Light rare earth cast aluminum alloy material for tire mold and preparation method thereof

Abstract

The application belongs to the technical field of aluminum alloy, and particularly relates to a light rare earth casting aluminum alloy material for a tire mold and a preparation method thereof. The light rare earth casting aluminum alloy material for the tire mold comprises the following raw materials in percentage by weight: Mg 3.0%-3.5%, Ce 0.1%-0.2%, Nd 0.3%-0.4%, Zn 0.10%-0.15%, Cu 0.05%-0.10%, Mn 0.2-0.5%, Cr 0.15%-0.35%, Fe 0.2-0.3%, Si 0.1-0.2%, Ti 0.05-0.15%, and Al the balance. The aluminum alloy material prepared by the application has high quality, excellent mechanical properties and wear resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum alloy, and particularly relates to a light rare earth cast aluminum alloy material for a tire mold and a preparation method thereof. BACKGROUND

[0002] AC7A alloy is an alloy with the largest elongation and good machinability in aluminum-magnesium series alloys. The AC7A aluminum alloy has good corrosion resistance, toughness and anodizing performance, but poor castability, and is used for wire supports, accessory parts, ship parts, handles, carving blanks, office appliances and airplane electrical installation products.

[0003] Tire mold aluminum alloy pattern blocks are essential key components in the tire manufacturing process, and their quality directly affects the appearance and performance of the tires. Currently, one of the commonly used aluminum alloy materials is AC7A (aluminum-magnesium alloy), which is widely used in the manufacture of tire molds due to its good mechanical properties, corrosion resistance and processing performance. However, in the actual production process, AC7A alloy still faces some problems in the processes of melting, casting and subsequent processing: 1. Difficulty in degassing and deslagging: During the melting process of aluminum alloy, hydrogen gas and oxide inclusions are easily produced, which can cause porosity and slag inclusion defects in the castings. 2. Poor fluidity: The fluidity of AC7A alloy is relatively poor, which can affect the filling effect of the castings, especially in the casting process of complex-shaped pattern blocks, incomplete filling problems are easily encountered. Poor fluidity can also cause cold shut, underfilling and other casting defects, affecting the quality and yield of the castings. 3. Many casting defects: Common defects in the casting process include sand holes, pores, shrinkage, etc. These problems not only affect the appearance of the castings, but also reduce their mechanical properties and service life. 4. Insufficient hardness: Although AC7A alloy has a certain hardness, with the increasing requirements of consumers, the current hardness level may not fully meet the needs of high-strength applications. 5. Corrosion resistance needs to be improved: Although AC7A alloy has good corrosion resistance, it may still have corrosion problems in some extreme environments.

[0004] Chinese Patent No. CN104561699B discloses a high-strength aluminum-magnesium alloy material for tire molds, which is obtained by adding rare earth elements to the aluminum-magnesium alloy and optimizing the element ratios of Cu, Mg, Si, Zn, Fe, Mn, Ti, Cr and Al. The tensile strength (Mpa) of the obtained aluminum-magnesium alloy is 300-400, the yield strength (Mpa) is 150-200, the elongation (%) is 12-14, and the Brinell hardness HB is 60-75.

[0005] Therefore, there is an urgent need for a light rare earth cast aluminum alloy material for a tire mold and a preparation method thereof. SUMMARY

[0006] The application aims to provide a light rare earth casting aluminum alloy material for tire mold and a preparation method thereof.

[0007] To achieve the above-mentioned purpose, the application provides the following technical solutions.

[0008] The light rare earth casting aluminum alloy material for tire mold comprises the following raw materials by weight percentage: Mg 3.0%-3.5%, Ce 0.1%-0.2%, Nd 0.3%-0.4%, Zn 0.10%-0.15%, Cu 0.05%-0.10%, Mn 0.2-0.5%, Cr 0.15%-0.35%, Fe 0.2-0.3%, Si 0.1-0.2%, Ti 0.05-0.15%, and Al the rest; wherein the ratio of Ce / Nd is 1:(2-2.5).

[0009] Further, the sum of the weight percentages of Ce and Nd is greater than the weight percentage of Mn.

[0010] The application can improve the mechanical properties of the aluminum alloy material at room temperature by adding specific types and proportions of rare earth elements in the aluminum alloy material.

