Automobile wheel hub and method for manufacturing the same

Abstract

The application discloses an automobile wheel hub and a preparation method thereof. The automobile wheel hub comprises Si, Mg, Ti, Fe, Mn, P, Sb, Zn, Cu, Pb, Sn, Cr, Ni, RE, Sr and Al; wherein the RE must contain Sc and further contains at least one selected from La and Ce. The automobile wheel hub has a smaller secondary dendrite arm spacing in the structure.

Description

Technical Field

[0001] This invention relates to an automobile wheel hub and its manufacturing method. Background Technology

[0002] Cast aluminum alloys are aluminum alloys with Al as the matrix and Si and Mg as the main alloying elements, which can be strengthened by heat treatment. Cast aluminum alloys possess high strength and plasticity, excellent fluidity and castability, and the shells cast from them have high airtightness, making them ideal materials for producing automobile wheel hubs. However, the mechanical properties of cast aluminum alloys still need further improvement.

[0003] CN102366828A discloses a low-pressure casting method for aluminum alloy automobile wheel hubs, which is formulated with the following mass percentages: Si 6.8-7.2%, Mg 0.6-1.0%, Ti 0.1-0.2%, Cu 0.5-0.8%, Zn 0.2-0.5%; the total amount of impurity elements such as Fe, Mn, Sn, and Pb does not exceed 0.5%, and the remainder is Al. The prepared aluminum alloy is heated and melted in a melting furnace. After the alloy is completely melted, the temperature of the molten aluminum is adjusted to 760–770°C, and a finer Al-Ti-BC refining agent is added at a rate of 0.1–0.2% of the total mass of the molten alloy. The temperature of the molten aluminum is then adjusted to 750–760°C, and a rare earth modifier is added at a rate of 0.3–0.5% of the total mass of the molten alloy. The temperature of the molten aluminum is then adjusted to 710–730°C, and a refining agent is added at a rate of 0.5–0.6% of the total mass of the molten alloy. Finally, slag is skimmed off, and the molten aluminum alloy is transferred to a low-pressure casting machine holding furnace for pouring. The mold is closed and locked for casting, and the casting is removed. The automotive wheel hub casting undergoes solution treatment followed by complete artificial aging heat treatment. This application does not disclose the composition of the rare earth modifier.

[0004] CN116103543A discloses a recycled high thermal conductivity die-cast aluminum alloy containing rare earth elements. Its chemical composition and the mass percentage of each chemical component are as follows: Si 9.0–12.0%, Fe 0.6–1.2%, Cu 0.5–3.0%, Mg 0.1–1.0%, Zn 0.1–1.0%, Mn 0.05–0.4%, Cr 0.03–0.2%, Ti 0.05–0.2%, Ni 0.05–0.2%, Sn≤0.05%, Zr≤0.05%, V≤0.05%, Cd≤0.01%, Pb≤0.01%, Sr 0.01–0.1%, La 0.03–0.3%, Ce The alloy contains 0.03-0.3% aluminum, with individual impurities ≤0.03% and total impurities ≤0.15%, with the balance being aluminum. This alloy has low tensile strength and elongation, making it unsuitable for use as automotive wheel hubs.

[0005] CN116219233A discloses a high thermal conductivity cast aluminum alloy, comprising, by weight percentage: Si: 7.5–9.5%, Fe: 0.5–0.8%, Cu: 0.05–0.15%, Mg: 0.1–0.2%, Sr: 0.3–0.6%, B: 0.005–0.02%, Re: 0.01–0.02%, Zn: 0.05–0.15%, Mn: 0.01–0.1%. The aluminum alloy contains the following components: Ti: 0.002–0.008%, V: 0.001–0.006%, Cr: 0.02–0.08%, Pb: 0.005–0.015%, Sn: 0.01–0.02%, Sb: 0.002–0.006%, with the balance being Al. The chemical composition of the aluminum alloy satisfies the following relationship: 5 ≤ (Ti + V + Cr + Mn) / B ≤ 35, Si + Sr ≥ 8.0%. This document does not disclose the element Re, and the alloy has low elongation and tensile strength, making it unsuitable for use as automotive wheel hubs. Summary of the Invention

[0006] One object of the present invention is to provide an automobile wheel hub with a small secondary branching spacing in its metallographic structure. Further, the automobile wheel hub has high tensile strength. Even further, the automobile wheel hub has high yield strength and / or elongation. Another object of the present invention is to provide a method for manufacturing an automobile wheel hub.

