WO2024048895A1 - Aluminum alloy casting material and brake disc comprising same - Google Patents

Abstract

The present invention provides an aluminum alloy casting material with excellent high-temperature tensile strength and corrosion resistance. The aluminum alloy casting material comprises 13.0 wt% (exclusive) to 15 wt% (inclusive) of silicon (Si), 2.7 wt% to 4.1 wt% of magnesium (Mg), 0 wt% (exclusive) to 2 wt% (inclusive) of copper (Cu), and the balance being aluminum (Al) and inevitable impurities.

Description

Aluminum alloy castings and brake discs containing the same

The present invention relates to an aluminum alloy casting material, and more specifically, to an aluminum alloy casting material having excellent high-temperature strength and corrosion resistance and a brake disc containing the same.

Due to environmental and energy issues around the world, transportation devices such as automobiles are being converted from internal combustion engines to electric vehicles. Even in electric vehicles, reducing vehicle weight is essential to improve fuel efficiency. In particular, brake discs, which are braking parts of automobiles, are mainly manufactured from cast iron. In general, in an internal combustion engine, braking is performed only by mechanical braking. However, since regenerative braking is introduced in electric vehicles, the braking environment required for mechanical braking applied to electric vehicles can be alleviated compared to internal combustion engine vehicles. Due to this braking environment, attempts are being made to use aluminum alloy castings as brake discs in electric vehicles.

Meanwhile, aluminum has been examined as a material that can replace cast iron in order to reduce the weight of automobiles over the past few decades, but materials that can replace it have been limited to aluminum matrix composites (MMCs). In particular, in electric vehicles, the use of aluminum alloy as a replacement for cast iron in brake discs is being actively considered for weight reduction. Until now, the aluminum material has excellent room and high temperature characteristics and excellent wear resistance, but has not been used in brake discs due to its high manufacturing cost, low recyclability, and poor machinability. In addition, the main properties required for materials used in brake discs are high-temperature strength and wear resistance, and corrosion resistance is additionally required to improve emotional quality.

However, an aluminum alloy casting material that can improve high-temperature strength and wear resistance while also improving corrosion resistance has not been developed.

The technical problem to be achieved by the technical idea of the present invention is to provide an aluminum alloy casting material having high high-temperature strength and excellent corrosion resistance, and a brake disc containing the same.

However, these tasks are illustrative and do not limit the scope of the present invention.

According to one aspect of the present invention, an aluminum alloy casting material having high high-temperature strength and excellent corrosion resistance and a brake disc including the same are provided.

According to one embodiment of the present invention, the aluminum alloy casting material contains more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 2% copper (Cu) by weight; and the remainder may include aluminum (Al) and inevitable impurities.

According to one embodiment of the present invention, it may further include more than 0% by weight to 1.0% by weight of manganese (Mn).

According to one embodiment of the present invention, it may further include more than 0% by weight to 1.5% by weight of nickel (Ni).

According to one embodiment of the present invention, it may further include zirconium (Zr) in an amount greater than 0% by weight to 0.25% by weight.

According to one embodiment of the present invention, titanium (Ti) in an amount greater than 0% by weight to 0.05% by weight; And it may further include boron (B) in an amount of more than 0% by weight to 0.005% by weight.

According to one embodiment of the present invention, the aluminum alloy cast material may have a microstructure consisting of at least one of eutectic Si, eutectic Mg ₂ Si, primary Si, and primary Mg ₂ Si.

According to one embodiment of the present invention, the aluminum alloy casting material may have a corrosion rate of 0.2 mm/year or less.

According to one embodiment of the present invention, the aluminum alloy cast material may have a high temperature tensile strength of 250°C in the range of 190 MPa to 230 MPa.

According to one embodiment of the present invention, the aluminum alloy casting material may be subjected to solution treatment and then subjected to aging treatment.

The aluminum alloy casting material may be aged without solution treatment.

According to one embodiment of the present invention, the aluminum alloy casting material contains more than 13.0% by weight to 15% by weight of silicon (Si); 2.81% to 3.5% magnesium (Mg) by weight; 0.021% to 1.603% by weight copper (Cu); 0.002% to 0.537% by weight manganese (Mn); and the remainder may include aluminum (Al) and inevitable impurities.

According to one embodiment of the present invention, it may further include 0.021% by weight to 0.641% by weight of nickel (Ni).

According to one embodiment of the present invention, it may further include 0.004% by weight to 0.185% by weight of zirconium (Zr).

According to one embodiment of the present invention, the aluminum alloy casting material contains more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 1% by weight manganese (Mn); and the remainder may include aluminum (Al) and inevitable impurities.

According to one embodiment of the present invention, the brake disc includes more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 2% copper (Cu) by weight; and the remainder may be composed of aluminum alloy casting material containing aluminum (Al) and inevitable impurities.

According to various embodiments of the present invention as described above, by controlling the alloy composition and content of copper and manganese, it is possible to provide an aluminum alloy casting material with high high-temperature strength and excellent corrosion resistance and wear resistance. Additionally, a brake disc for an electric vehicle can be manufactured using the alloy. Of course, the scope of the present invention is not limited by this effect.

Figure 1 is a phase diagram of an aluminum-silicon binary alloy for alloy design of an aluminum alloy cast material according to an embodiment of the present invention.

Figure 2 is a phase diagram of an aluminum-silicon-magnesium alloy obtained through thermodynamic computational calculations for alloy design of an aluminum alloy cast material according to an embodiment of the present invention.

Figures 3 and 4 are optical microscope photographs showing the microstructure of an aluminum alloy cast material for alloy design of the aluminum alloy cast material according to an embodiment of the present invention.

Figure 5 is a graph showing the room temperature tensile strength and elongation of an aluminum alloy cast material subjected to T6 heat treatment according to an embodiment of the present invention.

Figure 6 is a graph showing the room temperature tensile strength and elongation of an aluminum alloy cast material subjected to T5 heat treatment according to an embodiment of the present invention.

Figure 7 is a graph calculated by thermodynamic calculation of the fraction of the formed phase upon addition of copper in an aluminum alloy casting material according to an embodiment of the present invention.

Figure 8 is a graph calculated by thermodynamic calculation of the fraction of phases formed upon adding nickel in an aluminum alloy casting material according to an embodiment of the present invention.

Figures 9 and 10 are optical microscope photographs showing the microstructure of an aluminum alloy cast material according to an embodiment of the present invention.

Figure 11 is a schematic diagram showing a brake system including a brake disc formed of aluminum alloy casting according to an embodiment of the present invention.

Hereinafter, various preferred embodiments of the present invention will be described in detail with reference to the attached drawings.

The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following examples may be modified into various other forms, and the scope of the present invention is as follows. It is not limited to examples. Rather, these embodiments are provided to make the present disclosure more faithful and complete and to fully convey the spirit of the present invention to those skilled in the art. Additionally, the thickness and size of each layer in the drawings are exaggerated for convenience and clarity of explanation.

The terms used herein are used to describe specific embodiments and are not intended to limit the invention. As used herein, the singular forms include the plural forms unless the context clearly indicates otherwise. Additionally, when used herein, “comprise” and/or “comprising” means specifying the presence of stated features, numbers, steps, operations, members, elements and/or groups thereof. and does not exclude the presence or addition of one or more other shapes, numbers, operations, members, elements and/or groups.

The aluminum alloy casting material according to an embodiment of the present invention contains more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 2% copper (Cu) by weight; and the remainder may include aluminum (Al) and inevitable impurities. Additionally, the content of silicon (Si) contained in the aluminum alloy casting may range from 13.1% by weight to 15% by weight.

