A method for preparing stainless steel EBSD samples

Abstract

A method for preparing stainless steel EBSD samples utilizes a combination of electrolytic polishing and vibration polishing, combined with the use of an electrolytic polishing solution. Electrolytic polishing is performed at room temperature, quickly removing the surface strain layer of the sample to be tested while avoiding over-corrosion. Subsequent vibration polishing removes residual relief, minor over-corrosion, and residual stress on the sample surface, resulting in improved surface quality. The resolution rate of stainless steel EBSD samples of various tissue types consistently exceeds 98%. The overall operation is simpler, the efficiency of preparing stainless steel EBSD samples of different tissue types is higher, and the electrolyte preparation is simple, stable, and safe.

Description

Technical Field

[0001] The present invention relates to the technical field of detection sample preparation, in particular to a method for preparing a stainless steel EBSD sample. Background Art

[0002] Stainless steel has excellent high-temperature and corrosion resistance. Based on its microstructure, it is classified into austenitic, ferritic, martensitic, and austenitic-ferritic (duplex) stainless steels. It is widely used in many fields, including kitchenware and tableware, household appliances, the chemical industry, architectural decoration, and transportation. Given the wide range of stainless steel applications, in-depth research on its microstructure and crystallography is essential.

[0003] Electron backscatter diffraction (EBSD), an analytical method for studying microstructure and crystallographic features, has become a powerful tool in matrix mechanism research and new product development. It relies on the electron beam in a scanning electron microscope striking the inclined sample surface, stimulating backscattered electrons. These electrons are collected by the detector and form a diffraction pattern, which can be used to determine crystal structure, crystal orientation, grain size, phase identification, and stress analysis. EBSD occurs only in a shallow surface region (10 to 30 nm thick) on the sample surface, placing high demands on sample preparation quality, requiring a smooth surface with no processing strain layers or oxide films.

[0004] The various stainless steel EBSD sample preparation methods and their advantages and disadvantages are shown in Table 1:

[0005] Table 1

[0006] Preparation method advantage shortcoming Mechanical polishing Fewer sample preparation steps The personnel experience requirements are extremely high and the success rate is low Chemical polishing Simple sample preparation Strong acid corrosion, low temperature environment, low resolution electrolytic polishing Fast delivery time Strong acid electrolyte, low temperature control, unstable resolution Vibration polishing Good universality Slow timeliness and unstable resolution rate Chemical-vibration polishing Applicable to high corrosion resistant steel Chemical corrosive agents have poor universality, low resolution, and slow aging Ion Thinning Suitable for all materials Expensive equipment and long time

[0007] Chinese patent CN109030134A discloses a "method for preparing high-nitrogen nickel-free austenitic stainless steel EBSD samples." This patent uses a purely mechanical polishing method, which requires precise polishing position, rotation speed, polishing liquid drop rate, etc. This method is limited by the equipment and the experience of the experimenters, and the success rate is difficult to guarantee.

[0008] Chinese patent CN109632436A discloses a "surface treatment method for EBSD test specimens of high-nitrogen stainless steel." This patent designs a chemical corrosion method for preparing EBSD samples for high-nitrogen stainless steel. The corrosive agents used are analytically pure hydrochloric acid and nitric acid, which are strong inorganic acids and have poor universality.

[0009] Chinese patent CN115406918A discloses a method for preparing EBSD samples of martensitic high-strength steel. The patent adopts a combination of chemical etching and vibration polishing to prepare EBSD samples. However, this method takes a long time and has a low resolution.

[0010] Chinese patent CN116413292A discloses a method for preparing zirconium alloy EBSD samples by vibration polishing. This method uses vibration polishing to prepare samples, which takes at least 4 hours, which is too long.

[0011] Chinese patent CN113670699A discloses a ferritic heat-resistant stainless steel EBSD sample and a preparation method thereof. The method uses an electrolyte comprising a mixed solution of perchloric acid and ethanol in a volume ratio of 8-12:88-92. The electrolyte needs to be used at -30 to -10°C while stirring.

