Detection method of steel nanoscale precipitated phase based on scanning electron microscope

Abstract

The invention provides a method for detecting a steel nanoscale precipitated phase based on a scanning electron microscope. The method comprises the following steps: pretreating a graphite block to obtain a graphite base sample; the sample is polished and then deeply corroded, and a deeply corroded sample is obtained; covering the surface of the deep corrosion sample with an acetone solution, covering the surface with a cellulose acetate membrane, taking out a thin film after the cellulose acetate membrane is dissolved and solidified again to form the thin film, and performing carbon spraying treatment on the inner side surface of the thin film to obtain a cellulose acetate carbon membrane; placing the cellulose acetate carbon film in an acetone solution until cellulose acetate in the cellulose acetate carbon film is completely dissolved to obtain a carbon film; flattening the carbon film in deionized water, fishing out the film by adopting a graphite base sample, and then drying and cleaning to obtain a to-be-detected sample; and placing the to-be-detected sample under a scanning electron microscope to carry out precipitated phase detection statistics. According to the application, the detection of the nanoscale precipitated phase with the size of more than or equal to 10nm can be realized, and meanwhile, the statistical efficiency of the precipitated phase is effectively improved and the accuracy of a statistical result is ensured.

Description

Technical Field

[0001] This application relates to the technical field of steel material detection methods, and particularly relates to a detection method for nano-scale precipitates in steel based on a scanning electron microscope. Background Art

[0002] In the development and production process of steel materials, the expected organizational structure and performance are generally obtained through reasonable design and control of composition, process, and heat treatment, and the core mechanism is the dissolution and precipitation behavior of alloying elements. Therefore, the detection, analysis, and control of precipitates in steel materials to adjust their product quality are essential in the development and production process of steel materials. Currently, the detection and analysis of nano-scale precipitates in steel materials mainly rely on transmission electron microscopes to complete, but the transmission electron microscope cannot achieve automatic statistics of precipitates. This is mainly because the depth of field of the transmission electron microscope is small, and even very small protrusions require manual focusing adjustment of the sample before analysis. Moreover, it is impossible to ensure that the sample is in the same plane during sample preparation. Therefore, when statistically analyzing the sample over a large range, only manual adjustment of each field of view can be performed followed by single-field statistics for each view. At the same time, the maximum sample size for transmission electron microscope testing is a circle with a diameter of 3 mm, and the statistical sample size is limited. The scanning electron microscope can perform large-area statistics and analysis on information such as the composition, morphology, quantity, and size of inclusions in the sample. However, in terms of precipitate analysis, currently, it can only be used for statistics on specific steel samples, with an analysis size of more than 50 nm. Moreover, since the support of the precipitates is the steel matrix during the statistical process, the signal intensity of iron will be very strong, and the obtained precipitate signals will be misjudged as the background. At the same time, the single-point acquisition time needs to be longer than the conventional statistical time, and the total statistical time will become longer. This method also requires corrosion of the sample. When using energy spectroscopy to analyze precipitates and inclusions, the sample needs to be a polished surface. After corrosion, the surface of the sample not only has protrusions of precipitates but also protrusions of interfaces such as tissues and grain boundaries, which seriously affects the accuracy of signal collection, affects the statistical results, and results in poor accuracy of the statistical results. Summary of the Invention

[0003] This application aims to solve the technical problems in the prior art that the method for detecting precipitates in steel materials based on a transmission electron microscope cannot achieve large-area automatic statistics, while the method for detecting precipitates in steel materials based on a scanning electron microscope can only be used for statistical analysis of precipitates with a size of more than 50 nm in specific steel types, and the statistical time is long, and the accuracy of the statistical results is poor. A detection method for nano-scale precipitates in steel based on a scanning electron microscope is proposed to achieve the detection and automatic statistics of nano-scale precipitates with a size of ≥10 nm, and at the same time, improve the statistical efficiency and the accuracy of the statistical results.