[0011] Tire molds will face various complex working conditions and environmental challenges in actual use. In the tire manufacturing process, tire molds are usually subjected to vulcanization treatment under high temperature and high pressure conditions, and the vulcanization temperature is generally between 160-200℃. In such a high temperature environment, the mold material must maintain sufficient strength to prevent deformation or damage. During the vulcanization process, the mold needs to withstand pressure from the rubber mixture, which not only comes from the expansion force of the rubber itself, but also includes the gas pressure generated during the vulcanization process. High tensile strength at high temperature can ensure that the mold does not undergo plastic deformation or rupture under high pressure conditions. At the same time, tire molds usually have complex geometric shapes and fine pattern designs, which require the material to maintain good mechanical properties at high temperatures to ensure the overall structural integrity and precision of the mold. And tire molds are high-value equipment, usually need to maintain high performance for a long time. The aluminum alloy material of the present application improves the tensile properties of the aluminum alloy material at high temperature when the ratio of Ce / Nd is within a certain range, and the sum of the weight percentages of Ce and Nd is greater than the weight percentage of Mn. The added rare earth elements (Ce / Nd) form stable intermetallic compounds with the aluminum matrix. These nanoscale precipitates can act as heterogeneous nucleation cores to refine the grains. The atomic radius difference between Ce and Nd results in different solubility with Al. When the ratio of Ce / Nd is 1:2-1:2.5, the Al3(Ce / Nd) phase formed remains stable at high temperature, inhibiting dynamic recrystallization and grain boundary sliding through pinning the grain boundaries, thereby improving high temperature strength. Mn is easy to form coarse Al6Mn phase in Al, and when the total amount of Ce / Nd exceeds Mn, the generation of harmful phases is reduced, and high-temperature brittleness is reduced.

[0012] The present application also provides a preparation method of the light rare earth cast aluminum alloy material for tire molds, comprising the following steps:

[0013] (1) Melting: preheat the melting crucible to 300℃ under argon atmosphere, put aluminum into the preheated crucible, heat and melt to liquid state, and add the remaining raw materials when the aluminum liquid temperature reaches 700-750℃;

[0014] (2) Refining: add a refining agent and perform refining; after refining is completed, stand for 20-30min and then remove the slag;

[0015] (3) Pouring: preheat the tire mold to 230-250℃, pour the refined aluminum alloy liquid into the ladle, and pour on the mold, then naturally cool, and then take out for air cooling;

[0016] (4) Homogenization treatment: perform homogenization treatment on the pattern block obtained in step (3), and air cool to room temperature after homogenization treatment;

[0017] (5) Solution treatment: perform solution treatment on the pattern block obtained in step (4);

[0018] (6) aging treatment: the pattern block obtained in step (5) is subjected to aging treatment to obtain the aluminum alloy material.

[0019] Further, the refining agent in step (2) comprises NaF and NaCl in a weight ratio of 1: (1.2-1.4).

[0020] Further, the refining agent in step (2) is added in an amount of 0.1%-0.2% of the total weight of the raw materials of the aluminum alloy material.

[0021] Further, the refining conditions in step (2) are 760-770℃ for 20-30min.

[0022] Further, the pouring temperature in step (3) is controlled at 700-740℃.

[0023] Further, the homogenization treatment in step (4) is: first, under room temperature conditions, the temperature is raised to 430-440℃, and the temperature is maintained for 10-12h; then the temperature is continuously raised to 470-480℃, and the temperature is maintained for 7-9h; finally, the temperature is raised to 500-510℃, and the temperature is maintained for 14-15h, and air cooling is performed to room temperature.

[0024] By using the hierarchical homogenization treatment conditions, the wear resistance of the aluminum alloy material is improved. After homogenization treatment, the hard precipitated phase can be uniformly distributed in the matrix, and the grain boundary brittle phase is reduced, the crack initiation tendency in the wear process is reduced, and the wear resistance is improved.

[0025] Further, the solid solution treatment in step (5) is heated to 470-480℃ and maintained for 1-3h, and then air cooled.

[0026] Further, the aging treatment in step (6) is performed under artificial aging conditions at 120-190℃ for 12-15h, and air cooling is performed to room temperature.

[0027] Compared with the prior art, the advantages and beneficial effects of the present application are:

[0028] 1. By adding specific types and proportions of rare earth elements in the aluminum alloy material, the mechanical properties of the aluminum alloy material at room temperature can be improved.