The aluminum alloy casting material according to an embodiment of the present invention contains more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 2% copper (Cu) by weight; Greater than 0% to 1.0% by weight manganese (Mn); and the remainder may include aluminum (Al) and inevitable impurities. That is, the aluminum alloy cast material further contains manganese (Mn) in an amount of more than 0% by weight to 1.0% by weight.

The aluminum alloy casting material according to an embodiment of the present invention contains more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 1% by weight manganese (Mn); and the remainder may include aluminum (Al) and inevitable impurities.

The aluminum alloy casting material may further include nickel (Ni) in an amount of more than 0% by weight to 1.5% by weight in addition to the above elements, or it may further include zirconium (Zr) in an amount of more than 0% by weight to 0.25% by weight in addition to the elements. , more than 0% by weight to 1.5% by weight of nickel (Ni) in addition to the above elements; And it may further include zirconium (Zr) in an amount of more than 0% by weight to 0.25% by weight.

The aluminum alloy casting material includes titanium (Ti) in an amount of more than 0% by weight to 0.05% by weight in addition to the above elements; And it may further include boron (B) in an amount of more than 0% by weight to 0.005% by weight.

The aluminum alloy casting material may further include iron (Fe) in an amount of more than 0% by weight to 0.2% by weight as an inevitable impurity in addition to the above elements.

The aluminum alloy casting material may further contain 30 ppm to 200 ppm of phosphorus. The phosphorus may be included in the form of AlP. Additionally, the aluminum alloy casting material may further include 50 ppm to 200 ppm of strontium (Sr).

The aluminum alloy casting material according to an embodiment of the present invention contains more than 13.0% by weight to 15% by weight of silicon (Si); 2.81% to 3.5% magnesium (Mg) by weight; 0.021% to 1.603% by weight copper (Cu); 0.002% to 0.537% by weight manganese (Mn); and the remainder may include aluminum (Al) and inevitable impurities. Additionally, the content of silicon (Si) contained in the aluminum alloy casting may range from 13.3% by weight to 14.6% by weight.

The aluminum alloy casting material may further include 0.021% to 0.641% by weight of nickel (Ni) in addition to the above elements, or may further include 0.004% to 0.185% by weight of zirconium (Zr) in addition to the above elements. 0.021% to 0.641% by weight of nickel (Ni) in addition to the element; And it may further include 0.004% by weight to 0.185% by weight of zirconium (Zr).

The aluminum alloy casting material includes, in addition to the above elements, 0.034% by weight to 0.040% by weight of titanium (Ti); And it may further include 0.001% by weight to 0.004% by weight of boron (B).

The aluminum alloy casting material may further include 0.120% to 0.158% by weight of iron (Fe) as the inevitable impurity in addition to the above elements.

The aluminum alloy casting material may further contain 30 ppm to 200 ppm of phosphorus. The phosphorus may be included in the form of AlP. Additionally, the aluminum alloy casting material may further include 50 ppm to 200 ppm of strontium (Sr).

The aluminum alloy cast material may have a microstructure consisting of at least one of eutectic Si, eutectic Mg ₂ Si, primary Si, and primary Mg ₂ Si.

The aluminum alloy cast material may be subjected to heat treatment after casting, for example, T6 heat treatment, which is an aging treatment after solution treatment.

The aluminum alloy casting material subjected to the T6 heat treatment may have a corrosion rate in the range of 0.2 mm/year or less, and may have a corrosion rate in the range of more than 0 mm/year to less than 0.2 mm/year. The corrosion rate is calculated by measuring the weight loss after immersing the aluminum alloy cast material in a 5.0% NaCl aqueous solution for 480 hours.

The aluminum alloy casting material subjected to the T6 heat treatment may have a room temperature tensile strength in the range of 300 MPa to 360 MPa. The aluminum alloy casting may have a high temperature tensile strength of 200°C in the range of 240 MPa to 300 MPa. The aluminum alloy cast material may have a high temperature tensile strength of 250°C in the range of 190 MPa to 230 MPa. The aluminum alloy casting material may have a high temperature tensile strength of 300°C in the range of 90 MPa to 140 MPa. The aluminum alloy casting material may have a high temperature tensile strength of 350°C in the range of 70 MPa to 80 MPa.

Alternatively, the aluminum alloy cast material may be subjected to T5 heat treatment, which is aging treatment without solution treatment.

The aluminum alloy casting material subjected to the T5 heat treatment may have a corrosion rate in the range of 0.4 mm/year or less, and may have a corrosion rate in the range of more than 0 mm/year to less than 0.4 mm/year. The corrosion rate is calculated by measuring the weight loss after immersing the aluminum alloy cast material in a 5.0% NaCl aqueous solution for 480 hours.

The aluminum alloy casting material subjected to the T5 heat treatment may have a room temperature tensile strength in the range of 200 MPa to 230 MPa. The aluminum alloy casting material may have a high temperature tensile strength of 200°C in the range of 180 MPa to 210 MPa. The aluminum alloy cast material may have a high temperature tensile strength of 250°C in the range of 130 MPa to 150 MPa. The aluminum alloy cast material may have a high temperature tensile strength of 300°C in the range of 90 MPa to 110 MPa. The aluminum alloy casting may have a high temperature tensile strength of 350°C in the range of 60 MPa to 80 MPa.

Hereinafter, the critical significance of the composition range of the aluminum alloy cast material of the present invention, the formation of intermetallic compounds according to the composition range, and the resulting effects will be explained in detail.

In general, a widely used aluminum alloy casting material is an aluminum-silicon alloy. Therefore, the aluminum-silicon binary alloy will be described.

Figure 1 is a phase diagram of an aluminum-silicon binary alloy for alloy design of an aluminum alloy cast material according to an embodiment of the present invention.

Referring to Figure 1, a phase diagram of an aluminum-silicon binary alloy is shown. When silicon (Si) is 12.6% by weight, the composition is a eutectic reaction between aluminum and silicon. Below the eutectic composition (i.e., less than 12.6 wt% silicon), a microstructure composed of α-Al and fine eutectic Si (eutectic Si) is formed. On the other hand, if the eutectic composition is exceeded, that is, if silicon exceeds 12.6% by weight, a microstructure composed of α-Al, eutectic Si (eutectic Si), and primary Si (primary Si) is formed. Here, silicon has higher hardness than α-Al, which is a matrix, and can contribute to high-temperature strength and wear resistance.

However, if silicon is added in excess of the eutectic reaction composition, the primary Si is formed, and as the content of silicon increases, the primary Si exists in a coarse polygonal form, which reduces the contribution to high temperature strength and also reduces wear resistance. You can. Therefore, control of the silicon content is required.

Additionally, in general, if silicon is present in a fine and uniform state in a large amount within the microstructure of an aluminum-silicon alloy, wear resistance is improved. However, the above microstructure cannot be realized using a general casting method in aluminum-silicon alloys, and can only be achieved when the solidification rate is very fast. For example, a casting method with a fast solidification speed, such as spray deposition, must be used.

Additionally, from the perspective of high-temperature strength, the interconnectivity of the generated phases within the microstructure is important, and the higher the interconnectivity, the higher the high-temperature strength. The interconnectivity of the formation phases refers to the degree to which individual formation phases are in contact with each other, and can be easily understood as a truss structure. Here, if the produced phase is needle-shaped or fibrous, interconnectivity is high, and if the produced phase is square or spherical, interconnectivity is low. In aluminum-silicon alloys, primary Si has low interconnectivity, and eutectic Si has high interconnectivity. In other words, eutectic Si appears two-dimensionally in the form of needles or fine spheres, and three-dimensionally is connected in a fibrous form, so interconnectivity is high. Therefore, the more eutectic Si, the higher the high-temperature strength can be.

