A method for evaluating and analyzing inclusions in steel

Abstract

The present invention provides a method for evaluating and analyzing inclusions in steel, comprising: presetting at least one reference value of inclusion size, composition, and classification standard in a scanning electron microscope program based on at least one of the main types of inclusions in the steel and the composition of the molten steel; selecting and preparing samples based on the shape of the finished steel; defining a scanning area on the detection surface of the prepared sample, setting electron microscope scanning parameters, and performing electron microscope scanning detection on the inclusions; and defining at least one of the number, type, size, composition, perimeter, and area of ​​the inclusions within the scanning area obtained by scanning the sample, as a quantitative evaluation index for the inclusions in the steel, the distribution uniformity, circularity, and inclusion size distribution uniformity of the inclusions in the finished steel, thereby characterizing the distribution, morphology, and size of the inclusions. The present invention can comprehensively, accurately, and quickly evaluate and analyze inclusions in finished steel based on an automatic scanning electron microscope, thereby providing guidance for the production of high-cleanliness steel.

Description

Technical Field

[0001] The present invention relates to the technical field of material analysis, and in particular to a method for evaluating and analyzing inclusions in steel. Background Art

[0002] Steel plays an increasingly important role in social development and human life, and the demand for high-quality steel is growing. Non-metallic inclusions in steel have a significant impact on properties such as fatigue performance, strength, toughness, and melting point. Therefore, controlling non-metallic inclusions in steel is crucial, and how to quickly and accurately evaluate them is key.

[0003] At present, the detection and evaluation methods for inclusions in steel mainly include: (1) metallographic method, which is relatively traditional and can determine the distribution, shape and size of inclusions. It relies on the human eye to distinguish and is prone to large errors; (2) anhydrous electrolysis method, which can obtain the three-dimensional morphology and type of inclusions, but it consumes a lot of manpower and takes a long time. It is more suitable for the analysis of large-sized inclusions; (3) in-situ analysis method, which uses the spectral signal generated by spark discharge to detect and analyze inclusions. It can obtain information such as the number of inclusions and particle size distribution, but its accuracy is relatively low.

[0004] Chinese patent CN112285143A discloses a method for evaluating inclusions in high-cleanliness gear steel. This patent involves cutting several metallographic samples from finished gear steel and using a scanning electron microscope to perform metallographic statistics on the maximum inclusion area within a certain scanning area of ​​the sample. A metallographic microscope is then used to grade the inclusions in one of the samples. The resulting data is then linearly fitted with the equivalent diameter to determine the inclusion evaluation index. However, this method is only applicable to large inclusions.

[0005] Chinese patent CN107132244B discloses a method for quantitatively evaluating inclusions in steel. This patent utilizes metallographic scanning observation of prepared metallographic samples, facilitating the use of the total inclusion area detected and the inclusion spacing calculated from the scanned area as a quantitative evaluation indicator for inclusions in steel. However, this method has errors in the evaluation of small-sized inclusions.

[0006] Chinese patent CN113376195A discloses a method for detecting and evaluating inclusions in spring steel wire rods. This patent utilizes an organic solution to electrolytically corrode a prepared metallographic sample under certain conditions. This sample is then subjected to SEM scanning and analysis. Image processing software is used to determine the area of ​​each inclusion and the area of ​​the pores surrounding the inclusion. This data is then used to calculate the inclusion's equivalent size and shrinkage coefficient, which serve as quantitative inclusion evaluation indicators. However, this method is time-consuming, the use of image processing software is cumbersome, and certain errors are present.

[0007] Chinese patent CN108593649A discloses a method for qualitatively and quantitatively testing and analyzing inclusions in steel. This method first places a prepared metallographic sample under a metallographic microscope to determine its size range. SEM scanning is then performed, using different working distances and magnification factors based on the size range of the inclusions to determine the composition, size, and morphology of the inclusions. This method requires constant switching of electron microscope parameters, which can affect the accuracy of the results.

[0008] In summary, there is currently no comprehensive and accurate method for evaluating inclusions in finished steel products based on automatic scanning electron microscopy. Summary of the Invention

[0009] The present invention provides a method for evaluating and analyzing inclusions in steel, which can comprehensively, accurately and quickly evaluate and analyze inclusions in finished steel products based on an automatic scanning electron microscope, thereby providing guidance for the production of high-cleanliness steel.

