JP6010454B2 - Aluminum alloy wire - Google Patents

Description

  The present invention relates to aluminum alloys and aluminum alloy wires that are used as materials for various parts. In particular, it relates to an aluminum alloy having high strength and excellent luster after anodization.

  Conventionally, JIS standard 6000 series aluminum alloys have been used as materials for parts such as automobiles and bicycles. The 6000 series aluminum alloy is excellent in strength by precipitation strengthening by performing heat treatment such as solution treatment and aging treatment, but the above heat treatment is necessary and the productivity is poor. In addition, even when an anodic oxidation treatment (so-called alumite treatment) is applied to a 6000 series aluminum alloy, it is difficult to obtain a metallic luster, has a matte surface, and is inferior in glitter.

  On the other hand, the JIS standard 5000 series aluminum alloy is a non-heat treatment type alloy and does not require the above solution treatment and aging treatment. In addition, 5000 series aluminum alloy tends to have excellent metallic luster and excellent luster when subjected to anodizing treatment after bright finish (so-called bright alumite treatment). However, 5000 series aluminum alloys are inferior in strength to 6000 series aluminum alloys.

  On the other hand, Patent Document 1 discloses an aluminum alloy that is a non-heat-treatable alloy and has excellent strength by having a specific composition.

JP 2012-082469

  Development of an aluminum alloy having high strength and excellent luster after anodizing is desired.

  The 6000 series aluminum alloy has high strength as described above, but is inferior in appearance after anodizing (particularly after bright alumite treatment). A conventional 5000 series aluminum alloy is excellent in glitter after anodization (particularly after glitter alumite), but has insufficient strength.

  Although the aluminum alloy described in Patent Document 1 is excellent in strength, it does not mention a configuration excellent in glitter after anodizing treatment (particularly after glittering alumite treatment).

  Accordingly, one of the objects of the present invention is to provide an aluminum alloy that has high strength and excellent luster after anodizing. Another object of the present invention is to provide an aluminum alloy wire that is high in strength and excellent in glitter after anodizing.

  The inventors of the present invention are alloy types that do not require solution treatment and aging treatment, specifically, JIS standard 5000 series aluminum alloys (Al-Mg series alloys) containing Mg, which is a solid solution strengthening element, as a main additive element. ) Was studied for further strengthening and improving the appearance after anodizing (especially after bright alumite treatment).

  Increasing the Mg content is effective for improving the strength of the Al-Mg alloy. In addition, if the Al—Mg alloy contains excessive hydrogen, hydrogen accumulates at the grain boundaries of the alloy and the grain boundary strength may decrease, leading to a decrease in material strength. Furthermore, excessive hydrogen content tends to cause blowholes, which can lead to deterioration of the appearance accompanying the blowholes.

  Based on the above findings, an aluminum alloy with an adjusted Mg content and hydrogen content was prepared, and when this aluminum alloy was subjected to a bright anodized treatment, black spots were generated on the anodized film and the appearance was poor. Met. When the cause was examined by observing a cross section or the like, coarse crystal precipitates were present in the aluminum alloy base material under the portion where the black spots existed in the anodized film. Therefore, when coarse crystal precipitates were reduced, the black spots were reduced or substantially absent, and an anodized film excellent in glitter was obtained. The present invention is based on these findings.

The aluminum alloy of the present invention contains Mg in an amount of 4.5% by mass to 12.0% by mass, the balance is made of Al and inevitable impurities, and the hydrogen content is 10 ml / 100 g or less. The number of crystal precipitates having a diameter of 10 μm or more in the cross section of the aluminum alloy is 3 pieces / mm ² or less.

  The aluminum alloy of the present invention has high strength because it contains more Mg, which is a solid solution strengthening element, than a general 5000 series aluminum alloy. Moreover, the aluminum alloy of the present invention can stably produce a high-strength aluminum alloy even when the aluminum alloy having the specific composition described above is mass-produced because the hydrogen content is in a specific range.

  And since the aluminum alloy of the present invention has few coarse crystal precipitates, it can suppress appearance defects based on the coarse crystal precipitates even when the bright alumite treatment is performed, and has a metallic luster to make it bright. Excellent. Moreover, since the aluminum content of this invention can also suppress the appearance defect resulting from a blowhole because content of hydrogen is a specific range, it can have the outstanding external appearance.

