JP4112526B2 - Ultrasonic flaw detection method and apparatus - Google Patents

Ultrasonic flaw detection method and apparatus Download PDF

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JP4112526B2
JP4112526B2 JP2004164085A JP2004164085A JP4112526B2 JP 4112526 B2 JP4112526 B2 JP 4112526B2 JP 2004164085 A JP2004164085 A JP 2004164085A JP 2004164085 A JP2004164085 A JP 2004164085A JP 4112526 B2 JP4112526 B2 JP 4112526B2
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crack defect
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JP2005345217A (en
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甫 羽田野
秀秋 田中
哲也 天野
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Japan Steel Works Ltd
JFE Engineering Corp
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04Analysing solids
    • G01N29/06Visualisation of the interior, e.g. acoustic microscopy
    • G01N29/0654Imaging
    • G01N29/069Defect imaging, localisation and sizing using, e.g. time of flight diffraction [TOFD], synthetic aperture focusing technique [SAFT], Amplituden-Laufzeit-Ortskurven [ALOK] technique
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00Indexing codes associated with group G01N29/00
    • G01N2291/04Wave modes and trajectories
    • G01N2291/044Internal reflections (echoes), e.g. on walls or defects

Description

本発明は超音波探傷に関し、特に、欠陥の傾き角を簡便かつ精確に推定することができる超音波探傷方法とその装置に関するものである。   The present invention relates to ultrasonic flaw detection, and more particularly to an ultrasonic flaw detection method and apparatus capable of easily and accurately estimating a tilt angle of a defect.

最近、種々の装置や設備の安全性が求められている中で、事故の原因となりかねない欠陥を早く正確に発見することが重要となってきている。非破壊検査法は対象物を破壊することなく欠陥や物性的特性を調べる方法である。非破壊検査法の一種である超音波探傷法は、対象物の外部から超音波を入射し、その反射波や透過波、あるいは回折波を受信し分析することにより内部を調べるものである。   Recently, safety of various devices and facilities has been demanded, and it has become important to quickly and accurately find defects that may cause accidents. The nondestructive inspection method is a method for examining defects and physical properties without destroying an object. The ultrasonic flaw detection method, which is a kind of nondestructive inspection method, is for examining the inside by receiving ultrasonic waves from the outside of an object and receiving and analyzing the reflected waves, transmitted waves, or diffracted waves.

従来の超音波探傷法は、欠陥などの欠陥の存在をある程度敏感に検出できたが、欠陥の形状や大きさ、又は傾き角に関する情報を得ることは難しかった。
そこで、欠陥の寸法をより精確に測定し得る超音波探傷法としてTOFD(Time of Flight Diffraction)法が期待されている。TOFD法では、一対の送波用の超音波探触子と受波用の超音波探触子を、対象物の表面に一定距離を隔てて対向して配置し、送波用探触子から対象物中に超音波を放射する。対象物の表面を直接伝わる波(ラテラル波)、そして対象物の底面から反射された底面反射波とともに、対象物中にきずなどの欠陥が存在する場合に欠陥の端部に入射した超音波によって生じる回折波を受波用探触子で受信し、これらの波の伝搬時間を基に欠陥の位置や寸法を測定しようとするものである。従来の超音波探傷試験における欠陥の寸法測定には、デシベルドロップ法、評価レベル法、DGS法などが広く用いられてきた。これらの手法は、探触子の移動距離やエコー高さに基づいた評価を行なうため、探触子のビームピロフィール、走査ピッチ、あるいは欠陥の傾き角度などによって、測定精度が影響を受けることを避け得なかった。これに対しTOFD法は、比較的高精度の測定が可能な伝搬時間を利用するため、欠陥の寸法測定の精度の向上を期待できることになる。
Conventional ultrasonic flaw detection methods can detect the presence of defects such as defects with some sensitivity, but it has been difficult to obtain information on the shape and size of the defects or the tilt angle.
Therefore, a TOFD (Time of Flight Diffraction) method is expected as an ultrasonic flaw detection method capable of measuring the size of a defect more accurately. In the TOFD method, a pair of an ultrasonic probe for transmission and an ultrasonic probe for reception are arranged opposite to each other at a certain distance from the surface of an object, and the transmission probe is used. Ultrasound is emitted into the object. Along with the wave that travels directly on the surface of the object (lateral wave) and the bottom surface reflected wave reflected from the bottom surface of the object, if there is a defect such as a flaw in the object, the ultrasonic wave incident on the edge of the defect The generated diffracted wave is received by a receiving probe, and the position and size of the defect are to be measured based on the propagation time of these waves. A decibel drop method, an evaluation level method, a DGS method, and the like have been widely used for dimension measurement of defects in conventional ultrasonic flaw detection tests. Since these methods perform evaluation based on the distance and echo height of the probe, the measurement accuracy is affected by the probe's beam pillow feel, scan pitch, or defect tilt angle. It was inevitable. On the other hand, since the TOFD method uses a propagation time capable of relatively high accuracy measurement, it can be expected to improve the accuracy of defect dimension measurement.

図6は、TOFD法における超音波探触子の配置と、種々の超音波の伝搬経路の概要を示している。送波用探触子30と受波用探触子31の一対の探触子の間の対象物40中に高さDのスリット状の欠陥41が存在する場合を想定している。図7は、このとき受波用探触子31から得られる受波信号の概要である。まず対象物40の表面を直接伝わるラテラル波が受信され、続いて欠陥41の上端部41a(超音波探触子を配置した対象物表面に近い側の欠陥の端部)からの上端回折波、そして欠陥41の下端部41b(超音波探触子を配置した対象物表面に遠い側の欠陥の端部)からの下端回折波が受信される。ここで各々の超音波について送波用探触子30の入射点30abから受波用探触子31の入射点31abに至る伝搬時間を測定し、これに対象物40における超音波の伝搬速度を乗ずることによって、各々の超音波の送波用探触子30から受波用探触子31に至る伝搬経路長が求められる。   FIG. 6 shows an outline of the arrangement of ultrasonic probes and the propagation paths of various ultrasonic waves in the TOFD method. It is assumed that a slit-like defect 41 having a height D exists in the object 40 between the pair of probes of the transmitting probe 30 and the receiving probe 31. FIG. 7 shows an outline of the received signal obtained from the receiving probe 31 at this time. First, a lateral wave that is directly transmitted through the surface of the object 40 is received, and then an upper end diffracted wave from the upper end 41a of the defect 41 (the end of the defect close to the object surface on which the ultrasonic probe is disposed), And the lower end diffracted wave from the lower end 41b of the defect 41 (the end of the defect far from the surface of the object on which the ultrasonic probe is arranged) is received. Here, for each ultrasonic wave, the propagation time from the incident point 30ab of the transmitting probe 30 to the incident point 31ab of the receiving probe 31 is measured, and the propagation speed of the ultrasonic wave in the object 40 is measured. By multiplying, the propagation path length from each ultrasonic wave transmission probe 30 to the wave reception probe 31 is obtained.