In order to be applied to parts such as pistons and brake discs that require high temperature characteristics, alloys containing 10% to 13% by weight of silicon, which is near the eutectic composition of aluminum-silicon, are used. In this way, an alloy having a composition close to the eutectic point in the Al-Si binary phase diagram is referred to as an Al-Si approximate binary eutectic alloy (near eutectic Al-Si alloy).

In order to further improve the high temperature characteristics by improving the above-mentioned interconnectivity, copper (Cu) or nickel (Ni) may be added, for example, copper in an amount of 2 to 4 wt% and nickel in an amount of 2 to 3 wt%. Weight percent can be added. In addition, molybdenum (Mo), chromium (Cr), manganese (Mn), cobalt (Co), titanium (Ti), zirconium (Zr), vanadium (V), etc. can be added, for example, 1% by weight of each. The following can be added.

Copper (Cu) can react with aluminum (Al), silicon (Si), magnesium (Mg), etc. to form various types of intermetallic compounds (IMCs). The intermetallic compound may include, for example, CuAl ₂ , CuMgAl, AlCuMgSi, etc. The intermetallic compound can increase the hardness of the aluminum matrix and improve high-temperature strength by improving interconnectivity together with eutectic Si.

Nickel (Ni) can react with aluminum (Al), copper (Cu), etc. to form various types of intermetallic compounds. The intermetallic compound may include, for example, Al ₃ Ni, AlCuNi, etc. Most of the intermetallic compounds have a needle-like or polygonal shape, are stable at high temperatures, and have significantly higher hardness than the aluminum matrix. The intermetallic compound can improve high-temperature strength by improving interconnectivity with eutectic Si.

Molybdenum (Mo), chromium (Cr), manganese (Mn), cobalt (Co), titanium (Ti), zirconium (Zr), vanadium (V), etc. react with aluminum (Al), silicon (Si), etc. to form various types. can form intermetallic compounds. The intermetallic compound may include, for example, AlMo, AlCr, AlMn, AlCo, AlZr, AlTi, AlV, AlSiTi, AlSiZr, etc. Most of the intermetallic compounds have a needle-like or polygonal shape, are stable at high temperatures, and have significantly higher hardness than the aluminum matrix. The intermetallic compound can improve high-temperature strength by improving interconnectivity with eutectic Si.

However, as mentioned above, copper (Cu), nickel (Ni), molybdenum (Mo), chromium (Cr), manganese (Mn), cobalt (Co), titanium (Ti), and zirconium are added to improve high temperature strength. (Zr), vanadium (V), etc. have the problem of lowering the corrosion resistance of aluminum alloy. This is because the intermetallic compounds formed by these elements have a higher corrosion potential than the aluminum matrix, which ultimately reduces the corrosion resistance of the aluminum alloy.

To increase the matrix hardness of aluminum, magnesium (Mg) can be added. Magnesium (Mg) reacts with silicon (Si) to form a Mg ₂ Si intermetallic compound. The Mg ₂ Si intermetallic compound has a lower corrosion potential than the aluminum matrix and can act as a sacrificial anode to improve the corrosion resistance of the alloy. there is. In addition, in the case of silicon (Si), the corrosion potential is higher than that of aluminum (Al), but the current density is low and the corrosion resistance of the alloy is not significantly reduced. Magnesium (Mg) can be added, for example, in an amount of 1% by weight or less, but in the present invention, it is added in an amount of 2.7% by weight to 4.1% by weight to increase corrosion resistance.

In the present invention, in order to improve high-temperature strength while minimizing the decrease in corrosion resistance, the content of silicon, which relatively does not decrease corrosion resistance, and magnesium, which improves corrosion resistance, are controlled, and in particular, Mg ₂ Si is produced finely and densely, thereby producing We seek to devise a method to implement microstructures with improved interconnectivity. In addition, elements such as copper (Cu), nickel (Ni), molybdenum (Mo), chromium (Cr), manganese (Mn), cobalt (Co), titanium (Ti), zirconium (Zr), and vanadium (V). We would like to devise a method to improve high-temperature strength while minimizing the decline in corrosion resistance by selectively adding it and controlling its content.

Figure 2 is a phase diagram of an aluminum-silicon-magnesium alloy obtained through thermodynamic computational calculations for alloy design of an aluminum alloy cast material according to an embodiment of the present invention.

Referring to Figure 2, a ternary phase diagram of an aluminum-silicon-magnesium alloy is shown. It can be seen that when a large amount of magnesium is added to an Al-Si alloy, eutectic Si, primary Si, eutectic Mg ₂ Si, and primary Mg ₂ Si are produced depending on the added amounts of silicon and magnesium. At this time, in order to maximize the fraction of eutectic Si or eutectic Mg ₂ Si, it is important to control the added amounts of silicon and magnesium.

From the above phase diagram, the ternary eutectic point of Al-Si-Mg ₂ Si is calculated to be 14.0% by weight of silicon and 5.1% by weight of magnesium. That is, in the Al-Si binary system, silicon added by more than 12.6% exists as polygonal primary Si as described above, but if a large amount of magnesium is added here, the excess added silicon reacts with magnesium to form eutectic Mg rather than primary Si. ₂ Si is formed. Interconnectivity can be improved by forming a eutectic structure composed of fine eutectic Si and eutectic Mg ₂ Si.

When magnesium is added to an Al-Si alloy, if the silicon content exceeds 17% by weight, the size of primary Si increases. In order to satisfy the desired corrosion resistance and strength properties, it is desirable to increase the fraction of eutectic Si and minimize the production of primary Si. However, since primary Si has higher hardness than primary Mg ₂ Si, it is more effective in improving high temperature characteristics and wear resistance, and does not significantly reduce corrosion resistance, so the characteristics can be improved even if some primary Si remains. Therefore, if the silicon content is 13.0% by weight or less, eutectic Si cannot be sufficiently secured and it is difficult to obtain a dense eutectic structure, and if the silicon content is more than 15% by weight, a large amount of primary Si may be formed. Accordingly, the content of silicon may range from more than 13.0% by weight to 15% by weight.

Hereinafter, an alloy to which more than 13.0 wt% to 15.0 wt% of silicon (Si) and 2.7 wt% to 4.1 wt% of magnesium (Mg) are added to aluminum (Al) is subjected to an Al-Si-Mg ₂ Si approximate ternary process. It will be referred to as the composition (near ternary eutectic Al-Si-Mg ₂ Si). Here, the approximate ternary eutectic composition refers to an alloy having a composition close to the eutectic point of the ternary phase diagram shown in FIG. 2.

Additionally, when manganese (Mn) is added to the approximate ternary eutectic composition of Al-Si-Mg ₂ Si, manganese reacts with aluminum, silicon, and iron, which is an inevitable impurity, to form Al(Fe, Mn)Si, etc. can be formed. As the manganese content increases, the fraction of the produced phase increases and its size becomes coarse. The addition of manganese does not significantly impair corrosion resistance, and the resulting Al(Fe, Mn)Si phase can provide the advantage of improving high-temperature tensile strength. However, if the Mn content is too excessive, Al(Fe, Mn)Si becomes coarse and may act as sludge in the molten metal. Therefore, the content of manganese may be 1% by weight or less. Additionally, the content of manganese may be 0.8% by weight or less and may range from 0.3% by weight to 0.7% by weight.

Hereinafter, the composition range and mechanical properties of the aluminum alloy cast material will be described in detail through experimental examples of the present invention.