[0012] Chinese patent CN112116001813 discloses a method for preparing super martensitic stainless steel EBSD samples. The method uses an electrolyte composed of a mixture of perchloric acid, acetic acid, and alcohol in a volume ratio of (1±0.1):(3±0.1):(6±0.1). The electrolyte needs to be stirred at -20 to 0°C.

[0013] Chinese patent CN112229860A discloses a method for electrolytic polishing of austenitic stainless steel for EBSD testing. The method uses an electrolyte composed of a mixture of perchloric acid and alcohol in a volume ratio of 1:1.5 to 2.5. The electrolyte needs to be used at -30 to -15°C while stirring.

[0014] Chinese patent CN111929337A discloses an EBSD sample preparation method and EBSD sample for an Al-Zn-Mg-Cu alloy. This patent utilizes a method of vibratory polishing followed by electrolytic polishing to prepare the sample. This results in the Al-Zn-Mg-Cu alloy requiring 3-4 hours of vibratory polishing, a lengthy process that results in inefficient detection. This patent shares common understandings of existing EBSD sample preparation: 1. Electrolytic polishing is believed to produce superior surface quality, and 2. Vibratory polishing provides superior stress relief.

[0015] Due to the limitations of sample materials, existing EBSD preparation methods are all performed on samples of a single material. Since the corrosion rates of different tissues are different, especially stainless steel containing multiphase tissues, such as precipitated phases in stainless steel and duplex stainless steel, there is no unified preparation method that can be applied to EBSD samples of stainless steel with different tissues. Summary of the Invention

[0016] The present invention aims to provide a method for preparing stainless steel EBSD samples. The method is applicable to the preparation of stainless steel EBSD samples with different structures (ferrite, austenite, martensite and duplex), and can achieve a high resolution rate of ≥98% for EBSD samples prepared for different structures. In addition, the preparation operation is simpler and more efficient.

[0017] To achieve the above object, the technical solution of the present invention is:

[0018] A method for preparing a stainless steel EBSD sample comprises the following steps:

[0019] 1) Sampling

[0020] Cut the sample to be tested from the stainless steel;

[0021] 2) Electrolytic polishing

[0022] The sample to be tested is placed in an electrolytic polishing solution for electrolytic polishing for 10 to 90 seconds. The electrolytic polishing solution comprises: oxalic acid: 1 to 10% wt, alcohol: 5 to 10% wt, cocamidopropylamine oxide: 0.1 to 0.2% wt, and the balance is water;

[0023] 3) Vibration polishing, polishing time 10 to 20 minutes;

[0024] 4) Clean the surface of the sample to be tested until no polishing liquid remains on the surface to obtain a stainless steel EBSD sample.

[0025] Preferably, in step 2), the electrolytic polishing voltage is 1.0 to 5.0 V, and the current is 0.1 to 0.5 A.

[0026] Preferably, in step 2), the oxalic acid, alcohol, and cocamidopropylamine oxide used in the electrolytic polishing solution are all analytically pure, and the water is deionized water with a conductivity of ≤18.25 MΩ.cm.

[0027] Preferably, in step 3), the vibration polishing voltage is 170-220V, and the polishing frequency is 50-75Hz.

[0028] Preferably, the stainless steel is austenitic stainless steel, ferritic stainless steel, martensitic stainless steel or ferrite-austenite duplex stainless steel.

[0029] Preferably, in step 1), the size of the sample to be tested is: 5-10 mm in length, 5-10 mm in width, and 3-6 mm in height.

[0030] Preferably, the sample to be tested is first hot-mounted, and then coarsely ground with water-abrasive sandpaper, starting from 280 mesh, 600 mesh, and 1200 mesh in sequence, and finally polished with a polishing cloth until the sample surface is flat and scratch-free.

[0031] Preferably, the direction of the new grinding mark during the rough grinding process should be perpendicular to the direction of the previous grinding mark.

[0032] Preferably, during the polishing process using the polishing cloth, a diamond polishing agent is used in the polishing machine, and the polishing direction is perpendicular to the 1200 mesh wear mark direction.