[0004] To achieve the above object, this application adopts the following technical solutions: A detection method for nano-scale precipitation phases in steel based on a scanning electron microscope, comprising the following steps: Perform primary cutting on the graphite block, prepare it to a polished state of 1 μm according to metallographic sample preparation, vibratory polishing, and secondary cutting to obtain a graphite-based sample; Among them, the process of the primary cutting is to process a graphite block (or graphite rod) with a purity higher than 99.9% and dense interior into small square graphite with a length, width, and height of 10 mm × 10 mm × 10 mm (or round rod graphite with a diameter of 10 mm). The processed small square graphite / round rod graphite is embedded with a cold embedding mold with a diameter of 30 mm. The small square graphite / round rod graphite is embedded at 1 / 4 of the diameter of the embedding block, and the height is not less than 25 mm. The embedded small square graphite / round rod graphite is placed on a precision cutting machine for primary cutting, and a thickness of 1 mm from the edge is cut off; The process of the metallographic sample preparation is to automatically grind and polish the small square graphite / round rod graphite cut in the first step on an automatic grinding and polishing machine to a polished state of 1 µm according to the standard metallographic sample preparation process; The weight of the auxiliary block used in the vibratory polishing process is 300 g - 500 g, and the polishing time is 50 min - 70 min; After the sample is prepared to a polished state of 5 µm according to metallographic sample preparation, perform deep etching, rinse with running water and dry. During this process, do not wipe the surface of the sample with items such as cotton balls to obtain a deeply etched sample; Cover the surface of the deeply etched sample with acetone solution and then cover it with a cellulose acetate membrane. After the cellulose acetate membrane dissolves in the surface of the deeply etched sample and solidifies again to form a film, take out the film and perform carbon spraying treatment on the side of the film in contact with the deeply etched sample to obtain a cellulose acetate carbon film; Place the cellulose acetate carbon film in acetone solution until the cellulose acetate in the cellulose acetate carbon film is completely dissolved to obtain a carbon film; Flatten the carbon film in water, use the graphite-based sample to fish the film so that the carbon film is completely flat on the surface of the graphite-based sample, and then dry and clean to obtain a sample to be detected; Place the sample to be detected under a scanning electron microscope for precipitation phase detection and statistics; among them, the detection parameters for the scanning electron microscope to perform precipitation phase detection and statistics include: acceleration voltage: 10 kV, energy spectrum output count rate ≥ 50000 cps, equipment acquisition signal: backscattered electrons, brightness and contrast adjustment method: adjust the brightness to 0, gradually increase the contrast, and it is necessary to simultaneously open the image of the backscattered signal and the secondary electron image. When the bright spots in the backscattered image correspond one by one to the precipitation phases in the secondary electron image, and the rest of the backscattered image is black, the values at this time are the brightness and contrast values of the backscattered image during statistics.

[0005] Further, the graphite block is solid graphite with a purity higher than 99.9% and dense interior.

[0006] Further, when performing vibration polishing, a vibration polishing liquid needs to be added to the polishing disc or polishing cloth; the preparation method of the vibration polishing liquid is: pouring an Al2O3 suspension into a KOH solution, magnetically stirring for 1.5 h - 2.5 h, adding dishwashing liquid, and continuing to stir until a uniform emulsion is formed; wherein, the volume ratio of the Al2O3 suspension, the KOH solution, and the dishwashing liquid is 1:1.5:0.1.

[0007] Further, the particle size of the Al2O3 suspension is 0.02 µm.

[0008] Further, the concentration of the KOH solution is 5%.

[0009] Further, the thickness of the graphite-based sample is 1 mm.

[0010] Further, the process of carbon spraying treatment is: the distance between the carbon rod and the surface of the film ≥ 4 cm, the carbon spraying current is 65 nA, the carbon spraying time is: 2 s, and the vacuum degree is: ≤ 9×10 -5 mbar.

