JP2009019223A - Aluminum alloy sheet superior in heat resistance, manufacturing method therefor, aluminum alloy sheet superior in heat resistance and deep drawability, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy sheet which is superior in heat resistance and can be manufactured without requiring a complicated process; an aluminum alloy sheet superior in heat resistance and deep drawability; and methods for manufacturing the aluminum alloy sheets. <P>SOLUTION: The aluminum alloy sheet superior in heat resistance and deep drawability comprises, by mass%, 0.05 to 1.0% Si, 0.05 to 1.0% Fe, 0.5 to 2.0% Mn, 0.05 to 0.5% Cu, and the balance Al with unavoidable impurities; and has a matrix which contains dissolved Mn in an amount of 40% or more with respect to the Mn content. The aluminum alloy sheet also is (1) in a cold rolled state, and has a yield strength of 130 MPa or higher and a tensile strength of 140 MPa or higher at 200°C, or (2) in a state of being cold-rolled and then annealed, and has a yield strength of 50 MPa or higher, a tensile strength of 70 MPa or higher at 200°C, and a value r<SB>AVE</SB>of 0.7 or more, which is defined by the expression of r<SB>AVE</SB>=(r<SB>0°</SB>+2r<SB>45°</SB>+r<SB>90°</SB>)/4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aluminum alloy plate excellent in heat resistance, an aluminum alloy plate excellent in heat resistance and deep drawability, and a production method thereof.

  JIS 3000-based Al—Mn-based aluminum alloy plates are excellent in formability and corrosion resistance, have little decrease in yield strength after baking, and have been widely used as plates for forming such as aluminum cans and electrical / mechanical equipment.

  In addition, it is required to supply a JIS 3000 alloy plate that is optimal as a material for parts that require heat resistance, such as an aluminum plate for battery cases and an engine cover, and that has good formability as an annealing material at low cost.

  Regarding heat resistance characteristics, in Patent Document 1, a thickness of 4 to 10 mm is obtained by cooling and solidifying by passing between a pair of cooled rolls provided facing each other with a molten aluminum melted with 1.8 to 2.8% by weight of Mn. A method for producing a heat-resistant aluminum plate material is disclosed, characterized in that a plate-shaped ingot is formed and then cold-rolled.

  However, the alloy properties studied here are 0.2% proof stress of a room temperature tensile test of a cold-rolled sheet heat-annealed at 300 to 450 ° C. in an electric furnace, and heat-resistant aluminum with excellent softening resistance It only shows the manufacturing method of the board. In addition, no description regarding formability is found.

  On the other hand, regarding the formability, in Patent Document 2, the production conditions of the Al—Mn—Mg-based aluminum alloy sheet, particularly the hot rolling conditions, and the subsequent annealing conditions are appropriately set, and the Mn solid solution amount in the final sheet is 0. More than 16%, an aluminum alloy sheet is proposed that is excellent in DI formability and also excellent in formability of the can body edge after DI molding and paint baking treatment.

  Specifically, an Al—Mn—Mg based alloy is cast by a DC casting method, homogenized at 530 to 600 ° C., the end temperature of hot rolling is 250 to 320 ° C., and the plate thickness exceeds 2.5 mm. Hot rolling is performed at 3.5 mm or less, the first stage annealing is performed at a heating rate of 100 ° C./hr or less, 330 to 400 ° C. × 1 to 10 hours, and then the second stage annealing is performed to 450 to 600 ° C. × 10 minutes. Then, cold rolling of 85% or more is performed to obtain an aluminum alloy plate having an Mn solid solution amount exceeding 0.16%.

  Patent Document 3 proposes a method for producing an aluminum alloy plate for a beverage can body that is excellent in wrinkling properties at the time of can bottom molding and excellent in heat-resistant softening after baking.

