JP6805001B2 - A device for estimating the reference orientation and estimating the cause of destruction of metal materials or evaluating the damage rate - Google Patents

Description

The present invention relates to a method of estimating a reference orientation from a damaged or broken metallic material.

In recent years, a method has been devised in which the cause of fracture of a metal material is estimated and the damage rate is evaluated by using crystal orientation analysis by electron backscatter diffraction (EBSD) (Patent Document 1, Patent). Reference 2). Specifically, the crystal orientation of the metal material is measured by the EBSD method. Then, the crystal orientation of each measured measurement point is compared with the reference orientation to obtain the crystal orientation difference, and the damage rate and the cause of fracture of the metal material are evaluated based on the obtained crystal orientation difference.

Japanese Unexamined Patent Publication No. 2012-2614

JP 2013-64626

In the above, the crystal orientation difference is obtained by comparing the crystal orientation of each measurement point of the metal material with the reference orientation (ideally, the crystal orientation before damage). Therefore, in order to accurately obtain the crystal orientation difference, it is necessary to accurately obtain the reference orientation. Such a reference orientation can be easily identified by measuring the crystal orientation by the EBSD method before damage or fracture, but if the crystal orientation is not measured before damage or fracture, the damage occurs. There is no choice but to specify the reference direction from the product or the destroyed product.
However, since a part of the crystal orientation of the damaged product or the broken product is rotated from the reference orientation, there is a problem that it is difficult to accurately specify the reference orientation.

The present invention has been completed based on the above circumstances, and an object of the present invention is to improve the estimation accuracy of the reference orientation of a metal material.

The present invention is a method for estimating a reference orientation from a damaged or destroyed metal material, in which the metal material is irradiated with an electron beam and the crystal orientation at each measurement point is measured by an electron backscattering diffraction image method. The measurement step and the calculation step of calculating the maximum density point of the crystal orientation by excluding a part of the measurement points whose crystal orientation has rotated are included, and the maximum density point calculated in the calculation step is included. The crystal orientation is defined as the reference orientation of the metal material.

The present invention is an apparatus for estimating the cause of destruction of a metal material or evaluating the damage rate, irradiating the damaged or destroyed metal material with an electron beam, and measuring the crystal orientation of each measurement point by the electron rear scattering diffraction image method. The data processing unit includes a measuring unit and a data processing unit, and the data processing unit calculates the maximum density point of the crystal orientation by excluding a part of the measurement points whose crystal orientation is rotated. Based on the calculation process, the orientation difference calculation process for calculating the crystal orientation difference of each measurement point with respect to the reference orientation with the crystal orientation of the highest density point as the reference orientation, and the crystal orientation difference of each measurement point, the metal The process of estimating the cause of material destruction or evaluating the damage rate is performed.

In the present invention, the "maximum density point" means a measurement point having the highest density in the distribution of crystal orientations. For example, a reverse pole point diagram showing the crystal orientation of a metal material in FIG. When represented by, the "maximum density point" is the center of gravity point of a point group (excluding some points whose crystal orientation is rotated) which is a collection of measurement points. Further, "the crystal orientation has rotated" means that the crystal orientation has changed from the reference orientation before the damage due to the metal material being damaged or the like.

According to the present invention, the reference orientation of a metal material can be estimated with high accuracy even after damage or destruction. In addition, it is possible to estimate the damage rate and the cause of destruction of the metal material with high accuracy.

Block diagram of the evaluation device according to the first embodiment Flow chart showing how to evaluate the damage rate of metal materials Diagram showing measurement point and crystal orientation difference Master curve graph Flow chart showing the calculation method of the highest density point Reverse pole figure showing the distribution of crystal orientation Enlarged view of a part of FIG. Diagram showing the coordinate system of crystal orientation Reverse pole figure showing the distribution of crystal orientation The figure which shows the outline of the chemical composition of a metal material and the tensile property Diagram showing the shape of the test piece Diagram showing the relationship between the ratio of measurement points and the directional difference The flowchart which shows the method of estimating the cause of destruction in Embodiment 2. Front view of the sample used for measurement Graph showing the orientation difference curve of each fractured material The figure which shows the distribution of the crystal orientation difference H of a broken product (when the reference orientation is calculated by the method of this invention). A diagram showing the distribution of the crystal orientation difference H of the fractured product (when the reference orientation is calculated by the arithmetic mean).

