TWI568860B - Aluminum alloy plate - Google Patents

Description

Aluminum alloy plate

The present invention relates to an aluminum alloy sheet, and more particularly to an aluminum alloy sheet excellent in design.

In order to satisfy the quality required as a target product, aluminum alloy sheets used in various industrial fields have been studied intensively for mechanical properties such as tensile strength, endurance, elongation, and bending workability.

Moreover, the mechanical properties of the aluminum alloy sheet will affect the quality of the product, and therefore it is an extremely important matter. Under the condition that the mechanical properties are not bad, the design of the enthusiasm for buying and selling customers is also considered to be an important matter.

Therefore, the following technique has been proposed regarding a technique for improving the designability of an aluminum alloy plate.

For example, Patent Document 1 proposes an aluminum alloy material for grain pattern development, which is characterized by containing Si: 0.05 to 0.15 wt%, Fe: 0.13 to 0.35 wt%, and Mg: 2.0 to 5.0 wt%. Mn+Cr: 0.15~0.80wt%, further containing Ti: 0.005~0.15wt%, or Ti: 0.005~0.15wt% and B: 0.0005~ 0.05 wt%, the balance is composed of Al and other impurities.

[current technical literature] [Patent Literature]

[Patent Document 1]: JP-A-2005-325420

The technique of Patent Document 1 is a technique for exhibiting a crystal grain pattern having a large particle diameter on the surface of a plate. However, in order to prevent grain refinement, it is only a very low pressure of 1 to 6% (preferably 2 to 4%). The cold rolling is carried out at a lower rate (in detail, cold rolling after annealing).

As a result, the technique of Patent Document 1 exhibits a small contrast between crystal grains and crystal grains on the surface of the sheet, and is not excellent in design.

Therefore, the aluminum alloy sheet of the present invention has an object of providing an aluminum alloy sheet having a large grain size crystal grain on the surface of the sheet and having excellent contrast between the crystal grains and the crystal grains.

In other words, the aluminum alloy sheet of the present invention contains Mg: 2.0 to 6.0% by mass, Mn + Cr: 0.01 to 0.20% by mass, Fe: 0.20% by mass or less, Si: 0.10% by mass or less, and the balance is Al and Inevitable impurities, the average grain size of the surface of the plate is 1 to 10 mm, and the Cube orientation distribution density of the plate surface is 20 or less with respect to the random orientation.

According to the aluminum alloy plate, since the average crystal grain diameter is within a predetermined range, a crystal grain pattern having a large particle diameter of 1 mm or more can be formed on the surface of the plate.

Further, according to the aluminum alloy sheet, since the content of Mn + Cr is within a predetermined range, the reduction ratio of cold rolling (in detail, cold rolling after annealing) can be set large, and as a result, it can be large. The cold rolling of the reduction ratio makes the contrast between the crystal grains and the crystal grains clear.

In addition, according to the aluminum alloy plate, since the Cube orientation distribution density is 20 or less, the effect of sharp contrast between crystal grains and crystal grains can be obtained.

Further, in the prior art of Patent Document 1, since cold rolling which is performed at a very low reduction ratio is an essential requirement, the strain formed by the cold rolling is unstable, and there is a problem that the quality varies between products. However, according to the aluminum alloy sheet, since the reduction ratio of the cold rolling can be set large, variation in quality between products (especially variation in crystal grains in the sheet width direction) can be suppressed, and as a result, it is possible to reduce Qualified products also increase productivity (production volume).

Further, according to the aluminum alloy sheet, since the content of Mn + Cr is within a predetermined range, although the cold rolling step itself is omitted, the final pass reduction ratio in the step of controlling the hot rolling in the crystal oil can be made large. The grain pattern of the particle size appears on the surface of the plate, and the contrast between the crystal grains and the crystal grains is sharp, and an aluminum alloy plate having a thick plate thickness (for example, a plate thickness of 2 mm or more) can also be achieved.

In the aluminum alloy sheet of the present invention, the total content of the Mn and the Cr is preferably 0.01 to 0.14% by mass.

According to the aluminum alloy sheet, the content of the crystal grains having a large particle diameter is exhibited on the surface of the sheet, and the contrast between the crystal grains and the crystal grains is sharpened by setting the total content of Mn and Cr within a predetermined range. One effect is more certain.

The aluminum alloy sheet of the present invention may further contain Zr, and the total content of the Mn and the Cr and the Zr is 0.01 to 0.20% by mass.

According to the aluminum alloy sheet, when Zr is contained, since the content of Mn+Cr+Zr is within a predetermined range, the reduction ratio of cold rolling (in detail, cold rolling after annealing) can be set to be large, and as a result, The contrast between the crystal grains and the crystal grains can be made clear by cold rolling with a large reduction ratio.

Further, according to the aluminum alloy sheet, since the content of Mn + Cr + Zr is within a predetermined range, although the cold rolling step itself is omitted, the reduction in the final pass in the hot rolling step can be made large. The grain pattern of the particle size appears on the surface of the plate while making the contrast between the crystal grains and the crystal grains clear, and an aluminum alloy plate having a thick plate thickness (for example, a plate thickness of 2 mm or more) can also be achieved.

In the aluminum alloy sheet of the present invention, the total content of the Mn, the Cr, and the Zr is preferably 0.01 to 0.14% by mass.

According to the aluminum alloy sheet, the content of Mn, Cr and Zr in a predetermined range is set to a predetermined range, whereby a crystal grain pattern having a large particle diameter can be expressed on the surface of the sheet, and the contrast between the crystal grains and the crystal grains can be made clear. This effect is more certain.

