A method for evaluating grain size of tungsten carbide-based hard alloy and tungsten carbide-based hard alloy

Abstract

The application provides a tungsten carbide-based hard alloy grain size evaluation method and a tungsten carbide-based hard alloy, and the evaluation method comprises the following steps: (1) obtaining grain size data of the tungsten carbide-based hard alloy based on EBSD analysis, and calculating effective grain size D mgs ; (2) combining the grain size estimated value D of the tungsten carbide-based hard alloy with the effective grain size D mgs , and evaluating the grain size of the tungsten carbide-based hard alloy; wherein in the formula of the effective grain size, the evaluation method provided by the application utilizes the grain size data obtained by EBSD analysis for weighted average processing, and the coefficient is corrected according to tungsten carbide-based hard alloy samples with different estimated grain sizes, so that the microstructure performance difference of tungsten carbide-based hard alloys from different sources can be accurately characterized and evaluated.

Description

Technical Field

[0001] This invention belongs to the field of analytical measurement technology, and relates to a method for evaluating grain size, and more particularly to a method for evaluating the grain size of tungsten carbide-based cemented carbide and the tungsten carbide-based cemented carbide. Background Technology

[0002] Electron backscatter diffraction (EBSD) is a characterization technique that utilizes the diffraction phenomenon of backscattered electrons to analyze the microstructure of materials such as metal or metal compound powders and alloys. For alloys with tungsten carbide (WC) as the hard phase, EBSD analysis can be used to identify and analyze the crystallographic structural characteristics of the hard phase grains, including their morphology, size, crystal axis orientation, grain boundary type, and distribution.

[0003] Since the above characteristics are directly related to the application performance of cemented carbide, accurately characterizing and evaluating the grain distribution state of cemented carbide, especially the average grain size, can help researchers grasp the microstructure performance level of the material. This allows for more accurate quantitative evaluation of tungsten carbide-based cemented carbide that cannot be further subdivided using traditional characterization methods such as Fisher's grain size, laser grain size distribution, and scanning electron microscopy, and enables more scientific predictions and inferences about the application performance of the product.

[0004] CN103902841A discloses a method for quantitatively analyzing the grain size of body-centered cubic alloy solidification microstructure using EBSD measurement. The method includes: 1. acquiring EBSD data; 2. establishing a two-dimensional array; 3. establishing a rotation matrix and a growth orientation matrix; 4. assigning properties to precipitated phase elements; 5. transforming dendritic structures into granular structures; 6. calculating the equivalent diameter of the grains; and 7. calculating the average equivalent diameter of the grains along the gravitational direction. This invention can analyze both granular and dendritic structures, evaluating grain size and distribution characteristics, and subsequently using grain size grading standards to evaluate mechanical properties. However, this invention addresses the technical problem that current EBSD measurements, which measure dendritic structures rather than granular structures, cannot evaluate grain size and is not applicable to the evaluation of tungsten carbide-based cemented carbide grain size.

[0005] Therefore, how to provide a method for evaluating the grain size of tungsten carbide-based cemented carbide, and accurately characterize and evaluate the differences in microstructure and properties of tungsten carbide-based cemented carbide from different sources, has become an urgent problem that needs to be solved by those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for evaluating the grain size of tungsten carbide-based cemented carbide and the tungsten carbide-based cemented carbide. The evaluation method uses the grain size data obtained by EBSD analysis for weighted averaging and performs coefficient correction according to tungsten carbide-based cemented carbide samples with different estimated grain sizes, thereby achieving accurate characterization and evaluation of the differences in microstructure and properties of tungsten carbide-based cemented carbide from different sources.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for evaluating the grain size of tungsten carbide-based cemented carbide, the evaluation method comprising the following steps:

[0009] (1) Grain size data of tungsten carbide-based cemented carbide were obtained based on EBSD analysis, and the effective grain size D was calculated. mgs ;

[0010] (2) Combining the estimated grain size D of tungsten carbide-based cemented carbide with the effective grain size D obtained in step (1) mgs The grain size of the tungsten carbide-based cemented carbide was evaluated.

