JP2001281174A - Inclusion detecting method and inclusion detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inclusion detecting method and an inclusion detector capable of detecting an inclusion existing within a solid sample such as steel in a non-destructive manner. SOLUTION: The sample is irradiated with a radiation, preferably gamma rays or X rays. The radiation is scattered elastically and/or non-elastically by the sample. The elastically scattered radiation and/or the non-elastically scattered radiation are taken into a radiation detector through a tube bundle for radiation transmission. The inclusion existing within the sample is detected based on the intensity of the elastically scattered radiation and/or the non- elastically scattered radiation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting inclusions present in a solid sample, and more particularly to a method and apparatus for detecting inclusions present in steel such as steel slabs. The present invention relates to an object detection device.

[0002]

2. Description of the Related Art Inclusions present on the surface and several mm below the surface of a steel slab obtained by continuous casting of molten steel cause surface defects called so-called ridges when the slab is rolled. For this reason, the development of a non-destructive detection method for the presence or absence of an inclusion and the location of the inclusion is desired.

On the other hand, as a method of detecting inclusions inside a solid, there is a method of irradiating a solid with ultrasonic waves and detecting ultrasonic waves reflected by the inclusions. It is not applicable to hot slabs because it requires a medium, such as water, to communicate to the slab, and requires the detector to be in contact with a solid. As a method of non-contact detection of inclusions in a solid, a laser ultrasonic method can be used.

According to this method, a solid is irradiated with a condensed laser beam, and the variation of an elastic wave generated on the surface of the solid due to inclusions is measured by irradiating another laser beam to the solid surface and changing the reflection position. However, a slab having a non-mirror surface, such as a slab, cannot be applied because the reflection intensity of laser light is low and the reflection position greatly changes due to surface irregularities.

As described above, conventionally, it has been extremely difficult to non-destructively detect inclusions present inside a solid sample such as a steel slab having a high temperature and large surface irregularities.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and includes an inclusion detection method and an inclusion capable of detecting inclusions present inside a solid sample such as steel. The object of the present invention is to provide a detection device, and furthermore, it is possible to non-destructively detect inclusions present inside a solid sample having a high temperature and large surface irregularities, such as a steel slab, which was conventionally difficult. It is an object to provide a detection method and an inclusion detection device.

[0007]

According to a first aspect of the present invention, a sample is irradiated with radiation, and elastic scattered radiation and / or inelastic scattered radiation of the radiation by the sample are taken into a radiation detector by a radiation transmission tube bundle. An inclusion detection method characterized by detecting inclusions present inside a sample based on the intensity of elastic scattered radiation and / or the intensity of inelastic scattered radiation detected by a radiation detector.

[0008] In the first aspect of the present invention, it is preferable that the radiation is γ-ray or X-ray. In the first aspect of the invention, when X-rays are used as the radiation for irradiating the sample, the X-rays are preferably short-wavelength X-rays having a wavelength of 3 ° or less.

In the first aspect of the present invention, it is preferable that the radiation transmission tube bundle is a tube bundle for γ-ray transmission and / or X-ray transmission. In addition, the first
In the invention, the radiation transmission tube bundle is preferably a radiation transmission tube bundle in which elastic scattered radiation and / or inelastic scattered radiation are totally reflected and transmitted in the tube.

In the first aspect of the present invention, the intensity of elastic scattered γ-rays transmitted through each tube of the radiation transmission tube bundle and / or the intensity of elastic scattered γ-rays transmitted through each tube of the radiation transmission tube bundle are controlled. It is preferable to measure the intensity of each elastic scattering γ-ray. In the first aspect, the integrated intensity of the peak region in the energy-intensity distribution of the elastic scattered radiation and / or the peak intensity in the energy-intensity distribution of the inelastic scattered radiation of the sample is measured. Then, it is preferable to detect inclusions in the sample based on the obtained integrated intensity.

According to a second aspect of the present invention, there is provided a radiation irradiation system 3 having a radiation source 1, a collimator 2 disposed between the radiation source 1 and the sample, and defining a radiation irradiation area on the sample, a scattered radiation from the sample. Detector 4 and a radiation transmission tube bundle 5 and the detector 4 which are disposed between the detector 4 and the sample and take in scattered radiation from a plurality of measurement regions in the radiation irradiation region into the detector 4. An inclusion detection device comprising a measurement system 7 having a device 6 for counting and calculating the intensity of scattered radiation from a detected sample.

