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

Abstract

The invention 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 of the light rare earth cast aluminum alloy material. The light rare earth casting aluminum alloy material for the tire mold comprises the following raw materials in percentage by weight: 3.0%-3.5% of Mg, 0.1%-0.2% of Ce, 0.3%-0.4% of Nd, 0.10%-0.15% of Zn, 0.05%-0.10% of Cu, 0.2%-0.5% of Mn, 0.15%-0.35% of Cr, 0.2%-0.3% of Fe, 0.1%-0.2% of Si, 0.05%-0.15% of Ti and the balance of Al. The prepared aluminum alloy material is high in quality and excellent in mechanical property and wear resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloys, and particularly relates to a light rare earth cast aluminum alloy material for tire molds and a preparation method thereof. Background Art

[0002] Alloy AC7A is an alloy with the largest elongation rate and good machinability among aluminum-magnesium alloys. Alloy AC7A aluminum alloy has good corrosion resistance, toughness, and anodizing performance, but poor casting performance, and is used for overhead lines, fitting ship parts, handles, carving blanks, office appliances, and aircraft electrical installation supplies, etc.

[0003] The aluminum alloy tread block of a tire mold is an essential key component in the tire manufacturing process, and its quality directly affects the appearance and performance of the tire. Currently, one of the commonly used aluminum alloy materials is AC7A (aluminum-magnesium alloy), and this alloy 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, alloy AC7A still faces some problems in the melting, casting, and subsequent processing processes: 1. Difficulty in degassing and slag removal: During the melting process of aluminum alloy, hydrogen and oxide inclusions are easily generated, and these gases and impurities will cause porosity and slag inclusion defects inside the casting. 2. Insufficient fluidity: The fluidity of alloy AC7A is relatively poor, which will affect the filling effect of the casting. Especially during the casting process of complex-shaped tread blocks, incomplete filling is likely to occur. Poor fluidity will also cause casting defects such as cold shut and misrun, affecting the quality and yield of the casting. 3. Many casting defects: Common defects in the casting process include sand holes, pores, shrinkage porosity, etc. These problems not only affect the appearance of the casting but also reduce its mechanical properties and service life. 4. Insufficient hardness: Although alloy AC7A 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 alloy AC7A has good corrosion resistance, corrosion problems may still occur in some extreme environments.

[0004] Chinese Patent No. CN104561699B discloses a high-strength aluminum-magnesium alloy material for tire molds. 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 obtained aluminum-magnesium alloy has a tensile strength (Mpa): 300 - 400, a yield strength (Mpa): 150 - 200, an elongation rate (%): 12 - 14; and a Brinell hardness HB: 60 - 75.

[0005] Therefore, there is an urgent need for a light rare earth cast aluminum alloy material for tire molds and a preparation method thereof. Summary of the Invention

[0006] The object of the present invention is to provide a light rare earth cast aluminum alloy material for tire molds and a preparation method thereof.

[0007] To achieve the above object, the present invention provides the following technical solutions: A light rare earth cast aluminum alloy material for tire molds, comprising raw materials in 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%, with the balance being Al; wherein, the ratio of Ce / Nd is 1:(2-2.5).

[0008] Furthermore, the sum of the weight percentages of Ce and Nd is greater than the weight percentage of Mn.

[0009] By adding specific types and proportions of rare earth elements to the aluminum alloy material, the present invention can improve the mechanical properties of the aluminum alloy material at room temperature.

[0010] During the actual use process of tire molds, they will face various complex working conditions and environmental challenges. During the tire manufacturing process, tire molds usually undergo vulcanization treatment under high temperature and high pressure conditions, and the vulcanization temperature is generally between 160~200°C. 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 the pressure from the rubber mixture, and this pressure 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 temperatures 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, and these designs require the material to still maintain good mechanical properties at high temperatures to ensure the overall structural integrity and accuracy of the mold. And tire molds are high-value equipment and usually need to maintain high performance for a long time. When Ce / Nd of the aluminum alloy material of the present invention is at 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 temperatures are improved. The rare earth elements (Ce / Nd) added in the present invention form stable intermetallic compounds with the aluminum matrix. These nano-scale precipitation phases can serve as heterogeneous nucleation cores to refine the grains. The difference in atomic radii between Ce and Nd results in different solid solubilities with Al. When the Ce / Nd ratio is 1:2~1:2.5, the formed Al3(Ce / Nd) phase remains stable at high temperatures and inhibits dynamic recrystallization and grain boundary slip by pinning the grain boundaries, thereby enhancing the high-temperature strength. Mn easily forms coarse Al6Mn phases in Al, and when the total amount of Ce / Nd exceeds Mn, the generation of harmful phases is reduced and the high-temperature brittleness is lowered.

