CN110952048B - Heat treatment method suitable for A356.2 alloy low-pressure casting hub - Google Patents
Heat treatment method suitable for A356.2 alloy low-pressure casting hub Download PDFInfo
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- CN110952048B CN110952048B CN201911336155.1A CN201911336155A CN110952048B CN 110952048 B CN110952048 B CN 110952048B CN 201911336155 A CN201911336155 A CN 201911336155A CN 110952048 B CN110952048 B CN 110952048B
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- 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
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- 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
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- 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
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Abstract
The invention belongs to the technical field of non-ferrous metal heat treatment, relates to a heat treatment method, and particularly relates to a heat treatment method suitable for an A356.2 alloy low-pressure casting hub, which comprises the following steps: homogenizing the low-pressure cast hub at 440-460 ℃ for 11-13 hours, performing solid solution treatment after homogenization at 540-550 ℃ for 4-6 hours, immediately quenching at 70-90 ℃ for no more than 25 seconds, and immediately aging at 145-155 ℃ for 4-5 hours. The heat treatment method greatly improves the comprehensive mechanical property of the low-pressure cast hub, greatly improves the tensile strength and the yield strength, obviously increases the elongation after fracture, obviously improves the microstructure, and ensures that various mechanical property indexes meet the technical requirements, so that the A356.2 alloy hub cast under low pressure is more suitable for the production requirements of high-quality hubs of export high-grade cars and large trucks.
Description
Technical Field
The invention belongs to the technical field of non-ferrous metal heat treatment, relates to a heat treatment method, and particularly relates to a heat treatment method suitable for an A356.2 alloy low-pressure casting hub.
Background
The light weight technology of automobiles promotes the continuous development of the automobile industry. Researches show that when the weight of the automobile is reduced by 10%, 3% -7% of fuel consumption can be saved, the fuel economy of the automobile is greatly improved, the emission of carbon dioxide and PM2.5 of the automobile in the service life can be reduced, and the automobile fuel has very important effects on energy conservation, emission reduction and haze treatment. The aluminum alloy wheel hub is used as an important part of an automobile, and has important significance in reducing weight of the automobile compared with the light weight of the automobile. The main manufacturing methods of the aluminum alloy hub comprise a casting method, a forging method, a stamping method, a spinning method, a semi-solid die forging method and the like. Wherein, the aluminum alloy hub cast by low pressure is dominant, which accounts for about 75% of the total aluminum alloy hub, the forged aluminum alloy hub accounts for about 15%, and the aluminum alloy hub manufactured by other methods accounts for about 10%. The most commonly used alloy for low pressure casting of hubs is Al-Si series cast aluminum alloy. The heat treatment commonly used for low pressure casting of a356.2 aluminum alloy hubs is typically a T6 heat treatment process, i.e., a high temperature solution followed by a quench treatment and then immediately followed by an artificial aging treatment.
The wheel hub has dendritic crystal segregation in the solidification process of low-pressure casting, and has the phenomena of coarse precipitated phases, uneven chemical component distribution and the like in grain boundaries and crystal grains, and the phenomena that the solid solution and the aging treatment in the existing heat treatment process cannot completely eliminate and improve the phenomena often cause low alloy strength and are difficult to meet the use requirements. The homogenization treatment can promote the soluble low-melting-point eutectic phase in the alloy to dissolve into the matrix to reach a complete or nearly complete dissolution state, improve the solid solubility of alloy elements in the matrix, reduce the volume fraction of a coarse second phase, enable the chemical component distribution of the alloy to tend to be uniform, enable the structure to reach or approach a balance state, improve the strength of the alloy and simultaneously improve the plasticity of the alloy. Therefore, the homogenization process is creatively introduced into the heat treatment process of the low-pressure cast hub of the A356.2 alloy wheel, and the aim of improving the comprehensive mechanical property of the low-pressure cast hub is fulfilled by the novel heat treatment method.
Disclosure of Invention
In view of the above-mentioned deficiencies in the prior art, it is an object of the present invention to provide a heat treatment process suitable for low pressure casting of a356.2 alloy hubs.
The technical scheme is as follows:
a heat treatment method suitable for a356.2 alloy low pressure cast hubs, comprising the steps of: homogenizing the cast product, taking out the homogenized product from a furnace, air-cooling to room temperature, carrying out T6 heat treatment, namely immediately quenching after solid solution treatment, and carrying out aging treatment after quenching, wherein the temperature of the homogenizing treatment is 440-540 ℃, and the time is 4-13 hours.
In the preferred embodiment of the invention, the homogenization treatment is carried out by putting the cast product into a medium-temperature box type resistance furnace.
In the preferred embodiment of the invention, the temperature of the solution treatment is 540-550 ℃, and the time is 4-6 hours, preferably 545 ℃ and 5 hours.
In the preferred embodiment of the invention, the water temperature of the quenching treatment is 70-90 ℃, preferably 80 ℃, and the quenching transfer time is not more than 30 seconds.
