JPH0215024B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for identifying defects by determining whether the phase of an ultrasonic echo is in the correct phase or not, and particularly to a method and an apparatus for identifying defects by determining whether or not the phase of an ultrasonic echo is in the correct phase. The present invention relates to a method and apparatus for identifying.

Conventionally, flaw detection methods using ultrasonic waves have been put to practical use, but this method has the disadvantage that the properties of the reflector cannot be reliably identified. That is,
The size and position of the reflector were evaluated based on the amplitude of the ultrasonic echo and the length of the ultrasonic echo reception time (corresponding to the propagation distance). However, even if the ultrasonic echo reception times are the same, the reflectors are not necessarily the same. For example, when the object to be inspected is a steel weld, it is difficult to detect cracks existing around the weld.
This is because the reflector as a crack and the reflector such as weld sag are often close to each other, so it is not possible to easily and reliably identify whether or not a crack exists from an evaluation based only on the position of the reflector. That's not to say there isn't.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a defect identification method and apparatus that can easily and reliably identify cracks even if they exist around the outside of a weld sag.

For this purpose, the present invention discriminates the phase of each time-series ultrasound echo with respect to the pulsed ultrasound every time the pulsed ultrasound is obliquely irradiated into the subject from the probe in the scanning state. At the same time, the maximum amplitude value of each echo is detected as a peak value, and the one corresponding to the local maximum value is extracted from among the peak values obtained corresponding to the scanning position. By being in phase with the ultrasonic wave, crack defects occurring or existing around the outside of the weld sag within the subject can be identified.

In addition, an ultrasonic defect identification device is basically configured to use a probe and an ultrasonic transmitter/receiver to scan an object at an oblique angle using pulsed ultrasonic waves. A phase discrimination circuit that discriminates the phase of each time-series ultrasound echo for the irradiated pulsed ultrasound received by the instrument, and a peak value detection circuit that detects the maximum value of the amplitude from each of these echoes as a peak value. a map data creation circuit that creates map data as a pair of a peak value obtained corresponding to a scanning position from the peak value detection circuit and a discrimination phase for the peak value from the phase discrimination circuit; and a map data creation circuit. A display device is provided that displays map data from the map as one map in a state where it is related to the scanning position.

The present invention will be explained below with reference to FIGS. 1 to 4.

First, the method or its principle according to the present invention will be explained with reference to FIGS. 1a, b and 2 a, b. As shown in Fig. 1a and b, the welded part and its surroundings are the objects to be inspected, but when detecting cracks existing around the outside of the weld sag using ultrasonic waves, the probe 1 is placed outside the object 3. The surface is scanned in the direction of the arrow. Ultrasonic transceiver 2 while scanning is being performed
pulsed ultrasound is applied to the object 3 through the probe 1.
The light is emitted into the interior at a predetermined angle of incidence. Ultrasonic waves are emitted with a certain spread inside the object 3 and are normally reflected by the inner surface of the object 3, but if there is a crack F or weld sag W, the , the ultrasonic waves are also reflected by these cracks F and weld sag W. The reflected ultrasonic waves, that is, the ultrasonic echoes, are received by the ultrasonic transmitter/receiver 2 via the probe 1, but if the incident angle is as shown in the figure, the ultrasonic echoes from the inner surface of the object 3 are received by the ultrasonic transmitter/receiver 2. Since the acoustic wave echoes are rarely reflected in the direction of the probe 1, the reception level of the ultrasonic echoes from the inner surface of the subject 3 is low. On the other hand, since the ultrasonic echoes due to the cracks F and the weld sag W are considerably reflected in one direction of the probe, their reception level becomes high. This means that when a crack F exists, the ultrasonic wave is first reflected by the inner surface of the object 3, as shown in Figure 1a, and then is also reflected by the surface of the crack F, or is it different from this? Follow the opposite route to probe 1
This is because the light will be reflected in the same direction. This is because if there is a weld sag W, the light will be directly reflected at that part, as shown in FIG. 1b, and will be reflected in the direction of the probe 1.