In the second aspect, the radiation source 1 is preferably a γ-ray source 1A or an X-ray source 1B. In the second aspect, it is preferable that the radiation transmission tube bundle 5 is a tube bundle for γ-ray transmission and / or X-ray transmission. In the second aspect, it is preferable that the radiation transmission tube bundle 5 is a radiation transmission tube bundle in which elastic scattered radiation and / or inelastic scattered radiation are totally reflected and transmitted in the tube.

Further, in the second invention,
It is preferable that the detector 4 and the counting and calculating device 6 are the detector 4 and the counting and calculating device 6 that detect, count, and calculate each of the scattered radiation transmitted in each tube of the radiation transmission tube bundle 5. .

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In order to solve the above-described problems, the present invention irradiates a sample with radiation such as γ-rays or X-rays, and emits elastic scattered radiation and / or inelastic scattered radiation generated when the irradiated radiation is scattered by the sample. The inclusion in the radiation detector is detected by a transmission tube bundle, and the inclusions inside the solid are detected by measuring the intensity of the elastic scattered radiation and / or the intensity of the inelastic scattered radiation.

Hereinafter, the case where γ-rays are used as radiation will be described. When a solid is irradiated with γ-rays having a specific energy, the γ-rays enter the predetermined depth while being attenuated in the solid. During this time, the γ-rays are scattered by atoms in the solid to generate scattered radiation. FIG. 6 shows the intensity distribution of scattered radiation when a solid is irradiated with γ-rays.

As shown in FIG. 6, elastic scattered radiation (Rayleigh scattered radiation) is scattered without losing energy, and inelastic scattered radiation is scattered by losing a certain energy determined by the composition of a solid. (Compton scattered radiation). The present invention provides an inclusion detection method and an inclusion detection device for detecting inclusions present inside a sample from the intensity of these scattered radiations.

The intensity I _co of the elastically scattered radiation is given by the following equation (1).
Represented by

[0018]

(Equation 1)

Here, I _e is the scattering intensity of one electron, e
Is the electron charge, c is the speed of light, m is the mass of the electron, χ is the scattering angle, f is the atomic scattering factor, Z is the atomic number, and λ is the wavelength of the incident γ-ray. Since the atomic scattering factor f is inherent to atoms as shown in the above formulas (3) and (4), if there is an inclusion different from the matrix component of the sample in the solid sample, the elastic scattering radiation to be measured is Varies in intensity.

Therefore, from the change in the intensity of the elastic scattered radiation, it is possible to detect inclusions at a depth inside the sample where γ rays can penetrate and scattered rays can be detected. On the other hand, the intensity I _inco of the inelastic scattered radiation is given by the following equation (5).
Represented by

[0021]

(Equation 2)

Therefore, similarly to the case of elastic scattered radiation, if there is an inclusion different from the matrix component of the sample in the solid sample, the intensity of the measured inelastic scattered radiation changes, and the intensity of the inelastic scattered radiation changes. It is possible to detect inclusions at a depth inside the sample where γ-rays can penetrate and scattered rays can be detected from the change. The detectable depth inside the sample depends on the energy of the γ-ray used and the mass absorption coefficient for the γ-ray determined by the composition of the sample. For example, the energy is 59.5 ke for a steel sample.
When V gamma rays ( ²⁴¹ Am) are used, the diameter is about 2 mm.

According to the present invention, inclusions present inside a sample are detected by measuring the intensity of the elastic scattered radiation and / or the intensity of the inelastic scattered radiation. Either the elastic scattered radiation or the inelastic scattered radiation may be used, but it is preferable to use the larger of the elastic scatterability and the inelastic scatterability of the sample to be measured. In the present invention, both the intensity of elastic scattered radiation and the intensity of inelastic scattered radiation may be measured, and the intensity ratio may be used.

Next, FIG. 1 is a side sectional view showing an example of the inclusion detecting device of the present invention. In FIG. 1, 1
(1A) is a radiation source that is a γ-ray source, 2 is a collimator that is an incident collimator, 3 is a radiation irradiation system, 4 is a detector of scattered radiation from a sample, and 5 is a plurality of measurement regions in the radiation irradiation region. (minute region) a ₁ to a _n radiation transmission tube bundle capturing scattered radiation to the detector 4 _{from, 5 1, 5 i, 5} n radiation transmission tube constituting the pipe bundle radiation transmission (radiation transmission capillary) , 6 is a device for counting and calculating the intensity of scattered radiation from the sample detected by the detector 4, 7 is a measurement system, 8 is a control device, 9 is incident radiation, 10 is scattered radiation, 11 is a sample moving table, 12 Is a sample moving table moving device, 12a is a rod for moving the sample moving table, 12b is a driving device for the rod 12a, 13 is a control signal for indicating a measurement position, and S is a sample.

