Aluminum alloy valve body for automobile and preparation method of aluminum alloy valve body

Abstract

The invention relates to the field of aluminum alloy material processing, in particular to an aluminum alloy valve body for an automobile and a preparation method of the aluminum alloy valve body for the automobile, and the valve body comprises the following components in percentage by weight: 0.65-0.77% of Si; the content of Fe is 0.32 to 0.37 percent; the content of Cu is 0.28 to 0.33 percent; the content of Mn is 0.08 to 0.13 percent; the content of Mg is 0.9 to 0.95 percent; the content of Cr is 0.18 to 0.23 percent; the Zn content is less than or equal to 0.1%; ti content is less than or equal to 0.1%; the single content of other impurity elements is less than or equal to 0.05%; the total content of other impurity elements is less than or equal to 0.15%; the preparation method comprises the steps of casting, homogenization treatment, extrusion, quenching and aging treatment. The quenching conditions include that a plate with the size of a quenched profile being 150 mm * 30 mm is subjected to full water quenching through a water tank, the cooling rate is 180-200 DEG C / s, the quenching temperature is 510-530 DEG C, the distance between the upper surface of the profile and the water surface is larger than 300 mm, the time when the profile is located in the water tank is larger than or equal to 3 s, the hardness of the valve body can reach 110-120 HB under the high-temperature and high-pressure extrusion technology, and the valve body is not prone to deformation. And the application requirement of the aluminum alloy valve body for the vehicle is met.

Description

Technical Field

[0001] The present invention relates to the field of aluminum alloy material processing, and in particular to an aluminum alloy valve body for automobiles and a preparation method thereof. Background Art

[0002] After extrusion quenching and artificial aging, aluminum alloy valve bodies used in automotive parts often have defects such as tool sticking and poor turning performance during machining and turning holes. At present, products produced by extrusion using the existing aluminum alloy ingot composition often have uneven hardness distribution on the end face of the extruded profile and low overall hardness. Without optimizing the existing aluminum alloy composition, multiple tests and adjustments have been carried out by increasing the supersaturated solid solubility of the aluminum alloy and shortening the aging parking time. However, the Brinell hardness of the end face of the product cannot meet the 9-point hardness range of 110-120HB. This is often due to the composition of the material and quenching. Due to the limitation of sensitivity, if higher temperature and extrusion rod speed are used for extrusion production, although the mechanical properties and end face hardness of the product are improved, the surface of the product often has transverse micro cracks perpendicular to the extrusion direction, and the low-magnification structure is accompanied by a deep and thick coarse grain structure. At the same time, the hardness of the low-magnification end face of the product is between 100-104HB. After machining in the later stage, defects such as material being too soft, sticking to the knife and aluminum will also appear. Once the product is too soft, the processing parameters need to be re-debugged, which will greatly reduce the production capacity of the equipment, and in severe cases, cause wear and damage to the processing tool.

[0003] In summary, there is an urgent need for an aluminum alloy automobile valve body having a hardness greater than or equal to 110HB under high-temperature and high-speed extrusion conditions and a preparation method thereof. Summary of the Invention

[0004] The present invention aims to solve the technical problem of how to provide an aluminum alloy automobile valve body having a hardness greater than or equal to 110HB under high-temperature and high-speed extrusion conditions and a preparation method thereof.

[0005] In order to achieve the above-mentioned object, the first aspect of the present invention provides an aluminum alloy valve body for automobiles, wherein the components and their weight percentages in the valve body are as follows:

[0006] Si content is 0.65-0.77%;

[0007] Fe content is 0.32-0.37%;

[0008] Cu content is 0.28-0.33%;

[0009] Mn content is 0.08-0.13%;

[0010] Mg content is 0.9-0.95%;

[0011] Cr content is 0.18-0.23%;

[0012] Zn content ≤ 0.1%;

[0013] Ti content ≤ 0.1%;

[0014] The content of other impurity elements is ≤0.05%;

[0015] The total content of other impurity elements is ≤0.15%;

[0016] The balance is Al.

