High-performance automobile dragging nut profile and preparation method thereof

Abstract

The invention relates to the field of aluminum alloy material processing, in particular to a high-performance automobile towing nut profile and a preparation method thereof, and the profile comprises the following components in percentage by weight: 1.04-1.09% of Si; the content of Fe is smaller than or equal to 0.15%; the content of Cu is 0.45 to 0.50 percent; the content of Mn is 0.77 to 0.82 percent; the content of Mg is 0.85 to 0.90 percent; the content of Cr is 0.15 to 0.20 percent; the content of Zn is 0 to 0.15 percent; the content of Ti is 0.05 to 0.15 percent; 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 balance is Al; according to the aluminum alloy profile, the content of Mg2Si is 1.33-1.42%, and the content of excess Si is 0.52-0.6%, under the condition that the forming difficulty of the profile is large, the size precision of the profile can still be guaranteed, the part performance is greatly improved, the yield strength of the profile can reach 370 Mpa, the tensile strength can reach 400 Mpa, the requirement for the higher standard of automobile dragging nut parts is met, and the overall quality of an automobile is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy processing, and in particular to a high-performance automobile towing nut profile and a preparation method thereof. Background Art

[0002] With the development of my country's new energy vehicle manufacturing industry, in pursuit of the goal of lightweight vehicles and higher endurance, automakers in the industry are continuing to optimize and seek more aluminum alloy alternatives for body parts, replacing more high-performance parts with aluminum alloys instead of steel, such as automobile towing nuts.

[0003] The existing automotive drag nuts in the industry are mostly made of high-strength alloy steel, stainless steel and other materials. In order to seek an alternative to aluminum alloy, 6110A aluminum alloy with high alloying and high strength is now used for production.

[0004] The high-alloyed aluminum alloy materials in the existing technology have disadvantages such as high quenching sensitivity, poor formability, and rough surface during continuous production. They are now required to meet high performance requirements and be able to be stably mass-produced. The 6110A alloy drag nut, with an external circle diameter of 86mm and a rod with two thin-walled free ends, is difficult to form and has poor surface quality. The free ends and surface are extremely prone to cracking, which seriously reduces the yield rate and increases production costs. At the same time, the performance strength is difficult to meet the requirements.

[0005] Therefore, there is an urgent need to provide an automobile towing nut profile with high surface quality and high performance strength and a preparation method thereof. Summary of the Invention

[0006] The present invention aims to solve the technical problem of how to provide an automobile towing nut profile with high surface quality and high performance strength.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a high-performance automobile towing nut profile, wherein the components and their weight percentages in the profile are as follows:

[0008] Si content is 1.04-1.09%;

[0009] Fe content ≤ 0.15%;

[0010] Cu content is 0.45-0.50%;

[0011] Mn content is 0.77-0.82%;

[0012] Mg content is 0.85-0.90%;

[0013] Cr content is 0.15-0.20%;

[0014] Zn content is 0-0.15%;

[0015] Ti content is 0.05-0.15%;

[0016] The content of other impurity elements is ≤0.05%;

[0017] The total content of other impurity elements is ≤0.15%;

[0018] The remainder is Al;

[0019] Among them, the Mg2Si content is 1.33-1.42%, and the excess Si content is 0.52-0.6%.

[0020] A second aspect of the present invention provides a method for preparing the high-performance automotive towing nut profile, wherein the method comprises:

[0021] Casting, homogenization, extrusion, aging treatment;

[0022] The conditions for the casting include: the hydrogen content during the casting process does not exceed 0.1 cm 3 / 100g, the amount of waste added shall not exceed 25%, only the scrap aluminum with the surface as the base material shall be added, and the cast grain size shall be ≤50μm;

[0023] The homogenization treatment conditions include: homogenization treatment at 545-555° C. for 9-10 hours, and cooling to room temperature at a cooling rate of 20-40° C. / min.

[0024] The beneficial effects of the present invention are:

[0025] The profile provided by the present invention optimizes the chemical composition ratio, and after controlling the mold structure, smelting and casting, and extrusion processes, the use of 6110A alloy can still ensure the profile dimensional accuracy and greatly improve the part performance even when the profile forming is difficult. The yield strength of the profile can reach 370 MPa and the tensile strength can reach 400 MPa, meeting the higher standards required for automotive towing nut parts and further improving the overall quality of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-section diagram of the profile. DETAILED DESCRIPTION

[0027] 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.

