JP2014070968A - Ultrasonic inspection device and ultrasonic inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic inspection device capable of detecting a damage occurring in a welding heat affected zone selectively, easily in a short time.SOLUTION: The ultrasonic inspection device for inspecting a weld part using ultrasonic wave includes at least one ultrasonic sensor and an operation section. The ultrasonic sensor transmits ultrasonic wave to the weld part and receives the reflected wave. The operation section identifies a weld heat affected zone on the basis of a first received signal acquired by scanning the weld part with the ultrasonic sensor for region identification (step S101), detects a weld defect or damage in the weld part on the basis of a second received signal acquired by scanning the weld part with the ultrasonic sensor for damage analysis, extracts a damage existing in the identified weld heat affected zone 10C (step S102), and calculates a damage rate as a degree of the extracted damage (step S104).

Description

  The present invention relates to an ultrasonic inspection apparatus and an ultrasonic inspection method for inspecting a weld with ultrasonic waves.

  With the aging of thermal power plants, technology that can diagnose non-destructively the soundness (degree of creep damage) of structural materials such as piping under high temperature and stress has become important. On the other hand, in a thermal power plant having a high operating temperature, a steel material having a high chromium ratio (hereinafter also referred to as high chromium steel) is used as a structural material by welding. However, a characteristic of high chromium steel is that deterioration progresses from the inside at the weld heat affected zone at the weld location. Therefore, it is necessary to inspect the progress of the deterioration.

  A replica method is known as a method for nondestructive inspection of structural materials. Since the replica method is a non-destructive observation of the structure of the metal surface of the structural material, the damage state of the surface of the structural material can be grasped, but the damage state inside the material of the structural material cannot be inspected.

  As a method for detecting an initial deterioration state, a technique for extracting a harmonic component of a transmission frequency is known. For example, Patent Document 1 discloses a method of creating an image of a transmission frequency component and a harmonic component of a backscattered wave or surface wave of an ultrasonic probe and evaluating a remaining life from the ratio of both.

  Patent Document 2 discloses a method for detecting a tissue change by a differential process with a reference signal of a specimen reference unit as a method for detecting a tissue change.

JP 2005-128018 A JP 2007-085949 A

  Conventional ultrasonic inspection devices for welded parts cannot detect the damage that occurs in the weld metal heat-affected zone in distinction from the material structure noise and weld defects of the weld metal part and base metal part. In particular, it was not applicable to the detection of the initial state of creep damage in metallic structural materials.

(1) The invention described in claim 1 is an ultrasonic inspection apparatus that inspects a welded portion using ultrasonic waves, and at least one ultrasonic sensor that transmits ultrasonic waves to the welded portion and receives reflected waves thereof. And an arithmetic unit. The calculation unit specifies a welding heat affected zone based on a first received signal obtained by scanning the welded portion with an ultrasonic sensor to specify a region, and uses the ultrasonic sensor to analyze the damage. Based on the second received signal obtained by scanning, the welding defect or damage in the welded portion is detected, the damage existing in the specified weld heat affected zone is extracted, and the extent of the extracted damage It is characterized by calculating a damage rate.
(2) The invention described in claim 8 is an ultrasonic inspection method for inspecting a welded portion using ultrasonic waves. In order to specify a region, ultrasonic waves are applied to the welded portion while scanning the welded portion with an ultrasonic sensor. And transmits the reflected wave as a first received signal, transmits ultrasonic waves to the welded part while scanning the welded part with an ultrasonic sensor for damage analysis, and receives the reflected wave as the second received signal. The welding heat affected zone is identified based on the first received signal obtained, and the damage present in the identified weld heat affected zone is extracted based on the second received signal. The degree of damage detected at the welding heat affected zone is calculated as a damage rate, and the calculated damage rate is output.

  According to the present invention, a welding heat affected zone is specified, and a reception signal due to damage existing in the specified welding heat affected zone is extracted. For this reason, it is possible to detect a received signal representing damage by distinguishing from weld defect noise of the weld metal part and structure noise of the base metal part, and it is possible to detect deterioration of the metal material at an initial stage.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall schematic diagram including an apparatus and an inspection object for explaining a first embodiment of an ultrasonic inspection apparatus for a weld according to the present invention. It is a figure which shows the operation | movement flow in the ultrasonic inspection apparatus of 1st Embodiment by this invention. It is a figure which shows typically the measurement result which determines the position of a welding heat affected zone with the ultrasonic inspection apparatus of 1st Embodiment by this invention. (A) is sectional drawing of test object, (b) is an example of the change of the reflected wave intensity measured by scanning an ultrasonic probe in the horizontal direction in the figure on the upper surface side of (a) test object. FIG. It is a figure which shows typically the result of having displayed the measurement position of the welding heat affected zone by the 1st Embodiment of this invention on ultrasonic signal distribution. (A) shows sectional drawing of a test object. (B), (c), and (d) are time spectra of ultrasonic signals detected at positions B1, B2, and B3 shown in (a), respectively. As shown in FIG. 4, the reflected wave intensity measured at each scanning position of the ultrasonic probe 6B is displayed in a distribution diagram (B scope) with the scanning distance on the horizontal axis and the ultrasonic propagation time on the vertical axis. FIG. It is a figure explaining the data referred when converting the signal data by the 1st Embodiment of this invention into a damage rate. It is a figure for demonstrating the modification 1 of the 1st Embodiment of this invention. (A) shows sectional drawing of a test object. (B) and (c) are time spectra of ultrasonic signals detected at positions A and C shown in (a), respectively. It is sectional drawing of the test object for demonstrating the modification 2 of the 1st Embodiment of this invention. (A) shows sectional drawing of a test object. (B), (c), and (d) are time spectra of ultrasonic signals detected at positions B1, B2, and B3 shown in (a), respectively. It is a flowchart which shows the operation | movement with the ultrasonic inspection apparatus by the 2nd Embodiment of this invention. It is an example of the welding part drawing by the 2nd Embodiment of this invention. It is a block diagram of the whole structure of the ultrasonic inspection apparatus by the 3rd Embodiment of this invention. It is a flowchart which shows the operation | movement with the ultrasonic inspection apparatus by the 3rd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
-First embodiment-
FIG. 1 is a block diagram showing an outline of a first embodiment of an ultrasonic inspection apparatus according to the present invention. The ultrasonic inspection apparatus includes an ultrasonic sensor, that is, ultrasonic probes 6A and 6B that detect ultrasonic waves that are reflected or scattered by the inspection target 10, and an ultrasonic transmission / reception unit. 2, a data recording unit 3, a data analysis unit 4, and a display unit 5. The data analysis unit 4 includes a data storage unit 4A that stores various data.