[0007] The present invention achieves the above objectives through the following technical solutions.

[0008] On one hand, the present invention provides an automobile wheel hub comprising Si 6.8–7.5 wt%, Mg 0.25–0.35 wt%, Ti 0.05–0.15 wt%, Fe 0.05–0.15 wt%, Mn 0.01–0.05 wt%, P 0.0005–0.003 wt%, Sb 0.003–0.01 wt%, Zn 0.01–0.045 wt%, Cu 0.003–0.01 wt%, Pb 0.01–0.05 wt%, Sn 0.01–0.05 wt%, Cr 0.01–0.05 wt%, Ni 0.005–0.015 wt%, RE 0.025–0.07 wt%, Sr 0.007–0.025 wt%, and Al 91–93 wt%.

[0009] The RE must contain Sc, and also contain at least one selected from La and Ce.

[0010] According to the present invention, the content of RE in the automobile wheel hub is preferably 0.03 to 0.065 wt%.

[0011] According to the present invention, the content of RE in the automobile wheel hub is preferably 0.05 to 0.055 wt%.

[0012] According to the present invention, in the automotive wheel hub, preferably, the content of Sc in RE is 15-60 wt%.

[0013] According to the present invention, the RE is preferably selected from one of the following combinations:

[0014] (A) Sc and La;

[0015] (B)Sc and Ce.

[0016] According to the present invention, the automobile wheel hub preferably has RE as combination (A), Sc content of 0.01-0.02 wt%, and La content of 0.01-0.045 wt%.

[0017] Alternatively, RE is combination (B), with Sc content of 0.01–0.02 wt% and Ce content of 0.01–0.03 wt%.

[0018] According to the present invention, the secondary branch spacing of the automobile wheel hub is preferably ≤26μm.

[0019] According to the present invention, the automobile wheel hub preferably has a tensile strength ≥265MPa, a yield strength ≥180MPa, and an elongation ≥12.5%.

[0020] On the other hand, the present invention provides a method for manufacturing an automobile wheel hub, comprising the following steps:

[0021] (1) Provide an alloy liquid formed according to the composition of automobile wheel hubs;

[0022] (2) Add rare earth aluminum alloy to the alloy liquid to obtain the first melt;

[0023] (3) Add aluminum-strontium alloy and aluminum-titanium-boron alloy to the first melt to obtain the second melt;

[0024] (4) Cast the second melt to obtain a billet;

[0025] (5) Heat treat the blank to obtain the car wheel hub.

[0026] According to the preparation method of the present invention, preferably, in step (2), after the rare earth aluminum alloy is added, the mixture is stirred for 5 to 20 minutes, and then degassed; after degassed, a refining agent is added to obtain the first melt;

[0027] In step (3), after the aluminum-strontium alloy and the aluminum-titanium-boron alloy melt, they are stirred evenly; then the slag is removed to obtain the second melt.

[0028] In step (4), casting is carried out in a low-pressure casting machine.

[0029] The automotive wheel hub of the present invention reduces the secondary branching spacing through the cooperation between various elements. Furthermore, the automotive wheel hub of the present invention has higher tensile strength, yield strength, and elongation. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the shape of the specimen used to test the mechanical properties of automobile wheel hubs in this invention.

[0031] Figure 2 This is a metallographic diagram of the outer rim portion of the automobile wheel hub in Example 1.

[0032] Figure 3 This is a metallographic diagram of the outer rim portion of the automobile wheel hub in Example 2.