欠陥41の端部41a、41bの位置を決定するためには例えば、送波用探触子30と受波用探触子31の間隔を一定に保ったまま図6の左右方向に探触子を走査し(B−走査)、回折波の伝搬時間が極小になったときの両探触子30、31のそれぞれの入射点位置の丁度中央の対象物中に、その回折波を生じた欠陥41の端部41aまたは端部41bがあるとする方法などが用いられている。これにより欠陥41の端部41a、41bとそれぞれの探触子30、31との間の水平距離X、Yが定められるので、上記のように求めた伝搬経路長との幾何学的計算により、欠陥41の端部41aまたは端部41bの深さZが推定される。   In order to determine the positions of the end portions 41a and 41b of the defect 41, for example, the probe in the left-right direction in FIG. 6 while keeping the distance between the transmitting probe 30 and the receiving probe 31 constant. (B-scan), the defect that caused the diffracted wave in the object just in the center of each incident point position of the probes 30 and 31 when the propagation time of the diffracted wave is minimized For example, a method in which there are 41 end portions 41a or 41b is used. Thereby, since the horizontal distances X and Y between the end portions 41a and 41b of the defect 41 and the respective probes 30 and 31 are determined, the geometrical calculation with the propagation path length obtained as described above gives The depth Z of the end 41a or the end 41b of the defect 41 is estimated.

また、欠陥の傾き角は、その破壊力学的評価を行う上での重要なパラメータである。上述の方法によって、欠陥の上端部と下端部の位置を求めることによって傾き角を推定することができるが、上端回折波と下端回折波のそれぞれについてB−走査を行って伝搬時間が極小となる位置を決定する必要があり、手続きが煩雑になった。さらに送波用探触子と受波用探触子の間隔に比べて欠陥の寸法は通常微小であるため、この方法によって欠陥の傾き角を精確に推定することは困難であった。勿論この方法は、B−走査が困難となるような対象物には適用が難しく、また実際の対象物で生じることの多い表面又は裏面に開口した欠陥については、当該欠陥の下端部又は上端部のいずれかの位置しか推定できないので、傾き角を決定できなかった。   In addition, the inclination angle of the defect is an important parameter in performing the destructive mechanical evaluation. Although the inclination angle can be estimated by obtaining the positions of the upper end and the lower end of the defect by the above-described method, the propagation time is minimized by performing B-scan for each of the upper end diffracted wave and the lower end diffracted wave. It was necessary to determine the position, and the procedure became complicated. Further, since the size of the defect is usually very small compared to the distance between the transmitting probe and the receiving probe, it is difficult to accurately estimate the inclination angle of the defect by this method. Of course, this method is difficult to apply to an object that makes B-scanning difficult, and for a defect that is frequently generated in an actual object, the lower end or the upper end of the defect. Since only one of the positions can be estimated, the tilt angle could not be determined.

本発明は、上記の問題を解決しかつ煩雑な作業を要しないで、TOFD法において欠陥の傾き角の推定を簡便かつ精確に行い得る超音波探傷方法および装置を提供するものである。   The present invention provides an ultrasonic flaw detection method and apparatus that can easily and accurately estimate the inclination angle of a defect in the TOFD method without solving the above-described problems and requiring complicated work.

本発明者は、TOFD法においてきずなどの欠陥の端部に入射した超音波によって生じる回折波の放射指向性が、欠陥の端部への超音波の入射角に殆んど依存しないことを見いだした。図1はその確認を行うための実験の概要を示している。円形の試験片50の中心に半径方向に沿って垂直な疲労き裂51をいれ、送波用に縦波垂直探触子Tと受波用に縦波垂直探触子Rを試験片50の円周上に配置して、き裂端部からの回折波の強度分布を調べた。図2は、送波用探触子Tを垂直から例えば45°の位置に設置した場合について、受波用探触子Rを試験片50の円周上に沿って移動しながらき裂51の下端部51aからの回折波を受信してその強度分布を測定し、放射指向性のパターンとしてプロットしたものである。回折波の強度は垂直即ち、き裂50の方向から、受波用探触子R側に約60°傾いた方向で最大となっているのが分かる。送波用探触子Tを垂直から20°〜80°の範囲で試験片50の円周上を移動してき裂下端部51aへの超音波入射角を変えても、き裂51の方向から約60°傾いた方向で最大となる回折波の放射パターンは殆んど変化しなかった。この実験は図6に示したTOFD法における下端回折波に対応したものであるが、上端回折波に対応した実験においても、き裂端部への超音波の入射角に拘らず、き裂の方向から約60°傾いた方向で最大となる回折波の放射パターンが確認された。かかる知見に基づいて本発明は完成するに至ったものである。   The present inventor has found that the radiation directivity of the diffracted wave generated by the ultrasonic wave incident on the edge of the defect such as a flaw in the TOFD method is almost independent of the incident angle of the ultrasonic wave on the edge of the defect. It was. FIG. 1 shows an outline of an experiment for performing the confirmation. A vertical fatigue crack 51 is formed along the radial direction at the center of the circular test piece 50, and the longitudinal wave vertical probe T is used for transmitting and the longitudinal wave vertical probe R is used for receiving the test piece 50. Arranged on the circumference, the intensity distribution of the diffracted wave from the crack end was examined. FIG. 2 shows a case in which the crack 51 of the crack 51 is moved while the wave receiving probe R is moved along the circumference of the test piece 50 when the wave transmitting probe T is installed at a position of, for example, 45 ° from the vertical. The diffracted wave from the lower end 51a is received, its intensity distribution is measured, and plotted as a radiation directivity pattern. It can be seen that the intensity of the diffracted wave is maximum, that is, in the direction inclined by about 60 ° from the direction of the crack 50 toward the receiving probe R side. Even if the transmission probe T is moved on the circumference of the test piece 50 in the range of 20 ° to 80 ° from the vertical to change the ultrasonic incident angle to the crack lower end 51a, the direction from the crack 51 can be reduced. The radiation pattern of the diffracted wave that becomes the maximum in the direction inclined by 60 ° hardly changed. This experiment corresponds to the lower end diffracted wave in the TOFD method shown in FIG. 6, but even in the experiment corresponding to the upper end diffracted wave, regardless of the incident angle of the ultrasonic wave to the crack end, The maximum diffraction wave radiation pattern was confirmed in a direction inclined by about 60 ° from the direction. Based on this finding, the present invention has been completed.

すなわち本発明の超音波探傷方法のうち、第1の発明は、対となる送波用探触子と受波用探触子を、対象物の表面に一定距離を隔てて配置し、前記送波用探触子から前記対象物中に超音波を放射し、該対象物中にき裂欠陥が存在する場合に該き裂欠陥の端部に入射した超音波によって生じる回折波を、前記受波用探触子で受信して対象物中に存在する前記き裂欠陥の端部の傾き角を推定する超音波探傷方法であって、
(1)前記き裂欠陥の端部の前記対象物中の位置を特定し、
(2)前記き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを求め、
(3)前記受波用探触子を前記送波用探触子の方向に前後走査したときの受信信号が最大となる前記受波用探触子の位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ該き裂欠陥の端部から引いた法線までの距離(Ymax)を求め、
(4)前記き裂欠陥の端部近傍の傾き角(γ)を以下の式によって推定することを特徴とする超音波探傷方法。
γ={tan −1 (Ymax/Z)}− 60°
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。
That is, of the ultrasonic flaw detection methods of the present invention, the first invention is that the transmitting probe and the receiving probe to be paired are arranged on the surface of the object at a certain distance, and the transmitting probe is received. When the ultrasonic wave is radiated from the wave probe into the object and a crack defect exists in the object, the diffraction wave generated by the ultrasonic wave incident on the end of the crack defect is received. An ultrasonic flaw detection method for estimating an inclination angle of an end of the crack defect received in a wave probe and existing in an object,
(1) Identify the position of the end of the crack defect in the object,
(2) Find the distance Z from the end of the crack defect to a straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object,
(3) From the position of the receiving probe that maximizes the received signal when the receiving probe is scanned back and forth in the direction of the transmitting probe, the transmitting probe And the distance (Ymax) to the normal drawn from the end of the crack defect to the straight line connecting the respective incident points of the receiving probe,
(4) An ultrasonic flaw detection method characterized by estimating an inclination angle (γ) in the vicinity of the edge of the crack defect by the following equation.
γ = {tan −1 (Ymax / Z)} − 60 °
However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).

