Method for determining a delay law, inspection method, device and associated computer program product

Abstract

Method for determining a delay law, inspection method, associated device and computer program product The invention relates to a method for determining a delay law for ultrasonic inspection of a weld (10), comprising the following steps: - providing information on the weld (10) including the arrangement of grains of the weld and a respective orientation of said grains, - modeling the weld (10) by a digital model based on the provided information, - positioning a defect in the digital model at a desired location, - simulating in the digital model a propagation of an ultrasonic wave from a location through the weld (10) to the defect and a resulting reflected wave, - determining the flight times of the resulting reflected wave, and - applying a time reversal on the flight times to determine a suitable delay law.The invention also relates to an inspection method, a device and a computer program product associated therewith. Figure for abstract: Fig 1.

Description

Title of the invention: Method for determining a delay law, associated inspection method, device and computer program product

[0001] The present invention relates to a method for determining a delay law for the ultrasonic inspection of a weld.

[0002] It is known to use a multi-element ultrasonic probe for the inspection of a weld.

[0003] It is common to apply a delay law for the emission of the ultrasonic beam by the probe to focus the beam at a detection location and to compensate for the loss of acoustic energy due to the diffusion phenomenon.

[0004] However, the calculation of these delay laws is based on an isotropic material.

[0005] However, a weld is not an isotropic structure.

[0006] The use of such a delay law results in less good focusing of the beam at the desired location and a reduction in the signal to noise ratio, which complicates the possible detection of a defect in the weld at said location.

[0007] An alternative is to use another non-destructive testing technology, for example by radiography. However, such a method is more expensive to implement.

[0008] The aim of the invention is then to propose a method for determining a delay law for the ultrasonic inspection of a weld, adapted to the weld.

[0009] To this end, the invention relates to a method for determining a delay law for the ultrasonic inspection of a weld by a multi-element probe, more particularly of the primary circuit of a nuclear power plant, the weld having grains, the method comprising the following steps:

[0010] - providing information on the weld, the information including the arrangement of at least a portion of the grains of the weld and a respective orientation of said grains,

[0011] - modeling of the weld in the form of a digital model, the model digital being based on the information provided,

[0012] - positioning a defect in the digital model at a desired location of focus,

[0013] - simulation in the numerical model of a propagation of an ultrasonic wave from a location through the weld to the defect at the desired location and a resulting reflected wave,

[0014] - determination of the flight times of the resulting reflected wave, and

[0015] - application of a time reversal on the flight times to determine a delay law adapted to focus an ultrasonic wave from the multi-element probe to the desired location from the localization.

[0016] Modeling the weld from information concerning it and determining the delay law from this model makes it possible to take into account the microstructure of the weld, and in particular the orientation of the grains of the weld.

[0017] According to other advantageous aspects of the invention, the method comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

[0018] - the weld information relates to a section of the weld perpendi cularly to a direction of extension of the weld, the digital model being a two-dimensional model,

[0019] - the method comprises a step of obtaining information on the weld comprising the application of a chemical attack on a model of the weld, the observation of the respective orientation of at least part of the grains of the model of the weld and the memorization of the respective orientations,

[0020] - the digital model of the weld comprises a finite number of elements,

[0021] - the steps of positioning a fault, simulation, determination and of application are repeated by successively considering different desired locations for at least one respective location,

[0022] - the method comprises a step of validating the digital model between the step of modeling and the positioning step, the validation step comprising the simulation of the propagation of at least one ultrasonic wave in the digital model and the comparison of the deflection of the simulated ultrasonic wave with a deflection obtained experimentally on the weld,

[0023] - the defect is a hole drilled laterally in the digital model, and / or

[0024] - the adapted delay law includes an emission instant for each element of the multi-element probe, the emission time being equal to the subtraction at a given time of flight of the reflected wave received at the location of said element of the multi-element probe.

[0025] The invention also relates to a method for ultrasonic inspection of a weld, using a multi-element ultrasonic probe, the multi-element ultrasonic probe emitting an ultrasonic wave with the adapted delay law determined by the determination method as described previously.

[0026] The inspection method is likely to have the following characteristic: the multi-element ultrasonic probe successively emits an ultrasonic wave with each delay law adapted for each desired location considered.

