JP2004263253A - Aluminum alloy hard sheet for can barrel, and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the material for a DI (draw and ironing) can barrel excellent in the balance of strength, low earing ratio, ironing properties and flange formability at a low cost. <P>SOLUTION: The Al alloy hard sheet consists of an Al-Mg-Mn based alloy. Provided that the total of each orientation density of Cu, S and Bs belonging to βfiber in the sheet surface layer is defined as d<SB>0</SB>, the total of each orientation density of Cu, S and Bs belonging to βfiber at the position of 1/4 of the sheet thickness as d<SB>1/4</SB>, the Cube orientation density in the sheet surface layer as C<SB>o</SB>and the Cube orientation density at the position of 1/4 of the sheet thickness as C<SB>1/4</SB>, (d<SB>0</SB>+d<SB>1/4</SB>)>(C<SB>o</SB>+C<SB>1/4</SB>) is satisfied. The solid solution content of Mn is controlled to 0.05 to 0.35% and its electric conductivity to 34 to 45 IACS%. In the production method, an ingot is subjected to homogenizing treatment, then, on hot rolling, the starting temperature is controlled to 350 to 590°C, from a sheet thickness of 50 mm to a finish sheet thickness, the material temperature is controlled to 280 to 450°C, the strain rate in each pass to 2.0 to 350/s, the residence time between the passes to ≤10 min, the average surface temperature of a rolling roll to ≤350°C, the finish material temperature in the hot rolling to 280 to 350°C, the finish sheet thickness to 1.5 to 2.8 mm and the cooling rate to a room temperature to ≤100°C/hr. Thereafter, cold rolling of ≥65% is performed without carrying out process annealing. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００６５】
【表２】

【００６６】
【表３】

【００６７】
【表４】

【００６８】
【表５】

【００６９】
表２〜表５において、製造番号１〜５は、いずれもこの発明で規定する成分組成範囲内の合金を用いて、この発明で規定する製造方法に従って製造した例である。これらの例では、表４、表５に示す通り、耳率が低く、ベーク後の強度も充分に高く、しかもしごき性とフランジ成形性にも優れた材料を得ることができた。
【００７０】
これに対し製造番号６は、合金成分はこの発明で規定する範囲内であるが、製造方法がこの発明で規定する範囲から外れたものである。すなわち熱間圧延における板厚５０ｍｍ以降における最高温度が４７２℃と高く、この発明で規定する２８０〜４５０℃の範囲を外れ、また熱間圧延の上がり温度が２５６℃と低く、この発明で規定する２８０〜３５０℃の範囲を外れ、さらに熱間圧延上がり板の耐力が１４４ＭＰａと高く、この発明で規定する１２０ＭＰａ以下の範囲を外れ、そしてまた熱間圧延板の集合組織と最終板の集合組織も、この発明で規定する範囲を外れたものであって、ＤＩ缶胴用の板として４５°耳率が高く、苛酷しごきの成功率が低く、口拡げ率も劣った。
【００７１】
また製造番号７は合金成分がこの発明で規定する範囲から外れたものであり、ベーク後の強度が不足し（注：ＤＩ缶の耐圧性などの点から、材料の耐力は２４０ＭＰａ以上が必要）、またしごき性とフランジ成形性も劣っていた。
【００７２】
さらに製造番号８から製造番号１０までの場合は、均質化処理あるいは熱間圧延の条件がこの発明で規定する範囲を外れたため、熱間圧延中途からエッジ割れにより熱間圧延の続行が困難となってしまった。
【００７３】
また製造番号１１の場合は、熱間圧延ロールの表面温度がこの発明で規定する範囲の上限を越えてしまったため、４５°耳率が高く、またＤＩ缶のしごき性も劣ってしまった。
【００７４】
そしてまた製造番号１２の場合は、均質化処理条件がこの発明で規定する範囲を外れたため、０°、９０°耳率が高く、またＤＩ缶のしごき性も劣ってしまった。
【００７５】
【発明の効果】
前述の実施例からも明らかなように、この発明によれば、ＤＩ缶胴用硬質板としてバランスの優れた板、すなわち塗装焼付後の強度として高強度を有すると同時に低耳率で、しかもしごき性およびフランジ成形性のいずれもが優れた板を得ることができる。そしてまた、製造方法として、熱間圧延後や冷間圧延中途における中間焼鈍を省略したプロセスで上述のような優れた材料を得ることができるところから、低コストで高品質の材料を得ることができる。[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard plate made of an Al-Mg-Mn-based aluminum alloy used for a can body for a two-piece aluminum can by DI molding (drawing and ironing), and a method for producing the same, in particular, having a low deep drawing ear and coating. Aluminum alloy hard plate for DI can body with high strength after baking and excellent formability during DI processing, such as ironing workability, as well as formability after paint baking, such as flange formability, and its production It is about the method.
[0002]
[Prior art]
Generally, as a manufacturing process of a two-piece aluminum can (DI can), the material for the can body is subjected to DI forming by deep drawing and ironing to form a can body, and then trimmed to a predetermined size and shape. Degrease and wash, paint and print, bake (baking), then neck and flange the can body edge, and seam together with the separately formed can lid Is usually performed.
[0003]
As a material for the DI can body thus manufactured, a hard plate of JIS3004 alloy made of an Al-Mg-Mn alloy has been widely used. This 3004 alloy is excellent in ironing workability and shows relatively good formability even when cold-rolled at a high rolling ratio in order to increase strength, so that it is suitable as a DI can body material. Have been.
[0004]
In addition, as a method for manufacturing such a hard plate for a DI can body made of 3004 alloy, generally, after casting by a DC casting method or the like, a homogenization treatment is applied to the ingot, and a predetermined ingot is further subjected to hot rolling and cold rolling. In general, a method of reducing the sheet thickness and performing intermediate annealing for recrystallization during cold rolling after hot rolling before cold rolling or in the middle of cold rolling.