[0011] Among them, the effective grain size mentioned in step (1) In the formula, And D i It is the diameter of the equal-area circle of the i-th effective statistical grain obtained from EBSD analysis, n is the number of effective statistical grains, and c is the correction factor.

[0012] This invention proposes an effective grain size D for characterizing tungsten carbide-based cemented carbide. mgs Compared to the general average grain size of metals (the calculation method is detailed in GB / T 36165-2018 Determination of Average Grain Size of Metals by Electron Backscatter Diffraction (EBSD)), the main difference of this invention is that it uses the grain size data obtained by EBSD analysis for weighted averaging and performs coefficient correction based on tungsten carbide-based cemented carbide samples with different estimated grain sizes, thereby achieving accurate characterization and evaluation of the differences in microstructure and properties of tungsten carbide-based cemented carbide from different sources.

[0013] In this invention, the calculation method for the diameter of the equal-area circle of the i-th effective statistical grain refers to "GB / T36165-2018 Determination of Average Grain Size of Metals - Electron Backscattering Diffraction (EBSD) Method", and the specific calculation formula is as follows: Among them, A i It is the scan area of ​​the i-th valid statistical grain.

[0014] Preferably, the value of the correction coefficient c is in the range of 0.88-0.98, for example, it can be 0.88, 0.89, 0.90, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97 or 0.98, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] Preferably, step (1) determines the value of the correction coefficient c based on the estimated grain size D of the tungsten carbide-based cemented carbide, specifically as follows:

[0016] When D∈[0.05μm, 1.0μm), the correction coefficient c=0.88.

[0017] When D∈[1.0μm, 3.0μm), the correction coefficient c=0.92.

[0018] When D∈[3.0μm, 10.0μm), the correction coefficient c=0.95.

[0019] When D∈[10.0μm, 25.0μm), the correction coefficient c=0.98.

[0020] Preferably, the EBSD analysis in step (1) includes sample preparation, estimated grain size, sample loading, step size selection, field of view selection, EBSD scanning, and data processing performed sequentially.

[0021] Preferably, the sample preparation includes cutting, mounting, and polishing performed sequentially.

[0022] Preferably, the surface size of the sample obtained after cutting for testing is (5-8) mm × (5-8) mm or For example, it could be 5mm×5mm, 6mm×6mm, 7mm×7mm, 8mm×8mm, or However, this does not apply to all values ​​listed; other unlisted values ​​within this range also apply.

[0023] In this invention, the mounting process is consistent with the conventional cemented carbide mounting process, so it will not be described in detail here.

[0024] Preferably, the polishing includes mechanical polishing and / or focused ion beam etching.

[0025] This invention removes surface stress from the sample through polishing and improves the smoothness of the sample surface.

[0026] Preferably, the estimated grain size is performed using scanning electron microscopy and / or EBSD pre-scanning.

[0027] Preferably, the scanning electron microscopy method specifically involves directly measuring the grain size in the horizontal direction using a secondary electron observation mode to obtain the estimated grain size D of the tungsten carbide-based cemented carbide.

[0028] Preferably, the EBSD pre-scan method specifically involves using EBSD attachments to scan several lines to estimate the grain size, thereby obtaining the estimated grain size D of the tungsten carbide-based cemented carbide.

[0029] In this invention, the sample loading specifically involves fixing the sample on a sample stage tilted at 70° to ensure the sample is stable and has good conductivity. Then, the sample stage is installed in the sample chamber, and an appropriate magnification is selected to dynamically focus on the upper, middle, and lower regions within the sample's field of view, so that each point can be clearly displayed.

[0030] Preferably, the step size selection is specifically adjusted to 1 / 50-1 / 10 of the estimated grain size D of the tungsten carbide-based cemented carbide. For example, it can be 1 / 50, 1 / 40, 1 / 30, 1 / 20 or 1 / 10, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] Preferably, the selection of the field of view specifically involves selecting at least two fields of view to scan the sample under test, and determining the number of samples based on the estimated grain size D of the tungsten carbide-based cemented carbide.

