Aluminum-titanium-boron rod with low oxidized slag content and preparation method thereof

Abstract

The application relates to the technical field of metal materials, in particular to an aluminum-titanium-boron rod with low oxidation and slag inclusion quantity and a preparation method thereof. The preparation method comprises the following steps: S1, mixing potassium fluoborate and part of potassium fluotitanate to obtain a mixed salt; S2, melting aluminum ingot to obtain first aluminum liquid; S3, adding the mixed salt into the aluminum liquid and stirring to obtain second aluminum liquid; S4, adding the remaining part of potassium fluotitanate into the second aluminum liquid and stirring, cleaning the floating dregs generated on the surface of the second aluminum liquid until the remaining part of potassium fluotitanate is added completely, and obtaining third aluminum liquid; S5, adding aluminum-vanadium intermediate alloy into the third aluminum liquid, and sequentially performing refining, casting and rolling to obtain the aluminum-titanium-boron rod; wherein the mass ratio of potassium fluotitanate to potassium fluoborate in the mixed salt is (46-50):(50-54). The aluminum-titanium-boron rod prepared by the preparation method has high cleanliness and high TiAl3 particle dissolution speed.

Description

[0001] This case is a divisional application based on the invention patent with the application date of August 12, 2022, application number 2022109714389, entitled "An Aluminum Titanium Boron Rod and Its Preparation Method". Technical Field

[0002] This invention relates to the field of metal materials technology, and in particular to an aluminum-titanium-boron rod with low oxide inclusion content and its preparation method. Background Technology

[0003] The Al-Ti-B series grain refiners are commonly prepared using the fluoride salt method both domestically and internationally. This involves a chemical reaction between a mixed salt of potassium fluorotitanate and potassium fluoroborate and liquid aluminum, followed by continuous casting and rolling or continuous casting and extrusion to produce 9.5mm wire rods. Currently, the aluminum casting industry routinely adds the aluminum-titanium-boron wire rod raw material continuously to the molten aluminum before the online degassing or filtration box. However, as the aluminum casting and rolling industries increasingly demand higher quality and lower costs for plates, strips, and foils, they desire to add the grain refiner as late as possible, including after all purification systems, specifically in the runner between the filter and the casting machine.

[0004] The paper "Review of the latest developments and best use of grain refiners" presented by Dr. Paul Cooper and Allan Barber at the Second International Melt Quality Symposium also discussed how some foundries want to add grain refiners as late as possible, even after all purification systems. The main obstacle to achieving this is the cleanliness of the aluminum-titanium-boron rod and the dissolution rate of the second-phase TiAl3 particles, which corresponds to less oxide residue and smaller TiAl3 particles. Currently, conventional production techniques yield aluminum-titanium-boron rods with an oxide residue content ≤1000 μm / cm². 2 The average size of the second-phase TiAl3 particles is 25-30 μm, which makes it difficult for existing aluminum-titanium-boron rods to meet the requirements of high cleanliness and high dissolution rate of the second-phase TiAl3 particles. Summary of the Invention

[0005] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to provide an aluminum-titanium-boron rod with low oxide inclusion content in molten aluminum and its preparation method.

[0006] To address the aforementioned technical problems, this invention provides a method for preparing an aluminum-titanium-boron rod, comprising the following steps:

[0007] S1. Mix potassium fluoroborate and a portion of potassium fluorotitanate to obtain a mixed salt;

[0008] S2. Melt the aluminum ingot to obtain the first molten aluminum;

[0009] S3. Add the mixed salt to the aluminum liquid and stir to obtain a second aluminum liquid;

[0010] S4. Add the remaining potassium fluorotitanate to the second aluminum liquid and stir. Clean the scum generated on the surface of the second aluminum liquid until the remaining potassium fluorotitanate is added to obtain the third aluminum liquid.

[0011] S5. Add aluminum-vanadium intermediate alloy to the third aluminum liquid, and then refine, cast and roll in sequence to obtain the aluminum-titanium-boron rod.

[0012] The mass ratio of potassium fluorotitanate to potassium fluoroborate in the mixed salt is (46-50):(50-54).

[0013] Further, an aluminum-titanium-boron rod prepared by the aforementioned method is provided, comprising the following components:

[0014] 2.6–5.5 wt% Ti, 0.15–1.2 wt% B, 0.02–0.10 wt% V, balance Al and unavoidable impurities.

[0015] The beneficial effects of this invention are as follows: By adding a certain amount of aluminum-vanadium intermediate to aluminum-titanium-boron, the vanadium in the aluminum-vanadium intermediate increases the surface tension of the slag, thereby promoting the full separation of the slag and the aluminum liquid, thus reducing the slag content of the aluminum liquid; at the same time, by adopting a process of adding potassium fluorotitanate in stages, smaller TiAl3 particles and a cleaner melt are obtained. Attached Figure Description

[0016] Figure 1 The image shown is a metallographic photograph of aluminum-titanium-boron alloy prepared in Example 1 of the present invention.