[0011] The present invention also provides a preparation method of the light rare earth cast aluminum alloy material for the tire mold, comprising the following steps: (1) Melting: Under an argon atmosphere, preheat the melting crucible to 300 °C, put aluminum into the preheated crucible, heat and melt it to a liquid state, and when the temperature of the aluminum liquid reaches 700 - 750 °C, add the remaining raw materials; (2) Refining: Add a refining agent and conduct refining; after the refining is completed, let it stand for 20 - 30 min and then skim the slag; (3) Pouring: Preheat the tire mold to 230 - 250 °C, pour the refined aluminum alloy liquid into a ladle, and conduct pouring above the mold. First, let it cool naturally, and then take it out for air cooling; (4) Homogenization treatment: Conduct homogenization treatment on the pattern block obtained in step (3), and after the homogenization treatment, air cool it to room temperature; (5) Solution treatment: Conduct solution treatment on the pattern block obtained in step (4); (6) Aging treatment: Conduct aging treatment on the pattern block obtained in step (5) to obtain the aluminum alloy material.

[0012] Further, in the step (2), the refining agent comprises NaF and NaCl with a weight ratio of 1:(1.2 - 1.4).

[0013] Further, the addition amount of the refining agent in the step (2) accounts for 0.1% - 0.2% of the total weight of the raw materials of the aluminum alloy material.

[0014] Further, the refining conditions in the step (2) are: refining at 760 - 770 °C for 20 - 30 min.

[0015] Further, the pouring temperature in the step (3) is controlled at 700 - 740 °C.

[0016] Further, the steps of the homogenization treatment in the step (4) are: first, under room temperature conditions, raise the temperature to 430 - 440 °C, hold for 10 - 12 h; continue to raise the temperature to 470 - 480 °C, hold for 7 - 9 h; finally, raise the temperature to 500 - 510 °C, hold for 14 - 15 h, and air cool to room temperature.

[0017] By using the hierarchical homogenization treatment conditions in the present invention, the wear resistance of the aluminum alloy material is improved. After the homogenization treatment, the hard precipitated phases can be evenly distributed in the matrix, and at the same time, the brittle phases at the grain boundaries are reduced, reducing the crack initiation tendency during the wear process and improving the wear resistance.

[0018] Further, the solution treatment conditions in the step (5) are: heat to 470 - 480 °C, hold for 1 - 3 h, and then air cool.

[0019] Furthermore, the aging treatment conditions in step (6) are as follows: treatment is carried out under artificial aging conditions of 120 - 190 °C for 12 - 15 h, and then air-cooled to room temperature.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. By adding specific types and ratios of rare earth elements to the aluminum alloy material, the mechanical properties of the aluminum alloy material at room temperature can be improved.

[0021] 2. When Ce / Nd is at a specific ratio and the sum of the weight percentages of Ce and Nd is greater than the weight percentage of Mn in the aluminum alloy material of the present invention, the tensile properties of the aluminum alloy material at high temperatures are improved.

[0022] 3. By using hierarchical homogenization treatment conditions, the wear resistance of the aluminum alloy material is improved. Description of the Drawings

[0023] Figure 1 Schematic structural diagram of a tire mold prepared from the aluminum alloy material of Example 1. Detailed Embodiments

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0025] Example 1 This example provides a light rare earth cast aluminum alloy material for a tire mold, including the following raw materials in weight percentages: 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%, with the balance being Al; The preparation method of the light rare earth cast aluminum alloy material for the tire mold includes the following steps: (1) Melting: Under an argon atmosphere, preheat the melting crucible to 300 °C, put aluminum into the preheated crucible, heat and melt it to a liquid state, and when the temperature of the aluminum liquid reaches 720 °C, add the remaining raw materials; (2) Refining: Add a refining agent for refining; after the refining is completed, let it stand for 20 - 30 min and then skim the slag; the refining agent includes NaF and NaCl with a weight ratio of 1:1.3; the addition amount of the refining agent accounts for 0.15% of the total weight of the raw materials of the aluminum alloy material; the refining conditions are: refining at 765 °C for 20 min.

