Method for non-destructive testing of the conformity of a part made of conductive material, and corresponding device, system, and computer program

Abstract

The invention relates to a method for non-destructive testing of the conformity of a part (PaC) made of conductive material, which method is implemented by a control system (SysC) comprising a local resistivity measurement device (DMLR) that comprises a pair of current injection probes (Plnj) and a pair of aligned voltage measurement probes (Pmes), the probes of the pair of current injection probes being arranged on either side of the probes of the pair of measurement probes, the local resistivity measurement device (DMLR) further comprising means for adjusting the spacing between the probes, the method comprising: • - adjusting (10) the spacing of the probes of the local resistivity measurement device (DMLR); • - obtaining (20) data representative of the resistivity (DrR) of the part (PaC); • - determining (30), according to the data representative of the resistivity (DrR) of the part (PaC), the presence of a defect within the part (PaC).

Description

[0001] DESCRIPTION

[0002] Title: Non-destructive testing method for conformity of a part made of conductive material, device, system and corresponding computer program.

[0003] 1. Domain

[0004] The invention relates to the non-destructive testing of conformity of parts made of conductive materials. More particularly, the invention relates to a method, a device and a system for non-destructive testing which detects defects located inside the parts to be tested, including ferromagnetic parts.

[0005] 2. Prior Art

[0006] In the context of quality control of manufactured parts in many industrial sectors, the detection of defects in conductive material parts using eddy currents has contributed significantly to the advancement of non-destructive testing (NDT) methods. Industrial applications of quality control are numerous, in various sectors such as aerospace, the petroleum industry, automotive and electronic component manufacturing.

[0007] Since its inception, this technique has undergone constant development, notably by increasing the limits of sensitivity and precision in the detection of surface or subsurface (immediately below the surface) imperfections in conductive materials, mainly non-ferromagnetic metal parts.

[0008] Eddy current-based NDT devices use electromagnetic coils to induce currents in conductive materials. These induced currents generate magnetic fields, and variations in these fields are then measured to identify anomalies such as cracks, porosities, or other subsurface defects. These methods, while effective, are limited in terms of sensitivity and spatial resolution.

[0009] The introduction of frequency modulation has improved discrimination between different types of defects, while more sensitive sensors have significantly increased detection sensitivity. More recently, the technology has evolved with the introduction of techniques such as eddy current imaging. These methods provide a visual representation of detected defects, greatly facilitating the analysis and understanding of anomaly characteristics. The use of multiplexed sensors and computerized systems has also allowed for greater automation of NDT procedures. These recent techniques, however, have the disadvantage of being relatively expensive.

[0010] Furthermore, since these technologies are based on the use of electromagnetic fields that are used to generate electron movements in the metal part to be tested, these electron movements are measured (with varying degrees of sensitivity) depending on suitable sensors. However, one of the disadvantages of this electromagnetic induction-based technique lies in the testing of ferromagnetic parts or in the testing of parts comprising several different types of conductive materials, such as metallic materials and ferromagnetic materials. In such situations, non-destructive testing based on eddy currents does not always produce satisfactory results or requires specific calibrations.This is essentially due to the fact that certain materials with magnetic properties disturb the measuring probe more or less strongly, including at locations within the part to be inspected which may be random.

[0011] It is therefore necessary to provide a method and a conformity control device which is capable of detecting the presence of a defect within a part (not visible, not emerging) of conductive material, including a ferromagnetic material.

[0012] 3. Summary of the invention

[0013] The invention improves the situation.

[0014] More particularly; the invention relates to a method for non-destructive testing of the conformity of parts made of conductive materials. More particularly, the invention relates to a method for non-destructive testing of the conformity of a part made of conductive material. The method is implemented by a testing system comprising a local resistivity measuring device, the local resistivity measuring device comprising a pair of current injection tips and a pair of voltage measuring tips, said pairs of tips being aligned, the tips of the pair of current injection tips being arranged on either side of the tips of the pair of measuring tips, the local resistivity measuring device further comprising means for adjusting the spacing of the tips between them.The method comprising: a step of adjusting the spacing of the tips of the local resistivity measuring device; a step of obtaining data representative of the resistivity of the part; a step of determining, as a function of the data representative of the resistivity of the part, the presence of a defect within the part. Thus, it is possible to detect defects, including non-through defects, within ferromagnetic parts, including when the material of these parts is not homogeneous, in particular by adapting the spacing of the injection and current measurement tips.

