JP6474582B2 - Aluminum alloy plate with excellent formability - Google Patents

Description

  The present invention relates to an aluminum alloy plate and a method for producing the same, and more particularly to a silicon-containing aluminum alloy plate excellent in formability and a method for producing the same.

Conventionally, an aluminum alloy plate is manufactured by casting an aluminum raw material, so-called virgin material, to produce a slab, surface-treating the slab, then performing a soaking treatment, and further performing hot rolling and cold rolling. (For example, see Patent Document 1 and Patent Document 2).
Moreover, in the conventional twin roll type continuous casting, since the soaking process is performed before rolling, the process cost tends to be large (for example, see Non-Patent Document 1 and Non-Patent Document 2).

JP 2004-143511 A JP 7-41896 A

Materials Transactions, Vol. 45, no. 2 (2004) pp. 403to406 Journal of Materials Processing Technology, 140 (2003) pp. 610to615

  However, in the production of such a conventional aluminum alloy sheet, the raw material cost is high, and it is necessary to carry out each process such as chamfering and soaking of the slab, and also corresponds to hot and cold rolling. It took a lot of time and was not sufficient in terms of raw material costs and production efficiency.

  Further, in conventional twin roll type continuous casting, the structure control of the twin roll material has not been established, and segregation is likely to occur in the central part of the thickness of the aluminum alloy plate. There is a problem that a desired product shape cannot be realized because of lowering and moldability.

  The present invention has been made in view of such problems of the prior art. The object of the present invention is to provide a silicon-containing aluminum alloy plate having low raw material costs, excellent production efficiency, and excellent formability. It is in providing the manufacturing method.

  As a result of intensive studies to achieve the above object, the present inventor found that the above object can be achieved by using a low-cost casting alloy or scrap material and imparting a predetermined Si concentration distribution. The invention has been completed.

That is, the silicon-containing aluminum alloy plate of the present invention is a silicon-containing aluminum alloy plate having a Si concentration distribution that varies in the plate thickness direction.
The silicon-containing aluminum alloy sheet, the Si concentration _{(Si max)} in the thickness direction position Si concentration is maximum, the ratio _Si max _{/ Si aver} the average value of the Si concentration in the thickness direction and _{(Si aver)} 1 .0～1.3 der is,
Cu is 0 to 0.2 mass%, Si is 6.5 to 7.5 mass%, Mg is 0.2 to 0.5 mass%, Fe is 0 to 0.8 mass%, and Mn is 0 to 0.0 mass%. It is characterized in that it is contained in a proportion of 6% by mass, and the balance consists of Al and inevitable impurities .
In addition, the aluminum containing aluminum alloy plate of this invention includes both the cast plate as cast and the rolled plate which gave this the rolling process.

Moreover, the manufacturing method of the silicon containing aluminum alloy plate of this invention is a method of manufacturing the above silicon containing aluminum alloy plates.
This manufacturing method produces a plate by vertical twin roll continuous casting,
Next, this plate material is cold-rolled at a reduction rate of 50% or more,
Thereafter, annealing is performed in the range of 400 to 500 ° C.
In addition, in this manufacturing method, when the aluminum alloy plate made into object is a cast plate, said cold rolling and annealing treatment can be abbreviate | omitted.

  According to the present invention, a silicon-containing aluminum alloy having low raw material cost, excellent production efficiency, and excellent formability is obtained by using an inexpensive casting alloy or scrap material and imparting a predetermined Si concentration distribution. A board and a manufacturing method thereof can be provided.

It is an optical microscope structure | tissue photograph which shows the cross section (plate thickness cross section) in the thickness direction of one Example of the silicon-containing aluminum alloy plate of this invention. It is an optical microscope structure | tissue photograph which shows the cross section (plate thickness cross section) in the thickness direction of the other Example of the silicon containing aluminum alloy plate of this invention. It is an optical microscope structure | tissue photograph which shows the cross section (plate thickness cross section) in the thickness direction of an example of the conventional silicon-containing aluminum alloy plate. It is a graph which shows Si concentration distribution of a silicon containing aluminum alloy plate. It is a graph which shows the cold rolling result of a silicon containing aluminum alloy plate. It is a graph which shows the result of the overhang test and X-ray diffraction of a silicon containing aluminum alloy plate.

