Emat system for detecting surface and internal discontinuities of electrically conductive structures at high temperatures

Abstract

An EMAT system (1) for detecting surface and internal discontinuities (2) in thick conductive structures (90) at high temperatures, comprising a magnet (4) generating a static magnetic field (SMF) and a HF electric coil (6) for inducing eddy currents in the material (14) or being induced by eddy currents. It comprises a perforated matrix laminated magnetic core (22) placed between the HF electric coil (6) and the material under inspection (3), composed of a plurality of perforated HF active thin layers (29) incorporating ferromagnetic material and perforated insulating passive thin layers (53). Through holes (41, 57) are drilled through each layer (29, 53) and form slotted cylindrical orifices (39). Parallel inductive current loops (43) encircle each magnetic through hole (41) of the HF active thin layers (29). Cooling means (58) force a heat transfer fluid (60) through the slotted cylindrical orifices (39).

Description

Technical Field

[0001] This invention generally relates to non-destructive ultrasonic testing (UNDT) technology. It particularly relates to electromagnetic acoustic transducers (EMAT) for UNT applications, their implementation methods, and their industrial applications.

[0002] The technical field of this invention specifically relates to EMAT transducers:

[0003] a. They are non-vibrational transducers; they do not generate mechanical vibrations, but rather sense and / or receive ultrasonic mechanical vibrations through electromagnetic devices.

[0004] b. To study or analyze materials using a transmitter and / or receiver apparatus adapted to induce or receive ultrasonic waves in or from a conductive test body via an electromagnetic device for testing; and to observe the interior of an object by emitting and / or receiving such ultrasonic waves emitted through the object; and,

[0005] c. Therefore, they belong to the international category of International Patent Classification Int.Cl.G01N29 / 24 and / or the category of U.S. Patent No.Cl.73 / 643.

[0006] The technical field of this invention is limited to EMAT transducers, and they further include:

[0007] a. Equipped with a significant electromagnetic coupling device located between the active electromagnetic portion of the transducer and the test body to increase high-frequency magnetic field coupling between the active electromagnetic portion of the transducer and the surface of the conductive test body (through which eddy currents flow); and,

[0008] b. Having a specific type, wherein the electromagnetic coupling device of this specific type consists of a laminated magnetic core made of a matrix of laminated sheets containing ferromagnetic or ferrimagnetic material; and,

[0009] c. Having a specific type, which is equipped with an active cooling device to dissipate the heat induced on the periphery of the laminate of its electromagnetic coupling device by the current loop.

[0010] The present invention is preferably implemented in a laser EMAT type device and / or an EMAT-EMAT device, which combines the two: an ultrasound generator consisting of a high-power pulsed laser or an EMAT that generates ultrasound, and an ultrasound EMAT receiver.

[0011] The preferred application of the present invention is 3D objective physical scanning and non-destructive ultrasonic UNDT testing, under high throughput of surface and internal discontinuities, in production lines of large and / or thick structures and / or components (made of conductive materials), such as steel slabs in the casting process, in high industrial environments with temperatures above 1000°C.

[0012] This invention can be used to automatically optimize the parameter settings for dynamic reduction (DNS) and / or dynamic secondary cooling (DSC) of continuous casting of steel slabs in steel plants at temperatures above 1000°C. Background Technology

[0013] EMAT technology is used for non-destructive testing of structures made of conductive materials under challenging conditions. Non-destructive testing (NDT) techniques are commonly used in industrial environments for structural monitoring or inspection of structures and components of various shapes and sizes without damaging them. However, the operating conditions and temperatures, implementation types, sizes, and structural complexity of the components being tested limit the number and types of available NDT techniques and their applications. The raw data provided by existing NDT systems are not suitable for precise and in-depth inspection of defects and their 3D location in large components handled under harsh and / or extremely hot operating conditions above 1000°C (e.g., those encountered during continuous casting of a steel slab in a steel mill).

[0014] Ultrasonic nondestructive testing (UNDT) is a family of NDTs based on the propagation of ultrasonic waves within the test object or equipment. In traditional UNDT testing, an ultrasonic probe connected to the diagnostic machine passes over the object being inspected. Traditional UNDT methods use short-wavelength, high-frequency mechanical beams emitted from the ultrasonic generating probe through the material under test and detected by the same probe or another ultrasonic receiving probe to identify structural defects in the component. The main probes used for UNDT testing include piezoelectric transducers, laser transducers, and electromagnetic acoustic transducers (EMAT). Traditional piezoelectric UNDT testing offers many advantages: safety, flexibility, and cost. However, piezoelectric testing has certain limitations: it requires the use of connectors and good surface conditions. Mechanical contact between the test part and the probe is required. Finding suitable connectors for UNDT piezoelectric testing during the testing of hot parts increases with increasing temperature. Generally, piezoelectric UNDT testing cannot be performed above 100°C.

[0015] The main aspect of the prior art of this invention relates to electromagnetic acoustic transducers (EMAT). In UNDT technology, the EMAT method is based on a magnetic coupling mechanism. Sound waves are generated within the material, rather than through contact with the surface of the material of the part under test. EMAT offers significant advantages over conventional piezoelectric transducers. EMAT can generate and receive different wave modes in conductive and ferromagnetic materials without physical contact or liquid coupling with the part under test. This contactless and coupling-free capability increases the reliability of the test because the physical properties of the transmission path remain unchanged. Furthermore, the tolerances required for the position of the part being tested in front of the EMAT probe and for its advancement are flexible. This makes conventional EMAT ideal for industrial applications involving average inspection temperatures (up to 600°C) and poor surface conditions of the parts under test in motion.

