Grain refiner for casting aluminum alloy and preparation method of grain refiner

Abstract

The invention discloses a grain refiner for casting aluminum alloy and a preparation method of the grain refiner, and belongs to the technical field of additives for aluminum alloy casting. The grain refiner is formed by casting 76 to 97 parts by weight of potassium fluotitanate, 140 to 186 parts by weight of potassium fluoborate and 1000 parts by weight of aluminum ingots, or is formed by casting 30 to 59 parts by weight of potassium fluotitanate, 4.5 to 8.85 parts by weight of TiH2 powder, 140 to 186 parts by weight of potassium fluoborate and 1000 parts by weight of aluminum ingots. The raw materials are sequentially subjected to mixing, smelting, alloying, diluting, refining, casting and machining forming, and the grain refiner is prepared. The grain refiner with long effective refinement time can be prepared by improving the composition and proportion of the raw materials and the process.

Description

Technical Field

[0001] The invention belongs to the technical field of additives for aluminum alloy casting, and specifically relates to a grain refiner for casting aluminum alloy and a preparation method thereof. Background Art

[0002] Cast aluminum alloys are castings of various shapes and properties obtained by casting. The casting methods generally adopt sand casting, metal mold casting, investment casting, shell casting, etc. In the casting process, the grains of the aluminum alloy can be refined by adding TiB intermediate alloy formed by titanium and boron elements. This refinement can improve the mechanical properties of the casting, such as strength, plasticity and toughness, while improving the surface quality of the casting. For example, the invention patent with publication number CN116287835A discloses an aluminum titanium boron grain refiner prepared with titanium powder, potassium fluoroborate, potassium fluorotitanate, potassium fluoroaluminate and pure aluminum as raw materials. The aluminum titanium boron grain refiner has TiAl 3 and TiB 2 Two phases, TiB 2 The particles are spherical, evenly distributed, and the size is 0.5~1.5um; TiAl 3 It is a block with few sharp angles, evenly distributed in a dispersed state, with a size of less than 50um, and has a good refining effect. However, since the production process of cast aluminum alloy is non-continuous production, the production time of a single furnace is relatively long, which makes the ordinary aluminum titanium boron (Ti% 3~5; B% 0.2~1) grain refiner due to TiB 2 Failure due to particle settling. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a grain refiner for cast aluminum alloy with long-term refinement ability and a preparation method thereof.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a grain refiner for casting aluminum alloy, which is cast by weight from 76 to 97 parts of potassium fluorotitanate, 140 to 186 parts of potassium fluoroborate and 1000 parts of aluminum ingot, or from 30 to 59 parts of potassium fluorotitanate, 4.5 to 8.85 parts of TiH 2 It is cast from 140 to 186 parts of potassium fluoroborate powder and 1000 parts of aluminum ingot.

[0005] Another technical solution adopted by the present invention is: a method for preparing the above-mentioned grain refiner for cast aluminum alloy, comprising the following steps: S1. Mixing: uniformly mixing all raw materials except the aluminum ingot to obtain a mixture; S2, smelting: melting the aluminum ingot to obtain liquid aluminum; S3, alloying: adding 1 / 2 of the mixture to 1 / 2 of the liquid aluminum, after the reaction is completed, removing the slag on the surface of the melt; then continue to add the remaining 1 / 2 of the mixture and react fully, after the reaction is completed, remove the slag on the surface of the melt to obtain aluminum liquid; S4, dilution: maintaining the temperature of the aluminum liquid at 730-760° C., and adding the remaining 1 / 2 of the liquid aluminum; S5. Refining: Degassing and deslagging with inert gas at 755-900°C for 20-40 minutes to obtain a clean aluminum alloy melt; S6, casting: casting and cooling the aluminum alloy melt to obtain a casting billet; S7, processing and forming: hot rolling or extruding the ingot.

[0006] The beneficial effect of the present invention is that the present invention can prepare a grain refiner for cast aluminum alloy with an effective refinement time of up to 360 minutes by adjusting the addition amount of potassium fluorotitanate and potassium fluoroborate and adding a dilution step between alloying and refining. DETAILED DESCRIPTION

[0007] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes.

