JP5243229B2 - Ultrasonic flaw detection method and probe unit for ultrasonic flaw detector - Google Patents

Description

  The present invention is a method for performing an ultrasonic flaw inspection utilizing the diffraction phenomenon of SV waves, and in particular, inferring the “penetration amount” or “unwelded amount” when fillet welding or partial penetration welding is performed. In particular, the present invention relates to an ultrasonic flaw detection inspection method performed on a welded portion, and a probe unit for an ultrasonic flaw detection device that can be suitably used when performing the method.

  As in the case where a truffle is welded to the deck plate, the end of the upright plate abuts against one side of the main plate, and one corner formed by the end of the upright plate and the main plate. When integrating the main plate and the upright plate by performing fillet welding, etc., it is necessary to evaluate the amount of penetration in the welded part or the size of the unwelded part that can occur in the vicinity of the opposite corner. As a method of this, an oblique flaw detection method using a transverse ultrasonic wave (SV wave, Shear Vertical Wave) has been conventionally performed.

  A general oblique flaw detection method using an SV wave is a method in which an ultrasonic beam is incident in an oblique direction with respect to a flaw detection surface and is propagated into the inspection object. The height of a reflected echo obtained from a predetermined flaw detection position. From this, the size of the unwelded portion and the amount of penetration are estimated. In the oblique angle probe used in this method, the longitudinal wave ultrasonic pulse generated by the transducer is refracted at the flaw detection surface, totally reflected above the critical angle, converted into a transverse wave, and converted. Only the transverse ultrasonic pulse is designed to propagate through the surface to be inspected.

  The refraction angle through which the transverse ultrasonic pulse is transmitted varies depending on the applied material, and is about 35 to 80 ° in the case of steel. And since the reciprocation rate of sound pressure is extremely reduced from around a refraction angle of 80 °, a bevel angle probe for steel is generally a refraction angle of 45 to 70 °. Those having a refraction angle of 80 ° or more where the pressure reciprocation rate is low have been rarely used so far.

Moreover, in the general oblique flaw detection method using SV waves, it is interpreted that the ultrasonic beam does not spread and propagates linearly for convenience because of the necessity of geometrically calculating the reflection source at an unknown position. In addition, when the maximum peak echo is obtained when the probe is set at a certain position, the center axis (sound axis) of the ultrasonic beam emitted from the probe at that position is hit by the reflection source. It is interpreted. For this reason, in the general oblique flaw detection method, it is essential to detect the position of the probe (optimum incident point position) from which the maximum peak echo can be obtained.
JP 2004-333387 A JP 2007-178197 A JP 2007-205959 A

  However, there is a case where the optimal incident point position of the probe cannot be ensured due to the relationship between the thickness of the standing plate and the bead (for example, when the thickness of the standing plate is 6 mm or less). In this case, it is difficult to perform good flaw detection by a general oblique flaw detection method using SV waves. Therefore, when the optimum incident point position of the probe cannot be secured, for example, it is conceivable to use an oblique flaw detection method using an oblique probe having a high refraction angle of 80 ° or more.

  It is known to use a transverse ultrasonic wave (SH wave, Shear Horizontal Wave), a creeping wave, etc. for the oblique refraction inspection method with a high refraction angle, but it is possible to stably obtain a reflection echo from a reflection source. And it is difficult to clearly identify the echo to be evaluated. Furthermore, when the SV wave is applied to an oblique flaw detection method with a high refraction angle, there is a problem that the sound pressure reciprocation rate becomes low as described above.

  The present invention has been made to solve the above-described problems of the prior art, and can be implemented without problems even under conditions that cannot be handled by the conventional general oblique flaw detection method. An object of the present invention is to provide an ultrasonic flaw detection inspection method and a probe unit therefor that can realize the evaluation of the unwelded amount and the like with high accuracy by a simple procedure.

