Ultrafine-grained oxide dispersion strengthened steel ebsd sample and method for producing same

Abstract

This invention discloses an ultrafine-grained oxide dispersion strengthened steel (EBSD) sample and its preparation method. The main steps of the preparation method include: electropolishing the ultrafine-grained oxide dispersion strengthened steel to obtain the ultrafine-grained oxide dispersion strengthened steel EBSD sample; the specific parameters of the electropolishing are: the temperature of the electropolishing solution is -30℃ to -10℃, polishing is first performed with a microcurrent of 0.1-0.3A for 10-30s, and then the current is increased to 0.6-1.0A for 10-30s; the electropolishing solution is a mixed solution composed of perchloric acid and ethanol, wherein the volume percentage of perchloric acid is 6-12%. This preparation method, through segmented electrolysis, shortens the electropolishing time while improving the quality of the EBSD sample, can identify ultrafine grains with a high calibration rate, and has good results, providing a good foundation for quantitative or qualitative research on the crystal information of ultrafine-grained oxide dispersion strengthened steel.

Description

Technical Field

[0001] This invention belongs to the field of metal material surface polishing technology, and specifically relates to a method for preparing an ultrafine grain oxide dispersion strengthened steel EBSD sample, and also relates to the ultrafine grain oxide dispersion strengthened steel EBSD sample obtained by the preparation method. Background Technology

[0002] In scanning electron microscopy (SEM), electron imaging can obtain the surface morphology of materials, and energy dispersive spectroscopy (EDS) can obtain the compositional distribution. Although electron backscattering (EBSD) technology started later, it has developed rapidly because it can obtain structural and orientation information of materials, especially suitable for characterizing micron-scale structures. EBSD technology can characterize crystal information from multiple perspectives, such as phase fraction statistics, ultrafine grain identification, crystal orientation, grain boundary distribution, recrystallization, and grain deformation. It can also be combined with SEM to analyze microstructure and crystal information, and therefore is widely used in qualitative and quantitative research on materials.

[0003] Oxide dispersion strengthened (ODS) steel is considered an important candidate structural material for nuclear reactors due to its excellent high-temperature creep resistance and radiation resistance. Typically, this material is prepared using powder metallurgy methods, exhibiting a mixed distribution of micron- and ultrafine grains. Micron-grains improve the material's plasticity, while ultrafine grains enhance its strength; both significantly influence the material's mechanical properties. Metallurgical microscopy, limited by its magnification and optical imaging methods, struggles to quantitatively and qualitatively study the crystalline information of this material. Therefore, EBSD technology can address these limitations.

[0004] However, due to the stringent requirements of EBSD data acquisition in sample preparation, different samples typically require different preparation methods. Currently, there are EBSD sample preparation processes for materials such as martensitic stainless steel and ferritic stainless steel, achieving a calibration rate of over 95%. However, these existing EBSD sample preparation processes cannot be used for preparing EBSD samples of ultrafine-grained oxide dispersion strengthened steel. The main reasons are: ① Oxide dispersion strengthened steel is formed by solid-state sintering of powder, typically at temperatures below 1150℃. Due to defects such as sintering interfaces and pores in powder sintered samples, the calibration rate of EBSD samples for ODS steel is usually low. Furthermore, its grain boundary bonding is weaker than that of ordinary metals, resulting in a significant difference in the number of grain boundaries between ultrafine-grained and micron-grained regions, leading to different resistance to chemical and mechanical corrosion in different regions; ② Different grain sizes: conventional materials have very large grains, while ultrafine-grained materials have grain sizes below 500nm; ③ Materials such as 9Cr-ODS steel have a two-phase structure, with a microstructure mainly consisting of martensite and residual ferrite, resulting in an uneven microstructure. The above factors make it difficult to prepare EBSD samples of ultrafine-grained oxide dispersion strengthened steel. Summary of the Invention

[0005] In view of this, the present invention needs to provide a method for preparing EBSD samples of ultrafine grain oxide dispersion strengthened steel. This preparation method can improve the quality of EBSD samples, identify ultrafine grains, and has a high calibration rate.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a method for preparing an EBSD (Extra-fine Grained Oxide Dispersion Strengthening) steel sample, comprising the following steps:

[0008] Electrolytic polishing was performed on ultrafine-grained oxide dispersion strengthened steel to obtain ultrafine-grained oxide dispersion strengthened steel EBSD samples;

[0009] The specific parameters for the electropolishing are as follows: the temperature of the electropolishing solution is -30℃ to -10℃; polishing is first performed with a microcurrent of 0.1-0.3A for 10-30 seconds, and then the current is increased to 0.6-1.0A for another 10-30 seconds; the electropolishing solution is a mixed solution of perchloric acid and ethanol, wherein the volume percentage of the perchloric acid is 6-12%.

