A new method for measuring the diffusion coefficient of a substance in steel inclusions.

Abstract

To provide a new method for measuring the diffusion coefficient of a substance in an inclusion in steel. [Solution] This method includes the steps of: obtaining experimental material, pre-treating the experimental material, where the experimental material includes a steel sample and inclusions; performing a high-temperature modification experiment on the pre-treated experimental material using a high-temperature confocal apparatus, and analyzing the inclusion components at different times based on the experimental data; obtaining initial conditions for a dynamic model, and estimating the mass transfer coefficient of the inclusions based on the initial conditions and the analysis of the inclusion components. The novel method for measuring the diffusion coefficient of a substance in inclusions in steel provided by the present invention effectively estimates the diffusion coefficient of a substance in the steel molten metal diffusing through the inclusions, thereby providing important basic data for optimizing the steelmaking process. The method of the present invention has important experimental and productive guidance effects and good prospects for widespread application.

Description

[Technical Field]

[0001] This invention belongs to the field of metallurgy, and more particularly to a novel method for measuring the diffusion coefficient of a substance in an inclusion in steel. [Background technology]

[0002] With the continuous increase in user demand for high-quality steel, controlling the content of nonmetallic inclusions in steel has become particularly important. To achieve high purity in steel, inclusions must be precisely monitored and controlled. In killed steel, alumina inclusions are the most common, possessing high melting points and hardness. The presence of large amounts of alumina inclusions in the steel matrix causes stress concentration, seriously affecting the plasticity, toughness, and fatigue resistance of the steel. Simultaneously, large amounts of alumina inclusions accumulate inside the immersion nozzle, causing clogging and significantly hindering the smooth progress of the continuous casting process. Currently, the calcium treatment process is the most common method for resolving alumina inclusions in steel. Calcium treatment can modify alumina inclusions into relatively low-melting-point spherical calcium aluminate inclusions, which are easily removed from the steel solution. Even if small amounts remain, the harm to steel properties is less than that caused by solid alumina inclusions.

[0003] In recent years, metallurgical researchers have developed various dynamic models to effectively control the composition of alumina inclusions in steel, better predicting the shape, size, quantity, and distribution of inclusions during the modification process. A commonly used model is the multilayer unreacted core model, which also takes into account the influence of a certain substance during the diffusion process. Simultaneously, in the process of establishing dynamic models, inclusions in steel are usually assumed to be spherical to simplify calculations. However, in actual production, inclusions usually exist in the steel molten metal in irregular shapes, so there is some room for debate regarding the dynamic parameters and other calculation results ultimately proposed based on this assumption.

[0004] Currently, high-temperature confocal microscopy is being used by many researchers as a new research tool in the field of steel metallurgy to study the collision behavior of inclusions in steel and their melting behavior in slag. However, due to the limitations of high-temperature confocal microscopy experimental methods, there is currently relatively little research on the modification behavior of inclusions. Conventional research has mainly focused on observing in-situ the modification process in which endogenous alumina inclusions in steel change to spherical calcium aluminate inclusions using high-temperature confocal microscopy, and component analysis of the target inclusion at different time points has not been performed. This is because there are several problems with the experimental method: (1) Endogenous alumina inclusions are numerous on the surface of the steel molten metal and undergo collisions, making it extremely difficult to track and observe the modification process of the target inclusion in steel. (2) The accuracy of the start time of modification of alumina inclusions in steel cannot be guaranteed. (3) The operating process is relatively complex and not easy to control. To address the need to predict the component changes of alumina inclusions due to calcium treatment, the present invention provides a new method for measuring the diffusion coefficient of substances in inclusions in steel. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] To solve the above technical problems, the present invention proposes a new method for measuring the diffusion coefficient of a substance in an inclusion in steel, thereby solving the problems of the prior art described above. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides a novel method for measuring the diffusion coefficient of a substance in an inclusion in steel: The experimental material is obtained, and the experimental material is pre-treated, wherein the experimental material includes a steel sample and inclusions. The steps include: performing high-temperature modification experiments on pre-treated experimental materials using a high-temperature confocal apparatus, and analyzing the composition of inclusions at different time points based on the experimental data; Obtaining the initial conditions of the kinetic model and estimating the mass transfer coefficient of the inclusion based on the initial conditions and the inclusion component analysis.