[0011] Further, the film fishing process includes: keeping an angle of 150° - 160° between the graphite-based sample and the water surface and slowly inserting it into deionized water along the direction close to the carbon film. After one edge of the carbon film completely adheres to the surface of the graphite-based sample, slowly lift the graphite-based sample on the premise of keeping no displacement between the carbon film and the graphite-based sample. At this time, keep the angle between the graphite-based sample and the water surface at 150° - 160°. After the graphite-based sample with the carbon film attached is completely lifted out of the deionized water surface, use filter paper to absorb the excess deionized water at the edge of the carbon film.

[0012] Further, the drying process is to place the graphite-based sample with the carbon film laid flat in a device with a vacuum degree ≤ 1×10 -4 mbar for vacuum drying for 0.5 h - 2 h.

[0013] Further, the cleaning process is to place the graphite-based sample with the carbon film laid flat in a plasma cleaner and clean it with a mixed gas of hydrogen and oxygen for 5 min - 10 min.

[0014] The beneficial effects of this application are: In this application, by using a processed graphite block as the base sample and adopting the method of extracting the sample to the carbon film with a cellulose acetate membrane, a test sample with a flat surface, free from the interference of the steel matrix, and containing nanoscale precipitates in the sample can be obtained. Then, by adjusting the detection parameters under specific conditions, the large-area automatic statistics of nanoscale precipitates with a size of ≥10 nm can be achieved under a scanning electron microscope, and accurate statistical results can be obtained.

[0015] In this application, a compound of Al2O3 suspension, KOH solution, and dishwashing liquid is used as the vibration polishing liquid. With a specific weight of the auxiliary block and a certain polishing time, the surface of the graphite matrix can be made smooth but slightly convex (within 10 nm), which can not only ensure that the carbon film can be laid flat on the surface of the graphite matrix without breakage and wrinkles, but also improve the adhesion between the carbon film and the graphite substrate without affecting the energy spectrum acquisition efficiency, laying a good foundation for the accuracy of the subsequent test results of the sample to be measured and ensuring the accuracy of the detection results.

[0016] The carbon spraying treatment process adopted in this application can form a dense and moderately thick carbon film on the surface of the thin film, which is convenient for subsequent film fishing and detection and statistics of precipitates.

[0017] The film fishing process adopted in this application can effectively ensure that the carbon film can be laid flat in the graphite matrix, thus ensuring the accuracy of the subsequent detection and statistical results.

[0018] The drying process adopted in this application can improve the adhesion between the carbon film and the surface of the graphite body. The cleaning process can remove trace gases and water on the surface of the carbon film, improve the surface cleanliness of the sample, prevent surface contamination during testing, and improve the conductivity of the sample to avoid thermal drift of the sample, thereby improving the accuracy of the subsequent detection and statistical results. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is the backscattered electron image of the X70MS sample provided in Embodiment 1 of this application after adjusting the brightness and contrast; Figure 2 It is Figure 1 The corresponding secondary electron image; Figure 3 It is the comparison diagram of the minimum precipitate size measured for the X70MS sample provided in Embodiment 1 of this application; Figure 4It is the distribution and morphology diagram of the precipitated phases in the entire statistical area after the statistics of the X70MS sample provided in Embodiment 1 of this application; Figure 5 It is the composition diagram of the precipitated phases corresponding to the X70MS sample provided in Embodiment 1 of this application; Figure 6 It is the size distribution and quantity diagram of the precipitated phases corresponding to the X70MS sample provided in Embodiment 1 of this application; Figure 7 It is the distribution and morphology diagram of the precipitated phases after the statistics of the W310 sample provided in Embodiment 2 of this application; Figure 8 It is the composition diagram of the precipitated phases statistics of the W310 sample provided in Embodiment 2 of this application; Figure 9 It is the size quantity and distribution diagram of the precipitated phases of the W310 sample provided in Embodiment 2 of this application. Detailed implementation manners

[0021] Next, the technical solutions of this application will be described clearly and completely in conjunction with specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative efforts belong to the protection scope of this application.