[0010] A further approach includes a mechanical polishing step prior to electropolishing.

[0011] A further approach includes mechanical polishing and vibratory polishing steps prior to electropolishing.

[0012] In a further embodiment, the mechanical polishing process specifically involves cutting ultrafine-grained oxide dispersion reinforced steel into squares, sanding them with sandpaper, and then polishing them with water-soluble polishing paste to achieve a scratch-free mirror finish.

[0013] In a further embodiment, the sanding is performed using 400#, 800#, 1200#, 1500#, and 2000# sandpaper in sequence.

[0014] In a further embodiment, the particle size of the water-soluble polishing paste is 0.1-0.25 μm.

[0015] A further embodiment of the vibration polishing process involves immersing the sample surface in a polishing agent and vibrating it for 5-10 hours, wherein the pressure exerted on the sample during the vibration polishing process is 0.05-0.15 kg / cm². 2 .

[0016] In a further embodiment, the polishing agent is a SiO2 polishing agent.

[0017] In a further embodiment, during the electropolishing process, the polished surface of the sample is parallel to the cathode plate, and the working distance between the polished surface and the cathode plate is 4-7 cm.

[0018] The present invention further provides an ultrafine grain oxide dispersion strengthened steel EBSD sample, characterized in that it is prepared by the preparation method described above.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] In this invention, ultrafine-grained oxide dispersion strengthened steel (EBSD) samples were prepared using an electrolytic polishing process. The segmented, two-stage electrolysis shortened the polishing time and effectively identified the ultrafine grains. The calibration rate of the ultrafine-grained oxide dispersion strengthened steel (EBSD) samples reached over 85%.

[0021] This invention is applicable to various metal samples with ultrafine grains and mixed grains, can improve the quality of EBSD samples, and is simple to operate and low in cost. Attached Figure Description

[0022] Figure 1 The secondary electron image and IPF plot of 9Cr-ODS steel obtained in Comparative Example 1;

[0023] Figure 2 The secondary electron image and IPF plot of 9Cr-ODS steel obtained in Comparative Example 2;

[0024] Figure 3 The images shown are secondary electron images and IPF plots obtained from the 9Cr-ODS steel in Example 1.

[0025] Figure 4 The secondary electron image and IPF plot of 9Cr-ODS steel obtained in Comparative Example 3;

[0026] Figure 5 The secondary electron image and IPF plot of 9Cr-ODS steel obtained in Comparative Example 4;

[0027] Figure 6 The images shown are secondary electron images and IPF plots obtained from the 9Cr-ODS steel in Example 4.

[0028] Figure 7 This is a statistical chart of grain size of 9Cr-ODS steel collected at different time points in Example 4. Detailed Implementation

[0029] The embodiments of the present invention are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0031] The first aspect of this invention provides a method for preparing an ultrafine-grained oxide dispersion strengthened (ODS) steel sample. Here, ultrafine grains refer to grains with a size ≤ 500 nm. The oxide dispersion strengthened (ODS) steel is a conventional definition in the art, and conventional ODS steels in the art are applicable to the preparation method of the EBSD sample described herein, and will not be specifically elaborated upon here.

[0032] The preparation method includes an electropolishing step, the main purpose of which is to improve the surface smoothness of the sample and remove surface stress. The specific process is as follows:

[0033] The temperature of the electropolishing solution is -30℃ to -10℃. The polishing surface of the sample is parallel to the cathode plate, and the working distance between the polishing surface and the cathode plate is controlled at 4-7cm. Pre-polishing is first performed with a microcurrent of 0.1-0.3A for 10-30s to smooth the sample surface. Then, the current is increased to 0.6-1.0A for 10-30s to remove the stress layer of the sample. The electropolishing solution is a mixed solution of perchloric acid and ethanol, with the volume percentage of perchloric acid being 6-12%. In some specific embodiments of the present invention, preferably, pre-polishing is performed with a microcurrent of 0.25A for 10s, followed by polishing with the current increased to 0.75A for 20s.