  Specifically, Mg: 0.8 to 1.5%, Mn: 0.5 to 1.5%, Fe: 0.35 to 0.5%, Si: 0.20 to 0.35 by weight ratio %, Cu: 0.1 to 0.3%, Ti: 0.1% or less, B: 0.05% or less, and after manufacturing and chamfering an aluminum alloy ingot containing the remaining Al and inevitable components , A temperature set in advance as the starting temperature of hot rough rolling during the hot rolling after the homogenization treatment when performing the homogenizing treatment in a temperature range of 550 to 620 ° C. The temperature rise rate and the cooling rate in the temperature range below the upper limit of the range are set to 40 ° C./hour or more, and hot rough rolling is performed in a temperature range set in advance as the start temperature of hot rough rolling, and then hot rough rolling The finish time from the end of hot rolling to the start of hot finish rolling (HR-HT time) within 20 minutes, and hot finish rolling is performed at the delivery temperature After performing the cold rolling to a temperature of 140 ° C. or higher of the final pass and the outlet temperature of the rolling pass other than the cold rolling final roll to 110 ° C. or lower, There has been proposed a method for producing an aluminum alloy plate for a beverage can body, characterized in that the cooling after rolling is performed at a cooling rate of up to 80 ° C. at 15 to 30 ° C./hour.

  As described above, conventionally, in order to produce an Al-Mn aluminum alloy sheet having excellent forming processability and at the same time maintaining high Mn solid solution amount and excellent anti-seizure softening property, at the end of hot rolling It is necessary to keep the slab temperature within the appropriate range, and after cold rolling, it is necessary to cold-roll at a predetermined intermediate annealing treatment, a predetermined cold rolling rate, and to carry out a predetermined final annealing treatment, which complicates the process. Therefore, there was a drawback that the cost was increased.

Japanese Patent Laid-Open No. 49-9414 JP-A-8-13109 JP 2006-291326 A

  An object of the present invention is to provide an aluminum alloy plate excellent in heat resistance, an aluminum alloy plate excellent in heat resistance and deep drawability, and a method for producing them, which can be manufactured without requiring a complicated process. .

  In order to achieve the above object, according to the first invention, in mass%, Si: 0.05 to 1.0%, Fe: 0.05 to 1.0%, Mn: 0.5 to 2. 0%, Cu: 0.05 to 0.5%, the balance is made of Al and inevitable impurities, and remains in the cold-rolled state, and the Mn solid solution amount of the matrix is 40% of the Mn content. Thus, an aluminum alloy plate excellent in heat resistance, characterized by having a yield strength at 200 ° C. of 130 MPa or more and a tensile strength of 140 MPa or more is provided.

  A method for producing an aluminum alloy plate according to the first invention is such that a molten metal having the above composition is a twin-belt casting machine and has a thickness of 5 to 15 mm at a solidification cooling rate of 20 to 200 ° C./sec at a quarter of the slab thickness. It is characterized by casting on a slab and cold rolling.

Furthermore, according to the second invention, Si: 0.05-1.0%, Fe: 0.05-1.0%, Mn: 0.5-2.0%, Cu: 0.0. Contains 0.5 to 0.5%, the balance is made of Al and inevitable impurities, and is annealed after cold rolling, the Mn solid solution amount of the matrix is 40% or more of the Mn content, and the yield strength at 200 ° C. Is 50 MPa or more, the tensile strength is 70 MPa or more, and the following formula:
r _AVE = (r _{0 °} + 2r _{45 °} + r _{90 °} ) / 4
[Where r _{0 °} , r _{45 °} and r _{90 °} are the Rankford values in the directions parallel to the cold rolling direction, 45 ° and vertical, respectively]
An aluminum alloy plate excellent in heat resistance and deep drawability is provided, wherein the r _AVE value defined by the above is 0.7 or more.

  According to the first aspect of the method for producing the aluminum alloy sheet of the second invention, the molten metal having the above composition is solidified and cooled at a site of 1/4 of the slab thickness by a twin belt type casting machine at 20 to 200 ° C. After casting into a slab having a thickness of 5 to 15 mm at / sec and performing cold rolling, continuous annealing is performed at 450 to 550 ° C. in a continuous annealing furnace.

  According to the second aspect of the method for producing the aluminum alloy sheet of the second invention, the molten metal having the above composition is solidified and cooled at a portion of 1/4 of the slab thickness by a twin belt type casting machine at 20 to 200 ° C. After casting into a slab having a thickness of 5 to 15 mm at / sec and performing cold rolling, batch annealing is performed at 390 to 450 ° C. in an annealing furnace.

