GB2614215A

GB2614215A - Automobile hub aluminum alloy capable of being subjected to spin casting and rotary forging and preparation method therefor, and automobile hub and

Info

Publication number: GB2614215A
Application number: GB2305926.4A
Authority: GB
Inventors: Wang Hongming; Li Guirong
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2021-01-19
Filing date: 2021-04-13
Publication date: 2023-06-28
Anticipated expiration: 2041-04-13
Also published as: GB2614215B; GB202305926D0; WO2022156075A1; CN112921215B; CN112921215A

Abstract

An automobile hub aluminum alloy capable of being subjected to spin casting and rotary forging and a preparation method therefor, and an automobile hub and a manufacturing method therefor. The aluminum alloy comprises the following components in percentage by mass: 3.0%-4.0% of Si, 2.0%-2.5% of Mg, 0.5%-1.0% of Mn, 0.10%-0.50% of Zr, 0.05%-0.1% of Cr, 0.5%-0.8% of Cu, 0.1%-0.3% of Zn, 0.10%-0.20% of Ti, 0.01%-0.05% of B, 0.05%-0.1% of Y, 0.1%-0.2% of Er, 0.02%-0.05% of Sr, and the balance of Al. The preparation method mainly comprises melting alloying, refining, casting, heat treatment, deformation processing, and other steps. The aluminum alloy is simple in alloying, can be applied to a spin casting process and a rotary forging process to prepare a high-performance aluminum alloy hub.

Description

AUTOMOBILE HUB ALUMINUM ALLOY CAPABLE OF BEING SUBJECTED TO

SPIN CASTING AND ROTARY FORGING AND PREPARATION METHOD

THEREFOR, AND AUTOMOBILE HUB AND MANUFACTURING METHOD

THEREFOR

TECHNICAL FIELD

The present disclosure belongs to the technical field of aluminum alloy preparation, and specifically relates to an automobile wheel hub aluminum alloy capable of undergoing casting and spinning, and forging and spinning, and a manufacturing method thereof

BACKGROUND

With the continuous improvement of automobile weight reduction requirements, lightweight aluminum alloy materials are more likely to replace high-specific gravity materials such as steel with a high specific gravity, and parts of high-end cars such as all-aluminum bodies and aluminum alloy wheel hubs require an aluminum alloy itself to exhibit high toughness, corrosion resistance, fatigue resistance, and very excellent deformation processing performance while having a light weight. Wheel hubs are indispensable key parts of automobiles, and 80% or more of automobiles adopt aluminum alloy wheel hubs. However, it is urgent to improve the performance of the current aluminum alloy wheel hubs, which needs to be achieved in the two aspects of optimizing an aluminum alloy material and continuously optimizing a wheel hub processing method.

There are currently two mainstream options for the material and processing method of an aluminum alloy wheel hub: 1. An A356 cast aluminum alloy is used to produce an aluminum alloy wheel hub through a casting and spinning process. This method is simple and easy to control, but the resulting wheel hub has poor performance (especially, the impact toughness is very low), and a finished automobile wheel has poor toughness and an elongation generally of about 2%, which is a bottleneck that can hardly be overcome by A356 aluminum alloy materials. 2. A 6061 aluminum alloy is used to produce an automobile wheel through forging and spinning, and the automobile wheel has high performance (especially, the elongation is significantly improved). However, the forging and spinning process is complex, and has large technical difficulty and a low yield rate. The current problem can hardly be overcome through process optimization alone, and needs to be solved from the root of materials.

In the field of aluminum alloy wheel hub processing, a new aluminum alloy is urgently needed, and this aluminum alloy can exhibit the superior performance of both a cast aluminum alloy and a deformable aluminum alloy, is suitable for flexible deformation processing and heat treatment methods, and can be processed into an aluminum alloy wheel hub through either a casting and spinning process or a forging and spinning process, which can meet the needs of current traditional aluminum alloy wheel hub production lines.

SUMMARY

In view of the problem that the processing adaptability is poor and an aluminum alloy wheel hub has poor performance due to a material itself when the aluminum alloy wheel hub is produced through aluminum alloy deformation, the present disclosure provides an aluminum alloy that has the performance of both a cast aluminum alloy and a deformable aluminum alloy and can be processed into an aluminum alloy wheel hub through either a casting and spinning process or a forging and spinning process, and the present disclosure also provides a high-performance wheel hub that can be produced through either a casting and spinning process or a forging and spinning process, and a manufacturing method thereof To achieve the objective of the present disclosure, the present disclosure adopts the following technical solutions.