  The inspection object 10 is, for example, a welded portion of a pressure vessel or a pipe, and the ultrasonic inspection apparatus of the embodiment inspects damage such as a weld defect in the weld and a void in the weld heat affected zone. In the base material portion 10A of the inspection object 10, there are a weld metal portion 10B and a weld heat affected zone 10C which are weld pools by welding.

  The ultrasonic transmission / reception unit 2 applies transmission waveforms, that is, transmission signals to the ultrasonic probes 6A and 6B in order to transmit ultrasonic waves, and further amplifies reception waveforms from the respective probes, that is, reception signals. The ultrasonic transmission / reception unit 2 includes a signal generator, a transmission amplifier, and a reception amplifier that apply signals to the ultrasonic probes 6A and 6B.

  Connection of the ultrasonic probes 6A and 6B to the ultrasonic transmission / reception unit 2 is performed via a coaxial cable. The ultrasonic transmission / reception unit 2 is connected to the data recording unit 3 by a coaxial cable. The data recording unit 3 has a function of converting a reception waveform of an ultrasonic wave that is an analog signal into a digital waveform that is a digital signal. The data recording unit 3 may use, for example, a commercially available external A / D converter or a board type A / D converter built in a computer.

The data analysis unit 4 is, for example, a computer, has a function of analyzing the digital waveform recorded by the data recording unit 3, and the analysis result is stored in the data storage unit 4A. The analysis content will be described later.
In the data storage unit 4A, the incident state of the ultrasonic wave incident on the inspection object 10 from the ultrasonic probes 6A and 6B, for example, the ultrasonic wave output and the incident angle, and the welding heat affected zone as compared with the analysis result. Shape data is also stored to calculate the degree of damage. The shape data is, for example, CAD data or measurement data.

  The display unit 5 displays image information generated by the data analysis unit 4, for example, a B scope. Furthermore, the digital waveform signal input from the data recording unit 3 to the data analysis unit 4 is displayed on the A scope as necessary. This digital waveform signal is a signal obtained by sampling the output signal from the reception amplifier of the ultrasonic transmission / reception unit 2 by the data recording unit 3.

Next, the ultrasonic probes 6A and 6B will be described.
The ultrasonic probe 6A has at least one ultrasonic transducer. The ultrasonic waves generated by the ultrasonic transducer are transmitted in a substantially vertical direction with respect to the incident surface 10D of the inspection object 10, that is, the scanning surface of the ultrasonic probe 6A. When this ultrasonic wave is incident on the inspection object 10, it is reflected on the inside or the bottom surface 10E of the inspection object 10, and is received by the ultrasonic probe 6A as a reflected signal. The transducer included in the ultrasonic probe 6A generates a longitudinal wave or a transverse wave, and is composed of, for example, a piezoelectric element.

  The ultrasonic probe 6B has at least one or more ultrasonic transducers, transmits ultrasonic waves obliquely toward the welding heat-affected zone 10C of the inspection object 10, and is reflected inside the inspection object 10. Receive a signal. The transducer included in the ultrasonic probe 6B generates a longitudinal wave or a transverse wave, and is composed of, for example, a piezoelectric element. For example, the ultrasonic wave is incident obliquely on the inspection object 10 via a resin wedge. The method to be used is used.

  In an inspection apparatus for flaw-detecting a weld defect in a welded part such as a metal pressure vessel or piping, scanning is performed so as to cross the welded portion on the surface to be inspected. That is, the ultrasonic probe 6A transmits ultrasonic waves in the thickness direction perpendicular to the surface of the inspection object 10 and receives reflected waves. The ultrasonic probe 6B transmits ultrasonic waves at a predetermined angle inclined with respect to a reference line that is the thickness direction of the inspection object 10, that is, incidents ultrasonic waves at an oblique incident angle and receives reflected waves.

  Here, the operation of the ultrasonic inspection apparatus of the present embodiment will be described with reference to the process flow diagram of FIG. 2 and FIGS. 3 to 5 showing the operation at the time of inspection.

-Region identification processing of welding heat affected zone 10C-
In step S101, ultrasonic waves are transmitted and received, and the region of the welding heat affected zone 10C is determined from the reflected wave amplitude. In step S101, the ultrasonic transmission / reception unit 2 selectively applies a transmission signal to the ultrasonic probe 6A. The ultrasonic wave 7 </ b> A (see FIG. 1) incident on the surface of the inspection object 10 approximately perpendicularly is reflected by the inspection object 10. The ultrasonic probe 6 </ b> A receives the reflected ultrasonic wave that is reflected from the inspection object 10 and returns. At this time, the ultrasonic probe 6A is scanned manually or moving from left to right as shown in FIG. 1, for example, and reflection in a range including the base material portion 10A, the welding heat affected zone 10C, and the weld metal portion 10B. Receive waves. That is, the ultrasonic probe 6A is scanned so as to cross the flaw detection area of the inspection object 10.