[0010] In order to solve the above-mentioned purpose of the invention, the technical solution provided by the present invention is as follows:

[0011] A method for evaluating and analyzing inclusions in steel includes:

[0012] Based on at least one of the main types of inclusions in the steel and the composition of the molten steel, at least one reference value of the inclusion size, composition, and classification standard is preset in the scanning electron microscope program;

[0013] Select and prepare samples according to the shape of finished steel products;

[0014] Define the scanning area on the test surface of the prepared sample, set the electron microscope scanning parameters, and perform electron microscope scanning detection on the inclusions;

[0015] By scanning the sample to obtain at least one of the following information: the number, type, size, composition, perimeter, and area of ​​inclusions within the scanned area, the distribution uniformity, circularity, and inclusion size distribution uniformity of inclusions in the finished steel are defined as quantitative evaluation indicators of inclusions in steel, which are used to characterize the distribution, morphology, and size of inclusions, thereby obtaining a comprehensive and complete inclusion evaluation system.

[0016] Optionally, the sample selection and preparation according to the shape of the finished steel product includes: grinding and polishing the detection surface parallel to the rolling direction.

[0017] Optionally, the finished steel product includes a rolled plate, a bar, and a wire. If the finished steel product is a rolled plate, at least three samples are taken from the rolled plate along the rolling direction, and at least one sample is taken from the rolled plate along the perpendicular rolling direction; and / or,

[0018] If the finished steel product is a bar, samples are taken from the cross section of the bar at equal intervals of the same angle and evenly along the radial direction, wherein the number of equal cross-sections is at least 3, the number of radial samples is at least one, and at least five samples are evenly taken along the rolling direction of the bar; and / or,

[0019] If the finished steel is a wire, samples are taken at equal intervals of the same angle on the cross section of the wire, and samples are taken evenly along the radial direction, wherein the number of equal parts of the cross section is at least 3, the number of radial samples is at least one, and at least five samples are taken evenly along the rolling direction of the wire.

[0020] Optionally, a scanning area is defined on the detection surface of the prepared sample, electron microscope scanning parameters are set, and electron microscope scanning detection is performed on the inclusions, wherein the setting of electron microscope scanning parameters includes:

[0021] Set the scan voltage setting range to 10-25kV; and / or,

[0022] Set the magnification to 300-1000 times; and / or,

[0023] Set the working distance to 16-18mm; and / or,

[0024] Setting a reference material includes: pasting aluminum foil as a reference material at a position on the edge of the sample that is not to be analyzed;

[0025] and / or,

[0026] Set the scan area, including:

[0027] Determine the scanning area;

[0028] The scanning area of ​​the scanning region is ≥30 square millimeters.

[0029] Optionally, determining the scanning area includes: using a diagonal two-point method to determine the scanning area, and the area shape is a rectangle.

[0030] Optionally, the scanning area is determined according to the size of the scanned inclusions.

[0031] Optionally, the setting of electron microscope scanning parameters further includes:

[0032] Set the contrast setting, where the steel substrate contrast value is 200 and the aluminum foil contrast value is 60;

[0033] Set the grayscale threshold. The grayscale of conventional inclusions is darker than that of the steel matrix, and the threshold range is 0-170. The grayscale of rare earth inclusions is lighter than that of the steel matrix, and two thresholds are set. The upper threshold range is 220-250, and the lower threshold range is 0-170.

[0034] Optionally, the inclusion distribution uniformity F is defined as Among them, N i (i=1,2,3…) is the number density of inclusions in a single scan area in a single sample, is the average number density. In a single sample, n is the number of divided areas, and in the entire finished product, n is the number of samples taken.

[0035] Optionally, the circularity e of the inclusion is defined as Among them, D S is the equivalent diameter of the inclusion area, D L is the equivalent diameter of the inclusion perimeter, S is the inclusion area, and L is the inclusion perimeter.

[0036] Optionally, define the inclusion size distribution uniformity d as Among them, in a single sample, D i (i=1, 2, 3...) and The size and average size of each inclusion obtained by automatic scanning electron microscopy, n is the number of divided areas, in the entire finished product, D i (i=1, 2, 3...) and To calculate the size of inclusions in each sample and the overall average size, n is the number of samples taken.

