WO2018235272A1

WO2018235272A1 - Aluminum alloy and aluminum alloy casting

Info

Publication number: WO2018235272A1
Application number: PCT/JP2017/023240
Authority: WO
Inventors: 敦夫鏑木; 宮尻　聡; 大城　直人; 山田　毅
Original assignee: 株式会社大紀アルミニウム工業所; 株式会社シマノ
Priority date: 2017-06-23
Filing date: 2017-06-23
Publication date: 2018-12-27
Also published as: JPWO2018235272A1; CN110709526A; JP6267408B1; PH12019502327A1

Abstract

Provided are: an aluminum alloy with an extremely good balance of mechanical properties, especially tensile strength, elongation, 0.2% proof stress and hardness, that can be used for an increasing number of applications mainly in the field of transport equipment in general, and can be produced economically and sustainably using recycled starting materials such as scrap; and an aluminum alloy casting made from said alloy. That is, the present invention is: an aluminum alloy characterized in containing, in mass%, 0.75%≤Cu≤1.25%, 7.5%≤Si≤8.5%, 0.50%<Mg≤0.80%, 0.20%≤Fe≤0.50%, 0.30%≤Mn≤0.50%, and 0.10%≤Cr≤0.30%, the balance being made of Al and unavoidable impurities; and an aluminum alloy casting thereof.

Description

Aluminum alloy and aluminum alloy cast article

The present invention relates to an aluminum alloy excellent in mechanical properties and an aluminum alloy cast article using the alloy.

Weight reduction is required in all transport devices such as bicycles and automobiles, and the application of aluminum alloy cast articles is expanding. Conventionally, JIS ADC 3 alloy has been widely used for this type of application, but with the spread of such application, applications in which mechanical properties can not be satisfied with this conventional material have become apparent.

Then, in order to correspond to the use which conventional materials such as JIS ADC 3 alloy can not cope with, for example, the following Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-27169) has improved mechanical strength and toughness. As an aluminum alloy, 8.5 to 9.5% of Si, 0.20% or less of Cu, 0.20 to 0.40% of Mg, and 0.6% or less of Fe on a weight basis .30 to 0.50% of Mn, 0.05 to 0.15% of Ti, 0.01 to 0.025% of Sr, and 0.15% or less of Zn, the balance being Al An aluminum alloy is disclosed.
According to this technology, it is believed that an aluminum alloy having high strength and high toughness can be provided so that it can withstand breakage even in a severe use environment (than the use environment of conventional materials).

Unexamined-Japanese-Patent No. 2003-27169

However, if Cu is treated as an impurity in order to maintain the corrosion resistance of the alloy and the content thereof is limited to 0.20% or less as described above, the use of scrap material becomes substantially impossible, and the aluminum alloy is economically In addition to being unable to manufacture, it is also the rate-limiting factor in constructing a recycling society. In addition, Cu has the effect of improving mechanical properties such as tensile strength and 0.2% proof stress with respect to aluminum alloy, but if the content ratio of Cu is limited to 0.20% or less, Such effects are also limited.
Therefore, the present invention is an aluminum alloy capable of balancing mechanical properties, in particular tensile strength, elongation, 0.2% proof stress and hardness at a high level, and also for expanding applications mainly in transport equipment generally. It is an object of the present invention to provide an aluminum alloy that can be economically and sustainably produced using recycled raw materials such as scrap, and an aluminum alloy cast article made of the alloy.

According to a first aspect of the present invention, “% by weight, 0.75% ≦ Cu ≦ 1.25%, 7.5% ≦ Si ≦ 8.5%, 0.50% <Mg ≦ 0.80%, 0.20% ≦ Fe ≦ 0.50%, 0.30% ≦ Mn ≦ 0.50%, 0.10% ≦ Cr ≦ 0.30%, and the balance consists of Al and unavoidable impurities ” Is an aluminum alloy characterized by