[0016] An EMAT probe has two main components: a magnet and an HF coil. The magnet can be a permanent magnet or an electromagnet, generating a static or quasi-static magnetic field. An HF current flows through the coil (or circuit). It is emitted or induced by the high-frequency magnetic field. The EMAT phenomenon is reversible. Therefore, the same EMAT probe can be used both as an ultrasonic transmitter in the material being inspected and as an ultrasonic receiver of the ultrasonic signal emitted by the material being inspected, or a combination of both operating modes. EMAT is used extensively in various applications, including measuring the thickness of metal products, detecting defects in pipes, detecting defects in rails, and detecting defects in steel products.

[0017] Prior art involves attaching a wear-resistant plate to an EMAT (Electrical Electrode Actuator) to protect the magnets and coil circuitry from wear caused by the movement of the EMAT toward the material being inspected. The wear-resistant plate is typically positioned between the material being inspected and the active components of the EMAT, including the magnets and coil circuitry. A disadvantage of conventional wear-resistant plates is the introduction of a higher magnetic reluctance path between the magnetically active portion of the EMAT and the material being inspected.

[0018] A major challenge of conventional EMAT technology is the low magnetic conversion efficiency of EMAT probes for both the static magnetic field generated by the magnet and the HF magnetic field transmitted or received. It is known that introducing a ferromagnetic or subferromagnetic core made of a high-dielectric-constant material between the magnetic transmitter and receiver can increase the induced magnetic field strength by hundreds or thousands of times. The core itself generates a magnetic field, which is added to the transmission field. The magnetic field amplification effect depends on the dielectric constant of the core material. It is also known that the intervention of the core can have negative effects in the case of variable HF magnetic fields, related to the eddy currents generated within the core. These result in significant energy losses, depending on the frequency of the HF magnetic field. When the core consists of a single continuous element, the variable HF magnetic field generates significant eddy currents, arranged in a closed loop according to the current flowing through the entire cross-section of the core, perpendicular to the transmitted variable HF magnetic field. The eddy currents flowing through the core cause significant power losses due to the Joule effect caused by the resistance of its material. This is why existing technologies often use matrix-laminated magnetic cores, which consist of a stack of thin active sheets made of magnetically active material, of the ferromagnetic or ferrimagnetic type, separated by thin insulating passive sheets. These thin insulating passive sheets act as eddy current barriers. In this way, eddy currents can only circulate in narrow loops perpendicular to the emission field within the thickness of each thin magnetically active sheet. Assuming that the current in an eddy current loop is substantially proportional to its loop area, existing matrix-laminated magnetic cores aim to minimize the area of ​​all eddy current loops, which are essentially perpendicular to the emitted HF magnetic field.

[0019] To overcome magnetic reluctance, as known in prior art literature such as U.S. Patent No. 7,546,770B2, EMAT includes a matrix laminated magnetic core constructed in the form of a sandwich matrix comprising multiple thin ferromagnetic laminates arranged in layers. Insulating sheets are sandwiched between the thin ferromagnetic sheets to form the sandwich matrix of the matrix laminated magnetic core. EMAT is specifically and specifically described in this configuration where the HF coil is configured to induce eddy currents on the surface of the material being inspected, rather than to receive eddy currents. Therefore, it should be noted that this prior art relates to and describes a probe configured only as an EMAT transmitter and not as a receiver. The laminated magnetic core is arranged between the magnet and the material being inspected. It is not arranged directly opposite the HF coil. The entire outer surface of the laminated magnetic core is covered with a continuous conductive layer made of a conductive material. It is known that an electric coil having a coil shape and being powered by current generates a bundle of magnetic field lines consisting of a number of magnetic field loops parallel to the axis of a circular helix passing through the interior of the coil. The absolute strength of each magnetic field loop is variable. This depends on its point of passage and its distance from the center of the coil. It is also known that alternating HF magnetic field loops generate eddy currents in the material placed near their center, with their direction substantially perpendicular to the HP magnetic field loop. Therefore, although this is not described in the prior art, it can be understood that when the EMAT operates in HF emission mode, its coils generate multiple alternating HF magnetic field loops in the direction of the core, with variable absolute strength, passing through the center of the helix. The axis of the described coil is substantially parallel to the stacked plane of the sheets. The alternating HF magnetic field loops are therefore substantially parallel to the stacked plane of the laminated core sheets. This results in multiple induced current loops, distributed only on the surface of the continuous conductive layer that completely encloses the laminated core. These induced current loops are topologically distributed on the surface of the conductive layer in a non-uniform, unorganized, continuous, and non-discrete manner. They have variable and non-uniform absolute strengths depending on their position on the continuous conductive layer. They are oriented substantially perpendicular to the stacked plane of the sheets. Therefore, the current loops induced on the surface of the conductive layer are substantially perpendicular to the ferromagnetic laminated sheet. As a result, no periphery of the ferromagnetic laminated sheet is surrounded by induced current loops. The current loop induced on the surface of the conductive layer is mostly parallel to the surface of the object being inspected.