Experiment example

Below, preferred experimental examples are presented to aid understanding of the present invention. However, the following experimental examples are only intended to aid understanding of the present invention, and the present invention is not limited by the following experimental examples. Any information not described here can be technically inferred by anyone skilled in the art, so description thereof will be omitted.

Experimental method

According to the composition as shown in Table 1 below, pure aluminum, metal silicon, pure magnesium, pure copper, pure nickel, and Al-10% by weight Mn master alloy, Al-10% by weight Zr master alloy, and Al-10% by weight Sr master alloy. , Al-5% by weight TiB ₂ master alloy, Al-P master alloy, etc. were melted using an electric resistance melting furnace in the air to form molten aluminum. At the time of dissolution, the melting temperature of the molten aluminum was 750°C. After melting and degassing, molten aluminum was injected into a mold preheated to 200°C and cast to form an aluminum alloy cast material.

Heat treatment (T6) was performed on the aluminum alloy casting material as follows. The solution treatment was carried out in a temperature range of 490°C to 540°C. After solution treatment, it was quenched in water. Subsequently, aging treatment was performed at a temperature range of 160°C to 200°C. Details of the heat treatment were carried out in a conventional manner. The solution treatment temperature and aging treatment temperature were changed depending on the copper (Cu) content.

Some of the aluminum alloy castings were heat treated (T5) by only aging treatment at a temperature range of 180°C to 240°C without solution heat treatment. The aging treatment temperature was changed depending on the copper (Cu) content.

After performing the heat treatment described above, a tensile test was performed on the aluminum alloy casting at room temperature and high temperature (200°C to 350°C) in accordance with ASTM E8 and ASTM E21 regulations. In addition, a salt spray test was conducted on the aluminum alloy casting material according to ISO 9227 regulations. The salt spray test was conducted for 480 hours using a 5.0% NaCl aqueous solution, and after the test, corrosion products were removed according to ASTM G1 regulations, weight loss was measured, and the corrosion rate was calculated using this. The tensile strength and corrosion rate of aluminum alloy castings are shown in Table 2 below.

The microstructure of the aluminum alloy cast material was observed using an optical microscope.

Experimental results and discussion

Table 1 is a table showing the composition and content of the aluminum alloy casting material according to an embodiment of the present invention. The alloy composition in Table 1 refers to weight percent. In all experimental examples, the balance includes aluminum and other unavoidable impurities.

classification	Si	Mg	Cu	Mn	Ni	Zr	Fe	Ti	B
Experimental Example 1	14.0	2.93	0.013	0.005	0.014	0.002	0.162	0.042	0.002
Experimental Example 2	13.9	3.32	0.014	0.001	0.011	0.003	0.120	0.048	0.001
Experimental Example 3	14.1	4.02	0.020	0.002	0.013	0.002	0.138	0.045	0.002
Experimental Example 4	13.8	4.50	0.020	0.001	0.012	0.002	0.122	0.046	0.002
Experimental Example 5	14.3	3.31	0.031	0.003	0.013	0.004	0.147	0.043	0.002
Experimental Example 6	14.0	5.33	0.020	0.001	0.011	0.001	0.107	0.046	0.001
Experimental Example 7	18.5	0.46	0.034	0.013	0.017	0.011	0.188	0.048	0.006
Experimental Example 8	17.5	0.47	4.862	0.005	0.007	0.003	0.212	0.015	0.003
Experimental Example 9	19.1	0.48	1.246	0.010	0.012	0.008	0.158	0.047	0.004
Experimental Example 10	17.7	1.88	0.028	0.013	0.016	0.009	0.202	0.053	0.005
Experimental Example 11	13.9	2.92	0.009	0.004	0.031	0.003	0.168	0.034	0.002
Experimental Example 12	12.6	2.80	0.981	1.340	0.014	0.005	0.130	0.038	0.003
Experimental Example 13	18.5	0.46	0.034	0.013	0.017	0.011	0.188	0.048	0.006
Experimental Example 14	17.5	0.47	4.862	0.005	0.007	0.003	0.212	0.015	0.003
Experimental Example 15	14.3	2.89	0.021	0.506	0.033	0.006	0.146	0.038	0.004
Experimental Example 16	14.6	3.26	1.043	0.002	0.029	0.004	0.132	0.038	0.003
Experimental Example 17	14.0	3.18	1.018	0.497	0.028	0.006	0.140	0.039	0.003
Experimental Example 18	14.4	3.24	1.222	0.514	0.037	0.176	0.158	0.034	0.003
Experimental Example 19	14.1	3.18	1.027	0.004	0.503	0.005	0.144	0.037	0.003
Experimental Example 20	13.8	3.42	1.206	0.502	0.594	0.006	0.141	0.040	0.002
Experimental Example 21	13.8	3.50	1.098	0.537	0.641	0.185	0.149	0.038	0.001
Experimental Example 22	13.4	3.06	1.061	0.344	0.029	0.006	0.124	0.037	0.004
Experimental Example 23	13.6	2.81	1.002	0.341	0.021	0.006	0.120	0.038	0.003
Experimental Example 24	13.3	3.10	1.007	0.342	0.562	0.004	0.130	0.038	0.003
Experimental Example 25	13.3	3.31	1.603	0.381	0.034	0.006	0.120	0.039	0.002

Referring to Table 1, the content of elements that are not intentionally added to the aluminum alloy casting material but are included as inevitable impurities are underlined.

In all of the experimental examples, iron (Fe) was included as an inevitable impurity without intentional addition, and titanium (Ti) and boron (B) were included by the addition of AlTiBor, a particle refiner.

In addition, in Experimental Examples 1 to 14 below, nickel (Ni) and zirconium (Zr) were not intentionally added but included as inevitable impurities.

Experimental Examples 1 to 3 are different in that silicon (Si) and magnesium (Mg) are included within the scope of the present invention, and copper (Cu) and manganese (Mn) are included as inevitable impurities rather than intentionally added.

Experimental Example 4 includes silicon (Si) within the scope of the present invention, but includes magnesium (Mg) in excess of the upper limit of the scope of the present invention, and copper (Cu) and manganese (Mn) are added without intentional addition. There is a difference in the inclusion of impurities.

Experimental Example 5 includes silicon (Si) and magnesium (Mg) within the scope of the present invention, but is different in that copper (Cu) and manganese (Mn) are included as inevitable impurities rather than intentionally added.

Experimental Example 6 includes silicon (Si) within the scope of the present invention, but includes magnesium (Mg) in excess of the upper limit of the scope of the present invention, and copper (Cu) and manganese (Mn) are added without intentional addition. There is a difference in the inclusion of impurities.

Experimental Example 7 contains silicon (Si) exceeding the upper limit of the range of the present invention, magnesium (Mg) below the lower limit of the range of the present invention, and copper (Cu) and manganese (Mn) are intentionally added. There is a difference in that it does not contain it as an inevitable impurity.

Experimental Example 8 contains silicon (Si) exceeding the upper limit of the range of the present invention, magnesium (Mg) below the lower limit of the range of the present invention, and copper (Cu) exceeding the upper limit of the range of the present invention. There is a difference in that manganese (Mn) is not added intentionally but is included as an inevitable impurity.

Experimental Example 9 contains silicon (Si) above the upper limit of the range of the present invention, magnesium (Mg) below the lower limit of the range of the present invention, and copper (Cu) within the range of the present invention, There is a difference in that manganese (Mn) is not added intentionally but is included as an inevitable impurity.

Experimental Example 10 contained silicon (Si) exceeding the upper limit of the range of the present invention, magnesium (Mg) below the lower limit of the range of the present invention, and copper (Cu) and manganese (Mn) were intentionally added. There is a difference in that it does not contain it as an inevitable impurity.