[0022] Embodiment 1 A detection method for steel nano-scale precipitated phases based on a scanning electron microscope, comprising the following steps: Configure the vibration polishing liquid Measure 500 mL of neutral Al2O3 suspension with a particle size of 0.02 µm using a measuring cylinder and pour it into a beaker, stir it with a magnetic stirrer, then measure 750 mL of KOH solution with a concentration of 5% using a measuring cylinder and pour it into the beaker containing the neutral Al2O3 suspension. After stirring for 2 h, measure 50 mL of dishwashing liquid using a measuring cylinder and pour it into the beaker, and continue to stir for 3 h until a uniform emulsion is obtained.

[0023] Prepare the graphite-based sample Process a graphite block with a purity higher than 99.9% and a dense interior into small cubic graphite with dimensions of 10 mm × 10 mm × 10 mm. Use a hot embedding machine with a diameter of 30 mm to embed the small cubic graphite. The small cubic graphite is embedded at 1 / 4 of the diameter of the embedding block, and the height is not less than 25 mm. Place the embedded small cubic graphite on a precision cutting machine for the first cut, cutting off a thickness of 1 mm from the edge. Automatically grind and polish the small cubic graphite cut for the first time on an automatic grinding and polishing machine according to the standard metallographic sample preparation process to a polished state of 1 µm, and perform vibratory polishing using a vibratory polishing fluid. After polishing, place it on a precision cutting machine for the second cut to cut out a 1-mm-thick slice. Gently break it by hand to remove the surrounding embedding material, obtaining a graphite-based sample with a polished surface and a thickness of 1 mm. Among them, the weight of the auxiliary block used for vibratory polishing is 400 g, and the polishing time is 60 min.

[0024] Among them, the vibratory polishing fluid used in the vibratory polishing process is the vibratory polishing fluid prepared above.

[0025] Prepare the sample to be tested After hot embedding a selected X70MS pipeline steel sample, grind and polish it to a polished state of 5 µm without scratches according to the standard metallographic sample preparation steps. After deep etching the sample, rinse it with running water and quickly dry the surface to obtain a deeply etched sample; Cover the surface of the deeply etched sample with acetone solution and then cover it with a cellulose acetate film. After the cellulose acetate film dissolves on the surface of the deeply etched sample and solidifies again to form a film, take out the film and fix it. Then, place the side of the film in contact with the deeply etched sample facing up in a high-vacuum carbon spraying instrument and perform carbon spraying treatment on the film to obtain a cellulose acetate carbon film; among them, the process of the carbon spraying treatment is: the distance between the carbon rod and the surface of the film is 5 cm, the carbon spraying current is 65 nA, the carbon spraying time is: 2 s, and the vacuum degree is: 5×10 -5 mbar.

[0026] Gently scratch the cellulose acetate carbon film with a blade into a grid size of 4 mm × 4 mm; place the scratched cellulose acetate carbon film in acetone solution until the cellulose acetate in the cellulose acetate carbon film is completely dissolved to obtain a carbon film; at this time, the carbon film is in a curled state in the acetone solution; fish out the curled carbon film and place it in a beaker filled with deionized water. At this time, the curled carbon film will automatically flatten and float on the surface of the deionized water; Use tweezers to hold one corner of the graphite-based sample, and slowly insert the graphite-based sample into deionized water at a position far from the carbon film, keeping the angle between the graphite-based sample and the liquid surface at 150° all the time. When the insertion depth into the water is half of the side length of the graphite-based sample, slowly move the graphite-based sample closer to the flattened carbon film. At this time, keep the line where the graphite-based sample intersects the water surface parallel to one side of the carbon film. After the side of the carbon film adheres to the surface of the graphite-based sample, slowly lift the graphite-based sample upward. At this time, continue to keep the angle between the graphite-based sample and the liquid surface at 150°. After both the carbon film and the graphite-based sample are separated from the deionized water surface, use filter paper to absorb the deionized water around the carbon film on the graphite-based sample; Place the graphite-based sample with the carbon film laid flat into a vacuum device, and keep the vacuum degree at 4×10 -5 mbar. After 1 h, take it out and put it into a plasma cleaner to be cleaned with a mixed gas of hydrogen and oxygen to obtain the sample to be tested; among them, the gas ratio of hydrogen and oxygen in the mixed gas is 1:1, and the cleaning time is 5 minutes.