[0005]
By the way, it is strongly desired to reduce the thickness of a two-piece aluminum can body (DI can), mainly from the viewpoint of material cost reduction. When the thickness is reduced in this way, it is indispensable to increase the strength of the material in order to avoid a problem such as a decrease in the buckling strength of the can caused by the reduction in the thickness.
[0006]
Further, it is desired that the material for the DI can have a small ear ratio at the time of DI molding. That is, a low ear ratio during the DI molding is important from the viewpoint of improving the yield during the DI molding and preventing the can body from being broken due to the cut end of the can body.
[0007]
Further, it is necessary that the moldability of the DI can be excellent at the time of manufacturing the DI can (opening property) and that the ironing property (can-cut resistance) is excellent.
[0008]
Here, any one of these strength, ear ratio, flange formability (mouth expansion property), and ironing property (can-break resistance) is not a matter that any one of them is excellent. It is important that the production method be low, in addition to the above-mentioned requirements from the material characteristics, as well as the production method.
[0009]
By the way, in the conventional method for manufacturing a hard plate for a 3004 alloy can body, intermediate annealing is performed for recrystallization before cold rolling after hot rolling or in the middle of cold rolling as described above. Is usually the case. If the conventional main manufacturing processes are classified from the viewpoint of such intermediate annealing, they can be classified into the following processes (a) to (c).
(A) Hot rolling-batch annealing process
In this method, after normal hot rolling, annealing is performed using a box-type annealing furnace (batch annealing furnace; BAF) having a low heating rate.
(B) Hot rolling-continuous annealing process
In this method, after normal hot rolling, annealing is performed using a continuous annealing furnace (CAL) having a high heating rate.
(C) Cold rolling intermediate continuous annealing process
This is a method of annealing using a continuous annealing furnace with a high heating rate in the middle of cold rolling after ordinary hot rolling.
[0010]
Further, in addition to the above processes (a) to (c), there is also a method as shown in the following (d).
(D) Self-recrystallization process
This is a method in which a material is self-recrystallized (self-annealed) in a hot-rolled state by controlling the rising temperature of hot rolling to be equal to or higher than the recrystallization temperature of the material.
[0011]
When the processes (a), (b) and (d) are applied among the processes (a) to (d) as described above, the ironability of the finally obtained can body is inferior. There is a common problem. Further, when the process (d) is applied, there is a problem that the material strength of the obtained can body is insufficient. Furthermore, when the process (c) is applied, there is a problem that although the ironability is excellent as a can body material, the flange formability is inferior. Further, in the processes (a), (b), and (c) that require annealing for recrystallization after hot rolling, there is a problem that manufacturing costs are relatively high.
[0012]
Here, as a prior art method already proposed as a method for manufacturing a DI can body made of an Al-Mg-Mn-based alloy, for example, there are methods as shown in Patent Documents 1 to 8; Among them, the methods of Patent Documents 1 to 6 require annealing after hot rolling or in the middle of cold rolling, and have a problem in terms of cost as described above.
[0013]
Patent Literature 7 also discloses a method of performing final cold rolling without annealing after hot rolling. However, Patent Literature 7 uses a tandem rolling mill as a hot rolling mill. And a method using a reverse rolling mill (reversing mill, reversing worm mill) is not disclosed. Usually, the optimal hot rolling process conditions are different between the tandem rolling mill and the reverse rolling mill. Therefore, even if the method disclosed in Patent Document 7 is diverted to the case where the reverse rolling mill is used, In fact, it is not always the case that a can body material excellent in the above-mentioned various properties can be obtained immediately.
[0014]
Further, in the method of Patent Document 8, annealing after hot rolling may be omitted, but the method of Patent Document 8 also uses a tandem-type rolling mill as a hot rolling mill. Also, the hot rolling conditions are not strictly defined, and therefore, even if the method of Patent Document 8 is diverted to use a reverse type rolling mill, a DI can body material excellent in the balance of the above-mentioned properties can be obtained. There was no.
[0015]
[Patent Document 1] JP-A-11-256290
[Patent Document 2] JP-A-11-256291
[Patent Document 3] JP-A-11-256292
[Patent Document 4] JP-A-2000-234158
[Patent Document 5] JP-A-2001-40461
[Patent Document 6] JP-A-2002-212691
[Patent Document 7] JP-A-10-310837
[Patent Document 8] JP-A-11-140576
[0016]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and is a material capable of satisfying various characteristics desired as a DI can body material in a well-balanced manner, that is, having high strength, low ear rate, and flange formability, ironing property. In addition to providing an aluminum alloy plate for a DI can body that is excellent in the balance of these various properties and has a good balance of these properties, a hard plate for a high quality DI can body with an excellent balance of such properties is provided. It is an object of the present invention to provide a method of obtaining a high-quality DI can body as described above using a reverse type rolling mill instead of a tandem rolling mill as a hot rolling mill. The purpose is to provide a method suitable for obtaining at low cost.
[0017]
[Means for Solving the Problems]
As a result of various experiments and studies conducted by the present inventors to solve the above-described problems, the texture of the plate, particularly the texture of the portion close to the plate surface, is appropriately controlled, and at the same time, the Mn solid solution amount and the conductivity are adjusted. It has been found that by properly adjusting the balance between the flange formability and the ironability while securing high strength and a low ear ratio, a high-quality DI can body can be obtained. In addition, as a manufacturing method, by strictly controlling the hot rolling conditions, particularly the conditions in the stage after hot rolling from the stage of the plate thickness of 50 mm, annealing for recrystallization after hot rolling is omitted. The present inventors have found that a process capable of obtaining a high-quality DI can body, particularly a process capable of obtaining a high-quality DI can body using a reversing mill type hot rolling mill, can be realized. I've reached the point.