[0017] Figure 2 The image shown is a metallographic photograph of aluminum-titanium-boron alloy prepared in Comparative Example 1 according to a specific embodiment of the present invention. Detailed Implementation

[0018] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0019] A method for preparing an aluminum-titanium-boron rod includes the following steps:

[0020] S1. Mix potassium fluoroborate and a portion of potassium fluorotitanate to obtain a mixed salt;

[0021] S2. Melt the aluminum ingot to obtain the first molten aluminum;

[0022] S3. Add the mixed salt to the aluminum liquid and stir to obtain a second aluminum liquid;

[0023] S4. Add the remaining potassium fluorotitanate to the second aluminum liquid and stir. Clean the scum generated on the surface of the second aluminum liquid until the remaining potassium fluorotitanate is added to obtain the third aluminum liquid.

[0024] S5. Add aluminum-vanadium intermediate alloy to the third aluminum liquid, and then refine, cast and roll in sequence to obtain the aluminum-titanium-boron rod.

[0025] The mass ratio of potassium fluorotitanate to potassium fluoroborate in the mixed salt is (46-50):(50-54). Preferably, the mass ratio of potassium fluorotitanate to potassium fluoroborate in the mixed salt is 48:52. Since this ratio is close to the Ti to B ratio in TiB2 in the second phase, it is equivalent to first reacting to generate TiB2 particles, and then adding the remaining potassium fluorotitanate and aluminum water to generate TiAl3, thus making the generated TiAl3 finer.

[0026] This invention adds a certain amount of aluminum-vanadium intermediate to aluminum-titanium-boron alloy to increase the surface tension of the slag through the vanadium in the aluminum-vanadium intermediate, thereby promoting the complete separation of the slag and the aluminum melt and reducing the slag content of the aluminum melt. At the same time, by adopting a process of adding potassium fluorotitanate in stages, smaller TiAl3 particles and a cleaner melt are obtained.

[0027] The aluminum-vanadium intermediate is preferably AlV5 or AlV10.

[0028] Preferably, the potassium fluoroborate and potassium fluorotitanate have a particle size of 70 μm to 200 μm ≥ 90%. Selecting raw materials with appropriate particle sizes effectively reduces the particle size of TiAl3 and TiB2. The particle size of potassium fluoroborate and potassium fluorotitanate needs to be strictly controlled. Particle sizes that are too large or too small will lead to coarsening of the second phase. Specifically, if the raw materials are too fine, the reaction rate will be too fast, the temperature will rise rapidly, and the second phase will deteriorate; if the raw materials are too coarse, the reaction time will be prolonged, which will also cause the second phase to enlarge.

[0029] Preferably, S2 specifically involves: melting aluminum ingots, and when the temperature reaches above 740°C, using an inert gas to remove impurities and hydrogen to obtain the first molten aluminum.

[0030] The inert gas is preferably argon.

[0031] In one embodiment, the remaining potassium fluorotitanate is added to the second molten aluminum in at least two portions. Preferably, the remaining potassium fluorotitanate is added to the second molten aluminum in 2 to 10 portions.

[0032] Preferably, the feeding rate of the mixed salt and the potassium fluorotitanate is 10-60 kg / min, and more preferably 30-50 kg / min.

[0033] Preferably, the stirring time is 10–40 min, and the reaction temperature during stirring is 740–850 °C. By controlling the stirring time and the reaction temperature during stirring, the raw materials are fully mixed, and the slag is separated from the molten aluminum phase, thereby reducing the cleanliness of the molten aluminum.

[0034] Preferably, the refining temperature is 740–880°C, and the refining time is 30–120 min. By controlling the refining temperature and refining time, the agglomeration of TiB2 particles and the growth of TiAl3 particles can be avoided.

[0035] Preferably, the cooling rate is 20–60 °C / s. Rapid cooling of the melt yields a cast billet with fine grains and a fine second phase.

[0036] Specifically, the preparation method includes the following steps:

[0037] S1. Mixing: Weigh out remelted aluminum ingots, potassium fluorotitanate, potassium fluoroborate and aluminum-vanadium master alloy according to the proportions; mix potassium fluoroborate and a portion of potassium fluorotitanate to obtain mixed salt;

[0038] S2. Smelting: Remelted aluminum ingots with a purity of 99.7% or higher are put into a smelting furnace for melting. When the temperature reaches 740°C or higher, impurities and hydrogen are removed by inert gas. Then, the clean liquid aluminum (first aluminum liquid) is transferred into a medium-frequency induction furnace.

