JPH0654265B2 - 2-axis swing X-ray stress measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an apparatus for measuring stress of a metal material or the like by X-ray diffraction.

(B) Conventional technology In this type of stress measurement, stress is applied to a material consisting of minute crystals.
This is because the lattice spacing of the crystal changes when added.
It Diffraction angle 2
θ is measured and sin² Is plotted as a variable, 2θ
And sin² Is theoretically a straight line, and the slope of this straight line
Is proportional to the stress on the material surface. Conventional X-ray stress measurement device
Then, this 2θ-sin² To obtain a diagram (regression line)
Do not irradiate a point on the surface of the material to be measured with an X-ray beam.
The position of the X-ray detector is scanned to find the peak of detection intensity.
Then, obtain the diffraction angle 2θ at that time, then use the X-ray tube or
Move the measurement material and change the X-ray incidence angle
Then, the diffraction angle 2θ is calculated, and 2θ is calculated for several points.
There is. When the relation with 2θ is obtained in this way, sin²
Is plotted on the horizontal axis and 2θ on the vertical axis.
Using the least squares method, a straight line (regression line) passing through the center of
Ask for.

When performing the above-mentioned measurement, the detector and the X-ray tube are usually swung around one axis in order to reduce the measurement error. This is to prevent the number of lattice planes that diffract the irradiation beam from varying depending on the incident angle due to the size of the crystal grains that make up the material, and to prevent inaccurate measurement values. However, even if such rocking is performed, if the material contains coarse crystal grains or has a texture such as a rolled metal material, the diffraction X-ray intensity decreases and the variation due to the orientation becomes large, which makes measurement difficult. was there. Generally, the crystalline state of practical materials includes a work-affected layer and a carburized / decarburized layer, and often has coarse crystal grains and a texture. Recently, there has been a demand for stress measurement of sintered alloys, non-ferrous metals, and ceramic materials having large crystal grains, but as described above, it is difficult to measure the stress of such materials with conventional devices.

(C) Object of the present invention An object of the present invention is to improve the conventional X-ray stress measuring device and to provide a device capable of accurately measuring stress even when a material having a large crystal grain or a texture is included.

(D) Structure The X-ray stress measuring apparatus of the present invention comprises an X-ray tube for irradiating the material to be measured with X-rays and a detector for detecting diffracted X-rays, and two straight lines passing through the X-ray incident position on the material surface. It is characterized in that a drive mechanism (hereinafter referred to as a swing drive mechanism) for rotating (swinging) a small angle about (two axes) is provided.

(E) Examples The present invention will be described in more detail with reference to Examples below. First
FIG. 1 is a block diagram showing the outline of one embodiment of the present invention.
Is an X-ray tube, (2) is an X-ray detector, and (3) is a material to be measured.
X-ray tube (1) and detector (2) are the X-ray incident position on the surface of the material (3)
It is attached to an arcuate support member (5) whose center point is (4). The X-ray tube (1) is fixed to the support member (5) and the detector
(2) is installed so as to be able to scan along the support member (5) by the motor (6). The support member (5) is further installed on the support member (7) so that it can be scanned by the motor (8), and the support member (7) also has an arc shape centered on the X-ray incident position (4). Has been formed. The support member (7) is fixed to the arm (9), and the arm (9) is attached to the rotating shaft of the motor (10) and is rotatable. The material (3) is fixed on the base (11) so that the X-ray incidence position (4) exists on the extension of the center line (A) of the rotation axis of the motor (10). motor
(6), (8) and (10) rotate according to the pulse signal sent from the control device (12), and the output of the detector (2) is sent to the control device (12) for processing and display.

The operation of the apparatus shown in FIG. 1 will be described below. The X-ray generated by the X-ray tube (1) is made into a thin beam shape by a solar slit (not shown), and the fixed point (4) on the surface of the material (3) is always irradiated during the measurement. In order to obtain the diffraction angle 2θ for a certain X-ray incident angle, the motor is controlled by the controller (12).
It is necessary to scan (6) and scan the angle 2θ 'formed by the emitted X-ray and the incident X-ray that is detected, but this scanning is performed stepwise from the initial position at a constant small angle. For each value of 2θ ', the output value from the detector (2) for a certain period of time is the control device.
It is sent to (12) and the control unit integrates this output value. Hereinafter, this detection for a certain period of time will be referred to as one-step measurement. The above integration has the same meaning as obtaining an average value. Motor during this one-step measurement
Swing is performed according to (8) and (10). When the motor (8) is driven, the detector, the X-ray tube and the support member (5) are
It moves along (7), which is a rotation around a straight line passing through the X-ray incident position (4). The control device uses a motor so that the rotation angle is within a range of ± Δθ _1. Control (8). The motor (10) is driven at the same time as the motor (8), and the periodic operation is performed within the rotation angle range of ± Δθ ₂ .
These operations are called rocking. These Δθ ₁ and Δθ ₂ are small values, and there is at least one cycle within the measurement time of one step, but there should be many cycles and the operation of the motors (8) and (10) If the periods are made different, the detectors and the like are effective because they do not take a simple orbit such as an ellipse as a result.

