JP2626922B2 - Method for producing aluminum plate with uniform mechanical properties and ear ratio in plate width direction - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an aluminum plate having uniform mechanical properties in the width direction of the plate and having a uniform ear ratio in the width direction during forming.

Conventional technology Generally aluminum plate, especially JIS 1050, JIS 1100, JIS
BACKGROUND ART Pure aluminum-based aluminum plates such as 1200 are widely used as foils, printing plates, building materials, fin materials for heat exchangers, and the like.

In the aluminum plate such applications, except when used as a complete annealed materials (O materials), i.e. H _1n material and H
_When used as a _2n temper material, it is required that the mechanical properties in the plate width direction be uniform.

Conventionally, as a method of manufacturing an aluminum plate having uniform mechanical properties in the width direction, Japanese Patent Publication No. Sho 56-502 proposes a method of controlling the hot rolling end temperature to 260 ° C. or lower. In the proposed method, if the hot-rolling end temperature exceeds 260 ° C., the cooling rate differs between the center and the end of the coil during the process of cooling the hot-rolled coil.
The degree of precipitation of Fe, Si, Mn, and Cr is different, and the distribution of fine precipitates is not uniform in the width direction of the sheet, and the recrystallization behavior in the width direction of the sheet is different, and as a result, the mechanical properties are reduced in the width direction of the sheet. Therefore, it is possible to make the mechanical properties in the sheet width direction uniform by setting the hot rolling end temperature to 260 ° C. or less.

On the other hand, when an aluminum plate is used for forming such as deep drawing, it is often used as a completely annealed material (O material). In this case, not only the ear ratio at the time of forming is low but also the width of the plate. It is required that variation in ear ratio be small in the direction and the plate longitudinal direction.

Conventionally, as a method of manufacturing an aluminum sheet having a uniform ear ratio in the sheet width direction, Japanese Patent Publication No. 52-6684 discloses a method in which the hot-rolling ending temperature is set to 260 as in the above-mentioned method of Japanese Patent Publication No. 56-502.
There has been proposed a method of forcibly cooling in the course of hot rolling so that the temperature is not more than ℃. In the proposed method, fine precipitates such as Fe and Si are generated non-uniformly in the width direction of the plate in the temperature range of 280 ℃ ± 20 ℃ after the completion of hot rolling. As a cause of this, as a preventive measure before or after the start of hot rolling, or in the middle of hot working, forced cooling to 260 ° C. or less by shower cooling or air blowing etc.
It is stated that if the temperature is rapidly cooled to not more than ℃, the precipitation of fine precipitates will be uniform in the width direction of the sheet, and the ear ratio at the time of forming will be uniform in the width direction of the sheet.

SUMMARY OF THE INVENTION As described above, in the method proposed in Japanese Patent Publication No. 56-502 or the method proposed in Japanese Patent Publication No. 52-6684, mechanical properties in the plate width direction or uniformity of ear ratio are obtained. For this reason, only the precipitation behavior of solute elements after the completion of hot rolling is considered, but the present inventors have conducted further experiments and examinations, and found that the change of crystal grains themselves during hot rolling, that is, the recrystallization state It was also found that merely controlling the hot-rolling end temperature does not always make it possible to achieve uniform mechanical properties or ear ratio in the sheet width direction. In carrying out the method proposed above, it is necessary to forcibly cool the hot-rolling end temperature to 260 ° C. or less.However, it is difficult to perform forced cooling uniformly. On the contrary, the mechanical properties or ear ratio may become non-uniform.

The present invention has been made in view of the above circumstances,
It also controls the change in crystal structure during hot rolling, making it possible to make the mechanical properties in the sheet width direction even more uniform without necessarily performing forced cooling. It is an object of the present invention to provide a method for manufacturing an aluminum plate that can be surely made uniform.

