JP2003239030A - HIGH-RIGIDITY BORON-CONTAINING Al ALLOY - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an Al alloy which can also be manufactured by a low-cost, high-productivity melting/casting method and has excellent mechanical properties, such as strength, toughness and wear resistance, high shear modulus, and improved machinability and plastic workability. <P>SOLUTION: The Al alloy contains, by mass, >1.5 to 20% B. Further, the average size of B-containing compounds having AlB<SB>2</SB>type crystal structure is ≤200 μm, and those having ≤50 μm size among the compounds comprise ≥50% of the whole of the AlB<SB>2</SB>type B-containing compounds by percentage by number. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an Al alloy that exhibits excellent strength, toughness, and abrasion resistance and can improve the rigidity, and these characteristics are particularly required. The present invention relates to a B-containing Al alloy useful as a material for automobile parts.

[0002]

2. Description of the Related Art In recent years, weight reduction of automobiles has been promoted from the viewpoint of environmental protection and improvement of fuel consumption, and as a part thereof, the transition from iron-based materials to Al alloy materials is being carried out as a material for automobile parts. However, general Al alloys tend to be inferior in mechanical properties to iron-based materials. That is, automobile parts are required not only to have excellent mechanical properties such as strength, toughness and wear resistance, but also to have a high rigidity (stress / strain ratio) from the viewpoint of weight reduction and size reduction. However, there is a problem that these characteristics are not sufficient in a normal Al alloy.

For these reasons, Al alloys used as automobile parts are usually made to satisfy the above-mentioned characteristics by containing a relatively large amount of Si. That is, in the Al-Si alloy, it is said that by containing Si, the coefficient of thermal expansion can be reduced and the rigidity can be improved, and excellent wear resistance can be exhibited. As such an Al-Si based Al alloy, A403
Al alloy for forging such as 2FD (JIS H4140) and A
In addition to Al alloys for casting such as C8A and AC9B (JIS H5202), Al-Si alloys and the like by the powder metallurgy method are known (for example, JP-A-6-158211).
However, all of these Al-Si based Al alloys have the following problems, and in reality, they cannot be said to be characteristically sufficient as materials for automobile parts.

Among the Al alloys mentioned above, A4032FD and AC8A are excellent in heat resistance and strength by containing about 11 to 13% of Si. It is still insufficient in terms of wear resistance. In addition, in the above AC9B, 18 to 20
% Of Si, which exhibits excellent wear resistance, but due to coarsening of the primary crystal Si particles, the cutting tool wears early and machinability is low. Inferior,
Moreover, there is a problem that plastic workability and toughness are rather poor.

In order to solve such a problem, a technique such as Japanese Patent Laid-Open No. 6-293933 has been proposed. In this technique, the wear resistance of the Al alloy obtained by the melt casting method is controlled by controlling the grain size and distribution of primary crystal Si and eutectic Si and Si precipitates in the alloy structure together with optimization of the alloy composition. It significantly improves machinability and plastic workability, and exhibits excellent strength, toughness, and ductility. However, in order to obtain such an Al alloy by the melt casting method, there are many restrictions in the manufacturing conditions,
It is difficult to perform the above control stably.

Further, in the above technique, P is contained in order to prevent coarsening of the primary crystal Si, and growth inhibiting elements such as Na, Sb and Sr are contained in order to miniaturize the eutectic Si. Although it is also shown, these alloying elements basically cause the strength deterioration of the Al alloy, and the inclusion of these alloying components rather deteriorates the mechanical properties of the Al alloy. Further, in the above technique, the characteristics of the Al alloy are exhibited by controlling the morphology of the Si-containing compound. However, the Si-containing compound easily re-dissolves and grows at a high temperature, and the size of the compound varies. However, there is a drawback that the above characteristics cannot be stably exhibited.

On the other hand, Al produced by powder metallurgy
The alloy can contain not only a large amount of Si above the solid solution limit, but also alloy elements such as Fe, Ni, Mn, Cu, and Mg in a wide range, and moreover, primary crystal Si can be contained in an extremely large amount as compared with the melt casting method. Since it can be made extremely small, it has an advantage that heat resistance strength and wear resistance can be remarkably improved. However, in powder metallurgy, the raw material powder is expensive and
Since there are many manufacturing processes, the productivity is lower than that of the melting and casting method.

As a technique to which the powder metallurgy method is applied, S
An Al-based composite material containing a nitrogen compound instead of i has also been proposed (for example, JP-A-6-57363),
It can be said that this composite material exhibits excellent properties in terms of rigidity, but the cost and production disadvantages of applying the powder metallurgy method are unavoidable, and moreover, a sintering additive is also mixed in the matrix component. Must be done (Mg, Z
(n, Al-Cu-Mg, etc.), the versatility is low, and there is a problem that it can be used only for extremely limited purposes.

[0009]

SUMMARY OF THE INVENTION The present invention has been made under such circumstances, and an object thereof is to be manufactured by a melt casting method which is low in cost and excellent in productivity, and has strength and toughness. In addition to providing excellent mechanical properties such as wear resistance and the like, it is also an object of the present invention to provide an Al alloy exhibiting high rigidity and improved plastic workability.

[0010]

The boron-containing Al alloy of the present invention which has been able to achieve the above object is B: 1.5.
The average size of the B-containing compound having a crystal structure of AlB ₂ type is 200 μm or less and the size of the compound is 50 μm or less based on the entire AlB ₂ type B-containing compound. 5 in proportion to the number
The gist is that it occupies 0% or more. Further, in this Al alloy, the AlB ₂ type B-containing compound is 80 in terms of the number ratio with respect to all the compounds containing B.
% Or more is preferable.