[0018]
More specifically, the aluminum alloy hard plate for a can body according to the first aspect of the present invention includes: Mg 0.5 to 2.0%, Mn 0.5 to 2.0%, Fe 0.1 to 0.7%, Si 0.05 ０．５0.5%, Cu 0.05〜0.5%, the balance being an aluminum alloy consisting of Al and unavoidable impurities, and each of Cu, S, and Bs directions belonging to β fiber of the plate surface layer. D is the sum of the azimuth densities ₀ And the sum of the azimuth densities of the Cu, S, and Bs directions belonging to the β fiber at a position at a depth of 1/4 of the plate thickness in the plate thickness direction from the plate surface is d _1/4 And the cubic density of the Cube azimuth in the plate surface layer is C ₀ And the azimuth density of the Cube azimuth at a position at a depth of 1/4 of the plate thickness in the plate thickness direction from the plate surface is C _1/4 And the following equation
(D ₀ + D _1/4 )> (C ₀ + C _1/4 )
And the Mn solid solution amount is in the range of 0.05 to 0.35% and the conductivity is in the range of 34 to 45 IACS%.
[0019]
The aluminum alloy hard plate for a can body according to the second aspect of the present invention is the aluminum alloy hard plate for a can body according to the first aspect, further comprising, as a component of the aluminum alloy, 0.05 to 0.3% of Cr and 0.05 to 0.3% of Zn. It is characterized by containing one or more of 0.5% and 0.005 to 0.20% of Ti.
[0020]
Further, the method for producing an aluminum alloy hard plate for a can body of the invention according to claim 3 is characterized in that after casting an aluminum alloy having a component composition defined in claim 1 or 2, the aluminum alloy is hardened at a temperature in the range of 520 to 630 ° C. Performing a homogenization treatment for 1 hour or more, then performing hot rolling and winding, and cooling to a temperature of 100 ° C. or less,
(1) The hot rolling start temperature is in the range of 350 to 590 ° C,
(2) During hot rolling from a plate thickness of 50 mm to a rising plate thickness, the material temperature is controlled within a range of 280 to 450 ° C., and the strain rate of each pass is set within a range of 2.0 to 350 / sec. Control and control the residence time between each pass within 10 minutes,
(3) During hot rolling from a plate thickness of 50 mm to a rising plate thickness, the average temperature of the contact portion between the rolling roll and the plate is maintained at 350 ° C. or less,
(4) The material temperature after hot rolling is set to a range of 280 to 350 ° C,
(5) The hot-rolled sheet thickness is in the range of 1.5 to 2.8 mm,
(6) controlling the average cooling rate from a temperature in the range of 280 to 350 ° C. after hot rolling to 100 ° C. or less to 100 ° C./hour or less,
According to the above (1) to (6), the proof strength is 120 MPa or less, and the azimuth density of the Cube orientation in a portion having a depth of 1/4 of the thickness in the thickness direction from the surface of the plate is 5 to 140 times the random orientation. And a hot-rolled sheet in which each of the Cu, S, and Bs orientations belonging to the rolling texture is 10 times or less the random orientation, and 65% or more without intermediate annealing Cold rolling at a rolling rate of
[0021]
Furthermore, the method for producing an aluminum alloy hard plate for a can body according to the invention of claim 4 is the method for producing an aluminum alloy hard plate for a can body according to claim 3, further comprising: The final annealing is carried out by heating to a temperature within the range described above and holding for 0.1 to 24 hours.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the reasons for limiting the component composition of the aluminum alloy used for the aluminum alloy hard plate for a can body of the present invention will be described.
[0023]
Mg:
The addition of Mg is effective in improving the strength due to solid solution of Mg itself, and can be expected to improve the strength by increasing the amount of work hardening accompanying the solid solution of Mg. ₂ It can be expected that the strength will be improved by aging precipitation of Si. Therefore, Mg is an indispensable element for obtaining the strength required for the body of the can. Also, Mg has an effect of increasing dislocations during processing, and is therefore effective for making recrystallized grains finer. However, when the Mg content is less than 0.5%, the above-mentioned effect is small. On the other hand, when the Mg content is more than 2.0%, although high strength is easily obtained, deformation resistance at the time of DI processing is increased and drawability and ironability are reduced. Make it worse. Therefore, the amount of Mg was set in the range of 0.5 to 2.0%.
[0024]
Mn:
Mn is an effective element that contributes to improvement in strength and formability. In particular, in the can body material, which is the intended use of the present invention, ironing is added during DI molding, and therefore Mn is particularly important. Emulsion type lubricants are usually used for ironing aluminum plates, but when the amount of Mn-based crystals is small, lubricating ability is insufficient with only emulsion type lubricants even if they have the same strength. However, there is a possibility that poor appearance such as abrasion and seizure called "goling" may occur. It is known that galling is affected by the size, amount, and type of a crystallized substance, and Mn is an essential element for forming the crystallized substance. If the Mn content is less than 0.5%, the solid lubricating effect of the Mn-based compound cannot be obtained, while if the Mn content exceeds 2.0%, Al ₆ A primary crystal giant intermetallic compound of Mn is generated, which significantly impairs formability. Therefore, the Mn content is set in the range of 0.5 to 2.0%. Further, here, the solute Mn in the product plate has an effect of suppressing recovery during processing and an effect of reducing softening during baking, so that in the present invention, as will be described later, the total Mn amount in the material In addition, it defines the amount of Mn solid solution in the product plate.