In this way, the ultrasonic echo based on the crack F is the original ultrasonic wave reflected twice, whereas
The ultrasonic echo based on the weld sag W is the original ultrasonic wave reflected once, but this difference appears as a difference in phase. The sound pressure Pr of the reflected ultrasound is calculated from the sound pressure Pi of the incident ultrasound and the acoustic impedances Z ₁ and Z ₂ of the medium, Pr = (Z ₂ −
Z ₁ )・Pi/(Z ₂ + Z ₁ ), but if Z ₂ and Z ₁ are the acoustic impedances of air and iron, respectively, then Z ₂ ≪ _{Z 1} , so each time the ultrasonic wave is reflected The polarity of the sound pressure of the reflected ultrasound is the inverse of the polarity of the sound pressure of the incident ultrasound. That is, basically, the phase of the ultrasonic echo based on the crack F is the same as the original ultrasonic wave, but the phase of the ultrasonic echo based on the weld sag W is reversed.

Figures 2a and b show the RF waveforms of ultrasonic echoes when ultrasonic waves are actually irradiated to crack F and weld sag W, respectively, but in the latter case, the phase is reversed. It can be seen that It can also be seen that in the former case, the peak value is on the positive side of the average value (zero), and in the latter case, it is on the negative side. Subject 3
The ultrasonic echo from the inner surface is phase-wise identical to the ultrasonic echo based on the weld sag W; therefore, by distinguishing the phase of the ultrasonic echo, it is possible to identify whether a crack exists or not. It is about getting.

It is possible to identify the presence of cracks as described above, but if we take into account that the ultrasonic waves emitted from the probe 1 have a certain spread,
It can be said that it is reliable to identify the presence or absence of cracks using ultrasonic echo information over the entire scanning range. The wider the ultrasonic beam spreads, the more various ultrasonic echoes will be received.
This is because, depending on the direction, the ultrasonic waves may be reflected directly from the crack toward the probe.
The same situation applies to weld sag, and it is conceivable that ultrasonic waves that have been reflected twice due to weld sag may be reflected in the direction of the probe. In short, the phase of the reflected ultrasound echo is generally determined by the difference in acoustic impedance at the reflecting part, and the phase of the ultrasound echo that is actually received by the probe is determined by the difference in acoustic impedance at the reflecting part. The phase of the ultrasonic echo is also dependent on the number of reflections of the irradiated ultrasonic wave until the ultrasonic echo is received. Therefore, in general, ultrasonic echoes that are received in chronological order as irradiated ultrasonic waves are reflected at various parts, and the echoes are reflected at various times. This means that the phase of the received ultrasonic echo is determined by which discontinuous acoustic impedance portion the irradiated ultrasound is first reflected at, and how many times it is subsequently reflected by which discontinuous acoustic impedance portion. are doing. However, the propagation and reflection paths of the irradiated ultrasonic waves until they are received as ultrasonic echoes cannot be seen from outside the subject. That is, just because an ultrasonic echo whose phase has not been reversed is received at a certain scanning point does not necessarily mean that a crack exists, and just because an ultrasonic echo whose phase has been reversed is received at a certain scanning point does not necessarily mean that a crack exists. This does not necessarily mean that they do not exist. However, when actually scanning the probe, if a crack exists, a large amplitude ultrasound echo associated with two reflections will be received at a certain scanning position, and if there is no crack, an ultrasound echo associated with one reflection will be received. The presence or absence of cracks can be reliably identified by receiving ultrasonic echoes with large amplitudes. Incidentally, to briefly explain the cracking defect to be detected according to the present invention, this cracking defect is particularly close to the inner surface of the specimen 3 and is located at a welded part, as shown in FIG. 1b. It is said to occur or exist around the outside of the weld sag. Cracks that occur or exist inside the weld are not covered, but this is because the acoustic impedance conditions inside the weld are clearly different from those outside the weld. This is because cracks cannot be easily detected.

FIG. 3 shows a schematic configuration of an apparatus according to the present invention for identifying cracks in this manner. As mentioned above, ultrasonic waves are irradiated from the ultrasound transmitter/receiver 2 to the subject (not shown) via the probe (not shown), and the ultrasound echoes from the subject follow the opposite path to become ultrasonic waves. The ultrasound is received by the ultrasound transmitter/receiver 2, but this device creates a predetermined map from the phase information, peak value information, and scanning position information (probe position information) of the ultrasound echoes. This is what we are trying to display.