[0032] Preferably, the criteria for determining the sample size are:

[0033] When D∈[0.05μm, 1.0μm), it is guaranteed that each field of view contains at least 750 complete grains, and all fields of view contain at least 1500 complete grains. For example, the number of complete grains contained in each field of view can be 750, 760, 770, 780, 790 or 800, and the number of complete grains contained in all fields of view can be 1500, 1520, 1540, 1560, 1580 or 1600, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0034] When D∈[1.0μm, 3.0μm), it is guaranteed that each field of view contains at least 500 complete grains, and all fields of view contain at least 1000 complete grains. For example, the number of complete grains in each field of view can be 500, 510, 520, 530, 540 or 550, and the number of complete grains in all fields of view can be 1000, 1020, 1040, 1060, 1080 or 1100, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0035] When D∈[3.0μm, 10.0μm), it is guaranteed that each field of view contains at least 300 complete grains, and all fields of view contain at least 600 complete grains. For example, the number of complete grains contained in each field of view can be 300, 310, 320, 330, 340 or 350, and the number of complete grains contained in all fields of view can be 600, 620, 640, 660, 680 or 700, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0036] When D∈[10.0μm, 25.0μm), it is guaranteed that each field of view contains at least 250 complete grains, and all fields of view contain at least 500 complete grains. For example, the number of complete grains contained in each field of view can be 250, 260, 270, 280, 290 or 300, and the number of complete grains contained in all fields of view can be 500, 520, 540, 560, 580 or 600, but it is not limited to the listed values. Other unlisted values ​​within this range also apply.

[0037] Preferably, the data processing includes sequentially acquiring the original grain size data, removing noise, and acquiring the processed grain size data.

[0038] In this invention, the detailed steps of data processing are described in accordance with GB / T 36165-2018 "Determination of average grain size of metals by electron backscatter diffraction (EBSD) method", and therefore will not be repeated here.

[0039] Preferably, the grain size evaluation standard for the tungsten carbide-based cemented carbide in step (2) is:

[0040] When D∈[0.05μm, 1.0μm), if D mgs If the tungsten carbide-based cemented carbide is within the range of [0.99×D,+∞), then it meets the high-quality grain size standard; otherwise, it does not.

[0041] When D∈[1.0μm, 3.0μm), if D mgs If the tungsten carbide-based cemented carbide is within the range of [0.97×D,+∞), then it meets the high-quality grain size standard; otherwise, it does not.

[0042] When D∈[3.0μm, 10.0μm), if D mgs If the tungsten carbide-based cemented carbide is within the range of [0.95×D,+∞), then it meets the high-quality grain size standard; otherwise, it does not.

[0043] When D∈[10.0μm, 25.0μm), if D mgsIf the tungsten carbide-based cemented carbide is within the range of [0.93×D,+∞), then it meets the high-quality grain size standard; otherwise, it does not.

[0044] As a preferred technical solution of the present invention, the evaluation method includes the following steps:

[0045] (1) Grain size data of tungsten carbide-based cemented carbide were obtained based on EBSD analysis, and the effective grain size was calculated. In the formula, And D i It is the diameter of the equal-area circle of the i-th effective statistical grain obtained from EBSD analysis, where n is the number of effective statistical grains and c is the correction factor.

[0046] The value of the correction factor c is determined based on the estimated grain size D of the tungsten carbide-based cemented carbide, specifically as follows:

[0047] When D∈[0.05μm, 1.0μm), the correction coefficient c=0.88;

[0048] When D∈[1.0μm, 3.0μm), the correction coefficient c=0.92;

[0049] When D∈[3.0μm, 10.0μm), the correction coefficient c=0.95;

[0050] When D∈[10.0μm, 25.0μm), the correction coefficient c=0.98;

[0051] The EBSD analysis includes sequential steps such as sample preparation, grain size estimation, sample loading, step size selection, field of view selection, EBSD scanning, and data processing.