An automobile wheel hub aluminum alloy capable of undergoing spin-casting and rotary-swaging is provided, including the following components in mass percentages: Si: 3.0% to 4.0%; Mg: 2.0% to 2.5%; Mn: 0.5% to 1.0%; Zr: 0.10% to 0.50%; Cr: 0.05% to 0.1%; Cu: 0.5% to 0.8%; Fe: 0.1% to 0.2%; Zn. 0 1% to 0.3%; 0.10% to 0.20%; B: 0.01% to 0.05%; Y: 0.05% to 0.1%; Er: 0.1% to 0.2%; Sr: 0.02% to 0.05%; and Al: the balance.

A manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing casting and spinning, and forging and spinning is provided, including the following steps: 1) smelting: melting an Al material in a furnace, adding a silicon ingot to the furnace, and after the silicon ingot is melted, adding a metal material including Al, Mn, Cu, Cr, Mg, Zn, and Fe to the furnace for melting; smelting at 740°C to 750°C for 100 min, and conducting mechanical slag removal; adding alloys of Zr, Ti, B, Y, Er, and Sr successively, and further smelting for 30 min until all the alloys are melted; mechanically stirring, slagging off, and sampling; and fine-tuning a composition to obtain an aluminum alloy melt; 2) refining: adjusting a temperature of the aluminum alloy melt obtained in the step 1) to 710°C to 730°C, spraying a refining agent into the furnace by argon, stirring to allow a refining treatment for 25 min, and slagging off, to obtain a refined aluminum alloy melt; 3) standing: adding a covering agent to the refined aluminum alloy melt, and allowing a resulting mixture to stand at 700°C to 710°C for 30 min; and 4) molding: subjecting an aluminum alloy melt obtained in the step 3 to low-pressure casting molding or semi-solid forging molding. Further, in the manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing spin-casting and rotary-swaging, in the step 4), the low-pressure casting molding is conducted at 680°C to 700°C within a pressure range of 500 mBar to 1,000 mBar in a low-pressure casting molding cavity; and the semi-solid forging molding is conducted at 580°C to 640°C.

Further, in the step 2), the refining agent includes the following components in mass percentages 35% to 40% of a basic component, 10% to 15% of a cryolite, 18% to 25% of hexachloroethane, 15% to 20% of sodium chlorosilicate, 6% of a rare earth fluoride CeF3, and 4% of a rare earth fluoride NaYF4, where the basic component is 50 wt% NaC1 + 50 wt% KC1; and the refining agent is added in an amount of 0.1% to 0.15% of a weight of the aluminum alloy melt.

Further, in the step 2), the argon is introduced at a rate of 25 mL/s Further, in the step 3), the covering agent is a sodium-free covering agent; and the covering agent is added in an amount of 0.1% of a weight of the aluminum alloy melt.

A method for manufacturing an automobile wheel hub based on the manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing spin-casting and rotary-swaging is provided, including: molding a wheel billet in the step 4), subjecting the wheel billet to a solution heat treatment, and processing by spinning forming or forging forming to obtain a formed wheel hub; and directly punching the formed wheel hub, conducting a heat treatment, cleaning, and polishing to obtain a finished wheel hub.

Further, in the method for manufacturing an automobile wheel hub, when the wheel billet is molded by the low-pressure casting molding, after the solution heat treatment, the wheel hub is formed by the spinning forming; and when the wheel billet is molded by the semi-solid forging molding, after the solution heat treatment, the wheel hub is formed by the forging forming.

Further, the solution heat treatment is conducted at 400°C to 420°C.

An automobile wheel hub manufactured by the method for manufacturing an automobile wheel hub is provided, and the automobile wheel hub has a residual gas impurity content of less than 0.1 vol.%, a melt gas content of less than 0.1 mL/100 g Al, a density of 2.75 g/cm3 or more, a tensile strength of greater than 320 MPa, a yield strength of greater than 280 MPa, an elongation of greater than 6%, and a microhardness of greater than 88 RV The present disclosure mainly has the following advantages.

(1) Compared with the traditional A356 aluminum alloy for casting and spinning of a wheel hub and the traditional 6061 aluminum alloy for forging and spinning of a wheel hub, the aluminum alloy of the present disclosure is obtained through the optimal coordination of alloying components, and after the aluminum alloy of the present disclosure is subjected to a solution heat treatment at 400°C to 420°C, a silicon precipitation phase and reinforcing phases such as Mg2Si and AI2Cu can be completely dissolved, the material deformation resistance is low, and the plastic workability is optimal, such that the aluminum alloy of the present disclosure can be processed into an aluminum alloy wheel hub through either a casting and spinning process or a forging and spinning process, which provides an optimal choice for aluminum alloy wheel hub processing enterprises to adopt production lines of different processing methods.

