JPH1025555A - Production of aluminum alloy rolled sheet for resin-coated building material excellent in strength an bendability - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a bendability of an alloy sheet without deteriorating its strength even by high temp. baking finish by subjecting an Al alloy ingot having a specified compsn. to heat treatment or the like under prescribed conditions. SOLUTION: An Al alloy contains, by weight, 0.5 to 1.6% Mn and furthermore contains a small amt. of Fe, Si, Cu, Mg, Zn, Cr, Zr, V or the like for the impartment of strength. The ingot having the aforesaid compsn. is subjected to soaking treatment, hot rolling, primary cold rolling and process annealing in succession to obtain fine recrystallized grains. Then, secondary cold rolling is executed for improving its strength. Thereafter, final annealing is executed, and the temp. and holding time are prescribed so as to be regulated to the conditions in fluororesin coating finish or above and also not so as to produce new recrystallized grains. In this way, deterioration in its strength and deformation after baking finish do not occur. For example, in the case of a batch annealing furnace, it is executed under the conditions of 240 to 350 deg.C×0.5 to 24hr. As a result, the alloy sheet having >=110N/mm<2> proof stress, and in which the average grain diameter in the rolled face is regulated to <=80μm can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a rolled aluminum alloy plate for resin-coated building material which maintains high strength and has improved bending workability, and more particularly to a resin-coated building material subjected to high-temperature baking such as fluororesin. The present invention relates to a method for manufacturing a rolled aluminum alloy plate.

[0002]

2. Description of the Related Art Recently, high-temperature baking paints such as fluororesins have been used for resin-coated building materials, and a resin material having a bending strength of 90 ° or more has been used.
There is a case where a severe bending work design of up to 180 ° is made, and in this case, there is a problem that the conventional material has insufficient strength or breaks during bending. For example, conventional (a) a method for producing an aluminum plate for building having excellent high-temperature baking coating properties (Japanese Patent Laid-Open No. 6-172945), (b) a rolled aluminum alloy sheet for resin-coated building materials having excellent strength and bending workability and production thereof A method (JP-A-6-212333) is known. However, although (a) has a modestly superior effect on bending workability, the upper limit (28) is set under the condition of baking with fluororesin (usually 240 to 280 ° C. × 20 min).
(0 ° C. × 20 min), the yield strength is almost 1
The strength is as low as 10 N / mm ² or less, and it is difficult to solve this. Although (b) has an excellent effect on the proof stress, cracking occurs in bending at a bending of 90 ° or more, for example, bending at 120 to 180 °, and it is difficult to solve this.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art and provides an aluminum alloy sheet having improved bending workability without loss of strength (proof strength of 110 N / mm ² or more) even by high-temperature baking coating. It is intended to provide a manufacturing method.

[0004]

Means for Solving the Problems The present inventors have studied the component composition and manufacturing conditions of an Al plate in order to solve the above problems, and as a result, have completed the present invention. That is, in the present invention, Mn: 0.5 to 1.6% (% by weight, hereinafter the same), F
e: 0.10 to 0.8%, and further, Si: 0.0
5 to 0.5%, Cu: 0.05 to 0.5%, Mg: 0.
05-0.3%, Zn: 0.05-0.5%, Cr:
0.05-0.3%, Zr: 0.05-0.2%, V:
An Al alloy ingot containing one or more of 0.05% to 0.2% and the balance of unavoidable impurities and Al is soaked at a temperature of more than 500 ° C. and 640 ° C. or less, and hot rolling is performed at 550 ° C.
Starting at the following temperature, ending at 300 ° C or less, and performing cold rolling at 40% or more, A, 300-500 ° C × 0.5-
24 hr or B, 400-620 ° C. × 0 (no holding) to 10 min, intermediate annealing and recrystallization, and after cold rolling 15-35%, C, 240-3
50 ° C x 0.5 to 24 hours or D, 300 to 50
A final annealing that does not cause new recrystallization is performed under the conditions of 0 ° C. × 0 (no holding) to 10 min, and after the final annealing,
The gist of the present invention is a method for producing a rolled aluminum alloy plate for resin-coated building material having excellent strength and bending workability, wherein the yield strength is 110 N / mm ² or more and the average crystal grain size of the rolled surface is 80 μm or less.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the reasons for limiting the chemical components in the present invention will be described. Mn: Mn is an element that improves the strength. If it is less than 0.5%, its effect is small, and if it exceeds 1.6%, it is excessively improved and the bending workability is reduced. Therefore, the amount of Mn is 0.5 to
The range is 1.6%. Fe: Fe contributes to the strength, but is an element that combines with Mn during casting to become an Al—Mn—Fe crystallized compound and inhibits bending workability. If less than 0.10%, the required strength cannot be obtained. If it exceeds 0.8%, bending workability is significantly impaired. Therefore, the Fe content is in the range of 0.10 to 0.8%. Si: Si is an element that imparts strength, but 0.05%
If it is less than 0.5%, there is no effect, and if it exceeds 0.5%, the improvement in strength saturates, and it is useless to add more. Therefore, S
The i amount is in the range of 0.05 to 0.5%. Cu: Cu is an element that imparts strength, but 0.05%
If it is less than 0.5%, there is no effect, and if it exceeds 0.5%, the corrosion resistance is undesirably deteriorated. Therefore, the amount of Cu is 0.05 to
The range is 0.5%. Mg: Mg is an element that improves strength by forming a solid solution.
If it is less than 05%, the effect is small, and if it exceeds 0.3%, it is excessively improved and the bending workability is reduced. Therefore, the Mg content is in the range of 0.05 to 0.3%. Zn: Zn is an element that imparts strength, but 0.05%
If it is less than 0.5%, there is no effect, and if it exceeds 0.5%, the corrosion resistance is undesirably deteriorated. Therefore, the amount of Zn is 0.03-
The range is 0.5%. Cr: Cr is an element contributing to the improvement of the strength.
If it is less than 5%, there is no effect, and if it exceeds 0.3%, a giant compound is formed and bending workability is reduced. Therefore, the Cr content is in the range of 0.05 to 0.3%. Zr, V: Zr and V are elements that impart strength. However, if the content is less than 0.05%, the effect is not obtained. If the content is more than 0.2%, a giant compound is generated and bending workability is deteriorated. Therefore, the amount of Zr and the amount of V are 0.05 to
The range is 0.2%.

