EXTRUDED MATERIAL OF Al-Mg-Si BASED ALUMINUM ALLOY, AND METHOD FOR PRODUCING THE SAME

Abstract

To provide a technique capable of reducing surface defects of an extruded material, independently of the cooling rate during homogenization of a cast material.SOLUTION: An extruded material of an Al-Mg-Si based aluminum alloy contains: 0.20 mass% to 0.90 mass% of Si; 0.22 mass% to 0.50 mass% of Fe; 0.01 mass% to 0.40 mass% of Cu; 0.01 mass% to 0.50 mass% of Mn; 0.40 mass% to 1.20 mass% of Mg; 0.01 mass% to 0.15 mass% of Cr; 0.01 mass% to 0.25 mass% of Zn; and 0.001 mass% to 0.15 mass% of Ti. The rest of the aluminum alloy includes unavoidable impurities and aluminum.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to an extruded material of an Al-Mg-Si-based aluminum alloy and a method for producing the same. [Background technology]

[0002] Extrusions of Al-Mg-Si aluminum alloys are used in many fields, such as automobiles, railways, civil engineering, construction, and industrial equipment. The manufacturing method of extrusions includes a process of homogenizing cast materials and a process of extruding cast materials. Surface quality is important for extrusions. Surface quality is evaluated, for example, by the number of surface defects per unit area.

[0003] A typical example of a surface defect is a pick-up. A pick-up is a long, streak-like concave defect in the extrusion direction. Patent Document 1 discloses controlling the temperature of a homogenization treatment to suppress the occurrence of pick-up. In the homogenization treatment of Patent Document 1, the cast material is heated at a high temperature of 550°C or higher for 2 hours or more, and then the cast material is water-cooled. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-31582 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 does not clearly state the cooling rate at which the cast material should be water-cooled. Cast materials for extrusion are generally cylindrical. If the cast material is too thick, when the cast material is quenched from the outside, the inside of the cast material cannot be cooled sufficiently, and the desired metal structure cannot be obtained. Also, if the cast material is too thin, when the cast material is quenched from the outside, bending deformation of the cast material occurs, and the amount of processing such as cutting before extrusion increases.

[0006] One aspect of the present disclosure provides a technique that can reduce surface defects in an extruded material, regardless of the cooling rate in the homogenization treatment of the cast material. [Means for solving the problem]

[0007] An extruded material of an Al-Mg-Si-based aluminum alloy according to an embodiment of the present disclosure contains 0.20 mass% to 0.90 mass% Si, 0.22 mass% to 0.50 mass% Fe, 0.01 mass% to 0.40 mass% Cu, 0.01 mass% to 0.50 mass% Mn, 0.40 mass% to 1.20 mass% Mg, 0.01 mass% to 0.15 mass% Cr, 0.01 mass% to 0.25 mass% Zn, and 0.001 mass% to 0.15 mass% Ti, with the balance being inevitable impurities and aluminum. Effect of the Invention

[0008] According to one aspect of the present disclosure, surface defects of an extruded material can be reduced regardless of the cooling rate in the homogenization treatment of the cast material. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a flow chart showing an example of a method for producing an aluminum alloy extrusion material. [Diagram 2] FIG. 2 is a flow chart showing a modified example of the method for producing an aluminum alloy extrusion material. [Diagram 3] FIG. 3 is a photograph showing an example of a pickup observed on the surface of an aluminum alloy extrusion. [Figure 4] FIG. 4 is an electron microscope photograph showing an example of a metal structure including a β-AlFeSi phase after casting and before homogenization treatment. [Diagram 5] FIG. 5 is an electron microscope photograph showing an example of a metal structure including an α-AlFeSi phase and a β-Mg2Si phase after the homogenization treatment and before the extrusion process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments for carrying out the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding configurations are given the same reference numerals, and the description may be omitted. In the specification, "~" indicating a numerical range means that the numerical values ​​before and after it are included as the lower limit and upper limit. The numerical range includes the range rounded off. In the following description, the combination of the upper limit and lower limit of the preferred range is not particularly limited.