第2の発明の超音波探傷方法は、対となる送波用探触子と対象物表面に沿って複数の垂直縦波振動子をアレイ状に配設した受波用探触子を、前記対象物の表面に一定距離を隔てて配置し、前記送波用探触子から前記対象物中に超音波を放射し、該対象物中にき裂欠陥が存在する場合に該き裂欠陥の端部に入射した超音波によって生じる回折波によって前記対象物表面に発生する垂直応力成分を、該アレイ探触子の複数の垂直縦波振動子によりそれぞれ受波して対象物中に存在する前記き裂欠陥の端部の傾き角を推定する超音波探傷方法であって、
(1)前記き裂欠陥端部の前記対象物中の位置を特定し、
(2)前記き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを求め、
(3)それぞれの前記垂直縦波振動子の内で前記回折波の受信信号が最大となる垂直縦波振動子の前記対象物表面における位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ該き裂欠陥の端部から引いた法線までの距離(Ymax)を求め、
(4)前記き裂欠陥の端部の傾き角(γ)を以下の式によって推定することを特徴とする超音波探傷方法。
γ={tan −1 (Ymax/Z)}− 60°
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。
An ultrasonic flaw detection method according to a second aspect of the present invention provides a wave receiving probe in which a plurality of vertical longitudinal wave transducers are arranged in an array along a surface of an object and a pair of a wave transmitting probe, Arranged on the surface of the object at a certain distance, radiating ultrasonic waves from the transmitting probe into the object, and if there is a crack defect in the object, The vertical stress components generated on the surface of the object due to the diffracted waves generated by the ultrasonic waves incident on the end portions are respectively received by the plurality of vertical longitudinal wave vibrators of the array probe and exist in the object. An ultrasonic flaw detection method for estimating an inclination angle of an end of a crack defect,
(1) Identify the position of the crack defect end in the object,
(2) Find the distance Z from the end of the crack defect to a straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object,
(3) From the position on the surface of the object of the vertical longitudinal wave vibrator where the received signal of the diffracted wave is maximum among each of the vertical longitudinal wave vibrators, the transmitting probe and the receiving wave Find the distance (Ymax) to the normal line drawn from the end of the crack defect to the straight line connecting each incident point of the probe,
(4) An ultrasonic flaw detection method characterized in that an inclination angle (γ) of an end portion of the crack defect is estimated by the following equation.
γ = {tan −1 (Ymax / Z)} − 60 °
However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).

第3の発明の超音波探傷装置は、対象物中に存在するき裂欠陥の端部の傾き角を超音波探傷法を用いて推定する超音波探傷装置であって、
(1)前記対象物中に超音波を放射する送波用探触子と、
(2)前記き裂欠陥の端部に入射した超音波によって生じる回折波を受波する受波用探触子と、
(3)前記き裂欠陥端部の前記対象物中の位置を特定し、該き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを測定する手段と、
(4)前記受波用探触子を前記送波用探触子の方向に前後走査したときの受信信号が最大となる前記受波用探触子の位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ前記き裂欠陥の端部から引いた法線までの距離(Ymax)を求める位置測定手段と、
(5)前記測定する手段で求められた距離Zと、前記位置測定手段で得られた距離Ymaxを用いて、以下の式によって欠陥の端部近傍の傾き角(γ)を算出する演算部を設けたことを特徴とする超音波探傷装置。
γ={tan −1 (Ymax/Z)}− 60°
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。
An ultrasonic flaw detector according to a third aspect of the present invention is an ultrasonic flaw detector that estimates an inclination angle of an end of a crack defect existing in an object using an ultrasonic flaw detection method.
(1) a transmission probe that emits ultrasonic waves into the object;
(2) a wave receiving probe for receiving a diffracted wave generated by an ultrasonic wave incident on an end of the crack defect;
(3) The position of the crack defect end in the object is specified, and the transmitting probe and the receiving probe arranged on the surface of the object from the end of the crack defect Means for measuring a distance Z to a straight line connecting each incident point of the child;
(4) From the position of the receiving probe that maximizes the received signal when the receiving probe is scanned back and forth in the direction of the transmitting probe, the transmitting probe And a position measuring means for obtaining a distance (Ymax) to a normal line drawn from the end of the crack defect to a straight line connecting the respective incident points of the receiving probe;
(5) Using the distance Z obtained by the measuring means and the distance Ymax obtained by the position measuring means, an arithmetic unit for calculating the inclination angle (γ) near the edge of the defect by the following equation: An ultrasonic flaw detector provided.
γ = {tan −1 (Ymax / Z)} − 60 °
However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).

第4の発明の超音波探傷装置は、対象物中に存在するき裂欠陥の端部の傾き角を超音波探傷法を用いて推定する超音波探傷装置であって、
(1)前記対象物中に超音波を放射する送波用探触子と、
(2)前記対象物表面に沿って複数の垂直縦波振動子がアレイ状に配設され、前記き裂欠陥の端部に入射した超音波によって生じる回折波によって前記対象物表面に発生する垂直応力成分を、前記複数の垂直縦波振動子によりそれぞれ受波する受波用探触子と、
(3)前記き裂欠陥端部の前記対象物中の位置を特定し、該き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを測定する手段と、
(4)それぞれの前記垂直縦波振動子の内で前記回折波の受信信号が最大となる垂直縦波振動子の対象物表面における位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ該き裂欠陥の端部から引いた法線までの距離(Ymax)を求める位置測定手段と、
(5)前記測定する手段で求められた距離Zと、前記位置測定手段で得られた距離Ymaxを用いて、、以下の式によってき裂欠陥の端部の傾き角(γ)を算出する演算部を設けたことを特徴とする超音波探傷装置。
γ={tan −1 (Ymax/Z)}− 60°
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。
An ultrasonic flaw detector according to a fourth aspect of the present invention is an ultrasonic flaw detector that estimates an inclination angle of an end of a crack defect existing in an object using an ultrasonic flaw detection method.
(1) a transmission probe that emits ultrasonic waves into the object;
(2) A plurality of vertical longitudinal wave vibrators arranged in an array along the surface of the object, and vertical generated on the surface of the object by a diffracted wave generated by an ultrasonic wave incident on an end of the crack defect A receiving probe for receiving a stress component by each of the plurality of vertical longitudinal wave vibrators;
(3) The position of the crack defect end in the object is specified, and the transmitting probe and the receiving probe arranged on the surface of the object from the end of the crack defect Means for measuring a distance Z to a straight line connecting each incident point of the child;
(4) From the position on the object surface of the vertical longitudinal wave transducer where the received signal of the diffracted wave is maximum among each of the vertical longitudinal wave transducers, the transmitting probe and the receiving probe are A position measuring means for obtaining a distance (Ymax) to a normal line drawn from the end of the crack defect to a straight line connecting the respective incident points of the transducer;
(5) Using the distance Z obtained by the measuring means and the distance Ymax obtained by the position measuring means, the calculation for calculating the inclination angle (γ) of the crack defect end by the following equation An ultrasonic flaw detector provided with a portion.
γ = {tan −1 (Ymax / Z)} − 60 °
However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).