[0027] Precipitate phase detection and statistics Fix the sample to be tested on the surface of a standard 10-mm circular T-shaped stage of a scanning electron microscope with glue, and apply conductive glue to the connection between the sample to be tested and the T-shaped stage to ensure electrical conduction between the sample to be tested and the T-shaped stage; Place the sample to be tested in a scanning electron microscope for precipitate phase statistics. The statistical parameters are: 1) acceleration voltage 10 kV; 2) energy spectrum output counting rate 65000 cps; 3) the device collects signals as backscattered electrons; 4) working distance 8.5 mm; 5) brightness and contrast adjustment: adjust the brightness to 0 and the contrast to 85%; Set the scanning area to 30 µm×30 µm, magnification 78704, minimum acquisition size 0.01 µm, single-particle pixel points 30, and acquisition time 3 s.

[0028] The final acquisition results are shown in Figures 1-6 . Among them, Figure 1 is the backscattered electron photo of the X70MS sample after adjusting the brightness and contrast for statistics, Figure 2 is Figure 1 the corresponding secondary electron photo, Figure 1 and Figure 2 By comparison, it can be seen that all the precipitate phases in the steel can be identified after adjusting the brightness and contrast. Figure 3 is the minimum precipitate phase size measured for the X70MS sample. It can be seen from Figure 3 that the present application can detect precipitate phases with a minimum size of 10 nm based on a scanning electron microscope. Figure 4 is the distribution and morphology diagram of the precipitate phases in the entire statistical area after the statistics of the X70MS sample, Figure 5 is the composition diagram of the corresponding precipitate phases statistically analyzed for the X70MS sample, Figure 6This is the size distribution and quantity diagram corresponding to the precipitated phases of the X70MS sample. It can be seen from Figures 4-6 that the detection method of this application can quickly analyze and statistically analyze information such as the composition, morphology, and quantity of precipitated phases with a minimum size of 10 nm in steel samples over a large area.

[0029] Example 2 A detection method for nano-scale precipitated phases in steel based on a scanning electron microscope, comprising the following steps: Preparation of a graphite-based sample Process a graphite block with a purity higher than 99.9% and a dense interior into a round graphite rod with a thickness of 10 mm and a diameter of 10 mm. Inlay the round graphite rod with a hot inlay machine with a diameter of 30 mm. The round graphite rod is inlaid at 1 / 4 of the diameter of the inlay block, and the height is not less than 25 mm. Place the inlaid round graphite rod on a precision cutting machine for the first cut, cutting off a thickness of 1 mm from the edge. Polish the round graphite rod cut for the first time automatically on an automatic grinding and polishing machine to a polished state of 1 µm according to the standard metallographic sample preparation process, and perform vibration polishing using a vibration polishing liquid. After polishing, place it on a precision cutting machine for the second cut to cut out a 1 mm thin slice, and gently break it by hand to remove the surrounding inlay material to obtain a graphite-based sample with a polished surface and a thickness of 1 mm. Among them, the weight of the auxiliary block used for vibration polishing is 400 g, and the polishing time is 60 min.

[0030] Among them, the vibration polishing liquid used in the vibration polishing process is the vibration polishing liquid prepared in Example 1.