[0034] Because fine grains contain numerous precipitates at grain boundaries, prolonged high-current electrolysis of the matrix will expose these precipitates, leading to grain boundary separation and reduced sample recognition rate. Therefore, this invention employs a segmented electrolysis method. First, micro-current electrolytic pre-polishing smooths the sample surface, then the current intensity is increased to eliminate the stress layer on the sample surface. This significantly improves the quality of ultrafine-grained oxide dispersion strengthened steel EBSD samples while greatly reducing the time required for electrolytic polishing.

[0035] A further embodiment of the invention can be understood as including a mechanical polishing step before electrolytic polishing. The specific parameters of this mechanical polishing are not particularly limited and can be adjusted according to actual conditions. According to an embodiment of the invention, the mechanical polishing described herein is mirror polishing, the purpose of which is to remove scratches and contaminants from the sample surface. The specific process is as follows: the ultrafine-grained oxide dispersion-strengthened steel is cut into cubes, sanded with sandpaper, and then polished with a water-soluble polishing paste to achieve a scratch-free mirror surface. Preferably, 400#, 800#, 1200#, 1500#, and 2000# sandpaper are used sequentially for sanding, improving polishing efficiency while eliminating scratches from previous passes. The selection of the water-based polishing paste is not particularly limited and can be chosen as needed; preferably, a polishing paste with a particle size of 0.1-0.25 μm is used to polish the sample to a scratch-free mirror surface. It is understood that after polishing, the sample surface is cleaned for subsequent processes. Cleaning is a conventional method in the art and is not particularly limited. According to an embodiment of the invention, the sample is ultrasonically cleaned with ethanol and then dried.

[0036] Preferably, in some specific embodiments of the present invention, a vibration polishing process is included between mechanical polishing and electrolytic polishing. Vibration polishing is used to pre-remove stress from the sample surface, further improving the calibration rate of EBSD samples. According to an embodiment of the present invention, the vibration polishing process specifically involves: immersing the sample surface in a polishing agent, waiting for the vibration equipment to reach its resonant frequency, and vibrating for 5-10 hours. During the vibration polishing process, the pressure on the sample is 0.05-0.15 kg / cm². 2 The preferred value is 0.1 kg / cm³. 2 The polishing agent can be a conventional choice in the art; in some specific embodiments of the present invention, SiO2 polishing agent is used. By combining vibration polishing with electrolytic polishing, the effect of EBSD samples can be further improved, identifying ultrafine grains while increasing the calibration rate of EBSD samples.

[0037] The second aspect of this invention provides an ultrafine-grained oxide dispersion strengthened steel EBSD sample, which is prepared using the preparation method described in the first aspect of this invention.

[0038] The ultrafine-grained oxide dispersion strengthened steel EBSD sample prepared by the preparation method described in the first aspect of this invention can identify ultrafine grains and has a high calibration rate. Preferably, according to embodiments of this invention, the measurement is performed at a high magnification of 2000-4000X and a small scan step size of 50-100nm, which can improve the grain identification effect. More preferably, the measurement is performed at a magnification of 4000X and a scan step size of 50nm.

[0039] The present invention will be described below through specific embodiments. It should be noted that the specific embodiments below are for illustrative purposes only and do not limit the scope of the present invention in any way. In addition, unless otherwise specified, methods that do not specifically describe conditions or steps are conventional methods, and the reagents and materials used can be obtained commercially.

[0040] In the following examples and comparative examples, the electropolishing equipment was built in a fume hood, the electropolishing solution was a mixture of perchloric acid and ethanol (of which the volume percentage of perchloric acid was 6-12%), and weights were attached to the sample during vibration polishing.

[0041] Comparative Example 1

[0042] In this comparative example, the ultrafine-grained oxide dispersion strengthened steel sample was a 9Cr-ODS steel formed by hot isostatic pressing, and the electropolishing solution was a mixed solution of 10% perchloric acid and ethanol. The preparation steps of the EBSD sample are as follows:

[0043] S1. Mirror polishing: 9Cr-ODS steel is cut into 7mm×7mm×2mm squares by wire cutting. The squares are polished with 400#, 800#, 1200#, 1500# and 2000# sandpaper in sequence. Then, the samples are polished to a mirror finish with 0.25μm and 0.1μm water-soluble polishing pastes respectively. The samples are ultrasonically cleaned with ethanol and the surface is dried.