すなわち、本発明の超音波探傷方法によれば、超音波探傷に際し、欠陥の端部で発生した回折波の放射指向性が入射角に殆ど依存せず、欠陥の傾き角に依存していることから、回折波の放射指向性から欠陥の傾き角を容易かつ正確に知ることができる。また、放射指向性に関しては、受波位置によって受波出力が異なる現象を利用して受信信号が最大となる受波位置を得て回折波の放射指向性を知ることができる。受信信号が最大となる受波位置は、前記するように受波用探触子を走査することで出力が変化する受信信号から最大受信信号となる受波位置を認識することができる。また、受波用探触子をアレイ探触子で構成し、該アレイ探触子の内で最大の受信信号出力が得られる振動子の位置に基づいて受信信号が最大となる受波位置を知ることができる。
上記した受信信号が最大となる受波位置、欠陥の端部位置などを用いることで、回折波の放射指向性、欠陥の傾き角を幾何学的に算出することができる。
That is, according to the ultrasonic flaw detection method of the present invention, the radiation directivity of the diffracted wave generated at the edge of the defect is almost independent of the incident angle and is dependent on the inclination angle of the defect. Therefore, the inclination angle of the defect can be easily and accurately known from the radiation directivity of the diffracted wave. Further, regarding the radiation directivity, it is possible to know the radiation directivity of the diffracted wave by obtaining the reception position where the reception signal is maximized by using the phenomenon that the reception output varies depending on the reception position. As described above, the reception position where the reception signal becomes the maximum can be recognized from the reception signal whose output changes by scanning the reception probe as described above. In addition, the receiving probe is composed of an array probe, and the receiving position where the received signal is maximized is determined based on the position of the transducer from which the maximum received signal output is obtained in the array probe. I can know.
By using the received wave position where the received signal is maximized, the edge position of the defect, and the like, the radiation directivity of the diffracted wave and the inclination angle of the defect can be calculated geometrically.

また、本発明の超音波探傷装置によれば、受波用探触子において受信信号が最大となる受波位置が位置測定手段によって容易に得られ、前記のようにして欠陥の傾き角を容易かつ正確に推定することができる。また、前記した幾何学的な算出は、演算部によって速やかに行うことができ、欠陥の傾きを容易に知ることができる。   In addition, according to the ultrasonic flaw detector of the present invention, the wave receiving position where the received signal becomes maximum in the wave receiving probe can be easily obtained by the position measuring means, and the inclination angle of the defect can be easily obtained as described above. And can be estimated accurately. Further, the geometric calculation described above can be quickly performed by the calculation unit, and the inclination of the defect can be easily known.

以上説明したように、本発明の超音波探傷方法によれば、対となる送波用探触子と受波用探触子を、対象物の表面に一定距離を隔てて配置し、前記送波用探触子から前記対象物中に超音波を放射し、該対象物中にき裂欠陥が存在する場合に該き裂欠陥の端部に入射した超音波によって生じる回折波を、前記受波用探触子で受信して対象物中に存在する前記き裂欠陥の端部の傾き角を推定する超音波探傷方法であって、
(1)前記き裂欠陥の端部の前記対象物中の位置を特定し、
(2)前記き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを求め、
(3)前記受波用探触子を前記送波用探触子の方向に前後走査したときの受信信号が最大となる前記受波用探触子の位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ該き裂欠陥の端部から引いた法線までの距離(Ymax)を求め、
(4)前記き裂欠陥の端部近傍の傾き角(γ)を、
γ={tan −1 (Ymax/Z)}− 60°
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。
の式によって推定するので、従来のTOFD法の問題を解決しかつ煩雑な方法を要しないで、TOFD法において欠陥の傾き角の推定を簡便かつ精確におこなうことができる。
As described above, according to the ultrasonic flaw detection method of the present invention, a pair of a transmitting probe and a receiving probe are arranged on a surface of an object with a certain distance, and the transmitting probe is received. When the ultrasonic wave is radiated from the wave probe into the object and a crack defect exists in the object, the diffraction wave generated by the ultrasonic wave incident on the end of the crack defect is received. An ultrasonic flaw detection method for estimating an inclination angle of an end of the crack defect received in a wave probe and existing in an object,
(1) Identify the position of the end of the crack defect in the object,
(2) Find the distance Z from the end of the crack defect to a straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object,
(3) From the position of the receiving probe that maximizes the received signal when the receiving probe is scanned back and forth in the direction of the transmitting probe, the transmitting probe And the distance (Ymax) to the normal drawn from the end of the crack defect to the straight line connecting the respective incident points of the receiving probe,
(4) The inclination angle (γ) near the edge of the crack defect,
γ = {tan −1 (Ymax / Z)} − 60 °
However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).
Since estimated by the formula, at solves conventional in TOFD method problems and do not require complicated way, it is possible to estimate the tilt angle of the defect simply and accurately in TOFD method.

また、本発明の超音波探傷装置によれば、対象物中に存在するき裂欠陥の端部の傾き角を超音波探傷法を用いて推定する超音波探傷装置であって、
(1)前記対象物中に超音波を放射する送波用探触子と、
(2)前記き裂欠陥の端部に入射した超音波によって生じる回折波を受波する受波用探触子と、
(3)前記き裂欠陥端部の前記対象物中の位置を特定し、該き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを測定する手段と、
(4)前記受波用探触子を前記送波用探触子の方向に前後走査したときの受信信号が最大となる前記受波用探触子の位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ前記き裂欠陥の端部から引いた法線までの距離(Ymax)を求める位置測定手段と、
(5)前記測定する手段で求められた距離Zと、前記位置測定手段で得られた距離Ymaxを用いて、
γ={tan −1 (Ymax/Z)}− 60°
上記式によって欠陥の端部近傍の傾き角(γ)を算出する演算部を設けたので、前記探傷方法を確実に実行して欠陥の傾き角を知ることができる。
Further, according to the ultrasonic flaw detection apparatus of the present invention, an ultrasonic flaw detection apparatus that estimates the inclination angle of the end of a crack defect existing in an object using an ultrasonic flaw detection method,
(1) a transmission probe that emits ultrasonic waves into the object;
(2) a wave receiving probe for receiving a diffracted wave generated by an ultrasonic wave incident on an end of the crack defect;
(3) The position of the crack defect end in the object is specified, and the transmitting probe and the receiving probe arranged on the surface of the object from the end of the crack defect Means for measuring a distance Z to a straight line connecting each incident point of the child;
(4) From the position of the receiving probe that maximizes the received signal when the receiving probe is scanned back and forth in the direction of the transmitting probe, the transmitting probe And a position measuring means for obtaining a distance (Ymax) to a normal line drawn from the end of the crack defect to a straight line connecting the respective incident points of the receiving probe;
(5) Using the distance Z obtained by the measuring means and the distance Ymax obtained by the position measuring means,
γ = {tan −1 (Ymax / Z)} − 60 °
Since the calculation unit for calculating the inclination angle (γ) in the vicinity of the edge of the defect by the above formula is provided, the inclination angle of the defect can be known by reliably executing the flaw detection method.