[0033] Figure 4 This is a metallographic diagram of the outer rim portion of the automobile wheel hub in Example 3.

[0034] The attached figures are labeled as follows:

[0035] 1-Rock section; 2-Head; 3-Frustum; 31-Arc surface. Detailed Implementation

[0036] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0037] <Car Wheels>

[0038] The automobile wheel hub of the present invention comprises Si, Mg, Ti, Fe, Mn, P, Sb, Zn, Cu, Pb, Sn, Cr, Ni, RE, Sr and Al.

[0039] In the automobile wheel hub of the present invention, the Si content is 6.8 to 7.5 wt%; preferably 7.0 to 7.2 wt%; more preferably 7.0 to 7.1 wt%.

[0040] In the automobile wheel hub of the present invention, the content of Mg is 0.25-0.35 wt%; preferably 0.3-0.33 wt%; more preferably 0.32-0.33 wt%.

[0041] In the automobile wheel hub of the present invention, the Ti content is 0.05 to 0.15 wt%; preferably 0.1 to 0.13 wt%; more preferably 0.11 to 0.12 wt%.

[0042] In the automobile wheel hub of the present invention, the Fe content is 0.05 to 0.15 wt%; preferably 0.08 to 0.12 wt%; more preferably 0.09 to 0.1 wt%.

[0043] In the automobile wheel hub of the present invention, the content of Mn is 0.01 to 0.05 wt%; preferably 0.02 to 0.04 wt%; more preferably 0.02 to 0.03 wt%.

[0044] In the automobile wheel hub of the present invention, the content of P is 0.0005 to 0.003 wt%; preferably 0.001 to 0.0025 wt%; more preferably 0.002 to 0.0022 wt%.

[0045] In the automobile wheel hub of the present invention, the Sb content is 0.003 to 0.01%; preferably 0.005 to 0.008 wt%; more preferably 0.006 to 0.007 wt%.

[0046] In the automobile wheel hub of the present invention, the Zn content is 0.01 to 0.045 wt%; preferably 0.015 to 0.035 wt%; more preferably 0.025 to 0.03 wt%.

[0047] In the automobile wheel hub of the present invention, the Cu content is 0.003 to 0.01 wt%; preferably 0.004 to 0.007 wt%; more preferably 0.005 to 0.006 wt%.

[0048] In the automobile wheel hub of the present invention, the Pb content is 0.01 to 0.05 wt%; preferably 0.02 to 0.04 wt%; more preferably 0.03 to 0.035 wt%.

[0049] In the automobile wheel hub of the present invention, the Sn content is 0.01 to 0.05 wt%; preferably 0.02 to 0.04 wt%; more preferably 0.03 to 0.04 wt%.

[0050] In the automobile wheel hub of the present invention, the Cr content is 0.01 to 0.05 wt%; preferably 0.02 to 0.04 wt%; more preferably 0.02 to 0.03 wt%.

[0051] In the automobile wheel hub of the present invention, the Ni content is 0.005 to 0.015 wt%; preferably 0.007 to 0.012 wt%; more preferably 0.009 to 0.01 wt%.

[0052] In the automobile wheel hub of the present invention, the content of RE is 0.025 to 0.07 wt%; preferably 0.03 to 0.065 wt%; more preferably 0.05 to 0.052 wt%.

[0053] RE must contain Sc and at least one selected from La and Ce. Preferably, RE is selected from one of the following combinations: (A) Sc and La; (B) Sc and Ce. More preferably, RE is Sc and La.

[0054] The content of Sc in RE is 15-60 wt%; preferably 20-55 wt%; more preferably 25-30 wt%.

[0055] In the automobile wheel hub of the present invention, the content of Sc can be 0.01 to 0.02 wt%; preferably 0.013 to 0.018 wt%; more preferably 0.015 to 0.016 wt%.

[0056] In the automobile wheel hub of the present invention, the content of La can be 0.01 to 0.045 wt%; preferably 0.016 to 0.04 wt%; more preferably 0.035 to 0.037 wt%.

