Method for measuring grain boundary length of arbitrary orientation difference

Abstract

The invention provides a method for measuring the grain boundary length of any orientation difference, and relates to the field of material analysis and test.The method comprises the following steps that S1, a sample to be analyzed is pretreated, and a preliminary analysis sample is obtained; s2, performing magnification observation on the preliminary analysis sample under a scanning electron microscope to obtain a grain orientation IPF diagram and a grain distribution diagram of the preliminary analysis sample; s3, processing the grain orientation IPF graph and the grain distribution graph to obtain grain boundary pixels and X with poor orientation; and S4, obtaining a grain boundary length value of a certain orientation difference unit area according to the grain boundary pixel and X of the orientation difference and the test step length. The measurement method provided by the invention not only can obtain the probability information of the large and small angle orientation differences, but also can accurately calculate the grain boundary lengths of different orientation differences, and the measurement method is more scientific and accurate than a common measurement method which can only provide the relative probability, and can be applied to detection and analysis practice.

Description

Technical Field

[0001] The invention relates to the field of material analysis and testing, and in particular to a method for measuring the length of an arbitrary orientation difference grain boundary. Background Art

[0002] The precipitation and distribution of cementite in hypereutectoid steel has a great influence on the drawing properties of steel. When analyzing the precipitation law of cementite, it is found that the amount of cementite precipitated along the grain boundary is related to the grain boundary angle and the length of the large-angle grain boundary.

[0003] Therefore, we need to determine the absolute length of the large-angle grain boundary per unit area in the study of cementite precipitation mode. The existing experimental conditions can only analyze the large-angle grain boundary ratio, but the actual grain boundary length is also related to factors such as grain size, so there is an urgent need for a method to analyze the actual length of the grain boundary, which can be used to study the law of cementite precipitation. Summary of the invention

[0004] According to the above technical problem that the prior art lacks the actual length of the grain boundary, a method for measuring the length of the grain boundary with arbitrary orientation difference is provided.

[0005] The technical means adopted by the present invention are as follows:

[0006] A method for measuring the length of an arbitrary misorientation grain boundary comprises the following steps:

[0007] S1. Pre-treating the sample to be analyzed to obtain a preliminary analysis sample;

[0008] S2. Observe the preliminary analysis sample under a scanning electron microscope at a magnification to obtain an IPF map of the grain orientation and a grain distribution map of the preliminary analysis sample;

[0009] S3, processing the IPF map of grain orientation and the grain distribution map to obtain the grain boundary pixels and X of the orientation difference;

[0010] S4. According to the grain boundary pixels of the orientation difference and X and the test step length, the grain boundary length value per unit area of ​​a certain orientation difference is obtained.

[0011] Furthermore, the pretreatment process in S1 includes: grinding the analysis surface of the sample to be analyzed, polishing the analysis surface by mechanical method, and then removing the deformation layer formed on the sample surface during grinding and mechanical polishing by vibration polishing or electrolytic polishing to obtain a preliminary analysis sample.

[0012] Furthermore, in S1, the length of the analyzed sample is 6 mm, the width is 4 mm, and the thickness is 2 mm.

[0013] Furthermore, in S1, the analysis surface of the sample to be analyzed is ground using coarse and fine sandpaper.

[0014] Furthermore, S2 specifically includes: observing the area to be measured of the preliminary analysis sample under a scanning electron microscope at a magnification, and simultaneously using an electron backscatter diffractometer to calibrate the crystal orientation information to obtain an IPF map of grain orientation and a grain distribution map.

[0015] Furthermore, the working parameters of the scanning electron microscope in S2 are selected as an acceleration voltage of 15-25 kV, a working distance of 15-25 mm, and an aperture of 60-120 μm.

[0016] Furthermore, in S2, the step size of the electron backscatter diffractometer is set to 1 / 20-1 / 10 of the average grain size.

[0017] Furthermore, the fluorescent screen of the electron backscatter diffractometer in S2 captured the Kikuchi pattern.

[0018] Furthermore, in S4, X is multiplied by the step length and then divided by the analysis area to calculate the grain boundary length value per unit area of ​​the orientation difference.

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

[0020] The method provided by the present invention not only obtains the probability information of the large and small angle orientation differences, but also can accurately calculate the grain boundary lengths of different grain sizes. This measurement method is more scientific and accurate than the commonly used measurement method that can only provide relative probabilities, and can be applied to detection and analysis practices. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 The figure is a flow chart of the method of the present invention.

[0023] Figure 2 It is a schematic diagram of the inverse pole figure + cementite + grain boundary with an orientation difference greater than 15 degrees in the present invention.

[0024] Figure 3 Without using the present invention, only orientation distribution diagrams with orientation differences greater than 15 degrees can be obtained. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the 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.

[0027] like Figure 1-3 As shown, the present invention provides a method for measuring the length of an arbitrary orientation difference grain boundary, comprising the following steps:

[0028] Select the sample to be analyzed with a length of 6 mm, a width of 4 mm, and a thickness of 2 mm. Grind the analysis surface of the sample with coarse and fine sandpaper, polish the analysis surface mechanically, and then remove the deformation layer formed on the sample surface during the grinding and mechanical polishing process by vibration polishing or electrolytic polishing to obtain a preliminary analysis sample; ensure that the sample resolution rate is above 95%.