[0025]
Fe:
Fe is an element that promotes crystallization and precipitation of Mn, and controls the amount of Mn solid solution in the aluminum matrix and the dispersion state of the Mn-based intermetallic compound. In order to obtain an appropriate compound dispersion state, it is necessary to add Fe according to the amount of Mn added. If the Fe content is less than 0.1%, it is difficult to obtain an appropriate compound dispersion state, while if the Fe content exceeds 0.7%, a primary intermetallic compound is likely to be generated with the addition of Mn. And the moldability is significantly impaired. Therefore, the range of the Fe amount is set to 0.1 to 0.7%.
[0026]
Si:
The addition of Si ₂ It contributes to the improvement of the strength of the can body through age hardening due to the precipitation of the Si-based compound. Si is an element necessary for generating an Al-Mn-Fe-Si-based intermetallic compound and controlling the dispersion state of the Mn-based intermetallic compound. If the Si content is less than 0.05%, the above effects cannot be obtained, while if it exceeds 0.5%, the material becomes too hard due to age hardening, and the formability is impaired. Therefore, the range of the amount of Si is set to 0.05 to 0.5%.
[0027]
Cu:
Cu is dissolved in an aluminum matrix, and contributes to an improvement in strength utilizing precipitation hardening due to precipitation as an Al-Cu-Mg-based precipitate during coating baking. When the Cu content is less than 0.05%, the effect cannot be obtained. On the other hand, when Cu is added in excess of 0.5%, although age hardening is easily obtained, it becomes too hard and impairs formability. Also, the corrosion resistance deteriorates. Therefore, the range of the amount of Cu is set to 0.05 to 0.5%.
[0028]
In addition to the above elements, Al and unavoidable impurities may be basically used, but one or more of Ti, Cr, and Zn may be added as necessary. These Ti, Cr and Zn will be described in more detail.
[0029]
Ti:
In ordinary aluminum alloys, a small amount of Ti is added to refine the ingot crystal grains. In the present invention, a small amount of Ti may be added as needed. However, if the Ti content is less than 0.005%, the effect cannot be obtained. On the other hand, if the Ti content exceeds 0.20%, a giant Al-Ti-based intermetallic compound is crystallized to inhibit formability. Was made in the range of 0.005 to 0.20%. It is known that the effect of refinement of ingot crystal grains can be improved by adding a small amount of B together with Ti. Therefore, in the case of the present invention, addition of a small amount of B together with Ti is permitted. When B is added together with Ti, the effect is not obtained if the B content is less than 0.0001%, and if the B content exceeds 0.05%, Ti-B-based coarse particles are mixed to impair the formability. Therefore, when B is added together with Ti, the amount of B is desirably in the range of 0.0001 to 0.05%.
[0030]
Cr:
Cr is an element effective for improving the strength. However, if it is less than 0.05%, its effect is small, and if it exceeds 0.3%, the formability is reduced due to the formation of giant crystals, which is not preferable. Therefore, the range of the Cr content when Cr is added is set to 0.05 to 0.3%.
[0031]
Zn:
Addition of Zn contributes to the improvement in strength due to aging precipitation of Al-Mg-Zn-based particles. However, if the content is less than 0.05%, the effect cannot be obtained. If it exceeds 0.5%, the contribution to the strength is problematic. No, but deteriorates corrosion resistance. Therefore, the range of the amount of Zr when adding Zn is set to 0.05 to 0.5%.
[0032]
Further, in the aluminum alloy hard plate for a can body of the present invention, it is necessary to not only adjust the component composition of the alloy as described above, but also to appropriately adjust the amount of solid solution elements in the product plate. In the present invention, the amount of solid solution of typical Mn among the solid solution elements is determined, and the conductivity is determined as an index of the total amount of solid solution including other solid solution elements.
[0033]
In other words, solid-solution elements are effective in suppressing recovery and suppressing softening during paint baking.In order to obtain appropriate strength after paint baking, not only the amount of each element added but also the solid solution It is necessary to control the amount appropriately. In the present invention, the Mn solid solution having the greatest effect is set in the range of 0.05 to 0.35%, and the solid solution of Mg, Cu, Si, and Fe other than Mn, By setting the conductivity of the plate as an index within the range of 34 to 45 IACS%, it was possible to obtain the necessary high strength after baking without painting, without impairing the ironing property and the flange formability.
[0034]
Here, if the Mn solid solution amount is less than 0.05%, it becomes difficult to obtain the required strength, while if it exceeds 0.35%, the ironing property and the flange formability deteriorate. Therefore, the Mn solid solution amount is set in the range of 0.05 to 0.35%.
[0035]
If the conductivity of the plate, which is an index of the total solid solution amount of Mg, Cu, Si, Fe, etc. in addition to Mn, is less than 34 IACS%, the total solid solution amount is too large and ironing property and flange formability are poor. On the other hand, if the electrical conductivity exceeds 45 IACS%, the total amount of solid solution may be too small and the strength may be insufficient. Therefore, the electrical conductivity of the plate is set in the range of 34 to 45 IACS%.
[0036]
In addition, in the aluminum alloy hard plate for a can body according to the present invention, it is necessary to appropriately control the texture of the surface of the plate or a portion close to the surface (a portion of the plate surface layer and a portion 板 of the plate thickness). It is important to improve the ironability without adversely affecting the iron.