[0057] In the automobile wheel hub of the present invention, the Ce content can be 0.01 to 0.03 wt%; preferably 0.015 to 0.02 wt%; more preferably 0.016 to 0.018 wt%.

[0058] In the automobile wheel hub of the present invention, the Sr content is 0.007 to 0.025 wt%; preferably 0.01 to 0.02 wt%; more preferably 0.012 to 0.015 wt%.

[0059] In the automobile wheel hub of the present invention, the Al content is 91-93 wt%; preferably 91.5-92.5 wt%; more preferably 92.0-92.2 wt%.

[0060] In the metallographic structure of the automobile wheel hub of the present invention, the secondary branch spacing is less than or equal to 26 μm; preferably, it is less than or equal to 25 μm. In some embodiments, the secondary branch spacing can be greater than or equal to 20 μm; or greater than or equal to 22 μm.

[0061] The tensile strength of the automobile wheel hub of the present invention is greater than or equal to 265 MPa; preferably, greater than or equal to 270 MPa; more preferably, greater than or equal to 272 MPa. In some embodiments, the tensile strength may be less than or equal to 290 MPa; or less than or equal to 280 MPa.

[0062] The yield strength of the automobile wheel hub of the present invention is greater than or equal to 180 MPa; preferably, greater than or equal to 185 MPa; more preferably, greater than or equal to 188 MPa. In some embodiments, the tensile strength may be less than or equal to 195 MPa; or less than or equal to 190 MPa.

[0063] The elongation of the automotive wheel hub of the present invention is greater than or equal to 12.5%; preferably, greater than or equal to 13%. In some embodiments, the elongation may be less than or equal to 15%; or less than or equal to 14%.

[0064] The automobile wheel hub of the present invention has high tensile strength, yield strength and elongation, which can meet the mechanical properties of automobile wheel hubs.

[0065] <Manufacturing Methods of Automobile Wheel Hubs>

[0066] The method for preparing an automobile wheel hub of the present invention includes the following steps: (1) providing an alloy liquid; (2) preparing a first melt; (3) preparing a second melt; (4) casting; and (5) heat treatment.

[0067] Steps for providing alloy liquid

[0068] Provides alloy liquid formed according to the composition of automobile wheel hubs.

[0069] The raw materials can be melted to obtain a liquid alloy. The composition of the raw materials can be configured according to the composition of the automobile wheel hub. The raw materials may include aluminum ingots, metallic silicon, and magnesium ingots. The purity of the aluminum ingots can be greater than or equal to 99.5%; preferably, greater than or equal to 99.7%. The purity of the magnesium ingots can be greater than or equal to 99.5%; preferably, greater than or equal to 99.9%.

[0070] Steps for preparing the first melt

[0071] Rare earth aluminum alloy is added to the alloy liquid to obtain the first melt.

[0072] The rare earth elements in the rare earth aluminum alloy are determined based on the types of rare earth elements contained in the automobile wheel hub. The rare earth aluminum alloy can be selected from one or more of lanthanum aluminum alloy, cerium aluminum alloy, and scandium aluminum alloy. The content of rare earth elements in the rare earth aluminum alloy can be 1–15 wt%. In some embodiments, the content of rare earth elements is 1.5–2.8 wt%. In other embodiments, the content of rare earth elements is 9–11 wt%.

[0073] In some embodiments, a first rare earth aluminum alloy and a second rare earth aluminum alloy are added to the alloy liquid.

[0074] The first rare earth aluminum alloy is selected from lanthanum aluminum alloy and cerium aluminum alloy. The amount of the first rare earth aluminum alloy can be 0.1% to 0.5% of the mass of the alloy liquid; preferably 0.35% to 0.4%.

[0075] The second rare-earth aluminum alloy is a scandium-aluminum alloy. The amount of the second rare-earth aluminum alloy can be 0.5% to 1.0% of the mass of the alloy liquid; preferably 0.6% to 0.7%.

