Ultrasonic inspection method and device and program

Abstract

To enable determination of the presence or absence of a defect such as a crack and the like present in an inner surface of an inspection object in an ultrasonic inspection method and device and program.SOLUTION: An ultrasonography method has the steps of: adjusting a convergence point of an ultrasonic signal which is transmitted from a probe to an inspection object, to a position deviated in a plate thickness direction with respect to an inner surface of the inspection object; transmitting the ultrasonic signal toward the inspection object from the probe, and oscillating a transmission direction of the ultrasonic signal within a preset prescribed angle range; receiving a secondary creeping wave of the ultrasonic signal reflected from the inspection object by the prove for each specified angle in the angle range to acquire the creeping wave; receiving a mode conversion wave of the ultrasonic signal reflected from the inspection object for each specified angle in the angle range to acquire the mode conversion wave; and determining presence or absence of a defect of an inner surface of the inspection object on the basis of the secondary creeping wave and mode conversion wave.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an ultrasonic inspection method, apparatus, and program. [Background technology]

[0002] The ultrasonic inspection method is a method of scanning an object to be inspected with ultrasonic signals to detect inner surface defects of the object to be inspected. In this case, it is common to use a secondary creeping wave method to detect inner surface defects of the object to be inspected. It is also considered to use a mode conversion wave method in combination with the secondary creeping wave method. For example, a technology described in Patent Document 1 is an example of such an ultrasonic inspection method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-8844 A Summary of the Invention [Problem to be solved by the invention]

[0004] The secondary creeping wave method and the mode converted wave method are generally effective when the depth of the defect is 20% or more of the thickness of the object to be inspected, and it is difficult to detect small cracks. In addition, the mode converted wave method detects not only defects such as cracks on the inner surface of the object to be inspected, but also shape changes on the back surface of the object to be inspected, making it difficult to determine whether or not there are defects such as cracks.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide an ultrasonic inspection method, apparatus, and program that make it possible to determine the presence or absence of defects such as cracks on the inner surface of an object to be inspected. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the ultrasonic inspection method disclosed herein includes the steps of adjusting the focal point of an ultrasonic signal transmitted from a probe to an object to be inspected to a position shifted in the plate thickness direction relative to the inner surface of the object to be inspected; transmitting an ultrasonic signal from the probe toward the object to be inspected and oscillating the transmission direction of the ultrasonic signal within a predetermined angular range; receiving and acquiring with the probe secondary creeping waves of the ultrasonic signal reflected from the object to be inspected for each specified angle in the angular range; receiving and acquiring with the probe mode conversion waves of the ultrasonic signal reflected from the object to be inspected for each specified angle in the angular range; and determining the presence or absence of defects on the inner surface of the object to be inspected based on the secondary creeping waves and the mode conversion waves.

[0007] In addition, the ultrasonic inspection device disclosed herein includes a probe that transmits an ultrasonic signal to an object to be inspected and receives an ultrasonic signal reflected from the object to be inspected, and a calculation processing unit that acquires data obtained by scanning the object to be inspected with an ultrasonic signal using the probe and processes and synthesizes the data of the acquired ultrasonic signal, wherein the calculation processing unit adjusts a focal point of the ultrasonic signal to be transmitted from the probe to the object to be inspected to a position shifted in the plate thickness direction relative to the inner surface of the object to be inspected, transmits an ultrasonic signal from the probe toward the object to be inspected while oscillating the transmission direction of the ultrasonic signal within a predetermined angular range that is set in advance, receives and collects secondary creeping waves of the ultrasonic signal reflected from the object to be inspected at each specified angle in the angular range with the probe, receives and acquires mode converted waves of the ultrasonic signal reflected from the object to be inspected at each specified angle in the angular range with the probe, and judges the presence or absence of defects on the inner surface of the object to be inspected based on the secondary creeping waves and the mode converted waves.

