Aluminum alloy and cast product

Abstract

Provided are an aluminum alloy and a cast product, with which it is possible to improve rigidity and ensure fluidity of molten metal during casting. This aluminum alloy contains Cu, Si, Mg, Mn, Fe, Ni, Ti, and P, and the remainder is Al and impurities. The element content ratios are 6.9-10.1 wt% of Cu, 16.0-18.0 wt% of Si, 0.4-0.7 wt% of Mg, 1.5-2.1 wt% of Mn, 1.0-2.1 wt% of Fe, 2.0-3.0 wt% of Ni, 0.15-0.20 wt% of Ti, and 0.01-0.015 wt% of P. This cast product is obtained by casting the aluminum alloy.

Description

Aluminum alloys and castings

[0001] The present invention relates to aluminum alloys and castings.

[0002] Cast iron is used in some casting parts that require high rigidity. In recent years, market demand has led to a demand for high-rigidity, lightweight aluminum alloys to replace cast iron.

[0003] However, aluminum alloy castings AC4A and AC4C specified in JIS H5202:2010 have good castability but do not satisfy the required rigidity due to their low Young's modulus. Furthermore, the aluminum alloy described in Patent Document 1 aims to improve high-temperature strength (tensile strength at high temperatures), but does not necessarily ensure a high Young's modulus and therefore does not necessarily satisfy the required rigidity. Aluminum alloy castings AC9A and AC9B specified in the same JIS have higher Young's modulus than AC4A and AC4C and approach the required rigidity, but the flow of molten metal is hindered by coarsening of primary Si, leaving room for improvement in the fluidity (flowability) of the molten metal.

[0004] Japanese Patent Application Publication No. 09-272939

[0005] The above-mentioned conventional aluminum alloys have the problem that they are unable to increase rigidity and improve the fluidity of the molten metal during casting.

[0006] The present invention has been made to solve this problem, and an object of the present invention is to provide an aluminum alloy and a cast product which have improved rigidity and which can ensure the fluidity of the molten metal during casting.

[0007] To achieve this object, a first aspect of the present invention is an aluminum alloy comprising Cu, Si, Mg, Mn, Fe, Ni, Ti, and P, with the remainder being Al and impurities, with the element contents being 6.9-10.1 wt% Cu, 16.0-18.0 wt% Si, 0.4-0.7 wt% Mg, 1.5-2.1 wt% Mn, 1.0-2.1 wt% Fe, 2.0-3.0 wt% Ni, 0.15-0.20 wt% Ti, and 0.01-0.015 wt% P.

[0008] In a second aspect, in the first aspect, the value obtained by dividing the Fe content by the Si content is 0.061 or more.

[0009] A third aspect is the first or second aspect, further comprising 1.1 to 1.5 wt % of Zn.

[0010] A fourth aspect is any one of the first to third aspects, further comprising 0.15 to 0.20 wt % Be.

[0011] A fifth aspect is a casting obtained by casting the aluminum alloy according to any one of the first to fourth aspects.

[0012] According to the first aspect, the alloy contains 1.5 to 2.1 wt% Mn, which improves the rigidity of the casting obtained by casting through solid solution hardening of Mn. Furthermore, the alloy contains 16.0 to 18.0 wt% Si and 1.0 to 2.1 wt% Fe, which reacts with Si to form Al-Fe-Si intermetallic compounds, contributing to dispersion strengthening. As a result, the rigidity of the casting can be improved.

[0013] The Cu content (6.9 to 10.1 wt%) is considered to be a necessary and sufficient content for improving the rigidity of the casting by solid solution hardening of Cu. Therefore, compared to when the Cu content is higher than this, it is possible to include more Al, which allows the casting to be lighter while improving its rigidity.