In the present invention, Cu is contained in the range of 0.75% by weight or more and 1.25% by weight or less, and Mg is also contained in the range of more than 0.50% by weight to 0.80% by weight or less Not only is it possible to use recycled materials such as scrap, but it is also possible to improve mechanical properties such as tensile strength, 0.2% proof stress and hardness. Moreover, while suppressing the content ratio of Cu which may deteriorate the corrosion resistance within the above range, Cr containing 0.10% by weight or more and 0.30% by weight or less of the effect of improving the corrosion resistance is contained. It is possible to minimize the deterioration of the corrosion resistance of the aluminum alloy caused by the inclusion of Cu.
As described above, in the present invention, the ingot of an aluminum alloy excellent in castability and mechanical properties is recycled mainly by containing the above six types of elemental components in a predetermined ratio, and their interaction with each other. It can be economically and simply manufactured using raw materials.

In the aluminum alloy of the present invention, it is preferable to further contain 0.30% by weight or less of Ti based on the total weight of the alloy. By so doing, the crystal grains of the alloy can be refined to suppress casting cracks more effectively, and mechanical properties, in particular, elongation can be improved.

Further, in the aluminum alloy of the present invention, at least one selected from Na, Sr and Ca is further added so as to be 30 to 200 ppm with respect to the total weight of the alloy, or Sb relative to the total weight of the alloy It is preferable to add so as to be 0.05 to 0.20% by weight. By so doing, particles of eutectic Si can be made finer, and the toughness and strength of the aluminum alloy can be further improved.
Furthermore, it is also preferable to add B to 1 to 50 ppm with respect to the weight of the entire alloy. By so doing, the crystal grains of the aluminum alloy can be made finer even if the amount of Si is small or the casting method with a slow cooling rate is used, and as a result, the elongation of the aluminum alloy is improved. Can.

A second invention of the present invention is an aluminum alloy cast article comprising the aluminum alloy according to the first invention.
The aluminum alloy cast article comprising the aluminum alloy of the present invention can be mass-produced with good castability, and because mechanical characteristics, especially tensile strength, elongation, 0.2% proof stress and hardness are balanced at high dimensions, for example It can be suitably used in new applications of cast articles that require weight reduction in general transportation equipment where the application of aluminum alloy cast articles is expanding.

According to the present invention, it is an aluminum alloy capable of balancing mechanical properties, in particular tensile strength, elongation, 0.2% proof stress and hardness at a high level, and also for expanding applications mainly in transport equipment generally, It is possible to provide an aluminum alloy that can be economically and sustainably produced using recycled raw materials such as scrap, and an aluminum alloy cast article made of the alloy.

It is a graph which shows the relationship between the content rate of Cu, and each aluminum alloy physical property of non-heat processing. It is a graph which shows the relationship between the content rate of Cu, and each aluminum alloy physical property after T6 process.

Hereinafter, embodiments of the present invention will be described in detail by way of specific examples.
The aluminum alloy of the present invention is, by weight, 0.75% ≦ Cu ≦ 1.25%, 7.5% ≦ Si ≦ 8.5%, 0.50% <Mg ≦ 0.80%, 0.20 It contains% ≦ Fe ≦ 0.50%, 0.30% ≦ Mn ≦ 0.50%, 0.10% ≦ Cr ≦ 0.30%, and the balance is roughly constituted by Al and unavoidable impurities. The characteristics of each element will be described below.

Cu (copper) is an important element for improving the wear resistance, mechanical strength and hardness of aluminum alloys.
The content of Cu relative to the weight of the entire aluminum alloy is preferably in the range of 0.75% by weight or more and 1.25% by weight or less as described above. If the content ratio of Cu is less than 0.75% by weight, the above-mentioned mechanical property improvement effect can not be obtained, and conversely, if the content ratio of Cu exceeds 1.25% by weight, the main In the T6 treated material (details will be described later), the tensile strength and the elongation become insufficient.

