A high-performance aluminum rod for manufacturing a die-cast cylinder head cover and a production method thereof

Abstract

The present invention discloses a high-performance aluminum rod for manufacturing a die-cast cylinder head cover and a production method thereof. The high-performance aluminum rod comprises the following raw materials in mass percentage: Mg 0.5-0.8%, Si 2.5-3.9%, Mn 0.2-0.6%, Cu 0.1-0.5%, Ti 0.1-0.3%, Fe 0.2-0.5%, Ni 0.01-0.0.02%, Sn 0.01-0.03%, 0.02-0.06% of other alloying elements, with the balance being Al; the other alloying elements include Cd, Cr, Sr, and a rare earth element combination. Adding Cd, Cr, Sr, and a rare earth element combination to the aluminum rod raw material of the present invention can synergistically improve mechanical properties and corrosion resistance, wherein the tensile strength is above 396.9 MPa, the yield strength is above 375.2 MPa, the elongation at break is above 14.7%, and the salt spray corrosion rate is below 0.0165 g / m 2 d or less.

Description

Technical Field

[0001] The invention belongs to the field of aluminum alloy materials, and particularly relates to a high-performance aluminum rod for manufacturing a die-cast cylinder head cover and a production method thereof. Background Art

[0002] Aluminum alloy is a multi-performance material that facilitates lightweighting. By adjusting the composition of various elements, aluminum alloys can achieve diverse properties, including high thermal conductivity, high electrical conductivity, high yield strength, high tensile strength, corrosion resistance, high toughness, and high hardness. They are widely used in communications, automotive, transportation, power, aerospace, and other fields. With the continuous advancement of science and technology, the material requirements for high-tech applications are becoming increasingly stringent. Previously, a single performance characteristic was no longer sufficient to meet the demands of technological development. Today's aluminum alloys not only have strict requirements for their basic chemical composition but also must meet various specialized requirements, balancing multiple performance characteristics. Some of these properties were even previously considered to be in conflict with each other. The objective need now and for the foreseeable future is to rationally blend and optimize the various components and properties of the material, tailored to the specific needs of each material, to create a new aluminum alloy that meets its specific requirements.

[0003] ADC12, a Japanese aluminum grade also known as No. 12 aluminum, is an Al-Si-Cu alloy suitable for die-casting applications such as cylinder head covers, sensor brackets, and cylinder blocks. ADC12 is commonly used in traditional die-casting of thin-walled parts. However, due to its high copper content, the material's inherent corrosion resistance is poor, limiting its service life. Furthermore, ADC12's performance, particularly its strength, no longer meets the evolving technical requirements of high-tech products.

[0004] Patent CN202011619797.5 discloses a method for preparing a high-strength, corrosion-resistant aluminum alloy. The method involves melting raw materials to obtain a premelt; adding a refining agent to the premelt to obtain a refined material; and filtering the refined material through a filter box before casting to obtain an aluminum rod. While the aluminum alloy produced in this invention possesses a certain strength, its corrosion resistance is insufficient in certain specialized applications, making it insufficient for high-performance aluminum alloys. Therefore, a high-performance aluminum rod suitable for manufacturing die-cast cylinder head covers is desired. Summary of the Invention

[0005] The present invention provides a high-performance aluminum rod for manufacturing a die-cast cylinder head cover and a production method thereof, so as to improve the strength and corrosion resistance of the high-performance aluminum.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A high-performance aluminum rod for manufacturing a die-cast cylinder head cover, the aluminum rod comprising the following raw materials, measured by mass percentage: 0.5-0.8% Mg, 2.5-3.9% Si, 0.2-0.6% Mn, 0.1-0.5% Cu, 0.1-0.3% Ti, 0.2-0.5% Fe, 0.01-0.0.02% Ni, 0.01-0.03% Sn, 0.02-0.06% other alloying elements, the balance being Al and unremovable impurity elements;

[0008] Other alloying elements include Cd, Cr, Sr, rare earth element combination, and 100×n Cd +200×n Cr =500×n Sr +0.2; 100×(n Cd +n Cr +n Sr )=(100×n 稀土元素组合 +0.5) 2 +0.2; the rare earth element combination includes: Y, La, Er, wherein the usage ratio of Y, La, Er is (0.5-0.9): (0.6-1.2): (0.2-0.5).

[0009] Preferably, in parts by weight, the following raw materials are included: the aluminum rod includes the following raw materials in mass percentage: Mg0.6%, Si3.3%, Mn0.4%, Cu0.3%, Ti0.2%, Fe0.3%, Ni0.015%, Sn0.02%, 0.02-0.06% of other alloying elements, and the balance is Al and non-removable impurity elements.

[0010] Preferably, the usage ratio of Y, La and Er is 0.7:0.9:0.4.

[0011] Preferably, the content of a single element in the non-removable impurities is not greater than 0.01%, and the total content of the non-removable impurities is not greater than 0.08%.

