JP2001316750A - EXTRUDED Al-Mg-Si ALUMINUM ALLOY EXCELLENT IN CRUSHING CAPACITY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an extruded Al-Mg-Si aluminum alloy which is contracted and deformed into a bellowslike shape without generating cracks when a compressive impact or a compressive static load is applied in the axial direction, and can absorb the impact load and static load. SOLUTION: This shape material has a fibrous crystal structure in T1 refining and has a composition in which the content of stoichiometrically equivalent Mg2Si composed of Mg and Si as the main alloy elements is 0.6 to 1.2%, containing Si exceeding stoichiometrically equivalent Mg2Si by <=0.6% and Cu by <=0.4% and containing at least one or more kinds selected from 0.05 to 0.3% Mn, 0.01 to 0.1% Ti, 0.05 to 0.1% Cr and 0.05 to 0.1% Zr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an A type having a function of absorbing an impact load and a static load when a compression impact load or a compression static load is applied in the extrusion axis direction of a profile.
The present invention relates to a 1-Mg-Si based aluminum alloy extruded member.

[0002]

2. Description of the Related Art A 6000 series (Al-Mg-Si) aluminum alloy has relatively high corrosion resistance among alloys having high tensile properties, and is widely used as a sash material in the market. Because of its superiority to aluminum alloys of the type described above, application to structural members and functional members has attracted attention. For example, as disclosed in Japanese Patent Application Laid-Open No. 7-118782, extruded profiles are used for automobile side members and bumper stays. It has been studied to apply it to a shock absorbing member.

[0003] One of the characteristics required of a shock absorbing member is as follows.
As described in the above publication, when the member is subjected to a load in the direction of the extrusion axis, the entire shape does not undergo Euler buckling (buckling in which the entire shape bends in a U-shape) without cracking. Shrinking deformation in the form of a bellows. Al-Mg-
In order to absorb the impact without causing cracks in the member by using the extruded Si-based alloy, a method of increasing the elongation of the member as much as possible to increase its deformability has been generally performed. .

Accordingly, the tensile strength and proof stress (0.
2% proof stress) must be kept at a state considerably lower than the maximum value that can be exhibited by the alloy, and when high strength is required for the member, an alloy element for improving the tensile properties, namely, Si , Mg, Cu and the like are added in a considerably large amount, and then annealing is performed to increase elongation. For this reason, it has been necessary to design a material that sacrifices the tensile strength and proof stress that the alloy can exhibit. In this method, 100% of the effect of the added alloy element was not utilized, and in some aspects, the addition was useless.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In an extruded Al-Mg-Si alloy material, an impact load of compression or a static load of compression in the direction of the extrusion axis. When subjected to a load, it shrinks and deforms in a bellows shape without generating cracks, has the effect of absorbing the impact load and static load, and without sacrificing the tensile strength or proof stress that the alloy can exhibit Further, an object of the present invention is to obtain an Al-Mg-Si based alloy extruded material having excellent crushing performance, wherein the crushing performance does not particularly depend on the value of elongation.

[0006]

The extruded Al-Mg-Si-based aluminum alloy according to the present invention, which is excellent in crushing performance, has a crystal structure showing a fiber structure under T1 tempering, and its main alloying element. The stoichiometrically balanced Mg ₂ Si composed of Mg and Si is 0.6% or more and 1.2% or less, and exceeds the stoichiometrically balanced Mg ₂ Si composed of Mg and Si. 0.6% or less of Si, Cu
Of 0.4% or less.

[0007] The present invention relates to A
The l-Mg-Si-based aluminum alloy extruded material has a crystal structure exhibiting a fiber structure under T5 tempering, and a stoichiometrically balanced Mg ₂ composed of its main alloying elements Mg and Si. Mg having a stoichiometric balance of 0.6% or more and less than 1.1% and comprising Mg and Si
0.6% of Si in excess of ₂ Si hereinafter, characterized by having a composition containing Cu 0.4% or less.

Further, the extruded Al-Mg-Si-based aluminum alloy material having excellent crushing performance according to the present invention is T6
Under refining, the crystal structure shows a fiber structure, and the stoichiometrically balanced Mg ₂ Si composed of Mg and Si, which are the main alloying elements, is 0.6% or more and 1.1% or less. , A stoichiometric equilibrium of Mg and Si
0.4% or less of Si exceeding g ₂ Si and 0.2% of Cu
It is characterized by having the following composition.

