Refining agent for aluminum alloy as well as preparation method and application of refining agent

Abstract

The invention relates to a refiner for aluminum alloy and a preparation method and application thereof, and relates to the field of metal materials. Comprising the following steps: (1) melting a part of regenerated aluminum ingots to obtain molten aluminum, adding uniformly mixed K2NbF7 and KBF4 salts into the molten aluminum in batches, and carrying out stirring reaction under the condition of controlling the temperature to be stable; after the reaction, adding the residual regenerated aluminum ingot, and continuing the reaction until the reaction is complete; and (2) the aluminum alloy liquid obtained after reaction is subjected to refining treatment, the refined aluminum alloy liquid is treated, and the rod-shaped refiner is obtained. The refiner is relatively low in cooling speed sensitivity and good in grain refining effect, the mechanical property of aluminum alloy can be improved, the poisoning effect of high-Si-series cast aluminum alloy is greatly reduced, and the refiner can be applied to preparation of automobile parts such as steering knuckles, automobile hubs and piston alloy in the industry.

Description

Technical Field

[0001] The invention relates to the field of metal materials, and in particular to a refiner for aluminum alloys, a preparation method and an application thereof. Background Art

[0002] Aluminum alloys are widely used in today's industrial fields, especially in aerospace, automobile and other fields, due to their advantages such as low density, high specific strength, good corrosion resistance and easy processing. Aluminum alloys are prone to produce coarse twin structures during the casting process, affecting the microstructure and mechanical properties of aluminum alloys. Grain refinement can improve the microstructure of aluminum alloys, reduce pores and defects, and according to the traditional Hall-Page formula, it can also be obtained that grain refinement can improve the mechanical properties of aluminum alloys. Grain refinement can be mainly divided into two categories: physical refinement and chemical refinement. The physical refinement method includes changing casting parameters and processes, applying physical fields, and ultrasonically treating the melt. The chemical refinement method mainly includes adding refiners or modifiers. The refiners mainly increase the solid-liquid supercooling and introduce heterogeneous nucleation particles to increase nucleation points. Adding modifiers can change the growth mode of crystals and achieve good modification effects and grain refinement effects.

[0003] Adding a refiner to an aluminum alloy can bring about a good grain refining effect, and change its own state without introducing other impurities, becoming a commonly used means of grain refining in the industrial field. Refiners have developed from traditional salt refiners to the more mature rod-shaped refiner alloys that are now used. The Al5TiB series refiners are the most widely used commercial aluminum alloy refiners, but the Al5TiB series refiners have a "poisoning" problem in the cast Al-Si series aluminum alloys, that is, the refinement effect is weakened in high-Si aluminum alloys, which has become an unresolved problem in the industry. Therefore, the industry has developed a new type of Nb-containing refiner based on the research on the refinement effect of solute elements on aluminum alloys. At the same time, combined with the Al5TiB series refiners, the generated TiB2 particles can assist in providing nucleation points for the heterogeneous nucleation of aluminum alloys. In view of this, the present invention provides a refiner for aluminum alloys, a preparation method and an application thereof. Summary of the invention

[0004] Due to the large relative atomic mass of the Nb element, the second phase particle sedimentation phenomenon is prone to occur when preparing the AlxNbyB series refiners through the Al-Nb alloy reaction, resulting in a low refiner yield and thus a poor refinement effect. However, the production cost of the AlxNbyB series refiners prepared by Nb powder is too high, and pollution is prone to occur during the preparation of the refiners, and volatilization problems are caused by excessively high temperatures. The present invention provides a refiner for aluminum alloys, a preparation method thereof, and an application thereof.

