Preparation method of microalloyed high-temperature-resistant aluminum alloy

Abstract

The invention discloses a preparation method of a microalloyed high-temperature-resistant aluminum alloy. The high-temperature-resistant aluminum alloy is prepared from the following components in percentage by mass: 4.7 percent to 5.04 percent of Cu, 0.98 percent to 1.08 percent of Fe, 1.45 percent to 1.6 percent of Ni, 0.51 percent to 0.56 percent of Mn, 0.45 percent to 0.55 percent of Mg, 0.18 percent to 0.2 percent of Ti, 0.2 percent to 0.32 percent of Ce, 0.05 percent to 0.3 percent of Zr, impurities and the balance of Al. By adding Mn, an Al20Cu3Mn2 precipitated phase with high thermal stability can be formed, and Mn is gathered around a theta'phase to inhibit coarsening of the theta 'phase, so that the high-temperature strength and the alloy performance of the aluminum alloy are improved. Fe and Ni are added, so that a stable iron-rich phase Al9FeNi is formed, and the thermal stability and the high-temperature strength of the alloy are also favorably improved. Ti is attached to the periphery of a theta'precipitated phase and hinders coarsening of the theta 'precipitated phase, grains are refined, and the high-temperature strength of the aluminum alloy is cooperatively improved. Ce can form an Al-Ce-M (M = Fe, Ti) intermetallic compound, and can also synergistically improve the thermal stability of the aluminum alloy. In addition, by adding the compounded refining agent, the degassing and impurity removal efficiency can be improved, and after deep purification, the high-temperature-resistant strength of the aluminum alloy is promoted. And the effect of improving the high-temperature strength of the alloy is integrally achieved.

Description

Technical Field

[0001] The invention relates to the field of aluminum alloy preparation, and in particular to a method for preparing a micro-alloyed high-temperature resistant aluminum alloy. Background Art

[0002] Aluminum alloys have been widely used in the fields of automobiles, ships, weapons, aerospace and aviation due to their low density and excellent thermal conductivity. However, the mechanical properties of aluminum alloys at high temperatures are poor, which limits the further expansion of their application range. Therefore, improving the high-temperature mechanical properties of aluminum alloys not only has important practical application value, but also has far-reaching theoretical significance. In cast heat-resistant aluminum alloys, the commonly used alloy systems mainly include Al-Si and Al-Cu. The advantage of the Al-Si system is its excellent casting performance, which can form various parts with complex structures. However, the alloy has relatively low strength at room temperature and high temperature, so it is not suitable for the manufacture of parts requiring higher operating temperature and strength requirements. In contrast, the heat resistance of Al-Cu cast aluminum alloys is better than that of Al-Si. For example, the applicable temperature of cast Al-Si-Mg alloys generally does not exceed 185°C, while the working temperature of Al-Si-Cu-Mg alloys can be increased to 200°C to 225°C. The main reason is that the alloy contains W (Al4Mg5Si4Cu4) phase, which can still maintain high thermal stability at 225°C. Therefore, Al-Cu cast aluminum alloys have better high-temperature mechanical properties and can be used in working environments of 300°C to 400°C. However, when the operating temperature approaches 350°C, the main strengthening phase will coarsen and lose its strengthening effect. Therefore, it is necessary to improve the high-temperature strength of Al-Cu alloys at 350°C and above.

[0003] The Chinese patent publication number CN 114807693A discloses a preparation method and application of a combined microalloyed high heat-resistant aluminum alloy, the alloy contains: Sb: 0.01~0.05wt.%, Mn: 0.1~0.3wt.%; the balance is an aluminum alloy matrix. By adding Sb and Mn elements and solid solution + aging heat treatment, a heat-resistant alloy with a tensile strength of ≥150MPa at a high temperature of 300°C is obtained. For example, the Chinese patent publication number CN109402441A discloses a method for preparing AlN and Al2O3 particle reinforced aluminum-based composite materials using ultrafine aluminum powder and air as raw materials. The tensile strength of the composite material can reach up to 130MPa at 375°C. The above patents all obtain relatively good high-temperature performance through component optimization design and preparation methods. However, the alloy disclosed in CN 114807693 A is close to pure aluminum, has poor casting performance, and its high temperature resistance needs to be further improved; the method in CN 109402441 A has a complex preparation process, high cost, and great difficulty in regulation, and is not suitable for industrial application and production. Summary of the invention

