method and device for non-destructive ultrasonic testing of a metal part or weld bead

Abstract

Method and Device for Non-Destructive Ultrasonic Inspection of a Metal Part or Weld Bead. The invention relates to a method and device for non-destructive ultrasonic inspection of a metal part or weld bead. The device (2) moves along the inspected area (Z) and consists of a transmitting transducer (E1, E2) positioned on one side of the inspected area and two receiving transducers (R1, R2) positioned on the opposite side. The position of each end of a defect is determined by a geometric intersection between two ellipses comprising a first ellipse associated with a first acquisition group and whose foci correspond to the position of the transmitting transducer and one of the two receiving transducers, and a second ellipse associated with a second acquisition group and whose foci correspond to the position of the transmitting transducer and the other receiving transducer. Figure for the abstract: Fig. 1.

Description

Title of the invention: method and device for non-destructive ultrasonic testing of a metal part or a weld bead Technical field

[0001] The present invention relates to the general field of non-destructive ultrasonic testing. More specifically, it relates to a method for examining a metal part or a weld bead deposited in a chamfer formed between two metal parts in order to characterize a possible defect present in the area being tested. Prior art

[0002] Non-destructive ultrasonic examination known as TOFD (for "Time of Flight Diffraction" in English) is a control technique known per se. Its detection principle is based on scanning a part to be inspected using a pair of highly divergent transmitter and receiver transducers which are mounted face to face on the part, then viewing on a B-scan type graphic representation the diffraction and reflection echoes generated by any defects in the inspected part.

[0003] Compared to a conventional ultrasound or radiographic examination, this TOFD technique has many advantages. In particular, it allows high detection sensitivity with low sensitivity to the orientation of the reflectors. In addition, this technique has an implementation that is easy and requires little skill from the operators. Its speed of execution and analysis and the precision of its measurements are also remarkable.

[0004] However, despite its many advantages, the TOFD technique has a certain number of drawbacks which hinder its implementation on an industrial scale.

[0005] Indeed, the high detection sensitivity of TOFD technique control can lead to detecting defects that are not noticeable in the context of a conventional ultrasonic examination. In addition, its implementation can be complex on materials with a coarse crystalline structure and is limited to sheets and assemblies welded together. In addition, with the TOFD technique, the detection zones are limited to the proximity of the surface of the part being tested. Finally, this technique presents problems of locating the defect in depth and in relation to the axis of the TOFD device (the precise location of the defect is only possible by using a complementary ultrasonic examination targeted at the right of the detected reflector).

[0006] Also known from publication EP 2,605,009 is a hybrid ultrasonic testing technique combining a multi-element ultrasonic transmitter translator with a conventional, highly damped monolithic receiver translator. Compared to the TOFD technique, the method described in this publication allows for improved fault location and dimensioning. However, this method has the disadvantage of requiring extremely high costs for the control electronics required for its implementation and due to the complexity of developing the software for analyzing the acquisition data. Statement of the invention

[0007] The main aim of the present invention is therefore to propose a method for non-destructive ultrasonic testing of a metal part or a weld bead which does not have the aforementioned drawbacks.

[0008] This aim is achieved by means of a method for non-destructive ultrasonic testing of a metal part or a weld bead deposited in a chamfer formed between two metal parts, the method comprising, from an acquisition device moving along the controlled area and composed of at least one transmitting transducer positioned on one side of the controlled area and two receiving transducers positioned on the opposite side of the controlled area: - the emission by the transmitting transducer of longitudinal ultrasonic waves towards the controlled zone, and the reception of ultrasonic data by each of the two receiving transducers so as to form a first and a second distinct acquisition group; - determination of the geometric position of two ends of a defect on a sectional view of the controlled area from a representation of the ultrasonic data of the two acquisition groups; - and in which, in accordance with the invention, the geometric position of each end of the defect is determined by a geometric intersection between at least two ellipses comprising a first ellipse associated with the first acquisition group and whose foci correspond to the position of the emitting translator and one of the two receiving translators, and a second ellipse associated with the second acquisition group and whose foci correspond to the position of the emitting translator and the other receiving translator.