  Furthermore, the aluminum alloy of this invention can suppress the fall of workability accompanying addition of Mg by containing Mg in a specific range, and is excellent in workability, such as wire drawing, rolling, and forging. Moreover, since the fall of grain boundary intensity | strength can also be suppressed because hydrogen content is a specific range, the aluminum alloy of this invention is excellent in workability. In addition, the aluminum alloy of the present invention can be manufactured without performing solution treatment and aging treatment. From these points, the aluminum alloy of the present invention is also excellent in productivity.

  As one form of this invention, the form whose content of Si is 0.1 mass% or less and content of Fe is 0.3 mass% or less among the said inevitable impurities is mentioned.

  The lower the Si content, the higher the glitter and the higher the strength. Further, the lower the Fe content, the more the generation of crystal precipitates containing Fe can be suppressed, and the presence of coarse crystal precipitates is difficult. Therefore, the above-described form is excellent in strength and excellent in glitter after anodizing treatment.

  As one form of this invention, the form whose tensile strength of the said aluminum alloy is 300 MPa or more is mentioned.

  The above form has a tensile strength equal to or higher than that of the 6000 series aluminum alloy and is high in strength.

  As one form of this invention, the form whose breaking elongation of the said aluminum alloy is 15% or more is mentioned.

  The above form is excellent in toughness, has a high elongation at break equivalent to or higher than that of a 6000 series aluminum alloy, and hardly breaks or cracks during processing. Therefore, the said form is high intensity | strength and is excellent also in workability.

  As one form of this invention, the form which contains 0.01 mass% or more and 0.3 mass% or less of Zr is mentioned further.

  The said form is more excellent in intensity | strength by containing Zr in a specific range.

  The aluminum alloy wire of the present invention is composed of the aluminum alloy of the present invention.

  The aluminum alloy wire of the present invention is composed of the aluminum alloy of the present invention that is high in strength and excellent in glitter after anodization, and thus has high strength and excellent in glitter after anodization. In addition, the aluminum alloy wire of the present invention is composed of the aluminum alloy of the present invention which is excellent in workability, so that various plastic working after casting, for example, hot working such as hot forging and hot rolling, In the cold working such as cold wire drawing, cracks and the like hardly occur and the productivity is excellent. Furthermore, since the aluminum alloy wire of the present invention itself is excellent in workability, plastic processing such as forging (secondary processing) can be performed well, and the material for plastic processing (material for secondary processing) Can be suitably used. By subjecting the secondary processed material subjected to forging or the like to a bright alumite treatment, an aluminum alloy member having a metallic luster and excellent in glitter is obtained.

  The aluminum alloy of the present invention and the aluminum alloy wire of the present invention have high strength and excellent glitter after anodizing treatment.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, content of an element shows a mass ratio.

[Aluminum alloy]
(composition)
One of the characteristics of the aluminum alloy of the present invention (hereinafter referred to as “Al alloy”) is an Al—Mg-based alloy whose main additive element is Mg. Mg is a solid solution element having a high strength improvement effect. By containing 4.5% or more of Mg, the effect of improving the strength can be obtained. The greater the Mg content, the higher the strength, and 5.5% or more, and more preferably 7% or more. In addition, by making the Mg content 12.0% or less, (1) the added Mg can be sufficiently dissolved, and the effect of solid solution strengthening can be obtained sufficiently. (2) Workability with increasing Mg (3) It is easy to suppress the formation of crystal precipitates, and as a result, it is possible to suppress degradation of glitter after anodizing treatment. When the Mg content is 10.0% or less, it is possible to further suppress a decrease in workability due to an increase in Mg, to improve the workability, and to improve the productivity.

  Zr can be contained as an additive element other than Mg. Zr segregates at the grain boundary of the Al alloy and contributes to the improvement of the grain boundary strength. Moreover, Zr is effective in refining crystal grains and contributes to improvement in strength and workability due to the fine structure. By making the content of Zr 0.01% or more, the above-mentioned effect can be obtained, and the above effect can be easily obtained as the Zr content increases. For example, the Zr content can be 0.1% or more, and further 0.15% or more. However, the above effect tends to saturate when the Zr content is about 0.3%. Further, when the Zr content is 0.3% or less, it is possible to suppress a decrease in workability due to the addition of Zr. Therefore, considering workability and the like, the content of Zr is preferably 0.25% or less.