[0027] The invention also relates to an electronic device for determining a law delays for the ultrasonic inspection of a weld with grains, the electronic device being adapted to:

[0028] - receive information about the weld, the information including the arrangement of at least a portion of the grains of the weld and a respective orientation of said grains,

[0029] - model the weld in the form of a digital model, the digital model being based on the grain orientation of the weld,

[0030] - position a defect in the digital model at a desired location of fo calibration,

[0031] - simulate in the digital model a propagation of an ultrasonic wave from a localization through the weld to the defect at the desired location and a resulting reflected wave,

[0032] - determine the resulting reflected wave flight times, and

[0033] - apply a time reversal on the flight times to determine a law of delays adapted to focus an ultrasonic wave from the phased array probe to the desired location from the localization.

[0034] The invention further relates to a computer program product comprising instructions for carrying out the steps of a method as described above.

[0035] The invention also relates to a computer program comprising software instructions which, when executed by a computer, implement a method for determining a delay law as defined above.

[0036] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0037] [Fig-1] [Fig.l] is a sectional view of a weld to be inspected according to an example,

[0038] [Fig.2] [Fig.2] is a schematic representation of a first example of a determination method according to the invention,

[0039] [Fig.3] [Fig.3] is a schematic representation of a second example of a determination method according to the invention,

[0040] [Fig.4] [Fig.4] is a schematic view of a model of the weld of [Fig.l],

[0041] [Fig.5] [Fig.5] is a schematic representation of a digital model of the weld of [Fig.l] with a defect and a multi-element probe, according to an embodiment of the invention, and

[0042] [Fig.6] [Fig.6] is an example of improving the focusing of the ultrasonic wave by applying the adapted delay laws.

[0043] An example of a weld cross-section 10 to be inspected is shown in [Fig.l], for illustration purposes only.

[0044] The weld 10 is, for example, a weld between two parts of a pipe.

[0045] The weld 10 is, for example, a weld of the primary circuit of a nuclear power plant.

[0046] The weld 10 has an extension direction.

[0047] The sectional view of [Fig. 1] is taken perpendicular to the direction of extension.

[0048] The weld 10 has a surface on which a multi-element ultrasonic probe can be arranged.

[0049] The weld 10 has grains, each grain having a respective orientation.

[0050] In [Fig.l], respective orientations 12 of the grains are shown at several locations of the weld 10.

[0051] A method for determining a delay law for the ultrasonic inspection of a weld by a multi-element probe, in particular as described previously, will now be described with reference to Figures 2 and 3.

[0052] A simplified embodiment of the determination method is shown in [Fig.3]. An enhanced embodiment of the determination method is shown in [Fig.4].

[0053] The multi-element probe is an ultrasonic probe comprising a plurality of elements, each element being adapted to emit and receive an ultrasonic wave.

[0054] The plurality of elements is, for example, in the form of a rectangular matrix distributed on a plane, a linear matrix, or concentric rings.

[0055] The determination method comprises the following steps:

[0056] - provision 102, 202 of information on welding,

[0057] - modeling 104; 204 of the weld in the form of a digital model,

[0058] - positioning 106; 206 of a defect in the digital model in one em desired focus placement,

[0059] - simulation 108; 208 in the numerical model of a propagation of a ul wave trasonic from a location of a multi-element probe through the weld to the defect at the desired location and a resulting reflected wave,

[0060] - determination 110; 210 of the flight times of the reflected Fonde, and

[0061] - application 112; 212 of a time reversal on the flight times to de terminate a suitable delay law to focus an ultrasonic wave from the multi-element probe to the desired location from the localization.

[0062] In a particular embodiment, the method further comprises a step 200 of obtaining information on the weld before the supply step 102, 202.

[0063] The obtaining step 200 comprises, for example, the application of a chemical attack on a model 250 of the weld, an example of which is shown in [Fig. 4], more particularly on an observation plane of the model of the weld 10 perpendicular to the direction X of the model corresponding to the direction extension of the weld, observation of the respective orientation of grains of the weld model 10, in particular of all the grains of the observation plane, and memorization of the respective orientations.

[0064] The weld model comprises a weld 252 between parts 254, 256 similar to the parts welded by the weld, according to the same welding process.

[0065] Similar parts are, for example, portions of the welded parts, for example a section of the welded parts according to a cut perpendicular to the direction of extension of the weld.

[0066] More particularly in the case of parts of a pipe, the model comprises a section of a portion of pipe.

[0067] The application of the chemical attack is, for example, carried out on a visible face 258 of the weld 252 of the model 250.