[0020] This prior art laminated magnetic core provides mechanical protection for the magnet and the high-frequency HF coil. It also improves the transmission of static magnetic flux from the magnet to the material being inspected. This laminated magnetic core provides high-frequency, global but low-frequency, fuzzy, and topologically inhomogeneous HF magnetic field coupling between the HF coil and the eddy currents on the surface of the material being inspected facing the probe and the HF coil. This HF magnetic field coupling is achieved globally and non-uniformly by an external continuous conductive layer, rather than selectively and / or locally by each internal thin ferromagnetic laminate.

[0021] According to the prior art, the HF coil is positioned above the magnet, at a considerable distance from the laminated magnetic core and the material being inspected. In this magnet arrangement, additional losses occur during the transmission of HF electromagnetic energy between the HF coil and the material being inspected. EMAT's laminated magnetic core arrangement minimizes flux leakage of the static magnetic field generated by the magnet. However, it reduces the quality of eddy currents at the surface of the material being inspected facing the probe and the HF magnetic field coupling between EMAT's HF coil. This HF magnetic coupling exhibits uneven strength between various locally active portions of the material facing each edge of each ferromagnetic laminate on one side and the HF coil on the other.

[0022] According to this prior art, the laminated magnetic core is thermodynamically passive. It does not include any active cooling device that could actively extract a portion of the heat generated by the current loop induced at the periphery of the ferromagnetic laminated sheet of the core. Such an EMAT without active thermal protection cannot operate reliably and sustainably at temperatures above 600°C.

[0023] In traditional EMAT, this protection of active components is ensured by an electromagnetic passive protection plate, which is made of insulating material and fixed to the operating side of the transducer, keeping its active components away from the material being inspected. The thickness of this protection plate is a trade-off between mechanical resistance, required operating temperature, and EMAT conversion efficiency.

[0024] Existing technologies also provide EMATs equipped with hollow, non-laminated passive magnetic cores. These cores may or may not be equipped with cooling devices for high-temperature operation. However, these existing EMATs do not integrate laminated magnetic cores and cooling devices within such laminated cores, and they do not optimize HF magnetic coupling or homogenize HF magnetic coupling, and / or effectively minimize magnetic flux leakage of the HF magnetic field between the HF coil and the material being inspected.

[0025] The EMAT operating in receive mode receives ultrasonic signals in the same way as the EMAT operating in transmit mode. The receiving direction of the EMAT operating in receive mode can be easily modified electronically. This directivity allows for a high signal-to-noise ratio in the EMAT operating in receive mode.

[0026] The operation of existing EMAT technology is very limited, intended for inspection in harsh industrial environments and / or at temperatures above 1000°C, in order to scan large areas of movable structures in a plate-like manner from a single location through continuous and moving linear scanning, similar to the method used when inspecting pipes and rails at low temperatures.

[0027] The second aspect of the prior art involves laser EMAT UNDT technology, which improves the overall sensitivity of UNDT systems using EMAT, as well as their adaptability to operate at average temperatures up to 600°C. The UNDT phenomenon requires an ultrasonic generator and an ultrasonic receiver.

[0028] A typical laser EMAT system combines an ultrasonic generator made of a high-power pulsed laser with an EMAT operating as an ultrasonic receiver in receive mode. Existing technologies describe such UNDT (Underlying Device Tolerance) combinations for detecting surface and subsurface discontinuities in structures. They are based on the following combined operation: i) an ultrasonic transmitter made of a pulsed laser directs a laser beam to the structure at the target point, generating surface ultrasonic waves and shear waves within the structure when the pulsed laser beam radiation is absorbed by the structure; ii) an ultrasonic receiver made of an EMAT operating in receive mode detects the surface ultrasonic waves and / or shear waves at the detection point. When a high-energy-density laser beam is attracted to the surface of the material of the component being tested (e.g., a steel slab), the localized pulse causes rapid heating, resulting in a plasma explosion on the surface of the component. This explosion generates ultrasonic waves throughout the material of the component. The laser generates two different types of waves in the material. One propagates on or near the surface of the component. This is the most important detectable signal, propagating laterally to the surface of the component. The other propagates deep within most of the material of the component at a wide angle. When the component's material is conductive, the ultrasonic EMAT receiver of the laser EMAT system detects the ultrasonic signals generated in the tested material through a combination of the action of its HF coil and magnet. Vibrations on the material's surface and within (induced by the ultrasonic signals generated by the laser and influenced by the echoes of material discontinuities and their positions) induce HF currents in the detection circuit of the ultrasonic EMAT receiver via eddy currents generated in the material under inspection. The surface and internal discontinuities of the component, located between the laser shock and the EMAT ultrasonic receiver, can therefore be detected by processing the current signal in the HF coil and identifying variations and interferences in the received ultrasonic signals caused by these discontinuities in the tested material.

[0029] These combined DUNT devices demonstrate better efficiency than standalone EMAT devices in discontinuous detection, where the EMAT device is based on an EMAT used in both transmitter and receiver modes. Pulsed lasers are more efficient, more directional, and more powerful as ultrasonic transmitters compared to conventional EMAT transmitters. A major drawback of conventional laser EMAT systems is that they retain the limitations and disadvantages of conventional EMAT receivers used as receivers, as mentioned above. Laser beams can operate at temperatures above 600°C. However, conventional EMATs in the prior art cannot achieve this.

[0030] A third aspect of the prior art of the present invention relates to the optimized automatic adjustment of dynamic soft pressure (DSR) parameters for the continuous casting of steel components (e.g., slab billets and / or steel slabs) in steel mill production at a temperature of approximately 1200°C. The steel slabs are typically subsequently transformed into finished steel products, including sheets, plates, strip coils, tubes, and pipes.