The aluminum alloy plate of the present invention may further contain Cu, which The content of Cu is 0.60% by mass or less.

According to the aluminum alloy plate, since the content of Cu is within a predetermined range, the effect of causing a crystal grain pattern having a large particle diameter to appear on the surface of the plate and the contrast between the crystal grains and the crystal grains can be exhibited. .

The aluminum alloy sheet of the present invention preferably has a tensile strength of 150 MPa or more.

According to the aluminum alloy sheet, since the tensile strength is 150 MPa or more, the strength required for the alloy sheet can be ensured.

The aluminum alloy sheet of the present invention can also be obtained by subjecting the aluminum alloy sheet described above to a surface treatment.

The aluminum alloy sheet of the present invention may also form a resin film on the surface of the aforementioned aluminum alloy sheet.

In the aluminum alloy sheet of the present invention, since the content of each component is within a predetermined range and the average crystal grain diameter is within a predetermined range, and the Cube orientation distribution density is within a predetermined range, a crystal grain size of a large particle size can be obtained. It appears on the surface of the board, and the contrast between the crystal grains and the crystal grains is sharp, whereby the design is excellent.

Fig. 1 is a photographic image showing the surface state of the test material 1 (average crystal grain diameter: 4 mm, Cube orientation distribution density: 8).

Fig. 2 is a photographic image showing the surface state of the test material 11 (average crystal grain diameter: 1 mm, Cube orientation distribution density: 23).

[Best form for carrying out the invention]

Hereinafter, the form of the aluminum alloy plate for carrying out the present invention will be described in detail.

[Aluminum alloy plate]

The aluminum alloy sheet of the present invention is characterized by containing Mg, Mn+Cr, Fe, and Si in a predetermined range, and the balance is composed of Al and unavoidable impurities, and the average crystal grain diameter on the surface of the sheet is within a predetermined range, and the Cube orientation Below the specified value. Therefore, the aluminum alloy sheet of the present invention may contain Zr in such a manner that the total content of Mn and Cr and Zr is within a predetermined range, and may contain Cu in a predetermined range. Further, the aluminum alloy sheet of the present invention preferably has a tensile strength of at least a specified value.

Hereinafter, the reason why the numerical value is limited will be described for each alloy component, average crystal grain diameter, Cube orientation, and tensile strength of the aluminum alloy sheet of the present invention.

(Mg: 2.0 to 6.0% by mass)

Mg has an effect of improving strength by solid solution strengthening in an aluminum alloy, and when it coexists with Si, a Mg-Si-based intermetallic compound is formed to contribute to strength improvement. By making the content of Mg 2.0% by mass or more, The desired strength is obtained. On the other hand, when the content of Mg is more than 6.0% by mass, the number of nuclei of crystal grains is too large, and the average crystal grain diameter of crystal grains appearing on the surface of the plate becomes small.

Therefore, the content of Mg is 2.0 to 6.0% by mass, preferably 3.0% by mass or more and 5.0% by mass or less.

(Mn+Cr: 0.01 to 0.20% by mass)

Mn and Cr are used to cause a crystal grain pattern having a large particle diameter to appear on a surface of the plate. By setting the total content of Mn and Cr to 0.01% by mass or more, Mn and Cr which are pinned by the crystal grains are solid-melted in the final annealing, whereby the pinning is released, and the crystal grains can be grown (coarse) to the desired particles. path. On the other hand, when the total content of Mn and Cr is more than 0.20% by mass, the average crystal grain diameter of crystal grains appearing on the surface of the sheet becomes small.

Therefore, the content of Mn+Cr (the total content of Mn and Cr) is 0.01 to 0.20% by mass, preferably 0.14% by mass or less, and particularly preferably 0.05% by mass or more and 0.11% by mass or less.

In addition, since Mn and Cr are components which exhibit substantially the same function in the aluminum alloy sheet of the present invention, the content of either Mn or Cr may be 0.00% by mass as long as the total content of Mn and Cr is within the range. .

However, in order to obtain a crystal grain pattern having a large particle diameter on the surface of the sheet, the effect of Mn is preferably 0.01 to 0.10% by mass, and the content of Cr is preferably 0.01 to 0.10% by mass.

(Fe: 0.20% by mass or less)

Fe is mixed as a base metal impurity in the aluminum alloy, and an Al-Mn-Fe-based intermetallic compound or an Al-Mn-Fe-Si-based intermetallic compound is formed together with Mn and Si in the aluminum alloy. Although Fe contributes to the improvement of the strength, if the content of Fe is more than 0.20% by mass, the number of crystal grains in which the intermetallic compound is the core becomes excessive, and the average crystal grains of the crystal grains appearing on the surface of the plate become excessive. The diameter becomes smaller.

Therefore, the content of Fe is 0.20% by mass or less (including 0% by mass), preferably 0.01% by mass or more and 0.15% by mass or less.

(Si: 0.10% by mass or less)

Si is contained in the aluminum alloy as a base metal impurity, and has an effect of improving the strength by solid solution strengthening in the aluminum alloy. Further, when it coexists with Mg, a Mg-Si-based intermetallic compound is formed to contribute to strength improvement. However, when the content of Si is more than 0.10% by mass, the number of crystal grains in which the intermetallic compound or the like is a core becomes excessive, and the average crystal grain diameter of the crystal grains appearing on the surface of the plate becomes small.

Therefore, the content of Si is 0.10% by mass or less (including 0% by mass), preferably 0.005% by mass or more and 0.06% by mass or less.

