CN112226655B - Composite aluminum alloy wheel and manufacturing method thereof - Google Patents

Composite aluminum alloy wheel and manufacturing method thereof Download PDF

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CN112226655B
CN112226655B CN202011088191.3A CN202011088191A CN112226655B CN 112226655 B CN112226655 B CN 112226655B CN 202011088191 A CN202011088191 A CN 202011088191A CN 112226655 B CN112226655 B CN 112226655B
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alloy
wheel
pressure
rim
intermediate alloy
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CN112226655A (en
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昝建玖
刘军
杜晓东
邱明坤
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Anhui Topler Automobile Technology Co ltd
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Anhui Topler Automobile Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B3/00—Disc wheels, i.e. wheels with load-supporting disc body
    • B60B3/06—Disc wheels, i.e. wheels with load-supporting disc body formed by casting
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/78—Combined heat-treatments not provided for above
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/34—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for tyres; for rims
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C22C1/026—Alloys based on aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C22C1/03—Making non-ferrous alloys by melting using master alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/06—Making non-ferrous alloys with the use of special agents for refining or deoxidising
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/002—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working by rapid cooling or quenching; cooling agents used therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/043—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with silicon as the next major constituent
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2310/00—Manufacturing methods
    • B60B2310/20—Shaping
    • B60B2310/202—Shaping by casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2310/00—Manufacturing methods
    • B60B2310/20—Shaping
    • B60B2310/214—Shaping by extrusion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2310/00—Manufacturing methods
    • B60B2310/50—Thermal treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2310/00—Manufacturing methods
    • B60B2310/50—Thermal treatment
    • B60B2310/54—Hardening
    • B60B2310/542—Quenching
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2360/00—Materials; Physical forms thereof
    • B60B2360/10—Metallic materials
    • B60B2360/104—Aluminum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2900/00—Purpose of invention
    • B60B2900/10—Reduction of
    • B60B2900/111—Weight
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2900/00—Purpose of invention
    • B60B2900/10—Reduction of
    • B60B2900/112—Costs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60B—VEHICLE WHEELS; CASTORS; AXLES FOR WHEELS OR CASTORS; INCREASING WHEEL ADHESION
    • B60B2900/00—Purpose of invention
    • B60B2900/10—Reduction of
    • B60B2900/113—Production or maintenance time

Abstract

The invention discloses a composite aluminum alloy wheel and a manufacturing method thereof.A rim and a spoke part of the wheel are respectively cast and molded by adopting different casting methods so as to meet the integral performance requirement of the wheel in the service process; in order to meet different casting process requirements, the components of the alloy material at the rim part are designed to be as follows by mass percent: 4.1-4.5% of Si, 0.80-0.85% of Mg, 0.17-0.2% of Ti, 0.10-0.15% of Cr, 0.10-0.15% of Mn, 0.015-0.017% of Sr and the balance of pure aluminum; the alloy material at the spoke part comprises the following components in percentage by mass: 6.5 to 6.7 percent of Si, 0.21 to 0.25 percent of Mg, 0.13 to 0.16 percent of Ti, 0.18 to 0.22 percent of Cr, 0.18 to 0.22 percent of Mn, 0.16 to 0.2 percent of Zr, 0.011 to 0.013 percent of Sr and the balance of pure aluminum.

Description

Composite aluminum alloy wheel and manufacturing method thereof
Technical Field
The invention belongs to the technical field of non-ferrous metal aluminum-based alloy, and particularly relates to a composite aluminum alloy wheel and a manufacturing method thereof.
Background
The aluminum alloy material is widely applied to the automobile wheel, and the automobile wheel is mainly divided into a rim and a spoke. In the prior art, two parts are integrally cast and molded by aluminum liquid with the same components, but the performance requirements of all parts of the automobile wheel are actually different due to different stress conditions. The rim part is arranged on the outermost side and mainly bears lateral force impact and frictional wear, so the requirements on strength and wear resistance are generally higher, and the spoke is not easily worn due to the protection of the rim, but bears stronger impact and bending stress, so the requirements on plasticity and toughness are relatively higher, the requirements on strong hardness are second, and the requirements on the appearance of the lower surface are also higher. Generally, when a household vehicle rarely encounters extreme road conditions, the requirement of the outer rim is important, so that in order to guarantee the service life of the tire, the cast wheel is designed according to the performance requirement of the rim, the strength and hardness of the spoke are excessive, the toughness is slightly insufficient, potential performance hazards exist, and accidents are easily caused by the insufficient performance in the case of dangerous conditions. Therefore, neglecting the different performance requirements of different parts, the single use of the same alloy composition for integral casting molding brings about two problems. Firstly, the overall performance of the wheel is not high; secondly, because the trends of the performance index requirements of different parts are conflicting, the compromise is difficult. When the same material is adopted, the components are designed according to the characteristics of the rim of strong weight, hardness, light plasticity and toughness, so that the plasticity and toughness of the spoke part do not reach the standard; or the toughness is improved by sacrificing the strength and the hardness so as to meet the toughness requirement of the spoke, and the strength and the hardness of the rim do not reach the standard. If the requirements of the strength of the rim and the ductility and toughness of the spoke are simultaneously met, more ductility and toughness redundancy exists on the rim, and more strength redundancy exists on the spoke. Therefore, the waste of raw materials and the serious performance surplus are caused, and the production cost of enterprises is increased. How to more fully utilize the optimal utilization rate of materials and further improve the quality of the wheel becomes a problem which needs to be solved urgently at present. Based on the method, different alloy elements are firstly selected to alloy different parts of the spoke and the rim of the wheel, and a foundation is laid for subsequently selecting different casting and forming processes.
Disclosure of Invention
Aiming at the defects of the existing wheel casting forming quality, the invention provides a composite aluminum alloy wheel and a manufacturing method thereof. According to the invention, different contents and types of alloy components are firstly designed for the rim and the spoke of the wheel, and a novel casting molding process service is adopted subsequently, so that the prepared composite aluminum alloy wheel can meet the respective performance requirements of the rim and the spoke, and simultaneously, the investment of redundant alloy elements and production equipment is saved, the overall performance of the designed and manufactured wheel is further improved, the unnecessary resource waste and the investment of manpower and equipment are reduced, the production efficiency of the wheel is improved, the production cost is saved, and the wheel conforms to the current green development concept.
The rim and the spoke of the composite aluminum alloy wheel respectively adopt different casting forming processes: the wheel rim is formed by extrusion after low-pressure casting, so that high strength, toughness and good air tightness are obtained, and for realizing the process, the wheel rim is designed by adopting 4.1-4.5% of Si, 0.80-0.85% of Mg, 0.17-0.2% of Ti, 0.10-0.15% of Cr, 0.10-0.15% of Mn, 0.015-0.017% of Sr and the balance of aluminum; the spoke is directly manufactured by low-pressure casting and molding in synchronization with rim pouring, so that high ductility and certain strength are obtained, and the spoke is designed by adopting 6.5-6.7% of Si, 0.21-0.25% of Mg, 0.13-0.16% of Ti, 0.011-0.013% of Sr, 0.18-0.22% of Cr0.18-0.22% of Mn, 0.16-0.2% of Zr and the balance of aluminum alloy components.