[0017] A second aspect of the present invention provides a method for preparing the above-mentioned automotive aluminum alloy valve body, wherein the method comprises:

[0018] Casting, homogenization, extrusion, quenching, aging treatment;

[0019] The quenching conditions include: the size of the quenched profile is 150mm×30mm, the profile is rapidly cooled in a water tank full of water, the cooling rate is 180-200℃ / s, the quenching temperature is 510-530℃, the distance between the upper surface of the profile and the water surface is greater than 300mm, and the profile is in the water tank for greater than or equal to 3s;

[0020] The cooling rate is the cooling rate of the entire quenching valve body.

[0021] The beneficial effects of the present invention are:

[0022] By introducing Mn and Cr to refine the aluminum alloy grains and controlling the alloy composition and a specific quenching process, the aluminum alloy valve body provided by the present invention meets the requirement of a hardness greater than or equal to 110HB under high-temperature and high-speed extrusion conditions, and adopts a specific quenching process to improve the online quenching and solid solution effect. Furthermore, the specific extrusion and aging treatment processes make the performance of the aluminum alloy valve body more excellent. The heat treatment method of high temperature, long-term rapid cooling effectively improves the overall extrudability of the aluminum alloy ingot, while increasing the temperature of the product before quenching and reducing the natural parking time of the product, ultimately achieving an aluminum alloy valve body product with fine grains, a coarse grain layer thickness of less than 1 mm, and good overall uniformity of end face hardness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the grain size picture of Example 1;

[0024] Figure 2 This is a picture of the coarse-grained layer of Example 1. DETAILED DESCRIPTION

[0025] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0026] The high-temperature and high-speed extrusion conditions referred to in the present invention are extrusion conditions of 480-500° C. and 2-3 m / min.

[0027] In the existing technology, due to the relatively low content of Mn and Cr, the grain-refining elements in the existing alloy composition, the product's lattice is severely distorted during the high-temperature extrusion process, resulting in defects such as dynamic growth and swallowing, that is, abnormal grain coarsening. However, in order to meet higher strength and hardness requirements, the product must be extruded under high temperature and high speed conditions. The product's structure will undergo dynamic recrystallization. The content of fine grain elements directly affects the recrystallization temperature of the material, making it difficult for the aluminum alloy valve body to meet the required hardness.

[0028] To achieve this goal, the inventors attempted to optimize the composition and processing technology of the aluminum alloy valve body. The inventors found that the above purpose can be achieved through specific component composition and quenching process. Furthermore, specific extrusion and aging treatment processes make the performance of aluminum alloy even better.

[0029] A first aspect of the present invention provides an aluminum alloy valve body for automobiles, wherein the components and their weight percentages in the valve body are as follows:

[0030] Si content is 0.65-0.77%;

[0031] Fe content is 0.32-0.37%;

[0032] Cu content is 0.28-0.33%;

[0033] Mn content is 0.08-0.13%;

[0034] Mg content is 0.9-0.95%;

[0035] Cr content is 0.18-0.23%;

[0036] Zn content ≤ 0.1%;

[0037] Ti content ≤ 0.1%;

[0038] The content of other impurity elements is ≤0.05%;

[0039] The total content of other impurity elements is ≤0.15%;

[0040] The balance is Al.

[0041] In the present invention, the content of grain-refining elements such as Mn and Cr is controlled by utilizing the alloy composition ratio of grain-refining elements to keep it within the upper limit range, which can increase the dynamic recrystallization temperature of the material and thus improve the low-magnification coarse-grained density of the aluminum alloy valve body.

[0042] According to the present invention, the thickness of the coarse-grained layer of the valve body is less than 1 mm.

[0043] According to the present invention, the valve body has a grain size of 7 levels.

[0044] According to the present invention, the hardness of the valve body is 110-120 HB.

[0045] A second aspect of the present invention provides a method for preparing the above-mentioned automotive aluminum alloy valve body, wherein the method comprises:

[0046] Casting, homogenization, extrusion, quenching, aging treatment;

[0047] The quenching conditions include: the size of the quenched profile is 150mm×30mm, the profile is rapidly cooled in a water tank full of water, the cooling rate is 180-200℃ / s, the quenching temperature is 510-530℃, the distance between the upper surface of the profile and the water surface is greater than 300mm, and the profile is in the water tank for greater than or equal to 3s;

[0048] The cooling rate is the cooling rate of the entire quenching valve body.