[0009] The method according to the invention is remarkable in that it makes it possible to characterize a defect in the controlled area by its nature, its type, its position, its dimensions and its orientation, while overcoming the limitations linked to the TOFD technique (in particular in terms of localization of the indications) and without impacting the examination times. Indeed, the ultrasound data collected by the method allow the reconstruction of the defects on a sectional view, and the precise quantification of the localization and sizing parameters, evaluation of the residual ligaments, height and orientation of defects.

[0010] Due to its ease of implementation and its low sensitivity to the dexterity of the operators, the invention makes it possible to effectively replace contractual manual ultrasound examinations and complementary ultrasonic characterization examinations while guaranteeing precise in-service monitoring of the indications (recording of acquisition and characterization data).

[0011] In particular, the method according to the invention makes it possible to precisely locate the “head” and “foot” components of the defect. These locations are known precisely, which makes it possible to precisely determine the vertical height of the defect, its depth, and its orientation.

[0012] Preferably, the geometric equation of each of the ellipses in a reference frame (x,y) on the sectional view of the controlled zone is given by: (x2 / a2) + (y2 / b2) = 1; in which: - the semi-major axis “a” is a function of: • the measurement of the time of flight of the component of one end of the observed defect, • the measurement of the flight time between the transmitting transducer and the receiving transducer considered, and • ultrasonic speed in the controlled area - the semi-minor axis “b” is a function of the major axis “a” and the distance measured between the transmitting transducer and the receiving transducer considered.

[0013] In this case, the semi-major axis “a” is given by the following equation:

[0014] [Math.l] _ {Tv-TvQLyCOL a- 2

[0015] in which “Tv” is the measurement of the time of flight of the component of a chosen end of the observed defect, “TvOL” is the measurement of the time of flight between the emitting transducer and the receiving transducer considered, and “C0L” is the ultrasonic speed in the controlled zone.

[0016] Still in this case, the semi-minor axis “b” is given by the following equation:

[0017] [Math.2] b - \]a2 - c 2

[0018] in which “a” is the semi-major axis and “c” is the half focal length of the ellipse considered.

[0019] According to one embodiment, the acquisition device is composed of two separate transmitter translators and two separate receiver translators so as to form four separate acquisition groups.

[0020] Preferably, the method further comprises determining the dimensions and the orientation of the defect observed on the sectional view of the controlled area from the geometric positions of the two ends of the observed defect.

[0021] Also preferably, the transmitting translator transmits longitudinal waves at a frequency between 1 and 15 MHz.

[0022] The invention also relates to a device for implementing the method as defined above, comprising at least one transmitting translator intended to be positioned on one side of the observed controlled zone and two receiving translators intended to be positioned on the opposite side of the controlled zone, the translators being mounted on the same rod moving along the chamfer.

[0023] The device may comprise two separate transmitter translators and two separate receiver translators. Brief description of the drawings

[0024] [Fig-1] [Fig.l] is a schematic view of an example of a device for the implementation implementation of the non-destructive ultrasonic testing method according to the invention.

[0025] [Fig.2] [Fig.2] is an illustration of the principle of implementation of the non-destructive ultrasonic testing method according to the invention.

[0026] [Fig.3] [Fig.3] schematically illustrates an example of implementation of the method according to the invention with two acquisition groups.

[0027] [Fig.4] [Fig.4] schematically illustrates another example of implementation of the method according to the invention with four acquisition groups.

[0028] [Fig.5] [Fig.5] schematically illustrates an example of characterization of a defect using the method according to the invention with four acquisition groups. Description of the embodiments

[0029] The invention relates to a non-destructive ultrasound examination solution making it possible to replace contractual manual ultrasound examinations and complementary ultrasonic characterization examinations while guaranteeing precise in-service monitoring of the detected indications.

[0030] This solution applies to the ultrasonic volumetric examination of the welded volume and the heat-affected zone of the base metal of butt-welded assemblies of forged sheets of low-alloy steel. It also applies to the ultrasonic volumetric examination of the base metal of forged sheets of low-alloy or austenitic steel, and also to the ultrasonic volumetric examination of welds for the installation of tappings or tube / accessory assemblies when the geometry of the assembly and the location of the monitored zone allow it.

[0031] This solution is implemented in particular using a non-destructive ultrasonic testing device such as that shown in [Fig.l].