FIG. 3 is a diagram schematically illustrating the position of the ultrasonic probe 6A and the measured value 21 of the received reflected wave.
The inspection object 10 of the ultrasonic inspection apparatus of this embodiment is a pressure vessel or piping manufactured from, for example, high chromium steel. In the high chromium steel, the crystal grains of the weld heat affected zone 10C are smaller than the crystal grains of the base metal portion 10A and the weld metal portion 10B, and the attenuation of ultrasonic waves in the weld heat affected zone 10C is small. In addition, if there is a weld defect in the weld metal portion 10B, the attenuation of the ultrasonic wave increases. FIG. 3 will be described based on these assumptions.

(1) At the position where the ultrasonic wave is incident only on the base material part 10A of the inspection object 10 (position A1 in FIG. 3A), the ultrasonic wave from the ultrasonic probe 6A is only the base material part 10A having a large attenuation. Is received by the ultrasonic probe 6A as an ultrasonic bottom surface reflected wave. The intensity of the received signal, that is, the reflected wave intensity is referred to as a reference reflected wave intensity Rs0.

(2) The reflected wave intensity observed at the position where the ultrasonic wave enters the base material part 10A through the welding heat affected part 10C of the inspection object 10 (position between P1 and P2 in FIG. 3A) is The reference reflected wave intensity at the position where the ultrasonic wave is incident only on the base material portion 10A of the inspection object 10 (the position A1 in FIG. 3A) becomes larger.

(3) At a position where ultrasonic waves are incident on the weld metal part 10B of the inspection object 10 and further pass through the welding heat affected part 10C and incident on the base material part 10A (position A2 in FIG. 3A). The observed reflected wave intensity passes through the weld metal part 10B where the attenuation of the ultrasonic wave is large, the welding heat affected part 10C where the attenuation is small, and the base material part 10A where the attenuation is large, so that the position P1 in FIG. And the reflected wave intensity observed between P2 and P2. This reflected wave intensity depends on the path length of the ultrasonic waves in the weld metal part 10B and the base material part 10A, and the reflected wave intensity decreases as the path length in the weld metal part 10B increases.

(4) At a position where the ultrasonic wave is incident on the weld metal part 10B of the inspection object 10 and the bottom surface reflected wave is received by the ultrasonic probe 6A through the weld metal part 10B (position A3 in FIG. 3A). The observed reflected wave intensity Rsmin has a large attenuation of the ultrasonic wave and a weld defect exists, so that the reflected wave intensity is smaller than the reflected wave intensity at the position A2.

For the measured value 21 of the reflected wave in FIG. 3B, the reference wave intensity is Rs0, the maximum value is Rsmax, and the minimum value is Rsmin. With the scanning of the ultrasonic probe 6A, the measured value 21 changes as follows.
The change starts from the change point 22A at the reference wave intensity Rs0 to the change point 22B at the maximum value Rsmax. The measured value 21 starts to decrease from the change point 22B of the maximum value Rsmax toward the change point 22C having the minimum value Rsmin. When the ultrasonic probe 6A is further scanned, the measurement value 21 starts to increase again from the change point 22D at which the minimum value Rsmin is reached toward the change point 22E at which the maximum value Rsmax is set. Further, the measured value 21 starts to decrease from the change point 22E of the maximum value Rsmax toward the change point 22F where the reference wave intensity Rs0 is obtained.

  The change point 22B at which the maximum value Rsmax of the measurement value 21 in FIG. 3B is obtained is when the attenuation in the path until the ultrasonic wave incident on the surface of the inspection object 10 is reflected from the bottom surface and emitted from the surface is the smallest. can get. This is when the ultrasonic wave enters the position P2 in FIG. Similarly, the maximum value 22E is obtained when the attenuation in the path is the smallest. The scanning direction difference L1 between the scanning position P1 corresponding to the change point 22A where the reference wave intensity Rs0 is obtained and the scanning position P2 corresponding to the change point 22B where the maximum value Rsmax is obtained is the width in the scanning direction of the welding heat affected zone 10C. Corresponds to W1.

  On the other hand, the change point 22C, which is the minimum value Rsmin of the measured value 21 in FIG. 3B, has the greatest attenuation in the path from the time when the ultrasonic wave incident on the surface of the inspection object 10 is reflected from the bottom surface and emitted from the surface. Sometimes obtained. This is when an ultrasonic wave enters between positions P3 and P4 in FIG. Similarly, the change point 22D having the minimum value Rsmin is obtained when the attenuation in the path is the largest. A difference L2 in the scanning direction between the scanning position P3 corresponding to the change point 22C where the minimum value Rsmin is obtained and the scanning position P4 corresponding to the change point 22D where the minimum value Rsmin is obtained is the difference in the scanning direction on the bottom surface of the weld metal portion 10B. The width is W2.

  The calculation unit 4 includes the scan positions P1 to P4, the scan direction width W1 of the welding heat affected zone 10C, the scan direction differences L1 and L2, the scan direction width W2 on the bottom surface of the weld metal unit 10B, and the inspection target. Based on the thickness T of 10, the region of the weld heat affected zone 10C in the inspection object 10 can be specified.