Hereinafter, the aluminum alloy plate of the present invention will be described in detail.
The aluminum alloy plate of the present invention is a plate made of aluminum alloy containing silicon (Si), and has a Si concentration distribution that varies in the thickness direction (plate thickness direction).
Further, a Si concentration _{(Si max)} in the thickness direction position Si concentration is maximum, the ratio _Si max _{/ Si aver} the average value of the Si concentration in the thickness direction _{(Si aver)} is 1.0 to 1. 3.

  Here, the Si concentration distribution typically has a concentration gradient in which the Si concentration gradually decreases in the direction of the outermost surface located on both sides of the alloy plate from the center of the plate thickness, but is not limited thereto. It is not something. For example, at any two positions adjacent in the direction of the outermost surface on one side from the thickness center, the Si concentration at the position on the thickness center side does not necessarily have to be higher than the Si concentration at the position on the outermost surface side, It may be the same or small.

In general, the Si concentration distribution is configured in a form in which a plurality of layers having the same or substantially the same Si concentration (Si concentration uniform phase) are adjacent (laminated). Typically, an Si concentration uniform phase of about 8% (about 200 μm in the case of an aluminum alloy plate produced by twin roll type continuous casting) of the plate thickness is adjacent (laminated) from the plate thickness center to one outermost surface direction. ).
In this case, the Si concentration distribution is substantially line-symmetric with respect to a line (sheet thickness center line) that passes through the sheet thickness center and is perpendicular to the thickness direction, and thus the Si thickness center phase including the sheet thickness center constitutes the Si concentration distribution. The concentration uniform phase has a thickness of about 8% with respect to the plate thickness (about 200 μm in the above-mentioned twin-roll continuous cast aluminum alloy plate).

In the silicon-containing aluminum alloy plate having the structure as described above, the plate thickness center or the plate thickness center phase often has Si _max. However, if the Si concentration of the plate thickness center phase or the like becomes too high, Even after rolling and annealing, the Si concentration such as the sheet thickness central phase remains high, and the cold rollability and formability may deteriorate.
In contrast, the present invention is typically in the Si concentration uniform phase formed in a thickness direction, the ratio _{Si max} of the maximum value of the Si concentration _{(Si max)} average of Si concentration _{(Si aver)} By controlling the / Si _average within a predetermined range, the cold rolling property and formability of the alloy plate are improved.

That is, in the silicon-containing aluminum alloy sheet of the present invention, the Si concentration _{(Si max)} in the thickness direction position Si concentration becomes the maximum, the average value of the Si concentration in the thickness direction _{(Si aver)} ratio of _{Si max} / When Si _average exceeds 1.3, the Si concentration in the sheet thickness center phase becomes too high, the cold rolling property is inferior, and breakage may occur during rolling.

Further, the silicon-containing aluminum alloy plate of the present invention is subjected to cold rolling and annealing treatment, and (111) plane strength I ₁₁₁ , (200) plane strength I ₂₀₀ , (220) plane strength by X-ray diffraction. For I ₂₂₀ and (311) plane intensity I ₃₁₁ , I ₁₁₁ is I ₃₁₁ or less and I ₂₂₀ or less, I ₂₂₀ / I ₁₁₁ and I ₃₁₁ / I ₁₁₁ are 3.0 or less, and I ₂₀₀ / I ₂₂₀ is 0. .6 to 2.0 is preferable.
When deviating from the above-mentioned X-ray intensity ratio, the formability, particularly the stretchability, may be deteriorated as compared with a conventional general aluminum alloy plate. Conventionally, the formability of the aluminum alloy plate has been improved by developing the (100) plane, which is equivalent to the (200) plane, but by applying appropriate cold rolling and annealing as in the present invention. In addition to the (220) plane, it is possible to develop the (220) plane and the (311) plane in a well-balanced manner, thereby realizing good moldability.

The silicon-containing aluminum alloy plate of the present invention has a Cu content of 0 to 0.2 mass%, a Si content of 6.5 to 7.5 mass%, a Mg content of 0.2 to 0.5 mass%, and a Fe content of 0 to 0.0 mass%. 8% by mass, Mn from 0 to 0.6% by mass, optionally containing Zn from 0 to 0.3% by mass, Ti from 0 to 0.3% by mass, the balance being Al and inevitable impurities Ru consists of.
The effects of the above various constituent elements and the reasons for limiting the numerical values are as follows.