[0033] The present invention first performs electrolytic polishing on a stainless steel sample to be tested. The electrolytic polishing liquid used for electrolytic polishing uses an electrolytic polishing liquid containing oxalic acid. During the electrolytic polishing process, the electrolytic polishing liquid near the anode surface of the sample forms a viscous film of uneven thickness on the sample according to the surface unevenness. The film diffuses quickly near the raised areas of the sample surface, forming a thin film; while the film diffuses slowly near the recessed areas, forming a thick film. The film has a large resistance, and the current density is high in thin areas and low in thick areas. As a result, the current density varies across the sample film surface, and the raised areas of the sample surface are preferentially selectively dissolved, gradually smoothing the sample surface.

[0034] The oxalic acid contained in the electropolishing solution is a weak acid compared to other inorganic acids (such as sulfuric acid, hydrochloric acid, and perchloric acid), but it is a medium-strong acid compared to other weak acids (such as acetic acid, carbonic acid, and other organic acids). This ensures that it can react corrosively with the sample during the electrolysis process while also preventing excessive corrosion. Furthermore, oxalic acid's properties are insensitive to temperature changes, allowing electropolishing operations at room temperature to avoid excessive corrosion. Conventional electrolytes use inorganic acids (such as sulfuric acid, hydrochloric acid, and perchloric acid) as electrolytes. To avoid excessive corrosion, liquid nitrogen is required to cool the electrolyte and perform electropolishing at low temperatures. The alcohol and cocamidopropylamine oxide in the electrolyte are primarily used to dilute the acid, dissolving it in the film produced during the polishing process and preventing excessive corrosion caused by excessive acidity.

[0035] The oxalic acid concentration in the electrolytic polishing liquid of the present invention is 1 to 10% by weight. If the concentration is too low, a long time of electrolysis is required, and if the concentration is too high, corrosion pits are easily formed on the sample surface. The electrolytic polishing voltage is 1.0 to 5.0 V, the current is 0.1 to 0.5 A, and the time is 10 to 90 seconds, effectively removing the deformation layer and stress on the surface of the stainless steel sample to be tested without generating additional surface deformation. If the voltage and current are too high during the electrolysis process, corrosion pits are easily formed on the sample surface.

[0036] After electrolytic polishing, the sample is vibratory polished for 10 to 20 minutes. The subsequent vibration polishing removes residual relief or slight over-corrosion and residual stress on the sample surface to obtain better surface quality. For stainless steel with different tissue types, the EBSD sample resolution rate can reach more than 98%.

[0037] Preferably, the sample of the present invention is pretreated before electrolytic polishing, that is, it is first mounted and then roughly ground, and then polished with 280 mesh, 600 mesh, and 1200 mesh water-abrasive sandpaper in sequence. This process will form a very thick metal deformation layer on the surface of the sample.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The existing polishing methods generally adopt mechanical polishing or chemical polishing.

[0040] Mechanical polishing uses a diamond spray polishing agent. Diamond is an ideal polishing agent with the highest hardness and strong cutting ability. However, it only produces a grinding action during the polishing process and cannot remove the deformed layer, making it unsuitable for preparing EBSD samples.

[0041] Chemical polishing is not suitable for preparing EBSD samples because the electrochemical potentials of the various components on the sample surface are different, forming many micro-batteries, which will cause uneven dissolution in the chemical solution, and the surface is prone to ripples.

[0042] The present invention adopts a sample preparation method of electrolytic polishing + vibration polishing. Electrolytic polishing removes the surface strain layer of the sample to be tested in a relatively short time. Subsequent vibration polishing removes residual relief or slight over-corrosion and residual stress on the surface of the sample to be tested, thereby obtaining better surface quality. The resolution rate of stainless steel EBSD samples with various structures can stably reach above 98%.