  Actually, the welding heat-affected zone 10C depends on the groove shape and heat input conditions of the welding operation, and if the boundary surface between the welding heat-affected zone 10C and the weld metal portion 10B is not clear, the groove is further increased. When the shape is narrow, the shape of the change point 22C that becomes the minimum value Rsmin and the change point 22D that becomes the minimum value Rsmin may not be clear. In that case, the center of the region of the welding heat affected zone 10C is obtained from the change point 22B at which the maximum value Rsmax is reached and the change point 22E at which the maximum value Rsmax is reached, and the groove angle θ and the weld heat affected zone 10C which are set in advance in the welding operation are obtained. The region of the weld heat affected zone 10C may be determined on the basis of the width D, which is an empirical value. That is, the angle θ, which is data representing the shape of the region of the weld heat affected zone 10C, is determined by the groove shape of the welded portion in the welding operation, and the width D is accumulated from this groove shape and heat input conditions. It can be determined based on the data of welding work.

  As described above, in step S101, the ultrasonic wave is incident on the scanning surface 10D of the inspection object 10 from the ultrasonic probe 6A substantially perpendicularly and the reflected wave intensity is measured, whereby the welded portion of the inspection object 10 is measured. Measure reflected wave intensity reflecting tissue structure. If necessary, the region of the weld heat affected zone 10C may be determined based on the angle θ and the width D set in advance by welding.

  It is a characteristic of high chromium steel that the attenuation of ultrasonic waves is large in the weld metal portion 10B and the attenuation is small in the weld heat affected zone 10C. When high-chromium steel is not used as the structural material, depending on the material, change points 22B and 22E at which the measured value 21 of the reflected wave becomes the maximum value Rsmax in FIG. 3B, or conversely the minimum value Rsmin in FIG. There is a possibility that the shape of the change points 22C and 22D to be different from the shape illustrated in FIG. Further, the width of the weld heat affected zone 10C, the size of the crystal grains, and the like vary depending on the groove shape of the welding work and the heat input conditions. However, even in such a case, the data of the reflection intensity change as shown in FIG. 3B is obtained, and from this, the position of the welding heat affected zone 10C can be detected, that is, the region can be specified.

-Specifying the presence or absence of damage in the weld heat affected zone 10C-
Next, in step S102, the reflected wave intensity is measured by transmitting and receiving ultrasonic waves while scanning the ultrasonic probe 6B on the upper surface 10D of the inspection object 10, and the reflection intensity distribution in the depth direction of the inspection object 10 is measured. (B scope), the signal data of the reflected wave from the region of the welding heat affected zone 10C determined in step S101 is extracted.

  In step S <b> 102, the ultrasonic transmission / reception unit 2 reflects the ultrasonic wave 7 </ b> B (see FIG. 1 and FIG. 4) propagated in an oblique direction at a predetermined angle with respect to the incident surface of the inspection object 10. Then, a transmission signal is selectively applied to the ultrasonic probe 6B so as to receive the returning ultrasonic wave, and a reflected signal is received. At this time, the position of the ultrasound probe 6B is scanned manually or with a moving body from the left to the right of the scanning surface 10D of the inspection object 10 as shown in FIG. The reflected wave in the range including the welding heat affected zone 10C and the weld metal portion 10B is received.

Examples of changes in the reflected wave intensity with respect to the ultrasonic propagation distance at this time are schematically shown in FIGS. 4B, 4C, and 4D. 4B to 4D correspond to the case where the ultrasonic probe 6B is at the positions B1 to B3 in FIG. 4A.
In FIG. 4A, it is assumed that a damaged portion (void) is included in the welding heat affected zone 10C. This is based on the fact that damage is likely to occur inside the region where the crystal grains of the weld heat affected zone 10C are small.

  The ultrasonic wave incident from the oblique direction on the upper surface 10D of the inspection object 10 from the ultrasonic probe 6B is partially scattered inside the inspection object, reflected at a portion where the composition or tissue inside the inspection object changes, and super The detection is returned to the acoustic probe 6B. When entering from an oblique direction, most of the ultrasonic waves reflected from the bottom surface 10E are directed to the left side in FIG. 4A, and the reflected waves hardly return to the ultrasonic probe 6B.

In the portion where the composition or tissue changes, the propagation speed of the ultrasonic wave changes and the ultrasonic wave is reflected. In particular, the reflection of ultrasonic waves increases in damaged parts such as voids and cracks. FIG. 4B shows that at the scanning position B1 of the ultrasonic probe 6B, the ultrasonic wave reflected by the damaged portion 10V1 on the left side of the welding heat affected zone 10C is detected to the right of the central portion. .
FIG. 4D shows that the ultrasonic wave reflected by the damaged portion 10V2 on the right side of the welding heat affected zone 10C is detected at the central portion at the scanning position B3 of the ultrasonic probe 6B. Yes.

FIG. 4C corresponds to the scanning position B2 of the ultrasonic probe 6B, and since there is no particularly reflecting tissue in the ultrasonic wave propagation path, the central portion of FIG. It is shown that the scattered wave is detected as a background signal.
Note that the reflected wave on the right bottom surface 10E in FIG. 4C includes a reflected wave at the boundary between the weld heat affected zone 10C and the weld metal portion 10B, as can be seen from FIG. 4A.

  Although damage such as voids and cracks may occur outside the weld heat affected zone 10C, in this case, as can be seen from the above description, the detected reflected ultrasonic waves are other than the weld heat affected zone 10C. Therefore, it can be easily determined that the problem has occurred.

  When the reflected wave intensity measured at each scanning position of the ultrasonic probe 6B is displayed in a distribution diagram (B scope) with the scanning distance on the horizontal axis and the ultrasonic propagation time on the vertical axis, the pattern of FIG. It looks like the figure. Here, the signals in the regions 24A and 24B correspond to the reflected waves from the damaged portions 10V1 and 10V2 in the welding heat affected zone 10C, respectively. The signal in the region 25 is a scattered wave from the weld metal portion 10B, and the signal in the region 26 is a reverberation (scattered wave) near the surface of the inspection target 10 of the transmission signal. Further, the signal in the region 27 is a scattered wave from the base material portion 10A.

