JPH0690183B2 - Defect type / shape discrimination method by electronic scanning ultrasonic flaw detection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention uses an array probe in which a plurality of transducers are arranged in a straight line to detect electrons in a defect in an object to be inspected. In the scanning ultrasonic flaw detection method,
The present invention relates to a defect type / shape discrimination method by electronic scanning ultrasonic flaw detection capable of discriminating shapes in a short time and with high reliability.

(Prior Art) Generally, an ultrasonic flaw detection method has been used as one of the methods for flaw detection of a defect existing in an inspection object such as a steel pipe. Further, as the defect shape discrimination method by the ultrasonic flaw detection method, two approach methods are conventionally known. The first approach is to analyze the waveform of the ultrasonic reflected wave from the defect including the property of the defect, for example, to distinguish the defect shape by the frequency analysis and phase analysis of the reflected wave. The second approach mainly focuses on the change in the reflection behavior of the reflected wave due to the defect shape, and attempts to discriminate the defect shape by, for example, the change in the shape of the reflected wave, the peak value, the propagation time, or the like. (Unexamined Japanese Patent Publication No. 61-173152, "Fundamental Study on Defect Identification Method of ERW Steel Pipe Welds by Ultrasonic Waves", Japan Nondestructive Inspection Association
59th Autumn Meeting Lecture Summary P740-741). The present invention belongs to this second approach.

By the way, in the conventional method, the probe is manually scanned, and the change of the reflected wave is classified by the combination of various probe scanning methods to estimate the defect shape. For example, when determining the shape or type (defects, cracks, blowholes, slags, etc.) of defects in the weld, flaw detection on both sides of the defect crossing line sandwiching the weld with a pair of probes,
For each side, a comprehensive evaluation of reflected wave changes due to front-back scanning, pendulum scanning, oscillating scanning, etc., for defects in the probe is performed. Further, even in the case of the electric resistance welded pipe welded portion in which the types of defects that occur are relatively limited, it is possible to reduce the combination of manual scanning methods of the probe, but inefficiency in manual scanning and reflected wave change Qualitative extraction of discriminative characteristic values by reading, subjectivity in combination evaluation of these, and in any procedure, the skill of the inspector greatly depends, and there remains an uncertain factor in the reliability of defect shape discrimination. .

Hereinafter, a conventional method for the defect of the electric resistance welded pipe will be described in detail.

Typical defects that occur in the ERW welded portion include center cracks and hook cracks as shown in FIGS. 3 (a) and 3 (b). In addition to this, FIG. 3 (c)
As shown in (1), the non-metallic inclusions remaining in the pipe base material and the defective cutting portion of the electric resistance weld bead are also detected by ultrasonic waves. in this case,
Considering the use of pipes under internal pressure, center cracks are a serious defect and non-metallic inclusions are harmless. Since the causes of these defects are different, it is necessary to discriminate the type or shape of the defect detected by ultrasonic flaw detection and to promptly feed it back to the welding process to correct the welding condition.

FIG. 4 is a conceptual diagram showing a conventional manual probe scanning method,
For example, there is a case where the final pass / fail judgment is performed as described above by manual re-flaw detection on the defect indication portion by automatic ultrasonic flaw detection. That is, for the defect 2 of the electric resistance welded portion 1, the probe 3
(A) Observe the change in the peak value of the reflected wave with the probe distance (b) Measure the peak value of the reflected wave (c) Measure or observe the beam path at the same peak position. The probe 3 is scanned left and right as needed, and the dimension of the defect 2 in the tube axis direction (indicated defect length) is measured. The above scanning is performed on both sides (the A side and the B side in the figure) sandwiching the electric resistance welded portion 1. The determination is based on the comprehensive evaluation of these scanning results.
It is presumed that if the peak wave heights at the side B and B side flaw detection are almost the same, there is a tendency for center cracking, and if there is a difference between the two, there is a tendency for hook cracking.