[0004] Based on this, in order to solve the technical problem that the aluminum alloy prepared by the prior art has poor high temperature mechanical properties, the present invention provides a method for preparing a micro-alloyed high temperature resistant aluminum alloy, and the specific technical scheme is as follows:

[0005] A method for preparing a microalloyed high temperature resistant aluminum alloy, the method comprising the following steps:

[0006] The pure aluminum ingot is then added into the smelting furnace, and Al-Fe alloy, Al-Mn alloy, Al-Ni alloy and Al-Cu alloy are added in sequence, and the raw materials containing Ti element, Mg element, Zr element and Ce element are added after being completely melted, and electromagnetic stirring is used to promote the flow of the melt to obtain a melt with high uniformity;

[0007] Using an inert gas as a carrier, introducing a refining agent with a mass fraction of 0.05% to 0.15% for the first refining, and the first refining is kept at 720° C. to 750° C. for 10 min to 30 min, sampling and testing the composition, and adjusting the alloy composition;

[0008] The scum on the surface of the melt is removed, and a refining agent with a mass fraction of 0.03% to 0.13% is introduced with an inert gas as a carrier to perform a second refining, and the second refining is kept at 720° C. to 750° C. for 10 min to 30 min;

[0009] After the second refining is completed, the scum on the surface of the melt is removed again, and then the melt is introduced into the degassing and filtering device for online degassing and online filtering, and flows into the holding furnace through the flow channel to directly supply the casting molding machine for casting processing to obtain an ingot;

[0010] The ingot is subjected to T5 heat treatment, and the conditions of the T5 heat treatment are: raising the furnace temperature to 500°C to 550°C and maintaining it for 10h to 15h, then quickly taking it out and quenching it to room temperature, then raising the temperature to 150°C to 200°C, maintaining it for 6h to 10h, air cooling, completing aging treatment, and obtaining a high temperature resistant aluminum alloy.

[0011] Furthermore, the high temperature resistant aluminum alloy is composed of the following components in mass percentage: Cu: 4.7% to 5.04%, Fe: 0.98% to 1.08%, Ni: 1.45% to 1.6%, Mn: 0.51% to 0.56%, Mg: 0.45% to 0.55%, Ti: 0.18% to 0.2%, Ce: 0.2% to 0.32%, Zr: 0.05% to 0.3%, the total amount of unavoidable impurity elements does not exceed 0.3%, and the balance is Al.

[0012] Furthermore, the temperature of the smelting treatment is 750-800°C.

[0013] Furthermore, the average particle size of the refining agent is 0.5 mm to 3 mm.

[0014] Furthermore, the refining agent consists of KCl, MnCl2 and K2CO3 in a mass ratio of (1-3):(1-5):(1-2).

[0015] Furthermore, the preparation method of the refining agent is: KCl, MnCl2 and K2CO3 are mixed, dried at 100°C to 120°C, calcined at 500°C to 800°C for 20min to 30min, and then pulverized after cooling.

[0016] Furthermore, during the first refining and the second refining, the flow rate of the inert gas is controlled to be 45 L / min to 60 L / min.

[0017] Furthermore, the online degassing time is 10 min to 40 min, the online degassing uses N2 as the covering gas, the pressure is 0.15 MPa to 0.35 MPa, and the flow rate is 50 L / min to 120 L / min.

[0018] Furthermore, the online filtration is performed using a double-stage foam ceramic filter plate with a front mesh of 40 to 60 and a rear mesh of 60 to 80.

[0019] Furthermore, the casting process speed is 15 mm / min to 30 mm / min, the temperature is 720°C to 750°C, and the flow rate of cooling water is 25 m 3 / h~30m 3 / h.