[0068] Alternatively or additionally, the obtaining step 200 comprises at least one step of cutting the model 250 along a plane perpendicular to the direction X of the model corresponding to the direction of extension of the weld 10. The chemical attack is then, for example, applied to at least one of the newly accessible faces of the weld 252.

[0069] The chemical attack makes it possible in particular to improve the visualization of the respective orientation of the grains of the weld 10.

[0070] The observation of the respective orientation of the grains is, for example, carried out by acquiring an image of said plane and analyzing the image to deduce the respective orientation of the grains of the weld.

[0071] Alternatively, the obtaining step 200 comprises the implementation of a characterization by diffraction of backscattered electrons called EBSD characterization for Electron BackScattered Diffraction in English, in a scanning electron microscope.

[0072] Then, the arrangement of a part of the grains of the weld, in particular of all the grains of the observation plane, and the respective orientation of said grains are memorized.

[0073] During the provision step 102; 202, the information provided includes the arrangement of at least a portion of the grains of the weld, here of all the grains of the observation plane, and a respective orientation of said grains.

[0074] The information on the weld here relates to at least one, here one, section of the weld perpendicular to the direction of extension X of the weld 10, here to the observation plane.

[0075] The information is, for example, provided to a receiving module.

[0076] The digital model of the weld 10 is based on the information provided.

[0077] In particular, the digital model is representative of the arrangement of at least one part of the grains of the weld and the respective orientation of said grains.

[0078] The digital model is here generated by a modeling module, connected to the receiving module. The receiving module sends the information to the modeling module.

[0079] An example of a digital model 300 is, for example, represented in [Fig.4].

[0080] The digital model 300 here comprises an envelope 302, representing the contour of the weld, here in the observation plane.

[0081] The digital model 300 comprises a finite number n of elements 304.

[0082] The elements 304 are arranged in the envelope 302.

[0083] More particularly, the weld is divided into the finite number n of elements 304, for example by gridding the envelope 302.

[0084] The modeling is, for example, such that each grain of the weld is modeled by at least one element 304, here for example by at least four, here four, elements 304.

[0085] The number of elements representing a grain depends in particular on a plurality of parameters, including, for example, the frequency of the ultrasonic wave provided for the ultrasonic inspection described, the size of the defect sought, and the dimension of the grain.

[0086] Each element 304 is associated with a respective representative orientation.

[0087] The respective representative orientation is representative of the respective orientation of the grain(s) modeled at the level of said element.

[0088] Here, the respective orientation representative of the elements modeling a grain is, for example, the respective orientation of the grain of the weld.

[0089] Alternatively, the modeling is such that each element 304 models a plurality of grains of the weld.

[0090] The respective orientation representative of the element is, for example, equal to the average orientation of the plurality of grains modeled by the element.

[0091] The digital model 300 is here a two-dimensional model, more particularly of the observation plane of the weld 10.

[0092] More particularly, it is considered here that the volume of the weld is a succession of identical planes, corresponding here to the information observed on the observation plane, so that the digital model 300 is representative of the entire volume of the weld.

[0093] Alternatively, the obtaining step comprises a step of obtaining information on a plurality of observation planes perpendicular to the direction of extension of the weld, for example as described previously on a model.

[0094] The digital model 300 is then, for example, a three-dimensional model integrating the different observation planes.

[0095] In one embodiment, the method further comprises a validation step 205 of the digital model 300 between the modeling step 104, 204 and the positioning step 106, 206.

[0096] The validation step 205 comprises the simulation of the propagation of at least one ultrasonic wave in the digital model 300 and the comparison of the deviation of the simulated ultrasonic wave, corresponding to the curvature of the wave, with a deviation obtained experimentally on the weld 10 with a similar wave and / or the acoustic energy of the simulated wave with the acoustic energy obtained experimentally on the weld 10 with a similar wave in each direction.

[0097] For example, if the simulated deviation differs from the experimentally obtained deviation only by a value less than a threshold, then the numerical model is validated.

[0098] Otherwise, the digital model is not validated.

[0099] Then, a new digital model is generated, in particular by the modeling module.

[0100] The new digital model has, for example, a number of elements strictly greater than the number of elements of the digital model, and / or the new digital model is, for example, based on new information provided.

[0101] The validation step is, for example, implemented by a validation module.

[0102] The validation module is connected to the modeling module.

[0103] The modeling module sends the digital model to the validation module.

[0104] The validation module also receives the deviation obtained experimentally. tlement.