[0044] S2. Electrolytic polishing: Pour 50 mL of perchloric acid and 450 mL of ethanol into a beaker, and use liquid nitrogen to lower the temperature to -10℃ to obtain an electrolytic polishing solution; place the power supply cathode plate at the bottom of the beaker, connect the anode to conductive tweezers, hold the side of the sample with the tip of the tweezers, so that the mirror surface of the sample is in horizontal contact with the surface of the polishing solution, 7 cm away from the cathode plate, adjust the current to 0.25A, polish for 30 s, then take out the sample and clean and dry it with ethanol to obtain the EBSD sample;

[0045] S3, EBSD acquisition: Grain information of 9Cr-ODS steel was acquired using a magnification of 2000X and a step size of 100nm.

[0046] The calibration rate was only 56% after testing, and from Figure 1 The secondary electron microscopy (TEM) and IPF (Inductively Coupled Function) images show that only micron-sized grains can be identified, while large black areas represent unidentified ultrafine grains. Therefore, while electrolysis at 0.25A for 30 seconds can identify coarser grains in 9Cr-ODS steel, it is ineffective for finer grains (ultrafine grains).

[0047] Comparative Example 2

[0048] This comparative example uses the same implementation method as Comparative Example 1, except that in the electropolishing process, a current of 0.75A is used for electrolysis for 30 seconds. All other processes are the same as in Comparative Example 1.

[0049] The calibration rate was only 69% after testing, and from Figure 2 The secondary electron image and IPF image show that the recognition effect of the ultrafine grain region of 9Cr-ODS steel is improved compared with Comparative Example 1, but some fine grain regions are over-dissolved and grain boundaries are separated, so the recognition rate is still low.

[0050] Example 1

[0051] In this embodiment, the ultrafine-grained oxide dispersion strengthened steel sample is a 9Cr-ODS steel formed by hot isostatic pressing, and the electropolishing solution is a mixed solution of 10% perchloric acid and ethanol. The preparation steps of the EBSD sample are as follows:

[0052] S1, Mirror polishing: Same as comparative example 1;

[0053] S2, Electrolytic polishing: Same as Comparative Example 1, except that: first, the current is adjusted to 0.25A, the sample is taken out immediately after polishing for 10s, then the current is increased to 0.75A, polishing for 20s, then the sample is taken out and cleaned with ethanol and dried to obtain EBSD sample;

[0054] S3, EBSD acquisition: Same as comparison sample 1.

[0055] The calibration rate has been tested and found to reach 85%. Figure 3 The secondary electron microscopy (TEM) and IPF (Inductively Coupled Function) diagrams show that not only micron-sized grains but also ultrafine grains can be identified. This indicates that segmented electrolysis (using 0.25A for 10 seconds and 0.75A for 20 seconds) can effectively identify ultrafine grains.

[0056] Comparative Example 3

[0057] In this comparative example, the ultrafine-grained oxide dispersion strengthened steel sample is a 9Cr-ODS steel formed by hot isostatic pressing. The preparation steps of the EBSD sample are as follows:

[0058] S1. Mirror polishing: Same as in Example 1;

[0059] S2. Vibratory polishing: Clean the polishing cloth, fix the sample, place the mirror on the polishing cloth, pour in SiO2 polishing agent to immerse the sample surface, load weights, adjust the voltage to make the vibratory polisher resonate at about 58kHz, vibrate polish for 5 hours, take out the sample, clean the sample surface with Seagull brand detergent and ethanol and blow dry to obtain EBSD sample.

[0060] S3, EBSD acquisition: Sample grain information was acquired using a magnification of 1000X and a step size of 50nm.

[0061] The calibration rate reached 77% after testing. Figure 4 The secondary electron microscopy (TEM) and IPF (Inductively Coupled Function) images show that the acquisition effect is better for micron-sized grains, while the identification of ultrafine grain regions is lower. This indicates that 5 hours of vibration polishing yields good grain acquisition results, but the effect is poor for some ultrafine grain regions.

[0062] Comparative Example 4

[0063] In this comparative example, the ultrafine-grained oxide dispersion strengthened steel sample was a 9Cr-ODS steel formed by hot isostatic pressing, and the vibration polishing time was 10 hours. The preparation steps of the EBSD sample are as follows:

[0064] S1, Mirror polishing: Same as comparative example 3.

[0065] S2, Vibratory polishing: Same as comparative example 3, except that the vibratory polishing time is increased to 10 hours.

[0066] S3, EBSD acquisition: Sample grain information was acquired using a magnification of 2000X and a step size of 100nm.

[0067] The calibration rate reached 75% after testing. Figure 5 The secondary electron microscopy (TEM) and IPF (Inductively Coupled Function) images show that the grain acquisition effect is good, but the identification rate of ultrafine grain regions is low. Therefore, increasing the vibration polishing time does not improve the identification effect of ultrafine grains; on the contrary, it reduces the identification rate.

