Method and system for detecting inclusions in alloy

Abstract

The invention provides a method and system for detecting inclusions in alloy, and relates to the field of material analysis. The method for detecting the inclusions in the alloy comprises the following steps: selecting a scanning mode, and determining a threshold value of a real-time scanning contrast of a scanning electron microscope in a maximum scanning contrast interval according to a normal distribution curve of a contrast intermediate value of a matrix of a sample; according to the preset minimum inclusion size, the amplification factor and the resolution ratio are adjusted, area scanning is carried out to obtain a backscattered electron image of the inclusion in the alloy, the inclusion is subjected to recognition and statistical analysis, and an inclusion detection result is output; the normal distribution curve is # imgabs0 #; wherein the # imgabs 1 # is a contrast intermediate value of the matrix, and a is a matrix material coefficient and ranges from 0.8 to 3.3. According to the method and system for detecting the inclusions in the alloy, the detection efficiency and precision of the alloy inclusions are improved, the steelmaking process is optimized, and the steel quality is improved.

Description

Technical Field

[0001] This application relates to the field of material analysis, and particularly to a method and system for detecting inclusions in alloys. Background Art

[0002] Inclusions in steel materials not only damage the continuity and compactness of the steel matrix, but also have a very great impact on the mechanical properties and service performance of steel. They will reduce the strength, plasticity, toughness, fatigue resistance and corrosion resistance of steel, etc., thus affecting its mechanical properties and processing performance. In addition, some non-metallic inclusions may also have magnetism. By finely regulating the size, quantity, morphology, composition and distribution of these inclusions, the steelmaking technology can be effectively improved, thereby enhancing the quality of steel. Therefore, in the production process, in order to ensure the quality and performance of steel, it is necessary to strictly control the content and type of inclusions in steel.

[0003] An automatic inclusion scanning and statistical system using a scanning electron microscope / energy spectrometer can efficiently and comprehensively capture various information of inclusions in steel, overcoming the problems of low efficiency, easy omission and limited detection range of traditional manual detection. The principle of this automatic statistical system is based on the molecular weight difference between the matrix and inclusions, which is manifested as a contrast difference in the backscattered electron image. By presetting the contrast threshold between the matrix and the reference object, the system can accurately identify inclusions.

[0004] Traditional automatic inclusion scanning technology can only simply scan inclusions that appear black under the electron microscope, such as MnS, TiN, etc. However, with the development of the steel industry, high-quality steel has emerged. The elements added to steel are also more complex. Therefore, traditional scanning technology cannot accurately identify this type of composite inclusion. Therefore, how to accurately distinguish inclusions during the statistical process has become an urgent problem to be solved.

[0005] Document CN202410875188.8 discloses an automatic gray value adjustment method and device for inclusion statistics. After each acquisition of the field-of-view image, the field-of-view image is converted into gray value information and screened, and then the average value of the gray values of the matrix part is taken. However, the program is too complex and the detection requires real-time screening.

[0006] Document CN202311096239.9 discloses an inclusion analysis method and related equipment based on steel materials. This solution requires determining the brightness of the matrix and inclusions before detection, and performing a proportional calculation based on the brightness relationship in the image and the standard brightness. The accuracy of this correspondence is still difficult to meet the actual needs of scientific research during the scanning process.

[0007] Document CN202111635455.7 discloses a method and system for in-situ statistical distribution characterization of inclusions in steel. This solution can only identify inclusions that are darker in color compared to the matrix and cannot detect complex inclusions, having certain limitations.

[0008] Therefore, improving the detection efficiency and accuracy of inclusions in alloys is crucial for the development of material testing. Summary of the Invention

[0009] The purpose of this application is to provide a method and system for detecting inclusions in alloys to solve the above problems.

[0010] To achieve the above objectives, this application adopts the following technical solutions: A method for detecting inclusions in alloys, comprising: According to the normal distribution curve of the contrast median value of the matrix of the sample, determine the threshold of the real-time scanning contrast of the scanning electron microscope within the maximum scanning contrast interval; After correcting the threshold, select the scanning mode, adjust the magnification and resolution according to the preset target inclusion size, perform area scanning on the sample to obtain the backscattered electron image of the inclusions in the alloy, identify and statistically analyze the inclusions, and output the inclusion detection result; The normal distribution curve is: ; Wherein, is the contrast median value of the matrix, a is the matrix material coefficient, taking values in the range of 0.8 - 3.3. Among them, for Fe-based it is 2.37, for Ni-based it is 3.23, and for Ti-based it is 1.56.