<Embodiment 1>
Hereinafter, the evaluation device for evaluating the damage rate of the metal material will be described in detail with reference to FIGS. 1 to 12.

1. 1. Configuration of Evaluation Device 1 FIG. 1 shows a block diagram of an evaluation device for estimating a damage rate Z of a metal material. The evaluation device 1 includes a measurement unit 5 and a data processing device 20. The measuring unit 5 includes a scanning electron microscope (SEM) 10, an EBSD (Electron Back Scatter Diffraction) detector 14, and three control units 17, 18, and 19.

The scanning electron microscope 10 includes a sample chamber 12 in which a sample stage 11 capable of fixing a sample is arranged, and an electron gun 13 (corresponding to the electron source of the present invention) capable of irradiating the sample with an electron beam. It has a general configuration. Further, the EBSD detector 14 generally includes a screen 15 for projecting an electron backscatter diffraction image generated by irradiating a sample with an electron beam, and a high-sensitivity camera 16 for capturing the projected electron backscatter diffraction image. It has a typical structure.

The three control units 17, 18, and 19 are an electron beam control unit 17 that controls electron beam irradiation by an electron gun, a stage control unit 18 that controls the position and angle of a sample stage 11, and an image pickup by a high-sensitivity camera 16. It is composed of a camera control unit 19 for controlling. These control units 17, 18 and 19 are connected to the data processing device 20 and control the sample stage 11, the electron gun 13 and the high-sensitivity camera 16 according to a command from the CPU 21.

The data processing device 20 is composed of a computer, and includes a CPU 21 that executes a measurement / analysis program that controls electron beam irradiation, acquires a diffraction image, performs orientation analysis, and the like, and a hard disk 22. A data storage area 23 and a program storage area 24 are secured on the hard disk 22, respectively. The data storage area 23 stores data of the master curve La, which will be described later. Further, in the program storage area 24, a program for analyzing the crystal orientation and evaluating the damage rate Z of the metal material and the like are stored.

2. 2. Method for Estimating Damage Rate Z of Metal Material Next, using the evaluation device 1 configured as described above, for example, the damage rate of the metal material (nickel-based superalloy as an example) used for the moving blade of a gas turbine. A method of estimating Z will be described with reference to the flowchart shown in FIG.

The damage rate Z is the degree of damage to the metal material, and is defined by the following equation (1) in the present specification.

Z = T / Tf ..... (1) Equation "T" is the elapsed time from the initial stage. "Tf" is the elapsed time from the initial stage to the breakage.

First, in S10, the measurer prepares the sample. That is, a part of the damaged metal material to be evaluated (for example, a nickel-based alloy) is sampled. Then, it is prepared so that the surface state is suitable for analysis by the electron backscatter diffraction method. Here, by using general methods such as mechanical polishing and electrolytic polishing, a sample for evaluation by the electron backscattering method can be prepared. After that, the measurer sets the prepared sample on the sample stage 11.

Subsequently, in S20, the crystal orientation of each measurement point P is measured by the electron backscatter diffraction method for the sample to be evaluated set on the sample stage 11 of the scanning electron microscope 10.

Specifically, the surface of the sample is scanned with an electron beam and irradiated at predetermined pitch intervals. The irradiation of the electron beam produces an electron backscatter diffraction image, which is projected onto the screen 15. The projected electron backscatter diffraction image is taken by the high-sensitivity camera 16 and output to the data processing device 20 as image data.

Subsequently, in S30, the CPU 21 of the data processing device 20 analyzes the obtained electron backscatter diffraction image to obtain the crystal orientation at each measurement point P. This process can be performed by a known method using, for example, a measurement / analysis program such as "OIM" manufactured by TSL Solutions. The obtained crystal orientation is recorded in the data storage area 23 of the hard disk 22 together with the coordinate data of each measurement point P. In addition, S20 and S30 correspond to the "measurement step" of the present invention.

Subsequently, in S40, the CPU 21 of the data processing device 20 performs a process of calculating a reference orientation (crystal orientation before damage) from the crystal orientation data of each measurement point P obtained in S30. The method of calculating the reference direction will be described in detail later. Further, S40 corresponds to the "calculation step" and the "maximum density point calculation process" of the present invention.