  One of the features of the Al alloy of the present invention is that the content of hydrogen is small. Hydrogen is considered to be present at the grain boundaries of the Al alloy and reduce the grain boundary strength. As a result, the strength of the material and the workability may be reduced. In addition, hydrogen generates blow holes during casting, leading to deterioration of quality and appearance such as deterioration of surface properties accompanying blow holes and deterioration of appearance after anodization. Therefore, the hydrogen content is 10 ml or less, that is, 10 ml / 100 g or less in 100 g of the Al alloy. The content of hydrogen is preferably small, preferably 5 ml / 100 g or less, more preferably 2 ml / 100 g or less, and no lower limit is set. In particular, in a mass production system, it is expected that an Al alloy satisfying a certain level of characteristics (here, a particularly high-strength Al alloy) can be stably provided by controlling the hydrogen content within a specific range. It is considered that hydrogen is mainly mixed into the Al alloy from the atmosphere during melting or casting. Therefore, in order to reduce the content of hydrogen in the Al alloy, for example, degassing is performed on the molten metal immediately before casting. Examples of the degassing treatment include using an appropriate flux or using bubbling with an inert gas such as argon (Ar). By reducing the hydrogen at the molten metal stage, the reduced hydrogen state is substantially maintained in the subsequent manufacturing processes, and the cast material, wire drawing material, soft material, secondary material with a low hydrogen content are maintained. A processed material can be obtained.

  Additive elements other than Mg tend to reduce the metallic luster inherent in Al itself. That is, when a plurality of additive elements other than Mg are contained, particularly in a large amount, crystal precipitates are easily generated, and the growth of crystal precipitates causes a decrease in glitter after anodization. Therefore, in the Al alloy of the present invention, Mg and, as appropriate, Zr are added elements, and the balance is Al and inevitable impurities. Inevitable impurities include Si, Fe, Cu, Mn, Zn, Cr, Ti and the like.

  In particular, Si forms Mg-Si-based crystal precipitates, and when these crystal precipitates grow and become coarse, the brightness after anodizing treatment is reduced, and workability is reduced ( Coarse crystal precipitates may be the starting point of cracks). Further, when Si contains Zr, it is considered that the effect of improving the grain boundary strength due to the grain boundary segregation of Zr is reduced. Therefore, the Si content is preferably 0.1% or less. If the Si content is 0.1% or less, the brightness after anodization is excellent, but the material strength can be increased as the Si content is further reduced. Therefore, the Si content can be 0.05% or less, more preferably 0.01% or less, and there is no particular lower limit for the Si content.

  In particular, Fe forms an Al—Fe—Si based crystal precipitate, and when this crystal precipitate grows and becomes coarse, the brightness after anodizing treatment is lowered. Moreover, when this crystal precipitate is also coarse, workability and strength improvement effect are reduced. Therefore, the Fe content is preferably 0.3% or less, preferably 0.1% or less, and more preferably 0.05% or less, and there is no particular lower limit for the Fe content. The content of Si or Fe can be reduced, for example, by using pure aluminum with high purity as a raw material or by refining the raw material.