(When further containing Zr, Mn+Cr+Zr: 0.01 to 0.20% by mass)

Zr is a component which exhibits the effect of causing a crystal grain pattern having a large particle diameter to appear on the surface of the sheet, similarly to Mn or Cr. When Zr is further contained, the content of Mn and the total of Cr and Zr is 0.01% by mass or more, and the nail is nailed. The grown Mn of the grain is solidified by the Cr and Zr in the final annealing, so that the pinning is released, and the grain can be grown (coarse) to a desired particle size. On the other hand, when the total content of Mn and Cr and Zr is more than 0.20% by mass, the average crystal grain diameter of crystal grains appearing on the surface of the sheet becomes small.

Therefore, the content of Mn+Cr+Zr (the content of Mn and the total of Cr and Zr) is 0.01 to 0.20% by mass, preferably 0.14% by mass or less, and particularly preferably 0.05% by mass or more and 0.11% by mass or less.

Further, since Mn, Cr and Zr are components which exhibit substantially the same function in the aluminum alloy sheet of the present invention, any one of Mn, Cr and Zr may be contained in a range in which the total content of Mn, Cr and Zr is within the range or The content of the two components may be 0.00% by mass.

(When Cu is further contained, Cu: 0.60% by mass or less)

When the content of Cu is more than 0.60% by mass, the number of nuclei of crystal grains becomes excessive, and the average crystal grain diameter of crystal grains appearing on the surface of the plate becomes small.

Therefore, when Cu is contained, the content of Cu is 0.60% by mass or less, preferably 0.50% by mass or less.

(inevitable impurities)

As an unavoidable impurity, Ti, V, Zn, Ni, Bi, Pb, or the like may be contained in a range that does not impair the effects of the present invention. Specifically, it may be contained in a range of 0.05% by mass or less and 0.20% by mass or less, preferably 0.01% by mass or less, and preferably 0.10% by mass or less.

In addition, when Ti, V, Zn, Ni, Bi, Pb, etc. are not contained in the above-mentioned predetermined content, when it is contained not only as an unavoidable impurity, even if it is positively added, it does not impair the effect of this invention. .

For example, in the case of Ti, it is possible to add Ti monomer or Ti-B for the purpose of refining the ingot structure in the casting step, and if the amount of B at this time is about 0.01% by mass, the effect of the present invention is not impaired. .

In addition, it is also possible to contain Fe, Si, and Zr and Cu which are not essential components, and may be contained as an unavoidable impurity.

Further, the content of each element listed as an unavoidable impurity may of course be 0% by mass.

(Average grain diameter: 1~10mm)

The surface of the aluminum alloy sheet of the present invention has an average crystal grain diameter of 1 to 10 mm.

When the average crystal grain diameter is 1 mm or more, when the aluminum alloy sheet is applied to various applications to be described later, it is possible to realize that the design property is excellent. On the other hand, if the average crystal grain diameter is more than 10 mm, the formability is lowered.

Therefore, the average crystal grain diameter is 1 to 10 mm, preferably 3 mm or more and 8 mm or less.

The average crystal grain diameter can be measured by the following method.

Using a tuckers reagent (hydrochloric acid, nitric acid, hydrofluoric acid), the surface of the finally annealed aluminum alloy sheet in the manufacturing method described later is etched, washed with water, dried, and visually used in the rolling direction. The section method calculates the average grain size of the plant. Also, the measurement using the slicing method is for example The length of one measuring line is 50 mm, and each of the three fields of view is three, and five fields of view are observed in total, so that the length of all the measuring lines is 50 × 15 mm. Further, when the crystal grain diameter is less than 1 mm, the crystal grains are respectively released by the Bark method, and after photographing with an optical microscope, the average crystal grain diameter can also be calculated by the slicing method.

Further, the average crystal grain diameter can be controlled while the content of each of the alloy components described above is controlled, and among the steps of the production method to be described later, in particular, the reduction ratio via the second cold rolling step (first implementation) In the case of the method, the final pass reduction ratio of the hot rolling step (in the case of the second embodiment) is controlled.

(Cube orientation distribution density: 20 or less)

The Cube orientation distribution density of the surface of the aluminum alloy sheet of the present invention is 20 or less with respect to the random orientation (in detail, the Cube orientation distribution density of the sheet surface obtained by analysis of the crystal orientation distribution function is relative to the random orientation. 20 or less). If the Cube orientation distribution density is 20 or less, the contrast between the crystal grains and the crystal grains can be made clear.

Therefore, the Cube orientation distribution density is 20 or less, preferably 15 or less.

The Cube orientation distribution density can be measured by the following method.

For example, after the final annealing in the manufacturing method described later by using an X-ray diffraction apparatus [Model No. RI-rX" (Ru-200B) manufactured by Rigaku Co., Ltd. (in detail, after final annealing, after polishing, By 10% hydrogen The surface of the aluminum alloy plate in which the hydrofluoric acid was chemically polished in a state of about 30 seconds and washed and dried was used to obtain a distribution density of the Cube orientation with respect to the random orientation. Then, the crystal orientation distribution function analysis (ODF analysis) based on the incomplete pole figure can be performed using the X-ray diffraction apparatus. In detail, the incomplete pole figure of {100} plane and {111} plane is made by the reflection method of schluz, and the ODF analysis is performed by Bunge's inverse calculation series positivity method, and the Cube orientation distribution can be obtained. density.