[0037]
That is, according to the detailed experiments by the inventors of the present application, d ₀ , D _1/4 , C ₀ , C _1/4 , Respectively
d ₀ : Total of each orientation density of Cu orientation, S orientation, and Bs orientation belonging to β fiber in plate surface layer
d _1/4 : The sum of the azimuth densities of the Cu, S, and Bs orientations belonging to the β fiber at a depth of 1/4 of the plate thickness in the plate thickness direction from the plate surface
C ₀ : Orientation density of Cube orientation in plate surface layer
C _1/4 : Azimuth density of Cube orientation at a depth of 1/4 of the plate thickness in the plate thickness direction from the plate surface
If it is specified, the following equation (1)
(D ₀ + D _1/4 )> (C ₀ + C _1/4 …… (1)
By adjusting the texture of the plate so as to satisfy the above, it has been found that the ironing property can be remarkably improved as compared with the related art, and the formula (1) is defined in the present invention. If the formula (1) is not satisfied, the effect of improving the ironing property cannot be obtained sufficiently.
[0038]
For each azimuth density, an incomplete pole figure of {200}, {220}, and {111} was measured by the Schulz reflection method using an X-ray diffractometer, and a three-dimensional crystal orientation analysis (ODF) was performed based on these. ). Here, the Cu orientation is ideally the {111} <112> orientation, the S orientation is the {123} <634> orientation, the Bs orientation is the {110} <112> orientation, and the Cube orientation is the {001} <100> orientation. It is assumed that the azimuth includes those having an azimuth difference of 15 ° around the ideal azimuth.
[0039]
In addition, d ₀ , C ₀ Is defined as the surface layer of the plate, which means the azimuth density measured on the surface of the plate.
[0040]
Next, the manufacturing process of the aluminum alloy hard plate for a can body of the present invention will be described.
[0041]
First, an aluminum alloy ingot having the above-described alloy composition is cast by a DC casting method (semi-continuous casting method) according to a conventional method. Next, the ingot is subjected to a homogenization treatment to homogenize segregation of the ingot and optimize the size and distribution of the Mn, Fe, and Si-based second phase particles. Also, the size and distribution of such second phase particles may affect the texture of the final sheet. If the homogenization treatment temperature is lower than 520 ° C., not only the homogenization effect is insufficient, but also an optimum texture may not be obtained, while if it exceeds 630 ° C., eutectic melting may occur. If the time for the homogenization treatment is less than 1 hour, not only the effect of homogenization will be insufficient, but also an optimum texture may not be obtained. Therefore, the homogenization treatment condition was defined as a temperature within the range of 520 to 630 ° C. for 1 hour or more. The upper limit of the homogenization treatment time is not particularly limited, but is preferably 48 hours or less in view of economy.
[0042]
Hot rolling is performed on the ingot subjected to the homogenization treatment. In the case of the method of the present invention, since a method in which annealing is not performed after hot rolling is applied, it is necessary to recrystallize at a recrystallization rate of 90% or more in a hot-rolled finished plate as described later. In addition, the recrystallization behavior during hot rolling has a great influence on reduction of ear rate and improvement of ironability through texture control. Therefore, in the present invention, not only the hot rolling start temperature and the hot rolling end temperature (hot rolling temperature), but also various conditions from the stage of the thickness of 50 mm to the hot rolling during the hot rolling, and the conditions after the hot rolling. Strictly stipulate the conditions until cooling to a temperature close to room temperature (a temperature of 100 ° C. or less). Specifically, the following conditions (1) to (6) are required.
[0043]
(1) The hot rolling start temperature is in the range of 350 to 590 ° C.
(2) During hot rolling from a plate thickness of 50 mm to a rising plate thickness, the material temperature is controlled within a range of 280 to 450 ° C., and the strain rate of each pass is controlled at 2.0 to 350 / sec. And control the residence time between passes within 10 minutes
(3) During hot rolling from a plate thickness of 50 mm to a rising plate thickness, the average temperature of the contact portion between the rolling roll and the plate is maintained at 350 ° C. or less.
(4) The material temperature after hot rolling is in the range of 280 to 350 ° C.
(5) The hot-rolled finished sheet thickness is in the range of 1.5 to 2.8 mm.
(6) The average cooling rate from the temperature in the range of 280 to 350 ° C after hot rolling to a temperature of 100 ° C or less is controlled to 100 ° C / hour or less.
[0044]
The method of the present invention uses a reversing mill and a reversing worm mill as a finishing mill for hot rolling, or uses a reversing mill as a rolling mill for both rough rolling and finishing rolling of hot rolling. A case is assumed, and the above-mentioned conditions (1) to (6) are also defined as effective conditions at least when a reverse type rolling mill is used for finish rolling. In the above conditions, "during hot rolling from a plate thickness of 50 mm to an increased plate thickness" is included in the finish rolling by the reverse method.
[0045]
Next, the hot rolling conditions (1) to (6) will be described in detail.
[0046]
(1) The hot rolling start temperature is in the range of 350 to 590 ° C:
The hot rolling start temperature has a strong influence on the recovery and recrystallization behavior of the material during hot rolling. If the hot rolling start temperature is lower than 350 ° C., recrystallization is unlikely to occur during rolling, the ductility of the material is reduced, and the edge cracking of the sheet is likely to occur during rolling. On the other hand, if hot rolling is started at a temperature exceeding 590 ° C., coarse crystal grains are likely to be formed, and the surface quality of the sheet is reduced. Therefore, the hot rolling start temperature was set in the range of 350 to 590 ° C.