[0015] According to a particular characteristic, the step of obtaining data representative of the resistivity of said part to be checked comprises at least one iteration of the following steps: a current injection step, at the current injection peaks of the local resistivity measuring device; a step of measuring a voltage resulting from said current injection, measurement carried out at the measurement peaks of the local resistivity measuring device, allowing the resistivity to be obtained; a step of recording the electrical resistivity at the current location of the local resistivity measuring device; a step of moving the local resistivity measuring device to a following measurement location.

[0016] Thus, it is possible to serialize the capture of resistivity data, so as to allow batch processing, for example by batch of parts.

[0017] According to a particular characteristic, the step of recording the electrical resistivity at the current location of the local resistivity measuring device further comprises recording the current location of the local resistivity measuring device.

[0018] This makes it possible to precisely position the locations of any defects being sought.

[0019] According to a particular characteristic, the step of configuring the local resistivity measurement device comprises: a step of adjusting the spacing of the injection tips from each other according to a first predetermined spacing parameter; a step of adjusting the spacing of the measurement tips from each other according to a second predetermined spacing parameter; a step of adjusting the spacing between a reference measurement tip and a reference injection tip according to a third predetermined spacing parameter.

[0020] Thus, it is possible to easily adapt the way in which the voltage is measured by the measuring tips, and indirectly to adapt to the material of the part to be inspected. According to a particular characteristic, the step of determining the presence of a defect within the part is also a function of data representative of the spacing of the tips of the local resistivity measuring device.

[0021] According to a particular characteristic, the step of determining the presence of a defect within the part comprises at least one step of comparing at least part of the data representative of the resistivity of the part with at least one reference datum.

[0022] Thus, the invention makes it possible to facilitate the detection of defects, including non-through defects.

[0023] According to a particular characteristic, said at least one reference data comes from the data representative of the resistivity of the part.

[0024] According to a particular characteristic, said at least one reference data item comes from learning carried out on a set of parts composed of conductive material free from defects.

[0025] According to another aspect, the invention also relates to a local resistivity measurement device comprising a pair of current injection tips and a pair of voltage measurement tips, said pairs of tips being aligned, the tips of the pair of current injection tips being arranged on either side of the tips of the pair of measurement tips. According to the invention, the local resistivity measurement device further comprises means for adjusting the spacing of the tips from each other.

[0026] Thus, such a device makes it easier to detect defects, including non-through defects, which can be detected even on ferromagnetic parts.

[0027] According to a particular characteristic, the means for adjusting the spacing of the tips between them can be controlled from a parameterization module of said device.

[0028] Thus, it is possible to configure the device, for example, on a sample of parts or on a portion of a part to obtain reference data, then to use this configuration to subsequently carry out specific measurements on the device itself.

[0029] According to a particular characteristic, each of the tips of the pairs of tips comprises a return means, so that each of the tips remains in contact with the surface of the part.

[0030] Thus, the invention greatly facilitates measurement by ensuring permanent contact between the surface of the part and the tips.

[0031] According to a particular characteristic, the device further comprises motorized movement means. Thus, the device can be controlled remotely, by a computer program to carry out a mapping of the pieces of conductive material.

[0032] According to another aspect, the invention also relates to a system for non-destructive testing of the conformity of a part made of conductive material, a system comprising a local resistivity measuring device according to claim 9, an electric current generator for transmitting a measurable electric current through current injection tips of the local resistivity measuring device, a detection module, for determining, from the voltage measured by the measuring tips, data representative of the resistivity, a module for recording the data representative of the resistivity and a module for determining, as a function of the data representative of the resistivity, the presence of a defect within the part.