Further, the Cube orientation distribution density may be controlled by the content of each of the alloy components (particularly Mn+Cr, Mn+Cr+Zr) described above, and may be passed through a second step in a step of a manufacturing method to be described later. The reduction ratio of the cold rolling step (in the case of the first embodiment) or the final reduction ratio of the hot rolling step (in the case of the second embodiment) is controlled.

(tensile strength: 150 MPa or more)

The aluminum alloy sheet of the present invention preferably has a tensile strength of 150 MPa or more. When the tensile strength is 150 MPa or more, the strength of the alloy sheet as various uses to be described later can be secured.

Therefore, the tensile strength is preferably 150 MPa or more, and particularly preferably 200 MPa or more.

The tensile strength can be measured by the following method.

The test piece of JIS No. 5 was cut out from the aluminum alloy plate after final annealing in the manufacturing method mentioned later, and the tensile strength was measured by the tensile test according to JISZ2241:2011, and the perpendicular direction of the rolling direction was perpendicular.

Further, the tensile strength can be controlled by the content of each of the alloy components described above, and can be controlled particularly by the heat history and the reduction ratio of each step in the steps of the production method to be described later.

(state of aluminum alloy plate)

The aluminum alloy sheet of the present invention basically means an alloy sheet before the final annealing in the production method described later and before the surface treatment, but also includes an alloy sheet surface-treated for the alloy sheet after the final annealing. .

Here, the "alloyed sheet which has been subjected to surface treatment" is an alloy sheet which is subjected to pretreatment (chemical pretreatment such as mechanical pretreatment such as sand blasting or polishing, chemical pretreatment such as degreasing or etching) to the alloy sheet after final annealing. Further, there is an alloy sheet which has been subjected to a usual surface treatment such as an anodizing treatment, a coloring treatment, and a sealing treatment.

However, when the surface treatment is performed on the aluminum alloy sheet, after the etching is performed using an acidic chemical solution, if anodizing treatment (aluminum anodizing treatment) is performed, irregularities are formed on the surface of the aluminum alloy sheet, and the reflectance is caused by the unevenness. reduce. As a result, the surface of the aluminum alloy plate looks dark, and there is a possibility that the design property is lowered.

Therefore, if it is desired to improve the weather resistance and the like of the aluminum alloy sheet by performing the surface treatment, the above-mentioned "surface treatment" is preferably performed by etching with an acidic chemical solution, and then a treatment for forming a resin film is performed. Instead of performing an anodizing treatment.

Further, the resin film is preferably a fluorine-based resin film (specifically, Japanese Patent No. 3996520, Japanese Patent No. 3846807, Japanese Patent No. 5255612, etc., or a polyester resin film (refer to Japanese Patent No. 4448511, etc.) or an epoxy resin film (specifically, Japanese Patent No. No. 413427, etc.). In addition, the film thickness is not particularly limited, and may be, for example, 0.1 to 10 μm.

(use)

Since the aluminum alloy sheet of the present invention exhibits excellent design properties, it can be applied to all tangible materials that are required to be designed, that is, may be seen.

For example, "for building materials" such as roofs, walls, beds, etc.; for "chassis" for storage machinery and electrical equipment; for "outer or inner panel panels" for transportation equipment such as automobiles, ships, and railway vehicles. Or as an "beverage can", the aluminum alloy plate of the present invention can be applied.

The thickness of the aluminum alloy plate of the present invention is not particularly limited, and may be a thin plate thickness (for example, a plate thickness of less than 2 mm) or a thick plate thickness (for example, a plate thickness of 2 mm or more), according to the foregoing. The purpose of use, you can choose.

As described above, the aluminum alloy sheet of the present invention is conventionally known as other unspecified characteristics and the like, and is not limited as long as the effects obtained by the above characteristics are exhibited.

[Manufacturing method of aluminum alloy plate]

Next, a method of manufacturing the aluminum alloy sheet of the present invention will be described.

Further, since the aluminum alloy sheet of the present invention can be produced by two methods, the method for producing the aluminum alloy sheet according to the first embodiment and the method for producing the aluminum alloy sheet according to the second embodiment will be described below.

(Method of Manufacturing Aluminum Alloy Sheet of First Embodiment)

The aluminum alloy sheet of the present invention is produced by performing a casting step, a homogenization heat treatment step, a hot rolling step, a first cold rolling step, an intermediate annealing step, a second cold rolling step, and a final annealing step.

Further, the aluminum alloy sheet of the present invention can also be produced by performing a surface treatment step after the final annealing step.

Hereinafter, the above respective steps will be mainly described.

(casting step)

In the casting step, the aluminum alloy which is a component of the above-described composition is melted and cast by a known casting method such as a DC casting method, and is cooled to a solidus temperature lower than that of the aluminum alloy to have a predetermined thickness (for example, about 400 to 600 mm). ) the ingot.

(homogenization heat treatment step)

In the homogenization heat treatment step, a homogenization heat treatment is performed at a predetermined temperature before rolling the ingot cast by the casting step. By performing homogenization heat treatment on the ingot, the internal stress is removed, and the solute elements segregated during casting are homogenized, and the intermetallic compound precipitated at the time of casting cooling or thereafter is grown.

The heat treatment temperature of the homogenization heat treatment step is preferably from 400 to 550 °C. The above homogenization effect can be obtained by reaching 400 ° C or more. On the other hand, when the treatment temperature is higher than 550 ° C, the intermetallic compound which is the core of the crystal grains is reduced, and the size of the finally obtained crystal grains becomes large.

Further, the heat treatment time is not particularly limited and may be 1 to 24 hours.