[0011] Preferably, after determining the threshold of the real-time scanning contrast, it further includes: Using aluminum foil as a reference object, the selected matrix as the matrix, and the threshold as the verification scanning contrast, measure the actual contrast value of the aluminum foil I Al , when I Al meets the verification formula, it is determined that the threshold selection is correct; the verification formula is: ; Wherein, I Al is the actual contrast value of the aluminum foil; k 基 is the matrix indicator variable, which is 1 when the matrix type conforms and 0 when it does not conform; is the matrix type coefficient, 1 for Fe-based, 0.8 for Ni-based, 1.15 for Ti-based, -0.05 for Ce element, and -0.03 for La element; is the error term, and the maximum value is 200.

[0012] Preferably, the relationship between the target inclusion size, the magnification, and the resolution satisfies the following formula: ; where A is the target inclusion size, with the unit of μm; S is the absolute value of the area of the device display area, dimensionless; P is the single-side size of the scanning image pixel, with the unit of μm; mag is the magnification; y is the pixel size.

[0013] Preferably, when the target inclusion size is 0.2 - 10 µm, the magnification is 40 - 500 times, the resolution is 1 - 20 pixel; the scanning image size pixels are 1024×1024, 2048×2048, 4096×4096, or 8192×8192, and the corresponding single-side size of the scanning image pixel is 1024, 2048, 4096, or 8192; the image acquisition time is 1 - 10 µs, and the energy spectrum acquisition time is 0.2 - 5 s.

[0014] Preferably, the scanning mode includes a circular mode, a rectangular mode, or a trapezoidal mode.

[0015] Preferably, the area scanning further includes: Taking points within the set range according to the scanning mode for secondary focusing.

[0016] Preferably, the statistical analysis includes: According to the results of the area scanning, screening out the data where the components of the scanning results are all matrix, and the data with only C, O, and matrix; Conducting statistics according to the inclusion size and inclusion type; Calculating the number density according to the scanning results combined with the scanning area.

[0017] Preferably, the maximum scanning contrast interval is 0 - 32767.

[0018] Preferably, during the area scanning process, the spot size of the scanning electron microscope is 500 - 550, the scanning current is 1.1 - 1.4 nA, the scanning voltage is 15 kV or 20 kV, and the grating is 20 µm or 30 µm.

[0019] This application also provides a system for detecting inclusions in an alloy, which is used to execute the method for detecting inclusions in an alloy; The system includes: A scanning electron microscope / energy spectrometer, which is used to obtain the backscattered electron image and composition of inclusions in the alloy; A contrast monitoring module for real-time monitoring of changes in the image contrast value; An inclusion identification and statistical analysis module for identifying and statistically analyzing inclusions.

[0020] Compared with the prior art, the beneficial effects of this application include: For the method for detecting inclusions in an alloy provided by this application, first, according to the normal distribution curve of the contrast median value of the matrix, the contrast distribution interval of the matrix is removed within the maximum scanning contrast interval to obtain the threshold of the real-time scanning contrast of the scanning electron microscope, thereby reducing the inclusion identification error and improving the detection accuracy of inclusions in the alloy; further, by selecting the scanning mode, adjusting the magnification and resolution according to the preset minimum inclusion size, the minimum inclusion size that can be detected is broken through, and the detection can be made more accurate and efficient.

[0021] The system for detecting inclusions in an alloy provided by this application realizes the real-time monitoring of the image contrast value during the long-term test process, improving the accuracy and detection efficiency of inclusion detection.

[0022] The method and system for detecting inclusions in an alloy provided by this application contribute to optimizing the smelting process and improving the quality of the alloy. Description of the Drawings

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as limiting the scope of this application.