[0006] Other than the above elements are impurities or optional addition elements. Ti, B: In an ordinary aluminum alloy, Ti alone or a combination of Ti and B is added in order to refine the ingot. In the present invention, Ti alone or a combination of Ti and B may be added. In that case, T
If the i content is less than 0.005%, there is no effect, and if it exceeds 0.15%, primary crystal TiAl ₃ is crystallized and bending workability is impaired, so the Ti content is in the range of 0.005 to 0.15%. And When B is added together with Ti, the amount of B is 1
If it is less than 500 ppm, there is no effect, and if it exceeds 500 ppm, T
Because workability iB ₂ is bent to produce is inhibited, B content is set to 1 to 500 ppm. Be: Be may be added to prevent oxidation of the molten metal, but may also be added in the present invention. If the amount of Be in this case is less than 1 ppm, there is no effect, and 500 ppm
If the amount exceeds, the effect is saturated, and adding more than that is useless. Therefore, the Be amount is in the range of 1 to 500 ppm. In addition, Na, Ca,
It is preferable that impurities such as Pb, Bi, Ga, Sn, and Ni are each independently suppressed to less than 200 ppm.

Next, a method of manufacturing a rolled aluminum alloy sheet will be described in the order of steps. [Casting] The casting method is not particularly limited, and an ingot may be made by a conventional method, but a DC casting method (semi-continuous casting method) is preferable. [Soaking heat treatment] The soaking heat treatment is performed to obtain fine recrystallized grains in the intermediate annealing step.
₆ Mn precipitates are minute, and it is difficult to obtain fine recrystallized grains by intermediate annealing. If the temperature exceeds 640 ° C., there is a possibility of melting.
Therefore, the soaking temperature is in the range of more than 500 ° C and 640 ° C or less, preferably more than 560 ° C and 640 ° C or less. Also,
Although the holding time depends on the temperature, the object of the present invention is achieved by setting it to 1 to 30 hours. [Heat treatment and hot rolling] The hot rolling start temperature is set to 550 ° C or lower in order to keep the hot rolling end temperature at 300 ° C or lower, which is lower than the recrystallization temperature. Hot rolling start temperature is 550 ℃
If the temperature exceeds 300 ° C., the hot rolling end temperature will exceed 300 ° C., and the whole or partial recrystallization will occur, which will lead to coarsening of crystal grains and reduction in strength, which is not preferable. Heating for hot rolling is performed so as to satisfy the hot rolling conditions. However, the heat treatment may be omitted when hot rolling is performed after the ingot after the soaking is gradually cooled to 550 ° C. or lower. [Primary cold rolling] Primary cold rolling is performed to obtain fine recrystallized grains in the next intermediate annealing step and to prevent surface roughness during bending, but at a rolling reduction of less than 40%, the recrystallized grains have a size of 80 µm.
And the skin becomes rougher. Therefore, the primary cold rolling rate is set to 40% or more to prevent roughening of the surface. [Intermediate annealing] Intermediate annealing is performed to obtain recrystallized grains, and any of a batch annealing furnace and a continuous annealing furnace may be used. For the purpose of obtaining recrystallized grains, when using a batch annealing furnace, the recrystallization temperature is 300 ° C. or higher, and when using a continuous annealing furnace, the process is performed at 400 ° C. or higher because of a short time. Also,
If the temperature exceeds 500 ° C. in a batch annealing furnace and 620 ° C. in a continuous annealing furnace, coarse crystal grains are formed, which may cause roughening during bending. Therefore, the intermediate annealing is performed at 300 to 500 ° C. × 0.5 to 24 hours in the batch annealing furnace and 400 to 620 ° C. × 0 (no holding) to 10 min in the continuous annealing furnace.