[0008] In addition, the program disclosed herein causes a computer to execute the following steps: adjusting the focal point of an ultrasonic signal transmitted from a probe to an object to be inspected to a position shifted in the thickness direction relative to the inner surface of the object to be inspected; transmitting an ultrasonic signal from the probe toward the object to be inspected and oscillating the transmission direction of the ultrasonic signal within a predetermined angular range; receiving and collecting with the probe secondary creeping waves of the ultrasonic signal reflected from the object to be inspected for each specified angle in the angular range; receiving and acquiring with the probe mode converted waves of the ultrasonic signal reflected from the object to be inspected for each specified angle in the angular range; and determining whether or not there is a defect on the inner surface of the object to be inspected based on the secondary creeping waves and the mode converted waves. Effect of the Invention

[0009] According to the ultrasonic inspection method, apparatus, and program disclosed herein, it is possible to determine the presence or absence of defects such as cracks on the inner surface of an object to be inspected. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of an ultrasonic inspection device according to this embodiment. [Diagram 2] FIG. 2 is an explanatory diagram showing a flaw detection inspection method using a secondary creeping wave and a mode conversion wave. [Diagram 3] FIG. 3 is a schematic diagram for explaining the ultrasonic inspection method of the present embodiment. [Figure 4] FIG. 4 is a comparison diagram showing ultrasonic inspection results between the conventional method and the present embodiment. [Diagram 5] FIG. 5 is a flowchart showing the ultrasonic inspection method of this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes a configuration in which each embodiment is combined. In addition, the components in the embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range.

[0012] <Ultrasonic inspection equipment> FIG. 1 is a block diagram showing a schematic configuration of an ultrasonic inspection device according to this embodiment.

[0013] As shown in Fig. 1, the object to be inspected is a pipe 1. However, the object to be inspected is not limited to the pipe 1. The ultrasonic inspection device 100 is an inspection device (flaw detection device) for detecting (detecting flaws) cracks, which are inner surface defects, of the pipe 1, which is the object to be inspected. The ultrasonic inspection device 100 includes a flaw detector 10, a calculation unit 20, and an operation / display unit 30.

[0014] <Flaw detector> The flaw detector 10 has a linear array probe (probe) 11, a pulser 12, a receiver 13, a data storage unit 14, and a control element switching unit 15. The linear array probe 11 has a plurality (N pieces) of transducers (elements) 110 (see FIG. 3), which will be described later. The plurality of transducers 110 are arranged in a linear array. The transducer 110 is connected to the pulser 12 as a transmitter and to the receiver 13 as a receiver. Between the transducer 110 and the piping 1, a medium 2 capable of propagating an ultrasonic signal S is filled. The transducer 110 transmits the ultrasonic signal S transmitted from the pulser 12 to the piping 1 via the medium 2. The transducer 110 also receives the ultrasonic signal S reflected from the piping 1 via the medium 2, and transmits it to the receiver 13. The ultrasonic signal S transmitted to the receiver 13 is stored in the data storage unit 14. The control element switching unit 15 switches, among the multiple transducers 110, the transducer 110 that causes the pulsar 12 to emit the ultrasonic signal S, in accordance with an instruction from the control unit 21 of the calculation unit 20.

[0015] The medium 2 filling the gap between the transducer 110 and the pipe 1 may be any material that can propagate ultrasonic waves. For example, ultrasonic transmission gel, water, etc. can be used as the medium 2. When ultrasonic transmission gel is used as the medium 2, by pressing a pocket of the ultrasonic transmission gel against the surface of the pipe 1 with an appropriate force, the ultrasonic transmission gel deforms according to the shape of the pipe 1 even if the surface of the pipe 1 has a complex shape. Therefore, the medium 2 can fill the gap between the pipe 1 and the linear array probe 11 without leaving any gaps. This allows the ultrasonic signal S to propagate between the linear array probe 11 and the pipe 1 via the medium 2.

[0016] <Calculation part> The calculation unit 20 is an arithmetic processing device provided separately from the flaw detector 10 and connected to the flaw detector 10. The calculation unit 20 is, for example, an externally connected personal computer. The calculation unit 20 may be provided integrally with the flaw detector 10. The calculation unit 20 has a control unit 21, a storage unit 22, and an arithmetic processing unit 23.