[0029] 2. When the weight percentage of Ce / Nd is in a specific ratio, and the sum of the weight percentages of Ce and Nd is greater than the weight percentage of Mn, the tensile properties of the aluminum alloy material at high temperature are improved.

[0030] 3. By using hierarchical homogenization treatment conditions, the wear resistance of the aluminum alloy material is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the tire mold structure made of the aluminum alloy material of Example 1. DETAILED DESCRIPTION

[0032] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a light rare earth cast aluminum alloy material for a tire mold, comprising the following raw materials in percentage by weight: Mg 3.2%, Ce 0.15%, Nd 0.33%, Zn 0.12%, Cu 0.07%, Mn 0.3%, Cr 0.2%, Fe 0.24%, Si 0.17%, Ti 0.09%, and the balance Al;

[0035] The method for preparing the light rare earth cast aluminum alloy material for the tire mold comprises the following steps:

[0036] (1) Melting: In an argon atmosphere, preheat the melting crucible to 300°C, place aluminum into the preheated crucible, heat and melt it until it becomes liquid, and when the temperature of the aluminum liquid reaches 720°C, add the remaining raw materials;

[0037] (2) Refining: Add refining agent and carry out refining; after the refining is completed, let it stand for 20-30 minutes and then skim off the slag; the refining agent includes NaF and NaCl in a weight ratio of 1:1.3; the amount of refining agent added accounts for 0.15% of the total weight of the raw materials of the aluminum alloy material; the refining conditions are: refining at 765℃ for 20 minutes.

[0038] (3) Pouring: Preheat the tire mold to 240°C, pour the refined aluminum alloy liquid into the ladle, and pour it above the mold. The pouring temperature is controlled at 720°C. Let it cool naturally first, then take it out and air cool it.

[0039] (4) Homogenization treatment: The pattern blocks obtained in step (3) were subjected to homogenization treatment and then air-cooled to room temperature. The steps of the homogenization treatment were as follows: first, the temperature was raised to 430°C at room temperature and kept at this temperature for 11 hours; then the temperature was raised to 480°C and kept at this temperature for 8 hours; finally, the temperature was raised to 510°C and kept at this temperature for 14 hours, and then air-cooled to room temperature.

[0040] (5) Solution treatment: the pattern block obtained in step (4) is subjected to solution treatment; the solution treatment conditions are: heated to 470℃, kept for 2h, and then air cooled.

[0041] (6) Aging treatment: the pattern block obtained in step (5) is subjected to aging treatment; the aging treatment conditions are: treated under artificial aging conditions at 150℃ for 13h, and air cooled to room temperature, to obtain an aluminum alloy material.

[0042] Example 2

[0043] The present embodiment provides a light rare earth casting aluminum alloy material for tire mold, comprising the following raw materials by weight percentage: Mg 3.0%, Ce 0.2%, Nd 0.4%, Zn 0.15%, Cu 0.05%, Mn 0.5%, Cr 0.35%, Fe 0.3%, Si 0.1%, Ti 0.15%, Al balance;

[0044] The preparation method of the light rare earth casting aluminum alloy material for tire mold comprises the following steps:

[0045] (1) Melting: under an argon atmosphere, preheat the melting crucible to 300℃, put aluminum into the preheated crucible, heat and melt to liquid state, when the aluminum liquid temperature reaches 750℃, add the remaining raw materials;

[0046] (2) Refining: add a refining agent for refining; after refining, stand for 20min and then remove slag; the refining agent comprises NaF and NaCl in a weight ratio of 1:1.4; the addition amount of the refining agent accounts for 0.2% of the total weight of the raw materials of the aluminum alloy material; the refining conditions are: 760℃ refining for 30min.

[0047] (3) Pouring: preheat the tire mold to 230℃, pour the refined aluminum alloy liquid into a ladle, and pour on the mold, with the pouring temperature controlled at 740℃, first naturally cooled, and then air cooled after taking out;

[0048] (4) Homogenization treatment: the pattern block obtained in step (3) is subjected to homogenization treatment, and air cooled to room temperature after homogenization treatment; the homogenization treatment steps are: first heated to 430℃ under room temperature conditions, kept for 12h; continue to heat to 470℃, kept for 9h; finally heat to 500℃, kept for 15h, and air cooled to room temperature.