[0008] A grain refiner for casting aluminum alloy, which is cast from 76-97 parts of potassium fluorotitanate, 140-186 parts of potassium fluoroborate and 1000 parts of aluminum ingot, and contains 1.5-1.9wt% of Ti, 1.2-1.6wt% of B, and the rest is Al and unavoidable impurities. or 30-59 parts of potassium fluorotitanate, 4.5-8.85 parts of TiH 2 The aluminum alloy is cast from powder, 140-186 parts of potassium fluoroborate and 1000 parts of aluminum ingots, and contains 1.4-2.0wt% of Ti, 1.2-1.6wt% of B, and the rest is Al and unavoidable impurities.

[0009] From the above description, it can be seen that the beneficial effect of the present invention is that some cast aluminum alloys will add a certain amount of Si in order to improve the high temperature fluidity of the alloy, reduce shrinkage, improve wear resistance, etc. When the Si content is low, the behavior of Si is expected to reduce the grain size through the growth restriction effect. However, when the Si content exceeds about 3%, the situation is just the opposite and coarsening occurs. This is because with the presence of Si, the solubility of Ti in solid Al decreases, and the surface chemistry and surface energy are believed to be positive for TiB 2 The nucleation of Si is adversely affected, that is, Si poisoning may occur. The grain refiner for cast aluminum alloy provided by the present invention utilizes potassium fluorotitanate and potassium fluoroborate to react to generate TiB 2 ·AlB2 Particles, the density of the particles is 2.60~3.0g / cm 2 , average particle size ≤1.5μm, compared with TiB 2 4.52g / cm 2 The particle density is much smaller, and it is basically in a suspended state in the aluminum melt without settling, so it has a long-term refining ability and reacts to generate TiB 2 ·AlB 2 The particles can also avoid the problem of Si poisoning at the application end. When added to the cast aluminum alloy, the particles will preferentially react with the additional Ti in the melt, thus avoiding the influence of Si on the surface energy of the particles. 2 As an alternative to potassium fluorotitanate, TiH 2 Adding it will decompose hydrogen and instantly break up TiB 2 ·AlB 2 The particles are refined to make them finer, thereby obtaining particles <1μm, which can further increase the effective time of refinement.

[0010] Furthermore, when the raw material contains TiH 2 When TiH 2 The weight of potassium fluorotitanate is preferably 15%. When the addition is less than 15%, the effect of further improving the effective time of refinement is not obvious. When the content exceeds 15%, the decomposed hydrogen overflows more, which is not conducive to safe production.

[0011] A method for preparing a grain refiner for casting aluminum alloy comprises the following steps: S0. Ingredients: By weight, weigh 76-97 parts of potassium fluorotitanate, 140-186 parts of potassium fluoroborate and 1000 parts of aluminum ingot, or weigh 30-59 parts of potassium fluorotitanate, 7.5 parts of TiH 2 powder, 140-186 parts of potassium fluoroborate and 1000 parts of aluminum ingot; S1. Mixing: uniformly mixing all raw materials except the aluminum ingot to obtain a mixture; S2, smelting: melting the aluminum ingot to obtain liquid aluminum; S3, alloying: add 1 / 2 of the mixture to 1 / 2 of liquid aluminum. After the reaction is complete, remove the slag on the surface of the melt. Then continue to add the remaining 1 / 2 of the mixture and react fully. After the reaction is complete, remove the slag on the surface of the melt to obtain aluminum liquid. S4, dilution: maintain the aluminum liquid temperature at 730~760℃, add the remaining 1 / 2 liquid aluminum; S5. Refining: Degassing and deslagging with inert gas at 755-900°C for 20-40 minutes to obtain a clean aluminum alloy melt; S6, casting: casting and cooling the aluminum alloy melt to obtain a casting billet; S7. Processing and forming: hot rolling or extrusion of the ingot.

