Fine distinguishing method for refining capacity of grain refiner

Abstract

The invention discloses a fine distinguishing method for the refining capacity of a grain refiner, and relates to the technical field of grain refiner preparation.The fine distinguishing method for the refining capacity of the grain refiner comprises the following steps that S1, a certain mass of aluminum, titanium and boron is dissolved in molten aluminum, stirred for 30 s and stood for 60 s, then a specific square mold is used for sampling, and the adding amount of aluminum, titanium and boron should be 0.1%; s2, after aluminum, titanium and boron are dissolved, a ceramic foam filter is added to filter molten aluminum, undissolved titanium and boron clusters and oxide inclusions are removed, and the purity of a melt is ensured; s3, a square mold with the inner wall sprayed with a boron nitride coating (smaller than or equal to 50 microns) is used and preheated to 200 DEG C, molten aluminum is injected after moisture is removed, adhesion is avoided, and demolding integrity is improved; according to the fine distinguishing method for the refining capacity of the grain refiner, a traditional conical mold is modified into a common square mold, so that machining is more convenient, meanwhile, errors are reduced, experimental raw materials are saved, and the experimental time is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of grain refiner preparation, in particular to a method for finely distinguishing the refining ability of a grain refiner. Background Art

[0002] Grain refiners are additives used to enhance the grain refining ability of metal materials (such as aluminum and steel). Grain refiners can improve material properties such as strength, hardness, and plasticity. A method for finely distinguishing the refining ability is key to evaluating the effectiveness of different grain refiners. Aluminum-titanium-boron (Al-TiB) wire, as a highly effective grain refiner, is widely used in the aluminum industry, and its refining effect is a key focus for all manufacturers. The existing technology typically evaluates the refining effect of Al-TiB wire using a water-cooled cone die method (known in the industry as the "TP1 test"). However, this test struggles to distinguish grain refiners with a refining ability below 110 μm, making it impossible to screen for refiners with excellent refining ability. Furthermore, the conical die creates a slope on the sample surface, making processing difficult and easily introducing errors during the cutting process. This can affect actual testing and lead to inaccurate grain refining ability evaluation. Therefore, this paper optimizes the existing technology and proposes a method for finely distinguishing the refining ability of grain refiners. Summary of the Invention

[0003] In view of the deficiencies of the prior art, the present invention provides a method for finely distinguishing the refining ability of a grain refiner, which solves the problems raised in the above-mentioned background technology.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for finely distinguishing the refining ability of a grain refiner, comprising the following steps: S1. Dissolve a certain amount of aluminum titanium boron in aluminum liquid, stir for 30 seconds, let it stand for 60 seconds, and then use a specific square mold to take a sample. The addition amount of aluminum titanium boron should be 0.1%; S2. After the aluminum-titanium-boron is dissolved, a ceramic foam filter is added to filter the aluminum liquid to remove undissolved titanium-boron clusters and oxide inclusions to ensure the purity of the melt; S3. Use a square mold with a boron nitride coating (≤50μm) sprayed on the inner wall. Preheat to 200°C to remove moisture before injecting molten aluminum to avoid adhesion and improve demoulding integrity. S4. Install a circulating water cooling jacket (synchronous flow rate 4 L / min) on the outside of the mold, monitor the cooling rate in real time (10-15℃ / s) with an infrared thermometer, and record the temperature curve; S5. After cooling, use a laser scriber to mark 3mm, 5mm, and 7mm circular reference lines on the sample surface (error ≤ 0.05mm). Use a CNC wire cutting machine to cut according to the marks, and retain three cross sections for comparative analysis. S6. After grinding and polishing, the cut surface was ultrasonically etched with 10% NaOH solution. The central 10 mm area was imaged using FE-SEM / EBSD (resolution 1 μm), and the grain size (D50, D90) was calculated using an AI image algorithm. S7. Add crystal orientation distribution function (ODF) analysis to EBSD detection to count the preferred orientation and texture strength of grains and evaluate the effect of refiners on grain anisotropy.

[0005] According to the above technical solution, in S1, the temperature of the molten aluminum is precisely controlled at 720±5°C, and mechanical stirring is adopted (250±50rpm, 30s). After standing, argon protection (0.5 L / min) is introduced to cover the surface of the molten aluminum to form a gas barrier, thereby reducing the formation of oxide slag. The argon protection reduces the inclusions in the melt by more than 30%, thereby improving the accuracy of grain measurement.

[0006] According to the above technical solution, in S2, an alumina-based ceramic foam filter with a pore size of ≤50μm is used and installed in the casting runner. When the aluminum liquid passes through, it intercepts undissolved TiB2 clusters (size >50μm) and Al2O3 inclusions. After filtration, the undissolved TiB2 particles in the melt are reduced by 80%, eliminating the interference of large-sized heterogeneous cores on grain size statistics.