[0012] The present invention also provides a method for producing a high-performance aluminum rod for manufacturing a die-cast cylinder head cover, comprising the following steps:

[0013] S1. Putting aluminum raw material and master alloy raw material into a melting furnace for melting to obtain alloy aluminum liquid;

[0014] S2. Add a refining agent to the alloy aluminum liquid, use a refiner to charge the refining agent into the alloy aluminum liquid along with argon gas, refine the alloy aluminum liquid, adjust the temperature of the alloy aluminum liquid to 810-850° C., and refine for 20-30 minutes; degas, let it stand for 1-2 hours, and continue refining for 10-20 minutes to obtain a refined material;

[0015] S3. The refined material is passed through a launder, an online degassing device, a filter plate, a diverter plate and cast to obtain an aluminum rod.

[0016] Preferably, the melting in step S1 is to raise the temperature of the melting furnace to 840-860° C., stir the alloy evenly and keep it warm for 2-4 hours, then lower the temperature of the melting furnace to 720-750° C. and let it stand for 10-30 minutes.

[0017] Preferably, the mass ratio of the refining agent to the aluminum content in the alloy aluminum liquid in step S2 is 0.6-1:1000; the argon flow rate is 1.0-1.85m 3 / h.

[0018] Preferably, the refining agent in step S2 is 30-40% alumina, 10-20% sodium carbonate, 20-30% sodium chloride, 2-3% hexachloroethane, 0.01-0.12% rare earth, and the balance is potassium chloride.

[0019] Preferably, in step S3, the alloy aluminum liquid is flowed into the launder to perform online refinement treatment on the alloy aluminum liquid; the alloy aluminum liquid after refinement treatment by the online degassing equipment is degassed online, and the alloy aluminum liquid after online degassing passes through the filter plate to filter and remove slag from the alloy aluminum liquid; the alloy aluminum liquid after deslagging is introduced into the mold through the diverter plate, continuously poured and assisted by electromagnetic stirring, and cooled to obtain the aluminum rod.

[0020] Preferably, in step S3, the casting temperature is 700-750°C, the homogenization treatment is performed at 500-540°C for 2-3h, and the aluminum rod is extruded by an extruder, wherein the hot extrusion temperature is 520-540°C and the extrusion speed is 4-6m / min, and the rod is water-cooled to room temperature to obtain a high-performance aluminum rod.

[0021] The present invention has the following beneficial effects:

[0022] (1) The raw materials for preparing the high-performance aluminum rod for manufacturing the die-cast cylinder head cover of the present invention lack Cd, Cr, Sr, and rare earth element combinations, which have a great impact on the mechanical properties and corrosion resistance of the high-performance aluminum rod for manufacturing the die-cast cylinder head cover. Adding Cd, Cr, Sr, and rare earth element combinations to the raw materials for preparing the aluminum rod can significantly improve the mechanical properties and corrosion resistance of the aluminum rod.

[0023] (2) The combination of Cd, Cr, Sr and rare earth elements plays a synergistic role in the preparation of high-performance aluminum rods for manufacturing die-cast cylinder head covers, and can synergistically improve the mechanical properties and corrosion resistance of high-performance aluminum rods for manufacturing die-cast cylinder head covers, which may be:

[0024] 1) Cadmium (Cd) can be incorporated into numerous alloys exhibiting high tensile strength and wear resistance. Cd significantly enhances nucleation capacity, leading to the formation of numerous nanoscale α-Al(Mn,Fe)Si dispersed phases. Peak microhardness is achieved at 450°C, where the amount of α dispersed phase in the Cd-added alloy is twice that of the un-Cd-added alloy. Consequently, the addition of Cd can increase yield strength by 25%. Cd addition shifts the nucleation pattern of the α-Al(Mn,Fe)Si dispersed phase from heterogeneous to homogeneous nucleation. During heating, Cd-rich nanoparticles undergo a phase transformation, resulting in the formation of ultrafine Cd-rich nanoparticles at temperatures between 150 and 250°C, which exist as metallic phases such as Al3Cd or Al4Cd. The significant dispersion strengthening of the Al-Cd precipitates during heating improves the mechanical properties of the aluminum rod.

[0025] 2) The addition of chromium (Cr) can significantly improve the corrosion resistance of aluminum alloys. Aluminum itself has good corrosion resistance, but it is still prone to corrosion when exposed to harsh environmental conditions (such as acidic or alkaline environments). The addition of chromium can form a dense oxide film, which effectively prevents corrosion of aluminum alloys. This is because the chromium oxide film formed by the reaction of chromium with oxygen has high stability and corrosion resistance, which can prevent foreign substances from further corroding the aluminum alloy, thereby extending the service life of the material. At the same time, the addition of chromium can improve the strength and hardness of aluminum alloys. Aluminum alloys themselves have relatively low strength and hardness, but the addition of chromium can form some strengthening phases, such as Al-Cr phases. The presence of these phases can hinder grain boundary slip and dislocation movement, thereby improving the strength and hardness of the alloy. In addition, chromium can also promote the formation of finer precipitates in the alloy, further increasing the strength and hardness of the material.

