JPH07238355A - Production of hard al alloy sheet for forming - Google Patents

Abstract

PURPOSE:To obtain a hard Al alloy sheet reduced in anisotropy and improved in strength and formability by casting an Al alloy containing specific amounts of Mg, Mn, Cu, Si, and Fe and subjecting the resultant ingot to temp. rise under specific conditions and then to rolling. CONSTITUTION:An Al alloy, having a composition consisting of, by weight, 0.2-2.8% Mg, 0.2-3.0% Mn, 0.1-1.0% Cu, 0.01-0.5% Si, 0.05-1.0% Fe, and the balance Al with inevitable impurities, is cast. The resultant Al alloy ingot is subjected to temp. rise up to 150-300 deg.C at <=300 deg.C/hr temp. rise rate and then to holding at this temp. for 1-30hr. Subsequently, the ingot is subjected to temp. rise up to a homogenizing heat treatment temp. at 300 deg.C/hr temp. rise rate to undergo homogenizing treatment. Then, the ingot is hot-rolled and subjected, in succession, to cold rolling, process annealing, and final cold rolling. Further, final stabilizing heat treatment is done, if necessary. By specifying these heat treatment conditions, the hard Al alloy sheet for forming, capable of reducing the ear rate after deep drawing and ironing, can be obtained.

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 a hard Al alloy plate for molding which is suitable mainly for can bodies.

[0002]

2. Description of the Related Art An Al alloy 2-piece scan is assembled by a can body and a can end by deep drawing and ironing (DI) processing. Among these, can body plate materials are required to have excellent deep drawability, ironing workability, necking workability after paint baking, flanging workability, etc., and are usually Al-Mn-Mg-based JIS3004.
Alloys are often used. Further, recently, in order to reduce the cost, the body material has been made thinner, and it is desired that the strength of the body material is further increased.

[0003]

At present, in particular, the anisotropy of the material often increases the earing rate after deep drawing and ironing, which not only lowers the yield but also causes many problems in manufacturing. . The Al-Mn-Mg-based alloy is a work-hardening alloy, and strength can be obtained by accumulation of strain introduced by cold working.
The 04 alloy has H19 material (work hardening material) and H39 material (stabilized heat treatment material) which have the highest degree of cold workability and have the highest strength.
Therefore, it is difficult to further improve the strength. As a result of various studies in view of the above, the present invention has developed a method for producing an Al-Mn-Mg-based alloy hard plate for forming that can reduce the anisotropy of a can body material and improve the strength and formability. It was done.

[0004]

Means for Solving the Problems That is, the present invention is based on Mg:
0.2-2.8 wt%, Mn: 0.2-3.0 wt%,
Cu: 0.1-1.0 wt%, Si: 0.01-0.5
wt%, Fe: 0.05 to 1.0 wt% and the balance is Al and Al and unavoidable impurities are melt-cast to form an ingot, which is homogenized and heat-treated according to a conventional method, and then hot-rolled. Then, in the manufacturing process of the Al alloy hard plate manufactured by subsequently performing cold rolling and intermediate annealing, final cold rolling, or performing further stabilizing heat treatment, the cast ingot is heated at a heating rate of 300 ° C. / After heating to a temperature of 150 to 300 ° C. at a temperature of not more than hr and holding at a temperature of 150 to 300 ° C. for 1 to 30 hours, subsequently heating to a temperature of homogenizing heat treatment at a temperature rising rate of 300 ° C./hr or less and performing a homogenizing heat treatment. This is a method of manufacturing an Al alloy hard plate for molding.

[0005]

In the present invention, the Al alloy composition is limited as described above for the following reason.

Mg forms a solid solution in the aluminum base material to improve the strength of the alloy. Its content is 0.2 ~
The reason why the content is set to 2.8 wt% is that the effect is small when the content is less than 0.2 wt% and the crack tends to occur at the time of casting and rolling when the content exceeds 2.8 wt% and the yield is reduced.

Mn is an element effective for preventing softening of the alloy during baking of the coating. The amount is set to 0.2 to 3.0 wt% because if it is less than 0.2 wt%, the effect of preventing softening of the alloy is small, and if it exceeds 3.0 wt%, Fe and Si and coarse intermetallic compounds are produced during casting. This is because it adversely affects the properties of the alloy.