以下に、本発明の一実施形態を図3に基づいて説明する。
この実施形態では、送波用探触子1に通常の楔を用いた縦波斜角探触子を使用し、受波用探触子2に複数(n個)の垂直縦波振動子a1…anをアレイ状に配設したアレイ探触子を使用する。該垂直縦波振動子a1…anは、対象物5に設置した際に、対象物5の表面5aに沿って位置させることができる。
Below, one Embodiment of this invention is described based on FIG.
In this embodiment, a longitudinal wave oblique angle probe using a normal wedge is used for the transmitting probe 1, and a plurality (n) of vertical longitudinal wave transducers a1 are used for the receiving probe 2. ... An array probe in which an is arranged in an array is used. The vertical longitudinal wave transducers a1 to an can be positioned along the surface 5a of the object 5 when installed on the object 5.

送波用探触子1は、制御部10によって制御される送波信号発生部11に接続されており、該送波用信号発生部11からの送波用信号を受けて超音波縦波を発生する。
送波用探触子1によって対象物5中に超音波縦波を放射することにより生ずるラテラル波、上端回折波、下端回折波、及びその他の超音波は受波用探触子2で受波される。
アレイ探触子を構成する各々の垂直縦波振動子a1…anの受波信号は、それぞれ制御部10で制御される受波信号処理部12に入力される。
The transmission probe 1 is connected to a transmission signal generation unit 11 controlled by a control unit 10 and receives a transmission signal from the transmission signal generation unit 11 to generate an ultrasonic longitudinal wave. appear.
Lateral waves, upper end diffracted waves, lower end diffracted waves, and other ultrasonic waves generated by radiating longitudinal ultrasonic waves into the object 5 by the transmitting probe 1 are received by the receiving probe 2. Is done.
The received signals of the vertical longitudinal wave transducers a1... An constituting the array probe are input to received signal processing units 12 controlled by the control unit 10, respectively.

受波信号処理部12は、各々の垂直縦波振動子a1…anの受波信号から、本実施形態においては例えば上端回折波の受信信号をそれぞれ抽出し、抽出された受信信号の内で最大となる垂直縦波振動子を検出し、当該垂直縦波振動子の受信信号と識別番号を前記制御部10に伝達する。制御部10は当該垂直縦波振動子の受信信号と識別番号を記憶し、表示部15に表示する。制御部10では受信信号と識別番号を記憶するためのメモリなどの記憶部を備える。当該垂直縦波振動子が、アレイ探触子の受波面において前方(図3の左方)又は後方(図3の左方)の端部付近に位置する垂直縦波振動子である場合は、上端回折波の受信信号が対象物の表面5aにおいて最大となる位置が、アレイ探触子の受波面の外側に存する可能性がある。このときはアレイ探触子を前方(図3の左方)又は後方(図3の右方)に、アレイ探触子の受波面の前後の長さLに概ね相当する距離を移動してから、再度送受波を行う。   In this embodiment, the received signal processing unit 12 extracts, for example, the received signal of the upper end diffracted wave from the received signals of the vertical longitudinal wave transducers a1... An, and the maximum received signal is extracted. And the received signal and identification number of the vertical longitudinal wave vibrator are transmitted to the control unit 10. The control unit 10 stores the reception signal and identification number of the vertical longitudinal wave vibrator and displays them on the display unit 15. The control unit 10 includes a storage unit such as a memory for storing the received signal and the identification number. When the vertical longitudinal wave vibrator is a vertical longitudinal wave vibrator located near the front (left side in FIG. 3) or rear (left side in FIG. 3) end of the receiving surface of the array probe, There is a possibility that the position where the received signal of the upper-end diffracted wave is maximum on the surface 5a of the object exists outside the receiving surface of the array probe. At this time, the array probe is moved forward (leftward in FIG. 3) or backward (rightward in FIG. 3) by a distance approximately corresponding to the length L before and after the receiving surface of the array probe. Then, transmit and receive again.

上端回折波の受信信号の内で最大となった垂直縦波振動子の対象物表面における位置は、本実施形態では例えば、送波用探触子1から対象物の表面に沿って当該垂直縦波振動子a1…anに到達するラテラル波の伝搬時間に基づいて推定することができる。当該垂直縦波振動子a1…anの受波信号は、受波信号処理部12を経て探触子位置検出部13にも入力される。
探触子位置検出部13は、当該垂直縦波振動子の受波信号からラテラル波の受信信号を抽出し、送信信号とラテラル波の受信信号の間の時間差を測定する。この時間差から予め設定された送波用探触子1及び受波用探触子2内部での時間遅れを減じたものに、ラテラル波の伝搬速度(通常は対象物における縦波音速)を乗算することにより、送波用探触子1の入射点から当該垂直縦波振動子の入射点に至る距離が精確に算出される。すなわち、この実施形態では、受波信号処理部12と探触子位置検出部とによって本発明の位置測定手段が構成されている。
In the present embodiment, the position of the vertical longitudinal wave vibrator on the surface of the object, which is the largest among the received signals of the upper-end diffracted wave, is, for example, from the wave transmission probe 1 along the surface of the object. It can be estimated based on the propagation time of the lateral wave that reaches the wave transducers a1. The received signals of the vertical longitudinal wave transducers a 1... An are input to the probe position detecting unit 13 via the received signal processing unit 12.
The probe position detection unit 13 extracts a lateral wave reception signal from the reception signal of the vertical longitudinal wave vibrator, and measures a time difference between the transmission signal and the lateral wave reception signal. Multiply the time delay in the transmitter probe 1 and the receiver probe 2 set in advance from this time difference by the propagation speed of the lateral wave (usually the longitudinal sound velocity of the object). By doing so, the distance from the incident point of the transmission probe 1 to the incident point of the vertical longitudinal wave vibrator is accurately calculated. That is, in this embodiment, the received signal processing unit 12 and the probe position detecting unit constitute the position measuring means of the present invention.

一方、上端回折波を生じた欠陥の上端部6aの対象物中における位置は、例えば前述したように、送波用探触子1と受波用探触子2の間隔を一定に保ったまま図3の左右方向に探触子1、2を走査(B−走査)して、上端回折波の伝搬時間が極小になったときの両探触子のそれぞれの入射点位置の丁度中央の対象物中に、回折波を生じた欠陥6の上端部6aがあるとする方法によって推定することができる。すなわち、上記探触子1、2と探触子を走査(B−走査)した際に回折波の伝搬時間を測定する機器などによって本発明における対象物中における欠陥の端部位置を測定する手段が構成されている。本実施形態では、ラテラル波の伝搬時間に基づいて送波用探触子1と受波用探触子2の入射点間距離を精確に測定できるので、上端回折波を生じた欠陥6の上端部6aの位置も精確に推定できる特徴がある。   On the other hand, the position of the defect in which the upper end diffracted wave is generated in the object of the upper end portion 6a is, for example, as described above, while keeping the distance between the transmitting probe 1 and the receiving probe 2 constant. The probes 1 and 2 are scanned (B-scan) in the left-right direction in FIG. 3, and the object just at the center of each incident point position of both probes when the propagation time of the upper end diffracted wave is minimized. It can be estimated by a method in which an object has an upper end portion 6a of a defect 6 in which a diffracted wave is generated. That is, means for measuring the position of the end of the defect in the object according to the present invention by using a device for measuring the propagation time of the diffracted wave when the probes 1, 2 and the probe are scanned (B-scan). Is configured. In the present embodiment, since the distance between the incident points of the transmitting probe 1 and the receiving probe 2 can be accurately measured based on the propagation time of the lateral wave, the upper end of the defect 6 in which the upper end diffracted wave is generated is measured. There is a feature that the position of the portion 6a can also be accurately estimated.