The invention relates to a casting forming method of a composite aluminum alloy wheel, which is characterized in that a closed crucible, a liquid lifting pipe and a pouring system which are respectively used for containing different aluminum alloy liquids are respectively arranged at the corresponding parts of a spoke and a rim of the wheel during casting, alloy at the spoke part is smelted through ingredients and then enters a spoke cavity under the action of low pressure through the liquid lifting pipe distributed at the corresponding part of the spoke, and alloy at the rim part is smelted through ingredients and then enters a rim cavity under the action of low pressure through the liquid lifting pipe distributed at the corresponding part of the rim. And maintaining the pressure until the aluminum liquid in the casting mold is completely solidified, then releasing the gas pressure, and automatically dropping the aluminum liquid which does not participate in solidification in the liquid lifting pipe back to the crucible under the action of gravity. After the rim is prepared, the rim part is extruded and formed to reach the designed size. The spoke part of the wheel is formed by low pressure casting, and the rim part of the wheel is subjected to low pressure casting forming and extrusion forming, and then is subjected to heat treatment.
The rising speed of the aluminum alloy solution in the low-pressure liquid rising pipe corresponding to the wheel rim and the wheel spoke is determined by the structural size of the wheel, namely the volume ratio V of the wheel rim to the wheel spokeA：VBDetermining the rising speed ratio of the two different compositions of the aluminum alloy solution in the lift tube as VA：VB。
The manufacturing method of the composite aluminum alloy wheel comprises the following steps:
step 1: spoke part forming
1a, preparing materials
Weighing pure aluminum, Al-Si intermediate alloy, Al-Mg intermediate alloy, Al-Ti intermediate alloy, Al-Zr intermediate alloy and Al-Sr intermediate alloy (the Al-Sr intermediate alloy adopts flat Sr strips with the shape of 0.2 x 5 mm), the Al-Cr intermediate alloy and the Al-Mn intermediate alloy according to the proportion;
1b, melting
Adding the dried Al-Si intermediate alloy into the preheated crucible, adding pure aluminum to cover the upper surface of the Al-Si intermediate alloy, heating to 750 ℃ along with the furnace, standing and preserving heat for 20min after the Al-Si intermediate alloy is completely melted; then adding Al-Ti intermediate alloy, Al-Zr intermediate alloy, Al-Cr intermediate alloy and Al-Mn intermediate alloy into the melted alloy melt, standing and keeping the temperature for 10min after all the intermediate alloy is melted; adjusting the temperature to 720 ℃ (preventing the Mg element from being burnt out due to overhigh temperature), adding Al-Mg intermediate alloy into the alloy melt, stirring for 3-5 minutes by using a quartz rod after the Al-Mg intermediate alloy is completely melted or dissolved to ensure that the elements are uniformly distributed, standing and preserving the heat for 10 min;
1c refining and modification
Rapidly skimming dross on the surface layer of the alloy melt obtained in the step 1b by using a skimming ladle, and then using a graphite bell jar to skim dross C2Cl6Pressing a refining agent into the solution to 1/3 parts at the bottom of the crucible, maintaining the same direction, rotating slowly, refining and degassing, then sending flat Sr strips with the thickness of 0.2 x 5mm into a molten pool, standing at 720 ℃ and keeping the temperature for 10-20 min, and finally, scattering a slag removal agent for removing slag;
1d, pouring
And (3) molding the alloy melt obtained in the step (1 c) by adopting a low-pressure casting process, wherein the side die temperature of a low-pressure casting die is controlled to be 460-480 ℃, the temperature of the alloy melt is kept to be 720-740 ℃, the alloy melt is introduced into a low-pressure casting machine for carrying out low-pressure casting on the spoke, and the process parameters in the casting process are as follows:
liquid lifting: the pressure is 250-270 bar, and the time is 16-20 s;
filling a mold: the pressure is 400-420 bar, and the time is 36-40 s;
supercharging: the pressure is 850-870 bar, and the time is 46-50 s;
pressure maintaining: the pressure is 860 to 880bar, and the time is 52 to 56 s.
After pressure relief and solidification, cooling, demolding and taking out to obtain a spoke part of the wheel;
step 2: rim part forming
2a, preparing materials
Weighing pure aluminum, Al-Si intermediate alloy, Al-Mg intermediate alloy, Al-Ti intermediate alloy, Al-Cr intermediate alloy, Al-Mn intermediate alloy and 0.2 x 5mm flat Sr strips according to the proportion;
2b, melting
Adding the dried Al-Si intermediate alloy into the preheated crucible, adding pure aluminum to cover the Al-Si intermediate alloy, heating to 750 ℃ along with the furnace, standing and preserving heat for 20min after the Al-Si intermediate alloy is completely melted; then adding Al-Ti intermediate alloy, Al-Cr intermediate alloy and Al-Mn intermediate alloy into the molten alloy melt, standing and keeping the temperature for 10min after all the intermediate alloy is molten; adjusting the temperature to 720 ℃, adding Al-Mg intermediate alloy into the alloy melt, stirring for 3-5 minutes by using a quartz rod after the Al-Mg intermediate alloy is completely melted or dissolved so as to ensure that the elements are uniformly distributed, standing and keeping the temperature for 10 min;
2c refining and modification
Rapidly skimming the dross on the surface layer of the alloy melt by using a skimming ladle, and then using a graphite bell jar to skim C2Cl6Pressing a refining agent into the solution to 1/3 parts at the bottom of the crucible, maintaining the same direction, rotating slowly, refining and degassing, then sending flat Sr strips with the thickness of 0.2 x 5mm into a molten pool, standing at 720 ℃ and keeping the temperature for 10-20 min, and finally, scattering a slag removal agent for removing slag;
2d, pouring
And (3) molding the alloy melt obtained in the step (2 c) by adopting a low-pressure casting process, wherein the side die temperature of a low-pressure casting die is controlled to be 460-480 ℃, the temperature of the alloy melt is kept to be 720-740 ℃, the alloy melt is introduced into a low-pressure casting machine for low-pressure casting of a rim, and the process parameters in the casting process are as follows:
liquid lifting: the pressure is 260-280 bar, and the time is 18-22 s;
filling a mold: the pressure is 410-430 bar, and the time is 38-42 s;
supercharging: the pressure is 860-880 bar, and the time is 48-52 s;
pressure maintaining: the pressure is 870-890 bar, and the time is 54-58 s.
After pressure relief and solidification, cooling, demolding and taking out to obtain a rim part of the wheel;
and step 3: extrusion forming of rim part
Heating the cast wheel to 240-260 ℃, putting the wheel into a wheel extrusion die after diathermy, and carrying out isothermal extrusion on the rim part by using a press machine, wherein the rolling reduction is 10-16% of the wall thickness of the rim, and the extrusion strain rate is 0.05-0.08S-1Extruding and deforming until the design size of the rim is reached;
and 4, step 4: thermal treatment
And carrying out heat treatment on the obtained wheel, namely sequentially carrying out solution treatment and artificial aging treatment.
The solution treatment process comprises the following steps: carrying out solid solution and heat preservation at 540 +/-5 ℃ for 3h, discharging and quenching, carrying out water quenching at 40-60 ℃ in warm water, wherein the time from discharging to quenching in water is less than or equal to 15s, and the cooling time in water is about 4-6 min;
the artificial aging treatment process comprises the following steps: aging and preserving heat for 3.5h at 170 +/-5 ℃, and discharging and air cooling.