  As can be seen from the description in FIG. 4, the signal strength of the regions 24A and 24B corresponding to the damaged portions 10V1 and 10V2 of the welding heat affected zone 10C and the signal strength of the region 26 corresponding to the vicinity of the upper surface 10D of the inspection target 10 are high. The signal intensity in the region 25 corresponding to the weld metal portion 10B and the region 27 corresponding to the base material portion 10A is low.

In FIG. 5, dotted lines 23A and 23B are boundaries of the region of the welding heat affected zone 10C determined in step S101. By superimposing the dotted lines 23A and 23B on the reflected wave intensity distribution data (B scope) of FIG. 5, it is possible to easily determine whether or not the signals are from the damaged portions 10V1 and 10V2 in the welding heat affected zone 10C.
In addition to the signals from the damaged portions 10V1 and 10V2, the signal from the welding heat affected zone 10C includes a scattered wave other than these damaged portions and a signal reflected at the boundary with the weld metal portion 10B or the base material portion 10A. Although included, it is smaller than the signals from the damaged portions 10V1 and 10V2, and these signals form one peak as shown in FIGS.

  As described above, since the signals from the damaged portions 10V1 and 10V2 in the welding heat affected zone 10C are identified, the intensity of the signals (reflection signals) from the damaged portions 10V1 and 10V2 is calculated (step 103).

  In step S104, the extracted reflected signal intensity of the damaged portion 10V1 or 10V2 is converted into a damage rate. For example, by using a structural material in which a weld is damaged, a plurality of sample points 28 of the damage rate and ultrasonic signal reflected signal intensity as shown in FIG. deep. Using such a master curve 29, it is converted into a damage rate. For example, the signal intensity in the region 24A can be converted into a damage rate by comparing with the relationship of FIG. Similarly, the damage rate can be obtained for the signal intensity in the region 24B.

According to the first embodiment described above, the following operational effects can be obtained.
(1) The ultrasonic inspection apparatus according to the first embodiment for inspecting a welded portion using ultrasonic waves transmits ultrasonic waves to the welded portion, receives ultrasonic waves from the ultrasonic sensors 6A and 6B, and ultrasonic waves. Based on the first and second received signals received by the sensors 6A and 6B, the welding heat affected zone 10C is specified, the damage existing in the weld heat affected zone 10C is detected, and the calculation unit 4 calculates the damage rate. Is provided.
According to such an ultrasonic inspection apparatus, since the welding heat affected zone 10C is specified, when the deterioration of the metal material is detected at the initial stage, the detected reflected signal of the ultrasonic wave is generated in the weld heat affected zone. It can be easily discriminated whether it is due to damage such as voids or due to weld defect noise in the weld metal part or structure noise in the base metal part. Moreover, the damage rate of damage existing in the welding heat affected zone 10C can be calculated with high accuracy.

  In particular, in a high chromium steel weld zone, a reflected wave other than damage, such as a weld defect signal and a tissue boundary signal, is generated in the weld heat affected zone 10C, the base metal portion 10A, and the weld metal zone 10B. By clearly distinguishing and detecting the reflected wave, it is possible to reliably grasp the state of the weld heat affected zone where damage is likely to occur.

(2) A data storage unit 4A for storing the shape data of the welded portion is provided, and the calculation unit, that is, the data analysis unit 4, specifies the welding heat affected zone 10C based on the first received signal and the shape data. . As a result, even when it is difficult to identify the welding heat affected zone 10C only by the first received signal, the welding heat affected zone 10C can be accurately identified with reference to the shape data.
(3) Referring to the master curve, which is a correspondence relationship representing the relationship of the damage rate to the intensity of the second received signal, the intensity of the second received signal in the area where damage is detected in the welding heat affected zone 10C Based on this, the damage rate was calculated. As a result, the calculation of the damage rate is simplified.

(Modification 1)
In calculating the intensity of the reflected wave peak from the damaged portion 10V1 or 10V2 described above, the intensity distribution (spectrum) of the reflected wave with respect to the entire region of the ultrasonic propagation distance as shown in FIGS. The time window (gate) may be set at the time of signal detection so that only the peak of the reflected wave from the damaged part is detected. Since the ultrasonic propagation distance (signal delay time) at which the reflected signal from the welding heat affected zone 10C is detected is determined in step S101, based on this, it is time to detect only the reflected signal from the welding heat affected zone 10C. A window (gate) may be set.

  For example, as shown in FIG. 7A, the timing of a time window (gate) in which obliquely incident ultrasonic waves pass through the welding heat affected zone 10C and the reflected waves of this portion are detected by the ultrasonic probe 6B. By changing according to the movement of the ultrasonic probe 6B, only the reflection signal from the welding heat affected zone 10C can be detected.

  Alternatively, a time window (gate) having a fixed width for detecting a reflection signal from the range of the welding heat affected zone 10C may be moved with time in accordance with the movement of the ultrasonic probe 6B. As shown in FIGS. 7B and 7C, the reflected waves from the damaged portions 10V1 and 10V2 that move in accordance with the movement of the ultrasonic probe 6B on the horizontal axis (ultrasonic propagation distance). This corresponds to moving the window (gate) according to the peak of.

  By measuring the reflected signal in this way, most of the operation in step S102 can be omitted, and the measurement time can be shortened.

(Modification 2)
Since the damaged part in the welding heat affected part 10C is often formed at the substantially central part in the welding heat affected part 10C, that is, the central part in the thickness direction of the inspection object 10, the signal detection is further performed in the first modification. Sometimes the time window (gate) is set so as to detect signals from only the central part in the thickness direction of the inspection object 10 (see FIG. 8A).

  For example, the width and the temporal position of the time window (gate) can be fixed and set so as to detect ultrasonic waves reflected only from a predetermined range in the central portion of the inspection object 10 in the thickness direction. In this case, as shown in FIGS. 8A to 8D, this always corresponds to fixing a window having a predetermined width at the position of the same horizontal axis (ultrasonic propagation distance).

  By fixing the width and time position of the time window (gate) for measuring the reflected signal in this way, most of the operation of step S102 can be omitted and the amount of data to be processed can be greatly reduced. Measurement time can be further reduced.

  Note that this window position may be fixed at substantially the same position in the thickness direction, even if it is other than the central portion in the thickness direction. This is because the damaged portion in the weld heat affected zone 10C may be displaced from the central portion in the thickness direction depending on the shape and material of the welded portion and the ambient temperature environment during welding.

-Second Embodiment-
The ultrasonic inspection apparatus for a welded portion according to the second embodiment of the present invention is improved to improve the accuracy of determining the region of the weld heat affected zone.
Since the basic configuration of the ultrasonic inspection apparatus according to this embodiment is the same as that of the first embodiment shown in FIG. 1, only the differences will be mainly described.
An outline of the operation of the ultrasonic inspection apparatus of the present embodiment will be described with reference to the flowchart of FIG. 9 and FIG.

  In step S201, ultrasonic waves are transmitted and received, and the position of the welding heat affected zone 10C is determined from the reflected wave amplitude. This step S201 is substantially the same as step S101 shown in FIG. 2 of the first embodiment, and the position of the welding heat affected zone 10C is detected from the change points 22B and 22E where the maximum value Rsmax of the measured value 21 is obtained. . The difference from step S101 is that the width D and the angle θ of the welding heat affected zone 10C are set according to various welds to be inspected using the welding drawing data.

  In step S202, the region of the welding heat affected zone 10C is determined with reference to the welding drawing. A welding drawing is an example as shown in FIG. 10, for example, and is actually given by, for example, CAD data. The width D and the angle θ of the weld heat affected zone 10C actually vary depending on the groove shape and heat input conditions of the welding work for each weld zone, but in the first embodiment, this is related to the weld zone. A fixed value was adopted. However, by referring to the CAD data for performing welding, the region of the welding heat affected zone 10C can be more accurately identified with reference to the width D and the angle θ read from the CAD data for each welded portion.

  Although the above description has been made with reference to only the cross section of the welding work, the inspection object 10 has a two-dimensional size in a direction perpendicular to the cross section. It is performed so as to form a continuous line from the upper surface 10D side. In this continuous welding operation, the thickness of the inspection object and the surrounding conditions may change, so that the groove shape and the heat input conditions are changed in accordance with these, and welding is performed. Accordingly, the width and angle of the weld heat affected zone can be accurately set by using CAD data or the like in an inspection object having a complicated shape in which welding conditions can be variously changed.

Steps S203 to S205 are the same as steps S102 to S104 of the first embodiment, respectively, and thus description thereof is omitted.
As described above, the accuracy of determining the region of the weld heat affected zone 10C is improved by using the second embodiment of the present invention.

  Note that the angle θ and the width D, which are the shape parameters of the welding heat affected zone 10C in the welding operation described in the first embodiment, or the CAD data described in the second embodiment are shown in FIG. The program is stored as appropriate in the storage unit 4A described above, and the display program is operated and displayed on the display unit 5 (see, for example, FIG. 3A). It is visually recognized that the ultrasonic signal from the welding heat affected zone is detected by superimposing and displaying the analysis result of the ultrasonic data analysis unit 4 detected by the ultrasonic probes 6A and 6B. can do.

  Further, the shape of the weld heat affected zone is displayed on the display unit 5 in this way, and on the displayed shape, as described above, as shown in FIGS. 7 (a) and 8 (a). As described above, by setting the window (gate), it is possible to set the window for detecting the reflected wave of the ultrasonic wave shown in FIG. 7B and FIGS. 8B to 8D. . The position of the window (gate) on the screen as shown in FIGS. 7A and 8A, and the reflected wave detection window shown in FIGS. 7B and 8B to 8D ( The position of the gate) is easily related from the incident angle of the ultrasonic wave, the ultrasonic wave propagation speed of the inspection object, or the measured spectra of FIGS. 7B and 8B to 8D.

According to the ultrasonic inspection apparatus of the second embodiment described above, the same operational effects as the apparatus of the first embodiment can be obtained, and the following operational effects can also be obtained.
(1) By using CAD data corresponding to the welding construction drawing, the region of the welding heat affected zone 10C is specified for each welding portion in consideration of the detailed groove shape and heat input conditions of the inspection target in the welding construction. Can improve the accuracy of damage diagnosis.

-Third embodiment-
In the ultrasonic inspection apparatus according to the third embodiment of the present invention, an ultrasonic sensor that identifies the welding heat affected zone 10C and an ultrasonic sensor that detects damage are combined using an ultrasonic array sensor.
FIG. 11 is a block diagram of an ultrasonic inspection apparatus according to the third embodiment of the present invention, in which an inspection object 10, an array type ultrasonic sensor 11 that makes ultrasonic waves incident on the inspection object 10, a transmission / reception unit 12, and a reception The display unit 13 displays signals and flaw detection images.

  As shown in the figure, the array-type ultrasonic sensor 11 basically includes a plurality of piezoelectric vibration elements 14 that generate and receive ultrasonic waves. The array type ultrasonic sensor 11 is installed on the flaw detection surface of the inspection object 10 and then generates an ultrasonic wave 15 by a drive signal supplied from the transmission / reception unit 12. This ultrasonic wave is propagated into the inspection object 10 and reflected within the inspection object 10. Such reflected waves are received and input to the transmission / reception unit 12.