In the boron-containing Al alloy of the present invention,
It contains B as a basic component, and other components are not particularly limited, but the following (a) to (g) are preferable as the Al alloy component system applicable in the present invention. In all cases, various mechanical properties can be improved by appropriately controlling the distribution state of the AlB ₂ type B-containing compound.

In addition to (a) B, Fe: 2% or less (including 0%) and / or Si: 2% or less (including 0%) is contained (hereinafter referred to as "1000 system composition"). , A1 alloy whose balance consists essentially of Al.

(B) In addition to B, Cu: 1.5 to 7% is contained, and if necessary, (i) Mg: 1.8% or less (not including 0%), Mn: 1.2% Below (not including 0%),
Cr: 0.4% or less (not including 0%), Zr: 0.3
% Or less (not including 0%), Zn: 0.5% or less (0%
Or not) and Ti: 0.3% or less (not including 0%), or (ii) Fe: 2
% Or less (not including 0%) and / or Si: less than 2% (not including 0%) (hereinafter, referred to as "2000-based composition"), and the balance is Al alloy consisting essentially of Al.

(C) In addition to B, Mn: 0.3 to 2% is contained, and if necessary, (i) Mg: 1.8% or less (not including 0%), Cu: 0.6% Below (not including 0%) C
r: 0.4% or less (not including 0%), Zr: 0.3%
One or more selected from the group consisting of the following (not including 0%), Zn: 0.5% (not including 0%) and Ti: 0.3% or less (not including 0%), or (ii ) Fe: 2% or less (including 0%) and / or Si: 2% or less (0%)
Is not included) (hereinafter referred to as “3000 series composition”), and the balance substantially consists of Al.

(D) In addition to B, Si: 2 to 16% is contained, and if necessary, Mg: 11% or less (0% is not included), Cu: 5% or less (0% is not included), Cr: 0.
4% or less (0% is not included), Ni: 0.6% (0% is not included), Mn: 0.6% or less (0% is not included),
Zr: 0.3% or less (not including 0%), Zn: 0.5
% (Not including 0%), Ti: 0.3% or less (not including 0%), and Fe: 2% or less (not including 0%), and at least one selected from the group (hereinafter: , "400
0 composition "), the balance being A1 consisting essentially of Al
alloy.

(E) In addition to B, Mg: 2 to 8% is contained, and if necessary, (i) Cu: 0.6% or less (not including 0%), Mn: 1% or less (0%) Not included), Cr:
0.4% or less (0% is not included), Zr: 0.3% or less (0% is not included), Zn: 0.5% (0% is not included) and Ti: 0.3% or less ( 1% or more selected from the group consisting of (0% is not included), and (ii) Fe: 2% or less (0% is not included) and / or Si: 2% or less (0)
% Al) (hereinafter referred to as “5000 series composition”), and the balance substantially consists of Al.

(F) In addition to B, Mg: 0.3 to 1.5%
And Si: 0.3 to 1.5%, if necessary Cu: 0.6% or less (0% is not included), Mn: 1% or less (0% is not included), Cr: 0.4 % Or less (0% is not included), Zr: 0.3% or less (0% is not included), Z
n: 0.5% (not including 0%), Ti: 0.3% or less (not including 0%) and Fe: 2% or less (not including 0%), one or more selected from the group consisting of (Hereinafter referred to as “6000 system composition”), and the balance is substantially Al.
Al alloy consisting of.

(G) In addition to B, Mg: 1 to 4% and Z
n: 0.8 to 8%, and if necessary, (i) Cu:
3% or less (not including 0%), Mn: 1% or less (not including 0%), Cr: 0.4% or less (not including 0%),
Zr: 0.3% or less (not including 0%) and Ti:
One or more selected from the group consisting of 0.3% or less (not including 0%), and (ii) Fe: 2% or less (not including 0%) and / or Si: less than 2% (0% is not included). Not included)
(Hereinafter, referred to as “7000-based composition”), and the balance substantially consists of Al.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied from various angles, aiming at the realization of Al alloys having improved various mechanical properties, without being caught by the existing concepts. As a result, an appropriate amount of B is contained and the crystal structure is A
B-containing compounds that are 1B ₂ type (hereinafter, simply referred to as “AlB ₂ type B
The present invention has been completed by finding that the above object can be achieved satisfactorily by appropriately controlling the average size of the "containing compound") and the distribution ratio of the B-containing compound having a predetermined size.

According to the present invention, not only the rigidity can be increased without being restricted by the component system, but also the compound size and morphology can be easily controlled by the usual melt casting method. As a result, an Al alloy having improved machinability and plastic workability in addition to strength, toughness, wear resistance, etc. can be produced with high productivity.

In the Al alloy of the present invention, an appropriate amount of B is contained as described above, and among the B-containing compounds, particularly the average size of AlB ₂ type B-containing compounds and the distribution ratio of B-containing compounds of a predetermined size. Is properly controlled. First, the reason for defining these will be described.