[0039] S3, Alloying 1: The mixed salt is added to the first aluminum liquid at a feeding rate of 10-60 kg / min. During this process, the medium frequency furnace is self-stirred or externally mechanically stirred for 10-40 min or more, and the reaction temperature is 740-850℃ to obtain the second aluminum liquid.

[0040] S3, Alloying 2: The remaining potassium fluorotitanate is added to the second aluminum liquid in batches at a feeding rate of 10-60 kg / min. After each addition, the slag must be cleaned before the next addition of potassium fluorotitanate is made. This process is repeated until all the potassium fluorotitanate is added. During this process, the medium frequency furnace is self-stirred or externally mechanically stirred for 10-40 minutes or more, and the reaction temperature is 740-850℃ to obtain the third aluminum liquid.

[0041] S4. Refining: The third aluminum liquid is transferred into a holding furnace, aluminum-vanadium master alloy is added, and degassing and slag removal are carried out. The refining temperature is 740-880℃ and the refining time is 30-120min to obtain aluminum alloy melt.

[0042] S5. Casting: The aluminum alloy melt is rapidly cooled by a horizontal water-cooled wheel-type copper mold or other casting methods at a cooling rate of 20-60°C to obtain a casting billet.

[0043] S6. Rolling: The cast billet is hot rolled into a 9.5mm round rod at a rolling temperature of 400-550℃ to obtain an aluminum-titanium-boron rod.

[0044] The rolling and casting processes are preferably carried out continuously to make full use of the heat of the billet itself, thereby greatly reducing manufacturing costs and improving production efficiency.

[0045] An aluminum-titanium-boron rod prepared by the aforementioned method comprises the following components:

[0046] 2.6–5.5 wt% Ti, 0.15–1.2 wt% B, 0.02–0.10 wt% V, balance Al and unavoidable impurities.

[0047] In this invention, the content of V needs to be strictly controlled. If it is below 0.02wt%, it will be difficult to reduce the slag content in the aluminum melt. If it is above 0.10wt%, it will cause the second phase particles to grow and deteriorate the grain refinement ability.

[0048] A certain amount of V is introduced into the aluminum-titanium-boron rod to increase the surface tension of the slag, thereby promoting the complete separation of the slag from the molten aluminum and reducing the slag content in the molten aluminum. Testing showed that the aluminum-titanium-boron rod prepared by the method provided in this invention has an average TiAl3 particle size ≤20μm; TiB2 is dispersed without agglomeration and has an average particle size ≤2μm; and the oxide inclusion content is ≤500μm / cm³. 2 In actual production, even when added after the purification system, thin plates with Grade 1 grains can still be obtained.

[0049] Examples 1 to 4 (S1 to S4) and Comparative Examples 1 to 5 (D1 to D5)

[0050] The preparation method of the aluminum-titanium-boron rod includes the following steps:

[0051] S1. Mixing: Weigh out remelted aluminum ingots, potassium fluorotitanate, potassium fluoroborate and aluminum-vanadium master alloy according to the proportions; mix potassium fluoroborate and a portion of potassium fluorotitanate to obtain mixed salt;

[0052] S2. Smelting: Remelted aluminum ingots with a purity of 99.7% or higher are put into a smelting furnace for melting. When the temperature reaches 740°C or higher, impurities and hydrogen are removed by inert gas. Then, the clean liquid aluminum (first aluminum liquid) is transferred into a medium-frequency induction furnace.

[0053] S3, Alloying 1: The mixed salt is added to the first aluminum liquid at a feeding rate of 40 kg / min. During this process, the medium frequency furnace is self-stirred or externally mechanically stirred for 40 min and the reaction temperature is 800℃ to obtain the second aluminum liquid.

[0054] S3, Alloying 2: The remaining potassium fluorotitanate is added to the second aluminum liquid in equal portions at a feeding rate of 40 kg / min. After each addition, the slag must be cleaned before the next addition of potassium fluorotitanate is made. This process is repeated until all the potassium fluorotitanate is added. During this process, the medium frequency furnace is self-stirred or externally mechanically stirred for more than 40 minutes and the reaction temperature is 800℃ to obtain the third aluminum liquid.

[0055] S4. Refining: The third aluminum liquid is transferred into a holding furnace, aluminum-vanadium master alloy is added, and degassing and slag removal are carried out. The refining temperature is 800℃ and the refining time is 100min to obtain aluminum alloy melt.

[0056] S5. Casting: The aluminum alloy melt is rapidly cooled by a horizontal water-cooled wheel-type copper mold or other casting methods at a cooling rate of 50°C to obtain a casting billet.

