JPH06256916A - Production of aluminum alloy sheet - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for producing an aluminum alloy sheet excellent in formability and strength and having a wide temperature range of partial annealing treatment and excellent workability. [Composition] Mn: 0.05-1wt% or Mn: 0.05-1wt%
And Mg 0.05-0.5 wt% and recrystallized by an intermediate annealing treatment on an aluminum alloy coil obtained by continuous casting and rolling to a plate thickness of 20 mm or less consisting of the balance crystal refining elements and impurities. It is performed below the temperature, and then subjected to final cold rolling and partial annealing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum alloy sheet, which is excellent in formability and strength, and has a wide temperature range for partial annealing treatment and excellent workability. It is what

[0002]

2. Description of the Related Art In order to obtain fins for plate fin type heat exchangers, caps, aluminum cans, aluminum foil containers and the like, A1000 series alloys and semi-hard thin plates containing Mn are conventionally used. In particular, the fin for plate fin type heat exchanger is a semi-hard thin plate obtained by subjecting the continuously cast rolled material of the above-mentioned A1000 alloy to cold rolling only, or subjecting it to final cold rolling after recrystallization intermediate annealing treatment, and then performing partial annealing. Was manufactured as.

On the other hand, in Japanese Patent Publication No. 61-21296, Mg 0.5%
Over 1.0% and less than 1.0% and Mn in an amount of 0.05 to 1.0%, Fe and Si in a specific relationship, and the balance of Al and unavoidable impurities are proposed for thin plate aluminum alloys. In addition, a so-called flare process in which a hole close to the outer diameter of the liquid passage through which the heat exchange medium flows is formed in the manufactured semi-rigid thin plate, an overhang is formed around the hole, and the overhang is curled outward Molding the plate fins by means of the drawings is also illustrated.

[0004]

In the prior art as described above, the strength of the thin plate is increased in order to reduce the weight, and the thickness of the thin plate is reduced accordingly, which corresponds to the weight reduction. In order to improve the strength of a hard thin plate, since there is no stable region in the heating softening curve at the time of partial annealing, the heating temperature range is narrow, workability is poor, and the quality is unstable.

Further, the thin plate obtained as described above has a reduced elongation, resulting in cracking during flare processing, and since the Erichsen value is low, the overhang height cannot be made large and the plate fin is made lightweight. There is a drawback that it is difficult to obtain a preferable product as a semi-rigid thin plate corresponding to.

[0006]

Means for Solving the Problems The present invention has been studied to solve the problems in the prior art as described above, and in the course of cold rolling an aluminum alloy coil having Mn dissolved in supersaturation in continuous casting rolling. It is possible to suppress the growth of the recrystallization initial structure generated in the rolling structure in the subsequent partial annealing treatment by precipitating a fine Al-Mn-based intermetallic compound by heating and holding at a temperature lower than the recrystallization temperature. A stable region is formed in the heat-softening curve at the time of partial annealing by the recrystallization initial structure so as to prevent the flare from cracking even if the strength is improved, and is as follows.

(1) Mn: 0.05 to 1 wt% or Mn: 0.0
For an aluminum alloy coil containing 5 to 1 wt% and Mg: 0.05 to 0.5 wt% and obtained by continuous casting and rolling to a plate thickness of 20 mm or less composed of the remaining crystal refining elements and impurities. A method for producing an aluminum alloy sheet, which comprises performing an intermediate annealing treatment at a temperature lower than a recrystallization temperature, and then performing final cold rolling and partial annealing.

[0008]

According to the present invention as described above, the composition of the material, the plate-making conditions, the specific intermediate annealing treatment, the final cold rolling and the partial annealing are included, which are as follows.

Mn: 0.05-1 wt%. Mn precipitates as an Al-Mn-based fine intermetallic compound in the intermediate annealing, suppresses the growth of subcrystals (recrystallization initial structure) in the subsequent partial annealing, and forms a temperature range in which softening stagnates. If it is less than 0.05%, such an effect cannot be effectively obtained. On the other hand, if it exceeds 1%, the elongation in the softening stagnation temperature range decreases and the workability deteriorates.

Mg: 0.05 to 0.5 wt%. Strength is improved by adding Mg, but 0.05 wt%
If it is less than the above range, the effect is poor, and preferable improvement in strength and thinning cannot be obtained. On the other hand, if it exceeds 0.5 wt%, the hardening during cold rolling becomes large, it becomes difficult to control the plate strain, and the plate becomes wavy, which is not preferable.

Elements other than the above are Fe, Si, Cu, Cr,
Zn and the like are impurity elements, and Fe and Si up to 0.5 wt% and Cu, Cr, and Zn up to 0.3 wt% impede the stabilizing effect on the thermal softening curve during partial annealing by the intermediate annealing treatment of the present invention. And does not hinder the achievement of the object of the present invention.

The grain refining element is appropriately added to prevent the occurrence of cracks during casting. For example, Ti: 0.001 to 0.1 wt%, B: 0.0001 to 0.02.
wt% and Zr: 0.001 to 0.1 wt% are added to effectively achieve the technical object of the present invention.

