JPH0633202A - Manufacture of aluminum alloy sheet for di forming - Google Patents

Abstract

PURPOSE:To improve the formability of an aluminum alloy sheet while its strength is maintained by suppressing the generation of the deposition of the metastable phase (Q<1> phase) of a Q phase (Al-Cu-Mg-Si series) with a specified size or below therein. CONSTITUTION:The formation of the Al-Cu-Mg-Si series deposition with <100nm size is suppressed to obtain the Al alloy sheet good in formability, particularly in ironability. The ingot of an Al alloy contg. 0.8 to 1.5% Mn, 0.7 to 1.3% Mg, 0.15 to 0.3% Cu, <0.25% Si and 0.3 to 0.7% Fe, and the balance Al with inevitable impurities is subjected to homogenizing treatment and hot rolling and is immediately subjected to cold rolling at <100 deg.C to regulate its sheet thickness into a final one, which is annealed at 130 to 280 deg.C for <=10min at >=100 deg.C/min temp. raising rate.

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 for forming, and more particularly to a method for producing an aluminum alloy sheet for DI forming used for forming by ironing a DI can and the like. .

[0002]

2. Description of the Related Art AA3004 alloy (Al-1.25 wt% Mn-1.05 wt% Mg alloy) has hitherto been used as a body material for aluminum beer cans or general beverage cans. This alloy is originally used because it is excellent in formability to some extent by cold rolling with a high workability and has the strength required as a body material. However, in recent years, there has been a demand for thinner materials for the purpose of further cost reduction, and in response to this, the strength required for the body material of food and drink cans has become higher than before. As one developed to improve the strength, Japanese Patent Laid-Open No. 52-
No. 105509, which utilizes precipitation of Mg ₂ Si, or Japanese Patent Application Laid-Open No. 57-120648, which uses a precipitation hardening method using an Al—Cu—Mg-based precipitate, there is a method for producing an aluminum alloy sheet. Are known. On the other hand, improving the productivity by reducing defects in the molding process as a method of cost reduction is also a major issue. In particular, cracking during ironing becomes a problem due to the progress of thinner and higher strength. Therefore, the interaction between precipitates and cold rolling was examined.
No. 5 publication is known. In the studies up to now, the improvement in strength and the improvement in moldability are in conflict with each other, and a material capable of obtaining high strength is generally inferior in moldability, and sufficient results have not been obtained.

[0003]

In the present invention, in consideration of such a situation, as a result of investigating a dispersed phase which respectively influences strength and formability, as a result, DI formability, particularly ironing, while maintaining the strength at a high level. This is to develop a method for producing an aluminum alloy sheet for DI molding with improved properties.

That is, according to the invention of claim 1, Mn 0.8 to
1.5%, Mg 0.7 to 1.3%, Cu 0.15 to 0.
Immediately after homogenizing and hot rolling an Al alloy ingot containing 3%, less than 0.25% Si, and 0.3 to 0.7% Fe, and the balance consisting of Al and unavoidable impurities. 10
Aluminum for DI forming, which is characterized by performing cold rolling at a temperature of less than 0 ° C. to obtain a final plate thickness and performing annealing at a temperature of 130 to 280 ° C. within 10 minutes at a temperature rising rate of 100 ° C./min or more. It is a manufacturing method of an alloy plate, and the invention according to claim 2 has Mn 0.8 to 1.5% and Mg 0.7 to 1.3.
%, Cu 0.15-0.3%, Si less than 0.25%, F
The aluminum alloy ingot containing 0.3 to 0.7% of e and the balance of Al and unavoidable impurities is homogenized and hot-rolled, and then subjected to intermediate annealing at a temperature of 300 to 400 ° C. After that, cold rolling is performed at a temperature of less than 100 ° C. to obtain the final plate thickness, and the temperature is raised at a rate of 100 ° C./min or more to
It is a method for producing an aluminum alloy sheet for DI forming, characterized in that annealing at a temperature of 30 to 280 ° C. is performed within 10 minutes. The invention according to claim 3 has Mn of 0.8 to 1.5.
%, Mg 0.7 to 1.3%, Cu 0.15 to 0.3%,
Immediately after applying homogenization treatment and hot rolling to an aluminum alloy ingot containing Si of less than 0.25% and Fe of 0.3 to 0.7%, and the balance of Al and unavoidable impurities, 40
Intermediate annealing is performed at a temperature of more than 0 ° C and 600 ° C or less, and 10
Cool to less than 100 ° C at a cooling rate of ℃ / min or more, and
Cold-rolled to a final thickness of less than 0 ° C, 10
A method for producing an aluminum alloy sheet for DI forming, characterized in that annealing at a temperature of 130 to 280 ° C. is performed within 10 minutes at a temperature rising rate of 0 ° C./min or more. The invention according to claim 4 provides Mn0. 8-1.5%, Mg 0.7-1.3%, C
u 0.15-0.3%, Si less than 0.25%, Fe0.
An aluminum alloy ingot containing 3 to 0.7%, the balance of which is Al and inevitable impurities, is homogenized and hot-rolled, and then cold-rolled to over 400 ° C and 600 ° C.
Perform intermediate annealing at the following temperatures, cool to less than 100 ° C at a cooling rate of 10 ° C / min or more, and perform cold rolling at a temperature of less than 100 ° C to obtain the final plate thickness, and increase the temperature to 100 ° C / min or more. It is a method for producing an aluminum alloy sheet for DI forming, characterized in that annealing at a temperature of 130 to 280 ° C. is performed within 10 minutes.