[0047]
(2) During hot rolling from a plate thickness of 50 mm to a rising plate thickness, the material temperature is controlled within a range of 280 to 450 ° C., and the strain rate of each pass is controlled at 2.0 to 350 / sec. And control the residence time between each pass within 10 minutes:
The hot rolling conditions from the stage of the plate thickness of 50 mm to the finished plate thickness during the hot rolling greatly affect the recrystallization behavior and the formation of an appropriate texture. At this stage, the material temperature, the strain rate of each pass, and the residence time between the passes are determined and combined as described above, thereby adjusting the recrystallization behavior of the hot-rolled sheet and changing the texture of the sheet to hot rolling. By controlling from the stage, the texture in the final plate can satisfy the above expression (1). If the material temperature is lower than 280 ° C. at this stage, the surface quality may be degraded and serious edge cracking may occur during hot rolling. On the other hand, if the material temperature at this stage exceeds 450 ° C., recrystallization proceeds. Prematurely, the required texture cannot be obtained. If the strain rate of each pass at this stage is less than 2.0 / sec, the productivity is reduced. On the other hand, if the strain rate is more than 350 / sec, the edge cracks and the surface quality of the sheet are deteriorated, and the rolling load becomes excessive. May be caused. Further, when the residence time between the passes of the material is 10 minutes or more, the recovery and recrystallization progress during the residence, and a required texture may not be obtained, and the productivity may be reduced. Therefore, these conditions were determined as described above.
[0048]
(3) During hot rolling from a plate thickness of 50 mm to a rising plate thickness, the average temperature (roll surface average temperature) of the contact portion between the rolling roll and the plate is maintained at 350 ° C. or less:
The formation of the texture of the sheet, particularly the texture of the surface layer, is greatly affected by the state of the surface of the rolling roll, particularly its temperature. The effect is small at the stage of a thick plate exceeding 50 mm, but in the range from the plate thickness of 50 mm to the rising plate thickness, the surface temperature of the rolling roll has a great influence on the texture formation of the surface layer of the plate. Here, in the hot rolling, the surface temperature of the rolling roll becomes higher than room temperature due to the contact between the rolling plate and the rolling roll, but if the temperature of the contact portion between the rolling roll and the rolling plate exceeds 350 ° C., An appropriate texture cannot be obtained on the surface layer, and the surface quality of the plate may be degraded. Therefore, in the present invention, the average temperature of the contact portion between the rolling roll and the plate between the plate thickness of 50 mm and the finished plate thickness is kept at 350 ° C. or less.
[0049]
(4) The material temperature after hot rolling is in the range of 280 to 350 ° C:
If the end temperature of hot rolling is lower than 280 ° C., it is difficult to obtain sufficient recrystallization, and if this is cold-rolled to the final thickness without annealing, the ears of the DI can become high and the formability deteriorates. Invite. On the other hand, when the hot rolling end temperature exceeds 350 ° C., the material is completely recrystallized, but the surface quality may be deteriorated. Therefore, the end temperature of the hot rolling is set in the range of 280 to 350 ° C. In addition, even in this range, 290 to 340 ° C. is particularly preferable.
[0050]
(5) The hot-rolled sheet thickness is in the range of 1.5 to 2.8 mm:
When the thickness after hot rolling is less than 1.5 mm, it is difficult to control the thickness accuracy in a hot rolling mill. On the other hand, if the thickness of the hot-rolled sheet exceeds 2.8 mm, the subsequent cold-rolling rate becomes too high, and high strength can be easily obtained, but the ear rate increases. Therefore, the thickness of the hot-rolled sheet was set in the range of 1.5 to 2.8 mm.
[0051]
(6) Controlling the average cooling rate from a temperature in the range of 280 to 350 ° C. after hot rolling to a temperature of 100 ° C. or less to 100 ° C./hour or less:
The cooling process of the hot-rolled material (coil) from a temperature in the range of 290 to 350 ° C. to a temperature of 100 ° C. or less is a progress of recrystallization and a process of growing Cube-oriented crystal grains. If the cooling rate in this process exceeds 100 ° C./hour, recrystallization cannot proceed sufficiently, and the generation of Cube-oriented crystal grains becomes insufficient. As a result, the ear ratio of the final plate cannot be sufficiently reduced, and the moldability may be reduced. Therefore, the average cooling rate in the cooling process from a temperature in the range of 280 to 350 ° C. after the hot rolling to a temperature of 100 ° C. or less was set to 100 ° C./hour or less.
[0052]
According to the above conditions (1) to (6), the hot-rolled sheet is hot-rolled and wound into a coil, and further cooled to a temperature of 100 ° C. or less, and achieves a recrystallization rate of 90% or more by self-annealing. It is possible to finish a low-cost, high-quality final plate on a hot-rolled plate having such a structure of a substantially completely recrystallized state without performing intermediate annealing for recrystallization again thereafter. be able to.
[0053]
Further, as the characteristics of the hot-rolled sheet, the proof strength is 120 MPa or more, and the texture condition is that the azimuth density of the Cube orientation at a depth of 1/4 of the sheet thickness in the sheet thickness direction from the sheet surface is random orientation. And the orientation density of each of the Cu orientation, S orientation, and Bs orientation belonging to the rolling texture is controlled to be 10 times or less the random orientation. Here, when the proof stress of the hot-rolled sheet exceeds 120 MPa, the strength of the final sheet becomes too high, which may cause a reduction in ironing property. If the density of the Cube orientation at a portion corresponding to a thickness of 1/4 in the hot-rolled sheet is less than 5 times the random orientation density, the final sheet tends to have a 45 ° ear, while if it exceeds 140 times, the final sheet has 0-90 ° ears tend to be high. Further, when the orientation density of the Cu, S, and Bs components belonging to the rolling texture in the hot-rolled sheet each exceeds 10 times the random orientation, the 45 ° ear tends to be high in the final sheet, and the ironing property is reduced. There is a risk.
[0054]
The hot-rolled sheet is then cold-rolled to the final sheet thickness without intermediate annealing for recrystallization. Here, the cold rolling reduction needs to be 65% or more. That is, in order to make the final cold rolling reduction less than 65% without performing intermediate annealing, the thickness of the hot-rolled sheet is less than 1 mm in consideration of the thickness of the final product (usually 0.35 to 0.25 mm). This is not only extremely difficult in practical operation, but also the strength of the material due to cold work hardening is reduced, and sufficient material strength may not be obtained. It is also disadvantageous for rate control. Therefore, the cold rolling reduction was set to 65% or more.