[0017] <Control Unit> The control unit 21 is an arithmetic processing device constituted by, for example, a CPU (Central Processing Unit). The control unit 21 is connected to the control element switching unit 15 of the flaw detector 10, the storage unit 22, the arithmetic processing unit 23, and the inspection condition setting unit 32 of the operation and display unit 30. The control unit 21 loads a program stored in the storage unit 22 into a memory and executes instructions included in the program. More specifically, the control unit 21 acquires information on the inspection conditions set by the user from the inspection condition setting unit 32. Based on the acquired information on the inspection conditions, the control unit 21 controls the control element switching unit 15 to sequentially transmit ultrasonic signals S from each transducer 110 of the linear array probe 11 to the pipe 1, and collects data on the ultrasonic signals S reflected from the pipe 1.

[0018] <Data collection method> A phased array ultrasonic inspection method is used for collecting data on the ultrasonic signals S. This is a data collection method in which ultrasonic signals S, which are simultaneously emitted from a plurality of transducers 110 and reflected from the pipe 1, are received by all of the transducers 110. More specifically, the control unit 21 causes all of the transducers 110 of the linear array probe 11 to transmit ultrasonic signals S to the pipe 1. Then, a composite wave formed by combining the ultrasonic signals S from all of the transducers 110 reaches the pipe 1, and the ultrasonic signals S reflected from the pipe 1 are received by all of the transducers 110 and stored in the data storage unit 14 via the receiver 13.

[0019] <Storage section> The storage unit 22 stores data (programs) required for various processes in the ultrasonic inspection device 100. The storage unit 22 is, for example, a semiconductor memory element such as a random access memory (RAM), a read only memory (ROM), or a flash memory, or a storage device such as a hard disk or an optical disk. The storage unit 22 is connected to the data storage unit 14 of the flaw detector 10 and the arithmetic processing unit 23. The storage unit 22 receives and stores collected data of the ultrasonic signal S from the data storage unit 14. The storage unit 22 transmits the stored data of the ultrasonic signal S to these in response to a command from the arithmetic processing unit 23.

[0020] <Calculation processing unit> The calculation processing unit 23 is, for example, a calculation processing device configured by a CPU. The calculation processing unit 23 is connected to the storage unit 22, the calculation condition setting unit 33 of the operation / display unit 30, and the calculation result display unit 31. The calculation processing unit 23 loads a program stored in the storage unit 22 into a memory and executes instructions included in the program. The calculation processing unit 23 obtains information on calculation conditions that are set based on the inspection conditions from the calculation condition setting unit 33.

[0021] Moreover, the arithmetic processing unit 23 receives the collected data of the ultrasound signal S from the storage unit 22.

[0022] (Operation / display section) The operation and display unit 30 is a device having both a display function for displaying the inspection results and an input operation function as a user interface. For example, a touch panel type display can be used as the operation and display unit 30. The operation and display unit 30 is provided separately from the flaw detector 10 and connected to the calculation unit 20. The operation and display unit 30 may be provided integrally with the flaw detector 10. Furthermore, the operation and display unit 30 is not limited to a touch panel type display, and may be provided separately from the display function for displaying the inspection results and the operation function as a user interface.

[0023] The operation / display unit 30 has a calculation result display unit 31, an inspection condition setting unit 32, and a calculation condition setting unit 33. The calculation result display unit 31 is connected to the calculation processing unit 23 of the calculation unit 20. The calculation result display unit 31 displays the calculation results received from the calculation processing unit 23, i.e., the drawing results of the interior of the pipe 1, to the user.

[0024] The inspection condition setting unit 32 is a user interface through which the user sets the inspection conditions. The inspection conditions include, for example, information such as the arrangement of the multiple transducers 110 of the linear array probe 11 and the type of the medium 2. The inspection conditions also include, for example, information such as the fact that the object to be inspected is a pipe 1, the size (wall thickness) of the pipe 1, and the type of material constituting the pipe 1.

[0025] The calculation condition setting unit 33 sets calculation conditions based on the inspection conditions input by the user, and transmits them to the calculation processing unit 23 of the calculation unit 20. The calculation conditions are various conditions required when the calculation processing unit 23 performs calculation processing according to the information of the inspection conditions.