Next, the plate-making conditions will be described. Continuous casting of an Al-Mn or Al-Mn-Mg alloy melt, which has been subjected to slag treatment and the like, by a movable mold method such as a Hunter method, a 3C method or a Hazarley method. Roll to obtain a plate having a plate thickness of 20 mm or less. This is to solidify the molten alloy rapidly during casting so as to form a solid solution of Mn element. When the plate thickness is 20 mm or more, it is difficult to obtain a sufficiently fine Al-Mn compound by the intermediate annealing treatment. In the partial annealing treatment of No. 1, an intermediate annealed material having low temperature sensitivity with respect to strength cannot be obtained.

The continuously cast rolled plate having a plate thickness of 20 mm or less obtained as described above is cold-rolled in consideration of the final desired thickness, but is re-rolled at least once during the cold-rolling process. Intermediate annealing is performed at a temperature lower than the crystallization temperature. The cold rolling before the intermediate annealing is necessary to obtain a stable region in the heat softening curve during the partial annealing, and the cold rolling amount may be, for example, about 30% in the rolling reduction in the Hunter method.

The intermediate annealing treatment at a temperature lower than the recrystallization temperature described above, together with the cold rolling before the treatment, precipitates the supersaturated solid solution Mn element in the continuous casting rolling as an Al--Mn system fine compound, In order to improve the strength and workability of the partially annealed material while suppressing the growth of sub-crystals generated in the rolling structure in the subsequent partial annealing treatment and creating the stable region as described above in the heat softening curve during the partial annealing. It is a thing. If recrystallized during intermediate annealing, roughening occurs during flare processing and the workability is impaired.

Generally, the recrystallization temperature is not constant depending on the history of the treated material, but in the case of the present invention, it is about 350 to 400 ° C., so that it is surely set to 350 ° C. or less, which is preferable. Also, this lower limit temperature of heating is about 250 near the recovery temperature of the treated material.
The heating time is 1 to 24 hours.

The sheet material subjected to the intermediate annealing treatment as described above is cold-rolled to a desired thickness and then subjected to the partial annealing treatment. The rolling reduction of the final cold rolling is 50% or more, preferably 8 in order to stabilize the quality of the sheet material after the partial annealing treatment.
It is better to be 0% or more.

The hard thin plate cold-rolled to the desired plate thickness as described above is made into a product by partial annealing, and this partial annealing is less than the recrystallization temperature and generally 250.
It is carried out in a temperature range of about 360 ° C. for about 1 to 12 hours while being adapted to the desired properties of the semi-hard thin plate. By such partial annealing, both elongation and Erichsen value are high, and excellent strength (tensile strength) is obtained. Since the annealing temperature is lower than the recrystallization temperature, rough skin at Erichsen becomes small.

[0019]

EXAMPLES Examples of the present invention as described above will be explained. First, the Al-Mn alloy, the Al-Mn-Mg alloy according to the present invention used by the present inventors, and the Al-Mn alloy as a comparative example are described. The composition of the Fe-Si alloy (1100 alloy) is as shown in Table 1 below.

[0020]

[Table 1]

Each of the alloys A, B and C shown in Table 1 was manufactured by a Hunter continuous casting and rolling machine to produce an aluminum coil having a thickness of 6.8 mm, and each of these coils is shown in Table 2 below. A thin plate having a thickness of 0.115 mm was prepared according to the plate-making process, tensile strength, elongation and Erichsen value were measured, and rough skin at the time of Erichsen was examined. The results are shown in Table 3. That is, it is clear that the present invention has excellent properties in balance of tensile strength, elongation and Erichsen value as compared with Comparative Examples. Also, it is found that the workability is excellent and the quality is stable.

[0022]

[Table 2]

[0023]

[Table 3]

In the accompanying drawings, Example B of the present invention shown in Table 3 above.
1 and 2 and B6 by the conventional manufacturing method, that is, the comparative example in which 530 ° C. × 2 hr was performed as the intermediate annealing, the changes in tensile strength and elongation with respect to the change in final annealing temperature are also shown. It can be seen that the product according to the present invention has a small change in tensile strength between about 250 to 350 ° C. and has a low temperature sensitivity, so that the heat treatment is easy and a product of stable quality can be obtained.

[0025]

As described above, according to the present invention, the temperature range of the partial annealing treatment is wide, the workability is excellent, and the formability and strength are both excellent, and the fins and caps for the plate fin type heat exchanger, This is an invention which can obtain a preferable product as an aluminum can or an aluminum foil, and which has a great industrial effect.

[Brief description of drawings]

FIG. 1 is a table summarizing changes in tensile strength and elongation with respect to changes in final annealing temperature for Examples B1 and 2 according to the present invention and Comparative Example B6 according to a conventional method.

Claims (1)

[Claims] 1. Mn: 0.05-1 wt% or Mn: 0.05-
Intermediate annealing of an aluminum alloy coil containing 1 wt% and Mg: 0.05 to 0.5 wt% and obtained by continuous casting and rolling to a plate thickness of 20 mm or less consisting of the balance grain refining elements and impurities. A method for producing an aluminum alloy sheet, characterized in that the treatment is carried out at a temperature lower than the recrystallization temperature, followed by final cold rolling and partial annealing.