Means for Solving the Problems The present inventors have conducted intensive experiments and studies in order to solve the above-mentioned problems, and as a result, the starting temperature of hot rolling is in the range of 300 to 420 ° C, preferably 300 to 370 ° C. At the same time as regulating, the rolling reduction in each pass of hot rolling is regulated to 60% or less per pass to completely suppress recrystallization during the hot rolling process to make it systematically uniform and finish hot rolling. 250 ° C
By the following, the mechanical properties in the width direction of the sheet, that is, the strength and elongation of the _H1n material and the _H2n temper material can be sufficiently and surely uniform, and at the same time, the ear ratio at the time of forming as the O material is reduced. The present inventors have found that uniformization can be sufficiently and reliably performed in the width direction of the sheet, and have accomplished the present invention.

Specifically, the method for manufacturing an aluminum plate of the present invention includes heating an ingot of an aluminum alloy, starting hot rolling at a temperature in the range of 300 to 420 ° C., and reducing a rolling reduction in each pass of hot rolling. Is set to 60% or less per pack, recrystallization during hot rolling is suppressed, and the hot rolling is performed at 250 ° C.
The process is terminated at the following temperature.

The target aluminum in the method of the present invention is not particularly limited to pure aluminum, but various aluminum alloys, for example, pure aluminum alloys such as JIS 1100 and JIS 1200, or aluminum such as JIS 3003 and AA 3102. -Mn-based alloys, JIS 5005, JIS 5052 Al-Mg-based alloys may be used.

As a casting method of the aluminum ingot, a semi-continuous casting method (DC casting method) may be applied according to a conventional method. The presence or absence of soaking in the aluminum ingot before hot rolling is not particularly limited in the present invention, but the soaking in soaking reduces the segregation of components and reduces the width direction in the H _1n or H _2n temper material of the final sheet. The mechanical properties and the ear ratio of the O material tend to be uniform.

In the method of the present invention, the start temperature of hot rolling on the aluminum ingot and the rolling reduction in each pass in hot rolling are important, and the hot rolling start temperature is set to 300 to 420 ° C. By controlling the rolling reduction to 60% or less per pass, recrystallization during hot rolling is prevented. If the hot rolling temperature exceeds 420 ° C., local recrystallization occurs during hot rolling. This recrystallization is more likely to occur near the surface of the plate, and if you compare the end of the plate width and the center of the plate width,
Recrystallization occurs in the central part of the sheet width up to a thicker part in the sheet thickness direction. Thus inhomogeneous recrystallization occurs, the crystal orientation in the sheet width direction becomes uneven, and the solid solution amount of solute elements becomes uneven, with the result final plate H _1n material or H _2n temper material Also, the mechanical properties of the material become non-uniform, and the occurrence of ears at the time of forming when the material is completely annealed to obtain an O material also becomes non-uniform. On the other hand, if the hot rolling start temperature is lower than 300 ° C., the hot rolling property is reduced, so that it is necessary to increase the size of the hot rolling mill. The rolling reduction has to be reduced significantly, which leads to problems such as impairing the economy and further causing edge cracks to occur easily in the rolled material. Therefore, the hot rolling start temperature must be in the range of 300 to 420 ° C. Even within this range, it is preferable to set the temperature within the range of 300 to 370 ° C. in order to more completely prevent recrystallization during hot rolling.

Also, in order to reliably suppress recrystallization during hot rolling, it is necessary to reduce the rolling reduction for each pass of hot rolling. It is necessary to always reduce the rate to 60% or less per pass. If the rolling reduction per pass exceeds 60%, recrystallization may occur partially.

The hot rolling end temperature must be 250 ° C. or less. 250
If the hot rolling is completed at a high temperature exceeding ℃, the mechanical properties and the ear ratio at the end and the center in the width direction of the sheet become non-uniform. This is because the distribution and amount of precipitation of the solute element during the cooling of the coil after the completion of the hot rolling are not uniform. When hot rolling is completed at a temperature exceeding 250 ° C, recrystallization may partially occur in the coil after the completion of hot rolling, and in this case, the mechanical properties and ear ratio in the width direction are not uniform. Become. Therefore, in order to make the mechanical properties and ear ratio in the width direction uniform, the hot rolling end temperature needs to be 250 ° C. or less.