[0012] From the above description, it can be seen that the TiB generated by the alloying step 2 ·AlB 2 The particle density is still relatively high, about 3.5~4.0g / cm 2 , by adding aluminum liquid to dilute, aluminum and TiB 2 ·AlB 2 The reaction increases the proportion of Al in the particles, thereby further reducing the particle density to 2.60~3.0g / cm 2 TiB can be avoided by controlling the temperature and time during the refining process. 2 Agglomeration of particles and TiAl 3 The growth of particles.

[0013] Furthermore, the aluminum ingot is a remelted aluminum ingot with a purity of 99.7% or more.

[0014] Furthermore, the particle size of potassium fluorotitanate and potassium fluoroborate satisfies: the particles with a size of -100 μm to 60 μm account for ≥ 85%. From the above description, it can be seen that if the particle size of potassium fluorotitanate and potassium fluoroborate cannot meet the above particle size requirements, the TiB in the obtained aluminum titanium boron wire structure will be 2 ·AlB 2 >1.5μm.

[0015] Furthermore, when the aluminum ingot is melted in S2, when the temperature reaches 730-760°C or above, an inert gas is used to eliminate impurities and hydrogen, and then liquid aluminum is obtained.

[0016] Further, in S3, 1 / 2 of the mixture is added to 1 / 2 of the liquid aluminum at a feeding rate of 10-45 kg / min under stirring conditions. The stirring conditions are achieved by self-stirring or stirring with an inert gas, which can promote a full reaction.

[0017] Furthermore, in S3, the remaining 1 / 2 of the mixture is added at a feeding rate of 10-45 kg / min under stirring conditions and reacted fully.

[0018] Furthermore, the temperature of the first reaction in S3 is 730-800°C, and the temperature of the second reaction is 750-800°C.

[0019] Further, in S4, the remaining 1 / 2 of the liquid aluminum is added at a feeding rate of 50-100 kg / min under stirring conditions.

[0020] Furthermore, the cooling rate in S6 is 20-60°C / s. By controlling the cooling rate during casting, a casting with fine grains and a fine second phase can be obtained.

[0021] Furthermore, the processing temperature of S7 is controlled at 400-550℃ during processing. Hot rolling or extrusion processing (processing) is carried out immediately after casting, which can make full use of the heat of the casting material, greatly reducing the manufacturing cost and improving production efficiency.

[0022] In one or more embodiments, a method for preparing a grain refiner for a cast aluminum alloy comprises the following steps: S1. Ingredients: weigh 76-97 parts of potassium fluorotitanate, 140-186 parts of potassium fluoroborate and 1000 parts of remelted aluminum ingot with a purity of more than 99.7% by weight; Alternatively, weigh 30-59 parts of potassium fluorotitanate; 7.5 parts of TiH 2 Powder; 140~186 parts of potassium fluoroborate and 1000 parts of remelted aluminum ingot with a purity of more than 99.7%, of which TiH 2 The weight should be 15% of potassium fluorotitanate.

[0023] S2. Mixing: All raw materials except the remelted aluminum ingot are loaded into the "V-type" fluoride salt mixing system, and the mixing time is set to 30-50 minutes to mix all the added raw materials evenly to obtain a mixture; Among them, the particle size of potassium fluorotitanate and potassium fluoroborate meets the following requirements: particles of -100μm to 60μm ≥ 85%, specifically particles of -100μm to 60μm are 85%, particles of -100μm to 60μm are 90%, particles of -100μm to 60μm are 95%, etc.

[0024] S3. Melting: Put the remelted aluminum ingot into a melting furnace for melting. When the temperature reaches 730-760°C or above, use an inert gas to eliminate impurities and hydrogen to obtain liquid aluminum. Then, transfer 1 / 2 of the liquid aluminum to a medium frequency induction heating furnace. Specifically, the elimination treatment can be started when it is detected that the melt temperature reaches 730°C, 735°C, 740°C, 745°C, 750°C, 755°C or 760°C or above.