  In the ultrasonic flaw detection inspection method of the present invention, an SV wave is transmitted, a probe whose refraction angle is set within a range of 78 to 88 ° is arranged on the flaw detection surface, and the tip of the probe is connected to the flaw detection surface. The ultrasonic wave is transmitted in a state where it is aligned with the position of the start end of the boundary portion with the thick portion extending upward from the flaw detection surface or within 3 mm from the start end, and proceeds while expanding in the thick portion by the diffraction phenomenon. Using the diffracted wave, a received signal including a reflected echo from a reflection source located above the flaw detection surface is obtained.

This ultrasonic flaw detection inspection method is applied to an object to be inspected that is integrated by bringing one end of a vertical plate into contact with one surface of a main plate and welding to one corner of the end of the vertical plate. , Flaw detection is performed using an ultrasonic flaw detector, and the presence or absence of an unwelded portion in the welded portion of the inspection object is determined from the obtained received signal, or there is an unwelded portion in the welded portion of the inspection object In such a case, it can be used suitably when trying to estimate the unwelded amount or the amount of penetration by performing necessary calculations. Specifically, the probe is placed on the surface of the main plate on the bead side, and ultrasonic waves are transmitted in a state where the tip of the probe is aligned with the position of the start end of the bead or within 3 mm from the start end, When a received signal including a reflected echo of a diffracted wave that travels while expanding in the bead due to diffraction phenomenon is acquired and only one reflected echo of the diffracted wave is included in the received signal, If there are two diffracted wave reflection echoes included in the received signal, it is determined that there are no welds in the welded part of the test object. If there are two reflected echoes of the diffracted wave included in the received signal, the reflected echo displayed at a position far from the base point in the graph is reflected on the back edge of the vertical plate. Identify the source signal and The reflection echo displayed at a position close to is determined as a signal with the innermost part of the unwelded part as the reflection source, and the distance from the ultrasonic wave incident point of the probe to the back surface edge of the standing plate And the reading of the reflected echo displayed on the graph far from the base point in the graph and the reading of the reflected echo displayed on the graph near the base point in the graph Estimate the amount of unwelded or melted.

  In addition, when displaying the received signal including those reflected echoes on the screen, in advance for a standard test piece (having a thick part with a horizontal hole formed in the interior extending above the flaw detection surface). It is preferable to adjust the screen display magnification about the vertical axis with reference to the sound pressure of the reflected echo that transmits ultrasonic waves and uses the horizontal hole as a reflection source.

  Further, in this ultrasonic flaw detection inspection method, a probe unit comprising a transmission probe and a reception probe, wherein the opening angle of the sound axis is in a range of 10 to 30 °. The roof angle is preferably set to any angle within the range of 1 to 10 °.

  According to the ultrasonic inspection method according to the present invention, even if the conventional oblique inspection method using the SV wave cannot perform the inspection well, the inspection is preferably performed. It can be performed. In particular, when applied to a flaw detection inspection or the like for the purpose of evaluating the unwelded amount and the penetration amount of a welded portion, the unwelded amount and the like can be estimated with high accuracy by a simple procedure.

  Also, the probe unit for an ultrasonic flaw detector according to the present invention can obtain an effective reflected echo very efficiently when it is used for the ultrasonic flaw detection inspection method as described above, and tries to evaluate it. Even in the case where the radius of curvature of the reflection source is very small, it is possible to obtain a reception signal that can easily and clearly distinguish the reflected echo and noise visually.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a “method for ultrasonic inspection of welded portions” according to the present invention will be described with reference to the accompanying drawings. In this ultrasonic flaw detection inspection method, a flaw detection inspection is performed on an object to be inspected using an ultrasonic flaw detection apparatus, and the presence or absence of an unwelded portion in a welded portion of the object to be inspected is determined from the obtained reception signal. When there is an unwelded portion, a necessary calculation is performed to estimate the unwelded amount or the amount of penetration.