[0011] [Manufacturing method for aluminum alloy extrusions] An example of a method for producing an aluminum alloy extrusion material will be described with reference to FIG. 1. The method for producing the extrusion material includes, for example, steps S101, S102, S103, S104A, S104B, and S105. Step S101 is a casting step. Step S102 is a homogenization treatment step. Step S103 is an extrusion processing step. Step S104A is a solution treatment step. Step S104B is a quenching step. Step S105 is an aging treatment step. Note that the method for producing the extrusion material does not have to include all steps S101 to S105, and may include at least steps S102 to S103. Each step will be described below.

[0012] The casting process includes melting raw materials of an aluminum alloy to obtain a molten metal, and pouring the molten metal into a mold to obtain a casting material. The raw materials are mixed so that the aluminum alloy has a desired composition. The raw materials may include recycled materials that have been recycled. The molten metal may be filtered with a filter before being poured into the mold. The filtration method may be a gas bubbling filtration (GBF), a rigid media filter (RMF), a deep bed filter (DBF), a ceramic foam filter (CFF), a glass sock, or the like. A plurality of filtration methods may be combined. The combination of filtration methods is arbitrary. The casting method may be float casting, hot top casting, or the like. Casting materials for extrusion processing are generally cylindrical. A cylindrical casting material may be called a billet. The billet may be cut to a desired length.

[0013] The homogenization process includes performing homogenization of the cast material after the casting process. The homogenization process includes heating the cast material at a desired temperature of 550°C or more for 3 hours or more, as will be described later in detail. The homogenization process reduces segregation that occurs during solidification of the casting. The homogenization process may also precipitate a solid solution element that is dissolved as a supersaturated solid solution during solidification of the casting. The heating temperature is preferably 600°C or less, and more preferably 570°C or less, in order to suppress melting of the intermetallic compound. The heating time is preferably 24 hours or less, more preferably 20 hours or less, and even more preferably 18 hours or less, in order to suppress coarsening of the particles of the intermetallic compound. The homogenization process, which will be described in detail later, may include, in this order, cooling the cast material from the desired temperature to 200°C at a cooling rate of 0.036°C / sec to 0.075°C / sec, and cooling the cast material from 200°C to room temperature at a cooling rate of 0.0028°C / sec to 0.022°C / sec. Here, the cooling rate is an average value.

[0014] The extrusion process includes extruding the cast material after the homogenization process to obtain an extruded material. The extrusion process may be, for example, direct extrusion or indirect extrusion. Direct extrusion is a method in which a heated billet is placed in a container and the billet is extruded with a stem from a die fixed relative to the container. Indirect extrusion is a method in which a heated billet is placed in a container and the container and billet are moved together to extrude the billet from the die. Indirect extrusion is different from direct extrusion in that the container and the die move relative to each other.

[0015] The solution treatment process involves heating the extrusion material at a temperature below the solidus temperature of the aluminum alloy for a period of time to obtain a uniform solid solution. The solution treatment process is immediately followed by a quenching process. Quenching can be, for example, water cooling or air cooling. Water cooling can involve placing the extrusion material in water stored in a water tank or spraying the extrusion material with water or mist. Air cooling can be fan cooling or natural cooling. Fan cooling can involve blowing air over the extrusion material with a fan. Natural cooling can involve leaving the extrusion material in the atmosphere. Quenching can result in a supersaturated solid solution.

[0016] As shown in Fig. 2, a die quenching step may be performed, which serves as both a solution treatment step and a quenching step. In Fig. 2, step S104 is the die quenching step. The die quenching step can be adopted when the extrusion process is a direct extrusion process. The die quenching step includes performing a solution treatment and quenching at the outlet of a die for extrusion process. When the die quenching step is not performed, fan cooling or natural cooling may be performed after the extrusion process step and before the solution treatment step.

[0017] The aging treatment step includes improving mechanical properties by precipitating precipitates from a supersaturated solid solution after the quenching step. The aging treatment includes at least one of natural aging treatment and artificial aging treatment. The natural aging treatment is performed at room temperature. The artificial aging treatment is performed at a high temperature. The heating temperature of the artificial aging treatment is preferably 140°C or higher, more preferably 160°C or higher, in order to promote the precipitation of precipitates. The heating temperature of the artificial aging treatment is preferably 240°C or lower, more preferably 220°C or lower, in order to suppress excessive growth of precipitates.

