JP2007308767A - Method for producing aluminum alloy thick plate, and aluminum alloy thick plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an aluminum alloy thick plate in which productivity is excellent, the control of surface conditions and flatness is facilitated, and plate thickness precision is improved, and to provide an aluminum alloy thick plate. <P>SOLUTION: A melting process (S1) where an aluminum alloy having a composition comprising Mg of a prescribed quantity, further comprising at least one or more kinds selected from Si, Fe, Cu, Mn, Cr, Zn and Ti by prescribed quantity, and the balance Al with inevitable impurities is melted; a gaseous hydrogen removing process (S2) where gaseous hydrogen is removed from the aluminum alloy melted in the melting process (S1); a filtering process (S3) where inclusions are removed from the aluminum alloy freed from the gaseous hydrogen; a casting process (S4) where the aluminum alloy freed from the inclusions is cast, so as to produce a cast ingot; and a slicing process (S6) where the cast ingot is sliced into a prescribed thickness are performed in this order. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an aluminum alloy thick plate and an aluminum alloy thick plate.

In general, aluminum alloy materials such as aluminum alloy thick plates are used in various applications such as base electronics, transfer equipment, semiconductor equipment such as chambers for vacuum equipment, as well as electrical and electronic parts, manufacturing equipment, household goods, and machine parts. Has been.
Such an aluminum alloy material is manufactured by melting and casting an aluminum alloy as a raw material to produce an ingot, homogenizing heat treatment if necessary, and then rolling the ingot to a predetermined thickness. It is general (see, for example, Patent Document 1).

In addition, as a die material used for a press die, steel, cast steel or the like is used for mass production, and a zinc alloy cast material, an aluminum alloy cast material or the like is used for trial production. Further, in recent years, due to the tendency to reduce the variety of products, rolling materials such as rolled aluminum alloys or forged materials have become widespread for medium and small volume production.
JP 2005-344173 A (paragraphs 0037 to 0045)

However, the above-described method for producing an aluminum alloy material by rolling has the following problems.
In the method of rolling after casting, the surface state and flatness of the rolled plate (particularly the flatness in the longitudinal direction) are controlled only by the rolling roll, and a thick oxide film is formed on the rolled plate surface by hot rolling. Due to the formation, there is a problem that it is difficult to control the surface state and the flatness. Also, in the rolling roll, it is difficult to control the plate thickness, so the thickness accuracy is poor, the size of the intermetallic compound is increased at the center in the plate thickness direction, and the cross section in the plate thickness direction when anodized. There was a problem of causing unevenness on the surface. Furthermore, in the case of rolling an ingot, there is a problem in that costs increase due to an increase in work steps due to an increase in the number of rolling operations.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has excellent productivity, easy control of the surface state and flatness, and a method for manufacturing an aluminum alloy thick plate with improved plate thickness accuracy. It aims at providing the obtained aluminum alloy thick plate.

  In order to solve the above-mentioned problem, the method for producing an aluminum alloy thick plate according to claim 1 includes Mg: 1.5 mass% or more and 12.0 mass% or less, and Si: 0.7 mass% or less. Fe: 0.8 mass% or less, Cu: 0.6 mass% or less, Mn: 1.0 mass% or less, Cr: 0.5 mass% or less, Zn: 0.4 mass% or less, Ti: 0.1 A melting step of dissolving an aluminum alloy containing at least one of mass percent or less and the balance being Al and inevitable impurities, and dehydrogenation for removing hydrogen gas from the aluminum alloy dissolved in the melting step A gas process; a filtration process for removing inclusions from the aluminum alloy from which hydrogen gas has been removed in the dehydrogenation gas process; and a casting process for producing an ingot by casting the aluminum alloy from which inclusions have been removed in the filtration process. The casting A slicing step for slicing a predetermined thickness, and the is characterized in that it is carried out in this order.