  FIG. 1 is an explanatory diagram of an ultrasonic flaw detection inspection method for welds according to the first embodiment of the present invention. In this figure, 1 is a main plate, 2 is a standing plate, 3 is a bead, and 4 is a probe of an ultrasonic flaw detector. In the present embodiment, as shown in the drawing, the end of the standing plate 2 is brought into contact with one surface (the upper surface in FIG. 1) of the main plate 1 as an object to be inspected. Of the two corners formed on both sides of the end of the upright plate 2, fillet welding is performed on one of the corners (the left side corner in FIG. 1) to integrate the main plate 1 and the upright plate 2. Is used. In addition, when the to-be-inspected object used here is, for example, a deck plate in which a truffle is welded, the main plate 1 in FIG. 1 corresponds to the deck plate, and the standing plate 2 corresponds to the truffle.

  In the present embodiment, an oblique probe having a high refraction angle, in which an SV wave is transmitted and a refraction angle (incident angle) is set to 80 °, is used as the probe 4.

  Here, the procedure of the ultrasonic inspection method for the welded portion according to the present invention will be described. First, as shown in FIG. 1, the probe 4 is arranged on one surface (surface on the bead 3 side) of the main plate 1, and the tip of the probe 4 is positioned at the position of the start end 3 a of the bead 3 (or (Position within 3 mm from the start end 3a). In this state, ultrasonic waves are transmitted from the probe 4 toward the front (in the direction of the main plate 1 and in the vicinity of the welded portion). Then, the direction of the sound axis 8 of the ultrasonic wave (in this embodiment, the direction of the refraction angle of 80 ° from the incident point P) does not coincide with the position of the reflection source (unwelded part or the like) to be flawed. However, a wave (diffracted wave) that travels while spreading in the bead 3 due to the diffraction phenomenon can be used. By obtaining a reflected echo of this diffracted wave, the flaw detection surface (the surface of the main plate 1 in the present embodiment). Information can also be acquired from a reflection source positioned above the point. Specifically, when an ultrasonic wave is transmitted from the probe 4 in the state shown in FIG. 1, for example, a waveform as shown in FIG. 2 (1) or (2) is received according to the state of the welded portion. A signal is obtained.

  More specifically, when an unwelded portion is not formed in the welded portion of the main plate 1 and the upright plate 2, a signal including only one reflected echo A is received as shown in FIG. Become. On the other hand, when the unwelded portion 5 as shown in FIG. 1 exists in the welded portion of the main plate 1 and the upright plate 2, as shown in FIG. 2 (2), the signal includes two reflected echoes A and B. Will be received. In FIG. 2, the horizontal axis represents time (propagation distance), and the vertical axis represents sound pressure.

  Therefore, as shown in FIG. 2A, when a signal including only one reflected echo A is received, it can be determined that an unwelded portion is not formed in the welded portion of the object to be inspected. . Further, as shown in FIG. 2 (2), when a signal including two reflected echoes A and B is received, it is determined that the unwelded portion 5 exists in the welded portion of the inspection object. be able to.

  When it is determined that the unwelded portion 5 is present in the welded portion (when a signal including two reflected echoes A and B is received), a received signal obtained by executing the above procedure (A signal having a waveform as shown in FIG. 2 (2)), the size of the unwelded portion 5 (the dimension from the back end 2a of the upright plate 2 to the innermost portion 5a of the unwelded portion 5), and the penetration Guess the amount.

  In the inspected object as shown in FIG. 1, when the unwelded portion 5 exists, the received signal includes a reflection echo having the back surface end 2 a of the upright plate 2 as a reflection source and the outermost portion of the unwelded portion 5. The reflection echo which uses the inner part 5a as a reflection source should be included. In the graph of FIG. 2, the horizontal axis represents time (the time from when the ultrasonic wave is transmitted until it is received). If the ultrasonic wave propagation speed is given, the ultrasonic wave propagation distance (incident point). 2), the signal from the reflection source existing at a farther position with respect to the ultrasonic incident point P becomes a position farther from the base point in the graph of FIG. 2 (2). The signal from the reflection source present at a position near the ultrasonic incident point P appears at a position closer to the base point in the graph of FIG. 2 (2).

  Therefore, in the graph of FIG. 2B, the reflection echo A displayed at a position far from the base point uses the back end 2a of the upright plate 2 existing at a position far from the ultrasonic incident point P as a reflection source. The reflected echo B displayed at a position close to the base point can be identified as a signal, and is a signal having the innermost part 5a of the unwelded portion 5 existing near the incident point P as a reflection source. Can be specified.