Subsequently, in S50, the CPU 21 of the data processing device 20 determines the crystal orientation difference H at each measurement point P based on the crystal orientation of each measurement point P obtained in S30 and the reference orientation calculated in S40. Specifically, the difference between the crystal orientation of the target measurement point P and the reference orientation is calculated as the crystal orientation difference (GROD: Grain Reference Orientation Deviation) at the measurement point P. Further, FIG. 3 shows the crystal orientation difference H between the highest density point (point of the reference orientation) Po in the crystal grain and each measurement point P. Note that S50 corresponds to the "direction difference calculation process" of the present invention.

Subsequently, in S60, the CPU 21 of the data processing device 20 calculates the average value Hav of the crystal orientation difference H from the crystal orientation difference H of each measurement point P calculated in S50.

Then, in S70, the CPU 21 of the data processing device 20 correlates the average value Hav of the crystal orientation difference H calculated in S60 with the master carp La (damage rate Z and the average value Hav of the crystal orientation difference H) shown in FIG. The damage rate Z of the sample can be evaluated by referring to the curve (curve showing the property). For example, when the average value Hav of the crystal orientation difference H is “H1”, the damage rate Z of the sample is “Z1”.

The master curve La shown in FIG. 4 is subjected to a damage test (for example, creep damage test) in advance using the same metal material as the sample (nickel-based superalloy in the above example), and the same method as described above is used for each damage rate Z. It was obtained by obtaining the crystal orientation difference H at each measurement point P and its average value Hav in (S10 to S60). The creep damage test is a test in which a sample is damaged by continuously applying a constant stress to the sample under a high temperature state.

3. 3. Reference Orientation Estimate Method In this embodiment, as described above, the damage rate Z of the metal material is evaluated based on the “crystal orientation difference H”. In order to improve the evaluation accuracy of the damage rate Z, it is necessary to accurately calculate the crystal orientation difference H, and it is desirable to accurately specify the reference orientation of the crystal.

The reference orientation is ideally the crystal orientation before damage to the metallic material. Therefore, the reference orientation can be easily specified by measuring the crystal orientation by the EBSD method before the metal material is damaged.

However, if the crystal orientation is not measured before the damage, the reference orientation must be specified from the damaged sample. On the other hand, in the damaged sample, the crystal orientation of some crystals is rotated from the reference orientation.

Therefore, for example, when trying to obtain the reference orientation from the arithmetic mean of the crystal orientations of each measurement point P for a damaged sample, the rotated orientation becomes an error and it is difficult to accurately specify the reference orientation. There's a problem.

Therefore, in the present embodiment, the maximum density point of the crystal orientation is calculated by excluding a part of all the measurement points P in which the crystal orientation is rotated, and the crystal orientation of the calculated maximum density point is used as a reference for the metal material. The direction. By doing so, the reference direction can be estimated more accurately than the method using the arithmetic mean. In addition, "the crystal orientation has rotated" means that the crystal orientation has changed from the reference orientation before the damage due to the metal material being damaged or the like.

Hereinafter, the procedure for calculating the reference orientation from the damaged sample will be described with reference to FIG. Note that FIG. 5 shows the details of the “reference direction calculation process (S40)” shown in FIG.

As shown in FIG. 5, the reference direction calculation process (S40) is composed of three steps of S41, S43, and S45. Then, in S41, the CPU 21 of the data processing device 20 calculates the first center of gravity point of the crystal orientation.

Specifically, the following calculation is performed on the measurement point P irradiated with the electron beam in S20. First, one measurement point is selected from all measurement points. Then, for each of the selected measurement points P, the crystal orientation difference H with all the other measurement points P is calculated, and the total sum ΣH is obtained. The same calculation is performed by changing the selected measurement points P, and the total ΣH of the crystal orientation difference H is calculated for each measurement point. Then, the total ΣH of the crystal orientation difference H of each measurement point P is compared, and the measurement point (hereinafter, the first center of gravity point) at which the total sum ΣH of the crystal orientation difference H is minimized is calculated.

FIG. 6 is a reverse pole figure (reverse pole figure of the crystal orientation group) showing the distribution of crystal orientations of the damaged metal material. In FIG. 6, the coordinates (positions) of each measurement point P indicate the crystal orientation of each measurement point P. FIG. 7 is an enlarged view of a part of FIG. 6, and the crystal orientation difference H between the measurement points can be obtained from the distance D between the two points on FIGS. 6 and 7. Further, the total sum ΣH of the crystal orientation difference H can be obtained from the total ΣD of the distances D between the points.