[0033] The management device has the architecture of a computer. It is equipped with one or more processors capable of running all types of computer programs, from operating systems to application software, written in compiled or interpreted languages. The various components of the device are connected to each other by a communication bus. The device may optionally be equipped with a communication system to communicate via protocols such as Bluetooth, Ethernet or WiFi with other systems and to connect to mobile or non-mobile telecommunications networks. The device also includes memory components that will store the data and programs necessary for the operation of the device.The device is further modified so that it can perform management operations involving a large number of vehicles and manage several thousand simultaneous operations per second, in particular by parallel implementation of route calculations.

[0034] The data carriers may be any entity or device capable of storing the programs. For example, the carriers may comprise a storage means, such as a ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording means such as a hard disk, or more often a Flash memory. On the other hand, the carriers may be transmissible media such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The programs according to the invention may in particular be downloaded from a network such as the Internet. Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question. 4. Description of the drawings

[0035] Other characteristics and advantages of the invention will appear more clearly on reading the following description of a particular embodiment, given as a simple illustrative and non-limiting example, and the appended drawings, among which:

[0036] [Fig. 1] schematically illustrates a control method according to the invention;

[0037] [Fig. 2] schematically illustrates the tips of a local resistivity measuring device according to the invention;

[0038] [Fig. 3] illustrates a first example of arrangement of the local resistivity measuring device according to the invention;

[0039] [Fig. 4] illustrates an example of a representation of a defect using a digital model;

[0040] [Fig. 5] illustrates an example of gain, in terms of signal-to-noise ratio of the injection tip spacing.

[0041] 5. Description of an embodiment

[0042] As previously stated, to overcome the problems of the prior art, a method for non-destructive testing of the conformity of parts made of conductive materials is described. This method can be implemented in a wide range of situations involving parts made of conductive materials, including parts made of ferromagnetic material, mixed parts comprising both conductive materials and ferromagnetic materials, etc.

[0043] The general principle is to implement a DCPD (Direct Current Potential Drop) method to measure the resistivity of a conductive material, by applying a direct current to the surface through two electrodes, and measuring a potential drop through two other electrodes, which makes it possible to determine the resistivity locally. According to the invention, the different resistivities are supplied to a processing module, which determines the presence or absence of a defect within the part (by associating the variation in the measured resistivity with the presence of a defect). The detected defects can be through (i.e. visible on the surface of the conductive material) or non-through (i.e. located inside the material, therefore invisible from the outside).The conductive material of the part may be a metallic, ferromagnetic, or other conductive material or a combination (for example in the form of layers, welds) of different types of conductive materials. The principle implemented consists of determining, at predetermined locations of the part, the capacity of the material of which it is composed to resist the passage of electric current. The variation of this capacity makes it possible to detect the presence of a conformity defect of the part, including non-emerging defects and including for ferromagnetic materials.

[0044] Figure 1 shows the different stages of the control process. This includes:

[0045] A step of setting up (10) the local resistivity measuring device;

[0046] A step of obtaining (20) data representative of the resistivity of said part to be controlled;

[0047] A step of determining (30), as a function of data representative of the resistivity of said part to be checked and optionally data representative of the spacing of the tips of the local resistivity measuring device, the presence of a defect within said part to be checked.

[0048] The identification of internal, non-terminating defects on the conductive material part is thus facilitated. In addition, the determination of the presence of defects can be carried out by directly analyzing the series of data representative of the resistivity, either using a digital detection model, or solely as a function of the data in the series, for example by identifying in this series of data, data representative of an absence of defects with regard to data representative of the presence of defects. When defects are identified within the part to be checked, an alarm can be emitted by the control system. This alarm can be visual, for example by implementing a human-machine interface on the screen of a digital device, or audible. It is thus possible, for example, to check piping parts in a simple and effective manner.