[0007] According to the above technical solution, in S3, a boron nitride (BN) coating is sprayed on the inner wall of the square mold with a thickness controlled at 20-50μm. After spraying, the adhesion is enhanced by high-temperature curing (400℃ / 2h). The BN coating increases the demolding success rate from 70% to 95%, avoiding grain structure damage caused by tearing on the sample surface. At the same time, preheat treatment reduces porosity defects and increases the sample density by 15%.

[0008] According to the above technical solution, in S4, a copper water-cooling jacket is installed on the outside of the mold, a spiral flow channel is designed inside, the water flow is synchronously controlled with the bottom (flow rate 4 L / min), and an infrared thermometer (wavelength range 8-14 μm) collects the sample surface temperature at a frequency of 10 Hz and calculates the cooling rate in real time. Dual-channel cooling reduces the radial temperature gradient of the sample by 40%, improves the uniformity of grain size distribution, and reduces the standard deviation from ±25 μm to ±10 μm.

[0009] According to the above technical solution, in the S5, a 532nm wavelength green laser is used to etch a 50μm-deep circular reference line on the sample surface with a positioning accuracy of ±0.03mm. The section 5mm from the bottom (high cooling rate zone) is preferentially analyzed, while the 3mm (ultra-cooling rate zone) and 7mm (transition zone) section data are retained. By comparing the grain size gradient, multi-section analysis can identify local anomalies (such as surface coarse grains), improving data reliability by 35%.

[0010] According to the above technical solution, in the S6, after etching with 10% NaOH solution for 8 seconds, it was immediately vibrated with an ultrasonic cleaner (frequency 40kHz) for 30 seconds to enhance the grain boundary contrast. The sample was scanned under an accelerating voltage of 15kV and a beam spot of 10nm. The EBSD step size was set to 0.5μm, covering the central 10mm area. The U-Net model was used to segment the grain boundaries, calculate the equivalent circular diameter (ECD) of the grains, and output D50 (median grain size) and D90 (90% of the grains are smaller than this value). The AI ​​recognition accuracy reached ±1μm, and it could distinguish grain differences of <50μm. The D90 value statistics were more sensitive to reflect coarse grain anomalies, and the refiner performance evaluation dimension was more comprehensive.

[0011] According to the above technical solution, in S7, based on the EBSD data, the MTEX ​​toolbox is used to calculate the ODF cross-section diagram (φ2=0°~90°), quantify the preferred orientation strength of the grains such as {001} and {011}, compare the texture strength index (J value) of samples with different refiners, evaluate the difference in grain anisotropy, reveal the effect of the refiner on grain orientation, and provide data support for subsequent rolling / extrusion processes. Through texture analysis, the dispersion uniformity of the refiner in the melt can be indirectly judged.

[0012] The present invention provides a method for finely distinguishing the refining ability of a grain refiner. It has the following beneficial effects:

[0013] (1) The method for finely distinguishing the refining ability of the grain refiner is to modify the traditional conical mold into an ordinary square mold, which makes processing more convenient and provides a more stable structure during the sampling process. For some situations that require plane observation or analysis, the square mold is more conducive to the placement and detection of samples. At the same time, the addition amount of aluminum, titanium and boron is reduced from 0.2% to 0.1%, saving experimental raw materials and shortening the experimental time.

[0014] (2) The method of finely distinguishing the refining ability of the grain refiner minimizes human and environmental interference through dual-channel dynamic cooling, improves the stability of the cooling rate and argon protection, further ensures uniform grain growth conditions, reduces the formation of oxide slag, improves the accuracy of grain measurement, and further reduces the error of the results. At the same time, multi-section analysis can capture local anomalies, avoid single-point sampling deviation, and make the data more representative. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the experimental process of the present invention; Figure 2 This is a schematic diagram of the square mold structure of the present invention; Figure 3 This is a comparison chart of the experimental results of the present invention. DETAILED DESCRIPTION