[0025] S4, alloying: add 1 / 2 of the S2 mixture evenly and slowly at a feeding rate of 10~45kg / min to the medium frequency furnace containing liquid aluminum. During this process, the medium frequency furnace should be self-stirred or stirred with an external inert gas. The reaction time is controlled at 5~10min, and the reaction temperature is controlled at 730~800℃. After the reaction is completed, the slag on the surface of the melt is removed; continue to add the remaining 1 / 2 of the S2 mixture at a feeding rate of 10~45kg / min, the reaction time is controlled at 5~10min, and the reaction temperature is controlled at 750~800℃. After the reaction is completed, the slag on the surface of the melt is removed to obtain aluminum liquid; Among them, the feeding rate can be 10kg / min, 15kg / min, 20kg / min, 25kg / min, 30kg / min, 35kg / min, 40kg / min, 45kg / min, etc., which can be selected according to actual process conditions; the reaction time can be 5 min, 6 min, 7 min, 8 min, 9 min, 10 min, etc.

[0026] S5. Dilution: transfer the aluminum liquid obtained in S4 to a holding furnace, and control the temperature of the aluminum liquid to 730-760°C, and then add the remaining 1 / 2 of the liquid aluminum to the holding furnace at a feeding rate of 50-100kg / min under stirring conditions; wherein the insulation temperature of the aluminum liquid can be 730°C, 735°C, 740°C, 745°C, 750°C, 755°C, 760°C, etc.; the feeding rate can be 50kg / min, 55kg / min, 60kg / min, 65kg / min, 70kg / min, 75kg / min, 80kg / min, 85kg / min, 90kg / min, 95kg / min, 100kg / min, etc.

[0027] S6. Refining: Degassing and deslagging are carried out with Ar gas. The refining temperature of the whole process is controlled at 755-900°C, and the refining time is controlled at 20-40min to obtain a clean aluminum alloy melt. The refining temperature can be 755°C, 760°C, 765°C, 770°C, 775°C, 780°C, 785°C, 790°C, 795°C, 800°C, 810°C, 815°C, 820°C, 825°C, 825°C, 830°C, 835°C, 840°C, 845°C, 850°C, 855°C, 860°C, 865°C, 870°C, 875°C, 880°C, 885°C, 890°C, 895°C, 900°C, etc. The refining time can be 20 min, 25 min, 30 min, 35 min, 40 min, etc.

[0028] S7. Casting: The clean aluminum alloy melt is quickly and evenly cooled by a horizontal water-cooled wheel copper mold or other casting methods. The cooling rate of the casting process is controlled at 20-60°C / s to obtain a cast billet; wherein the cooling rate can be 20°C / s, 25°C / s, 30°C / s, 35°C / s, 40°C / s, 45°C / s, 50°C / s, 55°C / s, 60°C / s.

[0029] S8. Processing and forming: The ingot is hot-rolled or extruded into a cylinder, and the processing temperature is controlled at 400-550°C to obtain a grain refiner (i.e., titanium boron wire).

[0030] Embodiment 1: A method for preparing a grain refiner for casting aluminum alloy, specifically comprising the following steps: S1. Ingredients: Weigh 86 parts of potassium fluorotitanate, 140 parts of potassium fluoroborate and 1000 parts of remelted aluminum ingots with a purity of more than 99.7% by weight; S2. Mixing: All raw materials except the remelted aluminum ingot are loaded into a "V-type" fluoride salt mixing system, and the mixing time is set to 50 minutes to mix all the added raw materials evenly to obtain a mixture; Among them, the particle size of potassium fluorotitanate and potassium fluoroborate meets the following requirements: 85% of the particles are between -100 μm and 60 μm.

[0031] S3. Melting: Put the remelted aluminum ingot into the melting furnace for melting. When the temperature reaches above 740°C, use inert gas to eliminate impurities and hydrogen to obtain liquid aluminum. Then, transfer 1 / 2 of the liquid aluminum to the medium frequency induction heating furnace.