[0043] The electrolytic polishing liquid used in the present invention is formulated with weak acid oxalic acid and can be operated at room temperature to avoid excessive corrosion of the sample. Compared with conventional electrolytic polishing that uses liquid nitrogen for cooling to avoid excessive corrosion, the operation is simpler and the current and voltage used are lower. The electrolytic polishing voltage is 1.0 to 5.0 V and the current is 0.1 to 0.5 A. Conventional electrolytic polishing voltage is generally between 13 and 35 V and the current is between 0.8 and 1.5 A.

[0044] The electrolytic polishing liquid of the present invention is simple to prepare, stable and safe; however, sulfuric acid, phosphoric acid and chromic acid used in conventional electrolytes are relatively serious environmental pollutants, and perchloric acid has the risk of explosion due to the increase in liquid temperature, evaporation of the solution and change in solution concentration.

[0045] The method for preparing stainless steel EBSD samples provided by the present invention is applicable to the preparation of EBSD samples of austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, and ferrite-austenite (duplex) stainless steel. It is a stainless steel EBSD sample preparation method that does not require liquid nitrogen cooling, has strong practicality, high success rate, and high resolution, and is conducive to the application and development of EBSD technology in stainless steel material research. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the EBSD information distribution map of the mechanically polished austenitic stainless steel sample;

[0047] Figure 2 This is the EBSD information distribution map of the mechanically polished ferritic stainless steel sample;

[0048] Figure 3 This is the EBSD information distribution map of the mechanically polished martensitic stainless steel sample;

[0049] Figure 4 This is the EBSD information distribution map of the mechanically polished duplex stainless steel sample;

[0050] Figure 5 This is the EBSD information distribution map of the chemically polished austenitic stainless steel sample;

[0051] Figure 6 This is the EBSD information distribution map of the chemically polished ferritic stainless steel sample;

[0052] Figure 7 This is the EBSD information distribution map of the chemically polished martensitic stainless steel sample;

[0053] Figure 8 This is the EBSD information distribution map of the chemically polished duplex stainless steel sample;

[0054] Figure 9 This is the EBSD information distribution map of the chemical-vibration polished austenitic stainless steel sample;

[0055] Figure 10 This is the EBSD information distribution map of the chemical-vibration polished ferritic stainless steel sample;

[0056] Figure 11 This is the EBSD information distribution map of the chemical-vibration polished martensitic stainless steel sample;

[0057] Figure 12 This is the EBSD information distribution map of the chemical-vibration polished duplex stainless steel sample;

[0058] Figure 13 This is the EBSD information distribution map of the electrolytically polished austenitic stainless steel sample;

[0059] Figure 14 This is the EBSD information distribution map of the electrolytically polished ferritic stainless steel sample;

[0060] Figure 15 This is the EBSD information distribution map of the electrolytically polished martensitic stainless steel sample;

[0061] Figure 16 This is the EBSD information distribution map of the electrolytically polished duplex stainless steel sample;

[0062] Figure 17 This is the EBSD information distribution map of the austenitic stainless steel sample after vibration polishing for 4 hours;

[0063] Figure 18 This is the EBSD information distribution map of the ferritic stainless steel sample after vibration polishing for 4 hours;

[0064] Figure 19This is the EBSD information distribution map of the martensitic stainless steel sample after vibration polishing for 4 hours;

[0065] Figure 20 This is the EBSD information distribution map of the duplex stainless steel sample after vibration polishing for 4 hours;

[0066] Figure 21 EBSD information distribution diagram of the austenitic stainless steel sample of Example 1 of the present invention;

[0067] Figure 22 This is the EBSD information distribution diagram of the ferritic stainless steel sample of Example 2 of the present invention;

[0068] Figure 23 EBSD information distribution diagram of the martensitic stainless steel sample of Example 3 of the present invention;

[0069] Figure 24 This is the EBSD information distribution diagram of the duplex stainless steel sample of Example 4 of the present invention. DETAILED DESCRIPTION

[0070] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0071] Example 1

[0072] The stainless steel to be tested in this embodiment is austenitic stainless steel, grade QN1803, and its chemical composition is as follows: 0.41% C, 0.47% Si, 18.35% Cr, 6.58% Mn, 3.62% Ni, 1.09% Cu, and the balance is Fe and unavoidable impurities. The EBSD sample preparation specifically includes the following steps:

[0073] 1) Sampling

[0074] Cut the sample to be tested from stainless steel using a metallographic cutting machine. The size of the sample to be tested is 10 mm long, 10 mm wide, and 5 mm high. The sample to be tested is hot-mounted and then polished using 280-mesh, 600-mesh, and 1200-mesh sandpaper in sequence. Use a 3.5 μm diamond polishing agent and a polishing cloth to polish the sample until the surface is flat and free of scratches.

[0075] 3) Electrolytic corrosion

[0076] The sample to be tested was placed in an electrolytic polishing solution with a voltage of 1.0 V, a current of 0.1 A, and a time of 90 s. The electrolytic polishing solution consisted of 10 g oxalic acid, 928 g water, 70 g alcohol, and 2 g cocamidopropylamine oxide.

[0077] 4) Vibration polishing

[0078] The vibration polishing voltage was 170 V, the vibration frequency was 63 Hz, the load was 287 g, and the vibration polishing time was 10 min.

[0079] 5) Clean the surface of the sample to be tested until no polishing liquid remains on the surface to obtain a stainless steel EBSD sample.

[0080] The obtained stainless steel EBSD sample was placed on a SEM instrument with EBSD function for testing, with an operating voltage of 20kV, a tilt angle of 70.0°, and a beam spot of 6um. The resolution of austenitic stainless steel is 99.27%, that is, 99.27% ​​of the test area on the sample surface can identify the diffraction information of backscattered electrons. The orientation distribution diagram of EBSD is shown in the figure below. Figure 21 As shown, the grain structure is clear and the grain boundaries are clearly visible.

[0081] Example 2

[0082] The stainless steel selected for testing in this embodiment is ferritic stainless steel, grade 430, with a chemical composition of 0.27% C, 0.14% Si, 16.64% Cr, 0.37% Mn by mass, and the balance Fe and unavoidable impurities. The EBSD sample preparation specifically includes the following steps:

[0083] 1) Sampling

[0084] Cut the sample to be tested from stainless steel using a metallographic cutting machine. The size of the sample to be tested is 10 mm long, 10 mm wide, and 5 mm high. The sample to be tested is hot-mounted and then polished using 280-mesh, 600-mesh, and 1200-mesh sandpaper in sequence. Use a 3.5 μm diamond polishing agent and a polishing cloth to polish the sample until the surface is flat and free of scratches.

[0085] 3) Electrolytic corrosion

[0086] The sample to be tested was placed in an electrolytic polishing solution with a voltage of 3.0 V, a current of 0.3 A, and a time of 50 s. The electrolytic polishing solution consisted of 45 g of oxalic acid, 904 g of water, 50 g of alcohol, and 1 g of cocamidopropylamine oxide.

[0087] 4) Vibration polishing

[0088] The vibration polishing voltage was 200 V, the vibration frequency was 60 Hz, the vibration load was 287 g, and the vibration polishing time was 15 min.

[0089] 5) Clean the surface of the sample to be tested until no polishing liquid remains on the surface to obtain a stainless steel EBSD sample.

[0090] The stainless steel EBSD sample was placed on an EBSD-capable SEM instrument for testing, operating at 20 kV, a tilt angle of 70.0°, and a beam spot size of 6 μm. The resolution of the austenitic stainless steel was 99.34%, meaning that 99.34% of the surface area tested could identify backscattered electron diffraction information. The EBSD orientation distribution diagram is shown in the attached figure. Figure 22 As shown, the grain structure is clear and the grain boundaries are clearly visible.