[0005] The technical solution of the present invention to solve the above technical problems is as follows:

[0006] In a first aspect, a method for preparing a refiner for aluminum alloy is provided, the method for preparing a refiner for aluminum alloy comprising the following steps:

[0007] (1) melting a portion of the recycled aluminum ingots to obtain liquid aluminum, adding evenly mixed K2NbF7 and KBF4 salts to the liquid aluminum in batches, stirring and reacting under temperature control; after a period of reaction, adding the remaining recycled aluminum ingots, and continuing to stir until the reaction is complete to obtain a reacted aluminum alloy liquid;

[0008] (2) refining the aluminum alloy liquid after the reaction to obtain a refined aluminum alloy liquid; and continuously casting and rolling the refined aluminum alloy liquid to obtain a rod-shaped refiner alloy.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, the method for preparing the refiner for aluminum alloy further comprises the following steps: pretreatment and weighing of AlxNbyB refiner alloy raw materials; specifically as follows:

[0011] K2NbF7 is used as the Nb source of the refiner alloy, KBF4 is used as the B source, and recycled aluminum ingots are used as the aluminum source; the proportions are made according to the following ratios (mass percentage): K2NbF7 accounts for about 60% to 66% (purity>99.8%); KBF4 accounts for about 10% to 15% (purity>99.5%); recycled aluminum ingots account for about 20% to 25% (purity>99.5%); the accuracy is controlled at ±0.5%; pretreatment of pure aluminum and cast aluminum alloy raw materials: remove stains on the surface of the alloy and perform drying treatment.

[0012] Furthermore, the preparation method of the refiner for aluminum alloy comprises the following specific steps:

[0013] (1) Melting part of the recycled aluminum ingots at 700°C to 750°C to obtain liquid aluminum, adding evenly mixed K2NbF7 and KBF4 salts to the liquid aluminum in at least two batches, reacting under stirring, the reaction temperature is maintained at 730°C ± 50°C, the first stirring time is 3min to 5min, the stirring interval time is 10min to 15min, and the stirring speed is 200r / min to 400r / min; then adding the remaining recycled aluminum ingots, continuing to react under stirring until the reaction is complete, the reaction temperature is maintained at 730°C ± 50°C, the stirring time is 5min to 8min, the stirring interval time is 10min to 20min, and the stirring speed is 400r / min to 600r / min, to obtain a reacted aluminum alloy liquid; wherein the reaction time of each step is determined according to the specific situation.

[0014] (2) A refining agent is added to the aluminum alloy liquid after the reaction for refining treatment and high-purity argon gas is introduced (argon purity> 99.99%, argon flow rate is 5m / s within 20s to 30s after the valve is opened) 3 / s~8m 3 / s, then the flow rate is controlled at 0.5m 3 / s~1m 3 / s, the degassing time is 8min~10min. ) is degassed, and the stirring rate of the degassing rod during the degassing process is 400r / min~600r / min to obtain a refined aluminum alloy liquid; after the refining treatment, the scum on the surface of the aluminum liquid is removed, and after the surface slag removal treatment, the refined aluminum alloy liquid is continuously cast and continuously rolled to obtain a rod-shaped refiner alloy.

[0015] Among them, the refining agent is purchased through commercial channels; the components of the refining agent used are three or more of NaCl, KCl, Na3AlF6, CaF2, and MgCl2.

[0016] Further, when the evenly mixed K2NbF7 and KBF4 salts are added in two batches, the weight ratio of the first batch added to the evenly mixed K2NbF7 and KBF4 salts is 60% to 75%, and the weight ratio of the second batch added to the evenly mixed K2NbF7 and KBF4 salts is 25% to 40%.

[0017] Furthermore, the stirring method in step (1) adopts electromagnetic stirring, and the magnetic field intensity of the electromagnetic stirring is 4T to 6T.

[0018] Furthermore, the mass ratio of the recycled aluminum ingot, the K2NbF7 and the KBF4 is 20-25:60-66:10-15. That is, the mass content of the recycled aluminum ingot is 20%-25% (purity>99.5%), the mass content of the K2NbF7 is 60%-66% (purity>99.8%), and the mass content of the KBF4 is 10%-15% (purity>99.5%). Among them, the Nb recovery rate of the AlxNbyB refiner alloy is not less than 60%, and the B recovery rate is not less than 50%. 1%-2% of the recycled aluminum ingot is additionally added as a burnout compensation.