[0032] This device 2 comprises a set of three or four high-sensitivity translators- sibility and very highly damped.

[0033] As a reminder, a translator is an electroacoustic device generally comprising one or more transducers intended for the emission or reception of ultrasonic waves. A transducer is an active element of a translator allowing the conversion of electrical energy into acoustic energy (and vice versa).

[0034] More precisely, the device 2 according to the invention comprises, in the exemplary embodiment of [Fig.l], two transmitter translators E1, E2, and two receiver translators R1, R2.

[0035] This embodiment of the device of [Fig.l] relates to a configuration with four acquisition groups. In another embodiment, the device comprises two acquisition groups consisting of a single transmitter translator El and two receiver translators RI, R2.

[0036] The transmitting translators E1, E2 are designed to generate longitudinal waves with a refraction angle a in low-alloy steel equal to 35, 45, 60 or 70°. Their transmission frequency is advantageously between 1 and 15 MHz.

[0037] The translators E1, E2, R1, R2 are secured by a linkage system consisting of two stainless steel rods 4 to ensure their alignment and tightening knobs 6 to fix the translators on the linkage and to adjust the distances E1-R1, E2-R2, E2-R1 and E1-R2.

[0038] In practice, the translators E1, E2, R1, R2 are positioned on the same face of the part to be controlled 8 on either side of the zone to be controlled Z (the emitting translators being positioned on the same side of the zone to be controlled and the receiving translators being positioned on the other side). For example, as shown in [Fig.l], the zone to be controlled Z can be a weld bead deposited in a chamfer formed between two metal parts.

[0039] The translators E1, E2, R1, R2 are then moved along the area to be controlled in a sweeping movement (back and forth).

[0040] The device according to the invention also comprises a computer processing system (not shown in the figures) for the collected ultrasound data. Typically, this processing system consists of specific acquisition electronics, a touch-screen computer with a high-definition screen, specific acquisition software, and specific analysis software.

[0041] The acquisition electronics of this computer processing system make it possible to control the device so as to recover the ultrasonic data from each transmitter translator E1, E2 to each of the receiver translators R1, R2.

[0042] The computer of the computer processing system has sufficient computing power to process the encoded signals from the different acquisition groups. The resolution of its screen will be sufficient to allow the vi standardization of all sectional views (called “B-scan”).

[0043] The specific acquisition software has been developed to allow the operator to configure the device (by adjusting the ultrasonic speed, the ultrasonic speed, the frequency of the translators, etc., but also by defining the number of acquisition groups, by adjusting the position of the translators, etc.).

[0044] The specific acquisition software is presented in the form of a software solution that is based around a Desktop-type application that interacts with the operator through a graphical environment (HMI). It collects ultrasound data from the acquisition card via a native library provided by the manufacturer. The collected data is organized and stored in a fixed SQLite-type database.

[0045] The specific analysis software was developed to enable the acquisition data to be reread and the position, orientation and precise dimensions of the defects to be determined on a sectional view of the part being inspected (with a representation of the chamfer in the case of a welded assembly).

[0046] The operator will use three cursors located in XY on the B-scan sectional view of each acquisition group (with “X” the position of the transmitter / receiver translator pair on the part and “Y” the time of flight), namely:

[0047] A cursor OL for measuring the time of flight of the lateral wave propagating in a straight line between the emergence points El and R2.

[0048] A cursor S for measuring the time of flight TvS of the “head” (or top) component of the observed defect.

[0049] A cursor P for measuring the time of flight TvP of the “foot” component of the observed defect.

[0050] As shown in [Fig.2], we consider by: TvOL the time of flight between the emitting pellet PE1 and the receiving pellet PR2 measured on the B-scan sectional view of the analysis software using the cursor OL, and by TvS or TvP the times of flight PE1-M-PR2 measured on the B-scan sectional view of the analysis software using the cursors S or P depending on the component studied of the defect (namely head or foot).

[0051] Knowing that the geometric equation of an ellipse in a (x,y) frame of reference on the B-scan sectional view of the controlled area is given by the general equation:

[0052] [Math.3]

[0053] In this equation, "a" corresponds to the semi-major axis of the ellipse, and "b" corresponds to the semi-minor axis of the ellipse.