[0026] 3) Strontium (Sr) can be adsorbed and accumulated on the surface of the Si phase, thereby inhibiting the nucleation and growth of the Si phase. Sr can also cause stacking faults on the Si phase surface, increasing the undercooling required for Si phase growth. Furthermore, when Sr and rare earth elements are mixed into the alloy, the rare earth elements accelerate the diffusion of Sr in the melt, causing more Sr to accumulate on the surface of the Si phase, enhancing the modification effect of the Si phase. Therefore, adding an appropriate amount of strontium to aluminum alloys can effectively improve the strength and hardness of aluminum alloys. Strontium can replace aluminum and form a uniform solid solution, reducing the grain size of the aluminum alloy and enhancing the strengthening effect. The yield strength, tensile strength, and hardness of the aluminum alloy are all increased. The presence of strontium in aluminum alloys can improve the corrosion resistance of aluminum alloys, making them particularly suitable for applications in certain specific fields.

[0027] 4) The rare earth element combination (Y, La, Er) La and Sr form a composite modifier, Al-6Sr-7La, in aluminum alloys. This not only reduces the secondary dendrite arm spacing of α-Al, but also transforms the eutectic Si morphology from needles to fibers or particles, significantly improving the alloy's mechanical properties. Y and Sr can significantly reduce the hydrogen content of the melt, which gradually decreases to a stable state with increasing addition. The composite modifier formed by Y and Sr in aluminum alloys completes the Si phase modification, transforming the eutectic Si phase from short rods or fibers to particles, and refining the dendritic α-Al structure into axially distributed, uniformly distributed, and densely packed crystals. Er has a microalloying effect in aluminum alloys. Er forms a nanoscale Ll2 structure Al3Er phase in the microalloyed aluminum alloy, which can maintain coherence with the matrix. Adding Er to the aluminum alloy at the same time can form a fine dispersed phase with a core-shell structure. These precipitated phases with good thermal stability can refine the grain size, reduce segregation, make the microstructure uniform, increase strength, hinder recrystallization, and thus improve the comprehensive performance of the aluminum alloy.

[0028] The present invention prepares aluminum rods by combining Cd, Cr, Sr and rare earth elements, thereby synergistically improving the mechanical properties and corrosion resistance of high-performance aluminum rods used for manufacturing die-cast cylinder head covers.

[0029] (3) The aluminum alloy prepared by the present invention has a tensile strength of more than 396.9 MPa, a yield strength of more than 375.2 MPa, an elongation at break of more than 14.7%, and a salt spray corrosion rate of 0.0165 g / m 2 ·d or less, it can be seen that the mechanical properties and corrosion resistance are good.

[0030] (4) The mechanical properties and corrosion resistance of the aluminum alloy produced by the present invention are significantly better than those of the aluminum alloy produced by the prior art, and can meet the requirements for application in the manufacture of die-cast cylinder head covers. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a diagram of a die-cast cylinder head cover manufactured using the aluminum rod prepared in Example 3. DETAILED DESCRIPTION

[0032] In order to facilitate a better understanding of the present invention, the following examples are provided for illustration. These examples belong to the protection scope of the present invention, but do not limit the protection scope of the present invention.

[0033] In an embodiment, the high-performance aluminum rod used to manufacture the die-cast cylinder head cover includes the following raw materials in mass percentage: Mg0.5-0.8%, Si2.5-3.9%, Mn0.2-0.6%, Cu0.1-0.5%, Ti0.1-0.3%, Fe0.2-0.5%, Ni0.01-0.0.02%, Sn0.01-0.03%, 0.02-0.06% of other alloying elements, and the balance is Al and non-removable impurity elements; the content of a single element in the non-removable impurities is not more than 0.01%, and the total content of the non-removable impurities is not more than 0.08%.

[0034] Other alloying elements include Cd, Cr, Sr, rare earth element combination, and 100×n Cd +200×n Cr =500×n Sr +0.2; 100×(n Cd +n Cr +n Sr )=(100×n 稀土元素组合 +0.5) 2 +0.2; the rare earth element combination includes: Y, La, Er, wherein the usage ratio of Y, La, Er is (0.5-0.9): (0.6-1.2): (0.2-0.5).

