Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
  • B22D21/02—Casting exceedingly oxidisable non-ferrous metals, e.g. in inert atmosphere
  • B22D21/04—Casting aluminium or magnesium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D21/00—Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
  • B22D21/002—Castings of light metals
  • B22D21/007—Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
  • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
  • C25D11/08—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing inorganic acids
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/04—Anodisation of aluminium or alloys based thereon
  • C25D11/18—After-treatment, e.g. pore-sealing
  • C25D11/24—Chemical after-treatment
  • C25D11/246—Chemical after-treatment for sealing layers

Definitions

• the present invention relates to a brilliant aluminum alloy and a brilliant aluminum alloy die-cast material using the brilliant aluminum alloy.
• Aluminum alloy material is used for the housings of portable electronic devices and electronic terminals because it is lightweight and has an excellent texture.
• an aluminum alloy material may be partially used for the purpose of improving the design of the product appearance.
• the texture of the aluminum alloy material for example, by forming an oxide layer on the surface of the aluminum alloy material by anodizing treatment, in addition to improving the brilliance and corrosion resistance, coloring is possible as needed. Further, in many cases, the anodized film has a higher hardness than the surface of the aluminum alloy material, so that it can be suitably used as an exterior material in that resistance to scratches and the like can be imparted.
• the material has high mechanical properties and is absolutely excellent as long as it develops a beautiful color after the anodizing treatment, and it cannot be simply said that the material is excellent in texture and color tone.
• the mechanical properties such as strength as much as possible while ensuring the consistency of.
• Patent Document 1 Japanese Patent Publication No. 56-31854
• An aluminum alloy for die casting containing 05 to 1.0% and 0.02 to 0.3% titanium and consisting of the balance aluminum and impurities is disclosed.
• the aluminum alloy is said to be an aluminum alloy for die casting that has less seizure during die casting, has good mold releasability, and has good corrosion resistance, surface treatment properties, and mechanical properties.
• Patent Document 2 Japanese Patent Publication No. 56-31855
• manganese is 1.2 to 2.8%
• iron is 0.2 to 1.5%
• chromium is 0.1 to 1.35%
• titanium is 0 by weight.
• An aluminum alloy for die casting containing 0.05 to 1.0% and 0.02 to 0.3% titanium and consisting of the balance aluminum and impurities is disclosed.
• the aluminum alloy is said to be an aluminum alloy for die casting that has less seizure during die casting, has good mold releasability, and has good corrosion resistance, surface treatment properties, and mechanical properties.
• Tungsten is contained in both the aluminum alloys for die casting disclosed in Patent Document 1 and Patent Document 2. Tungsten tends to add a reddish color to the anodized film in the anodized treatment with a sulfuric acid bath and a golden color in the anodized treatment with an oxalic acid bath. In addition, aluminum alloys containing tungsten are dyed. It is known to bring about vivid and uniform color development when anodized aluminum is used, and improvement of mechanical properties is desired.
• the intermetallic compound that is inevitably formed also changes. Since the color tone of the anodic oxide film usually changes in a complicated manner depending on the type and amount of the intermetallic compound in the base aluminum alloy material, the structure morphology, the type and amount of the solid solution element, etc., the anodic oxide treatment is performed. It is also not easy to change the mechanical properties of the aluminum alloy material while maintaining the same color tone as compared later.
• the aluminum alloy disclosed in Patent Document 1 and Patent Document 2 has a 0.2% proof stress of approximately 100 MPa or more in many examples. It seems as if an aluminum alloy member having sufficiently high yield strength and capable of providing a beautiful anodized film has been realized.
• the mold shape used for die casting in the examples is a simple plate shape of 100 mm (L) ⁇ 100 mm (W) ⁇ 2 mm (t), and under such die casting conditions, the cooling rate at each member position is high. Since the variation is relatively small, it cannot be said that the state of occurrence of color unevenness when the anodic oxidation treatment is performed in the actual product shape can be sufficiently simulated.
• the present inventors have made electronic devices, electronic terminals, etc., which are becoming smaller and more complicated in shape, with respect to the aluminum alloy compositions described in the examples of Patent Document 1 and Patent Document 2. Die-casting was performed with a mold having the complexity of the actual product shape level, and the obtained member was anodized. As a result, color unevenness occurred due to variations in the concentration of contained elements due to different cooling rates depending on the position, variations in alloy structure morphology, and the like, and the product could not be used as a product. Therefore, when manufacturing an actual product, the components that contribute to the strength of the aluminum alloy such as Mn and Fe are adjusted to be close to the lower limit of the component range shown in Patent Document 1 and Patent Document 2. In addition, the concentration of contained elements and the variation in the structure of the intermetallic compound depending on the position of the member were reduced, and the occurrence of color unevenness had to be suppressed.