Si (silicon) is an important element which secures the fluidity at the time of aluminum alloy melting and improves the castability.
The content of Si relative to the weight of the entire aluminum alloy is preferably in the range of 7.5% by weight or more and 8.5% by weight or less as described above. When the content ratio of Si is less than 7.5% by weight, it is difficult to secure the fluidity of the molten metal, and in the case of forming by ordinary die casting generally used widely as the casting method, it is large Application to parts is hindered, and conversely, when the content of Si exceeds 8.5% by weight, the castability is improved but the elongation of the alloy is significantly reduced.

Mg (magnesium) mainly exists as a solid solution in an Al base material in an aluminum alloy or exists as Mg ₂ Si and imparts yield strength and hardness to the aluminum alloy while elongation is significantly reduced by the inclusion of an excessive amount Together with castability and corrosion resistance.
The content ratio of Mg to the weight of the entire aluminum alloy is preferably in the range of more than 0.50% by weight and 0.80% by weight or less as described above. When the content ratio of Mg is 0.5% by weight or less, it becomes possible to secure 0.2% proof stress and hardness of the alloy regardless of the presence or absence of heat treatment, while the content ratio of Mg is 0.8 If it exceeds the weight percent, the elongation of the alloy will be significantly reduced.

Fe (iron) is known to have an effect of preventing seizing of a mold when casting, for example, die casting. However, this Fe crystallizes needle-like crystals consisting of Al-Si-Fe and lowers the toughness (elongation) of the aluminum alloy, and when added in large amounts, makes it difficult to melt at an appropriate temperature.
The content ratio of Fe with respect to the weight of the entire aluminum alloy is preferably 0.20% by weight or more, as described above, in consideration of using a recycled material such as scrap for a part of the material from the viewpoint of recycling. On the other hand, if the Fe content ratio is too high, as described above, needle crystals consisting of Al-Si-Fe crystallize and the elongation of the alloy decreases, so the upper limit is 0.50% by weight as described above It is preferable that it is the following.

Mn (manganese) is mainly for preventing seizing between an aluminum alloy and a mold at the time of casting such as die casting, as in the case of Fe described above. Similarly to Fe, if this Mn is contained in a large amount, it becomes difficult to melt at an appropriate temperature. Therefore, in the present invention, the upper limit of the content ratio of Mn to the weight of the entire aluminum alloy is suppressed to 0.50 wt% or less There is.
The lower limit of the content of Mn is preferably 0.30% by weight or more, as described above, in order to exert the above-mentioned anti-seizure effect remarkably.

Cr (chromium) is an element having an effect of improving the corrosion resistance of the alloy in addition to preventing the seizure between the aluminum alloy and the mold at the time of casting such as die casting, similarly to Fe and Mn described above.
The content of Cr relative to the weight of the entire aluminum alloy is preferably in the range of 0.10% by weight or more and 0.30% by weight or less as described above. If the content ratio of Cr is less than 0.10% by weight, the above-mentioned effects can not be sufficiently obtained, and conversely, if the content ratio of Cr exceeds 0.30% by weight, it is added more Even if the amount is increased, the addition effect can not be improved.

According to the above content ratio, adjusting the content ratio of Cu, Si, Mg, Fe, Mn and Cr, the mechanical properties, especially tensile strength, elongation, 0.2% proof stress and hardness were balanced with high dimension Aluminum alloys can be economically and sustainably produced using recycled materials.

Note that Ti (titanium) may be added in addition to each of the above-described element components. This Ti has an effect of refining crystal grains, and is generally an element which can particularly improve elongation among suppression of casting cracks and mechanical properties.
The content of Ti with respect to the weight of the entire aluminum alloy is preferably in the range of 0.30% by weight or less. When the content ratio of Ti exceeds 0.30% by weight, it is difficult to melt the aluminum alloy, and there is a possibility that the unmelted portion is generated.