According to such a manufacturing method, the fineness and strength of the intermetallic compound of the aluminum alloy thick plate are improved by limiting the Mg content of the aluminum alloy thick plate and the content of the predetermined element to a predetermined range. To do.
Also, by removing the hydrogen gas through the dehydrogenation process, the hydrogen concentration in the ingot is limited, and even if the crystal grains in the ingot become coarse, hydrogen accumulates at the grain boundary near the surface of the ingot. It is not concentrated, and the swelling of the ingot and the swelling of the aluminum alloy thick plate caused by the swelling are suppressed, and the potential defect on the thick plate surface that appears as the surface defect of the thick plate is suppressed. Furthermore, the strength of the aluminum alloy thick plate is improved.
Further, inclusions such as oxides and non-metals are removed from the aluminum alloy by the filtration step.
Furthermore, by slicing the ingot, the thickness of the oxide film is reduced, the surface state of the aluminum alloy thick plate, the flatness and the plate thickness accuracy are improved, and the productivity is improved.

  The method for producing an aluminum alloy thick plate according to claim 2 is characterized in that after the casting step, a heat treatment is performed to hold the ingot at a temperature from 400 ° C. to less than the melting point for 1 hour or more.

  According to such a manufacturing method, the internal stress of the aluminum alloy is removed, and the internal structure becomes uniform.

  The method for producing an aluminum alloy thick plate according to claim 3 is characterized in that after the slicing step, a surface smoothing treatment is further performed on the surface of the sliced aluminum alloy thick plate having a predetermined thickness.

  According to such a manufacturing method, the surface state and flatness of the aluminum alloy thick plate are further improved. In addition, the smoothing of the surface eliminates gas accumulation on the thick plate surface.

  The method for producing an aluminum alloy thick plate according to claim 4 is characterized in that the surface smoothing treatment is performed by one or more methods selected from a cutting method, a grinding method, and a polishing method.

  According to such a manufacturing method, the surface state and flatness of the aluminum alloy thick plate are further improved. Moreover, the smoothing of the thick plate surface eliminates gas accumulation.

  The aluminum alloy thick plate according to claim 5 is an aluminum alloy thick plate made of the above-described aluminum alloy, wherein the amount of hydrogen gas is 0.2 ml / 100 g or less, and the crystallized material in the vicinity of the surface and the central portion of the plate thickness in the plate thickness section. The area ratio difference is within 10%.

  According to such an aluminum alloy thick plate, the surface state, flatness, and plate thickness accuracy of the aluminum alloy thick plate are improved, and further, gas accumulation is eliminated by smoothing the thick plate surface.

According to the method for manufacturing an aluminum alloy thick plate according to claim 1 of the present invention, aluminum is removed by removing inclusions such as hydrogen gas, oxides, and non-metals from a molten aluminum alloy having a predetermined composition. While preventing the surface defect of an alloy thick plate, it can improve intensity | strength and can also be set as a high quality ingot in a casting process.
In addition, since the aluminum alloy is manufactured by slicing the ingot, it is not necessary to reduce the thickness by hot rolling like conventional aluminum alloys, and the work process can be omitted and the productivity can be improved. Can be made. Further, unevenness of the surface at the end face of the thick plate is eliminated, the surface state and flatness can be easily controlled, and the plate thickness accuracy can be improved.

  According to the method for manufacturing an aluminum alloy thick plate according to claim 2, the internal stress of the aluminum alloy thick plate can be removed and the internal structure can be made uniform by performing heat treatment on the ingot. Therefore, the surface state and flatness can be improved, and deformation during cutting of the aluminum alloy thick plate can be prevented, so that the machinability can be improved.

  According to the manufacturing method of the aluminum alloy thick plate according to claim 3 and claim 4, since the surface smoothing treatment is performed on the surface of the sliced aluminum alloy thick plate, the surface state and flatness of the aluminum alloy thick plate are further increased. Can be improved. Further, since the gas is not accumulated due to the smoothing of the surface, the degree of vacuum of the chamber can be improved when used in a vacuum apparatus chamber.

  According to the aluminum alloy thick plate according to claim 5, the surface condition, flatness and plate thickness accuracy of the aluminum alloy thick plate are good, and there is no gas accumulation due to the smoothing of the surface. It can be a thick plate. Further, the surface appearance after the alumite treatment in the plate thickness section is less likely to be uneven. Therefore, it can be used for a wide variety of applications, and can be recycled to other applications.