[0052] (2) Combining the estimated grain size D of tungsten carbide-based cemented carbide with the effective grain size D obtained in step (1) mgs The grain size of the tungsten carbide-based cemented carbide is evaluated, and the evaluation criteria are as follows:

[0053] When D∈[0.05μm, 1.0μm), if D mgs If the tungsten carbide-based cemented carbide is within the range of [0.99×D,+∞), then it meets the high-quality grain size standard; otherwise, it does not.

[0054] When D∈[1.0μm, 3.0μm), if D mgs If the tungsten carbide-based cemented carbide is within the range of [0.97×D,+∞), then it meets the high-quality grain size standard; otherwise, it does not.

[0055] When D∈[3.0μm, 10.0μm), if D mgsIf the tungsten carbide-based cemented carbide is within the range of [0.95×D,+∞), then it meets the high-quality grain size standard; otherwise, it does not.

[0056] When D∈[10.0μm, 25.0μm), if D mgs If the tungsten carbide-based cemented carbide is within the range of [0.93×D,+∞), then it meets the high-quality grain size standard; otherwise, it does not.

[0057] In a second aspect, the present invention provides a tungsten carbide-based cemented carbide that meets the high-quality grain size standard obtained according to the evaluation method described in the first aspect.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] This invention proposes an effective grain size D for characterizing tungsten carbide-based cemented carbide. mgs Compared to the average grain size of metals in the general sense, the main difference of this invention is that it uses the grain size data obtained by EBSD analysis for weighted averaging and performs coefficient correction according to tungsten carbide-based cemented carbide samples with different estimated grain sizes, thereby realizing accurate characterization and evaluation of the differences in microstructure and properties of tungsten carbide-based cemented carbide from different sources. Attached Figure Description

[0060] Figure 1 The image is an EBSD scan image provided in Example 1;

[0061] Figure 2 The image is an EBSD scan image provided in Example 2;

[0062] Figure 3 The image is an EBSD scan image provided in Example 3;

[0063] Figure 4 This is the EBSD scan image provided in Example 4. Detailed Implementation

[0064] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0065] Example 1

[0066] This embodiment provides a method for evaluating the grain size of tungsten carbide-based cemented carbide and a tungsten carbide-based cemented carbide. The evaluation method includes the following steps:

[0067] (1) EBSD analysis, specifically:

[0068] (1.1) Sample preparation, including cutting, mounting and polishing in sequence; wherein, the surface size of the sample block obtained after cutting is 6mm×6mm; the polishing includes low-speed mechanical polishing and focused ion beam etching in sequence to remove surface stress of the sample and improve the flatness of the sample surface;

[0069] (1.2) The grain size was estimated by scanning electron microscopy. Specifically, the grain size was directly measured in the horizontal direction using the secondary electron observation mode, and the estimated grain size of tungsten carbide-based cemented carbide was D = 0.9 μm.

[0070] (1.3) Sample loading: Specifically, the sample is fixed on a sample stage tilted at 70° to ensure that the sample is stable and has good conductivity. Then, the sample stage is installed in the sample chamber. Select an appropriate magnification and dynamically focus on the upper, middle and lower areas of the sample field of view so that each point can be clearly displayed.

[0071] (1.4) Select the step size. Specifically, adjust the test step size to 1 / 18 of the estimated grain size D of the tungsten carbide-based cemented carbide, which is 0.05 μm.

[0072] (1.5) Select the field of view. Specifically, select two fields of view to scan the sample under test, and determine the number of samples based on the estimated grain size D of the tungsten carbide-based cemented carbide. Since D = 0.9 μm ∈ [0.05 μm, 1.0 μm), ensure that each field of view contains at least 750 complete grains, and all fields of view contain at least 1500 complete grains.

[0073] (1.6) Adjust the testing conditions of the scanning electron microscope and EBSD, perform EBSD scanning, and obtain high-quality scan images. Figure 1 ;

[0074] (1.7) Data processing, including sequentially acquiring raw grain size data, removing noise, and acquiring processed grain size data;

[0075] (1.8) Based on the grain size data of the tungsten carbide-based cemented carbide obtained in step (1.7), calculate the effective grain size. in, And D i It is the diameter of the equal-area circle of the i-th effective statistical grain obtained from EBSD analysis. In this embodiment, the number of complete grains is 1905.