The conditions are as follows. [Secondary Cold Rolling (Final Cold Rolling)] The secondary cold rolling is performed to improve the strength. However, if the cold rolling reduction is less than 15%, the final annealing falls below the strength target of the present invention and exceeds 35%. In addition, the balance between strength and bending workability is lost due to final annealing, and the object of the present invention is not achieved. Therefore, the secondary cold rolling is set in the range of 15 to 35%. [Final annealing] The conditions of the temperature and the holding time of the final annealing are defined as conditions that are higher than or equal to the fluororesin baking coating conditions (240 to 280 ° C x 20 min) and that no new recrystallized grains are generated. By doing so, there is no reduction in strength or deformation after the baking of the fluororesin. Either a batch annealing furnace or a continuous annealing furnace may be used. 24 when using a batch annealing furnace
When using a continuous annealing furnace at 0 ° C or higher, since the time is short, 3
Perform at 00 ° C or higher. In a batch annealing furnace, 350
If the temperature exceeds 500 ° C. in a continuous annealing furnace at a temperature of 500 ° C., new recrystallized grains are generated and the strength is reduced. Therefore, the final annealing is performed at 240 to 350 ° C. × 0.5 to 24 hours in the batch annealing furnace, and at 300 to 500 ° C. × 0 (no holding) to 10 mi in the continuous annealing furnace.
Perform under the condition of n.

[0008] After annealing, distortion correction may be performed with a stretcher, a roller leveler, or the like as necessary. In this case, the proof stress before the resin baking coating is slightly improved, and after the resin baking coating, the strength is reduced. It does not become lower than the proof stress immediately after annealing, and does not hinder the effects of the present invention.

The rolled aluminum alloy sheet thus obtained is particularly excellent in bending workability and has high strength without any reduction in strength after baking resin coating.好 適 Suitable as a resin baking coating material that requires bending.

[0010]

EXAMPLES For alloys A to G in Table 1, D
Cast by C casting method (semi-continuous casting method), 450m thick
mx 1200 mm wide 3000 mm length).

[0011]

[Table 1]

With respect to the obtained ingot, production numbers 1 to
Under the conditions shown in Fig. 14, soaking → heating → hot rolling is applied to a thickness of 8
mm (however, serial numbers 3 and 14 are 10 mm, serial number 12 is 5.5 mm). Then, the thickness was set to 4.0 mm (however, production number 13 was 3.35 mm, production number 14 was 5.0 mm) by primary cold rolling, and intermediate annealing was performed in a batch annealing furnace or a continuous annealing furnace. Thereafter, secondary cold rolling was performed to a thickness of 3.0 mm, and final annealing was performed in a batch annealing furnace or a continuous annealing furnace to obtain a final sheet. Then, the strength, crystal grain size, and bending workability of each final plate were examined.
For the strength, the proof stress was measured by a tensile test, and for the crystal grain size, the average crystal grain size of the rolled surface was determined by a cutting method.
The presence or absence of cracks and rough skin was examined by a 35 ° bending (punch tip 0 mm ^R ) test. The results are also shown in Table 2. In the table Underlined conditions indicate conditions outside the scope of the present application.

[0013]

[Table 2]

Hereinafter, each result will be described. The materials of Production Nos. 1 to 5 are invention examples in which both the component composition and the production process satisfy the conditions specified in the present invention. As shown in Table 2, the proof stress shows a high strength of 110 N / mm ² or more. It is clear that the material is excellent in strength and bending workability without cracking or roughening even in a 135 ° bending test.