  The distance Y1 (see FIG. 1) from the ultrasonic incident point P of the probe 4 to the back surface end 2a of the standing plate 2 can be measured using a scale or the like. Since the horizontal axis in the graph of FIG. 2 (2) can also be considered as “distance from the incident point P” as described above, the reflected echo A (standing) shown in the graph of FIG. The reading W1 on the horizontal axis of the signal having the back end 2a of the plate 2 as a reflection source) is considered to be the distance Y1 shown in FIG. 1 (the distance from the incident point P to the back end 2a of the standing plate 2). be able to.

  The relationship between the reading value W1 and the distance Y1, and the horizontal axis reading value of the reflection echo B (the signal having the innermost portion 5a of the unwelded portion 5 as a reflection source) shown in the graph of FIG. A distance Y2 shown in FIG. 1 (a distance from the incident point P to the innermost part 5a of the unwelded portion 5) can be obtained from W2. And the dimension from the back surface edge part 2a of the standing board 2 to the innermost part 5a of the unwelded part 5 can be calculated | required from the difference of the distance Y1 and the distance Y2. Moreover, the dimension from the back surface edge part 2a of the standing board 2 to the innermost part 5a of the unwelded part 5 can also be calculated | required from the relationship between reading value W1 and distance Y1, and the difference of reading value W1 and reading value W2. . And the amount of penetration can be calculated | required from the magnitude | size of the calculated | required unwelded part 5. FIG.

  In the graph of FIG. 2 (2), the reflected echoes A and B and the signal components (noise) of other waveforms can be easily and clearly identified visually. This is because the waveform of the received signal is displayed on the screen after the screen display magnification of the component (sound pressure) on the vertical axis for the received signal is adjusted to an appropriate value. When such screen display magnification adjustment is not performed, the reflected echoes A and B and the signal components of other waveforms cannot always be easily and clearly identified.

  In the present embodiment, the screen display magnification is adjusted by executing the following routine in advance. First, a standard test piece 6 as shown in FIG. 3 is prepared. In this standard test piece 6, a portion (thick portion 6c) having a plate thickness larger than the portion of the flaw detection surface 6a on which the probe 4 is disposed and extending upward from the flaw detection surface 6a is formed. Further, an inclined portion 6b simulating the shape of the bead 3 in the object to be inspected shown in FIG. 1 is formed at the boundary between the flaw detection surface 6a and the thick portion 6c. Further, a lateral hole 7 (hollow) having a diameter of about 3 mm is formed inside the thick portion 6c. The lateral hole 7 is formed so that the height position of the center 7a coincides with the flaw detection surface 6a.

  Next, the probe 4 is placed on the flaw detection surface 6 a of the standard test piece 6. At this time, the tip of the probe 4 is aligned with the position of the starting end of the inclined portion 6b (or a position within 3 mm from the starting end) as shown in FIG. In this state, ultrasonic waves are transmitted from the probe 4 toward the inside of the standard test piece 6. If it does so, the reflective echo which uses the horizontal hole 7 formed in the inside of the thick part 6c as a reflection source will be obtained. Based on the height (sound pressure) of the reflected echo, the screen display magnification is adjusted for the vertical axis. For example, the magnification is adjusted so that the height of the reflection echo having the horizontal hole 7 of the standard test piece 6 as a reflection source is 80% of the vertical axis on the screen, and this is used as the reference sensitivity. By performing the adjustment of the screen display magnification in advance, as shown in the graph of FIG. 2 (2), the reflected echoes A and B and the signal components (noise) of other waveforms can be easily and visually observed. The received signal obtained from the object to be inspected can be displayed on the screen in such a condition that it can be clearly identified.

  In the present embodiment, the probe 4 having a refraction angle of 80 ° is used. However, the probe 4 is not limited to this angle, and is set within a range of 78 to 88 °. Any probe having a high refraction angle can be suitably used in the same manner as the probe 4 of the present embodiment.

