JP2002139478A - Creep damage detection method and device of structural material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a creep damage for each depth position of a structural material, and further to perform evaluation objectively. SOLUTION: An ultrasonic sound 3 is applied from the surface of the structural material to the bottom surface by an ultrasonic probe 2. Out of the detected waveforms, the time zone between a transmission pulse and a first bottom surface echo is divided into a plurality of equal sections, and a noise signal for each divided zone is analyzed by a computing unit 6. The analysis result it compared with the noise value ratio of a raw material for calculating as a numeric value. Numeric value data for each scanning position are stored at a storage 8, and are subjected to imaging processing as two-dimensional data by an image processor 9.

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 creep damage of a structural material for accurately detecting creep damage inside the structural material.

[0002]

2. Description of the Related Art Conventionally, research and development of remaining life evaluation of various industrial plants have been actively carried out. However, in order to predict the remaining life of plant equipment and the like, defective parts due to deterioration and damage of structural materials are considered. Nondestructive testing techniques are very important.

[0003] In the nondestructive inspection of a structural material, a replica method is known as a method for detecting a defect on the surface of the structural material. In this method, irregularities on the surface of a structural material are transferred by a thin film (replica) through which an electron beam easily passes, and this thin film is indirectly observed with an electron microscope.

On the other hand, as a method for detecting creep damage inside a structural material, an ultrasonic noise analysis method is known. In such an ultrasonic noise analysis method, in a portion where there is no defect in the structural material, since the ultrasonic wave incident from the material surface is reflected back on the bottom surface (back surface), it is detected as an echo. If there is a defect such as a void inside the material, for example, the scattered wave of the ultrasonic wave colliding with the defect is detected as noise, so that the existence of the defect can be grasped. That is, in the case of an undamaged material (new material) having no internal defect in the depth direction, an ultrasonic waveform as shown in an example in FIG. 4A is detected, and a defect such as a void exists in the internal depth direction. In the case of a damaged material, an ultrasonic waveform as shown in an example in FIG. 4B is detected by the sound returned from each defective portion.
When a noise signal in a time zone G between the first time and the first bottom echo b is gated and frequency-analyzed by FFT operation,
In the case of an undamaged material, a spectrum as shown in FIG. 5A is obtained, and in the case of a damaged material, a spectrum as shown in FIG. 5B is obtained. Therefore, the area value of the frequency spectrum is collated with a test curve as shown in FIG. 6 to perform creep damage evaluation. In this case, assuming that the area value of the frequency spectrum shown in FIG. 5A is 1 and the area value of the frequency spectrum shown in FIG. An evaluation of 85% is obtained.

[0005]

However, in the creep damage detection method using the ultrasonic noise analysis method, it is possible to evaluate the entire thickness of the structural material, but it is possible to evaluate a portion having a high degree of creep damage (depth position). ) Is difficult to identify, and a certain point is evaluated only by the calculated numerical value, so that there is a problem of lack of objectivity.

[0006] Therefore, the present invention is to make it possible to detect creep damage at each depth position of a structural material and to perform an objective evaluation.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an ultrasonic probe in which ultrasonic waves are incident from the surface to the bottom surface of a structural material, and a transmission pulse detected at that time is used. The time zone between the first bottom echo is divided into a plurality of equal parts, and the noise signal of each divided band is analyzed, thereby obtaining the creep damage degree for each depth position corresponding to each divided band as numerical data. A method and an apparatus for detecting creep damage of a structural material are described.

Since the noise signal is divided and analyzed in the depth direction of the structural material, information at each depth position can be obtained, and a portion having a high degree of creep damage can be specified.

[0009] Further, by causing the ultrasonic probe to scan and numerical data at each scanning position and depth position to be image-processed as two-dimensional data, the degree of creep damage can be objectively determined from the image. Evaluation is possible.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment of a creep damage detecting apparatus for a structural material according to the present invention. For example, a structural material 1 having a welded portion 1a is connected to an ultrasonic probe 2 through an ultrasonic probe 2. FIG. An ultrasonic transceiver 4 for transmitting and receiving the ultrasonic waves 3;
An A / D converter 5 for A / D converting an electric signal sent from the ultrasonic transmitter / receiver 4, and a transmission pulse of a waveform as shown in FIG. a is divided into a plurality of equal parts (for example, divided into five equal parts), and each divided band g is set, and each divided band g is gated for each divided band g. An arithmetic unit 6 for analyzing each noise signal by a noise analysis method, and a comparator 7 for comparing a calculation result of the arithmetic unit 6 with setting data of an undamaged material and digitizing the result.

A storage unit 8 for storing numerical data of each divided band g for each scanning position obtained by the comparator 7.
And an image processor 9 for processing the numerical data stored in the storage unit 8 as two-dimensional image data such as a color map as shown in FIG. 3, and displaying the image processed by the image processor 9. And a display 10.

