JP2002333409A - X-ray stress measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the X-ray dosage of diffracted X-rays detected by an X-ray detector, and to shorten a measuring time. SOLUTION: This X-ray stress measuring device 1 increases the X-ray dosage of the diffracted X-rays detected by the X-ray detector and shortens the measuring time, by increasing the X-ray dosage radiated to a sample from an X-ray source and increasing the X-ray dosage of the diffracted X-rays reaching an X-ray detection means. The device comprises a constitution equipped with an X-ray collimating means 3 for collimating X-rays emitted from the X-ray source 2 and irradiating the sample therewith, an X-ray detection means 4 including plural X-ray detection elements for detecting the diffracted X-rays emitted from the sample S, and an X-ray reflecting and condensing means 5 for reflecting the diffracted X-rays emitted from the sample and condensing the X-rays onto the X-ray detection means 4 on the focal position. Thus, the X-ray dosage is increased, and measured on the condensing position of the diffracted X-rays on the X-ray detection means 4, to thereby measure the stress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray stress measuring apparatus applied to nondestructive inspection of materials.

[0002]

2. Description of the Related Art When stress is applied to a material composed of fine crystals, the lattice spacing of the crystals changes. When the sample is irradiated with the collimated X-rays, the X-rays are diffracted according to the lattice spacing. This diffraction angle changes when the sample has a stress. X-ray stress measurement uses this X-ray diffraction phenomenon,
The change in the lattice spacing caused by the stress is obtained by changing the diffraction angle, and the stress applied to the sample and the residual stress are measured from the change in the diffraction angle.

[0003] Conventionally known X-ray stress measurements include observing changes in a pattern formed on an X-ray diffraction image on a phosphor plate or a film, and measuring the X-ray diffraction image on the angle of a collimator-equipped detection element. By scanning while shaking,
A device for measuring a diffraction angle is known.

FIGS. 3 and 4 are schematic diagrams for explaining an example of conventional X-ray stress measurement. The example shown in FIG. 3 is an example in which the stress is measured by observing a change in the pattern of the diffraction image formed on the film. In FIG. 3A,
The X-ray emitted from the X-ray source 12 is irradiated on the sample S after being narrowed down by the slit 13 (or pinhole).
The irradiated X-ray is diffracted by the sample crystal. By projecting this diffracted X-ray on the film 14, FIGS.
Can be observed.

When a stress is applied to the sample S, the diffraction interval changes because the lattice spacing of the sample crystal changes, and the diffraction image pattern also changes as shown in FIG. 3 (b) or 3 (c).

The example shown in FIG. 4 is an example in which the stress is measured by measuring the diffraction angle of the diffracted X-ray while changing the angle of the detection element. 4A, an X-ray emitted from an X-ray source 22 is focused on a slit 23 to irradiate the sample S, and the diffracted X-ray diffracted by the sample S is converted into an X-ray detector 24 such as a counter tube.
Is detected by the counting means 26, counted by the counting means 26, and recorded in the recording means 27. At this time, the X-ray detector 24 measures along the scanning circle by moving with a goniometer or the like.

Here, the angle (incident angle) between the sample surface normal and the diffraction surface normal is defined as ψ, the angle between the incident X-ray direction and the diffracted X-ray direction (diffraction angle) is defined as 2θ, and the incident X The ray and the diffracted X-ray are equiangular with respect to the normal to the diffraction plane. The angle 2θ at which the diffraction intensity of the diffracted X-ray peaks changes according to the direction (angle ψ) of the normal to the diffraction surface.

[0008] The diffraction angle 2θ is measured by changing the incident angle Ｘ of the X-ray.
And then sin²If プ ロ ッ ト is plotted as a variable, theoretically
2θ and sin²The relationship of ψ is a straight line, and the slope of this straight line is
It is proportional to the stress on the sample surface. X-ray stress measurement device shown in FIG.
Is the 2θ-sin²To obtain a 図 diagram (regression line)
Irradiate a point on the surface of the sample to be measured with X-rays at an angle of incidence ψ.
While scanning the position of the X-ray detector,
And the diffraction angle 2θ at this time is determined. FIG.
(B) and (c) are diffraction angles 2θ at incident angles ψ1 and ψ2. ₁, 2
θ₂(2θ₁, 2θ₂) Is shown. this
Change the operation of detecting the diffraction angle 2θ by changing the X-ray incident angle ψ.
Then, as shown in FIGS. 4D and 4E, sin
²ψ is plotted on the horizontal axis 2θ and the vertical axis is plotted.
The regression line is calculated using the least squares method.
Find the stress from the slope. FIGS. 4 (d) and (e) show the results.
Diffraction intensity curve and 2θ-sin when force is applied²ψ
FIG.