[0020] Compared with the prior art, this application has the following beneficial effects:

[0021] The present application improves the high-temperature mechanical properties of aluminum alloys by optimizing the alloy composition ratio and heat treatment process. The present application has the following significant advantages: (1) By adding trace alloying elements to traditional aluminum alloys, the high-temperature mechanical properties of aluminum alloys can be significantly improved; (2) The preparation method of the present application significantly enhances the thermal stability of aluminum alloys during long-term high-temperature exposure; (3) The aluminum alloy of the present application has excellent heat resistance, and the tensile strength, yield strength and elongation at 300°C reach 270MPa, 195MPa and 4.0% or more, respectively; the tensile strength, yield strength and elongation at 350°C reach 225MPa, 155MPa and 4.5% or more, respectively; the tensile strength at 400°C can still reach 145MPa, 13MPa and 7.0% or more, which can meet the requirements of aluminum alloy parts with different heat resistance requirements; (4) The preparation process is simple, no special treatment is required, and mass production can be achieved. Therefore, the present invention is based on Al-Cu alloys and significantly improves the heat resistance of the alloy through composition design, microalloying and heat treatment, making it suitable for manufacturing structural components of aircraft, rockets, missiles and other aircraft, as well as automobile engine parts.

[0022] Specifically, by adding a trace amount of Mn element, on the one hand, Al 20 Cu3Mn2 precipitates and Mn gathers around the θ' phase to inhibit its coarsening, thereby improving the high-temperature strength of the aluminum alloy; on the other hand, the formation of the needle-like iron-rich phase is inhibited, and a spatially connected network-like iron-rich phase Al6 (FeMn) is formed, thereby improving the performance of the aluminum alloy. At the same time, Fe and Ni elements are added in appropriate amounts to form a stable iron-rich phase Al9FeNi, thereby improving the thermal stability and high-temperature strength of the aluminum alloy. Ti has a low diffusion rate in the aluminum matrix, adheres to the periphery of the θ' precipitated phase and hinders its coarsening, which can further improve the high-temperature strength of the aluminum alloy; at the same time, Ti acts as a refining element to refine the grains and synergistically improve the room-temperature strength of the aluminum alloy. The Ce element can form Al-Ce-M (M=Fe,Ti) intermetallic compounds, further synergistically improving the thermal stability of the aluminum alloy. In addition, by adding a compounded refining agent, it not only helps to improve the efficiency of degassing and impurity removal, but also has a positive effect on the heat-resistant strength of the aluminum alloy after deep purification. On the whole, the present invention can achieve the effect of improving the high-temperature strength of the alloy by optimizing the composition ratio. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with its embodiments. It should be understood that the specific implementation methods described herein are only used to explain the present invention and do not limit the protection scope of the present invention.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] A method for preparing a microalloyed high temperature resistant aluminum alloy in one embodiment of the present invention comprises the following steps:

[0026] The pure aluminum ingot is then added into the smelting furnace, and Al-Fe alloy, Al-Mn alloy, Al-Ni alloy and Al-Cu alloy are added in sequence, and the raw materials containing Ti element, Mg element, Zr element and Ce element are added after being completely melted, and electromagnetic stirring is used to promote the flow of the melt to obtain a melt with high uniformity;

[0027] Using an inert gas as a carrier, introducing a refining agent with a mass fraction of 0.05% to 0.15% for the first refining, and the first refining is kept at 720° C. to 750° C. for 10 min to 30 min, sampling and testing the composition, and adjusting the alloy composition;

[0028] The scum on the surface of the melt is removed, and a refining agent with a mass fraction of 0.03% to 0.13% is introduced with an inert gas as a carrier to perform a second refining, and the second refining is kept at 720° C. to 750° C. for 10 min to 30 min;

[0029] After the second refining is completed, the scum on the surface of the melt is removed again, and then the melt is introduced into the degassing and filtering device for online degassing and online filtering, and flows into the holding furnace through the flow channel to directly supply the casting molding machine for casting processing to obtain an ingot;

[0030] The ingot is subjected to T5 heat treatment, and the conditions of the T5 heat treatment are: raising the furnace temperature to 500°C to 550°C and maintaining it for 10h to 15h, then quickly taking it out and quenching it to room temperature, then raising the temperature to 150°C to 200°C, maintaining it for 6h to 10h, air cooling, completing aging treatment, and obtaining a high temperature resistant aluminum alloy.