[0054] It is then possible to draw two ellipses (one relating to the “head” component of the defect, and the other relating to its “foot” component) whose foci correspond to the position of the transmitter translator El and one of the two receiver translators (in the example of [Fig.2] this is the receiver translator R2).

[0055] The ellipse relating to the “head” component of the defect is plotted using the equation above with the value for the semi-major axis “a” given by the equation below:

[0056] [Math.4] (Ti-ST vOL)xCol £l = - 2 ~

[0057] Where “TvS” is the PE1-M-PR2 time of flight measured on the B-scan sectional view of the analysis software using the S cursor, and “C0L” is the ultrasonic velocity in the controlled area.

[0058] As for the value of the semi-minor axis “b” of the ellipse, it is given by the following equation:

[0059] [Math.5] b^a2-c2

[0060] In which “a” corresponds to the semi-major axis of the ellipse, and “c” corresponds to the half focal length of the ellipse, namely half the distance physically measured between the emitting translator El and the receiving translator R2 (in the example of [Fig.2]).

[0061] The ellipse relating to the “foot” component of the defect is plotted using the equation above with the value for the semi-major axis “a” given by the equation below:

[0062] [Math.6] _ iTvP-TvOLyçOL

[0063] Where “TvP” is the PE1-M-PR2 time of flight measured on the B-scan sectional view of the analysis software using the P cursor, and “Col” is the ultrasonic speed in the controlled area. As for the value of the semi-minor axis “b” of the ellipse, it is given by equation 5 above.

[0064] Thus, in the case of an acquisition device with two acquisition groups (namely a single transmitter translator El and two receiver translators RI, R2), the time-of-flight measurements carried out with the cursors OL, S and P make it possible to trace two distinct ellipses el, e2 for each of the components studied of the defect (namely head or foot).

[0065] [Fig.3] represents such an example with two acquisition groups.

[0066] In this example, the ellipse el was drawn by considering the “head” component of the defect (see equation 4 above) and from the acquisition group formed by the transmitter translator El and the receiver translator R2. Still in this example, the ellipse e2 was drawn from the acquisition group formed by the transmitter translator El and the receiver translator RI (still considering the component “head” of the defect).

[0067] The two ellipses el, e2 have two points of intersection, namely a first point 1-1 positioned inside the part to be checked 8, and a second point 1-2 positioned outside it.

[0068] The intersection point 1-1 positioned inside the part to be checked 8 thus corresponds to the position of the head of the defect.

[0069] The same plot of two ellipses is carried out for the “foot” component of the defect (see equation 6 above).

[0070] In the case of an acquisition device with four acquisition groups (namely two transmitting translators El, E2 and two receiving translators RI, R2), the time-of-flight measurements carried out with the cursors OL, S and P make it possible to plot for each of the components studied of the defect (namely head or foot) between two and four distinct ellipses el to e4 depending on the acquisition groups retained (namely the following groups: El-Rl, E2-R2, E2-R1, and E1-R2).

[0071] [Fig.4] shows such an example with four acquisition groups in which four ellipses e1 to e4 are drawn for the "head" component of the defect, namely an ellipse e1 for the acquisition group E1-R1, an ellipse e2 for the acquisition group E2-R2, an ellipse e3 for the acquisition group E2-E1 and an ellipse e4 for the acquisition group E1-R2.

[0072] As shown in [Fig.4], these four ellipses e1 to e4 have two points of intersection, namely a first point J1 positioned inside the part to be checked 8, and a second point J-2 positioned outside it.

[0073] The intersection point Jl positioned inside the part to be checked 8 corresponds to the position of the head of the defect.

[0074] The same plot of four ellipses is carried out for the “foot” component of the defect (see equation 6 above).

[0075] It will be noted that when the location of the defect component is carried out by considering more than two ellipses (as in the example of [Fig.4]), the points of intersection of the different ellipses may, due to uncertainties in time-of-flight measurements, not be perfectly coincident. In this case, the barycenter of the identified points of intersection will be retained.

[0076] Once the position of the foot and the position of the top of the defect have been identified, the dimensions and orientation of the defect observed on the sectional view of the controlled area can be easily defined by connecting the foot and top positions of the defect.