  In the composition corresponding to JIS 3000 series, the solidification cooling rate is limited by a twin belt casting machine, and the ratio of the Mn solid solution amount to the Mn content is limited, so that it is excellent in heat resistance as a cold rolled plate and heat resistant as an annealed plate. An aluminum alloy sheet having excellent properties and deep drawability can be obtained.

  The present inventor made a slab having a thickness of 5 to 15 mm at a solidification cooling rate of 20 to 200 ° C./sec at a slab thickness of 1/4 with a belt-type casting machine using a molten Al—Mn alloy having a composition corresponding to JIS 3000 series. After casting and cold rolling, (1) continuous annealing at 450 to 550 ° C. in a continuous annealing furnace, or (2) batch annealing at 390 to 450 ° C. in an annealing furnace, It has been found that an aluminum alloy plate excellent in deep drawability and heat resistance can be produced.

  According to this manufacturing method, processes such as slab casting by a conventional DC casting machine, double-sided face milling, homogenization treatment, hot rolling, and subsequent intermediate annealing are not required, and the cost can be greatly reduced.

  According to the present invention, by mass%, Si: 0.05-1.0%, Fe: 0.05-1.0%, Mn: 0.5-2.0%, Cu: 0.05-0. A molten alloy containing 5% and the balance substantially consisting of Al and inevitable impurities is cast into a slab having a thickness of 5 to 15 mm by a twin belt type casting machine. Since the solidification cooling rate at a quarter of the slab thickness can be made relatively high at 20 to 200 ° C./sec, precipitation of Mn from the matrix is suppressed, and the amount of Mn solid solution in the matrix can be increased. .

  By winding this slab directly on a coil and performing cold rolling to the final gauge without performing intermediate annealing, an Al—Mn-based aluminum alloy plate having excellent heat resistance can be obtained. Furthermore, as the final annealing treatment, tempering is performed by (1) continuous annealing at 450 to 550 ° C. in a continuous annealing furnace or (2) batch annealing at 390 to 450 ° C. in an annealing furnace. Thereby, it can be set as the Al-Mn type aluminum alloy plate excellent in deep drawability and heat resistance.

  Next, the significance and reasons for limitation of the alloy components of the present invention will be described. In the present application, “%” means “mass%” unless otherwise specified.

[Mn: 0.5 to 2.0%]
Mn, which is an essential element, causes Al— (Fe · Mn) —Si intermetallic compounds having a size of 5 μm or less together with Fe and Si to crystallize uniformly and finely, thereby contributing to an increase in strength by dispersion strengthening. These fine intermetallic compounds become the nuclei of recrystallized grains during the final annealing, but the amount of Mn in the matrix is high, the recrystallization inhibiting action is strong, and the rolling texture remains after the final annealing. _{The AVE} value is increased and the plate is excellent in deep drawability.

  Further, in the thin slab continuous casting machine, since the solidification cooling rate of the molten metal is fast, the tendency of Mn to dissolve in supersaturation increases, and in the present invention in which homogenization treatment and intermediate annealing are not performed, in the matrix in the final plate The Mn solid solution amount is 40% or more of the Mn content. Mn dissolved in the matrix remains a rolled texture after the final annealing, and becomes a plate excellent in deep drawability. Moreover, the strength by holding at a high temperature is higher than that of the DC material by the conventional method, and the plate has excellent heat resistance.

  The range of Mn content is 0.5 to 2.0%. If the Mn content is less than 0.5%, the effect is not sufficient, and the heat resistance is lowered. If it exceeds 2.0%, a coarse intermetallic compound is likely to be produced during casting, and the deep drawability is deteriorated. A preferable Mn content is 0.5 to 1.7%.

[Fe: 0.05 to 1.0%]
Fe, which is an essential element, coexists with Mn and Si to crystallize Al—Fe, Al— (Fe · Mn) —Si based compounds in a thin slab uniformly and finely. Although these fine intermetallic compounds remain in the metal structure after the final annealing, they are very fine, so that the high-temperature strength is increased.

  The range of Fe content is 0.05 to 1.0%. If the Fe content is less than 0.05%, the strength of the final plate becomes too low, and if it exceeds 1.0%, a coarse intermetallic compound is likely to be produced during casting, and the deep drawability may be deteriorated. Because. A preferable range of the Fe content is 0.05 to 0.8%.