In the inclusion detecting device shown in FIG. 1, the measurement position of the sample S is controlled by a control signal 13 from the control device 8 to the sample moving table moving device 12. The sample S is moved by the sample moving table moving device 12 in the left-right direction and the vertical direction in FIG. The inclusion detection device of the present invention includes the following (1) a radiation irradiation system 3 and (2) a measurement system 7.

(1) Irradiation system 3: radiation in the present invention
The ray irradiation system 3 includes the radiation source 1 and the radiation source 1 and the sample S.
Is disposed between the two to define a radiation irradiation area on the sample S.
It has a meter 2. (2) Measurement system 7: The measurement system 7 in the present invention starts from the sample S.
Between the detector 4 and the sample S,
Multiple measurement areas (micro areas) within the radiation irradiation area
A₁~ A _nFor taking scattered radiation from the detector 4 into the detector 4
From the transmission tube bundle 5 and the sample S detected by the detector 4
Of the intensity of the scattered radiation.

As described above, the collimator 2 on the incident side is for limiting the irradiation area of the radiation, and a suitable collimator can be installed depending on the size of the inclusion to be measured. As the detector 4, a counter tube, a semiconductor detector, a CCD detector, or an imaging plate can be used. However, in order to increase the positional resolution of the measurement and to detect smaller inclusions, the radiation transmission tube bundle 5 is used. It is preferable to use a detector that detects each of the scattered radiation transmitted through each of the tubes.

For this reason, in the present invention, as the detector 4, a movable counter tube, a semiconductor detector, a CCD detector, or an imaging plate, ie, a BaFBr: It is preferable to use a film having a photostimulable luminous body such as Eu ²⁺ applied on the surface. As a CCD detector, a method of directly detecting the scattered radiation 10 with the CCD detector 20 as shown in FIG. 5A, or a method of converting the scattered radiation 10 into light as shown in FIG. Using body 21, light 22 emitted from phosphor 21 is CC
A method of detecting with the D detector 20 can be used.

In the present invention, a detecting element having a positional resolution may be used. The counting and calculating device 6 is preferably a counting and calculating device that counts and calculates each detection intensity of the scattered radiation transmitted through each tube of the radiation transmission tube bundle 5. Note that the counting / arithmetic device 6 counts the intensity of the scattered radiation detected by the detecting device 4 and normalizes those count values, and performs an operation for performing two-dimensional display by mapping.

In the present invention, the use of the measurement system 7 having the tube bundle 5 for radiation transmission improves the positional resolution, allows a plurality of different micro regions to be measured by a single measurement, and allows the measurement of a predetermined area at a high speed. Can be performed. The radiation transmission tube bundle 5 is used for γ-ray transmission and / or
Alternatively, the tube bundle is preferably a tube bundle for X-ray transmission, and is preferably a tube bundle for radiation transmission in which elastic scattered radiation and / or inelastic scattered radiation is totally reflected and transmitted.

As the above-described radiation transmission tube bundle 5, a tube bundle formed by bundling a plurality of tubes (capillaries) having a small inner diameter made of glass, quartz or metal can be used, but the inner and outer diameters of the tubes are small. It is more preferable to use a tube bundle formed by bundling a plurality of tubes (capillaries) each made of glass or quartz and having a small inner diameter in order to increase the positional resolution of the minute region using a tube.

The glass is preferably borosilicate glass, and the quartz is preferably fused quartz. Further, as the radiation transmission tube bundle 5, it is preferable that the surface of the inner wall surface of the tube is close to a mirror surface. Therefore, the surface accuracy of the inner wall surface of the tube is 10 ° (1 nm) RMS (: root mean).
square).

In this case, the surface accuracy of the surface of the inner wall surface of the tube of the radiation transmission tube bundle 5 does not necessarily have to be 10 ° (1 nm) RMS or less, and the average surface of all the tubes is not required. Accuracy may be less than 10Å (1 nm) RMS. Further, in the present invention, in order to scan a moving sample such as a steel slab in the width direction, an apparatus integrating an irradiation system and a detection system,
The entire surface of the sample can be quickly measured by placing the sample on the moving table and measuring the moving sample surface in the width direction and the longitudinal direction.

FIG. 2 is a side sectional view showing an example of the above-described inclusion detecting device of the present invention. In FIG. 2, reference numeral 14 denotes a detection system including the radiation transmission tube bundle 5 and the detector 4, 15 denotes a storage case for the radiation irradiation system 3 and the detection system 14,
16a and 16b are storage cases (radiation irradiation system 3 and detection system
14) A moving table for moving, 17 is a moving table driving device, 18 is a control device, 19 is a control signal for instructing a measurement position, f indicates a moving direction of a sample S such as a steel slab, and other symbols are figures. Shows the same content as 1.