[0105] The validation module emits, for example to the modeling module, a signal validation if the digital model is validated or a refusal signal if the model digital is not validated.

[0106] During positioning 106, 206, the defect 306 is positioned at a desired focusing location on the digital model 300.

[0107] The defect 306 extends, for example, over at least one element 304, for example here over a plurality of elements 304.

[0108] The defect 306 is, for example, a hole drilled laterally, that is to say here directly at the desired focusing location, as if the drilling were carried out from one side of the digital model 300, more particularly perpendicular to the two-dimensional digital model 300.

[0109] The positioning step is, for example, implemented by a positioning module connected to the modeling module.

[0110] During the simulation step, the emission of an ultrasonic wave is simulated from a location, more particularly present in the digital model on the surface of the weld 10, to the desired location.

[0111] The location corresponds here, in the digital model 300, to the location planned multi-element probe 308 on the weld surface.

[0112] The simulated ultrasonic wave has characteristics, for example including frequency, waveform or gain, corresponding to the ultrasonic wave intended for the ultrasonic inspection.

[0113] The propagation of said ultrasonic wave from the location to the defect 306 is further simulated, more particularly by propagation in the elements 304.

[0114] Defect 306 then reflects the wave.

[0115] During the simulation step, the propagation of the reflected wave resulting from the reflection on the defect 306 is simulated, more particularly by propagation in the elements 304.

[0116] The simulation step is, for example, implemented by a simulation module connected to the positioning module.

[0117] During the determination step, the resulting reflected Fonde flight time is determined for each of the locations corresponding to the surface of the weld opposite which the elements of the multi-element probe are arranged.

[0118] More particularly, for each of the locations, the flight time corresponds to the time taken by the simulated ultrasonic wave from its emission to the reception of the resulting reflected wave at the surface.

[0119] Said flight times are calculated from the simulation of the propagation of the simulated ultrasonic wave.

[0120] The simulation step is, for example, implemented by a determination module, for example by a Python script.

[0121] The determination module is connected to the simulation module.

[0122] The simulation module sends the simulation of the propagation to the determination module.

[0123] Then, during the application step, the determined flight times are returned temporally.

[0124] More particularly, the adapted delay law includes an emission instant for each element of the probe.

[0125] The delay law is such that the element of the multi-element probe for which the determined flight time is the highest transmits first, then the element of the multi-element probe for which the determined flight time is the second highest transmits second, and so on up to the element of the multi-element probe having the lowest determined flight time.

[0126] For each element of the multi-element probe, the emission time ti is equal to the subtraction at a given time tO of the flight time tv of the reflected wave received at the expected location of said element, i.e. ti = tO- tv.

[0127] The given moment tO is identical for all the elements of the multi-element probe.

[0128] Indeed, in a solid, an ultrasonic wave moves according to the following equation:

[0129] px = (2 + 2 / / ) x (grad(div(u)) -px curl(curl(u)))

[0130] with u the displacement of the wave, X and q the Lamé coefficients and ps the density of the solid.

[0131] Now, if u(tl) is a solution of the above equation, u(-tl) is also, since the equation contains only second-order differentiation operators.

[0132] By inverting the simulated flight times, this therefore makes it possible to compensate them with the information included in the digital model, including the arrangement and respective orientation of the grains.

[0133] This makes it possible to determine a delay law for the desired focusing location, adapted to the weld, and in particular to the anisotropy of the weld.

[0134] The application step is, for example, implemented by an application module.

[0135] The application module is connected to the determination module.

[0136] The determination module sends the determined flight times to the module of application.

[0137] In a particular embodiment, the steps of positioning a defect, simulating, determining and applying are repeated by successively considering different desired locations for at least one location, as shown in [Fig.3].

[0138] During each iteration of the positioning step, the defect is positioned at the desired location, the simulation, determination and application steps then being implemented with said defect.

[0139] The location is, for example, identical for each of the iterations.

[0140] Additionally or alternatively, the steps of positioning a fault, simulating, determining and applying are repeated by successively considering different locations, more particularly different locations provided for the multi-element probe 308.

[0141] In the present embodiment, the steps of positioning a defect, simulating, determining and applying are repeated by considering all the combinations of the different desired locations and the different localizations.

[0142] The steps of positioning a fault, simulation, determination and application are, for example, repeated successively by successively considering each of the different locations, by successively considering for each different location the different desired locations.