(2) The casting and spinning, and forging and spinning products of the present disclosure have a high surface metal supercooling degree, fast solidification, and relatively fine grains, and thus surfaces of the casting and spinning, and forging and spinning products have an effect of fine grain strengthening. Compared with the ordinary cast aluminum alloy, a density of the composite aluminum alloy is significantly improved and a specific strength is also significantly improved, such that a produced aluminum alloy wheel billet can meet the production requirements of subsequent spinning-deformation processing and forging-deformation processing.

(3) The refining agent designed by the present disclosure to be injected with argon exhibits an excellent effect of gas and impurity removal while not reacting with the aluminum alloy. The injection of argon takes away a large amount of hydrogen based on the principle of solvent diffusion, adsorption, and dissolution, thereby playing a dual effect of gas removal and slag removal.

(4) Main performance indexes of a wheel hub obtained by processing the aluminum alloy of the present disclosure meet the performance index requirements of high-performance aluminum alloy wheel hubs. Table 1 shows the comparison of wheel hubs produced from A356, 6061, and the three aluminum alloys of the present disclosure through the same casting and spinning, and heat treatment in tensile strength, yield strength, and elongation, and the results show that the wheel hubs produced from the aluminum alloys of the present disclosure are greatly improved in all aspects, and can lead to automobile wheels with light weight and high toughness.

Table 1

Tensile strength/MPa Yield strength/MPa Elongation A356 273 245 4.5% 6061 283 261 6.1% Aluminum alloy of the present disclosure 326 290 6.5%

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a scanning electron microscopy (SEM) image illustrating a microstructure of the lightweight automobile wheel hub aluminum alloy obtained in Example 1 of the present disclosure after a T6 heat treatment.

FIG. 2 is an SEM image illustrating a microstructure of the lightweight automobile wheel hub aluminum alloy obtained in Example 2 of the present disclosure after a T6 heat treatment.

FIG. 3 is an SEM image illustrating a microstructure of the aluminum alloy wheel hub obtained in the comparative example after a T6 heat treatment.

DETAILED DESCRIPTION OF THE EMBODIMENTS Example 1

1) Smelting: An Al material was melted in a furnace, a silicon ingot was added to the furnace, and after the silicon ingot was melted, according to the following mass percentages: Si: 3.5%, Mg: 2.25%, Mn: 0.75%, Zr: 0.3%, Cr: 0.075%, Cu: 0.65%, Zn. 0 2%, Fe: 0.15%, Ti: 0.15%, B: 0.03%, Y: 0.075%, Er: 0.15%, Sr: 0.035%, and Al: the balance, a metal material including Al, Mn, Cu, Cr, Mg, Zn, and Fe was added to the furnace for melting; smelting was conducted at 750°C for 100 min, and mechanical slag removal was conducted; alloys of Zr, Ti, B, Y, Er, and Sr were added successively, and smelting was further conducted for 30 min until all the alloys were melted; mechanical stirring, slagging-off, and sampling were conducted; and a composition was fine-tuned to obtain an aluminum alloy melt.

2) Refining: A temperature of the aluminum alloy melt obtained in the step 1 was adjusted to 730°C, 0.15% of a refining agent was sprayed into the furnace by argon, the resulting mixture was stirred to allow a refining treatment for 25 min, and slagging-off was conducted, where the refining agent included: 40% of a basic component (50 wt% NaCI + 50 wt% KCI), 10% of a cryolite, less than 20% of hexachloroethane, 20% of sodium chlorosilicate, 6% of a rare earth fluoride CeF3, and 4% of a rare earth fluoride NaYF4; the refining agent was added in an amount of 0.10% of a weight of the aluminum alloy melt; and the argon was introduced at a rate of 25 mL/s.

3) Standing: A sodium-free covering agent was added to the refined aluminum alloy melt in an amount of 0.1%, and the resulting mixture was stood at 710°C for 30 min. 4) Molding: An aluminum alloy melt obtained in the step 3) was further molded into a wheel billet by low-pressure casting molding at 700°C within a pressure range of 500 mBar to 1,000 mBar in a low-pressure casting molding cavity.

5) Processing of the wheel billet into a wheel hub: The wheel billet obtained in the step 4) was subjected to a solution heat treatment at 400°C to 420°C and then processed into the wheel hub through spinning forming.

