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 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 any defect present in the inspected area. Previous technique

[0002] Non-destructive ultrasonic testing, known as TOFD (for "Time of Flight Diffraction"), is a well-known inspection technique. Its detection principle is based on scanning a part to be inspected using a pair of highly divergent transmitter and receiver transducers mounted opposite each other on the part, and then visualizing the diffraction and reflection echoes generated by any defects in the inspected part on a B-scan type graphic representation.

[0003] Compared to conventional ultrasonic or radiographic examination, this TOFD technique offers numerous advantages. In particular, it provides high detection sensitivity with low sensitivity to reflector orientation. Furthermore, this technique is easy to implement and requires little operator skill. Its speed of execution and analysis, as well as the accuracy of its measurements, are also noteworthy.

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

[0005] Indeed, the high detection sensitivity of TOFD (Total-Oriented Fault Detection) can lead to the detection of defects that would not be noticeable during conventional ultrasonic testing. Furthermore, its implementation can be complex on materials with a coarse crystalline structure and is limited to sheets and welded assemblies. In addition, with TOFD, the detection zones are limited to the vicinity of the surface of the part being inspected. Finally, this technique presents problems in locating the defect both in depth and relative to the axis of the TOFD device (precise defect localization is only possible by using a complementary ultrasonic examination focused on the detected reflector).

[0006] A hybrid ultrasonic control technique combining a multi-element ultrasonic transmitter transducer with a conventional, highly damped monolithic receiver transducer is also known from publication EP 2,605,009. Compared to the The TOFD technique, the method described in this publication, improves the localization and sizing of defects. However, this method has the drawback of requiring extremely high costs for the control electronics necessary for its implementation and due to the complexity of developing the software for analyzing the acquisition data. Description of the invention

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

[0008] This goal is achieved by means of a non-destructive ultrasonic inspection method for a metal part or weld bead deposited in a chamfer formed between two metal parts, the method comprising, from an acquisition device moving along the area being inspected and composed of at least one transmitting transducer positioned on one side of the area being inspected and two receiving transducers positioned on the opposite side of the area being inspected: - the emission by the transmitting translator of longitudinal ultrasonic waves towards the controlled area, and the reception of ultrasonic data by each of the two receiving translators so as to form a first and a second distinct acquisition group; - the determination of the geometric position of two ends of a defect on a cross-sectional view of the controlled area from a representation of the ultrasonic data from the two acquisition groups; - and in which, according to 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 transmitting 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 transmitting translator and the other receiving translator.

[0009] The method according to the invention is remarkable in that it allows a defect in the controlled area to be characterized by its nature, type, position, dimensions, and orientation, while overcoming the limitations associated with the TOFD technique (particularly in terms of localizing the indications) and without impacting examination times. Indeed, the ultrasonic data collected by the method allows for the reconstruction of the defects on a cross-sectional view and precise quantification. parameters for location and dimensioning, evaluation of residual ligaments, height and orientation of defects.

[0010] Due to its ease of implementation and its low sensitivity to operator dexterity, the invention makes it possible to effectively replace contractual manual ultrasound examinations and complementary ultrasound characterization examinations while ensuring precise in-service monitoring of 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 with precision, which makes it possible to accurately determine the vertical height of the defect, its depth, and its orientation.

[0012] Preferably, the geometric equation of each of the ellipses in a coordinate system (x,y) on the cross-sectional view of the controlled area is given by: (x² / a²) + (y² / b²) = 1; where: - the semi-major axis "a" is a function of: • the measurement of the flight time of the component at one end of the observed defect, • the measurement of the time of flight between the transmitting transducer and the receiving transducer in question, and • the 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-TvOL)xCol a- 2 “

[0015] in which "Tv" is the time-of-flight measurement of the component of a chosen end of the observed defect, "TvOL" is the time-of-flight measurement between the transmitting transducer and the receiving transducer considered, and "C0L" is the ultrasonic velocity in the controlled area.

[0016] In this case, the semi-minor axis "b" is given by the following equation:

[0017] [Math.2] b = ^-c 2

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

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

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

[0021] Preferably also, the transmitting translator emits 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 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.

