JP2550384B2 - Method for producing extruded aluminum alloy material with suppressed surface recrystallization - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an aluminum alloy extruded material for use in rims and rear forks of motorcycles, cutting rods and other general shape members, and in particular aluminum with suppressed surface recrystallization. The present invention relates to a method for manufacturing an alloy extruded material.

Conventional technology and its problems Generally, Al-Zn-Mg system, Al-Zn-Mg-Cu system, Al-Cu system, Al-
Cu-Mg-based, when extruding aluminum or aluminum alloy billet such as Al-Mg-Si-based, a recrystallized layer is formed on the surface of the extruded material, resulting in color unevenness after anodizing and impairing the appearance, It has been conventionally recognized that there is a problem that it may cause surface roughness and weld cracking during processing, or that stress corrosion cracking resistance may deteriorate. Therefore, conventionally, the surface recrystallized layer is removed by buffing the extruded material surface prior to processing, but the surface recrystallized layer is thick, so it can be easily removed. There wasn't. On the other hand, in order to suppress the formation of the recrystallized layer, the homogenization treatment condition, the extrusion temperature, the extrusion speed, etc. are also appropriately adjusted, but the desired effects cannot be obtained. .

The present invention has been made in view of the above technical background, and an object thereof is to provide an aluminum alloy extruded material in which surface recrystallization is suppressed.

Means for Solving the Problems In the above object, the present invention is to add one or two or more kinds of Zr, Mn, Cr and Fe for adjusting the structure to aluminum or an aluminum alloy, and add the element for adjusting the structure. While using the aluminum alloy billet prepared as above, an extrusion die having an inclined surface having a predetermined length and angle on the bearing side inlet side of the die is used, and the billet is extruded in combination with this die, thereby extruding the billet. The present invention has been completed by finding that the surface recrystallized layer of the material can be eliminated or the thickness of the recrystallized layer can be reduced.

That is, according to the method for producing an aluminum alloy extruded material in which recrystallization is suppressed according to the present invention, referring to FIGS. 1 and 2, aluminum for extrusion or an aluminum alloy has Zr: 0.05 to 0.5 wt%, Mn. : 0.05-1.2wt%, Cr: 0.05-
0.6%, Fe: 0.2-1.5wt% 1 or 2 selected from the group
When extruding an aluminum alloy billet (2) containing more than one kind of structure adjusting element and adding this structure adjusting element, the extrusion cross-sectional area is continuously reduced at the inlet side peripheral edge of the bearing part (11). The inclined surface (12) with an inclination angle (θ) of 1 ° or more is 0.1 m in the length (L) in the extrusion direction.
It is characterized by extruding using an extrusion die (1) having a length of at least m.

Aluminum alloy billet used in this invention (2)
Is an aluminum or aluminum alloy that can be used for extrusion, Zn: 0.05 ~ 0.5 wt%, Mn: 0.05 ~ 1.2 wt%, Cr: 0.0
It contains one or two or more kinds of texture adjusting elements selected from the group of 5 to 0.6 wt% and Fe: 0.2 to 1.5 wt%.
Such a structure adjusting element suppresses recrystallization of the extruded material and forms a fibrous structure. In terms of such effects, they are mutually equivalent, and one or two or more thereof may be contained, but if each is less than the lower limit, the recrystallization suppressing effect is poor, and conversely if the upper limit is exceeded, coarse crystallization occurs. Things are generated.
The aluminum or aluminum alloy to which the element for adjusting the structure is added may be one used for extrusion, for example, Zn: about 0.8 to 6.5 wt%, Mg: about 0.5 to 2.9 wt% or further Cu: 1.2 to Al-Zn containing about 2.0wt%
-Mg-based (JIS7000-based) alloys, Al-Cu-based alloys containing Cu: 1.5-6.0 wt% or Mg: 0.2-1.8 wt% (20
00 series) alloy, Mg: 0.35-1.5wt%, Si: 0.2-1.2wt%
Al-Mg-Si-based (6000-based) alloys and the like containing a certain amount can be cited, but which one is used may be selected depending on the application and the like. For example, when applied to the rim of a motorcycle or the rear hawk, it is preferable to use 7000 series alloy.