[0032] S4, alloying: add 1 / 2 of the S2 mixture evenly and slowly at a feeding rate of 25kg / min into a medium frequency furnace containing liquid aluminum. During this process, the medium frequency furnace should be self-stirred or stirred with an external inert gas. The reaction time is controlled at 10min and the reaction temperature is controlled at 760℃. After the reaction is completed, the slag on the surface of the melt is removed. Continue to add the remaining 1 / 2 of the S2 mixture at a feeding rate of 25kg / min. The reaction time is controlled at 10min and the reaction temperature is controlled at 780℃. After the reaction is completed, the slag on the surface of the melt is removed to obtain aluminum liquid.

[0033] S5. Dilution: The aluminum liquid obtained in S4 is transferred to a holding furnace, and the temperature of the aluminum liquid is controlled to 760°C. Then, under stirring conditions, the remaining 1 / 2 of the liquid aluminum is added to the holding furnace at a feeding rate of 70 kg / min.

[0034] S6. Refining: Use Ar gas for degassing and deslagging. The refining temperature of the whole process is controlled at 800°C and the refining time is controlled at 30 minutes to obtain a clean aluminum alloy melt.

[0035] S7. Casting: The clean aluminum alloy melt is quickly and evenly cooled through a horizontal water-cooled wheel-type copper mold, and the cooling rate is controlled at 45°C / s to obtain a cast billet.

[0036] S8. Processing and forming: hot rolling the ingot into a 9.5 mm cylinder, the processing temperature is controlled at 450°C, and a grain refiner is obtained. The obtained grain refiner contains 1.7 wt% Ti, 1.2 wt% B, and the rest is Al and unavoidable impurities.

[0037] Embodiment 2: The difference between Example 2 and Example 1 is that S1 is: 76 parts of potassium fluorotitanate, 187 parts of potassium fluoroborate and 1000 parts of remelted aluminum ingots with a purity of more than 99.7% are weighed by weight; and the particle size of potassium fluorotitanate and potassium fluoroborate satisfies: 90% of the particles are -100μm to 60μm; the obtained grain refiner contains 1.5wt% Ti, 1.6wt% B, and the rest is Al and unavoidable impurities.

[0038] Embodiment three: The difference between Example 3 and Example 1 is that S1 is: 97 parts of potassium fluorotitanate, 140 parts of potassium fluoroborate and 1000 parts of remelted aluminum ingots with a purity of more than 99.7% are weighed by weight; and the particle size of potassium fluorotitanate and potassium fluoroborate satisfies: 95% of the particles are -100μm to 60μm; the obtained grain refiner contains 1.9wt% Ti, 1.2wt% B, and the rest is Al and unavoidable impurities.

[0039] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the step of diluting S5 is not performed, that is, the mixture is directly added to the entire liquid aluminum obtained by S3 in two equal portions; the control of other reaction conditions is the same as that of Example 1, and the prepared grain refiner contains 1.7wt% Ti, 1.2wt% B, and the rest is Al and unavoidable impurities.

[0040] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the particle size of potassium fluorotitanate and potassium fluoroborate satisfies: 80% of the particles are -100 μm to 60 μm, and the prepared grain refiner contains 1.7 wt% Ti, 1.4 wt% B, and the rest is Al and unavoidable impurities.

[0041] Comparative Example 3: A conventional AlTi5B1 grain refiner is provided, which contains 5.01wt% of Ti, 1.02wt% of B, and the remainder of Al and inevitable impurities.

[0042] The grain refiners of Examples 1, 2, 3 and Comparative Examples 1, 2, 3 were added to the production of aluminum alloy at an addition amount of 2 kg / t. The structural characteristics of the grain refiners and the grain refinement effects when applied are shown in Table 1.

[0043] Table 1

[0044] It can be seen from Table 1 that the effective time of grain refinement provided by the present invention can reach 300 min, and TiB can be significantly reduced by controlling the particle size of fluoride salt and using dilution process. 2 ·AlB 2 The average particle size increases the effective time of refinement.

