JP3161141B2 - Manufacturing method of aluminum alloy sheet - Google Patents

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, and provides a method for producing an aluminum alloy sheet having excellent formability and strength, a wide temperature range for partial annealing, and excellent workability. It is assumed that.

[0002]

2. Description of the Related Art In order to obtain fins, caps, aluminum cans, aluminum foil containers and the like for plate fin type heat exchangers, conventionally, an A1000 series alloy and a semi-hard thin plate containing Mn therein have been used. In particular, fins for plate fin type heat exchangers are preferably made of the above-mentioned continuous cast rolled material of the A1000 series alloy only by cold rolling, or subjected to recrystallization intermediate annealing treatment and then subjected to final cold rolling, and then subjected to partial annealing to obtain a semi-hard thin plate. And was manufactured.

On the other hand, in Japanese Patent Publication No. 61-21296, Mg 0.5%
Over 1.0% or less and Mn in a range of 0.05 to 1.0%, further containing Fe and Si in a specific relationship, the balance being Al and unavoidable impurities. Also, a so-called flare process is performed on the manufactured semi-rigid thin plate by forming a hole similar to the outer diameter of the liquid passage pipe through which the heat exchange medium flows, forming an overhang around the hole, and curling the overhang outward. It is also illustrated and described that the plate fin is formed by using the same.

[0004]

In the prior art as described above, the strength of the thin plate has been increased in response to the demand for weight reduction, and the thickness of the thin plate has been correspondingly reduced to reduce the thickness. In order to improve the strength of a hard thin plate, there is a disadvantage that the heating temperature range is narrow because the heating softening curve at the time of the partial annealing does not have a stable region, the workability is poor, and the quality is not stable.

[0005] Further, the thin plate obtained as described above has a reduced elongation, and as a result, cracks occur during flaring, and the Erichsen value is low, so that the overhang height cannot be made large and the weight of the plate fin can be reduced. There is a disadvantage that it is difficult to obtain a product which is preferable as a semi-rigid thin plate corresponding to the above.

[0006]

SUMMARY OF THE INVENTION The present invention has been studied to solve the problems in the prior art as described above, and an aluminum alloy coil having Mn dissolved in a supersaturated state by continuous casting and rolling is formed during cold rolling. By heating and holding at a temperature lower than the recrystallization temperature to precipitate a fine Al-Mn-based intermetallic compound, it is possible to suppress the growth of the recrystallization initial structure generated in the rolled structure in the subsequent partial annealing treatment. It is a structure in which a stable region is formed in a heating softening curve at the time of partial annealing by a recrystallization initial structure so that the flare is not cracked even when the strength is improved, and is as follows.

(1) Mn: 0.05 to 1 wt% or Mn: 0.0
5-1 wt% and Mg: 0.05-0.5 wt%, and
Ti: 0.001 to 0.1 wt%, B: 0.0001 to 0.02 wt%
And Zr: one or more of 0.001 to 0.1 wt%, the balance being Al and impurities having a thickness of 20
In the middle of cold rolling, the aluminum alloy coil obtained by continuous casting and rolling to a thickness of not more than mm is subjected to intermediate annealing at a temperature lower than the recrystallization temperature, and then the partial annealing after the final cold rolling is also performed at the recrystallization temperature. A method for producing an aluminum alloy sheet.

[0008]

According to the present invention as described above, the composition of the raw material and the conditions such as sheet making conditions, specific intermediate annealing treatment, final cold rolling and partial annealing are as follows.

Mn: 0.05 to 1 wt%. Mn precipitates as an Al-Mn-based fine intermetallic compound in the intermediate annealing, and suppresses the growth of subcrystals (initial recrystallized structure) in the subsequent partial annealing to form a temperature range in which softening stagnates. If it is less than 0.05%, such an effect cannot be obtained effectively, while if it exceeds 1%, elongation in the above-mentioned softening stagnation temperature range is reduced, and workability is deteriorated.

Mg: 0.05 to 0.5 wt%. The strength is improved by adding Mg, but 0.05wt%
If it is less than 30%, the effect is poor, and desirable strength improvement and thinning cannot be obtained. On the other hand, if it exceeds 0.5% by weight, the hardening during cold rolling becomes large, and it becomes difficult to control the plate distortion, and the plate may become wavy, which is not preferable.

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

The crystal 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%, Zr: 0.001 to 0.1 wt%, to effectively achieve the technical object of the present invention.