[0009] The extruded Al-Mg-Si-based aluminum alloy material has a tensile strength or a proof stress that the alloy can exhibit by controlling the crystal structure to a stable fiber shape under T1, T5 or T6 tempering. Without sacrificing and without depending on the value of elongation (there is no clear correlation between the magnitude of elongation and the presence or absence of cracks)
The crushing performance can be improved. Here, T1, T5
Alternatively, the T6 treatment is a treatment prescribed in JIS H0001, and the fiber structure means a structure in which a fiber structure by extrusion remains as it is without being recrystallized even during a heat treatment step after the extrusion step.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the Al-Mg according to the present invention will be described.
The chemical composition of the Si-based alloy will be described. Al-Mg
Major alloying elements of the -Si-based alloys are Mg and Si, mainly over these elements exceeds an amount stoichiometrically balanced to form a stoichiometrically equilibrium precipitates Mg 2 _Si S
The solid solution of i increases the tensile strength and proof stress of the material. However, in exchange for the improvement in tensile strength and proof stress, the deformability of the material is reduced, and cracking due to deformation in the extrusion axis direction is likely to occur.

In order to obtain industrially useful tensile properties, M
The g ₂ Si content is required to be 0.6% or more, and 0.8% or more provides higher tensile strength and proof stress. In the case of T1 refining, the deformation ability as an extruded material exceeds 1.2%. And the secondary processing becomes difficult, and cracks due to deformation in the direction of the extrusion axis tend to occur. Excess Si is also Mg ₂ Si
It has the effect of reducing the deformability instead of increasing the tensile strength and proof stress similarly to the above, and from the viewpoint of preventing cracking due to deformation in the extrusion axis direction, 0.6% or less (including 0%) in the case of T1 tempering. Is limited to The total amount of Si is preferably Mg ₂ S
The content is set to 1.0% or less together with Si constituting i.

Incidentally, as the degree of the heat treatment proceeds to T5 and T6, the tensile strength and proof stress of the Al-Mg-Si alloy increase, and the deformability decreases. Even with alloys of the same component, it is difficult to deform when the tensile strength and proof stress are high (the force required for processing is large). Nevertheless, when deformation and processing are forced, defects such as cracks and destruction occur. Will be.
Therefore, the composition range in which crush cracking can be prevented is inevitably narrower under T5 and T6 temper than under T1 temper. In the present invention, Mg ₂ Si is reduced to 1.1% or less and excess Si is reduced under T5 temper. 0.6% or less (including 0%), and under T6 refining, Mg ₂ Si is limited to 1.1% or less, and excess Si is limited to 0.4% or less (including 0%).

[0013] The Al-Mg-Si alloy according to the present invention contains the above-mentioned Mg and Si as main alloy elements, and contains Cu, Ti, Mn, Cr, Zr and the like as necessary. The following composition can be mentioned.
Cu has the function of increasing the tensile strength and proof stress of the alloy according to the added amount, but on the other hand, it also reduces the corrosion resistance and stress corrosion cracking resistance, and at the time of welding, uses a microfischer (base metal and bead to be welded). (A small internal crack generated near the interface of the alloy). Therefore, in general, when Cu is added to an Al-Mg-Si alloy as an additive element, the upper limit is 0.4% in order not to generate microfischer.

In the extruded profile of the present invention, T1
Alternatively, if the Cu content exceeds 0.4% under T5 refining, cracks are likely to occur due to deformation in the extrusion axis direction, and if the Cu content exceeds 0.2% under T6 refining, cracks tend to occur. T
(6) The reason why the composition range in which the crush cracking can be prevented under the refining is narrowed is the same reason as described above for Mg ₂ Si and Si. For the above reasons, the Cu content was limited to 0.4% or less or 0.2% or less (both including 0%) as described above. In order to obtain an effect of improving strength by adding Cu, it is preferable to add 0.1% or more.
Less than 0.1% may be contained as an acceptable impurity in the alloy of this system.