Next, with reference to drawings, the manufacturing method of the aluminum alloy thick plate and aluminum alloy thick plate which concern on this invention are demonstrated in detail. In the drawings to be referred to, FIG. 1 is a diagram showing a flow of a manufacturing method of an aluminum alloy thick plate.
As shown in FIG. 1, the manufacturing method of an aluminum alloy thick plate (hereinafter referred to as “thick plate” as appropriate) includes a melting step (S1) for dissolving the aluminum alloy, a dehydrogenation gas step (S2), and a filtration step ( S3), the casting step (S4), and the slicing step (S6) are performed in this order. Further, if necessary, a heat treatment step (S5) may be included after the casting step (S4), and a surface smoothing step (S7) may be included after the slicing step (S6).

  In this manufacturing method, first, an aluminum alloy as a raw material is melted by the melting step (S1). In the aluminum alloy dissolved in the melting step (S1), hydrogen gas is removed in the dehydrogenation gas step (S2), and inclusions such as oxides and nonmetals are removed in the filtration step (S3). Next, this aluminum alloy is cast in the casting step (S4) to become an ingot, and this ingot is heat-treated in the heat treatment step (S5) as necessary, and then in the slicing step (S6), a predetermined thickness. It is sliced. In addition, you may perform a surface smoothing process by a surface smoothing process process (S7) after a slice process (S6) as needed.

Next, each process in the manufacturing method of an aluminum alloy thick plate is demonstrated.
<Dissolution process>
The melting step (S1) contains a predetermined amount of Mg, and further includes a predetermined amount of at least one of Si, Fe, Cu, Mn, Cr, Zn, and Ti, with the balance being Al and inevitable. This is a step of melting an aluminum alloy composed of mechanical impurities.
The reason why the content of each component is limited to the numerical values will be described below.

[Mg: 1.5% by mass or more and 12.0% by mass or less]
Mg has the effect of improving the strength of the aluminum alloy. If the Mg content is less than 1.5% by mass, this effect is small. On the other hand, if the Mg content exceeds 12.0% by mass, the castability is remarkably deteriorated and product production becomes impossible.

The aluminum alloy contains Mg as an essential component, and further contains at least one of the following Si, Fe, Cu, Mn, Cr, Zn, and Ti.
[Si: 0.7% by mass or less]
Si has the effect of improving the strength of the aluminum alloy. Si is usually mixed into the aluminum alloy as a metal impurity, and in the casting step (S4) and the like, the Al- (Fe)-(Mn) -Si based metal is combined with Mn and Fe in the ingot. To give a compound. When the Si content exceeds 0.7% by mass, a coarse intermetallic compound is generated in the ingot, and unevenness of the surface appearance after the alumite treatment tends to occur. Therefore, the Si content is 0.7% by mass or less.

[Fe: 0.8% by mass or less]
Fe has the effect of refining and stabilizing the crystal grains of the aluminum alloy and improving the strength. Fe is usually mixed into the aluminum alloy as a metal base impurity, and an Al—Fe— (Mn) — (Si) intermetallic compound is formed in the ingot in combination with Mn and Si in the casting step (S4) and the like. Let When the Fe content exceeds 0.8% by mass, a coarse intermetallic compound is generated in the ingot, and unevenness of the surface appearance after the alumite treatment tends to occur. Therefore, the Fe content is set to 0.8 mass% or less.

[Cu: 0.6% by mass or less]
Cu has the effect of improving the strength of the aluminum alloy plate. However, a content of Cu of 0.6% by mass is sufficient to ensure strength that can withstand use as a thick plate. Therefore, the Cu content is 0.6% by mass or less.

[Mn: 1.0% by mass or less]
Mn has the effect of improving the strength by dissolving in an aluminum alloy. On the other hand, when the content of Mn exceeds 1.0% by mass, a coarse intermetallic compound is generated, and unevenness of the surface appearance after the alumite treatment tends to occur. Therefore, Mn content shall be 1.0 mass% or less.

[Cr: 0.5% by mass or less]
Cr is precipitated as a fine compound in the casting step (S4) and the heat treatment step (S5), and has the effect of suppressing crystal grain growth. If the Cr content exceeds 0.5% by mass, coarse Al—Cr intermetallic compounds as primary crystals are formed, and unevenness in the surface appearance after anodizing is likely to occur. Therefore, the Cr content is 0.5% by mass or less.