[0035] A method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover comprises the following steps:

[0036] S1. Place the aluminum raw material and the master alloy raw material into a melting furnace, raise the temperature of the melting furnace to 840-860°C, stir the alloy evenly and keep it warm for 2-4 hours, then lower the temperature of the melting furnace to 720-750°C, let it stand for 10-30 minutes, and obtain alloy aluminum liquid;

[0037] S2. Add a refining agent to the alloy aluminum liquid. The refining agent is 30-40% alumina, 10-20% sodium carbonate, 20-30% sodium chloride, 2-3% hexachloroethane, 0.01-0.12% rare earth, and the balance is potassium chloride. The mass ratio of the refining agent to the aluminum content in the alloy aluminum liquid is 0.6-1:1000. Use a refining machine to fill the refining agent into the alloy aluminum liquid along with argon gas to refine the alloy aluminum liquid. The argon gas flow rate is 1.0-1.85m 3 / h; adjust the temperature of the alloy aluminum liquid to 810-850℃, and refine for 20-30min; degas, let it stand for 1-2h, and continue refining for 10-20min to obtain refined material;

[0038] S3. The alloy aluminum liquid is flowed into the flow trough for online refinement treatment of the alloy aluminum liquid; the alloy aluminum liquid refined by the online degassing equipment is degassed online, and the alloy aluminum liquid after online degassing passes through the filter plate to filter and remove slag from the alloy aluminum liquid; the alloy aluminum liquid after slag removal is introduced into the mold through the diverter plate, continuously poured and assisted by electromagnetic stirring, the casting temperature is 700-750℃, and homogenized at 500-540℃ for 2-3h, and extruded by the extruder, wherein the hot extrusion temperature is 520-540℃, the extrusion speed is 4-6m / min, and the aluminum rod is obtained by water cooling to room temperature.

[0039] In order to make the disclosure of the present invention more complete, it is described below through more specific embodiments.

[0040] Example 1

[0041] A high-performance aluminum rod for manufacturing a die-cast cylinder head cover. The aluminum rod comprises the following raw materials, measured in percentage by mass: 0.6% Mg, 3.3% Si, 0.2% Mn, 0.5% Cu, 0.1% Ti, 0.5% Fe, 0.0.02% Ni, 0.02% Sn, and 0.047% other alloying elements, with the remainder being Al and unremovable impurity elements; the content of a single element in the unremovable impurities is no more than 0.01%, and the total content of the unremovable impurities is no more than 0.08%.

[0042] Other alloying elements include Cd 0.012%, Cr 0.02%, Sr 0.01%, and rare earth element combination 0.015%; the rare earth element combination includes: Y, La, Er, wherein the usage ratio of Y, La, and Er is 0.8:0.7:0.4.

[0043] A method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover comprises the following steps:

[0044] S1. Place the aluminum raw material and the master alloy raw material into a melting furnace, raise the temperature of the melting furnace to 840°C, stir the alloy evenly and keep it warm for 2 hours, then lower the temperature of the melting furnace to 720°C and let it stand for 22 minutes to obtain alloy aluminum liquid;

[0045] S2. Add a refining agent to the alloy aluminum liquid. The refining agent is 31% aluminum oxide, 12% sodium carbonate, 26% sodium chloride, 3% hexachloroethane, 0.011% rare earth, and the balance is potassium chloride. The mass ratio of the refining agent to the aluminum content in the alloy aluminum liquid is 0.6:1000. Use a refining machine to fill the refining agent into the alloy aluminum liquid along with argon gas to refine the alloy aluminum liquid. The argon gas flow rate is 1.74m 3 / h; adjust the temperature of the alloy aluminum liquid to 810℃ and refine for 30min; degas, let it stand for 1.3h, and continue refining for 12min to obtain refined material;

[0046] S3. The alloy aluminum liquid is flowed into the flow trough for online refinement treatment of the alloy aluminum liquid; the alloy aluminum liquid refined by the online degassing equipment is degassed online, and the alloy aluminum liquid after online degassing passes through the filter plate to filter and remove slag from the alloy aluminum liquid; the alloy aluminum liquid after slag removal is introduced into the mold through the diverter plate, continuously poured and assisted by electromagnetic stirring, the casting temperature is 750℃, and the homogenization treatment is carried out at 530℃ for 2h, and extruded by the extruder, wherein the hot extrusion temperature is 520℃, the extrusion speed is 6m / min, and the aluminum rod is obtained by water cooling to room temperature.

[0047] Example 2

[0048] A high-performance aluminum rod for manufacturing a die-cast cylinder head cover. The aluminum rod comprises the following raw materials, measured in percentage by mass: 0.8% Mg, 3.9% Si, 0.3% Mn, 0.1% Cu, 0.25% Ti, 0.2% Fe, 0.01% Ni, 0.03% Sn, and 0.047% other alloying elements, with the remainder being Al and unremovable impurity elements; the content of a single element in the unremovable impurities is no more than 0.01%, and the total content of the unremovable impurities is no more than 0.08%.

[0049] Other alloying elements include Cd 0.012%, Cr 0.02%, Sr 0.01%, and rare earth element combination 0.015%; the rare earth element combination includes: Y, La, Er, wherein the usage ratio of Y, La, and Er is 0.9:1.2:0.5.