Experimental Example 11 includes silicon (Si) and magnesium (Mg) within the scope of the present invention, but has the difference in that copper (Cu) and manganese (Mn) are included as inevitable impurities rather than intentionally added.

Experimental Example 12 includes silicon (Si) below the lower limit of the range, magnesium (Mg) within the scope of the present invention, copper (Cu) within the scope of the present invention, and manganese (Mn) within the scope of the present invention. There are differences that include exceeding the upper limit of the range.

Experimental Example 13 contains silicon (Si) above the upper limit of the range of the present invention, magnesium (Mg) below the lower limit of the range of the present invention, and copper (Cu) and manganese (Mn) are intentionally added. There is a difference in that it does not contain it as an inevitable impurity.

Experimental Example 14 contained silicon (Si) exceeding the upper limit of the range of the present invention, magnesium (Mg) below the lower limit of the range of the present invention, and copper (Cu) exceeding the upper limit of the range of the present invention. There is a difference in that manganese (Mn) is not added intentionally but is included as an inevitable impurity.

All of the following Experimental Examples 15 to 25 include silicon (Si) and magnesium (Mg) within the scope of the present invention.

Experimental Example 15 further includes manganese (Mn) within the scope of the present invention, and includes copper (Cu), nickel (Ni), and zirconium (Zr) as inevitable impurities without intentional addition.

Experimental Example 16 further includes copper (Cu) within the scope of the present invention, and includes manganese (Mn), nickel (Ni), and zirconium (Zr) as inevitable impurities without intentional addition.

Experimental Example 17 further includes copper (Cu) and manganese (Mn) within the scope of the present invention, and includes nickel (Ni) and zirconium (Zr) as inevitable impurities without intentional addition.

Experimental Example 18 further includes copper (Cu), manganese (Mn), and zirconium (Zr) within the scope of the present invention, and includes nickel (Ni) as an inevitable impurity without intentional addition.

Experimental Example 19 further includes copper (Cu) and nickel (Ni) within the scope of the present invention, and includes manganese (Mn) and zirconium (Zr) as inevitable impurities without intentional addition.

Experimental Example 20 further includes copper (Cu), manganese (Mn), and nickel (Ni) within the scope of the present invention, and includes zirconium (Zr) as an inevitable impurity without intentional addition.

Experimental Example 21 further includes copper (Cu), manganese (Mn), nickel (Ni), and zirconium (Zr) within the scope of the present invention.

Experimental Examples 22 and 23 further include copper (Cu) and manganese (Mn) within the scope of the present invention, and include nickel (Ni) and zirconium (Zr) as inevitable impurities without intentional addition.

Experimental Example 24 further includes copper (Cu), manganese (Mn), and nickel (Ni) within the scope of the present invention, and includes zirconium (Zr) as an inevitable impurity without intentional addition.

Experimental Example 25 further includes copper (Cu) and manganese (Mn) within the scope of the present invention, and includes nickel (Ni) and zirconium (Zr) as inevitable impurities without intentional addition.

Experimental Examples 7 to 12 and Experimental Examples 15 to 22 are cases in which T6 heat treatment is performed, and Experimental Examples 13, 14, and 23 to 25 are cases in which T5 heat treatment is performed. Specifically, Experimental Example 7 and Experimental Example 13 had the same alloy composition, but Experimental Example 7 was subjected to T6 heat treatment and Experimental Example 13 was subjected to T5 heat treatment. Similarly, Experimental Example 8 and Experimental Example 14 correspond.

Figures 3 and 4 are optical microscope photographs showing the microstructure of an aluminum alloy cast material for alloy design of the aluminum alloy cast material according to an embodiment of the present invention.

Referring to Figure 3, the microstructure of Experimental Examples 7 to 10 as an Al-18Si alloy is shown. The microstructure consists of α-Al, eutectic Si (Eutectic Si), and primary Si. It can be confirmed that a certain amount of α-Al exists even when a large amount of silicon is added, up to 18% by weight. This means that during solidification, primary Si crystallizes first, and there is a local shortage of silicon in the vicinity of the crystallized primary Si, thereby generating α-Al. In other words, it can be seen that adding more silicon above the eutectic point of 12.6% by weight silicon in the Al-Si alloy leads to an increase in coarse primary Si rather than an increase in the eutectic structure. In addition, when adding a large amount of magnesium (Mg) to Al-18Si alloy, eutectic Mg ₂ Si is generated as in Experimental Example 10, but the problem of primary Si becoming coarse is confirmed.

Therefore, the ternary eutectic point of Al-Si-Mg ₂ Si (Si 14.0 wt%, Mg 5.1 wt%) is an ideal case, so the magnesium content was changed from silicon 14.0 wt% Si to determine the silicon and magnesium contents. .

Referring to Figure 4, the microstructure of the aluminum alloy cast material of Experimental Examples 1 to 6, which is an Al-14Si-Mg alloy, is shown. It can be seen that the microstructure is densely composed of α-Al, eutectic Si, and eutectic Mg ₂ Si. It can be seen that as the magnesium content increases, the process structure becomes more dense. For example, when the magnesium content is 4.02% by weight or more, primary Mg ₂ Si is generated. On the other hand, during melting and casting, magnesium is oxidized and forms an oxide film such as MgO or MgAl ₂ O ₄ , which may cause casting defects. Although the casting defect did not occur in Experimental Example 3 where the magnesium content was 4.02% by weight, it was confirmed that casting defects occurred in Experimental Example 4 where the magnesium content was 4.50% by weight and Experimental Example 6 where the magnesium content was 5.33% by weight.

Therefore, if the magnesium content is less than 2.7% by weight, it is difficult to form a dense process structure, and if the magnesium content exceeds 4.1% by weight, casting defects may occur. Accordingly, the content of magnesium may range from 2.7% to 4.1% by weight.

Below, the physical properties of aluminum alloy castings that have undergone T6 heat treatment will be described.

Table 2 is a table showing the corrosion resistance, room temperature tensile strength, and high temperature tensile strength of aluminum alloy castings subjected to T6 heat treatment according to an embodiment of the present invention.

classification	corrosion resistance	Tensile strength (MPa)
	corrosion rate (mm/year)	room temperature	200℃	250℃	300℃	350℃
Experimental Example 7	0.0299	299.3	227.0	145.0	72.4	49.2
Experimental Example 8	0.9543	360.3	284.0	215.5	126.5	66.0
Experimental Example 9	0.2505	331.7	278.0	181.0	83.9	54.0
Experimental Example 10	0.0231	265.7	202.0	146.0	69.4	52.6
Experimental Example 11	0.0157	359.5	234.5	178.0	92.5	46.5
Experimental Example 12	0.1260	358.0	290.0	208.0	105.0	62.5
Experimental Example 15	0.0219	352.7	271.0	192.0	92.5	46.0
Experimental Example 16	0.0921	350.3	269.0	221.5	129.0	71.0
Experimental Example 17	0.0866	333.0	267.0	223.5	128.0	74.5
Experimental Example 18	0.1033	353.5	267.5	219.0	134.5	75.5
Experimental Example 19	0.1527	308.5	243.0	214.5	130.5	72.5
Experimental Example 20	0.1751	319.3	256.5	224.0	136.0	73.5
Experimental Example 21	0.1697	312.7	248.5	223.5	135.0	75.0
Experimental Example 22	0.0974	355.5	276.5	211.5	131.0	75.5

Table 2 shows the corrosion resistance, room temperature tensile strength, and high temperature tensile strength of the aluminum alloy cast material that underwent the T6 heat treatment. The corrosion resistance is indicated by the corrosion rate, and the smaller the corrosion rate, the better the corrosion resistance. Room temperature tensile strength was performed at 20°C, and high temperature tensile strength was performed at 200°C, 250°C, 300°C, and 350°C.