[0007] Optionally, the process of pretreating the steel sample is as follows: After cutting the steel sample into several cylindrical bodies of the same predetermined dimensions, using a UV adhesive to prepare a cold-embedded sample of the steel sample, stepwise polishing and cleaning the prepared steel sample, and after the polishing is completed, transferring it to a container containing alcohol for ultrasonic cleaning.

[0008] Optionally, the predetermined dimensions include height and diameter, the height range is 3 - 5 mm, and the diameter range is 5 - 10 mm.

[0009] Optionally, the process of pretreating the inclusion is as follows: Obtaining slag containing the components required for the experiment, pulverizing and mixing to obtain a powdered preheated slag, compression molding the powdered preheated slag into a disk of a predetermined size, heating the disk to prepare a preliminarily melted slag, crushing and sorting the preliminarily melted slag, and screening out inclusion particles that meet the dimensional conditions. Here, the predetermined dimensional conditions include the dimension and the error of the inclusion particles for each group, the dimension is 100 - 300 μm, and the error between the dimensions of the inclusion particles for each group does not exceed 40 μm.

[0010] Optionally, when heating to prepare the preliminarily melted slag, control the holding temperature to be 50 - 100 °C higher than the complete melting temperature of the slag, and control the holding time to be 20 - 30 minutes.

[0011] Optionally, performing a high-temperature modification experiment on the pretreated experimental material using a high-temperature confocal facility, and the process of analyzing the components of the inclusion at different times based on the experimental data is as follows: Through preliminary experiments, the reaction time corresponding to the inclusion particles for each group is obtained. Based on the reaction time, a high-temperature reforming experiment is carried out on the experimental material after pretreatment. When the reaction time is reached, the temperature is decreased by filling helium gas into the heating furnace. After the experiment, the experimental material is taken out, and the components of the inclusion particles are analyzed using a scanning electron microscope to obtain the inclusion components. Here, the temperature decrease rate is controlled at 300 - 1000 °C / min.

[0012] Optionally, the initial conditions of the kinetic model include the density and volume of the inclusion particles. Here, the density of the inclusion particles is calculated based on the relationship between the oxide molar volume and temperature and the following formula:

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[0013] Optionally, the volume calculation formula of the inclusion particles is as follows:

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Advantages of the Invention

[0014] Compared to conventional technology, the present invention has the following advantages and technical effects.

[0015] This invention discloses a novel method for measuring the diffusion coefficient of a substance in inclusions in steel. First, in the preparation of experimental materials, the experimental materials include a steel sample and inclusions. Here, the steel sample needs to be cut into columnar pieces of predetermined dimensions, and the inclusion particles need to be prepared by heating a predetermined mixture of slag using a high-temperature facility to prepare pre-molten slag, crushing and sorting the pre-molten slag to select inclusion particles of appropriate dimensions. Next, a high-temperature modification experiment is performed on the experimental sample prepared using a high-temperature laser confocal facility, and the composition of the inclusions at different times is analyzed using an electron microscope. Finally, the initial conditions necessary for a dynamic model are collected, and the mass transfer coefficient of the substance in the inclusions is estimated. This invention simulates a steel-liquid-inclusion reaction experiment using a high-temperature confocal facility, analyzes the composition of the inclusions at different times in combination with an electron microscope, and collects the parameters necessary for the model. Finally, the mass transfer coefficient of the substance in the inclusions is estimated. The calculation results are close to those of previous studies, demonstrating the feasibility of the experiment. The method provided by this invention has important experimental and productive guidance effects and good prospects for widespread application. [Brief explanation of the drawing]

[0016] The drawings, which constitute part of this application, are provided to further enhance the understanding of this application, and the exemplary embodiments and descriptions thereof are for illustrative purposes only and do not constitute an unreasonable limitation of this application. In the drawings: [Figure 1] This is a schematic diagram of the preparation and chemical analysis of steel samples according to an embodiment of the present invention. [Figure 2] This is a schematic diagram of the preparation flow of inclusion particles according to an embodiment of the present invention. [Figure 3] This is a schematic diagram showing the overall process of change of inclusion particles on a steel surface according to an embodiment of the present invention. [Figure 4] This is a schematic diagram showing the change over time in the inclusion particle components according to an embodiment of the present invention. [Figure 5]This is a schematic diagram showing the projection of liquid inclusions on a solid steel surface and their shape on the solid surface according to an embodiment of the present invention. [Figure 6] In steel according to an embodiment of the present invention

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[0017] Where there is no contradiction, the embodiments and features of the present application can be combined with each other. The present application will now be described in detail with reference to the drawings, in relation to the embodiments.