[Zn: 0.4 mass% or less]
Zn has the effect of improving the strength of the aluminum alloy. However, a content of Zn of 0.4% by mass is sufficient to ensure a strength that can be used as a thick plate. Therefore, the Zn content is set to 0.4 mass% or less.

[Ti: 0.1% by mass or less]
Ti has the effect of refining the crystal grains of the ingot. Even if the Ti content exceeds 0.1% by mass, the effect is saturated. Therefore, the Ti content is 0.1% by mass or less.

  Moreover, if content of V, B, etc. as an unavoidable impurity is 0.01 mass% or less, respectively, it does not affect the characteristic of the aluminum alloy thick plate of this invention.

<Dehydrogenation gas process>
The dehydrogenation gas step (S2) is a step of removing hydrogen gas from the aluminum alloy melted in the melting step (S1).
Hydrogen gas is generated from hydrogen in fuel, water adhering to metal, etc., and other organic substances. If a large amount of hydrogen gas is contained, it may cause pinholes or weaken the product. In addition, hydrogen accumulates and concentrates at the grain boundaries near the surface of the ingot, causing bulges in the ingot and creaking of the aluminum alloy thick plate due to the bulges, and the surface of the thick plate that appears as a surface defect of the thick plate. Potential defects arise.

Therefore, the hydrogen gas is preferably 0.2 ml or less in 100 g of the aluminum alloy, and more preferably 0.1 ml or less.
The removal of hydrogen gas in the dehydrogenation gas process can be suitably performed by performing fluxing, chlorine refining, in-line refining, or the like on the molten metal. If it uses, it can remove more suitably.

  Here, the concentration of hydrogen gas in the ingot is, for example, a sample cut out from the ingot before homogenization heat treatment and subjected to ultrasonic cleaning with alcohol and acetone. (LIS AO6-1993). The concentration of hydrogen gas in the aluminum alloy thick plate is, for example, a sample cut out from the aluminum alloy thick plate, immersed in NaOH, the oxide film on the surface removed with nitric acid, and subjected to ultrasonic cleaning with alcohol and acetone. , By vacuum heating extraction capacity method (LIS AO6-1993).

<Filtration process>
The filtration step (S3) is a step of mainly removing oxides and non-metallic inclusions from the aluminum alloy with a filtration device.
The filtration device is provided with a ceramic tube using alumina having a particle size of, for example, about 1 mm, and the oxides and inclusions can be removed by passing molten metal through the tube.
By these dehydrogenation gas and filtration, in the casting step (S4), an aluminum alloy with high quality can be made into an ingot. In addition, since deposition of oxide deposits (dross) can be suppressed, labor for removing dross can be reduced.

<Casting process>
The casting step (S4) is, for example, a step for producing an ingot by forming and solidifying a molten aluminum alloy into a predetermined shape such as a rectangular parallelepiped shape in a casting apparatus configured to include a water-cooled mold. It is.
As a casting method, a semi-continuous casting method can be used.
In the semi-continuous casting method, molten metal is poured from above into a metal water-cooled mold with an open bottom, and the solidified metal is continuously removed from the bottom of the water-cooled mold to obtain an ingot of a predetermined thickness. It is. The semi-continuous casting method may be performed either vertically or horizontally.

<Slicing process>
The slicing step (S6) is a step of slicing the ingot cast by the casting step (S4) to a predetermined thickness.
As the slicing method, a slab slicing method can be used.
The slab slicing method is a method of slicing an ingot produced by the above-described semi-continuous casting method with a band saw cutter or the like to cut the ingot in the casting direction, whereby an aluminum alloy thick plate having a predetermined thickness can be obtained. Manufactured. Here, the thickness of the aluminum alloy thick plate is preferably 15 to 200 mm, but is not particularly limited, and can be appropriately changed depending on the use of the aluminum alloy thick plate.

As a method of slicing, it is preferable to use a band saw, but it is not particularly limited, and it may be cut by a circular saw cutter. Moreover, you may cut | disconnect by a laser, water pressure, etc.
Thus, by slicing the ingot, an aluminum alloy thick plate superior in surface condition, flatness, plate thickness accuracy, etc., compared with the rolled material, for example, in the evaluation of flatness, per 1 m of casting direction It is possible to obtain a thick plate having a flatness (warping amount) of 0.4 mm or less / 1 m length and a plate thickness accuracy of ± 100 μm or less.

