JP2001183313A - Method and apparatus for detecting inclusion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for detecting an inclusion capable of detecting the inclusion existing in a solid sample such as a steel or the like non-destructively. SOLUTION: The method for detecting the inclusion comprises the steps of irradiating a sample with a radioactive ray such as preferably a γ ray or an X-ray, measuring the intensity of the elastically scattered radiation by the sample and/or the intensity of the inelastically scattered radiation, and detecting the inclusion existing in the sample based on the obtained intensity. The apparatus for detecting the inclusion is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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 detecting inclusions in a solid body by a non-contact method, 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 the intensity of elastic scattered radiation and / or the intensity of inelastic scattered radiation of the radiation from the sample is measured.
An inclusion detection method characterized by detecting inclusions present inside a sample based on the obtained intensity. In the first aspect, it is preferable that the radiation is γ-ray or X-ray.

[0008] In the first aspect of the present invention,
(1) a plurality of irradiation areas of the radiation, or (2)
Either a plurality of measurement regions of the intensity of the elastic scattered radiation and / or a measurement region of the intensity of the inelastic scattered radiation, or (3) a plurality of irradiation regions of the radiation, and a measurement region of the intensity of the elastic scattered radiation It is preferable that a plurality of measurement regions for the intensity of the inelastic scattered radiation are provided.

In the first aspect of the present invention, when X-rays are used as 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,
Energy of elastic scattered radiation by the radiation sample-
It is preferable to measure the integrated intensity of the peak region in the intensity distribution and / or the integrated intensity of the peak region in the energy-intensity distribution of the inelastic scattered radiation, and to detect inclusions in the sample based on the obtained integrated intensity.

Further, the first invention is suitably used for analyzing a sample in which the sample is a solid sample such as steel. The second invention is a radiation irradiation system 3 having a radiation source 1 and a collimator 2 disposed between the radiation source 1 and the sample to define a radiation irradiation area, a detector 4 for detecting scattered radiation from the sample, and a detector 4 A measurement system having a collimator for defining a measurement area disposed between the sample and a sample, and a device for counting and calculating the intensity of scattered radiation from the sample detected by the detector; It is an object detection device.

In the second aspect, it is preferable that the radiation source 1 is a γ-ray source (1A) or an X-ray source (1B). Further, in the second invention, it is preferable to include a plurality of the radiation irradiation systems and / or a plurality of the measurement systems. That is, in the second invention described above, the radiation irradiation area and the measurement area are targeted at a plurality of radiation irradiation areas and / or a plurality of measurement areas, and the plurality of radiation irradiation areas corresponding to the plurality of radiation irradiation areas, respectively. It is preferable to provide a radiation irradiation system and / or a plurality of measurement systems corresponding to a plurality of measurement regions, respectively.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. In order to solve the above-mentioned problems, the present invention irradiates a sample with radiation such as γ-rays or X-rays, and irradiates the sample with the radiated radiation. The inclusion is detected by measuring the intensity.

The case where γ-rays are used as radiation will be described below. 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. 5 shows the intensity distribution of scattered radiation when the solid is irradiated with γ-rays.

As shown in FIG. 5, scattered radiation is elastic scattered radiation (Rayleigh scattered radiation) scattered without losing energy, and inelastic scattered radiation 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

[0016]

(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, inclusions can be detected 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

[0019]

(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.

In the present invention, inclusions present inside the 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 are measured,
The intensity ratio may be used. Next, FIG. 2 shows an example of the inclusion detection device of the present invention in a side sectional view. In FIG. 2, 1 (1A) is a radiation source which is a γ-ray source, 2 is a collimator which is an incident collimator, 3 is a radiation irradiation system,
4 is a detector for scattered radiation from the sample, 5 is a collimator that is a take-out collimator that defines a measurement area, 6 is a device for counting and calculating the intensity of scattered radiation from the sample detected by the detector 4, and 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. 2, the measurement position is controlled by a control signal 13 from the control device 8 to the sample moving table moving device 12. The inclusion detection device of the present invention includes the following (1) a radiation irradiation system 3 and (2) a measurement system 7. (1) Radiation irradiation system 3: has a radiation source 1 and a collimator 2 disposed between the radiation source 1 and the sample S to define a radiation irradiation area.