The design basis of the invention is as follows:
the spoke part comprises 6.5-6.7% of Si, 0.21-0.25% of Mg, 0.13-0.16% of Ti, 0.011-0.013% of Sr, 0.18-0.22% of Cr, 0.18-0.22% of Mn, 0.16-0.2% of Zr and the balance of aluminum, and the rim part comprises 4.1-4.5% of Si, 0.80-0.85% of Mg, 0.17-0.2% of Ti, 0.10-0.15% of Cr, 0.10-0.15% of Mn, 0.015-0.017% of Sr and the balance of aluminum. The difference of the components of the two parts mainly serves the following casting and forming processes of the two parts, so that the quality of the wheel is further improved, the comprehensive performance of the novel composite aluminum alloy wheel is optimized and improved, and the added Si, Mg, Ti, Sr, Cr, Mn and Zr have the following specific functions:
compared with cast aluminum alloy wheels used at home and abroad, the design component of the spoke part is 6.5-6.7% of Si, the content of Si is slightly lower than that of the conventional A356 wheel, the requirement on fluidity is relatively lower in consideration of the fact that the spoke part is formed by adopting a low-pressure casting method, and the eutectic Si phase is further reduced by combining proper heat treatment due to the fact that the Si phase in the structure after casting is reduced through casting forming, so that the ductility and toughness of the obtained spoke part are further improved.
Compared with cast aluminum alloy wheels used at home and abroad, the design component of the rim part is Si4.1-4.5%, so that the obtained Al-Si-Mg alloy can be cast and molded at low pressure, and because the Si phase in the cast structure is low, the eutectic Si phase is further reduced by combining with proper heat treatment, the alloy has certain extrusion formability and work hardening capacity. After the rim part is cast and formed near net shape, the shape and the size of the rim part can be changed to the design size by warm extrusion with lower strain rate and lower temperature, air holes are compacted, work hardening and subgrain strengthening are generated, and the requirements of the rim part on the strength, the rigidity and the air tightness are met. In the extrusion process of the rim, a large amount of dislocation is introduced, and due to the lower deformation temperature, dynamic recovery and dynamic recrystallization are insufficient, and the deformation strengthening effect is good. In the deformation process of controlling the strain rate, the dislocation formation and merging disappearance of the local areas reach dynamic balance, and the same-sign dislocations are vertically arranged to form a dislocation wall, so that a large amount of subgrains are formed, the subgrains are strengthened, and the alloy is further strengthened.
The invention can form Al by adding transition metals Ti and Zr into the alloy3Zr phase, Al3Ti phase, Al3The phase has lattice constants (a is 0.407nm) which are close to the matrix and have smaller mismatching degree (about 0.5 percent) with the matrix, the heterogeneous nucleation efficiency is improved, the grain refining effect is obviously enhanced, and the second phase strengthening effect is also achieved.
The secondary Mg separated out from the alloy in the aging process2Si particles have strong pinning dislocation to block dislocation movement, and meanwhile, the migration and combination of sub-grain boundaries are prevented, so that the recrystallization temperature of the alloy is increased, and a sub-structure strengthening effect is generated on the alloy. In addition, secondary Mg2Si is precipitated in the alloy in a dispersed and fine mode, and the Si also has extremely obvious precipitation strengthening effect on the alloy.
Cr added into the alloy can effectively treat a coarse brittle eutectic phase which is generated by Fe, Al and Si together in the Al alloy due to the existence of Fe and is usually in a long needle or a flake shape, the brittle eutectic phase is easy to cause stress concentration to induce fracture during deformation, and the Cr added can be converted into a fine Cr-rich phase to pin dislocation, inhibit recrystallization and strengthen the alloy. At the same time, the Cr-rich phases can provide the prior surface-promoted precipitation strengthening effect during the aging precipitation. Also, the risk of producing a coarse phase is excessively added.
Mn added to the alloy can prevent the recrystallization process of the aluminum alloy, improve the recrystallization temperature and obviously refine recrystallized grains. The recrystallized grains are refined mainly by MnAl6The dispersed particles of the compound hinder the growth of recrystallized grains. MnAl6Has the other function of dissolving impurity iron to form (Fe, Mn) Al6Thereby reducing the deleterious effects of iron. Manganese is an important element in aluminum alloys. It may be added alone to form an Al — Mn binary alloy, and more often together with other alloying elements. Therefore, most aluminum alloys contain manganese. The Cr element can precipitate AlCrSi phase in the aging stage of the aluminum alloy, the precipitated phases can become non-uniform nucleation sites of Mg-Si phase, so that the strengthening effect of the alloy is reduced, and the Mn element can be matched with the Cr element by adding the Mn element, so that the effect of improving the ductility and toughness of the alloy is better.
Sr added in the alloy can play a role in modification, obviously refines grain structure, and has obvious etching and refining effects on Si phase and second phase.
The wheel consists of two main parts, namely: rim, spoke, as shown in fig. 1. The rim is directly contacted with the tire, the part of the outer ring of the tire is supported, the stress condition is more severe than that of the spoke part, and the rim directly bears higher load and is subjected to frictional wear in the use process, so that the rim part requires higher hardness and higher wear resistance, and the requirement on the plasticity and toughness is lower. Therefore, more alloying element Mg is added into the rim part to form more Mg2The Si strengthening phase improves the strength, and simultaneously obtains high strength by low strain rate after casting, low temperature and temperature extrusion deformation to form deformation strengthening and subgrain strengthening. And adding Sr and Ti togetherThe modification treatment is to improve the overall structure morphology and remove dendrites and coarse flaky eutectic phases, and the strengthening phase keeps a good shape and is beneficial to subsequent aging heat treatment. Wherein the modification effect of Sr is more inclined to improve the overall structure morphology, Ti is inclined to refine alloy grains, the modification effect can be greatly improved by the composite modifier, and the better plastic toughness of the aluminum alloy matrix is kept while enough strengthening phases are provided so as to achieve the indexes in the aspects of impact resistance and fatigue resistance. Meanwhile, Ti can also reduce the hydrogen absorption tendency of the aluminum alloy after Sr is added. The addition of Cr can purify the impurity Fe, refine the crystal grains when the impurity Fe is the same, and add a small amount of Mn element to match with the action of Cr element so that the Mn element and the Cr element further improve the ductility and toughness of the alloy, and simultaneously avoid the generation of a coarse phase caused by the addition of excessive Cr. The Zr is added to refine the crystal grains and reduce the rapid cooling sensitivity, so that more alloy elements can be dissolved in the solution to precipitate more strengthening phases during the aging treatment. Because Cr and Mn can react with Al and other elements in the matrix to generate a dispersed phase, and the combination of Cr and Mn can generate more dispersed phases than the combination of Cr and Mn added alone, the effect of refining crystal grains is better, and the effect of purifying Fe impurities is also better.