[0045] Embodiment 4: A method for preparing a grain refiner for casting aluminum alloy, specifically comprising the following steps: S1. Ingredients: Weigh 50 parts of potassium fluorotitanate, 7.5 parts of TiH 2 powder, 164 parts of potassium fluoroborate and 1000 parts of remelted aluminum ingots with a purity of more than 99.7%; S2. Mixing: All raw materials except the remelted aluminum ingot are loaded into a "V-type" fluoride salt mixing system, and the mixing time is set to 45 minutes to mix all the added raw materials evenly to obtain a mixture; Among them, the particle size of potassium fluorotitanate and potassium fluoroborate meets the following requirements: particles of -100 μm to 60 μm account for ≥ 85%.

[0046] S3. Melting: Put the remelted aluminum ingot into the melting furnace for melting. When the temperature reaches above 730°C, use inert gas to eliminate impurities and hydrogen to obtain liquid aluminum. Then, transfer 1 / 2 of the liquid aluminum to the medium frequency induction heating furnace.

[0047] S4, alloying: add 1 / 2 of the S2 mixture evenly and slowly at a feeding rate of 20kg / min into a medium frequency furnace containing liquid aluminum. During this process, the medium frequency furnace should be self-stirred or stirred with an external inert gas. The reaction time is controlled at 10min and the reaction temperature is controlled at 750℃. After the reaction is completed, the slag on the surface of the melt is removed. Continue to add the remaining 1 / 2 of the S2 mixture at a feeding rate of 20kg / min. The reaction time is controlled at 10min and the reaction temperature is controlled at 770℃. After the reaction is completed, the slag on the surface of the melt is removed to obtain aluminum liquid.

[0048] S5. Dilution: The aluminum liquid obtained in S4 is transferred to a holding furnace, and the temperature of the aluminum liquid is controlled to 750°C. Then, under stirring conditions, the remaining 1 / 2 of the liquid aluminum is added to the holding furnace at a feeding rate of 65 kg / min.

[0049] S6. Refining: Use Ar gas for degassing and deslagging. The refining temperature of the whole process is controlled at 820°C and the refining time is controlled at 28 minutes to obtain a clean aluminum alloy melt.

[0050] S7. Casting: The clean aluminum alloy melt is quickly and evenly cooled through a horizontal water-cooled wheel copper mold or other casting methods. The cooling rate of the casting process is controlled at 40°C / s to obtain a cast billet.

[0051] S8. Processing and forming: hot rolling the ingot into a 9.5 mm cylinder, and controlling the processing temperature at 450°C to obtain a grain refiner. The obtained grain refiner contains 1.7 wt% Ti, 1.4 wt% B, and the rest Al and unavoidable impurities.

[0052] Embodiment five: The difference between Example 5 and Example 4 is that S1 is: 44 parts of potassium fluorotitanate, 6.6 parts of TiH 2 powder, 187 parts of potassium fluoroborate and 1000 parts of remelted aluminum ingots with a purity of more than 99.7%; and the particle sizes of potassium fluorotitanate and potassium fluoroborate meet: 90% of the particles are -100μm to 60μm; the obtained grain refiner contains 1.5wt% Ti, 1.6wt% B, and the rest is Al and unavoidable impurities.

[0053] Embodiment six: The difference between Example 6 and Example 4 is that S1 is: 41 parts of potassium fluorotitanate, 6.15 parts of TiH 2 powder, 140 parts of potassium fluoroborate and 1000 parts of remelted aluminum ingots with a purity of more than 99.7%; and the particle sizes of potassium fluorotitanate and potassium fluoroborate meet: 95% of the particles of -100μm to 60μm; the obtained grain refiner contains 1.4wt% Ti, 1.2wt% B, and the rest Al and unavoidable impurities.

[0054] Comparative Example 4: The difference between Comparative Example 4 and Example 6 is that the step of diluting S5 is not performed, that is, the mixture is directly added to the entire liquid aluminum obtained by S3 in two equal portions; the control of other reaction conditions is the same as that of Example 6, and the prepared grain refiner contains 1.5wt% Ti, 1.3wt% B, and the rest Al and unavoidable impurities.