The moving tables 16a and 16b are integrated tables except for an opening serving as a path for the irradiation radiation 9 and the scattered radiation 10. In the inclusion detection device shown in FIG. 2, the radiation irradiation system 3 and the detection system 14 are housed in a storage case 15, and the radiation irradiation system 3 and the detection system are controlled by a control signal 19 from a control device 18 to a moving table driving device 17. 14 is moved (traversed) in the width direction of the sample S (the direction perpendicular to the paper surface of FIG. 2) to control the measurement position.

The case where γ-rays and γ-ray sources are mainly used as radiation and radiation sources has been described above.
In the present invention, the same operation and effect can be obtained when an X-ray and an X-ray source are used as radiation (incident radiation) and radiation source (incident radiation source). FIGS. 3 and 4 show an example of the inclusion detection apparatus of the present invention using an X-ray source as a radiation source.
Shown by side sectional view.

FIG. 3 shows a method for controlling the measurement position by moving the sample S in the same manner as in FIG. 1, and FIG.
In this method, a moving sample surface such as a steel slab is measured in the sample width direction and the sample longitudinal direction (sample moving direction) as in FIG. 2 described above. In FIGS. 3 and 4, 1 (1B) indicates a radiation source which is an X-ray source, and the other symbols indicate the same contents as those in FIGS.

In the present invention, when X-rays are used as radiation, the wavelength is 3Å (0.3 n) in consideration of the penetration depth of the X-rays.
m) It is preferable to irradiate the following short wavelength X-rays to the sample. Although the present invention has been described above, the inclusion detection device of the present invention may further include a goniometer for controlling a radiation incident angle on the sample and an extraction angle of scattered radiation from the sample.

[0039]

EXAMPLES The present invention will be described below more specifically based on examples. (Embodiment 1) In this embodiment, the above-described inclusion detecting device shown in FIG. 1 was used. In the present embodiment,
As the radiation transmission tube bundle 5, the tube material is borosilicate glass, the tube inner diameter is 1 μm, and the surface accuracy of the tube inner wall surface is 10 mm (1 nm) RM.
A bundle of 40,000 tubes below S was used.

As the detector 4, a movable counter tube for scanning the cross section of the radiation transmitting tube bundle 5 two-dimensionally in the plane direction was used. A simulated sample having inclusions inside the steel was prepared by forming open holes with different diameters in a steel sample having a thickness of 20 mm, filling the sample with alumina, and placing iron plates with different thicknesses thereon.

Next, these samples are irradiated with γ-rays emitted from ²⁴¹ Am, and the respective intensities of the elastic scattered γ-rays transmitted through each tube of the radiation transmission tube bundle 5 and the inelastic scattered γ-rays Each strength was measured. Table 1 shows the specification of the sample used and the result of normalizing and mapping the obtained inelastic scattered γ-ray intensity (integrated intensity in the peak region).

In the mapping chart of the normalized inelastic scattered γ-ray intensity in Table 1, in the area of 2 mm × 2 mm centering on the position of alumina, a portion where the intensity is low is white, and a portion where the intensity is high is black. it's shown. As shown in Table 1, it was found that the inclusion detection method and the inclusion detection device of the present invention can clearly detect inclusions present inside the sample.

[0043]

[Table 1]

(Embodiment 2) In this embodiment, the above-described inclusion detecting device shown in FIG. 3 was used. In this embodiment, the same radiation transmission tube bundle and detector as those used in Example 1 were used as the radiation transmission tube bundle 5 and the detector 4. The sample used in Example 1 described above (sample
Nos. 1 to 3) were irradiated with X-rays emitted from a W tube, and the detector 4 measured the elastic scattered X-ray intensity and the inelastic scattered X-ray intensity of WKα rays (energy: 58.5 keV).

In this case, the respective intensities of elastic scattered γ-rays and the intensities of inelastic scattered γ-rays transmitted in the respective tubes of the radiation transmission tube bundle 5 were measured. In Table 2,
The result of mapping and normalizing the specification of the used sample and the obtained inelastic scattered X-ray intensity (integrated intensity of the peak region) in the measurement region is shown. In the mapping diagram of the normalized inelastic scattered X-ray intensity in Table 2, in the area of 2 mm × 2 mm centering on the position of alumina, a weak portion is displayed in white, and a strong portion is displayed in black. I have.

As shown in Table 2, it was found that the inclusion detection method and the inclusion detection device of the present invention can clearly detect inclusions present inside the sample.