For example, when detecting creep damage near the welded portion 1a of the structural material 1 as shown in FIG. 1, the ultrasonic probe 2 is placed on one side of the welded portion 1a. While transmitting the probe 2 in the direction of the arrow X, the transmitter 3 of the ultrasonic transmitter / receiver 4 transmits and propagates the ultrasonic wave 3 via the probe 2 while scanning the probe 2 in the direction of the arrow X. The wave is received by the receiving unit of the ultrasonic transceiver 4 via the probe 2, and the signal is digitized by the A / D converter 5 and sent to the arithmetic unit 6.

The computing unit 6 determines a plurality of divided bands g obtained by equally dividing a time zone G between the transmission pulse a and the first bottom echo b in the digital waveform as shown in FIG. A gate is applied to the band g, a noise signal for each divided band g is analyzed by a noise analysis method, and an analysis result is sent to the comparator 7. The comparator 7 estimates the creep damage degree for each divided band g from the noise value ratio compared with the new material, calculates the numerical value as a numerical value, and sends the numerical data to the storage device 8 for storage. . As a result, it is possible to specify a depth portion having a high degree of damage.

Further, in the same manner as described above, numerical data of the degree of creep damage at each scanning position accompanying the scanning of the probe 2 is sequentially stored in the storage unit 8. After the numerical data of the two-dimensional creep damage degree for each of the depth of the probe 2 and the scanning position is collected in this way, these numerical data are then sent to the image processor 9 and shown in FIG. Image processing is performed as two-dimensional data as described above, and is displayed on the display device 10. Therefore, the degree of creep damage can be objectively evaluated using the two-dimensional data.

It should be noted that the present invention is not limited to the above-described embodiment, and that the number of divisions of the time gate can be arbitrarily selected when analyzing the noise signal by the computing unit 6.
Of course, various changes can be made without departing from the spirit of the present invention.

[0017]

As described above, according to the present invention, ultrasonic waves are made incident from the surface of the structural material toward the bottom surface by the ultrasonic probe, and the transmission pulse and the first bottom surface echo detected at that time are detected. Structural material that divides the time zone between and into multiple equal parts and analyzes the noise signal for each divided band to obtain the creep damage degree for each depth position corresponding to each divided band as numerical data Since it is a creep damage detection method and apparatus, it is possible to obtain more detailed information than in the case of the conventional ultrasonic noise analysis method, it is possible to identify the depth portion of high creep damage degree, In addition, by scanning the ultrasonic probe and performing numerical processing on the numerical data for each scanning position and depth position as two-dimensional data, it is possible to perform a Objective evaluation of over-flops degree of damage can be carried out, to excellent effect and the like.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a structural material creep damage detection device according to the present invention.

FIG. 2 is an ultrasonic waveform diagram showing an example of a divided band set by a computing unit.

FIG. 3 is a diagram illustrating an example of an image processed by an image processor.

FIG. 4 shows a digitized ultrasonic waveform,
(A) is a diagram showing an example of a case of an undamaged material, and (B) is a diagram showing an example of a case of a damaged material.

FIGS. 5A and 5B show analysis results of an ultrasonic waveform, in which FIG. 5A shows an example of an undamaged material, and FIG. 5B shows an example of a damaged material.

FIG. 6 is a diagram showing a test curve used for evaluating the degree of creep damage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Structural material 2 Ultrasonic probe 3 Ultrasonic wave 4 Ultrasonic wave transmitter / receiver 5 A / D converter 6 Computing unit 7 Comparator 8 Memory unit 9 Image processor 10 Display a Transmission pulse b 1st bottom echo G time Band g Divided band

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Saburo Shibata 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawajima-Harima Heavy Industries, Ltd. Tokyo Engineering Center F-term (reference) 2G047 AA07 AB07 BC07 BC10 BC11 GA19 GG01 GG09 GG19 GG33 GH06

Claims (4)

[Claims] 1. An ultrasonic probe is irradiated by an ultrasonic probe from a surface of a structural material to a bottom surface, and a time zone between a transmission pulse detected at that time and a first bottom echo is divided into a plurality of equal parts. A method for detecting a creep damage degree of a structural material at each depth position corresponding to each divided band as numerical data by analyzing a noise signal for each divided band. 2. An ultrasonic probe is scanned.
2. The method for detecting creep damage of a structural material according to claim 1, wherein the numerical data at each of the scanning position and the depth position is imaged as two-dimensional data. 3. An ultrasonic transceiver for transmitting and receiving ultrasonic waves to and from a structural material via an ultrasonic probe, an A / D converter for digitizing an electric signal from the ultrasonic transceiver, and digitizing. An arithmetic unit for analyzing a noise signal for each divided band by dividing a time zone between the transmission pulse of the obtained waveform and the first bottom echo into a plurality of equal parts, and comparing the operation result of the arithmetic unit with the set data. An apparatus for detecting creep damage of a structural material, comprising a configuration provided with a comparator for digitizing. 4. A storage for storing numerical data of each divided band for each scanning position obtained by the comparator, and image processing of each numerical data stored in the storage to produce two-dimensional image data. 4. The apparatus for detecting creep damage of a structural material according to claim 3, further comprising an image processor for displaying the image on a display.