Cu (copper): 0 to 0.2% by mass
Cu is contained in order to improve proof stress and tensile strength. If the Cu content exceeds 0.2% by mass, the corrosion resistance may deteriorate.

Si (silicon): 6.5 to 7.5% by mass
Si is contained in order to improve castability such as hot water flowability. If the Si content is less than 6.5% by mass, the fluidity is low and the castability may be deteriorated. If it exceeds 7.5% by mass, the fluidity is increased, but the elongation and formability may be reduced. is there.

Mg (magnesium): 0.2 to 0.5 mass%
Mg is contained in order to improve proof stress and tensile strength. If the Mg content is less than 0.2% by mass, improvement in yield strength and tensile strength may not be observed, and if it exceeds 0.5% by mass, elongation and formability may be reduced.

Fe (iron): 0 to 0.8 mass%
Fe is contained to prevent seizure. If the Fe content exceeds 0.8% by mass, the elongation and formability may be reduced.

Mn (manganese): 0 to 0.6% by mass
Mn is contained for mitigating adverse effects such as a decrease in ductility due to Fe and for preventing seizure. When the content of Mn exceeds 0.6% by mass, a precipitated phase and coarse crystallized matter may be generated, and elongation and formability may be lowered.

  Inevitable impurities include Zn, Ti, Ni, Pb, Sn, Cr, Sb, Ca, and Na. Usually, these impurities are contained at 0.1% by mass or less.

  The silicon-containing aluminum alloy plate of the present invention described above is excellent in formability. In particular, the overhang property is excellent, and the overhang height described later is typically 27 mm or more.

Next, the automotive part of the present invention will be described.
The automotive part of the present invention is manufactured using the above-mentioned silicon-containing aluminum alloy plate of the present invention. Due to the excellent formability of the aluminum alloy plate, it is excellent in production efficiency and processing accuracy.
Although it does not specifically limit as components for motor vehicles, Panel materials, such as an outer plate panel and an inner plate panel, a heat insulation board, a sound insulation board, a bracket, etc. can be illustrated.

Next, the manufacturing method of the silicon containing aluminum alloy plate of this invention is demonstrated.
The method for producing a silicon-containing aluminum alloy plate of the present invention is a method for producing the above-described silicon-containing aluminum alloy plate of the present invention.
In this manufacturing method, first, a plate material is produced by vertical twin roll continuous casting, and then the plate material is cold-rolled at a reduction rate of 50% or more, and then annealed in the range of 400 to 500 ° C. .

Here, the twin roll type continuous casting is a technique that can directly manufacture a plate material from a molten metal without using a slab or the like, and is a technique in which the molten metal is stretched or rolled by two rollers and a coiler arranged in a vertical shape. A conventionally known method can be applied.
As the molten material, a so-called virgin raw material can be used, but a scrap material or a scrap alloy mixed with an inexpensive casting alloy, for example, wheel scrap, sash scrap, can scrap, or the like can be used.

Moreover, about the board | plate material produced by the twin roll type continuous casting, after cold-rolling at a reduction rate of 50% or more, annealing treatment is performed in the range of 350 to 550 ° C. In some cases, the crystal grains become coarse, and molding such as elongation and overhang height cannot be performed.
In addition, when the annealing temperature is less than 350 ° C., recrystallization becomes incomplete, the elongation and the extrudability deteriorate, and the target formability may not be obtained. When the annealing temperature exceeds 550 ° C., the recrystallized grains are coarse. Therefore, the strength may decrease and the moldability may decrease.
In addition, if the annealing treatment following the cold rolling described above is performed within a temperature range of 350 ° C. to 550 ° C., a silicon-containing aluminum alloy plate satisfying the X-ray intensity ratio and having excellent formability, particularly extensibility, can be obtained. can get. More preferably, by performing the annealing treatment within a temperature range of 400 ° C. to 500 ° C., I ₂₂₀ / I ₁₁₁ and I ₃₁₁ / I ₁₁₁ are 3.0 or less and I ₂₀₀ / I ₂₂₀ is 0.6 as described above. It becomes -2.0, and a moldability improves further.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

(Examples 1 and 2, Comparative Example 3)
Al alloy melts having various chemical component compositions shown in Table 1 were cast by the twin roll continuous casting shown in Table 2 or the DC casting method.
For Examples 1 and 2, the molten alloy of number A in Table 1 was used, and for the comparative example 3, the molten alloy of number A was also used.
In Table 1, an alloy having an Mg content of 2.54% (No. B) and an alloy having an Mn content of 0.97% (No. C) are examples of raw materials outside the preferred range in the present invention.