[0031] In one of the embodiments, the high temperature resistant aluminum alloy is composed of the following components in mass percentage: Cu: 4.7% to 5.04%, Fe: 0.98% to 1.08%, Ni: 1.45% to 1.6%, Mn: 0.51% to 0.56%, Mg: 0.45% to 0.55%, Ti: 0.18% to 0.2%, Ce: 0.2% to 0.32%, Zr: 0.05% to 0.3%, the total amount of unavoidable impurity elements does not exceed 0.3%, and the balance is Al.

[0032] In one embodiment, the temperature of the smelting process is 750-800°C.

[0033] In one embodiment, the average particle size of the refining agent is 0.5 mm to 3 mm.

[0034] In one embodiment, the refining agent is composed of KCl, MnCl2 and K2CO3 in a mass ratio of (1-3):(1-5):(1-2).

[0035] In one embodiment, the refining agent is prepared by mixing KCl, MnCl2 and K2CO3, drying them at 100°C to 120°C, calcining them at 500°C to 800°C for 20min to 30min, and then cooling and crushing them.

[0036] In one embodiment, during the first refining and the second refining, the flow rate of the inert gas is controlled to be 45 L / min to 60 L / min.

[0037] In one of the embodiments, the online degassing time is 10 min to 40 min, and the online degassing uses N2 as the covering gas, the pressure is 0.15 MPa to 0.35 MPa, and the flow rate is 50 L / min to 120 L / min.

[0038] In one embodiment, the online filtration is performed using a double-stage foam ceramic filter plate with a front mesh of 40 to 60 mesh and a rear mesh of 60 to 80 mesh.

[0039] In one embodiment, the casting process speed is 15 mm / min to 30 mm / min, the temperature is 720°C to 750°C, and the flow rate of cooling water is 25 m / min. 3 / h~30m 3 / h.

[0040] The above scheme can obtain an aluminum alloy with excellent high temperature resistance and strength by optimizing the composition and component ratio.

[0041] The embodiments of the present invention will be described in detail below with reference to specific examples.

[0042] Embodiment 1:

[0043] A microalloyed high temperature resistant aluminum alloy is composed of the following components in mass percentage: Cu: 4.7%, Fe: 0.98%, Ni: 1.45%, Mn: 0.51%, Mg: 0.45%, Ti: 0.18%, Ce: 0.32%, Zr: 0.1%, the total amount of unavoidable impurity elements does not exceed 0.3%, and the balance is Al.

[0044] A method for preparing a microalloyed high temperature resistant aluminum alloy comprises the following steps:

[0045] Mix KCl, MnCl2 and K2CO3 in a mass ratio of 3:1:1, dry at 120°C, calcine at 650°C for 25 minutes, and grind to obtain a refining agent with an average particle size of 1 mm after cooling for later use;

[0046] The pure aluminum ingot is then added into the smelting furnace, and Al-Fe alloy, Al-Mn alloy, Al-Ni alloy and Al-Cu alloy are added in sequence, and smelted at 750°C. After being completely melted, raw materials containing Ti, Mg, Zr and Ce elements are continuously added, and electromagnetic stirring is performed to promote melt flow, so as to obtain a melt with high uniformity;

[0047] The flow rate of the inert gas is controlled to be 45 L / min and the inert gas is used as a carrier, and a refining agent with a mass fraction of 0.15% is introduced for the first refining, and the first refining is kept at 750° C. for 30 minutes, and the composition is sampled and tested, and the alloy composition is adjusted;

[0048] The scum on the surface of the melt was removed, the flow rate of the inert gas was controlled to 45 L / min, and a refining agent with a mass fraction of 0.12% was introduced using the inert gas as a carrier to perform a second refining, and the second refining was kept at 750° C. for 30 min;

[0049] After the second refining is completed, the scum on the surface of the melt is removed again, and then the melt is introduced into the degassing and filtering device for online degassing and online filtering, and the online degassing time is 20 minutes, and the online degassing uses N2 as the covering gas, the pressure is 0.15MPa, and the flow rate is 80L / min; the online filtration uses a two-stage foam ceramic filter plate with a front 40 mesh and a rear 60 mesh for filtration;