[0077] [Fig.5] thus represents an example of implementation of this method for characterizing a defect 10 observed in a control zone Z of a part to be controlled 8.

[0078] In this example, the acquisition device has two acquisition groups (namely with a single transmitter translator El for two receiver translators RI, R2).

[0079] In this figure, two ellipses el, e2 have been determined and plotted by considering the “head” component of the defect (the ellipse el is relative to the acquisition group El-RI, while the ellipse e2 is relative to the acquisition group E1-R2). The intersection of these two ellipses el, e2 made it possible to determine the position of the head 10-1 of the defect 10.

[0080] Similarly, two ellipses e' 1, e'2 were determined and plotted considering the "foot" component of the defect (ellipse e' 1 is relative to acquisition group El-Rl, while ellipse e'2 is relative to acquisition group E1-R2). The intersection of these two ellipses e' 1, e'2 made it possible to determine the position of the foot 10-2 of the defect 10.

[0081] By connecting points 10-1 and 10-2 together, it is then possible to obtain the dimensions and orientation of the defect 10 observed in the sectional view of the controlled zone Z.

Claims

Claims

1. A method for non-destructive ultrasonic testing of a metal part or a weld bead deposited in a chamfer formed between two metal parts, the method comprising, from an acquisition device (2) moving along the controlled zone (Z) and composed of at least one emitting transducer (El, E2) positioned on one side of the controlled zone (Z) and two receiving transducers (RI, R2) positioned on the opposite side of the controlled zone: - the emission by the emitting transducer of longitudinal ultrasonic waves in the direction of the controlled zone, and the reception of ultrasonic data by each of the two receiving transducers so as to form a first and a second distinct acquisition group, - the determination of the geometric position of two ends (10-1, 10-2) of a defect (10) on a sectional view of the controlled zone from a representation of the ultrasonic data of the two acquisition groups,- characterized in that the geometric position of each end (10-1, 10-2) of the defect (10) is determined by a geometric intersection between at least two ellipses (el, e2) comprising a first ellipse associated with the first acquisition group and whose foci correspond to the position of the emitting translator and one of the two receiving translators, and a second ellipse associated with the second acquisition group and whose foci correspond to the position of the emitting translator and the other receiving translator.,

2. Method according to claim 1, in which the geometric equation of each of the ellipses (el, e2) in a reference frame (x,y) on the sectional view of the controlled zone is given by: (x2 / a2) + (y2 / b2) = 1; in which: - the semi-major axis “a” is a function of: • the measurement of the time of flight of the component of one end of the observed defect, • the measurement of the time of flight between the emitting transducer and the receiving transducer considered, and • the ultrasonic speed in the controlled zone - the semi-minor axis “b” is a function of the major axis “a” and the distance measured between the transmitting transducer and the receiving transducer considered.

3. Method according to claim 2, in which the semi-major axis "a" is given by the following equation: [Math.7] (Tv-TVQLyçOL a— 2 in which "Tv" is the measurement of the time of flight of the component of a chosen end of the observed defect, "TvOL" is the measurement of the time of flight between the emitting transducer and the receiving transducer considered, and "C0L" is the ultrasonic speed in the controlled zone.

4. Method according to one of claims 2 and 3, in which the semi-minor axis "b" is given by the following equation: [Math. 8] b = ^a2 - c 2 in which "a" is the semi-major axis and "c" is the half focal length of the ellipse considered.

5. Method according to any one of claims 1 to 4, in which the acquisition device (2) is composed of two separate transmitter translators (El, E2) and two separate receiver translators (RI, R2) so as to form four separate acquisition groups.

6. A method according to any one of claims 1 to 5, further comprising determining the dimensions and orientation of the defect (10) observed in the sectional view of the inspected area from the geometric positions of the two ends of the observed defect.

7. A method according to any one of claims 1 to 6, wherein the transmitting translator transmits longitudinal waves at a frequency between 1 and 15 MHz.

8. Device for implementing the method according to any one of claims 1 to 7, comprising at least one transmitting translator intended to be positioned on one side of the observed controlled area and two receiving translators intended to be positioned on the opposite side of the controlled area, the translators being mounted on the same rod moving along the chamfer.

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