JPH0718363A - Aluminum alloy material excellent in bendability and its production - Google Patents

Abstract

PURPOSE:To produce an aluminum alloy material excellent in bendability and in which fractures by working can be prevented and surface quality can be improved and to provide a method for producing the same. CONSTITUTION:This aluminum alloy material is the one contg., by weight, 4.6 to 2% Zn, 0.9 to 1.3% Mg, 0.2 to 0.3% Mn, 0.12 to 0.18% Cu, 0.10 to 0.20% Zr, 0.025 to 0.04% Cr, 0.005 to 0.035% Ti, <=0.20% Fe and <=0.07% Si. At the time of producing it by hot extrusion, the billet is extruded at 6 to 9m/min extrusion rate while it is heated to 430 to 450 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention produces an aluminum alloy material excellent in bending workability used for a frame or an arm of a motorcycle etc. and an aluminum alloy material excellent in bending workability by hot extrusion. Regarding the method.

[0002]

2. Description of the Related Art For members such as frames or arms of motorcycles, a lightweight and rust-resistant aluminum alloy material is used in order to enhance sportiness and fashionability and facilitate maintenance thereof. There is.

Conventionally, as this type of aluminum alloy material, a 7000 series aluminum alloy material such as JIS A7N01 alloy material has been used.

[0004]

However, in the conventional 7000 series aluminum alloy material, when the material structure is fibrous, a plastic deformation zone is formed on the surface when the material is bent or when it is stretch-corrected after extrusion. (Stretcher strain mark) is generated, and during the subsequent bending process, the portion becomes uneven, and in some cases, there is a problem that the uneven portion breaks from the starting point.

Further, when the material structure of the aluminum alloy material is recrystallized remarkably in the surface portion, the surface becomes orange peel (orange peel) when subjected to bending work, and then painting or alumite treatment etc. However, there is a problem that the appearance of the product is significantly impaired even if the surface treatment is performed.

Therefore, in order to control the above two characteristics based on the material structure, various methods have been devised for an aluminum alloy material extruding method or an extruding apparatus.
The desired effect has not been achieved.

The present invention has been made in view of the above problems, and it is possible to prevent breakage due to processing and to improve surface quality, and an aluminum alloy material excellent in bending workability and its manufacture. The purpose is to provide a method.

[0008]

The aluminum alloy material excellent in bending workability according to the present invention comprises 4.6 to 5.2 wt% Zn, 0.9 to 1.3 wt% Mg, and 0.1. 2 to 0.3 wt% Mn, 0.12 to 0.18 wt% C
u, 0.10 to 0.20 wt% Zr, 0.025 to 0.04 wt% Cr, 0.005 to 0.035 wt% Ti, 0.20 wt% or less Fe and 0.07 It is characterized by containing Si by weight or less and the balance being aluminum and inevitable impurities.

The method for producing an aluminum alloy material having excellent bending workability according to the present invention is 4.6 to 5.2 wt% Zn, 0.9 to 1.3 wt% Mg, 0.2. To 0.3 wt% Mn, 0.12 to 0.18 wt% C
u, 0.10 to 0.20 wt% Zr, 0.025 to 0.04 wt% Cr, 0.005 to 0.035 wt% Ti, 0.20 wt% or less Fe and 0.07 It is characterized in that an aluminum alloy billet containing Si by weight or less is hot extruded at a temperature of 430 to 450 ° C. at an extrusion speed of 6 to 9 m / min.

[0010]

The reason for adding each component and the reason for limiting the composition of the aluminum alloy material having excellent bending workability according to the present invention will be described below.

Zn Zn has a function of improving the strength of the aluminum alloy material by forming a solid solution with Al and finely precipitating a part thereof. However, if the Zn content is less than 4.6% by weight, the action is insufficient, and the Zn content is 5.
If it exceeds 2% by weight, its action is saturated and the cost only increases. Therefore, the Zn content is set to 4.6 to 5.2% by weight.

Mg and Cu Mg and Cu have the action of promoting solid solution hardening and precipitation hardening due to fine precipitates. However, the content of Mg is less than 0.9% by weight, or the content of Cu is 0.1
If it is less than 2% by weight, its action is insufficient. On the other hand, when the Mg content exceeds 1.3% by weight, the action is saturated and the extrudability of the aluminum alloy material decreases, and when the Cu content exceeds 0.18% by weight, the action is saturated. As a result, the weldability of the aluminum alloy material decreases. Therefore, the Mg content is 0.9 to 1.3% by weight.
And the Cu content is 0.12 to 0.18 wt%.

Mn, Zr, Cr and Fe Mn, Zr, Cr and Fe are transition metal elements, and M
n and Fe have a function of promoting solid solution hardening and precipitation hardening, and Zr and Cr have a function of refining crystal grains to improve the strength of the aluminum alloy material. However, M
The content of n is less than 0.2% by weight, the content of Zr is less than 0.10% by weight, or the content of Cr is 0.0.
If it is less than 25% by weight, the fiber state of the material structure is weakened and recrystallization is likely to occur, so that orange peel is generated by bending. On the other hand, the Mn content exceeds 0.3% by weight, the Zr content exceeds 0.2% by weight, the Cr content exceeds 0.04% by weight, or the Fe content is 0.2%.
When it exceeds 0% by weight, not only the action is saturated, but
Since the fibrous structure is finely reinforced, stretcher strain marks are generated by tension straightening during the manufacturing process or subsequent bending. Therefore, the Mn content is 0.
2 to 0.3% by weight, the Zr content is 0.10 to 0.2% by weight, and the Cr content is 0.025 to 0.
The content of Fe is 0.20% by weight or less.

Ti and Si Ti and Si have the function of refining the intermetallic compound and improving the strength of the aluminum alloy material. However,
If the Ti content is less than 0.005% by weight, the action is insufficient. On the other hand, when the Ti content exceeds 0.035 wt% and the Si content exceeds 0.07 wt%, the action is saturated, the cost increases, and the toughness of the aluminum alloy material decreases. Therefore, the content of Ti is set to 0.005 to 0.035% by weight, and the content of Si is set to 0.07% by weight or less.

Next, a method for manufacturing an aluminum alloy material having excellent bending workability according to the present invention will be described. That is,
When hot-extruding the aluminum alloy material having the above composition, by setting the billet heating temperature and the extrusion speed to predetermined values, the structure does not recrystallize, and stretcher strain marks are generated by straightening or bending. An aluminum alloy material having a fibrous structure that is difficult to obtain can be obtained.

When the heating temperature of the billet is lower than 430 ° C., not only the extrudability of hot extrusion is lowered, but also the heat treatment effect is insufficient and sufficient strength cannot be obtained. on the other hand,
When the heating temperature of the billet exceeds 450 ° C, the surface of the aluminum alloy material is seized and the surface quality deteriorates. Further, when the surface quality is deteriorated, the extrusion speed is decreased to suppress the deterioration of the surface quality, and the productivity of the aluminum alloy material is decreased. Therefore, the billet heating temperature is 430 to 450.
To ℃.

If the extrusion speed is less than 6 m / min,
The fiber structure of the aluminum alloy material becomes finer, stretcher strain marks are likely to occur, and the productivity of the aluminum alloy material decreases. On the other hand, if the extrusion temperature exceeds 9 m / min, the aluminum alloy material may be cracked or a thick recrystallized layer may be formed on the surface of the aluminum alloy material, and orange peel may be generated by subsequent bending. Therefore, the extrusion speed is set to 6 to 9 m / min.

According to the present invention, it is possible to prevent the occurrence of stretcher strain marks and orange peel when processing an aluminum alloy material, so that it is possible to prevent breakage due to processing and deterioration of commercial property. The surface quality can be improved.

[0019]

Embodiments of the present invention will now be described with reference to the accompanying drawings.