[0049] In the present invention, the quenching temperature of the valve body material is increased, and a specific quenching temperature is limited. The specific rapid cooling rate is beneficial to the fine structure of the product and the formation of a supersaturated solid solution, and the supersaturated concentration before aging is increased, which is beneficial to subsequent artificial aging. The distance between the upper surface of the profile and the water surface is greater than 300 mm, and the profile needs to be processed in the cooling water tank for a time greater than or equal to the above limit. This can reduce the natural aging of the aluminum alloy after quenching, resulting in the precipitation of the supersaturated solid solution, thereby reducing the effect of artificial aging. The processing is carried out within the aging time specified by the present invention, so that the processed valve body has better processing performance.

[0050] If traditional spray cooling or water mist cooling is used, the quenching strength of the core structure of the product is too low, resulting in high hardness at the edges and uneven hardness of the core structure when the product is subsequently subjected to Brinell hardness testing, which in turn causes tool damage during machining. The quenching cooling method used in the present invention can ensure a consistent cooling rate for the entire profile, ensuring that the hardness remains within a specific range.

[0051] According to the present invention, the conditions for the homogenization treatment include: the annealing temperature of the ingot is 560-580° C., and the annealing time is 8-10 hours.

[0052] In the present invention, during the casting process, the high-alloy element aluminum alloy will cause the alloy elements to be unevenly distributed in the ingot due to reasons such as uneven cooling rate. During high-temperature homogenization treatment, the atoms have higher energy and can overcome the diffusion activation energy to diffuse over long distances, so that the alloy elements are evenly distributed throughout the alloy, reducing component segregation. At high temperatures, the solute atoms between the dendrites diffuse toward the dendrite trunk, gradually homogenizing the dendrite structure to form an equiaxed crystal structure. During the high-temperature homogenization process, the second phase particles are partially dissolved in the matrix, and the undissolved particles will also become smaller and more dispersed, and evenly distributed in the matrix, thereby improving the strength and hardness of the alloy. Residual stress will be generated inside the aluminum alloy during the casting process. When homogenized at the specific temperature specified in the present invention, the alloy is in a thermoplastic state, and the internal stress is relaxed and eliminated, which helps to reduce deformation and cracking tendencies in subsequent processing and improve product quality.

[0053] In the present invention, the specific ingot soaking temperature and soaking time can eliminate the segregation of the structure and composition of the product during the crystallization process.

[0054] According to the present invention, the extrusion conditions include: ingot heating is divided into two stages, the first stage heating temperature is 300-450℃, the first stage heating time is 3-5min, the second stage heating temperature is 480-500℃, the second stage heating time is 1-2min.

[0055] In the present invention, the first heating stage is the ingot preheating stage, and the second heating stage is the ingot heating stage, which avoids structural defects such as overburning and surface cracks in the profile due to excessive rod temperature heating.

[0056] According to the present invention, the extrusion conditions include: an extrusion speed of 2-3 m / min.

[0057] In the present invention, increasing the extrusion speed can effectively increase the overall hardness of the end face of the valve body.

[0058] According to the present invention, the extrusion conditions include: the extrusion upset deformation is 180-200 mm.

[0059] In the present invention, the aluminum alloy has good plasticity at the extrusion temperature. When subjected to external force, the grains inside it slip and rotate, and the grain boundaries also migrate and adjust. In the roughening area, this plastic deformation is more intense, the grains are elongated and twisted, and then rearranged, making the structure of the aluminum alloy denser, thereby improving the strength and toughness of the material. During the roughening process, the plastic deformation increases the dislocation density inside the aluminum alloy, and the dislocations intersect and entangle with each other, hindering the further movement of the dislocations, resulting in increased strength and hardness of the material. Under the high temperature and high strain rate conditions of extrusion roughening, the aluminum alloy will also undergo dynamic recrystallization. Within the extrusion roughening deformation range defined by the present invention, the energy stored inside the aluminum alloy is sufficient to drive the nucleation and growth of new grains. These new grains have a fine and uniform structure, which can eliminate work hardening, so that the material can restore a certain degree of plasticity and toughness while maintaining a high strength, further improving the comprehensive performance of the aluminum alloy.