Before slicing the ingot produced in the casting step (S4), heat treatment for the purpose of removing internal stress and homogenizing the internal structure may be performed as necessary.
<Heat treatment process>
The heat treatment step (S5) is a step in which the ingot produced in the casting step (S4) is heat treated (homogenized heat treatment).
The homogenization heat treatment is carried out by maintaining at a treatment temperature of 400 ° C. to a temperature lower than the melting point for 1 hour or longer according to a conventional method.

  When the treatment temperature of the homogenization heat treatment is less than 400 ° C., the amount of internal stress removed is small, and the solute elements segregated during casting are not sufficiently homogenized, so that the effect of the heat treatment is small. Accordingly, the processing temperature is set to 400 ° C. or higher. Further, when the processing temperature exceeds the melting point, a phenomenon called burning in which a part of the ingot surface is melted is likely to cause a surface defect of the aluminum alloy thick plate. Accordingly, the processing temperature is set to the melting point or lower. On the other hand, when the treatment time is less than 1 hour, the solid solution of the intermetallic compound is insufficient and the precipitation tends to occur. Therefore, processing time shall be 1 hour or more.

The aluminum alloy thick plate manufactured by the above-described manufacturing method has a surface for removing crystallized substances and oxides formed on the surface of the thick plate as necessary, and for eliminating gas accumulation on the surface of the thick plate. Smoothing processing may be performed.
<Surface smoothing process>
The surface smoothing treatment step (S7) is a step of smoothing the surface of the aluminum alloy thick plate sliced by the slicing step (S6).
As the surface smoothing treatment method, a cutting method such as end mill cutting or diamond bite cutting, a grinding method in which the surface is ground with a grindstone, a polishing method such as buffing, or the like can be used, but it is not limited thereto. .

Here, the vacuum apparatus chamber, which is one of the uses of the aluminum alloy thick plate, releases the adsorbed gas from the inner surface of the chamber when the pressure is reduced to a high vacuum, or the gas atoms dissolved in the thick plate. The degree of vacuum decreases due to the release to the surface. Therefore, it takes a long time to reach the target degree of vacuum, and the production efficiency decreases. Therefore, the aluminum alloy thick plate used in the chamber has a small amount of gas adsorbed on the surface of the thick plate located in the inner part of the chamber, and gas atoms dissolved in the thick plate may not be released even when the vacuum is high. Desired.
Therefore, when an aluminum alloy thick plate is used for a chamber, it is particularly effective to perform a surface smoothing treatment.

  As described above, the aluminum alloy thick plate obtained by the manufacturing method described above has good surface condition, flatness, and plate thickness accuracy. Therefore, in addition to semiconductor-related devices such as base substrates, transfer devices, vacuum device chambers, etc., it can be used for various applications such as electrical and electronic parts, manufacturing equipment, daily necessities, mechanical parts, etc. Recycling is also possible.

Next, the aluminum alloy thick plate according to the present invention will be described.
<Aluminum alloy plate>
The aluminum alloy thick plate is made of the above-described aluminum alloy (Al-Mg alloy), the hydrogen concentration in the alloy is 0.2 ml / 100 g or less, and the intermetallic compound in the vicinity of the surface and the center of the plate thickness in the plate thickness section. The difference in the area ratio of (crystallized product) is within 10%.
Note that the hydrogen concentration can be controlled by the manufacturing method described above.
Here, since the color tone after anodization varies depending on the area ratio of the Al-Fe-Mn crystallized product, if the difference in area ratio exceeds 10%, color tone unevenness after anodization occurs. On the other hand, if it is within 10%, color tone unevenness does not occur.

In other words, in the case of a rolled material, the size of the intermetallic compound is increased at the center in the plate thickness direction, so that uneven color tone occurs in the cross section when anodized, but when sliced from the ingot, the distribution of the intermetallic compound Since the state is averaged and the difference in the area ratio of the crystallized material in the vicinity of the surface and in the central portion of the plate thickness is small, color tone unevenness does not occur.
As a method for measuring such an area ratio, the vicinity of the surface of the plate thickness (for example, defined as the position of the plate thickness 1/8) and the center portion of the plate thickness (for example, defined as the position of the plate thickness 1/2). )) By measuring the area ratio of the crystallized product.
Specifically, in the plate thickness section, the image magnification is 1000 times, the field of view is 20 fields or more by image processing with the SEM composition image, and the area ratio of the Al-Fe-Mn based crystallized substance is obtained. .