B: more than 1.5 to 20% B forms a B-containing compound (particularly an AlB ₂ type B-containing compound), thereby increasing the rigidity of the Al alloy and increasing the strength and wear resistance. Is an effective element. Further, such a B-containing compound does not show a size change even during holding at high temperature, and exhibits the effect of stabilizing the rigidity during holding at high temperature. In order to exert these effects, it is necessary to contain more than 1.5%. However, if the B content becomes excessive and exceeds 20%, it becomes too hard and the machinability and plastic workability deteriorate. The preferable lower limit of B content is about 2%, and the preferable upper limit is 1%.
It is about 9%.

The average size of the AlB ₂ type B-containing compound is 2
The AlB ₂ type B-containing compound of 00 μm or less is a very hard compound and is an effective component for improving the strength and rigidity of the Al alloy with a small amount of dispersion. For example, the hardness of AlB ₂ is about 1500 to 2000 in terms of Vickers hardness Hv, and
The strength and rigidity are higher than those of the phase (Hv870 to 1350). Further, this AlB ₂ type B-containing compound is
Since it is a stable compound in which no size change is observed even during holding at high temperature, it brings about an effect of lowering the thermal expansion coefficient of the Al alloy. Due to these effects, not only a large amount of Si is contained but desired mechanical properties can be exerted, but also B can be obtained even in the usual melt casting method.
The morphology of the contained compound can be controlled.

In order to exert the above effects, the average size of the B-containing compound needs to be 200 μm or less. That is, when the average size of the B-containing compound exceeds 200 μm, the mechanical properties (especially ductility and rigidity) are rather deteriorated. The above B
The form of the containing compound is various such as lump, needle or plate, and the "average size of the B-containing compound" in the present invention means the longest dimension of the B-containing compound regardless of the plate thickness direction or the plate width direction. It means the average value.

AlB ₂ having a size of 50 μm or less
In the Al alloy of the present invention, the size distribution of the AlB ₂ -type B-containing compound needs to be in a finely divided state in order to ensure a high rigidity in the Al alloy of the present invention. From this point of view, the AlB ₂ type B-containing compound having a size of 50 μm or less needs to be 50% or more in terms of the number ratio with respect to the entire AlB ₂ type B-containing compound. That is, when the number ratio is less than 50%, the B-containing compound is not dispersed uniformly (the area of the matrix containing the B-containing compound is increased), and the effect of improving the rigidity cannot be obtained.

In the present invention, the B-containing material which is the subject of morphology control
Compound is AlB₂The reason is as follows.
Is the street. The B-containing compound in the Al alloy is A
LB ₂, AlB₁₂, TiB₂, CrB, FeB, B₂O₃,
B_FourIt is expected that various things such as C will be generated,
Of these, TiB₂, CrB, FeB, B₂O₃, B_FourIn C etc.
Is more likely to agglomerate by the usual melt casting method, which is preferable.
Not bad, AlB ₁₂Is a coarse compound,
It rather deteriorates plastic workability. On the other hand
AlB₂If it is a type B-containing compound, it will meet the above requirements.
By adding the above, it is not affected by other factors.
The effect will be exhibited.

The "AlB ₂ type B-containing compound" in the present invention exhibits the effect not only of the above AlB ₂ but also of the AlB ₂ type having the same crystal structure. , Si, Cu, Nb, Cr and the like containing a predetermined amount of components (for example, about 0.01 to 30 atomic%) are also included. In order to exert the above effects, the AlB ₂ type B-containing compound as described above is
It is preferable to control so as to be 80% or more of the B-containing compound.

The Al alloy of the present invention is basically assumed to be manufactured by a melt casting method (continuous casting, semi-continuous casting), but it can be manufactured by a powder metallurgy method, and any method can be used. Also, an Al alloy material that can be effectively used as a casting, a rolled material, and an extruded material can be obtained. However, the melting and casting method is advantageous in terms of the number of manufacturing steps and manufacturing costs, and the composition and solid solution state of the aluminum matrix alloy due to subsequent rolling, extrusion, heat treatment, etc.
It is preferable in that the precipitation state can be controlled and the overall characteristics are improved.

The B-containing compound in the present invention is formed by adding B to the molten Al alloy, and is also added to the molten Al alloy (or the molten Al) in the form of the compound containing B in the stage of the raw material powder. It may be the one obtained, and is not limited to its origin. The size of the B-containing compound is the size of the B powder particles in the raw material, the size of the raw material powder in the form of the compound in advance, the maximum dissolution temperature (that is, the dissolution holding temperature of the B-containing compound), the holding time, etc. (In case of melt casting)
Can be controlled by adjusting.

The above-mentioned maximum melting temperature is an important requirement for re-solidifying the B-containing compound to make it finer. The optimum range of the melting temperature varies depending on the B content and cannot be specified unconditionally, but generally, the higher the B content, the higher the temperature (for example, about 850 ° C. when the B content is 5%). Tend. However, B powder and B used as raw materials
The smaller the particle size of the contained compound powder, the lower the melting temperature can be controlled.

On the other hand, with respect to the holding time, the longer the time, the more easily the B-containing compound grows and the dispersion state of the fine particles tends to deteriorate, but in actual operation,
A certain amount of holding time is required for temperature rising time, component adjustment, degassing and other treatments. From this point of view, the holding time is preferably set within 30 minutes.

Under the above manufacturing conditions, AlB ₂
In order to control the content of the type B-containing compound to be 80% or more of the compound containing B, AlB should be previously prepared at the stage of raw material powder.
_When adding a type ₂ B-containing compound to the molten Al alloy (or molten Al), it may be adjusted at that stage, but when B is added to the molten Al alloy to form the compound containing B For example, B may be generated by raising it to a temperature at which B forms a solid solution with Al (for example, about 1200 to 1300 ° C.) and crystallizing it in the cooling process.