[0008] Cu was added to G. P. Zone, S
^, Precipitates phases (intermediate phase) and improves the strength. The amount is set to 0.1 to 1.0 wt% because if the amount is less than 0.1 wt%, the strength improvement is small, and if it exceeds 1.0 wt%, the corrosion resistance decreases.

Si has the effect of precipitating a Mg ₂ Si phase at the time of baking for coating to improve the strength and precipitate solid solution Fe to improve the formability. The amount is set to 0.01 to 0.5 wt%, if the amount is less than 0.01 wt%, the improvement in strength and formability is small, and if it exceeds 0.5 wt%, the formability decreases.

Fe is usually contained as an impurity in an aluminum ingot, but the amount of Fe is 0.05 to 1.0.
If the amount is less than 0.05% by weight, a high-purity aluminum ingot is used, resulting in high cost, and if it exceeds 1.0% by weight, the formability deteriorates. Also,
Inevitable impurities other than the above, such as Zn, Ti, and B, do not impair the effects of the manufacturing method of the present invention as long as they are 0.25 wt% or less.

Next, the heat treatment method for the Al alloy ingot and the function and effect thereof in the method of the present invention will be described. Al-Mn
-The Mg-based alloy ingot generates a Mg ₂ Si phase that is a hardening precipitation phase in a low temperature range of 150 to 300 ° C while the temperature is raised to the homogenizing heat treatment temperature, and becomes a Mg ₂ Si phase in a high temperature range of 300 ° C or higher. An Al (Fe, Mn) Si dispersed phase is non-uniformly deposited on the upper surface of the layer. At temperatures above about 450 ° C, M
The g ₂ Si phase redissolves, leaving only the dispersed phase. When a conventional melt-cast ingot is subjected to homogenizing heat treatment, solidification segregation occurs during casting, so that the distribution of the dispersed phase becomes coarse and non-uniform even after the homogenizing heat treatment. For this reason, a uniform work structure cannot be obtained during the subsequent hot rolling and cold rolling, and the anisotropy of the material is remarkably left in the end, and the earring ratio of the can body after deep drawing and ironing becomes high. . In addition, since coarse Mg ₂ Si phase and S phase (stable phase) preferentially precipitate on the already segregated Al (Fe, Mn) Si dispersed phase at the time of coating baking, finally the distribution of the precipitated phase Becomes uneven,
High strength of alloy cannot be obtained.

The present inventors, based on the above findings,
-Mn-Mg alloy improves the strength and formability of hard plate,
The heat treatment method of the alloy ingot capable of reducing the ear ratio after deep drawing and ironing was examined, and the heat treatment method of the present invention was found. That is, an Al alloy having a predetermined composition is melt cast to form an ingot, which is homogenized and heat-treated, and then hot-rolled, cold-rolled,
As a result of examining the manufacturing process of the hard plate produced by intermediate annealing, final cold rolling or further stabilizing heat treatment, it is possible to perform preliminary heat treatment at low temperature before homogenizing heat treatment of the ingot to improve the above characteristics. It was found to be effective. This is shown in Fig. 1 after melt casting the alloy by the usual method.
As shown in (1), the ingot is first heated at a temperature rising rate of 300 ° C./hr or less, and when (B) the temperature range of 150 to 300 ° C. is reached, the ingot is held at this temperature for 1 to 30 hr, After that, (C) the homogenizing heat treatment temperature is again raised at a heating rate of 300 ° C./hr or less, and then (D) the homogenizing heat treatment is performed to improve the strength and formability of the hard plate and to deep draw. ,
It reduces the ear rate after ironing. After the homogenizing heat treatment, it is cooled (E) to a hot rolling temperature according to a conventional method and then subjected to hot rolling. Further, after the homogenizing heat treatment, the material may be once cooled (E) to room temperature, reheated and subjected to hot rolling.

