JPH09272941A - Aluminum base alloy fed to product forging through casting into product preliminary shape and casting and forging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the content of Si in the conventional Al alloy for casting and top reconcile the castability and forgeability therein by adding a specified amt. of Be to an Al base alloy having a specified compsn. contg. Si and Mg. SOLUTION: The molten metal of an Al base alloy contg., by weight, 2.0 to 3.3% Si, 0.2 to 0.7% Mg, 0.01 to 0.015% Be, and the balance Al is cast at <=180mm/sec molten metal rate in a spruce into a roughened material having a product predominate shape, and this raw material is forged into a product shape. By the addition of Be, the thickness of Al oxidized coating can be reduced to improve its forgeabiity. As result, not only in the case of casting products having a small-sized and simple shape but also in the case of casting products having a large-sized and complicates shape, surface defects such as flow marls and cold laps are not generated in the casting, and cracks are nor generated at the time of the subsequent forging, by which the product good in quality can be obtd. Furthermore, the above alloy may be incorporated with prescribed amounts of Ti and B, furthermore, one or more kinds among Cu, Mn, Cr and Zr, one more kinds among Na, Sr, Sb and Ca and P and Fe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention manufactures not only small-sized or simple-shaped parts made of aluminum-based alloys but also, for example, relatively large-sized or complicated-shaped automobile parts, aircraft parts, machine tool parts, agricultural machine parts and the like. The present invention relates to an aluminum-based alloy that is used for product forging after casting into a product preform and a casting and forging method thereof.

[0002]

2. Description of the Related Art Conventionally, as an aluminum alloy for casting, for example, AC having a Si content of 6.5 to 7.5% is used.
There is a 4CH alloy (JIS H 5202), and it is known as an alloy excellent in castability (melt flowability).

On the other hand, as an aluminum alloy for rolling or extrusion, for example, a 6061 alloy having a Si content of 0.4 to 0.8% (JIS H 4000, JIS H 4)
100) and is known as an alloy excellent in plastic workability (rollability, extrudability, forgeability, etc.).

In recent years, in order to make castability and forgeability compatible with this type of aluminum alloy, for example, S
Aluminum alloy with i content of 2.0 to 3.0% (Japanese Patent Application No. 3-189335) and Si content of 2.5
~ 4.0% aluminum alloy (JP-A-6-73)
482), an aluminum-based alloy having a Si content of 2.0 to 3.3% (JP-A-7-109536), and S.
Aluminum alloys having an i content of 3.3 to 5.5% (JP-A-7-109537) have been developed.

[0005]

However, in an aluminum-based alloy developed to achieve both such castability and forgeability, in order to improve the forgeability, the Si content in the aluminum alloy for casting should be controlled. Since the castability is less than that of aluminum alloys for casting such as AC4CH, for example, when casting large products or parts, or products with complex shapes or parts, defects in the molten metal pattern There is a problem that surface defects such as the above may occur.

Even if the surface defect has a depth of about 0.2 mm which cannot be detected by non-destructive inspection in the casting process, it progresses to cracks during the subsequent forging process. Since there is a problem that it may become a defective product, there is a problem to solve such a problem.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, in which the Si content is made smaller than that of a conventional aluminum alloy for casting, and castability and forgeability are improved. Using an aluminum-based alloy that is compatible with both as a material, not only small and simple shaped products or parts, but also large products or parts or complicated shaped products or parts It does not cause surface defects such as metal defects and molten metal defects, does not crack during the subsequent forging process of this cast product, and it is a large product or part with excellent shape accuracy and internal and external quality The object is to enable shaped products or parts to be produced by the cast forging process.

[0008]

The aluminum-based alloy that is subjected to product forging through casting into a product preform according to the present invention is, as described in claim 1, S% by weight.
i: 2.0 to 3.3%, and in some cases 2.7 to 3.0
%, Mg: 0.2 to 0.7%, and sometimes 0.
4 to 0.5%, Be: 0.001 to 0.015%, and in some cases 0.0015 to 0.0100%, and has a chemical composition of balance Al and impurities. I am trying.

In an embodiment of the aluminum-based alloy that is subjected to product forging through casting into a product preform according to the present invention, as described in claim 2, the component composition of claim 1 is obtained. In addition, Ti: 0.01-
0.20%, B: 0.0001 to 0.0100% may be contained. Further, as described in claim 3, in addition to the component composition of claim 1 or 2, Cu:
0.20 to 0.50%, Mn: 0.02 to 0.50%,
Cr: 0.01 to 0.50%, Zr: 0.01 to 0.2
It may contain one or more of 0%, and also as described in claim 4,
In addition to the composition of any one of claims 1 to 3, N
a: 0.001 to 0.010%, Sr: 0.001 to
0.050%, Sb: 0.05 to 0.15%, Ca:
One or more of 0.0005 to 0.0100% may be included, and P may be regulated to 0.001% or less. Further, as described in claim 5. In the component composition according to any one of claims 1 to 4, Fe: may be regulated to 0.15% or less.