(Organization)
One feature of the Al alloy of the present invention is that the content of coarse crystal precipitates is small. Specifically, the number of crystal precipitates (coarse crystal precipitates) having a diameter of 10 μm or more in the cross section of the Al alloy is 3 or less per unit area (mm ² ), that is, 3 / mm ² or less. If the coarse crystal precipitates are present, after the bright alumite treatment, black spots are formed on the anodized film formed on the coarse crystal precipitates as described above. In this case, a uniform metallic luster is not obtained and the appearance is inferior in glitter. The more such coarse crystal precipitates are present, the more black spots appear and the appearance is further inferior in glitter. Therefore, in the present invention, a structure with few coarse crystal precipitates is proposed as an Al alloy excellent in glitter after anodizing. The smaller the number of crystal precipitates having a diameter of 10 μm or more, the better the glitter, which is preferably 2.5 / mm ² or less, more 2 / mm ² or less, particularly 1.5 / mm ² or less, and further 1.0 / mm ² or less. More preferred. Since there are few coarse crystal precipitates, it is possible to suppress the coarse crystal precipitates from causing cracks and breaks, so that improvement in strength and improvement in elongation can be expected. Examples of the composition of the crystal precipitate include Mg-Si, Al-Mg-Si, Al-Fe-Si, and Al-Zr. It is preferable that the maximum diameter of the coarse crystal precipitate is also small. In particular, when the maximum diameter of the crystal precipitates is 30 μm or less, and further 25 μm or less, it is easier to suppress the deterioration of the appearance due to the generation of the black spots, and it is also expected to improve the strength and the elongation. It is also preferable that the total area of crystal precipitates is small. In particular, when the total area ratio of crystal precipitates in the cross section is 2% or less, further 1% or less, and particularly 0.5% or less, it is expected that the above-described deterioration of the appearance due to the generation of black spots is more easily suppressed. A method for measuring the content of crystal precipitates, the maximum diameter, and the total area ratio will be described later.

(Characteristic)
The Al alloy of the present invention has high strength. In addition to being excellent in strength, it can also be excellent in toughness. For example, there is a form in which the tensile strength is 300 MPa or more, further 330 MPa or more, particularly 350 MPa or more, and further 380 MPa or more. Alternatively, a mode in which the elongation at break satisfies 15% or more, further 17% or more, particularly 20% or more can be mentioned. These mechanical characteristics can be changed mainly by the content of additive elements (Mg, Zr).

(Form)
Representative forms of the Al alloy of the present invention, when distinguished by the manufacturing process, were subjected to plastic processing (for example, extrusion, forging, press processing, etc.) other than cast material, wire drawing material, rolled material, wire drawing and rolling. Heat treatment such as homogenization treatment, softening treatment, etc. for plastic working materials (including secondary working materials that have been subjected to further plastic working using wire drawing materials as primary working materials), casting materials, wire drawing materials, rolled materials, and the above plastic working materials The heat processing material which gave is mentioned. On the other hand, when distinguished by shape, there are a wire (the aluminum alloy wire of the present invention), a plate (typically a rolled plate), and other various three-dimensional shapes. It can also be set as the form which provides the plastic processing part by which plastic processing, such as forging, was given to a part of wire and board | plate material. Typical examples of the wire include a round wire and a round bar having a circular cross section, and various other shapes such as a rectangular shape, a polygonal shape, and an elliptical shape. When the diameter of the round wire or round bar is about 10 mm to 30 mm, it can be easily used as a material for parts of automobiles and bicycles.

[Production method]
The Al alloy of the present invention is typically prepared by preparing raw materials → melting / casting → appropriate processing (plastic processing such as hot processing or cold processing) or appropriate heat treatment (homogenization processing or softening processing). Can be manufactured. The Al alloy wire of the present invention can be produced by raw material preparation → melting / casting → hot working (hot forging, hot rolling, etc.) → cold drawing, and heat treatment (homogenization treatment or softening as appropriate). Processing) step.

  As the raw material, pure aluminum, Mg, and optionally Zr are used. If pure aluminum of high purity such as 4N or 6N is used as the raw material pure aluminum, the content of inevitable impurities can be reduced as described above. The raw material is melted to prepare a molten metal, and the molten metal before casting (or immediately before) may be subjected to the above degassing treatment so that the hydrogen content is adjusted to a specific range. The molten metal with the adjusted hydrogen content is used for casting.

  For casting, typically, die casting (billet casting) using a fixed mold having a desired shape can be used. In billet casting, the cooling rate can be easily adjusted by appropriately selecting the material and shape of the mold and the cooling method, for example, rapid solidification can be performed. In addition, when continuous casting using a movable mold or a frame-shaped fixed mold is used, the molten metal is easily rapidly solidified, and generation of crystal precipitates and growth of crystal precipitates are easily suppressed by rapid solidification. A cast material having a fine crystal structure is obtained by rapid solidification. When a cast material having this fine structure is used as a raw material, an Al alloy having a fine crystal structure can be easily produced, and the strength and workability can be improved by the fine structure. In continuous casting, a long cast material can be easily manufactured. By using this cast material as a raw material, a long wire or plate can be manufactured. Using a continuous casting mill, etc., when performing continuous (hot) rolling from continuous casting, it is possible to easily perform hot rolling using the heat accumulated in the cast material, and energy efficiency is good. Long hot work materials can be manufactured efficiently. For continuous casting, for example, a belt-and-wheel method, a twin roll method, or the like can be used.