[0009]

SUMMARY OF THE INVENTION Conventionally used X
In the X-ray stress measuring device, the X-ray diffraction
Since the dose is extremely small, there is a problem that measurement takes time. The conventional X-ray stress measurement device extracts only a specific direction by cutting out a part of the X-ray generated by the X-ray source with a slit or pinhole, so the X-ray dose of the incident X-ray is limited. Become. Further, since most of the X-rays irradiated on the sample are absorbed or transmitted by the sample, the X-ray dose of the diffracted X-rays is slightly smaller than the irradiation X-ray. Therefore, the X-ray dose of the incident X-ray and the X-ray dose of the diffracted X-ray are both limited, and the X-ray dose contributing to the measurement is extremely small.

In order to measure such a small amount of X-ray by the film method, the exposure time of the film becomes long, and to measure by the diffraction angle detection method in which the detector is scanned, the detection time is short. It takes a long time to detect the detector, and the scanning time becomes long. The scanning time can be shortened by increasing the X-ray dose of the X-ray source, but this requires a large X-ray source.

A continuous X-ray source that generates continuous X-rays can generate a certain amount of X-rays, so that the problem of lengthening the measurement time can be reduced. Since a pulsed X-ray source that generates a ray generates a small amount of X-ray, prolonging the measurement time is a particularly serious problem. Further, in order to increase the X-ray dose of the pulse X-ray source, it is necessary to generate pulse X-rays many times, which causes a problem that the pulse X-ray source becomes expensive and the life of the pulse X-ray source is shortened. .

Accordingly, an object of the present invention is to solve the above-mentioned conventional problems, to increase the amount of X-ray diffracted X-rays detected by an X-ray detector, and to shorten the measurement time.

[0013]

SUMMARY OF THE INVENTION The present invention provides an X-ray detector by increasing the amount of X-rays irradiated to a sample from an X-ray source and increasing the amount of X-rays of diffracted X-rays reaching X-ray detecting means. This is to increase the X-ray dose of the diffracted X-rays detected and shorten the measurement time. The X-ray stress measuring device of the present invention comprises: an X-ray collimating means for collimating X-rays emitted from an X-ray source and irradiating the sample with a plurality of X-ray detecting elements for detecting diffracted X-rays emitted from the sample. Increasing the X-ray dose by providing a configuration including an X-ray detecting unit including the X-ray detecting unit and a X-ray reflecting and condensing unit that reflects diffracted X-rays emitted from the sample and condenses the X-ray detecting unit on the focal position. The stress is measured by measuring the diffraction X-ray on the X-ray detecting means at the focus position.

The X-ray collimating means of the present invention collimates X-rays scattered in all directions from the X-ray source, thereby utilizing only a part of the X-rays emitted from the X-ray source. As compared with the X-ray stress measurement, the X-ray dose for irradiating the sample can be increased.

The X-ray reflection / condensing means of the present invention focuses diffracted X-rays emitted from the sample on the X-ray detecting means by disposing the X-ray detecting means at the focal position. Diffraction X
By condensing the rays, it is possible to increase the X-ray dose of the diffracted X-rays to be detected, as compared with the conventional X-ray stress measurement using only a part of the diffracted X-rays.

Therefore, the X-ray stress measurement apparatus of the present invention measures the X-ray stress by increasing the X-ray dose of the X-ray irradiating the sample and increasing the X-ray dose of the diffracted X-ray detected by the X-ray detecting means. Can be increased. The measurement time can be shortened by increasing the X-ray dose that contributes to the X-ray stress measurement.

As one form of the X-ray detecting means, a plurality of X-rays
A configuration in which the detection elements are arranged in a line (array)
Can be. X-ray detectors are arranged in a line (array)
Measurement of the linear intensity distribution of diffracted X-rays
Can be measured. Peak position of diffraction X-ray intensity
It is necessary to obtain the relationship between the diffraction X-ray and the diffraction angle 2θ in advance.
Therefore, the diffraction angle 2θ is determined from the peak position of the diffraction X-ray intensity.
Can be sin ²From the slope of 2θ to ψ
Direction stress can be determined.

Further, as another form of the X-ray detecting means, it is possible to adopt a configuration in which a plurality of X-ray detecting elements are arranged in a plane. By disposing the X-ray detecting element in a plane, the in-plane intensity distribution of the diffracted X-ray can be measured by one measurement. By previously obtaining the relationship between the peak position of the diffraction X-ray intensity and the diffraction angle 2θ of the diffraction X-ray, the diffraction angle 2θ can be obtained from the peak position of the diffraction X-ray intensity, and the inclination of 2θ with respect to sin ² ψ. , The stress in any direction can be obtained.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram for explaining the outline of the X-ray stress measuring device of the present invention. The X-ray stress measurement apparatus 1 includes an X-ray source 2, an X-ray collimator 3 for aligning the traveling directions of the X-rays emitted from the X-ray source 2 in one direction, and a diffracted X-ray diffracted by the sample S. An X-ray mirror 5 that reflects light and condenses it on the X-ray detector 4, and an X-ray detector 4 including a plurality of X-ray detection elements and arranged at the focal point of the X-ray mirror 5 are provided. Further, in addition to the signal processing means 6 for performing signal processing on the detection signal detected by the X-ray detector 4 and the recording means 7 for recording the processing result, display means (not shown) can be provided.