  The transmission / reception unit 12 transmits and receives ultrasonic waves using the array-type ultrasonic sensor 11. The transmission / reception unit 12 includes a computer 12A, a delay time control unit 12B, a pulsar 12C, a receiver 12D, and a data recording unit 12E. In the transmission / reception unit 12 configured as described above, the pulser 12C supplies a drive signal to the array-type ultrasonic sensor 11, and the receiver 12D processes the reception signal input from the array-type ultrasonic sensor 11.

The computer 12A reads the required external data from the data recording unit 12E, performs arithmetic processing, and outputs the processed data to the data recording unit 12E as necessary. The computer 12A controls the delay time control unit 12B, the pulsar 12C, and the receiver 12D so that necessary operations can be obtained.
First, the delay time control unit 12B controls both the timing of the drive signal output from the pulsar 12C and the input timing of the received signal by the receiver 12D, thereby performing the operation of the array-type ultrasonic sensor 11 by the phased array method. Make it. The operation of the array-type ultrasonic sensor 11 by the phased array method is an operation of transmitting and receiving an ultrasonic wave by controlling the focal position and the incident angle 16 of the ultrasonic wave 15. A reception signal is supplied from the receiver 12D to the data recording unit 12E by the array type ultrasonic sensor 11 of the phased array system.

  Subsequently, the data recording unit 12E processes the supplied reception signal and records it as recorded data, and simultaneously sends the data to the computer 12A. The computer 12A synthesizes the waveform obtained by each piezoelectric vibration element according to the delay time, performs an appropriate interpolation process on the waveform for each incident angle of each ultrasonic wave, and uses a two-dimensional square lattice called a pixel as a unit. 2D flaw detection data in the pixel format is created. The two-dimensional flaw detection data is imaged and displayed on the display unit 13.

  The display unit 13 includes a two-dimensional display screen 13B that displays two-dimensional flaw detection data, and a waveform display screen 13A that displays the waveform signal of each piezoelectric vibrator. Although only one display unit 13 is shown in FIG. 1, the waveform display screen 13A and the two-dimensional display screen 13B may be displayed by being shared by a plurality of display units.

The operation of the ultrasonic inspection apparatus according to the third embodiment will be described with reference to the flowchart of FIG.
In step S301, the delay time is controlled to transmit / receive ultrasonic waves from the array ultrasonic sensor 11, and the position of the welding heat affected zone 10C is determined from the reflected wave amplitude. At this time, the delay time is controlled so that ultrasonic waves are transmitted in a direction perpendicular to the incident surface of the inspection object 10. The ultrasonic wave propagated in the substantially vertical direction of the inspection object 10 receives a bottom surface reflected wave that is reflected by the bottom surface of the inspection object 10 and returns.

In step S302, the delay time is controlled, ultrasonic waves are transmitted / received from the array-type ultrasonic sensor 11, the reflected wave intensity distribution is measured, and signal data in the region of the welding heat affected zone 10C determined in step S301 is extracted. . In step S <b> 301, the ultrasonic transmission / reception unit 2 controls the delay time for applying the transmission signal to the array type ultrasonic sensor 11, and causes the ultrasonic wave to enter the oblique direction with respect to the incident surface of the inspection object 10. The ultrasonic wave propagating in the oblique direction receives an ultrasonic reflected wave that returns after being reflected inside the inspection object 10. Subsequent steps S302 to S304 are equivalent to steps S102 to S104 shown in FIG. 2 of the first embodiment.
Note that step S303 is the same as step S103 of the first embodiment, and a description thereof will be omitted.

As described above, according to the third embodiment, the same operational effects as the ultrasonic inspection apparatus of the first embodiment can be obtained, and the following operational effects can also be obtained.
(1) By controlling the delay time using one array type ultrasonic sensor, it is not necessary to use a plurality of ultrasonic probes as in the first and second embodiments, and the measurement procedure is simplified. it can.

  Note that the ultrasonic inspection apparatus of the third embodiment can be operated as in the first and second modifications of the first embodiment, and by operating in this way, the measurement time can be reduced. Shortening and processing data can be reduced.

(Modification 3)
When the damage rate calculated from the reflected wave intensity of the damaged portions 10V1 and 10V2 of the welding heat affected zone 10C described above is equal to or greater than a predetermined value, the calculation unit 4 may output a warning. Further, the calculation unit 4 calculates and stores the damage rate at predetermined time intervals, calculates the time change of the damage rate, and based on the time change, for example, creep damage develops and becomes a crack, causing a problem. It is also possible to estimate the time when it seems to be.

In the ultrasonic inspection apparatus according to the third modification, the following operational effects can be obtained.
(1) If the calculation unit 4 is configured to output a warning when the damage rate is greater than a predetermined damage rate, the reliability in maintenance work is improved.
(2) If the calculation unit 4 is configured to output a warning before the damage rate reaches a predetermined damage rate based on the change in the damage rate over time, the life of the welded portion can be more reliably predicted. it can.
(3) Therefore, it is possible to incorporate functions such as generating an alarm such as parts replacement when a problem occurs or sufficiently before the problem occurs. As a result, a safer ultrasonic inspection apparatus for a welded portion can be obtained.

The above embodiments and modifications can be further modified as follows.
(1) In the first embodiment described above, the ultrasonic probes 6A and 6B are scanned across the welded part on the surface of the inspection object spread in a plane, and ultrasonic waves are transmitted and received perpendicularly to this surface. However, although it has been described that ultrasonic waves are transmitted to and received from this surface in an oblique direction, the inspection target is not limited to a planar shape.
(2) The moving object on which the ultrasonic probes 6A and 6B are mounted may be moved on the surface of the inspection object 10 to scan the inspection object 10. The operator can also manually scan the surface to be inspected with the ultrasonic probes 6A and 6B.