[0026] <Flaw detection method using secondary creeping waves and mode conversion waves> FIG. 2 is an explanatory diagram showing a flaw detection inspection method using a secondary creeping wave and a mode conversion wave.

[0027] As shown in Fig. 2, the pipe 1, which is the object to be inspected, has a surface 1a and an inner surface (rear surface) 1b, and the position to be inspected is, for example, a welded portion. In the second-order creeping wave method, the ultrasonic signal S transmitted from the linear array probe 11 travels in the thickness direction from the surface 1a of the pipe 1 as a shear wave Sa, is reflected parallel to the inner surface 1b to generate a longitudinal wave Sb, and the longitudinal wave Sb is reflected by a defect C as a shear wave Sc, which reaches the linear array probe 11 and is detected. On the other hand, in the mode conversion wave method, the ultrasonic signal S transmitted from the linear array probe 11 travels in the thickness direction from the surface 1a of the pipe 1 as a shear wave Sd, is reflected by the inner surface 1b to become a mode-converted longitudinal wave Se, and the longitudinal wave Se is reflected by the defect C as a longitudinal wave Sf, which reaches the linear array probe 11 and is detected.

[0028] <Ultrasonic inspection method> FIG. 3 is a schematic diagram for explaining the ultrasonic inspection method of the present embodiment.

[0029] As shown in Figure 3, the ultrasonic inspection method of this embodiment includes the steps of adjusting the focal point P of ultrasonic signals transmitted from multiple transducers 110 to the pipe 1 to a position shifted in the thickness direction relative to the inner surface 1b of the pipe 1, transmitting ultrasonic signals from the transducers 110 toward the pipe 1 and oscillating the transmission direction of the ultrasonic signals within a predetermined angular range, receiving and acquiring secondary creeping waves of the ultrasonic signals reflected from the pipe 1 at each specified angle in the angular range by the transducer 110, receiving and acquiring mode conversion waves of the ultrasonic signals reflected from the pipe 1 at each specified angle in the angular range by the transducer 110, and determining the presence or absence of defects on the inner surface 1b of the object to be inspected based on the secondary creeping waves and the mode conversion waves.

[0030] However, the order of the step of adjusting the focal point P of the ultrasonic signal, the step of transmitting the ultrasonic signal and oscillating the transmission direction of the ultrasonic signal, the step of acquiring a secondary creeping wave of the ultrasonic signal, and the step of acquiring a mode-converted wave of the ultrasonic signal is not limited. For example, the step of acquiring a secondary creeping wave and the step of acquiring a mode-converted wave may be reversed. Also, the step of adjusting the focal point P of the ultrasonic signal and the step of transmitting the ultrasonic signal and oscillating the transmission direction may be reversed.

[0031] Here, the process for implementing the ultrasonic inspection method by the ultrasonic inspection device 100 of this embodiment is performed by the control unit 21 and the calculation processing unit 23 of the calculation unit 20 executing a program stored in the storage unit 22. This process is performed with the flaw detector 10 positioned at a predetermined position on the surface 1a of the pipe 1. In the following description, the surface 1a and the inner surface 1b of the pipe 1 are appropriately referred to as the "geometry part" of the pipe 1. Note that, when the object to be inspected is different from the pipe 1 and does not have the inner surface 1b, the geometry part means all surface parts within the inspection range, or the surface parts and the back surface parts opposite the surface parts.

[0032] The linear array probe 11 has a plurality (N pieces) of transducers 110. The plurality of transducers 110 are arranged in a linear array. The transducers 110 transmit ultrasonic signals toward the surface 1a of the pipe 1 at a predetermined transmission angle α. The transmission angle α is an angle with respect to the wall thickness direction of the pipe 1, and is preferably, for example, approximately 30 degrees. The frequency of the ultrasonic signals transmitted by the transducers 110 is preferably a low frequency (for example, 2 MHz or less). It is also desirable that the length of the transducers 110 in the linear array probe 11 in the arrangement direction be as large as possible.

[0033] Furthermore, when the transducer 110 transmits an ultrasonic signal toward the surface 1a of the pipe 1, the transmission direction of the ultrasonic signal is oscillated in a preset predetermined angle range β on both sides of a range including a predetermined transmission angle α. That is, a sector scan is performed by the linear array probe 11. The angle range β is preferably, for example, from 0 degrees to 80 degrees with respect to the wall thickness direction of the pipe 1, but is not limited to this angle range.