• an object of the present invention is that when an aluminum alloy die-cast material containing tungsten is anodized, the occurrence of color unevenness is highly suppressed and a high machine is used. It is an object of the present invention to provide a bright aluminum alloy having a specific property. Another object of the present invention is to provide a bright aluminum alloy die-cast material produced by using the bright aluminum alloy.
• the present inventors have made an aluminum alloy die casting material containing an appropriate amount of tungsten. We have found that it is extremely effective to strictly control the addition amounts of Mn, Si and Mg, which are elements that improve mechanical properties, and have arrived at the present invention.
• the present invention Mn: 0.5 to 3.0% by mass, Mg: 0.1-2.0% by mass, W: 0.01 to 1.0% by mass, Si: contains 0.05 to 2.0% by mass, Provided is an aluminum alloy, the balance of which is aluminum and unavoidable impurities.
• the aluminum alloy of the present invention The Mn content is 1.2 to 2.0% by mass, The Mg content is 0.3 to 1.2% by mass, The Si content is preferably 0.15 to 0.5% by mass.
• the aluminum alloy die-cast material has high yield strength and high resistance without impairing the color development of the anodic oxide film formed by the anodic oxidation treatment of the aluminum alloy containing tungsten. Hardness can be imparted.
• the metal structure of the aluminum alloy die-cast material can be made finely uniform, and the occurrence of casting cracks and color unevenness after the anodic oxidation treatment can be suppressed.
• the present invention also provides an aluminum alloy die-cast material, which is made of the aluminum alloy of the present invention and has a 0.2% proof stress of 100 MPa or more. Since the aluminum alloy die-cast material of the present invention contains Mn, Si, and Mg that contribute to the improvement of 0.2% proof stress, it is possible to realize 0.2% proof stress of 100 MPa or more.
• the aluminum alloy die-cast material of the present invention preferably has a Vickers hardness of 60 or more. Since the Vickers hardness of the aluminum alloy die-cast material is 60 or more, it is possible to suppress deformation at the time of mold release even in the part where the thickness must be thin due to the shape of the product, and the formation of screw holes, etc. Since it is possible to impart the workability required for precision machining, it can be suitably used as various housings.
• the granular crystal region formed by the primary crystal ⁇ particles having a maximum ferret diameter of 10 ⁇ m or more occupies 90% or more of the surface area ratio of the member surface. Further, in order to realize more uniform color development during dyeing, the granular crystal region formed by the primary crystal ⁇ particles having a maximum ferret diameter of 10 ⁇ m or more occupies 95% or more of the surface area ratio of the member surface. Is more preferable.
• the aluminum alloy die-cast material of the present invention includes an anodized film of about 5 ⁇ m formed by anodizing without dyeing using a sulfuric acid bath, and the light source is CIE by measuring the color on the surface of the anodized film. It is preferable that the L * value is 70 or more, the a * value is 0 to 2, and the b * value is 1 to 4 when the standard illuminant D65 is used. In the color measurement of the surface provided with the anodic oxide film of about 5 ⁇ m, the aluminum alloy die-cast material has these values, so that the appearance of a beautiful color tone can be obtained.
• the present invention it is possible to provide a bright aluminum alloy having high mechanical properties in addition to highly suppressing the occurrence of color unevenness when anodizing an aluminum alloy die-cast material containing tungsten. Can be done. It is also possible to provide a bright aluminum alloy die-cast material produced by using the bright aluminum alloy.
• the aluminum alloy of the present invention has Mn: 0.5 to 3.0% by mass, Mg: 0.1 to 2.0% by mass, W: 0.01 to 1.0% by mass, Si: 0.05. It is an aluminum alloy containing up to 2.0% by mass, the balance of which is aluminum and unavoidable impurities.
• Mg 0.5 to 3.0% by mass
• W 0.01 to 1.0% by mass
• Si 0.05. It is an aluminum alloy containing up to 2.0% by mass, the balance of which is aluminum and unavoidable impurities.
• each component will be described in detail.
