JP2012255191A - Aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy with which an extruded shape having low surface roughness and exhibiting excellent brightness without buffing is obtained.SOLUTION: The aluminum alloy contains 0.30-0.60 wt.% Si, 0.35-0.65 wt.% Mg, and 0.015-0.054 wt.% B.

Description

  The present invention relates to an aluminum alloy having a small surface roughness and capable of obtaining an extruded profile excellent in glitter even without buffing.

  6000 series aluminum alloys such as A6063 and A6061 are widely used for building materials, furniture, home appliances, etc., as extruded profiles. However, when a conventional aluminum extruded shape is extruded from a die, a large number of fine lines called die lines are formed on the surface, so that the surface is not smooth and has low gloss. In the case where a high design property such as an audio panel is required, the die line is eliminated by buffing after extrusion.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an aluminum alloy having a small surface roughness and capable of obtaining an extruded profile excellent in glitter even without buffing.

  In order to achieve the above object, the aluminum alloy according to the first aspect of the present invention has an Si content of 0.30 to 0.60 wt%, Mg of 0.35 to 0.65 wt%, and B of 0.015 to 0.054 wt%. % Content.

  The reason why the die line is formed on the surface of the conventional aluminum extruded profile is thought to be that aluminum is thickly and unevenly coated on the die bearing during extrusion, and this aluminum coating is transferred to the surface of the profile. In the aluminum alloy according to the first aspect of the present invention, 0.01 to 0.054 wt% of B is added, so that the compound formed by B has an action of cleaning (polishing) the bearing of the die. Since the aluminum coating is thinly and uniformly formed, the die line is suppressed, and an extruded shape having a small surface roughness and excellent glossiness can be obtained. By containing 0.30 to 0.60 wt% Si and 0.35 to 0.65 wt% Mg, mechanical properties and extrudability are generally good.

It is a figure which shows an example of the cross-sectional shape of an extrusion shape member. It is a graph which shows the relationship between B content and surface roughness. 2 is a photograph of the appearance of extruded profiles according to Example 2 and Comparative Example 1. (A) is a schematic diagram of a die, and (b) is a photograph of a die bearing in which Example 2 and Comparative Example 1 are extruded. It is a cross-sectional structure | tissue observation photograph of the extrusion shape material by Examples 1-4 and Comparative Example 1. FIG. It is the cross-sectional structure | tissue observation photograph of the extrusion shape material by Example 4, and the enlarged photograph of the particles 1 and 2 in it.

  Embodiments of the present invention will be described below. The aluminum alloy of the present invention contains 0.30 to 0.60 wt% Si, 0.35 to 0.65 wt% Mg, and 0.015 to 0.054 wt% B. Furthermore, Fe, Mn, Ti, Cu, etc. may be contained as impurities. Hereinafter, the reason why the function of each component and the component range are limited in this way will be described.

Si is added to precipitate Mg ₂ Si and impart strength to the material, and the strength increases as the content increases. When Si is more than 0.60 wt%, the extrusion processability and surface properties are lowered, and when Si is less than 0.30 wt%, the strength is lowered. Therefore, in order to ensure substantially good extrudability, strength, and surface properties, Si is set to 0.30 to 0.60 wt%. When the Si content is 0.40 to 0.48 wt%, the extrudability and the mechanical properties can be improved in a balanced manner, which is more preferable.

Mg is added to precipitate Mg ₂ Si and impart strength to the material, and the strength increases as the content increases. When Mg is more than 0.65 wt%, the extrudability and surface properties are lowered, and when Mg is less than 0.35 wt%, the strength is lowered. Therefore, in order to ensure generally good extrudability, strength, and surface properties, Mg is set to 0.35 to 0.65 wt%. When the Mg content is 0.45 to 0.53 wt%, the extrudability and the mechanical properties can be improved in a balanced manner, which is more preferable.

  B is not usually added to the JIS A6063 alloy, but if a small amount of B is added, an effect of smoothing the surface of the extruded profile is obtained by the cleaning action of the die bearing by the compound produced by B. When B is more than 0.054 wt%, billet casting becomes difficult, and when B is less than 0.015 wt%, the surface smoothing effect cannot be sufficiently obtained. Therefore, B is set to 0.015 to 0.054 wt%.

  Fe exists as an impurity, and if it is too much, the surface properties and strength of the extruded shape will be reduced. The content of Fe is preferably approximately 0.07 to 0.13 wt%.

  Mn improves strength and surface properties when added in a small amount. If too much, there is no effect. The content of Mn is preferably about 0.02 to 0.05 wt%.

  Next, a procedure for producing an extruded shape from the aluminum alloy of the present invention will be described. First, a billet is manufactured by a conventional continuous casting method using a molten aluminum alloy to which the above elements are added. Next, in order to homogenize the billet structure, the billet is homogenized at a general temperature and time. Thereafter, the billet is hot-extruded and extruded into a predetermined cross-sectional shape. Thereafter, the extruded shape material is subjected to a surface treatment such as an alumite treatment after an artificial age hardening treatment, if necessary. The homogenization treatment, hot extrusion processing, and artificial age hardening treatment can be performed under normal conditions in the A6063 alloy.

  Examples of the present invention will be described below in comparison with comparative examples. Table 1 shows alloy components of Examples and Comparative Examples. Comparative Example 1 does not contain B, Comparative Examples 2 and 3 have a B content outside the scope of Claim 1, and Comparative Example 4 has a Si and Mg content outside the scope of Claim 1. is there. Table 2 shows the extrusion situation when extruding the alloys of Examples and Comparative Examples, and the results of die observation after extrusion. FIG. 1 shows a cross-sectional shape of an extruded profile, which is used for an audio panel.