上記の手順によって取得された、前記アレイ探触子のそれぞれの垂直縦波振動子の内で上端回折波の受信信号が最大となる垂直縦波振動子の対象物表面における位置と、該欠陥6の上端部6aの対象物5中における位置と、予め設定された欠陥の端部に入射した超音波によって生じる回折波の放射指向性によって定まる角度とによって演算部14が前記式(1)の計算を行い、算出された欠陥6の傾き角を表示部15に表示する。演算部14は、例えばCPUとこれを動作させるプログラムとによって構成することができる。   The position on the object surface of the vertical longitudinal wave transducer where the received signal of the upper-end diffracted wave becomes the maximum among the vertical longitudinal wave transducers of each of the array probes obtained by the above procedure, and the defect 6 The calculation unit 14 calculates the equation (1) based on the position of the upper end portion 6a of the object in the object 5 and the angle determined by the radiation directivity of the diffracted wave generated by the ultrasonic wave incident on the end of the defect set in advance. And the calculated tilt angle of the defect 6 is displayed on the display unit 15. The calculation unit 14 can be configured by, for example, a CPU and a program that operates the CPU.

なお本実施形態においては、欠陥の上端部に入射した超音波によって生じる上端回折波の受信信号を抽出して欠陥の傾き角を算出する例を示したが、欠陥の下端部に入射した超音波によって生じる下端回折波の受信信号を抽出して欠陥の傾き角を算出することも勿論同様に可能であり、両者を求めて平均値などによって欠陥の傾き角を算出することも可能である。   In the present embodiment, the example in which the received signal of the upper end diffracted wave generated by the ultrasonic wave incident on the upper end portion of the defect is extracted to calculate the inclination angle of the defect is shown, but the ultrasonic wave incident on the lower end portion of the defect is shown. Of course, it is also possible to calculate the tilt angle of the defect by extracting the received signal of the lower end diffracted wave generated by the above, and it is also possible to calculate the tilt angle of the defect based on an average value or the like by obtaining both.

なお、上記実施形態では、受波用探触子としてアレイ探触子を用いて受信信号が最大となる受波位置を、複数の垂直縦波振動子における受波信号分布によって求めたが、アレイ探触子を用いないで、受波用探触子を送波用探触子に対し前後に走査することで受信信号が最大となる受波位置を求めてもよい。この場合、受波用探触子の位置を外部のセンサによって検知したり、受波用探触子に位置情報を保持させる機構などを設けたりして本発明の位置測定手段を構成することができる。
さらに、本発明は上記実施形態の説明に限定されるものではなく、本発明の範囲内において適宜変更が可能である。
In the above-described embodiment, an array probe is used as the wave receiving probe, and the wave receiving position where the received signal is maximum is obtained from the wave receiving signal distribution in the plurality of vertical longitudinal wave transducers. Instead of using a probe, the wave receiving position where the received signal is maximized may be obtained by scanning the wave receiving probe back and forth with respect to the wave transmitting probe. In this case, the position measuring means of the present invention can be configured by detecting the position of the wave receiving probe with an external sensor or providing a mechanism for holding the position information in the wave receiving probe. it can.
Furthermore, the present invention is not limited to the description of the above embodiment, and can be appropriately changed within the scope of the present invention.

なお、上記実施形態では、受波用探触子で検出した受信信号が最大となる受波位置を求めたが、このときの受信信号は回折波の受波面に垂直な成分に対応したものになる。回折波が縦波の場合は、それぞれの受信信号に (Y+Z1/2/Z を乗じて回折波の伝搬方向に平行な成分を算出して、回折波の伝搬方向に平行な成分が最大となる受波位置を求めることによって、本発明による欠陥の傾き角の推定精度がさらに向上し得ることは勿論である。 In the above embodiment, the reception position where the reception signal detected by the reception probe is maximized is obtained, but the reception signal at this time corresponds to a component perpendicular to the reception surface of the diffracted wave. Become. When the diffracted wave is a longitudinal wave, each received signal is multiplied by (Y 2 + Z 2 ) 1/2 / Z to calculate a component parallel to the propagation direction of the diffracted wave, and parallel to the propagation direction of the diffracted wave. It goes without saying that the accuracy of estimation of the inclination angle of the defect according to the present invention can be further improved by obtaining the receiving position where the component is maximized.

以下に、本発明の一実施例を説明する。
本発明の超音波探傷方法を、対象物表面に垂直な高さD=5mmのスリット状の欠陥を内部に有する鋼製の対象物に実施した。送波用探触子には、周波数5MHzで公称屈折角60°の縦波斜角探触子を用い、受波用探触子には、同じく周波数5MHzで対象物表面に16個の垂直縦波振動をピッチ0.375mmでアレイ状に配設したアレイ探触子を使用した。
An embodiment of the present invention will be described below.
The ultrasonic flaw detection method of the present invention was carried out on a steel object having a slit-shaped defect having a height D = 5 mm perpendicular to the object surface. The transmission probe uses a longitudinal wave oblique angle probe with a frequency of 5 MHz and a nominal refraction angle of 60 °, and the reception probe also has 16 vertical longitudinal waves on the object surface at a frequency of 5 MHz. An array probe in which wave vibrations were arranged in an array with a pitch of 0.375 mm was used.

図4は、受波用のアレイ探触子を対象物の表面に沿って、1回毎にアレイ探触子の受波面の前後の長さL=6mmずつ移動させながら合計6回の送受波を行った結果の例である。アレイ探触子を形成する各々の垂直縦波振動子の受波信号から上端回折波の受信信号を抽出して、その信号電圧を対象物の表面における各々の垂直縦波振動子の位置の関数として、垂直縦波振動のピッチである0.375mmきざみでプロットした。同図における各々の垂直縦波振動子の位置は、送波用探触子と受波用探触子のそれぞれの入射点を結ぶ直線へ該欠陥の上端部から引いた法線からの距離、つまり図3におけるYで表示してある。図4から、上端回折波の受信信号が最大となる対象物表面における位置は、Ymax≒17mmであることが分かる。また欠陥の上端部から対象物の表面に配置した送波用探触子と受波用探触子のそれぞれの入射点を結ぶ直線までの距離は、Z=10mmであり、α=60°として式(1)に代入して計算した結果、下記のように欠陥の傾き角がほぼ正確に推定できた。
γ={tan−1(17/10)}− 60 ≒ − 0.5 (°)
FIG. 4 shows a total of six times of transmission / reception while moving the array probe for reception along the surface of the object by a length L = 6 mm before and after the reception surface of the array probe each time. It is an example of the result of having performed. The received signal of the upper end diffracted wave is extracted from the received signal of each vertical longitudinal wave transducer forming the array probe, and the signal voltage is a function of the position of each vertical longitudinal wave transducer on the surface of the object. As a result, the vertical longitudinal wave vibration pitch is plotted in increments of 0.375 mm. The position of each vertical longitudinal wave vibrator in the figure is the distance from the normal line drawn from the upper end of the defect to the straight line connecting the respective incident points of the transmitting probe and the receiving probe, That is, it is indicated by Y in FIG. From FIG. 4, it can be seen that the position on the surface of the object where the received signal of the upper-end diffracted wave is maximum is Ymax≈17 mm. The distance from the upper end of the defect to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object is Z = 10 mm, and α = 60 °. As a result of calculation by substituting into the equation (1), the inclination angle of the defect can be estimated almost accurately as follows.
γ = {tan −1 (17/10)} − 60≈−0.5 (°)