The X-ray collimator 3 parallelly aligns X-rays emitted from the X-ray source 2 and traveling in different directions to be incident on the sample S. Conventionally, since only X-rays that have passed through a slit or a pinhole are applied, the amount of X-rays to be applied is limited, but the X-ray collimator 3 causes the X-ray source 2 to travel in different directions from the X-ray source 2. By collimating the emitted X-rays toward the sample S, the X-ray dose of the X-rays incident on the sample S at the same incident angle can be increased.

X-rays irradiated at the same incident angle are diffracted by the sample S, and diffracted X-rays are emitted. Assuming that the angle (diffraction angle) between the incident X-ray direction and the diffraction X-ray direction is 2θ and the direction of the normal to the diffraction surface is an angle ψ, the angle 2θ at which the diffraction intensity of the diffraction X-ray peaks is determined by the diffraction surface method. It changes according to the direction of the line (angle ψ).

The X-ray mirror 5 reflects the diffracted X-rays from the sample S in the direction of the X-ray detector 4 and focuses the X-rays on the X-ray detector 4 arranged at the focal point. At this time, since the position at which the diffracted X-rays converge on the X-ray detector 4 depends on the diffraction angle 2θ, the peak position of the diffracted X-ray condensed on the X-ray detector 4 is determined to obtain the diffraction angle 2θ. You can know. Further, since the amount of diffracted X-rays is increased by being focused on one point on the X-ray detector 4 by the X-ray mirror 5, the intensity of the diffracted X-rays detected on the X-ray detector 4 is To increase.

Therefore, the X-ray stress measuring apparatus 1 of the present invention
Then, the X-ray collimator 3 increases the amount of X-rays incident on the sample S, and the X-ray mirror 5
By increasing the X-ray dose of X-rays condensed on the X-ray detector 4, the X-ray dose of X-rays detected by the X-ray detector can be increased.

The X-ray detector 4 is formed by arranging a plurality of X-ray detecting elements in a linear (array) or planar shape. When arranged in a line (array), the X-ray intensity distribution along the line direction of the diffracted X-rays can be obtained from the detection intensity detected by each X-ray detection element and the position of the X-ray detection element. it can. When the X-ray detectors are arranged in a plane, the in-plane X-ray intensity distribution of the diffracted X-rays can be obtained from the detection intensity detected by each X-ray detector and the position of the X-ray detector.

In FIG. 1A, the diffracted X-ray indicated by the solid line and the broken line indicates a state in which the stress applied to the sample S has changed, and is condensed on the X-ray detector 4 by the X-ray mirror 5. In the position of the diffracted X-ray, the light-condensing position is shifted between the solid line and the broken line, and the shift in the light-condensing position allows a change in stress to be known.

The diffraction angle 2θ is measured by changing the X-ray incident angle ψ, and 2θ and s obtained by plotting sin ²変 数 as a variable
The stress on the sample surface can be determined from the slope of the in ²直線 line. In a conventional measuring device, as shown in FIG.
The intensity is measured a plurality of times by changing the angle of the detection element with a collimator for each predetermined incident angle ψ, and a diffraction intensity curve is obtained from the intensities of a plurality of diffraction X-rays.
The diffraction angle 2θ is measured by determining the peak position of the detected intensity of the line. On the other hand, in the X-ray stress measuring apparatus of the present invention, the diffraction intensity curve is obtained by one measurement at each predetermined incident angle ψ, and the detection intensity of the diffracted X-ray has a peak on the X-ray detector. The diffraction angle 2θ is measured from the indicated position.

FIG. 1B shows an example of a diffraction intensity curve. For example, when the X-ray detector at D1 on the X-ray detector detects the peak of the diffraction intensity when the incident angle is ψ1, the position of the X-ray detector on the X-ray detector obtained in advance is determined. The diffraction angle 2θ1 can be obtained from the relationship between D and the diffraction angle 2θ. Similarly, when the incident angle is ψ2, the position D on the X-ray detector for detecting the peak of the diffraction intensity
2, the diffraction angle 2θ2 can be obtained.