Further, the casting and forging method of the aluminum-based alloy, which is used for the forging of the product through the casting into the preliminary shape of the product, according to the present invention, as set forth in claim 6,
1 to 5, the molten metal of the aluminum-based alloy to be forged by the product after being cast into the preliminary shape of the product is melted, and the melt speed of the sprue is 180 mm / sec or less (converted when the LPDC method is used. In this case, the filling speed of the molten metal is set to 0.010 kgf / cm ² · sec or less), the product is precast into a rough forging material having a preliminary shape, and then the forging rough material is forged into a product shape. .

[0011]

The aluminum alloy used in the forging of the product through the casting of the preliminary shape of the product according to the present invention has the above-mentioned chemical composition. The reason for limitation will be described.

Si: Si is used when casting a forging rough material having a shape corresponding to the product shape in consideration of the material flow at the time of forging of a cast forged product made of an aluminum alloy. It is an effective element for improving the fluidity and shrinkage of the aluminum-based alloy melt and preventing defects such as unfilled parts of the melt and casting cracks, and improves the flowability of the aluminum-based alloy melt. 2.0% in order to obtain good castability
Above, more desirably, it is contained by 2.7% or more.

However, if the Si content is too high, the forgeability at the time of forging the rough product for forging of the preliminary shape of the product is deteriorated, so 3.3% or less, more preferably 3.0%. It is less than.

Mg: Mg is an element useful for improving the mechanical strength such as tensile strength and proof stress by precipitating the compound Mg ₂ Si by heat treatment in the presence of Si.
The content is 0.2% or more, more preferably 0.4% or more.

However, if the Mg content is too high, mechanical properties such as elongation and impact value are deteriorated.
0.7% or less, more preferably 0.5% or less.

Be: In an aluminum-based alloy in which the castability and the forgeability are made compatible by setting the Si content to about 2.0 to 5.5%, the influence of the Be content on the thickness of the aluminum oxide film is influenced. When examined, the results are shown in FIG.

As shown in FIG. 1, when Be is not contained, the thickness of the aluminum oxide film is around 30 nm, while the Be content is 0.001% (10 pp).
m), the thickness of the aluminum oxide film decreases to around 17 nm, and the Be content is 0.0015.
% (15 ppm), it was confirmed that the thickness of the aluminum oxide film can be reduced to around 12 nm.

As described above, Be reduces the thickness of the oxide film of an aluminum alloy to about half, improves the castability (flowability of molten metal), and is used for forging in a preliminary shape of a product manufactured by casting. 0.001% or more because it is a useful element for preventing surface defects such as hot water pattern and boundary defects from occurring in the rough material and preventing cracks from occurring during the forging process for this rough material for forging. , More preferably 0.0015%
That is all.

However, if the Be content is too high, the surface texture of the forged rough material having a preformed product formed by casting is soiled, the yield strength increases but the elongation decreases, and the number of cavities increases. Therefore, the content is set to 0.015% or less, more preferably 0.0100% or less.

Further, since Be is an element that is most easily oxidized as compared with other constituent elements, strength is secured and yield is improved by suppressing the consumption of Mg, Sr, etc., which are easily consumed by oxidation in the melting / casting process. Since it has the effect of contributing to cost reduction by providing the improvement, Be is included in the above range.

Ti, B Ti and B have the effect of refining the cast structure of the aluminum alloy and are useful elements for improving the mechanical properties. Therefore, Ti is 0.01 %that's all,
It is also desirable in some cases to contain B in an amount of 0.0001% or more.

However, if the Ti and B contents become too large, the amount of inclusions precipitated will increase, rather reducing the mechanical properties.
20% or less and B must be 0.0100% or less.

Cu: Since Cu is an element useful for further improving the strength of the aluminum-based alloy, if necessary, it is also desirable to contain 0.20% or more. However, if Cu is contained in a large amount, the corrosion resistance is lowered.
It should be 50% or less.

Mn, Cr, Zr: Mn, Cr, Zr are elements useful for preventing recrystallization of the aluminum alloy during forging, so Mn is 0.02% or more, if necessary. Cr is 0.01% or more, Zr is 0.0
It is also desirable to contain 1% or more in some cases. However, if contained in a large amount, the hardness of the matrix increases and the workability is rather lowered. Therefore, even if contained, Mn is 0.50% or less and Cr is 0.50%.
Hereinafter, Zr needs to be 0.20% or less.