[0023] The device may include two separate transmitting translators and two separate receiving translators. Brief description of the drawings

[0024] [Fig-1] Fig. 1 is a schematic view of an example of a device for the setting 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 defect characterization using the method according to the invention with four acquisition groups. Description of embodiments

[0029] The invention relates to a non-destructive ultrasound examination solution that can replace contractual manual ultrasound examinations and complementary ultrasound characterization examinations while ensuring precise in-service monitoring of 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 low-alloy steel forgings. It also applies to the ultrasonic volumetric examination of the base metal of low-alloy or austenitic steel forgings, and furthermore to the ultrasonic volumetric examination of branch connection welds or tube / fitting assemblies when the geometry of the assembly and the location of the monitored area allow it.

[0031] This solution is implemented in particular by means of a non-destructive ultrasonic testing device such as that shown in [Fig.1].

[0032] This device 2 comprises a set of three or four highly sensitive and very heavily damped translators.

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

[0034] More specifically, the device 2 according to the invention comprises, in the example embodiment of [Fig.1], two transmitting translators El, E2, and two receiving translators RI, R2.

[0035] This embodiment of the device in [Fig. 1] relates to a configuration with four acquisition groups. In another embodiment, the device comprises two acquisition groups consisting of a single transmitting translator E1 and two receiving translators R1, R2.

[0036] The El, E2 transmitter transducers are designed to generate longitudinal waves with a refraction angle α in low-alloy steel of 35, 45, 60 or 70°. Their emission frequency is advantageously between 1 and 15 MHz.

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

[0038] In practice, the transducers E1, E2, RI, R2 are positioned on the same face of the part to be inspected 8 on either side of the area to be inspected Z (the transmitting transducers being positioned on one side of the area to be inspected and the receiving transducers being positioned on the other side). For example, as shown in [Fig. 1], the area to be inspected Z can be a weld bead deposited in a chamfer formed between two metal parts.

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

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

[0041] The acquisition electronics of this computer processing system allows the device to be controlled so as to recover the ultrasonic data from each transmitter translator El, E2 to each of the receiver translators RI, R2.

[0042] The computer in 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 viewing of all the cross-sectional views (known as "B-scan").

[0043] The specific acquisition software was 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 a software solution based on a desktop application that interacts with the operator via a graphical user interface (GUI). It collects ultrasound data from the acquisition card using a native library provided by the manufacturer. The collected data is organized and stored in a fixed SQLite database.

[0045] The specific analysis software was developed to allow the acquisition data to be read and the precise position, orientation and dimensions of the defects to be determined on a cross-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 cross-sectional view of each acquisition group (with "X" the position of the transmitter / receiver transducer pair on the part and "Y" the time of flight), namely:

[0047] A slider 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 apex) component of the observed defect.

[0049] A slider P for measuring the time of flight TvP of the "foot" component of the observed defect.

[0050] As shown in [Fig.2], TvOL is considered to be the time of flight between the emitting pad PE1 and the receiving pad PR2 measured on the B-scan cross-sectional view of the analysis software using the OL cursor, and TvS or TvP are the PE1-M-PR2 flight times measured on the B-scan cross-sectional view of the analysis software using the S or P cursors depending on the component of the defect being studied (namely head or foot).

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

[0052] [Math.3] S+p = 1

[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 transmitting translator El and one of the two receiving translators (in the example of [Fig.2] it is the receiving translator R2).

[0055] The ellipse relating to the "head" component of the defect is drawn using the above equation with the value for the semi-major axis "a" given by the following equation:

[0056] [Math.4] (TvS-TvOL)kCol a- 2

[0057] Where “TvS” is the PE1-M-PR2 time of flight measured on the B-scan cross-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 = ^2- c2

[0060] Where "a" corresponds to the semi-major axis of the ellipse, and "c" corresponds to the half focal length of the ellipse, namely half of the physically measured distance between the transmitting 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 drawn using the equation above, with the value for the semi-major axis "a" given by the following equation:

[0062] [Math.6] _ (TvP-TvOL)xCol a— 2 “

[0063] Where “TvP” is the PE1-M-PR2 time of flight measured on the B-scan cross-sectional view of the analysis software using cursor P, and “C0L” is the ultrasonic velocity 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 made 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] Figure [Fig. 3] represents such an example with two acquisition groups.

