JPH08209279A - High strength and high formability aluminum alloy - Google Patents

Abstract

PURPOSE: To produce an Al alloy having high strength and high formability by prescribing the compositional ratios of Al alloy contg. Mg, Cu, Si, Cr, Mn, Fe and Ti under specified conditions. CONSTITUTION: The compsn. of an alloy contg. Mg, Cu, Si, Cr, Mn, Fe, Ti, and the balance Al lies within a quadrangle obtd. by surrounding the lines connecting the primary point (4.7% Mg, 0.0% X), the secondary point (4.0% Mg, 0.4% X), the third point (7.2% Mg, 0.68% X) and the fourth point (8.0% Mg, 0.0% X) in the Figure in which the axis of abscissas expresses the Mg concn. (by atom) and the axis of ordinates expresses X (by atom), i.e., the expresse in terms of concn. defined by the formula. Moreover, the compsn. is constituted of, by atom, <=0.3% Cu, <=0.2% Si, 0.1% Cr, 0.2% Mn, <=0.1% Fe, <=0.01% Ti, and the balance Al with inevitable impurities. Thus, the Al alloy having high strength and high formability can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength and high-formability aluminum alloy used for automobile parts requiring high strength and high formability.

[0002]

2. Description of the Related Art In recent years, aluminum alloys have been adopted in automobile parts in order to reduce the weight of vehicle bodies, and the conventional JIS5086 (Al-0.
45 wt% Mn-4.0 wt% Mg-0.15 wt% Cr),
5182 (Al-0.35 wt% Mn-4.5 wt% M
g), 5083 (Al-0.7 wt% Mn-4.5 wt% M
Alloys such as g-0.15 wt% Cr) have been used. However, although such a high-Mg alloy has high elongation, it has high deformation resistance and has problems such as difficulty in rolling. In addition, since the strength and the formability change greatly due to the influence of the additive elements Cu, Mn, Cr, and Ti, it is important to understand the relationship between the compositions of each element even though it is important to understand each characteristic. Didn't. In the present specification, strength means tensile strength, proof stress, hardness, etc., and moldability means elongation,
Erichsen value, deep drawability, and overhanging property.

In view of the above, the present invention has been studied by various methods, and as a result, Al
A high-strength and high-formability aluminum alloy was developed by investigating the relationship between the addition amount of the additional element in the Mg-based alloy and the strength and formability in detail.

That is, the present invention relates to Mg, Cu, Si, Cr,
In an aluminum alloy containing Mn, Fe, and Ti and the balance Al, the horizontal axis represents the Mg concentration (at%), and the vertical axis represents the converted concentration X (at%) defined by the following formula. Mg 4.7at%, X0.0at% Second point Mg4.0at%, X0.4at% Third point Mg7.2at%, X0.68at% Fourth point Enclosed by a line connecting Mg8.0at%, X0.0at% Has a composition in a rectangular shape
0.3 at% or less, Si 0.2 at% or less, Cr 0.1 at%
Below, Mn 0.2 at% or less, Fe 0.1 at% or less, Ti
It is characterized by being 0.01 at% or less and the balance being Al and inevitable impurities. X = Cuat% + 0.664 × Siat% + 1.07 × Feat% + 1.10 × Mnat% + 1.14 × Crat% + 1.24 × Tiat% ………

[0005]

The alloy of the present invention, as described above, is suitable for Mg, Cu, S.
Diagram showing i, Cr, Mn, Fe, Ti, the balance Al and unavoidable impurities, and the horizontal axis represents the Mg concentration (at%) and the vertical axis represents the converted concentration X (at%) defined by the above formula. 1, 1st point Mg 4.7at%, X0.0at% 2nd point Mg 4.0at%, X0.4at% 3rd point Mg 7.2at%, X0.68at% 4th point Mg 8.0at%, X0.0at %, The composition within the rectangle surrounded by the line connecting
0.3 at% or less, Si 0.2 at% or less, Cr 0.1 at%
Below, Mn 0.2 at% or less, Fe 0.1 at% or less, Ti
Due to the compositional limitation of 0.01 at% or less, the tensile strength is 25
An aluminum alloy having a high elongation of 0 MPa or more and an elongation of 30% or more can be obtained.