[0049] (5) Solution treatment: the pattern block obtained in step (4) is subjected to solution treatment; the solution treatment conditions are: heated to 470℃, kept for 3h, and then air cooled.

[0050] (6) aging treatment: the pattern block obtained in step (5) is subjected to aging treatment, and the aging treatment conditions are as follows: the aging treatment is performed at 190℃ for 12h, and the pattern block is air-cooled to room temperature, thereby obtaining the aluminum alloy material.

[0051] Comparative Example 1

[0052] The difference between this comparative example and Example 1 is that the raw material proportions are different.

[0053] A light rare earth casting aluminum alloy material for a tire mold comprises the following raw materials by weight percentage: Mg 4.0%, Ce 0.05%, Nd 0.24%, Zn 0.18%, Cu 0.02%, Mn 0.15%, Cr 0.10%, Fe 0.35%, Si 0.24%, Ti 0.02%, and Al the balance.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 1 is that the types of rare earth elements are different.

[0056] A light rare earth casting aluminum alloy material for a tire mold comprises the following raw materials by weight percentage: Mg 3.2%, La 0.15%, Pr 0.33%, Zn 0.12%, Cu 0.07%, Mn 0.3%, Cr 0.2%, Fe 0.24%, Si 0.17%, Ti 0.09%, and Al the balance.

[0057] Comparative Example 3

[0058] The difference between this comparative example and Example 1 is that the proportion of Ce / Nd is different.

[0059] A light rare earth casting aluminum alloy material for a tire mold comprises the following raw materials by weight percentage: Mg 3.2%, Ce 0.33%, Nd 0.15%, Zn 0.12%, Cu 0.07%, Mn 0.3%, Cr 0.2%, Fe 0.24%, Si 0.17%, Ti 0.09%, and Al the balance.

[0060] Comparative Example 4

[0061] The difference between this comparative example and Example 1 is that the sum of the weight percentages of Ce and Nd is less than the weight percentage of Mn.

[0062] A light rare earth casting aluminum alloy material for a tire mold comprises the following raw materials by weight percentage: Mg 3.2%, Ce 0.25%, Nd 0.1%, Zn 0.12%, Cu 0.07%, Mn 0.5%, Cr 0.2%, Fe 0.24%, Si 0.17%, Ti 0.09%, and Al the balance.

[0063] Comparative Example 5

[0064] The difference between the present comparative example and example 1 is that the homogenization treatment step is: heating to 480℃ at room temperature, holding for 36h, and air cooling to room temperature.

[0065] Comparative Example 6

[0066] The present comparative example differs from example 1 only in that the raw material of the aluminum alloy material is different. Referring to: Chinese patent No. CN104561699B discloses a high-strength aluminum-magnesium alloy material for tire mold, which comprises the following components by weight percentage: Cu 0.3%, Mg 3.9%, Si 0.2%, Zn 0.04%, Fe 0.01%, Mn 0.3%, Ti 0.15%, Cr 0.005%, Zr 0.05%, Sm 0.05%, Nd 0.05%, Y 0.05%, and the balance of Al.

[0067] Performance test

[0068] The aluminum alloy materials prepared in examples 1-2 and comparative examples 1-6 were subjected to performance tests

[0069] 1. The mechanical properties of the aluminum alloy material at room temperature and heated to 250℃ were determined by referring to GB / T228.1-2021 and ASTM A370.

[0070] 2. The Brinell hardness was determined by the Brinell hardness test method.

[0071] 3. The wear rate was detected by using MMG-5 type friction and wear tester, the load was 100N, the friction time was 150min, there was no lubrication, and 45# steel was used as the counter grinding material. Wear rate = weight after wear - weight before wear / weight before wear x 100%.

[0072] The results are shown in Table 1.

[0073] Table 1 Performance test results

[0074] Tensile strength at 25°C MPa Tensile strength at 200°C MPa Brinell hardness HB Wear rate % Example 1 487 345 89 1.43 Example 2 481 341 87 1.45 Comparative Example 1 428 287 79 1.89 Comparative Example 2 441 302 80 1.57 Comparative Example 3 454 314 85 1.63 Comparative Example 4 450 310 83 1.60 Comparative Example 5 437 304 81 1.80 Comparative Example 6 416 255 76 2.02

[0075] As can be seen from Table 1, the aluminum alloy material prepared in examples 1-2 of the present application has high tensile strength at room temperature and high temperature, high hardness, and good wear resistance.