[0049] According to the invention, the step of obtaining (20) data representative of the resistivity of said part to be checked comprises at least one iteration of the following steps:

[0050] A current injection step (201), at the current injection peaks of the local resistivity measuring device;

[0051] A step of measuring (202) a voltage resulting from said current injection, measurement carried out at the level of the measuring points of the local resistivity measuring device, allowing the resistivity to be obtained;

[0052] A step of recording (203) the electrical resistivity at the current location of the local resistivity measuring device;

[0053] A step of moving (204) the local resistivity measuring device to a next measurement location. These steps are repeated as many times as necessary to allow the complete inspection of the piece of conductive material. For example, in the case of a pipe, the local resistivity measuring device makes successive movements, according to a movement pattern, for example 1 to 2 centimeters each time, makes a measurement, and moves again. Alternatively, the part to be inspected can move in place of the local resistivity measuring device. In this way, for example in the case of a piece of piping, it is possible to rotate the part on its longitudinal axis, which facilitates the inspection operations.

[0054] According to the invention, the parameterization step 10 of the local resistivity measurement device comprises:

[0055] A step of adjusting the spacing of the injection tips between them according to a first predetermined spacing parameter;

[0056] A step of adjusting the spacing of the measuring tips between them according to a second predetermined spacing parameter;

[0057] A step of adjusting the spacing between a reference measuring tip and a reference injection tip according to a third predetermined spacing parameter;

[0058] The inventors have in fact determined that a non-equidistant spacing of the tips makes it possible to improve the search for ligament defects. The optimal detection of a ligament notch type defect is when the two tension measuring tips are on either side of the notch line. By adjusting the respective distance between the tips, it is thus possible to refine the search for defects. The choice of the spacing between the tips thus depends on the type of material, its thickness, its shape and the position of the defect sought. Figure 2 represents in section the four tips (two injection tips 11, 12, two measuring tips U1, 12), a plate (Pcs) and a ligament notch type defect (def). The three parameters to be modulated are: the distance between the injection tips II, the distance between the measuring tips UU, and the relative position of the measuring tips with respect to the injection tips IU.

[0059] According to the invention, the movement of the local resistivity measuring device is carried out according to a predetermined movement pattern. For example, when the implementation of the control method consists of checking the absence of defects in a weld made on a part, for example a piece of piping, the adjustment of the spacing of the measuring tips is carried out so that each point of the pair of measuring tips is located on either side of the weld. The spacing of the current injection tips is also adjusted so that they are located at a predetermined distance from the measuring tips, for example a few centimeters. The measurements are for example spaced one (1) centimeter apart and the local resistivity measuring device moves along the weld. In other words, the movement of the tips is parallel to that of the weld.Several measurement campaigns can be carried out, for example by varying the spacing of the different measuring tips, so as to have several sets of measurements.

[0060] Generally speaking, the injection tip spacing range is from a few centimeters to twenty centimeters, the measurement tip spacing range is of the order of a few centimeters, the injected current intensity value range is between 1 and 5 amperes and the injection (and measurement) duration is less than a second (for each measurement). The thicknesses of the parts can be of the order of a few millimeters to a few centimeters, depending on the situation. Other configurations are obviously possible, as illustrated in Figure 5, in which the gain, in terms of signal-to-noise ratio (SNR) is measured as a function of the injection tip spacing (for a given type of material, at constant spacing of the measurement tips). In the illustrated case, the SNR is already greater than 2.5 for a spacing of 20 centimeters, which already provides good performance. This SNR increases further with the spacing.In practice, the settings carried out before the measurements therefore consist of determining the best balance (spacing of the tips, amperage of current introduced, injection time) to allow an effective measurement and therefore to allow increased detection of defects. These parameters can be stored in a database, to be loaded into the system. These parameters can be the subject of successive learning, for example by carrying out tests on standard parts (in terms of material composition, thickness, etc.).

[0061] When the part to be checked is a surface of given dimensions, the movement of the local resistivity measuring device can be carried out for example by making a grid of the part, comprising series of measurements in a longitudinal axis and series of measurements in a transverse axis of the surface of the part to be checked (the transverse axis can be perpendicular to the transverse axis), so as to have different measurement points at the level of the part to be checked, these measurement points being localized (i.e. having a precise location) at the level of the part. Other movement patterns are also conceivable, for example only along a longitudinal axis.The advantage of this type of part path is that we have a grid of localized measurements (i.e. the position of the measurement is known) and it is therefore possible to detect the position of a possible defect based on several measurements taken at locations more or less close to this defect, and therefore to characterize its shape, its dimension and its depth in the material of the part. Several measurement campaigns can be carried out, for example by varying the spacing of the different measuring tips, so as to have several sets of measurements.