As mentioned above, the strength of the spoke portion is slightly lower than that of the rim portion, but the requirements for safety, impact resistance, and fatigue resistance are higher. Therefore, the composition design of the spoke part in the proposal mainly reduces the adding amount of Si and Mg. In order to make up for the strong hardness and the toughness, the addition amount of Sr and Ti is basically fine-tuned. In addition, the elements for purifying impurities such as Cr, Zr, Mn and the like are added in an increased amount so as to form more Cr-rich and Mn-rich phase pinning dislocations, inhibit recrystallization and strengthen and refine the alloy. Meanwhile, the Cr-rich and Mn-rich phases can provide the existing surface for promoting precipitation during aging precipitation so as to achieve the effect of strengthening aging. And the addition of more Zr can also provide nucleation points and dispersed distribution pinning grain boundaries for primary precipitated particles in the solidification process to inhibit recrystallization, so that the ductility, toughness and corrosion resistance of the alloy are improved. Zr can also obviously reduce the quenching sensitivity of the alloy, strengthen the aging effect and improve the plasticity and toughness of the alloy.
The design scheme of the invention aims to: the rim is subjected to low-pressure casting and then extrusion molding to obtain high strength, high toughness and better air tightness, and in order to realize the process, the rim is designed by adopting 4.1-4.5% of Si, 0.80-0.85% of Mg, 0.17-0.2% of Ti, 0.10-0.15% of Cr0.10-0.15% of Mn, 0.015-0.017% of Sr and the balance of aluminum; the spoke is directly manufactured through a low-pressure casting molding system synchronous with rim casting, so that performance indexes such as high ductility, toughness and strength are obtained, and therefore, 6.5-6.7% of Si, 0.21-0.25% of Mg, 0.13-0.16% of Ti, 0.011-0.013% of Sr, 0.18-0.22% of Cr, 0.18-0.22% of Mn0.18-0.22% of Zr, and the balance of aluminum alloy components are adopted for design. The spoke and the rim of the wheel adopt different casting forming process methods and different alloy component designs, so that the overall comprehensive performance of the wheel is obviously improved. The components of a rim part and a spoke part of the conventional wheel for the existing automobile are the same, wherein the tensile strength of each part is that the rim is more than or equal to 275MPa, and the spoke is more than or equal to 250 MPa; yield strength: the rim is more than or equal to 165MPa, and the spoke is more than or equal to 155 MPa. If the components are designed according to the index of plasticity and toughness reduced by the rim side weight strength and the index of strong hardness reduced by the spoke side remodeling toughness, the wheel is integrally cast and molded, and then the loss is caused in the aspects of plasticity and toughness and strong hardness. Under ordinary driving conditions, even if the toughness or hardness is insufficient, danger is not caused because the road is smooth and does not receive too much impact, but once the road is in a bad condition, danger is caused because of imbalance in performance. If the components are designed according to the strength of the rim and the ductility and toughness of the spoke, the rim and the spoke have excessive performances, and the service life is not prolonged, and the cost is wasted.
In the heat treatment process, when the solution treatment and heat preservation are carried out at 540 +/-5 ℃ for 3 hours, the strength after aging can reach more than 95 percent compared with the long-time solution treatment and heat preservation treatment of the conventional T6. Because the amount of Mg added at the rim part is higher, enough Mg can be dissolved into an Al matrix after short-time solid solution heat preservation, and the strength of the rim is greatly from extrusion forming processing after casting, the invention adopts short-time solid solution heat preservation. For the spoke, the content of Si and Mg is lower than that of the common A356, and the required solid solution heat preservation time is shorter. Therefore, the invention adopts the solid solution heat preservation in a short time and has good effect.
The artificial aging heating heat preservation temperature is 170 +/-5 ℃, the formation speed of an aging phase is high, the aging heat preservation time is shortened to 3 hours, and a second phase in dispersion distribution can be obtained, so that the aging strengthening effect is achieved.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention mainly aims at different parts of the automobile wheel, firstly designs alloy materials with different component contents, and then respectively adopts different casting forming processing methods to prepare the required novel composite aluminum alloy wheel. The Si content of the spoke part is slightly lower than that of the conventional A356 wheel, so that the obtained spoke part has good plasticity and toughness and higher strength, and can meet the requirements of the spoke part on the plasticity and toughness and the strength. The Si content of the rim part is 4.1-4.5%, so that the obtained alloy is subjected to low-pressure casting and near-net forming, and then is extruded and deformed to a designed size, holes are reduced and even compacted in the process, the air tightness of the rim is improved, and the air leakage of a tire is reduced. The deformation produces strong work hardening and subgrain strengthening, and high strength and hardness are obtained. Therefore, the overall comprehensive performance of the obtained wheel is greatly improved. The performance of the rim and the spoke of the wheel after the casting forming processing and the heat treatment is detected as follows:
the tensile strength of the rim part is: 295-325 MPa, and the yield strength is as follows: 205-235 MPa, and the hardness is as follows: 86-88 HB, elongation: 8.4-8.8%. The air tightness of the rim part is detected by a helium detection method, and the leak rate is 1.0 multiplied by 10-7～1.0×10- 6The mbarl/s is qualified, and the leakage rate of the rim part is 1.0 multiplied by 10 through detection-6～0.4×10-6The air tightness of the rim is greatly improved between mbarl/s.
The tensile strength of the spoke part is as follows: 262-280 MPa, and the yield strength is: 160-170 MPa, and the hardness is: the elongation of 77-80 HB is as follows: 9.1 to 9.5 percent.
After weighing, compared with the wheel prepared by adopting the A356 aluminum alloy material and adopting low-pressure casting molding, the novel composite aluminum alloy wheel prepared by the casting molding process disclosed by the invention has the advantages that the weight is reduced by 0.5-1.0 kg, and the light weight of the automobile wheel is further promoted.
In the bending fatigue test, no abnormity occurs at 36-37 ten thousand revolutions under the load of 4.2-4.5 KN/M; in the radial fatigue test, no abnormality occurs at 182-183 ten thousand revolutions under the condition that the load in the radial direction is 20.2-20.5 KN; in the 13-degree impact test, an impact hammer of 740-752 kg falls 240-243 mm from the 0-degree direction to cause impact, and the wheel is not abnormal; in a 90-degree impact test, an 1100-1200 kg impact hammer falls 252-254 mm from the 0-degree direction to cause impact, and the wheel still has no abnormality. The wheel invented in the above fatigue test and impact test has no crack, and the fatigue life is good.
2. The invention optimally designs two alloy materials with different components according to respective performance indexes of each part, reduces the effect of harmful elements by adding proper amounts of Cr, Mn and Zr into a rim and a spoke, and improves the comprehensive performance of the wheel.
3. Different components are adopted at different parts of the wheel, the addition of Si is greatly reduced at the rim part, the contents of Si, Mg, Ti and Sr are reduced at the spoke part, the addition of redundant alloy elements is saved, and the manufacturing cost of the wheel is reduced.
4. The solution heat preservation time in the solution treatment process of the heat treatment is shortened to only 3h, the heat preservation time of the artificial aging treatment is correspondingly shortened to only 3.5h, the heat treatment time is saved by 20 percent, namely, the power consumption in the heat treatment process is reduced, and the integral production cost of the wheel is greatly reduced.
5. When Sr is added, 0.2 x 5mm flat Sr strips are fed into a molten pool, and the contact surface of the flat Sr strips with the molten liquid is larger than that of round Sr strips, so that the melting time is reduced, the distribution uniformity of the flat Sr strips in the aluminum alloy solution is improved, and the modification effect of eutectic Si phase is improved.