The aluminum alloy wheel hub obtained by the above steps was punched at a high temperature, subjected to a heat treatment, cleaned, and polished to obtain a finished wheel hub. The finished aluminum alloy wheel hub had a residual gas impurity content of 0.1 vol.%, a melt gas (hydrogen) content of less than 0 1 mL/100 g Al, a pinhole degree level about 2 times lower than a pinhole degree level of the traditional cast aluminum alloy wheel hub, a density of 2.75 g/cm3, a tensile strength of 326 MPa, a yield strength of greater than 287 MPa, an elongation of greater than 6.2%, and a microhardness of 89 HV.

FIG. 1 is an SEM image illustrating a microstructure of the lightweight automobile wheel hub aluminum alloy obtained in Example 1 of the present disclosure after a T6 heat treatment. Example 2 1) Smelting: An Al material was melted in a furnace, a silicon ingot was added to the furnace, and after the silicon ingot was melted, according to the following mass percentages: Si: 4.0%, Mg: 2.5%, Mn: 1.0%, Zr: 0.50%, Cr: 0.1%, Cu: 0.8%, Zn: 0.3%, Fe: 0.13%, Ti: 0.20%, B: 0.05%, Y: 0.1%, Er: 0.2%, Sr: 0.05%, and Al: the balance, a metal material including Al, Mn, Cu, Cr, Mg, Zn, and Fe was added to the furnace for melting; smelting was conducted at 745°C for 100 min, and mechanical slag removal was conducted; alloys of Zr, Ti, B, Y, Er, and Sr were added successively, and smelting was further conducted for 30 min until all the alloys were melted; mechanical stirring, slagging-off, and sampling were conducted; and a composition was fine-tuned to obtain an aluminum alloy melt.

2) Refining: A temperature of the aluminum alloy melt obtained in the step (1) was adjusted to 730°C, 0.15% of a refining agent was sprayed into the furnace by argon, the resulting mixture was stirred to allow a refining treatment for 25 min, and slagging-off was conducted, where the refining agent was the same as the refining agent used in Example 1; and the argon was introduced at a rate of 22 mL/s.

3) Standing: A sodium-free covering agent was added to the refined aluminum alloy melt in an amount of 0.1%, and the resulting mixture was stood at 710°C for 30 min. 4) Molding: An aluminum alloy melt obtained in the step 3) was further molded into a wheel billet by semi-solid forging molding at 580°C to 640°C.

5) Processing of the wheel billet into a wheel hub: The wheel billet obtained in the step 4) was subjected to a solution heat treatment at 400°C to 420°C and then processed into the wheel hub through forging and spinning forming.

The aluminum alloy wheel hub obtained by the above steps was punched at a high temperature, subjected to a heat treatment, cleaned, and polished to obtain a finished wheel hub. The finished aluminum alloy wheel hub had a residual gas impurity content of 0.08 vol.%, a melt gas (hydrogen) content of less than 0 08 mL/100 g Al, a hole degree level about 2 times lower than a pinhole degree level of the traditional cast aluminum alloy wheel hub, a density of 2.78 g/cm3, a tensile strength of 330 MPa, a yield strength of greater than 290 MPa, an elongation of 6.7%, and a microhardness of 90 HV.

In order to illustrate the advantages of the present disclosure, an aluminum alloy wheel hub was manufactured with the A356 aluminum alloy through the traditional gravity casting method as a comparative example. FIG. 3 is an SEM image illustrating a microstructure of the aluminum alloy wheel hub obtained in the comparative example after a TO heat treatment. It can be seen from the SEM images of Examples 1 and 2 in FIG. 1 and FIG. 2 and the SEM image of the comparative example in FIG. 3 that the alloy and processing method of the present disclosure make a silicon phase uniformly distributed in a sample along a grain boundary, and after the T6 heat treatment, crystalline silicon is spherified and uniformly diffused around the grain boundary in the form of fine spherical or ellipsoidal particles, the resulting structure is dense, and Mg2Si is completely dissolved in the matrix a-Al; and compared with the comparative example, in terms of the microstructure, tissue densities of Examples 1 and 2 are significantly increased.

The above examples are preferred implementations of the present disclosure, but the present disclosure is not limited to the above implementations. Any obvious improvement, substitution, or modification made by those skilled in the art without departing from the essence of the present disclosure should fall within the protection scope of the present disclosure.