[0018] The steps shown in the flowchart can be executed on a computer system, such as a set of computer executable instructions. While the flowchart shows a logical sequence, in some cases, the steps illustrated or described may be executed in a different order.

[0019] Example 1

[0020] As shown in Figure 12, this embodiment provides a novel method for measuring the diffusion coefficient of a substance in a steel inclusion. Here, we provide an example of measuring the mass transfer coefficient of CaO in CaO-Al2O3-MgO-SiO2 inclusion particles, and the specific operating procedure is as follows: S1: In the preparation of experimental materials, the experimental materials include steel samples and inclusions. Here, the steel samples need to be cut into columnar bodies of predetermined dimensions, and the inclusion particles need to be prepared by heating slag of a predetermined composition using high-temperature equipment to prepare pre-molten slag, crushing and sorting the pre-molten slag to select inclusion particles of appropriate dimensions. S2: High-temperature modification experiments were conducted using a high-temperature laser confocal facility, and the composition of inclusions at different time points was analyzed using an electron microscope. S3: Collect the initial conditions necessary for the dynamics model and estimate the mass transfer coefficient of the material in the inclusions.

[0021] In a preferred embodiment, the steel sample in step S1 is selected as industrial Al-deoxidized steel, the specific composition of which is shown in Table 1. Several cylindrical pieces of Al-deoxidized steel are cut into 5 mm diameter and 3 mm high. To obtain a clear image when observing the steel sample under a high-temperature laser confocal microscope, the top and bottom surfaces of the sample must be kept strictly parallel. The steel sample is cold-embedded using UV adhesive, and then the steel sample is polished stepwise using sandpaper of different grits (300#, 600#, 800#, 1200#, 2400#), followed by cleaning with alcohol. Next, the sample is polished using 8 μm and 1 μm polishing solutions, and finally, the polished steel sample is transferred to a beaker containing alcohol, and the beaker is washed in an ultrasonic cleaner for 5 minutes to thoroughly remove any remaining impurities and contaminants from the surface. The preparation and chemical analysis plan for the steel sample is shown in Figure 1.

[0022] [Table 1]

[0023] In a preferred embodiment, the main components of the inclusion particles in step S1 are CaO, Al2O3, MgO, and SiO2. First, CaO (national drug, purity ≥ 98%), Al2O3 (national drug, purity ≥ 99%), SiO2 (national drug, purity ≥ 99%), and MgO (national drug, purity ≥ 99%) reagents are prepared in predetermined ratios to obtain a slag of the components necessary for the experiment. This is placed in a quartz polishing crucible, and operations such as polishing and mixing are performed to ensure that the components of the preheated slag are uniform. Next, the powder sample is placed in a specific pressure mold, and appropriate pressure is applied to compress and mold the powder into a disc shape with a diameter of 10 mm and a height of 3 mm. Finally, the platinum crucible is placed in the heating chamber of a high-temperature confocal microscope (CSLM), melted at 1600°C in the CSLM heating chamber, held for 20 minutes, and a uniform molten slag component is obtained. Subsequently, the slag sample required for the experiment was rapidly cooled at 1200°C per minute using He gas, preventing the crystallization of the slag sample from affecting the initial composition of the subsequent inclusion particles and bringing them closer to the pre-experiment slag composition. The inclusion particles were analyzed using XRF, and their CaO, Al2O3, MgO, and SiO2 content was found to be 55.50%, 29.77%, 7.98%, and 6.75%, respectively. Finally, the platinum crucible was removed, and the pre-molten slag inside the crucible was crushed using pointed stainless steel tweezers. Particles of appropriate size were selected from these fragments to be used as inclusion particles for the subsequent CSLM experiment. The specific procedure is shown in Figure 2.