Drawings
Fig. 1 is a schematic diagram of a simple structure of the novel composite aluminum alloy wheel after casting forming, wherein: 1 rim, 2 spokes.
Detailed Description
The technical solution of the present invention is further illustrated by the following specific examples.
In order to meet the casting forming method adopted by the invention, the alloy components designed in the embodiment are the following components in percentage by mass (wt%) at the rim part: 4.1-4.5% of Si, 0.80-0.85% of Mg, 0.17-0.2% of Ti, 0.10-0.15% of Cr, 0.10-0.15% of Mn, 0.015-0.017% of Sr and the balance of aluminum; the spoke part alloy comprises the following material components in percentage by mass (wt%): 6.5 to 6.7 percent of Si, 0.21 to 0.25 percent of Mg, 0.13 to 0.16 percent of Ti, 0.011 to 0.013 percent of Sr, 0.18 to 0.22 percent of Cr, 0.18 to 0.22 percent of Mn0.18 to 0.2 percent of Zr, and the balance of aluminum. The following table shows the material compositions of the novel aluminum alloy wheel in mass percent (wt%):
example alloy material composition of rim part:
group of Si Mg Ti Sr Cr Mn Al
1 4.1 0.80 0.17 0.015 0.10 0.10 Balance of
2 4.3 0.83 0.17 0.015 0.10 0.10 Balance of
3 4.3 0.83 0.19 0.016 0.13 0.13 Balance of
4 4.5 0.85 0.19 0.016 0.13 0.13 Balance of
5 4.5 0.85 0.20 0.017 0.15 0.15 Balance of
In the first group of the table, the contents of Si and Mg are lower, meanwhile, the contents of Cr, Sr and Ti are less, the alloy has better fluidity, and the alloy can be innovated by low-pressure casting. The alloy has good plasticity, good extrusion deformation capability and work hardening potential, and is easy to extrude after casting. Si and Mg are mainly used for forming a strengthening phase, and the addition of Sr and Ti can refine alpha-Al dendrites and eutectic Si phases, so that the morphology of the eutectic phases can be improved and the eutectic phases become continuous and uniform. After Cr and Mn are added, impurities can be purified, and the number of second phases precipitated during aging and the refinement of the second phases are increased.
In the second group in the table, compared with the first group, Si is increased by 0.2%, Mg is increased by 0.03%, the number of strengthening phases formed in the alloy is increased, and the strength is improved without greatly influencing the ductility and toughness because the increasing range of Si and Mg is limited.
In the third group in the table, compared with the second group, the Ti and Sr contents are increased, the metamorphic effect is improved, alpha-Al dendrites are further refined, the integral morphology of the structure is improved, and the strong hardness and the plastic toughness are improved. Meanwhile, Cr and Mn are increased by 0.03 percent, the harmful effect of impurities is further reduced, and the plasticity and toughness are improved.
In the fourth group in the table, Si is increased by 0.2% and Mg is increased by 0.02% compared with the third group, so that the alloy strength and hardness are increased, but the plasticity is reduced due to the increase of the Si ratio, and the subsequent extrusion deformation is difficult.
In the fifth group of the table, compared with the fourth group, the contents of Si and Mg are unchanged, the contents of Ti, Sr, Cr and Mn are increased, all the elements reach the maximum addition value in the design, the effects of modification, refinement and impurity removal and purification of the alloy are improved compared with the fourth group, the strength and the toughness are improved, and meanwhile, the ductility and the toughness are not greatly lost. .
Spoke part example alloy material composition:
group of Si Mg Ti Sr Cr Zr Mn Al
1 6.5 0.21 0.13 0.011 0.18 0.16 0.18 Balance of
2 6.6 0.23 0.13 0.011 0.18 0.17 0.18 Balance of
3 6.6 0.23 0.14 0.012 0.20 0.18 0.20 Balance of
4 6.7 0.25 0.14 0.012 0.20 0.18 0.20 Balance of
5 6.7 0.25 0.16 0.013 0.22 0.20 0.22 Balance of
In the first group of the table, the contents of Si and Mg are lower, meanwhile, the contents of Cr, Sr, Ti, Zr and Mn are less, the alloy has better fluidity, and can be innovated by low-pressure casting. The alloy has good ductility and toughness and low strength. Si and Mg are mainly used for forming a strengthening phase, and the addition of Sr, Ti and Zr can refine alpha-Al dendrites and eutectic Si phases, so that the morphology of the eutectic phase can be improved and the eutectic phase becomes continuous and uniform. After Cr and Mn are added, impurities can be purified, and the number of second phases precipitated during aging and the refinement of the second phases are increased.
In the second group of the above table, Si is increased by 0.1% and Mg is increased by 0.02% as compared with the first group, and the strengthening phases formed in the alloy are increased, thereby improving the alloy strength. Because the increase range of Si and Mg is limited, the strength is improved without causing great influence on the plasticity and toughness.
In the third group in the table, compared with the second group, the contents of Ti, Sr and Zr are increased, the metamorphic effect is improved, alpha dendrite is further refined, the integral morphology of the structure is improved, and the strong hardness and the plastic toughness are improved. Meanwhile, Cr and Mn are increased by 0.02 percent, the harmful effect of impurities is further reduced, and the plasticity and toughness are improved.
In the fourth group of the above table, Si is increased by 0.1% and Mg is increased by 0.02% compared with the third group, so that the alloy strength and hardness are increased, but the ductility and toughness are reduced due to the increase of the Si phase ratio.
In the fifth group of the table, compared with the fourth group, the contents of Si and Mg are unchanged, the contents of Ti, Sr, Cr, Zr and Mn are increased, all the elements reach the maximum addition value in the design, the modification, refinement and impurity removal and purification effects of the alloy are improved compared with the fourth group, and the strength, hardness and toughness are improved.
Example 1:
according to the components of a rim, namely 4.3 percent of Si, 0.83 percent of Mg, 0.17 percent of Ti, 0.10 percent of Cr, 0.10 percent of Mn, 0.015 percent of Sr and the balance of aluminum, the components of a spoke, namely Si 6.5 percent, 0.21 percent of Mg, 0.13 percent of Ti, 0.011 percent of Sr, 0.18 percent of Cr, 0.16 percent of Zr, 0.18 percent of Mn and the balance of aluminum, respectively carrying out batching and smelting to prepare alloy liquid, then respectively adopting different casting forming methods to prepare a complete wheel and carrying out subsequent production processes such as subsequent cooling, heat treatment and the like.
The alloy melt obtained by designing alloy components on the wheel spokes is molded by adopting a low-pressure casting process, wherein the side die temperature of a low-pressure casting die is controlled at 460 ℃. The temperature of the molten aluminum is kept at 720 ℃, the molten aluminum is introduced into a low-pressure casting machine for carrying out low-pressure casting on the spoke, and the technological parameter requirements in the casting process are as follows:
liquid lifting: pressure 250bar, time 16 s;
filling a mold: pressure 400bar, time 36 s;
supercharging: pressure 850bar, time 46 s;
pressure maintaining: pressure 860bar, time 52 s.