  As shown in Table 2, the extruding situation is good for Examples 1 to 5 and Comparative Examples 1 to 3, and there is no particular problem with the dies after extrusion. In Example 6, since the contents of Si and Mg are large, the extrudability is slightly worse as compared with Examples 1 to 5, but is generally good. Since Comparative Example 4 has a higher Si and Mg content than Example 6, the extrudability is further deteriorated.

  Table 3 shows the tensile strength, proof stress, and elongation of the extruded shapes of Examples and Comparative Examples that were T5 heat treated.

  As shown in Table 3, when Examples 1-4 containing 0.02 to 0.05 wt% of B and Comparative Example 1 containing no B are compared, there is not much difference in tensile strength, yield strength, and elongation. It was confirmed. Each of Examples 1 to 6 has high strength that sufficiently satisfies the standard of A6063T5. In particular, Example 6 has higher tensile strength and yield strength than Examples 1 to 5 because of the high Si and Mg contents.

  Table 4 shows the surface roughness Ra, Rz and the cloth glossiness of the extruded profiles of Examples and Comparative Examples. Moreover, the relationship between B content and surface roughness Ra is shown in FIG. FIG. 3 is a photograph of the appearance of an extruded profile made from the alloys of Example 2 and Comparative Example 1.

As shown in Table 4 and FIG. 2, in Comparative Example 1 that does not contain B, the surface roughness Ra is about 0.3 μm, whereas Examples 1 to 6 that contain 0.02 to 0.05 B. Then, Ra is as small as about 0.1 μm or less. The fabric glossiness is also significantly improved in Examples 1 to 6 as compared with Comparative Example 1 containing no B. Among Examples 1-6, although there is no big difference in surface roughness and glossiness by some B content, Example 6 with much content of Si and Mg is compared with Examples 1-5. Slightly large surface roughness. As shown in FIG. 3, the surfaces of the extruded profiles of Examples 1 to 6 have a mirror-like shape in which the die line is not noticeable and buffed. Although Comparative Example 1 and Comparative Example 2 having a B content of less than 0.015 wt% have a smaller surface roughness than Comparative Example 1 that does not contain B, Ra is higher than 0.1 μm and the die line is also conspicuous. It becomes a state.
As is clear from the above results, by adding 0.015 to 0.054 wt% of B, it is possible to obtain an extruded shape having a smooth surface where the die line is not noticeable without buffing after extrusion. .

  The extruded shapes of Example 2 and Comparative Example 1 were alumite-treated (silver, dark bronze), and the surface appearance was observed. The results are shown in Table 5.

  As shown in Table 5, it was confirmed that both Example 2 and Comparative Example 1 had no surface defects due to alumite, and the surface treatment property was good even in the examples of the present invention to which B was added.

  In order to investigate the cause of smoothing the surface of the extruded profile by adding a small amount of B, as shown in FIG. 4 (a), a die obtained by extruding Example 2 containing 0.03% by weight of B, and B A die obtained by extruding Comparative Example 1 not containing was divided into upper and lower parts, and the bearings were observed. FIG. 4B is an enlarged photograph of the bearing. As shown in FIG. 4 (b), the comparative example 1 (right side) has a thick and uneven aluminum coating on the bearing, whereas the example 2 (left side) has an aluminum coating. Is thin and uniform. When the surface roughness of the aluminum coating was measured, Ra of the example 2 was 0.05 μm, and Ra of the comparative example 1 was 0.24 μm. Since the surface of the extruded profile is formed by transferring the aluminum coating of the die bearing, it is considered that the surface of the extruded profile becomes smooth because the aluminum coating is thin and uniform.

  FIG. 5 is a photograph of the cross-sectional structure of extruded profiles according to Examples 1 to 4 and Comparative Example 1. As shown in the figure, it can be seen that relatively large black particles are conspicuously increasing as the amount of addition of B increases. FIG. 6 is an enlarged photograph of the particles. These particles are the compounds produced by the added B, and these particles clean (polish) the die bearings to make the bearing's aluminum coating thin and uniform, along with the surface of the extruded profile. Is thought to be smooth.

  As described above, the aluminum alloy of the present invention to which B is added in an amount of 0.015 to 0.054 wt% has an action of cleaning (polishing) the die bearing by the compound produced by B, thereby Since the aluminum coating is thinly and uniformly formed, the die line is suppressed, and an extruded profile having a low surface roughness and excellent glossiness can be obtained without buffing. By containing 0.30 to 0.60 wt% Si and 0.35 to 0.65 wt% Mg, mechanical properties and extrudability are generally good. In particular, those containing 0.40 to 0.48 wt% Si and 0.45 to 0.53 wt% Mg can be improved in a good balance between extrudability and mechanical properties. The surface properties are further improved.

  The present invention is not limited to the embodiments described above. The alloy component can be changed as appropriate within the scope of the claims. The conditions for the homogenization treatment of the billet, the extrusion conditions, the cross-sectional shape of the extruded profile, and the conditions for the aging treatment after extrusion are arbitrary. The use of the aluminum alloy of the present invention is arbitrary, and for example, it can be used for building materials such as sashes and handrails, furniture, electrical products, parts of automobiles, and the like.

Claims (1)

  An aluminum alloy containing 0.30 to 0.60 wt% of Si, 0.35 to 0.65 wt% of Mg, and 0.015 to 0.054 wt% of B.