[0031] Preparation of the sample to be tested After hot inlaying the selected W310 non-oriented silicon steel sample, polish it to a polished state without scratches after polishing to 5 µm according to the standard metallographic sample preparation steps. After deep etching the sample, rinse it with running water and quickly dry the surface to obtain a deeply etched sample; Cover the surface of the deeply etched sample with acetone solution and then cover it with a cellulose acetate film. After the cellulose acetate film dissolves on the surface of the deeply etched sample and solidifies again to form a film, take out the film and fix it. Then, place the surface of the film in contact with the deeply etched sample facing up in a high-vacuum carbon spraying instrument and perform carbon spraying treatment on the film to obtain a cellulose acetate carbon film; among them, the process of the carbon spraying treatment is: the distance between the carbon rod and the surface of the film is 6 cm, the carbon spraying current is 65 nA, the carbon spraying time is: 3 s, and the vacuum degree is: 4×10 -5 mbar.

[0032] Use a blade to gently scratch a 5mm×5mm grid on the cellulose acetate carbon film; place the scratched cellulose acetate carbon film into an acetone solution until the cellulose acetate in the cellulose acetate carbon film is completely dissolved to obtain a carbon film; at this time, the carbon film is in a curled state in the acetone solution; fish out the curled carbon film and place it in a beaker filled with deionized water, and at this time, the curled carbon film will automatically flatten and float on the surface of the deionized water; Use forceps to hold the edge of the graphite-based sample, and slowly insert one side of the graphite-based sample into the deionized water at a position far from the carbon film, keeping the angle between the graphite-based sample and the liquid surface at 160° all the time. When the depth inserted into the water is half of the diameter of the graphite-based sample, slowly move the graphite-based sample closer to the flattened carbon film. At this time, keep the line where the graphite-based sample intersects the water surface parallel to one side of the carbon film. When the edge of the carbon film adheres to the surface of the graphite-based sample, slowly lift the graphite-based sample upward. At this time, continue to keep the angle between the graphite-based sample and the liquid surface at 160°. After the carbon film and the graphite-based sample are both separated from the deionized water surface, use filter paper to absorb the deionized water around the carbon film on the graphite-based sample; Place the graphite-based sample with the carbon film laid flat into a vacuum device, keep the vacuum degree at 4×10 -5 mbar. After 1h, take it out and put it into a plasma cleaner for cleaning with a mixed gas of hydrogen and oxygen to obtain the sample to be tested; among them, the gas ratio of hydrogen and oxygen in the mixed gas is 1:1, and the cleaning time is 5 minutes.

[0033] Precipitate phase detection and statistics Fix the sample to be tested on the surface of a standard 10mm circular T-shaped stage of a scanning electron microscope with glue, and apply conductive glue to the connection between the sample to be tested and the T-shaped stage to ensure conduction between the sample to be tested and the T-shaped stage; Place the sample to be tested in a scanning electron microscope for precipitate phase statistics. The statistical parameters are: 1) acceleration voltage 10kV; 2) energy spectrum output count rate 50000cps; 3) the device collects signals as backscattered electrons; 4) working distance 8.5mm; 5) brightness and contrast adjustment: adjust the brightness to 0 and the contrast to 70%; Set the scanning area to 10µm×20µm, magnification 78704, minimum acquisition size 0.01µm, single particle pixel points 30, and acquisition time 3s.

[0034] The final acquisition results are shown in Figures 7-9 . Among them, Figure 7 is the distribution and morphology diagram of the precipitate phase after statistics of the W310 sample, Figure 8 is the precipitate phase statistical composition diagram of the W310 sample, Figure 9 is the size number and distribution diagram of the precipitate phase of the W310 sample. From Figures 7-9It can be seen that the detection method of the present application can also perform large-area rapid analysis and statistics on information such as the composition, morphology, and quantity of precipitation phases with a minimum size of 10 nm in the W310 non-oriented silicon steel sample.