Releasing pressure, solidifying, cooling, demoulding and taking out to obtain a spoke part of the wheel;
the alloy solution obtained by designing alloy components for the wheel rim is molded by adopting a low-pressure casting and extrusion molding process, wherein the side die temperature of the low-pressure casting die is consistent with that of the die during low-pressure casting of the spoke, and is also controlled at 460 ℃. The temperature of the aluminum liquid is kept at 725 ℃, the aluminum liquid is introduced into a low-pressure casting machine for low-pressure casting of the rim, and the technological parameter requirements in the casting process are as follows:
liquid lifting: pressure 260bar, time 18 s;
filling a mold: pressure 410bar, time 38 s;
supercharging: pressure 860bar, time 48 s;
pressure maintaining: pressure 870bar, time 54 s.
Releasing pressure, solidifying, cooling, demoulding and taking out to obtain a spoke part of the wheel;
heating the cast wheel to 240 ℃, putting the wheel into a wheel extrusion die after diathermy, and carrying out isothermal extrusion on the rim part by using a press machine, wherein the rolling reduction is 11% of the wall thickness of the rim, and the extrusion strain rate is 0.05S-1And extruding and deforming until the wheel rim is designed to be in the size.
And carrying out heat treatment on the obtained wheel, namely sequentially carrying out solution treatment and artificial aging treatment.
The solution treatment process comprises the following steps: carrying out solid solution and heat preservation at 540 +/-5 ℃ for 3h, discharging from the furnace and quenching, carrying out water quenching at 40 ℃ in warm water, wherein the time from discharging to quenching in water is less than or equal to 15s, and the cooling time in water is about 4 min;
the artificial aging treatment process comprises the following steps: aging and preserving heat for 3.5h at 170 +/-5 ℃, and discharging and air cooling.
The detection proves that the tensile strength of the alloy material at the rim part is 307MPa, the yield strength is 209MPa, the hardness is 86HB, the elongation is 8.7 percent, the air tightness detection of the rim part adopts a helium detection method, and the leak rate is 1.0 multiplied by 10-7～1.0×10-6The mbarl/s is qualified, and the leakage rate of the rim part is 0.9 multiplied by 10 through detection-6Between mbarl/s, the air tightness of the rim is greatly improved; by weighing, compared with the wheel prepared by adopting the A356 aluminum alloy material and adopting low-pressure casting molding, the novel composite aluminum alloy wheel prepared by the casting molding process disclosed by the invention has the advantages that the weight is reduced by 0.65kg, and the light weight of the automobile wheel is further promoted. The tensile strength of the obtained alloy at the spoke part is 262MPa, the yield strength is 160MPa, the hardness is 78HB, and the elongation is 9.5%. 36 ten thousand rotations under the load of 4.2KN/M in the bending fatigue test have no abnormity; no abnormality occurs in 182 ten thousand revolutions under the condition of load of 20.2KN in the radial direction in the radial fatigue test; in the 13-degree impact test, a 740kg impact hammer falls 240mm from the 0-degree direction to cause impact, and the wheel is not abnormal; in the 90-degree impact test, an impact hammer of 1100kg falls by 252mm from the direction of 0 degrees to cause impact, and the wheel still has no abnormity. The wheel invented in the above fatigue test and impact test has no crack, and the fatigue life is good.
Example 2:
according to the components of a rim, namely 4.3 percent of Si, 0.83 percent of Mg, 0.19 percent of Ti, 0.13 percent of Cr, 0.13 percent of Mn, 0.016 percent of Sr and the balance of aluminum, the components of a spoke, namely Si 6.6 percent, 0.23 percent of Mg, 0.14 percent of Ti, 0.012 percent of Sr, 0.20 percent of Cr, 0.18 percent of Zr, 0.20 percent of Mn and the balance of aluminum, respectively carrying out batching and smelting to prepare alloy liquid, then respectively adopting different casting forming methods to prepare a complete wheel and carrying out subsequent production processes, such as subsequent cooling, heat treatment and the like.
And forming the alloy melt obtained by designing the alloy components of the wheel spokes by adopting a low-pressure casting process, wherein the side die temperature of the low-pressure casting die is controlled at 470 ℃. The temperature of the aluminum liquid is kept at 730 ℃, the aluminum liquid is led into a low-pressure casting machine for low-pressure casting of a rim, and the technological parameter requirements in the casting process are as follows:
liquid lifting: pressure 260bar, time 18 s;
filling a mold: pressure 410bar, time 38 s;
supercharging: pressure 860bar, time 48 s;
pressure maintaining: pressure 870bar, time 54 s.
Releasing pressure, solidifying, cooling, demoulding and taking out to obtain a spoke part of the wheel;
the alloy melt obtained by designing the alloy components for the rim is molded by adopting a low-pressure casting and extrusion molding process, wherein the side die temperature of the low-pressure casting die is consistent with that of the die during the low-pressure casting of the spoke, and is also controlled at 470 ℃. The temperature of the aluminum liquid is kept at 735 ℃, the aluminum liquid is led into a low-pressure casting machine for low-pressure casting of the rim, and the technological parameter requirements in the casting process are as follows:
liquid lifting: pressure 270bar, time 20 s;
filling a mold: pressure 420bar, time 40 s;
supercharging: pressure 870bar, time 50 s;
pressure maintaining: pressure 880bar, time 56 s.
Releasing pressure, solidifying, cooling, demoulding and taking out to obtain a spoke part of the wheel;
heating the cast wheel to 250 ℃, putting the wheel into a wheel extrusion die after diathermy, carrying out isothermal extrusion on the rim part by using a press machine, wherein the reduction is 13% of the wall thickness of the rim, and the extrusion strain rate is 0.06S-1And extruding and deforming until the wheel rim is designed to be in the size.
And carrying out heat treatment on the obtained wheel, namely sequentially carrying out solution treatment and artificial aging treatment.
The solution treatment process comprises the following steps: carrying out solid solution and heat preservation at 540 +/-5 ℃ for 3h, discharging from the furnace and quenching, carrying out water quenching at 50 ℃ in warm water, wherein the time from discharging to quenching in water is less than or equal to 15s, and the cooling time in water is about 5 min;
the artificial aging treatment process comprises the following steps: aging and preserving heat for 3.5h at 170 +/-5 ℃, and discharging and air cooling.
The detection proves that the tensile strength of the alloy material at the rim part is 321MPa, the yield strength is 226MPa, the hardness is 87HB, the elongation is 8.6 percent, the air tightness detection of the rim part adopts a helium detection method, and the leak rate is 1.0 multiplied by 10-7～1.0×10-6The wheel rim part is obtained by detecting that mbarl/s is qualifiedHas a leak rate of 0.7X 10-6Between mbarl/s, the air tightness of the rim is greatly improved; after weighing, compared with the wheel prepared by adopting the A356 aluminum alloy material and adopting low-pressure casting molding, the novel composite aluminum alloy wheel prepared by the casting molding process disclosed by the invention has the advantages that the weight is reduced by 0.72kg, and the light weight of the automobile wheel is further promoted. The tensile strength of the obtained alloy at the spoke part is 275MPa, the yield strength is 167MPa, the hardness is 79HB, and the elongation is 9.3%. 36.5 million revolutions under the load of 4.3KN/M in the bending fatigue test have no abnormality; no abnormality occurs in 182.5 ten thousand revolutions under the condition of load of 20.3KN in the radial direction in the radial fatigue test; in the 13-degree impact test, a 745kg impact hammer is impacted by falling for 242mm in the 0-degree direction, and the wheel is not abnormal; in the 90-degree impact test, an impact hammer of 1150kg falls 253mm from the direction of 0 degrees to cause impact, and the wheel still has no abnormity. The wheel invented in the above fatigue test and impact test has no crack, and the fatigue life is good.