The homogenization heat treatment step may be "primary soaking" in which hot rolling is performed without cooling after the homogenization heat treatment, or may be cooled to a temperature below the hot rolling start temperature (for example, normal temperature) after the homogenization heat treatment, and after the end face turning The "secondary soaking" for performing hot rolling by reheating may be "two-stage soaking" which is cooled to a hot rolling start temperature after the homogenization heat treatment and is hot rolled.

Here, when "one-time soaking" and "two-stage soaking" are performed, face turning can be performed in advance before the homogenization heat treatment step.

(hot rolling step)

In the hot rolling step, hot rolling is performed on the homogenized ingot.

The rolling start temperature or the rolling end temperature in the hot rolling step is not particularly limited. For example, the rolling start temperature is 400 to 550 ° C, and the rolling end temperature is 250 to 380 ° C.

Then, by performing hot rolling composed of a plurality of passes, a hot rolled sheet (hot coil) having a desired thickness can be obtained.

(first cold rolling step)

In the first cold rolling step, cold rolling is performed on the hot rolled sheet below the recrystallization temperature (for example, normal temperature). The reduction ratio of the first cold rolling step is not particularly limited and may be 0 to 80%.

Further, the reduction ratio of 0% indicates the case where the intermediate annealing is performed after completion of the hot rolling (when the first cold rolling is not performed).

(intermediate annealing step)

In the intermediate annealing step, the rolled sheet after the first cold rolling step is annealed.

The annealing temperature or annealing time in the intermediate annealing step is not particularly limited, and is, for example, 300 to 450 ° C for 1 to 12 hours.

(second cold rolling step)

In the second cold rolling step, the rolled sheet after the intermediate annealing is subjected to cold rolling below the recrystallization temperature (for example, normal temperature).

The reduction ratio of the second cold rolling step is preferably 30% or more. When the content of Mn+Cr, Mn+Cr+Zr of the aluminum alloy sheet is within the predetermined range specified by the present invention, the reduction ratio is 30% or more, whereby the particle diameter of the finally obtained crystal grain can be increased to a desired level. The values are simultaneous and the contrast between the grains and the grains can be made sharp. Further, as the reduction ratio becomes larger, the particle diameter of the finally obtained crystal grains gradually becomes smaller.

In summary, according to the aluminum alloy sheet of the present invention, the reduction ratio of the second cold rolling step can be set larger than in the prior art of Patent Document 1.

(final annealing step)

In the final annealing step, the rolled sheet after the second cold rolling step is annealed.

The annealing temperature in the final annealing step is preferably 450 to 550 °C. By making the annealing temperature 450 ° C or more, the growth of Mn, Cr (and Zr) of the pinned grains is solid-melted, and the grain growth (coarse) is performed by one gas, so that the grain size of the crystal grains can be increased to a desired level. value. On the other hand, if the annealing temperature is higher than 600 ° C, melting occurs.

Further, the annealing time is not particularly limited and may be 1 to 12 hours.

The annealing in the final annealing step is continuous annealing (CAL) of rapid heating and cooling, and the crystal grains are not sufficiently grown (coarse), so that batch annealing (box annealing) is preferred. Moreover, the apparatus etc. at the time of batch annealing can be used conventionally.

(surface treatment step)

In the surface treatment step, the surface of the rolled sheet after the final annealing step is subjected to surface treatment.

Examples of the surface treatment in the surface treatment step include "pretreatment" (mechanical pretreatment such as sand blasting or polishing, chemical pretreatment such as degreasing and etching), "anodizing treatment", "coloring treatment", and "sealing". Processing such as general surface treatment.

For example, in the surface treatment step, the rolled plate after the final annealing step is washed with an aqueous sodium hydroxide solution (60 ° C, 10%) for 1 minute, and then decontaminated with a nitric acid aqueous solution (10%) for 1 minute. can. Of course After that, after the pretreatment such as washing or decontamination, it is of course possible to perform anodizing treatment → coloring treatment → sealing treatment.

However, in the surface treatment step, after the etching is performed using an acidic chemical solution, if anodizing treatment (aluminum anodizing treatment) is performed, irregularities are formed on the surface of the aluminum alloy sheet, and the unevenness causes a decrease in reflectance. As a result, the surface of the aluminum alloy plate looks dark, and there is a possibility that the design property is lowered.

Therefore, in the case where the weather resistance and the like of the aluminum alloy sheet are improved by the surface treatment, when the etching is performed using an acidic chemical solution, it is preferred that the anodizing treatment is not performed after the etching, and the treatment for forming the resin film is performed.

In addition, as a process of forming a resin film, for example, formation of a fluorine-based resin film (specifically, Japanese Patent No. 3965520, Japanese Patent No. 3846807, Japanese Patent No. 5255612, etc.) or a polyester resin film is formed (specifically The treatment of the formation of an epoxy resin film (refer to Japanese Patent No. 413427, etc.) may be referred to in Japanese Patent No. 4448511 or the like.

Next, a method of manufacturing the aluminum alloy sheet of the second embodiment will be described.

(Method of Manufacturing Aluminum Alloy Sheet of Second Embodiment)

The aluminum alloy sheet of the present invention is produced by performing a casting step, a homogenization heat treatment step, a hot rolling step, and a final annealing step.

In addition, the aluminum alloy sheet of the present invention may also pass through a final annealing step. The surface treatment step is followed by fabrication.

Hereinafter, the description will be focused on each step.