[0024] In a preferred embodiment, during the high-temperature modification experiment in step S2, as the temperature rises to 1732.4K, the inclusion particles begin to melt, and their irregular edges gradually become smoother. Further heating to 1786.6K causes the inclusion particles to melt further, and their shape changes to a spherical form. When the temperature reaches 1857.1K, the steel surface placed beneath the slag begins to melt, and the slag begins to float on the surface of the molten steel. This is the start time of the reaction between the inclusions and the molten steel, after which the temperature is controlled and the reaction time is recorded. Figure 3 shows the changes in the inclusion particles on the steel surface throughout the entire process. To prevent the inclusion particles from moving too quickly and leaving the observation range, the argon gas flow rate should be reduced during the experiment to avoid violent waves on the molten steel surface. Once the reaction time reaches the target time, the cooling program is started, and He gas is introduced into the heating furnace to achieve a rapid temperature drop. Subsequently, the steel sample is removed, and the components of the inclusion particles are analyzed using a scanning electron microscope. Throughout the entire transition process, the steel sample is stored in an alcohol bottle to avoid surface contamination. Throughout the high-temperature confocal experiment, the high-temperature confocal microscope and scanning electron microscope must be operated sequentially and repeatedly, with only the reaction time between the inclusions and the steel solution being changed. Figure 4 shows the time-dependent changes in the inclusion particle components.

[0025] Furthermore, the initial conditions of the dynamics model include the density and volume of the inclusion particles. Here, the density of the inclusion particles is calculated based on the relationship between the oxide molar volume and temperature and the following equation:

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[0026] Furthermore, the formula for calculating the volume of the inclusion particles is as follows:

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[0027] In a preferred embodiment, the calculation of the inclusion particle volume, which is an initial condition for the dynamic model in step S2, is based on a literature search, and the contact angle between the liquid inclusion particles and the solid steel is 83.18°. Using equation (3), the volume of the liquid inclusion particles is calculated to be 1.87 × 10⁻⁶. -11 m 3 Figure 5 shows the projection of liquid inclusions on the solid steel surface and their shape on the solid surface.

[0028] In a preferred embodiment, the calculation of the inclusion particle density, which is the initial condition for the dynamic model in step S2, is performed by substituting the inclusion particle components measured by XRF into equations (1) and (2). After calculation, the density of liquid inclusion particles is 2891 kg·m³. -3 This is the result.

[0029] Specifically, the relationship between the molar volume of oxide and temperature T is shown in Table 2.

[0030] [Table 2]

[0031] In a preferred embodiment, the estimation of the mass transfer coefficient of the substance in the inclusion in step S3 is based on an unreacted core model. Due to the high [Al] content in the molten steel, boundary layer diffusion of [Al] on the molten steel side of the inclusion does not constitute a limiting link. At the same time, since chemical reactions at the interface are usually fast, the limiting link in this reaction process may be mass transfer of CaO or Al2O3 within the inclusion particles. Assuming that the rate-determining step of the reaction is the diffusion of CaO within the inclusion, its mass transfer rate is as follows:

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[0032] The experimental results are substituted into Equation 6 and a linear fitting is performed. Similarly, the diffusion coefficient of Al2O3 in the inclusions is also fitted. The fitting results for the diffusion coefficients of CaO and Al2O3 in the inclusions are shown in Figures 6 and 7. It was found that the logarithm of the change in CaO content in the inclusions shows a linear relationship with the reaction time, indicating that the limiting link of the inclusions is the diffusion coefficient of CaO in the inclusions, and the diffusion coefficient obtained by calculation is approximately 3.77 × 10⁻⁶. -6 m·s -1 That is the case.

[0033] Example 2

[0034] The technical solution proposed in this invention is a method for measuring the diffusion coefficient of a substance in an inclusion in steel. Here, we will give an example of measuring the mass transfer coefficient of SiO2 in CaO-Al2O3-MgO-SiO2 inclusion particles, and the specific operating procedure is as follows: S1: In the preparation of experimental materials, the experimental materials include steel samples and inclusions. Here, the steel samples need to be cut into columnar bodies of predetermined dimensions, and the inclusion particles need to be prepared by heating slag of a predetermined composition using high-temperature equipment to prepare pre-molten slag, crushing and sorting the pre-molten slag to select inclusion particles of appropriate dimensions. S2: High-temperature modification experiments were conducted using a high-temperature laser confocal facility, and the composition of inclusions at different time points was analyzed using an electron microscope. S3: Collect the initial conditions necessary for the dynamics model and estimate the mass transfer coefficient of the material in the inclusions.