(Problems to be Solved by the Invention) However, the conventional defect shape discrimination method by such manual scanning of the probe has the following problems.

(A) Since the reflected wave detection in each manual scanning is mechanical scanning, it takes time, and its inspection accuracy depends on the skill of the inspector (for example, reflected wave peak position detection and peak value reading). Individual error occurs. (B) In extracting characteristic values for defect shape discrimination, some qualitative evaluations such as change of reflected wave shape due to front-back scanning or beam path change at peak value of reflected wave are left. This also largely depends on the skill of the inspector. (C) Experience that the comprehensive evaluation of various characteristic values for defect shape discrimination is limited to the information from the given scan. It is a rule.
In this case, although it is an optimization with given information, it is desirable to have many quantified discrimination characteristic values in order to further improve the accuracy of the judgment. Lack of quantification in extraction and evaluation, and therefore generation of individual error due to skill dependency, impairs the reliability of the discrimination result. In particular, when it comes to discriminating defect shapes during the pipe manufacturing process, there is a limit in the allowable time in terms of distribution balance, so the line operation needs such as quick, accurate, and more information are less than the accuracy of conventional methods. It is clear that it acts on.

The present invention has been made to solve the above problems, and an object thereof is to be able to discriminate the types and shapes of defects existing in an object to be inspected efficiently in a short time and with high reliability. It is an object of the present invention to provide a defect type / shape discrimination method by electronic scanning ultrasonic flaw detection.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the first invention, a pair of array probes are relatively arranged at substantially the same distance position with a defect of an inspection object interposed therebetween, These array probes are switched side by side to perform electronic scanning ultrasonic flaw detection, and the difference in the reflection behavior of each reflected wave from the defect obtained by this electronic scanning ultrasonic flaw detection is extracted to characterize the multiple characteristics. The difference characteristic of the reflection behavior of each reflected wave from the defect obtained by the electronic scanning ultrasonic flaw detection that distinguishes the type of the defect based on this discrimination characteristic value is extracted and characterized. The discrimination characteristic value is calculated, and the type of defect is discriminated based on the discrimination characteristic value. Further, in the second invention, a pair of array probes are arranged at substantially the same distance position across the defect of the inspection object. Relative to each other, and B. Electronic scanning ultrasonic flaw detection is performed by switching the probe on each side, and the difference in the reflection behavior of each reflected wave from the defect obtained by this electronic scanning ultrasonic flaw detection is extracted to distinguish it. A characteristic value is calculated, an evaluation value for shape discrimination is calculated based on the discrimination characteristic value, and the defect shape is discriminated from the correlation obtained from the evaluation value and the actual defect shape.

(Operation) In the first invention, it is possible to discriminate the defect type based on a plurality of discrimination characteristic values that characterize the difference in the reflection behavior of the respective reflected waves obtained by the electronic scanning ultrasonic flaw detection, In the second invention, an evaluation value for shape discrimination is calculated based on a plurality of discrimination characteristic values that characterize the difference in the reflection behavior of the reflected waves obtained by the electronic scanning ultrasonic flaw detection, and the evaluation value The shape of the defect can be discriminated from the correlation with the actual shape of the defect. Therefore, by applying the functions of the electronic scanning ultrasonic flaw detection method effectively and efficiently, and further by applying the logical judgment to the quantified characteristics, the problem of the defect shape discrimination method based on the above-mentioned manual scanning is solved. It is possible to eliminate inefficiency, skill-dependent personal error in accuracy, restriction of judgment accuracy limited to given information, etc., and perform highly reliable discrimination with less human dependence. .

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

FIG. 1 is a conceptual diagram showing an example of a defect type / shape discrimination method by electronic scanning ultrasonic flaw detection of the present invention. In addition, in this example, the case where the present invention is applied to the defect inspection of the electric resistance welded pipe welded portion will be described.