[0037] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0038] (1) By obtaining information on inclusions of all sizes under fixed parameter settings of the scanning electron microscope, without having to switch the electron microscope parameters midway, the number, type, size, composition, perimeter, area and other information of the inclusions can be automatically obtained, with less human error, a larger analysis area and more accurate results.

[0039] (2) By defining the distribution uniformity, circularity, and size uniformity of inclusions as quantitative evaluation indicators of inclusions in steel, they are used to characterize the distribution, morphology, and size of inclusions, respectively. This can qualitatively and quantitatively analyze inclusions in steel, provide an effective technical means for evaluating steel cleanliness, and provide more accurate guidance for inclusion control and optimization of smelting processes during the production process.

[0040] (3) The implementation of the above technical solution is simple to operate and is applicable to the inclusion analysis of various types of steel, providing a new method for quickly and accurately analyzing inclusions in steel. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 This is a flow chart of a method for evaluating and analyzing inclusions in steel according to the present invention;

[0043] Figure 2 Schematic diagram of sampling of finished steel.

[0044] Figure 3 Schematic diagram of another sampling method for finished steel. DETAILED DESCRIPTION

[0045] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Unless otherwise defined, technical or scientific terms used in this invention shall have the same general meaning as those generally understood by persons skilled in the art in the art to which this invention pertains. Words such as "include" or "comprise" used in this invention mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0047] The object of the present invention is to provide a method for evaluating inclusions in steel based on an automatic scanning electron microscope. The method is simple to operate and can more quickly and comprehensively evaluate inclusions in steel. It has important guiding significance for reducing inclusions in steel and improving product quality. The present invention provides a relatively comprehensive and systematic inclusion evaluation index, which can clearly and unambiguously perform quantitative analysis of inclusions in finished products, provides an effective technical means for evaluating the cleanliness of steel, and provides more accurate guidance for inclusion control and optimization of smelting processes during the production process.

[0048] Combine Figure 1 The present invention provides a method for evaluating and analyzing inclusions in steel, comprising:

[0049] S100: Presetting at least one reference value of inclusion size, composition, and classification standard in a scanning electron microscope program based on at least one of the main types of inclusions in the steel and the composition of the molten steel;

[0050] S200: Sample selection and preparation based on the shape of finished steel products;

[0051] S300: Delimiting a scanning area on the test surface of the prepared sample, setting electron microscope scanning parameters, and performing electron microscope scanning detection on inclusions;

[0052] S400: By scanning the sample to obtain at least one of the information of the number, type, size, composition, perimeter, and area of ​​inclusions within the scanned area, the distribution uniformity, circularity, and inclusion size distribution uniformity of inclusions in the finished steel are defined as quantitative evaluation indicators of inclusions in the steel, thereby characterizing the distribution, morphology, and size of inclusions to obtain a comprehensive and complete inclusion evaluation system.

[0053] It should be noted that although the steps in the flowcharts of the accompanying drawings are shown in sequence as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in any logical order. Moreover, at least some of the steps in the flowcharts of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0054] The above implementation provides a comprehensive and complete set of inclusion evaluation indicators. It defines inclusion distribution uniformity, circularity, and size uniformity as quantitative evaluation indicators for inclusions in steel, characterizing the distribution, morphology, and size of inclusions. This provides an effective technical means for evaluating steel cleanliness and offers more accurate guidance for inclusion control and smelting process optimization during production.

[0055] In addition, the above embodiment can also obtain information on inclusions of all sizes under fixed parameter settings of the scanning electron microscope, without switching the electron microscope parameters midway. Information such as the number, type, size, composition, perimeter, and area of ​​the inclusions can be automatically obtained, with minimal human error, a large analysis area, and more accurate results.

[0056] In some optional embodiments, in step S200, preparing the sample includes: grinding and polishing the detection surface parallel to the rolling direction. Grinding and polishing the detection surface can help the detection surface to be evenly exposed to light and scanned by a scanning electron microscope, thereby preventing errors in electron microscope scanning caused by unevenness of the detection surface.

[0057] In some optional specific embodiments, the finished steel product may be in the form of a rolled plate, a bar, or a wire. If the finished steel product is a rolled plate, at least three samples are taken from the rolled plate along the rolling direction, and at least one sample is taken from the rolled plate along the perpendicular rolling direction.