[0016] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0017] See also Figure 1-Figure 3 One embodiment of the present invention is a method for finely distinguishing the refining ability of a grain refiner, comprising the following steps: S1. Dissolve a certain amount of aluminum titanium boron in aluminum liquid, stir for 30 seconds, let it stand for 60 seconds, and then use a specific square mold to take a sample. The addition amount of aluminum titanium boron should be 0.1%; S2. After the aluminum-titanium-boron is dissolved, a ceramic foam filter is added to filter the aluminum liquid to remove undissolved titanium-boron clusters and oxide inclusions to ensure the purity of the melt; S3. Use a square mold with a boron nitride coating (≤50μm) sprayed on the inner wall. Preheat to 200°C to remove moisture before injecting molten aluminum to avoid adhesion and improve demoulding integrity. S4. Install a circulating water cooling jacket (synchronous flow rate 4 L / min) on the outside of the mold, monitor the cooling rate in real time (10-15℃ / s) with an infrared thermometer, and record the temperature curve; S5. After cooling, use a laser scriber to mark 3mm, 5mm, and 7mm circular reference lines on the sample surface (error ≤ 0.05mm). Use a CNC wire cutting machine to cut according to the marks, and retain three cross sections for comparative analysis. S6. After grinding and polishing, the cut surface was ultrasonically etched with 10% NaOH solution. The central 10 mm area was imaged using FE-SEM / EBSD (resolution 1 μm), and the grain size (D50, D90) was calculated using an AI image algorithm. S7. Add crystal orientation distribution function (ODF) analysis to EBSD detection to count the preferred orientation and texture strength of grains and evaluate the effect of refiners on grain anisotropy.

[0018] In S1, the aluminum liquid temperature was precisely controlled at 720±5°C, and mechanical stirring was used (250±50rpm, 30s). After standing, argon protection (0.5 L / min) was introduced to cover the surface of the aluminum liquid to form a gas barrier and reduce the formation of oxide slag.

[0019] In S2, an alumina-based ceramic foam filter with a pore size of ≤50μm is installed in the pouring channel to intercept undissolved TiB2 clusters (size>50μm) and Al2O3 inclusions when the aluminum liquid passes through. In S3, a boron nitride (BN) coating is sprayed on the inner wall of the square mold with a thickness controlled at 20-50 μm. After spraying, it is cured at high temperature (400°C / 2h) to enhance adhesion and avoid grain structure damage caused by tearing on the sample surface. At the same time, preheat treatment is used to reduce porosity defects.

[0020] In S4, a copper water-cooling jacket is installed on the outside of the mold, and a spiral flow channel is designed inside. The water flow is controlled synchronously with the bottom (flow rate 4 L / min). An infrared thermometer (wavelength range 8-14μm) collects the sample surface temperature at a frequency of 10Hz and calculates the cooling rate in real time. Dual-channel cooling reduces the radial temperature gradient of the sample and improves the uniformity of grain size distribution.

[0021] In S5, a 532nm green laser is used to etch a 50μm-deep circular reference line on the sample surface with a positioning accuracy of ±0.03mm. Priority is given to analyzing the section 5mm from the bottom (the high cooling rate zone), while retaining the 3mm (ultra-cooling rate zone) and 7mm (transition zone) section data. Grain size gradients are compared, and multi-section analysis can identify local anomalies (such as surface coarse grains).

[0022] In S6, after etching with 10% NaOH solution for 8 seconds, the sample was immediately vibrated in an ultrasonic cleaner (frequency 40kHz) for 30 seconds to enhance the grain boundary contrast. The sample was scanned at an accelerating voltage of 15kV and a beam spot of 10nm. The EBSD step size was set to 0.5μm, covering the central 10mm area. The U-Net model was used to segment the grain boundaries, calculate the equivalent circular diameter (ECD) of the grains, and output D50 (median grain size) and D90 (90% of the grains are smaller than this value). The AI ​​recognition accuracy reached ±1μm, and grain differences of <50μm could be distinguished.

[0023] In S7, based on EBSD data, the MTEX ​​toolbox was used to calculate the ODF cross-section (φ2=0°~90°) to quantify the preferred orientation strength of the grains, such as {001} and {011}. The texture strength index (J value) of samples with different refiners was compared to evaluate the differences in grain anisotropy, revealing the effect of refiners on grain orientation and providing data support for subsequent rolling / extrusion processes.

[0024] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for finely distinguishing the refining ability of a grain refiner, characterized in that: The following steps are involved: S1. Dissolve a certain amount of aluminum titanium boron in aluminum liquid, stir for 30 seconds, let it stand for 60 seconds, and then use a specific square mold to take a sample. The addition amount of aluminum titanium boron should be 0.1%; S2. After the aluminum-titanium-boron is dissolved, a ceramic foam filter is added to filter the aluminum liquid to remove undissolved titanium-boron clusters and oxide inclusions to ensure the purity of the melt; S3. Use a square mold with a boron nitride coating (≤50μm) sprayed on the inner wall. Preheat to 200°C to remove moisture before injecting molten aluminum to avoid adhesion and improve demoulding integrity. S4. Install a circulating water cooling jacket (synchronous flow rate 4 L / min) on the outside of the mold, monitor the cooling rate in real time (10-15℃ / s) with an infrared thermometer, and record the temperature curve; S5. After cooling, use a laser scriber to mark 3mm, 5mm, and 7mm circular reference lines on the sample surface (error ≤ 0.05mm). Use a CNC wire cutting machine to cut according to the marks, and retain three cross sections for comparative analysis. S6. After grinding and polishing, the cut surface was ultrasonically etched with 10% NaOH solution. The central 10 mm area was imaged using FE-SEM / EBSD (resolution 1 μm), and the grain size (D50, D90) was calculated using an AI image algorithm. S7. Add crystal orientation distribution function (ODF) analysis to EBSD detection to count the preferred orientation and texture strength of grains and evaluate the effect of refiners on grain anisotropy.