Next, T used as a grain refining element is used.
Each action of i, Mn, Cr and Zr will be described in detail. Ti
Has the function of forming nuclei during melting and casting to make the casting structure fine, and is appropriately added. The effect becomes remarkable when added at 0.01% or more, and when it exceeds 0.1%, a coarse compound is formed and the Al-Mg-Si alloy is made brittle, so the added amount is 0.01% or more and 0%. 0.1% or less is preferable.

Mn suppresses the recrystallization of the alloy structure and is effective in refining the structure. Due to this property, it has a function of stabilizing the fiber structure of the extruded material, and is added as appropriate.
The effect becomes apparent at 0.05% or more, but 0.3% or more.
%, The diffusion of Mg during the heat treatment is suppressed, the heat treatment property is deteriorated, and coarse Al ₆ Mn is generated to make the aluminum alloy brittle.
More than 0.3% is suitable.

Cr has the effect of pinning the grain boundaries and has the function of stabilizing the fiber structure of the extruded material.
It is added as appropriate. The effect becomes apparent at 0.05% or more. However, if it exceeds 0.1%, the initial pressure at the time of extrusion processing is remarkably increased, which is not practical. % Or more and 0.1% or less is preferable.
Like Zr, Zr has a pinning effect on the grain boundaries and has a function of stabilizing the fiber structure of the extruded material, so Zr is appropriately added. The effect becomes apparent at 0.05% or more, but the effect of stabilizing the fiber structure is not further increased even if added over 0.1%, so the added amount is 0.05% or more. 0.1% or less is preferable.

The preferred composition of the Al—Mg—Si alloy according to the present invention is, in addition to the aforementioned Mg, Si and Cu,
Composition containing Mn 0.05% or more and 0.3% or less, further, Ti 0.01% or more and 0.1% or less, Cr0.
05% or more and 0.1% or less, Zr 0.05% or more and 0.1%
A composition containing at least one or more of the following (particularly, Ti), or in addition to Mg, Si, and Cu, Ti.
01% or more and 0.1% or less, Cr 0.05% or more and 0.1%
And a composition simultaneously containing Zr 0.05% or more and 0.1% or less.

Next, the extrusion processing conditions will be described. Extrusion is usually performed at a hot temperature, and it is industrially common to use the processing temperature to serve as a solution. For this reason, it is important that the extrusion temperature be as high as possible the solution temperature.
If the extrusion temperature is too high, recrystallization of the crystal structure is promoted, and the fiber structure changes to coarse grains. On the other hand, the strain in the material when the material is deformed is guided by the movement of dislocations. However, since the dislocations disappear in a portion where the arrangement of metal crystals such as crystal grain boundaries is irregular, the metal crystals such as crystal grain boundaries and the like are lost. Are irregular, the lattice displacement due to the dislocations accumulates, and the distortion concentrates. Therefore, the distribution of dislocations in the material, that is, the distribution of strain, tends to be uniform throughout the material as the crystal grain size is smaller. Then, in order to suppress the occurrence of cracks at the time of crushing, it is necessary to make the deformation strain uniform in the material.

By suppressing the recrystallization and keeping the fiber structure, that is, the grain boundary in a fine state, the deformation strain can be evenly distributed in the material, and excellent tensile properties can be exhibited. Based on this,
In the extrusion step, it is preferable to control the temperature of the shaped material immediately after extrusion to an appropriate solution temperature range, that is, 515 ° C. or more and 550 ° C. or less.

[0021]

EXAMPLES Al-Mg-containing the chemical components shown in Table 1
470 is added to the ingot produced by semi-continuous casting of a Si alloy.
After performing a homogenizing heat treatment at 8 ° C. × 8 h, a 2 mm-thick rice-shaped section having a cross-sectional shape of 70 × 54 mm and a thickness of 2 mm is manufactured by the hot direct extrusion method at the solution treatment temperature, and extruded at the same time as room temperature water. And quenching was performed. The obtained extruded profile is T1
Used as a temper. In addition, 170 ° C x 6
h after the artificial aging treatment of T
The tempered material was again solution-solutioned at 530 ° C. × 1 h, quenched in room temperature water, and then subjected to artificial aging treatment at 170 ° C. × 6 h, and provided as a T6 tempered material.