That is, in FIG. 1, when discriminating the type and shape of the defect 6 existing in the electric resistance welded portion 5 of the electric resistance welded pipe 4 which is the object to be inspected, first, the defect 6 of the electric resistance welded portion 5 is sandwiched and the defect 6 is almost the same distance on the transverse line. At a position, a pair of array probes 7A and 7B in which a plurality of transducers are linearly arranged are relatively arranged. Next, with respect to the pair of array probes 7A and 7B, the ultrasonic beam 8A is transmitted by performing known linear scanning by switching linear transmission / reception along each transducer at a flaw detection refraction angle on one side. Then, the defect 6 of the electric seam portion 5 is ultrasonically flaw-detected. Next, the array probe 7A receives the reflected wave reflected by the defect 6 along with the transmission of the ultrasonic beam 8A. Then, from the change in the reflection behavior of the reflected wave from the defect 6 obtained by the electronic scanning ultrasonic flaw detection method, the peak detection position (beam path) of the reflected wave, the peak crest value, and the 1/10 crest value width with respect to the peak waveform ( Discrimination characteristic values such as waveform sharpness evaluation) are extracted. Further, the ultrasonic beam is transmitted only by one transducer group consisting of a predetermined number of transducers in the central portion of the array probe 7A, and the reflected wave from the defect 6 accompanying the transmission of the ultrasonic beam is arrayed. By linearly scanning each transducer forming the probe 7A along the arrangement direction and sequentially switching and receiving, the reflection directivity characteristic of the reflected wave is extracted as a discrimination characteristic value. The above scanning is also performed for the other array probe 7B.

The table shows the extracted discrimination characteristic values for defect shape discrimination, and further an example in which generality is given to the evaluation and adopted as a processing value convenient for the defect shape. That is, as the practical discrimination characteristic value, the difference or correlation coefficient between the discrimination characteristic values at the time of flaw detection on the A side and the B side is used.

FIG. 2 is a diagram showing an example of a behavior corresponding to the defect type of the discrimination characteristic value in the present embodiment. In FIG. 2, the discrimination characteristic values are graduated so as to show hook cracking as they are located on the outer side of the radar chart. The figure (a) corresponds to the hook crack, and the figure (b) corresponds to the center crack, respectively, and as is clear from the figure, the centrifugal tendency of each discrimination characteristic value can be verified with the increase of the hook crack property. Therefore, by comprehensively evaluating these discrimination characteristic values, the type of the defect 6 can be easily determined.

In addition, in the present embodiment, since the determination of the above-mentioned defect type is given a quantitative property and the defect shape (particularly, the hook crack inclination angle) is also estimated, the shape characteristic discrimination is performed by combining the respective discrimination characteristic values. The evaluation value of is calculated according to the following linear correlation equation. Then, the shape of the defect 6 is discriminated from the correlation obtained from the evaluation value and the actual shape of the defect.

Evaluation value (Evaiuation Value) = ΣfiPi Here, Pi is the calculated discrimination characteristic value, and fi is the weighting coefficient.

In this case, there is a problem in selecting how many discrimination characteristic values are selected. That is, if only the type of the defect 6 is determined, the above-mentioned echo height ratio, beam path difference,
The purpose can be achieved by the reflection directivity correlation, but in order to estimate the shape of the defect 6 in more detail, it is desirable to improve the accuracy by using more discrimination characteristic values.

As described above, in this embodiment, the electric resistance welded pipe 4 which is the object to be inspected.
A pair of array probes 7A, 7B are relatively arranged at substantially the same distance position with the defect 6 of the electric-sewing portion 5 sandwiched therebetween, and the array probes 7A, 7B are switched one by one to perform electronic scanning ultrasonic wave. After performing flaw detection, a plurality of discrimination characteristic values characterizing the difference in the reflection behavior of each reflected wave from the defect 6 obtained by this electronic scanning ultrasonic flaw detection are calculated, and based on the discrimination characteristic values, shape discrimination for shape discrimination is performed. The evaluation value is calculated, and the shape of the defect 6 is discriminated from the correlation obtained from the evaluation value and the actual shape of the defect.