In the boron-containing Al alloy of the present invention,
It contains B as a basic component, and other components are not particularly limited, but as the Al alloy component system applicable in the present invention, each component system shown in the above (a) to (g) is used. (1000 to 7000 series compositions). In any of the component systems, the strength and rigidity can be increased by about 10% as compared with the case where B is not contained. The reason for setting the preferable range of each element in these component systems is as follows.

(A) 1000 system composition [B: Fe: 2
% Or less (including 0%) and / or Si: 2% or less
(Including 0%)] In the 1000 series composition, Fe and Si are Al-Fe series compounds in the Al alloy [for example, Al ₁₃ Fe and Al _m Fe.
(However, m is a positive integer) or the like, or various crystallized substances or precipitates of Al-Fe-Si-based compounds (for example, α-AlFeSi, etc.) are formed to improve the strength by refining the crystal grains. It has the effect of increasing the workability (workability, rolling, extruding, pulling out). Further, by containing Fe or Si, hardness and formability can be enhanced, and also by containing Si, corrosion resistance can be improved. However, F
From the standpoint of enhancing the electrical conductivity and the thermal conductivity of e and Si, it is preferable to increase the purity of Al by reducing the content of these components as much as possible. From these viewpoints, Fe and Si can each be contained up to 2% or less.

(B) 2000-based composition (in addition to B, Cu:
(Containing 1.5 to 7%) In the 2000 type composition, Cu is an element that contributes to hardening and increase in strength due to age precipitation. That is,
In an Al-Cu-based Al alloy, Cu is a θ-CuAl ₂ phase and a GP zone which is an intermediate layer and θ ′ in a series of precipitation processes of α → GP zone → θ′-CuAl ₂ phase → θ-CuAl ₂ phase. -Forms a CuAl ₂ phase and exerts hardening and strength increasing effects. In order to effectively exhibit such an action, the Cu content is preferably 1.5% or more.
The more preferable lower limit of the Cu content is about 1.6%,
More preferably, it should be 1.7% or more. On the other hand, C
If the u content becomes excessive and exceeds 7%, coarse precipitates are formed and the material becomes brittle. The more preferable upper limit of the Cu content is about 6.9%, further preferably 6.8%.
The following is good.

In this 2000 series composition, Mg: 1.8% or less (not including 0%), Mn:
1.2% or less (0% is not included), Cr: 0.4% or less (0% is not included), Zr: 0.3% or less (0% is not included), Zn: 0.5% or less It is also effective to contain one or more selected from the group consisting of (not containing 0%) and Ti: 0.3% or less (not containing 0%).

Of these, Mg is Al ₂ CuMg or Al ₁₆
Aging of a compound such as CuMg ₄ exhibits an effect of contributing to an increase in strength and hardness. Especially Cu
When the amount is small, the hardening effect of Mg becomes dominant. However, when the content of Mg exceeds 1.8%, a coarse compound is formed and becomes brittle. The more preferable upper limit of Mg is about 1.7%.

Further, Mn, Cr, Zr and Ti are elements for refining crystal grains to improve strength, ductility and toughness. These effects increase as the content increases, but if the content is excessive and exceeds the above range, a coarse compound is formed and becomes brittle. The more preferable upper limit of these is Mn: 1.1.
%, Cr: 0.3%, Zr: 0.2%, Ti: 0.2%
Is.

Furthermore, Zn contributes to the improvement of strength, but if the content of Zn exceeds 0.5% and becomes excessive, coarse A
The 1-Zn system or compound is formed and becomes brittle.
The more preferable upper limit of Zn content is 0.4%.

If necessary, this 2000 series composition has
Further, it is also effective to contain Fe: 2% or less (not including 0%) and / or Si: 2% or less (not including 0%). By containing these, 100
The same effect as the 0-based composition is obtained. In particular, Al alloy is M
When g is included, the inclusion of Si forms an aging precipitate such as Mg ₂ Si and contributes to the increase in hardness.

(C) 3000 series composition (in addition to B, Mn:
In the 3000 series composition, Mn is an element that exerts a solid solution hardening action and a work hardening action and contributes to an increase in strength. In order to exert such an effect, it is preferable to contain 0.3% or more, and more preferably 0.4% or more. However, if the content exceeds 2%, coarse precipitates are formed and the material becomes brittle. Incidentally, M
The upper limit more preferable than the n content is about 1.9%, more preferably 1.8% or less.

In this 3000 series composition, Mg: 1.8% or less (not including 0%), Cu:
0.6% or less (not including 0%) Cr: 0.4% or less (not including 0%), Zr: 0.3% or less (not including 0%), Zn: 0.5% (0 % Not included) and T
It is also effective to contain at least one selected from the group consisting of i: 0.3% or less (not including 0%).

Of these, Mg is an element effective for solid solution strengthening and contributing to hardening. These effects increase as the content increases, but the Mg content is 1.8.
If it exceeds%, a coarse compound is formed and becomes brittle.
The more preferable upper limit of Mg is about 1.7%.

Cu is an element that contributes to hardening by forming Al ₂ Cu, Al ₂ CuMg and the like. However, when the Cu content becomes excessive and exceeds 0.6%, A
The l ₂ CuMg becomes coarse and becomes brittle. The more preferable upper limit of Cu is about 0.5%.