[0076] (2) Since D = 0.9μm ∈ [0.05μm, 1.0μm), and D mgs =0.966μm∈[0.99×D,+∞)=[0.891μm,+∞), then the tungsten carbide-based cemented carbide meets the high-quality grain size standard.

[0077] Example 2

[0078] This embodiment provides a method for evaluating the grain size of tungsten carbide-based cemented carbide and a tungsten carbide-based cemented carbide. The evaluation method includes the following steps:

[0079] (1) EBSD analysis, specifically:

[0080] (1.1) Sample preparation, including cutting, mounting and polishing in sequence; wherein, the surface size of the sample block obtained after cutting is 5mm×5mm; the polishing includes low-speed mechanical polishing and focused ion beam etching in sequence to remove surface stress of the sample and improve the flatness of the sample surface.

[0081] (1.2) The grain size was estimated by using the EBSD pre-scanning method. Specifically, the grain size was estimated by scanning several lines of the EBSD attachment, and the estimated grain size of the tungsten carbide-based cemented carbide was D = 2.1 μm.

[0082] (1.3) Sample loading: Specifically, the sample is fixed on a sample stage tilted at 70° to ensure that the sample is stable and has good conductivity. Then, the sample stage is installed in the sample chamber. Select an appropriate magnification and dynamically focus on the upper, middle and lower areas of the sample field of view so that each point can be clearly displayed.

[0083] (1.4) Select the step size. Specifically, adjust the test step size to 1 / 21 of the estimated grain size D of the tungsten carbide-based cemented carbide, which is 0.1 μm.

[0084] (1.5) Select the field of view. Specifically, select two fields of view to scan the sample under test, and determine the number of samples based on the estimated grain size D of the tungsten carbide-based cemented carbide. Since D = 2.1 μm ∈ [1.0 μm, 3.0 μm), ensure that each field of view contains at least 500 complete grains, and that all fields of view contain at least 1000 complete grains.

[0085] (1.6) Adjust the testing conditions of the scanning electron microscope and EBSD, perform EBSD scanning, and obtain high-quality scan images. Figure 2 ;

[0086] (1.7) Data processing, including sequentially acquiring raw grain size data, removing noise, and acquiring processed grain size data;

[0087] (1.8) Based on the grain size data of the tungsten carbide-based cemented carbide obtained in step (1.7), calculate the effective grain size. in, And D iIt is the diameter of the equal-area circle of the i-th effective statistical grain obtained from EBSD analysis. In this embodiment, the number of complete grains is 1426.

[0088] (2) Since D = 2.1μm ∈ [1.0μm, 3.0μm), and D mgs =2.238μm∈[0.97×D,+∞)=[2.037μm,+∞), then the tungsten carbide-based cemented carbide meets the high-quality grain size standard.

[0089] Example 3

[0090] This embodiment provides a method for evaluating the grain size of tungsten carbide-based cemented carbide and a tungsten carbide-based cemented carbide. The evaluation method includes the following steps:

[0091] (1) EBSD analysis, specifically:

[0092] (1.1) Sample preparation, including cutting, mounting and polishing in sequence; wherein, the surface size of the sample block obtained after cutting is 8mm×8mm; the polishing includes low-speed mechanical polishing and focused ion beam etching in sequence to remove surface stress of the sample and improve the flatness of the sample surface;

[0093] (1.2) The grain size was estimated by scanning electron microscopy. Specifically, the grain size was directly measured in the horizontal direction using the secondary electron observation mode, and the estimated grain size of tungsten carbide-based cemented carbide was D = 6.6 μm.

[0094] (1.3) Sample loading: Specifically, the sample is fixed on a sample stage tilted at 70° to ensure that the sample is stable and has good conductivity. Then, the sample stage is installed in the sample chamber. Select an appropriate magnification and dynamically focus on the upper, middle and lower areas of the sample field of view so that each point can be clearly displayed.