(2) Measuring system 7: Detector 4 for scattered radiation from sample S, collimator 5 disposed between detector 4 and sample S to define a measurement area,
And a device 6 for counting and calculating the intensity of scattered radiation from the sample S detected by the detector 4. Note that, as described above, the collimators 2 and 5 on the incident side and the detection side are for limiting the irradiation area of radiation and the incident area to the detector, that is, the measurement area, respectively. A preferable collimator can be installed depending on the size.

As the detector 4, a semiconductor detector can be used. However, in order to increase the measurement position resolution and detect smaller inclusions, a plurality of measurement areas are required for one radiation irradiation area. It is preferred to provide an area, that is to say a plurality of detectors and a plurality of collimators on the detector side. Further, it is preferable that a plurality of radiation irradiation areas are provided, that is, a plurality of radiation sources and a plurality of collimators on the incident side are provided.

In the present invention, a detecting element having a positional resolution may be used. The use of such a detection system can improve the position resolution, measure a plurality of regions by one measurement, and measure a predetermined area at high speed. Further, in the present invention, the apparatus integrating the irradiation system and the detection system is placed on a moving table for scanning a moving sample such as a steel slab in the width direction, and the moving sample surface is measured in the width direction and the longitudinal direction. By doing so, the entire surface of the sample can be measured quickly.

FIG. 3 is a side sectional view showing an example of the above-described inclusion detecting device of the present invention. In FIG. 3, reference numeral 14 denotes a detection system including a take-out collimator 5 and a detector 4, 15 denotes a storage case for the radiation irradiation system 3 and the detection system 14, and 16a and 16b denote storage cases (the radiation irradiation system 3 and the detection system 14). 2) 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, and other symbols are the same as those in FIG.

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

In the above, the case where γ-rays and γ-ray sources are mainly used as radiation and radiation sources has been described.
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). FIG. 4 shows that X
An example of the inclusion detection device of the present invention using a radiation source is shown in a plan view (enlarged partial plan view) (a) and a side sectional view (b).

[0030] In FIG. 4, 1 (1B) shows the radiation source is an X-ray source, 4 a plurality of detectors _{4 1, 4 2, 4 i} , 4 n-1, 4 n
Detector composed of a plurality of collimators 5 ₁ of 5 detector _side, 5 _2, 5 _i, 5 _n-1, a collimator consists of _{5 n, 10,10 1, 10 i} , 10 n Represents scattered radiation, 20 represents a radiation (X-ray) irradiation region, 30 ₁ , 30 _{i, and} 30 _n represent a plurality of measurement regions in the measurement region.

In the inclusion detecting apparatus shown in FIG. 4, the detector and the collimator on the detector side are each n.
Although the bases are arranged, the illustration is simplified. In the present invention, when X-rays are used as radiation, it is preferable to irradiate the sample with short-wavelength X-rays having a wavelength of 3 ° or less in consideration of the penetration depth of the X-rays.

[0032]

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. 2 was used. A simulated sample with inclusions inside the steel was created by drilling open holes with different diameters and depths in a steel sample with a thickness of 20 mm, filling it with alumina, and placing iron plates with different thicknesses on it. .

Next, these samples were irradiated with gamma rays emitted from ²⁴¹ Am, and the elastic scattering gamma ray intensity and the inelastic scattering gamma ray intensity were measured using a semiconductor detector. Table 1 shows the specifications of the sample used and the obtained inelastic scattered γ-ray intensity (integrated intensity in the peak region). FIG. 1 shows the relationship between the thickness of the alumina in the sample, the thickness of the iron plate above the sample, and the inelastic scattered γ-ray intensity (the integrated intensity in the peak region) when the diameter of the alumina in the sample is 1 mm. .

As shown in FIG. 1, it has been found that the inclusion detection method and the inclusion detection device of the present invention make it possible to clearly detect the inclusions present inside the sample.

[0035]

[Table 1]

(Embodiment 2) In this embodiment, the above-described inclusion detecting apparatus shown in FIG. 4 was used. The sample (sample Nos. 1 to 3) used in Example 1 is irradiated with X-rays emitted from a W tube, and a detector (counter) is used to elastically scatter WKα rays (wavelength: 0.2 °). X-ray intensity and inelastic scattered X-ray intensity were measured.