Therefore, it is a problem of the defect shape discrimination method based on the combination of various scanning methods in the conventional manual ultrasonic flaw detection, inefficiency, quantitative evaluation, induction of individual error in discrimination accuracy due to the skill of the inspector, It is possible to eliminate instability of judgment accuracy limited to given information, reduce human dependency, and perform efficient and reliable discrimination of defect type and shape in a short time. Become. In particular, this method capable of discriminating the type and shape of defects in the manufacturing line is an extremely effective method for quality control because it allows immediate feedback of process conditions.

In addition, in the above-mentioned embodiment, although the five kinds of discrimination characteristic values shown in the table are described, it goes without saying that the discrimination characteristic values are not limited to these.

Further, in the above embodiment, the case where a linear correlation equation is used as the calculation formula of the evaluation value is described, but the present invention is not limited to this, and it is possible to correspond to the defect shape by the quantitative segmentation of the evaluation value. Other expressions may be used as long as they do.

(Effects of the Invention) As described above, according to the present invention, an electronic scanning ultrasonic flaw detector capable of efficiently discriminating the type and shape of a defect existing in a test object in a short time with high reliability. It is possible to provide a defect type / shape discrimination method by

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a defect type / shape discrimination method by electronic scanning ultrasonic flaw detection of the present invention, and FIG. 2 is an example of a behavior corresponding to a defect type of a discrimination characteristic value in the same embodiment. FIG. 3 is a diagram showing an example of a typical defect occurring in an electric resistance welded pipe weld, and FIG. 4 is a conceptual diagram showing a conventional manual probe scanning method. 4 ... ERW pipe, 5 ... ERW part, 6 ... Defect, 7A, 7B ...
Array probe, 8A, 8B ... Ultrasonic beam.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideo Kosuge 1st Toshiba Town, Fuchu-shi, Tokyo Inside Toshiba Fuchu Plant (72) Inventor Kiyohide Tamaki 1st Toshiba-cho, Fuchu City Tokyo Inside of Fuchu Plant, Toshiba (56) References JP-A-2-114114 (JP, A) JP-A-61-173152 (JP, A)

Claims (2)

[Claims] 1. An oscillator of an array probe having a plurality of oscillators arranged linearly is driven to transmit an ultrasonic beam to an object to be inspected and receive a reflected wave from the ultrasonic beam. In an electronic scanning ultrasonic flaw detection method for flaw detection of an internal defect of the inspection object, in a method of discriminating the type of the defect, a pair of array probes are disposed at substantially the same distance position with the defect of the inspection object interposed therebetween. Are arranged relative to each other, and these array probes are switched one by one to perform electronic scanning ultrasonic flaw detection, and the difference in reflection behavior of each reflected wave from the defect obtained by this electronic scanning ultrasonic flaw detection is extracted. Then, a plurality of discrimination characteristic values that characterize this are calculated, and the defect type is discriminated based on the discrimination characteristic values. The defect type discrimination method by electronic scanning ultrasonic flaw detection is characterized. 2. An array probe having a plurality of transducers arranged linearly is driven to transmit an ultrasonic beam to an object to be inspected and receive a reflected wave from the ultrasonic beam. In the method for discriminating the shape of a defect by electronic scanning ultrasonic flaw detection for detecting a defect existing in the inspected object, a pair of array probes are disposed at substantially the same distance position across the defect of the inspected object. Are arranged relative to each other, and these array probes are switched one by one to perform electronic scanning ultrasonic flaw detection, and the difference in reflection behavior of each reflected wave from the defect obtained by this electronic scanning ultrasonic flaw detection is extracted. Then, a plurality of discrimination characteristic values characterizing this are calculated, and an evaluation value for shape discrimination is calculated based on this discrimination characteristic value, and the defect value is determined from the correlation obtained from the evaluation value and the actual defect shape. That we decided to distinguish the shapes Defect shape discrimination method using the electronic scanning ultrasonic flaw detection to symptoms.