[0035] Preferably, the steel sample in step S1 is an Al-deoxidized steel smelted in the laboratory, the specific composition of which is shown in Table 3. Several cylindrical pieces of Al-deoxidized steel with different content are cut into 5 mm diameter and 3 mm height shapes. In order to obtain a clear image when observing the steel sample under a high-temperature laser confocal microscope, the top and bottom surfaces of the sample must be kept strictly parallel. The steel sample is cold-embedded using UV adhesive, and the steel sample is polished stepwise using sandpaper of different grits (300#, 600#, 800#, 1200#, 2400#), and then washed with alcohol. Next, the sample is polished using 8 μm and 1 μm polishing solutions, and finally the polished steel sample is transferred to a beaker containing alcohol, and the beaker is washed in an ultrasonic cleaner for 5 minutes to thoroughly remove any remaining impurities and contaminants from the surface.

[0036] [Table 3]

[0037] Preferably, the main components of the inclusion particles in step S1 are CaO, Al2O3, and SiO2. First, CaO (national pharmaceutical, purity ≥ 98%), Al2O3 (national pharmaceutical, purity ≥ 99%), and SiO2 (national pharmaceutical, purity ≥ 99%) reagents are prepared in predetermined ratios to obtain a slag containing the components necessary for the experiment. This is placed in a quartz polishing crucible, and operations such as polishing and mixing are performed to ensure that the components of the preheated slag are uniform. Next, the powder sample is placed in a specific pressure mold, and appropriate pressure is applied to compress and mold the powder into a disc shape with a diameter of 10 mm and a height of 3 mm. Finally, the platinum crucible is placed in the heating chamber of a high-temperature confocal microscope (CSLM), melted at 1600°C in the CSLM heating chamber, and held for 20 minutes to obtain a uniform molten slag component. Subsequently, the slag sample required for the experiment was rapidly cooled at 1200°C per minute using He gas, preventing the crystallization of the slag sample from affecting the initial composition of the subsequent inclusion particles and bringing them closer to the pre-experiment slag composition. The inclusion particles were analyzed using XRF, and their CaO, Al2O3, and SiO2 content was found to be 17.02%, 39.22%, and 43.75%, respectively. Finally, the platinum crucible was removed, and the pre-molten slag inside the crucible was crushed using pointed stainless steel tweezers. Particles of appropriate size were selected from among them to be used as inclusion particles for the subsequent CSLM experiment.

[0038] Preferably, the high-temperature modification experiment in step S2 is performed on steels with different aluminum content and inclusion particles of a predetermined size. Figure 8 shows the effect of different aluminum content steels on the changes in the inclusion particle composition.

[0039] Preferably, the calculation of the inclusion particle volume, which is the initial condition for the dynamic model in step S2, is based on a literature review, and the contact angle between the liquid inclusion particles and the solid steel is 36°. Using Equation 3, the volumes of the three groups of liquid inclusion particles are 6.64 × 10⁻⁶ each. -13 m 3 , 6.60×10 -13 m 3 and 6.31 × 10 -13 m 3 This is the result.

[0040] Preferably, the calculation of the inclusion particle density, which is the initial condition for the dynamic model in step S2, is performed by substituting the inclusion particle components measured by XRF into equations (1) and (2). After the calculation, the density of liquid inclusion particles is 2817.4 kg·m³. -3 This is the result.

[0041] Preferably, the estimation of the mass transfer coefficient of the substance in the inclusion in step S3 is based on an unreacted core model. Due to the high [Al] content in the molten steel, boundary layer diffusion of [Al] on the molten steel side of the inclusion does not constitute a limiting link. At the same time, since chemical reactions at the interface are usually fast, the limiting link in this reaction process may be mass transfer of SiO2 or Al2O3 within the inclusion particles. Assuming that the rate-determining step of the reaction is the diffusion of SiO2 within the inclusion, the mass transfer rate is as follows:

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[0042] Substitute the experimental results into Equation 9 and perform a linear fitting. Similarly, fit the diffusion coefficient of Al2O3 in the inclusions. The fitting results for the diffusion coefficients of SiO2 and Al2O3 in the inclusions are shown in Figures 9, 10, and 11. Experiments revealed that in experiments of different groups, the logarithm of the change in SiO2 content in the inclusions showed a linear relationship with the reaction time, indicating that the limiting link of the inclusions is the diffusion coefficient of SiO2 in the inclusions. The diffusion coefficients obtained by calculation are 6.38 × 10⁻⁶ each. -8 m·s -1 , 7.13×10 -8 m·s -1 and 8.38 × 10 -8 m·s -1 The result was significantly different from values ​​in previous research literature. Since the reduction reaction of SiO2 by Al is an exothermic reaction, in the high-temperature experimental process, as the temperature rises, the steel near the inclusion particles begins to melt first. However, at this point, the contact area between the molten steel and the inclusions is small, and as a result, the calculated diffusion coefficient of SiO2 in the inclusion particles becomes relatively small. Therefore, this experimental method cannot be applied to the study of mass transfer coefficients in which the molten steel-inclusion particle reaction is exothermic.