[0031] During the solidification of cast steel billets, there exists a region within the slab that is neither entirely solid nor entirely liquid, existing between the solid and liquid phases of the metal. The percentage of solid in this "pasty" region depends on the thermal properties and composition of the steel. Due to density changes associated with decreasing continuous casting temperature, the steel shrinks as it transitions from a liquid to a solid state. This shrinkage during solidification leads to voids in the interdendritic structure. At the center of the final solidified region, a central segregation zone appears. During the continuous steel casting process of the slab, internal segregation defects and voids at the center of the slab structure have a highly detrimental effect on the properties of the finished steel products subsequently produced from the slab. This central segregation reduces the quality of the steel product, especially thick steel plates. It leads to inconsistent mechanical properties and potential defects in the final steel product.

[0032] Numerous attempts have been made in the prior art to reduce or eliminate center segregation in steel slabs that occurs during continuous casting. A common approach to overcome this problem is to reduce the casting speed. This, of course, affects the overall casting rate. Another approach in the prior art involves applying light reduction (“light reduction” SR) and / or dynamic secondary cooling (DSC) during the final stage of solidification. The basic idea behind any light reduction (SR) is to suppress center macrosegregation and void formation by compensating for solidification shrinkage and interrupting the intake flow of residual steel. SR operations must be performed using pressure rollers or other similar specialized equipment, depending on the appropriate reduction intensity and the vertical direction of the appropriate mushy zone in the final solidification step. SR can only be performed before the center of the steel slab has hardened. The optimal point is the end of the solidification zone. The reduction interval must be located between the two-phase solid-liquid zone and the solidification end of the steel slab; to improve the density and uniformity of the center of the slab. The problem is that the exact location of the optimal point of solidification completion is variable and unknown because it is located at the center of the slab and is therefore invisible according to existing technical means.

[0033] In the "Light Reduction at the End of Solidification" (LSR) method, multiple reduction rolls are arranged at multiple reduction intervals near the location (estimated approximate) of the reduction zone of the slab after solidification and during continuous casting. LSR is a method to gradually reduce the gap at the center of the slab and the generation of molten soft steel flow. Existing techniques employ static light reduction (SSR) provided by adjusting the gap between fixed pinch rolls to improve the internal quality of continuously cast slabs. However, the optimized position of the pinch rolls with fixed reduction intervals is only applicable to a precise set of casting parameters. This means that the casting operation must be kept as stable as possible. The fixed reduction zone of SSR imposes limitations on the entire casting operation. Operational events make it difficult to maintain stable casting parameters for extended periods. Casting parameters such as casting speed and overheating can change during casting. As a result, the solidification range shifts during the process. The SSR method is inefficient.

[0034] To achieve greater operational flexibility while maintaining good internal quality, existing technologies have proposed Dynamic Soft Reduction (DSR) systems, which take into account transient casting conditions, evolving solidification processes, and the behavior of the material being inspected. DSR, combined with or without Dynamic Secondary Cooling (DSC), has been found to be a more effective method than SSR, minimizing segregation and voids in continuously cast slabs. The parameters of DSR must be carefully defined to effectively eliminate center segregation and improve the internal quality of the slab. It is crucial to apply the light reduction process at the correct location during the solidification stage and to ensure precise spacing of the rolls. If DSR occurs too early, the reduction will only deform the outer surface of the slab and will not effectively penetrate to the center. If applied too late, the slab has already fully solidified, resulting in excessive resistance to deformation and excessive load on the rolls of the equipment. The main parameters affecting DSR efficiency and determining the location of Dynamic Soft Reduction are slab size, casting speed, steel composition (thermal properties), and overheating and cooling rates. To achieve efficient dynamic soft-pressure DSR, it is necessary to dynamically control the spacing of the pinch rolls, and preferably their positions, based on the variable actual geometry of the internal solidification process, given the current and historical conditions of the billet casting.

[0035] Providing timely and accurate information such as: i) the dynamic 3D mapping (3DM) of the slab being cast, and / or ii) the 3D location of the central segregation zone and the location of segregation defects in the slab; provided by the casting dynamic 3D mapping system (3DMS), is a fundamental requirement for the effective implementation of dynamic soft-pressure DSR and / or effective dynamic secondary cooling DSC.

[0036] Existing DSR / DSC systems generally include the following methods:

[0037] a. Dynamic 3D Mapping System (3DMS) for Steel Casting;

[0038] b. Computerized DSR optimization system (DSRM), which generates dynamic DSR optimization parameters (PCSD) based on dynamic 3D mapping (3DM) and casting parameters provided by the 3DMS system;

[0039] c. Digital DSR Activator (ASR), which dynamically adjusts the DSR Action Parameters (PASD) as a function of the PCSD generated by the DSRM;

[0040] d. Optionally, the DSC optimization system (DSCM) generates dynamic DSC optimization parameters (PCSC) based on the dynamic 3D mapping (3DM) and casting parameters provided by the 3DMS system;

[0041] e. Optionally, the digital DSC activator (ASC) dynamically adjusts the DSC action parameters (PASC) of the molten steel flow rate of the DSC based on the PCSC generated by the DSCM.

[0042] The algorithm of the computer optimization model DSRM must take into account three important parameters of DSR pressing in detail, such as the location and geometry of the pressing zone, dynamics and pressing rate, and the value of the roller spacing in the pressing zone.