[0050] A method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover comprises the following steps:

[0051] S1. Place the aluminum raw material and the master alloy raw material into a melting furnace, raise the temperature of the melting furnace to 850°C, stir the alloy evenly and keep it warm for 3 hours, then lower the temperature of the melting furnace to 740°C and let it stand for 30 minutes to obtain alloy aluminum liquid;

[0052] S2. Add a refining agent to the alloy aluminum liquid. The refining agent is 35% aluminum oxide, 17% sodium carbonate, 30% sodium chloride, 2% hexachloroethane, 0.12% rare earth, and the balance is potassium chloride. The mass ratio of the refining agent to the aluminum content in the alloy aluminum liquid is 0.9:1000. Use a refining machine to fill the refining agent into the alloy aluminum liquid along with argon gas to refine the alloy aluminum liquid. The argon gas flow rate is 1.85m 3 / h; adjust the temperature of the alloy aluminum liquid to 840°C and refine for 20 minutes; degas, let it stand for 2 hours, and continue refining for 20 minutes to obtain refined material;

[0053] S3. The alloy aluminum liquid is flowed into the flow trough to perform online refinement treatment on the alloy aluminum liquid; the alloy aluminum liquid refined by the online degassing equipment is degassed online, and the alloy aluminum liquid after online degassing passes through the filter plate to filter and remove slag from the alloy aluminum liquid; the alloy aluminum liquid after slag removal is introduced into the mold through the diverter plate, continuously poured and assisted by electromagnetic stirring, the casting temperature is 700℃, and the homogenization treatment is carried out at 540℃ for 2.5h, and extruded by the extruder, wherein the hot extrusion temperature is 530℃, the extrusion speed is 4m / min, and the aluminum rod is obtained by water cooling to room temperature.

[0054] Example 3

[0055] A high-performance aluminum rod for manufacturing a die-cast cylinder head cover. The aluminum rod comprises the following raw materials, measured in percentage by mass: 0.6% Mg, 3.3% Si, 0.4% Mn, 0.3% Cu, 0.2% Ti, 0.3% Fe, 0.015% Ni, 0.02% Sn, and 0.047% other alloying elements, with the remainder being Al and unremovable impurity elements; the content of a single element in the unremovable impurities is no more than 0.01%, and the total content of the unremovable impurities is no more than 0.08%.

[0056] Other alloying elements include Cd 0.012%, Cr 0.02%, Sr 0.01%, and rare earth element combination 0.015%; the rare earth element combination includes: Y, La, Er, wherein the usage ratio of Y, La, and Er is 0.7:0.9:0.4.

[0057] A method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover comprises the following steps:

[0058] S1. Place the aluminum raw material and the master alloy raw material into a melting furnace, raise the temperature of the melting furnace to 850°C, stir the alloy evenly and keep it warm for 3 hours, then lower the temperature of the melting furnace to 730°C and let it stand for 20 minutes to obtain alloy aluminum liquid;

[0059] S2. Add a refining agent to the alloy aluminum liquid. The refining agent is 35% aluminum oxide, 15% sodium carbonate, 25% sodium chloride, 3% hexachloroethane, 0.011% rare earth, and the balance is potassium chloride. The mass ratio of the refining agent to the aluminum content in the alloy aluminum liquid is 0.8:1000. Use a refining machine to fill the refining agent into the alloy aluminum liquid along with argon gas to refine the alloy aluminum liquid. The argon gas flow rate is 1.62m 3 / h; adjust the temperature of the alloy aluminum liquid to 840℃ and refine for 30min; degas, let it stand for 1.5h, and continue refining for 15min to obtain refined material;

[0060] S3. The alloy aluminum liquid is flowed into the launder to perform online refinement treatment on the alloy aluminum liquid; the alloy aluminum liquid after refinement treatment is degassed online by the online degassing equipment, and the alloy aluminum liquid after online degassing passes through the filter plate to filter and remove slag from the alloy aluminum liquid; the alloy aluminum liquid after slag removal is introduced into the mold through the diverter plate, continuously poured and supplemented with electromagnetic stirring, the casting temperature is 710℃, and the homogenization treatment is carried out at 530℃ for 2.5h. The aluminum bar is extruded by the extruder, wherein the hot extrusion temperature is 530℃ and the extrusion speed is 5m / min. The aluminum bar is water-cooled to room temperature to obtain an aluminum rod, and the die-cast cylinder head cover is manufactured using the aluminum rod. Figure 1 shown.

[0061] Example 4

[0062] A high-performance aluminum rod for manufacturing a die-cast cylinder head cover. The aluminum rod comprises the following raw materials, measured in percentage by mass: 0.5% Mg, 2.5% Si, 0.6% Mn, 0.4% Cu, 0.3% Ti, 0.3% Fe, 0.015% Ni, 0.01% Sn, 0.047% other alloying elements, and the balance being Al and unremovable impurity elements; the content of a single element in the unremovable impurities is no more than 0.01%, and the total content of the unremovable impurities is no more than 0.08%.

