WO2015025706A1 - High-strength aluminum alloy and method for producing same - Google Patents
High-strength aluminum alloy and method for producing same Download PDFInfo
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- WO2015025706A1 WO2015025706A1 PCT/JP2014/070555 JP2014070555W WO2015025706A1 WO 2015025706 A1 WO2015025706 A1 WO 2015025706A1 JP 2014070555 W JP2014070555 W JP 2014070555W WO 2015025706 A1 WO2015025706 A1 WO 2015025706A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/053—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with zinc as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/56—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
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- 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
- C22C21/10—Alloys based on aluminium with zinc as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
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- 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
- C25D11/16—Pretreatment, e.g. desmutting
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- 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
Definitions
- the present invention relates to a high-strength aluminum alloy used at a site where both at least appearance characteristics and stress corrosion cracking resistance are regarded as important.
- Aluminum alloys are increasingly used as materials used in sports equipment, transportation equipment, machine parts and other applications where strength and appearance characteristics are important. Since durability is required for these uses, it is desired to use a high-strength aluminum alloy having a proof stress of 350 MPa or more.
- an aluminum alloy extruded material described in Patent Document 1 has been proposed.
- Patent Document 1 The 7000 series aluminum alloy disclosed in Patent Document 1 has a problem that stress corrosion cracking is likely to occur when T6 treatment is performed by aging treatment. Further, as a countermeasure, overaging treatment can improve the stress corrosion cracking resistance, but there is a problem that the strength is lowered.
- the conventional 7000 series aluminum alloy described in Patent Document 1 has a high yield strength, but it cannot be said that measures against stress corrosion cracking are taken. Therefore, these alloys are not suitable for applications that are used for a long time in a state where stress is always applied in a corrosive environment.
- the present invention has been made in view of such a background, and an object of the present invention is to provide a high-strength aluminum alloy excellent in surface quality and stress corrosion cracking resistance after anodizing, and a method for producing the same.
- One aspect of the present invention is a high-strength aluminum alloy that is anodized, In mass%, Zn: 5.0% to 7.0%, Mg: 2.2% to 3.0%, Cu: 0.01% to 0.10%, Zr: 0.10% or less Cr: 0.02% or less, Fe: 0.30% or less, Si: 0.30% or less, Mn: 0.02% or less, Ti: 0.001% or more and 0.05% or less, and the balance Having a chemical component having a Zn / Mg ratio of 1.7 or more and 3.1 or less, and consisting of Al and inevitable impurities, Yield strength is 350 MPa or more,
- the high-strength aluminum alloy is characterized in that the metal structure is a recrystallized structure.
- Another aspect of the present invention is a method for producing the high-strength aluminum alloy, In mass%, Zn: 5.0% to 7.0%, Mg: 2.2% to 3.0%, Cu: 0.01% to 0.10%, Zr: 0.10% or less Cr: 0.02% or less, Fe: 0.30% or less, Si: 0.30% or less, Mn: 0.02% or less, Ti: 0.001% or more and 0.05% or less, and the balance Is made of Al and inevitable impurities, and ingot having a chemical component having a Zn / Mg ratio of 1.7 or more and 3.1 or less, A homogenization treatment is performed in which the ingot is heated at a temperature of 540 ° C. to 580 ° C.
- the ingot is hot-worked to obtain a wrought material
- the average cooling rate while the temperature of the wrought material is in the range of 400 ° C. to 150 ° C. is 1 ° C./second to 300 ° C./second.
- the high-strength aluminum alloy has the specific chemical component, has a proof stress of 350 MPa or more, and has a recrystallized structure.
- the above high-strength aluminum alloy has high strength, excellent stress corrosion cracking resistance, and excellent surface quality after anodizing treatment, strength characteristics, appearance characteristics and stress corrosion cracking resistance. Can be suitably used for a site where importance is attached.
- the high-strength aluminum alloy can ensure excellent stress corrosion cracking characteristics by having the above specific chemical component, and thus exhibits excellent durability even when used in a corrosive environment. can do.
- the high-strength aluminum alloy has a yield strength equal to or higher than that of the conventional 7000 series aluminum alloy material, that is, a yield strength of 350 MPa or more. Therefore, for example, strength requirements such as ensuring strength characteristics that can cope with thinning for weight reduction can be satisfied relatively easily.
- the high-strength aluminum alloy has the specific chemical component and the metal structure is composed of a recrystallized structure, so that a streak pattern caused by the fibrous structure is generated after the anodizing treatment. Can be suppressed, and good surface quality can be obtained.
- the high-strength aluminum alloy is produced by the specific treatment temperature, treatment time, and treatment procedure. Therefore, the above excellent high strength aluminum alloy can be easily obtained.
- the high-strength aluminum alloy is, in mass%, Zn: 5.0% to 7.0%, Mg: 2.2% to 3.0%, Cu: 0.01% to 0.10%, Zr: 0.10% or less, Cr: 0.02% or less, Fe: 0.30% or less, Si: 0.30% or less, Mn: 0.02% or less, Ti: 0.001% or more and 0.05 %, And the balance is composed of Al and inevitable impurities, and has a chemical component having a Zn / Mg ratio of 1.7 or more and 3.1 or less.
- Zn 5.0% to 7.0%
- Zn is an element that precipitates the ⁇ ′ phase by coexisting with Mg in the aluminum alloy.
- the Zn content is preferably more than 5.0%, and more preferably 5.2% or more.
- the Zn content is preferably 7.0% or less, and preferably 6.8% or less.
- Mg 2.2% to 3.0% or less
- Mg is an element that precipitates the ⁇ ′ phase by coexisting with Zn in the aluminum alloy.
- strength improvement by precipitation strengthening can be obtained.
- the Mg content is 2.2% or less, the precipitation amount of the ⁇ ′ phase is reduced, and the strength improvement effect is reduced.
- the Mg content exceeds 3.0%, the hot workability is lowered, the productivity is lowered, and the stress corrosion cracking resistance is lowered.
- Zn / Mg ratio 1.7 or more and 3.1 or less
- the contents of Zn and Mg are selected so that they are within the above-mentioned limited ranges, and the value of the Zn content / Mg content ratio is always within the range of 1.7 to 3.1. If the Zn / Mg ratio is less than 1.7, the strength tends to be low, whereas if it exceeds 3.1, the stress corrosion cracking resistance is lowered.
- Zn / Mg ratio means the value of Zn content (mass%) / Mg content (mass%).
- Cu may be mixed when a recycled material is used as a raw material for the high-strength aluminum alloy material.
- the Cu content exceeds 0.10%, the surface quality deteriorates, such as a decrease in gloss after chemical polishing and a change in color tone to yellow due to anodizing treatment. If it is less than 01%, the stress corrosion cracking resistance decreases. Such deterioration of stress corrosion cracking resistance and surface quality can be avoided by controlling the Cu content to 0.01% or more and 0.10% or less.
- Zr 0.10% or less
- the content of Zr exceeds 0.10%, generation of a recrystallized structure is suppressed, and a fibrous structure is easily generated instead. If the fibrous structure is present, the streak pattern resulting from the fibrous structure is likely to appear on the surface after the anodizing treatment, so that the surface quality may be deteriorated. Therefore, the Zr content is 0.10% or less.
- the surface after the anodizing treatment may have a yellow color tone. Such deterioration of the surface quality due to color change or the like can be suppressed by regulating the Cr content to less than 0.02%.
- Fe 0.30% or less
- Si 0.30% or less
- Mn 0.02% or less
- Fe and Si are mixed as impurities in the aluminum ingot
- Mn is a component that may be mixed when using recycled materials.