[Si: 0.05-1.0%]
Si, which is an essential element, causes Al— (Fe · Mn) —Si intermetallic compounds having a size of 5 μm or less to crystallize uniformly and finely together with Fe and Mn during casting. Although these fine intermetallic compounds remain in the metal structure after the final annealing, they are very fine, so that the high-temperature strength is increased.

  The range of Si content shall be 0.05 to 1.0%. If the Si content is less than 0.05%, the strength of the final plate becomes too low, and if it exceeds 1.0%, a coarse intermetallic compound is likely to be produced during casting, which may deteriorate the deep drawability. Is also not preferred. A preferable range of the Si content is 0.05 to 0.8%.

[Cu: 0.05 to 0.5%]
Cu, which is an essential element, dissolves in the matrix and increases the high-temperature strength. The range of Cu content shall be 0.05-0.5%. If the Cu content is less than 0.05%, the strength of the final annealed plate becomes too low, and if it exceeds 0.5%, the corrosion resistance deteriorates, which is not preferable.

[Arbitrary element: Ti]
Even if Ti is contained in an amount of 0.10% or less, the effect of the present invention is not hindered, it acts as a grain refiner for thin slabs, and casting defects such as slab cracks can be reliably prevented. . When the Ti content is less than 0.005%, the effect is not sufficient, and when the Ti content exceeds 0.10%, a coarse intermetallic compound such as TiAl ₃ is generated at the time of casting. Is significantly reduced. Therefore, the preferable range of Ti content is 0.005 to 0.10%. A more preferable range of the Ti content is 0.005 to 0.05%.

[Arbitrary element: B]
When B is mixed with Ti, the crystal grain refining effect of the ingot is greatly improved. When the B content is less than 0.0005%, the crystal grain refining effect is not sufficient, and it is difficult to reliably prevent casting defects such as slab cracks. When the B content exceeds 0.01%, not only the crystal grain refining effect of the ingot is saturated, but excess TiB ₂ aggregates may act as inclusions in the final annealed plate. Further, there is a possibility that the formability may be deteriorated by causing scratches on the plate surface during deep drawing. Therefore, the preferable range of the B content is 0.0005 to 0.01%.

[Inevitable impurities]
Inevitable impurities are mixed due to the impurity element contained in the aluminum ingot, the return material, the flux, or the like, or the reduction elution of the furnace material silica, the reaction between the melting jig and the molten metal, and the like. Ni, Zn, Ga, V, Ca, Na, etc. are typical elements.

The reason why the conditions of the production method of the present invention are limited will be described.
The slab used for the production of the Al-Mn alloy plate excellent in heat resistance and deep drawability of the present invention is cast by a twin belt type casting machine. The twin-belt casting machine is a method in which molten metal is poured between a pair of rotating belts facing up and down and cooled by water, and the molten metal is solidified by cooling from the belt surface to form a slab. This is a casting machine that draws out a slab continuously and winds it up in a coil.

[Take up a 5-15mm thick slab cast by a twin-belt casting machine]
[Solidification cooling rate at slab thickness 1/4 is 20 to 200 ° C./sec]
In the present invention, the slab to be cast has a thickness of 5 to 15 mm. If the thickness is within this range, a solidification cooling rate of about 20 to 200 ° C./sec can be secured at a slab thickness of ¼, so that a uniform cast structure can be easily formed, and the solid solution amount of Mn in the matrix can be reduced. Can be secured. Moreover, it becomes possible to suppress the size of the intermetallic compound produced | generated at the time of casting solidification to 5 micrometers or less, and the aluminum alloy plate excellent in deep drawability and heat resistance can be manufactured.
The above slab thickness range is also appropriate from the execution side of the belt type casting machine. That is, when the slab thickness is less than 5 mm, the amount of aluminum alloy passing through the casting machine per unit time becomes too small, and casting itself becomes difficult. When the slab thickness exceeds 15 mm, it becomes difficult to wind it as a coil.