Cr, Zr and Ti are elements that refine the crystal grains to improve strength, ductility and toughness.
These effects increase as the content increases, but if the content is excessive and exceeds the above range, a coarse compound is formed and becomes brittle. The more preferable upper limits of these are Cr: 0.3% and Zr: 0.2.
%, Ti: 0.2%.

Zn contributes to the improvement of strength, but if its content exceeds 0.5% and becomes excessive, coarse Al-Z is produced.
An n-based compound is formed and becomes brittle. The more preferable upper limit of Zn content is 0.4%.

Even in this 3000 series composition, the above 20
It is also effective to contain Fe: 2% or less (0% is not included) and / or Si: 2% or less (0% is not included), if necessary, similarly to the 00 system composition. By doing so, the same effect as the 2000-based composition can be obtained.

(D) 4000 series composition (in addition to B, Si:
2 to 16% included) In the 4000 series composition, Si is primary crystal Si and eutectic S
It is an element effective for forming i to increase the strength and improve the corrosion resistance. In order to exert such effects, it is preferable to contain 2% or more, more preferably 5%.
It is better to contain at least%. However, if the content exceeds 16%, the primary crystal Si is excessively coarsened up to near 80 μm and machinability, plastic workability, toughness and ductility are impaired.

In this 4000 series composition, Mg: 11% or less (not including 0%), Cu: 5 if necessary.
% Or less (not including 0%), Cr: 0.4% or less (0%
, Ni: 0.6% (0% is not included), M
n: 0.6% or less (not including 0%), Zr: 0.3%
Below (not including 0%), Zn: 0.5% (not including 0%), Ti: 0.3% or less (not including 0%) and Fe: 2% or less (not including 0%) It is also effective to contain one or more selected from the group consisting of

Of these, Mg is an element that contributes to solid solution strengthening and precipitation strengthening and is effective in improving strength and hardness. Such an effect increases as the content thereof increases, but if it exceeds 11% by excess, the corrosion resistance is adversely affected and the forgeability of the Al alloy deteriorates.

Cu is an element effective in increasing the yield strength and hardness by solid solution strengthening and improving the wear resistance and fatigue strength by aging treatment. Such an effect increases as the content thereof increases, but if the content is excessive and exceeds 5%, the forgeability and the corrosion resistance deteriorate.
The more preferable lower limit of Cu for exerting the above effect is 0.5%.

Ni is an element that forms a precipitate and is effective in improving heat resistance and seizure resistance as the content of Ni increases. Such an effect increases as the content thereof increases, but when the content exceeds 0.5%, a large amount of coarse needle-like precipitates are deposited, and the forgeability, strength, toughness, etc. are significantly reduced. Become.

Mn is an element effective for improving the fatigue strength by making the shape of Fe precipitates or Al-Fe-Si based precipitates spherical and fine, but if contained in excess of 0.5%. However, this will deteriorate the forgeability and toughness.

Fe forms precipitates similarly to Ni,
It is an element effective in improving heat resistance and seizure resistance with an increase in its content. Such an effect increases as its content increases, but becomes too much.
If it exceeds%, the nonuniformity of the structure will progress and the ductility and machinability will be impaired.

(E) 5000-based composition (in addition to B, Mg:
In a 5000-based composition, Mg exerts a solid solution strengthening action and a work hardening action, and is a useful element for increasing strength. In order to exert such an effect, Mg is 2
It is better to contain at least%. The more preferable lower limit of the Mg content is 3%, and more preferably 4% or more. However, when the Mg content becomes excessive, 8
If it exceeds%, the ductility is lowered, and cracks such as edge cracks and surface cracks occur, making it difficult to perform processing such as rolling. A more preferable upper limit of the Mg content is about 7%, and further preferably 6% or less.

In this 5000 series composition, Cu: 0.6% or less (not including 0%), Mn:
1% or less (not including 0%), Cr: 0.4% or less (0
%), Zr: 0.3% or less (0% is not included), Zn: 0.5% (0% is not included) and Ti:
It is also effective to contain one or more selected from the group consisting of 0.3% or less (not including 0%), and all of these are mechanical properties of the Al alloy (strength, ductility, toughness, hardness, etc.). Contribute to the improvement of.

Of these, Cu forms Al ₂ CuMg and contributes to hardening. Such an effect increases as the content thereof increases, but when the content is excessive and exceeds 0.6%, Al ₂ CuMg becomes coarse and becomes brittle. Cu
The preferable upper limit of the content is about 0.5%.

Mn, Cr, Zr and Ti are effective elements for refining crystal grains and improving strength and toughness. These effects increase as the respective contents increase, but if the contents are excessive and exceed the above range, a coarse compound is formed and becomes brittle. The more preferable upper limits of these elements are: Mn: 0.9%, Cr: 0.3%, Z
r: 0.2% and Ti: 0.2%.

Further, Zn is an element that contributes to the improvement of strength, and its effect increases as the content increases, but if it exceeds 0.5% and becomes excessive, coarse Al-Z is produced.
An n-type compound is formed and becomes brittle. In this 5000 series composition, the more preferable upper limit of Zn is about 0.4%.

Also in this 5000 series composition, Fe: less than 2% (not including 0%) and / or Si: less than 2% (0%) as necessary, as in the above 2000 series composition and 3000 series composition. It is also effective to include the above), and by containing these, the above 2
The same effect as the 000-based composition is obtained.