  And in this invention, in order to reduce a coarse crystal precipitate, the temperature of the raw material molten metal is made comparatively high, and the production | generation of the crystallization thing by the fluctuation | variation of hot water temperature is suppressed. Here, conventionally, in the production of an Al alloy, the temperature of the molten metal is about the melting point of Al (about 660 ° C.) or higher, specifically about 670 ° C. to 720 ° C. However, at such a temperature, it is difficult to avoid crystallization (particularly, Al—Zr crystallization) associated with fluctuations in hot water temperature. Therefore, in the present invention, the temperature of the molten metal used for casting is positively increased. Specifically, the temperature of the molten metal is set to 730 ° C. or higher. By increasing the temperature of the molten metal to 730 ° C. or higher, crystallization associated with fluctuations in the molten metal temperature can be suppressed, and as a result, the formation of coarse crystal precipitates can be reduced. The temperature of the molten metal is preferably 730 ° C. or higher, more preferably 780 ° C. or higher, and preferably 850 ° C. or lower from the viewpoint of energy. In order to reduce crystal precipitates more effectively, it is preferable to increase the cooling rate in the casting process. A specific cooling rate is 5 ° C./sec or more. The cooling rate can be adjusted by the material of the mold, the shape of the mold, the cooling method, and the like. For example, the cooling rate can be increased by using a mold made of a material having excellent thermal conductivity, using a thin mold, or performing appropriate forced cooling. In continuous casting, the cooling rate can also be adjusted by the casting rate. The material and shape of the mold, the cooling method, the casting conditions, etc. may be selected so as to achieve a desired cooling rate.

  The cast structure can be reduced or eliminated by subjecting the cast material to hot working such as hot forging and hot rolling, or continuous casting and rolling, eliminating defects such as intergranular cracking in the cast structure. be able to.

  By subjecting the hot-worked material to (cold) wire drawing, the Al alloy wire (wire-drawing material) of the present invention can be obtained. The degree of wire drawing can be appropriately selected according to a desired wire diameter. An Al alloy sheet (rolled material) is obtained by subjecting the hot-worked material to (cold) rolling. The rolling reduction can be appropriately selected according to the desired thickness.

  The wire drawing material, rolled material, the above-described cast material, and hot-worked material can be used as they are, but heat treatment can be further performed. For example, for the purpose of suppressing harmful segregation and improving workability, the cast material is subjected to homogenization heat treatment, and the wire drawing material is subjected to softening for the purpose of ensuring sufficient elongation and workability. You can.

  The conditions for the homogenization treatment include a heating temperature of 400 ° C. to 550 ° C. and a heating time of 1 hour to 96 hours. As the softening treatment, both continuous treatment and batch treatment can be used, and continuous treatment is practical for long materials. The batch treatment conditions are such that the heating temperature of the heating target is 250 ° C. or higher, preferably 300 ° C. or higher and 500 ° C. or lower, and the heating time is 0.5 hours or longer and 6 hours or shorter. Continuous processing is a parameter that contributes to heating according to the processing method to achieve the desired characteristics (furnace temperature (furnace type), current value (energization type), conveyance speed such as wire speed, wire diameter and thickness, etc. ) Should be adjusted.

[Test example]
Al alloys with various compositions were prepared, and the structure, mechanical properties, and appearance after bright alumite of the obtained Al alloys were examined.

  Here, an Al alloy wire and an Al alloy plate were produced. The Al alloy wire was prepared in the order of raw material preparation → melting → degassing treatment → casting → homogenization treatment → hot forging → cold drawing → softening treatment. The Al alloy sheet was prepared in the order of raw material preparation → melting → degassing treatment → casting → homogenization treatment → hot rolling → cold rolling → softening treatment.