  Regarding the corrosion resistance, the base substrate and the transfer device are used in a clean room, and therefore general corrosion resistance is not necessary. Even when used in a chamber for a vacuum apparatus, severe corrosion resistance is unnecessary because the environment is less exposed to corrosive gases.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

Next, the effect of the embodiment that satisfies the claims of the present invention will be specifically described in comparison with a comparative example that departs from the claims of the present invention.
[Example 1]
First, an aluminum alloy having the composition shown in Table 1 was dissolved, subjected to dehydrogenation gas treatment and filtration, and then cast to produce an ingot having a thickness of 500 mm. The produced ingot was heated at 500 ° C. for 4 hours and subjected to a homogenization heat treatment. This ingot was sliced or hot-rolled to produce an aluminum alloy thick plate (sliced material, hot-rolled material) having a thickness of 20 mm.
The following tests were performed on the sliced material and the hot rolled material.

<Flatness evaluation test>
For the flatness evaluation, the amount of warpage (flatness) per 1 m in the casting direction was measured for the slice material, and the amount of warpage (flatness) per 1 m in the rolling direction was measured for the hot rolled material. A flatness of 0.4 mm / 1 m or less was accepted (O), and a flatness exceeding 0.4 mm / 1 m was rejected (X).
The results are shown in Table 2.

<Strength test>
The strength was measured by preparing a JIS No. 5 test piece from an aluminum alloy thick plate, performing a tensile test, and measuring the tensile strength and 0.2% proof stress.
Those having a tensile strength of 180 N / mm ² or more were evaluated as acceptable (◯), and those having a tensile strength of less than 180 N / mm ² were evaluated as unacceptable (x).

<Alumite evaluation test>
The alumite evaluation was performed by observing the appearance of the surface and cross section of the aluminum alloy thick plate.
An alumite film having a thickness of 10 μm was formed on the surface and cross section of an aluminum alloy thick plate (sliced material, hot rolled material) by sulfuric acid alumite treatment (15% sulfuric acid, 20 ° C., current density 2 A / dm ² ). The appearance of the surface and the cross section of the thick plate was observed, and those having no unevenness in the appearance were determined to be acceptable (◯), and those having the unevenness were determined to be unacceptable (x).
In addition, since the difference of the area ratio of the crystallized substance of the surface vicinity and plate | board thickness center part in a plate | board thickness cross section affects alumite property, the area ratio of the crystallized substance of the surface vicinity and plate | board thickness center part was calculated | required.
As a method for measuring the area ratio, in the cross section of the plate thickness, image processing is performed with an SEM composition image, the observation magnification is 1000 times, the field of view is 20 fields or more, the position near the plate thickness surface (1/8 position) and the plate The measurement was performed by measuring the area ratio of the crystallized product at the thickness center (1/2 position).
The results are shown in Table 2.
[Example 2]
First, an aluminum alloy (alloy component 3) having the composition of number 3 shown in Table 1 was dissolved, subjected to dehydrogenation gas treatment and filtration, and then cast to produce an ingot having a thickness of 500 mm. The produced ingot was subjected to homogenization heat treatment under the conditions shown in Table 3. This ingot was sliced to produce an aluminum alloy thick plate (slicing material) having a thickness of 20 mm.
About this slice material, the flatness evaluation test was done.
<Flatness evaluation test>
In the flatness evaluation, the amount of warpage (flatness) per 1 m in the casting direction was measured. A flatness of 0.4 mm / 1 m or less was accepted (◯), and a flatness of 0.25 mm / 1 m or less was judged good (◎).
The results are shown in Table 3.