[0034] Furthermore, when the transducers 110 transmit ultrasonic signals toward the surface 1a of the pipe 1, a focal point P of the ultrasonic signals transmitted from the multiple transducers 110 to the pipe 1 is adjusted to a position shifted in the plate thickness direction relative to the inner surface 1b of the pipe 1. It is preferable that the focal point P is shifted in the plate thickness direction relative to the inner surface 1b of the pipe 1 by a range of more than 0% to 20% of the plate thickness t.

[0035] That is, when the transducer 110 transmits an ultrasonic signal toward the surface 1a of the pipe 1, the focal point P of the ultrasonic signal is generally adjusted to be located on the inner surface 1b where defects such as cracks are to be detected. In this embodiment, when the transducer 110 transmits an ultrasonic signal toward the surface 1a of the pipe 1, the focal point P of the ultrasonic signal is adjusted to a position shifted by a distance L in the plate thickness direction from the inner surface 1b of the pipe 1. The distance L is the distance from the surface 1a of the pipe 1 in the plate thickness direction of the pipe 1, and is, for example, in the range of more than 0% to 20% of the plate thickness t. When the focal point P of the ultrasonic signal is adjusted to a position shifted from the inner surface 1b of the pipe 1, the area of ​​the ultrasonic signal that reaches the inner surface 1b of the pipe 1 is expanded, and the flaw detection range is increased.

[0036] Furthermore, when the transducer 110 transmits an ultrasonic signal toward the pipe 1 and the transmission direction of the ultrasonic signal is oscillated within a predetermined angle range β, the distance between the surface 1a of the pipe 1 and the focal point P of the ultrasonic signal is adjusted so as to be kept constant without fluctuating. In other words, if the position of the focal point P of the ultrasonic signal is fixed, when the transmission direction of the ultrasonic signal is oscillated from 0 degrees to 80 degrees, the focal point P of the ultrasonic signal will fluctuate in the thickness direction of the pipe 1. Therefore, when the transmission direction of the ultrasonic signal is oscillated from 0 degrees to 80 degrees, the position of the focal point P of the ultrasonic signal is adjusted so that the distance L between the surface 1a of the pipe 1 and the focal point P of the ultrasonic signal is constant.

[0037] In this embodiment, the direction in which the focal point P of the ultrasonic signal is shifted in the thickness direction relative to the inner surface 1b of the pipe 1 is the direction in which the transducer 110 approaches the inner surface 1b of the pipe 1.

[0038] After adjusting the focal point P of the ultrasonic signal to a position shifted from the inner surface 1b of the pipe 1, ultrasonic signals are transmitted from all transducers 110 toward the pipe 1, and the transmission direction of the ultrasonic signals is oscillated within a predetermined angle range β. At this time, the linear array probe 11 receives secondary creeping waves and mode-converted waves of the ultrasonic signals reflected from the pipe 1 at every specified angle (e.g., 1 degree) within the angle range β. In this manner, the transmission direction of the ultrasonic signal is oscillated up to the angle range β=80 degrees, and the secondary creeping waves and mode-converted waves of the ultrasonic signal are received.

[0039] The received waveform is then checked by sector scanning to confirm the detection of secondary creeping waves and mode conversion waves.

[0040] In this embodiment, an ultrasonic signal is transmitted from the linear array probe 11 toward the pipe 1, and the position of the focal point P of the ultrasonic signal is adjusted when the transmission direction of the ultrasonic signal is oscillated within a predetermined angle range β. That is, at a predetermined oscillation position within the angle range β, a secondary creeping wave and a mode converted wave are obtained when the focal point P of the ultrasonic signal is located on the inner surface 1b of the pipe 1, and a secondary creeping wave and a mode converted wave are obtained when the focal point P of the ultrasonic signal is shifted from the inner surface 1b of the pipe 1 in the plate thickness direction.