[0018] [Extruded aluminum alloy] Next, the composition of the aluminum alloy of the extruded material will be described. The aluminum alloy is an Al-Mg-Si system. The aluminum alloy contains 0.20 mass% to 0.90 mass% Si, 0.22 mass% to 0.50 mass% Fe, 0.01 mass% to 0.40 mass% Cu, 0.01 mass% to 0.50 mass% Mn, 0.40 mass% to 1.20 mass% Mg, 0.01 mass% to 0.15 mass% Cr, 0.01 mass% to 0.25 mass% Zn, and 0.001 mass% to 0.15 mass% Ti. The balance of the aluminum alloy is composed of inevitable impurities and aluminum. Each component will be described below.

[0019] Si forms fine precipitates by aging treatment, improving the strength of the aluminum alloy. The precipitates include at least one of β'' phase (Mg2Si) and Q phase (Al-Cu-Mg-Si). Si dissolves in the aluminum matrix by solution treatment, and precipitates by aging treatment after quenching. From the viewpoint of improving strength, the Si content is 0.20 mass% or more, and preferably 0.30 mass% or more. Also, from the viewpoint of suppressing precipitation of a single Si phase, the Si content is 0.90 mass% or less, and preferably 0.50 mass% or less. The single Si phase is hard and brittle, and may cause pick-up.

[0020] Fe mainly produces Al-Fe-Si intermetallic compounds. The main phases of Al-Fe-Si intermetallic compounds are the α phase, α' phase, and β phase. The α phase, or α-AlFeSi, is 17.5 Fe4Si 1.5 The α´ phase, i.e., α´-AlFeSi, is 85 Fe 23 S 11 The β-phase, i.e., β-AlFeSi, is Al9Fe2Si2. The element ratio of each phase may deviate from the stoichiometric ratio. Among the α-AlFeSi phase, the α´-AlFeSi phase, and the β-AlFeSi phase, the β-AlFeSi phase reduces the strength of the aluminum alloy if it exists in excess. The β-AlFeSi phase is also one of the causes of pickup.

[0021] The Fe content is 0.22% by mass or more, preferably 0.25% by mass or more, in order to reduce the ratio of the β-AlFeSi phase after homogenization and before extrusion, and 0.50% by mass or less, preferably 0.40% by mass or less, in order to suppress excessive consumption of Si in the formation of Al-Fe-Si intermetallic compounds and to improve strength by aging.

[0022] Like Si, Cu generates fine precipitates by aging treatment and improves the strength of the aluminum alloy. The precipitates include at least one of Q phase (Al-Cu-Mg-Si) and θ' phase (CuAl2). From the viewpoint of improving strength, the Cu content is 0.01 mass% or more, and preferably 0.02 mass% or more. Also, from the viewpoint of corrosion resistance, the Cu content is 0.40 mass% or less, and preferably 0.30 mass% or less.

[0023] Mn mainly produces at least one of Al-Mn-Si intermetallic compounds and Al-Mn-Cr-Fe-Si intermetallic compounds as crystallized or precipitated substances. These intermetallic compounds improve the strength of the aluminum alloy. From the viewpoint of improving the strength, the Mn content is 0.01 mass% or more, and preferably 0.02 mass% or more. Moreover, from the viewpoint of reducing the deformation resistance during extrusion processing, the Mn content is 0.50 mass% or less, and preferably 0.35 mass% or less.

[0024] Like Si, Mg generates fine precipitates by aging treatment and improves the strength of the aluminum alloy. The precipitates include at least one of β'' phase (Mg2Si) and Q phase (Al-Cu-Mg-Si). From the viewpoint of improving strength, the Mg content is 0.40 mass% or more, and preferably 0.45 mass% or more. Also, from the viewpoint of reducing deformation resistance during extrusion processing, the Mg content is 1.20 mass% or less, and preferably 0.90 mass% or less.