On the other hand, the materials of production numbers 6 to 9 are comparative examples which satisfy the production process conditions defined in the present invention but do not satisfy the component composition conditions. Production No. 6 uses alloy D whose Mn content is lower than the component range specified in the present invention, and Production No. 7 uses alloy E whose Mn content is higher than the component range specified in the present invention. Since the amount was small, the bendability was good, but the yield strength was as low as 110 N / mm ² or less, and the latter was too high in yield strength due to the large amount of Mn, and the bendability was reduced. Production No. 8 uses alloy F whose Fe content is lower than the component range specified in the present invention, and Production No. 9 uses alloy G whose Fe content is higher than the component range specified in the present invention. Although the bending workability is good because the amount is small, the yield strength is low strength of 110 N / mm ² or less, and the latter has a high yield strength due to the large amount of Fe, and the Al—Mn—Fe crystallized compound The bending workability was reduced by the increase in the size of.

Although the alloys A satisfying the component composition conditions specified in the present invention are used for the materials of the manufacturing numbers 10 to 14, the comparative examples in which the manufacturing process conditions deviate from the conditions specified in the present invention. is there. In production number 10, the heating temperature before hot rolling was too high, and the hot rolling end temperature exceeded 300 ° C., so that recrystallization occurred at the end of hot rolling, and the proof stress and bending workability decreased. Oops. Serial number 1
In No. 1, the soaking temperature was too low, and the precipitation of Al ₆ Mn was insufficient in the soaking process, so that the recrystallized grains became coarse in the intermediate annealing, and the crystal grains became too large, and the proof stress and bending workability decreased. have done. In production number 12, the primary cold rolling reduction was too low, the crystal grains became large, and the bending workability was reduced. In the case of Production No. 13, the secondary cold rolling reduction was too low, and the yield strength was insufficient. Further, the serial number 14
Since the secondary cold rolling reduction was high, the softening was accelerated and the proof stress was insufficient.

Further, the production numbers 15 to 21 show the effects of the intermediate annealing conditions and the final annealing conditions while keeping the other conditions constant. That is, the production numbers 18 to 21 are comparative examples in which any of the intermediate annealing conditions and the final annealing conditions out of the production process conditions deviate from the conditions specified in the present invention. In Production No. 18, the intermediate annealing temperature was too low, and recrystallization was not performed at the end of the intermediate annealing. In Production No. 19, the intermediate annealing temperature was too high, and the recrystallized grains became coarse at the end of the intermediate annealing, resulting in rough surface due to bending. In production number 20, the final annealing temperature was too low, and deformation occurred in the baking coating process. In the case of Production No. 21, the final annealing temperature was too high, and new coarse recrystallized grains were generated in the final annealing, resulting in a decrease in strength and roughening due to bending.
On the other hand, the production numbers 15 to 17 are examples of the invention in which the production process conditions are also within the range defined by the present invention, and all are excellent in strength and bendability.

[0018]

As is clear from the above examples, according to the present invention, the bendability is particularly good, and the proof strength after baking resin is as high as 110 N / mm ² or more. An aluminum alloy rolled plate having excellent strength can be obtained. By using the rolled aluminum alloy sheet according to the present invention as a resin-coated building material (curtain wall, interior / exterior building material, etc.) such as fluorine which requires a high-temperature baking coating, a construction design of severe bending processing requiring high strength is realized. It becomes possible.

Claims (1)

[Claims] 1. Mn: 0.5 to 1.6% (% by weight, the same applies hereinafter), Fe: 0.10 to 0.8%, and S
i: 0.05 to 0.5%, Cu: 0.05 to 0.5%,
Mg: 0.05-0.3%, Zn: 0.05-0.5
%, Cr: 0.05-0.3%, Zr: 0.05-0.
2%, V: An Al alloy ingot containing one or more of 0.05 to 0.2% and the balance of unavoidable impurities and Al is heat-treated at a temperature of more than 500 ° C. and 640 ° C. or less, and hot rolling is performed. Starting at a temperature of 550 ° C. or less and ending at a temperature of 300 ° C. or less, and after performing cold rolling of 40% or more, A, 300 to 500 ° C. × 0.5 to 24 hours or
B, 400-620 ° C x 0 (no holding)-10 min
Intermediate annealing and recrystallization under the conditions described above, and further cold-rolled by 15 to 35%, C, 240 to 350 ° C x 0.5 to 24 hours or
D, 300-500 ° C x 0 (no holding)-10 min
The final annealing that does not cause new recrystallization is performed under the conditions described above. After the final annealing, the proof stress is 110 N / mm ² or more,
A method for producing a rolled aluminum alloy plate for resin-coated building material having excellent strength and bending workability, wherein the average crystal grain size of a rolled surface is 80 μm or less.