  According to the “ultrasonic flaw detection inspection method for welds” of the present embodiment described above, the flaw detection inspection cannot be performed successfully by the conventional oblique angle flaw detection method using the SV wave. Even (for example, when the thickness of the standing plate is 6 mm or less, or when the optimal incident point position of the probe cannot be secured), the flaw detection inspection can be suitably performed. The amount of unwelded and the amount of penetration can be estimated easily and accurately.

  This point will be described in more detail. In the conventional oblique angle flaw detection method using the SV wave, the central axis (sound axis) of the ultrasonic beam output from the probe is the reflection source (the highest point of the unwelded portion). The probe is placed at a position that hits the back (such as the back), and the flaw detection is performed. Based on the height of the reflected echo contained in the received signal (sound pressure level), the amount of unwelded and the size of the flaw Therefore, the position where the probe should be placed is naturally limited based on the position of the reflection source and the refraction angle of the probe used (usually 45 to 70 °). Become.

  Specifically, when a conventional oblique angle flaw detection method using SV waves is used to detect the unwelded portion 5 of the inspection object as shown in FIG. As shown in FIG. 1, the innermost part 5a of the unwelded part 5 exists in a direction with a refraction angle of 90 ° from the surface of the main plate 1, where the probe needs to be arranged at a position corresponding to the inner part 5a. Therefore, when a probe is arranged on the surface of the main plate 1, the sound axis cannot be applied to the innermost part 5 a of the unwelded part 5. For this reason, in the case of the conventional oblique flaw detection method using the SV wave, the probe must be disposed on the surface of the upright plate 2.

  However, in the object to be inspected in FIG. 1, even if a probe is arranged on the surface of the standing plate 2 due to the thin plate thickness of the standing plate 2 and the position where the bead 3 is formed, the refraction angle. The innermost part 5a of the unwelded part 5 cannot be positioned in a direction within 70 °. In order to apply the sound axis of the probe arranged on the surface of the standing plate 2 to the innermost part 5a of the unwelded portion 5, it is necessary to use a probe having a refraction angle of 80 ° or more. The sound axis has a very large angle (an angle close to a right angle) with respect to the extending direction of the unwelded portion 5 (the direction from the back end 2a to the innermost portion 5a of the standing plate 2 and the horizontal direction in FIG. 1). ), And when a conventional general oblique angle flaw detection method is performed using a probe having a refraction angle of 80 ° or more, the sound pressure reciprocation rate significantly decreases. Therefore, good flaw detection cannot be performed.

  The ultrasonic flaw detection method according to the present embodiment is not intended to directly apply the sound axis from the probe to the reflection source, but transmits ultrasonic waves with the sound axis directed to the vicinity of the reflection source to generate a diffracted wave. Is applied to the reflection source, and a reflection echo of the diffracted wave is obtained to evaluate the unwelded portion 5. The reflection source such as the unwelded portion 5 is a flaw detection surface (in this embodiment, the main plate). 1 is greatly different from the conventional oblique flaw detection method in that the flaw detection can be suitably performed even in the case where it is located above the surface 1).

  Further, in the ultrasonic flaw detection method of the present embodiment, the propagation direction of ultrasonic echoes sent from the probe 4 and reaching the unwelded portion 5 (the traveling direction of the diffracted wave reaching the unwelded portion 5) The extension direction of the welded portion 5 is the same (in other words, the probe 4 is arranged on the extension line in the direction matching the extended direction of the unwelded portion 5), and the propagation time of the ultrasonic wave From the difference (the difference between the time until the ultrasonic wave reaches the innermost part 5a of the unwelded portion 5 and the time until it reaches the back surface end 2a of the standing plate 2), the dimensions of the unwelded portion 5 are calculated. It is estimated that the ultrasonic wave is sent so that the sound axis intersects at a very large angle with respect to the extending direction of the unwelded part, and the unwelded part is determined from the height (sound pressure) of the reflected echo. This is very different from the conventional bevel flaw detection method that calculates and estimates the size of the laser.