• Additive element Mn 0.5 to 3.0% by mass Mn can affect color development during anodic oxidation treatment, form Al—Mn intermetallic compounds, contribute to proof stress, and prevent the molten metal from seizing into the mold during casting. Is added. If Mn is less than 0.5% by mass, it is not possible to prevent the molten metal from being seized onto the mold during casting, so the lower limit of Mn is 0.5% by mass. On the other hand, if it is added in an amount exceeding 3.0% by mass, the Al—Mn-based intermetallic compound grows coarsely and casting cracks occur, so that the upper limit of Mn is 3.0% by mass.
• the Al—Mn-based intermetallic compound has a great effect of reducing the brightness of the die casting material after the anodizing film treatment. If it is added in an amount of more than 2.0% by mass, the amount of Al—Mn-based intermetallic compound increases and the desired color development may not be obtained. Therefore, a more preferable upper limit value is 2.0% by mass.
• the lower limit is preferably 1.2% by mass, more preferably 1.5% by mass.
• Mg 0.1-2.0% by mass Mg is added to form an Mg 2 Si intermetallic compound together with Si, which will be described later, and to contribute to strength.
• Mg 2 Si intermetallic compound contributes to the strength, it has the effect of lowering the L * value (brightness) in the color development after the anodizing treatment, so if it is excessively formed, the desired color development cannot be obtained.
• the Si concentration is low, the Mg 2 Si intermetallic compound is not excessively formed, but when the excess Mg is large, the color caused by the concentration segregation of Mg solid-solved in the base material. Unevenness occurs. Therefore, the upper limit of Mg is limited to 2.0% by mass.
• the lower limit value of Mg is 0.1% by mass. In order to obtain the above effect more reliably, it is preferable to set the upper limit to 1.2% by mass and the lower limit to 0.3% by mass, and from the same viewpoint, it is more preferable to set the upper limit to 0.7% by mass. preferable.
• Si 0.05 to 2.0% by mass Si is added because it forms an Mg 2 Si intermetallic compound together with the above-mentioned Mg and contributes to strength.
• Mg 2 Si intermetallic compound contributes to the strength, it also has the effect of lowering the L * value (brightness) in the color development after the anodizing treatment, so if it is excessively formed, the desired color development cannot be obtained. ..
• concentration of Mg is low, the Mg 2 Si intermetallic compound is not excessively formed, but when the excess Si is large, the Al—Mn—Si compound is formed together with the above-mentioned Mn.
• the intermetallic compound has a large effect on color development after the anodization treatment, and is therefore not preferable. Therefore, the upper limit of Si is 2.0% by mass. Further, since it is necessary to secure the amount of Mg 2 Si intermetallic compound in order to obtain the desired strength, the lower limit of Si is 0.05% by mass. In order to obtain the above effect more reliably, it is preferable that the upper limit is 0.5% by mass and the lower limit is 0.15% by mass.
• W 0.01 to 1.0% by mass W gives a reddish color in the anodizing treatment with a sulfuric acid bath and a golden color in the anodizing treatment with an oxalic acid bath in the color development after the anodic oxidation treatment, and in addition, the uniform and beautiful color development aimed at by the present invention. Is added to obtain. If the W content is less than the lower limit, the above effect is not sufficient, and if it is added in excess of 1.0% by mass, the alloy cost will increase. Therefore, the upper limit is 1.0% by mass and the lower limit is 0.01. It is mass%.
• Ti: 0.01 to 0.5% by mass, B: 0.001 to 0.2% by mass, and Zr: 0.01 to 0.5% by mass may be further added.
• These additive elements are added for the purpose of preventing casting cracks and color unevenness after the anodic oxidation treatment by making the metal structure finely uniform. If any of the elements is added excessively, a coarse intermetallic compound containing these added elements as a constituent element will be formed, and the above object cannot be achieved. Therefore, Ti: 0.5% by mass and Ti: 0.5% by mass, respectively.
• B: 0.2% by mass and Zr: 0.5% by mass are limited as upper limit values. If the amount added is less than the lower limit, the effect of microstructure miniaturization cannot be sufficiently obtained, so the lower limit is Ti: 0.01% by mass, B: 0.001% by mass, Zr: 0.01% by mass. %.
• Fe is an impurity element in the present invention because it affects color unevenness and lightness by forming an intermetallic compound, but if the content is 0.5% by mass or less, the effect is small and the content is high. Permissible.
• the method for producing the aluminum alloy of the present invention is not particularly limited as long as the effects of the present invention are not impaired, and various conventionally known production methods may be used.