The extrusion die (1) has a continuous extrusion cross-sectional area at the inlet side peripheral edge of the bearing portion (11) as shown in FIG. 1 in order to suppress the formation of a surface recrystallized layer of the extrusion material (4). It is manufactured to have a gradually decreasing inclined surface (12). further,
This inclined surface (12) has a length (L) in the extrusion direction of 0.1 mm or more, and the inclination angle, that is, the angle (θ) formed by the extension line of the bearing portion (11) and the inclined surface (12) is 1 °. The above conditions are required. This is because when the length (L) in the extrusion direction is less than 0.1 mm and the inclination angle (θ) is less than 1 °, the effect of suppressing the formation of the recrystallized layer on the surface of the extruded material (4) is poor. Most preferably, the length (L) in the extrusion direction is set to 3 to 10 mm, and the inclination angle (θ) is set to 3 to 10 °. The inclined surface (12) may be linearly inclined toward the bearing portion (11) or may be curvedly inclined. In the case of inclining curvilinearly, the condition of the inclination angle θ ≧ 1 ° is that the angle between the tangent line at any one point on the inclined surface and the extension line of the bearing portion (11) is at least 1 ° or more. Incidentally, (13) shown in FIG. 1 is a relief portion, and (3) shown in FIG. 2 is a container.

When an aluminum alloy billet containing an element for structure adjustment is extruded using the extrusion die (1), the surface recrystallized layer of the extruded material (4) disappears or has a thickness of about 100 μm even if it exists. The following can be thinned.
Also, when recrystallization occurs, the grain size becomes relatively small,
Usually, it is often 100 μm or less.

Effects of the Invention According to the above of the present invention, Zr: 0.05 to 0.5 wt%, M
n: 0.05-1.2wt%, Cr: 0.05-0.6%, Fe: 0.2-1.5wt% selected from the group of 1 or 2 or more kinds of texture adjusting elements are added, and this texture adjusting element is added. The extruding die containing the aluminum alloy billet has an inclined surface with an inclination angle of 1 ° or more at which the extrusion cross-sectional area continuously decreases at the inlet side peripheral edge of the bearing portion over 0.1 mm or more in the length in the extrusion direction. Since it is extruded by using, it is possible to eliminate the formation of a recrystallized layer on the surface of the extruded material or to make it thinner than in the conventional case. Therefore, when the recrystallized layer does not exist, since it can be easily removed by buffing or the like even when it exists, the occurrence of color unevenness after the anodizing treatment due to the presence of the recrystallized layer, the rough surface during processing, and the weld cracking,
It is possible to prevent deterioration of stress corrosion cracking resistance.

Embodiment Next, an embodiment of the present invention will be described.

The aluminum alloy billets having various compositions as shown in Table 1 containing the elements for adjusting the structure were changed in the inclination angle (θ) of the inclined surface and the length (L) in the extrusion direction as shown in Table 2. Extrusion die shown in Fig. 1 (bearing length 2m
m) was extruded into a rim material (5) having a sectional shape shown in FIG. Billet temperature 480 ℃, ram speed 1.6
It was performed at 7 mm / s.

In each of the extruded materials obtained as described above, test pieces were sampled at two points (a) and (b) shown in FIG. 3, and the thickness of the surface recrystallization was examined. The results are also shown in Table 2.

As can be seen from the results in Table 2 above, it was confirmed that the present invention can provide an extruded material having a thin surface recrystallized layer.

In addition, with respect to Sample Nos. 1 to 4, micrographs of the cross-sectional structures of the test pieces (a) and (b) are shown in FIGS. 4 to 7. As is clear from these photographs, the extruded material produced according to the present invention has a thin surface recrystallized layer. In addition, in the conventional die having no inclined surface and the die having an inclined surface,
Since the strain distribution of the extruded material is different at the time of extrusion, the extruded material produced by the die having no inclined surface (Fig. 7) has a very fine structure immediately below the surface recrystallization layer. The material has a slightly larger structure.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part of an extrusion die used in the present invention, FIG. 2 is a sectional view of an essential part showing a state during an extrusion process using the die of FIG. 1, and FIG. 3 is an extruded example. 4 to 7 are micrographs of the structures of the rim materials obtained in the examples. (1) …… Extrusion die, (11) …… Bearing part, (12) …… Inclined surface, (2) …… Billet, (4)…
… Extruded material.

Claims (1)

(57) [Claims] 1. Extruded aluminum or aluminum alloy, Zr: 0.05-0.5wt%, Mn: 0.05-1.2wt%, Cr: 0.0
5 to 0.6%, Fe: 0.2 to 1.5 wt% One or more elements selected from the group of structure adjusting elements are added, and an aluminum alloy billet (2) containing this structure adjusting element is extruded. When processing, the inclination angle (θ) of 1 ° at which the extrusion cross-sectional area continuously decreases at the inlet side peripheral edge of the bearing part (11)
The above inclined surface (12) in the length (L) in the extrusion direction
A method for producing an aluminum alloy extruded material with suppressed surface recrystallization, which comprises extruding using an extrusion die (1) having a diameter of 0.1 mm or more.