JP2002363677A - Al-Mg BASED ALUMINUM ALLOY HOLLOW EXTRUSION MATERIAL FOR BULGING - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an Al-Mg based aluminum alloy hollow extrusion material which has excellent bulging formability. SOLUTION: This Al-Mg based aluminum alloy hollow extrusion material contains, by mass, 1.5 to 5.0% Mg and 0.005 to 0.2% Ti, and satisfies H112 in refining. The extrusion material is suitable for forming a suspension subframe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy hollow extruded material having excellent bulge formability suitable for forming a frame or a joint portion of an automobile, a railway car or a building member.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of environmental problems such as global warming and destruction of the ozone layer, in order to suppress an increase in carbon dioxide gas in the atmosphere, lightening of automobiles and introduction of electric automobiles have been in earnest. Is being considered. As part of this reduction in weight, the replacement of materials, that is, the use of aluminum alloy materials instead of steel plates that have been mainly used in structural materials for automobiles has been increasing. Also in electric vehicles, there is a strong need to reduce the weight of the vehicle body to compensate for the increase in weight for loading batteries. Furthermore, the use of aluminum alloy materials has attracted attention, as extruded materials that provide a constant, but free cross-sectional shape in the longitudinal direction can expand the degree of freedom of design and improve the formability by obtaining a cross-sectional shape close to the final shape. For example, Japanese Patent Application Laid-Open No. 2000-177621 discloses that an aluminum alloy extruded material is used for manufacturing a suspension subframe.

On the other hand, bulge forming has attracted attention as a method of forming parts having complicated shapes such as a joint member used for joining frames during body assembly and a suspension sub-frame. It is known to use a suspension bulge formed by bulging. In addition, Japanese Patent Laid-Open No. 5-2
Japanese Patent No. 12464 describes that a 5000 series (Al-Mg based) aluminum alloy plate is hydraulically formed.

[0004]

In the case of Al-Mg based aluminum alloys, an annealing material (O material), which is generally advantageous in terms of formability, has been used as a material for bulging. However, when the overhang height of the bulge molding was high, a crack was formed at the top of the overhang portion, and the overhang molding could not be performed greatly. The present invention has been made in view of such problems with respect to bulge forming of an Al-Mg-based aluminum alloy, and is excellent in bulge formability (particularly, overhang height), and is suitable for a frame of an automobile, a railway vehicle, or a building member. Another object of the present invention is to provide an Al-Mg-based aluminum alloy hollow extruded material suitable for forming a joining member and the like.

[0005]

According to the present invention, there is provided an Al-Mg-based aluminum alloy hollow extruded material for bulge forming, comprising:
An Al-Mg-based aluminum alloy hollow extruded material for bulge forming, comprising 1.5 to 5.0% and Ti: 0.005 to 0.2%, and having a tempering of H112 (see JIS H0001). It is. In the present invention, bulge molding refers to expanding a part of a member by using fluid pressure (sometimes called hydroforming) and expanding a part of the member by applying a negative pressure to the outside of the member. Means to put out.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The Al-Mg-based aluminum alloy contains, if necessary, one or more of Mn, Cr, Zr and V as additional elements other than the above, and further contains Fe as an unavoidable impurity. , And other elements. Hereinafter, the reason for adding each component in the aluminum alloy hollow extruded material according to the present invention will be described. Mg Mg forms a solid solution in the aluminum matrix and improves the alloy strength. Strength required for structural members such as automobile frames or joint members (proof strength σ0.2 ≧ 50MPa)
In order to obtain Mg, it is necessary to add 1.5% or more of Mg. However, if added in excess of 5.0%, the amount of solid solution becomes excessive, and excellent bulge formability cannot be obtained. Therefore,
The Mg content is 1.5 to 5.0%. A more desirable range is 2.0 to 4.0%.

[0007] Ti Ti improves the alloy strength by refining the crystal grains during casting. To achieve this effect, Ti
It is necessary that the added amount be 0.005% or more. On the other hand, if the amount of Ti exceeds 0.2%, the above effect is saturated, and a coarse intermetallic compound is crystallized, so that a predetermined alloy strength cannot be obtained. Therefore, the content of Ti is 0.0
0.05 to 0.2%, more preferably 0.01 to 0.1%.
%, More preferably 0.01 to 0.05%.

Mn, Cr, Zr, V One or more of these elements may be used, if necessary, in order to control the structure in the manufacturing process, that is, to prevent crystal grains from coarsening and improve stress corrosion cracking resistance. Is added. 0.05%, 0.05%, 0.05%, 0.01 respectively
% Or less, the effect is not obtained.
If it exceeds 3% or 0.3%, the above effect is saturated, and a coarse intermetallic compound is crystallized, so that a predetermined alloy strength cannot be obtained.

Inevitable impurities Among the unavoidable impurities, Fe is the most contained impurity in aluminum ingot. If it exceeds 0.5% in the alloy, coarse intermetallic compounds are crystallized during casting, and the mechanical properties of the alloy are reduced. Impair the nature. Therefore, the content of Fe is restricted to 0.5% or less. Further, when casting an aluminum alloy, impurities are mixed from various routes such as a base metal, an intermediate alloy of an additional element, and a compound. The elements to be mixed are various,
Of impurities other than Si, 0.4% or less of Si and 0.2% of Cu
% Or less, Zn is 0.3%, and other impurities are 0.1% by themselves.
If it is not more than 05% and the total amount is not more than 0.15%, it hardly affects the properties of the alloy. Therefore, these impurities are set to the above numerical values or less. In addition, B among impurities is mixed into the alloy in an amount of about 1/5 of the Ti content with the addition of Ti, but a more preferable range is 0.02% or less, and further preferably 0.01% or less.