- Fe, Si, and Mn have an action of suppressing recrystallization by forming an AlMn-based, AlMnFe-based, or AlMnFeSi-based intermetallic compound with Al. For this reason, when the three components are excessively mixed in the high-strength aluminum alloy material, the generation of a recrystallized structure is suppressed, and a fibrous structure is easily generated instead.
- a streak pattern resulting from the fibrous structure is likely to appear on the surface after the anodizing treatment, so that the surface quality may be deteriorated.
- Such deterioration of the surface quality due to the streak pattern can be suppressed by regulating Fe to 0.30% or less, Si to 0.30% or less, and Mn to 0.02% or less. It becomes.
- Ti 0.001% or more and 0.05% or less, Ti has the effect
- the Ti content is less than 0.001%, the ingot structure is not sufficiently refined, and there is a possibility that spots and streaks are formed on the surface of the high-strength aluminum alloy material.
- the Ti content is more than 0.05%, AlTi-based intermetallic compounds formed between the Al and the like, it is easy to generate a dot-like or streak-like defect, The surface quality may be deteriorated.
- the high-strength aluminum alloy material has a metal structure composed of a granular recrystallized structure.
- an aluminum alloy produced by hot working has a metal structure composed of a fibrous structure, so that a streak pattern is generated on the surface, and as a result, the surface quality may be lowered.
- the metal structure is composed of a recrystallized structure, no streak pattern is generated on the surface, and the surface quality is good.
- the high-strength aluminum alloy has a b * value in the L * a * b * color system defined by JIS Z8729 (ISO 7724-1) (blue to 4) measured after anodizing using a sulfuric acid bath.
- the chromaticity of yellow is preferably 0 or more and 0.8 or less.
- the high-strength aluminum alloy material can achieve a color tone with a b * value of 0.8 or less by having at least the specific chemical component.
- the b * value exceeds 0.8, the color tone is yellowish after the anodizing treatment, which may reduce the designability.
- anodizing is performed on an aluminum alloy material having the above chemical components, it is difficult to obtain an aluminum alloy material having a b * value that is less than 0.
- the recrystallized structure has an average grain size of 500 ⁇ m or less, and the crystal length in the direction parallel to the hot working direction is 0 with respect to the crystal length perpendicular to the hot working direction. It is preferably 5 times or more and 4 times or less.
- the average grain size of the crystal grains exceeds 500 ⁇ m, the crystal grains become excessively coarse, so that after surface treatment such as anodic oxidation treatment, spots are likely to occur and the surface quality may be deteriorated. . Therefore, the smaller the average grain size of the crystal grains, the better.
- the aspect ratio of the crystal grains that is, the ratio of the crystal length in the direction parallel to the hot working direction to the crystal length in the direction perpendicular to the hot working direction exceeds 4
- the anodic oxidation treatment is performed.
- the said metal structure can confirm whether it is a recrystallized structure, for example by performing electropolishing on the surface of an aluminum alloy material, and observing the obtained surface with a polarizing microscope. That is, when the metal structure is a recrystallized structure, a uniform metal structure composed of granular crystals is observed, and solidified structures that can be formed during casting, such as coarse intermetallic compounds and suspended crystals, are observed. I can't. Similarly, in the metal structure composed of the recrystallized structure, a streak structure (so-called processed structure) formed by plastic processing such as extrusion or rolling is not observed.
- the average grain size of the crystal grains in the recrystallized structure is defined in JIS G0551 (ASTM E 112-96, ASTM E 1382-97) with respect to the metal structure image obtained by observation using the polarizing microscope. It can be calculated according to the cutting method. That is, by drawing one cutting line in each of the vertical, horizontal and diagonal directions at an arbitrary position in the metal structure image, and dividing the length of the cutting line by the number of grain boundaries crossing the cutting line. The average particle size can be calculated.
- the aspect ratio that is, the ratio of the crystal length in the direction parallel to the hot working direction to the crystal length in the direction perpendicular to the hot working direction
- the aspect ratio can be calculated according to the method described above. That is, in the same manner as described above, a cutting line in the direction parallel to the hot working direction and a direction perpendicular to the hot working direction is drawn to an arbitrary position in the metal structure image, and a direction parallel to the hot working direction from each cutting line. And the average particle size in the perpendicular direction is calculated. Then, the aspect ratio can be calculated by dividing the average particle size in the direction parallel to the hot working direction by the average particle size in the direction perpendicular to the hot working direction.
- the recrystallized structure is preferably generated during hot working.
- the recrystallized structure can be classified into a dynamic recrystallized structure and a static recrystallized structure depending on the manufacturing process. It is called crystal structure.
- a static recrystallized structure refers to a structure generated by adding a heat treatment step such as solution treatment or annealing treatment after hot working or cold working.
- a homogenization treatment is performed in which the ingot having the chemical component is heated at a temperature exceeding 540 ° C. and not more than 580 ° C. for 1 hour to 24 hours. Do.
- the heating temperature for the homogenization treatment is 540 ° C. or less, the ingot segregation layer is not sufficiently homogenized. As a result, coarsening of crystal grains, formation of a non-uniform crystal structure, and the like occur, so that the surface quality of the finally obtained alloy material is deteriorated.
- the heating temperature is higher than 580 ° C., the ingot is likely to be locally melted, which makes it difficult to manufacture. Accordingly, the temperature of the homogenization treatment is preferably more than 540 ° C. and not more than 580 ° C.
- the homogenization time is preferably 1 hour or more and 24 hours or less.
- the ingot that has been subjected to the above homogenization treatment is subjected to hot working to obtain a wrought material.
- the temperature of the ingot at the start of hot working is 440 ° C. or higher and 560 ° C. or lower.
- the heating temperature of the ingot before hot working is lower than 440 ° C., the deformation resistance is high, and it is difficult to work with a commonly used manufacturing facility.
- the temperature of the ingot before hot working is preferably 440 ° C. or higher and 560 ° C. or lower.
- an extrusion process, a rolling process, etc. are employable.
- the temperature of the wrought material is 400 ° C. or higher, and rapid cooling is performed until the temperature of the wrought material becomes 150 ° C. or lower.
- the quenching effect becomes insufficient, and the resulting wrought material may have a yield strength of less than 350 MPa.
- the temperature of the wrought material after the rapid cooling treatment exceeds 150 ° C., the quenching effect becomes insufficient, and the proof stress of the resulting wrought material may be less than 350 MPa.
- the said rapid cooling process means the process which cools the said wrought material by a forced means.
- a forced means for example, forced rapid cooling with a fan, shower cooling, or water cooling can be employed.
- the rapid cooling treatment is performed by controlling the average cooling rate to 1 ° C./second or more and 300 ° C./second or less while the temperature of the wrought material is in the range of 400 ° C. to 150 ° C.
- the average cooling rate exceeds 300 ° C./second, the equipment becomes excessive and an effect commensurate with it cannot be obtained.
- the average cooling rate is less than 1 ° C./second, the quenching effect becomes insufficient, and the yield strength of the obtained wrought material may be less than 350 MPa.
- the average cooling rate should be fast, preferably 1 ° C./second or more and 300 ° C./second or less, preferably 3 ° C./second or more and 300 ° C./second or less.
- the temperature of the wrought material is allowed to reach room temperature. This may reach room temperature by the quenching process, or may be reached by performing an additional cooling process after the quenching process. By causing the temperature of the wrought material to reach room temperature, an effect of room temperature aging appears, so that the strength of the wrought material is improved.
- a method such as fan air cooling, mist cooling, shower cooling, or water cooling can be employed.
- the strength of the wrought material is further improved by the aging effect at room temperature.
- the strength is improved as the time is long in the initial stage, but when the room temperature aging time is 24 hours or more, the effect of room temperature aging becomes saturated.
- artificial aging treatment is performed in which the wrought material that has been cooled to room temperature as described above is heated.