  As described above, the ultrasonic flaw detection method according to the present embodiment, compared with the conventional oblique flaw detection method, the ultrasonic transmission direction (how to determine the direction of the sound axis), the method of handling the reflected echo in the received signal, The calculation method of the unwelded amount (penetration amount) is completely different. And, it can be suitably applied to an object to be inspected under conditions where conventional flaw detection cannot be satisfactorily carried out, and it is possible to accurately apply the unwelded amount and the amount of penetration with a simple procedure. Can be calculated and estimated.

  Next, as a second embodiment of the present invention, a probe unit for an ultrasonic flaw detector that can be suitably used when carrying out the above-described “ultrasonic flaw inspection method for welds” will be described. As shown in FIG. 4, the probe unit of the present embodiment is configured by two probes (a transmission probe 4a and a reception probe 4b).

  The transmission probe 4a constituting this probe unit emits SV waves and has a high refraction angle set to any angle within the range of 78 to 88 ° (for example, 80 °). It is a bevel probe. When a probe for transmitting SV waves having such a high refraction angle is used, there is a problem that the sound pressure reciprocation rate is substantially lowered, and the probe is described as the first embodiment. The ultrasonic flaw detection inspection method uses a low sound pressure area away from the sound axis, so the echo obtained from the reflection source is weak and is not easily displayed as a clear signal (reflection echo) on the screen. There is a problem. Further, the tip of the unwelded portion 5 serving as a reflection source is considered to have a size of about 0.1 to 2 mm depending on the degree of adhesion of the steel material. However, when the size of the reflection source is extremely small, the reflectance rapidly increases. There is a possibility that the echo will become weaker. Therefore, the probe unit of the present embodiment is devised so that such a weak echo can be efficiently acquired.

  Specifically, in the probe unit in the present embodiment, the opening angle of the sound axis is set to any angle within the range of 10 to 30 ° (for example, 20 °). The “sound axis opening angle” here refers to the sound axis 8a of the transmitting probe 4a and the receiving probe 4b when the probe unit is viewed from above, as shown in FIG. Means the angle R1 at which the sound axis 8b intersects in front of the probe unit. In the case where the probe unit is arranged on a horizontal plane, it can also be defined as an angle at which the projection lines intersect when the sound axis 8a and the sound axis 8b are respectively projected on the horizontal plane.

  Furthermore, in the probe unit of the present embodiment, the roof angle is set to any angle within the range of 1 to 10 ° (for example, 5 °). The “roof angle” mentioned here refers to the vibration plate (ultrasonic vibrator) of the transmission probe 4a and the vibration plate of the reception probe 4b from the normal state. 4b around the central axes C1 and C2 (refer to FIG. 6) in the front-rear direction (see FIG. 6) in opposite directions (in FIG. 6 (1), the left transmission probe 4a is counterclockwise and the right-side reception in the figure). This means the sum of the rotation angles when the probe 4b is rotated in the clockwise direction.

  When “the roof angle is set to 5 °”, the directions of the diaphragms of the probes 4a and 4b and the directions of the sound axes 8a and 8b are the center axes in the front-rear direction of the probes 4a and 4b. It is in a state where it is rotated around C1 and C2 by several degrees (for example, by 2.5 °). However, the housings of the probes 4a and 4b do not rotate. Therefore, as shown in FIG. 6A, the apparent posture and orientation are the same as those of a normal probe (a probe whose roof angle is not changed).

  As shown in FIG. 6 (2), the normal probes 4c and 4d are rotated for each case, and the sound axes 8c and 8d are set to “the roof angle is set to 5 ° as shown in FIG. 6 (1)”. In the case where the sound axes 8a and 8b of the probes 4a and 4b are matched, the angle R2 formed between the adjacent vertical sides of the normal probes 4c and 4d is It becomes equal to the “roof angle” set for the touch elements 4a and 4b, and in this case, “5 °”.