As shown in Table 2, the slicing materials (alloy components 1 to 13, 15 to 21) had less processing distortion and small warpage. That is, the flatness was good.
In the alloy component 14, since Mg exceeded the upper limit, casting cracks occurred and production was impossible.
In the alloy component 13, since the Mg content was less than the lower limit, the strength was insufficient.
Alloy components 1 to 13, 17, 20, and 21 did not cause unevenness in the appearance of the surface of the aluminum alloy thick plate after the alumite treatment.
In alloy components 15, 16, 18, and 19, the contents of Si, Fe, Mn, and Cr exceeded the upper limit values, respectively, so that an intermetallic compound was generated, and the surface appearance after the alumite treatment was uneven.
About alloy components 1-13, 15-21, the nonuniformity did not arise in the external appearance of the cross section after the alumite process of the aluminum alloy thick board.

On the other hand, with respect to the hot rolled material (alloy components 1 to 13, 15 to 21), processing strain was accumulated and warpage was large in the rolling direction. That is, the flatness was poor.
In the alloy component 14, since Mg exceeded the upper limit, casting cracks occurred and production was impossible.
In the alloy component 13, since the Mg content was less than the lower limit, the strength was insufficient.
In alloy components 15, 16, 18, and 19, the contents of Si, Fe, Mn, and Cr exceeded the upper limit values, respectively, so that an intermetallic compound was generated, and the surface appearance after the alumite treatment was uneven.
About the alloy components 1-13, 15-21, the nonuniformity was produced in the external appearance of the cross section after the alumite process of the aluminum alloy thick board.

Moreover, about the hot-rolled material hot-rolled, the difference of the crystallized area ratio of the plate | board thickness surface vicinity and plate | board thickness center part in a plate | board thickness cross section exceeded 10%.
In addition, about the alloy components 17, 20, and 21 of a slicing material, content of Cu, Zn, and Ti exceeds an upper limit, respectively, The effect is saturated, and it is inferior to economical efficiency.

  As shown in Table 3, in Examples 1 and 2, since the conditions of the homogenization heat treatment satisfied the scope of the present invention, the flatness was good. In Example 3, since the homogenization heat treatment was not performed, the flatness was an acceptable value, but was slightly inferior to that obtained by the homogenization heat treatment. In Example 4, since the processing temperature of the homogenization heat treatment was less than 400 ° C., the flatness was an acceptable value, but it was slightly inferior to that satisfying the processing temperature condition. In Example 5, burning occurred and production was impossible.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and can be modified without departing from the scope of the present invention.

It is a figure which shows the flow of the manufacturing method of an aluminum alloy thick board.

Explanation of symbols

S1 Dissolution process S2 Dehydrogenation gas process S3 Filtration process S4 Casting process S5 Heat treatment process S6 Slicing process S7 Surface smoothing process

Claims (5)

Mg: 1.5% by mass or more and 12.0% by mass or less, Si: 0.7% by mass or less, Fe: 0.8% by mass or less, Cu: 0.6% by mass or less, Mn: 1 0.0% by mass or less, Cr: 0.5% by mass or less, Zn: 0.4% by mass or less, Ti: 0.1% by mass or less, and the balance is Al and inevitable A melting step of melting an aluminum alloy composed of impurities;
A dehydrogenation gas step of removing hydrogen gas from the aluminum alloy dissolved in the melting step;
A filtration step of removing inclusions from the aluminum alloy from which hydrogen gas has been removed in the dehydrogenation gas step;
A casting process for producing an ingot by casting an aluminum alloy from which inclusions have been removed in the filtration process;
And a slicing step of slicing the ingot to a predetermined thickness in this order.   2. The method for producing an aluminum alloy thick plate according to claim 1, wherein after the casting step, heat treatment is performed to hold the ingot at a temperature from 400 ° C. to a temperature lower than the melting point for 1 hour or more.   3. The method for producing an aluminum alloy thick plate according to claim 1, wherein after the slicing step, a surface smoothing process is further performed on the surface of the sliced aluminum alloy thick plate having a predetermined thickness. .   The method for producing an aluminum alloy thick plate according to claim 3, wherein the surface smoothing treatment is performed by at least one method selected from a cutting method, a grinding method, and a polishing method.   The aluminum alloy thick plate made of the aluminum alloy according to claim 1, wherein the amount of hydrogen gas is 0.2 ml / 100 g or less, and the difference in the area ratio of the crystallized material in the vicinity of the surface and the central portion of the plate thickness is within 10%. An aluminum alloy thick plate characterized by the above.

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