- MgZn 2 precipitates finely and uniformly in the wrought material, so that the proof stress of the wrought material can be easily increased to 350 MPa or more.
- any of the following embodiments can be applied.
- a first artificial aging treatment is performed in which the wrought material is heated at a temperature of 80 to 120 ° C. for 1 to 5 hours.
- a second artificial aging treatment can be performed in which the material is heated at a temperature of 145 to 200 ° C. for 2 to 15 hours.
- the first artificial aging treatment and the second artificial aging treatment are performed continuously, after the first artificial aging treatment is completed, the second artificial aging treatment is performed while maintaining the temperature of the wrought material. It means that. That is, it is sufficient that the wrought material is not cooled between the first artificial aging treatment and the second artificial aging treatment.
- the first aging treatment is not taken out from the heat treatment furnace. 2 There is a method of performing artificial aging treatment.
- the artificial aging treatment time can be shortened by continuously performing the first artificial aging treatment and the second artificial aging treatment.
- the treatment temperature in the second artificial aging treatment is preferably 145 to 200 ° C.
- the ductility of the wrought material is increased, so that the workability can be further improved.
- stress corrosion cracking of the obtained wrought material is likely to occur or the proof stress may be less than 350 MPa. .
- the wrought material can be heated at a temperature of 145 to 170 ° C. for 1 to 24 hours. In this case, since the manufacturing process becomes simple, it can be manufactured easily. If the above artificial aging treatment is out of the above temperature range or time range, the resulting wrought material may be susceptible to stress corrosion cracking, and the proof stress may be less than 350 MPa. It becomes difficult to obtain a drawn material.
- Example 1 Examples relating to the high-strength aluminum alloy material will be described with reference to Tables 1 to 3.
- samples No. 1 to No. 30
- the chemical composition of the aluminum alloy material was changed were prepared under the same manufacturing conditions, and the strength measurement and metal structure observation of each sample were performed. went. Furthermore, after surface-treating each sample, the surface quality was evaluated.
- the manufacturing conditions, strength measurement method, metal structure observation method, surface treatment method, and surface quality evaluation method for each sample will be described below.
- Example manufacturing conditions An ingot with a diameter of 90 mm having the chemical components described in Table 1 and Table 2 is cast by semi-continuous casting. Then, the homogenization process which heats this ingot for 6 hours at the temperature of 550 degreeC is performed. Thereafter, in the state where the temperature of the ingot is 520 ° C., the ingot is hot-extruded to form a stretched material having a width of 35 mm and a thickness of 7 mm. Thereafter, in the state where the temperature of the wrought material is 505 ° C., a rapid cooling process is performed in which the wrought material is cooled to 100 ° C. at an average cooling rate of 60 ° C./second.
- the said wrought material which performed the said rapid cooling process is cooled to room temperature, and room temperature aging is performed at room temperature for 24 hours. Thereafter, a first artificial aging treatment is performed in which the wrought material is heated at a temperature of 100 ° C. for 4 hours using a heat treatment furnace. Next, without removing the wrought material from the heat treatment furnace, the furnace temperature is raised to 160 ° C., and a second artificial aging treatment is performed by heating at 160 ° C. for 8 hours to obtain a sample.
- ⁇ Strength measurement method> A test piece is collected from the sample by a method in accordance with JIS Z2241 (ISO 6892-1), and a tensile test for measuring tensile strength, proof stress and elongation is performed. What shows the yield strength of 350 Mpa or more in the result of a tensile test is determined that the strength characteristic is acceptable.
- ⁇ Metallic structure observation method> After electrolytic polishing and electrolytic etching of the sample, a microscopic image of the sample surface is obtained with a polarizing microscope having a magnification of 50 to 100 times. Image analysis is performed on the microscopic image, and as described above, the average grain size of the crystal grains constituting the metal structure of the sample is obtained according to the cutting method defined in JIS G0551.
- the aspect ratio (the ratio of the crystal length in the direction parallel to the hot working direction to the crystal length in the direction perpendicular to the hot working direction) is the average of the directions parallel to the hot working direction as described above. Calculated by dividing the particle size by the average particle size perpendicular to the hot working direction. As a result, those having an average particle diameter of 500 ⁇ m or less and those having an aspect ratio in the range of 0.5 to 4.0 are determined as preferable results.
- ⁇ Surface treatment method The surface of the sample subjected to the artificial aging treatment is buffed, etched with an aqueous sodium hydroxide solution, and then desmutted. The sample subjected to the desmut treatment is subjected to chemical polishing for 2 minutes at a temperature of 90 ° C. using a phosphoric acid-nitric acid method. The chemically polished sample is anodized at a current density of 150 A / m 2 in a 15% sulfuric acid bath to form a 10 ⁇ m anodic oxide film. Finally, the sample after the anodizing treatment is immersed in boiling water, and the sealing treatment of the anodized film is performed.
- ⁇ Surface quality evaluation method The surface of the sample subjected to the surface treatment is visually observed. In visual observation, what does not appear a streak pattern, a spot-like pattern, or a point defect on the surface is determined to be acceptable. Next, the color tone of the surface of the sample is measured by a color difference meter, and the value of each coordinate in the L * a * b * color system described in JIS Z8729 is obtained. As a result, a value in the range of b * value (blue to yellow chromaticity): 0 to 0.8 is determined to be acceptable.
- ⁇ Stress corrosion cracking test method> The test is performed in accordance with JIS H8711 (ISO-9591). From each sample, a C-ring-shaped test piece provided with a notch in a part of the circumference is cut out from a ring shape having an outer diameter of 20 mm, an inner diameter of 17 mm, and an axial thickness of 7 mm. The direction connecting the center of the C-ring shape and the notch is aligned with the direction of extrusion during sample preparation. A stress of 330 MPa is applied to the test piece in a direction in which the C-ring shape is contracted in a direction perpendicular to the extrusion direction.
- Table 3 shows the evaluation results of the samples shown in Tables 1 and 2. In addition, about what was not determined to be acceptable or not preferable in each evaluation result, the evaluation result in Table 3 is underlined.
- Samples 1 to 15 passed all the evaluation items, and exhibited excellent properties in terms of strength, surface quality, and stress corrosion cracking resistance.
- FIG. As a representative example of a sample having excellent surface quality, FIG. As is known from the figure, the sample having an excellent surface quality has a metal structure composed of a granular recrystallized structure, and at the same time, no streak pattern is observed in visual confirmation, and there is no spot and high gloss.
- sample 19 had too high Mg content, it cracked partially at the time of extrusion, and also the resistance to stress corrosion cracking was inferior, and it was determined to be unacceptable. Since the sample 20 had a Zn / Mg ratio that was too low, the strength was inferior and it was determined to be unacceptable. Sample 21 was judged to be rejected because the stress corrosion cracking property was lowered because the Zn / Mg ratio was too high.
- sample 25 had too high Si content, as a result of forming a fibrous structure, the streak pattern was visually recognized on the surface and it was determined to be unacceptable.
- sample 26 since the Mn content was too high, a fibrous structure was formed. As a result, a streak pattern was visually recognized on the surface, and the sample 26 was determined to be unacceptable.
- sample 27 had too high Cr content, the color of the surface was yellowish and it was determined to be unacceptable.
- sample 28 Since the sample 28 has a Zr content that is too high, as a result of forming a fibrous structure, a streak pattern is visually recognized on the surface, and the sample 28 is determined to be unacceptable.
- Sample 29 since the Ti content was too low, a streak pattern resulting from a coarse ingot structure appeared and it was determined to be unacceptable.
- the sample 30 had an excessively high Ti content, an intermetallic compound with Al was formed. As a result, streaky and point-like defects were visually recognized on the surface, and the sample 30 was determined to be rejected.