(F) 6000 series composition (in addition to B, Mg:
0.3-1.5% and Si: 0.3-1.5%
Existence) In the 6000 series composition, Mg and Si are Mg ₂ S
i is formed to contribute to curing. In order to exert such effects, it is preferable to contain each of them by 0.3% or more,
If it is less than this, the strength becomes insufficient. However, if both are excessively contained in excess of 1.5%, a coarse compound is formed and becomes brittle. The more preferable lower limit of these elements is 0.4%, and more preferably 0.5% or more. A more preferable upper limit is 1.4%, and a further preferable upper limit is 1.3%.

If necessary, the 6000 series composition has C
u: 0.6% or less (0% is not included), Mn: 1% or less (0% is not included), Cr: 0.4% or less (0% is not included), Zr: 0.3% or less (Not including 0%), Z
It is also effective to contain one or more selected from the group consisting of n: 0.5% (not including 0%), Ti: 0.3% or less (not including 0%) and Fe: 2% or less. Therefore, by containing these, the same effect as that of the 5000-based composition is exhibited.

(G) 7000-based composition (in addition to B, Mg:
1 to 4% and Zn: 0.8 to 8% included) In the 7000 series composition, Mg and Zn are Mg ₃ Z.
n ₃ Al ₂ or MgZn ₂ or its metastable phase η '
It is an element that contributes to curing by forming a compound such as a layer and is effective for exerting a strength improving action. That is, these elements are aged when subjected to a predetermined heat treatment (see Examples below), which results in 450 MPa.
The above tensile strength can be obtained.

In order to exert such effects, Mg
1% or more, and Zn is preferably 0.8% or more. More preferable lower limits are 1.1% for Mg and 0.1% for Zn.
9%, more preferably 1.2% or more in Mg, Zn
Therefore, it is better to set it to 1.0% or more. However, if these elements become excessive and Mg exceeds 4% and Zn exceeds 8%, not only coarse Al—Zn-based compounds are formed and they become brittle, but also stress corrosion cracking resistance decreases. . A more preferable upper limit is 3.9% for Mg, 7.9% for Zn, and further preferably 3.8% or less for Mg and 7.8% or less for Zn.

In this 7000 series composition, Cu: 3
% Or less (0% is not included), Mn: 1% or less (0% is not included), Cr: 0.4% or less (0% is not included), Z
r: 0.3% or less (not including 0%) and Ti: 0.
1 selected from the group consisting of 3% or less (not including 0%)
It is also effective to contain more than one species.

Of these, Cu is Al ₂ CuMg ₂ or Al ₂
It forms a compound such as Cu and contributes to curing. When the Cu content is 3% or less, these compounds are in solid solution, but when the Cu content is more than 3%, the supersaturation degree at high temperature becomes large when the age hardening heat treatment is performed, and a coarse compound is formed. It becomes easy to form. From this point of view, when Cu is contained, the content is preferably 3% or less, and more preferably 2.9% or less.

On the other hand, Mn, Cr, Zr, and Ti are effective elements for achieving the refinement of crystal grains and improving the strength, toughness, ductility, etc., as in the case of the 5000 series composition. Further, Mn, Cr, Zr and Ti are effective elements for refining crystal grains and improving strength and toughness. These effects increase as the respective contents increase, but when the contents are excessive and exceed the above range, a coarse compound is formed and becomes brittle. More preferable upper limits of these elements are Mn: 0.9%, Cr: 0.3%, Zr:
0.2% and Ti: 0.2%.

Also in this 7000-series composition, Fe: 2% or less (not including 0%) and / or Si: 2%, if necessary, as in the above 2000-series, 3000-series and 5000-series compositions. Below (not including 0%)
It is also effective to contain the above, and by containing these, the same effect as the 2000 type composition can be obtained.

In the Al alloys of the respective systems of the present invention, other than the above-mentioned components, they are substantially composed of Al. here,
“Substantially consisting of Al” means that a trace amount component may be contained in addition to Al, and a substance containing such a component is also included in the technical scope of the present invention. Examples of such trace components include permissible components such as P, Na, Sb, Sr, and Ni, and inevitable impurities such as V, Be, Ga, Sn, Ca, Sr, and Co.

The operation and effects of the present invention will be more specifically described below with reference to the examples, but the following examples are not of the nature limiting the present invention, and the design may be changed without departing from the spirit of the preceding and the following. Both are included in the technical scope of the present invention.

[0071]

[Example] An Al alloy ingot having each chemical composition shown in Tables 1 and 2 below was produced by a vacuum / melting casting method. At this time, in order to confirm the influence of the size distribution of the AlB ₂ type B-containing compound, the B-containing raw material having the particle size shown in Table 3 below was used, and the maximum melting temperature and the holding time were adjusted to obtain AlB ₂
The size of the type B containing compound was controlled. At this time, 13
It was melted in an Ar atmosphere of 3.3 Pa or less and cast in an ingot case in a vacuum to obtain an ingot. The detailed production conditions after casting were changed as follows according to each alloy system.