[0050] The liquid flows into the holding furnace through the flow channel and is directly supplied to the casting molding machine for casting. The casting speed is 25 mm / min, the temperature is 720°C, and the cooling water flow rate is 30 m 3 / h, to obtain an ingot;

[0051] The ingot is subjected to T5 heat treatment, and the conditions of the T5 heat treatment are: the furnace temperature is raised to 538°C and maintained for 12 hours, then quickly taken out and quenched to room temperature, then the temperature is raised to 160°C, kept for 8 hours, air-cooled, and aging treatment is completed to obtain a high temperature resistant aluminum alloy.

[0052] Embodiment 2:

[0053] A microalloyed high temperature resistant aluminum alloy is composed of the following components in percentage by mass: Cu: 4.85%, Fe: 1.02%, Ni: 1.52%, Mn: 0.53%, Mg: 0.48%, Ti: 0.19%, Ce: 0.24%, Zr: 0.21%, the total amount of unavoidable impurity elements does not exceed 0.3%, and the balance is Al.

[0054] A method for preparing a microalloyed high temperature resistant aluminum alloy comprises the following steps:

[0055] Mix KCl, MnCl2 and K2CO3 in a mass ratio of 2:2:1, dry at 120°C, calcine at 700°C for 20 minutes, and grind to obtain a refining agent with an average particle size of 1 mm after cooling, for later use;

[0056] The pure aluminum ingot is then added into the smelting furnace, and Al-Fe alloy, Al-Mn alloy, Al-Ni alloy and Al-Cu alloy are added in sequence, and smelted at 750°C. After being completely melted, raw materials containing Ti, Mg, Zr and Ce elements are continuously added, and electromagnetic stirring is performed to promote melt flow, so as to obtain a melt with high uniformity;

[0057] The flow rate of the inert gas is controlled to be 45 L / min and the inert gas is used as a carrier, and a refining agent with a mass fraction of 0.15% is introduced for the first refining, and the first refining is kept at 720° C. for 20 minutes, and the composition is sampled and tested, and the alloy composition is adjusted;

[0058] The scum on the surface of the melt was removed, the flow rate of the inert gas was controlled to 45 L / min, and a refining agent with a mass fraction of 0.1% was introduced using the inert gas as a carrier to perform a second refining, and the second refining was kept at 720° C. for 20 min;

[0059] After the second refining is completed, the scum on the surface of the melt is removed again, and then the melt is introduced into the degassing and filtering device for online degassing and online filtering, and the online degassing time is 20 minutes, and the online degassing uses N2 as the covering gas, the pressure is 0.15MPa, and the flow rate is 80L / min; the online filtration uses a double-stage foam ceramic filter plate with a front 50 mesh and a rear 70 mesh for filtration;

[0060] The liquid flows into the holding furnace through the flow channel and is directly supplied to the casting molding machine for casting. The casting speed is 25 mm / min, the temperature is 720°C, and the cooling water flow rate is 25 m 3 / h, to obtain an ingot;

[0061] The ingot is subjected to T5 heat treatment, and the conditions of the T5 heat treatment are: the furnace temperature is raised to 520°C and maintained for 11 hours, then quickly taken out and quenched to room temperature, then the temperature is raised to 170°C, kept for 8 hours, air-cooled, and aging treatment is completed to obtain a high temperature resistant aluminum alloy.

[0062] Embodiment 3:

[0063] A microalloyed high temperature resistant aluminum alloy is composed of the following components in percentage by mass: Cu: 4.96%, Fe: 1.05%, Ni: 1.57%, Mn: 0.55%, Mg: 0.51%, Ti: 0.2%, Ce: 0.28%, Zr: 0.27%, the total amount of unavoidable impurity elements does not exceed 0.3%, and the balance is Al.