[0014] In addition, since it contains 0.15 to 0.20 wt% of Ti, TiAl ３ The formation of heterogeneous nuclei during solidification of the alloy refines the crystal grains, improving the rigidity of the cast product and the fluidity of the molten metal during casting. Furthermore, the alloy contains 0.01 to 0.015 wt% of P, which refines the crystal grains and ensures the fluidity of the molten metal. As a result, the rigidity of the cast product can be improved and the fluidity of the molten metal can be ensured.

[0015] According to the second aspect, since the value obtained by dividing the Fe content by the Si content is 0.061 or more, the Fe content relative to the Si content can be made to be a certain level or more. Therefore, it is possible to generate a certain amount or more of Al-Fe-Si intermetallic compounds. As a result, the rigidity of the casting can be improved.

[0016] According to the third aspect, since the alloy further contains 1.1 to 1.5 wt % of Zn, the fluidity of the molten metal can be improved.

[0017] According to the fourth aspect, since the alloy further contains 0.15 to 0.20 wt % of Be, the crystal grains can be made finer, and the rigidity of the casting and the fluidity of the molten metal during casting can be improved.

[0018] According to the fifth aspect, the rigidity can be improved and the fluidity of the molten metal during casting can be ensured, thereby providing an aluminum alloy casting having better fluidity (castability) during casting than AC9A and AC9B and higher rigidity than AC4A and AC4C.

[0019] Preferred embodiments of the present invention will be described below. The aluminum alloy in one embodiment of the present invention contains 6.9 to 10.1 wt% Cu (copper), 16.0 to 18.0 wt% Si (silicon), 0.4 to 0.7 wt% Mg (magnesium), 1.5 to 2.1 wt% Mn (manganese), 1.0 to 2.1 wt% Fe (iron), 2.0 to 3.0 wt% Ni (nickel), 0.15 to 0.20 wt% Ti (titanium), 0.01 to 0.015 wt% P (phosphorus), and 1.5 wt% or less Zn (zinc), with the remainder being Al (aluminum) and impurities. The aluminum alloy has good rigidity when cast and good fluidity when cast.

[0020] Each content value described in this specification is a meaningful number that omits zeros that merely indicate the place value among the numbers that represent measurement results, etc., in accordance with the significant figures specified in JIS K0211:2013. That is, for example, 1.0 wt% represents 0.95 wt% or more and less than 1.05 wt%, and 2.01 wt% represents 2.005 wt% or more and less than 2.015 wt%.

[0021] A casting according to one embodiment of the present invention is a casting obtained by casting the aluminum alloy. The casting can be used as a component of a machine tool that requires high rigidity. The casting may be used, for example, as floor components or structural components made of aluminum alloy, in addition to components that constitute machine tools. In these cases, the casting can be used in place of existing floor components or structural components made of aluminum alloy that are thick to ensure rigidity, thereby enabling the components to be thinner and lighter.

[0022] Cu is contained in the aluminum alloy in the range of 6.9 to 10.1 wt%, and has the effect of improving rigidity through solid solution hardening of Cu. If the Cu content is less than 6.9 wt%, the effect of improving rigidity through solid solution hardening cannot be obtained sufficiently, and if the Cu content is more than 10.1 wt%, the proportion of Cu, which has a large specific gravity relative to Al, increases, hindering weight reduction.

[0023] Si, contained in the aluminum alloy in the range of 16.0 to 18.0 wt%, has the effect of improving fluidity, shrinkage, and hot cracking resistance, and also has the effect of suppressing the thermal expansion coefficient. Si also reacts with Fe to form Al-Fe-Si intermetallic compounds, contributing to dispersion strengthening and improving rigidity. If the Si content is less than 16.0 wt%, the effect of improving fluidity, shrinkage, and hot cracking resistance is not sufficient, while if the Si content is more than 18.0 wt%, the needle-like portions of the Al-Fe-Mn intermetallic compounds become coarse, reducing rigidity.