Detailed manufacturing conditions after casting of each Al alloy (1) No. 1 to 14 (1000 system composition) The surface of the above ingot was ground and then soaked (540
C.) and further hot rolling was performed at a starting temperature of 540 ° C. to manufacture a plate material having a thickness of 10 mm. (2) No. 15-18 (2000-based composition) The surface of the ingot is ground and then soaked (490
C., 24 hours), and further hot rolling was performed at a starting temperature of 450.degree. C. to manufacture a plate material having a thickness of 10 mm. Then T
6 treatments (1 hour solution treatment at 500 ° C and 180 ° C
Aging treatment for 10 hours). (3) No. 19-22 (3000 series composition) After soaking the surface of the ingot, soaking (570
C., 10 hours), and further hot rolling was performed at a starting temperature of 570.degree. C. to manufacture a plate material having a thickness of 10 mm. Then, an annealing treatment (200 ° C. for 1 hour) was performed. (4) No. 23 to 26 (4000 series composition) Casting to prepare a billet for extrusion, heating at 420 ° C for 1 hour, and extruding into a round bar having an outer diameter of 60 mm, then 48
After heating at 0 ° C. for 1 hour, it was cooled with water and quenched. afterwards,
Further, tempering was performed at 170 to 180 ° C. for 6 hours. (5) No. 27-30 (5000-based composition) After surface-polishing the above ingot, soaking (490
C., 24 hours) and further hot rolling was performed at a starting temperature of 500.degree. C. to manufacture a plate material having a thickness of 10 mm. Then T
4 treatments (solution treatment at 530 ° C for 1 hour and 150 ° C
For 2 hours). (6) No. 31-34 (6000 series composition) After soaking the surface of the ingot, soaking (550
C., 8 hours), and further hot rolling was performed at a starting temperature of 500.degree. C. to manufacture a plate material having a thickness of 10 mm. Then T6
A treatment (solution treatment at 530 ° C. for 1 hour and aging treatment at 180 ° C. for 24 hours) was performed. (7) No. 35-38 (7000 series composition) The surface of the ingot is ground and then soaked (480
C., 24 hours), and further hot rolling was performed at a starting temperature of 480 ° C. to manufacture a plate material having a thickness of 10 mm. Then T
6 treatments (1 hour solution treatment at 480 ° C and 180 ° C
24 hours of aging treatment).

[0073]

[Table 1]

[0074]

[Table 2]

[0075]

[Table 3]

The Al-based alloy sheet material thus obtained was investigated for the following items.

[Method for evaluating B-containing compound] (Preparation of sample) The aluminum alloy plate obtained above was polished to a thickness of about 0.05 to 0.1 mm with Emily paper, and then,
Buffing with roughness of 3 μm and 1 μm was performed. here,
OPU (made by Struers) was used as the buffing liquid. Using the plate sample thus prepared, the following compound dispersion state was observed and the characteristics of the Al alloy were evaluated.

(Confirmation of Form of B-Containing Compound) The presence of the form of the compound (AlB ₂ type) was confirmed by X-ray diffractometry.

(Dispersion of Intermetallic Compound) Using a field emission scanning electron microscope (“S4500 type FE-SEM”: manufactured by Hitachi Ltd.), 1000 times magnification, about 100 μm × 100.
It was observed in a visual field of about μm. At this time, it is preferable to observe with backscattered electrons because each intermetallic compound can be clearly observed, and thereby the existence state of the intermetallic compound at a level of about 0.05 μm or more can be observed.

(Identification of B-Containing Compound) SEM-EDX ("EMAX-7" attached to the above-mentioned field emission scanning electron microscope.
000 type EDX ": manufactured by HORIBA Ltd.)
The presence of B in the compound was confirmed.

(Analysis of Size, Distribution, and Number Ratio of B-Containing Compound) The image of the B-containing compound distribution observed as described above was evaluated by image analysis. The image analysis software at this time is "Image-Pro Plu
s ”(manufactured by MEDIA CYBERNETICS). The size ranges from several 0.01 μm level to several μm
However, as a range in which the characteristics of the alloy controlled by the present invention can be quantitatively defined, compounds having a minimum average size of 0.05 μm or more were analyzed. Therefore, the dispersity of the B-containing compound defined in the present invention is intended for the compound having a size not smaller than that which can be observed by the field emission scanning electron microscope.

(Measurement of Strength, Elongation and Rigidity) From the finally processed plate or extruded material, a tensile test piece (JIS
No. 13 test piece is cut out and subjected to a tensile test (JIS Z
2241) to measure room temperature strength and elongation. Moreover, the elastic modulus (rigidity) was measured from the tensile test.

(Measurement of linear expansion coefficient) The compression load test method was performed at room temperature at 50 to 300 ° C. (interval of 50 ° C.),
The coefficient of linear expansion was evaluated.

(Evaluation Method of Abrasion Resistance) Evaluation was carried out by a test using an Ogoshi type rotating disk. In this test, the surface of the test piece is rubbed while a predetermined load P is applied on the side surface of the rotating disk (counterpart material), and the wear resistance is evaluated by the specific wear amount. The conditions at this time are as follows. Counterpart material: Cast iron load P: 2.1 kg Friction speed V: 0.1 m / s

The results thus obtained are shown in Table 4 below.
5 collectively, as is clear from this result, a boron-containing Al alloy (N
o. 1-4,12,13,15,16,19,20,2
3,24,27,28,31,32,35,36)
It can be seen that various mechanical properties are improved in each case. On the other hand, an Al alloy lacking any of the requirements defined in the present invention (No. 5 to 11, 14, 17, 18, 2)
1, 22, 25, 26, 29, 30, 33, 34, 3
7, 38), it can be seen that one of the characteristics is not improved.