[0064] A method for preparing a microalloyed high temperature resistant aluminum alloy comprises the following steps:

[0065] Mix KCl, MnCl2 and K2CO3 in a mass ratio of 1:3:1, dry at 120°C, calcine at 700°C for 20 minutes, and grind to obtain a refining agent with an average particle size of 1 mm after cooling for later use;

[0066] The pure aluminum ingot is then added into the smelting furnace, and Al-Fe alloy, Al-Mn alloy, Al-Ni alloy and Al-Cu alloy are added in sequence, and smelted at 750°C. After being completely melted, raw materials containing Ti, Mg, Zr and Ce elements are continuously added, and electromagnetic stirring is performed to promote melt flow, so as to obtain a melt with high uniformity;

[0067] The flow rate of the inert gas is controlled to be 45 L / min and the inert gas is used as a carrier, and a refining agent with a mass fraction of 0.1% is introduced for the first refining, and the first refining is kept at 720° C. for 15 minutes, and the composition is sampled and tested, and the alloy composition is adjusted;

[0068] The scum on the surface of the melt was removed, the flow rate of the inert gas was controlled to 45 L / min, and a refining agent with a mass fraction of 0.05% was introduced with the inert gas as a carrier to perform a second refining, and the second refining was kept at 720° C. for 15 min;

[0069] After the second refining is completed, the scum on the surface of the melt is removed again, and then the melt is introduced into the degassing and filtering device for online degassing and online filtering, and the online degassing time is 20 minutes, and the online degassing uses N2 as the covering gas, the pressure is 0.15MPa, and the flow rate is 80L / min; the online filtration uses a two-stage foam ceramic filter plate with a front mesh of 60 mesh and a rear mesh of 80 mesh for filtration;

[0070] The liquid flows into the holding furnace through the flow channel and is directly supplied to the casting molding machine for casting. The casting speed is 25 mm / min, the temperature is 730°C, and the cooling water flow rate is 30 m 3 / h, to obtain an ingot;

[0071] The ingot is subjected to T5 heat treatment, and the conditions of the T5 heat treatment are: the furnace temperature is raised to 540°C and maintained for 14 hours, then quickly taken out and quenched to room temperature, then the temperature is raised to 180°C, kept for 6 hours, air-cooled, and aging treatment is completed to obtain a high temperature resistant aluminum alloy.

[0072] Embodiment 4:

[0073] A microalloyed high temperature resistant aluminum alloy is composed of the following components in percentage by mass: Cu: 5.04%, Fe: 1.08%, Ni: 1.6%, Mn: 0.56%, Mg: 0.55%, Ti: 0.2%, Ce: 0.2%, Zr: 0.3%, the total amount of unavoidable impurity elements does not exceed 0.3%, and the balance is Al.

[0074] A method for preparing a microalloyed high temperature resistant aluminum alloy comprises the following steps:

[0075] Mix KCl, MnCl2 and K2CO3 in a mass ratio of 2:1:2, dry at 120°C, calcine at 650°C for 20 minutes, and grind to obtain a refining agent with an average particle size of 1 mm after cooling for later use;

[0076] The pure aluminum ingot is then added into the smelting furnace, and Al-Fe alloy, Al-Mn alloy, Al-Ni alloy and Al-Cu alloy are added in sequence, and smelted at 750°C. After being completely melted, raw materials containing Ti, Mg, Zr and Ce elements are continuously added, and electromagnetic stirring is performed to promote melt flow, so as to obtain a melt with high uniformity;

[0077] The flow rate of the inert gas is controlled to be 45 L / min and the inert gas is used as a carrier, and a refining agent with a mass fraction of 0.13% is introduced for the first refining, and the first refining is kept at 720° C. for 20 minutes, and the composition is sampled and tested, and the alloy composition is adjusted;

[0078] The scum on the surface of the melt was removed, the flow rate of the inert gas was controlled to 45 L / min, and a refining agent with a mass fraction of 0.06% was introduced with the inert gas as a carrier to perform a second refining, and the second refining was kept at 720° C. for 20 min;

[0079] After the second refining is completed, the scum on the surface of the melt is removed again, and then the melt is introduced into the degassing and filtering device for online degassing and online filtration, and the online degassing time is 20 minutes, and the online degassing uses N2 as the covering gas, the pressure is 0.15MPa, and the flow rate is 80L / min; the online filtration uses a two-stage foam ceramic filter plate with a front 40 mesh and a rear 80 mesh for filtration;