[0063] Other alloying elements include Cd 0.012%, Cr 0.02%, Sr 0.01%, and rare earth element combination 0.015%; the rare earth element combination includes: Y, La, Er, wherein the usage ratio of Y, La, and Er is 0.5:0.6:0.2.

[0064] A method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover comprises the following steps:

[0065] S1. Place the aluminum raw material and the master alloy raw material into a melting furnace, raise the temperature of the melting furnace to 840-860°C, stir the alloy evenly and keep it warm for 4 hours, then lower the temperature of the melting furnace to 750°C and let it stand for 10 minutes to obtain alloy aluminum liquid;

[0066] S2. Add a refining agent to the alloy aluminum liquid. The refining agent is 40% aluminum oxide, 20% sodium carbonate, 20% sodium chloride, 2.5% hexachloroethane, 0.01% rare earth, and the balance is potassium chloride. The mass ratio of the refining agent to the aluminum content in the alloy aluminum liquid is 1:1000. Use a refining machine to fill the refining agent into the alloy aluminum liquid along with argon gas to refine the alloy aluminum liquid. The argon gas flow rate is 1.0m 3 / h; adjust the temperature of the alloy aluminum liquid to 850℃ and refine for 25min; degas, let it stand for 1h, and continue refining for 10min to obtain refined material;

[0067] S3. The alloy aluminum liquid is flowed into the flow trough to perform online refinement treatment on the alloy aluminum liquid; the alloy aluminum liquid refined by the online degassing equipment is degassed online, and the alloy aluminum liquid after online degassing passes through the filter plate to filter and remove slag from the alloy aluminum liquid; the alloy aluminum liquid after slag removal is introduced into the mold through the diverter plate, continuously poured and assisted by electromagnetic stirring, the casting temperature is 730℃, and the homogenization treatment is carried out at 500℃ for 3h, and extruded by the extruder, wherein the hot extrusion temperature is 540℃, the extrusion speed is 5m / min, and the aluminum rod is obtained by water cooling to room temperature.

[0068] Comparative Example 1

[0069] The production method is basically the same as that of Example 3, except that the raw material for preparing the high-performance aluminum rod used to manufacture the die-cast cylinder head cover lacks Cd, Cr, Sr, and the rare earth element combination.

[0070] Comparative Example 2

[0071] The production method is basically the same as that of Example 3, except that the raw material for preparing the high-performance aluminum rod for manufacturing the die-cast cylinder head cover lacks Cd.

[0072] Comparative Example 3

[0073] The production method is basically the same as that of Example 3, except that the raw material for preparing the high-performance aluminum rod for manufacturing the die-cast cylinder head cover lacks Cr.

[0074] Comparative Example 4

[0075] The production method is basically the same as that of Example 3, except that the raw material for preparing the high-performance aluminum rod for manufacturing the die-cast cylinder head cover lacks Sr.

[0076] Comparative Example 5

[0077] The production method is basically the same as that of Example 3, except that the raw material for preparing the high-performance aluminum rod for manufacturing the die-cast cylinder head cover lacks the rare earth element combination.

[0078] Comparative Example 6

[0079] The aluminum alloy was prepared according to the method of Example 1 disclosed in the patent "A production method of high-strength and corrosion-resistant aluminum alloy (application number: CN202011619797.5)".

[0080] High-performance aluminum bars used in die-cast cylinder head covers, produced in Examples 1-4 and Comparative Examples 1-6, were subjected to room-temperature tensile testing for mechanical properties and corrosion resistance. Salt spray corrosion resistance testing was conducted in accordance with GB / T10125-NSS / AASS / CAS and alternating salt spray test standards. The test medium consisted of a 5% NaCl solution with a pH of 6.5-7.2, and the chamber temperature was controlled at (35±2)°C. Three samples of each alloy were tested repeatedly, and the averaged results were obtained. The results are shown in the table below.

[0081]

[0082]

[0083] It can be seen from the above table:

[0084] (1) As can be seen from the data of Examples 1-4, the aluminum alloy prepared by the present invention has a tensile strength of more than 396.9 MPa, a yield strength of more than 375.2 MPa, an elongation at break of more than 14.7%, and a salt spray corrosion rate of 0.0165 g / m 2 ·d or less, it can be seen that the mechanical properties and corrosion resistance are good.