[0035] The above has introduced in detail a detection method for steel nano-scale precipitation phases based on a scanning electron microscope provided by an embodiment of the present application. Specific examples are used herein to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A detection method for nano-scale precipitation phases in steel based on a scanning electron microscope, characterized in that, It includes the following steps: Perform primary cutting on the graphite block, prepare it to a polished state of 1 μm according to metallographic sample preparation, vibratory polishing, and secondary cutting to obtain a graphite-based sample; Polish the sample to a polished surface state, then perform deep etching, cleaning, and air drying to obtain a deeply etched sample; Cover the surface of the deeply etched sample with acetone solution and then cover it with a cellulose acetate membrane. After the cellulose acetate membrane dissolves in the surface of the deeply etched sample and solidifies again to form a film, take out the film and perform carbon spraying treatment on the side of the film in contact with the deeply etched sample to obtain a cellulose acetate carbon film; Place the cellulose acetate carbon film in acetone solution until the cellulose acetate in the cellulose acetate carbon film is completely dissolved to obtain a carbon film; Flatten the carbon film in deionized water, use the graphite-based sample to fish the film so that the carbon film is completely flat on the surface of the graphite-based sample, and then dry and clean to obtain a sample to be detected; Place the sample to be detected under a scanning electron microscope for precipitation phase detection and statistics.

2. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 1, wherein: The graphite block is solid graphite with a purity higher than 99.9% and dense inside.

3. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 1, characterized in that: During the vibratory polishing, a vibratory polishing liquid needs to be added to the polishing disc or polishing cloth; the preparation method of the vibratory polishing liquid is: pour the Al2O3 suspension into the KOH solution, magnetically stir for 1.5 h - 2.5 h, then add dishwashing liquid and continue stirring until a uniform emulsion is formed; among them, the volume ratio of the Al2O3 suspension, the KOH solution, and the dishwashing liquid is 1:1.5:0.1, the weight of the auxiliary block used in the vibratory polishing process is 300 g - 500 g, and the polishing time is 50 min - 70 min.

4. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 3, wherein: The particle size of the Al2O3 suspension is 0.02 µm.

5. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 1, characterized in that: The thickness of the graphite-based sample is 1 mm.

6. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 1, wherein: The process of the carbon spraying treatment is as follows: the distance between the carbon rod and the surface of the film is ≥ 4 cm, the carbon spraying current is 65 nA, the carbon spraying time is 2 s - 3 s, and the vacuum degree is ≤ 9×10 -5 mbar.

7. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 1, characterized in that: The film fishing process includes: keeping an angle of 150° - 160° between the graphite-based sample and the deionized water surface and slowly inserting it into the deionized water along the direction close to the carbon film. After the carbon film is completely attached to the surface of the graphite-based sample, slowly lift the graphite-based sample while keeping no displacement between the carbon film and the graphite-based sample. At this time, keep the angle between the graphite-based sample and the water surface at 150° - 160°. When the graphite-based sample with the carbon film attached is completely lifted out of the deionized water surface, use filter paper to absorb the excess deionized water.

8. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 1, wherein: The drying process is to place the graphite-based sample with the carbon film laid flat therein in a device with a vacuum degree ≤ 1×10 -4 mbar for vacuum drying for 0.5 h - 2 h.

9. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 1, characterized in that: The cleaning process is to place the graphite-based sample with the carbon film laid flat in a plasma cleaner and clean it with a mixed gas of hydrogen and oxygen for 5 min - 10 min.

10. The detection method of nano-scale precipitation phases in steel based on a scanning electron microscope according to claim 1, characterized in that: The detection parameters for the precipitation phase detection and statistics by the scanning electron microscope include: acceleration voltage: 10 kV, energy spectrum output count rate ≥ 50000 cps, equipment acquisition signal: backscattered electrons, brightness and contrast adjustment method: adjust the brightness to 0, gradually increase the contrast. It is necessary to open the images of the backscattered signal and the secondary electron image at the same time. When the bright spots in the backscattered image correspond one by one to the precipitation phases in the secondary electron image, and the rest of the backscattered image is black, the values at this time are the brightness and contrast values of the backscattered image during statistics.

Images