By performing hot rolling as described below, a hot-rolled sheet having a crystal structure in which recrystallization is completely suppressed, that is, having a completely non-recrystallized structure, and having a uniform precipitation amount and distribution in the width direction is obtained. Can be For such a hot-rolled sheet, or the H _1n material further subjected to cold rolling, if the H ₁₈ temper material was annealed by continuous annealing furnace or a batch furnace with H _2n-tempered material, ultimately sheet width A plate with uniform mechanical properties in the direction is obtained. Further, if the O material is obtained by performing complete annealing after the cold rolling, a plate can be obtained in which the occurrence of ears during forming is uniform in the plate width direction.

EXAMPLES [Example 1] J having a thickness of 500 mm and a width of 1200 mm manufactured by a DC casting method.
The ingot of IS 1100 alloy was soaked at 550 ° C. for 5 hours. After heating and holding at 330 ° C., hot rolling was started at 330 ° C. as shown in production condition code No. 1 and No. 3 in Table 1, and after hot rough rolling was completed at 240 ° C., Subsequently, hot finish rolling was completed at 210 ° C. to obtain a hot-rolled sheet having a thickness of 3 mm. The rolling reduction per pass in the hot rolling process is 50 at the maximum.
%. Then the hot-rolled sheet is further subjected to cold rolling final thickness 0.5mm cold rolled plate and (H ₁₈ material). Furthermore this H ₁₈
For a part of the material, final annealing under various conditions was performed in a batch furnace (No. 1 in Table 1) or a continuous furnace (No. 3 in Table 1), and each of H ₂₆ , H ₂₄ , and H ₂₂ A tempered material was used.

On the other hand, for comparison, an ingot of JIS 1100 alloy having the same
After performing a soaking process at 5 ° C for 5 hours, heat and maintain at 500 ° C, then start hot rolling at 500 ° C as shown in Production Conditions Nos. After finishing at 370 ° C,
Subsequently, the hot finishing reduction was completed at 290 ° C. to obtain a hot-rolled sheet having a thickness of 3 mm. The rolling rate per pass in the hot rolling step was set to 65% at the maximum. Then the similarly subjected to cold rolling thickness 0.5mm cold rolled sheet against hot rolled sheet and (H ₁₈ material). Furthermore for some of the H ₁₈ material, batch furnace final annealing of various conditions performed by or continuous furnace (No.2 in Table 1) (No.4 in Table 1), H _26, H _24, were each tempered material of H _22.

H ₂₆ material in the case of manufacturing conditions No.1~No.4 which Note described above, H ₂₄ material, although the final annealing conditions for the H ₂₂ material is not specifically stated, the plate width direction central portion thereof Annealing temperature was selected so as to be within the range of the mechanical properties of the temper type. Therefore, each annealing temperature differs depending on the rolling start temperature, rolling end temperature, and annealing method.

Also, 500m thick cast by DC casting method
m, an ingot of 1000 mm wide AA 3102 alloy was subjected to soaking at 550 ° C. for 5 hours, and then heated and maintained at 370 ° C., as shown in Production Condition Code No. 5 in Table 1 The hot rolling was started at 250C and the hot rough rolling was completed at 250C, and then the hot finish rolling was completed at 220C to obtain a hot-rolled sheet having a thickness of 4 mm.
The rolling reduction per pass in the hot rolling process is the highest.
55%. It was then subjected to cold rolling sheet thickness 0.2mm cold rolled plate and (H ₁₈ material) with respect to hot-rolled sheet. Furthermore for some of the H ₁₈ material, was H ₂₆ temper material by performing final annealing at 270 ° C. × 5 hours by a batch furnace.

For comparison, an ingot of AA3102 alloy having the same dimensions as above cast at the same casting chance as above was used.
After performing the soaking process for a period of time, it is heated and maintained at 500 ° C., and as shown in the manufacturing condition code No. 6 in Table 1, hot rolling is started at 500 ° C., and rough hot rolling is performed at 370 ° C. And hot finish rolling at 310 ° C. was completed to obtain a hot-rolled sheet having a thickness of 4 mm. The rolling reduction per pass in the hot rolling process was set to 70% at the maximum. Thereafter, by performing the cold rolling sheet thickness 0.2mm cold rolled sheet against hot rolled sheet and (H ₁₈ material), the portion of the H ₁₈ material, the final annealing of 270 ° C. × 5 hours by a batch furnace To give H ₂₆ temper material.