[0005]

The present invention makes it possible to produce an aluminum alloy sheet for DI molding having excellent properties by identifying the presence of a second phase, which has a bad influence on the formability, among various dispersed phases, and controlling these. It was done. In the case of the alloy of the present invention, as the fine second phase, precipitates mainly generated in the step of increasing the temperature of the material during plate production or can manufacturing are raised. Precipitates generally have a greater effect of improving the strength as the density becomes finer. In particular, Al-having a size of 100 to 200 nm as described in JP-A-57-120648.
It is said that the Mg-Cu based precipitate (metastable phase of S phase) greatly contributes to the strength improvement. However, a metastable phase (Q 'of a Q phase (Al-Cu-Mg-Si system) having a size of 100 nm or less is used.
It was found that the phase) also contributes to the improvement of strength, but on the other hand, it significantly reduces the formability, especially the ironing formability. By suppressing the generation of this precipitate, while maintaining the strength,
The object of the present invention of improving moldability can be achieved.

The present compounds (S phase and Q phase) occur on the dislocation cells or in the aluminum parent phase. The former is mainly spherical or lump-shaped, and the latter is needle-shaped or rod-shaped. In the case of needle-shaped precipitates, the size of the precipitates here is
It refers to the length in the longitudinal direction. The precipitate (Al
-Cu-Mg-Si system) forms a cluster state or GP zone in which the constituent elements Cu, Mg, and Si are integrated at specific positions as a pre-stage of forming a compound. DI
Formability is adversely affected by the present cluster state or GP zone. When a cold rolling temperature or final annealing is applied as a method for determining whether the precipitates of this system are in the initial state, it can be easily determined by maintaining the temperature for a long time and generating the above Q'phase.

The manufacturing conditions in the present invention are the above Al--Cu.
The present invention provides a manufacturing method having high strength and moldability by setting manufacturing conditions such that an Mg-Si compound or its cluster or GP zone does not occur before DI molding.

Next, the reasons for limiting the alloy composition in the present invention will be described. Mn is an element necessary to form an intermetallic compound with Fe and Si and prevent seizure on the die during ironing. If it is less than 0.8%, this effect is small and it is not suitable for molding for a long time.
On the other hand, if it exceeds 1.5%, a huge compound is likely to be formed under normal casting conditions, and there is a high possibility that a large second phase will be a starting point of crack generation during molding described later. Fe forms S, which forms a compound that impairs the moldability described later, in addition to the above effects.
It has the effect of taking in and fixing i. In order to bring about the latter effect, addition of 0.3% or more is required. However, addition of more than 0.7% leads to formation of a giant compound, like the Mn element. Here, when performing a continuous casting method or the like in which the cooling rate during casting is remarkably high, the size of the above compound can be suppressed to a small value, so that the addition amounts of Mn and Fe can be further doubled. Similar to Cu, Mg is an important element that improves the strength of the present alloy by mainly forming a solid solution. In addition, by making it a supersaturated solid solution state by solution heat treatment and quenching, Mg ₂ Si can be used at the time of heat treatment at about 200 ° C. in coating baking after can forming.
Alternatively, an Al-Mg-Cu based precipitate can be formed to further improve the strength. If the added amount of Mg is less than 0.7%, the required strength cannot be maintained, and if it exceeds 1.3%, scoring tends to occur. By using a special casting method with a fast solidification rate, the density of Mn-based precipitates having high seizure resistance can be increased, and the amount of added Mg can be increased to 2.
It is possible to increase up to 5%. Cu can be expected to have the same effect as Mg. If it is less than 0.15%, the effect of improving the strength cannot be expected, and if it exceeds 0.3%, the formability is impaired and a problem occurs in terms of corrosion resistance. Although Si has a low solid solution hardening property by itself, the fine compound formed in the initial stage of heat treatment serves as a nucleation site for precipitates of other elements, thereby promoting precipitation of other elements. Therefore, the addition of Si reduces the solid solution amount of Fe and Mn and promotes the precipitation of Al-Mg-Cu-based compound that causes precipitation hardening. Also, by adding more Si, finer A
l-Cu-Mg-Si-based compound (Al ₅ Cu ₂ Mg ₈ S
a new metastable phase of the Q phase of i ₆ ) is generated. These precipitates are effective in improving the strength, but the latter compound is finer than the former compound and remarkably reduces the formability. Therefore, the amount of Si added needs to be less than 0.25%.