[0024] Figure 1 Schematic diagrams of different scanning modes; Figure 2 Analysis result diagram obtained in Embodiment 3; Figure 3 Inclusion distribution diagram obtained in Embodiment 4 and distinguished by different colors; Figure 4 Detection abnormal interface diagram obtained in Comparative Example 1. Detailed Embodiments

[0025] To better explain the technical solutions provided by this application, before the embodiments, the technical solutions will be presented as a whole, specifically as follows: A method for detecting inclusions in an alloy, comprising: Determining the threshold of the real-time scanning contrast of the scanning electron microscope within the maximum scanning contrast interval according to the normal distribution curve of the contrast median value of the matrix of the sample; After correcting the threshold, select the scanning mode. According to the preset target inclusion size, adjust the magnification and resolution, perform area scanning on the sample to obtain the backscattered electron image of inclusions in the alloy, identify and statistically analyze the inclusions, and output the inclusion detection results; The normal distribution curve is: ; Among them, is the contrast median value of the matrix, a is the matrix material coefficient, which takes values in the range of 0.8 - 3.3. Among them, for Fe-based it is 2.37, for Ni-based it is 3.23, and for Ti-based it is 1.56.

[0026] It should be noted that the sample needs to be pretreated before detection, generally including cold embedding, hot embedding, light curing, etc. Grind and polish the processed sample to be detected so that its surface has no obvious scratches. Paste conductive glue on the sample surface to make its conductivity better under electron microscope observation. Paste aluminum foil on the conductive glue so that it covers the part of the conductive glue used for contrast with the matrix contrast.

[0027] Cold embedding: Select appropriate embedding materials (such as epoxy resin or polyester resin) and molds. Ensure that the surface of the metal sample is clean, free of oil and oxides. Mix the resin and curing agent in a certain proportion. Place the metal sample in the mold, ensuring that the sample is in the appropriate position in the mold. Slowly pour the mixed resin into the mold to cover the metal sample. Let the resin cure at room temperature. Depending on the resin type, the curing time may range from several hours to one day. After the resin is completely cured, take out the embedded metal sample from the mold. Trim and polish the resin surface to make it smooth and flat.

[0028] Hot embedding: Clean the metal sample to ensure it is free of dirt. Place the sample in a hot embedding machine. According to the set program, select the appropriate embedding material (including conductive powder and non-conductive powder) to reach a certain temperature. After the program ends, take out the sample and trim and polish the embedded sample to ensure that the sample is firmly fixed and has a clean appearance.

[0029] After embedding, the sample can be set with regions on one plane and scanned by region, efficiently solving the problem of having to reset after scanning a single sample. For a group of samples, it is in the same detection environment, minimizing the errors generated during the testing process to the greatest extent.

[0030] Light curing: Select a resin and photoinitiator suitable for light curing. Ensure that the surface of the metal sample is clean. Mix the resin and photoinitiator. Place the metal sample in the mold and pour the mixed resin. Use an ultraviolet lamp to irradiate the mixture to initiate resin curing. The resin cures rapidly under ultraviolet light irradiation. After curing, take out the embedded metal sample from the mold and perform necessary trimming and polishing.

[0031] The alloy referred to in this application can be, for example, various steels, or other alloys that will produce inclusions during the smelting process.

[0032] It should be noted that the alloy not only refers to the final product of smelting, but can also be the product during the smelting process.

[0033] In an alternative embodiment, after determining the threshold of the real-time scanning contrast, the following steps are further included: Using aluminum foil as a reference object, the selected matrix as the matrix, and the threshold as the verification scanning contrast, measure the actual contrast value of the aluminum foil I Al , when I Al meets the verification formula, it is determined that the threshold selection is correct; the verification formula is: ; wherein, I Al is the actual contrast value of the aluminum foil; k 基 is the indication variable of the matrix, which is 1 when the matrix type conforms, and 0 when it does not conform; is the type coefficient of the matrix, 1 for Fe-based, 0.8 for Ni-based, 1.15 for Ti-based, -0.05 for Ce element, and -0.03 for La element; is the error term, and the maximum value is 200.

[0034] The contrast threshold determined according to the normal distribution formula may still not be able to accurately determine the actual appropriate contrast threshold. Therefore, aluminum foil is used as a reference object to verify the threshold. Usually, k 基 is selected as 1, that is, it is first assumed that the matrix conforms during verification. If the error between the actual detected contrast value and the calculated contrast value of the formula is controlled within 200 and 200, it can be considered that the determined contrast threshold is appropriate. This verification process further ensures the accuracy of the determined threshold. If it does not conform, correction is performed by adjusting the contrast, brightness, and filament position.

[0035] Ce element and La element usually exist as doping elements and do not appear in the form of pure matrix. During verification, their relevant data are introduced to ensure the accuracy of the verification result.

[0036] In an alternative embodiment, the relationship between the target inclusion size, the magnification, and the resolution satisfies the following formula: ; wherein, A is the target inclusion size, with the unit of μm; Sis the absolute value of the area of the device display area (this value is related to the device), dimensionless; P is the single-side dimension of the pixels of the scanned image, with the unit of μm; mag is the magnification; y is the pixel size.

[0037] In an optional embodiment, when the inclusion size is 0.2 - 10 μm, the magnification is 40 - 500 times, and the resolution is 1 - 20 pixels; the pixel size of the scanned image is 1024×1024, 2048×2048, 4096×4096 or 8192×8192, and the corresponding single-side dimension of the pixels of the scanned image is 1024, 2048, 4096 or 8192; the image acquisition time is 1 - 10 μs, and the energy spectrum acquisition time is 0.2 - 5 s.

[0038] Preferably, when the target inclusion size is 0.2 - 10 μm, the magnification is 100 - 300 times, and the resolution is 3 - 15 pixels; the pixel size of the scanned image is 1024×1024, 2048×2048, 4096×4096, and the corresponding single-side dimension of the pixels of the scanned image is 1024, 2048 or 4096; the image acquisition time is 1 - 6 μs, and the energy spectrum acquisition time is 0.2 - 3 s.

[0039] In an optional embodiment, the scanning mode includes a circular mode, a rectangular mode or a trapezoidal mode.

[0040] The three scanning modes are as Figure 1 shown.

[0041] Preferably, the trapezoidal mode, and the scanning area is 3mm * 3mm, 5mm * 5mm, 7mm * 7mm, 10mm * 10mm, etc.

[0042] In an optional embodiment, the area scanning further includes: Taking points within the set range according to the scanning mode for secondary focusing.

[0043] In an optional embodiment, the statistical analysis includes: According to the results of the area scanning, screening out the data whose scanning result components are all matrix, and the data with only C, O and matrix; Statistical analysis is carried out according to the inclusion size and inclusion type; According to the scanning results combined with the scanning area, the number density is calculated.

[0044] In an optional embodiment, the maximum scanning contrast interval is 0 - 32767.

[0045] In an alternative embodiment, during the area scanning process, the spot size of the scanning electron microscope is 500 - 550, the scanning current is 1.1 - 1.4 nA, the scanning voltage is 15 kV or 20 kV, and the grating is 20 μm or 30 μm.

[0046] The present application also provides a system for detecting inclusions in an alloy, which is used to execute the method for detecting inclusions in an alloy; The system includes: A scanning electron microscope / energy spectrometer, which is used to obtain the backscattered electron image and composition of inclusions in the alloy; A contrast monitoring module, which is used to monitor the change of the image contrast value in real time; An inclusion identification and statistical analysis module, which is used to identify and statistically analyze inclusions.

[0047] The embodiments of the present application will be described in detail below in conjunction with specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0048] Example 1 This example provides a system for detecting inclusions in an alloy, including: a scanning electron microscope / energy spectrometer, a contrast monitoring module, and an inclusion identification and statistical analysis module; The scanning electron microscope / energy spectrometer is used to obtain the backscattered electron image and composition of inclusions in the alloy; the contrast monitoring module is used to monitor the change of the image contrast value in real time; the inclusion identification and statistical analysis module is used to identify and statistically analyze inclusions.

[0049] Example 2 This example provides a method for detecting inclusions in an alloy. The sample is a superalloy smelted in a vacuum induction furnace, and the specific grade is GH4169. The system for detecting inclusions in the alloy provided in Example 1 is used for detection, which specifically includes the following steps: (1) Cold mount the sample, and polish the processed sample to be detected so that its surface has no obvious scratches. Paste a conductive adhesive on the surface of the sample to make its conductivity better under electron microscope observation, and paste an aluminum foil on the conductive adhesive to cover the part on the conductive adhesive used for contrast with the matrix.

[0050] (2) Start the scanning electron microscope / energy spectrometer and name the storage path; set the scanning according to the type of inclusions to more accurately obtain the chemical composition, size, morphology, and coordinate position data of the inclusions.

[0051] During the process of detecting inclusions, set the spot size of the electron microscope to 500.

[0052] (3) Select nickel metal as the matrix, and the intermediate value of the matrix contrast makes it satisfy the following normal distribution: , where a takes the value of 3.23.

[0053] Within the maximum contrast range of 0 - 32767, according to the range corresponding to removing the intermediate value of the matrix contrast (μ ± 3σ, μ is the x corresponding to the maximum value of the normal curve, σ = 616.25a), determine the thresholds of the real-time scanning contrast of the scanning electron microscope to be 0 - 12000 and 21984 - 32767.

[0054] Add a reference aluminum foil, and use the above thresholds to verify the scanning contrast and measure the actual contrast value of the aluminum foil , and when it meets the following formula, it can ensure a relatively accurate inclusion contrast range: , Since the matrix of the test sample is Ni, its value is 0.8, and the value detected by the experiment is 2300, and the difference is 100, which is less than 200. Based on this, the above threshold values are reasonable.

[0055] (4) According to the target inclusion size required by the user (i.e., the minimum inclusion size set by the user), set the relationship between the magnification and the resolution to enable scanning of the required minimum inclusion size, scan, identify, and count the inclusions. The sample scanning mode can be circular, rectangular, trapezoidal, etc.

[0056] The relationship between the target inclusion size, the magnification, and the resolution satisfies the following formula: ; Among them, the absolute value S of the area of the display area in this device is 1.522, the minimum inclusion size detection is 0.38 µm, the magnification is 219 times, the resolution is 3 pixels, the pixel size of the scanned image is 2048×2048, the image acquisition time is 3 µs, and the energy spectrum acquisition time is 0.3 s.

[0057] The scanning mode is trapezoidal, and the scanning area is 5*5 mm.

[0058] When it is detected that the contrast value deviates from the preset value, adjust the filament position to make the image contrast value return to the normal range; the scanning current is 1.3 nA, the scanning voltage is 20 kV, and the grating is 30 µm.

[0059] (5) Take 4 points within the set area range for secondary focusing to ensure the accuracy of scanning and output the inclusion detection results.

[0060] The process of inclusion analysis includes one or more of the following steps: (1) According to the scanning results, filter out the data whose scanned components are all matrix, and the data with only C, O and matrix; (2) According to the scanning results, statistics can be carried out according to the inclusion size; (3) According to the scanning results combined with the scanned area obtained from the experimental detection, further calculations such as number density are carried out.

[0061] The final detection results are shown in Table 1: Table 1 Detection Results of Example 2

[0062] Example 3 Referring to the method provided in Example 2, samples of steel in the whole smelting process are taken for testing. The system for detecting inclusions in alloys provided in Example 1 is used for detection, which specifically includes the following steps: (1) Cold mount the specimen, and polish the processed sample to be detected so that its surface has no obvious scratches. Paste conductive glue on the specimen surface to make its conductive effect better under electron microscope observation.

[0063] (2) Start the scanning electron microscope / energy spectrometer and name the storage path; Set the scan according to the type of inclusion to more accurately obtain the chemical composition, size, morphology and coordinate position data of the inclusion.

[0064] During the process of detecting inclusions, set the spot size of the electron microscope to 530.

[0065] (3) Iron is used as the matrix, and the median value of the matrix contrast makes it satisfy the following normal distribution: , where a takes the value of 2.37.

[0066] Within the maximum contrast range of 0 - 32767, remove the range corresponding to the median value of the matrix contrast (μ ± 3σ, μ is the x corresponding to the maximum value of the normal curve, σ = 616.25a), and determine the threshold of the real-time scanning contrast of the scanning electron microscope to be 0 - 12000 and 20384 - 32767.

[0067] Add a reference object aluminum foil, and use the above threshold as the verification scanning contrast to measure the actual contrast value of the aluminum foil , and when it meets the following formula, it can ensure a relatively accurate inclusion contrast range: , Since the matrix of the test sample is Fe, its value is 1, the value detected by the experiment is 3000, and the difference is 0, which is less than 200. Based on this, the value of the above threshold is reasonable.

[0068] (4) According to the target inclusion size required by the user, set the relationship between the magnification and the resolution, so as to be able to scan the minimum inclusion size required, scan, identify and count the inclusions. The sample scanning mode can be circular, rectangular, trapezoidal, etc.

[0069] The relationship between the target inclusion size, the magnification and the resolution satisfies the following formula: ; Among them, the absolute value S of the area of the display area in this device is 1.522, the minimum inclusion size detected is 1 µm, the magnification is 117 times, the resolution is 5 pixels, the pixel size of the scanned image is 1024×1024, the image acquisition time is 2 µs, and the energy spectrum acquisition time is 0.4 s.