Table 2 shows the specifications of the samples used and the average values of the obtained inelastic scattered X-ray intensities (integrated intensity in the peak region). As shown in Table 2, the inclusion detection method of the present invention,
It has been found that the inclusion detection device can clearly detect inclusions present inside the sample.

[0038]

[Table 2]

(Example 3) A sample of a steel slab was irradiated with γ-rays emitted from ²⁴¹ Am using the inclusion detecting device shown in FIG. 3 described above, and inelastic scattering γ was irradiated using a semiconductor detector.
The line intensity was measured. In the above-described measurement, the surface of the slab sample is scanned, and the number of inclusions is determined from the number of peaks in which the inelastic scattered γ-ray intensity (integrated intensity of the peak region) is equal to or greater than a predetermined value. A peak whose intensity was equal to or greater than a predetermined value determined by the measurement conditions was determined to be an inclusion having a size of 50 μm or more.

Next, 1 mm of the surface layer of the above slab sample was dissolved in an acid, and the particle size of the inclusions was measured for the obtained residue by a laser diffraction method. Table 3 shows the results of measuring the particle size of the inclusions obtained by both the methods described above. 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 present invention clearly shows inclusions present inside a solid sample such as a steel slab. It was found that it could be detected.

[0041]

[Table 3]

[0042]

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 a graph showing the relationship between the thickness of alumina in a sample, the thickness of an iron plate above the sample, and the inelastic scattering γ-ray intensity.

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 showing an example of the inclusion detecting device of the present invention (a plan view (enlarged partial plan view): (a), a side sectional view: (b)).
It is.

FIG. 5 is a graph showing an intensity distribution of scattered γ-rays (energy-intensity of scattered γ-rays) when the solid is irradiated with γ-rays.

[Explanation of symbols]

1 radiation source 1A gamma ray source (radiation source) 1B X-ray source (radiation source) 2 collimator (incidence collimator) 3 irradiation system _{4,4 1, 4 2, 4 i} , 4 n-1, 4 n samples detector _{5,5 1, 5 2, 5 i} , 5 n-1, 5 n collimator (extraction collimator) 6 counting and calculation device 7 measuring system 8,18 controller 9 incident radiation 10 of the scattered radiation from, 10 ₁ , 10 _i , 10 _n Scattered radiation 11 Sample moving table 12 Sample moving table moving device 12a Rod 12b Rod driving device 13, 19 Control signal 14 Detection system 15 Storage cases 16a, 16b Moving table 17 Moving table driving device 20 Radiation (X-ray) irradiation area 30 ₁ , 30 _i, 30 _n Multiple measurement areas within the measurement area

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Tomohiro Matsushima 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref. Kawasaki Steel Research Institute Co., Ltd. (72) Inventor Naoki Matsuura 14-8 Akaoji-cho, Takatsuki-shi, Osaka Inside Rigaku Electric Industry Co., Ltd. LA02 SA02

Claims (6)

[Claims] 1. A sample is irradiated with radiation, the intensity of elastic scattered radiation and / or the intensity of inelastic scattered radiation by the sample is measured, and inclusions present inside the sample are detected based on the obtained intensity. A method for detecting inclusions. 2. The method according to claim 1, wherein the radiation is γ-rays or X-rays. (1) a plurality of irradiation regions of the radiation, or (2) a plurality of measurement regions of the intensity of the elastic scattered radiation and / or a plurality of measurement regions of the intensity of the inelastic scattered radiation, Or (3) a plurality of radiation irradiation regions, and a measurement region of the intensity of the elastic scattered radiation and / or
3. The method for detecting an inclusion according to claim 1, wherein a plurality of measurement regions for the intensity of the inelastic scattered radiation are provided. 4. A collimator for defining a radiation source and a radiation irradiation area disposed between the radiation source and the sample.
A radiation irradiation system (3) with (2), a detector (4) for scattered radiation from the sample, and a collimator (5) and detector that define the measurement area placed between the detector (4) and the sample An inclusion detection device comprising a measurement system (7) having a device (6) for counting and calculating the intensity of scattered radiation from the sample detected in (4). 5. The radiation source (1) is a gamma ray source (1A) or an X-ray source (1A).
5. The device for detecting inclusions according to claim 4, wherein the device is a radiation source. 6. The inclusion detection apparatus according to claim 4, further comprising a plurality of radiation irradiation systems and / or a plurality of measurement systems.