The production method of the present invention will be described. The alloy of the present invention is Al-Mn-F which improves scoring resistance.
A homogenization treatment and hot rolling for the purpose of stabilizing the ear rate by forming an e-Si-based compound or precipitating the solid solution Mn are required. Immediate annealing may be performed immediately after hot rolling or after cold rolling for the purpose of improving the ear ratio or the strength. Here, fine Al which is a problem of the present invention
-Cu-Mg-Si-based precipitate is 200 in normal heat treatment.
When the temperature is 100 ° C. or higher, or in the case of precipitation during processing, it occurs remarkably at a temperature of 100 ° C. or higher, and when it is 300 ° C. or higher, coarsening occurs and the influence on the formability is reduced. Therefore, the intermediate annealing temperature is set to 300 ° C or higher. Furthermore, the intermediate annealing temperature is 40
When the temperature exceeds 0 ° C., the solid solution amount of Mg or Cu increases, so that the precipitation of the Q ′ phase after the intermediate annealing is promoted. Therefore, when the intermediate annealing temperature exceeds 400 ° C., precipitation of the Q ′ phase during subsequent cooling also poses a problem. Cooling rate 10 ℃ /
If it is less than a minute, Q'phase is precipitated during cooling. 600
If the temperature exceeds ℃, the precipitation of Q'phase cannot be suppressed. Therefore, when the intermediate annealing temperature is higher than 400 ° C and lower than 600 ° C, the cooling rate is limited as described above.

Further, after cold rolling to the final plate thickness, low temperature annealing is performed to bring about partial recovery of dislocations, thereby improving deep drawing property or overhanging property. If the temperature is lower than 130 ° C, this effect cannot be obtained, and if the temperature exceeds 280 ° C, the strength is remarkably reduced. The processing time required for the partial recovery of dislocations that bring about the above effects is significantly shorter than the time required for the formation of the Q'phase produced by the heat treatment. Therefore, by performing the treatment at a temperature rising rate of 100 ° C./minute or more and for a short time of 10 minutes or less, it is possible to improve the squeezing and projecting properties without impairing the DI moldability.

By the alloy composition and the manufacturing conditions described above, it is possible to suppress the formation of Al-Cu-Mg-Si based precipitates having a size of less than 100 nm, and to obtain an aluminum alloy sheet having good formability, especially ironing formability. it can.

[0012]

EXAMPLES Next, the present invention will be described in more detail by way of examples. Example 1 A manufacturing experiment shown in Table 2 was conducted using a water-cooled casting ingot having a thickness of 500 mm and an alloy composition shown in Table 1. That is, after homogenizing treatment at 600 ° C. for 5 hours and making a plate with a thickness of 3 mm by ordinary hot rolling, immediately or at 300
After performing intermediate annealing at a temperature of up to 400 ° C. for 2 hours, cold rolling in which the temperature during rolling was controlled by changing the rolling speed was performed to obtain a rolled sheet having a sheet thickness of 0.30 mm. Further, these rolled sheets were subjected to final annealing under various conditions to obtain test materials. The following microstructure observations, mechanical performance tests, and moldability evaluations were performed on these test materials. As for the microstructure observation, about a fine precipitate, using a transmission electron microscope,
The average length of the precipitate was measured by observing at a magnification of 100,000 times, and the precipitate was identified by energy dispersive elemental analysis and electron diffraction. Further, in the case of an ordinary molded body, the proof stress value of the material after the baking treatment is a particular problem. Therefore, as the mechanical performance of the test material, the proof stress value after heat treatment for 15 minutes at 200 ° C. corresponding to the baking treatment was measured. As a method for evaluating formability, ironing workability was evaluated by the number of cracked cans by continuously forming 1000 standard cans with a capacity of 350 ml under the condition that the plate thickness reduction rate was kept constant at 64%. did. As evaluation criteria, no cracks: excellent, 1 to 4 cans cracked: current level, 5 or more cans cracked: inferior. On the other hand, the drawability was evaluated by a universal drawing tester manufactured by Erichsen Co., Ltd. with a punch diameter of 33 mm and a limiting drawing ratio (LDR). (LDR = greater than 1.95: excellent, 1.9 to 1.95: current level, less than 1.9:
Inferior). Table 3 shows these results.