[0070] The scanning mode is rectangular, and the scanning area is 7*7 mm. At the same time, draw 3 regions in a plane to save time to the greatest extent.

[0071] When it is detected that the contrast value deviates from the preset value, adjust the filament position to make the image contrast value return to the normal range; the scanning current is 1.2 nA, the scanning voltage is 15 kV, and the grating is 20 µm.

[0072] (5) Take 4 points within the set area range for secondary focusing to ensure the accuracy of the scan and output the inclusion detection result.

[0073] The inclusion analysis process includes one or more of the following steps: (1) According to the scanning result, filter out the data whose scanning result components are all matrix, and the data with only C, O and matrix; (2) According to the scanning result, statistics can be carried out according to the inclusion size; (3) According to the scanning result and the scanning area obtained from the test detection, further calculations such as number density are carried out.

[0074] The analysis result is as Figure 2 shown.

[0075] Example 4 Referring to the method provided in Example 2, rare earth Ce was added to ferritic stainless steel for laboratory smelting, and samples were sent for testing to ensure the smooth addition of Ce. The system for detecting inclusions in the alloy provided in Example 1 was used for detection, which specifically included the following steps: (1) The sample to be detected was polished to make its surface have no obvious scratches, and a relatively flat test surface was obtained. Conductive glue was pasted on the surface of the specimen to make its conductivity better under electron microscope observation.

[0076] (2) The scanning electron microscope / energy spectrometer was started, and the storage path was named; the scanning was set according to the type of inclusions to more accurately obtain the chemical composition, size, morphology, and coordinate position data of the inclusions.

[0077] During the process of detecting inclusions, the spot size of the electron microscope was set to 550.

[0078] (3) Iron was used as the matrix, and the median value of the matrix contrast made it satisfy the following normal distribution: , where a takes the value of 1.

[0079] In the range of the maximum contrast interval 0 - 32767, the range corresponding to the median value of the matrix contrast (μ ± 3σ, μ is the x corresponding to the maximum value of the normal curve, σ = 616.25a) was removed, and the threshold values of the real-time scanning contrast of the scanning electron microscope were determined to be 0 - 12000 and 20384 - 32767.

[0080] Since there are two obvious types of inclusions in the steel, in order to make the contrast between black and white inclusions greater, the contrast value range of the inclusions is 0 - 12000 and 20500 - 32767.

[0081] A reference aluminum foil was added, and the above threshold values were used to verify the scanning contrast, and the actual contrast value of the aluminum foil was measured , and when it meets the following formula, it can ensure a relatively accurate inclusion contrast interval: , The matrix of the test sample is Fe, and its value is 1. Since the rare earth content in the steel cannot be ignored, the influence of rare earth on the matrix should also be considered, and its value is -0.15. The value detected by the experiment is 2700, and the difference . Based on this, the above threshold values are reasonable.

[0082] (4) According to the target inclusion size required by the user, the relationship between the magnification and the resolution was set to enable scanning of the smallest required inclusion size, and the inclusions were scanned, identified, and counted. The sample scanning mode can be circular, rectangular, trapezoidal, etc.

[0083] The relationship between the target inclusion size, magnification, and resolution satisfies the following formula: ; Among them, the absolute value S of the area of the display region in this device is 1.522, the minimum inclusion size detected is 0.21 µm, the magnification is 400 times, the resolution is 3 pixels, the pixel size of the scanned image is 2048×2048, the image acquisition time is 2 µs, and the energy spectrum acquisition time is 0.3 s.

[0084] The scanning mode is trapezoidal, and the scanning area is 3*3 mm. At the same time, 3 regions in a plane are drawn to save time to the greatest extent.

[0085] When it is detected that the contrast value deviates from the preset value, adjust the filament position to make the image contrast value return to the normal range; the scanning current is 1.4 nA, the scanning voltage is 20 kV, and the grating is 30 µm.

[0086] (5) Take 4 points within the set area range for secondary focusing to ensure the accuracy of scanning and output the inclusion detection result.

[0087] The process of inclusion analysis includes one or more of the following steps: (1) According to the scanning result, filter out the data whose scanning result components are all matrix, and the data with only C, O, and matrix; (2) According to the scanning result, statistics can be carried out according to the inclusion size; (3) According to the scanning result and the scanned area obtained by experimental detection, further calculations such as number density are carried out.

[0088] Distinguished by different colors, the obtained inclusion distribution map is as Figure 3 shown.