Figure 5 is a graph showing the room temperature tensile strength and elongation of an aluminum alloy cast material subjected to T6 heat treatment according to an embodiment of the present invention.

Experimental Example 7, Experimental Example 8, Experimental Example 9, and Experimental Example 10 were alloys based on Al-18Si, and showed low high-temperature tensile strength and elongation, which was attributed to the presence of primary Si due to the high silicon content. is analyzed. In Experimental Examples 8 and 9 containing copper, the room temperature tensile strength was increased and the high temperature tensile strength was slightly increased, but the corrosion resistance was significantly reduced, compared to Experimental Examples 7 and 10 that did not contain copper. It is analyzed as a result of the copper content. In particular, Experimental Example 10, in which 1.88% by weight of magnesium was added along with a high content of silicon, showed significantly low elongation and room temperature tensile strength, which is believed to be due to coarsening of primary Si.

In conclusion, it can be seen that the Al-18Si-based aluminum alloy casting material has low elongation and high-temperature tensile strength, and does not satisfy corrosion resistance when it contains copper. Therefore, a method of reducing the silicon content may be considered.

Experimental Example 11 is an Al-14Si-based alloy, and has excellent corrosion resistance, room temperature tensile strength, and elongation, but does not satisfy the scope of the present invention because it does not contain copper and manganese, and thus has low high-temperature tensile strength.

The effect of copper on the physical properties of the aluminum alloy casting material will be described. Experimental examples that did not contain copper (Experimental Example 7, Experimental Example 10, Experimental Example 11, and Experimental Example 15) had superior corrosion resistance compared to other experimental examples containing copper, but had low high-temperature tensile strength above 250°C. can be seen. Therefore, it is necessary to contain copper in order to increase the high temperature tensile strength of the aluminum alloy casting material.

When compared to the case where the copper content is included at the level of 1% by weight, Experimental Examples 16 to 22 based on Al-14Si have better corrosion resistance than Experimental Example 9 based on Al-18Si, and at 250 ° C. or higher. High temperature tensile strength was increased. In Experimental Example 12, the silicon content was less than 13% by weight, so the corrosion resistance was reduced and the high temperature tensile strength above 250°C was reduced.

From these results, it was confirmed that the silicon content range of more than 13.0% by weight to 15% by weight of the present invention can provide excellent corrosion resistance and high high temperature tensile strength.

When copper is included, a decrease in elongation may occur along with a decrease in corrosion resistance. For example, in the case of having similar silicon and magnesium contents, compared to Experimental Example 11, which does not contain copper, Experimental Examples 16 to 21 had reduced elongation.

Experimental Example 12 is based on Al-14Si and contains copper and manganese in excess of 1% by weight, and has excellent corrosion resistance, but the elongation is reduced and the high-temperature tensile strength is particularly low. It is analyzed that when manganese exceeds 1% by weight, the Al(Fe, Mn)Si phase becomes coarse in the form of a polygon and does not improve interconnectivity, thereby reducing high temperature tensile strength. In addition, the inclusion of manganese can more effectively suppress the decrease in corrosion resistance due to copper content. Therefore, the content of manganese may be 1% by weight or less. Additionally, the content of manganese may be 0.8% by weight or less and may range from 0.3% by weight to 0.7% by weight.

Experimental Example 15 does not contain copper but contains manganese, and the corrosion resistance and room temperature tensile strength are excellent, but the high temperature tensile strength tends to decrease somewhat, but compared to Experimental Example 11, which does not contain manganese, it shows excellent corrosion resistance and room temperature tensile strength up to 250°C. It is analyzed that it improves the high temperature tensile strength of. In addition, compared to Experimental Example 5 or Experimental Example 8, it is analyzed that corrosion resistance, room temperature tensile strength, and high temperature tensile strength are all improved.

Experimental Examples 16 to 22 are alloys within the content range of the present invention, and although the corrosion resistance is somewhat reduced compared to the case without copper, they are within the scope of the present invention, and the high room temperature tensile strength and especially high temperature tensile strength are notable. has increased significantly. In particular, compared to Experimental Examples 8 and 9 containing only copper and not manganese, it was found that the high-temperature tensile strength was increased by including copper and manganese, and it was also possible to prevent a decrease in corrosion resistance due to the addition of copper. You can.

Therefore, it is necessary to include copper in order to improve the high-temperature tensile strength of the aluminum alloy casting material. The copper content that minimizes corrosion resistance degradation may be 2% by weight.

From the results of Experimental Example 18, it is analyzed that zirconium has little effect on corrosion resistance, elongation, and room temperature tensile strength, and improves high temperature tensile strength above 300°C.

From the results of Experimental Example 19, Experimental Example 20, and Experimental Example 21, it is analyzed that nickel has little effect on room temperature tensile strength and improves high temperature tensile strength above 250°C. However, although elongation and corrosion resistance tend to decrease somewhat, it satisfies the scope of the present invention.

Experimental Example 22 is analyzed as an alloy composition showing the best properties in corrosion resistance, elongation, room temperature tensile strength, and high temperature tensile strength.

Hereinafter, the physical properties of aluminum alloy castings subjected to T5 heat treatment will be described.

Below, the T5 heat treatment will be described. In general, the mechanical properties of T5 heat-treated aluminum alloy specimens are significantly lower than those of T6 heat-treated specimens. This creates various crystal phases during casting. When solution treatment is performed like T6 heat treatment, part of the crystalline phase is decomposed and dissolved into solid solution in the aluminum matrix, and the matrix composition becomes uniform. In addition, elements supersaturated and dissolved in the matrix precipitate out during aging treatment and contribute to strength improvement, and corrosion resistance improves as production phase decomposition and matrix composition uniformity increase. On the other hand, if solution treatment is not performed, such as T5 heat treatment, the process of decomposition of the product phase and improvement of matrix composition uniformity is eliminated, so the improvement in properties after aging treatment is limited, resulting in a decrease in strength and corrosion resistance. However, there is an advantage in that manufacturing costs can be reduced by omitting the solution heat treatment, and furthermore, it is possible to prevent distortion of parts that may occur when quenched in water after solution heat treatment. Therefore, recently, as aluminum casting parts have become larger and thinner, distortion of parts has become a major issue, and to compensate for this, the application of T5 heat treatment is increasing.

Table 3 is a table showing the corrosion resistance, room temperature tensile strength, and high temperature tensile strength of aluminum alloy castings subjected to T5 heat treatment according to an embodiment of the present invention.

classification	corrosion resistance	Tensile strength (MPa)
	corrosion rate (mm/year)	room temperature	200℃	250℃	300℃	350℃
Experimental Example 13	0.0344	177.7	150.0	118.0	80.2	49.6
Experimental Example 14	1.1669	215.0	200.0	169.0	106.0	68.5
Experimental Example 23	0.1833	213.0	187.0	138.5	97.5	65.5
Experimental Example 24	0.3826	216.7	184.5	146.5	104.0	71.5
Experimental Example 25	0.2524	210.0	199.0	143.0	104.5	64.0

Table 3 shows the corrosion resistance, room temperature tensile strength, and high temperature tensile strength of the aluminum alloy cast material that underwent the T5 heat treatment. The corrosion resistance is indicated by the corrosion rate, and the smaller the corrosion rate, the better the corrosion resistance. Room temperature tensile strength was performed at 20°C, and high temperature tensile strength was performed at 200°C, 250°C, 300°C, and 350°C.