[0068] Example 2

[0069] In this embodiment, the ultrafine-grained oxide dispersion strengthened steel sample is a 9Cr-ODS steel formed by hot isostatic pressing, vibratory polishing for 5 hours, and the electrolytic polishing solution is a 10% perchloric acid + ethanol mixed solution. The preparation steps of the EBSD sample are as follows:

[0070] S1. Mirror polishing: After wire cutting, the sample is cold-set, and the polishing process is the same as in Example 1.

[0071] S2. Vibratory polishing: Clean the polishing cloth, fix the sample, place the mirror on the polishing cloth, pour in SiO2 polishing agent to immerse the sample surface, load the weight, adjust the voltage to make the vibratory polisher resonate at about 58kHz, vibrate polish for 5 hours, take out the sample, clean the sample surface with Seagull brand detergent and ethanol and blow dry.

[0072] S3, Electropolishing: Same as Example 1.

[0073] S4, EBSD acquisition: Same as Example 1.

[0074] The calibration rate reached 89% after testing, with good identification of micron-sized and ultrafine grains. This indicates that vibration polishing combined with electrolytic polishing can effectively identify ultrafine grains and improve the calibration rate of EBSD samples, demonstrating good results.

[0075] Example 3

[0076] In this embodiment, the ultrafine grain oxide dispersion strengthened steel sample is a 9Cr-ODS steel formed by hot isostatic pressing. The preparation of its EBSD sample adopts the same process as in Example 2, except that: in the EBSD acquisition step, a magnification of 4000X and a scanning step size of 50nm are used to acquire sample grain information.

[0077] The calibration rate reached 90% after testing, and the identification of micron-sized and ultrafine grains was excellent. This indicates that using high magnification and a small scanning step size can better identify ultrafine grains, resulting in more accurate statistical results.

[0078] Example 4

[0079] In this embodiment, the ultrafine-grained oxide dispersion strengthened steel sample is a high-temperature normalized 9Cr-ODS steel formed by hot isostatic pressing, vibratory polishing for 5 hours, and the electrolytic polishing solution is a 10% perchloric acid + ethanol mixed solution. The preparation steps of the EBSD sample are as follows:

[0080] S1. Mirror polishing: Same as in Example 2.

[0081] S2, Vibration polishing: Same as in Example 2.

[0082] S3, Electropolishing: Same as Example 2.

[0083] S4, EBSD acquisition: Sample grain information was acquired using a magnification of 2000X and a step size of 100nm.

[0084] The calibration rate reached 95% after testing. Figure 6 The secondary electron microscopy (TEM) and IPF (Inductively Coupled Function) images show that the sample after high-temperature normalizing has a high proportion of micron-sized grains, and both micron-sized and ultrafine grains are identified. This indicates that the combination of vibration polishing and electrolytic polishing is not only effective in identifying ultrafine grains but also in identifying micron-sized grains. Furthermore... Figure 7 The figure shows a statistical chart of the grain size of 9Cr-ODS steel collected by EBSD sample at different scanning step sizes in this embodiment. It can be seen that scanning at a small step size of less than 100nm has a better effect on the identification of ultrafine grains.

[0085] Example 5

[0086] In this embodiment, the ultrafine-grained oxide dispersion strengthened steel sample is a 9Cr-ODS steel formed by hot isostatic pressing, vibratory polishing for 7 hours, and the electrolytic polishing solution is a 12% perchloric acid + ethanol mixed solution. The preparation steps of the EBSD sample are as follows:

[0087] S1. Mirror polishing: After cutting 9Cr-ODS steel into 7mm×7mm×2mm squares by wire cutting, the squares are cold-mounted and polished with 400#, 800#, 1200#, 1500# and 2000# sandpaper in sequence. Then, the samples are polished to a mirror finish with 0.25μm and 0.1μm water-soluble polishing pastes respectively. After ultrasonic cleaning of the samples with ethanol, the surface is dried.

[0088] S2. Vibratory polishing: Clean the polishing cloth, fix the sample, place the mirror on the polishing cloth, pour in SiO2 polishing agent to immerse the sample surface, load the weight, adjust the voltage to make the vibratory polisher reach resonance at about 58kHz, vibrate polish for 7 hours, take out the sample, clean the sample surface with Seagull brand detergent and ethanol and blow dry.