[0025] Cr mainly produces at least one of Al-Cr-Si intermetallic compounds and Al-Mn-Cr-Fe-Si intermetallic compounds as crystallized or precipitated substances. These intermetallic compounds improve the strength of the aluminum alloy. From the viewpoint of improving the strength, the Cr content is 0.01 mass% or more, more preferably 0.02 mass% or more. Moreover, from the viewpoint of reducing the deformation resistance during extrusion processing, the Cr content is 0.15 mass% or less, preferably 0.10 mass% or less.

[0026] Zn mainly forms intermetallic compounds with Mg, improving the strength of the aluminum alloy at room temperature. From the viewpoint of improving the strength, the Zn content is 0.01 mass% or more, more preferably 0.02 mass% or more. Also, from the viewpoint of improving the corrosion resistance, the Zn content is 0.25 mass% or less, preferably 0.15 mass% or less.

[0027] Ti becomes the nucleus of the aluminum parent phase during the solidification process during casting, and refines the crystal grains. The Ti content is 0.001% by mass or more, preferably 0.01% by mass or more, from the viewpoint of refinement of the crystal grains. The Ti content is 0.15% by mass or less, preferably 0.10% by mass or less, from the viewpoint of suppressing the generation of coarse crystallized products and suppressing an increase in the surface roughness of the aluminum alloy.

[0028] The aluminum alloy is composed of inevitable impurities and aluminum, excluding Si, Fe, Cu, Mn, Mg, Cr, Zn, and Ti. The inevitable impurities are not particularly limited, but examples thereof include Zr, Li, Na, P, Ca, Sc, V, Co, Ni, Sr, W, Mo, Ta, Hf, and Nb. The content of each element that is an inevitable impurity is preferably 0.05 mass% or less. The total content of the elements that are inevitable impurities is preferably 0.15 mass% or less. The balance excluding inevitable impurities is preferably composed of only aluminum.

[0029] The aluminum alloy preferably has a ratio (Fe content / Si content) of the Fe content (mass%) to the Si content (mass%) greater than 0.44. The Fe content is sufficiently greater than the Si content, so that the ratio of the β-AlFeSi phase after the homogenization treatment and before the extrusion process can be reduced. In addition, the Fe content is sufficiently greater than the Si content, so that the precipitation of the Si single phase can be suppressed. As described above, the Si single phase is hard and brittle, and can cause pick-up. The ratio (Fe content / Si content) is preferably 0.46 or more, and more preferably 0.48 or more.

[0030] The aluminum alloy preferably has a ratio (Fe content / Si content) of the Fe content (mass%) to the Si content (mass%) of less than 1.20. By limiting the Fe content, the generation of coarse Fe-based intermetallic compounds can be restricted, and the surface roughness of the aluminum alloy can be reduced. The ratio (Fe content / Si content) is preferably 1.10 or less.

[0031] [summary] The aluminum alloy of this embodiment has an Fe content of 0.22 mass% or more. The Fe content is sufficiently high, and the ratio of the β-AlFeSi phase after homogenization can be reduced, thereby reducing the pick-up. The pick-up is a streak-like concave defect that is long in the extrusion direction, as shown in FIG. 3. The pick-up occurs during extrusion. During extrusion, the β-AlFeSi phase and the β-Mg2Si phase may react and melt. The β-AlFeSi phase and the β-Mg2Si phase may occur at the grain boundaries of the crystal grains, which are the aluminum parent phase, during solidification in the casting process, and may be adjacent to each other. It is believed that when the β-AlFeSi phase and the β-Mg2Si phase that are adjacent at the grain boundaries of the crystal grains react and melt during extrusion, the crystal grains are detached, and the pick-up is formed.

[0032] Patent Document 1 describes that the cast material is heated at a desired temperature of 550°C or more for 2 hours or more in order to transform the β-AlFeSi phase into the α-AlFeSi phase in the homogenization treatment. Patent Document 1 also describes that the cast material is water-cooled from a high temperature of 520°C or more in order to suppress the precipitation of the Mg2Si phase (presumed to be the β"-Mg2Si phase) in the homogenization treatment. Patent Document 1 considers that the β-AlFeSi phase and the β"-Mg2Si phase each cause pickup independently, and solves the two causes of pickup by different means. The β"-Mg2Si phase is generated within the grains of the crystal grains that are the aluminum parent phase during cooling in the homogenization treatment.