[0043] Existing dynamic 3D mapping systems (3DMS) for steel casting operate solely through simulation. They include:

[0044] a. Based on theoretical algorithms; and based on mathematical models of heat transfer and solidification in slab castings, numerical simulations are performed for prediction; and,

[0045] b. Physical inspection that does not utilize the precise location of the central mushy zone and the discontinuous location in the middle of the slab casting to truly observe the actual dynamic 3D mapping (3DM) from inside the steel slab casting.

[0046] The latest variant of the existing dynamic 3D mapping system (3DMS) for cast steel is specifically manufactured by using an algorithm based on the analysis of 2D thermal tracking data of the slab exterior.

[0047] Existing dynamic 3D mapping systems (3DMS) for steel casting do not provide accurate and reliable definitions for the observed 3D mapping of discontinuities in the reduction / solidification zone of the slab and / or the location of the central mushy zone and / or segregation defects. Parameters of the light reduction DSR, such as the location and geometry of the reduction zone, kinetics and reduction rate, and the roll spacing in the reduction zone, are adjusted by existing technologies based on predictive information (a theoretical model based on the state of the central mushy zone and discontinuities within the slab), which has not been observed and is often illusory. Therefore, DSR and / or DSC parameters are generally unsuitable and ineffective in continuous steel casting machines. They cannot effectively address the segregation and excessive voids in the center of the slab during solidification through properly adjusted dynamic soft reduction and / or secondary dynamic cooling.

[0048] Technical issues

[0049] The analysis of the existing technology above shows that another method is needed to solve the following technical problems of ultrasonic non-destructive testing (UNDT):

[0050] a. Provide a combined solution to the following three technical problems in a single EMAT probe:

[0051] i. Increase the transmission of HF magnetic field energy, maximize HF magnetic coupling and / or minimize magnetic flux leakage between the eddy currents generated by the HF magnetic field on the surface of the coil and the material being inspected; and,

[0052] ii. Surface topological uniformity that provides this high-frequency electromagnetic coupling efficiency between the coil and the eddy currents on the surface of the material being inspected facing the probe; and,

[0053] iii. It has the ability to operate at high temperatures above 1000°C on the material being inspected.

[0054] b. Provide a combined solution to the following two technical problems in a single DNT device:

[0055] i. Optimize the resolution for detecting surface and subsurface discontinuities in thick metal structures; and,

[0056] ii. It has the ability to operate at high temperatures above 1000°C on the material being inspected.

[0057] c. Provide a 3D scanner for conductive structures, offering a combined solution to the following two technical problems:

[0058] i. Performing continuous 3D scans of each line of a large, thick, conductive moving structure (e.g., a metallurgical plate) from specific locations to produce a 3D map of the structure observed at high resolution, including providing locations of discontinuities both on the surface and deep beneath the surface; and,

[0059] ii. It has the ability to operate in harsh industrial environments at high temperatures above 1000°C on the materials being inspected.

[0060] d. Based on the observed internal state of the slab, the DSR action parameters (PASD) of the dynamic soft reduction (DSR) and / or the DSC action parameters (PAS) of the dynamic secondary cooling (DSC) of the continuous casting of steel slabs in the steel plant are automatically optimized and adjusted; by solving a combination of the following four technical problems in a single device:

[0061] i. Continuously provide dynamic 3D mapping (3DM) of the actual observed interior of the slab;

[0062] ii. Based on 3D physical observation, the location of the central mushy zone and / or segregation defects of the slab is continuously defined in a 3D observation manner, rather than simply provided by numerical simulation prediction through theoretical algorithms based on mathematical models;

[0063] iii. Based on 3D physical observation, accurately detect the observed position of the slab pressing point;

[0064] iv. Improve the accuracy and reliability of automatic adjustment of the parameters of dynamic soft pressure (DNS) and / or dynamic secondary cooling (DSC) of slabs in continuous casting at temperatures above 1000°C, so as to reduce segregation defects and voids in the central mushy zone of the slab during the structural melting process in the continuous casting process of steel plants.

[0065] Solution to the problem

[0066] In short, according to one aspect of the present invention, an electromagnetic acoustic transducer (EMAT) for detecting surface and internal discontinuities in an inspected conductive material is provided; this provides a technical solution to the technical problem described in (a) above. For those skilled in the art, the use of a laminated magnetic core in a counterintuitive manner, and unlike the conventional configuration of prior art EMATs, is particularly noteworthy in that:

[0067] a. This invention does not seek to reduce the area of ​​eddy current loops within the active HF layer of the laminated magnetic core. Instead, it aims to increase the area and effect of current loops induced in the (ferromagnetic) active HF layer; however, this is utilized, in a configuration and orientation appropriately topologically organized, to improve coupling efficiency and uniformity, as well as the performance of EMAT.

[0068] b. The EMAT is not configured such that, in the emission mode: i) the alternating HF magnetic field loops induced by the HF coils in the core are substantially parallel to the stacking plane of the laminated core sheet; ii) multiple induced current loops are distributed only on the surface of a continuous conductive layer that completely covers the laminated core; iii) the induced current loops are topologically distributed across the entire surface of the conductive layer in a non-uniform, unorganized, continuous, and non-discrete manner; and iv) these induced current loops are oriented substantially perpendicular to the stacking plane of the sheet. However, in contrast, according to the invention, the EMAT is configured such that, in the emission mode: i) the alternating HF magnetic field loops induced by the HF coils in the core are substantially perpendicular to the stacking plane of the laminated core sheet; and ii) the induced current loops are located only at the periphery of the active HF layer and oriented in a plane parallel to the plane of the active HF layer surrounding them, thus perpendicular to the surface of the object being inspected; iii) the induced current loops are topologically discrete and distributed far apart, but uniformly distributed at the periphery of the active HF layer; and iv) these induced current loops are therefore oriented substantially parallel to the stacking plane of the sheet.