次に、本発明の他の実施例を説明する。
本発明の超音波探傷方法を、対象物表面への垂線から10°傾いた高さD=5mmのスリット状の欠陥を内部に有する鋼製の対象物に実施した。送波用探触子には、周波数5MHzで公称屈折角60°の縦波斜角探触子を用い、受波用探触子には、同じく周波数5MHzで対象物表面に16個の垂直縦波振動をピッチ0.375mmでアレイ状に配設したアレイ探触子を使用した。
Next, another embodiment of the present invention will be described.
The ultrasonic flaw detection method of the present invention was carried out on a steel object having a slit-like defect having a height D = 5 mm inclined at 10 ° from a perpendicular to the surface of the object. The transmission probe uses a longitudinal wave oblique angle probe with a frequency of 5 MHz and a nominal refraction angle of 60 °, and the reception probe also has 16 vertical longitudinal waves on the object surface at a frequency of 5 MHz. An array probe in which wave vibrations were arranged in an array with a pitch of 0.375 mm was used.

図5は、受波用のアレイ探触子を対象物の表面に沿って、1回毎にアレイ探触子の受波面の前後の長さL=6mmずつ移動させながら合計6回の送受波を行った結果の例である。アレイ探触子を形成する各々の垂直縦波振動子の受波信号から上端回折波の受信信号を抽出して、その信号電圧を対象物の表面における各々の垂直縦波振動子の位置の関数として、垂直縦波振動のピッチである0.375mmきざみでプロットした。同図における各々の垂直縦波振動子の位置は、送波用探触子と受波用探触子のそれぞれの入射点を結ぶ直線へ該欠陥の上端部から引いた法線からの距離、つまり図3におけるYで表示してある。図5から、上端回折波の受信信号が最大となる対象物表面における位置は、Ymax≒27mmであることが分かる。また欠陥の上端部から対象物の表面に配置した送波用探触子と受波用探触子のそれぞれの入射点を結ぶ直線までの距離は、Z=10mmであり、α=60°として式(1)に代入して計算した結果、下記のように欠陥の傾き角がほぼ正確に推定できた。
γ={tan−1(27/10)}− 60 ≒ 9.7 (°)
FIG. 5 shows a total of six times of transmission / reception while moving the array probe for reception along the surface of the object by a length L = 6 mm before and after the reception surface of the array probe each time. It is an example of the result of having performed. The received signal of the upper end diffracted wave is extracted from the received signal of each vertical longitudinal wave transducer forming the array probe, and the signal voltage is a function of the position of each vertical longitudinal wave transducer on the surface of the object. As a result, the vertical longitudinal wave vibration pitch is plotted in increments of 0.375 mm. The position of each vertical longitudinal wave vibrator in the figure is the distance from the normal line drawn from the upper end of the defect to the straight line connecting the respective incident points of the transmitting probe and the receiving probe, That is, it is indicated by Y in FIG. From FIG. 5, it can be seen that the position on the object surface where the received signal of the upper-end diffracted wave is maximum is Ymax≈27 mm. The distance from the upper end of the defect to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object is Z = 10 mm, and α = 60 °. As a result of calculation by substituting into the equation (1), the inclination angle of the defect can be estimated almost accurately as follows.
γ = {tan −1 (27/10)} − 60≈9.7 (°)

回折波の放射指向性を示すための測定具を示す図である。It is a figure which shows the measuring tool for showing the radiation directivity of a diffracted wave. 同じく、放射指向性の測定結果を示す図である。Similarly, it is a figure which shows the measurement result of radiation directivity. 本発明の一実施形態における超音波探傷を説明するための図である。It is a figure for demonstrating the ultrasonic flaw detection in one Embodiment of this invention. 本発明の一実施例における測定結果を示す図である。It is a figure which shows the measurement result in one Example of this invention. 本発明の他の実施例における測定結果を示す図である。It is a figure which shows the measurement result in the other Example of this invention. TOFD法を説明するための図である。It is a figure for demonstrating the TOFD method. 同じくTOFD法による受波信号を示す図である。It is a figure which similarly shows the received signal by TOFD method.

符号の説明Explanation of symbols

1 送波用探触子
2 受波用探触子
5 対象物
6 欠陥
10 制御部
11 送波信号発生部
12 受波信号処理部
13 探触子位置検出部
14 演算部
15 表示部
30 送波用探触子
30ab 入射点
31 受波用探触子
31ab 入射点
40 対象物
41 欠陥
41a 上端部
41b 下端部
50 試験片
51 疲労き裂
DESCRIPTION OF SYMBOLS 1 Probe for wave transmission 2 Probe for wave reception 5 Object 6 Defect 10 Control part 11 Transmission signal generation part 12 Received signal processing part 13 Probe position detection part 14 Calculation part 15 Display part 30 Transmission Probe 30ab incident point 31 wave receiving probe 31ab incident point 40 object 41 defect 41a upper end 41b lower end 50 test piece 51 fatigue crack

Claims (4)