[0055]
The final plate (cold rolled plate) obtained as described above may be used as it is in a DI can body, but if necessary, in order to improve the formability by recovering the ductility of the final plate, The cold-rolled sheet may be subjected to final annealing (finish annealing) at a temperature of 80 to 200 ° C. for 0.1 to 24 hours. If the temperature of the final annealing is less than 80 ° C., the effect of improving the formability is insufficient, while if it exceeds 200 ° C., the strength decrease due to softening increases. If the holding time of the final annealing is less than 0.1 hour, the effect of improving the formability will be insufficient, while if it exceeds 24 hours, the effect of improving the formability will be saturated and a problem will arise in terms of cost. It should be noted that the same annealing effect as the above-described final annealing can be obtained even by utilizing the processing heat generated when cold rolling is performed at a high speed.
[0056]
【Example】
Each of the alloy symbols A to G shown in Table 1 was cast by a DC casting method according to a conventional method. The obtained ingot is subjected to a homogenization treatment, subjected to hot rolling, wound into a coil, cooled to 100 ° C. or lower, further subjected to cold rolling to a final sheet thickness, and finalized for a part of the ingot. Annealing was performed to obtain a final plate (product plate). Specific conditions of these processes are shown in production numbers 1 to 12 in Tables 2 and 3. In the hot rolling, a reversing mill was used as a finishing mill, and all rolling at a stage of a plate thickness of 50 mm or less was performed by a reversing mill.
[0057]
Here, at the stage of cooling to a temperature of 100 ° C. or less after the completion of the hot rolling, the strength (tensile strength and proof stress in the rolling direction) of the hot-rolled sheet is examined. The Cube azimuth density, Cu azimuth density, S azimuth density, and Bs azimuth density were measured at a position at a depth of 1/4 of the plate thickness in the thickness direction, and the results are shown in Table 3.
[0058]
In addition, for the final plate, the Cube orientation density C at a portion １ ／ of the plate thickness from the plate surface layer and the plate surface ₀ , C _1/4 In the same manner, the Cu orientation density, S orientation density, and Bs orientation density belonging to the β fiber in the plate surface layer and at a portion 部位 of the plate thickness from the plate surface are examined, and the Cube orientation density C of the plate surface layer is determined. ₀ And the Cube azimuth density C at a portion 板 of the plate thickness from the plate surface _1/4 And the value of the sum (C ₀ + C _1/4 ), And at the same time, the sum d of the respective orientation densities of the Cu, S, and Bs orientations of the plate surface layer ₀ And the total d of the azimuth densities of Cu orientation, S orientation, and Bs orientation at a quarter of the plate thickness from the plate surface _1/4 And the sum (d ₀ + D _1/4 ) Was obtained, and the results are shown in Table 4.
[0059]
Here, the measurement of each orientation density as described above, that is, the measurement of the texture was performed as follows.
[0060]
That is, when obtaining the texture of the surface layer of the sheet thickness, the rolled sheet was used as it was, without etching, as a measurement sample. On the other hand, when obtaining the texture of a portion corresponding to １ ／ of the plate thickness, a measurement sample was obtained by etching from the surface with a NaOH aqueous solution to a portion corresponding to １ ／ of the plate thickness. Then, using an X-ray diffractometer, imperfect pole figures of {200}, {220}, and {111} were measured by the Schulz reflection method, and three-dimensional crystal orientation analysis (ODF) was performed based on these. Note that the Cu orientation is the ideal orientation, the {112} <111> orientation, the S orientation is the {123} <634> orientation, the Bs orientation is the {110} <112> orientation, and the Cube orientation is the {001} <100> orientation. However, those having a misorientation of 15 ° around these ideal orientations were also calculated as crystals of each orientation.
[0061]
Further, the electric conductivity (% IACS) and the Mn solid solution amount of each final plate obtained as described above were also examined, and the results are also shown in Table 4. Here, the conductivity was measured by using an eddy current conductivity measuring device with copper and brass as reference samples.
[0062]
With respect to the final sheet (thin sheet for can body) obtained as described above, the tensile strength (TS), proof stress (YS), and elongation (EL) of the original sheet were obtained using a tensile test piece taken in parallel with the rolling direction. And a tensile strength (TS), a proof stress (YS), and an elongation (EL) after a heat treatment at 200 ° C. for 20 minutes assuming baking of the coating (baking). Further, the ear ratio of the base plate was examined, and the "success rate of severe canning of DI cans" was examined as an index of the ironing property, and the mouth spread rate was examined as an index of the flange formability (mouth spreadability). Tables 4 and 5 show these results.
[0063]
Here, the ear ratio was determined by performing a cup deep drawing test under the conditions of a punch diameter of 32 mm and a blank diameter of 56 mm. The “success rate of DI severe ironing” as an index of ironing property is obtained by extracting the second die in the DI can molding and setting the ironing rates of the first and third dies to 55%, for 100 continuous cans. The ratio of cans that did not cause can breakage in can making was examined. Further, the opening ratio as an index of the flange formability (mouth opening property) is such that the DI can after 4-stage necking is trimmed, washed and baked, and has a gradient of 15 ° in the upper opening portion of the DI can. A test was performed in which the punch was pushed into the material until cracks were generated, and the mouth expansion rate until the cracks were generated was determined by the following equation.
Mouth expansion rate = [R1-R0] × 100%
R0: radius of DI can opening after four-stage necking (29 mm)
R1: radius of the opening when the mouth is expanded to the limit where cracks occur
[0064]
[Table 1]

[0065]
[Table 2]

[0066]
[Table 3]

[0067]
[Table 4]

[0068]
[Table 5]

[0069]
In Tables 2 to 5, Production Nos. 1 to 5 are examples of production using alloys within the component composition range specified in the present invention and according to the manufacturing method specified in the present invention. In these examples, as shown in Tables 4 and 5, it was possible to obtain a material having a low ear ratio, a sufficiently high strength after baking, and excellent ironing properties and flange formability.