[0019] In a second aspect, a refiner for aluminum alloy is provided, wherein the refiner for aluminum alloy is prepared by the preparation method.

[0020] Furthermore, the refiner is AlxNbyB, 1≤x≤5, 1≤x / y≤10; wherein x and y are mass percentages, 1≤x≤5, 1≤x / y≤10, the sum of the mass percentages of the three elements Al, Nb and B is 100%, and the purity of the refiner AlxNbyB is greater than 99.5%;

[0021] The effective nucleation phases of the refiner are Al3Nb, NbB2, and Al3Nb-NbB2 composite particles, the Al3Nb particles have a size range of 2μm to 15μm; the NbB2 particles have a second phase particle size range of 0.5μm to 3μm, and the second phase particles of the microstructure of the refiner are evenly distributed.

[0022] Further, the diameter of the refiner is

[0023] In a third aspect, a refiner for aluminum alloy is used in the preparation of pure aluminum, Al-Si series or A356 series cast aluminum alloy, wherein the Al-Si series has a Si content of ≥7% (mass fraction).

[0024] Further, the application of AlxNbyB refiner in pure aluminum alloy includes the following preparation method:

[0025] (1) Weigh the raw materials according to the experimental ratio, including recycled aluminum ingots and AlxNbyB refiner, with an accuracy of 0.1g, and provide 1% to 2% of recycled aluminum ingots as burn-off compensation;

[0026] (2) The weighed recycled aluminum ingots are heated and melted at 700°C to 750°C, and an appropriate amount of AlxNbyB refiner alloy is added after melting. After the AlxNbyB refiner alloy is completely melted, stirring is performed, and the magnetic field strength is 4T to 6T, the stirring time is 5min to 10min, and the stirring rate is about 200r / min. After the stirring is completed, an appropriate amount of refining agent is added for refining treatment, and high-purity argon gas (purity>99.99) is introduced to degas the melt. During the degassing process, the aluminum alloy melt is stirred with a stirring head at a stirring rate of about 400r / min. After degassing, the slag on the surface of the aluminum liquid is removed, and the aluminum liquid is cast at about 710°C and cooled to room temperature to finally obtain a refined pure aluminum series alloy.

[0027] Further, the application of AlxNbyB refiner in Al-Si series aluminum alloys includes the following preparation method:

[0028] (1) Weighing the raw materials according to the experimental ratio, including recycled aluminum ingots, Si raw materials and AlxNbyB refiner, with an accuracy of 0.1g, and providing an additional 1% to 2% of recycled aluminum ingots as burn-off compensation;

[0029] (2) The weighed recycled aluminum ingot is heated and melted at 700°C to 750°C, and then an appropriate amount of Si raw material (purity>99.5) is added. After the Si raw material is melted, an appropriate amount of refiner alloy is added. After the AlxNbyB refiner alloy is completely melted, electromagnetic stirring is performed. The stirring time is 5min to 10min and the stirring rate is about 200r / min. After the stirring is completed, an appropriate amount of refining agent is added for refining treatment. High-purity argon gas (purity>99.99%) is introduced to degas the melt. During the degassing process, the aluminum alloy melt is stirred with a stirring head. The stirring time is about 8min to 10min and the stirring rate is about 400r / min. After degassing, the oxide slag on the surface of the melt is removed, and the melt is cast at about 710°C and cooled to room temperature to finally obtain a refined Al-Si series aluminum alloy.

[0030] Further, the application of AlxNbyB refiner in cast aluminum alloy A356 includes the following preparation method:

[0031] (1) weighing the raw materials according to the experimental ratio, including recycled A356 aluminum alloy raw materials and AlxNbyB refiner, with an accuracy of 0.1g, and providing 1% to 2% of A356 aluminum ingots as burn-off compensation;

[0032] (2) The weighed A356 alloy raw material is heated at 700°C to 750°C until it is melted, and an appropriate amount of a refiner alloy is added. After the refiner alloy is melted, electromagnetic stirring is performed for a stirring time of 5 min to 10 min and a stirring rate of about 200 r / min. After the stirring is completed, an appropriate amount of a refining agent is added, and high-purity argon gas (purity>99.99) is introduced for degassing. The stirring time is about 8 min to 10 min and the stirring rate is about 400 r / min. After the degassing treatment, the oxide slag on the surface is removed, and then a casting treatment is performed. The refined A356 series aluminum alloy is obtained by cooling to room temperature.