That is, received by the ultrasonic transceiver 2,
Each of the time-series ultrasound echoes for the irradiated ultrasound is given to a phase discrimination circuit 4 and a peak value detection circuit 5, where the phase is discriminated and the peak value of its amplitude is detected. The discriminated phase information and detected peak value information are given to a map data creation circuit 6 along with scanning position information from the probe or scanning control circuit, and phase/peak data for the scanning position is created. That is, the map data creation circuit 6 extracts, from among the ultrasonic echoes received in time series at the scanning position,
Phase information about the ultrasonic echo with the maximum amplitude and its maximum amplitude value (peak value) are extracted and held. The display device 7 displays phase and peak data for the scanning position that is created every time a scan is performed.
The map is output to the map and displayed as a map as shown in FIG. CRT as display device 7
General devices such as , graphic display, and XY plotter can be used, but if you want to display the peak value depending on whether the phase is reversed or
It is possible to know with certainty whether the ultrasonic echoes received from the map are due to cracks or weld sag. Incidentally, the map shown in Figure 4 is for the case of cracking. Even in the case of a crack, the phase of the ultrasonic echo may be reversed depending on the scanning position, but the peak value of the amplitude in this case will be smaller than the peak value at other scanning positions. Similarly, in the case of weld sagging, the phase of the ultrasonic echo may not be reversed depending on the scanning position.
The peak value of the amplitude in that case is smaller than the peak value at other scanning positions. Therefore, whether the map is due to cracking or not is determined based on the phase information at the largest peak value.

However, if we assume that there is one or more cracks around the weld, the map will have a complex shape with multiple maximum points regarding the peak value, but if it includes two or more maximum points, the phase at each maximum point will be It is only necessary to identify the presence or absence of cracks from the information.

As explained above, the present invention distinguishes the phase of each time-series ultrasound echo with respect to the pulsed ultrasound every time pulsed ultrasound is obliquely irradiated into the subject from the probe in the scanning state. At the same time, the maximum amplitude value of each echo is detected as a peak value, and the one corresponding to the maximum value is extracted from among the peak values obtained corresponding to the scanning position, and the discrimination phase for the maximum value is determined by the irradiation pulse. By being in phase with the phase of the ultrasonic waves, crack defects occurring or existing around the outside of the weld sag within the subject can be identified. Therefore, in the case of the present invention, even if there are cracks around the weld, the cracks can be easily and reliably identified by distinguishing them from weld sag, which greatly facilitates maintenance of structures and product quality control. It has the effect of being improved.

[Brief explanation of drawings]

Figures 1a and b are diagrams for explaining how ultrasound is reflected by cracks and weld sag, respectively. Figures 2a and b are diagrams showing RF waveforms of ultrasonic echoes from cracks and weld sag, respectively. , Figure 3 is
A diagram showing a schematic configuration of an example of a device according to the present invention,
FIG. 4 is a diagram showing an example of a map displayed by the device. 1... Probe, 2... Ultrasonic transceiver, 3...
Test object, 4... Phase discrimination circuit, 5... Peak value detection circuit, 6... Map data creation circuit, 7... Display device.

Claims (1)

[Claims] 1. Each time pulsed ultrasound is obliquely irradiated into the subject from a probe in a scanning state, the phase of each time-series ultrasound echo with respect to the pulsed ultrasound is discriminated, and , detect the maximum value of the amplitude from each of the echoes as a peak value, extract the one corresponding to the local maximum value from among the peak values obtained corresponding to the scanning position, and furthermore, if the discrimination phase for the maximum value exceeds the irradiation pulse-like 1. A defect identification method using ultrasonic waves, characterized in that a crack defect occurring or existing around the outside of a weld sag within the object is identified by being in phase with the phase of a sound wave. 2. The probe and the ultrasonic transmitter/receiver scan the object at an oblique angle using pulsed ultrasound, and the time-series ultrasound echoes for the irradiated pulsed ultrasound received by the ultrasound transmitter/receiver are A phase discrimination circuit that discriminates each phase, a peak value detection circuit that detects the maximum value of amplitude from each of the echoes as a peak value, and a peak value obtained from the peak value detection circuit corresponding to the scanning position. and a discrimination phase for the peak value from the phase discrimination circuit as a pair of map data, and a display that displays the map data from the generation circuit as one map in relation to the scanning position. What is claimed is: 1. An ultrasonic defect identification device characterized by a configuration comprising: