JPH05311309A - Impact beam made of aluminum alloy for automobile side door - Google Patents

Abstract

PURPOSE:To produce a lightweight and high-strength impact beam for automobile side door by incorporating specific percentages of Zn, Mg, Cu, Ti, Mn, Cr, Zr, and V into Al, extruding the resulting alloy, and applying T6 treatment. CONSTITUTION:An aluminum alloy having a composition consisting of, by weight, 4.0-8.0% Zn, 0.5-2.5% Mg, 0.01-0.5% Cu, further at least one kind selected from the group consisting of 0.005-0.30% Ti, 0.05-0.7% Mn, 0.01-0.5% Cr, 0.05-0.3% Zr, and 0.01-0.15% V, and the balance Al with impurities is prepared. This alloy is extruded and subjected to T6 treatment (solution heat treatment, hardening, and tempering), by which mechanical strength is improved. By this method, the lightweight and high-strength impact beam made of aluminum alloy suitable for being attached to the inside of automobile side door can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact beam for protecting an occupant installed in a side door of an automobile.

[0002]

2. Description of the Related Art Impact beams are being installed inside the side doors of automobiles for the purpose of protecting passengers in the event of a side collision. Since the impact beam is required to have a high energy absorption amount at the time of collision, conventionally, it is usually 100
A high-tensile steel pipe of kgf / mm ² class (hereinafter referred to as high-tense pipe) or a high-tensile pipe of 150 kgf / mm ² class is used.

[0003]

However, in the high tensile pipe, the mass of the impact beam is large (about 1.5 mm).
kg / m), which is a problem for weight reduction of the vehicle body. Furthermore, FMVSS No. 214 (Side Door S
In the bending test based on trength), there was a problem that the load buckled locally just below the load element and showed a sudden load decrease.

An object of the present invention is to solve the above problems and to provide a lightweight and high-strength automobile side door impact beam.

[0005]

The aluminum alloy automobile side door impact beam according to the present invention has a structure of Z
n: 4.0 to 8.0 wt%, Mg: 0.5 to 2.5 wt%, and Cu: 0.01 to 0.5 wt%, and further Ti: 0.005 to 0. 30% by weight, Mn: 0.0
5 to 0.7% by weight, Cr: 0.01 to 0.5% by weight, Z
r: 0.05 to 0.3% by weight, and V: 0.01 to 0.
An aluminum alloy containing at least one selected from the group consisting of 15% by weight and the balance being Al and impurities is extruded and then subjected to T6 treatment.

The T6 treatment means a treatment for increasing the strength by age hardening by sequentially performing solution treatment, quenching and tempering, that is, a treatment for obtaining the temper of T6. In this case, it is preferable that the quenching is performed with water cooling and the tempering is performed under the condition that the maximum strength is obtained.

The reasons for limiting the composition and the proportion of the aluminum alloy automobile side door impact beam of the present invention having the above structure are as follows. Zn: Increases strength at room temperature. If it is less than 4.0% by weight, high strength cannot be obtained in T6 treatment, and if it exceeds 8.0% by weight, stress corrosion cracking tends to occur.

Mg: Increases the strength at room temperature.
If it is less than 0.5% by weight, high strength cannot be obtained in the T6 treatment, and if it exceeds 2.5% by weight, hot workability, that is, extrudability is deteriorated, and stress corrosion cracking tends to occur. Cu: Improves stress corrosion cracking resistance. If it is less than 0.01% by weight, the effect is small, and if it exceeds 0.5% by weight, the improving effect is saturated, so that there is little industrial advantage and the weldability is deteriorated.

Ti: Effective in refining the cast structure and preventing ingot cracking during casting. Further, it is effective in refining crystal grains and improving stress corrosion cracking resistance. If it is less than 0.005% by weight, the effect is small, and if it exceeds 0.3% by weight, a huge intermetallic compound crystallizes out, which is not preferable.

Mn, Cr, Zr, V: These elements are
It is effective in refining crystals and improving stress corrosion cracking resistance. If it is less than the respective lower limit values, the effect is small, and if it exceeds the upper limit value, a huge crystallized product is formed during DC casting which is generally used industrially, which is not preferable.

The aluminum alloy automobile side door impact beam of the present invention is formed by extruding an aluminum alloy composed of the above metal elements and then subjecting it to T6 treatment. An aluminum alloy automobile side door impact beam having extremely improved mechanical strength can be obtained by performing T6 treatment on the aluminum alloy composed of the above-mentioned elements each having a characteristic action. These elements are
It is considered that they are involved in each other and improve the mechanical properties. Moreover, since aluminum is the main component,
It will be fairly lightweight.

[0012]

Preferred embodiments of the present invention will be described below in order to further clarify the constitution and effects of the present invention described above. The composition ratio is based on the weight of the entire alloy. Zn: 5.5 wt%, Mg: 1.5 wt%, Cu:
0.15 wt%, Mn: 0.2 wt%, Zr: 0.16
An aluminum alloy ingot composed of wt% was extruded into two kinds of so-called solid shapes whose cross section is shown in FIG.

[0013]

[Table 1]

Here, the height H is in the range of 25 to 32 mm. If the height is less than 25 mm, the bending strength becomes insufficient,
This is because if it exceeds 32 mm, it will not fit inside the door. Next, the solid extruded material was subjected to T6 treatment of 475 ° C. × 1 h → water cooling → 120 ° C. × 12 h to obtain an impact beam. In order to examine the energy absorption amount of the impact beam at the time of collision, a three-point bending test in which the two end points A and B of the impact beam or the pipe 1 are supported and a load P is applied to the central portion C (Fig. 3) Was performed and compared with the conventional high ten pipe. The high-tense pipe used here had a normal outer diameter of 31.8 mm and a wall thickness of 2.0 mm. The bending test results are shown in FIG. 4 and Table 1.

As is clear from FIG. 4 and Table 1, the solid shape aluminum alloy extruded material according to the present invention has almost the same maximum load as that of the high-tense pipe, but it is almost the same as that of the high-tensile pipe. The buckling does not occur, and the absorbed energy up to a load point displacement of 140 mm is improved compared to the high-tensile pipe, 12% each
And 5% greater. In addition, the mass was significantly reduced compared to the high-tense pipe, and the weight was 29% and 12% lighter, respectively.

According to each of the above-described examples, by properly selecting the composition and extrusion shape of the aluminum alloy and performing the T6 treatment successfully, it is possible to manufacture the aluminum alloy having higher strength and lighter weight than the conventionally used high strength material. The car side door impact beam can be obtained.

Therefore, the automobile side door impact beam of the present invention is not only required to have high strength, but also has a size and weight limitation because it is mounted inside the door. You can get the appropriate one.

In each of the above embodiments, the extruded shape is a solid shape having an increased cross-sectional modulus and increased strength.
It is also possible to make a hollow shape having high strength as shown in FIG. However, the extrusion speed of the solid shape is three times (about 15 m / min) as compared with the hollow shape (about 5 m / min) and is extremely fast, so that the material cost is further reduced. Further, although only one metal composition ratio is shown in the above examples, a lightweight and high-strength alloy was obtained with other compositions within the scope of the present invention. Also, M
Similarly, when Ti, Cr, and V were used instead of n and Zr, a lightweight and high-strength alloy was obtained.

The embodiment of the present invention has been described above.
The present invention is not limited to these examples, and it goes without saying that the present invention can be implemented in various modes without departing from the scope of the present invention.

[0020]

As described in detail above, according to the aluminum alloy automobile side door impact beam of the present invention, there is an excellent effect that it is lightweight and can be made extremely high in strength. In addition, when the aluminum alloy automobile side door impact beam is formed in a solid shape, it is lightweight and has high strength, and the extrusion speed is fast and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a solid shape of an aluminum alloy automobile side door impact beam of this embodiment.

FIG. 2 is a cross-sectional view showing a hollow shape as an example of another shape.

FIG. 3 is an explanatory diagram illustrating a three-point bending test method used in this example.

FIG. 4 is a graph showing a bending load with respect to a load point displacement of an aluminum alloy automobile side door impact beam and a high tensile pipe automobile side door impact beam for comparison in the present embodiment.

Claims (1)

[Claims] 1. Zn: 4.0 to 8.0% by weight, Mg:
0.5-2.5% by weight and Cu: 0.01-0.5% by weight, further Ti: 0.005-0.30% by weight, Mn: 0.05-0.7% by weight %, Cr: 0.01
To 0.5 wt%, Zr: 0.05 to 0.3 wt%, and V: 0.01 to 0.15 wt%, at least one selected from the group consisting of Al and impurities. An aluminum alloy side door impact beam made of aluminum alloy, which is obtained by extruding the following aluminum alloy and then performing T6 treatment.