[0089] Comparative Example 1 Different from Example 3, a is selected as 2.9, and the contrast threshold is selected as 0-11022 and 21745-32767.

[0090] When using aluminum foil for verification, since the matrix of the test sample is Fe, its value is 1, and the value detected by the experiment is 2700, , based on this, its value is unreasonable, further indicating that the inclusion contrast range is inaccurate.

[0091] When the system for detecting inclusions in alloys provided by this application uses the above contrast threshold for detection, detection anomalies occur, and the system interface is as Figure 4 shown.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for detecting inclusions in an alloy, characterized in that: include: According to the normal distribution curve of the contrast intermediate value of the matrix of the sample, a threshold value of the real-time scanning contrast of the scanning electron microscope is determined within the maximum scanning contrast interval; After correcting the threshold, a scanning mode is selected, and according to a preset target inclusion size, the magnification and resolution are adjusted, a regional scan is performed on the sample to obtain a backscattered electron image of inclusions in the alloy, the inclusions are identified and statistically analyzed, and the inclusion detection results are output; The normal distribution curve is: ； in, is the contrast median value of the matrix, a is the matrix material coefficient, which is in the range of 0.8-3.3, wherein the Fe-based is 2.37, the Ni-based is 3.23, and the Ti-based is 1.

56.

2. The method for detecting inclusions in an alloy according to claim 1, characterized in that: After determining the threshold of the real-time scanning contrast, the method further includes: The aluminum foil is used as a reference, the selected substrate is used as a substrate, and the threshold is used as a verification scan contrast to determine the actual contrast value of the aluminum foil. I Al ,when I Al When the verification formula is satisfied, it is determined that the threshold is selected correctly; the verification formula is: ； in, I Al is the actual contrast value of aluminum foil; k 基 is the indicator variable of the matrix, which is 1 when the matrix type is consistent and 0 when it is not consistent; is the type coefficient of the matrix, which is 1 for Fe-based, 0.8 for Ni-based, 1.15 for Ti-based, -0.05 for Ce element, and -0.03 for La element; is the error term, and its maximum value is 200.

3. The method for detecting inclusions in an alloy according to claim 1, characterized in that: The relationship between the target inclusion size, the magnification and the resolution satisfies the following formula: ； in, A is the target inclusion size, in μm; S It is the absolute value of the area of ​​the device display area, dimensionless; P is the single-side size of the scanned image pixel, in μm; mag is the magnification; y is the pixel size.

4. The method for detecting inclusions in an alloy according to claim 3, characterized in that: When the target inclusion size is 0.2-10µm, the magnification is 40-500 times and the resolution is 1-20pixel; the scanning image size pixel is 1024×1024, 2048×2048, 4096×4096 or 8192×8192, and the corresponding scanning image pixel single-side size is 1024, 2048, 4096 or 8192; the image acquisition time is 1-10µs, and the energy spectrum acquisition time is 0.2-5s.

5. The method for detecting inclusions in an alloy according to claim 1, characterized in that: The scanning pattern includes a circular pattern, a rectangular pattern or a trapezoidal pattern.

6. The method for detecting inclusions in an alloy according to claim 5, characterized in that: The area scan also includes: According to the scanning mode, a point is selected within the set range and secondary focusing is performed.

7. The method for detecting inclusions in an alloy according to claim 1, characterized in that: The statistical analysis includes: According to the results of the area scan, data whose scanning results are all composed of matrix and data whose scanning results are composed of only C, O and matrix are screened out; Statistics are made by inclusion size and inclusion type; The number density is calculated based on the scanning results and the scanning area.

8. The method for detecting inclusions in an alloy according to claim 1, characterized in that: The maximum scanning contrast range is 0-32767.

9. The method for detecting inclusions in an alloy according to claim 1, characterized in that: During the area scanning, the spot size of the scanning electron microscope is 500-550, the scanning current is 1.1-1.4 nA, the scanning voltage is 15 kV or 20 kV, and the grating is 20 μm or 30 μm.

10. A system for detecting inclusions in an alloy, characterized in that: Used to perform the method for detecting inclusions in an alloy as described in any one of claims 1 to 9; The system comprises: Scanning electron microscope / energy dispersive spectrometer to obtain backscattered electron images and composition of inclusions in alloys; Contrast monitoring module, used to monitor the changes of image contrast value in real time; The inclusion identification and statistical analysis module is used to identify and statistically analyze inclusions.

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