Figure 6 is a graph showing the room temperature tensile strength and elongation of an aluminum alloy cast material subjected to T5 heat treatment according to an embodiment of the present invention.

When the T5 heat treatment is performed, it can be seen that the overall corrosion resistance, room temperature tensile strength, and high temperature tensile strength are reduced compared to the aluminum alloy casting material that has been subjected to the T6 heat treatment.

Experimental Example 13 had excellent corrosion resistance, but the room temperature tensile strength and high temperature tensile strength were significantly low.

Experimental Example 14 is a case containing only copper, and when compared with Experimental Example 13 not containing copper and manganese, room temperature tensile strength and high temperature tensile strength were increased, but corrosion resistance was significantly reduced.

Experimental Examples 23 and 25 contained copper and manganese, and the room temperature tensile strength and high temperature tensile strength were significantly increased compared to Experimental Example 13 and slightly lower than Experimental Example 14. Corrosion resistance was lower than that of Experimental Example 13, but was significantly improved compared to Experimental Example 14. Additionally, the elongation was significantly increased compared to Experimental Examples 13 and 14.

Experimental Example 24 is a case in which copper and manganese are included and further nickel is included, and the room temperature tensile strength and high temperature tensile strength are increased, showing a value at the level of Experimental Example 14. Corrosion resistance was lower than that of Experimental Example 13, but was significantly improved compared to Experimental Example 14. Additionally, the elongation was significantly increased compared to Experimental Examples 13 and 14.

Figure 7 is a graph calculated by thermodynamic calculation of the fraction of the formed phase upon addition of copper in an aluminum alloy casting material according to an embodiment of the present invention.

Referring to FIG. 7, the results of thermodynamic calculation of the phase fraction produced when copper is added to an Al-Si-Mg ternary alloy are shown. Since Experimental Examples 7 and 10 do not contain copper, the Cu-containing phase does not appear, but the Mg-containing phase appears. Since Experimental Examples 8 and 9 contain copper, Cu-containing phases and Mg-containing phases appear, and in Experimental Example 8, which contains more copper, more Cu-containing phases appear.

Since Experimental Example 15 does not contain copper, the Cu-containing phase does not appear, but the Mg-containing phase appears. When calculating the fraction of the produced phase while increasing the copper content in Experimental Example 15, it can be seen that the fraction of the Cu-containing phase increases and at the same time, the fraction of the Mg-containing phase decreases. That is, when copper is added, the copper reacts with aluminum, silicon, and magnesium to form a Cu-rich phase such as CuAl ₂ and AlCuMgSi. As the copper content increases, the fraction of the Cu-containing phase increases. On the other hand, the fraction of Mg-rich phase such as Mg ₂ Si and AlFeMgSi, which are effective for corrosion resistance, decreases. In other words, as the copper content increases, high-temperature tensile strength increases but corrosion resistance decreases.

It is analyzed that at a copper content of 2.5% by weight, high-temperature tensile strength is advantageous, but corrosion resistance is reduced. Therefore, in the present invention, considering the combination of high-temperature tensile strength and corrosion resistance, the copper content may be 2.0% by weight or less. Additionally, the copper content may be 1.61% by weight or less.

Figure 8 is a graph calculated by thermodynamic calculation of the fraction of phases formed upon adding nickel in an aluminum alloy casting material according to an embodiment of the present invention.

Referring to FIG. 8, based on the composition of Experimental Example 15 in the Al-Si-Mg ternary alloy, copper was added in an amount of 1% or 2% by weight, and nickel was added in an increasing range from 0% by weight to 2.0% by weight. This is the result of thermodynamic calculation of the changes in the Mg-containing phase and Ni-containing phase. When nickel was added, the fraction of the Mg-containing phase did not change for all copper compositions. The fraction of the Ni-containing phase increased linearly, which was the same for the copper composition. It is analyzed that the fraction of the Ni-containing phase does not affect the fraction of the Mg-containing phase.

When nickel (Ni) is added to the approximate ternary composition of Al-Si-Mg ₂ Si, nickel reacts with aluminum, copper, iron, etc. to form Ni-rich phases such as Al ₃ Ni, AlCuNi, and AlFeNi. form As the nickel content increases, the fraction of the Ni-containing phase increases, and the high-temperature tensile strength increases but the corrosion resistance decreases. It is analyzed that at a nickel content of 2.0% by weight, high temperature tensile strength is advantageous, but corrosion resistance is likely to decrease. Therefore, in the present invention, considering the combination of high-temperature tensile strength and corrosion resistance, the nickel content may be 1.5% by weight or less. Additionally, the nickel content may be 1.0% by weight or less.

When zirconium (Zr) is added to the approximate ternary eutectic composition of Al-Si-Mg ₂ Si, zirconium reacts with aluminum, silicon, etc. to form a product phase such as AlSiZr. As the zirconium content increases, the fraction of the produced phase increases and its size becomes coarse. The addition of zirconium improves high-temperature tensile strength without almost deteriorating corrosion resistance. However, zirconium is a high-melting point element, so as the content increases, the dissolution temperature must increase when dissolving. Since a large amount of magnesium is added to the approximate ternary eutectic composition of Al-Si-Mg ₂ Si, as the dissolution temperature increases, the production of magnesium oxide increases, which may increase the amount of defects. According to the Al-Zr binary phase diagram, the liquidus line of 0.25% by weight zirconium is 740°C, and the liquidus line of 0.3% by weight zirconium is 760°C. Therefore, in the present invention, considering the dissolution temperature, the zirconium content may be 0.25% by weight or less.

In addition to the above added elements, chromium (Cr), molybdenum (Mo), etc. are analyzed to have a similar effect to manganese (Mn), and titanium (Ti), vanadium (V), etc. are expected to have a similar effect to zirconium (Zr). is analyzed. Therefore, the aluminum alloy casting material according to the technical idea of the present invention may further include at least one of chromium (Cr), molybdenum (Mo), titanium (Ti), and vanadium (V).

In addition, 0.2% or less of TiB ₂ , TiC, AlB _{2 ,} etc. is added as a grain refiner in aluminum alloy castings. For grain refinement of an alloy with an approximate ternary eutectic composition of Al-Si-Mg ₂ Si, the refiner is added to 0.2%. The following can be added. Generally, in hypoeutectic and eutectic Al-Si alloys, 50 ppm to 200 ppm of Sr is added to refine eutectic Si, and in eutectic and hypereutectic Al-Si alloys where primary Si is produced, P ( AlP form) is added at 30 ppm to 200 ppm. Even in the approximate ternary eutectic composition of Al-Si-Mg ₂ Si, 30 to 200 ppm of P (in the form of AlP) can be added as needed in compositions with a large amount of primary Si produced, and 50 ppm of Sr can be added in compositions with a small amount of primary Si produced. It can be added from ppm to 200 ppm. Therefore, the aluminum alloy casting material according to the technical idea of the present invention may further include at least one of titanium (Ti), boron (B), and strontium (Sr).

9 and 10 are optical microscope photographs showing the microstructure of an aluminum alloy cast material according to an embodiment of the present invention.

Referring to Figure 9, the microstructure of Experimental Example 21 is shown at low and high magnification. Experimental Example 21 is a case where copper (Cu), manganese (Mn), nickel (Ni), and zirconium (Zr) along with silicon (Si) and magnesium (Mg) are included within the scope of the present invention, and eutectic Si (eutectic It can be confirmed that it has a dense microstructure composed of Si) and eutectic Mg ₂ Si, and that primary Si (primary Si) and primary Mg ₂ Si are also formed in trace amounts. At high magnification, it can be seen that intermetallic compounds are formed in various crystalline phases by the addition of magnesium (Mg), copper (Cu), manganese (Mn), nickel (Ni), and zirconium (Zr).