In FIG. 1, however, sufficient strength cannot be obtained on the low density side of the line connecting the first and second points, and moldability deteriorates on the high density side of the line connecting the second and third points. And then the third
On the high-concentration side of the line connecting the point and the fourth point, the deformation resistance is high and the rolling process becomes difficult. Within the composition limited range surrounded by the rectangle, both high strength and high ductility characteristics are satisfied.

Cu 0.3 at% or less, Si 0.2 at%
Below, Cr 0.1 at% or less, Mn 0.2 at% or less, Fe
0.1 at% or less, Ti 0.01 at% or less, balance Al
The reason why the composition consisting of unavoidable impurities is limited to obtain a tensile strength of 250 MPa or more and an elongation of 30% or more as described above.
% Or less is an impurity level, and if it exceeds this level, the elongation characteristics deteriorate, if the Cu content exceeds 0.3 at%, the formability deteriorates, and if the Cr content exceeds 0.1 at%, crystallized substances are formed. To deteriorate the formability. If the Mn content exceeds 0.2 at%, the elongation decreases, and if the Ti content exceeds 0.01 at%, the crystal grains become coarse and the formability deteriorates.

[0008]

EXAMPLES The present invention will be described below with reference to examples. FIG.
Inventive Examples 1 to 20 and Comparative Examples x 21 to 39, that is, alloys containing the components of the Inventive Example and Comparative Example shown in Table 1 were cast by a normal method and subjected to predetermined homogenization to obtain 300 ~ 4
After hot rolling at 00 ° C, cold rolling was performed to obtain a plate material having a thickness of 1 mm. After that, solution treatment was performed at 550 ° C. The ease of hot rolling was investigated for these materials, and a tensile test was conducted after the solution treatment. The results are shown in Table 2.

[0009]

[Table 1]

[0010]

[Table 2]

As is clear from Table 2, the invention examples No. 1 to No. 1
20 has a high tensile strength of 250 MPa or more and has an elongation of 30%.
It turns out that it is expensive. On the other hand, Comparative Examples No. 21 to 33
Had inferior strength or elongation characteristics, and Comparative Examples 34 to 39 had cracks during hot rolling, and Nos. 38 and 39 had severe cracking levels and were difficult to manufacture.

Further, the solution treatment temperatures are 450 ° C. and 500 ° C.
As a result, all showed the same tendency as above. Further, the plate thickness was changed to 0.7 mm and 2.0 mm for some samples, but the result was not changed at all.

[0013]

As described above, according to the present invention, an aluminum alloy having high strength and high formability can be obtained, which is industrially remarkable such as facilitating the production of automobile parts requiring high strength and high formability. Has a great effect.

[Brief description of drawings]

FIG. 1 Mg concentration (at%) and Cu, Si, Cr, M
It is a diagram showing the composition range of the alloy of the present invention represented by the converted concentration X (at%) of n, Fe and Ti.

Claims (1)

[Claims] 1. Mg, Cu, Si, Cr, Mn, Fe,
In an aluminum alloy containing Ti and the balance being Al, the horizontal axis represents the Mg concentration (at%) and the vertical axis represents the converted concentration X (at%) defined by the following formula. %, X0.0at% Second point Mg4.0at%, X0.4at% Third point Mg7.2at%, X0.68at% Fourth point Square surrounded by a line connecting Mg8.0at% and X0.0at% With the composition of
0.3 at% or less, Si 0.2 at% or less, Cr 0.1 at%
Below, Mn 0.2 at% or less, Fe 0.1 at% or less, Ti
A high-strength and high-formability aluminum alloy, which is 0.01 at% or less, the balance being Al and inevitable impurities. X = Cuat% + 0.664 × Siat% + 1.07 × Feat% + 1.10 × Mnat% + 1.14 × Crat% + 1.24 × Tiat% ………