[0091] Example 3

[0092] The stainless steel to be tested in this embodiment is martensitic stainless steel, grade 30Cr13, with a chemical composition of 0.41% C, 0.39% Si, 11.41% Cr, 0.51% Mn by mass, and the balance Fe and unavoidable impurities. The EBSD sample preparation specifically includes the following steps:

[0093] 1) Sampling

[0094] Cut the sample to be tested from stainless steel using a metallographic cutting machine. The size of the sample to be tested is 10 mm long, 10 mm wide, and 5 mm high. The sample to be tested is hot-mounted and then polished using 280-mesh, 600-mesh, and 1200-mesh sandpaper in sequence. Use a 3.5 μm diamond polishing agent and a polishing cloth to polish the sample until the surface is flat and free of scratches.

[0095] 3) Electrolytic corrosion

[0096] The sample to be tested was placed in an electrolytic polishing solution with a voltage of 2.5 V, a current of 0.1 A, and a time of 70 s. The electrolytic polishing solution consisted of 45 g of oxalic acid, 853 g of water, 100 g of alcohol, and 2 g of cocamidopropylamine oxide.

[0097] 4) Vibration polishing

[0098] The vibration polishing voltage was 200 V, the vibration frequency was 60 Hz, the vibration load was 287 g, and the vibration polishing time was 15 min.

[0099] 5) Clean the surface of the sample to be tested until no polishing liquid remains on the surface to obtain a stainless steel EBSD sample.

[0100] The stainless steel EBSD sample was placed on an EBSD-capable SEM instrument for testing, operating at 20 kV, a tilt angle of 70.0°, and a beam spot size of 6 μm. The resolution of the austenitic stainless steel was 99.34%, meaning that 98.78% of the surface area tested could identify backscattered electron diffraction information. The EBSD orientation distribution diagram is shown in the attached figure. Figure 23 As shown, the grain structure is clear and the grain boundaries are clearly visible.

[0101] Example 4

[0102] The stainless steel to be tested in this embodiment is ferrite-austenite duplex stainless steel, grade S32750, and its chemical composition is as follows: 0.39% C, 0.48% Si, 27.95% Cr, 0.92% Mn, 4.62% Ni, 4.35% Mo, and the balance is Fe and unavoidable impurities. The EBSD sample preparation specifically includes the following steps:

[0103] 1) Sampling

[0104] Cut the sample to be tested from stainless steel using a metallographic cutting machine. The size of the sample to be tested is 10 mm long, 10 mm wide, and 5 mm high. The sample to be tested is hot-mounted and then polished using 280-mesh, 600-mesh, and 1200-mesh sandpaper in sequence. Use a 3.5 μm diamond polishing agent and a polishing cloth to polish the sample until the surface is flat and free of scratches.

[0105] 3) Electrolytic corrosion

[0106] The sample to be tested was placed in an electrolytic polishing solution with a voltage of 5.0 V, a current of 0.5 A, and a time of 10 s. The electrolytic polishing solution consisted of 100 g oxalic acid, 849 g water, 50 g alcohol, and 1 g cocamidopropylamine oxide.

[0107] 4) Vibration polishing

[0108] The vibration polishing voltage was 220 V, the vibration frequency was 70 Hz, the vibration load was 287 g, and the vibration polishing time was 20 min.

[0109] 5) Clean the surface of the sample to be tested until no polishing liquid remains on the surface to obtain a stainless steel EBSD sample.

[0110] The obtained stainless steel EBSD sample was placed on a SEM instrument with EBSD function for examination, operating voltage 20kV, tilt angle 70.0°, and beam spot size 6um. The resolution of austenitic stainless steel was 99.96%, which means that 99.83% of the surface area tested by the sample could identify the diffraction information of backscattered electrons. The EBSD orientation distribution map is shown in the attached figure. Figure 24 As shown, the grain structure is clear and the grain boundaries are clearly visible.

[0111] Figures 1 to 4 This is the EBSD information distribution diagram of the stainless steel sample prepared using the traditional mechanical polishing process disclosed in Chinese patent CN109030134A. As can be seen from the figure, the resolution rate of this method for stainless steel with different structures is shown in Table 2.

[0112] Figures 5 to 8This is the EBSD information distribution diagram of the stainless steel sample prepared using the traditional chemical polishing process disclosed in Chinese patent CN109632436A. As can be seen from the figure, the resolution rate of this method for stainless steel with different structures is shown in Table 2.