[0033] In contrast, in this embodiment, the pickup is considered to be caused by the reaction and melting of the β-AlFeSi phase and the β-Mg2Si phase adjacent to each other at the grain boundary during extrusion. In this embodiment, the cast material is heated at a desired temperature of 550°C or higher for 3 hours or more in order to transform as much of the β-AlFeSi phase into the α-AlFeSi phase in the homogenization treatment. In this embodiment, the Fe content is sufficiently high, and the ratio of the β-AlFeSi phase after the homogenization treatment can be sufficiently reduced. As a result, it is considered that the reaction between the β-AlFeSi phase and the β-Mg2Si phase during extrusion can be suppressed, and the pickup can be reduced.

[0034] FIG. 4 shows an example of the metal structure after casting and before homogenization. As shown in FIG. 4, before homogenization, the β-AlFeSi phase is observed at the grain boundaries of the crystal grains. The β-AlFeSi phase is three-dimensionally plate-like, and is observed as needle-like in the cut surface. FIG. 5 shows an example of the metal structure after homogenization and before extrusion. As shown in FIG. 5, after homogenization, the α-AlFeSi phase and the β-Mg2Si phase are observed at the grain boundaries of the crystal grains. The α-AlFeSi phase is granular. It can be seen from FIG. 4 and FIG. 5 that one acicular β-AlFeSi phase is divided into multiple granular α-AlFeSi phases by the homogenization. Note that both FIG. 4 and FIG. 5 are taken at a magnification of 1000 times and a field area of ​​11423 μm 2 It is.

[0035] In this embodiment, the homogenization treatment can be performed by slowly cooling the cast material from a desired temperature of 550°C or higher. For example, the homogenization treatment preferably includes the following steps (A), (B), and (C) in this order: (A) Heat the cast material at a desired temperature of 550°C or higher for 3 hours or more. (B) Cool the cast material from the desired temperature to 200°C at a cooling rate of 0.036°C / sec to 0.075°C / sec. (C) Cool the cast material from 200°C to room temperature at a cooling rate of 0.0028°C / sec to 0.022°C / sec. Note that, in this embodiment, as in Patent Document 1, the cast material can also be rapidly cooled from a desired temperature of 550°C or higher in the homogenization treatment.

[0036] When the cut surface of the cast material after homogenization and before extrusion, i.e., the extrusion billet, is observed with an electron microscope, it is preferable that (S1+S2) is 90% or more of (S1+S2+S3), where the area occupied by α-AlFeSi is S1, the area occupied by α'-AlFeSi is S2, and the area occupied by β-AlFeSi is S3. Note that when observed with an electron microscope, the magnification may be, for example, 1000 times, and the field area is, for example, 11423 μm 2 It may be.

[0037] If (S1+S2) is 90% or more of (S1+S2+S3), the proportion of β-AlFeSi phase is small after homogenization, and the reaction between β-AlFeSi phase and β-Mg2Si phase during extrusion can be suppressed, which is considered to reduce pick-up. (S1+S2) is more preferably 95% or more of (S1+S2+S3). The proportion of (S1+S2) is preferably as large as possible, and may be 100%. However, it is not realistic to make the proportion of (S1+S2) 100%. (S1+S2) is preferably less than 99.9% of (S1+S2+S3).

[0038] In the aluminum alloy of this embodiment, the ratio (Fe content / Si content) of the Fe content (mass%) to the Si content (mass%) is preferably greater than 0.44. The Fe content is sufficiently greater than the Si content, and the ratio of the β-AlFeSi phase after homogenization can be reduced. In addition, the Fe content is sufficiently greater than the Si content, and the precipitation of the Si single phase can be suppressed. As described above, the Si single phase is hard and brittle, and can cause pick-up. The ratio (Fe content / Si content) is preferably 0.46 or more, and more preferably 0.48 or more.