[0095] (1.4) Select the step size. Specifically, adjust the test step size to 1 / 33 of the estimated grain size D of the tungsten carbide-based cemented carbide, which is 0.2 μm.

[0096] (1.5) Select the field of view. Specifically, select two fields of view to scan the sample under test, and determine the number of samples based on the estimated grain size D of the tungsten carbide-based cemented carbide. Since D = 6.6 μm ∈ [3.0 μm, 10.0 μm), ensure that each field of view contains at least 300 complete grains, and all fields of view contain at least 600 complete grains.

[0097] (1.6) Adjust the testing conditions of the scanning electron microscope and EBSD, perform EBSD scanning, and obtain high-quality scan images. Figure 3 ;

[0098] (1.7) Data processing, including sequentially acquiring raw grain size data, removing noise, and acquiring processed grain size data;

[0099] (1.8) Based on the grain size data of the tungsten carbide-based cemented carbide obtained in step (1.7), calculate the effective grain size. in, And D i It is the diameter of the equal-area circle of the i-th effective statistical grain obtained from EBSD analysis. In this embodiment, the number of complete grains is 1082.

[0100] (2) Since D = 6.6μm ∈ [1.0μm, 3.0μm), and D mgs =6.495μm∈[0.95×D,+∞)=[6.27μm,+∞), then the tungsten carbide-based cemented carbide meets the high-quality grain size standard.

[0101] Example 4

[0102] This embodiment provides a method for evaluating the grain size of tungsten carbide-based cemented carbide and a tungsten carbide-based cemented carbide. The evaluation method includes the following steps:

[0103] (1) EBSD analysis, specifically:

[0104] (1.1) Sample preparation, including sequential cutting, mounting, and polishing; wherein, the surface dimensions of the sample block obtained after cutting are used for testing. The polishing includes sequential low-speed mechanical polishing and focused ion beam etching to remove surface stress from the sample and improve the smoothness of the sample surface.

[0105] (1.2) The grain size was estimated by scanning electron microscopy. Specifically, the grain size was directly measured in the horizontal direction using the secondary electron observation mode. The estimated grain size of the tungsten carbide-based cemented carbide was D = 18.4 μm.

[0106] (1.3) Sample loading: Specifically, the sample is fixed on a sample stage tilted at 70° to ensure that the sample is stable and has good conductivity. Then, the sample stage is installed in the sample chamber. Select an appropriate magnification and dynamically focus on the upper, middle and lower areas of the sample field of view so that each point can be clearly displayed.

[0107] (1.4) Select the step size. Specifically, adjust the test step size to 1 / 37 of the estimated grain size D of the tungsten carbide-based cemented carbide, which is 0.5 μm.

[0108] (1.5) Select the field of view. Specifically, select two fields of view to scan the sample under test, and determine the number of samples based on the estimated grain size D of the tungsten carbide-based cemented carbide. Since D = 18.4 μm ∈ [10.0 μm, 25.0 μm), ensure that each field of view contains at least 250 complete grains, and all fields of view contain at least 500 complete grains.

[0109] (1.6) Adjust the testing conditions of the scanning electron microscope and EBSD, perform EBSD scanning, and obtain high-quality scan images. Figure 4 ;

[0110] (1.7) Data processing, including sequentially acquiring raw grain size data, removing noise, and acquiring processed grain size data;

[0111] (1.8) Based on the grain size data of the tungsten carbide-based cemented carbide obtained in step (1.7), calculate the effective grain size. in, And D i It is the diameter of the equal-area circle of the i-th effective statistical grain obtained from EBSD analysis. In this embodiment, the number of complete grains is 752.

[0112] (2) Since D = 18.4 μm ∈ [10.0 μm, 25.0 μm), and D mgs =17.982μm∈[0.93×D,+∞)=[17.112μm,+∞), then the tungsten carbide-based cemented carbide meets the high-quality grain size standard.