In each of the above examples, the microstructure of the hot-rolled sheet in the sheet width direction and the sheet thickness direction was examined, and the recrystallization in the hot-rolled state was examined. The results are shown in Table 2. In addition, the mechanical properties of the H ₁₈ material, H ₂₆ temper material, H ₂₄ temper material, and H ₂₂ temper material obtained in each example at the center and the end in the sheet width direction were examined. The results are shown in Table 2.

From Table 2, it is clear that the aluminum plate obtained by the method of the present invention has uniform mechanical properties in the width direction in the state of _H1n material or _H2n temper material.

Further, although not shown in Table 2, the aluminum plate obtained by the method of the present invention has a strength reduction ratio with respect to the annealing temperature, that is, the annealing softening gradient is gradual, so that H _2n
It has been found that the annealing temperature can be set broadly within the standard value of each temper material. Further, the aluminum plate obtained by the method of the present invention is subjected to final annealing to obtain H _2n
In the case of producing a temper material, it was found that the mechanical properties became uniform whether the final annealing was in a batch furnace or a continuous furnace.

[Example 2] J having a thickness of 500 mm and a width of 1200 mm manufactured by a DC casting method
The ingot of IS 1100 alloy was soaked at 550 ° C. for 5 hours. Thereafter, after heating and holding at 330 ° C., hot rolling was started at 330 ° C. as shown in production condition codes No. 7 and No. 9 in Table 3, and after hot rough rolling was completed at 240 ° C., Subsequently, hot finish rolling was completed at 210 ° C. to obtain a hot-rolled sheet having a thickness of 6 mm. The rolling reduction per pass in the hot rolling process is 50 at the maximum.
%. Thereafter, the hot-rolled sheet was subjected to cold rolling at a stage of 4 mm thickness by performing intermediate annealing at 390 ° C. for 2 hours in a batch furnace, and further cold-rolled to obtain a final cold-rolled sheet having a final thickness of 2.0 mm. Cold-rolled sheets each having a thickness of 1.0 mm were obtained. The final annealing for complete annealing was performed on the cold rolled sheet of each thickness by a batch furnace (No. 7 in Table 3) or a continuous furnace (No. 9 in Table 3) to obtain an O material.

On the other hand, for comparison, an ingot of JIS 1100 alloy having the same
After performing a soaking at 5 ° C. for 5 hours, heating and holding at 450 ° C., as shown by the manufacturing conditions Nos. 8 and 10 in Table 3, hot rolling was started at 450 ° C. and hot rough rolling was performed. After finishing at 320 ° C,
Subsequently, hot finish rolling was completed at 290 ° C. to obtain a hot-rolled sheet having a thickness of 6 mm. The rolling reduction per pass in the hot rolling process was set to 60% at the maximum. Thereafter, the hot-rolled sheet was subjected to cold rolling, intermediate annealing, and cold rolling in the same order as described above to obtain a cold-rolled sheet having a sheet thickness of 2.0 mm and a cold-rolled sheet having a sheet thickness of 1.0 mm. Further, the cold-rolled sheet of each thickness was subjected to final annealing for complete annealing in a batch furnace (No. 8 in Table 3) or a continuous furnace (No. 10 in Table 3) to obtain an O material.

Also, 500m thick cast by DC casting method
m, an ingot of AA3102 alloy having a width of 1000 mm was subjected to soaking at 530 ° C. for 5 hours, and then heated and maintained at 370 ° C., as shown in Production Condition Code No. 11 in Table 3, The hot rolling was started at 250C, the hot rough rolling was completed at 250C, and then the hot finish rolling was completed at 220C to obtain a hot-rolled sheet having a thickness of 5 mm.
The rolling reduction per pass in the hot rolling process is the highest.
55%. After that, cold rolling is applied to the hot rolled sheet
At the stage of 3 mm thickness, intermediate annealing at 370 ° C. × 2 hours was performed in a batch furnace, and further cold rolling was performed to obtain cold-rolled sheets having final thicknesses of 2.0 mm and 1.0 mm. The final annealing for complete annealing in a batch furnace is performed on the cold-rolled sheet of each thickness,
Material.