[0041] It is effective for evaluation to simultaneously display an image including the shape and interior of the pipe 1 drawn based on the secondary creeping wave and mode conversion wave when the focal point P is located on the inner surface 1b of the pipe 1, and an image including the shape and interior of the pipe 1 drawn based on the secondary creeping wave and mode conversion wave when the focal point P is shifted in the plate thickness direction relative to the inner surface 1b of the pipe 1.

[0042] <Comparison image> FIG. 4 is a comparison diagram showing ultrasonic inspection results between the conventional method and the present embodiment.

[0043] Fig. 4 shows sector scan display images based on the acquired multiple secondary creeping waves and mode converted waves. As shown in Fig. 4, the image (a) is a sector scan display image of the secondary creeping waves and mode converted waves of the ultrasonic signal acquired when the focal point P of the ultrasonic signal is adjusted to the position of the inner surface 1b of the pipe 1. The image (b) is a sector scan display image of the secondary creeping waves and mode converted waves of the ultrasonic signal acquired when the focal point P of the ultrasonic signal is adjusted to a position shifted from the inner surface 1b of the pipe 1. The X direction is the arrangement direction of the transducers 110, and the Y direction is the wall thickness direction of the pipe 1.

[0044] In the image in Fig. 4(a), the focal point P of the ultrasonic signal is located on the inner surface 1b of the pipe 1, so the secondary creeping wave A is displayed clearly, but the mode converted wave B is unclear. On the other hand, in the image in Fig. 4(b), the focal point P of the ultrasonic signal is located at a position shifted from the inner surface 1b of the pipe 1, so the inspection range is expanded and the secondary creeping wave A and the mode converted wave B are detected, although they are blurred. Therefore, the mode converted wave can be detected even in small cracks in the pipe 1.

[0045] <Ultrasonic Inspection Method Procedure> FIG. 5 is a flowchart showing the ultrasonic inspection method of this embodiment.

[0046] 3 and 5, in step S11, the position of a focal point P of an ultrasonic signal transmitted from the linear array probe 11 to the pipe 1 is adjusted with respect to the inner surface 1b of the pipe 1. First, the focal point P of the ultrasonic signal is adjusted to the position of the inner surface 1b of the pipe 1. In step S12, an ultrasonic signal is transmitted from the linear array probe 11 toward the pipe 1.

[0047] In step S13, a secondary creeping wave of the ultrasonic signal reflected from the pipe 1 is received and acquired by the transducer 110. In step S14, a mode-converted wave of the ultrasonic signal reflected from the pipe 1 is received and acquired by the transducer 110.

[0048] In step S15, the focal point P of the ultrasonic signal transmitted from the linear array probe 11 to the pipe 1 is adjusted to a position shifted with respect to the inner surface 1b of the pipe 1. In step S16, the ultrasonic signal is transmitted from the linear array probe 11 toward the pipe 1.

[0049] In step S17, a secondary creeping wave of the ultrasonic signal reflected from the pipe 1 is received and acquired by the transducer 110. In step S18, a mode-converted wave of the ultrasonic signal reflected from the pipe 1 is received and acquired by the transducer 110.

[0050] In step S19, when the linear array probe 11 acquires the secondary creeping wave and the mode conversion wave by sector scanning, an image is displayed for determining the presence or absence of defects on the inner surface 1b of the pipe 1 based on the secondary creeping wave and the mode conversion wave.

[0051] [Effects of this embodiment] The ultrasonic inspection method of the first embodiment includes the steps of adjusting a focal point P of an ultrasonic signal transmitted from a linear array probe 11 (transducer) to a pipe (object to be inspected) 1 to a position shifted in the thickness direction relative to the inner surface 1b of the pipe 1, transmitting an ultrasonic signal from the linear array probe 11 toward the pipe 1 and oscillating the transmission direction of the ultrasonic signal within a predetermined angle range β, receiving and acquiring secondary creeping waves of the ultrasonic signal reflected from the pipe 1 at each specified angle in the angle range β with the linear array probe 11, receiving and acquiring mode conversion waves of the ultrasonic signal reflected from the pipe 1 at each specified angle in the angle range β with the linear array probe 11, and determining the presence or absence of defects in the inner surface 1b of the pipe 1 based on the secondary creeping waves and the mode conversion waves.