[0076] In some embodiments, after the rare earth aluminum alloy is added, the mixture is stirred and then degassed; after degassed, a refining agent is added to obtain the first melt.

[0077] The stirring time can be 5 to 20 minutes; preferably 10 to 15 minutes.

[0078] The refining agent can be A700-R refining agent. The amount of refining agent used can be 0.1% to 0.8% of the mass of the alloy liquid; preferably 0.3% to 0.5%.

[0079] Steps for preparing the second melt

[0080] An aluminum-strontium alloy and an aluminum-titanium-boron alloy are added to the first melt to obtain a second melt.

[0081] In aluminum-strontium alloys, the strontium content can be 5-15 wt%; preferably 10-12 wt%.

[0082] The amount of aluminum-strontium alloy used can be 0.1% to 0.25% of the mass of the alloy liquid; preferably 0.12% to 0.16%.

[0083] In aluminum-titanium-boron alloys, the titanium content can be 3–8 wt%, preferably 4–5 wt%. The boron content can be 0.2–1 wt%, preferably 0.5–0.8 wt%.

[0084] The amount of aluminum-titanium-boron alloy used can be 1 to 4% of the mass of the alloy liquid; preferably 2 to 2.5%.

[0085] In some embodiments, after the aluminum-strontium alloy and the aluminum-titanium-boron alloy are melted, they are stirred evenly; then the slag is removed to obtain a second melt.

[0086] Casting steps

[0087] The second melt is cast to obtain a billet. Casting can be carried out in a low-pressure casting machine.

[0088] The temperature of the second melt can be 650–750°C; preferably 690–700°C.

[0089] The low-pressure casting mold can be preheated to 200-250°C; preferably 220-240°C.

[0090] The lifting pressure can be 0.01–0.05 MPa; preferably 0.02–0.03 MPa. The lifting speed can be 5–10 cm / s; preferably 6–8 cm / s. The lifting time can be 5–8 s.

[0091] The preferred time is 6 to 7 seconds.

[0092] The filling pressure can be 0.05–0.09 MPa; preferably 0.06–0.08 MPa. The filling speed can be 3–10 cm / s; preferably 5–8 cm / s. The filling time can be 9–14 s.

[0093] The preferred time is 10 to 12 seconds.

[0094] The holding pressure can be 0.09–0.12 MPa; preferably 0.10–0.11 MPa. The holding time can be 60–100 s; preferably 80–90 s.

[0095] Heat treatment steps

[0096] The billet is heat-treated to obtain the automobile wheel hub. Specifically, the billet is solution-treated and then water-quenched to obtain a solution-treated billet. The solution-treated billet is then aged and cooled to obtain the automobile wheel hub.

[0097] The solution temperature can be 490–550℃; preferably 510–530℃. The solution time can be 3–12 h; preferably 5–10 h.

[0098] Water quenching can be carried out in hot water at a temperature of 50–90°C; preferably, water quenching is carried out in hot water at a temperature of 60–80°C.

[0099] The aging temperature can be 100–150℃; preferably 120–140℃. The aging time can be 1–6 hours; preferably 2–4 hours.

[0100] Cooling can be achieved through natural cooling.

[0101] The testing method is described below:

[0102] Tensile strength, yield strength and elongation were tested according to the methods specified in GB / T228.1-2010 Metallic materials, tensile testing - Part 1: Test method at room temperature.

[0103] The sample used is as follows Figure 1 As shown. The specimen is dumbbell-shaped, with a rod 1 and two heads 2 connected to both ends of the rod 1. The rod 1 and the two heads 2 are connected by frustums 3. The upper base of the frustum 3 is connected to the rod 1 and has the same diameter as the rod 1. The lower base of the frustum 3 is connected to the heads 2 and has the same diameter as the heads 2. The side of the frustum 3 is a concave arc surface 31. The length of the rod 1 is 27.5 mm, and the diameter is 5 ± 0.05 mm. The total length of the rod 1 and the two frustums 3 is 34 mm. The diameter of the heads 2 is 9 mm. The total length of the specimen (the sum of the lengths of the rod 1, the two frustums 3, and the two heads 2) is 64 mm. The original gauge length L0 is 25 mm.