[0043] The above are merely preferred specific embodiments of the present application; however, the scope of protection of the present application is not limited thereto. Any changes or substitutions that a person skilled in the art could easily conceive of within the technical scope disclosed herein are also included within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the scope of protection of the claims.

Claims

1. A method for measuring the diffusion coefficient of a substance in an inclusion in steel, The experimental material is obtained, and the experimental material is pre-treated, wherein the experimental material includes a steel sample and inclusions. The steps include: performing high-temperature modification experiments on pre-treated experimental materials using a high-temperature confocal apparatus, and analyzing the composition of inclusions at different time points based on the experimental data; This includes the steps of obtaining initial conditions for a dynamic model and estimating the mass transfer coefficient of the inclusions based on the initial conditions and inclusion component analysis, The initial conditions for the dynamic model include the density and volume of the inclusion particles, where the density of the inclusion particles is calculated based on the relationship between the oxide molar volume and temperature and the following equation: [Math 1] [Math 2] where ρ ｌｉｑｕｉｄ ｓｌａｇ is the density of the liquid molten slag, kg·m －３ , x ＭＯ is the mass percentage of different oxides in the slag, wt%, ρ ＭＯ is the density of different oxides in the slag, kg·m －３ , M ＭＯ is the molar mass of different oxides in the slag, kg·mol －１ , Z ＭＯ is the molar volume of different oxides in the slag, m ３ ·mol －１ , The formula for calculating the volume of inclusion particles is as follows: [Math 3] V is the volume of the liquid inclusion particles, m －３ A method for measuring the diffusion coefficient of a substance in an inclusion in steel, characterized in that R is the radius of the liquid inclusion particles after they have been spread on the surface of a steel sample, and m and θ are the contact angles between the liquid inclusion particles and the solid steel.

2. The process for pre-treating the steel sample is as follows: A method for measuring the diffusion coefficient of a substance in an inclusion in steel, as described in claim 1, characterized by comprising cutting a steel sample into several columnar bodies of the same predetermined dimensions, preparing a cold-embedded steel sample using a UV adhesive, polishing and cleaning the prepared steel sample in stages, and after polishing is complete, transferring it to a container containing alcohol and performing ultrasonic cleaning.

3. A method for measuring the diffusion coefficient of a substance in an inclusion in steel according to claim 2, characterized in that the predetermined dimensions include height and diameter, with the height range being 3 to 5 mm and the diameter range being 5 to 10 mm.

4. The process for pre-treating the aforementioned inclusions is as follows: A method for measuring the diffusion coefficient of a substance in an inclusion in steel according to claim 1, comprising: obtaining slag containing the components necessary for the experiment; crushing and mixing it to obtain powdered preheated slag; compressing the powdered preheated slag into a disc of a predetermined size; heating the disc to prepare pre-molten slag; crushing and sorting the pre-molten slag and sieving out inclusion particles that meet dimensional conditions, wherein the predetermined dimensional conditions include the dimensions and the error of inclusion particles for each group, the dimensions being 100 to 300 μm, and the error between the dimensions of inclusion particles for each group not exceeding 40 μm.

5. A method for measuring the diffusion coefficient of a substance in an inclusion in steel, as described in claim 4, characterized in that when raising the temperature to prepare a pre-molten slag, the holding temperature is controlled to be 50 to 100°C higher than the complete melting temperature of the slag, and the holding time is controlled to be 20 to 30 minutes.

6. The process of performing high-temperature modification experiments on pre-treated experimental materials using a high-temperature confocal apparatus, and analyzing the composition of inclusions at different time points based on the experimental data, is as follows: A method for measuring the diffusion coefficient of a substance in an inclusion in steel according to claim 1, characterized in that a preliminary experiment is conducted to obtain the reaction time corresponding to the inclusion particles for each group, a high-temperature modification experiment is performed on the pre-treated experimental material based on the reaction time, when the reaction time is reached, the temperature is lowered by filling the heating furnace with helium gas, the experimental material is removed after the experiment, the components of the inclusion particles are analyzed using a scanning electron microscope to obtain the inclusion components, wherein the cooling rate is controlled to 300 to 1000°C / min.

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