Next, the plate making conditions will be described. The molten Al-Mn or Al-Mn-Mg alloy which has been subjected to slag removal treatment or the like is continuously cast by a movable mold method such as a hunter method, a 3C method, or a Hazaret method. Rolling is performed to obtain a plate having a thickness of 20 mm or less. This is to rapidly solidify the molten alloy at the time of casting and to sufficiently solidify the Mn element. When the plate thickness exceeds 20 mm, it is difficult to obtain a sufficiently fine Al-Mn-based compound by intermediate annealing. In the partial annealing treatment, an intermediate annealing material having a low temperature sensitivity with respect to strength cannot be obtained.

The continuous cast rolled plate having a 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 treatment is performed at a temperature lower than the crystallization temperature. The cold rolling before the intermediate annealing treatment is necessary to obtain a stable region in the heating softening curve at the time of the partial annealing, and the amount of the cold rolling may be, for example, about 30% as the rolling reduction in the Hunter method.

The intermediate annealing treatment at a temperature lower than the recrystallization temperature, together with the cold rolling before the treatment, precipitates the super-saturated solid solution Mn element as a fine Al-Mn compound by continuous casting and rolling. In order to suppress the growth of subcrystals generated in the rolled structure in the subsequent partial annealing treatment, to create the above-mentioned stable region in the heating softening curve during partial annealing, and to improve the strength and workability of the partially annealed material. Things. If recrystallization is performed during intermediate annealing, the surface becomes rough during flare during flaring, and the workability is impaired.

In general, the recrystallization temperature is not constant depending on the history of the processing material. However, in the case of the present invention, the recrystallization temperature is about 350 to 400 ° C., so it is preferable and certainly set to 350 ° C. or less. The heating lower limit temperature is about 250 around the recovery temperature of the processing material.
C., and a suitable heating time is 1 to 24 hours.

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

The hard thin plate which has been cold rolled to a desired thickness as described above is made into a product by partial annealing. This partial annealing is also performed at a temperature lower than the recrystallization temperature.
It is carried out in a temperature range of about 360 ° C. for 1 to 12 hours in accordance with the desired properties of the semi-rigid thin plate. By such partial annealing, both high elongation and Erichsen value and excellent strength (tensile strength) can be obtained, and since the recrystallization temperature is lower than the recrystallization temperature, the surface roughness during Erichsen is also small.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific examples of the present invention as described above will be described. First, an Al-Mn alloy, an Al-Mn-Mg alloy according to the present invention, and an Al-Mn alloy as a comparative example used by the present inventors. 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 using a Hunter continuous casting and rolling mill to produce aluminum coils having a thickness of 6.8 mm. These coils are shown in Table 2 below. A thin plate having a thickness of 0.115 mm was prepared according to the above plate making process, and the tensile strength, elongation and Erichsen value were measured, and the surface roughness during Erichsen was examined. The results are shown in Table 3. That is, it is clear that the product of the present invention has excellent properties in balance of tensile strength, elongation and Erichsen value as compared with the comparative example. Also, it is found that the workability is excellent and the quality is stable.

[0022]

[Table 2]

[0023]

[Table 3]

The accompanying drawings show Example B of the present invention in Table 3 described above.
Changes in tensile strength and elongation with respect to changes in final annealing temperature are also shown for Comparative Examples 1 and 2 and B6 by a conventional production method, that is, Comparative Examples in which 530 ° C. × 2 hours were performed as intermediate annealing. It can be seen that the sample according to the present invention has a small change in tensile strength between about 250 ° C. and 350 ° C. and has low temperature sensitivity, so that a heat treatment operation is easy and a product of stable quality can be obtained.

[0025]

According to the present invention as described above, 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 plate-fin type heat exchangers are used. It is an invention which can obtain a product which is preferable as an aluminum can or an aluminum foil, and has a large industrial effect.

[Brief description of the 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.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI C22F 1/04 C22F 1/04 C (58) Field surveyed (Int.Cl. ⁷ , DB name) C22F 1/00-1/18 C22C 21 / 00-21/18

Claims (1)

(57) [Claims] 1. Mn: 0.05 to 1 wt% or Mn: 0.05 to 1 wt%
1 wt% and Mg: 0.05-0.5 wt%, and further Ti:
0.001 to 0.1% by weight, B: 0.0001 to 0.02% by weight, and Zr: 0.001 to 0.1% by weight, and the balance consists of Al and impurities. In the course of cold rolling, an intermediate annealing treatment is performed at a temperature lower than the recrystallization temperature on the aluminum alloy coil obtained by continuous casting and rolling to a thickness of 20 mm or less, and then the partial annealing after the final cold rolling is also performed. A method for producing an aluminum alloy sheet, which is performed at a temperature lower than a recrystallization temperature.