Example 3:
according to the components of a rim, namely 4.5 percent of Si, 0.85 percent of Mg, 0.20 percent of Ti, 0.15 percent of Cr, 0.15 percent of Mn, 0.017 percent of Sr and the balance of aluminum, 6.7 percent of spoke components, 0.25 percent of Mg, 0.16 percent of Ti, 0.013 percent of Sr, 0.22 percent of Cr, 0.20 percent of Zr, 0.22 percent of Mn and the balance of aluminum, respectively carrying out batching and smelting to prepare alloy liquid, then respectively adopting different casting forming methods to prepare a complete wheel and carrying out subsequent production processes such as subsequent cooling, heat treatment and the like.
The alloy melt obtained by designing alloy components on the wheel spokes is molded by adopting a low-pressure casting process, wherein the side die temperature of a low-pressure casting die is controlled at 480 ℃. The temperature of the aluminum liquid is kept at 740 ℃, the aluminum liquid is led into a low-pressure casting machine for low-pressure casting of a rim, and the technological parameter requirements in the casting process are as follows:
liquid lifting: pressure 270bar, time 20 s;
filling a mold: pressure 420bar, time 40 s;
supercharging: pressure 870bar, time 50 s;
pressure maintaining: pressure 880bar, time 56 s.
Releasing pressure, solidifying, cooling, demoulding and taking out to obtain a spoke part of the wheel;
the alloy solution obtained by designing alloy components for the rim is molded by adopting a low-pressure casting and extrusion molding process, wherein the side die temperature of the low-pressure casting die is consistent with that of the die during low-pressure casting of the spoke, and is also controlled at 480 ℃. The temperature of the aluminum liquid is kept at 740 ℃, the aluminum liquid is led into a low-pressure casting machine for low-pressure casting of a rim, and the technological parameter requirements in the casting process are as follows:
liquid lifting: pressure 280bar, time 22 s;
filling a mold: pressure 430bar, time 42 s;
supercharging: pressure 880bar, time 52 s;
pressure maintaining: pressure 890bar, time 58 s.
Releasing pressure, solidifying, cooling, demoulding and taking out to obtain a spoke part of the wheel;
heating the cast wheel to 260 ℃, putting the wheel into a wheel extrusion die after diathermy, and carrying out isothermal extrusion on the rim part by using a press machine, wherein the rolling reduction is 15% of the wall thickness of the rim, and the extrusion strain rate is 0.07S-1And extruding and deforming until the wheel rim is designed to be in the size.
And carrying out heat treatment on the obtained wheel, namely sequentially carrying out solution treatment and artificial aging treatment.
The solution treatment process comprises the following steps: carrying out solid solution and heat preservation at 540 +/-5 ℃ for 3h, discharging from the furnace and quenching, carrying out water quenching at 60 ℃ in warm water, wherein the time from discharging to quenching in water is less than or equal to 15s, and the cooling time in water is about 6 min;
the artificial aging treatment process comprises the following steps: aging and preserving heat for 3.5h at 170 +/-5 ℃, and discharging and air cooling.
The detection proves that the tensile strength of the alloy material at the rim part is 325MPa, the yield strength is 235MPa, the hardness is 88HB, the elongation is 8.5 percent, the air tightness detection of the rim part adopts a helium detection method, and the leak rate is 1.0 multiplied by 10-7～1.0×10-6The mbarl/s is qualified, and the leakage rate of the rim part is 0.5 multiplied by 10 through detection-6Between mbarl/s, the air tightness of the rim is greatly improved; after weighing, compared with the wheel prepared by adopting A356 aluminum alloy material and adopting low-pressure casting and molding, the novel composite aluminum alloy wheel prepared by adopting the casting and molding process adopted in the invention has the advantages that the weight is higherThe weight of the automobile wheel is reduced by 0.83kg, and the weight of the automobile wheel is further promoted. The tensile strength of the obtained alloy at the spoke part is 280MPa, the yield strength is 170MPa, the hardness is 80HB, and the elongation is 9.1%. No abnormity occurs at 37 ten thousand revolutions under the load of 4.5KN/M in the bending fatigue test; in the radial fatigue test, no abnormality occurs in 183 ten thousand rotations under the condition that the load in the radial direction is 20.5 KN; in the 13-degree impact test, the 752kg impact hammer falls 243mm in the 0-degree direction to cause impact, and the wheel is not abnormal; in the 90-degree impact test, a 1200kg impact hammer falls 254mm from the 0-degree direction to cause impact, and the wheel still has no abnormality. The wheel invented in the above fatigue test and impact test has no crack, and the fatigue life is good.
According to the technical scheme, the tensile strength of the obtained alloy material at the rim part is more than 295MPa, the yield strength is more than 205MPa, the hardness is 86-88 HB, and the elongation is more than 8.4%; the tensile strength of the obtained alloy at the spoke part is greater than 262MPa, the yield strength is greater than 160MPa, the hardness is 77-80 HB, the elongation is greater than 9.1%, the performance of the obtained alloy is obviously superior to that of the existing vehicle wheel, the performance matching of all parts is good, the overall performance of the wheel is superior to that of the existing aluminum alloy wheel, and the fatigue resistance and the impact resistance are good. After 2800Nm bending moment and 35 ten thousand turning curve fatigue tests are finished, the wheel has no crack, and the offset of a loading point does not exceed 12 percent of the initial full loading amount; the wheel has no cracks after completing the tests of tyre inflation pressure of 450KPa, nut torque of 130Nm, 15000N load and radial fatigue of 180 kiloturns; the impact position is 13 degrees and 90 degrees, the tire inflation pressure is 180KPa, the nut torque is 130Nm, any section of the rear spoke and the rim has no crack after the 280mm drop height impact test, any section of the rim has no air hole, and the rim has no separation and air leakage. The novel composite aluminum alloy wheel has the advantages of no defect in appearance, high surface quality, high strength and hardness, good plasticity and toughness, difficult deformation, air leakage and the like.