In the extruded Al-Mg-based aluminum alloy having the above composition, when the tempering is H112, the bulge formability is excellent because the uniform elongation is large, so that the deformation of the overhang portion at the time of bulge formation is localized. It is presumed that this is not the case, but the entire structure is deformed and the strain is dispersed, so that it can withstand stronger processing. It is thought that the dislocation is appropriately introduced while the H112 material is being extruded, thereby disturbing the movement of the dislocation at the time of deformation, and as a result, the deformation is dispersed and the uniform elongation is increased. On the other hand, in the O material conventionally used for bulge forming, dislocations are easily removed because dislocations are removed, deformation is concentrated locally, and uniform elongation is relatively small. It is considered that the deformation of the steel concentrates locally and cracks easily occur.

The Al-Mg-based aluminum alloy hollow extruded material according to the present invention can be manufactured by various extrusion methods, but indirect extrusion produces coarse recrystallized grains on the surface of the extruded material rather than direct extrusion. Is desirable in the sense of preventing
Although a porthole method is also possible, a mandrel method is more preferable than a porthole method from the viewpoint of ensuring the uniformity of the tissue in the cross section (there is no welded portion). Stretching (correction) after extrusion is also performed in H11.
Included in two materials.

[0012]

Next, an embodiment of the present invention will be described. First, aluminum alloy ingots having the compositions shown in Table 1 below were melted by a usual method, and these ingots were subjected to 520 ° C. × 4
hr, an extrusion process was performed at an extrusion temperature of 520 ° C. and an extrusion speed of 5 m / min. 1 to
As for 8, the outer diameter is 38.5 mm and the wall thickness is 1.5 mm
No. round pipe, No. 9 has an outer diameter of 47.0 mm,
A round pipe having a thickness of 1.5 mm was obtained. The material was cooled by air cooling with a fan (cooling rate: about 100 ° C./min) immediately after extrusion. No. Nos. 1 to 5 are left as they are. 6 ~
No. 8 was annealed at 380 ° C. × 2 hr after stretching. 9 was drawn to an outer diameter of 38.5 mm,
The thickness was 1.5 mm (H34), and each was used as a test material.

[0013]

[Table 1]

A JIS No. 12A test piece was prepared from this test material, and a tensile test was carried out in accordance with JIS Z2241 to determine a tensile strength σB, a proof stress σ0.2, and a total elongation (elongation to break). Further, based on the stress-strain diagram obtained in the tensile test, the elongation up to the point showing the maximum stress was determined as uniform elongation. Table 2 shows the results. Further, this test material was cut into a length of 177 mm, and a bulge forming test was performed. FIG. 1 is a schematic view showing a bulge forming test method. Each test material (pipe) 5 is set on a lower mold 1, mandrels 2 and 3 are inserted into end faces of the pipes, and then an upper mold 4 is tightened. At the same time as applying pressure to the inside of the pipe by passing water 6 through the holes 2a and 3a inside the pipe 3, the mandrel 2 and 3 were moved to compress the pipe in the longitudinal direction, thereby forming a T-shape.
The internal pressure (water pressure) was set to 14.7 MPa, the mandrel compression amount was set to 85 mm (42.5 mm on one side), and the overhang height (see FIG. 2) was set to 70 mm. The bulge formability was evaluated by the presence or absence of cracks (cracks) occurring on the surface of the overhanging top. The results are shown in Table 2 below. Here, no cracking was evaluated as ○, and cracking was evaluated as x.

[0015]

[Table 2]

[0016] As shown in Table 2, the composition of the component No. H112, which satisfies the requirements of the present invention, is H112. Each of Nos. 1 to 3 has good bulge formability, and the proof stress σ 0.2 satisfies the required strength as a structural member. On the other hand, N
o. No. 4 is inferior in bulge formability and has a small amount of Mg. 5
Lacks proof stress. In addition, No. 6-7
No. and H34 material. No. 9 is inferior in bulge formability probably because the total elongation is small. In addition, the extruded material according to the present invention also has good mouth-opening workability such as flange bending at the end and good hemming workability.

[0017]

As described above, as described above, Al-
In the case of Mg-based aluminum alloy hollow extruded material,
By setting to 112, excellent bulge formability can be obtained. This Al-Mg-Si-based aluminum alloy hollow extruded material is suitable as a bulge forming material for frames and joining members of automobiles, railway vehicles, ships or building members.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a bulge forming test method according to an example.

FIG. 2 is an explanatory diagram of an overhang height by a bulge forming test of an example.

[Explanation of symbols]

 1 Lower die 2, 3 Mandrel 4 Upper die 5 Test material (pipe)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C22F 1/00 630 C22F 1/00 630K 691 691B 691C 692 692A (72) Inventor Masakazu Hirano Nagafumo, Shimonoseki City, Yamaguchi Prefecture 14-1 Minatomachi Kobe Steel, Ltd. Chofu Works

Claims (2)

[Claims] 1. Al containing 1.5 to 5.0% (mass%, hereinafter the same) of Mg and 0.005 to 0.2% of Ti.
Al-M for bulge forming, comprising a Mg-based aluminum alloy hollow extruded material and having a tempering of H112.
g-based aluminum alloy hollow extruded material. 2. A suspension subframe using the aluminum alloy hollow extruded material according to claim 1.