[0089] S3. Electropolishing: Pour 60 mL of perchloric acid and 440 mL of ethanol into a beaker, and use liquid nitrogen to lower the temperature to -20℃ to obtain an electropolishing solution. Place the power supply cathode plate at the bottom of the beaker, connect the anode to conductive tweezers, and use the tweezers to hold the side of the sample so that the mirror surface of the sample is in horizontal contact with the surface of the polishing solution, 5 cm away from the cathode plate. First, adjust the current to 0.3 A, polish for 15 seconds, and then immediately remove the sample. Then increase the current to 1.0 A and polish for 10 seconds. After that, remove the sample, clean it with ethanol, and blow it dry to obtain the EBSD sample.

[0090] S4, EBSD acquisition: Sample grain information was acquired using a magnification of 2000X and a step size of 50nm.

[0091] The calibration rate was tested to be 91%, and the identification of ultrafine grains was good.

[0092] Example 6

[0093] In this embodiment, the ultrafine-grained oxide dispersion strengthened steel sample is a 9Cr-ODS steel formed by hot isostatic pressing, vibratory polishing for 10 hours, and the electrolytic polishing solution is a 6% perchloric acid + ethanol mixed solution. The preparation steps of the EBSD sample are as follows:

[0094] S1. Mirror polishing: Same as in Example 5.

[0095] S2. Vibratory polishing: Clean the polishing cloth, fix the sample, place the mirror on the polishing cloth, pour in SiO2 polishing agent to immerse the sample surface, load weights, adjust the voltage to make the vibratory polisher resonate at about 58kHz, vibrate polish for 10 hours, take out the sample, clean the sample surface with Seagull brand detergent and ethanol and blow dry.

[0096] S3. Electropolishing: Pour 30 mL of perchloric acid and 470 mL of ethanol into a beaker, and use liquid nitrogen to lower the temperature to -30℃ to obtain an electropolishing solution. Place the power supply cathode plate at the bottom of the beaker, connect the anode to conductive tweezers, and use the tweezers to hold the side of the sample so that the mirror surface of the sample is in horizontal contact with the surface of the polishing solution, 4 cm away from the cathode plate. First, adjust the current to 0.1 A, polish for 30 seconds, and then immediately remove the sample. Then increase the current to 0.6 A and polish for 30 seconds. After that, remove the sample, clean it with ethanol, and blow it dry to obtain the EBSD sample.

[0097] S4, EBSD acquisition: Sample grain information was acquired using a magnification of 4000X and a step size of 80nm.

[0098] The calibration rate was tested to reach 88%, and the identification of ultrafine grains was good.

[0099] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0100] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing an EBSD (Extra-fine Grained Oxide Dispersion Strengthened) steel sample, characterized in that, Includes the following steps: The ultrafine-grained oxide dispersion strengthened steel was subjected to mechanical polishing, vibration polishing and electrolytic polishing in sequence to obtain ultrafine-grained oxide dispersion strengthened steel EBSD samples. The specific process of vibration polishing is as follows: the sample surface is immersed in SiO2 polishing agent and vibrated for 5-10 hours. The pressure on the sample during vibration polishing is 0.05-0.15 kg / cm². 2 ; The specific parameters for the electropolishing are as follows: the temperature of the electropolishing solution is -30℃ to -10℃; the sample is polished with a microcurrent of 0.1-0.3A for 10-30 seconds, then the current is increased to 0.6-1.0A for another 10-30 seconds; the electropolishing solution is a mixed solution of perchloric acid and ethanol, wherein the volume percentage of the perchloric acid is 6-12%.

2. The preparation method according to claim 1, characterized in that, The mechanical polishing process specifically involves cutting ultrafine-grained oxide dispersion reinforced steel into squares, sanding them with sandpaper, and then polishing them with water-soluble polishing paste to create a scratch-free mirror finish.

3. The preparation method according to claim 2, characterized in that, The sanding was carried out using 400#, 800#, 1200#, 1500#, and 2000# sandpaper in sequence.

4. The preparation method according to claim 2, characterized in that, The water-soluble polishing paste has a particle size of 0.1-0.25 μm.

5. The preparation method according to claim 1, characterized in that, During the electropolishing process, the polished surface of the sample is parallel to the cathode plate, and the working distance between the polished surface and the cathode plate is 4-7 cm.

6. An EBSD sample of ultrafine-grained oxide dispersion strengthened steel, characterized in that, It is prepared by the preparation method described in any one of claims 1-5.

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