[0062] From a structural point of view, in relation to Figure 3, the local resistivity measurement device comprises a set of four tips aligned on the same axis, these four tips are divided into two pairs of tips (two injection tips 11, 12, two measurement tips U1, U2), and they form a rake. The first pair of tips, called current injection tips, is located at the two ends of the set formed by the four aligned tips. The potential measurement tips constituting the second pair (making it possible to deduce the local conductivity value), are those located between the two current injection tips. In other words, each tip of the four-armed rake plays a specific role in collecting electrical information. The two outer tips serve as current injection points, while the two inner tips measure the potential drop.This configuration minimizes measurement errors induced by potential variations on the material surface, thus providing more reliable results.

[0063] According to the present invention, the four-point rake which is the subject of the disclosure, specifically designed for measuring the resistivity of a conductive material, comprises in particular, on the one hand, return means (mrU1, mrU2, mrl1, mrl2), placed under each of the points, as illustrated in the sectional view of Figure 3. These return means (such as springs or flexible metal blades) ensure that even in the event of variation in the flatness of the surface of the conductive material, the four points of the rake remain in contact with the surface of the conductive material. Therefore, since the contact of the points with the surface of the material is permanent, unwanted causes of the variation in conductivity are eliminated. In other words, unlike other measuring devices of the prior art, the variation in the flatness of the material surface does not lead to a variation in the measurement of the conductivity.

[0064] On the other hand, the different spacings between the tips of the rake are modifiable, to vary the current injection conditions and the conditions for measuring the conductivity of the conductive material, according to at least three spacing variation parameters (spacing of the injection tips from each other according to a first spacing parameter, spacing of the measurement tips from each other according to a second spacing parameter, spacing between a reference measurement tip and a reference injection tip according to a third spacing parameter) as indicated previously in relation to the control method.

[0065] The arrangement of the tips of the four-pronged rake thus follows a calculated and modifiable symmetry, ensuring a predetermined distribution of the electric current through the material being tested. Each of the metal tips is positioned at specific distances, chosen according to the conductive material and / or the composition of the part to be tested, to minimize interference and guarantee an accurate measurement of the potential drop in direct current.

[0066] In practice, the four-point rake allows for more precise resistivity measurements, providing a robust method for assessing the electrical properties of conductive materials, and in particular for detecting the presence of non-opening defects, particularly for ferromagnetic materials which disrupt conventional methods based on eddy currents.

[0067] The local resistivity measuring device, generally speaking, is in the form of a rectangular parallelepiped, and comprises a housing (B) of which a rear face comprises at least one location to allow the tips of the rake to come into contact with the surface of the conductive material of the part to be tested. The four tips are for example mounted on a non-conductive rail RL. The rail supports the return means (mrU1, mrU2, mrl1, mrl2) which are adapted to each of the tips (two injection tips 11, I2, two measuring tips U1, U2). Power supply and measuring cables (c1, c2, m1, m2). Optionally, the rail RL can also comprise the means for varying the spacing (only one numbered, v1, for greater readability) of the tips of the rake.These means may be manual, such as clamping screws which, when loosened, allow the spacings of the rake tips on the rail RL to be modified using a sliding mechanism. In other embodiments, these means may be motorized to control the spacings of the rake tips from a parameterization module or another device of the control system, for example. In this case, each tip is controlled independently along an axis (for example mounted on the rail), for example using a translation mechanism such as a worm screw, and drive means, such as stepper motors, which allow the position of the tip to be varied on the horizontal axis of the tip support rail.

[0068] The local resistivity measuring device may also comprise motorized movement means. In this way, the local resistivity measuring device can perform a series of measurements in an automated manner, on a part over which it moves. The movement of the local resistivity measuring device may be rectilinear, in a direction determined in advance, and the spacing between each measurement may be parameterized (for example every centimeter, or every two centimeters).