[0113] Comparative Example 1

[0114] This comparative example provides a tungsten carbide-based cemented carbide, which, according to EBSD analysis as described in Example 1, has a D = 0.9 μm and... Therefore, the tungsten carbide-based cemented carbide does not meet the high-quality grain size standard.

[0115] Comparative Example 2

[0116] This comparative example provides a tungsten carbide-based cemented carbide, which, according to EBSD analysis as described in Example 2, has a diameter (D) of 2.1 μm and... Therefore, the tungsten carbide-based cemented carbide does not meet the high-quality grain size standard.

[0117] Comparative Example 3

[0118] This comparative example provides a tungsten carbide-based cemented carbide, which, according to EBSD analysis as described in Example 3, has a diameter (D) of 6.6 μm and... Therefore, the tungsten carbide-based cemented carbide does not meet the high-quality grain size standard.

[0119] Comparative Example 4

[0120] This comparative example provides a tungsten carbide-based cemented carbide, which, according to EBSD analysis as described in Example 4, has a diameter (D) of 18.4 μm and... Therefore, the tungsten carbide-based cemented carbide does not meet the high-quality grain size standard.

[0121] The performance parameters of the tungsten carbide-based cemented carbide described in Examples 1-4 and Comparative Examples 1-4 are shown in Table 1 below.

[0122] Table 1

[0123]

[0124]

[0125] Table 1 shows that, under the premise that the density of the tungsten carbide-based cemented carbides described in Examples 1-4 is comparable to that of the tungsten carbide-based cemented carbides described in Comparative Examples 1-4, the former has a higher hardness (HRA) and bending strength (TRS) than the latter, and the increase in bending strength (TRS) is in the range of 7-11%. This indicates that the tungsten carbide-based cemented carbides with a higher effective grain size value and within the standard range of excellent grain size have higher hardness, toughness, and overall performance.

[0126] Therefore, it can be seen that the present invention proposes an effective grain size D for characterizing tungsten carbide-based cemented carbide. mgs Compared to the average grain size of metals in the general sense, the main difference of this invention is that it uses the grain size data obtained by EBSD analysis for weighted averaging and performs coefficient correction according to tungsten carbide-based cemented carbide samples with different estimated grain sizes, thereby realizing accurate characterization and evaluation of the differences in microstructure and properties of tungsten carbide-based cemented carbide from different sources.

[0127] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for evaluating the grain size of tungsten carbide-based cemented carbide, characterized in that, The evaluation method includes the following steps: (1) Grain size data of tungsten carbide-based cemented carbide were obtained based on EBSD analysis, and the effective grain size was calculated. ; (2) Combining the estimated grain size D of tungsten carbide-based cemented carbide with the effective grain size obtained in step (1) The grain size of the tungsten carbide-based cemented carbide was evaluated. Among them, the effective grain size mentioned in step (1) In the formula, , ,and It is the diameter of the equal-area circle of the i-th effective statistical grain obtained from EBSD analysis, where n is the number of effective statistical grains and c is the correction factor. Step (1) Determine the value of the correction coefficient c based on the estimated grain size D of the tungsten carbide-based cemented carbide, specifically as follows: when At that time, the correction coefficient c = 0.88; when At that time, the correction coefficient c = 0.92; when At that time, the correction coefficient c = 0.95; when At that time, the correction coefficient c = 0.

98.

2. The evaluation method according to claim 1, characterized in that, Step (1) of the EBSD analysis includes sample preparation, estimated grain size, sample loading, step size selection, field of view selection, EBSD scanning and data processing performed sequentially.

3. The evaluation method according to claim 2, characterized in that, The sample preparation includes cutting, mounting, and polishing in sequence.

4. The evaluation method according to claim 3, characterized in that, The surface dimensions of the sample block obtained after cutting for testing are (5-8)mm×(5-8)mm or φ(5-8)mm.

5. The evaluation method according to claim 3, characterized in that, The polishing includes mechanical polishing and / or focused ion beam etching.

6. The evaluation method according to claim 2, characterized in that, The estimated grain size was determined using scanning electron microscopy and / or EBSD pre-scanning.