[0026] (3) Pouring: Preheat the tire mold to 240 °C, pour the refined aluminum alloy liquid into the ladle, and pour it above the mold. Control the pouring temperature at 720 °C, first cool naturally, and then take it out for air cooling; (4) Homogenization treatment: Homogenize the tread blocks obtained in step (3), and air cool to room temperature after homogenization treatment. The steps of homogenization treatment are as follows: First, at room temperature, heat up to 430 °C and hold for 11 h; continue to heat up to 480 °C and hold for 8 h; finally, heat up to 510 °C and hold for 14 h, and then air cool to room temperature.

[0027] (5) Solution treatment: Perform solution treatment on the tread blocks obtained in step (4). The conditions for solution treatment are: Heat to 470 °C, hold for 2 h, and then air cool.

[0028] (6) Aging treatment: Perform aging treatment on the tread blocks obtained in step (5). The conditions for aging treatment are: Carry out treatment under artificial aging conditions of 150 °C for 13 h, and air cool to room temperature to obtain the aluminum alloy material.

[0029] Example 2 This example provides a light rare earth cast aluminum alloy material for tire molds, including the following raw materials in weight percentages: 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%, with the balance being Al; The preparation method of the light rare earth cast aluminum alloy material for the tire mold includes the following steps: (1) Melting: Under an argon atmosphere, preheat the melting crucible to 300 °C, put the aluminum into the preheated crucible, heat and melt it into a liquid state. When the temperature of the aluminum liquid reaches 750 °C, add the remaining raw materials; (2) Refining: Add a refining agent for refining; after the refining is completed, let it stand for 20 min and then skim the slag. The refining agent includes NaF and NaCl with 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 conditions for refining are: Refine at 760 °C for 30 min.

[0030] (3) Pouring: Preheat the tire mold to 230 °C, pour the refined aluminum alloy liquid into the ladle, and pour it above the mold. Control the pouring temperature at 740 °C, first cool naturally, and then take it out for air cooling; (4) Homogenization treatment: Homogenize the tread blocks obtained in step (3), and air cool to room temperature after homogenization treatment. The steps of homogenization treatment are as follows: First, at room temperature, heat up to 430 °C and hold for 12 h; continue to heat up to 470 °C and hold for 9 h; finally, heat up to 500 °C and hold for 15 h, and then air cool to room temperature.

[0031] (5) Solution treatment: The pattern blocks obtained in step (4) are subjected to solution treatment; the conditions for solution treatment are: heating to 470 °C, holding for 3 h, and then air cooling.

[0032] (6) Aging treatment: The pattern blocks obtained in step (5) are subjected to aging treatment, and the conditions for aging treatment are: treating under artificial aging conditions at 190 °C for 12 h, air cooling to room temperature to obtain the aluminum alloy material.

[0033] Comparative Example 1 The difference between this comparative example and Example 1 is: different raw material ratios.

[0034] A light rare earth cast aluminum alloy material for tire molds, comprising the following raw materials in weight percentages: 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%, with the balance being Al.

[0035] Comparative Example 2 The difference between this comparative example and Example 1 is: different types of rare earth elements.

[0036] A light rare earth cast aluminum alloy material for tire molds, comprising the following raw materials in weight percentages: 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%, with the balance being Al

[0037] Comparative Example 3 The difference between this comparative example and Example 1 is: different ratios of Ce / Nd.

[0038] A light rare earth cast aluminum alloy material for tire molds, comprising the following raw materials in weight percentages: 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%, with the balance being Al.

[0039] Comparative Example 4 The difference between this comparative example and Example 1 is: the sum of the weight percentages of Ce and Nd is less than the weight percentage of Mn.

[0040] A light rare earth cast aluminum alloy material for tire molds, comprising raw materials in the following weight percentages: 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%, with the balance being Al.

[0041] Comparative Example 5 The difference between this comparative example and Example 1 is that the steps of homogenization treatment are as follows: at room temperature, heat up to 480 °C, hold for 36 h, and air cool to room temperature.

[0042] Comparative Example 6 The difference between this comparative example and Example 1 is only that the raw materials of the aluminum alloy material are different. Refer to Example 1 of a high-strength aluminum-magnesium alloy material for tire molds disclosed in Chinese Patent No. CN104561699B, which includes the following components in weight percentages: 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%, with the balance being Al.

[0043] Performance Test Perform performance tests on the aluminum alloy materials prepared in Examples 1-2 and Comparative Examples 1-6 1. Refer to GB / T228.1-2021 and ASTM A370 to determine the mechanical properties of the aluminum alloy material at room temperature and heated to 250 °C.