[0022]

[Table 1]

The tensile properties were measured using a No. 13 B specimen specified in JISZ2201. The crushing characteristics were obtained by cutting each extruded member into a 150 mm length as a test piece, and applying a static compression load using a hydraulic universal testing machine in the extrusion axis direction.
It was examined whether or not cracks occurred in the test specimen from the start of compression to the amount of compression deformation of 100 mm. The numerical value showing the highest value among the loads applied during the compression deformation was determined as the maximum load, and the product of the load applied from the start of compression to the compression deformation amount of 100 mm and the deformation amount was defined as the absorbed energy.
The cross-sectional shape having the cross-sectional shape has the purpose of having a plurality of hollow portions so as to complicate material deformation at the time of crushing and to represent a shape generally used in industry. When crush cracking does not occur in this shape, it can be said that crush cracking does not substantially occur even in a shape material generally manufactured industrially.

Table 2 (T1 tempered material), Table 3 (T5 tempered material)
And Table 4 (T6 tempered material) shows the tensile properties, crush properties, and macrostructure of each test piece measured by the above procedure. Regarding the occurrence of cracks in the crushing characteristics,
Those that occurred were evaluated as x, and those that did not occur were evaluated as ○. As shown in Tables 2 to 4, the shape material satisfying the requirements of the present invention contracted and deformed in a bellows shape without generating cracks, and was excellent in crushing performance. On the other hand, cracks occurred in Comparative Examples not satisfying the requirements of the present invention.

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

According to the present invention, the crystal structure is made to be a stable fiber structure, so that it does not buckle when subjected to a compressive impact load or a compressive static load in the extrusion direction of the profile and cracks. An Al-Mg-Si based alloy extruded material excellent in crushing performance, which absorbs an impact load and a static load by contracting and deforming in a bellows shape without generating cracks, can be obtained.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazutoshi Sakano 14-1 Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Inside the Kofu Steel Works Chofu Works (72) Inventor Tatsuya Kinoshita 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture No. 5 Inside Kobe Research Institute, Kobe Steel, Ltd.

Claims (7)

[Claims] 1. The crystal structure of T1 has a fiber structure under tempering, and the main alloying element Mg
Mg ₂ Si in stoichiometric balance consisting of
6% (mass%, the same applies hereinafter) to 1.2% or less;
Al—Mg— having excellent crushing performance, characterized by having a composition containing 0.6% or less of Si and 0.4% or less of Cu exceeding stoichiometrically balanced Mg ₂ Si composed of g and Si.
Extruded Si-based aluminum alloy. 2. Under T5 tempering, its crystal structure shows a fiber structure, and its main alloying element is Mg.
Mg ₂ Si in stoichiometric balance consisting of
6% or more and 1.1% or less, and having a composition containing 0.6% or less of Si exceeding 0.4% and Cu exceeding Mg ₂ Si in a stoichiometric equilibrium composed of Mg and Si. An Al-Mg-Si-based aluminum alloy extruded material with excellent crush performance. 3. The T6 temper has a crystal structure showing a fiber structure, and its main alloying element Mg
Mg ₂ Si in stoichiometric balance consisting of
6% or more and 1.1% or less, and having a composition containing 0.4% or less of Si and 0.2% or less of Cu exceeding stoichiometrically balanced Mg ₂ Si composed of Mg and Si. An Al-Mg-Si-based aluminum alloy extruded material with excellent crush performance. 4. A stoichiometric equilibrium of Mg ₂ Si of 0.8
%. The extruded Al-Mg-Si-based aluminum alloy according to any one of claims 1 to 3, which is excellent in crushing performance. 5. The extruded Al—Mg—Si based aluminum alloy according to claim 1, which has a composition containing Mn of 0.05% or more and 0.3% or less. Shapes. 6. An alloy containing Mn of 0.05% to 0.3%, Ti of 0.01% to 0.1%, and Cr of 0.1% to 0.1%.
05% or more and 0.1% or less, Zr 0.05% or more and 0.1%
The extruded Al-Mg-Si-based aluminum alloy according to any one of claims 1 to 4, wherein the aluminum-Mg-Si-based aluminum alloy has a composition containing at least one of the following. 7. Ti not less than 0.01% and not more than 0.1%, Cr
5. The composition according to claim 1, wherein the composition contains both 0.05% and 0.1% of Zr and 0.05% and 0.1% of Zr. 6. Extruded Mg-Si aluminum alloy.