Note that FIG. 8 shows an orthogonal coordinate system showing the crystal orientation of the metal material, in which the X direction is Lx, the Y direction is Ly, and the Z direction is Lz. “001” shown in FIG. 6 indicates the Lz direction (Z direction) of FIG. 8, “101” indicates the Lxz direction (XZ direction) of FIG. 8, and “111” indicates the Lxyz direction (XYZ direction) of FIG. ..

After that, in S43, the CPU 21 of the data processing device 20 excludes a predetermined ratio of measurement points having a large crystal orientation difference H with respect to the first center of gravity point from all the measurement points P. In this way, the reason for excluding some measurement points P having a large crystal orientation difference is that the measurement points having a large crystal orientation difference H can be considered to have the crystal orientation rotating due to damage, and are excluded. Because. Then, in the present embodiment, 60% of all the measurement points P are excluded, and in S43, the crystal orientation difference H is larger than the first center of gravity point (the first center of gravity point on the reverse pole diagram of FIG. 6). (Far from) 60% of measurement points are excluded.

After that, in S45, the CPU 21 of the data processing device 20 calculates the maximum density point of the crystal orientation based on the remaining 40% of the measurement points P. Specifically, for the remaining 40% of the measurement points P, the crystal orientation difference H is calculated in the same manner as in S41, and the total sum ΣH is obtained. Then, the total ΣH of the crystal orientation difference H of each measurement point is compared, and the measurement point (hereinafter, the second center of gravity point) at which the total ΣH of the crystal orientation difference H is minimized is obtained. The obtained second center of gravity point is the highest density point.

From the above, the highest density point (second center of gravity point) of the crystal orientation can be specified from all the measurement points P calculated in S30. Then, in the present embodiment, the crystal orientation of the highest density point calculated from the damaged sample is used as the reference orientation of the sample.

“●” shown in FIG. 6 is the highest density point obtained by 40% of all measurement points, and “*” is the direction of the arithmetic mean. The maximum density point obtained by 40% of all measurement points is closer to the reference direction before damage indicated by "+" in FIG. 9 than the arithmetic mean, and is the highest obtained by 40% of all measurement points. It can be understood that the density point has a smaller estimation error of the reference direction than the arithmetic mean.

4. Reference Orientation Estimation Accuracy In addition, in this embodiment, the estimation accuracy of the reference azimuth was verified using "nickel-based superalloy (the outline of the chemical composition and tensile properties are shown in FIG. 10)" as an example of the sample 100. .. Specifically, a creep damage test was performed on the flat plate-shaped test piece 100 shown in FIG.

The test conditions and sample shape are as follows.
<Test conditions>
At an ambient temperature of 880 ° C., the sample 100 was pulled in the R direction of FIG. 11 with a testing machine, and a stress of 294 MPa was continuously applied to the test piece 100.
<Sample shape>
The total length A of the test piece 100 is 68 mm, the length B of both ends 105 is 24 mm, and the length C of the central portion 110 is 20 mm. The width W1 of the test piece 100 is 8 mm, the width W2 of the central portion 110 is 4 mm, and the plate thickness is 1.5 mm.

Then, the surface of the central portion 110 of the test piece (damage rate Z = 99%) 100 damaged by the creep damage test is irradiated with an electron beam using the evaluation device 1, and the crystal orientation of each measurement point P is set to electron. It was measured by the backscatter diffraction method. Next, the first center of gravity point is obtained for all the measurement points P, and then the maximum density point is calculated by changing the ratio of the measurement points P used for the calculation, and the crystal orientation of the calculated maximum density point and before damage are obtained. The directional difference from the directional was calculated.

As the measurement point P used for calculating the maximum density point, a measurement point P having a small crystal orientation difference H with respect to the first center of gravity point is selected. For example, if the ratio of the measurement point P is "40%", Of all the measurement points P, "40%", which has a small crystal orientation difference from the first center of gravity, is the calculation target.

The pre-damage orientation is the crystal orientation of the sample before damage, and is obtained by measuring the crystal orientation of the sample before the start of the creep damage test and obtaining it from the arithmetic mean.