Further, in addition to the above-described respective element components, at least one selected from Na (sodium), Sr (strontium), Ca (calcium) and Sb (antimony) may be added as the improvement treatment material. By adding such an improvement treatment material, particles of eutectic Si can be made finer, and the toughness and strength of the aluminum alloy can be further improved.
Here, the addition ratio of the improved material to the total weight of the aluminum alloy is 30 to 200 ppm when the improved material is Na, Sr and Ca, and 0.05 to 0.20% by weight when Sb is used. It is preferable that it is a range. If the addition ratio of the improvement treatment material is less than 30 ppm (0.05% by weight in the case of Sb), it becomes difficult to refine the particles of eutectic Si in the aluminum alloy, conversely, the improvement treatment material In the case where the addition ratio of is greater than 200 ppm (0.20% by weight in the case of Sb), the particles of eutectic Si in the aluminum alloy are sufficiently finely divided, and addition is possible even if the addition amount is further increased It is because the effect does not rise.

Further, B (boron) may be added instead of the above-mentioned improved treatment material or together with the improvement treatment material. By adding B in this manner, the crystal grains of the aluminum alloy can be refined, and the elongation of the alloy can be improved. Such an effect is particularly remarkable when the amount of Si is small or when a casting method with a slow cooling rate is used.
The proportion of B added to the total weight of the aluminum alloy is preferably in the range of 1 to 50 ppm. When the addition ratio of B is less than 1 ppm, it is difficult to refine the crystal grains in the aluminum alloy, and conversely, when the addition ratio of B is more than 50 ppm, the crystal grains in the aluminum alloy are sufficient. The effect of addition is not improved even if the amount of addition is further increased.

In the production of the aluminum alloy of the present invention, first, raw materials are prepared in which the respective elemental components of Al, Cu, Si, Mg, Fe, Mn, and Cr are in the above-described predetermined ratio (necessary In accordance with the above, Ti and modified materials are added. Subsequently, the raw material is put into a melting furnace such as a forging furnace-containing melting furnace or a closed melting furnace to melt these materials. The molten raw material thus melted, that is, the molten metal of the aluminum alloy, is subjected to a purification treatment such as dehydrogenation treatment and removal treatment, if necessary. Then, the refined molten metal is poured into a predetermined mold or the like and solidified to form a molten metal of an aluminum alloy into an alloy base metal ingot or the like.

In addition, after casting an aluminum alloy cast article by various casting methods such as die casting method such as die casting and gravity casting, sand casting method or precision casting method using the aluminum alloy of the present invention, if necessary Solution treatment, aging treatment, etc. are performed. Thus, the mechanical properties of the aluminum alloy cast article can be improved by subjecting the aluminum alloy cast article to solution treatment, aging treatment and the like.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples.
Among the mechanical properties of the various alloys described below, tensile strength, elongation and 0.2% proof stress were measured by the following methods. That is, using an ordinary die casting machine with a clamping force of 135 tons (DC 135EL manufactured by Toshiba Machine Co., Ltd.), die casting is performed at an injection speed of 1.0 m / s and a casting pressure of 60 MPa. ASTM (American Society for Testing and Material) Round bar test piece conforming to the standard was prepared. And, with regard to the as-cast condition and the round bar test piece after T6 treatment, using a universal testing machine (AG-IS 100 kN) manufactured by Shimadzu Corp., tensile strength, elongation, 0.2% proof stress Was measured. Here, the T6 treatment is a heat treatment method in which reheating and artificial aging treatment are performed after the solution treatment. In this example, after heating at 510 ° C. for 3 hours as this T6 treatment, it was water cooled (solution treatment), and further heated at 180 ° C. for 3 hours, then air cooled (artificial aging treatment).
The hardness was evaluated by the Rockwell hardness test according to Japanese Industrial Standard JIS G0202. That is, after cutting 1 mm of the surface of a flat plate specimen cast under the same conditions as described above, the polished plate was tested with a Rockwell hardness tester. The measurement with this tester was performed three times, and the average value was taken as the measurement value of the Rockwell hardness test.
Further, alloy components of various alloys were measured using a solid state emission spectrometer (Thermo Scientific ARL 4460 manufactured by Thermo Fisher Scientific Co., Ltd.).

Influence of Cu on Aluminum Alloy Physical Properties Table 1 shows the composition of an aluminum alloy manufactured by adjusting the alloy components other than Cu to a certain ratio within the scope of the present invention and changing the content ratio of Cu. And the mechanical properties (tensile strength, elongation, 0.2% proof stress and hardness).