In the preferred embodiment of the invention, the temperature of the aging treatment is 145-155 ℃, the aging time is 4-5 hours, preferably 150 ℃, and 4.5 hours.
The casting process of the aluminum alloy hub comprises the following steps: during smelting, feeding is carried out in the form of aluminum ingots and intermediate alloys, aluminum liquid is modified by adopting aluminum strontium alloy AlSr10, a grain refiner AlTiB 5B1 is added for refining, after modification and refinement, the aluminum liquid is transported by a transfer ladle and poured into a low-pressure die casting machine, the casting temperature of the aluminum liquid is 690 +/-10 ℃, after low-pressure casting is carried out under pressure, sampling is carried out from the upper rim position of a hub, and the sampling position and the sample size (mm) are shown in figures 1 and 2.
The invention provides a heat treatment method for aging after homogenizing treatment and solution treatment in the heat treatment process of low-pressure cast aluminum alloy hubs. The samples of the as-cast alloy, which only adopt homogenization, only adopt solution treatment and both homogenization and solution treatment are respectively sampled for structure analysis, and the results show that: the crystalline grains in the as-cast alloy are coarse and contain a plurality of dendritic crystals, and the eutectic silicon is mostly needle-shaped, rod-shaped and blocky and has larger size. Most dendrites in the alloy structure subjected to homogenization treatment are converted into isometric crystals, a plurality of fine and dense second phases are precipitated in grain boundaries and crystal grains, and the morphology and the size of eutectic silicon are not obviously changed. In the alloy structure subjected to only the solution treatment, the spheroidization degree of eutectic silicon is remarkably increased. In the structure after homogenization and solution treatment, crystal grains are completely changed into isometric crystals, the size of eutectic silicon is reduced, the spheroidization degree of the eutectic silicon is higher than that of the eutectic silicon in a solid solution state, and the bulk density of the eutectic silicon is also increased. The key point of obviously improving the mechanical property of the hub sample treated by the heat treatment method is well explained.
By adopting the heat treatment method for the A356.2 alloy low-pressure cast hub, the elongation A after fracture of the alloy can reach about 12%, the elongation (upper rim sampling) far exceeding the national performance standard of the A356.2 alloy low-pressure cast hub is not lower than 7%, the tensile strength of the alloy reaches 256MPa, the tensile strength is improved by nearly 35% compared with the existing heat treatment method (hereinafter referred to as the original process, 5h + quenching at 550 ℃ for solid solution + 120 ℃ for 3.5h for aging), the yield strength reaches 175MPa, the yield strength is improved by 55%, and the technical requirements of export high-grade car hub products can be completely met.
Advantageous effects
After the heat treatment process disclosed by the invention, the strength of the low-pressure cast hub is greatly improved, the plasticity is also improved, the tensile strength and the yield strength are greatly improved, the elongation after fracture is obviously increased, the microstructure is obviously improved, and various mechanical property indexes meet the technical requirements, so that the A356.2 alloy hub cast under low pressure is more suitable for the production requirements of high-quality hubs of export high-grade cars and large trucks.
Drawings
FIG. 1 is a schematic view of a hub sampling position, wherein 1 is the sampling position;
FIG. 2 is a schematic drawing of the dimensions of a tensile test specimen;
FIG. 3 is a graph comparing the strength and elongation after fracture of samples obtained in the examples.
Detailed Description
The present invention will be described in detail below with reference to examples to enable those skilled in the art to better understand the present invention, but the present invention is not limited to the following examples.
Unless otherwise defined, terms (including technical and scientific terms) used herein should be construed to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art, and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Example 1
The heat treatment method of the A356.2 aluminum alloy for the low-pressure casting hub comprises the following steps: homogenizing at 445 deg.C for 13 hr, discharging, cooling in air to room temperature, dissolving at 545 deg.C for 6 hr, quenching at 70-90 deg.C for 30 s or less, and aging at 145 deg.C for 5 hr.
See scheme a in table 1 for mechanical property testing.
Example 2
The heat treatment method of the A356.2 aluminum alloy for the low-pressure casting hub comprises the following steps: homogenizing at 450 ℃ for 12 hours, discharging from the furnace after homogenizing, cooling to room temperature in air, then carrying out solid solution treatment, wherein the solid solution temperature is 550 ℃, the solid solution time is 5 hours, quenching treatment is carried out immediately after solid solution, the quenching mode is water quenching, the water temperature is 70-90 ℃, the quenching transfer time is not more than 30 seconds, and aging treatment is carried out after quenching, the aging temperature is 150 ℃, and the aging time is 4.5 hours.
See scheme B in table 1 for mechanical property testing.
Example 3
The heat treatment method of the A356.2 aluminum alloy for the low-pressure casting hub comprises the following steps: homogenizing at 455 ℃ for 11 hours, discharging from the furnace after homogenizing, cooling to room temperature in the air, then carrying out solid solution treatment, wherein the solid solution temperature is 540 ℃, the solid solution time is 5.5 hours, immediately quenching after solid solution, the quenching mode is water quenching, the water temperature is 70-90 ℃, the quenching transfer time is not more than 30 seconds, aging treatment is carried out after quenching, the aging temperature is 155 ℃, and the aging time is 4 hours.