(casting step)

In the casting step, the aluminum alloy which is a component of the above-described composition is melted and cast by a known casting method such as a DC casting method, and is cooled to a solidus temperature lower than that of the aluminum alloy to have a predetermined thickness (for example, about 400 to 600 mm). Ingots.

(homogenization heat treatment step)

In the homogenization heat treatment step, a homogenization heat treatment is performed at a predetermined temperature before rolling the ingot cast by the casting step. By performing homogenization heat treatment on the ingot, the internal stress is removed, and the solute elements segregated during casting are homogenized, and the intermetallic compound precipitated at the time of casting cooling or thereafter is grown.

The heat treatment temperature of the homogenization heat treatment step is preferably from 400 to 550 °C. The above homogenization effect can be obtained by reaching 400 ° C or more. On the other hand, when the treatment temperature is higher than 550 ° C, the intermetallic compound which is the core of the crystal grains is reduced, and the size of the finally obtained crystal grains becomes large.

Further, the heat treatment time is not particularly limited and may be 1 to 24 hours.

The homogenization heat treatment step may be "primary soaking" in which hot rolling is performed without cooling after the homogenization heat treatment, or may be cooled to below the hot rolling start temperature after the homogenization heat treatment (for example, The "secondary soaking" which performs hot rolling after re-heating after face turning, may be "two-stage soaking" which is cooled to the hot rolling start temperature after the homogenization heat treatment and hot rolling.

Here, when "one-time soaking" and "two-stage soaking" are performed, the end face turning may be performed before the homogenization heat treatment step.

(hot rolling step)

In the hot rolling step, hot rolling is performed on the homogenized ingot.

The rolling start temperature or the rolling end temperature in the hot rolling step is not particularly limited. For example, the rolling start temperature is 400 to 550 ° C, and the rolling end temperature is 250 to 380 ° C.

Then, by performing hot rolling composed of a plurality of passes, a hot rolled sheet (hot coil) having a desired thickness can be obtained.

Further, the reduction ratio of the final pass of the hot rolling step (specifically, the final pass reduction ratio of the final hot rolling) is preferably higher than 10% and 45% or less. When the content of Mn+Cr, Mn+Cr+Zr in the aluminum alloy sheet is within the predetermined range specified by the present invention, the final grain yield can be obtained by setting the reduction ratio of the final pass within the range. The diameter is increased to the desired value at the same time, and the contrast between the crystal grains and the crystal grains can be made clear.

Further, if the reduction ratio of the final pass of the hot rolling step is higher than 45%, it is difficult to cause a crystal grain pattern having a large particle diameter to appear on the surface of the plate. On the other hand, if it is 10% or less, the roll cannot be bitten into the roll. If you do not, you will not get a hot rolled sheet.

(final annealing step)

In the final annealing step, the rolled sheet after the hot rolling step is annealed.

The annealing temperature in the final annealing step is preferably 450 to 550 °C. By making the annealing temperature 450 ° C or more, the growth of Mn, Cr (and Zr) of the pinned grains is solid-melted, and the grain growth (coarse) is performed by one gas, so that the grain size of the crystal grains can be increased to a desired level. value. On the other hand, if the annealing temperature is higher than 600 ° C, melting occurs.

Further, the annealing time is not particularly limited and may be 1 to 12 hours.

The annealing in the final annealing step is continuous annealing (CAL) of rapid heating and cooling, and the crystal grains are not sufficiently grown (coarse), so that batch annealing (box annealing) is preferred. Moreover, the apparatus etc. at the time of batch annealing can be used conventionally.

(surface treatment step)

In the surface treatment step, the surface of the rolled sheet after the final annealing step is subjected to surface treatment.

Examples of the surface treatment in the surface treatment step include "pretreatment" (mechanical pretreatment such as sand blasting or polishing, chemical pretreatment such as degreasing and etching), "anodizing treatment", "coloring treatment", and "sealing". Processing such as general surface treatment.

For example, in the surface treatment step, the rolled plate after the final annealing step is washed with an aqueous sodium hydroxide solution (60 ° C, 10%) for 1 minute, and then decontaminated with a nitric acid aqueous solution (10%) for 1 minute. can. Then, after the pre-treatment such as cleaning and decontamination, of course, it is also possible to carry out the yang. Extreme oxidation treatment → coloring treatment → sealing treatment.

However, in the surface treatment step, after the etching is performed using an acidic chemical solution, if anodizing treatment (aluminum anodizing treatment) is performed, irregularities are formed on the surface of the aluminum alloy sheet, and the unevenness causes a decrease in reflectance. As a result, the surface of the aluminum alloy plate looks dark, and there is a possibility that the design property is lowered.

Therefore, in the case where the aluminum alloy sheet is improved in the weather resistance and the like by the surface treatment, when the etching is performed using an acidic chemical solution, it is preferred to carry out the treatment for forming the resin film without performing the anodizing treatment after the etching.

In addition, as a process of forming a resin film, for example, formation of a fluorine-based resin film (specifically, Japanese Patent No. 3965520, Japanese Patent No. 3846807, Japanese Patent No. 5255612, etc.) or a polyester resin film is formed (specifically The treatment of the formation of an epoxy resin film (refer to Japanese Patent No. 413427, etc.) may be referred to in Japanese Patent No. 4448511 or the like.

So far, the method for manufacturing an aluminum alloy plate has been described as being divided into two, and it is preferable to manufacture the aluminum alloy plate having a thin plate thickness (for example, a plate thickness of less than 2 mm) via the first embodiment, and to manufacture a thicker one. The aluminum alloy sheet having a sheet thickness (for example, a sheet thickness of 2 mm or more) is preferably produced by the second embodiment.