[0039] In the aluminum alloy of this embodiment, the ratio (Fe content / Si content) of the Fe content (mass%) to the Si content (mass%) is less than 1.20. By limiting the Fe content, it is possible to limit the generation of coarse Fe-based intermetallic compounds and reduce the surface roughness of the aluminum alloy. The ratio (Fe content / Si content) is preferably 1.10 or less. EXAMPLES

[0040] Next, experimental data will be described with reference to Table 1. In Examples 1 to 9, extrusions of aluminum alloys having the compositions shown in Table 1 were produced, and the number of pickups, mechanical properties, and surface roughness were measured. Examples 1 to 5 are working examples, and Examples 6 to 9 are comparative examples. Note that the compositions of the aluminum alloys of the present disclosure are not limited to the compositions of the working examples shown in Table 1.

[0041] In Examples 1 to 9, the manufacturing method shown in FIG. 2 was adopted as the manufacturing method of the extruded material. Hereinafter, the manufacturing conditions common to Examples 1 to 9 will be described. In the casting process, a cylindrical cast material was obtained by the hot top casting method. Next, in the homogenization process, the cast material was held at 550°C for 4 hours, cooled from 550°C to 200°C at a cooling rate of 0.056°C / sec, and cooled from 200°C to room temperature at a cooling rate of 0.0063°C / sec. Then, the cast material was cut to a length of 550 mm so as to fit in the container in the extruder. Next, in the extrusion process, the cast material heated to 480°C was placed in a container, and extruded with a stem from a die fixed to the container, to obtain an extruded material having a rectangular cross-sectional shape with a thickness of 8 mm and a width of 50 mm. Next, in the die quench process, solution treatment and quenching were performed at the outlet of the die for extrusion. The temperature at the outlet of the die was about 500°C to 540°C. The quenching was performed by cooling with a fan. Finally, in the aging treatment step, natural aging treatment was performed for 24 hours, and then artificial aging treatment was performed at 200° C. for 3 hours. In this manner, the extruded material was obtained.

[0042] The content of each component of the aluminum alloy constituting the extruded material was measured by emission spectrometry in accordance with JIS H 1305:2005.

[0043] The total ratio ((S1+S2) / (S1+S2+S3)) of the α-AlFeSi phase and the α´-AlFeSi phase in the cut surface of the cast material after the homogenization treatment but before the extrusion process, i.e., the extrusion billet, was measured by image processing of the backscattered electron image taken with a JEOL field emission scanning electron microscope JSM-7000F. The backscattered electron image was magnified 1000 times. A plate-shaped test piece with a length of 8 mm, a width of 8 mm, and a thickness of 1.5 mm was prepared as a test piece for microstructural observation. The surface to be observed was a rectangular end face (long side 8 mm, short side 1.5 mm), which was polished in advance with a JEOL cross-section polisher. Two types of test pieces were prepared. One surface to be observed was perpendicular to the extrusion direction. The other surface to be observed was parallel to the extrusion direction. The total ratios of α-AlFeSi and α´-AlFeSi phases ((S1+S2) / (S1+S2+S3)) were comparable in the two observed surfaces. The α-AlFeSi, α´-AlFeSi and β-AlFeSi phases were identified based on the elemental ratio of Fe to Si (Fe:Si). The elemental ratio (Fe:Si) of the α-AlFeSi phase was 1:2-1:3, the elemental ratio (Fe:Si) of the α´-AlFeSi phase was 1:1.5-1:2 and the elemental ratio (Fe:Si) of the β-AlFeSi phase was approximately 1:1. The elemental ratio (Fe:Si) was measured by semi-quantitative analysis using an energy dispersive X-ray analyzer attached to the JSM-7000F.

[0044] The number of pick-ups per unit area of ​​the extruded material was measured by observation with a stereomicroscope. Pick-ups were defined as long stripe-like defects in the extrusion direction and with a width of 1 mm or more among the concave defects on the surface of the extruded material.

[0045] The mechanical properties (tensile strength, yield strength, elongation) of the extruded material were measured by performing a tensile test at a strain rate of 1 mm / min using a Shimadzu universal testing machine AG-100kN+. The test specimens used were proportional test specimens No. 14B as described in Appendix D of JIS Z 2241:2011.

[0046] The surface roughness of the extruded material was measured using a Keyence VK-X100 shape measuring laser microscope in accordance with JIS B 0601: 1994. Here, the maximum height (Ry) was used as the surface roughness.