[0024] Mg is contained in the aluminum alloy in the range of 0.4 to 0.7 wt%, and has the effect of improving rigidity through solid solution hardening of Mg. If the Mg content is less than 0.4 wt%, the effect of improving rigidity through solid solution hardening cannot be sufficiently obtained, and if the Mg content is more than 0.7 wt%, the fluidity and replenishment properties of the molten metal are reduced.

[0025] Mn is contained in aluminum alloys in the range of 1.5 to 2.1 wt% and has the effect of improving rigidity through solid solution hardening of Mn. If the Mn content is less than 1.5 wt%, the kanji-shaped crystallization of Al-Fe-Si intermetallic compounds is slowed, reducing the ease of molten metal supply, while if the Mn content is more than 2.1 wt%, Al-Fe-Mn-Si or Al-Fe-Mn-Cr-Si intermetallic compounds are formed, causing hard spots that can cause tool damage when machining the casting, such as cutting.

[0026] Fe is contained in the aluminum alloy in the range of 1.0 to 2.1 wt%, and reacts with Si to form Al-Fe-Si intermetallic compounds, contributing to dispersion strengthening and thereby improving rigidity. If Fe is less than 1.0 wt%, the effect of improving rigidity by contributing to dispersion strengthening cannot be obtained sufficiently, and if Fe is more than 2.1 wt%, Al-Fe-Si intermetallic compounds are formed in a needle shape, reducing the ease of molten metal supply.

[0027] In particular, it is preferable that the value A / B obtained by dividing the Fe content A by the Si content B satisfies the relationship A / B≧0.061. This relationship allows the Fe content relative to the Si content to be maintained at a certain level or higher. This allows the amount of Al-Fe-Si intermetallic compounds formed in the casting to be maintained at a certain level or higher. This in turn improves the rigidity of the casting.

[0028] Ni is contained in aluminum alloys in the range of 2.0 to 3.0 wt%, and has the effect of improving the fluidity of the molten metal. If Ni is contained in an amount less than 2.0 wt%, the effect of improving the fluidity of the molten metal is not sufficient, whereas if Ni is contained in an amount greater than 3.0 wt%, the specific gravity of Ni is large relative to the specific gravity of Al, and the cost per mass is high, which hinders weight reduction and increases material costs.

[0029] Ti is contained in the aluminum alloy in the range of 0.15 to 0.20 wt %, and TiAl ３Ti has the effect of refining crystal grains through heterogeneous nucleation during solidification, thereby improving the rigidity of the casting and the fluidity of the molten metal during casting. If Ti is less than 0.15 wt%, it is not possible to obtain a sufficient effect of improving the rigidity of the casting and the fluidity of the molten metal during casting, while if Ti is more than 0.20 wt%, it coarsens intermetallic compounds, reducing toughness and increasing material costs.

[0030] P is contained in aluminum alloys in the range of 0.01 to 0.015 wt%, and has the effect of refining crystal grains and improving the rigidity of the casting and the fluidity of the molten metal during casting. If P is less than 0.01 wt%, the effect of improving the fluidity of the molten metal is not sufficient, and if P is more than 0.015 wt%, the fluidity of the molten metal is reduced.

[0031] Zn is contained in an aluminum alloy at a content of 1.5 wt% or less, and because its melting point is lower than that of Al, it has the effect of improving the fluidity of the molten metal. If the Zn content is higher than 1.5 wt%, the specific gravity of Zn is greater than that of Al, hindering weight reduction. It is preferable that Zn be contained in the range of 1.1 to 1.5 wt%. However, Zn may not be contained in the aluminum alloy.

[0032] The aluminum alloy may further contain 0.05 to 0.20 wt% of Be (beryllium). Be has the effect of refining crystal grains and improving the rigidity of the casting and the fluidity of the molten metal during casting. In particular, an aluminum alloy containing 0.15 to 0.20 wt% of Be is preferred. If the Be content is less than 0.05 wt%, the effect of improving the rigidity of the casting and the fluidity of the molten metal during casting is not sufficient, while if the Be content is more than 0.20 wt%, the intermetallic compounds become coarse, reducing toughness.