In the twin roll type continuous casting (Examples 1 and 2), the Al alloy melt containing silicon is fed from a refractory hot water supply nozzle of a twin roll such as a pair of copper molds rotating at a speed of 10 m / min or more. In the meantime, molten metal was poured at a liquidus temperature of + 5 ° C. or more and solidified at a cooling rate of 100 ° C./s or more to produce a cast plate having a plate thickness of 2 mm or more.
In addition, the cast material produced with the twin roll type continuous casting machine was cold-rolled to a plate thickness of 1 mm or less after completion of solidification as necessary. Subsequently, the cold-rolled sheet was annealed at a temperature of 350 to 550 ° C. for 5 minutes or longer to obtain an aluminum alloy sheet of each example.

The structure | tissue photograph image | photographed with the optical microscope of the cross section (plate thickness cross section) in the thickness direction of the obtained alloy plate of Examples 1 and 2 and the comparative example 3 is each shown in FIGS.
Further, the Si concentration at a predetermined interval in the direction from the thickness center (6) to the outermost surface (1) was measured in the manner of surface analysis in the following performance evaluation, and the obtained results are shown in Table 3 and FIG. Show.
The alloy plate of Example 1, the Si concentration _{(Si max)} in the thickness direction position Si concentration is maximum, the ratio _Si max _{/ Si aver} the average value of the thickness direction of the Si concentration _{(Si aver)} is 7.5 / 7.0 = 1.1.

Table 3 shows the Si concentration distribution measured at intervals of about 8% of the plate thickness from the center of the thickness of the silicon-containing aluminum alloy plate produced by vertical twin roll casting to the outermost surface. Si concentration, Si concentration ratio _(Si max _/ Si _aver), and shows the results of cold rolling test of the alloy plate.
Here, in the results of the cold rollability test, “◯” indicates that cold rolling up to a sheet thickness of 0.5 mm was possible, and “×” indicates that a large crack occurred and the sheet was cold down to a sheet thickness of 0.5 mm. Indicates that rolling was impossible.
Also shown obtained Example 1 and 2, Si concentration ratio of alloy plate of Comparative Example _{3 (Si max / Si aver)} , and the results of cold rolling test of the alloy sheet in FIG.

From Table 3, since Example 1 has a Si concentration ratio of 1.1 as described above, Si segregation is small in the plate thickness direction, and the Si concentration in the plate thickness central phase is low, and therefore, good cold rollability is achieved. was gotten.
In Example 2, the Si concentration ratio was 1.2, and Si segregation in the sheet thickness central phase was large, but cold rolling was possible because the Si concentration ratio was appropriately controlled.
In Comparative Example 3, since the Si concentration ratio was as high as 1.8 and there was a lot of Si segregation in the sheet thickness central phase, many cracks occurred during cold rolling and broke during the rolling, making rolling impossible.

(Examples 5-9, Comparative Examples 10 and 11)
The material having the chemical component composition shown in Table 1 is cast by the twin roll casting method or DC casting method shown in Table 2, and if necessary, various cold rolling processes and annealing heat treatments shown in Table 2 are performed. An aluminum alloy plate was produced.

<Performance evaluation>
The following performance evaluation was performed on the alloy plates of the respective examples obtained as described above. The obtained results are shown in Table 4 and FIG. In addition, the surface intensity | strength and diffraction intensity ratio were investigated by irradiating an X-ray with respect to the rolling parallel direction of an aluminum alloy plate.

[Tensile test]
Z2201: JIS No. 5 test piece specified in 1998 was prepared so that the longitudinal direction of the test piece coincided with the rolling direction, and each characteristic value of 0.2% proof stress, tensile strength, and elongation was measured by a tensile test at room temperature. Measure.