[0069] All of these means can be configured and / or controlled by means of a computer program operating on a control module, integrated or not within the local resistivity measurement device. The control module can comprise a processing circuit comprising a processor and a memory for recording the configuration parameters of the device. In addition, or as a variant, the data representative of the resistivity can also be processed and recorded within this control module. The memory stores at least the instructions of a computer program in accordance with the present disclosure.By performing this type of processing, and in particular by implementing data structures in accordance with the method of the disclosure, for recording resistivity data and measurement location data, the module processor has proven capable of performing resistivity measurements on the parts to be tested.

[0070] In preferred embodiments, the computer system or device comprises one or more processors (which may belong to the same computer or to different computers) and one or more memories (magnetic hard disk, optical disk, electronic memory or any computer-readable storage medium) in which a computer program product is stored, in the form of a set of program code instructions to be executed in order to implement all or part of the steps of the control method. Alternatively, or in combination, the computer system, device or module may comprise one or more programmable logic circuits (FPGA, PLD, etc.), and / or one or more specialized integrated circuits (ASIC), etc., adapted to implement all or part of said steps of the control method.In other words, the computer system comprises a set of means configured by software (specific computer program product) and / or by hardware (processor, FPGA, PLD, ASIC, etc.) to implement the steps of the control method.

[0071] The local resistivity measurement device is integrated into a non-destructive conformity control system for parts made of conductive materials.

[0072] This system also includes an electrical current generator that provides a constant source of electrical energy to the system. This generator transmits a measurable electrical current through current injection tips of the local resistivity measurement device. The system observes the voltage generated by the electrical current flowing through the part, using measuring tips of the local resistivity measurement device. This voltage is then measured using a detection module, after being amplified. The electrical resistance of the part is calculated based on the observed voltage and the applied current according to Ohm's law (R = V / l, where R is resistance, V is voltage and I is current).

[0073] Using the precise voltage and current measurements, as well as the geometric parameters of the part, the system calculates data representative of the specific resistivity of the conductive part, at the measurement locations. These data representative of the resistivity are recorded by a recording module. A control module is implemented to detect one or more defects in the part being tested, based on the data representative of the resistivity and possibly the digital detection model (which delivers a set of reference data). The control module compares the data obtained during the measurement with the reference data, for example from the digital detection model to identify the presence of one or more defects that would be present within the part being tested.The digital detection model is thus used, for example, to detect the presence of a fault by carrying out an analysis of the variability of the measured resistivity with regard to an expected variability. The digital detection model can also be used to produce a graphical representation of the fault, using a graphical representation module.

[0074] The digital detection model may comprise a set of data statistically representing, for example for a given material, or for a given composition of materials, resistivity ranges. This statistic relating to the resistivity range of a material or a composition of materials may result from learning carried out on a set of standard parts or portions of parts, of which it is established (for example during manufacture or using destructive methods implemented after the collection of the data used for the statistics), that they do not include any defects. This resistivity data is then used as a basis for constructing the digital detection model to characterize standard resistivity ranges, which are for example a function of the spacing of the current injection tips and the measurement tips between them.Measurement campaigns can be carried out, at several spacings of the tips of the local resistivity measuring device, to statistically determine, at known or unknown spacings of tips (i.e. not having been measured for learning), expected statistical resistivity values. The digital detection model can also include a set of data statistically representing, for example for a given material, or for a given composition of materials, resistivity ranges related to known defects.Just as for parts or portions of parts free of defects, the resistivity statistics of parts with defects are recorded after one or more resistivity data measurement campaigns, using the control system, the difference being that defects are, intentionally or not, present at the level of these parts or portions of parts to obtain these representative defect data. It is thus possible to have a library of digital models associated with typologies of materials and / or parts. The graphic representation module takes as input the parameters of the controlled part.

[0075] (composition, dimensions, thickness) as well as the data representative of the resistivity and the location of the measurements and all or part of the digital detection model, to calculate and represent the defect(s) as well as the shape of these. This module includes a processor and a memory to record the resistivity measurements and integrate them with the digital model so as to allow visualization, for example in a three-dimensional form. Figure 4 illustrates a graphical representation of the situation described in Figure 2, as a function of the data representative of the resistivity obtained by implementing the method of Figure 1.