[0104] The specific testing procedures are as follows: For each type of automotive wheel hub, parallel specimens were selected from at least six different locations for tensile testing. Before testing, the specimens were successively polished with 800#, 1000#, and 2000# sandpaper to ensure a smooth and free surface. The specimens were subjected to tensile testing at room temperature using an INSTRON-5982 electronic universal testing machine, with the tensile rate set to 1 mm / min. Six specimens were tested for each type of automotive wheel hub, and the maximum and minimum values ​​were removed before taking the average value.

[0105] The secondary branching spacing was tested using the following method: metallographic images were acquired using a Zeiss Axioscope 5 optical microscope, and the secondary branching spacing was measured and averaged using metallographic analysis software.

[0106] The content of various elements in the car wheel hub was tested using an ICPS-8100 inductively coupled plasma optical emission spectrometer (ICP-AES).

[0107] Examples 1-3

[0108] The prepared raw materials are melted according to the composition of the automobile wheel hub to obtain an alloy liquid. The raw materials include aluminum ingots with a purity of 99.7% or higher, metallic silicon, and magnesium ingots with a purity of 99.9% or higher.

[0109] The first rare earth aluminum alloy and the second rare earth aluminum alloy were added to the alloy liquid; after stirring for 10 minutes, the gas was removed, and then A-700R refining agent (purchased from Qingdao Fusaike Casting Materials Co., Ltd.) was sprinkled on the surface of the alloy liquid to obtain the first melt.

[0110] An aluminum-strontium alloy (strontium content 10 wt%) and an aluminum-titanium-boron alloy (titanium content 5.0 wt% and boron content 0.6 wt%) were added to the first melt. After the aluminum-strontium alloy and the aluminum-titanium-boron alloy melted, they were stirred evenly; then, the scum on the surface was skimmed off with a spoon to obtain the second melt.

[0111] The second melt at 700℃ was cast using a low-pressure casting machine to obtain a billet. The specific process conditions are as follows: the mold is preheated to 230℃, the liquid lifting pressure is 0.03MPa, the liquid lifting speed is 7cm / s, and the liquid lifting time is 6s; the filling pressure is 0.07MPa, the filling speed is 6cm / s, and the filling time is 11s; the holding pressure is 0.10MPa, and the holding time is 80s.

[0112] The billet was solution treated at 520℃ for 8 hours, and then water quenched in hot water at 70℃ to obtain the solution-treated billet. The solution-treated billet was then aged at 130℃ for 3 hours, and then naturally cooled to obtain the automobile wheel hub.

[0113] Specific parameters are shown in Table 1. The elemental composition of the obtained automobile wheel hub is shown in Table 2, as are the tensile strength, yield strength, elongation, and secondary branch spacing of the obtained automobile wheel hub.

[0114] Table 1

[0115]

[0116]

[0117] Comparative Example 1

[0118] Except for omitting the first and second rare earth aluminum alloys and adjusting the composition of the raw materials according to the composition of the automobile wheel hub, the rest is the same as in Example 1. The elemental composition of the obtained alloy is shown in Table 2, and the tensile strength, yield strength, elongation, and secondary branch spacing of the obtained automobile wheel hub are also shown in Table 2.