[0044] 2. Determine the Brinell hardness through the Brinell hardness test method.

[0045] 3. Use an MMG-5 type friction and wear testing machine to detect the wear rate. The load is 100 N, the friction time is 150 min, without lubrication, and 45# steel is used as the counter-material. Wear rate = (weight before wear - weight after wear) / weight before wear × 100%.

[0046] The results are shown in Table 1.

[0047] Table 1 Performance Test Results 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 As can be seen from Table 1, the aluminum alloy materials prepared in Examples 1-2 of the present invention have high tensile strength, high hardness, and good wear resistance at room temperature and high temperature.

[0048] In Comparative Example 1, the raw material ratio of the aluminum alloy material is different, and the comprehensive performance of the aluminum alloy material decreases.

[0049] In Comparative Example 2, the types of rare earth elements used are different, and the mechanical properties at room temperature decrease.

[0050] In Comparative Example 3 and Comparative Example 4, the ratio of Ce / Nd is different, and the sum of the weight percentages of Ce and Nd is less than the weight percentage of Mn, resulting in a decline in the tensile properties of the aluminum alloy material at high temperatures. This shows that only by meeting specific conditions can an aluminum alloy material with excellent tensile properties at high temperatures be obtained.

[0051] In Comparative Example 5, the conditions of homogenization treatment are changed, and the wear resistance of the aluminum alloy material decreases.

[0052] In Comparative Example 6, by using the composition of the aluminum alloy material in the prior art, it can be found that the comprehensive properties of the prepared product are much lower than those of Examples 1-2 of the present invention.

[0053] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art of the present technology, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A light rare earth cast aluminum alloy material for tire molds, characterized in that, Raw materials including 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%, with the balance being Al; wherein, the ratio of Ce / Nd is 1:(2 - 2.5).

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

3. A method for preparing a light rare earth cast aluminum alloy material for a tire mold according to any one of claims 1-2, characterized in that, Including the following steps: (1) Melting: Under an argon atmosphere, preheat the melting crucible to 300°C, put the aluminum into the preheated crucible, heat and melt it to a liquid state, and when the temperature of the aluminum liquid reaches 700 - 750°C, add the remaining raw materials; (2) Refining: Add a refining agent for refining; after the refining is completed, let it stand for 20 - 30 min and then skim the slag; (3) Pouring: Preheat the tire mold to 230 - 250°C, pour the refined aluminum alloy liquid into a ladle, and pour it above the mold. First, let it cool naturally, and then take it out for air cooling; (4) Homogenization treatment: Perform homogenization treatment on the tread blocks obtained in step (3), and air cool to room temperature after homogenization treatment; (5) Solution treatment: Perform solution treatment on the tread blocks obtained in step (4); (6) Aging treatment: Perform aging treatment on the tread blocks obtained in step (5) to obtain an aluminum alloy material.

4. The preparation method of the light rare earth cast aluminum alloy material for tire molds according to claim 3, characterized in that, In the said step (2), the refining agent includes NaF and NaCl with a weight ratio of 1:(1.2 - 1.4).

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

6. The preparation method of the light rare earth cast aluminum alloy material for tire molds according to claim 3, characterized in that, The refining conditions in the said step (2) are: refining at 760 - 770°C for 20 - 30 min.

7. The preparation method of the light rare earth cast aluminum alloy material for tire molds according to claim 3, characterized in that, The pouring temperature in the said step (3) is controlled at 700 - 740°C.

8. The preparation method of the light rare earth cast aluminum alloy material for tire molds according to claim 3, characterized in that, The steps of the homogenization treatment in the said step (4) are: First, under room temperature conditions, raise the temperature to 430 - 440°C, hold for 10 - 12 h; continue to raise the temperature to 470 - 480°C, hold for 7 - 9 h; finally, raise the temperature to 500 - 510°C, hold for 14 - 15 h, and air cool to room temperature.

9. The preparation method of the light rare earth cast aluminum alloy material for tire molds according to claim 3, characterized in that, The solution treatment conditions in the said step (5) are: Heat to 470 - 480°C, hold for 1 - 3 h, and then air cool.

10. The preparation method of the light rare earth cast aluminum alloy material for tire molds according to claim 3, characterized in that, The aging treatment conditions in the said step (6) are: Perform treatment for 12 - 15 h under artificial aging conditions of 120 - 190°C, and air cool to room temperature.

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