- Example 2 examples according to the method for producing the high-strength aluminum alloy will be described with reference to Tables 4 to 6.
- aluminum alloys material No. A
- samples No. A1 to A29
- the strength of each sample was measured and the metal structure was observed. Furthermore, after surface-treating each sample, the surface quality was evaluated.
- the strength measurement method, metal structure observation method, surface treatment method, and surface quality evaluation method for each sample were performed in the same manner as in Example 1.
- Example manufacturing conditions An ingot with a diameter of 90 mm having the chemical components described in Table 4 is cast by semi-continuous casting. Thereafter, using the combination of temperature, time or average cooling rate shown in Table 5 and Table 6, the ingot is subjected to homogenization treatment, hot extrusion processing, rapid cooling treatment, first artificial aging treatment and second artificial aging treatment. Apply in this order to obtain each sample.
- the room temperature aging time described in Tables 5 and 6 means the time from when the wrought material reaches room temperature until the first artificial aging treatment is performed after the rapid cooling treatment.
- Table 7 shows the evaluation results of each sample prepared as described above. In addition, about the thing which was not determined with the pass in each measurement result, or the thing which was not determined with the preferable result, the said evaluation result in Table 7 was underlined and shown.
- sample A18 Since the heating temperature in the homogenization process was too low for sample A18, the yield strength was less than 350 MPa, and the sample A18 was determined to be rejected. At the same time, the crystal grains became coarse, and spotted patterns were also visually recognized on the surface. Sample A19 was judged to be unacceptable because its proof stress was less than 350 MPa because the treatment time in the homogenization treatment was too short. At the same time, the crystal grains became coarse, and spotted patterns were also visually recognized on the surface.
- Sample A23 was over-aged because the treatment temperature in the second artificial aging treatment was too high, and the yield strength was less than 350 MPa, and the sample A23 was determined to be rejected.
- Sample A24 was judged to be rejected because the treatment time in the second artificial aging treatment was too short, so that age hardening was insufficient and the proof stress was less than 350 MPa, and the stress corrosion cracking resistance was insufficient.
- Sample A25 was over-aged because the treatment time in the second artificial aging treatment was too long, and the yield strength was less than 350 MPa, which was determined to be unacceptable.
- Sample A26 was subjected to only one stage of artificial aging treatment. However, since the treatment temperature in the artificial aging treatment was too low, the stress corrosion cracking resistance was insufficient, and the sample A26 was determined to be rejected.
- Sample A27 was subjected to only one stage of artificial aging treatment, but because the treatment temperature in the artificial aging treatment was too high, it was overaged and the yield strength was less than 350 MPa, and it was determined to be unacceptable.
- Sample A28 the treatment time in the first artificial aging treatment was too short, so that age hardening was insufficient and the proof stress was less than 350 MPa, and the sample A28 was determined to be unacceptable.
- Test A29 was over-aged because the treatment time in the first artificial aging treatment was too long, and the yield strength was less than 350 MPa, and it was determined to be unacceptable.
- FIG. 2 shows a metal structure observation result of the sample A19.
- the sample in which the streak pattern was visually recognized has a metal structure composed of a fibrous structure, as is known from FIG.
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Abstract
Description
本発明は、かかる背景に鑑みてなされたもので、陽極酸化処理後における表面品質および耐応力腐食割れ性に優れた高強度アルミニウム合金およびその製造方法を提供しようとするものである。 As described above, for example, the conventional 7000 series aluminum alloy described in Patent Document 1 has a high yield strength, but it cannot be said that measures against stress corrosion cracking are taken. Therefore, these alloys are not suitable for applications that are used for a long time in a state where stress is always applied in a corrosive environment.
The present invention has been made in view of such a background, and an object of the present invention is to provide a high-strength aluminum alloy excellent in surface quality and stress corrosion cracking resistance after anodizing, and a method for producing the same.
質量%において、Zn:5.0%以上7.0%以下、Mg:2.2%超え3.0%以下、Cu:0.01%以上0.10%以下、Zr:0.10%以下、Cr:0.02%以下、Fe:0.30%以下、Si:0.30%以下、Mn:0.02%以下、Ti:0.001%以上0.05%以下を含有し、残部がAl及び不可避的不純物からなると共に、Zn/Mg比が1.7以上3.1以下である化学成分を有し、
耐力が350MPa以上であり、
金属組織が再結晶組織よりなることを特徴とする高強度アルミニウム合金にある。 One aspect of the present invention is a high-strength aluminum alloy that is anodized,
In mass%, Zn: 5.0% to 7.0%, Mg: 2.2% to 3.0%, Cu: 0.01% to 0.10%, Zr: 0.10% or less Cr: 0.02% or less, Fe: 0.30% or less, Si: 0.30% or less, Mn: 0.02% or less, Ti: 0.001% or more and 0.05% or less, and the balance Having a chemical component having a Zn / Mg ratio of 1.7 or more and 3.1 or less, and consisting of Al and inevitable impurities,
Yield strength is 350 MPa or more,
The high-strength aluminum alloy is characterized in that the metal structure is a recrystallized structure.
質量%において、Zn:5.0%以上7.0%以下、Mg:2.2%超え3.0%以下、Cu:0.01%以上0.10%以下、Zr:0.10%以下、Cr:0.02%以下、Fe:0.30%以下、Si:0.30%以下、Mn:0.02%以下、Ti:0.001%以上0.05%以下を含有し、残部がAl及び不可避的不純物からなると共に、Zn/Mg比が1.7以上3.1以下である化学成分を有する鋳塊を作製し、
上記鋳塊を540℃超え580℃以下の温度で1~24時間加熱する均質化処理を行い、
加工開始時における上記鋳塊の温度を440℃~560℃とした状態で該鋳塊に熱間加工を施して展伸材とし、
該展伸材の温度が400℃以上である間に冷却を開始した後、該展伸材の温度が400℃から150℃の範囲にある間の平均冷却速度を1℃/秒以上300℃/秒以下に制御して冷却する急冷処理を行い、
該急冷処理またはその後の冷却により該展伸材の温度を室温まで冷却し、
その後、該展伸材に対して人工時効処理を行うことを特徴とする高強度アルミニウム合金の製造方法にある。 Another aspect of the present invention is a method for producing the high-strength aluminum alloy,
In mass%, Zn: 5.0% to 7.0%, Mg: 2.2% to 3.0%, Cu: 0.01% to 0.10%, Zr: 0.10% or less Cr: 0.02% or less, Fe: 0.30% or less, Si: 0.30% or less, Mn: 0.02% or less, Ti: 0.001% or more and 0.05% or less, and the balance Is made of Al and inevitable impurities, and ingot having a chemical component having a Zn / Mg ratio of 1.7 or more and 3.1 or less,
A homogenization treatment is performed in which the ingot is heated at a temperature of 540 ° C. to 580 ° C. for 1-24 hours,
In the state where the temperature of the ingot at the start of processing is 440 ° C. to 560 ° C., the ingot is hot-worked to obtain a wrought material,
After starting the cooling while the temperature of the wrought material is 400 ° C. or higher, the average cooling rate while the temperature of the wrought material is in the range of 400 ° C. to 150 ° C. is 1 ° C./second to 300 ° C./second. Performs a rapid cooling process to cool by controlling to less than a second,
Cooling the temperature of the wrought material to room temperature by the rapid cooling treatment or subsequent cooling;
Thereafter, an artificial aging treatment is performed on the wrought material.