[0069] c. EMAT is not configured such that the active HF layers consist of a solid plate. Instead, according to the invention, the active HF layers are pierced at their centers by through-holes, and rotated about these through-holes perpendicular to their axes, inducing a current loop around the periphery of each active HF layer.

[0070] d. The EMAT does not have an HF coil made of coil circuitry, which is located away from the laminated magnetic core and separated from the core by a magnet, emitting a variable HF magnetic field flux of non-uniform absolute strength in a continuous conductive layer surrounding all active HF thin layers of the magnetic core in emission mode. Instead, according to the invention, the EMAT is configured with an HF coil made of zigzag circuitry, which consists of a series of parallel conductive sections. The magnetic core is not covered by a continuous conductive layer. Each conductive section is traversed by a current of similar absolute strength but in the opposite direction to the adjacent conductive section. The conductive sections are alternately superimposed directly above and on the upper edge of each active HD thin layer of the laminated magnetic core. In emission mode, the HF coil thus emits a variable magnetic field flux of HF of equivalent strength perpendicular to each active HF thin layer.

[0071] e. According to the invention, in emission mode, adjacent active HF thin layers are surrounded by induced current loops rotating in opposite directions. Therefore, in consecutive portions of the frontal region of the material facing each active HF thin layer of the laminated core, a variable HF magnetic field flux in opposite directions is induced for each active HF thin layer, but with quasi-equal absolute intensities in each frontal region facing adjacent active HF thin layers. Consequently, an eddy current matrix formed by parallel vectors is induced on the surface of the material under inspection facing the laminated core, the eddy current matrix being substantially equal in intensity but opposite in direction. This topological configuration results in higher resolution for EMAT. Summary of the Invention

[0072] EMAT includes:

[0073] a. At least one magnet or electromagnet configured to generate a static or quasi-static magnetic field in the material being inspected;

[0074] b. At least one HF coil (or circuit) operating at high frequency, the latter being configured as an HF electromagnetic transmitter transmitting an HF electromagnetic field if the EMAT is used in transmit mode, and / or configured as an HF electromagnetic receiver transmitting an HF electromagnetic field if the EMAT is used in receive mode.

[0075] c. At least one perforated matrix laminated magnetic core configured to concentrate and guide the emission of an HF electromagnetic field; made of a type including a (sandwich) matrix consisting of multiple laminated sheets periodically stacked along the matrix axis.

[0076] The sandwich matrix comprises a plurality of HF active thin layers. These layers are isolated from each other. A magnetic material with high permeability is internally bonded to each layer. Each of these HF active thin layers either has a conductive material integrated externally, and / or is covered externally with a conductive layer at its peripheral edges. A slotted cylindrical aperture passes through each thin layer of the matrix and opens on each of the two transverse matrix faces. Multiple magnetic through-holes of similar size and cross-section, and with closed transverse perimeters, perforate through each of the plurality of HF active thin layers of the matrix and are substantially located at its center. They form the slotted cylindrical openings by alignment. Multiple induced current loops are generated within the HF active thin layers.

[0077] The unique feature of this EMAT lies in its combination of the following techniques: Each magnetic via, fabricated within the HF active thin film of each aperture, is located between a first edge facing the surface being detected and a second edge facing the HF coil. Each magnetic via of the slotted cylindrical aperture contains no rigid material and no electrical conductor passes through it. When the EMAT operates, induced current loops are induced within the active thin film skin at the outer edge of the HF active thin film, substantially parallel and separated from each other. They surround and rotate around the magnetic via of the HF active thin film.

[0078] In a variant embodiment of the present invention, a laser EMAT probe (LEMAT) is proposed for inspecting a material by receiving ultrasonic signals emitted from the material being inspected, in order to provide a technical solution to the technical problem described in (b) above.

[0079] The LEMAT includes:

[0080] a. The EMAT according to the present invention, as described above, is configured in receiving mode for receiving ultrasonic signals from the material being inspected; and

[0081] b. A laser source configured to draw a high-energy laser beam at a target point on the surface of the material being inspected.

[0082] A laser source generates ultrasonic waves, which in turn generate secondary ultrasonic waves that propagate on and / or deep within the surface of the material being inspected. These secondary ultrasonic waves are generated by echoes interacting with discontinuities located on and / or within the material being inspected, and depend on their propagation location on and / or within the material. Under the influence of the static magnetic field emitted by the magnet of the EMAT, the secondary ultrasonic waves induce material eddy currents in the material being inspected. This, in turn, induces emitted HF electromagnetic fields from the material eddy currents within the material being inspected, representing the surface morphology and internal discontinuities of the material.

[0083] In another embodiment of the invention, a multi-laser EMAT 3D scanner (MLEMAT) is proposed for detecting discontinuities on and inside a moving cylindrical conductive structure, in order to provide a technical solution to the technical problem described in (c) above.