In the present invention, the temperature rising rate up to the temperature of the preliminary heat treatment and the heat treatment for homogenization is set to 300 ° C./hr or less so that the Al (Fe, Mn) Si dispersed phase is uniformly precipitated while diffusing atoms. This is because when the temperature exceeds 300 ° C./hr, precipitation of the dispersed phase becomes uneven. The pre-heat treatment temperature is set to 150 to 300 ° C. in order to sufficiently nucleate the dispersed phase and finally obtain a uniform distribution of the dispersed phase. ,
On the other hand, if the temperature exceeds 300 ° C., the dispersed phase tends to become coarse. Further, the reason why the temperature is kept at 1 to 30 hr is to obtain a uniform distribution of the dispersed phase. If it is less than 1 hr, the nucleation of the dispersed phase is insufficient, and if it exceeds 30 hr, the alloy is sufficiently formed. The disperse phase becomes coarse before it is homogenized.

In the present invention, each condition of homogenizing heat treatment, hot rolling, cold rolling, intermediate annealing performed if necessary, final cold rolling, and final stabilizing heat treatment performed as necessary is Al. -Mn-Mg-based alloy hard plate (H19, H
The conditions generally used for the production of 39) are adopted.

[0015]

EXAMPLE An Al alloy having the alloy composition shown in Table 1 was melt-cast by a usual method to form an ingot for rolling 400 mm × 15.
00 mm x 2000 mm was manufactured. This ingot was subjected to the heat treatment shown in Table 2 after both sides were ground. That is, in the heat treatment of the present invention, the ingot is first heated to a temperature of 150 to 300 ° C for 30
The temperature is raised at a heating rate of 0 ° C / hr or less, and is 150 to 300 ° C.
At a temperature of 1 to 30 hours and then to the homogenizing heat treatment temperature at a temperature rising rate of 300 ° C./hr or less, 560 ° C.
Then, the homogenization heat treatment was performed for 6 hours. For comparison, the ingot was also heat-treated under the conventional heat-treatment conditions and heat-treatment conditions outside the range of the method of the present invention. Subsequently, the temperature is lowered from the homogenizing heat treatment temperature to the hot rolling temperature, and hot rolling (400 to 300 ° C.) is performed by a usual method to a plate thickness of 5.0 mm, which is cold rolled to 0.8 mm, and then 520 Intermediate annealing at 10 ° C for 10 seconds, and further final cold rolling to obtain a thickness of 0.
A 3 mm plate material (H19) was used. Tensile test, Erichsen bulge test, and ear rate measurement were performed on these plate materials. The tensile test was measured by a JIS No. 5 bulge test piece, and the Erichsen bulge test was measured by the JIS Z2247A method. In addition, ear ratio (blank diameter = φ55m
m, flat bottom punch diameter = φ33 mm). The results are shown in Tables 3-6.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

[Table 5]

[0021]

[Table 6]

As is clear from Tables 3 to 6, the alloy sheet produced by the method of the present invention has a higher elongation than the alloy sheets produced by the conventional production method and the comparative production method, although it has a higher elongation. It can be seen that the moldability and the ear rate are excellent.

[0023]

As described above, according to the method of the present invention, the formability and the ear ratio are particularly excellent as compared with the alloy sheet produced by the conventional production method, and the strength is also improved. Is most suitable as a method for producing a molding material, and it has remarkable effects such as a large contribution to the improvement of the moldability and strength of these materials and the reduction of the material thickness.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a heat treatment method according to the present invention.

[Explanation of symbols]

 A temperature rise B preliminary heat treatment C temperature rise D homogenization heat treatment E cooling

Claims (1)

[Claims] 1. Mg: 0.2 to 2.8 wt%, Mn:
0.2-3.0 wt%, Cu: 0.1-1.0 wt%,
Si: 0.01 to 0.5 wt%, Fe: 0.05 to 1.
An Al alloy containing 0 wt% and the balance of Al and unavoidable impurities is melt-cast to form an ingot, which is homogenized and heat-treated according to a conventional method, and then hot-rolled, followed by cold-rolling and intermediate annealing. In the manufacturing process of the Al alloy hard plate manufactured by performing cold rolling or further final heat treatment for stabilization,
The cast ingot is heated at a temperature rising rate of 300 ° C./hr or less to 1
After heating up to a temperature of 50 to 300 ° C. and holding at a temperature of 150 to 300 ° C. for 1 to 30 hours, subsequently heating rate 300
A method for producing an Al alloy hard plate for forming, which comprises raising the temperature to a homogenizing heat treatment temperature at a temperature of not more than ° C / hr and performing the homogenizing heat treatment.