First, the aluminum alloy raw materials according to Examples 1 and 2 and Comparative Examples 1 and 2 whose compositions are shown in Table 1 below are melted and cast (DC casting) by ordinary methods to form ingots. Obtained. Then, this ingot is heated to 470 ° C. for 6
A billet for extrusion was produced by performing a homogenizing treatment for time. The aluminum alloys according to Comparative Examples 1 and 2 are conventional JIS 7N01 alloys.

[0021]

[Table 1]

Next, the billet heating temperature was set to 440 ° C., the extrusion rate was set to 8 m / min, the above-mentioned extrusion billets were extruded from the extruder, straightened, and then subjected to an aging treatment by two-stage heating to obtain an extrusion mold material. Obtained.

Mechanical properties (tensile strength σ _B , 0.2% proof stress σ _0.2, and elongation) at room temperature of the extruded mold materials according to Examples 1 and 2 and Comparative Examples 1 and 2 obtained as described above are obtained. δ) was measured and a stress corrosion cracking resistance (SCC) test was conducted. The results are shown in Table 2 below. Further, each extruded mold material was subjected to bending, and the surface quality after the straightening and after the bending was evaluated. The results are shown in Table 3 below.

In the SCC test, a dichromic acid solution is used as a liquid for dipping the extrusion mold material, the load stress is set to 19 kgf / mm ² , the test time is set to 360 minutes at the maximum, and the test direction is set to the L direction and the L direction. In the −T direction, those in which stress corrosion cracking did not occur are indicated by ◯, and those in which stress corrosion cracking resistance occurred were indicated by ×. The surface quality was evaluated on a scale of 5 according to the occurrence status of orange peel and stretcher strain marks, and the one with few occurrences was shown as excellent, and the one with poorer quality was shown as 4, 3, 2, 1. It was

[0025]

[Table 2]

[0026]

[Table 3]

As is clear from Tables 2 and 3, the extruded profiles according to Examples 1 and 2 have the same mechanical properties as the extruded profiles according to Comparative Examples 1 and 2 using the conventional 7N01 alloy. In addition, stress corrosion cracking did not occur, orange peel and stretcher strain marks could be prevented from occurring after bending, and the surface quality was excellent.

[0028]

As described above, the aluminum alloy material excellent in bending workability according to the present invention is Zn, Mg, M.
Since the contents of n, Cu, Zr, Cr, Ti, Fe and Si are set to predetermined values, it is possible to prevent stretcher strain marks and orange peel from occurring during processing. For this reason, it is possible to prevent the aluminum alloy material from breaking due to processing and improve the surface quality.

Further, according to the method for producing an aluminum alloy material having excellent bendability according to the present invention, the aluminum alloy material having excellent bendability described above can be produced by hot extrusion. This makes it possible to obtain an aluminum alloy material having excellent bending workability, which is suitable for a member such as a frame or an arm of a motorcycle that requires bending work.

Claims (2)

[Claims] 1. 4.6 to 5.2 wt% Zn, 0.9
To 1.3 wt% Mg, 0.2 to 0.3 wt% M
n, 0.12 to 0.18 wt% Cu, 0.10 to 0.20 wt% Zr, 0.025 to 0.04 wt%
Cr, 0.005 to 0.035 wt% Ti, 0.
An aluminum alloy material having excellent bendability, characterized by containing 20% by weight or less of Fe and 0.07% by weight or less of Si, and the balance being aluminum and inevitable impurities. 2. 4.6 to 5.2 wt% Zn, 0.9
To 1.3 wt% Mg, 0.2 to 0.3 wt% M
n, 0.12 to 0.18 wt% Cu, 0.10 to 0.20 wt% Zr, 0.025 to 0.04 wt%
Cr, 0.005 to 0.035 wt% Ti, 0.
An aluminum alloy billet containing less than 20% by weight of Fe and less than 0.07% by weight of Si should be 430-45.
A method for producing an aluminum alloy material having excellent bendability, which comprises performing hot extrusion at an extrusion speed of 6 to 9 m / min at a temperature of 0 ° C.