As shown in Table 1 and FIGS. 1 and 2, when the Cu content of the aluminum alloy is 0.75% by weight or more, mechanical properties, in particular, tensile strength, elongation, 0.2% proof stress and hardness, are obtained. It is possible to obtain sufficient tensile strength to achieve balance in high dimensions, and up to 1.25% by weight, the tensile strength improves as the content of both non-heat-treated and T6 treated materials increases. I can see you. And in T6 processing material, when the content rate of Cu exceeds 1.25 weight%, tensile strength comes to fall. Such a tendency can be overcome with 0.2% proof stress and hardness.
On the other hand, the elongation of the alloy gradually decreases as the content of Cu increases, and in particular, when the content of Cu exceeds 1.25% by weight, the elongation becomes less than 5.0% in the T6 treated material. It is difficult to say that it is excellent in growth.
For this reason, in the aluminum alloy of the present invention, the content of Cu is in the range of 0.75% by weight or more and 1.25% by weight or less.
Alloys 1 and 2 in Table 1 are alloy compositions within the scope of the present invention, ie, example alloys, and alloy 9 is a JIS ADC 3 alloy representing a conventional material.

Influence of Mg on Aluminum Alloy Physical Properties Table 2 shows the composition of the aluminum alloy manufactured by adjusting the alloy components other than Mg to a certain ratio within the range of the present invention and changing the content ratio of Mg. And the mechanical properties (tensile strength, elongation, 0.2% proof stress and hardness).

As Table 2 shows, when an alloy 10 containing 0.29% by weight of Mg and an alloy 1 and 2 containing 0.66% by weight of Mg in the aluminum alloy are compared, when the content of Mg is high, The elongation is reduced while the 0.2% proof stress and hardness of the alloy is improved. Therefore, in the aluminum alloy of the present invention, as described above, the content ratio of Mg is set in the range of more than 0.50% by weight and 0.80% by weight or less in consideration of the balance with other element components. .
Alloys 1 and 2 in Table 2 are alloy compositions within the scope of the present invention, ie, example alloys.

According to the aluminum alloy of the present embodiment, Cu is contained in the range of 0.75% by weight or more and 1.25% by weight or less, and Mg is also more than 0.50% by weight or more and 0.80% by weight or less Since it is contained in the range, not only the use of recycled raw materials such as scraps becomes possible, but also mechanical properties such as tensile strength, 0.2% proof stress and hardness can be improved. Moreover, while suppressing the content ratio of Cu which may deteriorate the corrosion resistance within the above range, Cr containing 0.10% by weight or more and 0.30% by weight or less of the effect of improving the corrosion resistance is contained. It is possible to minimize the deterioration of the corrosion resistance of the aluminum alloy caused by the inclusion of Cu.

Claims

% By weight, 0.75% ≦ Cu ≦ 1.25%, 7.5% ≦ Si ≦ 8.5%, 0.50% <Mg ≦ 0.80%, 0.20% ≦ Fe ≦ 0.50 %, 0.30% ≦ Mn ≦ 0.50%, 0.10% ≦ Cr ≦ 0.30%, and the balance is made of Al and unavoidable impurities.
In the aluminum alloy of claim 1,
An aluminum alloy characterized by further containing 0.30% by weight or less of Ti based on the weight of the entire alloy.
In the aluminum alloy of claim 1 or 2,
Furthermore, an aluminum alloy characterized in that at least one selected from Na, Sr and Ca is added so as to be 30 to 200 ppm with respect to the total weight of the alloy.
In the aluminum alloy according to any one of claims 1 to 3,
Furthermore, Sb is added so as to be 0.05 to 0.20% by weight with respect to the total weight of the alloy.
In the aluminum alloy according to any one of claims 1 to 4,
Furthermore, B is added so as to be 1 to 50 ppm with respect to the weight of the entire alloy.
An aluminum alloy cast article comprising the aluminum alloy according to any one of claims 1 to 5.