Claims

CLAIMSWhat is claimed is: 1. An automobile wheel hub aluminum alloy capable of undergoing spin-casting and rotary-swaging, characterized by comprising the following components in mass percentages: Si: 3.0% to 4.0%; Mg: 2.0% to 2.5%; Mn: 0.5% to 1.0%; Zr: 0.10% to 0.50%; Cr: 0.05% to 0.1%; Cu: 0.5% to 0.8%; Fe: 0.1% to 0.2%; Zn: 0.1% to 0.3%; Ti: 0.10% to 0.20%; B: 0.01% to 0.05%; Y: 0.05% to 0.1%; Er: 0.1% to 0.2%; Sr: 0.02% to 0.05%; and Al: the balance.
2. A manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing casting and spinning, and forging and spinning according to claim 1, characterized by comprising the following steps: 1) smelting: melting an Al material in a furnace, adding a silicon ingot to the furnace, and after the silicon ingot is melted, adding a metal material comprising Al, Mn, Cu, Cr, Mg, Zn, and Fe to the furnace for melting; smelting at 740°C to 750°C for 100 min, and conducting mechanical slag removal; adding alloys of Zr, Ti, B, Y, Er, and Sr successively, and further smelting for 30 min until all the alloys are melted; mechanically stirring, slagging off, and sampling; and fine-tuning a composition to obtain an aluminum alloy melt; 2) refining: adjusting a temperature of the aluminum alloy melt obtained in the step 1) to 710°C to 730°C, spraying a refining agent into the furnace by argon, stirring to allow a refining treatment for 25 min, and slagging off, to obtain a refined aluminum alloy melt; 3) standing: adding a covering agent to the refined aluminum alloy melt, and allowing a resulting mixture to stand at 700°C to 710°C for 30 min; and 4) molding: subjecting an aluminum alloy melt obtained in the step 3 to low-pressure casting molding or semi-solid forging molding.
3. The manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing spin-casting and rotary-swaging according to claim 2, characterized in that, in the step 4), the low-pressure casting molding is conducted at 680°C to 700°C within a pressure range of 500 mBar to 1,000 mBar in a low-pressure casting molding cavity; and the semi-solid forging molding is conducted at 580°C to 640°C
4. The manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing casting and spinning, and forging and spinning according to claim 2, characterized in that, in the step 2), the refining agent comprises the following components in mass percentages: 35% to 40% of a basic component, 10% to 15% of a cryolite, 18% to 25% of hexachloroethane, 15% to 20% of sodium chlorosilicate, 6% of a rare earth fluoride CeF3, and 4% of a rare earth fluoride NaYF4, wherein the basic component is 50 wt% NaC1 + 50 wt% KC1; and the refining agent is added in an amount of 0.1% to 0.15% of a weight of the aluminum alloy melt.
5. The manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing casting and spinning, and forging and spinning according to claim 2, characterized in that, in the step 2), the argon is introduced at a rate of 25 mL/s
6. The manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing casting and spinning, and forging and spinning according to claim 2, characterized in that, in the step 3), the covering agent is a sodium-free covering agent; and the covering agent is added in an amount of 0.1% of a weight of the aluminum alloy melt.
7. A method for manufacturing an automobile wheel hub based on the manufacturing method of the automobile wheel hub aluminum alloy capable of undergoing spin-casting and rotary-swaging according to claim 2, characterized by comprising: molding a wheel billet in the step 4), subjecting the wheel billet to a solution heat treatment, and processing by spinning forming or forging forming to obtain a formed wheel hub; and directly punching the formed wheel hub, conducting a heat treatment, cleaning, and polishing to obtain a finished wheel hub.
8. The method for manufacturing the automobile wheel hub according to claim 7, characterized in that, when the wheel billet is molded by the low-pressure casting molding, after the solution heat treatment, the wheel hub is formed by the spinning forming; and when the wheel billet is molded by the semi-solid forging molding, after the solution heat treatment, the wheel hub is formed by the forging forming.
9. The method for manufacturing the automobile wheel hub according to claim 7, characterized in that, the solution heat treatment is conducted at 400°C to 420°C.
10. An automobile wheel hub manufactured by the method for manufacturing the automobile wheel hub according to claims 7 to 9, characterized in that, the automobile wheel hub has a residual gas impurity content of less than 0.1 vol.%, a melt gas content of less than 0 1 mL/100 g Al, a density of 2.75 g/cm3 or more, a tensile strength of greater than 320 MPa, a yield strength of greater than 280 MPa, an elongation of greater than 6%, and a microhardness of greater than 88 HV.