[0033] Furthermore, aluminum alloys with the addition of AlxNbyB refiner can be applied to pure aluminum alloys, cast Al-Si alloys, and A356 alloys, and thus applied to automotive parts, such as automotive steering knuckles, wheels, and piston alloys.

[0034] The beneficial effects of the present invention are:

[0035] (1) The AlxNbyB refiner of the present invention has more advantages than the commercial Al5TiB refiner: first, the AlxNbyB refiner alloy of the present invention is relatively less sensitive to cooling rate, has good microstructure, stable second phase particles, more uniform distribution, and good refinement effect; secondly, it can improve the mechanical properties of aluminum alloys; finally, for high Si series cast aluminum alloys, its "poisoning" effect is greatly reduced, the refinement effect is good, and the second phase aggregation phenomenon is greatly weakened.

[0036] (2) The present invention uses K2NbF7, KBF4, and recycled aluminum ingots as reaction raw materials to prepare the refiner alloy, which reduces the cost to a certain extent. At the same time, the uniformly mixed fluoride salt is added at least twice to avoid excessive heat after one addition, which causes the fluoride salt to volatilize. Combined with the temperature control process and electromagnetic stirring treatment, the volatilization of the fluoride salt in the reaction is reduced, the reaction is carried out more fully, and the purity of the refiner alloy is improved. The use of recycled aluminum ingots as raw materials responds to the national policy of recycling aluminum alloys to a certain extent and reduces carbon dioxide emissions. In the process of preparing the refiner, electromagnetic stirring is applied to the melt, and the generation of coarse second phases is reduced during the stirring process, so that the size of the generated nucleation second phase particles is reduced, and the problems of uneven distribution and aggregation of the second phase of the refiner alloy are improved. At the same time, applying a magnetic field to provide external energy is beneficial to the preparation of the alloy, so that the quality of the prepared refiner is better.

[0037] (3) Since the refiner is prepared by a fluoride salt reaction method, the reaction temperature is crucial. When the temperature is too high, the fluoride salt will volatilize, and when the temperature is too low, the reaction will not be complete, resulting in coarse second-phase particles. The present invention controls the temperature of the fluoride salt reaction to prevent further reactions from occurring in a fluctuating temperature environment, thereby affecting the formation and growth of the second-phase particles. In addition, after the stirring is completed, the aluminum liquid is refined and high-purity argon gas is introduced to further improve the quality of the refiner alloy. Finally, a rod-shaped refiner alloy is obtained by continuous casting and rolling, which is convenient for the transportation and industrial application of the refiner alloy.

[0038] (4) The present invention adds a proper amount of the refiner alloy of the present invention to the pure aluminum series to obtain obvious grain refinement. The grains of the pure aluminum alloy can be refined from 1445±20μm to 280±20μm, which confirms the good grain refining effect of the AlxNbyB refiner of the present invention. At the same time, when used in the casting Al-Si series alloy, the grains of the cast Al7Si aluminum alloy can be refined from 590±20μm to 230±20μm, which confirms that the AlxNbyB refiner of the present invention has good "anti-poisoning" performance; A356 aluminum alloy is used as a raw material for the preparation of automobile wheels and a small number of automobile parts. The addition of the new refiner in the A356 aluminum alloy makes the grain refinement effect good and the mechanical properties are improved. The yield strength can be increased to about 176±10MPa, and the tensile strength can be increased to about 268±10MPa; therefore, the AlxNbyB refiner of the present invention can be applied to the manufacture of automobile parts, such as automobile wheels, automobile steering knuckles and piston alloys; with the development of lightweight automobiles and new energy vehicles, the application of aluminum alloys is increasing. The content of the present invention has significant effects, simple processes, and low costs, and is suitable for large-scale industrial production, and has great industrial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The organizational diagram of the AlxNbyB refiner of the present invention, wherein (a) is a SEM diagram of the microstructure of the AlxNbyB refiner, and (b) is an XRD phase organization diagram;