FIG. 12 is a graph showing the relationship between the ratio [%] of the measurement points P used for calculating the maximum density point and the orientation difference [deg] with respect to the reference orientation (pre-damage orientation) of the maximum density point, with the horizontal axis indicating the relationship. The ratio [%] of the measurement point P and the vertical axis are the azimuth difference [deg].

As shown in FIG. 12, when the ratio of the measurement points P used for calculating the maximum density point is 20% or less, the directional difference is 14 [deg] or more. When the ratio of the measurement points P is 60% or more, the directional difference is 9 to 14 [deg].

On the other hand, when the ratio of the measurement points P used for calculating the maximum density point is 30%, the orientation difference is about 1 [deg]. Further, in the case of 40%, the directional difference is about 1.6 [deg], and in the case of 50%, the directional difference is about 1.8 [deg].

In this way, when the ratio of the measurement points P used for calculating the maximum density point is 30% to 50% (70% to 50% in the exclusion ratio), the directional differences are all within 2 [deg] or less. , The result that the estimation accuracy of the reference direction was high was obtained. From the above, in this example, in S43, the measurement point P of 60%, which has a large crystal orientation difference with respect to the first center of gravity point, is excluded.

The evaluation result of FIG. 12 is for a test piece having a damage rate Z = 99%, but even if the damage rate Z is different, the tendency of the change in crystal orientation due to damage does not change. Therefore, even if the damage rates Z are different, by setting the ratio of the measurement points P used for calculating the maximum density point to 30% to 50%, the directional difference is generally within 2 [deg], and the estimation accuracy of the reference directional is set. Can be expected to increase. Further, in the evaluation result of FIG. 12, when the ratio of the measurement points P used for calculating the maximum density point is 30% or less, the estimation accuracy of the reference direction deteriorates, and at least the measurement points P used for the calculation are 30. If% is left, the measurement accuracy of the reference direction is better. This is considered to be due to the following reasons. The initial reference orientation (first center of gravity of the crystal orientation) when determining the object to be excluded is a tentative reference, and itself contains an error. Therefore, if the ratio of exclusion is too large (more than 70% in the above example), the influence of the error becomes large, and the point of the true damage forward direction may be excluded at the same time.

5. Explanation of Effect The evaluation device 1 of the first embodiment can estimate the reference orientation of the metal material with high accuracy even after the damage. Therefore, even if the crystal orientation is not measured before the damage, the damage rate Z of the metal material can be evaluated with high accuracy. From the above, it is possible to optimize the replacement timing of the moving blades and the like of the gas turbine.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIGS. 13 to 17.
In the first embodiment, an example in which the damage rate Z of the metal material is evaluated from the crystal orientation difference H of each measurement point P is shown, but in the second embodiment, the cause of destruction of the metal material is shown from the crystal orientation difference H of each measurement point P. To estimate. The configuration of the device for estimating the cause of destruction of the metal material is the same as that of the evaluation device 1 of the first embodiment, and includes a measuring unit 5 and a data processing device 20.

Hereinafter, a method of estimating the cause of destruction of the metal material will be described with reference to the flowchart shown in FIG. Note that S10 to S50 are substantially the same processes as in the first embodiment, and the processes of S160 to S180 are the main differences from the first embodiment.

First, in S10, the measurer prepares the sample. In the present embodiment, the measurement target is a broken metal material. The measurer cuts out the sample 200 from the broken metal material to be measured so as to include the fracture surface F (see FIG. 14). Then, the cut-out sample 200 is prepared so as to have a surface state suitable for analysis by the electron backscatter diffraction method by setting the surface perpendicular to the fracture surface F as the measurement surface S and polishing the measurement surface S or the like. .. After that, the measurer sets the prepared sample 200 on the sample stage 11.

Subsequently, in S20, the crystal orientation of each measurement point P on the measurement surface S is measured by the electron backscatter diffraction method for the sample 200 to be evaluated set on the sample stage 11 of the scanning electron microscope 10.

Specifically, the electron beam is scanned on the measurement surface S and irradiated at predetermined pitch intervals. The irradiation of the electron beam produces an electron backscatter diffraction image, which is projected onto the screen 15. The projected electron backscatter diffraction image is taken by the high-sensitivity camera 16 and output to the data processing device 20 as image data.