[0084] MLMAT includes:

[0085] a. The conductive structure to be 3D scanned;

[0086] b. Chassis frame, configured to surround the conductive structure;

[0087] c. As described above, the plurality of laser EMAT probes (LEMAT) according to the present invention are fixed to a chassis frame, positioned and configured such that each active first edge face of each of their perforated matrix laminated magnetic cores faces the conductive structure; and,

[0088] d. A displacement device configured to linearly move a cylindrical conductive structure relative to the chassis frame.

[0089] The unique feature of this MLEMAT is that an aperture loop, consisting of virtual lines at the center of each continuous slotted cylindrical aperture of each perforated matrix laminated magnetic core of each adjacent MLEMAT, surrounds the conductive structure of the MLEMAT.

[0090] In another embodiment of the invention, an adaptation of the multi-laser EMAT 3D scanner (MLEMAT) according to the invention, as described above, is proposed for automatically adjusting the dynamic soft pressure (DSR) of continuously cast steel slabs at casting temperatures above 1000°C; and a technical solution is provided for the technical problem described above (d).

[0091] The steel slab is continuously pushed through a Dynamic Soft Reduction Device (DSRD) to suppress macroscopic segregation and void formation in the central mushy zone within the slab, thereby dynamically compensating for solidification shrinkage and interrupting the intake flow of residual molten metal in the slab. The HF coil of each laser EMAT in the MLEMAT is connected to a Casting Dynamic 3D Mapping System (3DMS). This 3DMS is equipped with an Analog and Digital Processing Unit (MDAN) configured to combine and process the secondary ultrasonic currents emitted from the coils of each laser EMAT in the MLEMAT, which are induced by material eddy currents in the frontal region of the inspected material in each HF coil of the laser EMAT. These material eddy currents are the result of the interaction between the echo generated by the laser source and discontinuities on and within the frontal region of the inspected material at the first edge face of the laser EMAT. The MDAN combines the secondary ultrasonic currents of each EMAT and, based on the combination and numerical analysis of multiple secondary ultrasonic currents in each laser EMAT of the MLEMAT, generates a dynamic 3D mapping (3DM) of the slab in the structural cross-section of the slab located in the frame plane. The DSR Optimization System (DSRM) for the slab is connected to the 3DMS. It receives the 3DM data of the slab and digitally generates a set of dynamic DSR optimization parameters (PCSD). The Digital DSR Activator (ASR) is connected to the DSRM. It dynamically adjusts the DSR operating parameters (PASD) based on the PCSD generated by the DSRM.

[0092] The unique feature of this MLEMAT lies in the combination of the following technical means. The cooling device of each EMAT according to the invention generates a cooling flow of heat transfer fluid. At a cooling temperature (TF) significantly lower (at least 50°C lower) than the Curie temperature (TC) of the magnetic material in the porous HF active thin layer, this cooling occurs within each magnetic through-hole and each spaced through-hole of the slotted cylindrical aperture in each perforated matrix laminated core of each adjacent MLEMAT. Therefore, dynamic soft reduction (DSR) and / or dynamic secondary cooling (DSC) are automatically and dynamically adjusted at casting temperatures above 1000°C. Attached Figure Description

[0093] These features, aspects, and advantages of the invention will be better understood when the following detailed description is read with reference to the accompanying drawings, in which similar characters represent the same parts, wherein:

[0094] Figure 1 This is a schematic perspective view of the EMAT transducer of the present invention.

[0095] Figure 2 This is a cross-sectional schematic diagram of the EMAT transducer of the present invention.

[0096] Figure 3 This is a schematic perspective view showing one of the operating modes of the HF active thin layer in the perforated matrix laminated magnetic core of the EMAT transducer of the present invention used in the emission mode.

[0097] Figure 4 This is a schematic perspective view showing one of the operating modes of the HF active sheet in the perforated matrix laminated magnetic core of the EMAT transducer of the present invention used in receiving mode.

[0098] Figure 5 This is a schematic perspective view of the perforated matrix laminated magnetic core of the EMAT transducer of the present invention, which is composed of a stack of its HF active thin layer and passive thin layer.

[0099] Figure 6 This is a partial schematic perspective view of the electromagnetic operation of the HF active thin layer of the perforated matrix laminated magnetic core of the EMAT transducer of the present invention in the transmission mode.

[0100] Figure 7 This is a schematic perspective view of some thin sheets of the perforated matrix laminated magnetic core of the EMAT transducer of the present invention, showing the perforated matrix laminated magnetic core dynamically lifted from the material being inspected.

[0101] Figure 8 This is a schematic cross-sectional view of the laser EMAT probe (LEMAT) according to the present invention.

[0102] Figure 9This is a schematic side view of the Multi-Laser EMAT 3D Scanner (MLEMAT) according to the present invention.

[0103] Figure 10 This is a schematic cross-sectional perspective view of the Multi-Laser EMAT 3D Scanner (MLEMAT) according to the present invention, showing the level of its EMAT probe for automatic adjustment of dynamic soft reduction (DSR) and / or dynamic secondary cooling (DSC) in continuous casting of molten steel slabs.

[0104] Figure 11 This is a schematic cross-sectional perspective view of the Multi-Laser EMAT 3D Scanner (MLEMAT) according to the present invention, showing the level of its laser source and the automatic adjustment of dynamic soft reduction (DSR) and / or dynamic secondary cooling (DSC) for continuous casting of molten steel slabs.