Na, Sr, Sb, Ca: Na, Sr, S
Since b and Ca are elements useful for refining eutectic Si in an aluminum-based alloy and improving mechanical properties such as elongation and impact value, Na is 0.1.
001% or more, Sr is 0.001% or more, Sb is 0.0
It is also desirable in some cases to contain 5% or more and Ca of 0.0005% or more. However, if these contents are too large, it tends to promote the absorption of gas and the formation of compounds and reduce the shrinkage of the molten metal. Therefore, even if they are contained, 0.010% or less of Na and Sr
Is 0.050% or less, and Sb is 0.15%.
%, And Ca needs to be 0.0100% or less.

P: The Na, Sr, Sb, Ca reacts with P in the molten aluminum alloy and does not act effectively on the refinement of eutectic Si. Therefore, it is one of Na, Sr, Sb, Ca. In the case of containing one kind or two or more kinds, it is desirable to regulate the P content to 0.001% or less so that the effect of refining eutectic Si can be effectively obtained.

Fe: Fe is an impurity mixed from the raw material, and if it is contained in a large amount, Fe-based intermetallic compounds are crystallized and the elongation is reduced, so it is desirable to regulate to 0.15% or less.

The aluminum alloy according to the present invention, which is used for product forging after casting into a product preform, has the above-described chemical composition, and the size of eutectic Si is 30 μm or less on average, Desirably, the thickness is 20 μm or less. That is, by making the eutectic Si fine, it is possible to further improve the plastic workability (forging workability) and to include it in the rough forging material that is formed by casting and has a preliminary shape of the product. Even if a slight forging process is performed by making the pores fine, the porosity can be significantly reduced, and a forged product of good quality can be obtained.

As described above, the aluminum-based alloy to be forged by the product according to the present invention after being cast into the product preform contains Be in order to suppress the aluminum oxide film and improve the castability. However, when Be is added to an aluminum-based alloy, the oxide film of aluminum becomes thin and easily breaks. Therefore, when turbulent flow occurs during casting, the oxide film is rolled into the aluminum and the strength is reduced. Is also concerned. Therefore, in the present invention, when casting the aluminum-based alloy melt, the melt speed of the gate is 180 mm /
It has been found that by setting the time to be not more than sec (in the LPDC method, the filling rate of the molten metal is not more than 0.010 kgf / cm ² · sec), such a concern can be eliminated and the strength can be prevented from being lowered.

That is, in the method for casting and forging an aluminum-based alloy according to the present invention, after the molten aluminum-based alloy having the above-described chemical composition is melted, the melt speed at the gate is set to 180 mm / sec or less. It is cast in a forging rough material having a product preliminary shape, and more preferably, the size of eutectic Si of the forging rough material having the product preliminary shape is 30 μm.
Hereafter, it is more desirable that the thickness is 20 μm or less, and then this rough forging material is forged into a product shape.

As described above, when the forging rough material having the preliminary shape of the product is formed by casting, the molten metal speed at the gate of the molten aluminum alloy is set to 180 mm / sec or less so that the oxide film of Be is formed. It becomes possible to suppress the mixture of the steel, and it is possible to significantly reduce the occurrence of forging cracks while preventing the deterioration of the actual strength.

[0032]

As described in claim 1, the aluminum-based alloy used for product forging after casting into the product preform according to the present invention has a Si content of 2.0:% by weight%.
3.3%, Mg: 0.2 to 0.7%, Be: 0.001
.About.0.015%, and the balance is Al and impurities. Therefore, it is possible to reduce the thickness of the aluminum oxide film by adding Be and improve the castability (melt flowability). As a result, it is possible to prevent defects such as molten metal patterns and boundary defects from occurring in the forging rough material that is the preform of the product manufactured by casting, and cracks occur during forging of this rough forging material. It is possible to prevent this from occurring, and it is possible to obtain a cast forged product with excellent shape accuracy and internal and external quality even when manufacturing large products or parts or complex shapes or parts. Great effect is brought about.

Then, as described in claim 2,
Ti: 0.01 to 0.20%, B: 0.0001 to 0.
By including 0100%, the casting structure of the aluminum-based alloy can be made finer, and the mechanical properties of the cast forged product can be further improved. As you can see, C
u: 0.20 to 0.50%, Mn: 0.02 to 0.50
%, Cr: 0.01 to 0.50%, Zr: 0.01 to
By including one or more of 0.20%, it becomes possible to further improve the mechanical properties of the cast forged product and prevent recrystallization from occurring during the forging process, As described in claim 4, Na: 0.001 to 0.010%, Sr: 0.00
1 to 0.050%, Sb: 0.05 to 0.15%, C
a: containing one or more of 0.0005 to 0.0100% and regulating P to 0.001% or less, the eutectic Si can be refined and the elongation can be improved. And mechanical properties such as impact value can be improved, and Fe:
By limiting the content to 0.15% or less, it is possible to prevent a decrease in elongation due to a large content of Fe, which is a remarkably excellent effect.