[0033] The aluminum alloy may contain impurities. These elements are contained in amounts that do not significantly affect the rigidity of the aluminum alloy or the fluidity of the molten metal, and include unavoidable impurities that are present in raw materials (such as scrap materials and new aluminum ingots, as described below) or that are inevitably mixed in during the production of the aluminum alloy. The aluminum alloy may contain the following unavoidable impurities: 0.3 wt% or less of Cr (chromium), 0.3 wt% or less of Pb (lead), 0.3 wt% or less of Sn (tin), and 0.003 wt% or less of Ca (calcium). In this case, the total of Cr, Pb, Sn, and Ca is set to 0.9 wt% or less.

[0034] The aluminum alloy may contain impurities other than Cr, Pb, Sn, and Ca. The impurities other than Cr, Pb, Sn, and Ca must each be 0.05 wt% or less, with the total amount being 0.15 wt% or less. However, this does not apply to unavoidable impurities (e.g., Na (sodium), Sr (strontium), Sb (antimony)) added for the purpose of modification or refinement.

[0035] The aluminum alloy of this embodiment is produced (cast) by melting aluminum scraps and aluminum scrap material (hereinafter collectively referred to as "scrap material, etc.") generated during machining of high-purity aluminum or aluminum alloys, adding each element (Cu, Si, Mg, Mn, Fe, Ni, Ti, P, Zn, with the remainder being Al and impurities) to adjust the composition so that each element falls within the above-mentioned predetermined range, removing hydrogen gas generated in the molten metal, and then pouring the resulting molten metal into a mold to solidify it.

[0036] The aluminum alloy in this embodiment contains 1.0 to 2.1 wt % Fe and 1.5 wt % or less Zn, which makes it possible to manufacture the aluminum alloy using scrap material containing large amounts of Fe and Zn.

[0037] The aluminum alloy of this embodiment can be produced using scrap materials, etc., and therefore does not require the production of new aluminum ingots from bauxite. This eliminates the need for the firing process and electrolysis process required to produce new aluminum ingots from bauxite, thereby reducing production costs. In addition, CO generated in these processes can be reduced. ２ can be reduced.

[0038] A method for manufacturing a casting in one embodiment will be described. The casting in this embodiment is manufactured by casting the aluminum alloy in this embodiment described above. In this embodiment, the casting is cast by sand casting. The aluminum alloy is heated and melted in a furnace to form a molten metal. The molten aluminum alloy is poured into a sand mold and solidified to obtain the casting.

[0039] The present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples.

[0040] The content of each element was adjusted, and the molten aluminum alloy was heated to 800±10°C. The molten aluminum alloy was poured into a boat-shaped mold heated to a mold temperature of 150±10°C and allowed to solidify, thereby obtaining five castings each for Examples 1 to 13 and Comparative Examples 1 to 5. The dimensions of the castings were approximately 170 mm in length, approximately 25 mm in width, and approximately 30 mm in thickness.

[0041] (Analysis and Results of Content of Each Element) A rectangular parallelepiped test piece measuring 60 mm in length, 10 mm in width, and 3 mm in thickness was cut out from a position 10 mm from the bottom of the casting (the portion corresponding to the bottom of the mold). The content of each element in the test piece was analyzed by optical emission spectroscopy using a Shimadzu PDA-8000 optical emission spectrometer. The analytical values ​​of five test pieces were averaged to calculate the content of each element in the casting. The content of each element in the castings in Examples 1 to 13 and Comparative Examples 1 to 5 is shown in Table 1.

[0042] (Young's Modulus Measurement and Results) The Young's modulus of each test piece was measured at room temperature (approximately 20°C) by the resonance method using an elastic modulus measuring device JE2-RT manufactured by Nippon Technoplus Co., Ltd. The Young's modulus of the casting was calculated by averaging the measured values ​​of five test pieces. The Young's moduli of the castings in Examples 1 to 13 and Comparative Examples 1 to 5 are shown in Table 1. Table 1 also shows the value A / B obtained by dividing the Fe content A by the Si content B of each casting.