[0047]

[Table 2]

Example 3 A moving steel slab sample was irradiated with γ-rays emitted from ^{24 1} Am using the inclusion detector shown in FIG. 2 to measure the inelastic scattered γ-ray intensity. did. In this embodiment, the radiation transmission tube bundle 5 is used.
The same tube bundle for radiation transmission as used in Example 1 was used, and as the detector 4, a CCD detector was used.

As a CCD detector, FIG.
The detector shown in (b) was used. In the above measurement, the surface of the slab sample was scanned in the width direction, and the inelastic scattering γ
The line intensity (integral intensity of the peak area) is normalized, and two-dimensional display is performed by mapping.
The inclusions less than m were determined. Next, 1 mm of the surface layer of the above slab sample was dissolved in an acid, and the obtained residue was measured for the particle size of inclusions by a laser diffraction method.

Table 3 shows the measurement results of the particle size of the inclusions obtained by the above two methods. As shown in Table 3, the results obtained by the present invention are in good agreement with the results obtained by the acid dissolution-laser diffraction method, and the inclusions present inside a moving solid sample such as a steel slab according to the present invention. Was clearly detected.

[0051]

[Table 3]

[0052]

According to the present invention, non-destructive inclusions present in a solid sample such as steel can be detected. In addition, since the present invention can be applied to high-temperature solids and solids with large surface irregularities, it is also possible to detect inclusions present inside the steel slab, and to eliminate inclusions after processing such as rolling of the steel slab. It has become possible to prevent surface defects that occur as a cause.

[Brief description of the drawings]

FIG. 1 is an explanatory view (side sectional view) showing an example of an inclusion detection device of the present invention.

FIG. 2 is an explanatory view (side sectional view) showing an example of the inclusion detection device of the present invention.

FIG. 3 is an explanatory view (side sectional view) showing an example of the inclusion detection device of the present invention.

FIG. 4 is an explanatory view (side sectional view) showing an example of the inclusion detection device of the present invention.

FIG. 5 is an explanatory diagram showing a method for detecting scattered radiation by a CCD detector.

FIG. 6 is a graph showing an intensity distribution of scattered γ rays (energy of scattered γ rays 線 intensity) when the solid is irradiated with γ rays.

[Explanation of symbols]

Reference Signs List 1 radiation source 1A γ-ray source (radiation source) 1B X-ray source (radiation source) 2 collimator (incident collimator) 3 radiation irradiation system 4 detector of scattered radiation from sample 5 radiation transmission bundle 5 ₁ , 5 _i , 5 _n Radiation transmission tube (radiation transmission capillary) 6 Counting / calculating device 7 Measuring system 8, 18 Controller 9 Incident radiation 10 Scattered radiation 11 Sample moving table 12 Sample moving table moving device 12a Rod 12b Rod driving device 13 , 19 control signals 14 detection system 15 housing case 16a, 16b moving table 17 moving table drive unit 20 CCD detector 21 phosphor 22 light a _1, a _i, a _n plurality of measurement areas irradiated region (micro-region) f Moving direction of sample

Continuation of the front page (72) Inventor Kimi Yamamoto 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref. Kawasaki Steel Engineering Co., Ltd. (72) Inventor Naoki Matsuura 14-8 Akaoji-cho, Takatsuki-shi, Osaka F term (for reference) 2G001 AA01 AA02 AA09 BA14 BA16 CA01 CA02 DA01 DA02 DA09 GA01 GA06 HA01 HA15 JA13 KA03 LA02 SA02 4E004 MC30

Claims (4)

[Claims] 1. A sample is irradiated with radiation, and elastic scattered radiation and / or inelastic scattered radiation of the radiation by the sample are taken into a radiation detector by a radiation transmission tube bundle.
An inclusion detection method, comprising: detecting inclusions present inside a sample based on the intensity of elastic scattered radiation and / or the intensity of inelastic scattered radiation detected by the radiation detector. 2. The method according to claim 1, wherein the radiation is γ-rays or X-rays. 3. A radiation irradiation system (3) having a radiation source (1), a collimator (2) disposed between the radiation source (1) and the sample, and defining a radiation irradiation area on the sample; A detector for detecting scattered radiation from the detector (4) and a radiation disposed between the detector (4) and the sample, the scattered radiation from a plurality of measurement regions in the radiation irradiation region being taken into the detector (4) Inclusion detection characterized by comprising a measurement system (7) having a device (6) for counting and calculating the intensity of scattered radiation from the sample detected by the transmission tube bundle (5) and the detector (4). apparatus. 4. The radiation source (1) is a gamma ray source (1A) or an X-ray source (1A).
The inclusion detection device according to claim 3, wherein the inclusion detection device is a radiation source (1B).