(Thin slabs are not homogenized or annealed)
In the present invention, the thin slab wound around the coil is cold-rolled to the final thickness without being subjected to homogenization or intermediate annealing. Since the homogenization and intermediate annealing are not performed, Mn dissolved in supersaturation in the matrix is maintained as it is, and a plate having excellent heat resistance can be manufactured. Furthermore, transition metal elements such as Mn dissolved in the matrix can prevent the movement of dislocations and can sufficiently store the strain energy necessary for recrystallization in the final annealing. For these reasons, the rolling reduction in cold rolling is preferably about 80 to 96%.
Moreover, in this manufacturing method, steps such as double-sided chamfering, homogenization treatment, hot rolling, and intermediate annealing among the complicated steps according to the conventional method are omitted, so that the manufacturing cost can be kept low.

[Continuous annealing is performed at 450 to 550 ° C. in a continuous annealing furnace]
In the present invention, final annealing is performed after cold rolling. This final annealing may be performed in a batch annealing furnace, but is preferably performed in a continuous annealing furnace (CAL). Continuous annealing furnace (CAL) is equipment for continuously solution treatment of coils, etc., equipped with induction heating device for heat treatment, water tank for water cooling, air nozzle for air cooling, etc. It is characterized by.
The annealing temperature by continuous annealing shall be 450-550 degreeC. If it is lower than 450 ° C., redrawing is not sufficient, and deep drawability is reduced. If it exceeds 550 ° C., the recrystallized grains become coarse and the strength of the final annealed sheet is lowered, which is not preferable.

  The holding time at the annealing temperature in the continuous annealing furnace is 40 seconds or less. In the case of holding time of 40 seconds or more, it is necessary to reduce the line speed, which is not preferable because productivity is lowered.

[Batch annealing at 390 to 450 ° C. in an annealing furnace]
The final annealing may be performed by batch annealing in an annealing furnace. The annealing temperature for batch annealing is in the range of 390 to 450 ° C. If it is lower than 390 ° C., redrawing is not sufficient, and deep drawability is reduced. If it exceeds 450 ° C., the recrystallized grains become coarse and the strength of the final annealed sheet is lowered, which is not preferable.

  The holding time at the annealing temperature is in the range of 1 to 10 hours. When the holding time is less than 1 hour, although depending on the rate of temperature increase, the entire coil is not heated uniformly, so a uniform and fine recrystallized structure cannot be obtained. If the holding time exceeds 10 hours, the production cost is too high, which is not preferable.

[Production of sample]
For the CC material, a molten aluminum alloy having the alloy composition shown in Table 1 was melted in a melting furnace, filtered through a ceramic filter, a 10 mm thick slab was cast with a twin-belt continuous casting machine, and wound around a coil. . Thereafter, the cast slab was cold-rolled to a final thickness of 1 mm without being subjected to homogenization or intermediate annealing. The tempering of this cold rolled sheet is H18.

  For the DC material, a molten aluminum alloy having the alloy composition shown in Table 1 is cast into a 1200 mm × 500 mm × 3800 mm slab with a DC casting machine, both sides are cut, and then homogenized at 550 ° C. × 12 hrs in a heat treatment furnace. Subsequently, hot rolling was performed with a hot rolling mill, and a 6 mm thick hot rolled sheet was wound around the coil. Then, it cold-rolled to the final board thickness of 1 mm, without carrying out intermediate annealing. The tempering of this cold rolled sheet is also H18.

  CC material cold-rolled sheets are annealed at a holding temperature of 525 ° C in a continuous annealing line (CAL), while DC material cold-rolled plates are annealed at a holding temperature of 525 ° C in the same continuous annealing furnace. It was. The tempering of these final annealed plates is “O”.

[Measurement of Mn solid solution amount]
Then, about CC material (H18 material, O material) and DC material (H18 material, O material), the solid solution amount of Mn in a matrix was measured by the hot phenol method. Specifically, the plate was decomposed with hot phenol, and the filtered solution was extracted with citric acid, and then measured by ICP emission spectroscopic analysis. The results are shown in Table 2. The ratio of the Mn solid solution amount to the Mn content in the CC material is 40% or more, and the ratio in the DC material is 10% or less.

[Heat resistance (high temperature strength)]
Furthermore, a tensile test piece in the rolling parallel direction was cut out from each plate material and subjected to a warm tensile test at each temperature of 200 ° C., 300 ° C., and 400 ° C., and the proof stress and tensile strength were measured. The results are shown in Table 3.