[0113] Figures 9 to 12 This is the EBSD information distribution diagram of a stainless steel sample prepared using the traditional chemical polishing followed by vibration polishing process disclosed in Chinese patent CN115406918A. As can be seen from the figure, the resolution rate of this method for stainless steels with different structures is shown in Table 2.

[0114] Figures 13 to 16 This is the EBSD information distribution diagram of a stainless steel sample prepared using the traditional electrolytic polishing process disclosed in Chinese patent CN113670699A. As can be seen from the figure, the resolution rate of this method for stainless steel with different structures is shown in Table 2.

[0115] Figures 17 to 20 This is the EBSD information distribution diagram of a stainless steel sample prepared using the traditional vibration polishing process disclosed in Chinese patent CN116413292A. As can be seen from the figure, the resolution rate of this method for stainless steel with different structures is shown in Table 2.

[0116] Figures 21 to 24 The EBSD information distribution diagrams of the stainless steel samples prepared in Examples 1 to 4 of the present invention are shown in Table 2.

[0117] As can be seen from Table 2, the stainless steel EBSD samples with different structures prepared by the present invention have a resolution rate of more than 98%, while the stainless steel EBSD samples with different structures prepared by the traditional process cannot achieve a high resolution rate at the same time.

[0118] The above description is merely an embodiment of the present invention and cannot be used to limit the scope of protection of the patent of the present invention. For those skilled in the art, several variations and improvements can be made without departing from the structure of the present invention. These should also be considered as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection claimed by this application shall be based on the content of its claims. The specific implementation methods and other records in the description can be used to interpret the content of the claims.

[0119] Table 2

[0120]

Claims

1. A method for preparing stainless steel EBSD samples, characterized in that: The steps include: 1) Sampling Cut the sample to be tested from the stainless steel; 2) Electrolytic polishing The sample to be tested is placed in an electrolytic polishing solution for electrolytic polishing for 10 to 90 seconds. The electrolytic polishing solution comprises: oxalic acid: 1 to 10% wt, alcohol: 5 to 10% wt, cocamidopropylamine oxide: 0.1 to 0.2% wt, and the balance is water. The electrolytic polishing voltage is 1.0 to 5.0 V and the current is 0.1 to 0.5 A. 3) Vibration polishing, polishing time 10 to 20 minutes; vibration polishing voltage 170 to 220V, polishing frequency 50 to 75Hz; 4) Clean the surface of the sample to be tested until no polishing liquid remains on the surface to obtain a stainless steel EBSD sample; The stainless steel is austenitic stainless steel, ferritic stainless steel, martensitic stainless steel or ferrite-austenite duplex stainless steel.

2. The method for preparing a stainless steel EBSD sample according to claim 1, wherein: In the step 2), the oxalic acid, alcohol, and cocamidopropylamine oxide used in the electrolytic polishing solution are all analytically pure, and the water is deionized water with a conductivity of ≤18.25 MΩ·cm.

3. The method for preparing a stainless steel EBSD sample according to claim 1, wherein: In step 1), the size of the sample to be tested is: 5-10 mm in length, 5-10 mm in width, and 3-6 mm in height.

4. The method for preparing a stainless steel EBSD sample according to claim 1, wherein: In step 1), the sample to be tested is first hot mounted, and then coarsely ground with water-abrasive sandpaper, starting from 280 mesh, 600 mesh, and 1200 mesh in sequence, and finally polished with a polishing cloth until the sample surface is flat and scratch-free.

5. The method for preparing a stainless steel EBSD sample according to claim 4, wherein: In step 1), the direction of the new grinding mark during the rough grinding process should be perpendicular to the direction of the previous grinding mark.

6. The method for preparing a stainless steel EBSD sample according to claim 4 or 5, wherein: In step 1), during the polishing process using the polishing cloth, a diamond polishing agent is used as the polishing agent, and the polishing direction is perpendicular to the 1200 mesh wear mark direction.

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