  The probe unit of the present embodiment is related to the configuration as described above, but when used in the "ultrasonic flaw detection inspection method for welds" described as the first embodiment, it is very efficient, An effective reflection echo can be obtained, and even if the radius of curvature of the innermost portion 5a (see FIG. 1) of the unwelded portion 5 is very small, the reflection echo and noise can be easily visually observed. In addition, a received signal that can be clearly identified can be obtained.

Explanatory drawing of the ultrasonic flaw detection inspection method of the welding part which concerns on the 1st Embodiment of this invention. The figure which shows the example of the waveform (graph) of the received signal obtained when an ultrasonic wave is transmitted toward the to-be-inspected object from the probe 4 shown in FIG. The side view of the standard test piece 6 used in the ultrasonic flaw detection inspection method of the welding part which concerns on the 1st Embodiment of this invention. The perspective view of the probe unit for ultrasonic flaw detectors (transmission probe 4a, reception probe 4b) which concerns on the 2nd Embodiment of this invention. The top view of the probe 4a for transmission shown in FIG. 4, and the probe 4b for reception. FIG. 5 is a bird's-eye view from the rear of the transmission probe 4a and the reception probe 4b shown in FIG.

Explanation of symbols

1: Main plate,
2: Standing board,
2a: back end,
3: Bead,
3a: the beginning,
4: Probe,
4a: probe for transmission,
4b: reception probe,
4c, 4d: normal probe,
5: Unwelded part,
5a: innermost part,
6: Standard test piece,
6a: flaw detection surface,
6b: inclined part,
6c: thick part,
7: Horizontal hole,
7a: center,
8, 8a to 8d: sound axis,
A, B: Reflected echo,
C1, C2: central axis,
P: incident point,

Claims (3)

An ultrasonic flaw detector is used for an object to be inspected that is integrated by welding one end of the upright plate with one end of the upright plate contacting one end of the main plate. Performing a flaw detection inspection, from the received signal obtained, to determine the presence or absence of an unwelded portion in the welded portion of the inspection object, or when there is an unwelded portion in the welded portion of the inspection object, In the ultrasonic flaw detection inspection method to estimate the unwelded amount or the amount of penetration by performing the necessary calculations,
An SV wave is transmitted and a probe whose refraction angle is set within a range of 78 to 88 ° is arranged on the surface of the main plate on the bead side,
Sending ultrasonic waves with the tip of the probe aligned with the position of the start end of the bead or within 3 mm from the start end,
Obtain a received signal including a reflected echo of a diffracted wave that travels while spreading in the bead due to diffraction phenomenon ,
The sound pressure of the reflected echo using the horizontal hole as a reflection source, acquired in advance by transmitting an ultrasonic wave to a standard test piece having a thick-walled portion with a horizontal hole formed therein, extending upward from the flaw detection surface. After adjusting the screen display magnification with respect to the vertical axis, the received signal is displayed on a screen with time or distance from the incident point on the horizontal axis,
If there is only one reflected echo of the diffracted wave included in the received signal, it is determined that an unwelded portion is not formed in the welded portion of the inspection object, and is included in the received signal An ultrasonic flaw detection inspection method, wherein when there are two reflected echoes of diffracted waves, it is determined that an unwelded portion is present in a welded portion of an inspection object . When there are two reflected echoes of the diffracted wave included in the received signal, the reflected echo displayed at a position far from the base point in the graph is a signal with the back end of the vertical plate as a reflection source. And specifying the reflected echo displayed at a position close to the base point as a signal having the innermost part of the unwelded portion as a reflection source,
The distance from the ultrasonic incident point of the probe to the back surface end of the standing plate, the reading on the graph of the reflected echo displayed at a position far from the base point in the graph, and the base point in the graph The ultrasonic flaw detection inspection method according to claim 1 , wherein an unwelded amount or a penetration amount of the welded portion is estimated based on a reading value on a graph of a reflected echo displayed at a close position. . It consists of a probe for transmission and a probe for reception, and the opening angle of the sound axis is set to any angle within the range of 10 to 30 °, and the roof angle is any within the range of 1 to 10 °. and performing flaw detection using an ultrasonic flaw detector for probe unit which is set to Kano angle, according to claim 1 or 2 ultrasonic testing method according.

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