With respect to the obtained diffraction angle 2θ, the relationship between the incident angle ψ and the diffraction angle 2θ is plotted with sin ² （as the horizontal axis 2θ as the vertical axis, as shown in FIG. A regression line is determined using the square method, and the stress on the sample surface is determined from the slope of the regression line (the slope of the line of 2θ and sin ² ψ). Here, the stress is σ, the slope is M, and the stress constant is S
If (= − (E / (2 · (1 + ν))) · cotθ ₀ ), it is represented by σ = S · M. E is the X-ray Young's modulus, and ν is the X-ray Poisson's ratio.

FIGS. 1D and 1E show a state where a stress is applied or a state where the applied stress is changed. When the stress applied to the sample S changes, the diffraction angle 2θ of the diffracted X-ray also changes. In the X-ray stress measurement device of the present invention, the change in the diffraction angle 2θ of the diffracted X-ray is detected as a change in the position of an X-ray detection element that detects a peak on the X-ray detector. For example, when the incident angle ψ1, the diffraction angle 2θ
A peak of the diffracted X-ray intensity is detected at a detection position D′ 1 corresponding to ′ 1, and when the incident angle is ψ2, the diffraction angle 2θ′2
Is detected at the detection position D'2 corresponding to. Based on the detected peak positions D'1 and D'2, the position D of the X-ray detecting element and the diffraction angle 2.theta.
Determine the diffraction angle 2θ'1,2θ'2 from the relationship between, sin ²
The stress is determined from the slope between ψ and 2θ.

Here, the X-ray detector 4 is linear (array).
In the case where the X-ray detector 4 is formed of a plurality of X-ray detection elements, the stress in the linear direction can be obtained. In such a case, an in-plane stress distribution can be obtained.

FIG. 2 is a schematic diagram for explaining detection by the X-ray detector 4 in which a plurality of X-ray detection elements are arranged in a plane. 2A and 2B, the curves show the intensity distribution of the diffracted X-rays focused on the X-ray detector 4 formed by arranging a plurality of X-ray detection elements 8 in a plane. , Each incident angle ψ
1, ψ2 and ψ3 are schematically shown. The distribution of the stress in the plane can be known from the intensity distribution of the diffracted X-ray for each incident angle ψ, and for example, the stress in the x and y directions or any direction can be obtained. Note that FIG.
FIG. 2B shows a change in stress, which represents a different intensity distribution of the diffracted X-rays from FIG.

The signal processing means 6 performs signal processing for obtaining the intensity distribution and stress of the diffracted X-ray based on the intensity of the diffracted X-ray detected by the X-ray detector 4 and the position of the detected X-ray detecting element. The recording means 7 records the intensity distribution and stress obtained by the signal processing means 6. In addition, it is displayed on display means (not shown).

[0033]

As described above, according to the X-ray stress measuring apparatus of the present invention, the amount of X-ray diffracted X-rays detected by the X-ray detector can be increased, and the measuring time can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining an outline of an X-ray stress measuring device of the present invention.

FIG. 2 is a schematic diagram for explaining detection by an X-ray detector in which a plurality of X-ray detection elements of the present invention are arranged in a plane.

FIG. 3 is a schematic diagram for explaining an example of conventional X-ray stress measurement.

FIG. 4 is a schematic diagram for explaining an example of conventional X-ray stress measurement.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... X-ray stress measuring device, 2 ... X-ray source, 3 ... X-ray collimator, 4 ... X-ray detector, 5 ... X-ray mirror, 6 ... Signal processing means, 7 ... Recording means, 8 ... X-ray detection element , 12 ... X-ray source,
13 slit, 14 screen, 22 X-ray source, 2
3 slit, 24 X-ray detector, 26 counting means, 2
7: recording means, S: sample.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Takashi Yagi 932-57 Moriya Ko, Moriya-cho, Kitasoma-gun, Ibaraki F-term (reference) 2G001 AA01 BA18 DA08 DA09 FA01 GA04 KA07 SA02

Claims (3)

[Claims] 1. An X-ray collimator for collimating X-rays emitted from an X-ray source and irradiating the specimen with X-rays, and an X-ray detector comprising a plurality of X-ray detectors for detecting diffracted X-rays emitted from the specimen. And an X-ray reflection condensing means for reflecting diffracted X-rays emitted from the sample and condensing the X-rays on the X-ray detecting means at a focal position, and the condensing position of the diffracted X-rays on the X-ray detecting means An X-ray stress measurement device for measuring a stress based on a stress. 2. The X-ray detecting apparatus according to claim 1, wherein said X-ray detecting means arranges a plurality of X-ray detecting elements in a line.
Linear stress measurement device. 3. An X-ray stress measuring apparatus according to claim 1, wherein said X-ray detecting means arranges a plurality of X-ray detecting elements in a plane.