[0076] The raw material ratio of the aluminum alloy material in comparative example 1 is different, and the comprehensive performance of the aluminum alloy material is decreased.

[0077] The types of rare earth elements used in comparative example 2 are different, and the mechanical properties at room temperature are decreased.

[0078] The ratio of Ce / Nd is different in Comparative Example 3 and Comparative Example 4, the sum of the weight percentages of Ce and Nd is less than the weight percentage of Mn, and the tensile property of the aluminum alloy material at high temperature decreases, which indicates that only when the specific conditions are met, the aluminum alloy material with excellent tensile property at high temperature can be obtained.

[0079] In Comparative Example 5, the uniform treatment conditions are changed, and the wear resistance of the aluminum alloy material decreases.

[0080] In Comparative Example 6, the composition of the aluminum alloy material in the prior art is used, and it can be found that the comprehensive performance of the prepared product is far lower than that of the embodiments 1-2 of the present application.

[0081] The above describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A light rare earth cast aluminum alloy material for tire molds, characterized in that: The raw materials include the following weight percentages: Mg 3.0%-3.5%, Ce 0.1%-0.2%, Nd 0.3%-0.4%, Zn 0.10%-0.15%, Cu 0.05%-0.10%, Mn 0.2-0.5%, Cr 0.15%-0.35%, Fe 0.2-0.3%, Si 0.1-0.2%, Ti 0.05-0.15%, and Al balance; wherein the ratio of Ce / Nd is 1:(2-2.5).

2. The light rare earth cast aluminum alloy material for a tire mold according to claim 1, characterized by, The sum of the weight percentages of Ce and Nd is greater than the weight percentage of Mn.

3. A method of producing a light rare earth cast aluminum alloy material for a tire mold as claimed in any one of claims 1 to 2, characterized by, The method comprises the following steps: (1) Melting: under an argon atmosphere, preheat a melting crucible to 300℃, put aluminum into the preheated crucible, heat and melt to a liquid state, and add the remaining raw materials when the aluminum liquid temperature reaches 700-750℃; (2) Refining: add a refining agent and perform refining; after the refining is completed, stand for 20-30 min and then remove the slag; (3) Pouring: preheat a tire mold to 230-250℃, pour the refined aluminum alloy liquid into a pouring ladle, and perform pouring above the mold, then naturally cool, and then take out and perform air cooling; (4) Homogenization treatment: perform homogenization treatment on the pattern block obtained in step (3), and air cool to room temperature after the homogenization treatment; (5) Solid solution treatment: perform solid solution treatment on the pattern block obtained in step (4); (6) Aging treatment: perform aging treatment on the pattern block obtained in step (5) to obtain an aluminum alloy material.

4. The method of producing a light rare earth cast aluminum alloy material for a tire mold according to claim 3, characterized by, The refining agent in step (2) includes NaF and NaCl in a weight ratio of 1:(1.2-1.4).

5. The method of producing a light rare earth cast aluminum alloy material for a tire mold according to claim 3, characterized by, The addition amount of the refining agent in step (2) accounts for 0.1%-0.2% of the total weight of the raw materials of the aluminum alloy material.

6. The method of producing a light rare earth cast aluminum alloy material for a tire mold according to claim 3, characterized by, The refining conditions in step (2) are 760-770℃ for 20-30 min.

7. The method of producing a light rare earth cast aluminum alloy material for a tire mold according to claim 3, characterized by, The pouring temperature in step (3) is controlled at 700-740℃.

8. The method of producing a light rare earth cast aluminum alloy material for a tire mold according to claim 3, characterized by, The homogenization treatment in step (4) comprises the following steps: first, under room temperature conditions, heat to 430-440℃, and keep warm for 10-12 h; then continue to heat to 470-480℃, and keep warm for 7-9 h; finally, heat to 500-510℃, and keep warm for 14-15 h, and air cool to room temperature.

9. The method of producing a light rare earth cast aluminum alloy material for a tire mold according to claim 3, characterized by, The solid solution treatment in step (5) is heated to 470-480℃ and kept for 1-3 h, and then air cooled.

10. The method of producing a light rare earth cast aluminum alloy material for a tire mold according to claim 3, characterized by, The aging treatment in step (6) is performed under artificial aging conditions at 120-190℃ for 12-15 h, and air cooled to room temperature.

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