  Regarding the cold-rolled sheet (H18 material) and each sheet material (O material) after the final annealing, it was found that the CC material had higher proof stress and tensile strength at each temperature than the DC material.

  The CC material (H18 material) has a yield strength of 130 MPa or more and a tensile strength of 140 MPa or more at 200 ° C., a yield strength of 40 MPa or more and a tensile strength of 50 MPa or more at 300 ° C., a yield strength of 25 MPa or more and a tensile strength of 30 MPa or more at 400 ° C. Met.

  The CC material (O material) has a yield strength of 50 MPa or more and a tensile strength of 70 MPa or more at 200 ° C., a yield strength of 40 MPa or more and a tensile strength of 50 MPa or more at 300 ° C., a yield strength of 25 MPa or more and a tensile strength of 30 MPa or more at 400 ° C. Met.

(Deep drawability)
From each plate after annealing, a tensile test piece in the rolling parallel direction, the 45 ° direction of rolling, and the vertical direction of rolling was cut out, a room temperature tensile test was performed, and an r value (Rankford value) was measured. The r _AVE value was calculated by the following formula. The results are shown in Table 4.
r _AVE = (r _{0 °} + 2r _{45 °} + r _{90 °} ) / 4

As shown in Table 4, it was found that the CC material had a higher r _AVE value than the DC material and was excellent in deep drawability.

  ADVANTAGE OF THE INVENTION According to this invention, the aluminum alloy plate excellent in heat resistance and the aluminum alloy plate excellent in heat resistance and deep drawability which can be manufactured without a complicated process, and these manufacturing methods are provided.

Claims (5)

  In mass%, Si: 0.05-1.0%, Fe: 0.05-1.0%, Mn: 0.5-2.0%, Cu: 0.05-0.5% The balance consists of Al and inevitable impurities, and is in a cold-rolled state. The Mn solid solution content of the matrix is 40% or more of the Mn content, the proof stress at 200 ° C. is 130 MPa or more, and the tensile strength is 140 MPa. An aluminum alloy plate excellent in heat resistance characterized by the above. In mass%, Si: 0.05-1.0%, Fe: 0.05-1.0%, Mn: 0.5-2.0%, Cu: 0.05-0.5% The balance is made of Al and inevitable impurities, and is annealed after cold rolling. The Mn solid solution amount of the matrix is 40% or more of the Mn content, the proof stress at 200 ° C. is 50 MPa or more, and the tensile strength is 70 MPa. That is the following formula:
r _AVE = (r _{0 °} + 2r _{45 °} + r _{90 °} ) / 4
[Where r _{0 °} , r _{45 °} and r _{90 °} are the Rankford values in the directions parallel to the cold rolling direction, 45 ° and vertical, respectively]
An aluminum alloy plate excellent in heat resistance and deep drawability, wherein the r _AVE value defined by is 0.7 or more.   The method for producing an aluminum alloy plate according to claim 1, wherein the molten metal having the above composition is formed by a twin-belt casting machine with a thickness of 5 at a solidification cooling rate of 20 to 200 ° C / sec at a quarter of the slab thickness. A method for producing an aluminum alloy plate excellent in heat resistance, which is cast on a slab of ˜15 mm and cold-rolled.   3. The method for producing an aluminum alloy sheet according to claim 2, wherein the molten metal having the above composition is formed at a thickness of 5 at a solidification cooling rate of 20 to 200 [deg.] C./sec. A method for producing an aluminum alloy plate excellent in heat resistance and deep drawability, which is cast on a slab of ˜15 mm, cold-rolled, and then subjected to continuous annealing at 450 to 550 ° C. in a continuous annealing furnace .   3. The method for producing an aluminum alloy sheet according to claim 2, wherein the molten metal having the above composition is formed at a thickness of 5 at a solidification cooling rate of 20 to 200 [deg.] C./sec. A method for producing an aluminum alloy plate excellent in heat resistance and deep drawability, which is cast on a slab of ˜15 mm, subjected to cold rolling, and then subjected to batch annealing at 390 to 450 ° C. in an annealing furnace.