[0143] This means that for a first location, we consider the set of desired locations, then for a second location we consider the set of desired locations, and so on until the last location.

[0144] This makes it possible in particular to cover the entire area formed by the weld.

[0145] The iteration is, for example, implemented by an iteration module, for example by a Python script.

[0146] The iteration module is connected to the positioning module.

[0147] This makes it possible to determine a suitable delay law for each of the weld locations, and thus to be able to implement a complete inspection of the weld by successively implementing the different delay laws determined.

[0148] Although in [Fig.3] the method with successive iterations is shown with validation 205 and obtaining 200 steps, in particular embodiments the method includes successive iterations, but not validation 205 and obtaining 200 steps, or only validation step 205, or only obtaining 200 step.

[0149] Alternatively, in particular embodiments, the method comprises the validation 205 and obtaining 200 steps, and not the successive iterations, or the validation 205 step only, or the obtaining 200 step only.

[0150] The invention further relates to an electronic device for determining a delay law for the ultrasonic inspection of a weld as described previously, and capable of implementing the determination method described previously.

[0151] The electronic determination device comprises the receiving module, the modeling module, the positioning module, the simulation module, the determination module and the application module.

[0152] As an optional addition, the electronic determination device comprises the validation module and / or the iteration module.

[0153] The electronic determination device comprises an information processing unit formed for example of a memory and a processor associated with the memory.

[0154] The reception module, the modeling module, the positioning module, the simulation module, the determination module and the application module, as well as optionally the validation module and / or the iteration module, are each implemented in the form of software, or a software brick, executable by the processor. The memory of the electronic determination device is then capable of storing software for each of the modules. The processor is then capable of executing each of the software.

[0155] In a variant not shown, at least one of the modules among the modeling module, the positioning module, the simulation module, the determination module and the application module, as well as as an optional addition the module of validation and / or the iteration module, is implemented in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array) or an integrated circuit, such as an ASIC (Application Specified In-tegrated Circuit).

[0156] When the electronic determination device is produced in the form of one or more software programs, that is to say in the form of a computer program, also called a computer program product, it is also capable of being recorded on a medium, not shown, readable by a computer. The computer-readable medium is, for example, a medium capable of storing electronic instructions and of being coupled to a bus of a computer system. For example, the readable medium is an optical disk, a magneto-optical disk, a ROM memory, a RAM memory, any type of non-volatile memory (for example FLASH or NVRAM) or a magnetic card. A computer program comprising software instructions is then stored on the readable medium.

[0157] The invention further relates to a method for ultrasonic inspection of a weld 10, using a multi-element ultrasonic probe.

[0158] The inspection method comprises the reception by the multi-element ultrasonic probe of the determined adapted delay law(s), with, for each law, the desired location and the localization associated with said law, during a determination method as described previously implemented beforehand.

[0159] The inspection method comprises the emission by the multi-element ultrasonic probe of an ultrasonic wave with the or one of the adapted delay laws, the multi-element ultrasonic probe being arranged in accordance with the corresponding location, and the reception of the corresponding reflected beam.

[0160] More particularly, each element of the multi-element probe emits an ultrasonic wave at the instant of emission of the delay law.

[0161] The ultrasonic beam, formed from all the ultrasonic waves, is then particularly focused at the desired focusing location, including when the weld is particularly anisotropic.

[0162] In the event of a defect, this reflects the ultrasonic beam, which is received by the multi-element probe.

[0163] The received reflected beam has an increased signal-to-noise ratio.

[0164] In a particular embodiment, the multi-element ultrasonic probe successively emits an ultrasonic wave with a delay law adapted for each of the locations of the weld at least in one plane, in particular with each of the adapted delay laws determined during the iterations, with the adapted location of the multi-element probe.

[0165] More particularly here, the multi-element ultrasonic probe successively emits a ultrasonic wave with a delay law adapted for each of the weld locations over the entire volume of the weld, considering for each weld location the location within the weld section perpendicular to the extension direction.

[0166] This thus makes it possible to carry out a complete inspection of the weld, with improved quality.

[0167] In the case where the steps of positioning a defect, simulation, determination and application have been implemented for different locations, then the inspection method comprises a plurality of detections, each detection comprising the emission by the multi-element ultrasonic probe of an ultrasonic wave with the or one of the adapted delay laws, the multi-element ultrasonic probe being arranged in accordance with one of the locations, and the reception of the corresponding reflected beam. The detections are implemented with the different locations of the multi-element ultrasonic probe.