[0119] Table 2

[0120] Si content (wt%) 7.2 7.0 7.1 7.0 Mg content (wt%) 0.30 0.33 0.31 0.33 Ti content (wt%) 0.1 0.12 0.12 0.1 Fe content (wt%) 0.10 0.09 0.08 0.085 Mn content (wt%) 0.03 0.02 0.03 0.03 P content (wt%) 0.001 0.002 0.0015 0.0015 Sb content (wt%) 0.008 0.006 0.007 0.007 Zn content (wt%) 0.020 0.030 0.017 0.017 Cu content (wt%) 0.005 0.005 0.005 0.005 Pb content (wt%) 0.03 0.03 0.02 0.02 Sn content (wt%) 0.02 0.03 0.03 0.03 Cr content (wt%) 0.03 0.02 0.03 0.03 Ni content (wt%) 0.009 0.009 0.009 0.009 La content (wt%) 0.018 0.037 -- -- Sc content (wt%) 0.016 0.015 0.018 -- Ce content (wt%) -- -- 0.016 -- Sr content (wt%) 0.014 0.015 0.015 0.014 Al content (wt%) 92.1 92.2 92.1 92.3 Tensile strength (MPa) 268.58 272.39 270.54 255.74 Yield strength (MPa) 184.08 188.96 183.10 172.5 Elongation (%) 12.5 13.0 12.6 12.3 Secondary branch spacing (μm) 25.94 24.47 25.32 27.73

[0121] This invention is not limited to the above-described embodiments. Any modifications, improvements, or substitutions that can be conceived by those skilled in the art without departing from the essential content of this invention fall within the scope of this invention.

Claims

1. A method for manufacturing an automobile wheel hub, characterized in that, Includes the following steps: The prepared raw materials are melted according to the composition of the automobile wheel hub to obtain an alloy liquid; the raw materials include aluminum ingots with a purity of 99.7% or higher, metallic silicon, and magnesium ingots with a purity of 99.9% or higher. First and second rare earth aluminum alloys were added to the alloy liquid; after stirring for 10 minutes, degassing was performed, and then A-700R refining agent was sprinkled on the surface of the alloy liquid to obtain the first melt; wherein, the first rare earth aluminum alloy is a lanthanum aluminum alloy with a lanthanum content of 10.5 wt%, the second rare earth aluminum alloy is a scandium aluminum alloy with a scandium content of 2.3 wt%, the amount of the first rare earth aluminum alloy accounts for 0.37 wt% of the mass of the alloy liquid, the amount of the second rare earth aluminum alloy accounts for 0.65 wt% of the mass of the alloy liquid, and the amount of A-700R refining agent accounts for 0.4 wt% of the mass of the alloy liquid; An aluminum-strontium alloy and an aluminum-titanium-boron alloy, each with a strontium content of 10 wt%, were added to the first melt. After the aluminum-strontium alloy and the aluminum-titanium-boron alloy melted, the mixture was stirred evenly. Then, the scum on the surface was skimmed off with a spoon to obtain the second melt. The aluminum-strontium alloy accounted for 0.15 wt% of the mass of the alloy liquid; the aluminum-titanium-boron alloy contained 5.0 wt% titanium and 0.6 wt% boron; and the aluminum-titanium-boron alloy accounted for 2.5 wt% of the mass of the alloy liquid. The second melt at 700℃ was cast using a low-pressure casting machine to obtain a billet. The specific process conditions are as follows: the mold is preheated to 230℃, the liquid lifting pressure is 0.03MPa, the liquid lifting speed is 7cm / s, and the liquid lifting time is 6s; the filling pressure is 0.07MPa, the filling speed is 6cm / s, and the filling time is 11s; the holding pressure is 0.10MPa, and the holding time is 80s. The billet was solution treated at 520℃ for 8 hours, and then water quenched in hot water at 70℃ to obtain the solution-treated billet; the solution-treated billet was aged at 130℃ for 3 hours, and then naturally cooled to obtain the automobile wheel hub. The automobile wheel hub comprises Si 7.0wt%, Mg 0.33wt%, Ti 0.12wt%, Fe 0.09wt%, Mn 0.02wt%, P 0.002wt%, Sb 0.006wt%, Zn 0.030wt%, Cu 0.005wt%, Pb 0.03wt%, Sn 0.03wt%, Cr 0.02wt%, Ni 0.009wt%, La 0.037wt%, Sc 0.015wt%, Sr 0.015wt%, and Al 92.2wt%.

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