  In any sample, commercially available pure aluminum (99 mass% or more Al) is prepared and melted as a base material, and Mg and Zr are contained in the obtained molten metal (molten aluminum) as shown in Table 1. To prepare a molten Al alloy. In Table 1, “-” indicates that no element was added. A flux was added to the Al alloy molten metal whose components were adjusted, and degassing treatment was performed to adjust the hydrogen content.

  In each sample, a cast material was produced by die casting (billet casting) by batch processing. In samples No. 1 to No. 3, the temperature of the molten Al alloy subjected to the degassing process is adjusted to 800 ° C. (≧ 730 ° C.) to produce an ingot having a diameter of 30 mm. In samples No. 1 to No. 3, the cooling rate from the temperature of the molten Al alloy to room temperature (here, about 20 ° C.) is 5 ° C./sec. On the other hand, in sample No. 100, the temperature of the molten Al alloy subjected to the degassing treatment is adjusted to 720 ° C. (<730 ° C.) to produce an ingot having a diameter of 30 mm. In sample No. 100, the cooling rate from the temperature of the molten Al alloy to room temperature is 1 ° C./sec (<5 ° C./sec). Here, the cooling rate of sample No. 1 to No. 3 and the cooling rate of sample No. 100 were made different by using molds having different thicknesses.

  Using each of the produced ingots, an Al alloy plate was produced, and the structure observation and appearance were examined. Here, each ingot is cut, a plate having a width of 16 mm and a thickness of 8 mm is cut out, and the cut ingot (plate) is subjected to a homogenization treatment of 440 ° C. × 16 hours, followed by hot rolling. Then, a hot-rolled material having a thickness of 4 mm is produced. Samples No. 1 to No. 3 could be rolled well without substantial cracking on the surface during hot rolling. The obtained hot-rolled material is cold-rolled to produce a plate material (rolled plate) having a thickness of 2 mm for each sample. The obtained plate material having a thickness of 2 mm is softened (batch treatment, 400 ° C. × 1 hour) to produce a soft material.

The obtained soft material (aluminum alloy plate) was observed for the structure as follows. Take a cross-section (cross-sectional or vertical cross-section) cut in parallel to the thickness direction of the produced aluminum alloy plate, observe the cross-section with a scanning electron microscope (SEM), crystals existing in the field of view in the observed image The area of each crystal precipitate is obtained by extracting the precipitate, and the diameter of the circle corresponding to the area (equivalent area circle) of each crystal precipitate is defined as the diameter of the crystal precipitate. Here, the number of cuts was 3, the number of fields per cross section was 5, and the total number of crystal precipitates with a diameter of 10 μm or more was divided by the total area of the total 15 fields for a total of 15 fields. The value (pieces / mm ² ) was determined. This value is the content of crystal precipitates of 10 μm or more, and this content (pieces / mm ² ) is shown in Table 2. Further, the total area ratio of the crystal precipitates was determined. Here, the total area is obtained by extracting all the crystal precipitates present in the total 15 fields of view described above, and the value obtained by dividing the total area of the crystal precipitates by the total area of the total 15 fields (× 100) Asked. This value is taken as the total area ratio, and the total area ratio (%) is shown in Table 2.

  The cross-sectional observation described above may use an optical microscope. The diameter may be calculated using a commercially available image processing apparatus or image processing software, and in this case, it can be easily calculated. Furthermore, the cross section may be cut so as to be orthogonal to the thickness direction, that is, cut in parallel to the front and back surfaces of the plate. From cross-sectional observation, it was confirmed that the base material of any sample was constituted by a recrystallized structure. In addition, the average crystal grain size of this structure was measured. The average crystal grain size was determined as follows. Using the SEM observation image of the cross section described above, the area of each crystal grain in the cross section is obtained, and the diameter of the area equivalent circle (equivalent area circle) of each crystal grain is defined as the diameter of the crystal grain. Then, 10 or more crystal grains were selected from each of the 15 total fields of view described above, and the average of the diameters of the 150 or more total crystal grains was defined as the average crystal grain size. Table 2 shows the average crystal grain size (μm).