Further, in the case of producing an aluminum alloy sheet having a Cube orientation distribution density of 15 or less and a very sharp contrast between crystal grains and crystal grains, it is preferably produced by the first embodiment.

The method for producing the aluminum alloy sheet of the present invention is as described above. However, in the case where the present invention is carried out, other steps may be included between or before and after the above steps insofar as the above steps are not adversely affected. For example, after the final annealing step or the surface treatment step, a cutting step of cutting the aluminum alloy sheet into a predetermined size or a processing step of processing into a predetermined shape (bending processing, punching, or the like) may be included.

In addition, in the above-described respective steps, conventionally known conditions may be employed for the unspecified conditions, and the effects obtained by the processes in the respective steps described above may be appropriately changed, and of course, the conditions may be appropriately changed.

[Examples]

Next, with respect to the aluminum alloy sheet of the present invention, an embodiment satisfying the requirements of the present invention is compared with a comparative example which does not satisfy the requirements of the present invention, and will be specifically described.

[Production of test materials]

With respect to the test materials 1 to 21 of Table 1, the aluminum alloy having the composition shown in Table 1 was melted, and the ingot was produced by semi-continuous casting, and subjected to face turning treatment to a thickness of 580 mm. After the homogenization heat treatment was performed on the ingot, hot rolling was performed (starting temperature: 480 ° C, end temperature: 320 ° C, final sheet thickness: 3 mm, final pass reduction ratio: shown in Table 1), thereby becoming a hot rolled sheet. . Thereafter, by performing first cold rolling (reduction ratio: 58%), intermediate annealing (temperature: 350 ° C, time: 4 h), second cold rolling (reduction ratio: shown in Table 1), final annealing (temperature) : 550 ° C, time: 4 h), made a test material.

With respect to the test materials 22 to 26 of Table 1, the aluminum alloy having the composition shown in Table 1 was melted, and the ingot was produced by semi-continuous casting, and subjected to face turning processing to a thickness of 580 mm. The ingot was subjected to homogenization heat treatment and then subjected to hot rolling (starting temperature: 480 ° C, end temperature: 320 ° C, final sheet thickness: shown in Table 1, final pass reduction ratio: shown in Table 1), from The hot-rolled sheet was subjected to final annealing (temperature: 550 ° C, time: 4 h) to prepare a test piece.

Then, for the test materials 1 to 26, the surface treatment was performed after the final annealing. This surface treatment was performed by washing the test material with an aqueous sodium hydroxide solution (60 ° C, 10%) for 1 minute, and then decontaminating with a nitric acid aqueous solution (10%) for 1 minute.

[Evaluation]

(average grain diameter)

The surface of the sample to be decontaminated was etched with a card etching solution (hydrochloric acid, nitric acid, hydrofluoric acid), washed with water, and dried, and the value of the average crystal grain diameter was calculated by a slice method in the rolling direction by visual inspection. Further, using the measurement by the slicing method, the length of one measurement line was 50 mm, and each of the three fields of view was observed, and five fields of view were observed in total, whereby the length of all the measurement lines was 50 × 15 mm. Further, when the crystal grain diameter is less than 1 mm, crystal grains are respectively exhibited by a barker method, and after photographing with an optical microscope, the average crystal grain diameter is also calculated by a slicing method.

(Tensile Strength)

The test piece of JIS No. 5 was cut out from the test piece in such a manner that the stretching direction was perpendicular to the rolling direction. Using this test piece, a tensile test was carried out in accordance with JIS Z2241:2011, and tensile strength was measured.

Further, the crosshead speed was 5 mm/min, and the speed was performed at a constant speed until the test piece was broken.

(Cube orientation)

The measurement of the Cube orientation was measured using an X-ray diffraction apparatus (Model "RiD RC-rX" (Ru-200B)] manufactured by Rigaku Co., Ltd., after final annealing, and after polishing, 10% hydrofluoric acid was used for about 30 seconds. The surface of the test piece which was ground and washed with water was dried, whereby the distribution density of the Cube orientation with respect to the random orientation was determined. The ODF analysis based on the incomplete pole figure was performed using the X-ray diffraction apparatus. Specifically, the incomplete pole figure of the {100} plane and the {111} plane is formed by the reflection method of schluz, and ODF analysis is performed by Bunge's inverse calculation series positivity method to obtain the Cube orientation distribution density. .

The composition and test results of the detailed aluminum alloy are shown in Table 1. Further, in Table 1, the numerical bottom line is shown as not satisfying the constitution of the present invention.

[Results of research]

In the test materials 1 to 10, 22 to 24, since the requirements specified in the present invention are satisfied, the result is that a large grain size grain pattern can be exhibited on the surface of the plate, and the grain and the grain are compared. Bright.

Further, in the test materials 1 to 10 and 22 to 24, the tensile strength was also 150 MPa or more, and the rigidity required for the alloy sheet was also obtained.

Moreover, as shown in FIG. 1, the test material 1 has a large average crystal grain diameter, and it is confirmed that the design property is excellent.

On the other hand, in the test material 11, since the content of Mg is lower than the lower limit of the numerical range defined by the present invention, the tensile strength is low, and as a result, it is not suitable as an alloy sheet. Further, in the test material 11, since the content of Mg is lower than the lower limit of the numerical range defined by the present invention, the Cube orientation distribution density of the surface of the sheet is higher than 20 with respect to the random orientation.

Moreover, as shown in FIG. 2, the test piece 11 has a small average crystal grain diameter, and it was confirmed that the design property was poor.