[0058] In addition, if the finished steel product is a bar, samples shall be taken from the cross section of the bar-type finished steel at equal intervals of the same angle, and samples shall be taken evenly along the radial direction, wherein the number of equal cross-sections shall be at least 3, the number of radial samples shall be at least one, and at least five samples shall be taken evenly along the rolling direction of the bar;

[0059] In addition, if the finished steel product is a wire, samples are taken at equal intervals of the same angle on the cross section of the wire-type finished steel, and samples are taken evenly along the radial direction, wherein the number of equal parts of the cross section is at least 3, the number of radial samples is at least one, and at least five samples are taken evenly along the rolling direction of the wire-type finished steel.

[0060] According to the specific production practice of steel, combined with Figure 2 and Figure 3 In some optional specific embodiments, the finished steel is a rolled plate, and ≥5 samples are uniformly taken along the rolling direction of the rolled plate, and the optimal number range is 5-20. ≥1 sample is uniformly taken along the vertical rolling direction of the rolled plate, and the optimal number range is 1-20. The finished product is a bar or wire, and the cross section of the bar or wire can be equally divided at the same angle and then uniformly sampled in the radial direction, wherein the number of equal cross-sections is ≥3 (i.e., the interval angle is ≤120 degrees), the optimal number of equal cross-sections is 3-16, the number of radial samples is ≥1, the optimal number of samples is 2-5, and at the same time, ≥5 samples are uniformly taken along the rolling direction of the rolled material, and the optimal number range is 5-20.

[0061] In some embodiments, in step S300, a scanning area is defined on the detection surface of the prepared sample, and electron microscope scanning parameters are set to perform electron microscope scanning detection on the inclusions, wherein setting the electron microscope scanning parameters includes: setting one or more scanning parameters of scanning voltage, magnification, working distance, reference material, and scanning area. Optionally, the scanning voltage setting range can be 10-25 kV, the magnification range can be 300-1000 times, and the working distance range can be 16-18 mm. In addition, the setting of the reference material can refer to pasting aluminum foil as a reference material at a position on the edge of the sample that is not analyzed.

[0062] In the above embodiment, based on the determined scanning region, the scanning area is set to be ≥ 30 square millimeters. It should be noted that determining the scanning area includes using the diagonal two-point method to determine the scanning area, and the area is rectangular. The scanning area can also be set to be circular or other polygonal, with the scanning area of ​​each sample being ≥ 30 square millimeters, and the preferred scanning area range is 30-150 square millimeters.

[0063] In another embodiment, the scanning area is determined according to the size of the scanned inclusions. The scanning area may vary according to the size of the scanned inclusions. For ultra-low oxygen steel, the preferred scanning area is ≥500 square millimeters.

[0064] In the above embodiment, the scanning parameters of the electron microscope also include the contrast setting and grayscale threshold of the scanning electron microscope. The contrast setting is set, wherein the contrast value of the steel matrix is ​​200, and the contrast value of the aluminum foil is 60. The grayscale threshold is set. The grayscale of conventional inclusions is darker than that of the steel matrix, and the threshold range is 0-170. The grayscale of rare earth inclusions is lighter than that of the steel matrix. Two thresholds are set, with an upper threshold range of 220-250 and a lower threshold range of 0-170.

[0065] In an optional embodiment, the inclusion distribution uniformity F is defined as Among them, N i (i=1,2,3…) is the number density of inclusions in a single scan area in a single sample, is the average number density. In a single sample, n is the number of divided areas, and in the entire finished product, n is the number of samples taken.

[0066] In the above embodiment, for a single sample taken, the automatic scanning electron microscope can divide the scanned sample into different numbers of regions according to the different scanning areas. The area of ​​each region is equal, and the number density N of inclusions in each region is calculated. i (i=1, 2, 3...) and the average number density For the entire finished product, the number density of inclusions in each sample N is calculated. i (i=1, 2, 3...) and the overall average number density The inclusion distribution uniformity F is defined as the ratio of the average number density of inclusions to the relative standard deviation of the number density, such as The greater the inclusion distribution uniformity F, the more uniform the inclusion distribution is, where n is the number of divided areas for a single sample and the number of samples taken for the entire finished product.