Subsequently, in S30, the CPU 21 of the data processing device 20 analyzes the obtained electron backscatter diffraction image to obtain the crystal orientation at each measurement point P. The obtained crystal orientation is recorded in the data storage area 23 of the hard disk 22 together with the coordinate data of each measurement point P.

Subsequently, in S40, the CPU 21 of the data processing device 20 performs a process of calculating a reference orientation from the crystal orientation data of each measurement point P obtained in S30. The reference direction is calculated as described in the first embodiment, and is calculated by the processes S41 to S45 shown in FIG.

Subsequently, in S50, the CPU 21 of the data processing device 20 determines the crystal orientation difference H at each measurement point P based on the crystal orientation of each measurement point P obtained in S30 and the reference orientation calculated in S40. Specifically, the difference between the crystal orientation of the target measurement point P and the reference orientation is calculated as the crystal orientation difference (GROD: Grain Reference Orientation Deviation) at the measurement point P.

Subsequently, in S160, the CPU 21 of the data processing device 20 divides the measurement surface S into a plurality of divisions E1, E2, ... En at predetermined intervals (for example, every 1 mm) in the depth direction from the fracture surface F. .. Then, for each category E, the average value of the crystal orientation difference H of the measurement points P belonging to the category E is obtained.

Subsequently, in S170, the CPU 21 of the data processing device 20 has the average value of the directional differences in each category E obtained in step S160 on the coordinates with the depth from the fracture surface as the horizontal axis and the directional difference as the vertical axis. Plot the data. Then, by approximating the obtained graph, an directional difference curve showing the relationship between the depth from the fracture surface and the directional difference is obtained. The approximation can be performed by a known method such as the least squares method.

Then, in S180, the CPU 21 of the data processing device 20 obtains the pattern of the directional difference curve obtained in S170 in the same manner as above using a standard sample whose cause of destruction is known in advance. The cause of destruction of the sample 200 is estimated by comparing with FIG. 15). Since the pattern of the orientation difference curve differs depending on the cause of destruction of the sample, the cause of destruction can be estimated by the above method.

In the apparatus for estimating the cause of destruction of the metal material of the second embodiment, it is possible to estimate with high accuracy the reference orientation of the metal material even after the destruction. Therefore, even if the crystal orientation is not measured before fracture, the cause of fracture of the metal material can be evaluated with high accuracy.

FIGS. 16 and 17 show the distribution of crystal orientation differences for the impact breaking material (nickel-based superalloy). FIG. 16 shows a case where the reference orientation is estimated from the highest density point of the crystal orientation, and FIG. 17 shows a case where the reference orientation is estimated by the arithmetic mean of the crystal orientation.

The actual crystal orientation difference is large near the fracture surface (upper surface in FIGS. 16 and 17) and decreases as the distance from the fracture surface increases. In FIG. 17, there is a portion where the crystal orientation difference is larger in the portion far from the fracture surface than in the shallow portion (the magnitude relation of the crystal orientation difference is exchanged), and there is an estimation error of the crystal orientation difference. On the other hand, in FIG. 16, the crystal orientation difference is large in the vicinity of the fracture surface (upper surface in FIGS. 16 and 17) and small in a place far from the fracture surface. In this way, when the reference orientation is estimated from the highest density point of the crystal orientation (Fig. 16), the result is closer to the actual distribution of the crystal orientation difference, and the estimation accuracy of the reference orientation and the crystal orientation difference. Has been obtained with high results. In FIGS. 16 and 17, a portion having a small crystal orientation difference H is indicated by a light tone, and a portion having a large crystal orientation difference H is indicated by a dark tone.

<Other embodiments>
The present invention is not limited to the embodiments described in the above description and drawings, and for example, the following embodiments are also included in the technical scope of the present invention.
(1) In the first and second embodiments, "nickel-based superalloy" is exemplified as an example of the metal material. The metal material to be evaluated has a characteristic that the crystal orientation difference H is small in an undamaged state and the crystal orientation difference H increases as the damage progresses, such as "nickel-based alloy", "aluminum alloy", and "SUS". Any metal material (alloy-based metal material) can be widely applied.