  The above description is examples of the embodiments and modified embodiments of the present invention, and the present invention is not limited to these embodiments and modified examples. Those skilled in the art can implement various modifications without impairing the features of the present invention. In particular, in the present invention, the first embodiment and the second embodiment can be implemented by appropriately combining the third embodiment and the first to third modifications. Thus, by implementing combining 1st-3rd embodiment and the modifications 1-3, it can be set as the ultrasonic inspection apparatus which can test | inspect the damage state of the welding part of a metal member easily and quickly. . Of course, the material to be inspected is not limited to high chromium steel, and the object to be inspected is not limited to a pressure vessel or piping.

DESCRIPTION OF SYMBOLS 1 ... Ultrasonic inspection apparatus 2 ... Ultrasonic transmission / reception part 3 ... Data recording part 4 ... Data analysis part 4A ... Data storage part 5 ... Display part 6A ... Ultrasonic sensor 6B ... Ultrasonic sensor 7A ... Ultrasonic 7B ... Ultrasonic 10 ... inspection object 10A ... base metal part 10B ... weld metal part 10C ... welding heat affected zone 10D ... top surface of inspection object 10 (scanning surface of ultrasonic probe)
10E: Bottom surface 11 of inspection object 10 ... Array-type ultrasonic sensor 12 ... Transmission / reception unit 12A ... Computer 12B ... Delay time control unit 12C ... Pulser 12D ... Receiver 12E ... Data recording unit 12F ... Data storage unit 13 ... Display unit 13A ... Waveform display screen 13B ... Two-dimensional display screen 14 ... Piezoelectric vibration element 15 ... Ultrasonic wave 16 ... Incident angle 21 ... Measurement values 22A to 22F ... Measurement value change point 23 ... Boundary line 24A of the region of welding heat affected zone 10C, 24B ... Reflected wave signal 25 from welding heat affected zone 10C ... Scattered wave signal 26 from inside welded metal part 10B ... Reverberation (scattering) signal 27 from transmitted object surface to be inspected 27 ... Scattered wave from inside base material 10A Signal 28 ... Ultrasonic signal amplitude sample point 29 ... Damage rate master curve

Claims (10)

In an ultrasonic inspection device that inspects welds using ultrasonic waves,
At least one ultrasonic sensor for transmitting ultrasonic waves to the weld and receiving the reflected waves;
The weld heat affected zone is identified based on a first received signal obtained by scanning the weld with the ultrasonic sensor for region identification, and the weld zone with the ultrasonic sensor for damage analysis. On the basis of the second received signal obtained by scanning the welded portion, the welding defect or damage in the welded portion is detected, the damage existing in the specified weld heat affected zone is extracted, and the extracted damage is detected. An ultrasonic inspection apparatus comprising: a calculation unit that calculates a damage rate that is a degree. The ultrasonic inspection apparatus according to claim 1,
The calculation unit has a data storage unit that stores shape data of the welded part,
The ultrasonic inspection apparatus, wherein the calculation unit identifies the welding heat affected zone based on the first reception signal and the shape data. The ultrasonic inspection apparatus according to claim 1,
The calculation unit includes a storage unit that stores a correspondence relationship representing a relationship of a damage rate with respect to the intensity of the second reception signal,
The ultrasonic inspection apparatus, wherein the damage rate is calculated based on the intensity of the second received signal in a region where damage is detected in the welding heat affected zone with reference to the correspondence relationship. The ultrasonic inspection apparatus according to claim 1,
The ultrasonic sensor has first and second ultrasonic sensors,
The first reception signal is a reception signal of an ultrasonic wave incident at a first angle from the first ultrasonic sensor to the welded portion,
The ultrasonic inspection apparatus, wherein the second reception signal is an ultrasonic reception signal incident on the welded portion from the second ultrasonic sensor at a second angle. The ultrasonic inspection apparatus according to claim 1,
As the ultrasonic sensor, having an ultrasonic array sensor,
The first reception signal is a reception signal of an ultrasonic wave incident on the weld at a substantially vertical angle from the ultrasonic array sensor,
The ultrasonic inspection apparatus, wherein the second reception signal is an ultrasonic reception signal incident on the welded portion at an oblique incident angle from the ultrasonic array sensor. The ultrasonic inspection apparatus according to claim 3,
The ultrasonic inspection apparatus, wherein the arithmetic unit outputs a warning when the damage rate is larger than a predetermined damage rate. The ultrasonic inspection apparatus according to claim 3,
The ultrasonic inspection apparatus, wherein the calculation unit outputs a warning before the damage rate reaches a predetermined damage rate based on a change in the damage rate with time. In the ultrasonic inspection method for inspecting the weld using ultrasonic waves,
In order to specify the region, an ultrasonic wave is transmitted to the welded portion while scanning the welded portion with an ultrasonic sensor, and the reflected wave is received as a first reception signal.
For damage analysis, ultrasonic waves are transmitted to the welded portion while scanning the welded portion with the ultrasonic sensor, and the reflected wave is received as a second received signal,
Identifying the weld heat affected zone based on the first received signal obtained;
Based on the second received signal, extract damage present in the identified weld heat affected zone,
Calculating the degree of damage detected at the identified weld heat affected zone as a damage rate,
An ultrasonic inspection method characterized by outputting the calculated damage rate. The ultrasonic inspection method according to claim 8,
Storing the shape data of the weld,
The ultrasonic inspection method characterized by specifying the welding heat affected zone based on the first received signal and the shape data. The ultrasonic inspection method according to claim 8,
Storing a correspondence relationship representing a relationship of a damage rate with respect to the second reception intensity;
An ultrasonic inspection method, wherein the damage rate is calculated based on the intensity of the second received signal in an area where the damage is detected with reference to the correspondence relationship.

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