[Overhang test]
Test conditions Test piece shape: 200 mm (length) x 200 mm (width) x 0.5 mm (plate thickness)
Wrinkle holding load: 450kN
Punch speed: 10 mm / min
Punch type: φ100mm
Test procedure For the overhang test, a bulge head punch having a diameter of 100 mm was used, a rust preventive oil as a lubricant was applied to a test piece having a plate thickness of 0.5 mm, a length of 200 mm, and a width of 200 mm, and a molding speed of 10 mm. / Min, overhang forming is performed at a wrinkle holding load of 450 kN, and the height (mm) when the test piece is cracked is measured.

[Analysis]
・ Test conditions Acceleration voltage: 20 kV
Measurement area: 200 × 260 μm
Measurement time: 200 sec
Test procedure Fill the resin in the plate thickness cross-section direction (direction parallel to the rolling direction) in the alloy plate of each example, and polish it until it becomes a mirror surface state. Using an X-ray analyzer SEM-EDX (JEOL JSM-5910L) (manufactured by JEOL Ltd.) and a scanning electron microscope (manufactured by Ametech Co., Ltd., trade name EDAX), X-rays are irradiated onto the 200 × 260 μm region of the mirror surface of the alloy plate. Then, concentration analysis of Al and Si is performed.

As shown in Table 4, in the aluminum alloy plate manufactured satisfying the predetermined Si concentration ratio of the present invention shown in Table 3, the formability as compared with Comparative Examples 10 and 11 not satisfying the predetermined Si concentration ratio of the present invention. Excellent results were obtained.
In addition, regarding the X-ray diffraction intensity ratio, for (111) plane intensity I ₁₁₁ , (200) plane intensity I ₂₀₀ , (220) plane intensity I ₂₂₀ , and (311) plane intensity I ₃₁₁ , I ₁₁₁ is I ₃₁₁ or less and and the I ₂₂₀ or _less, I 220 _{/ I 111} and _I 311 _{/ I 111} is 3.0 or _less, I 200 _{/ I 220} is to satisfy the 0.6 to 2.0, as in example 6-8, It was also found that better moldability was obtained for Comparative Examples 10 and 11.

  The aluminum alloy plate of the present invention can be widely used as a component material of not only automobile components but also industrial equipment and household appliances, for example, Al-Si based for applications requiring formability. It is suitable for application to an alloy plate.

Claims (5)

A silicon-containing aluminum alloy plate having a Si concentration distribution that varies in the plate thickness direction,
And Si concentration _{(Si max)} in the thickness direction position Si concentration is maximum, the ratio _Si max _{/ Si aver} the average value of the Si concentration in the thickness direction and _{(Si aver)} is located at 1.0 to 1.3 ,
Cu is 0 to 0.2 mass%, Si is 6.5 to 7.5 mass%, Mg is 0.2 to 0.5 mass%, Fe is 0 to 0.8 mass%, and Mn is 0 to 0.0 mass%. A silicon-containing aluminum alloy plate comprising 6% by mass, the balance being made of Al and inevitable impurities. Cold rolled and annealed,
For (111) plane intensity I ₁₁₁ , (200) plane intensity I ₂₀₀ , (220) plane intensity I ₂₂₀ , and (311) plane intensity I ₃₁₁ by X-ray diffraction,
I ₁₁₁ is less than or equal to I ₃₁₁ and I ₂₂₀ ,
I ₂₂₀ / I ₁₁₁ and I ₃₁₁ / I ₁₁₁ are 3.0 or less,
The silicon-containing aluminum alloy sheet according to claim 1, I ₂₀₀ / _{I 220} is characterized in that it is a 0.6 to 2.0.   An automotive part comprising the silicon-containing aluminum alloy plate according to claim 1 or 2. In producing the silicon-containing aluminum alloy sheet according to claim 1 or 2,
A plate material is produced by vertical twin roll continuous casting,
Next, this plate material is cold-rolled at a reduction rate of 50% or more,
Thereafter, an annealing treatment is performed in the range of 400 to 500 ° C., and the method for producing a silicon-containing aluminum alloy plate is characterized. In producing the silicon-containing aluminum alloy sheet according to claim 1 or 2,
When performing vertical twin-roll continuous casting, molten aluminum alloy containing silicon is poured at a liquidus temperature of + 5 ° C. or more between twin rolls rotating at 10 m / min or more, and 100 ° C./s or more. A method for producing a silicon-containing aluminum alloy plate, characterized by solidifying at a cooling rate to obtain a plate material having a plate thickness of 2 mm or more.

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