[0057] S6. Rolling: The cast billet is hot rolled into a 9.5mm round rod at a rolling temperature of 450℃ to obtain an aluminum-titanium-boron rod.

[0058] The aluminum-titanium-boron rods prepared in Examples 1 to 4 were obtained by preparing the rods according to the above preparation method and the relevant parameters shown in Table 1 below.

[0059] Table 1

[0060]

[0061] Detection Example 1

[0062] The aluminum-titanium-boron rods prepared in Examples 1 to 4 were subjected to performance testing. The testing method was based on YS / T447.1-2011 "Alloy wires for grain refinement of aluminum and aluminum alloys - Part 1: Aluminum-titanium-boron alloy wires". The results are shown in Table 2.

[0063] Table 2

[0064]

[0065] As can be seen from Table 2, the average size of TiAl3 in the aluminum-titanium-boron rod provided by the present invention is ≤20μm, the average size of TiB2 is ≤1.8μm, and no TiB2 particle agglomeration is observed in the metallographic structure. At the same time, the oxide inclusions meet the requirements (≤500μm).

[0066] Detection Example 2

[0067] The aluminum-titanium-boron rods prepared in Example 1 and Comparative Example 1 were photographed, and the results were as follows: Figure 1 and Figure 2 In the figure, the gray blocky second phase is TiAl3 particles, the dark gray granular second phase is TiB2 particles, and the black elongated strips are oxide inclusions (with dimensions marked). As can be seen from the figure, the oxide inclusions in the aluminum-titanium-boron rods prepared by the method provided in this invention meet the requirements and do not exhibit TiB2 particle agglomeration.

[0068] In summary, this invention reduces the slag content of the molten aluminum by adding a certain amount of aluminum-vanadium intermediate to aluminum-titanium-boron alloy, thereby increasing the surface tension of the slag through the vanadium in the intermediate and promoting the complete separation of the slag from the molten aluminum. At the same time, by using a process of adding potassium fluorotitanate in stages, smaller TiAl3 particles and a cleaner melt are obtained.

[0069] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing an aluminum-titanium-boron rod with low oxide inclusion content, characterized in that, Includes the following steps: S1. Mix potassium fluoroborate and a portion of potassium fluorotitanate to obtain a mixed salt; S2. Melt the aluminum ingot to obtain the first molten aluminum; S3. Add the mixed salt to the aluminum liquid and stir to obtain a second aluminum liquid; S4. Add the remaining potassium fluorotitanate to the second aluminum liquid and stir. Clean the scum generated on the surface of the second aluminum liquid until the remaining potassium fluorotitanate is added to obtain the third aluminum liquid. S5. Add aluminum-vanadium intermediate alloy to the third aluminum liquid, and then refine, cast and roll in sequence to obtain the aluminum-titanium-boron rod. The mass ratio of potassium fluorotitanate to potassium fluoroborate in the mixed salt is 48:

52. The aluminum-titanium-boron rod contains 0.02~0.10 wt% V; The aluminum-vanadium master alloy is AlV5 or AlV10; the particle size of the potassium fluoroborate and potassium fluorotitanate is 70μm~200μm≥90%.

2. The method for preparing an aluminum-titanium-boron rod with low oxide inclusion content according to claim 1, characterized in that, The aluminum ingot is a remelted aluminum ingot with a purity of 99.7% or higher.

3. The method for preparing an aluminum-titanium-boron rod with low oxide inclusion content according to claim 1, characterized in that, S2 specifically involves melting aluminum ingots and using an inert gas to remove impurities and hydrogen when the temperature reaches above 740°C, thereby obtaining the first molten aluminum.

4. The method for preparing an aluminum-titanium-boron rod with low oxide inclusion content according to claim 1, characterized in that, The remaining potassium fluorotitanate is added to the second aluminum liquid in 2 to 10 portions.

5. The method for preparing an aluminum-titanium-boron rod with low oxide inclusion content according to claim 1, characterized in that, The feeding rate of the mixed salt and the potassium fluorotitanate is 10~60 kg / min.

6. The method for preparing an aluminum-titanium-boron rod with low oxide inclusion content according to claim 1, characterized in that, The stirring time is 10-40 minutes, and the reaction temperature during stirring is 740-850℃.

7. An aluminum-titanium-boron rod prepared by the method for preparing an aluminum-titanium-boron rod with low oxide inclusion content as described in any one of claims 1 to 6.

8. The aluminum-titanium-boron rod according to claim 7, characterized in that, It contains the following components: 2.6~5.5wt% Ti, 0.15~1.2wt% B, 0.02~0.10wt% V, with the balance being Al and unavoidable impurities.

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