FIG. 2 is a diagram for explaining the swing, but for the sake of simplicity, the incident X
It is shown that the line is the Z axis, and the x axis and the y axis are the central axes of the swing. Due to such oscillation, the diffractive surface normal (a straight line that divides the incident X-ray and the diffracted X-ray into two equal parts and becomes a normal to the diffraction grating surface) is ₂ within the range of ± Δθ ₁ and ± Δθ 2. Shake the shaft.

The swing is performed for each measurement of one step, and once the measurement of one step is completed, the swing is stopped once and the motor is
By (6), the position of the detector, that is, 2θ ', is changed, the oscillation is restarted, and the next one-step measurement is performed.
FIG. 5 exemplifies the result of obtaining the change in the detected intensity with respect to the change in 2θ ′ in this way. The angle that peaks in the curve of FIG. 5 is the diffraction angle 2θ. In this way, the diffraction angle 2θ for one incident angle is obtained, and the same measurement is performed for several points.

When the relationship with 2θ is measured as described above, a 2θ-sin ² regression line is created by the method of least squares in the same manner as in the conventional case, and the stress σ is obtained from the slope.

The present invention is as shown in FIG.
The present invention is not limited to the figure, and any method may be used as long as the detector and the X-ray tube are oscillated around two straight lines passing through the X-ray incident position (4). Further, the two straight lines are not limited to being orthogonal to each other, and for example, the center (A) of the rotation axis of the motor (10) may be inclined.

Furthermore, it is possible to swing the material (3) instead of swinging the X-ray tube and the detector, but if the material to be measured is a structure and it is difficult to move it, use a detection system. The method of rocking is excellent.

(F) Effect According to the present invention, accurate stress measurement can be performed even for a material having large crystal grains or a material having a texture. In order to compare the present invention and the present invention with the experimental data, measurements were performed using an aluminum drawn material (having a texture) as the material to be measured, the relationship between 2θ and sin ² was plotted, and stress σ and measurement accuracy (dispersion) were measured. ) Was asked. Figure 3 is 2
The results are obtained by the shaft swing method, and FIG. 4 is based on the swing of only one axis. In FIG. 3 (method of the present invention), the stress is 3.93 kgF / cm ^{2 in the} compression direction and the dispersion is 0.93 kgF / cm ^2.
In Fig. 4, the stress is 0.84 kgF / cm in the tensile direction.
² , the dispersion was 8.43 kg / cm ² . As can be seen by comparing the dispersions, the present invention enables stress measurement, which is inaccurate and cannot be measured by the conventional method, and its effect is remarkable.

[Brief description of drawings]

FIG. 1 shows an embodiment of the device configuration of the present invention. FIG. 2 is a diagram for explaining the swing. 3 and 4 show the measurement results according to the present invention and the prior art, respectively, and FIG. 5 is a diagram showing an example of the measurement results for obtaining the diffraction angle 2θ. (1) …… X-ray tube, (2) …… X-ray detector (3) …… Measured material, (4) …… X-ray incident position (5), (7) …… Supporting member, (9 ) …… Arm (6), (8), (10) …… motor, (11) …… stand (14) …… incident X-ray, (13) …… exit X-ray (diffraction X-ray) (12) ……Control device

Claims (1)

[Claims] 1. An X-ray tube for introducing X-rays into a material to be measured,
A detector for detecting X-rays diffracted on the surface of the material, rotating means for rotating the X-ray tube and the detector around an incident point of the X-ray on the material, and the X-ray tube and the detector for the incident point. Passing through 2
It has a rotation oscillating means for oscillating about a straight line, and a control means for controlling the rotation means and the rotation oscillating means, and the control means moves the detector with respect to the X-ray tube. When detecting the diffracted X-rays by rotating the X-ray tube and the detector for a certain period of time, the detected intensity of the diffracted X-rays obtained is integrated, and the biaxial rocking X-ray stress measurement is performed. apparatus.