Claims (6)

1. A composite aluminum alloy wheel is characterized in that:
the rim and the spoke of the composite aluminum alloy wheel are made of different alloy materials respectively;
the wheel rim part alloy material comprises the following components in percentage by mass: 4.1-4.5% of Si, 0.80-0.85% of Mg0.17-0.2% of Ti, 0.10-0.15% of Cr, 0.10-0.15% of Mn, 0.015-0.017% of Sr and the balance of aluminum;
the spoke part alloy material comprises the following components in percentage by mass: 6.5-6.7% of Si, 0.21-0.25% of Mg, 0.13-0.16% of Ti, 0.011-0.013% of Sr, 0.18-0.22% of Cr, 0.18-0.22% of Mn, 0.16-0.2% of Zr, and the balance of aluminum;
the composite aluminum alloy wheel is prepared by the method comprising the following steps:
step 1: spoke part forming
1a, preparing materials
Weighing pure aluminum, Al-Si intermediate alloy, Al-Mg intermediate alloy, Al-Ti intermediate alloy, Al-Zr intermediate alloy, Al-Sr intermediate alloy, Al-Cr intermediate alloy and Al-Mn intermediate alloy according to the proportion;
1b, melting
Adding the dried Al-Si intermediate alloy into the preheated crucible, adding pure aluminum to cover the upper surface of the Al-Si intermediate alloy, heating to 750 ℃ along with the furnace, standing and preserving heat for 20min after the Al-Si intermediate alloy is completely melted; then adding Al-Ti intermediate alloy, Al-Zr intermediate alloy, Al-Cr intermediate alloy and Al-Mn intermediate alloy into the melted alloy melt, standing and keeping the temperature for 10min after all the intermediate alloy is melted; adjusting the temperature to 720 ℃, adding Al-Mg intermediate alloy into the alloy melt, stirring for 3-5 minutes by using a quartz rod after the Al-Mg intermediate alloy is completely melted or dissolved so as to ensure that the elements are uniformly distributed, standing and keeping the temperature for 10 min;
1c refining and modification
Rapidly skimming dross on the surface layer of the alloy melt obtained in the step 1b by using a skimming ladle, and then using a graphite bell jar to skim dross C2Cl6Pressing a refining agent into the molten liquid to 1/3 position of the bottom of the crucible, keeping the same direction, rotating slowly, refining and degassing, then sending Al-Sr intermediate alloy into a molten pool, standing at 720 ℃ and keeping the temperature for 10-20 min, and finally, scattering a slag removal agent for removing slag;
1d, pouring
Molding the alloy melt obtained in the step 1c by adopting a low-pressure casting process, wherein the side die temperature of a low-pressure casting die is controlled to be 460-480 ℃, the temperature of the alloy melt is kept to be 720-740 ℃, introducing into a low-pressure casting machine for carrying out low-pressure casting on a spoke, releasing pressure, solidifying, cooling, demoulding and taking out to obtain a spoke part of the wheel;
step 2: rim part forming
2a, preparing materials
Weighing pure aluminum, Al-Si intermediate alloy, Al-Mg intermediate alloy, Al-Ti intermediate alloy, Al-Cr intermediate alloy, Al-Mn intermediate alloy and 0.2 x 5mm flat Sr strips according to the proportion;
2b, melting
Adding the dried Al-Si intermediate alloy into the preheated crucible, adding pure aluminum to cover the Al-Si intermediate alloy, heating to 750 ℃ along with the furnace, standing and preserving heat for 20min after the Al-Si intermediate alloy is completely melted; then adding Al-Ti intermediate alloy, Al-Cr intermediate alloy and Al-Mn intermediate alloy into the molten alloy melt, standing and keeping the temperature for 10min after all the intermediate alloy is molten; adjusting the temperature to 720 ℃, adding Al-Mg intermediate alloy into the alloy melt, stirring for 3-5 minutes by using a quartz rod after the Al-Mg intermediate alloy is completely melted or dissolved so as to ensure that the elements are uniformly distributed, standing and keeping the temperature for 10 min;
2c refining and modification
Rapidly skimming the dross on the surface layer of the alloy melt by using a skimming ladle, and then using a graphite bell jar to skim C2Cl6Pressing the refining agent into the molten liquid to 1/3 parts at the bottom of the crucible, keeping the same direction, rotating slowly, refining and degassing, then sending flat Sr strips with the thickness of 0.2 x 5mm into a molten pool, standing at 720 ℃ and keeping the temperature for 10-20 min, and finally, scattering a slag removing agent for removing slag;
2d, pouring
Molding the alloy melt obtained in the step 2c by adopting a low-pressure casting process, wherein the side die temperature of a low-pressure casting die is controlled to be 460-480 ℃, the temperature of the alloy melt is kept to be 720-740 ℃, introducing into a low-pressure casting machine for low-pressure casting of a rim, releasing pressure, solidifying, cooling, demoulding and taking out to obtain a rim part of the wheel;
and step 3: extrusion molding
Heating the wheel formed by the low-pressure casting to 240-260 ℃, putting the wheel into a wheel extrusion die after heat penetration, carrying out isothermal extrusion on the rim part of the wheel by using a press machine, and carrying out extrusion deformation until the design size of the rim is reached;
and 4, step 4: thermal treatment
Carrying out heat treatment on the wheel obtained by adopting the casting and forming process, namely sequentially carrying out solid solution treatment and artificial aging treatment;
during casting, closed crucibles, liquid lifting pipes and pouring systems which are used for containing different aluminum alloy liquids are respectively arranged at the corresponding parts of the spoke and the rim of the wheel, and the alloy at the spoke part is smelted through batching and then enters a spoke cavity under the action of low pressure through the liquid lifting pipes distributed at the corresponding part of the spoke; alloy at the rim part is smelted through ingredients and then enters a rim cavity through liquid lifting pipes distributed at the corresponding part of the rim under the action of low pressure; keeping the pressure until the alloy liquid in the casting mold is completely solidified, then releasing the gas pressure, and automatically dropping the aluminum liquid which does not participate in solidification in the riser tube back into the crucible under the action of gravity; after preparing the rim, the rim part is extruded and formed to reach the design size; the spoke part of the wheel is cast and molded by low pressure, and the rim part is subjected to heat treatment after low pressure casting molding and extrusion molding;
the rising speed of the aluminum alloy melt in the low-pressure liquid rising pipe corresponding to the rim and the spoke is determined by the structural size of the wheel, namely the volume ratio V of the rim to the spokeA：VBAnd determining the rising speed ratio of the two molten aluminum alloys with different compositions in the lift pipe.
2. The composite aluminum alloy wheel of claim 1, wherein:
in the step 3, the rolling reduction in isothermal extrusion is 10-16% of the wall thickness, and the extrusion strain rate is 0.05-0.08S-1。
3. The composite aluminum alloy wheel of claim 1, wherein:
in step 4, the solution treatment process comprises the following steps: and (3) carrying out solid solution and heat preservation at 540 +/-5 ℃ for 3h, discharging and quenching, carrying out water quenching at 40-60 ℃ in warm water, wherein the time from discharging to quenching in water is less than or equal to 15s, and the cooling time in water is 4-6 min.
4. The composite aluminum alloy wheel of claim 1, wherein:
in step 4, the artificial aging treatment process comprises the following steps: aging and preserving heat for 3.5h at 170 +/-5 ℃, and discharging and air cooling.
5. The composite aluminum alloy wheel of claim 1, wherein:
the technological parameters in the casting process in the step 1d are as follows:
liquid lifting: the pressure is 250-270 bar, and the time is 16-20 s;
filling a mold: the pressure is 400-420 bar, and the time is 36-40 s;
supercharging: the pressure is 850-870 bar, and the time is 46-50 s;
pressure maintaining: the pressure is 860 to 880bar, and the time is 52 to 56 s.
6. The composite aluminum alloy wheel of claim 1, wherein:
and 2d, setting the technological parameters in the casting process as follows:
liquid lifting: the pressure is 260-280 bar, and the time is 18-22 s;
filling a mold: the pressure is 410-430 bar, and the time is 38-42 s;
supercharging: the pressure is 860-880 bar, and the time is 48-52 s;
pressure maintaining: the pressure is 870-890 bar, and the time is 54-58 s.
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