• the aluminum alloy die-cast material of the present invention is made of the aluminum alloy of the present invention and is characterized by having a 0.2% proof stress of 100 MPa or more. Excellent mechanical properties are basically realized by rigorously optimizing the composition, and have the mechanical properties regardless of the shape and size of the die-cast material, and regardless of the part and orientation of the die-cast material. doing.
• the aluminum alloy die-cast material of the present invention preferably has a Vickers hardness of 60 or more. Since the Vickers hardness of the aluminum alloy die-cast material is 60 or more, it is possible to suppress deformation at the time of mold release even in the part where the die-cast material has to be thin, and precision such as formation of screw holes. It is possible to impart the workability required for various processing.
• the granular crystal region formed by the primary crystal ⁇ particles having a maximum ferret diameter of 10 ⁇ m or more occupies 90% or more of the surface area ratio on the member surface.
• a granular crystal region having a relatively large particle size of the primary crystal ⁇ and a columnar crystal region having a relatively small particle size of the primary crystal ⁇ may coexist.
• the present inventors tend to (1) in the granular crystal region, the incident light tends to be specularly reflected due to the primary crystal ⁇ particles, while in the columnar crystal region, the surface area occupied by the individual crystal grains becomes small.
• this difference in reflection tendency causes color unevenness in the color development stage of the anodized film. I found that it is the main factor of. Color unevenness due to this difference in reflection tendency can be eliminated by making the particle size of the primary crystal ⁇ uniform, and 90% or more of the surface area ratio of the surface area of the member is either the granular crystal region or the columnar crystal region. When occupied by, color unevenness after the anodic oxidation treatment is suppressed.
• the particle size (maximum ferret diameter) of the primary crystal ⁇ particles in the columnar crystal region is as fine as several ⁇ m on average, and the abundance of the second phase particles appearing at the grain boundaries of the primary crystal ⁇ particles is relatively high. ..
• the second-phase particles present on the surface of the member are the main cause of the decrease in brightness in the anodizing treatment and also inhibit the coloring in the dyeing treatment. Therefore, in order to avoid color unevenness while maintaining good brightness after the anodizing treatment, the granular crystal region formed by the primary crystal ⁇ particles having a maximum ferret diameter of 10 ⁇ m or more has a surface area ratio of 90 on the member surface. It is effective to occupy% or more.
• the granular crystal region can be visually identified after the anodizing treatment. From this point of view, in order to expose the homogeneous primary alpha particles inside the die casting material to the surface, it is one of the effective solutions to perform surface cutting of about 1 mm on the die casting material and perform anodizing treatment. ..
• one of the advantages of the die-casting material over the members obtained by other construction methods such as wrought material is that the shape of the die-casting material is close to that of the product when the casting is completed. Die-casting the material loses at least a partial cost advantage over other construction methods. Therefore, there is a great demand for bright aluminum alloy die castings that do not have uneven color development even when anodizing is performed without surface cutting.
• the aluminum alloy die-cast material of the present invention can be provided with an anodized film having high brightness and uniform color development without surface cutting, which uses the aluminum alloy composition of the present invention.
• This has a great effect of forming primary crystal ⁇ particles having a uniform and sufficiently large particle size (maximum ferret diameter) on the surface of the die casting material and defining the amount of precipitation of various intermetallic compounds.
• the method for obtaining the maximum ferret diameter of the primary crystal ⁇ particles is not particularly limited, and measurement may be performed by various conventionally known methods.
• the ferret diameter is the length of the side of the rectangle circumscribing the particles, but the maximum ferret diameter of a certain crystal grain changes the angle of the circumscribing rectangle, and the length of the long side becomes the largest. It is the length of the rectangle.
• the maximum ferret diameter of each primary crystal ⁇ is measured.
• the cross-sectional sample may be subjected to mechanical polishing, buffing, electrolytic polishing, etching or the like.
• the shape and size of the aluminum alloy die-cast material are not particularly limited as long as the effects of the present invention are not impaired, and they can be used as various conventionally known members.
• Examples of the member include an electronic terminal housing.
• the method for producing the aluminum alloy die-casting material of the present invention is not particularly limited as long as the effects of the present invention are not impaired, and the aluminum alloy of the present invention can be die-cast by various conventionally known methods. Just give it.
• the casting pressure may be 80 to 150 MPa
• the molten metal temperature may be 680 to 780 ° C
• the mold temperature may be 130 to 200 ° C.