[0040] Figure 2 The present invention adds different contents of refiners to the pure aluminum series grain structure diagram, wherein (a) to (f) add different contents of refiners to the pure aluminum series grain structure diagram;

[0041] Figure 3 The present invention adds different contents of refiner Al7Si cast aluminum alloy series grain structure diagram; wherein (a) to (f) add different contents of refiner Al7Si cast aluminum alloy series grain structure diagram;

[0042] Figure 4 This is the SEM microstructure of AlxNbyB refiner. DETAILED DESCRIPTION

[0043] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in this field or the product instructions are used. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased through regular channels.

[0044] Example 1: Preparation of Al5Nb0.5B Refining Agent

[0045] This embodiment provides a method for preparing a refiner for aluminum alloy, and the method for preparing a refiner for aluminum alloy comprises the following steps:

[0046] Step 1: Proportioning according to the following ratio (mass percentage): K2NbF7 powder about 61.5%, KBF4 about 14%, recycled aluminum ingot about 24.5%, and the mass fraction of the raw materials added is 100%, and an additional 1% to 2% of recycled aluminum ingot is added as a burn-loss compensation aluminum ingot; wherein the purity of K2NbF7 is greater than 99.8%, the purity of KBF4 is greater than 99.5%, and the purity of recycled aluminum ingot is greater than 99.5%;

[0047] Step 2: Melt the recycled aluminum block at 700°C to 750°C, add the evenly mixed K2NbF7 and KBF4 salts after melting, add 70% of the mixed fluoride salt for the first time, and stir the aluminum liquid electromagnetically, the stirring time is 3 minutes, the stirring interval time is 10 minutes, and the rotor stirring speed is 400r / min; after the first stirring is completed, add the remaining 30% of the mixed fluoride salt, the stirring time is 5 minutes, the stirring interval time is 8 minutes, and the stirring speed is 500r / min;

[0048] Step 3: After the fluoride salt reaction is stable, add the aluminum ingot, and after the aluminum ingot is melted, stir the solution electromagnetically for 8 minutes, with an interval of 5 minutes and a stirring speed of 400 r / min;

[0049] Step 4: After the stirring is completed, add an appropriate amount of refining agent to the aluminum liquid for slag removal, introduce high-purity argon gas (purity greater than 99.9%) for degassing, and stir during the degassing process. The stirring rate is 400r / min and the stirring and degassing time is 10min.

[0050] Step 5: After degassing, remove the scum formed on the surface of the aluminum liquid, and carry out continuous casting and rolling to finally obtain a rod with a diameter of of refiner alloy;

[0051] Step 6: The obtained refiner alloy is subjected to element detection, and the refiner composition is obtained to be Al5Nb0.5B (5 and 0.5 are mass percentages).

[0052] Example 2: Preparation of Al3Nb0.5B Refiner

[0053] Step 1: Proportioning according to the following ratio (mass percentage): K2NbF7 powder about 61.5%, KBF4 about 14%, recycled aluminum ingot about 24.5%, and the mass fraction of the raw materials added is 100%, and an additional 1% to 2% of recycled aluminum ingot is added as a burn-loss compensation aluminum ingot; wherein the purity of K2NbF7 is greater than 99.8%, the purity of KBF4 is greater than 99.5%, and the purity of recycled aluminum ingot is greater than 99.5%;

[0054] Step 2: Melt the recycled aluminum block at 700℃~750℃, add the evenly mixed K2NbF7 and KBF4 salts after melting, and stir the aluminum liquid electromagnetically. The stirring time is 3min, the stirring interval time is 10min, and the rotor stirring speed is 400r / min;

[0055] Step 3: After the fluoride salt reaction is stable, add the aluminum ingot, and after the aluminum ingot is melted, stir the solution electromagnetically for 8 minutes, with an interval of 5 minutes and a stirring speed of 400 r / min;

[0056] Step 4: After the stirring is completed, add an appropriate amount of refining agent to the aluminum liquid for slag removal, introduce high-purity argon gas (purity greater than 99.9%) for degassing, and stir during the degassing process. The stirring rate is 400r / min and the stirring and degassing time is 10min.