For comparison, an ingot of AA3102 alloy having the same dimensions and cast at the same casting chance as above was used.
After performing a soaking heat treatment for a period of time, the steel sheet is heated and maintained at 460 ° C., and then, as shown in production condition code No. 12 in Table 3, hot rolling is started at 460 ° C. and rough hot rolling is performed at 340 ° C. , And then hot finish rolling at 310 ° C. was completed to obtain a hot-rolled sheet having a thickness of 5 mm. The rolling reduction per pass in the hot rolling process was set to 65% at the maximum. Then, cold rolling, intermediate annealing, and cold rolling are performed on the hot rolled sheet in the same
2.0 mm and 1.0 mm cold rolled sheets were obtained, and the cold rolled sheets of each thickness were subjected to final annealing for complete annealing in a batch furnace to obtain an O material.

Although the final annealing conditions for the O material in the case of the manufacturing conditions No. 7 to No. 12 described above are not particularly specified, the central part in the sheet width direction is within the range of the mechanical properties of the O material. Annealing temperature was selected so as to be as follows. Therefore, the respective annealing temperatures differ depending on the rolling start temperature, rolling end temperature, annealing method, and sheet thickness.

In each of the above examples, the microstructure of the hot-rolled sheet in the sheet width direction and the sheet thickness direction was examined, and the recrystallization state in the hot-rolled state was examined. The results are shown in Table 4. Further, with respect to the O material having a thickness of 1.0 mm and the O material having a thickness of 2.0 mm obtained in each example, the state of occurrence of ears at the center and ends in the width direction of the plate when deep drawing was performed was examined. Therefore, the results are also shown in Table 4. Note that the deep drawing in this case was performed at a drawing ratio of such a level that the processing could be carried out without any trouble in actual mass-production processing.

From Table 4, it is clear that the aluminum plate obtained by the method of the present invention has a uniform ear ratio in the width direction in the state of the O material, and further, the generation of ears itself is small.

Although not shown in Table 4, when the aluminum sheet obtained by the method of the present invention is subjected to final annealing to produce an O material, the occurrence of ears is uniform even if the final annealing is performed in a batch furnace or a continuous furnace. It turned out to be.

According to the method of the present invention, the hot-rolling end temperature is set to 250 ° C.
In addition to the regulation below, the hot rolling start temperature is 300 ~ 4
At the same time as controlling the temperature within the range of 20 ° C, the rolling reduction per pass of hot rolling is controlled to 60% or less, and recrystallization during hot rolling is suppressed. In addition to being uniform in the direction, a completely non-recrystallized structure can be obtained in the state after hot rolling, so that when H _1n material or H _2n temper material is used, the mechanical properties in the sheet width direction are extremely uniform. Furthermore, an aluminum plate having a uniform ear ratio in the width direction of the plate when the forming process is performed in the state of the O material can be obtained. Further, in the method of the present invention, the hot rolling start temperature is regulated to a relatively low temperature.
Because it is not necessary to perform forced cooling in the hot rolling process in order to make it 250 ° C or less, when the forced cooling is applied, the mechanical properties and the ear rate become uneven due to the uneven cooling rate. The occurrence of a situation can be prevented.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-169757 (JP, A) JP-A-61-257459 (JP, A) JP-A-59-179768 (JP, A)

Claims (2)

(57) [Claims] 1. An aluminum alloy ingot is heated to 300 to 4
Hot rolling is started at a temperature within the range of 20 ° C., and the rolling reduction in each pass of hot rolling is reduced to 60% or less per pass to suppress recrystallization during hot rolling and to perform hot rolling. Is finished at a temperature of 250 ° C. or less, a method for producing an aluminum plate having uniform mechanical properties and ear ratio in the width direction of the plate. 2. The method for producing an aluminum sheet according to claim 1, wherein the starting temperature of the hot rolling is set to a temperature in the range of 300 to 370 ° C.