The obtained soft material (aluminum alloy plate) was subjected to a bright finish treatment, followed by an anodizing treatment, that is, a bright alumite treatment, and the quality of the appearance after this treatment was examined. The results are shown in Table 2. Here, the quality of the appearance was determined by microscopic observation using an optical microscope. In the region of 1.0 mm × 1.0 mm, to find the total area of the black spots, the case of the total area is 1000 .mu.m ² or less ○, was evaluated as × in the case of 1000 .mu.m ² greater. The total area of the black spots is easily obtained by performing binarization processing or the like on the microscope observation image to extract the black spots and summing the areas of the extracted black spots. Furthermore, the glossiness of the treatment material obtained after the bright alumite treatment was measured. The results are also shown in Table 2. Glossiness is measured according to JIS Z 8741 (Specular Glossiness-Measurement Method, 1997, “Specular Glossiness Measurement Method” Method 3). Here, a general-purpose glossiness meter was used, and the glossiness (%) of each sample was measured when the incident angle and the light receiving angle were 60 degrees and the glossiness with a silver mirror was 100%. In sample No. 100, since black spots that can be visually confirmed were generated, the glossiness was not measured.

  Using each ingot produced, an Al alloy wire was produced and the mechanical properties were examined. Here, the surface of each ingot is cut to a diameter of φ22 mm, and after this homogenized treatment of 440 ° C. × 16 hours is applied to the cut ingot (round bar), hot forging is applied to obtain a diameter of φ13 mm. A forging material is produced. Samples No. 1 to No. 3 were all capable of being forged satisfactorily without substantially cracking the surface during hot forging. The obtained forging material is subjected to cold drawing to produce a wire material having a wire diameter of φ6.5 mm for each sample. The obtained wire having a diameter of φ6.5 mm is subjected to a softening treatment (batch treatment, 400 ° C. × 1 hour) to produce a soft material. The obtained soft material (aluminum alloy wire) was measured for tensile strength (MPa) and elongation at break (%). The results are shown in Table 2. Tensile strength and elongation at break (elongation) were measured at room temperature (approximately 20 ° C. to 25 ° C.) using a general-purpose tensile tester in accordance with JIS Z 2241 (Metal Material Tensile Test Method, 1998).

As shown in Tables 1 and 2, Samples No. 1 to No. 3 in which the contents of Mg and hydrogen are in a specific range, and the number of crystal precipitates having a diameter of 10 μm or more are 3 pieces / mm ² or less, It can be seen that, while containing a large amount of Mg as compared with a general 5000 series aluminum alloy, it has a high glossiness after the bright alumite treatment. In addition, it can be seen that Samples No. 1 to No. 3 are substantially free of black spots on the anodized film or very small (total area ratio is small), and have an excellent appearance after the bright alumite treatment. In other words, it can be said that Samples No. 1 to No. 3 have excellent glittering properties after the glittering alumite treatment. On the other hand, for sample No. 100 with a large total area ratio of black spots, when a cross-section cut in parallel with the thickness direction with an anodized film was observed, it was under the part where black spots were present in the anodized film. As a result, coarse crystal precipitates having a diameter of 10 μm or more (here, the maximum diameter was 34 μm) were confirmed. Sample No. 100 having a large total area ratio of black spots has a large amount of crystal precipitates (here, the total area ratio exceeds 2%). On the other hand, sample No.1 to No.3, which have very few coarse crystal precipitates and excellent appearance after anodizing treatment, all have a small maximum crystal precipitate size (22 μm or less in this case). The objects themselves are very small (here, the total area ratio is 0.15% or less). From these facts, samples No. 1 to No. 3 were able to have excellent luster as a whole because the above-mentioned coarse crystal precipitates were few or substantially absent. Conceivable. Samples No. 1 to No. 3 also have very few crystal precipitates themselves, and it is considered that black spots that impair the appearance after the treatment are less likely to occur during the anodizing treatment.

  Furthermore, it can be seen that Samples No. 1 to No. 3 containing Mg in a specific range have high strength. Here, all of samples No. 1 to No. 3 have a tensile strength of 300 MPa or more, higher strength than a general 5000 series aluminum alloy, and have the same strength as a general 6000 series aluminum alloy. . In particular, it can be seen that the strength can be further improved by containing Zr. In addition, it can also be seen that all of Samples No. 1 to No. 3 have high elongation at break (elongation) and high strength and high toughness. Furthermore, all of samples No. 1 to No. 3 have a fine structure (here, the average crystal grain size is 25 μm or less), and the fact that they are composed of such a fine structure also contributes to high strength and high toughness. it seems to do.