[0057] Step 5: After degassing, remove the scum formed on the surface of the aluminum liquid, and carry out continuous casting and rolling to finally obtain a rod with a diameter of of refiner alloy;

[0058] Step 6: The obtained refiner alloy is subjected to element detection, and the refiner composition is obtained to be Al3Nb0.5B (3 and 0.5 are mass fractions).

[0059] Example 3: Application of refiner in pure aluminum alloy

[0060] The application of refiners in pure aluminum alloys includes the following steps:

[0061] Step 1: First, pre-treat the surface of the experimental raw materials, and then weigh the raw materials according to the experimental ratio, accurate to 1g, the recycled aluminum ingot is about 2020±20g, and the refiner alloy is 0~42g;

[0062] Step 2: Put the recycled aluminum ingot alloy into a graphite crucible, heat it to 700°C to 750°C for melting, add the refiner alloy prepared in Proportion Example 1 after the recycled aluminum ingot is melted, and perform electromagnetic stirring treatment on the melt after the refiner is melted, the stirring time is 10min to 15min, the stirring rate is 400r / min to 600r / min, and the magnetic field strength is 4T to 6T;

[0063] Step 3: After the alloy of the refiner reacts completely, add an appropriate amount of refining agent, and introduce high-purity argon (purity greater than 99.99%) for degassing and refining. During the degassing process, stir the aluminum liquid at a stirring rate of 400r / min to 600r / min, and the stirring and degassing time is about 10min;

[0064] Step 4: After degassing, remove the slag on the surface of the aluminum liquid, cast at about 710°C, cool to room temperature, and obtain a refined pure aluminum series alloy ingot.

[0065] Table 1 Related parameters of pure aluminum series with different contents of refiners

[0066]

[0067] Example 4: Application of refiner in Al7Si alloy

[0068] The application of refiner in Al7Si alloy includes the following steps:

[0069] Step 1: First, pre-treat the surface of the experimental raw materials, and then weigh the raw materials according to the experimental ratio, accurately to g; 1870g~1895g of recycled aluminum ingot, 0~40g of Al5Nb0.5B refiner alloy, 140g~143g of Si raw material (purity greater than 99.5%);

[0070] Step 2: Put the recycled aluminum ingot alloy into a crucible and heat it to 700°C to 750°C for melting. After the recycled aluminum ingot is melted, add Si raw material and 0.2wt% Al10Sr alloy. After Si is completely melted, add the refiner alloy prepared in Experimental Proportion Example 1. After the refiner is melted, perform electromagnetic stirring on the melt. The stirring time is 10min to 15min, the stirring rate is 400r / min to 600r / min, and the magnetic field strength is 4T to 6T.

[0071] Step 3: After the refiner alloy reacts completely, add an appropriate amount of refining agent after stirring, and introduce high-purity argon gas (purity greater than 99.99%) for degassing and refining. During the degassing process, the stirring head stirs at a stirring rate of 400r / min to 600r / min and a stirring time of 10min to 15min;

[0072] Step 4: After degassing, remove the scum on the surface of the aluminum liquid, and cast at about 710°C to obtain the refined Al7Si series alloy;

[0073] Step 5: Cool the cast Al7Si series alloy to room temperature and then perform T6 heat treatment; the T6 heat treatment process is: solution temperature 540°C, solution time 280min, water quenching, cooling to room temperature and then performing aging treatment, the aging temperature is 150°C, and the aging time is 150min.