[0047] [Table 1]

[0048] In Table 1, an "A" rating means that all of the following (i), (ii), and (iii) are satisfied, and an "B" rating means that at least one of the following (i), (ii), and (iii) is not satisfied. (i) The number of pickups per unit area of ​​the extrusion is zero. (ii) The mechanical properties (tensile strength, yield strength, and elongation) satisfy the requirements for 6063 alloy described in JIS H 4100:2015. JIS H 4100:2015 specifies that the tensile strength of 6063 alloy is 205 MPa or more, the yield strength is 170 MPa or more, and the elongation is 10% or more. (iii) The maximum height (Ry) is less than 5.0 μm.

[0049] As shown in Table 1, in Examples 1 to 5, the Si content was 0.20 mass% to 0.90 mass%, and the Fe content was 0.22 mass% to 0.50 mass%, unlike Examples 6 to 9. Therefore, Examples 1 to 5 were evaluated as A, whereas Examples 6 to 9 were evaluated as B.

[0050] From Table 1, it can be seen that the higher the Fe content or the larger the ratio (Fe content / Si content), the larger the total ratio of the α-AlFeSi phase and the α´-AlFeSi phase ((S1+S2) / (S1+S2+S3)) is, and the more the pickup can be suppressed. It is believed that pickup occurred in Example 6 because the Si content was too high, and in Example 9 because the Fe content was too low.

[0051] It can be seen from Table 1 that the surface roughness (maximum height Ry) increases as the Fe content increases or as the ratio (Fe content / Si content) increases. In Examples 7 and 8, the Fe content was too high relative to the Si content, which is thought to have caused the formation of coarse Fe-based intermetallic compounds and increased the surface roughness.

[0052] It can be seen from Table 1 that the higher the Si content, the greater the mechanical properties (tensile strength and yield strength). In Example 7, it is believed that the Si content was too low, causing the tensile strength to fall below the prescribed 205 MPa.

[0053] The Al-Mg-Si aluminum alloy extrusion material and its manufacturing method according to the present disclosure have been described above, but the present disclosure is not limited to the above-mentioned embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

Claims

1. An extrusion material of an Al-Mg-Si based aluminum alloy, 0.20% by mass to 0.90% by mass of Si; Fe: 0.22% by mass to 0.50% by mass; Cu: 0.01% by mass to 0.40% by mass; Mn: 0.01% by mass to 0.50% by mass; Mg: 0.40% by mass to 1.20% by mass; 0.01% by mass to 0.15% by mass of Cr, 0.01% by mass to 0.25% by mass of Zn, Ti: 0.001% by mass to 0.15% by mass; Each contains The aluminum alloy is an extruded material of an Al-Mg-Si aluminum alloy, the balance of which is composed of unavoidable impurities and aluminum.

2. 2. The extruded material of Al-Mg-Si-based aluminum alloy according to claim 1, wherein the aluminum alloy has a ratio of the Fe content (mass%) to the Si content (mass%) (Fe content / Si content) of more than 0.

44.

3. The extruded material of Al-Mg-Si-based aluminum alloy according to claim 1 or 2, wherein the aluminum alloy has a ratio (Fe content / Si content) of the Fe content (mass%) to the Si content (mass%) of less than 1.

20.

4. A method for producing an extruded material of the Al-Mg-Si-based aluminum alloy according to claim 1 or 2, A step of homogenizing the casting material; performing an extrusion process on the cast material after the homogenization treatment; The present invention relates to a method for producing an extruded material of an Al-Mg-Si based aluminum alloy.

5. The homogenization treatment is Heating the casting material at a desired temperature of 550° C. or higher for 3 hours or more; cooling the cast material from the desired temperature to 200°C at a cooling rate of 0.036°C / sec to 0.075°C / sec; The method for producing an extruded material of an Al-Mg-Si system aluminum alloy according to claim 4, comprising the steps of:

6. 5. The method for producing an extruded material of an Al-Mg-Si-based aluminum alloy according to claim 4, wherein, when a cut surface of the cast material is observed by an electron microscope after the homogenization treatment and before the extrusion, an area occupied by α-AlFeSi is S1, an area occupied by α'-AlFeSi is S2, and an area occupied by β-AlFeSi is S3, where (S1+S2) is 90% or more of (S1+S2+S3).

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