• heat treatment is not required to obtain the aluminum alloy die-cast material of the present invention, it can be applied as long as it is a die-cast material having reduced porosity, such as a die-cast material produced by a vacuum die-casting method, a PF die-casting method, or the like. is there.
• Aluminum alloy die-cast material with anodic oxide film The aluminum alloy die-cast material with anodic oxide film of the present invention is obtained by subjecting the aluminum alloy die-cast material of the present invention to anodization treatment and is uniform. It is characterized by having a beautiful color appearance.
• the aluminum alloy die-cast material provided with the anodized film will be described in detail.
• the aluminum alloy die-cast material provided with the anodized film of the present invention is L * when the light source is CIE standard Illuminant D65 in the surface color measurement with the 5 ⁇ m anodized film undyed by a sulfuric acid bath. It is characterized in that the value is 70 or more, the a * value is 0 or more and 2 or less, and the b * value is 1 or more and 4 or less.
• the surface color measurement method the method specified in JISZ8781 may be used as the surface color measurement method.
• the aluminum alloy die-cast material provided with the anodized film of the present invention is characterized in that the occurrence of color unevenness is highly suppressed.
• the method of detecting color unevenness for example, in the reflectance measurement, if the reflectance is significantly different depending on the part, it is naturally recognized as color unevenness by the human eye, but on the other hand, it is tentatively all. Even if the same reflectance is obtained at the site, the light incident on the part where the average particle size of the primary crystal ⁇ particles is small and the intermetallic compound is densely present is diffusely reflected, and the average of the primary crystal ⁇ particles is reflected.
• Anodization treatment of aluminum alloy die-cast material The method of anodization treatment of aluminum alloy die-cast material will be described in detail below. It should be noted that the form of the invention does not have to include all of these steps. For example, the following surface milling process can be omitted in consideration of the manufacturing cost, and it is possible to select and carry out the steps as needed. is there.
• Blasting is a treatment in which hard fine particles are made to collide with an aluminum alloy die-cast material to roughen the surface.
• the blasting treatment By applying the blasting treatment, the metallographic structure after the anodizing treatment can be made inconspicuous.
• Known blasting conditions may be used. For example, fine particles having a grain size of 80 to 400 ⁇ m made of ZrO 2 , SiO 2, and the like may be used, and the injection pressure may be 0.2 to 0.6 MPa.
• Solventing treatment This is a treatment for removing oil and dust on the surface of an aluminum alloy die-cast material.
• Known degreasing conditions may be used.
• a halogenated hydrocarbon may be used as a solvent, and after a shower at a temperature of 72 ° C. or higher for about 10 seconds, steam injection may be performed for about 1 minute.
• Oxide film removal treatment This is a treatment for removing the oxide film formed on the surface of the aluminum alloy die-cast material.
• Known conditions for removing the oxide film may be used.
• HNO 3 having a concentration of 200 g / l may be used as a bath solution and immersed at room temperature for about 1 minute.
• Etching treatment This is a treatment for removing fine scratches and stains that cannot be removed by degreasing treatment by melting the surface of the aluminum alloy die-cast material.
• Known etching conditions may be used. For example, a 50 g / l NaOH aqueous solution may be used and immersed at room temperature for about 1 minute.
• Desmat treatment This is a treatment for removing oxides and the like existing on the surface of an aluminum alloy die-cast material.
• known ones may be used.
• HNO 3 having a concentration of 200 g / l may be used as a bath solution, immersed at room temperature for about 1 minute, and ultrasonically irradiated.
• Chemical polishing treatment This is a treatment for giving a glossy feeling to the surface of the aluminum alloy die-cast material by melting the surface of the aluminum alloy die-cast material.
• Known chemical polishing treatment conditions may be used, but for example, the chemical polishing treatment may be immersed in a phosphoric acid / nitric acid mixed solution at 95 ° C. for about 5 minutes.
• Anodizing treatment This is a treatment for forming an anodizing film on the surface of an aluminum alloy die-cast material.
• Known anodizing conditions may be used. For example, H 2 SO 4 having a concentration of 180 g / l is used as a solution, the solution temperature is 18 ° C., the current density is 150 A / m 2, and the energization treatment is performed for 33 minutes and 20 seconds. Should be applied.
• Dyeing treatment This is a treatment in which an organic dye or the like is allowed to penetrate into the fine pores of the anodized film to color it.