Znは、アルミニウム合金中においてMgと共存することでη’相を析出させる元素である。Mgと共にZnを含有させることにより、析出強化による強度向上を得ることができる。Znの含有量が5.0%以下の場合には、η’相の析出量が少なくなるため、強度向上効果が低くなる。そのため、Znの含有量は5.0%より多い方が良く、好ましくは5.2%以上が良い。一方、Znの含有量が7.0%を超えると、耐応力腐食割れ性が低下する。そのため、Znの含有量は7.0%以下が良く、好ましくは6.8%以下が良い。 Zn: 5.0% to 7.0%,
Zn is an element that precipitates the η ′ phase by coexisting with Mg in the aluminum alloy. By containing Zn together with Mg, strength improvement by precipitation strengthening can be obtained. When the Zn content is 5.0% or less, the amount of precipitation of the η ′ phase is reduced, and the strength improvement effect is reduced. Therefore, the Zn content is preferably more than 5.0%, and more preferably 5.2% or more. On the other hand, if the Zn content exceeds 7.0%, the stress corrosion cracking resistance is lowered. Therefore, the Zn content is preferably 7.0% or less, and preferably 6.8% or less.
Mgは、アルミニウム合金中においてZnと共存することでη’相を析出させる元素である。Znと共にMgを含有させることにより、析出強化による強度向上を得ることができる。Mgの含有量が2.2%以下の場合には、η’相の析出量が少なくなるため、強度向上効果が低くなる。一方、Mgの含有量が3.0%を超えると、熱間加工性が低下し生産性が低下するとともに、耐応力腐食割れ性が低下する。 Mg: 2.2% to 3.0% or less,
Mg is an element that precipitates the η ′ phase by coexisting with Zn in the aluminum alloy. By containing Mg together with Zn, strength improvement by precipitation strengthening can be obtained. When the Mg content is 2.2% or less, the precipitation amount of the η ′ phase is reduced, and the strength improvement effect is reduced. On the other hand, if the Mg content exceeds 3.0%, the hot workability is lowered, the productivity is lowered, and the stress corrosion cracking resistance is lowered.
ZnとMgの含有量はそれぞれ上述した限定範囲内で、かつ、必ず、上記Zn量/Mg量比の値が1.7~3.1の範囲内となるように、選択する。Zn/Mg比が1.7未満の場合には強度が低くなりやすく、一方、3.1を超える場合には耐応力腐食割れ性が低下する。なお、Zn/Mg比は、Zn含有量(質量%)/Mg含有量(質量%)の値を意味する。 Zn / Mg ratio: 1.7 or more and 3.1 or less,
The contents of Zn and Mg are selected so that they are within the above-mentioned limited ranges, and the value of the Zn content / Mg content ratio is always within the range of 1.7 to 3.1. If the Zn / Mg ratio is less than 1.7, the strength tends to be low, whereas if it exceeds 3.1, the stress corrosion cracking resistance is lowered. In addition, Zn / Mg ratio means the value of Zn content (mass%) / Mg content (mass%).
Cuは、上記高強度アルミニウム合金材の原料としてリサイクル材を使用する場合に混入する可能性がある。Cuの含有量が0.10%を超える場合には、化学研磨後の光沢の低下や、陽極酸化処理による黄色への色調変化など、表面品質が低下する原因となり、Cuの含有量が0.01%未満の場合には、耐応力腐食割れ性が低下する。このような耐応力腐食割れ性および表面品質の低下は、Cuの含有量を0.01%以上0.10%以下に制御することで回避することができる。 Cu: 0.01% or more and 0.10% or less,
Cu may be mixed when a recycled material is used as a raw material for the high-strength aluminum alloy material. When the Cu content exceeds 0.10%, the surface quality deteriorates, such as a decrease in gloss after chemical polishing and a change in color tone to yellow due to anodizing treatment. If it is less than 01%, the stress corrosion cracking resistance decreases. Such deterioration of stress corrosion cracking resistance and surface quality can be avoided by controlling the Cu content to 0.01% or more and 0.10% or less.
Zrの含有量が0.10%を超える場合は、再結晶組織の生成が抑制され、その替わりに繊維状組織が生成されやすくなる。上記繊維状組織が存在すると、陽極酸化処理を行った後に、上記繊維状組織に起因する筋状模様が表面に現れやすくなるため、表面品質が低下するおそれがある。そのため、Zr含有量は0.10%以下とする。 Zr: 0.10% or less,
When the content of Zr exceeds 0.10%, generation of a recrystallized structure is suppressed, and a fibrous structure is easily generated instead. If the fibrous structure is present, the streak pattern resulting from the fibrous structure is likely to appear on the surface after the anodizing treatment, so that the surface quality may be deteriorated. Therefore, the Zr content is 0.10% or less.
Crが0.02%以上含有されている場合には、陽極酸化処理後の表面が黄色の色調を帯びるおそれがある。このような色調変化等による表面品質の低下は、Crの含有量を0.02%未満に規制することで抑制することができる。 Cr: 0.02% or less,
When Cr is contained in an amount of 0.02% or more, the surface after the anodizing treatment may have a yellow color tone. Such deterioration of the surface quality due to color change or the like can be suppressed by regulating the Cr content to less than 0.02%.
Fe、Siはアルミニウム地金中の不純物として混入し、Mnはリサイクル材を使用する場合に混入する可能性のある成分である。Fe、SiおよびMnは、Alとの間にAlMn系、AlMnFe系もしくはAlMnFeSi系の金属間化合物を形成することにより再結晶化を抑制する作用を有する。そのため、上記3成分が上記高強度アルミニウム合金材に過度に混入した場合には再結晶組織の生成が抑制され、その替わりに繊維状組織が生成されやすくなる。繊維状組織が存在すると、陽極酸化処理を行った後に、繊維状組織に起因する筋状模様が表面に現れやすくなるため、表面品質が低下するおそれがある。このような筋状模様による表面品質の低下は、Feを0.30%%以下に、Siを0.30%以下に、Mnを0.02%以下にそれぞれ規制することで抑制することが可能となる。 Fe: 0.30% or less, Si: 0.30% or less, Mn: 0.02% or less,
Fe and Si are mixed as impurities in the aluminum ingot, and Mn is a component that may be mixed when using recycled materials. Fe, Si, and Mn have an action of suppressing recrystallization by forming an AlMn-based, AlMnFe-based, or AlMnFeSi-based intermetallic compound with Al. For this reason, when the three components are excessively mixed in the high-strength aluminum alloy material, the generation of a recrystallized structure is suppressed, and a fibrous structure is easily generated instead. When a fibrous structure is present, a streak pattern resulting from the fibrous structure is likely to appear on the surface after the anodizing treatment, so that the surface quality may be deteriorated. Such deterioration of the surface quality due to the streak pattern can be suppressed by regulating Fe to 0.30% or less, Si to 0.30% or less, and Mn to 0.02% or less. It becomes.
Tiは、アルミニウム合金に添加されることにより鋳塊組織を微細化する作用を有する。鋳塊組織が微細になるほど、斑がなく高い光沢の表面状態が得られるため、Tiが含有されることにより表面品質を向上させることができる。Tiの含有量が0.001%より少ない場合には、鋳塊組織の微細化が充分に為されないため、上記高強度アルミニウム合金材の表面に斑および筋状模様を生じるおそれがある。また、Tiの含有量が0.05%より多い場合には、Alとの間に形成されるAlTi系金属間化合物などが原因となり、点状や筋状模様の欠陥が発生しやすくなるため、表面品質が低下するおそれがある。 Ti: 0.001% or more and 0.05% or less,
Ti has the effect | action which refines | miniaturizes an ingot structure | tissue by adding to an aluminum alloy. As the ingot structure becomes finer, a more glossy surface state without spots is obtained, so that the surface quality can be improved by containing Ti. When the Ti content is less than 0.001%, the ingot structure is not sufficiently refined, and there is a possibility that spots and streaks are formed on the surface of the high-strength aluminum alloy material. In addition, when the Ti content is more than 0.05%, AlTi-based intermetallic compounds formed between the Al and the like, it is easy to generate a dot-like or streak-like defect, The surface quality may be deteriorated.