[0080] The liquid flows into the holding furnace through the flow channel and is directly supplied to the casting molding machine for casting. The casting speed is 25 mm / min, the temperature is 730°C, and the cooling water flow rate is 30 m 3 / h, to obtain an ingot;

[0081] The ingot is subjected to T5 heat treatment, and the conditions of the T5 heat treatment are: the furnace temperature is raised to 520°C and maintained for 10 hours, then quickly taken out and quenched to room temperature, and then the temperature is raised to 150°C, kept for 7 hours, air-cooled, and aging treatment is completed to obtain a high temperature resistant aluminum alloy.

[0082] Comparative Example 1:

[0083] Compared with Example 1, Comparative Example 1 does not add Ce, and the rest is the same as Example 1.

[0084] Comparative Example 2:

[0085] Compared with Example 2, Comparative Example 2 has the following characteristics: the addition amount of Mn in Comparative Example 2 is 0.2%, the addition amount of Mg is 0.25%, and the others are the same as Example 2.

[0086] Comparative Example 3:

[0087] Compared with Example 3, Comparative Example 3 does not add Mn, and the rest is the same as Example 3.

[0088] Comparative Example 4:

[0089] Compared with Example 4, Comparative Example 4 has the following characteristics: the amount of Fe added in Comparative Example 4 is 0.5%, the amount of Ni added in Comparative Example 4 is 1.6%, and the others are the same as Example 4.

[0090] The aluminum alloys of Examples 1 to 4 and Comparative Examples 1 to 4 were made into standard tensile specimens, and high temperature tensile tests were performed at 300°C, 350°C and 400°C on a microcomputer-controlled electronic universal testing machine. The loading rate was 1 mm / min, and at least three groups of experiments were performed for each group of alloys. The test results are shown in Tables 1 to 3.

[0091] Table 1: Mechanical properties at 300℃

[0092]

[0093]

[0094] Table 2: Mechanical properties at 350℃

[0095]

[0096] Table 3: Mechanical properties at 400℃

[0097]

[0098] From the data analysis of Tables 1 to 3, it can be seen that under the same conditions, the aluminum alloy material designed by the present invention has better mechanical properties after casting and T5 heat treatment, and its high temperature strength is significantly better than that of existing materials. The tensile strength of the alloy prepared in Example 1 at 300°C, 350°C and 400°C is increased by 23.5%, 16.2% and 19.2% respectively compared with the comparative example 1 without Ce addition. It can be seen from Example 2 and Comparative Example 2 that when the content of Mn and Mg is increased from 0.25% and 0.2% to 0.53% and 0.48%, the high temperature strength of the alloy at 300°C, 350°C and 400°C is increased by 17.2%, 20.0% and 21.4%, respectively, indicating that appropriately increasing the content of Mn and Mg is helpful to improve the performance of the alloy; from the high temperature performance of Example 3 and Comparative Example 3, it can be seen that adding Mn is beneficial to improving the high temperature performance of the alloy. Compared with the alloy without adding Mn, the tensile strength of the alloy in Example 3 at 300°C, 350°C and 400°C is increased by 15.5%, 24.9% and 18.1%, respectively, and the high temperature strength is significantly improved. It can be seen from Comparative Example 4 and Comparative Example 4 that increasing the Fe content is beneficial to improving the high temperature performance of the alloy. When the Fe content is increased from 0.4% to 1.08%, the tensile strength of the alloy at 300°C, 350°C and 400°C is increased by 30.3%, 21.6% and 26.3%, respectively. Therefore, the high temperature resistant aluminum alloy material prepared based on multi-element microalloying fully meets the requirements of high strength and high toughness of materials in the aerospace and automotive fields, and can be used in the manufacture of aircraft structural components and automobile engine cylinder blocks.

[0099] In addition, in order to study the effect of the refining agent on the high temperature strength of the aluminum alloy, comparative examples 5 to 8 were prepared. Compared with Example 4, comparative examples 5 to 8 differed only in the composition and proportion of the refining agent, and the others were the same as Example 4. The composition and proportion of the refining agent of comparative examples 5 to 8 are shown in Table 4, and the mechanical properties test results at 400°C are shown in Table 4.