[0168] This makes it possible, for example, to improve the coverage of the weld, in particular for a complex weld in the case of a deviation of the wave, in particular by its thickness and / or the structure of the grains.

[0169] An example of improvement in the focusing of ultrasonic Fonde obtained thanks to the invention is shown in [Fig.6].

[0170] On the left, the propagation of the ultrasonic wave from the focused probe to an area to be inspected (represented by the circle) is simulated by applying a delay law not adapted to the orientation of the weld grains.

[0171] On the right, the propagation of the ultrasonic wave from the focused probe to the area to be inspected is simulated by applying the delay law adapted to the orientation of the grains of the weld according to the invention.

[0172] It is noted that the focusing of the ultrasonic beam at the area to be inspected is improved thanks to the invention.

Claims

Claims

1. Method for determining a delay law for the ultrasonic inspection of a weld (10) by a multi-element probe, more particularly of the primary circuit of a nuclear power plant, the weld (10) having grains, the determination method comprising the following steps: - providing (102; 202) information on the weld (10), the information comprising the arrangement of at least a portion of the grains of the weld and a respective orientation of said grains, - modeling (104; 204) of the weld (10) in the form of a digital model (300), the digital model (300) being based on the provided information, - positioning (106; 206) of a defect (306) in the digital model (300) at a desired focusing location, - simulation (108;208) in the numerical model (300) of a propagation of an ultrasonic wave from a location through the weld (10) to the defect (306) at the desired location and of a resulting reflected wave, - determining (110; 210) the flight times of the resulting reflected wave, and - applying (112; 212) a time reversal on the flight times to determine a delay law suitable for focusing an ultrasonic wave from the multi-element probe to the desired location from the location.;

2. A determination method according to claim 1, wherein the weld information relates to a section of the weld (10) perpendicular to an extension direction of the weld (10), the digital model (300) being a two-dimensional model.

3. A determination method according to claim 2, comprising a step of obtaining (200) information on the weld comprising the application of a chemical attack on a model of the weld, the observation of the respective orientation of at least a portion of the grains of the model of the weld and the storage of the respective orientations.

4. A determination method according to any one of claims 1 to 3, wherein the digital model (300) of the weld comprises a finite number of elements (304).

5. A determination method according to claim 4, wherein the steps of positioning a fault (106; 206), simulating (108; 208), determining (110; 210) and applying (112; 212) are repeated by successively considering different desired locations for at least one respective location.

6. Determination method according to any one of claims 1 to 5, comprising a validation step (205) of the digital model (300) between the modeling step (204) and the positioning step (206), the validation step (204) comprising the simulation of the propagation of at least one ultrasonic wave in the digital model (300) and the comparison of the simulated ultrasonic Fonde deviation with a deviation obtained experimentally on the weld (10).

7. A determination method according to any one of claims 1 to 6, wherein the defect (306) is a hole drilled laterally in the digital model (300).

8. A determination method according to any one of claims 1 to 7, wherein the adapted delay law comprises an emission time for each element of the multi-element probe, the emission time being equal to the subtraction of the reflected Fonde time of flight received at the location of said element of the multi-element probe at a given time.

9. A method of ultrasonic inspection of a weld (10), using a multi-element ultrasonic probe, the multi-element ultrasonic probe emitting an ultrasonic wave with the adapted delay law determined by the determination method according to any one of claims 1 to 8.

10. An inspection method according to claim 9, when dependent on claim 5, wherein the multi-element ultrasonic probe successively emits an ultrasonic wave with each delay law adapted for each desired location considered.

11. Electronic device for determining a delay law for the ultrasonic inspection of a weld having grains, the electronic device being adapted to: - receive information on the weld (10), the information comprising the arrangement of at least a portion of the grains of the weld and a respective orientation of said grains, - model the weld (10) in the form of a digital model (300), the digital model (300) being based on the orientation of the grains of the welding (10), - positioning a defect (306) in the digital model (300) at a desired focusing location, - simulating in the digital model (300) a propagation of an ultrasonic wave from a location through the weld to the defect at the desired location and a resulting reflected wave, - determine the resulting reflected wave flight times, and - apply a time reversal on the flight times to determine a suitable delay law to focus an ultrasonic wave from the multi-element probe to the desired location from the localization.

12. A computer program product comprising instructions for carrying out the steps of a method according to any one of claims 1 to 10.

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