上記高強度アルミニウム合金材に係る実施例について、表1~表3を用いて説明する。本例では、表1に示すごとく、アルミニウム合金材の化学成分を変化させた試料(No.1~No.30)を同一の製造条件にて作製し、各試料の強度測定、金属組織観察を行った。更に、各試料に表面処理を行った後、表面品質評価を行った。
以下に、各試料の製造条件、強度測定方法及び金属組織観察方法、ならびに表面処理方法及び表面品質評価方法を説明する。 Example 1
Examples relating to the high-strength aluminum alloy material will be described with reference to Tables 1 to 3. In this example, as shown in Table 1, samples (No. 1 to No. 30) in which the chemical composition of the aluminum alloy material was changed were prepared under the same manufacturing conditions, and the strength measurement and metal structure observation of each sample were performed. went. Furthermore, after surface-treating each sample, the surface quality was evaluated.
The manufacturing conditions, strength measurement method, metal structure observation method, surface treatment method, and surface quality evaluation method for each sample will be described below.
半連続鋳造により、表1および表2に記載された化学成分を有する直径90mmの鋳塊を鋳造する。その後、該鋳塊を550℃の温度で6時間加熱する均質化処理を行う。その後、上記鋳塊の温度が520℃である状態で、該鋳塊を熱間押出加工することにより、幅35mm、厚さ7mmの展伸材を形成する。その後、該展伸材の温度が505℃である状態で、該展伸材を60℃/秒の平均冷却速度で100℃まで冷却する急冷処理を行う。そして、上記急冷処理を行った上記展伸材を室温まで冷却し、室温下で24時間の室温時効を行う。その後、熱処理炉を用いて上記展伸材を100℃の温度で4時間加熱する第1人工時効処理を行う。次いで、上記展伸材を熱処理炉から取り出すことなく炉内温度を160℃に昇温し、160℃で8時間加熱する第2人工時効処理を実施して試料とする。 <Sample manufacturing conditions>
An ingot with a diameter of 90 mm having the chemical components described in Table 1 and Table 2 is cast by semi-continuous casting. Then, the homogenization process which heats this ingot for 6 hours at the temperature of 550 degreeC is performed. Thereafter, in the state where the temperature of the ingot is 520 ° C., the ingot is hot-extruded to form a stretched material having a width of 35 mm and a thickness of 7 mm. Thereafter, in the state where the temperature of the wrought material is 505 ° C., a rapid cooling process is performed in which the wrought material is cooled to 100 ° C. at an average cooling rate of 60 ° C./second. And the said wrought material which performed the said rapid cooling process is cooled to room temperature, and room temperature aging is performed at room temperature for 24 hours. Thereafter, a first artificial aging treatment is performed in which the wrought material is heated at a temperature of 100 ° C. for 4 hours using a heat treatment furnace. Next, without removing the wrought material from the heat treatment furnace, the furnace temperature is raised to 160 ° C., and a second artificial aging treatment is performed by heating at 160 ° C. for 8 hours to obtain a sample.
試料から、JIS Z2241(ISO6892-1)に準拠する方法により試験片を採取し、引張強さ、耐力及び伸びの測定する引張試験を行う。引張試験の結果において350MPa以上の耐力を示すものを、強度特性が合格であると判定する。 <Strength measurement method>
A test piece is collected from the sample by a method in accordance with JIS Z2241 (ISO 6892-1), and a tensile test for measuring tensile strength, proof stress and elongation is performed. What shows the yield strength of 350 Mpa or more in the result of a tensile test is determined that the strength characteristic is acceptable.
試料を電解研磨および電解エッチングした後、倍率50倍~100倍の偏光顕微鏡により試料表面の顕微鏡像を取得する。該顕微鏡像に対し画像解析を行い、上述のごとく、JIS G0551に規定された切断法に準じて試料の金属組織を構成する結晶粒の平均粒径を求める。また、アスペクト比(熱間加工方向に直角方向の結晶長さに対する熱間加工方向に平行な方向の結晶長さの比を指す)は、上述のごとく、熱間加工方向に平行な方向の平均粒径を熱間加工方向に直角方向の平均粒径で割ることにより算出する。この結果、平均粒径については500μm以下であるもの、アスペクト比については、0.5~4.0の範囲内にあるものを好ましい結果と判定する。 <Metallic structure observation method>
After electrolytic polishing and electrolytic etching of the sample, a microscopic image of the sample surface is obtained with a polarizing microscope having a magnification of 50 to 100 times. Image analysis is performed on the microscopic image, and as described above, the average grain size of the crystal grains constituting the metal structure of the sample is obtained according to the cutting method defined in JIS G0551. The aspect ratio (the ratio of the crystal length in the direction parallel to the hot working direction to the crystal length in the direction perpendicular to the hot working direction) is the average of the directions parallel to the hot working direction as described above. Calculated by dividing the particle size by the average particle size perpendicular to the hot working direction. As a result, those having an average particle diameter of 500 μm or less and those having an aspect ratio in the range of 0.5 to 4.0 are determined as preferable results.
上記人工時効処理を行った試料の表面をバフ研磨した後、水酸化ナトリウム水溶液によりエッチングを行い、次いでデスマット処理を行う。該デスマット処理を行った試料を、リン酸-硝酸法を用いて90℃の温度で2分間の化学研磨を行う。そして、該化学研磨を行った試料を、15%硫酸浴下において150A/m2の電流密度で陽極酸化処理を行い、10μmの陽極酸化皮膜を形成する。最後に、上記陽極酸化処理後の試料を沸騰水に浸漬し、上記陽極酸化皮膜の封孔処理を行う。 <Surface treatment method>
The surface of the sample subjected to the artificial aging treatment is buffed, etched with an aqueous sodium hydroxide solution, and then desmutted. The sample subjected to the desmut treatment is subjected to chemical polishing for 2 minutes at a temperature of 90 ° C. using a phosphoric acid-nitric acid method. The chemically polished sample is anodized at a current density of 150 A / m 2 in a 15% sulfuric acid bath to form a 10 μm anodic oxide film. Finally, the sample after the anodizing treatment is immersed in boiling water, and the sealing treatment of the anodized film is performed.
上記表面処理を行った試料の表面を目視観察する。目視観察では、表面に筋状模様、斑状模様または点状欠陥等が現れていないものを合格と判定する。
次いで、試料の表面の色調を色差計により計測し、JIS Z8729に記載のL*a*b*表色系における各座標の値を取得する。その結果、b*値(青~黄の色度):0~0.8の範囲内にあるものを合格と判定する。 <Surface quality evaluation method>
The surface of the sample subjected to the surface treatment is visually observed. In visual observation, what does not appear a streak pattern, a spot-like pattern, or a point defect on the surface is determined to be acceptable.
Next, the color tone of the surface of the sample is measured by a color difference meter, and the value of each coordinate in the L * a * b * color system described in JIS Z8729 is obtained. As a result, a value in the range of b * value (blue to yellow chromaticity): 0 to 0.8 is determined to be acceptable.