In the test material 12, since the content of Mg is higher than the upper limit of the numerical range defined by the present invention, the crystal grains appearing on the surface of the plate are small, and as a result, the design is poor.

In the test material 13, since the total content of Mn and Cr is higher than the upper limit of the numerical range defined by the present invention, the crystal grains appearing on the surface of the plate are small, and as a result, the design property is poor.

In the test material 14, since the total content of Mn and Cr is higher than the upper limit value of the numerical range specified by the present invention, crystal grains appearing on the surface of the plate Small, the result is poor design.

In the test material 15, since the content of Fe is higher than the upper limit of the numerical range defined by the present invention, the crystal grains appearing on the surface of the plate are small, and as a result, the design property is poor.

In the test material 16, since the content of Si is higher than the upper limit of the numerical range defined by the present invention, the crystal grains appearing on the surface of the plate are small, and as a result, the design property is poor.

In the test material 17, since the total content of Mn, Cr, and Zr is higher than the upper limit of the numerical range defined by the present invention, the crystal grains appearing on the surface of the plate are small, and as a result, the design property is poor.

In the test material 18, since the total content of Mn, Cr, and Zr is lower than the lower limit of the numerical range defined by the present invention, the crystal grains appearing on the surface of the plate are small, and as a result, the design property is poor.

In the test material 19, since the content of Cu is higher than the upper limit of the numerical range defined by the present invention, the crystal grains appearing on the surface of the plate are small, and as a result, the design property is poor.

In the test material 20, since the reduction ratio of the second cold rolling was low and the average crystal grain diameter was small, the result was poor design.

The test material 21 is a technique conceived as Patent Document 1, the content of Mn+Cr is higher than the upper limit value of the numerical range defined by the present invention, and the reduction ratio of the second cold rolling is low, so the Cube orientation distribution density on the surface of the plate is low. Relative to a random orientation higher than 20. Therefore, in the test material 21, the contrast between the crystal grains and the crystal grains which appear on the surface of the sheet is small, and as a result, the design property is poor.

In the test material 25, since the total content of Mn, Cr, and Zr is higher than Since the upper limit of the numerical range defined by the present invention is small, the crystal grains appearing on the surface of the plate are small, and as a result, the design is inferior.

In the test material 26, since the reduction ratio of the final pass of the hot rolling was high and the average crystal grain diameter was small, the result was poor design.

From the above results, it is understood that the aluminum alloy sheet of the present invention allows the grain pattern of the particle size to appear on the surface of the sheet, and the contrast between the crystal grains and the crystal grains is sharp.

In addition, in the test materials 1 to 10 and 22 to 24, a fluorine-based resin film having a thickness of 2 μm is formed (formed by the same method as in the first embodiment of paragraphs 0034 and 0040 of Japanese Patent No. 3996520). The Cube orientation distribution density was measured, and as a result, there was almost no change from before the formation.

Therefore, it is understood that, in the case of the resin film, the contrast between the crystal grains and the crystal grains is not lowered, and the effect exerted by the resin film (resistance to abrasion, etc.) can be enjoyed.

Claims (10)

An aluminum alloy plate characterized by containing Mg: 2.0 to 6.0% by mass, Mn + Cr: 0.01 to 0.20% by mass, Fe: 0.20% by mass or less, Si: 0.10% by mass or less, and the balance being Al and inevitable The impurity has an average crystal grain diameter of 1 to 10 mm on the surface of the plate, and the Cube orientation distribution density on the surface of the plate is 20 or less with respect to the random orientation. An aluminum alloy plate characterized by containing Mg: 2.0 to 6.0% by mass, Mn+Cr+Zr: 0.01 to 0.20% by mass, Fe: 0.20% by mass or less, Si: 0.10% by mass or less, and the balance being Al and not The impurities to be avoided have an average crystal grain diameter of 1 to 10 mm on the surface of the plate, and the Cube orientation distribution density on the surface of the plate is 20 or less with respect to the random orientation. The aluminum alloy sheet according to claim 1 or claim 2, further comprising Cu, wherein the content of Cu is 0.60% by mass or less. The aluminum alloy sheet of claim 1, wherein the tensile strength is 150 MPa or more. The aluminum alloy sheet according to claim 2, wherein the tensile strength is 150 MPa or more. The aluminum alloy sheet according to claim 3, wherein the tensile strength is 150 MPa or more. An aluminum alloy plate characterized by being as claimed in claim 1 or 2 The aluminum alloy plate was obtained by surface treatment. The aluminum alloy sheet according to claim 7, which has a resin film formed on the surface of the aluminum alloy sheet by the surface treatment described above. An aluminum alloy plate characterized by containing Mg: 2.0 to 6.0% by mass, Mn+Cr: 0.01 to 0.14% by mass, Fe: 0.20% by mass or less, Si: 0.10% by mass or less, and the balance being Al and inevitable The impurity has an average crystal grain diameter of 1 to 10 mm on the surface of the plate, and the Cube orientation distribution density on the surface of the plate is 20 or less with respect to the random orientation. An aluminum alloy plate characterized by containing Mg: 2.0 to 6.0% by mass, Mn+Cr+Zr: 0.01 to 0.14% by mass, Fe: 0.20% by mass or less, Si: 0.10% by mass or less, and the balance being Al and not The impurities to be avoided have an average crystal grain diameter of 1 to 10 mm on the surface of the plate, and the Cube orientation distribution density on the surface of the plate is 20 or less with respect to the random orientation.