2. The method for finely distinguishing the refining ability of a grain refiner according to claim 1, characterized in that: In S1, the aluminum liquid temperature is precisely controlled at 720±5°C, and mechanical stirring is used (250±50rpm, 30s). After standing, argon gas protection (0.5 L / min) is introduced to cover the aluminum liquid surface to form a gas barrier, reducing the formation of oxide slag. The argon gas protection reduces the inclusions in the melt by more than 30%, improving the accuracy of grain measurement.

3. The method for finely distinguishing the refining ability of a grain refiner according to claim 2, characterized in that: In the S2, an alumina-based ceramic foam filter with a pore size of ≤50μm is used and installed in the casting runner. When the aluminum liquid passes through, it intercepts undissolved TiB2 clusters (size >50μm) and Al2O3 inclusions. After filtration, the undissolved TiB2 particles in the melt are reduced by 80%, eliminating the interference of large-sized heterogeneous cores on grain size statistics.

4. The method for finely distinguishing the refining ability of a grain refiner according to claim 3, characterized in that: In S3, a boron nitride (BN) coating is sprayed on the inner wall of the square mold with a thickness controlled at 20-50 μm. After spraying, the coating is cured at high temperature (400°C / 2h) to enhance adhesion. The BN coating increases the demolding success rate from 70% to 95%, avoiding grain structure damage caused by tearing on the sample surface. At the same time, preheat treatment reduces porosity defects and increases sample density by 15%.

5. The method for finely distinguishing the refining ability of a grain refiner according to claim 4, characterized in that: In the S4, a copper water-cooling jacket is installed on the outside of the mold, and a spiral flow channel is designed inside. The water flow is controlled synchronously with the bottom (flow rate 4 L / min). An infrared thermometer (wavelength range 8-14 μm) collects the sample surface temperature at a frequency of 10 Hz and calculates the cooling rate in real time. Dual-channel cooling reduces the radial temperature gradient of the sample by 40%, improves the uniformity of grain size distribution, and reduces the standard deviation from ±25 μm to ±10 μm.

6. The method for finely distinguishing the refining ability of a grain refiner according to claim 5, characterized in that: In the S5, a 532nm green laser is used to etch a 50μm-deep circular reference line on the sample surface with a positioning accuracy of ±0.03mm. Priority is given to analyzing the section 5mm from the bottom (the high cooling rate zone), while retaining data from sections 3mm (the ultra-cooling rate zone) and 7mm (the transition zone). By comparing grain size gradients, multi-section analysis can identify local anomalies (such as surface coarse grains), improving data reliability by 35%.

7. The method for finely distinguishing the refining ability of a grain refiner according to claim 6, characterized in that: In the S6, after etching with 10% NaOH solution for 8 seconds, it was immediately vibrated in an ultrasonic cleaner (frequency 40kHz) for 30 seconds to enhance the grain boundary contrast. The sample was scanned at an accelerating voltage of 15kV and a beam spot of 10nm. The EBSD step size was set to 0.5μm, covering the central 10mm area. The U-Net model was used to segment the grain boundaries, calculate the equivalent circular diameter (ECD) of the grains, and output D50 (median grain size) and D90 (90% of the grains are smaller than this value). The AI ​​recognition accuracy reached ±1μm, and it could distinguish grain differences of <50μm. The D90 value statistics more sensitively reflected coarse grain anomalies, and the refiner performance evaluation dimension was more comprehensive.

8. The method for finely distinguishing the refining ability of a grain refiner according to claim 7, characterized in that: In S7, based on the EBSD data, the MTEX ​​toolbox was used to calculate the ODF cross-section (φ2 = 0°~90°), quantify the preferred orientation strength of the grains, such as {001} and {011}, and compare the texture strength index (J value) of samples with different refiners. This evaluated the differences in grain anisotropy and revealed the effect of the refiner on grain orientation, providing data support for subsequent rolling / extrusion processes. Texture analysis can also indirectly determine the dispersion uniformity of the refiner in the melt.

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