[0070]
On the other hand, in the production number 6, the alloy component is within the range specified in the present invention, but the manufacturing method is out of the range specified in the present invention. That is, the maximum temperature in the hot rolling after a thickness of 50 mm or more is as high as 472 ° C., which is outside the range of 280 to 450 ° C. specified in the present invention, and the rising temperature of hot rolling is as low as 256 ° C., which is specified in the present invention. Outside the range of 280 to 350 ° C., the proof strength of the hot-rolled finished sheet is as high as 144 MPa, out of the range of 120 MPa or less specified in the present invention, and the texture of the hot-rolled sheet and the texture of the final sheet are also This is outside the range specified by the present invention, and as a plate for a DI can body, the 45 ° ear ratio is high, the success rate of severe ironing is low, and the mouth opening rate is inferior.
[0071]
In the case of Production No. 7, the alloy component is out of the range specified in the present invention, and the strength after baking is insufficient. (Note: The strength of the material must be 240 MPa or more from the viewpoint of the pressure resistance of the DI can, etc.) Also, the ironing property and the flange formability were inferior.
[0072]
Further, in the case of serial numbers 8 to 10, since the conditions of the homogenization treatment or the hot rolling were out of the range specified in the present invention, it was difficult to continue the hot rolling due to edge cracks during the hot rolling. I have.
[0073]
In the case of the production number 11, the surface temperature of the hot rolling roll exceeded the upper limit of the range specified in the present invention, so that the 45 ° ear ratio was high and the ironing property of the DI can was poor.
[0074]
In the case of the production number 12, the homogenization treatment conditions were out of the range specified in the present invention, so that the 0 ° and 90 ° ear ratios were high, and the ironing property of the DI can was inferior.
[0075]
【The invention's effect】
As is apparent from the above-described embodiment, according to the present invention, a hard plate for a DI can body has an excellent balance, that is, it has a high strength after baking, has a low ear rate, and has a high strength. A plate excellent in both properties and flange formability can be obtained. Further, as a manufacturing method, the above-described excellent material can be obtained by a process in which intermediate annealing is omitted after hot rolling or in the middle of cold rolling. it can.

Claims (4)

Mg 0.5 to 2.0% (mass%, the same applies hereinafter), Mn 0.5 to 2.0%, Fe 0.1 to 0.7%, Si 0.05 to 0.5%, Cu 0.05 to 0.5 %, And the balance is made of an aluminum alloy consisting of Al and unavoidable impurities, and the total of the orientation densities of the Cu, S, and Bs orientations belonging to the β fiber in the surface layer of the sheet is defined as d _0, and the surface of the sheet is determined. , The sum of the azimuth densities of the Cu, S, and Bs orientations belonging to the β fiber at a position at a depth of 板 of the thickness in the thickness direction is d _４, and the azimuth of the Cube orientation in the surface layer of the plate When the density is C ₀ and the azimuth density of the Cube orientation at a position at a depth of 板 of the plate thickness from the plate surface in the plate thickness direction is C _４ , the following formula (d ₀ + d _{４) is obtained.} )> (C ₀ + C _1/4 )
Characterized in that the solid solution amount of Mn is in the range of 0.05 to 0.35% and the electrical conductivity is in the range of 34 to 45 IACS%. The aluminum alloy hard plate for a can body according to claim 1,
The aluminum alloy further comprises one or more of 0.05 to 0.3% Cr, 0.05 to 0.5% Zn, and 0.005 to 0.20% Ti. Aluminum alloy hard plate for can body. After casting the aluminum alloy having the component composition defined in claim 1 or 2, a homogenization treatment is performed at a temperature in the range of 520 to 630 ° C. for 1 hour or more, and then hot rolling is performed. To cool to below 100 ° C
(1) The hot rolling start temperature is in the range of 350 to 590 ° C,
(2) During hot rolling from a plate thickness of 50 mm to a rising plate thickness, the material temperature is controlled within a range of 280 to 450 ° C., and the strain rate of each pass is set within a range of 2.0 to 350 / sec. Control and control the residence time between each pass within 10 minutes,
(3) During hot rolling from a plate thickness of 50 mm to a rising plate thickness, the average temperature of the contact portion between the rolling roll and the plate is maintained at 350 ° C. or less,
(4) The material temperature after hot rolling is set to a range of 280 to 350 ° C,
(5) The hot-rolled sheet thickness is in the range of 1.5 to 2.8 mm,
(6) controlling the average cooling rate from a temperature in the range of 280 to 350 ° C. after hot rolling to 100 ° C. or less to 100 ° C./hour or less,
According to the above (1) to (6), the proof strength is 120 MPa or less, and the azimuth density of the Cube orientation in a portion having a depth of 1/4 of the thickness in the thickness direction from the surface of the plate is 5 to 140 times the random orientation. And hot-rolled sheet having Cu orientation, S orientation, and Bs orientation belonging to the rolling texture, each having an orientation density of 10 times or less of the random orientation,
Further, a method for producing an aluminum alloy hard plate for a can body, wherein cold rolling is performed at a rolling rate of 65% or more without performing intermediate annealing. The method for producing an aluminum alloy hard plate for a can body according to claim 3,
A method for producing an aluminum alloy hard plate for a can body, comprising: performing a final annealing in which the steel sheet is further heated to a temperature in the range of 80 to 200 ° C. and maintained for 0.1 to 24 hours after the cold rolling.