[0013]

[Table 1]

[0014]

[Table 2]

[0015]

[Table 3]

As is clear from Table 3, the product No. 1 to
No. 4 is the conventional product No. Compared with No. 8, the yield value after heat treatment was comparable, and it was excellent in draw formability and ironing workability. On the other hand, the alloy composition or the manufacturing condition is out of the range of the present invention, the comparative product No. It is understood that the ironing workability of 5 to 7 is poor.

Example 2 A manufacturing experiment shown in Table 4 was conducted using a water-cooled casting ingot having a composition shown in Table 1 and having a thickness of 500 mm.
That is, after homogenizing treatment at 600 ° C. for 5 hours and making a plate having a thickness of 3 mm by normal hot rolling, immediately or after cold rolling, the temperature is more than 400 ° C. and 600 ° C. or less for 2 hours. Intermediate annealing is applied, cooling is performed by controlling the cooling rate,
A cold rolled sheet having a thickness of 0.30 mm was obtained by cold rolling in which the rolling temperature was controlled by changing the rolling speed. Further, these rolled sheets were subjected to final annealing under various conditions to obtain test materials. Microstructure observation, mechanical performance test, and moldability evaluation were performed on these test materials by the same method as in Example 1. Table 5 shows these results.

[0018]

[Table 4]

[0019]

[Table 5]

As is apparent from Table 5, the product No. of the present invention is 11
Nos. 14 to 14 are conventional products. Compared with No. 18, the yield value after heat treatment was comparable, and it was excellent in draw formability and ironing workability. On the other hand, the comparative product No. whose alloy composition or manufacturing conditions are out of the range of the present invention. It can be seen that the ironing workability of 15 to 17 is inferior.

[0021]

As described above, according to the present invention, it is possible to obtain an aluminum alloy sheet having excellent strength and DI formability, especially ironing workability, and it is possible to achieve a remarkable effect industrially.

Claims (4)

[Claims] 1. Mn 0.8-1.5% (weight% or less same), Mg 0.7-1.3%, Cu 0.15-0.3
%, Si less than 0.25%, Fe 0.3 to 0.7%, and the balance of 10% immediately after the homogenization treatment and the hot rolling of the Al alloy ingot, the balance of which is Al and inevitable impurities.
Aluminum for DI forming, which is characterized by performing cold rolling at a temperature of less than 0 ° C. to obtain a final plate thickness and performing annealing at a temperature of 130 to 280 ° C. within 10 minutes at a temperature rising rate of 100 ° C./min or more. Method for manufacturing alloy plate. 2. Mn 0.8-1.5%, Mg 0.7-
Homogenizing treatment to an aluminum alloy ingot containing 1.3%, Cu 0.15 to 0.3%, Si less than 0.25%, Fe 0.3 to 0.7%, and the balance Al and unavoidable impurities. After performing hot rolling, intermediate annealing was performed at a temperature of 300 to 400 ° C., and then cold rolling was performed at a temperature of less than 100 ° C. to obtain the final plate thickness, and a heating rate of 100 ° C./min or more. The method for producing an aluminum alloy sheet for DI molding, comprising: annealing at a temperature of 130 to 280 ° C. for 10 minutes or less. 3. Mn 0.8-1.5%, Mg 0.7-
Homogenizing treatment to an aluminum alloy ingot containing 1.3%, Cu 0.15 to 0.3%, Si less than 0.25%, Fe 0.3 to 0.7%, and the balance Al and unavoidable impurities. Immediately after hot rolling, the temperature exceeds 400 ℃ and 600
Perform intermediate annealing at a temperature of ℃ or less, cool to less than 100 ° C at a cooling rate of 10 ° C / min or more, and perform cold rolling at a temperature of less than 100 ° C to obtain a final plate thickness of 100 ° C / min or more. A method for producing an aluminum alloy sheet for DI forming, which comprises performing annealing at a temperature rising rate of 130 to 280 ° C. within 10 minutes. 4. Mn 0.8-1.5%, Mg 0.7-
Homogenizing treatment to an aluminum alloy ingot containing 1.3%, Cu 0.15 to 0.3%, Si less than 0.25%, Fe 0.3 to 0.7%, and the balance Al and unavoidable impurities. After hot rolling, cold rolling is performed, intermediate annealing is performed at a temperature higher than 400 ° C and lower than 600 ° C, cooled to less than 100 ° C at a cooling rate of 10 ° C / minute or higher, and lower than 100 ° C. Cold rolling at the temperature of
Annealing at a temperature of 130-280 ° C for 1 minute or more at a heating rate of 1 minute or more
A method for producing an aluminum alloy plate for DI molding, which is performed within 0 minutes.