[0066] In this example, the ellipse el was drawn considering the "head" component of the defect (see equation 4 above) and from the acquisition group formed by the transmitting translator El and the receiving translator R2. Also in this example, the ellipse e2 was drawn from the acquisition group formed by the transmitting translator El and the receiving translator RI (always considering the "head" component 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 controlled 8, and a second point 1-2 positioned outside of it.

[0068] The intersection point 1-1 positioned inside the part to be inspected 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 made with the cursors OL, S and P make it possible to trace 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 selected (namely the following groups: El-R1, E2-R2, E2-R1, and E1-R2).

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

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

[0073] The intersection point Jl positioned inside the part to be inspected 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 should be noted that when the location of the defect component is carried out by considering more than two ellipses (as in the example in [Fig. 4]), the points of intersection of the different ellipses may, due to uncertainties in flight time measurements, not be perfectly coincident. In this case, the centroid of the identified points of intersection will be used.

[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 cross-sectional view of the controlled area can be easily defined by linking the positions of the foot and top of the defect.

[0077] Fig. 5 thus represents an example of the implementation of this process to characterize 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 transmitting translator El for two receiving translators RI, R2).

[0079] In this figure, two ellipses el, e2 have been determined and drawn considering the "head" component of the defect (ellipse el is relative to acquisition group El-RI, while ellipse e2 is relative to 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 drawn considering the "foot" component of the defect (ellipse e'1 is relative to the acquisition group E1-R1, while ellipse e'2 is relative to the 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 on the cross-sectional view of the controlled area Z.

Claims

Demands

1. A non-destructive ultrasonic testing method for a metal part or weld bead deposited in a chamfer formed between two metal parts, the method comprising, from an acquisition device (2) moving along the controlled area (Z) and composed of two transmitting transducers (E1, E2) positioned on one side of the controlled area (Z) and two receiving transducers (RI, R2) positioned on the opposite side of the controlled area: - the emission by the transmitting transducers of longitudinal ultrasonic waves in the direction of the controlled area, and the reception of ultrasonic data by each of the two receiving transducers so as to form four distinct acquisition groups, - the determination of the geometric position of two ends (10-1, 10-2) of a defect (10) on a cross-sectional view of the controlled area 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 four ellipses (e1 to e4) comprising a first ellipse associated with the first acquisition group and whose foci correspond to the position of a first transmitting translator and a first receiving translator, a second ellipse associated with a second acquisition group and whose foci correspond to the position of the first transmitting translator and the second receiving translator, a third ellipse associated with a third acquisition group and whose foci correspond to the position of a second transmitting translator and the first receiving translator, and a fourth ellipse associated with a fourth acquisition group and whose foci correspond to the position of the second transmitting translator and the second receiving translator.

2. A method according to claim 1, wherein the geometric equation of each of the ellipses (e1 to e4) in a coordinate system (x,y) on the view in The cross-section of the controlled area is given by: (x2 / a2) + (y2 / b2) = 1; in which: - the semi-major axis "a" is a function of: • the time-of-flight measurement of the component of one end of the observed defect, • the time-of-flight measurement between the transmitting transducer and the receiving transducer considered, and • the 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.

3. Method according to claim 2, wherein the semi-major axis "a" is given by the following equation: [Math.7] _ (Tv-TvOL)xCol a~ 2 in which "Tv" is the time-of-flight measurement of the component of a chosen end of the observed defect, "TvOL" is the time-of-flight measurement between the transmitting transducer and the receiving transducer considered, and "C0L" is the ultrasonic velocity in the controlled area.

4. A method according to any one of claims 2 and 3, wherein 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. A method according to any one of claims 1 to 4, further comprising determining the dimensions and orientation of the defect (10) observed on the cross-sectional view of the controlled area from the geometric positions of the two ends of the observed defect.

6. A method according to any one of claims 1 to 5, wherein the transmitting translators emit longitudinal waves at a frequency between 1 and 15 MHz.

7. 12 Device for carrying out the method according to any one of claims 1 to 6, comprising two transmitting translators 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.