[0028] In the existing technology, the extrusion molding of profiles with a large difference in thickness between thick and thin walls is extremely difficult, and the performance requirements are very high. During the extrusion process, it is very easy to cause tears or small cracks on the free ends and the surface of the profile, and the performance cannot meet the requirements. The conventional solution for aluminum alloy extrusion is to reduce the degree of alloying in order to improve formability, which will inevitably reduce the final performance of the material, making it difficult to achieve both goals.

[0029] In the present invention, the inventors found that by controlling the alloy composition and adjusting the processing technology, the performance of the aluminum alloy profile can meet the requirements, without a coarse-grained layer, and having excellent mechanical properties.

[0030] To achieve this goal, the inventors attempted to optimize the composition and processing technology of the components of aluminum alloy profiles. The inventors found that the above objectives can be achieved through specific component compositions and melting, casting and homogenization processes. Furthermore, specific extrusion and heat treatment processes make the performance of aluminum alloy profiles even better.

[0031] A first aspect of the present invention provides a high-performance automotive towing nut profile, wherein the components and their weight percentages in the profile are:

[0032] Si content is 1.04-1.09%;

[0033] Fe content ≤ 0.15%;

[0034] Cu content is 0.45-0.50%;

[0035] Mn content is 0.77-0.82%;

[0036] Mg content is 0.85-0.90%;

[0037] Cr content is 0.15-0.20%;

[0038] Zn content is 0-0.15%;

[0039] Ti content is 0.05-0.15%;

[0040] The content of other impurity elements is ≤0.05%;

[0041] The total content of other impurity elements is ≤0.15%;

[0042] The remainder is Al;

[0043] Among them, the Mg2Si content is 1.33-1.42%, and the excess Si content is 0.52-0.6%.

[0044] In the present invention, the contents of Mg2Si and excess Si are controlled, and while the content of the strengthening phase is increased as much as possible, the excess Si content is strictly controlled to avoid the formation of hard and brittle phases by free Si, which increases the risk of extrusion cracks. The Cu content is controlled to maximize the solid solution strengthening and aging effects, while avoiding exceeding 0.50% which may reduce the extrusion fluidity. The Cr content is controlled to refine the grains, inhibit recrystallization, and reduce uneven deformation during the extrusion process. The Ti content is controlled to refine the grains, reduce the cast grain size, and reduce the tendency of extrusion cracking.

[0045] Fe is a common impurity element in aluminum alloys and needs to be controlled below 0.15% to avoid the formation of coarse phases. Excessive iron-rich phases in the aluminum alloy matrix will reduce the plasticity of the material. Elements such as silicon, copper, and magnesium can improve the strength of the material, but when excessive, they will reduce the formability of the material. For example, excessive silicon will increase the brittleness of the material, and excessive copper will increase the quenching sensitivity of the material, which will easily produce large thermal stress and structural stress during quenching, causing deformation or even cracking of parts; excessive magnesium will reduce the fluidity of the metal, which is not conducive to the surface quality and forming of the product. The above-mentioned composition control can not only improve the strength of the material within the industry composition standard range, but also maximize its surface quality and extrudability while ensuring performance, and achieve a good balance between high performance and good formability.

[0046] A second aspect of the present invention provides a method for preparing the high-performance automotive towing nut profile, wherein the method comprises:

[0047] Casting, homogenization, extrusion, aging treatment;

[0048] The conditions for the casting include: the hydrogen content during the casting process does not exceed 0.1 cm 3 / 100g, the amount of waste added shall not exceed 25%, only the scrap aluminum with the surface as the base material shall be added, and the cast grain size shall be ≤50μm;

[0049] The homogenization treatment conditions include: homogenization treatment at 545-555° C. for 9-10 hours, and cooling to room temperature at a cooling rate of 20-40° C. / min.

[0050] In the present invention, the above-mentioned limitation on waste materials avoids the occurrence of needle-shaped pores in the profile due to hydrogen precipitation during ingot solidification, thereby inducing cracks during the extrusion process.