Referring to Figure 10, the microstructures of Experimental Examples 12 and 22 are shown. Experimental Examples 12 and 22 contain similar amounts of silicon (Si), magnesium (Mg), and copper (Cu), but in Experimental Example 12, the manganese content is 1.34% by weight, which exceeds 1% by weight, and Example 22 is 0.344% by weight, which is 1% by weight or less. As described above, it can be seen that as the content of manganese increases, the fraction of the Al(Fe, Mn)Si formation phase increases and its size also becomes coarse.

Figure 11 is a schematic diagram showing a brake system including a brake disc formed of aluminum alloy casting according to an embodiment of the present invention.

Referring to FIG. 11, the brake system 100 includes a brake disc 120 inserted into the rotation shaft 110 of a vehicle, and a brake pad (brake pad) that slows down the rotation of the brake disc 120 by frictional contact with the brake disc 120. 130), and a caliper that secures the brake pads 130 to be disposed on both outer sides of the brake disc 120.

The brake disc 120 may be made of an aluminum alloy casting material having the composition described above. The brake disc 120 includes, for example, more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 2% copper (Cu) by weight; and the remainder may be composed of aluminum alloy casting material containing aluminum (Al) and inevitable impurities. The brake disc 120 includes, for example, more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 2% copper (Cu) by weight; Greater than 0% to 1.0% by weight manganese (Mn); and the remainder may be composed of aluminum alloy casting material containing aluminum (Al) and inevitable impurities. The brake disc 120 includes, for example, more than 13.0% by weight to 15% by weight of silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 1% by weight manganese (Mn); and the remainder may be composed of aluminum alloy casting material containing aluminum (Al) and inevitable impurities.

The aluminum alloy casting materials may further include nickel (Ni) in an amount of more than 0% by weight to 1.5% by weight in addition to the above elements, or may further include zirconium (Zr) in an amount of more than 0% by weight to 0.25% by weight in addition to the elements. or more than 0% by weight to 1.5% by weight of nickel (Ni) in addition to the above elements; And it may further include zirconium (Zr) in an amount of more than 0% by weight to 0.25% by weight. The aluminum alloy casting materials include titanium (Ti) in an amount of more than 0% by weight to 0.05% by weight in addition to the above elements; And it may further include boron (B) in an amount of more than 0% by weight to 0.005% by weight. The aluminum alloy casting materials may further include iron (Fe) in an amount of more than 0% by weight to 0.2% by weight as an inevitable impurity in addition to the above elements. The aluminum alloy casting material may further contain 30 ppm to 200 ppm of phosphorus. The phosphorus may be included in the form of AlP. Additionally, the aluminum alloy casting material may further include 50 ppm to 200 ppm of strontium (Sr).

The brake disc 120 includes, for example, more than 13.0% by weight to 15% by weight of silicon (Si); 2.81% to 3.5% magnesium (Mg) by weight; 0.021% to 1.603% by weight copper (Cu); 0.002% to 0.537% by weight manganese (Mn); and the remainder may be composed of aluminum alloy casting material containing aluminum (Al) and inevitable impurities. Additionally, the content of silicon (Si) contained in the aluminum alloy casting may range from 13.3% by weight to 14.6% by weight. The aluminum alloy casting material may further include 0.021% to 0.641% by weight of nickel (Ni) in addition to the above elements, or may further include 0.004% to 0.185% by weight of zirconium (Zr) in addition to the above elements. 0.021% to 0.641% by weight of nickel (Ni) in addition to the element; And it may further include 0.004% by weight to 0.185% by weight of zirconium (Zr). The aluminum alloy casting material includes, in addition to the above elements, 0.034% by weight to 0.040% by weight of titanium (Ti); And it may further include 0.001% by weight to 0.004% by weight of boron (B). In addition to the above elements, the aluminum alloy casting material may further include 0.120% by weight to 0.158% by weight of iron (Fe) as the inevitable impurity. The aluminum alloy casting material may further contain 30 ppm to 200 ppm of phosphorus. The phosphorus may be included in the form of AlP. Additionally, the aluminum alloy casting material may further include 50 ppm to 200 ppm of strontium (Sr).

The aluminum alloy casting material can be applied to parts of transportation such as automobiles, ships, or aircraft, and can be applied to various parts manufactured by die casting, for example. However, this is illustrative and the technical idea of the present invention is not limited to this use.

The present invention has been described with reference to the embodiments shown in the drawings, but these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the attached patent claims.

According to an embodiment of the present invention made as described above, an aluminum alloy casting material having high high-temperature strength and excellent corrosion resistance and wear resistance can be provided by controlling the alloy composition and content of copper and manganese. Additionally, a brake disc for an electric vehicle can be manufactured using the alloy.

Claims (15)

Greater than 13.0% to 15% by weight silicon (Si);

2.7% to 4.1% magnesium (Mg) by weight;

Greater than 0% to 2% copper (Cu) by weight; and

The remainder contains aluminum (Al) and inevitable impurities.

Aluminum alloy casting material.

According to claim 1,

Further comprising greater than 0% to 1.0% by weight of manganese (Mn),

Aluminum alloy casting material.

According to claim 1,

Further comprising greater than 0% to 1.5% by weight of nickel (Ni),

Aluminum alloy casting material.

According to claim 1,

Further comprising greater than 0% to 0.25% by weight of zirconium (Zr),

Aluminum alloy casting material.

According to claim 1,

Greater than 0% to 0.05% by weight titanium (Ti); and

More than 0% by weight to 0.005% by weight of boron (B);

Aluminum alloy casting material.

According to claim 1,

The aluminum alloy cast material has a microstructure consisting of at least one of eutectic Si, eutectic Mg ₂ Si, primary Si, and primary Mg ₂ Si,

Aluminum alloy casting material.

According to claim 1,

The aluminum alloy casting material,

Having a corrosion rate of less than 0.2 mm/year,

Aluminum alloy casting material.

According to claim 1,

The aluminum alloy casting material,

Having a high temperature tensile strength at 250°C ranging from 190 MPa to 230 MPa,

Aluminum alloy casting material.

According to claim 1,

The aluminum alloy casting material is solution treated and then aged.

Aluminum alloy casting material.

According to claim 1,

The aluminum alloy casting material is aged without solution treatment,

Aluminum alloy casting material.

According to claim 1,

The aluminum alloy casting material,

Greater than 13.0% to 15% by weight silicon (Si);

2.81% to 3.5% magnesium (Mg) by weight;

0.021% to 1.603% by weight copper (Cu);

0.002% to 0.537% by weight manganese (Mn); and

The remainder contains aluminum (Al) and inevitable impurities.

Aluminum alloy casting material.

According to claim 11,

Further comprising 0.021% to 0.641% by weight of nickel (Ni),

Aluminum alloy casting material.

According to claim 11,

Further comprising 0.004% to 0.185% by weight of zirconium (Zr),

Aluminum alloy casting material.

Greater than 13.0% to 15% by weight silicon (Si);

2.7% to 4.1% magnesium (Mg) by weight;

Greater than 0% to 1% by weight manganese (Mn); and

The remainder contains aluminum (Al) and inevitable impurities.

Aluminum alloy casting material.

Greater than 13.0% to 15% by weight silicon (Si); 2.7% to 4.1% magnesium (Mg) by weight; Greater than 0% to 2% copper (Cu) by weight; and the remainder is composed of aluminum alloy casting material containing aluminum (Al) and inevitable impurities,

brake disc.

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