[0052] According to the ultrasonic inspection method of the first aspect, the focal point P of the ultrasonic signal from the linear array probe 11 is shifted from the inner surface 1b of the pipe 1, and the transmission direction of the ultrasonic signal is oscillated, so that the ultrasonic flaw detection range is widened, and not only the secondary creeping wave but also the mode conversion wave can be appropriately detected, and even small cracks on the inner surface 1b of the pipe 1 can be detected. As a result, the presence or absence of defects such as cracks on the inner surface 1b of the pipe (inspection object) 1 can be determined.

[0053] The ultrasonic inspection method according to the second aspect is the ultrasonic inspection method according to the first aspect, and further includes adjusting the transmission direction of the ultrasonic signal so that the distance between the surface 1a of the pipe 1 and the focal point P of the ultrasonic signal does not vary when the transmission direction of the ultrasonic signal is oscillated within the angle range β. This makes the distance of the focal point P of the ultrasonic signal relative to the surface 1a of the pipe 1 constant, and allows the mode conversion wave to be properly detected.

[0054] The ultrasonic inspection method according to the third aspect is the ultrasonic inspection method according to the first or second aspect, and further, the focal point P is shifted in the thickness direction by more than 0% and not more than 20% of the plate thickness t with respect to the inner surface 1b of the pipe 1. This makes it possible to appropriately detect the mode conversion wave.

[0055] The ultrasonic inspection method according to the fourth aspect is the ultrasonic inspection method according to any one of the first to third aspects, and further acquires, for each specified angle in the angle range β, a secondary creeping wave and a mode converted wave when the focal point P is located on the inner surface 1b of the pipe 1, and acquires a secondary creeping wave and a mode converted wave when the focal point P is shifted in the plate thickness direction relative to the inner surface 1b of the pipe 1. This makes it possible to determine the presence or absence of a crack.

[0056] The ultrasonic inspection method according to the fifth aspect is the ultrasonic inspection method according to the fourth aspect, and further displays an image displayed based on the secondary creeping wave and the mode converted wave when the focal point P is located on the inner surface 1b of the pipe 1, and an image displayed based on the secondary creeping wave and the mode converted wave when the focal point P is located offset in the plate thickness direction with respect to the inner surface 1b of the pipe 1. This makes it possible to determine that there is a crack from the secondary creeping wave and the mode converted wave when the focal point P is located offset from the inner surface 1b of the pipe 1. In this case, it is effective for evaluation to simultaneously display an image displayed based on the secondary creeping wave and the mode converted wave when the focal point P is located on the inner surface 1b of the pipe 1, and an image displayed based on the secondary creeping wave and the mode converted wave when the focal point P is located offset in the plate thickness direction with respect to the inner surface 1b of the pipe 1.

[0057] The ultrasonic inspection device of the sixth aspect includes a linear array probe 11 that transmits ultrasonic signals to a pipe (object to be inspected) 1 and receives ultrasonic signals reflected from the pipe 1, and an arithmetic processing unit 23 that performs processing based on data acquired using the linear array probe 11. The arithmetic processing unit 23 adjusts a focal point P of the ultrasonic signal transmitted from the linear array probe 11 to the pipe 1 to a position shifted in the thickness direction relative to the inner surface of the pipe 1, transmits ultrasonic signals from the linear array probe 11 toward the pipe 1 while oscillating the transmission direction of the ultrasonic signal within a predetermined angle range β that has been set in advance, receives and collects secondary creeping waves of the ultrasonic signals reflected from the pipe 1 at each specified angle in the angle range β with the linear array probe 11, receives and acquires mode conversion waves of the ultrasonic signals reflected from the pipe 1 at each specified angle in the angle range β with the linear array probe 11, and judges the presence or absence of defects on the inner surface 1b of the pipe 1 based on the secondary creeping waves and the mode conversion waves.