[0051] In the present invention, high temperature annealing allows the strengthening phase to be fully integrated into the matrix and dispersed, preventing segregation of the ingot and improving the performance and extrudability of the cast rod. At the same time, slow cooling is conducive to the uniform distribution of the precipitated phase, which can play a role in strengthening the alloy.

[0052] In the present invention, the addition of aluminum titanium boron wire and electromagnetic stirring are combined with refinement treatment to control the cast grain size to ≤50 μm, thereby improving the uniformity of the entire interface of the ingot and thereby improving the performance and extrusion formability of the extruded product.

[0053] According to the present invention, the extrusion conditions include: the distance from the mold guide plate to the mold hole at the thin-wall position is 2.7-3 times the distance from the mold guide plate to the mold hole at the thick-wall position, and the width of the mold front chamber at the thin-wall position is 14-16 times the width of the mold front chamber at the thick-wall position.

[0054] In the present invention, the mold structure is optimized at the thin-wall free end position where molding is most difficult and prone to insufficient aluminum supply and cracking, so that the flow rate of the aluminum alloy material at this position is more sufficient and stable.

[0055] According to the present invention, the extrusion conditions include: the time for a single point of metal to pass through the working belt is ≤ 0.2s.

[0056] In the present invention, the contact time between the metal flow and the die working is reduced, the friction between the high-temperature metal flow and the working belt is reduced, and serious surface particle tearing is avoided.

[0057] According to the present invention, the extrusion conditions include: mold temperature of 460-500°C, extrusion ingot temperature of 490-520°C, extrusion barrel temperature of 440-460°C, and extrusion speed of 1-1.5m / min.

[0058] In the present invention, cracks are likely to appear on the lower surface and free end during high-speed extrusion. Therefore, on the one hand, the overall extrusion temperature is increased to enhance the metal fluidity, and on the other hand, the extrusion speed is reduced to ensure that the product size is qualified and free of cracks, thereby reducing the scrap rate. Water tank quenching is used to ensure that the product cools without scalding the material table and causing surface damage.

[0059] According to the present invention, the aging treatment system is 552-558 ° C offline quenching, heat preservation for 3.5-4.5 hours, and peak aging at 172-178 ° C, 7.5-8.5 hours.

[0060] In the present invention, the above aging system ensures that the strengthening phase can be completely dissolved in the matrix, and then the performance requirements are achieved through peak aging.

[0061] The profiles were tested according to conventional testing methods in the art.

[0062] 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.

[0063] Example 1

[0064] The chemical composition of the alloy is Si: 1.05%, Fe: 0.10%, Cu: 0.46%, Mn: 0.80%, Mg: 0.86%, Cr: 0.19%, Zn: 0.02%, Ti: 0.15%, Mg2Si content is 1.36%, excess Si content is 0.55%, the individual content of other impurity elements is ≤0.05%; the total content of other impurity elements is ≤0.15%; the balance is Al.

[0065] The total amount of scrap aluminum added is 18% of the total casting mass, and the hydrogen content is less than 0.1cm 3 / 100g, the cast grain size is 48μm. The homogenization process is annealed at 560℃ for 8h and then slowly cooled at a rate of 25℃ / min.

[0066] The distance from the mold guide plate to the mold hole in the thin-wall position is 2.9 times the distance from the mold guide plate to the mold hole in the thick-wall position. The width of the mold front chamber in the thin-wall position is 15.5 times the width of the mold front chamber in the thick-wall position. The time for a single point of metal to pass through the working belt is ≤0.2s. The mold temperature is 472°C, the extrusion ingot temperature is 517°C, the extrusion barrel temperature is 446°C, and the extrusion speed is 1.5m / min.

[0067] Aging heat treatment: 550℃ for 4h, offline quenching, aging system is 175℃×8h.

[0068] Aluminum alloy profile A1 was obtained, and the thickness of the thick wall of the profile was 20 times that of the thin wall.

[0069] Example 2

[0070] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the aluminum alloy components were Si: 1.04%, Fe: 0.05%, Cu: 0.45%, Mn: 0.77%, Mg: 0.85%, Cr: 0.15%, Zn: 0%, Ti: 0.05%, the Mg2Si content was 1.33%, and the excess Si content was 0.52%.

[0071] Aluminum alloy profile A2 is obtained.