JIS H8711(ISO-9591)に準拠して試験を実施する。各試料から、外径20mm、内径17mm、軸方向厚さ7mmのリング状形状から円周上の一部に切り欠き部を設けたCリング形状の試験片を削り出す。Cリング形状の中心と切り欠き部とを結ぶ方向は、試料作製時の押出方向に揃える。試験片への応力の負荷は、上記押出方向に直交する方向にCリング形状を縮める方向に、330MPaの応力を負荷する。この負荷状態で、25℃の温度雰囲気中で、試験片の3.5%NaCl水溶液への10分間の浸漬と、50分間の乾燥とを交互に行う交互浸漬を720時間行う。試験結果は、クラック発生の有無で判定する。クラックなしを良(○)、クラックが発生したものを不良(×)とする。 <Stress corrosion cracking test method>
The test is performed in accordance with JIS H8711 (ISO-9591). From each sample, a C-ring-shaped test piece provided with a notch in a part of the circumference is cut out from a ring shape having an outer diameter of 20 mm, an inner diameter of 17 mm, and an axial thickness of 7 mm. The direction connecting the center of the C-ring shape and the notch is aligned with the direction of extrusion during sample preparation. A stress of 330 MPa is applied to the test piece in a direction in which the C-ring shape is contracted in a direction perpendicular to the extrusion direction. In this loaded state, in a temperature atmosphere of 25 ° C., alternate immersion in which the test piece is alternately immersed in a 3.5% NaCl aqueous solution for 10 minutes and dried for 50 minutes is performed for 720 hours. The test result is determined by the presence or absence of cracks. “No crack” means “good” (◯), and “crack” means “bad” (×).
試料17は、Zn含有量が高すぎるため、耐応力腐食割れ性が劣り不合格と判定された。
試料18は、Mg含有量が低すぎるため、強度向上効果が充分に得られず、耐力が不合格と判定された。 Since the sample 16 had too low Zn content, the strength improvement effect was not fully acquired and it was determined that the proof stress was disqualified.
Since the sample 17 had too high Zn content, it was determined that the stress corrosion cracking resistance was inferior and was rejected.
Since the sample 18 had too low Mg content, the strength improvement effect was not fully obtained and it was determined that the proof stress was unacceptable.
試料20は、Zn/Mg比が低すぎるため、強度が劣り不合格と判定された。
試料21は、Zn/Mg比が高すぎるため応力腐食割れ性が低下し不合格と判定された。 Since the sample 19 had too high Mg content, it cracked partially at the time of extrusion, and also the resistance to stress corrosion cracking was inferior, and it was determined to be unacceptable.
Since the sample 20 had a Zn / Mg ratio that was too low, the strength was inferior and it was determined to be unacceptable.
Sample 21 was judged to be rejected because the stress corrosion cracking property was lowered because the Zn / Mg ratio was too high.
試料23は、Cu含有量が高すぎるため、表面の色調が黄色を帯び不合格と判定された。
試料24は、Fe含有量が高すぎるため、繊維状組織が形成された結果、表面に筋状模様が視認され不合格と判定された。 Since the sample 22 had too low Cu content, it was determined that the stress corrosion cracking resistance was inferior and it was rejected.
Since the sample 23 had too high Cu content, the surface color tone was yellowish and it was determined to be unacceptable.
In Sample 24, since the Fe content was too high, a fibrous structure was formed. As a result, a streak pattern was visually recognized on the surface, and the sample 24 was determined to be unacceptable.
試料26は、Mn含有量が高すぎるため、繊維状組織が形成された結果、表面に筋状模様が視認され不合格と判定された。
試料27は、Cr含有量が高すぎるため、表面の色調が黄色を帯び不合格と判定された。 Since sample 25 had too high Si content, as a result of forming a fibrous structure, the streak pattern was visually recognized on the surface and it was determined to be unacceptable.
In sample 26, since the Mn content was too high, a fibrous structure was formed. As a result, a streak pattern was visually recognized on the surface, and the sample 26 was determined to be unacceptable.
Since sample 27 had too high Cr content, the color of the surface was yellowish and it was determined to be unacceptable.
試料29は、Ti含有量が低すぎるため、粗大な鋳塊組織に起因する筋状模様が現れ不合格と判定された。
試料30は、Ti含有量が高すぎるため、Alとの金属間化合物が形成された結果、表面に筋状および点状欠陥が視認され不合格と判定された。 Since the sample 28 has a Zr content that is too high, as a result of forming a fibrous structure, a streak pattern is visually recognized on the surface, and the sample 28 is determined to be unacceptable.
In Sample 29, since the Ti content was too low, a streak pattern resulting from a coarse ingot structure appeared and it was determined to be unacceptable.
Since the sample 30 had an excessively high Ti content, an intermetallic compound with Al was formed. As a result, streaky and point-like defects were visually recognized on the surface, and the sample 30 was determined to be rejected.
次に、上記高強度アルミニウム合金の製造方法に係る実施例について、表4~表6を用いて説明する。
本例では、表4に示す化学成分を含有するアルミニウム合金(材質No.A)を用い、表5及び表6に示すごとく製造条件を変化させて試料(No.A1~A29)を作製し、各試料の強度測定、金属組織観察を行った。更に、各試料に表面処理を行った後、表面品質評価を行った。
以下に、各試料の製造条件を詳説する。なお、各試料の強度測定方法、金属組織観察方法、表面処理方法及び表面品質評価方法は、上記実施例1と同一の方法により行った。 (Example 2)
Next, examples according to the method for producing the high-strength aluminum alloy will be described with reference to Tables 4 to 6.
In this example, aluminum alloys (material No. A) containing chemical components shown in Table 4 were used, and samples (No. A1 to A29) were prepared by changing the manufacturing conditions as shown in Tables 5 and 6. The strength of each sample was measured and the metal structure was observed. Furthermore, after surface-treating each sample, the surface quality was evaluated.
Below, the manufacturing conditions of each sample are explained in detail. The strength measurement method, metal structure observation method, surface treatment method, and surface quality evaluation method for each sample were performed in the same manner as in Example 1.
半連続鋳造により、表4に記載された化学成分を有する直径90mmの鋳塊を鋳造する。その後、表5及び表6に示す温度、時間または平均冷却速度の組み合わせを用いて、上記鋳塊に均質化処理、熱間押出加工、急冷処理、第1人工時効処理及び第2人工時効処理をこの順で施し、各試料を得る。なお、表5及び表6に記載の室温時効時間とは、急冷処理を行った後、展伸材が室温に達してから第1人工時効処理を行うまでの時間を意味する。 <Sample manufacturing conditions>
An ingot with a diameter of 90 mm having the chemical components described in Table 4 is cast by semi-continuous casting. Thereafter, using the combination of temperature, time or average cooling rate shown in Table 5 and Table 6, the ingot is subjected to homogenization treatment, hot extrusion processing, rapid cooling treatment, first artificial aging treatment and second artificial aging treatment. Apply in this order to obtain each sample. In addition, the room temperature aging time described in Tables 5 and 6 means the time from when the wrought material reaches room temperature until the first artificial aging treatment is performed after the rapid cooling treatment.
試料A19は、均質化処理における処理時間が短すぎたため、耐力が350MPaに満たず不合格と判定された。同時に、結晶粒が粗大となり、表面に斑状模様も視認された。 Since the heating temperature in the homogenization process was too low for sample A18, the yield strength was less than 350 MPa, and the sample A18 was determined to be rejected. At the same time, the crystal grains became coarse, and spotted patterns were also visually recognized on the surface.
Sample A19 was judged to be unacceptable because its proof stress was less than 350 MPa because the treatment time in the homogenization treatment was too short. At the same time, the crystal grains became coarse, and spotted patterns were also visually recognized on the surface.
試料A22は、第2人工時効処理における処理温度が低すぎたため、耐応力腐食割れ性が不十分となり不合格と判定された。 In Sample A21, the average cooling rate in the rapid cooling treatment was too low, so that the quenching effect was insufficient, and the proof stress was less than 350 MPa.
Since the processing temperature in the second artificial aging treatment of Sample A22 was too low, the stress corrosion cracking resistance was insufficient and the sample A22 was determined to be rejected.