[0085] (2) It can be seen from the data of Example 3 and Comparative Examples 1-5 that the raw materials for preparing the high-performance aluminum rod for manufacturing the die-cast cylinder head cover lack Cd, Cr, Sr, and the rare earth element combination, which has a great impact on the mechanical properties and corrosion resistance of the high-performance aluminum rod for manufacturing the die-cast cylinder head cover. When Comparative Example 1 lacks Cd, Cr, Sr, and the rare earth element combination, Comparative Examples 2-5 lack one of the Cd, Cr, Sr, and rare earth element combination respectively, and their corrosion resistance and mechanical properties are lower than the mechanical properties and corrosion resistance of Example 3 containing Cd, Cr, Sr, and the rare earth element combination.

[0086] (3) From the data of Example 3 and Comparative Examples 1-5, it can be seen that the combination of Cd, Cr, Sr, and rare earth elements plays a synergistic role in preparing the high-performance aluminum rod for manufacturing the die-cast cylinder head cover, and synergistically improves the mechanical properties and corrosion resistance of the high-performance aluminum rod for manufacturing the die-cast cylinder head cover. This may be:

[0087] 1) Cadmium (Cd) can be incorporated into numerous alloys exhibiting high tensile strength and wear resistance. Cd significantly enhances nucleation capacity, leading to the formation of numerous nanoscale α-Al(Mn,Fe)Si dispersed phases. Peak microhardness is achieved at 450°C, where the amount of α dispersed phase in the Cd-added alloy is twice that of the un-Cd-added alloy. Consequently, the addition of Cd can increase yield strength by 25%. Cd addition shifts the nucleation pattern of the α-Al(Mn,Fe)Si dispersed phase from heterogeneous to homogeneous nucleation. During heating, Cd-rich nanoparticles undergo a phase transformation, resulting in the formation of ultrafine Cd-rich nanoparticles at temperatures between 150 and 250°C, which exist as metallic phases such as Al3Cd or Al4Cd. The significant dispersion strengthening of the Al-Cd precipitates during heating improves the mechanical properties of the aluminum rod.

[0088] 2) The addition of chromium (Cr) can significantly improve the corrosion resistance of aluminum alloys. Aluminum itself has good corrosion resistance, but it is still prone to corrosion when exposed to harsh environmental conditions (such as acidic or alkaline environments). The addition of chromium can form a dense oxide film, which effectively prevents corrosion of aluminum alloys. This is because the chromium oxide film formed by the reaction of chromium with oxygen has high stability and corrosion resistance, which can prevent foreign substances from further corroding the aluminum alloy, thereby extending the service life of the material. At the same time, the addition of chromium can improve the strength and hardness of aluminum alloys. Aluminum alloys themselves have relatively low strength and hardness, but the addition of chromium can form some strengthening phases, such as Al-Cr phases. The presence of these phases can hinder grain boundary slip and dislocation movement, thereby improving the strength and hardness of the alloy. In addition, chromium can also promote the formation of finer precipitates in the alloy, further increasing the strength and hardness of the material.

[0089] 3) Strontium (Sr) can be adsorbed and accumulated on the surface of the Si phase, thereby inhibiting the nucleation and growth of the Si phase. Sr can also cause stacking faults on the Si phase surface, increasing the undercooling required for Si phase growth. Furthermore, when Sr and rare earth elements are mixed into the alloy, the rare earth elements accelerate the diffusion of Sr in the melt, causing more Sr to accumulate on the surface of the Si phase, enhancing the modification effect of the Si phase. Therefore, adding an appropriate amount of strontium to aluminum alloys can effectively improve the strength and hardness of aluminum alloys. Strontium can replace aluminum and form a uniform solid solution, reducing the grain size of the aluminum alloy and enhancing the strengthening effect. The yield strength, tensile strength, and hardness of the aluminum alloy are all increased. The presence of strontium in aluminum alloys can improve the corrosion resistance of aluminum alloys, making them particularly suitable for applications in certain specific fields.

[0090] 4) The rare earth element combination (Y, La, Er) La and Sr form a composite modifier, Al-6Sr-7La, in aluminum alloys. This not only reduces the secondary dendrite arm spacing of α-Al, but also transforms the eutectic Si morphology from needles to fibers or particles, significantly improving the alloy's mechanical properties. Y and Sr can significantly reduce the hydrogen content of the melt, which gradually decreases to a stable state with increasing addition. The composite modifier formed by Y and Sr in aluminum alloys completes the Si phase modification, transforming the eutectic Si phase from short rods or fibers to particles, and refining the dendritic α-Al structure into axially distributed, uniformly distributed, and densely packed crystals. Er has a microalloying effect in aluminum alloys. Er forms a nanoscale Ll2 structure Al3Er phase in the microalloyed aluminum alloy, which can maintain coherence with the matrix. Adding Er to the aluminum alloy at the same time can form a fine dispersed phase with a core-shell structure. These precipitated phases with good thermal stability can refine the grain size, reduce segregation, make the microstructure uniform, increase strength, hinder recrystallization, and thus improve the comprehensive performance of the aluminum alloy.