[0072] Example 3

[0073] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the aluminum alloy components were Si: 1.09%, Fe: 0.15%, Cu: 0.5%, Mn: 0.82%, Mg: 0.9%, Cr: 0.2%, Zn: 0.15%, Ti: 0.15%, the Mg2Si content was 1.42%, and the excess Si content was 0.6%.

[0074] Aluminum alloy profile A3 is obtained.

[0075] Example 4

[0076] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the amount of waste added was 0% and the cast grain size was 44 μm.

[0077] Aluminum alloy profile A4 is produced.

[0078] Example 5

[0079] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the amount of waste added was 25% and the cast grain size was 50 μm.

[0080] Aluminum alloy profile A5 was obtained.

[0081] Example 6

[0082] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the homogenization treatment was performed at 545° C. for 9 h and the profile was cooled to room temperature at a rate of 20° C. / min.

[0083] Aluminum alloy profile A6 was obtained.

[0084] Example 7

[0085] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the homogenization treatment was performed at 555° C. for 10 h and the profile was cooled to room temperature at a rate of 40° C. / min.

[0086] Aluminum alloy profile A7 was obtained.

[0087] Example 8

[0088] Aluminum alloy profiles were prepared according to the processing method of Example 1, except that the distance from the mold guide plate to the mold hole at the thin-wall position was 2.7 times the distance from the mold guide plate to the mold hole at the thick-wall position, the width of the mold front chamber at the thin-wall position was 14 times the width of the mold front chamber at the thick-wall position, the mold temperature was 460°C, the extrusion ingot temperature was 490°C, the extrusion barrel temperature was 440°C, and the extrusion speed was 1 m / min.

[0089] Aluminum alloy profile A8 was obtained.

[0090] Example 9

[0091] Aluminum alloy profiles were prepared according to the processing method of Example 1, except that the distance from the mold guide plate to the mold hole at the thin-wall position was 3 times the distance from the mold guide plate to the mold hole at the thick-wall position, the width of the mold front chamber at the thin-wall position was 16 times the width of the mold front chamber at the thick-wall position, the mold temperature was 500°C, the extrusion ingot temperature was 520°C, the extrusion barrel temperature was 460°C, and the extrusion speed was 1.5 m / min.

[0092] Aluminum alloy profile A9 was obtained.

[0093] Example 10

[0094] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the profile was kept at 552° C. for 3.5 h and then offline quenched, and the aging system was 172° C. for 7.5 h.

[0095] Aluminum alloy profile A10 was obtained.

[0096] Example 11

[0097] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the profile was subjected to offline quenching at 558°C for 4.5 hours and the aging system was 178°C for 8.5 hours.

[0098] Aluminum alloy profile A11 was produced.

[0099] Comparative Example 1

[0100] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the aluminum alloy components were Si: 1.00%, Fe: 0.05%, Cu: 0.40%, Mn: 0.70%, Mg: 0.80%, Cr: 0.10%, Zn: 0.05%, Ti: 0.02%, the Mg2Si content was 1.26%, and the excess Si content was 0.54%.

[0101] Aluminum alloy profile DA1 was produced.

[0102] Comparative Example 2

[0103] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the aluminum alloy components were Si: 1.15%, Fe: 0.20%, Cu: 0.55%, Mn: 0.85%, Mg: 0.95%, Cr: 0.23%, Zn: 0.18%, Ti: 0.17%, the Mg2Si content was 1.50%, and the excess Si content was 0.61%.

[0104] Aluminum alloy profile DA2 was produced.

[0105] Comparative Example 3

[0106] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the amount of waste added was 30% and the cast grain size was 55 μm.

[0107] Aluminum alloy profile DA3 was produced.

[0108] Comparative Example 4

[0109] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the homogenization treatment was performed at 540° C.×8 h and the cooling rate was 15° C. / h to room temperature.

[0110] Aluminum alloy profile DA4 was produced.

[0111] Comparative Example 5

[0112] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the homogenization treatment was performed at 570° C.×11 h and the cooling rate was 60° C. / h to room temperature.

[0113] Aluminum alloy profile DA5 was produced.