[0043]

[0044] As shown in Table 1, the castings in Examples 1 to 13 had a Young's modulus of 89.4 GPa or more. In particular, the castings in Examples 1 to 4 and 11 to 13 had a Young's modulus of 93.0 GPa or more. The castings in Comparative Examples 1 to 5 did not satisfy the Young's modulus of 89.4 GPa, and even the casting in Comparative Example 5, which showed the highest Young's modulus among them, only had a Young's modulus of 88.2 GPa. The castings in Examples 1 to 13 and Comparative Examples 1 to 5 all had good fluidity of the molten metal during casting.

[0045] The casting in Comparative Example 1 had lower contents of Cu, Mn, Ti, and P than the castings in Examples 1 to 3 and 6 to 13. Therefore, it is presumed that the solid solution hardening by Cu and Mn and the refinement of crystal grains by Ti and P were less than those of the castings in Examples 1 to 13, and the Young's modulus remained at 85.2 GPa.

[0046] Furthermore, since the casting in Comparative Example 1 had an A / B value of 0.023, it is presumed that the generation of Al-Fe-Si intermetallic compounds was less than that of the castings in Examples 1 to 13, in which the A / B value was 0.061 or more, and dispersion strengthening was insufficient, resulting in a Young's modulus of only 85.2 GPa.

[0047] The castings in Examples 4 and 5 had a lower Cu content than the casting in Comparative Example 1, but had higher Si, Mn, Fe, Ti, and P contents. Therefore, it is presumed that the Young's modulus was improved beyond the solid solution hardening due to Cu in the casting in Comparative Example 1 due to solid solution hardening by Mn, refinement of crystal grains by Ti and P, and dispersion strengthening caused by the formation of an Al-Fe-Si intermetallic compound of Si and Fe.

[0048] Next, the castings in Comparative Examples 2 to 4 have lower contents of Cu, Mn, Ti, and P than the castings in Examples 1 to 13, or contain only amounts comparable to those of impurities. Therefore, it is presumed that the solid solution hardening by Cu and Mn and the refinement of crystal grains by Ti and P are less than those in the castings in Examples 1 to 13, and the Young's modulus remains at 86.2 GPa or less.

[0049] Next, the casting in Comparative Example 5 had a higher Mg content and lower Cu, Mn, Fe, and Si contents than the casting in Example 1. Therefore, although there was a certain degree of effect of improving rigidity due to solid solution hardening of Mg, there was little solid solution hardening of Cu and Mn, and dispersion strengthening due to the formation of an Al-Fe-Si intermetallic compound by Fe and Si, and it is presumed that the Young's modulus remained at 88.2 GPa.

[0050] In the castings of Examples 4 to 9, Zn was added up to about 1.1 to 1.5 wt% to improve the fluidity of the molten metal, but a Young's modulus of 89.4 GPa or more was ensured. It is presumed that the addition of Zn at about 1.1 to 1.5 wt% did not affect the Young's modulus.

[0051] Among the castings in Examples 4 to 9, the casting in Example 8 had a higher Young's modulus than the casting in Example 7. This is presumably because the addition of Be resulted in refinement of the crystal grains, thereby improving the Young's modulus.

[0052] The castings in Examples 1 to 4 and 11 to 13 had higher Young's moduli than the castings in Examples 5 to 10 and Comparative Examples 1 to 5. The castings in Examples 1 to 4 and 11 to 13 contained Mn in the range of 1.9 to 2.1 wt%, while the castings in Examples 5 to 10 and Comparative Examples 1 to 5 contained only 1.71 wt% or less of Mn. Therefore, it is presumed that, among the elements Cu, Si, Mn, Fe, Ti, and P that improve rigidity, Mn contributed greatly to improving rigidity.