[0029] The area to be measured of the preliminary analysis sample was observed under a scanning electron microscope at a magnification, and the electron backscatter diffractometer EBSD was used to calibrate the crystal orientation information to obtain the IPF map of grain orientation and the grain distribution map;

[0030] The working parameters of the scanning electron microscope can be selected as an acceleration voltage of 15-25 kilovolts, a working distance of 15-25 mm, an aperture of 60-120 microns, and an appropriate magnification factor can be selected according to the characteristics of the sample.

[0031] The EBSD step size was set to 1 / 20-1 / 10 of the average grain size. The Kikuchi pattern was captured on the fluorescent screen, and the IPF map of grain orientation and grain distribution map were obtained after analytical calibration.

[0032] The IPF map of grain orientation and grain distribution map are processed by Channel5 software to obtain the grain boundary pixels and X of the orientation difference; X is multiplied by the step size and then divided by the analysis area to obtain the grain boundary length value per unit area of ​​the orientation difference.

[0033] Example 1

[0034] like Figure 1-3 As shown, taking the measurement of hypereutectoid steel grain boundary length as an example, a method for measuring the length of arbitrary orientation difference grain boundary is provided, which includes the following steps:

[0035] S1. The analysis sample was selected with a length of 6 mm, a width of 4 mm, and a thickness of 2 mm. The analysis surface was ground with coarse and fine sandpaper. The sample surface was mechanically polished on a metallographic polishing machine. The deformation layer formed on the sample surface during the grinding and mechanical polishing process was removed by vibration polishing. The sample resolution rate was 97.6%.

[0036] S2. Observe under a scanning electron microscope and select the area to be measured. The working parameters can be selected as an acceleration voltage of 15 kV, a working distance of 18 mm, an aperture of 120 μm, and a suitable magnification of 1000 times according to the characteristics of the sample.

[0037] S3. Use electron backscatter diffractometer EBSD to calibrate crystal orientation information. The step size is set to 1 / 10 of the average grain size. The Kikuchi pattern is captured on the fluorescent screen, and the IPF map of grain orientation and grain distribution map are obtained after analytical calibration.

[0038] S4. In the HKL Channel5 post-processing software, the sum of the grain boundary pixels greater than 15 degrees is 7726, multiplied by the step size of 0.25 microns, and then divided by the analysis area of ​​4565 square microns, the grain boundary length per square millimeter when the orientation difference is greater than 15 degrees is 423 mm.

[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for measuring the length of an arbitrary misorientation grain boundary, characterized in that: The steps include: S1. Pre-treating the sample to be analyzed to obtain a preliminary analysis sample; S2. Observe the preliminary analysis sample under a scanning electron microscope at a magnification to obtain an IPF map of the grain orientation and a grain distribution map of the preliminary analysis sample; S3, processing the IPF map of grain orientation and the grain distribution map to obtain the grain boundary pixels and X of the orientation difference; S4. According to the grain boundary pixels of the orientation difference and X and the test step length, the grain boundary length value per unit area of ​​a certain orientation difference is obtained.

2. The method for measuring the length of any orientation difference grain boundary according to claim 1, characterized in that: The pretreatment process in S1 includes: grinding the analysis surface of the sample to be analyzed, polishing the analysis surface by mechanical method, and then removing the deformation layer formed on the sample surface during grinding and mechanical polishing by vibration polishing or electrolytic polishing to obtain a preliminary analysis sample.

3. The method for measuring the length of any orientation difference grain boundary according to claim 1, characterized in that: In S1, the length of the analyzed sample is 6 mm, the width is 4 mm, and the thickness is 2 mm.

4. The method for measuring the length of any orientation difference grain boundary according to claim 2, characterized in that: In S1, the analysis surface of the sample to be analyzed is ground using coarse and fine sandpaper.

5. The method for measuring the length of any orientation difference grain boundary according to claim 1, characterized in that: The S2 specifically includes: observing the area to be measured of the preliminary analysis sample under a scanning electron microscope at a magnification, and simultaneously using an electron backscatter diffractometer to calibrate the crystal orientation information to obtain an IPF map of grain orientation and a grain distribution map.

6. The method for measuring the length of any orientation difference grain boundary according to claim 5, characterized in that: The working parameters of the scanning electron microscope in S2 are selected as accelerating voltage 15-25 kV, working distance 15-25 mm, and aperture 60-120 μm.

7. The method for measuring the length of any orientation difference grain boundary according to claim 6, characterized in that: In S2, the step size of the electron backscatter diffractometer was set to 1 / 20-1 / 10 of the average grain size.

8. The method for measuring the length of any orientation difference grain boundary according to claim 7, characterized in that: The fluorescence screen capture of the Kikuchi pattern from the electron backscatter diffractometer in S2.

9. The method for measuring the length of any orientation difference grain boundary according to claim 1, characterized in that: In S4, X is multiplied by the step length and then divided by the analysis area to calculate the grain boundary length per unit area of ​​the orientation difference.

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