[0114] Comparative Example 6

[0115] Aluminum alloy profiles were prepared according to the processing method of Example 1, except that the distance from the guide plate to the die hole of the extrusion die at the thin-wall position was twice that at the thick-wall position, the width of the thin-wall front chamber was 10 times that at the thick-wall position, the die temperature was 440°C, the extrusion ingot temperature was 470°C, the extrusion barrel temperature was 420°C, and the extrusion speed was 0.6 m / min.

[0116] Aluminum alloy profile DA6 was produced.

[0117] Comparative Example 7

[0118] Aluminum alloy profiles were prepared according to the processing method of Example 1, except that the distance from the guide plate to the die hole of the extrusion die at the thin-wall position was 4 times that at the thick-wall position, the width of the thin-wall front chamber was 20 times that at the thick-wall position, the mold temperature was 510°C, the extrusion ingot temperature was 535°C, the extrusion barrel temperature was 470°C, and the extrusion speed was 2m / min.

[0119] Aluminum alloy profile DA7 was produced.

[0120] Comparative Example 8

[0121] Aluminum alloy profiles were prepared according to the processing method of Example 1, except that they were kept at 545°C for 3 hours and offline quenched, and the aging system was 165°C for 7 hours.

[0122] Aluminum alloy profile A8 was obtained.

[0123] Comparative Example 9

[0124] An aluminum alloy profile was prepared according to the processing method of Example 1, except that the profile was subjected to offline quenching at 562° C. for 5 h and the aging system was 185° C. for 9 h.

[0125] Aluminum alloy profile DA9 was produced.

[0126] Performance tests were conducted on A1-A11 and DA1-DA9, as shown in Table 1.

[0127] Table 1

[0128]

[0129]

[0130] By comparing the embodiments with the comparative examples, it can be seen that the profile designed by the present invention can ensure the profile dimensional accuracy and greatly improve the part performance by using 6110A alloy when the profile forming is difficult, so that the profile yield strength can reach 370 MPa and the tensile strength can reach 400 MPa, meeting the higher standard requirements of automobile towing nut parts and further improving the overall quality of the automobile.

[0131] 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. A high-performance automobile towing nut profile, characterized in that: The components and their weight percentages in the profile are: Si content is 1.04-1.09%; Fe content ≤ 0.15%; Cu content is 0.45-0.50%; Mn content is 0.77-0.82%; Mg content is 0.85-0.90%; Cr content is 0.15-0.20%; Zn content is 0-0.15%; Ti content is 0.05-0.15%; The content of other impurity elements is ≤0.05%; The total content of other impurity elements is ≤0.15%; The remainder is Al; Among them, the Mg2Si content is 1.33-1.42%, and the excess Si content is 0.52-0.6%.

2. The profile according to claim 1, characterized in that The profile comprises a thick wall and thin walls located on both sides of the thick wall, and the thickness of the thick wall is 17-20 times that of the thin wall.

3. A method for preparing the high-performance automobile towing nut profile according to claim 1 or 2, characterized in that: The method comprises: Casting, homogenization, extrusion, aging treatment; The conditions for the casting include: the hydrogen content during the casting process does not exceed 0.1 cm 3 / 100g, the amount of waste added shall not exceed 25%, only the scrap aluminum with the surface as the base material shall be added, and the cast grain size shall be ≤50μm; The homogenization treatment conditions include: homogenization treatment at 545-555° C. for 9-10 hours, and cooling to room temperature at a cooling rate of 10-20° C. / h.

4. The method according to claim 3, characterized in that The extrusion conditions include: the distance from the mold guide plate to the mold hole at the thin-wall position is 2.7-3 times the distance from the mold guide plate to the mold hole at the thick-wall position, and the width of the mold front chamber at the thin-wall position is 14-16 times the width of the mold front chamber at the thick-wall position.

5. The method according to claim 3, characterized in that The extrusion conditions include: the time for a single point of metal to pass through the working belt is ≤0.2s.

6. The method according to claim 3, characterized in that The extrusion conditions include: a mold temperature of 460-500° C., an extrusion ingot temperature of 490-520° C., an extrusion barrel temperature of 440-460° C., and an extrusion speed of 1-1.5 m / min.

7. The method according to claim 3, characterized in that The aging treatment system is offline quenching at 552-558° C., holding temperature for 3.5-4.5 hours, and peak aging at 172-178° C. for 7.5-8.5 hours.

Images