[0074] Table 2 shows the relevant parameters of Al7Si casting alloys with different contents of refiner

[0075]

[0076] Example 5: Application of refiner in A356 alloy

[0077] The application of refiner in A356 alloy includes the following steps:

[0078] Step 1: First, pre-treat the surface of the experimental raw materials, weigh the raw materials according to the experimental ratio, accurately to g; 1970g~2115g of recycled A356 aluminum ingot (purity greater than 99.5%), 0~44g of refiner alloy;

[0079] Step 2: Place the regenerated A356 aluminum ingot alloy in a crucible and heat it to 700°C to 750°C for melting. After the regenerated A356 aluminum ingot is melted, add 0.2wt% Al10Sr alloy and the refiner alloy prepared in Experimental Proportion Example 1. After the refiner alloy is melted, perform electromagnetic stirring on the melt. The stirring time is 10min to 15min, the stirring rate is 400r / min to 600r / min, and the magnetic field strength is 4T to 6T.

[0080] Step 3: After the refiner alloy reacts completely, add an appropriate amount of refining agent, introduce high-purity argon (purity greater than 99.99%) for degassing and refining, and stir during the degassing process at a stirring rate of 400r / min to 600r / min and a stirring time of 10min to 15min;

[0081] Step 4: After degassing, remove the scum on the surface of the aluminum liquid, and cast at about 710°C to obtain the refined A356 series alloy;

[0082] Step 5: Cool the cast A356 series alloy to room temperature and then perform T6 heat treatment. The T6 heat treatment process is: solution temperature 540°C, solution time 280min, water quenching, and aging treatment after cooling to room temperature. The aging temperature is 150°C and the aging time is 150min.

[0083] Table 3 Related parameters of A356 alloy series with different contents of refiner

[0084]

[0085]

[0086] According to Tables 1 to 3, it can be seen that the AlxNbyB refiner prepared in Example 1 has an obvious grain refining effect in pure aluminum series and Al7Si cast aluminum alloys, and can improve the mechanical properties of the alloy in A356 series alloys.

[0087] according to Figure 1It can be seen that the second phase particles of the AlxNbyB refiner prepared in Example 1 are evenly distributed and have a large number. From the XRD test results, it can be determined that the second phase particles are Al3Nb and NbB2 particles. Figure 2 It can be seen that the AlxNbyB refiner prepared in Example 1 has a better grain refining effect in the pure aluminum series as the refiner content increases. Figure 3 It can be seen that the AlxNbyB refiner prepared in Example 1 has an improved grain refining effect in the cast aluminum alloy Al7Si series as the refiner content increases.

[0088] In summary, the fluorine salt reaction of the present invention controls the temperature to reduce the heat release during the fluorine salt reaction, which seriously affects the formation of second-phase particles and the volatilization of fluorine salts; the mixed K2NbF7 and KBF4 salts are added in batches to reduce the difficulty of temperature control and increase feasibility. At the same time, magnetic field stirring is applied during the fluorine salt reaction to provide energy for the reaction, which can improve the second-phase particle sedimentation problem in the fluorine salt preparation process and make the reaction more sufficient. The high-cost preparation method will limit the industrial application of refiners. The traditional fluorine salt reaction method introduces impurities into the melt and the purity is not high enough. Therefore, the improved fluorine salt reaction method is used to prepare refiners, which can improve the purity of the refiners, simplify the production process, and to a certain extent guarantee the refiner alloy yield, which has certain industrial feasibility.

[0089] The AlxNbyB refiner alloy prepared by the present invention has good microstructure, a large number of second phase particles, uniform distribution, good refinement effect, and can improve the mechanical properties of related aluminum alloys. Compared with the traditional Al5TiB refiner alloy, the microstructure is improved, the mechanical properties are improved, and the anti-poisoning ability is enhanced. It is applied to cast Al-Si series alloys and A356 alloys with good effect. At present, it can be used in the production of automotive parts in industry, such as automotive steering knuckles, automotive wheels and piston alloys, etc., with good effect.