[0058] According to the ultrasonic inspection device of the sixth aspect, the ultrasonic inspection range is widened, and not only the secondary creeping wave but also the mode conversion wave can be appropriately detected, and even small cracks on the inner surface 1b of the pipe 1 can be detected. As a result, the presence or absence of defects such as cracks on the inner surface 1b of the pipe (inspection object) 1 can be determined. [Explanation of symbols]

[0059] 1 Piping (inspection object) 1a surface 1b Inner surface 2. Medium 10 Flaw detector 11 Linear array probe 12 Pulsar 13 Receiver 14 Data storage unit 15 Control element switching section 20 Calculation section 21 Control section 22 Memory section 23 Processing unit 30 Operation / display section 31 Calculation result display section 32 Inspection condition setting section 33 Calculation condition setting section 100 Ultrasonic inspection equipment 110 Transducer

Claims

1. adjusting a focal point of an ultrasonic signal transmitted from a probe to an object to be inspected to a position shifted in a plate thickness direction with respect to an inner surface of the object to be inspected; transmitting an ultrasonic signal from the probe toward the object to be inspected and oscillating a transmission direction of the ultrasonic signal within a preset predetermined angle range; receiving and acquiring, by the probe, a secondary creeping wave of the ultrasonic signal reflected from the object to be inspected for each specified angle in the angle range; receiving and acquiring, by the probe, a mode-converted wave of an ultrasonic signal reflected from the object to be inspected for each specified angle in the angle range; determining whether or not there is a defect on the inner surface of the object to be inspected based on the secondary creeping wave and the mode conversion wave; The ultrasonic inspection method includes:

2. adjusting the transmission direction of the ultrasonic signal so that the distance between the surface of the inspection object and the focal point of the ultrasonic signal does not vary when the transmission direction of the ultrasonic signal is swung within the angle range; The ultrasonic inspection method according to claim 1 .

3. The focal point is shifted in the thickness direction relative to the inner surface of the object to be inspected by 20% or less of the thickness. The ultrasonic inspection method according to claim 1 or 2.

4. For each specified angle in the angle range, the secondary creeping wave and the mode converted wave are obtained when the focal point is located on the inner surface of the object to be inspected, and the secondary creeping wave and the mode converted wave are obtained when the focal point is shifted in a plate thickness direction relative to the inner surface of the object to be inspected. The ultrasonic inspection method according to claim 1 .

5. displaying an image displayed based on the secondary creeping wave and the mode converted wave when the focal point is located on the inner surface of the inspection object, and an image displayed based on the secondary creeping wave and the mode converted wave when the focal point is located shifted in a plate thickness direction with respect to the inner surface of the inspection object; 5. The ultrasonic inspection method according to claim 4.

6. a probe for transmitting an ultrasonic signal to an object to be inspected and receiving an ultrasonic signal reflected from the object to be inspected; a processor that performs processing based on data acquired by using the probe, The arithmetic processing unit is adjusting a focal point of an ultrasonic signal transmitted from the probe to the object to be inspected to a position shifted in a plate thickness direction with respect to an inner surface of the object to be inspected; transmitting an ultrasonic signal from the probe toward the object to be inspected and oscillating a transmission direction of the ultrasonic signal within a preset predetermined angle range; receiving and collecting, by the probe, secondary creeping waves of the ultrasonic signal reflected from the object to be inspected for each specified angle in the angle range; receiving and acquiring, by the probe, a mode-converted wave of an ultrasonic signal reflected from the object to be inspected for each specified angle in the angle range; determining whether or not there is a defect on the inner surface of the object to be inspected based on the secondary creeping wave and the mode conversion wave; Ultrasound testing equipment.

7. adjusting a focal point of an ultrasonic signal transmitted from a probe to an object to be inspected to a position shifted in a plate thickness direction with respect to an inner surface of the object to be inspected; transmitting an ultrasonic signal from the probe toward the object to be inspected and oscillating a transmission direction of the ultrasonic signal within a preset predetermined angle range; receiving and collecting, by the probe, secondary creeping waves of the ultrasonic signal reflected from the object to be inspected for each specified angle in the angle range; receiving and acquiring, by the probe, a mode-converted wave of an ultrasonic signal reflected from the object to be inspected for each specified angle in the angle range; determining whether or not there is a defect on the inner surface of the inspection object based on the secondary creeping wave and the mode conversion wave; A program that causes a computer to execute the following.

Images