[0100] Table 4: Refining agent and mechanical properties test results

[0101]

[0102] From the data analysis of Table 4, it can be seen that in this application, by optimizing the composition and ratio of the refining agent, it is helpful to promote the high temperature resistant mechanical properties of the aluminum alloy.

[0103] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0104] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a microalloyed high temperature resistant aluminum alloy, characterized in that: The preparation method The following steps are involved: The pure aluminum ingot is then added into the smelting furnace, and Al-Fe alloy, Al-Mn alloy, Al-Ni alloy and Al-Cu alloy are added in sequence, and the raw materials containing Ti element, Mg element, Zr element and Ce element are added after being completely melted, and electromagnetic stirring is used to promote the flow of the melt to obtain a melt with high uniformity; Using an inert gas as a carrier, introducing a refining agent with a mass fraction of 0.05% to 0.15% for the first refining, and the first refining is kept at 720° C. to 750° C. for 10 min to 30 min, sampling and testing the composition, and adjusting the alloy composition; The scum on the surface of the melt is removed, and a refining agent with a mass fraction of 0.03% to 0.13% is introduced with an inert gas as a carrier to perform a second refining, and the second refining is kept at 720° C. to 750° C. for 10 min to 30 min; After the second refining is completed, the scum on the surface of the melt is removed again, and then the melt is introduced into the degassing and filtering device for online degassing and online filtering, and flows into the holding furnace through the flow channel to directly supply the casting molding machine for casting processing to obtain an ingot; The ingot is subjected to T5 heat treatment, and the conditions of the T5 heat treatment are: raising the furnace temperature to 500°C to 550°C and maintaining it for 10h to 15h, then quickly taking it out and quenching it to room temperature, then raising the temperature to 150°C to 200°C, maintaining it for 6h to 10h, air cooling, completing aging treatment, and obtaining a high temperature resistant aluminum alloy.

2. The preparation method according to claim 1, characterized in that: The high temperature resistant aluminum alloy comprises the following components in percentage by mass: Composition: Cu: 4.7% ~ 5.04%, Fe: 0.98% ~ 1.08%, Ni: 1.45% ~ 1.6%, Mn: 0.51% ~ 0.56%, Mg: 0.45% ~ 0.55%, Ti: 0.18% ~ 0.2%, Ce: 0.2% ~ 0.32%, Zr: 0.05% ~ 0.3%, the total amount of unavoidable impurity elements does not exceed 0.3%, and the balance is Al.

3. The preparation method according to claim 1, characterized in that: The temperature of the smelting treatment is 750-800°C.

4. The preparation method according to claim 1, characterized in that: The average particle size of the refining agent is 0.5 mm to 3 mm.

5. The preparation method according to claim 4, characterized in that: The refining agent is composed of KCl, MnCl2 and K2CO3 in a mass ratio of (1-3):(1-5):(1-2).

6. The preparation method according to claim 5, characterized in that: The preparation method of the refining agent is as follows: KCl, MnCl2 and K2CO3 are mixed, dried at 100°C to 120°C, calcined at 500°C to 800°C for 20min to 30min, and then pulverized after cooling.

7. The preparation method according to claim 1, characterized in that: During the first refining and the second refining, the flow rate of the inert gas is controlled to be 45 L / min to 60 L / min.

8. The preparation method according to claim 1, characterized in that: The online degassing time is 10 min to 40 min, and the online degassing uses N2 as the covering gas, the pressure is 0.15 MPa to 0.35 MPa, and the flow rate is 50 L / min to 120 L / min.

9. The preparation method according to claim 8, characterized in that: The online filtration adopts a double-stage foam ceramic filter plate with a front mesh of 40 to 60 meshes and a rear mesh of 60 to 80 meshes for filtration.

10. The preparation method according to claim 1, characterized in that: The casting process speed is 15mm / min to 30mm / min, the temperature is 720℃ to 750℃, and the flow rate of cooling water is 25m 3 / h~30m 3 / h.

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