[0055] Comparative Example 5: The difference between Comparative Example 5 and Example 4 is that no TiH is added. 2 The powder is replaced by an equal amount of potassium fluorotitanate to make the total weight of the added raw materials the same. The prepared grain refiner contains 1.7wt% Ti, 1.4wt% B, and the rest is Al and unavoidable impurities.

[0056] Comparative Example 6: A conventional AlTi5B1 grain refiner is provided, which contains 5 wt% of Ti, 1 wt% of B, and the remainder of Al and inevitable impurities.

[0057] The grain refiners of Examples 4, 5, 6 and Comparative Examples 4, 5, 6 were added to the production of aluminum alloy at an addition amount of 2 kg / t. The structural characteristics of the grain refiners and the grain refinement effects when applied are shown in Table 2.

[0058] Table 2

[0059] It can be seen from Table 2 that the effective time of the grain refiner provided by the present invention can reach 360 minutes, and the TiB can be significantly reduced by using the dilution process. 2 ·AlB 2 The average particle size of TiH 2 Replacing potassium fluorotitanate can further significantly reduce TiB 2 ·AlB 2 The average particle size increases the effective time of refinement.

[0060] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A grain refiner for cast aluminum alloy, characterized in that: The casting is made of 76-97 parts of potassium fluorotitanate, 140-186 parts of potassium fluoroborate and 1000 parts of aluminum ingots by weight.

2. The grain refiner for cast aluminum alloy according to claim 1, characterized in that: The casting is made of 30-59 parts of potassium fluorotitanate, 4.5-8.85 parts of titanium hydride powder, 140-186 parts of potassium fluoroborate and 1000 parts of aluminum ingots by weight.

3. The grain refiner for cast aluminum alloy according to claim 1 or 2, characterized in that: The particle sizes of the potassium fluorotitanate and the potassium fluoroborate satisfy: ≥85% of the particles are between -100 μm and 60 μm.

4. The method for preparing the grain refiner for cast aluminum alloy according to claim 1 or 2, characterized in that: The following steps are involved: S1. Mixing: uniformly mixing all raw materials except the aluminum ingot to obtain a mixture; S2, smelting: melting the aluminum ingot to obtain liquid aluminum; S3, alloying: adding 1 / 2 of the mixture to 1 / 2 of the liquid aluminum, after the reaction is completed, removing the slag on the surface of the melt; then continue to add the remaining 1 / 2 of the mixture and react fully, after the reaction is completed, remove the slag on the surface of the melt to obtain aluminum liquid; S4, dilution: maintaining the temperature of the aluminum liquid at 730-760° C., and adding the remaining 1 / 2 of the liquid aluminum; S5. Refining: Degassing and deslagging with inert gas at 755-900°C for 20-40 minutes to obtain a clean aluminum alloy melt; S6, casting: casting and cooling the aluminum alloy melt to obtain a casting billet; S7, processing and forming: hot rolling or extruding the ingot.

5. The preparation method according to claim 4, characterized in that: When the aluminum ingot is melted in S2, when the temperature reaches 730-760°C or above, an inert gas is used to eliminate impurities and hydrogen, and then liquid aluminum is obtained.

6. The preparation method according to claim 4, characterized in that: In S3, 1 / 2 of the mixture is added to 1 / 2 of the liquid aluminum at a feeding rate of 10-45 kg / min under stirring conditions.

7. The preparation method according to claim 4, characterized in that: In S3, the remaining 1 / 2 of the mixture is added at a feeding rate of 10-45 kg / min under stirring and fully reacted.

8. The preparation method according to claim 4, characterized in that: The temperature of the first reaction in S3 is 730~800℃, and the temperature of the second reaction is 750~800℃.

9. The preparation method according to claim 4, characterized in that: In S4, the remaining 1 / 2 of the liquid aluminum is added at a feeding rate of 50-100 kg / min under stirring conditions.

10. The preparation method according to claim 4, characterized in that: The cooling rate in S6 is 20~60℃ / s.

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