Further, according to the cast forging method of an aluminum alloy according to the present invention, as described in claim 6, product forging is performed through casting into the product preform according to any one of claims 1 to 5. After smelting the supplied aluminum alloy melt, the melt speed at the sprue is 180 mm / sec
Since it was cast into a rough product for forging of a product preliminary shape in the following, and then the rough material for forging was forged into a product shape,
The great effect that it is possible to manufacture a cast forged product excellent in shape accuracy and internal and external quality is brought about.

[0035]

EXAMPLE In this example, the molten aluminum alloys shown in Table 1 were melted.

[0036]

[Table 1]

Next, a cast product having a preliminary shape of a product (a rough material for forging having a preliminary shape of the product) is formed in consideration of the material flow at the time of forging with respect to the final shape of the disk of the aluminum road wheel which is the product. Using a casting mold having a mold cavity that can be obtained by casting, the casting position is such that the design surface of the disk is the lower mold, and the molten aluminum alloys shown in Table 1 above are individually listed in Table 2. Rough material for forging having a preliminary shape of the product was prepared by casting by filling the mold cavity at the molten metal speed (filling speed) shown in.

Subsequently, forgings (aluminum road wheels) having a predetermined product shape were manufactured by performing the forging process on the rough forging material having the above-mentioned product preliminary shape.

Next, the appearance quality of each forged product was examined, and the cracking occurrence rate for 100 products was examined. The results are also shown in Table 2.

Further, when an impact test was carried out on the road wheel 1 with an inclination angle θ of 13 ° as shown in FIG. 2, the results are also shown in Table 2.

[0041]

[Table 2]

As shown in Tables 1 and 2, molten metal No. which satisfies the chemical composition of the present invention. For aluminum alloys 1 to 8, the melt speed at the sprue is 180 mm / sec.
When the casting is performed within the range, it is possible to suppress the mixing of the oxide film of Be, so that it is possible to obtain an aluminum road wheel with a good impact test result, while the molten metal at the gate When the speed exceeds 180 mm / sec, it may not be possible to suppress the inclusion of Be oxide film, so the impact test result was a good or bad aluminum road wheel.

Further, in No. containing no Be. When the aluminum alloy of No. 9 is used, surface defects such as a hot water pattern or a hot water boundary may occur on the surface of the rough material for forging (that is, a cast product) having a preliminary shape of the product, and therefore, during the forging process. This was an aluminum road wheel that could crack and had poor impact characteristics.

[Brief description of drawings]

FIG. 1 is a graph showing the results of examining the relationship between the Be content and the oxide film thickness in a 2.9% Si-0.45% Mg-Al aluminum alloy.

FIG. 2 is an explanatory diagram showing a procedure of an impact test.

Claims (6)

[Claims] 1. An aluminum-based alloy that is subjected to forging of a product after being cast into a preform of the product, wherein the alloy contains S in weight%.
i: 2.0 to 3.3%, Mg: 0.2 to 0.7%, B
e: 0.001 to 0.015%, and the balance consisting of Al and impurities, an aluminum-based alloy that is subjected to forging of a product after being cast into a product preliminary shape. 2. Ti: 0.01 to 0.20%, B: 0.
An aluminum-based alloy that is subjected to product forging through casting into the product preform according to claim 1, containing 0001 to 0.0100%. 3. Cu: 0.20 to 0.50%, Mn:
0.02 to 0.50%, Cr: 0.01 to 0.50%,
Zr: An aluminum-based alloy that is subjected to forging of a product through casting into the product preliminary shape according to claim 1 or 2, containing one or more of 0.01 to 0.20%. 4. Na: 0.001-0.010%, S
r: 0.001 to 0.050%, Sb: 0.05 to 0.
15%, Ca: 0.0005 to 0.0100% of 1 type or 2 types or more, and P: 0.001% or less was controlled to the product preliminary shape according to any one of claims 1 to 3. Aluminum alloy used for product forging after casting. 5. An aluminum-based alloy that is used for forging a product after being cast into the preliminary shape of the product according to claim 1, wherein Fe: 0.15% or less. 6. A molten metal of an aluminum-based alloy used for product forging after casting into the product preliminary shape according to any one of claims 1 to 5, and then the melt speed of the gate is set to 1
A casting / forging method for an aluminum-based alloy, which comprises casting a rough product for forging having a preliminary shape of a product at 80 mm / sec or less, and then forging the rough product for forging into a product shape.