[0067] In some embodiments, the circularity e of the inclusion is defined as Among them, D S is the equivalent diameter of the inclusion area, D L is the equivalent diameter of the inclusion perimeter, S is the inclusion area, and L is the inclusion perimeter.

[0068] In the above embodiment, the equivalent diameter D of the inclusion area is defined as S Equivalent diameter D to the circumference of the inclusion L The ratio is the circularity of inclusions, such as The smaller the inclusion's circularity, the more irregular its shape. The closer the circularity is to 1, the more spherical the inclusion's appearance. S is the inclusion's area and L is its perimeter. The average circularity of the samples is the circularity of the entire plate.

[0069] In some embodiments, the inclusion size distribution uniformity d is defined as Among them, in a single sample, D i (i=1, 2, 3...) and The size and average size of each inclusion obtained by automatic scanning electron microscopy, n is the number of divided areas, in the entire finished product, D i (i=1, 2, 3...) and To calculate the size of inclusions in each sample and the overall average size, n is the number of samples taken.

[0070] In the above embodiment, for a single sample taken, the size D of each inclusion can be obtained by automatic scanning electron microscopy. i (i=1, 2, 3...) and average size For the entire finished product, the size D of each sample inclusion is calculated. i (i=1, 2, 3...) and the average size of the whole

[0071] Average size of inclusions The ratio of the relative standard deviation of the size is defined as the uniformity of the inclusion size distribution, such as The greater the inclusion size distribution uniformity d, the more even the inclusion sizes are; conversely, the greater the size disparity. For a single sample, n is the number of divided regions; for the entire finished product, n is the number of samples taken.

[0072] Through the above-listed embodiments, it can be understood that in the present invention, by scanning the sample with a scanning electron microscope, information on the number, type, size, composition, perimeter, and area of ​​inclusions within the scanned area can be obtained. By defining the distribution uniformity, circularity, and inclusion size distribution uniformity of inclusions as quantitative evaluation indices of inclusions in steel, they can be used to characterize the distribution, morphology, and size of inclusions, respectively, thereby obtaining a relatively comprehensive and complete inclusion evaluation index, which can be used as a reference for evaluating inclusions in steel and improving cleanliness.

[0073] In order to facilitate the understanding and description of the embodiments of the present invention, Figure 2 and Figure 3 Here, an optional specific embodiment is proposed, in which the aluminum killed steel is produced, and the production process is: KR molten iron pretreatment → 210t top and bottom blown converter → LF refining → calcium treatment → continuous casting and rolling.

[0074] After the production is stable, take the finished rolled plate and combine it with Figure 3 , take 5 samples along the rolling direction of the plate, number them as sample (1, 2, 3, 4, 5) in sequence, and combine them with Figure 2 , take one sample along the vertical rolling direction of the rolled plate, that is, the sampling quantity is 5×1, and the inspection surface of the sample parallel to the rolling direction is ground and polished. Then the prepared sample is placed in the vacuum chamber of the automatic scanning electron microscope to scan for inclusions larger than 2μm. The electron microscope acceleration voltage is 15kV, the working distance is 17mm, the magnification is 450 times, the search grid is 256×256, and the fixed area of ​​each area is 0.2069 square millimeters according to the scanning area and the number of areas.

[0075] Inclusion parameters obtained after scanning and calculated inclusion distribution uniformity

[0076] Roundness of inclusions Uniformity of inclusion size distribution As shown in Table 1:

[0077] Table 1 Inclusion data results of each sample

[0078]

[0079] In addition, according to the uniformity of a single sample obtained in the above table, the uniformity of the inclusion distribution of the entire rolled plate can be evaluated as follows: The circularity of inclusions is The size distribution uniformity of inclusions is

[0080] In the above specific embodiment, 5 aluminum-killed steel samples were selected. By scanning with a scanning electron microscope, information on the number of inclusions in the scanning area can be obtained. Through the above definitions of the distribution uniformity, circularity, and inclusion size distribution uniformity of the inclusions, the values ​​of the distribution uniformity, circularity 0 degree, and inclusion size distribution uniformity of the 5 samples can be obtained, thereby obtaining the distribution uniformity, circularity, and inclusion size distribution uniformity of the entire aluminum-killed steel, and qualitatively and quantitatively characterizing the distribution, morphology, and size of inclusions in the entire aluminum-killed steel.

[0081] The above are only specific embodiments of the present invention. In the absence of conflict, the features in the embodiments and examples of the present invention can be combined with each other to obtain new embodiments, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. A method for evaluating and analyzing inclusions in steel, characterized in that: include: According to at least one of the information of the inclusion type in the steel and the composition of the molten steel, at least one reference value of the inclusion size, composition, and classification standard is preset in the scanning electron microscope program; Select and prepare samples according to the shape of finished steel products; Define the scanning area on the test surface of the prepared sample, set the electron microscope scanning parameters, and perform electron microscope scanning detection on the inclusions; By scanning the sample to obtain at least one of the following information: the number, type, size, composition, perimeter, and area of ​​inclusions within the scanned area, the distribution uniformity, circularity, and size uniformity of inclusions in the finished steel are defined as quantitative evaluation indicators for inclusions in steel. These indicators are then used to characterize the distribution, morphology, and size of inclusions, thereby obtaining a comprehensive and complete inclusion evaluation system. The distribution uniformity F of the inclusions is defined as , where N i is the number density of inclusions in a single scan area in a single sample, is the average number density, in a single sample, n is the number of divided areas, and in the entire finished product, n is the number of samples taken; The circularity e of the inclusion is defined as Among them, D S is the equivalent diameter of the inclusion area, D L is the equivalent diameter of the inclusion perimeter, S is the inclusion area, and L is the inclusion perimeter; The inclusion size distribution uniformity d is defined as Among them, in a single sample, D i and The size and average size of each inclusion obtained by automatic scanning electron microscopy, n is the number of divided areas, in the entire finished product, D i and To calculate the size of inclusions in each sample and the average size of the whole sample, n is the number of samples taken; A scanning area is defined on the detection surface of the prepared sample, and electron microscope scanning parameters are set to perform electron microscope scanning detection on the inclusions, wherein the setting of electron microscope scanning parameters includes: Set the scanning voltage setting range to 10-25kV; Set the magnification to 300-1000 times; Set the working distance to 16-18mm; Setting a reference material includes: pasting aluminum foil as a reference material at a position on the edge of the sample that is not to be analyzed; Set the scan area, including: Determine the scanning area; The scanning area of ​​the scanning area is ≥30 square millimeters; The setting of electron microscope scanning parameters also includes: Set the contrast setting, where the steel substrate contrast value is 200 and the aluminum foil contrast value is 60; Set the grayscale threshold. The grayscale of conventional inclusions is darker than that of the steel matrix, and the threshold range is 0-170. The grayscale of rare earth inclusions is lighter than that of the steel matrix, and two thresholds are set. The upper threshold range is 220-250, and the lower threshold range is 0-170.

2. The method for evaluating and analyzing inclusions in steel according to claim 1, wherein: The sample selection and preparation according to the shape of the finished steel product includes: grinding and polishing the detection surface parallel to the rolling direction.

3. The method for evaluating and analyzing inclusions in steel according to claim 2, wherein the finished steel products include rolled plates, bars and wires, and wherein: If the finished steel product is a rolled plate, at least three samples are taken from the rolled plate along the rolling direction, and at least one sample is taken from the rolled plate along the perpendicular rolling direction; and / or If the finished steel product is a bar, samples are taken from the cross section of the bar at equal intervals of the same angle and evenly along the radial direction, wherein the number of equal cross-sections is at least 3, the number of radial samples is at least one, and at least five samples are evenly taken along the rolling direction of the bar; and / or, If the finished steel is a wire, samples are taken at equal intervals of the same angle on the cross section of the wire, and samples are taken evenly along the radial direction, wherein the number of equal parts of the cross section is at least 3, the number of radial samples is at least one, and at least five samples are taken evenly along the rolling direction of the wire.

4. The method for evaluating and analyzing inclusions in steel according to claim 1, wherein: The determining of the scanning area includes: using a diagonal two-point method to determine the scanning area, and the area shape is a rectangle.

5. The method for evaluating and analyzing inclusions in steel according to claim 4, wherein: The scanning area is determined based on the size of the scanned inclusions.

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