[0091] The present invention prepares aluminum rods by combining Cd, Cr, Sr and rare earth elements, thereby synergistically improving the mechanical properties and corrosion resistance of high-performance aluminum rods used for manufacturing die-cast cylinder head covers.

[0092] (4) It can be seen from the data of Examples 1-4 and Comparative Example 6 that the mechanical properties and corrosion resistance of the aluminum alloy prepared by the present invention are significantly better than the mechanical properties and corrosion resistance of the aluminum alloy prepared by Comparative Example 6 (prior art).

[0093] The above content cannot be used to determine that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions or substitutions without departing from the concept of the present invention, which should be regarded as falling within the scope of patent protection of the present invention determined by the submitted claims.

Claims

1. A high-performance aluminum bar for manufacturing a die-cast cylinder head cover, characterized in that: The aluminum rod comprises the following raw materials in percentage by mass: Mg 0.5-0.8%, Si 2.5-3.9%, Mn 0.2-0.6%, Cu 0.1-0.5%, Ti 0.1-0.3%, Fe 0.2-0.5%, Ni 0.01-0.0.02%, Sn 0.01-0.03%, 0.02-0.06% of other alloying elements, and the balance is Al and non-removable impurity elements; Other alloying elements include Cd, Cr, Sr, rare earth element combination, and 100×n Cd +200×n Cr =500×n Sr +0.2; 100×(n Cd +n Cr +n Sr )=(100×n 稀土元素组合 +0.5) 2 +0.2; the rare earth element combination includes: Y, La, Er, wherein the usage ratio of Y, La, Er is (0.5-0.9): (0.6-1.2): (0.2-0.5).

2. The high-performance aluminum rod for manufacturing a die-cast cylinder head cover according to claim 1, characterized in that: The aluminum rod comprises the following raw materials in parts by weight: Mg0.6%, Si3.3%, Mn0.4%, Cu0.3%, Ti0.2%, Fe0.3%, Ni0.015%, Sn0.02%, 0.02-0.06% of other alloying elements, and the balance is Al and non-removable impurity elements.

3. The high-performance aluminum rod for manufacturing a die-cast cylinder head cover according to claim 1, characterized in that: The usage ratio of Y, La and Er is 0.7:0.9:0.

4.

4. The high-performance aluminum rod for manufacturing a die-cast cylinder head cover according to any one of claims 1 to 3, characterized in that: The content of a single element in the non-removable impurities is not greater than 0.01%, and the total content of the non-removable impurities is not greater than 0.08%.

5. A method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Putting aluminum raw material and master alloy raw material into a melting furnace for melting to obtain alloy aluminum liquid; S2. Add a refining agent to the alloy aluminum liquid, use a refiner to charge the refining agent into the alloy aluminum liquid along with argon gas, refine the alloy aluminum liquid, adjust the temperature of the alloy aluminum liquid to 810-850° C., and refine for 20-30 minutes; degas, let it stand for 1-2 hours, and continue refining for 10-20 minutes to obtain a refined material; S3. The refined material is passed through a flow trough, an online degassing device, a filter plate, a diverter plate and cast to obtain an aluminum rod.

6. The method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover according to claim 5, characterized in that: The melting in step S1 is to raise the temperature of the melting furnace to 840-860° C., stir the alloy evenly and keep it warm for 2-4 hours, then lower the temperature of the melting furnace to 720-750° C. and let it stand for 10-30 minutes.

7. The method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover according to claim 6, characterized in that: In step S2, the mass ratio of the refining agent to the aluminum content in the alloy aluminum liquid is 0.6-1:1000; the argon flow rate is 1.0-1.85m 3 / h.

8. The method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover according to claim 5, characterized in that: The refining agent in step S2 is 30-40% of aluminum oxide, 10-20% of sodium carbonate, 20-30% of sodium chloride, 2-3% of hexachloroethane, 0.01-0.12% of rare earth, and the balance is potassium chloride.

9. The method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover according to claim 5, characterized in that: In step S3, the alloy aluminum liquid is flowed into the launder to perform online refinement treatment on the alloy aluminum liquid; the alloy aluminum liquid refined by the online degassing equipment is degassed online, and the alloy aluminum liquid after online degassing passes through the filter plate to filter and remove slag from the alloy aluminum liquid; the alloy aluminum liquid after deslagging is introduced into the mold through the diverter plate, continuously poured and assisted by electromagnetic stirring, and cooled to obtain the aluminum rod.

10. The method for producing a high-performance aluminum bar for manufacturing a die-cast cylinder head cover according to claim 5, characterized in that: In step S3, the casting temperature is 700-750° C., the homogenization treatment is carried out at 500-540° C. for 2-3 hours, and the aluminum rod is extruded by an extruder, wherein the hot extrusion temperature is 520-540° C. and the extrusion speed is 4-6 m / min. The rod is then water-cooled to room temperature to obtain a high-performance aluminum rod.

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