[0086]

[Table 4]

[0087]

[Table 5]

[0088]

EFFECTS OF THE INVENTION The present invention is constituted as described above, and it is possible to realize a high-rigidity Al alloy in which various mechanical properties are remarkably improved. Such a high-rigidity Al alloy replaces the conventional iron-based material, It can be applied as automobile engine parts and various sliding parts, and is extremely useful for weight reduction and performance improvement. Moreover, since the Al alloy of the present invention can be manufactured by the melt casting method in which the raw material is inexpensive and has excellent productivity, it can be manufactured at an extremely low cost as compared with the Al alloy obtained by the powder metallurgy method. There is also.

Claims (19)

[Claims] 1. B: more than 1.5 to 20% (meaning mass%,
The same applies to the following), and the average size of the B-containing compound having a crystal structure of AlB ₂ type is 200 μm or less, and the number ratio of the compound having a size of 50 μm or less to the entire AlB ₂ type B-containing compound is At 50%
A boron-containing high-rigidity Al alloy characterized by occupying the above. 2. The boron-containing high-rigidity A1 alloy according to claim 1, wherein the AlB ₂ type B-containing compound accounts for 80% or more of the total number of compounds containing B. 3. Fe: 2% or less (including 0%) and / or
Alternatively, the boron-containing high-rigidity A1 alloy according to claim 1 or 2, containing Si: 2% or less (including 0%), and the balance substantially consisting of Al. 4. The boron-containing high-rigidity A1 alloy according to claim 1 or 2, which contains Cu: 1.5 to 7% and the balance substantially consists of Al. 5. Further, Mg: 1.8% or less (not including 0%), Mn: 1.2% or less (not including 0%), C
r: 0.4% or less (not including 0%), Zr: 0.3%
Contains at least one selected from the group consisting of the following (not including 0%), Zn: 0.5% or less (not including 0%) and Ti: 0.3% or less (not including 0%). The high-rigidity boron-containing Al alloy according to claim 4, which is an alloy. 6. Fe: 2% or less (0% is not included) and / or Si: 2% or less (0% is not included)
The high-rigidity boron-containing Al alloy according to claim 4 or 5, which contains. 7. The boron-containing high-rigidity A1 alloy according to claim 1, wherein Mn: 0.3 to 2% is contained, and the balance substantially consists of Al. 8. Further, Mg: 1.8% or less (not including 0%), Cu: 0.6% or less (not including 0%) Cr:
0.4% or less (0% is not included), Zr: 0.3% or less (0% is not included), Zn: 0.5% (0% is not included) and Ti: 0.3% or less ( The high-rigidity boron-containing Al alloy according to claim 7, which contains at least one selected from the group consisting of (not including 0%). 9. Fe: 2% or less (not including 0%) and / or Si: 2% or less (not including 0%)
The high-rigidity boron-containing Al alloy according to claim 7 or 8, which contains. 10. The boron-containing high-rigidity A1 alloy according to claim 1 or 2, which contains Si: 2 to 16% and the balance substantially consists of Al. 11. Further, Mg: 11% or less (not including 0%), Cu: 5% or less (not including 0%), Cr:
0.4% or less (not including 0%), Ni: 0.6% (0
%), Mn: 0.6% or less (0% is not included), Zr: 0.3% or less (0% is not included), Zn:
0.5% (not including 0%), Ti: 0.3% or less (0
%) And Fe: 1% or more selected from the group consisting of 2% or less (not including 0%), and the boron-containing high-rigidity Al alloy according to claim 10. 12. The boron-containing high-rigidity A1 alloy according to claim 1 or 2, which contains Mg: 2 to 8% and the balance substantially consists of Al. 13. Cu: 0.6% or less (not including 0%), Mn: 1% or less (not including 0%), Cr:
0.4% or less (0% is not included), Zr: 0.3% or less (0% is not included), Zn: 0.5% (0% is not included) and Ti: 0.3% or less ( The boron-containing high-rigidity Al alloy according to claim 12, which contains at least one selected from the group consisting of (not including 0%). 14. Fe: 2% or less (not including 0%) and / or Si: 2% or less (not including 0%)
The high-rigidity boron-containing Al alloy according to claim 9 or 10, which contains. 15. Mg: 0.3-1.5% and Si:
The boron-containing high-rigidity A1 alloy according to claim 1 or 2, containing 0.3 to 1.5%, and the balance substantially consisting of Al. 16. Further, Cu: 0.6% or less (not including 0%), Mn: 1% or less (not including 0%), Cr:
0.4% or less (0% is not included), Zr: 0.3% or less (0% is not included), Zn: 0.5% (0% is not included), Ti: 0.3% or less ( 0% is not included) and F
e: The boron-containing high-rigidity Al alloy according to claim 15, containing at least one selected from the group consisting of 2% or less (not including 0%). 17. Mg: 1-4% and Zn: 0.8-
The boron-containing high-rigidity A1 alloy according to claim 1 or 2, containing 8% and the balance substantially consisting of Al. 18. Further, Cu: 3% or less (0% is not included), Mn: 1% or less (0% is not included), Cr: 0.
4% or less (not including 0%), Zr: 0.3% or less (0
%) And Ti: 0.3% or less (not including 0%), at least one selected from the group consisting of the high-rigidity boron-containing Al alloys according to claim 17. 19. Further, Fe: not more than 2% (not including 0%) and / or Si: not more than 2% (not including 0%).
The boron-containing high-rigidity Al alloy according to claim 17 or 18, which contains.