  In addition to such excellent luster, a high-strength aluminum alloy adjusts the raw material composition and controls the production conditions (in this case, the temperature of the molten metal is increased or the cooling rate is increased). It can be seen that production can be achieved by suppressing the formation and growth of crystal precipitates.

  In addition, it is considered that Samples No. 1 to No. 3 could have a good appearance because the blowholes could be suppressed by reducing the hydrogen content. Samples No. 1 to No. 3 are excellent in workability by containing Mg in a specific range, and can be said to have workability equivalent to or higher than that of a general 5000 series aluminum alloy. Furthermore, it is considered that by performing degassing treatment to reduce the hydrogen content, cracking during the production was suppressed, and the workability was improved. From these points, samples No. 1 to No. 3 are expected to be excellent in productivity.

  The composition of the obtained soft material was examined by ICP emission spectroscopy (ICP-AES), and the Mg and Zr contents were substantially equal to the values shown in Table 1. It was confirmed. Moreover, the softwood contained Fe and Si as inevitable impurities. Table 1 shows the contents of Fe and Si. As shown in Table 1, all of sample Nos. 1 to 3 have coarse crystal precipitates because the Fe content is 0.3% by mass or less and the Si content is 0.1% by mass. It is thought that it was difficult. On the other hand, although sample No. 100 had a low content of Fe and Si, crystal precipitates were generated because the manufacturing conditions were not appropriate (here, the temperature of the molten metal was low and the cooling rate was low). It is considered that coarse crystal precipitates were generated in addition to the ease.

  Furthermore, when the hydrogen content of the obtained cast material was examined using an inert gas melting method, the content shown in Table 1 was obtained. A commercially available apparatus can be used to measure the hydrogen content. The mass of the hydrogen can be measured, and the volume can be converted at room temperature and 1 atm (about 0.1 MPa). The hydrogen content of the obtained soft material substantially maintains the hydrogen content of the cast material.

  In addition, here, the structure and the appearance after bright alumite were confirmed for the plate material, and the mechanical characteristics were confirmed for the wire material. It has also been confirmed that the plate material is superior in strength to a general 5000 series alloy plate material as well as the wire material.

  As described above, it can be seen that the Al—Mg-based alloy having a specific composition and structure is excellent in appearance after anodizing treatment while having high strength without performing solution treatment and aging treatment. Therefore, it is expected that this Al—Mg alloy can be suitably used as a material for forming an aluminum alloy member having a good appearance and high commercial value.

  In addition, this invention is not limited to embodiment mentioned above, It is possible to change suitably, without deviating from the summary of this invention. For example, the contents of Mg, Zr, and hydrogen can be changed within a specific range, or the temperature of the molten metal can be changed. Moreover, it can replace with billet casting and can perform continuous casting rolling. In addition, the size (wire diameter) and cross-sectional shape of the aluminum alloy wire, the thickness of the aluminum alloy plate, and the like can be appropriately changed.

  The aluminum alloy of the present invention and the aluminum alloy wire of the present invention are suitably used as materials for parts of transportation equipment such as automobiles and bicycles, and other materials for parts in various fields where high strength and light weight are desired. be able to.

Claims (5)

Contains 7 % by mass or more and 12.0% by mass or less of Mg, with the balance consisting of Al and inevitable impurities,
Among the inevitable impurities, the Si content is 0.05% by mass or less, and the Fe content is 0.3% by mass or less,
The hydrogen content is 2 ml / 100 g or less,
Intermetallic compounds above diameter 10μm in cross section Ri Der three / mm ² or less,
An aluminum alloy wire having a total area ratio of crystal precipitates in a cross section of 0.15% or less . 2. The aluminum alloy wire according to claim 1 , wherein the tensile strength is 300 MPa or more. 3. The aluminum alloy wire according to claim 1 , wherein the elongation at break is 15% or more. 4. The aluminum alloy wire according to claim 1, further comprising 0.01% by mass to 0.3% by mass of Zr. 5. The aluminum alloy wire according to claim 1, wherein the average crystal grain size is 25 μm or less .