[0053] According to this example, it was revealed that castings (the castings in Examples 1 to 13) made from aluminum alloys containing 6.9 to 10.1 wt% Cu, 16.0 to 18.0 wt% Si, 0.4 to 0.7 wt% Mg, 1.5 to 2.1 wt% Mn, 1.0 to 2.1 wt% Fe, 2.0 to 3.0 wt% Ni, 0.15 to 0.20 wt% Ti, 0.01 to 0.015 wt% P, and 1.5 wt% or less Zn, with the remainder being Al and impurities, ensure the fluidity of the molten metal during casting and further have a higher Young's modulus than the castings in Comparative Examples 1 to 5.

[0054] It was revealed that castings (castings in Examples 1 to 13) made from aluminum alloys having the above-mentioned contents of Cu, Si, Mg, Mn, Fe, Ni, Ti, P, and Zn, and having a value A / B obtained by dividing the Fe content A by the Si content B of 0.061 or more, ensure the fluidity of the molten metal during casting, and furthermore, can have a higher Young's modulus than the castings in Comparative Examples 1 to 5.

[0055] It was revealed that the castings (the castings in Examples 4 to 9) made from an aluminum alloy having the above-mentioned contents of Cu, Si, Mg, Mn, Fe, Ni, Ti, P, and Zn, and an aluminum alloy having a Zn content of 1.1 to 1.5 wt %, can ensure a high Young's modulus while improving the fluidity of the molten metal during casting compared to the castings in Examples 1 to 3 and 10 to 13.

[0056] It was revealed that a casting (the casting in Example 8) made from an aluminum alloy having the above-mentioned contents of Cu, Si, Mg, Mn, Fe, Ni, Ti, P, and Zn and further containing 0.15 to 0.20 wt % Be ensures the fluidity of the molten metal during casting, and furthermore, can have a higher Young's modulus than the castings in Example 7 and Comparative Examples 1 to 5.

[0057] It was revealed that castings (the castings in Examples 1 to 4 and 11 to 13) made from aluminum alloys containing Cu, Si, Mg, Mn, Fe, Ni, Ti, P, and Zn in the above-mentioned contents, and having an Mn content of 1.9 to 2.0 wt%, ensure the fluidity of the molten metal during casting, and further have a higher Young's modulus than the castings in Examples 5 to 10 and Comparative Examples 1 to 5.

[0058] The present invention has been described above based on embodiments and examples, but the present invention is not limited to the above embodiments and examples, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention.

[0059] In the embodiment, a case has been described in which an aluminum alloy is produced using scrap material or the like, but new aluminum ingots may be used, or new aluminum ingots and scrap material or the like may be used in combination.

[0060] In the embodiment, a case where a casting is produced by sand casting has been described, but the casting may also be produced by die casting such as die casting, low-pressure die casting, and gravity die casting, or by other casting methods that can be used with existing aluminum alloys.

[0061] In the embodiment, a case has been described in which the casting is not subjected to various heat treatments such as age hardening and solution treatment that can be employed in existing castings, but any of these may be performed.

Claims

1. An aluminum alloy containing Cu, Si, Mg, Mn, Fe, Ni, Ti, and P, with the remainder being Al and impurities, with the element contents being 6.9-10.1 wt% Cu, 16.0-18.0 wt% Si, 0.4-0.7 wt% Mg, 1.5-2.1 wt% Mn, 1.0-2.1 wt% Fe, 2.0-3.0 wt% Ni, 0.15-0.20 wt% Ti, and 0.01-0.015 wt% P.

2. An aluminum alloy according to claim 1, wherein the value obtained by dividing the Fe content by the Si content is 0.061 or more.

3. The aluminum alloy of claim 1 further comprising 1.1 to 1.5 wt% Zn.

4. The aluminum alloy according to claim 3, further comprising 0.15 to 0.20 wt% Be.

5. A casting obtained by casting the aluminum alloy according to any one of claims 1 to 4.