7. The evaluation method according to claim 6, characterized in that, The scanning electron microscopy method specifically involves directly measuring the grain size in the horizontal direction using a secondary electron observation mode to obtain the estimated grain size D of the tungsten carbide-based cemented carbide.

8. The evaluation method according to claim 6, characterized in that, The EBSD pre-scanning method specifically involves using EBSD attachments to scan several lines to estimate the grain size, thereby obtaining the estimated grain size D of the tungsten carbide-based cemented carbide.

9. The evaluation method according to claim 2, characterized in that, The step size selection is specifically to adjust the test step size to 1 / 50-1 / 10 of the estimated grain size D of the tungsten carbide-based cemented carbide.

10. The evaluation method according to claim 2, characterized in that, The selection of the field of view specifically involves selecting at least two fields of view to scan the sample under test, and determining the number of samples based on the estimated grain size D of the tungsten carbide-based cemented carbide.

11. The evaluation method according to claim 10, characterized in that, The criteria for determining the sample size are as follows: when At the same time, ensure that each field of view contains at least 750 complete grains, and that all fields of view contain at least 1500 complete grains; when At the same time, ensure that each field of view contains at least 500 complete grains, and that all fields of view contain at least 1000 complete grains; when At the same time, ensure that each field of view contains at least 300 complete grains, and that all fields of view contain at least 600 complete grains; when At the same time, ensure that each field of view contains at least 250 complete grains, and that all fields of view contain at least 500 complete grains.

12. The evaluation method according to claim 2, characterized in that, The data processing includes sequentially acquiring the original grain size data, removing noise, and acquiring the processed grain size data.

13. The evaluation method according to claim 1, characterized in that, The grain size evaluation standard for the tungsten carbide-based cemented carbide in step (2) is as follows: when At that time, if If the grain size is within acceptable limits, then the tungsten carbide-based cemented carbide meets the high-quality grain size standard; otherwise, it does not. when At that time, if If the grain size is within acceptable limits, then the tungsten carbide-based cemented carbide meets the high-quality grain size standard; otherwise, it does not. when At that time, if If the grain size is within acceptable limits, then the tungsten carbide-based cemented carbide meets the high-quality grain size standard; otherwise, it does not. when At that time, if If the grain size is good, the tungsten carbide-based cemented carbide meets the high-quality grain size standard; otherwise, it does not.

14. The evaluation method according to any one of claims 1-13, characterized in that, The evaluation method includes the following steps: (1) Grain size data of tungsten carbide-based cemented carbide were obtained based on EBSD analysis, and the effective grain size was calculated. In the formula, , ,and It is the diameter of the equal-area circle of the i-th effective statistical grain obtained from EBSD analysis, where n is the number of effective statistical grains and c is the correction factor. The value of the correction factor c is determined based on the estimated grain size D of the tungsten carbide-based cemented carbide, specifically as follows: when At that time, the correction coefficient c = 0.88; when At that time, the correction coefficient c = 0.92; when At that time, the correction coefficient c = 0.95; when At that time, the correction factor c = 0.98; The EBSD analysis includes sequential steps such as sample preparation, grain size estimation, sample loading, step size selection, field of view selection, EBSD scanning, and data processing. (2) Combining the estimated grain size D of tungsten carbide-based cemented carbide with the effective grain size obtained in step (1) The grain size of the tungsten carbide-based cemented carbide is evaluated, and the evaluation criteria are as follows: when At that time, if If the grain size is within acceptable limits, then the tungsten carbide-based cemented carbide meets the high-quality grain size standard; otherwise, it does not. when At that time, if If the grain size is within acceptable limits, then the tungsten carbide-based cemented carbide meets the high-quality grain size standard; otherwise, it does not. when At that time, if If the grain size is within acceptable limits, then the tungsten carbide-based cemented carbide meets the high-quality grain size standard; otherwise, it does not. when At that time, if If the grain size is good, the tungsten carbide-based cemented carbide meets the high-quality grain size standard; otherwise, it does not.

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