• the dyeing treatment conditions known ones may be used. When imparting a dark color, it is common to immerse it in an aqueous solution adjusted to a high concentration of organic dyes for a long time, and when imparting a light color, it is generally immersed in an aqueous solution adjusted to a low concentration of organic dyes, etc. for a short time. Is. When this treatment is omitted, the color of the anodized film itself is mainly reflected in the color tone and texture of the die casting material.
• Pore Sealing Treatment This is a treatment for closing the fine pores existing in the anodized film.
• known ones may be used.
• a nickel acetate-based pore-sealing agent may be used as a solution, and the solution may be immersed in a solution at 95 ° C. for about 30 minutes.
• Example 1 >> In Table 1, an aluminum alloy having the composition described as Example 1 was melted, the casting pressure was 120 MPa, the molten metal temperature was 730 ° C, and the mold temperature was 170 ° C, and die casting was performed.
• the mold shape is a plate shape of 55 mm ⁇ 110 mm ⁇ 3 mm.
• the unit of numerical values shown in Table 1 is mass% concentration.
• a No. 14B test piece specified in JIS-Z2241 was collected from the obtained aluminum alloy die-cast material and subjected to a tensile test at room temperature. As a result, the 0.2% proof stress and Vickers hardness were as shown in Table 2. It was.
• the obtained aluminum alloy die cast material was blasted with fine particles of ZrO 2 and SiO 2 having a grain size of 125 to 250 ⁇ m and an injection pressure of 0.4 MPa, and a halogenated hydrocarbon was used as a solvent at 72 ° C.
• a degreasing treatment that injects steam for 1 minute
• a desmat treatment that uses HNO 3 with a concentration of 200 g / l as a bath solution, soaks it at room temperature for about 1 minute, and irradiates it with ultrasonic waves.
• Chemical polishing treatment by immersing in a mixed solution of phosphoric acid and nitric acid at ° C for 5 minutes , using H 2 SO 4 at a concentration of 180 g / l as a solution, setting the solution temperature to 18 ° C and a current density of 150 A / m 2, and energizing for 33 minutes and 20 seconds.
• Anodization treatment and a pore-sealing treatment in which a nickel acetate-based pore-forming agent was used as a solution and immersed in a solution at 95 ° C. for 30 minutes were sequentially performed to obtain an aluminum alloy diecast material having an anodized film.
• the L * value, a * value, and b * value (CIELab color space) of the obtained aluminum alloy die-cast material having an anodized film were measured by the color measuring method specified in JISZ8781.
• the presence or absence of color unevenness was visually determined, and when there was no color unevenness, ⁇ was given, when there was slight color unevenness, ⁇ was given, and when there was some color unevenness, ⁇ was given and evaluated.
• the granular crystal region was identified from the obtained optical micrograph, and the area ratio with respect to the entire observed image was calculated. If the area ratio of the granular crystal region exceeded 90%, it was judged as ⁇ , and if it did not exceed 90%, it was judged as x.
• Comparative Example 1 A test piece was collected in the same manner as in Example 1 except that the dissolving material was adjusted so as to have the components described as Comparative Example 1 in Table 1, and the 0.2% proof stress was measured. It became a value.
• Comparative Example 2 A test piece was collected in the same manner as in Example 1 except that the dissolving material was adjusted so as to have the components described as Comparative Example 2 in Table 1, and the 0.2% proof stress was measured. It became a value.
• Comparative Example 3 As a result of anodization treatment and color measurement in the same manner as in Example 1 except that the dissolving material was adjusted so as to have the components described as Comparative Example 3 in Table 1, L * value, a * value, and b * value ( CIELab color space) The evaluations for color unevenness and granular crystal region were the values shown in Table 3.
• the composition of Comparative Example 3 corresponds to ADC12.
• the aluminum alloy die-cast material of the present invention has a 0.2% proof stress of 100 MPa or more and a hardness of 60 HV or more.
• the aluminum alloy die-cast material of Comparative Example 3 has a high 0.2% proof stress and Vickers hardness, while the aluminum alloy die-cast materials of Comparative Examples 1 and 2 have a 0.2% proof stress of less than 100 MPa. And the hardness is less than 60HV.
• the aluminum alloy die-cast material provided with the anodic oxide film of about 5 ⁇ m of the present invention has an L * value of 70 or more when the light source is the CIE standard Illuminant D65 in the color measurement on the surface of the anodic oxide film.
• the a * value is in the range of 0 to 2
• the b * value is in the range of 1 to 4.
• the a * value and the b * value are within the range, but in Example 3, the L * value is significantly low. It has become.

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