[0090] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a refiner for aluminum alloy, characterized in that: The preparation method of the refiner for aluminum alloy comprises the following steps: (1) melting a portion of the recycled aluminum ingots to obtain liquid aluminum, adding evenly mixed K2NbF7 and KBF4 salts to the liquid aluminum in batches, and stirring the mixture under a controlled temperature and stable condition; after the reaction, adding the remaining recycled aluminum ingots, and continuing the reaction under a stirring condition until the reaction is complete, thereby obtaining a reacted aluminum alloy liquid; (2) The aluminum alloy liquid after the reaction is subjected to a refining treatment to obtain a refined aluminum alloy liquid, and the refined aluminum alloy liquid is subjected to a continuous casting and continuous rolling treatment to obtain a rod-shaped refiner.

2. The method for preparing a refiner for aluminum alloy according to claim 1, characterized in that: The preparation method of the refiner for aluminum alloy comprises the following specific steps: (1) Melting part of the recycled aluminum ingots at 700° C. to 750° C. to obtain liquid aluminum liquid, adding evenly mixed K2NbF7 and KBF4 salts to the liquid aluminum liquid in at least two batches, reacting under stirring conditions, maintaining the reaction temperature at 730° C. ± 50° C., the first stirring time is 3 min. to 5 min., the stirring interval time is 10 min. to 15 min., and the stirring speed is 200 r / min. to 400 r / min. Then adding the remaining recycled aluminum ingots, continuing the reaction under stirring conditions, and continuing the stirring process until the reaction is complete, maintaining the reaction temperature at 730° C. ± 50° C., the stirring time is 5 min. to 8 min., the stirring interval time is 10 min. to 20 min., and the stirring speed is 400 r / min. to 600 r / min, to obtain a reacted aluminum alloy liquid; (2) adding a refining agent to the aluminum alloy liquid after the reaction for refining treatment and introducing high-purity argon gas for degassing treatment, wherein the stirring rate of the degassing rod during the degassing process is 400 r / min to 600 r / min, to obtain a refined aluminum alloy liquid; and continuously casting and continuously rolling the refined aluminum alloy liquid to obtain a rod-shaped refiner.

3. The method for preparing a refiner for aluminum alloy according to claim 2, characterized in that: When the evenly mixed K2NbF7 and KBF4 salts are added in two batches, the weight ratio of the first batch to the evenly mixed K2NbF7 and KBF4 salts is 60% to 75%, and the weight ratio of the second batch to the evenly mixed K2NbF7 and KBF4 salts is 25% to 40%.

4. A method for preparing a refiner for aluminum alloy according to any one of claims 1 to 3, characterized in that: The stirring method in step (1) adopts electromagnetic stirring, and the magnetic field intensity of the electromagnetic stirring is 4T to 6T.

5. A method for preparing a refiner for aluminum alloy according to any one of claims 1 to 3, characterized in that: The mass ratio of the recycled aluminum ingot, the K2NbF7 and the KBF4 is 20-25:60-66:10-15.

6. A refiner for aluminum alloy, characterized in that: The refiner for aluminum alloy is prepared by the preparation method according to any one of claims 1 to 5.

7. A refiner for aluminum alloy according to claim 6, characterized in that: The refiner is AlxNbyB, 1≤x≤5, 1≤x / y≤10, x, y are mass percentages; The effective nucleation phases of the refiner are Al3Nb, NbB2, and Al3Nb-NbB2 composite particles, the Al3Nb particles have a size range of 2μm to 15μm; the NbB2 particles have a second phase particle size range of 0.5μm to 3μm, and the second phase particles of the microstructure of the refiner are evenly distributed.

8. A refiner for aluminum alloy according to claim 6, characterized in that: The diameter of the refiner is 9. An application of a refiner for aluminum alloy, characterized in that: The refiner according to any one of claims 6 to 8 is used in the preparation of pure aluminum, Al-Si series or A356 series cast aluminum alloy.

10. The use of a refiner for aluminum alloy according to claim 9, characterized in that: The refiner is used for preparing automobile parts.

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