See scheme C in table 1 for mechanical property testing.
After the cast hub upper rim sample is subjected to the heat treatment described in the embodiment, the mechanical property detection is performed, and the mechanical property test result of the alloy sample and the mechanical property data of the original heat treatment process are shown in table 1:
TABLE 1 mechanical Properties of A356.2 alloy under different heat treatment processes
(Note: scheme A, B, C corresponds to example 1, example 2 and example 3 of the present invention, respectively, the original process was solutionizing at 550 ℃ for 5h + quenching + aging at 120 ℃ for 3.5h)
As can be seen from the table 1, the tensile strength and the yield strength of the alloy can be improved by adopting the heat treatment method of the three schemes, and compared with the heat treatment process of the scheme B, the comprehensive mechanical property of the alloy is optimal, the tensile strength is improved by nearly 66MPa compared with the original process, the yield strength is also correspondingly improved by 60MPa, the elongation after fracture of the alloy is stabilized to be more than 10 percent and is far higher than the national standard that the elongation of the A356.2 alloy hub is more than or equal to 7 percent.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present invention or directly or indirectly applied to other related technical fields are included in the scope of the present invention.
Claims (5)
1. A heat treatment method suitable for a356.2 alloy low pressure casting hub, comprising the steps of: homogenizing the cast product, taking out the homogenized product from a furnace, air-cooling to room temperature, performing T6 heat treatment, namely performing quenching treatment immediately after solution treatment, performing aging treatment after quenching, wherein,
the homogenization treatment temperature is 440-460 ℃, and the time is 11-13 hours;
the temperature of the solution treatment is 540-550 ℃, and the time is 4-6 hours;
the water temperature of the quenching treatment is 70-90 ℃, and the quenching transfer time is not more than 30 seconds; the temperature of the aging treatment is 145-155 ℃, and the aging time is 4-5 hours.
2. The heat treatment method for the A356.2 alloy low pressure cast hub as claimed in claim 1 wherein: the homogenization treatment is carried out by putting the cast product into a medium-temperature box type resistance furnace.
3. The heat treatment method for the A356.2 alloy low pressure cast hub as claimed in claim 1 wherein: the temperature of the solution treatment is 545 ℃ and the time is 5 hours.
4. The heat treatment method for the A356.2 alloy low pressure cast hub as claimed in claim 1 wherein: the water temperature of the quenching treatment is 80 ℃.
5. The heat treatment method for the A356.2 alloy low pressure cast hub as claimed in claim 1 wherein: the temperature of the aging treatment is 150 ℃, and the aging time is 4.5 hours.
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| CN113403558A (en) * | 2021-06-22 | 2021-09-17 | 上海嘉朗实业南通智能科技有限公司 | Heat treatment process for casting aluminum-silicon alloy |
| CN115612951A (en) * | 2022-10-27 | 2023-01-17 | 大亚车轮制造有限公司 | Double-stage aging heat treatment method for aluminum alloy wheel |
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| CN102041464A (en) * | 2009-10-09 | 2011-05-04 | 韦加伟 | Method for increasing mechanical properties of vehicle hub through artificial aging |
| CN106756301A (en) * | 2016-12-06 | 2017-05-31 | 江苏凯特汽车部件有限公司 | A kind of semi-solid-state shaping full-sized car manufacture method of tough aluminium alloy wheel hub high |
| CN107116345A (en) * | 2017-07-04 | 2017-09-01 | 蚌埠市福沃特车轮制造科技有限公司 | Rub resistance aluminium alloy wheel hub spinning process |
| CN108823446A (en) * | 2018-07-16 | 2018-11-16 | 山东华宇合金材料有限公司 | A kind of process improving A356.2 Mechanical Properties of Aluminum Alloys |
| CN109554560A (en) * | 2018-12-05 | 2019-04-02 | 辽宁忠旺集团有限公司 | A kind of production method of aerospace 7 line aluminium alloy profile of superhigh intensity |
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| CN107586939A (en) * | 2017-09-13 | 2018-01-16 | 中信戴卡股份有限公司 | A kind of heat treatment method for aluminium alloy casting rotation wheel |
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Patent Citations (5)
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| CN102041464A (en) * | 2009-10-09 | 2011-05-04 | 韦加伟 | Method for increasing mechanical properties of vehicle hub through artificial aging |
| CN106756301A (en) * | 2016-12-06 | 2017-05-31 | 江苏凯特汽车部件有限公司 | A kind of semi-solid-state shaping full-sized car manufacture method of tough aluminium alloy wheel hub high |
| CN107116345A (en) * | 2017-07-04 | 2017-09-01 | 蚌埠市福沃特车轮制造科技有限公司 | Rub resistance aluminium alloy wheel hub spinning process |
| CN108823446A (en) * | 2018-07-16 | 2018-11-16 | 山东华宇合金材料有限公司 | A kind of process improving A356.2 Mechanical Properties of Aluminum Alloys |
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