[0060] According to the present invention, the aging treatment conditions include: aging treatment within 6 hours after quenching, an initial temperature of 15°C, a heating rate of 40°C / h, heating to 175°C, and a holding time of 8-10 hours.

[0061] In the present invention, during the aluminum alloy extrusion process, the specific homogenization heat treatment, quenching heat treatment and aging heat treatment of the present invention work together to significantly improve the performance of the aluminum alloy.

[0062] Homogeneous heat treatment is the basis. Through high temperature and long time heating, the alloy elements are fully diffused, the component segregation is reduced, the consistency of the organizational transformation during subsequent heat treatment is ensured, the second phase particles are fully dissolved and evenly distributed, the grains are refined, and a good organizational foundation is provided for subsequent processing and heat treatment, thereby improving the plasticity and processing properties of the material.

[0063] Quenching heat treatment is the key. The aluminum alloy is heated to above the critical temperature so that the alloying elements are fully dissolved into the matrix to form a uniform solid solution. It is then rapidly cooled to inhibit the precipitation of second-phase particles and obtain a supersaturated solid solution to prepare for aging strengthening. There are a large amount of lattice distortion and internal stress in the supersaturated solid solution, which increases the resistance to dislocation movement, thereby improving the strength and hardness of the aluminum alloy.

[0064] Aging heat treatment is a strengthening method. During aging treatment, the alloying elements in the supersaturated solid solution will precipitate in the form of fine dispersed second-phase particles. These particles will hinder dislocation movement. During the aging process, the structure of the alloy gradually stabilizes, reducing the performance degradation caused by structural changes during use and improving the strength and hardness of the aluminum alloy.

[0065] In the present invention, the aging system provided ensures that the temperature of each point of the profile is consistent, and effectively controls the hardness of the profile to be maintained within the range of 110-120HB.

[0066] In the present invention, by optimizing the content of Mn and Cr in the alloy and the alloy composition, and combining with a non-standard extrusion machine, a smaller extrusion barrel diameter is used to adjust the extrusion roughening deformation of the profile, and at the same time, by improving the ingot homogenization annealing system and increasing the ingot annealing temperature, the homogenization precipitation process of the supersaturated elements in the alloy is accelerated, and rapid cooling is adopted during cooling to prevent the aggregation, precipitation and coarsening of the strength in the aluminum alloy.

[0067] The properties in the present invention are measured according to conventional methods.

[0068] The technical solution of the present invention is further described in detail below with reference to the accompanying drawings and embodiments. Obviously, the embodiments described herein are only some embodiments of the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments implemented by those of ordinary skill in the art without making creative improvements are within the scope of protection of the present invention.

[0069] Example 1

[0070] A. Melting and Casting: Prepare 7 series aluminum alloy raw materials according to the following weight ratios: Si: 0.66%, Fe: 0.35%, Cu 0.3%, Mn: 0.1%, Mg: 0.93%, Cr: 0.19%, Zn: ≤ 0.05%, Ti: ≤ 0.1%, other impurity elements individually ≤ 0.05%, other impurity elements total ≤ 0.15%, balance Al, and melt the prepared aluminum alloy raw materials at a melting temperature of 740°C for 5 hours;

[0071] B. Homogenization treatment: heating the aluminum alloy cast rod obtained by melting and casting to 580°C, keeping the temperature for 10 hours, and cooling to 50°C to obtain a homogenized aluminum alloy cast rod;

[0072] C. Extrusion: The homogenized aluminum alloy casting rod is fed into the extrusion barrel of the extruder for extrusion. The ingot has a uniform annealing temperature of 580°C and a uniform annealing time of 10 hours. The ingot heating is divided into two stages: the first stage is heated at 400°C and the first stage is heated for 3 minutes; the second stage is heated at 500°C and the second stage is heated for 2 minutes. The extrusion speed is 3 m / min and the extrusion deformation is 200 mm.

[0073] D. Offline quenching: The size of the quenched profile is 150mm×30mm plate, and the water tank is filled with water for rapid cooling. The cooling rate is 200℃ / s, the quenching temperature is 530℃, the distance between the upper surface of the profile and the water surface is greater than 300mm, and the profile is in the water tank for more than or equal to 3s;

[0074] F. Aging: Aging treatment should be carried out within 6 hours after quenching. The initial temperature is 15℃, the heating rate is 40℃ / h, heating to 175℃, and the holding time is 9 hours.

