mn 0.3 to 0.8%, Cu 0.25
~ 0.5%, Zn 0.3 ~ 0.8% and Ti 0.05 ~ 0.20%
Fe as an impurity is limited to 0.30% or less,
Aluminum alloy consisting of balance Al and unavoidable impurities with electrical resistivity of 1.3 μΩ · cm or more and tensile strength of 180
The tensile strength is 400 MPa or less even after the final cold rolling with a working rate of 85% or less, and even after the coating baking treatment of 230 s or less for 50 s or more. An aluminum alloy material for blinds that has a yield strength of 350 MPa or more. 2. Si0.5-1.5%, Mg0.3-0.8%,
Mn0.3-0.8%, Cu0.25-0.5%, Zn0.3-0.
8% and Ti 0.05 to 0.20%, Fe as an impurity is limited to 0.30% or less, an aluminum alloy consisting of the balance Al and unavoidable impurities is hot-rolled and cold-rolled, and a continuous annealing furnace is used. After the solution treatment of heating to 500 ~ 550 ℃ by, the final cold rolling at a working rate of 70 ~ 85%, electrical resistivity of 1.3 μΩ · cm or more,
Tensile strength of 400 MPa or less and 50 at 230 ° C or less
The yield strength is 350 M after the coating baking process for s or more
A method for producing an aluminum alloy material for a blind, which is Pa or more.