対となる送波用探触子と受波用探触子を、対象物の表面に一定距離を隔てて配置し、前記送波用探触子から前記対象物中に超音波を放射し、該対象物中にき裂欠陥が存在する場合に該き裂欠陥の端部に入射した超音波によって生じる回折波を、前記受波用探触子で受信して対象物中に存在する前記き裂欠陥の端部の傾き角を推定する超音波探傷方法であって、
(1)前記き裂欠陥の端部の前記対象物中の位置を特定し、
(2)前記き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを求め、
(3)前記受波用探触子を前記送波用探触子の方向に前後走査したときの受信信号が最大となる前記受波用探触子の位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ該き裂欠陥の端部から引いた法線までの距離(Ymax)を求め、
(4)前記き裂欠陥の端部近傍の傾き角(γ)を以下の式によって推定することを特徴とする超音波探傷方法。
γ={tan −1 (Ymax/Z)}− 60°
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。
A transmitting probe and a receiving probe to be paired are arranged at a certain distance on the surface of the object, and an ultrasonic wave is emitted from the transmitting probe into the object. When there is a crack defect in the object, the diffraction wave generated by the ultrasonic wave incident on the end of the crack defect is received by the receiving probe and the crack is present in the object. An ultrasonic flaw detection method for estimating an inclination angle of an end of a crack defect,
(1) Identify the position of the end of the crack defect in the object,
(2) Find the distance Z from the end of the crack defect to a straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object,
(3) From the position of the receiving probe that maximizes the received signal when the receiving probe is scanned back and forth in the direction of the transmitting probe, the transmitting probe And the distance (Ymax) to the normal drawn from the end of the crack defect to the straight line connecting the respective incident points of the receiving probe,
(4) An ultrasonic flaw detection method characterized by estimating an inclination angle (γ) in the vicinity of the edge of the crack defect by the following equation.
γ = {tan −1 (Ymax / Z)} − 60 °
However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).
対となる送波用探触子と対象物表面に沿って複数の垂直縦波振動子をアレイ状に配設した受波用探触子を、前記対象物の表面に一定距離を隔てて配置し、前記送波用探触子から前記対象物中に超音波を放射し、該対象物中にき裂欠陥が存在する場合に該き裂欠陥の端部に入射した超音波によって生じる回折波によって前記対象物表面に発生する垂直応力成分を、該アレイ探触子の複数の垂直縦波振動子によりそれぞれ受波して対象物中に存在する前記き裂欠陥の端部の傾き角を推定する超音波探傷方法であって、A pair of wave transmitting probes and a wave receiving probe in which a plurality of vertical longitudinal wave transducers are arranged in an array along the surface of the object are arranged at a certain distance on the surface of the object. And diffracted waves generated by the ultrasonic waves radiated from the transmitting probe into the object and incident on the edge of the crack defect when the defect exists in the object. The vertical stress component generated on the surface of the object is received by a plurality of vertical longitudinal wave transducers of the array probe, and the inclination angle of the edge of the crack defect existing in the object is estimated. An ultrasonic flaw detection method,
(1)前記き裂欠陥端部の前記対象物中の位置を特定し、  (1) Identify the position of the crack defect end in the object,
(2)前記き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを求め、  (2) Find the distance Z from the end of the crack defect to a straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object,
(3)それぞれの前記垂直縦波振動子の内で前記回折波の受信信号が最大となる垂直縦波振動子の前記対象物表面における位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ該き裂欠陥の端部から引いた法線までの距離(Ymax)を求め、  (3) From the position on the surface of the object of the vertical longitudinal wave vibrator where the received signal of the diffracted wave is maximum among each of the vertical longitudinal wave vibrators, the transmitting probe and the receiving wave Find the distance (Ymax) to the normal line drawn from the end of the crack defect to the straight line connecting each incident point of the probe,
(4)前記き裂欠陥の端部の傾き角(γ)を以下の式によって推定することを特徴とする超音波探傷方法。  (4) An ultrasonic flaw detection method characterized in that an inclination angle (γ) of an end portion of the crack defect is estimated by the following equation.
γ={tan    γ = {tan −1-1 (Ymax/Z)}− 60°(Ymax / Z)}-60 °
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。  However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).
対象物中に存在するき裂欠陥の端部の傾き角を超音波探傷法を用いて推定する超音波探傷装置であって、An ultrasonic flaw detection apparatus that estimates an inclination angle of an end of a crack defect existing in an object using an ultrasonic flaw detection method,
(1)前記対象物中に超音波を放射する送波用探触子と、  (1) a transmission probe that emits ultrasonic waves into the object;
(2)前記き裂欠陥の端部に入射した超音波によって生じる回折波を受波する受波用探触子と、  (2) a wave receiving probe for receiving a diffracted wave generated by an ultrasonic wave incident on an end of the crack defect;
(3)前記き裂欠陥端部の前記対象物中の位置を特定し、該き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを測定する手段と、  (3) The position of the crack defect end in the object is specified, and the transmitting probe and the receiving probe arranged on the surface of the object from the end of the crack defect Means for measuring a distance Z to a straight line connecting each incident point of the child;
(4)前記受波用探触子を前記送波用探触子の方向に前後走査したときの受信信号が最大となる前記受波用探触子の位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ前記き裂欠陥の端部から引いた法線までの距離(Ymax)を求める位置測定手段と、(4) From the position of the receiving probe that maximizes the received signal when the receiving probe is scanned back and forth in the direction of the transmitting probe, the transmitting probe And a position measuring means for obtaining a distance (Ymax) to a normal line drawn from the end of the crack defect to a straight line connecting the respective incident points of the receiving probe;
(5)前記測定する手段で求められた距離Zと、前記位置測定手段で得られた距離Ymaxを用いて、以下の式によって欠陥の端部近傍の傾き角(γ)を算出する演算部を設けたことを特徴とする超音波探傷装置。(5) Using the distance Z obtained by the measuring means and the distance Ymax obtained by the position measuring means, an arithmetic unit for calculating the inclination angle (γ) near the edge of the defect by the following equation: An ultrasonic flaw detector provided.
γ={tan    γ = {tan −1-1 (Ymax/Z)}− 60°(Ymax / Z)}-60 °
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。  However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).
対象物中に存在するき裂欠陥の端部の傾き角を超音波探傷法を用いて推定する超音波探傷装置であって、An ultrasonic flaw detection apparatus that estimates an inclination angle of an end of a crack defect existing in an object using an ultrasonic flaw detection method,
(1)前記対象物中に超音波を放射する送波用探触子と、  (1) a transmission probe that emits ultrasonic waves into the object;
(2)前記対象物表面に沿って複数の垂直縦波振動子がアレイ状に配設され、前記き裂欠陥の端部に入射した超音波によって生じる回折波によって前記対象物表面に発生する垂直応力成分を、前記複数の垂直縦波振動子によりそれぞれ受波する受波用探触子と、  (2) A plurality of vertical longitudinal wave vibrators arranged in an array along the surface of the object, and vertical generated on the surface of the object by a diffracted wave generated by an ultrasonic wave incident on an end of the crack defect A receiving probe for receiving a stress component by each of the plurality of vertical longitudinal wave vibrators;
(3)前記き裂欠陥端部の前記対象物中の位置を特定し、該き裂欠陥の端部から前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線への距離Zを測定する手段と、  (3) The position of the crack defect end in the object is specified, and the transmitting probe and the receiving probe arranged on the surface of the object from the end of the crack defect Means for measuring a distance Z to a straight line connecting each incident point of the child;
(4)それぞれの前記垂直縦波振動子の内で前記回折波の受信信号が最大となる垂直縦波振動子の対象物表面における位置から、前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ該き裂欠陥の端部から引いた法線までの距離(Ymax)を求める位置測定手段と、(4) From the position on the object surface of the vertical longitudinal wave transducer where the received signal of the diffracted wave is maximum among each of the vertical longitudinal wave transducers, the transmitting probe and the receiving probe are A position measuring means for obtaining a distance (Ymax) to a normal line drawn from the end of the crack defect to a straight line connecting the respective incident points of the transducer;
(5)前記測定する手段で求められた距離Zと、前記位置測定手段で得られた距離Ymaxを用いて、以下の式によってき裂欠陥の端部の傾き角(γ)を算出する演算部を設けたことを特徴とする超音波探傷装置。(5) An arithmetic unit that calculates the inclination angle (γ) of the edge of the crack defect by the following formula using the distance Z obtained by the measuring means and the distance Ymax obtained by the position measuring means An ultrasonic flaw detector characterized by comprising:
γ={tan    γ = {tan −1-1 (Ymax/Z)}− 60°(Ymax / Z)}-60 °
ただし、γは、前記対象物の表面に配置した前記送波用探触子と前記受波用探触子のそれぞれの入射点を結ぶ直線へ引いた法線に対する前記き裂欠陥端部の傾き角(受波用探触子側への傾きを正とする)である。  However, γ is the inclination of the crack defect end with respect to the normal line drawn to the straight line connecting the incident points of the transmitting probe and the receiving probe arranged on the surface of the object. The angle (the inclination toward the receiving probe side is positive).
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