[0075] An aluminum alloy valve body A1 was produced.

[0076] Example 2

[0077] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that the components of the aluminum alloy were Si: 0.65%, Fe: 0.32%, Cu: 0.28%, Mn: 0.08%, Mg: 0.9%, and Cr: 0.18%.

[0078] An aluminum alloy valve body A2 is produced.

[0079] Example 3

[0080] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that the components of the aluminum alloy were Si: 0.77%, Fe: 0.37%, Cu: 0.33%, Mn: 0.13%, Mg: 0.95%, and Cr: 0.23%.

[0081] An aluminum alloy valve body A3 is produced.

[0082] Example 4

[0083] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that in the homogenization treatment, the annealing temperature of the ingot was 560°C, the annealing time was 8 hours, in the quenching process, the cooling rate was 180°C / s, the quenching temperature was 510°C, and in the aging process, the holding time was 8 hours.

[0084] An aluminum alloy valve body A4 is produced.

[0085] Example 5

[0086] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the homogenization treatment, the annealing temperature of the ingot was 580°C, the annealing time was 10 h, in the quenching process, the cooling rate was 200°C / s, the quenching temperature was 530°C, and in the aging process, the holding time was 10 h.

[0087] An aluminum alloy valve body A5 was produced.

[0088] Example 6

[0089] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the extrusion speed was 2 m / min.

[0090] An aluminum alloy valve body A6 was produced.

[0091] Example 7

[0092] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the extrusion speed was 3 m / min.

[0093] An aluminum alloy valve body A7 was produced.

[0094] Example 8

[0095] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the extrusion upsetting deformation amount was 200 mm.

[0096] An aluminum alloy valve body A8 is produced.

[0097] Example 9

[0098] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the extrusion upsetting deformation amount was 220 mm.

[0099] An aluminum alloy valve body A9 was produced.

[0100] Example 10

[0101] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the first stage heating temperature was 300°C, the first stage heating time was 3 minutes, and the second stage heating temperature was 480°C, the second stage heating time was 1 minute.

[0102] An aluminum alloy valve body A10 was produced.

[0103] Example 11

[0104] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the first heating temperature was 450°C, the first heating time was 5 minutes, the first heating temperature was 500°C, and the first heating time was 3 minutes.

[0105] An aluminum alloy valve body A11 was produced.

[0106] Comparative Example 1

[0107] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that the aluminum alloy components were Si: 0.63%, Fe: 0.30%, Cu: 0.27%, Mn: 0.06%, Mg: 0.8%, and Cr: 0.15%.

[0108] An aluminum alloy valve body DA1 was produced.

[0109] Comparative Example 2

[0110] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that the components of the aluminum alloy were Si: 0.79%, Fe: 0.39%, Cu: 0.35%, Mn: 0.15%, Mg: 0.97%, and Cr: 0.25%.

[0111] An aluminum alloy valve body DA2 was produced.

[0112] Comparative Example 3

[0113] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that in the homogenization treatment, the annealing temperature of the ingot was 555°C, the annealing time was 7.5h, in the quenching process, the cooling rate was 175°C / s, the quenching temperature was 505°C, and in the aging process, the holding time was 7.5h.

[0114] An aluminum alloy valve body DA3 was produced.

[0115] Comparative Example 4

[0116] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that in the homogenization treatment, the annealing temperature of the ingot was 585°C, the annealing time was 10.5 h, in the quenching process, the cooling rate was 205°C / s, the quenching temperature was 535°C, and in the aging process, the holding time was 10.5 h.

[0117] An aluminum alloy valve body DA4 was produced.

[0118] Comparative Example 5

[0119] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the first stage heating temperature was 295°C, the first stage heating time was 2.5 min, and the second stage heating temperature was 475°C, the second stage heating time was 0.5 min.

[0120] An aluminum alloy valve body DA5 was produced.

[0121] Comparative Example 6

[0122] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the first stage heating temperature was 455°C, the first stage heating time was 5.5 minutes, and the second stage heating temperature was 505°C, the second stage heating time was 2.5 minutes.