試料A24は、第2人工時効処理における処理時間が短すぎたため、時効硬化が不十分となり耐力が350MPaに満たず、耐応力腐食割れ性も不十分となり不合格と判定された。 Sample A23 was over-aged because the treatment temperature in the second artificial aging treatment was too high, and the yield strength was less than 350 MPa, and the sample A23 was determined to be rejected.
Sample A24 was judged to be rejected because the treatment time in the second artificial aging treatment was too short, so that age hardening was insufficient and the proof stress was less than 350 MPa, and the stress corrosion cracking resistance was insufficient.
試料A26は、1段のみの人工時効処理を施したものであるが、その人工時効処理における処理温度が低すぎたため、耐応力腐食割れ性が不十分となり不合格と判定された。 Sample A25 was over-aged because the treatment time in the second artificial aging treatment was too long, and the yield strength was less than 350 MPa, which was determined to be unacceptable.
Sample A26 was subjected to only one stage of artificial aging treatment. However, since the treatment temperature in the artificial aging treatment was too low, the stress corrosion cracking resistance was insufficient, and the sample A26 was determined to be rejected.
試料A28は、第1人工時効処理における処理時間が短すぎたため、時効硬化が不十分となり耐力が350MPaに満たず不合格と判定された。
試A29は、第1人工時効処理における処理時間が長すぎたため、過時効となり耐力が350MPaに満たず不合格と判定した。 Sample A27 was subjected to only one stage of artificial aging treatment, but because the treatment temperature in the artificial aging treatment was too high, it was overaged and the yield strength was less than 350 MPa, and it was determined to be unacceptable.
In Sample A28, the treatment time in the first artificial aging treatment was too short, so that age hardening was insufficient and the proof stress was less than 350 MPa, and the sample A28 was determined to be unacceptable.
Test A29 was over-aged because the treatment time in the first artificial aging treatment was too long, and the yield strength was less than 350 MPa, and it was determined to be unacceptable.
Claims (5)
- 陽極酸化処理を施す高強度アルミニウム合金において、
質量%において、Zn:5.0%以上7.0%以下、Mg:2.2%超え3.0%以下、Cu:0.01%以上0.10%以下、Zr:0.10%以下、Cr:0.02%以下、Fe:0.30%以下、Si:0.30%以下、Mn:0.02%以下、Ti:0.001%以上0.05%以下を含有し、残部がAl及び不可避的不純物からなると共に、Zn/Mg比が1.7以上3.1以下である化学成分を有し、
耐力が350MPa以上であり、
金属組織が再結晶組織よりなることを特徴とする高強度アルミニウム合金。 In high-strength aluminum alloy that is anodized,
In mass%, Zn: 5.0% to 7.0%, Mg: 2.2% to 3.0%, Cu: 0.01% to 0.10%, Zr: 0.10% or less Cr: 0.02% or less, Fe: 0.30% or less, Si: 0.30% or less, Mn: 0.02% or less, Ti: 0.001% or more and 0.05% or less, and the balance Having a chemical component having a Zn / Mg ratio of 1.7 or more and 3.1 or less, and consisting of Al and inevitable impurities,
Yield strength is 350 MPa or more,
A high-strength aluminum alloy characterized in that the metal structure is a recrystallized structure. - 上記再結晶組織は、その結晶粒の平均粒径が500μm以下であり、熱間加工方向に平行な方向の結晶粒長さが、熱間加工方向に直角方向の結晶粒長さに対して0.5~4倍であることを特徴とする請求項1に記載の高強度アルミニウム合金。 The recrystallized structure has an average grain size of 500 μm or less, and the crystal grain length in the direction parallel to the hot working direction is 0 with respect to the crystal grain length perpendicular to the hot working direction. The high-strength aluminum alloy according to claim 1, wherein the strength is 5 to 4 times.
- 請求項1又は2に記載の高強度アルミニウム合金を製造する方法であって、
質量%において、Zn:5.0%以上7.0%以下、Mg:2.2%超え3.0%以下、Cu:0.01%以上0.10%以下、Zr:0.10%以下、Cr:0.02%以下、Fe:0.30%以下、Si:0.30%以下、Mn:0.02%以下、Ti:0.001%以上0.05%以下を含有し、残部がAl及び不可避的不純物からなると共に、Zn/Mg比が1.7以上3.1以下である化学成分を有する鋳塊を作製し、
上記鋳塊を540℃超え580℃以下の温度で1~24時間加熱する均質化処理を行い、
加工開始時における上記鋳塊の温度を440℃~560℃とした状態で該鋳塊に熱間加工を施して展伸材とし、
該展伸材の温度が400℃以上である間に冷却を開始した後、該展伸材の温度が400℃から150℃の範囲にある間の平均冷却速度を1℃/秒以上300℃/秒以下に制御して冷却する急冷処理を行い、
該急冷処理またはその後の冷却により該展伸材の温度を室温まで冷却し、
その後、該展伸材に対して人工時効処理を行うことを特徴とする高強度アルミニウム合金の製造方法。 A method for producing the high-strength aluminum alloy according to claim 1 or 2,
In mass%, Zn: 5.0% to 7.0%, Mg: 2.2% to 3.0%, Cu: 0.01% to 0.10%, Zr: 0.10% or less Cr: 0.02% or less, Fe: 0.30% or less, Si: 0.30% or less, Mn: 0.02% or less, Ti: 0.001% or more and 0.05% or less, and the balance Is made of Al and inevitable impurities, and ingot having a chemical component having a Zn / Mg ratio of 1.7 or more and 3.1 or less,
A homogenization treatment is performed in which the ingot is heated at a temperature of 540 ° C. to 580 ° C. for 1 to 24 hours,
In the state where the temperature of the ingot at the start of processing is 440 ° C. to 560 ° C., the ingot is hot-worked to obtain a wrought material
After starting the cooling while the temperature of the wrought material is 400 ° C. or higher, the average cooling rate while the temperature of the wrought material is in the range of 400 ° C. to 150 ° C. is 1 ° C./second to 300 ° C./second. Performs a rapid cooling process to cool by controlling to less than a second,
Cooling the temperature of the wrought material to room temperature by the rapid cooling treatment or subsequent cooling;
Then, the manufacturing method of the high strength aluminum alloy characterized by performing artificial aging treatment with respect to this wrought material. - 上記人工時効処理として、上記展伸材を80~120℃の温度で1~5時間加熱する第1人工時効処理を行い、その後、上記第1人工時効処理と連続して上記展伸材を145~200℃の温度で2~15時間加熱する第2人工時効処理を行うことを特徴とする請求項3に記載の高強度アルミニウム合金の製造方法。 As the artificial aging treatment, a first artificial aging treatment is performed in which the wrought material is heated at a temperature of 80 to 120 ° C. for 1 to 5 hours, and then the wrought material is 145 continuously with the first artificial aging treatment. The method for producing a high-strength aluminum alloy according to claim 3, wherein the second artificial aging treatment is performed by heating at a temperature of -200 ° C for 2 to 15 hours.
- 上記人工時効処理として、上記展伸材を145~170℃の温度で1~24時間加熱することを特徴とする請求項3に記載の高強度アルミニウム合金の製造方法。 The method for producing a high-strength aluminum alloy according to claim 3, wherein as the artificial aging treatment, the wrought material is heated at a temperature of 145 to 170 ° C for 1 to 24 hours.
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CN105671384A (en) * | 2016-01-07 | 2016-06-15 | 瑞声光电科技(常州)有限公司 | Aluminum alloy and preparation method thereof |
CN107735503A (en) * | 2015-07-08 | 2018-02-23 | 日本轻金属株式会社 | The excellent aluminum alloy extrusion material of exterior quality with anodic oxide coating and its manufacture method |
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