(2) In the first and second embodiments, 60% of the measurement points P having a large crystal orientation difference H were excluded in S43. The ratio to be excluded is not limited to 60%. For example, as described in the first embodiment, 50% is used when evaluating the damage rate Z and estimating the cause of fracture of the nickel-based superalloy. It can be changed arbitrarily within the range of ~ 70%. When the metal materials are different, it is preferable to verify the relationship between the exclusion ratio and the estimation accuracy of the reference direction in advance to determine the exclusion ratio. Further, the intention of excluding the measurement point P having a large crystal orientation difference is to exclude the point where the crystal orientation is rotated. Therefore, in addition to the method of excluding the predetermined ratio, for example, a threshold value may be newly set to exclude a measurement point in which the crystal orientation difference H with respect to the first center of gravity point exceeds the threshold value in S43. ..

(3) In the first and second embodiments, an example in which the damage rate Z of the metal material is evaluated based on the average value Hav of the crystal orientation difference H at each measurement point P is shown. In addition to this, the damage rate Z of the metal material may be evaluated based on the total value ΣH of the crystal orientation difference H at each measurement point P. That is, any method may be used as long as the damage rate Z of the metal material is evaluated using the crystal orientation difference H of each measurement point P. The same applies to the estimation of the cause of destruction of metal materials.

1 ... Evaluation device 5 ... Measuring unit 10 ... Scanning electron microscope 11 ... Sample stage 13 ... Electron gun 14 ... EBSD detector 20 ... Data processing unit

Claims (6)

A reference orientation estimation method that estimates the reference orientation from a damaged or broken metal material.
A measurement step of irradiating the metal material with an electron beam and measuring the crystal orientation of each measurement point by an electron backscatter diffraction image method.
Includes a calculation step of calculating the maximum density point of the crystal orientation by excluding a part of the measurement points whose crystal orientation has rotated.
A method for estimating a reference orientation, in which the crystal orientation of the highest density point calculated in the calculation step is used as the reference orientation of the metal material. The reference orientation estimation method according to claim 1.
In the calculation step
The first center of gravity point that minimizes the crystal orientation difference from other measurement points measured in the measurement step is obtained, and at the same time.
Of all the measurement points measured in the measurement step, a predetermined ratio having a large crystal orientation difference with respect to the first center of gravity point is excluded, and the maximum density point at which the crystal orientation difference with the remaining other measurement points is minimized is calculated. How to estimate the reference orientation. The reference orientation estimation method according to claim 2.
The metal material is a nickel-based superalloy.
In the calculation step
Of all the measurement points measured in the measurement step, 70% to 50% of the measurement points having a large difference in crystal orientation with respect to the first center of gravity are excluded, and the remaining 30% to 50% of the measurement points are targeted for crystal orientation. A reference orientation estimation method that calculates the highest density point of the crystal orientation that minimizes the difference. A device that estimates the cause of destruction of metallic materials or evaluates the damage rate.
A measuring unit that irradiates a damaged or destroyed metal material with an electron beam and measures the crystal orientation of each measurement point by electron backscatter diffraction.
Including the data processing unit
The data processing unit
The maximum density point calculation process for calculating the maximum density point of the crystal orientation by excluding a part of the measurement points whose crystal orientation has rotated, and
Orientation difference calculation processing for calculating the crystal orientation difference of each measurement point with respect to the reference orientation with the crystal orientation of the highest density point as the reference orientation.
An apparatus that performs a process of estimating the cause of destruction of a metallic material or evaluating a damage rate based on the crystal orientation difference of each measurement point. The device according to claim 4.
The data processing unit
In the maximum density point calculation process, the first center of gravity point that minimizes the crystal orientation difference from other measurement points measured by the measurement unit is obtained, and at the same time.
Of all the measurement points measured by the measuring unit, the maximum density point at which the crystal orientation difference with the remaining other measurement points is minimized is calculated by excluding a predetermined ratio having a large crystal orientation difference with respect to the first center of gravity point. ,apparatus. The device according to claim 5.
The metal material is a nickel-based superalloy.
The data processing unit
In the maximum density point calculation process,
Of all the measurement points measured by the measuring unit, 70% to 50% of the measurement points having a large difference in crystal orientation with respect to the first center of gravity are excluded, and the remaining 30% to 50% of the measurement points are crystallized. A device that calculates the maximum density point of the crystal orientation that minimizes the orientation difference.

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