[0123] Aluminum alloy valve body DA6 was produced.

[0124] Comparative Example 7

[0125] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the extrusion speed was 1.5 m / min.

[0126] An aluminum alloy valve body DA7 was produced.

[0127] Comparative Example 8

[0128] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the extrusion speed was 3.5 m / min.

[0129] An aluminum alloy valve body DA8 was produced.

[0130] Comparative Example 9

[0131] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the extrusion upsetting deformation amount was 195 mm.

[0132] Aluminum alloy valve body DA9 was produced.

[0133] Comparative Example 10

[0134] An aluminum alloy valve body was prepared according to the processing method of Example 1, except that, in the extrusion process, the extrusion upsetting deformation amount was 225 mm.

[0135] An aluminum alloy valve body DA10 was produced.

[0136] Performance tests were conducted on A1-A11 and DA1-DA10. As shown in Table 1, the coarse grain layer thickness of the valve bodies A1-A11 prepared in the embodiment is less than 1 mm, and the grain size reaches level 7. The coarse grain layer thickness of the valve bodies DA1-DA10 prepared in the comparative example is greater than 1 mm, and the grain size is level 5-6.

[0137] Table 1

[0138]

[0139]

[0140] By comparing the examples with the comparative examples, it can be seen that the aluminum alloy valve body provided by the present invention has excellent hardness, strength and plasticity.

[0141] The aluminum alloy valve body provided by the present invention improves the hardness of the valve body by introducing Mn and Cr elements that refine the grains and regulating their content. Furthermore, the quenching process is regulated to solve the problem caused by the composition change after the introduction of Mn and Cr elements, and at the same time solves the problem of the material recrystallization temperature change caused by the high-temperature and high-speed extrusion process required to improve the hardness. Furthermore, by regulating the extrusion and aging processes, the hardness of the valve body can be made even better.

[0142] The above description is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, can make equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An aluminum alloy valve body for automobiles, characterized in that: The components and their weight percentages in the valve body are: Si content is 0.65-0.77%; Fe content is 0.32-0.37%; Cu content is 0.28-0.33%; Mn content is 0.08-0.13%; Mg content is 0.9-0.95%; Cr content is 0.18-0.23%; Zn content ≤ 0.1%; Ti content ≤ 0.1%; The content of other impurity elements is ≤0.05%; The total content of other impurity elements is ≤0.15%; The balance is Al.

2. The valve body according to claim 1, characterized in that The thickness of the coarse-grained layer of the valve body is less than 1 mm.

3. The valve body according to claim 1, characterized in that The valve body has a grain size of 7 levels.

4. The valve body according to claim 1, wherein: The hardness of the valve body is 110-120HB.

5. A method for preparing an automotive aluminum alloy valve body according to any one of claims 1 to 4, characterized in that: The method comprises: Casting, homogenization, extrusion, quenching, aging treatment; The quenching conditions include: the size of the quenched profile is 150mm×30mm, the profile is rapidly cooled in a water tank full of water, the cooling rate is 180-200℃ / s, the quenching temperature is 510-530℃, the distance between the upper surface of the profile and the water surface is greater than 300mm, and the profile is in the water tank for greater than or equal to 3s; The cooling rate is the cooling rate of the entire quenching valve body.

6. The method according to claim 5, characterized in that The homogenization treatment conditions include: the ingot annealing temperature is 560-580° C., and the annealing time is 8-10 hours.

7. The method according to claim 5, characterized in that The extrusion conditions include: ingot heating is divided into two stages, the first stage heating temperature is 300-450°C, the first stage heating time is 3-5 minutes, the second stage heating temperature is 480-500°C, the second stage heating time is 1-2 minutes.

8. The method according to claim 5, characterized in that The extrusion conditions include: an extrusion speed of 2-3 m / min.

9. The method according to claim 5, characterized in that The extrusion conditions include: the extrusion pier deformation is 200-220mm.

10. The method according to claim 5, characterized in that The aging treatment conditions include: aging treatment within 6 hours after quenching, an initial temperature of 15° C., a heating rate of 40° C. / h, heating to 175° C., and a holding time of 8-10 hours.

Images