Claims

CLAIMS 1. Method for non-destructive testing of the conformity of a part (PaC) composed of conductive material, method implemented by a control system (SysC) comprising a local resistivity measurement device (DMLR), the local resistivity measurement device (DMLR) comprising a pair of current injection tips (PI nj) and a pair of voltage measurement tips (PMes), said pairs of tips being aligned, the tips of the pair of current injection tips being arranged on either side of the tips of the pair of measurement tips, the local resistivity measurement device (DMLR) further comprising means for adjusting the spacing of the tips between them, the method comprising: a step (10) of adjusting the spacing of the tips of the local resistivity measurement device (DMLR); a step (20) of obtaining data representative of the resistivity (DrR) of the part (PaC);a step of determining (30), as a function of the data representative of the resistivity (DrR) of the part (PaC), the presence of a defect within the part (PaC).; 2. Control method according to claim 1, characterized in that the step of obtaining (20) data representative of the resistivity of said part to be controlled comprises at least one iteration of the following steps: a current injection step (201), at the current injection peaks of the local resistivity measuring device; a step of measuring (202) a voltage resulting from said current injection, measurement carried out at the measurement peaks of the local resistivity measuring device, allowing the resistivity to be obtained; a step of recording (203) the electrical resistivity at the current location of the local resistivity measuring device; a step of moving (204) the local resistivity measuring device to a following measurement location.

3. Control method according to claim 2, characterized in that the step of recording (203) the electrical resistivity at the current location of the local resistivity measuring device, further comprises recording the current location of the local resistivity measuring device.

4. Control method according to claim 1, characterized in that the step of parameterizing (10) the local resistivity measuring device comprises: a step of adjusting the spacing of the injection tips between them according to a first predetermined spacing parameter; a step of adjusting the spacing of the measurement tips between them according to a second predetermined spacing parameter; a step of adjusting the spacing between a reference measurement tip and a reference injection tip according to a third predetermined spacing parameter.

5. Control method according to claim 1, characterized in that the step of determining (30) the presence of a defect within the part (PaC) is furthermore a function of data representative of the spacing of the tips of the local resistivity measuring device.

6. Control method according to claim 1, characterized in that the step of determining (30) the presence of a defect within the part (PaC) comprises at least one step of comparing at least part of the data representative of the resistivity (DrR) of the part (PaC) with at least one reference datum.

7. Control method according to claim 6, characterized in that said at least one reference data comes from the data representative of the resistivity (DrR) of the part (PaC).

8. Control method according to claim 6, characterized in that said at least one reference data item comes from learning carried out on a set of parts composed of conductive material free from defects.

9. Local resistivity measurement device (DMLR) comprising a pair of current injection tips (Plnj) and a pair of voltage measurement tips (PMes), said pairs of tips being aligned, the tips of the pair of current injection tips being arranged on either side of the tips of the pair of measurement tips, the local resistivity measurement device (DMLR) further comprising means for adjusting the spacing of the tips between them.

10. Device according to claim 9, characterized in that the means for adjusting the spacing of the points between them can be controlled from a parameterization module of said device. 1 1. Device according to claim 9, characterized in that each of the tips of the pairs of tips comprises a return means, so that each of the tips remains in contact with the surface of the part.

12. Device according to claim 9, characterized in that it further comprises motorized displacement means.

13. Non-destructive conformity testing system for a part (PaC) made of conductive material, system comprising a local resistivity measurement device (DMLR) according to claim 9, an electric current generator for transmitting a measurable electric current through the current injection tips of the local resistivity measurement device (DMLR), a detection module, for determining, from the voltage measured by the measurement tips, data representative of the resistivity, a module for recording the data representative of the resistivity and a module for determining, as a function of the data representative of the resistivity (DrR), the presence of a defect within the part (PaC).

14. Computer program comprising instructions for implementing the method according to one of claims 1 to 8, when said instructions are executed by a processor of a computer processing circuit.

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