[0105] Figure 12 This is a functional block diagram of the Multi-Laser EMAT 3D Scanner (MLEMAT) according to the present invention, for automatic adjustment of dynamic soft reduction (DSR) and / or dynamic secondary cooling (DSC) in continuous casting of molten steel slabs. Detailed Implementation

[0106] The embodiments described below generally relate to an improved EMAT system (1) that can be used for non-destructive control (NDT) of conductive structures (90) at temperatures above 1000°C.

[0107] refer to Figure 1 and Figure 3 We see an electromagnetic acoustic transducer (EMAT) (1) used to detect surface and internal discontinuities (2) in a conductive material under inspection (3). Two magnets (4) are configured to generate a static or quasi-static magnetic field (SMF) in the material under inspection (3). It should be understood that each magnet (4) can be replaced by an electromagnet. An HF coil (6) (or circuit) is placed directly above the perforated matrix laminated magnetic core (22). Its winding plane (7) (or circuit plane) is parallel to the local surface under inspection (8) of the material under inspection (3) facing the EMAT (1). The two magnets (4) are positioned on each side of the perforated matrix laminated magnetic core (22).

[0108] refer to Figure 3According to observation, EMAT (1) can be used in the transmission mode (EM). An HF coil (6) is configured as an HF electromagnetic transmitter (9) that emits an HF electromagnetic field (HFEMF). It is connected to the output of at least one AC current source (11) to drive the HF alternating current (AC) in the HF coil (6) at an ultrasonic frequency. This induces the emitted HF electromagnetic field (HFEMF) in the direction of the material under inspection (3). The emitted HF electromagnetic field (HFEMF) generates material eddy currents (14) on the surface of the material under inspection (3). Through the interaction of the material eddy currents (14) with the static magnetic field (SMF), this generates a Lorentz force (15) in the material under inspection (3) at an ultrasonic frequency. If the material under inspection (3) is ferrimagnetic, this also generates magnetostriction. The disturbance of the Lorentz force (15) directly generates primary ultrasonic waves (17) in the material under inspection (3).

[0109] refer to Figure 4 It can be understood that EMAT (1) can also be used in receiver mode (RM). The HF coil (6) is then configured as an HF electromagnetic receiver (18). It is traversed by a secondary ultrasonic current (19) at the ultrasonic frequency. This HF current includes a secondary ultrasonic electrical signal (88) generated by a transmitting HF electromagnetic field (HFEMF) induced by material eddy currents (14). These material eddy currents (14) are generated on the surface (8) of the material under inspection (3) by secondary ultrasonic waves (21) under the influence of an external ultrasonic source and interact with a static magnetic field (SMF). These material eddy currents (14) represent surface and internal discontinuities (2) of the material under inspection (3).

[0110] Refer again Figure 1 and Figure 2 We see that a perforated matrix laminated core (22) is placed between the inspected surface (8) of the inspected material (3) and the HF coil (6) facing it. The perforated matrix laminated core (22) is configured to concentrate and guide the emitted HF electromagnetic field (HFEMF) toward and / or from the inspected material (3), depending on whether the EMAT (1) is transmitting or receiving. It is of the type comprising a sandwich matrix (23) consisting of multiple laminated sheets (24). They are periodically stacked along the matrix axis (25) between two main matrix faces (26) of the matrix (23), which are parallel to their stacking plane (27). The perforated matrix laminated core (22) has multiple edge faces (35) with laterally adjacent grooves extending substantially perpendicular to the stacking plane (27) and parallel to the matrix axis (25).

[0111] refer to Figure 2We see that one of the edge faces (35), namely the first edge face (36) of the matrix (23), faces the surface (8) of the material (3) being inspected. The other side, namely the second edge face (37) of the matrix (23), is located basically opposite the first edge face (36) and faces the HF coil (6).

[0112] refer to Figure 1 and Figure 5 We see that each laminated sheet (24) of matrix (23) has a similar spatial geometry and lateral dimensions to its adjacent sheets (24) in matrix (23). They have two main lateral sheet surfaces (32), each parallel to the stacking plane (27).

[0113] Refer again Figure 1 and Figure 5 As can be seen, the consecutive adjacent outer edges (33) of each sheet (24) form the grooved edge surface (34) of the matrix (23) around the matrix axis (25). The core axis (38) of the matrix (23) substantially connects the centers of the first edge surface (36) and the second edge surface (37). It is positioned substantially perpendicular to the matrix axis (25).

[0114] refer to Figure 5 and Figure 6 As can be seen, the matrix (23) comprises HF active thin layers (29) (four of which are shown in the figure) or a first group (28) of such thin layers. Each HF active thin layer (29) is isolated from each other. It is internally bonded with a magnetic material (particularly ferromagnetic or ferrimagnetic) with high permeability. The magnetic material has a certain Curie temperature (TC). It is externally bonded with a conductive material. Alternatively, it may be externally covered with a conductive layer on its peripheral edge (33). A slotted cylindrical aperture (39) passes through each sheet (24) of the matrix (23) along the aperture axis (40), which is substantially parallel to the matrix axis (25) and perpendicular to the core axis (38). It is open on each of the two matrix faces (26). Multiple magnetic through holes (41) with similar cross-sectional dimensions and closed perimeters are perforated through the center of each of the multiple HF active thin layers (29) along an axis substantially parallel to the surface being inspected (8), thus hollowing out the matrix (23). They are aligned along an axis parallel to the surface being inspected (8) to form grooved cylindrical orifices (39) through their alignment. They have a longitudinal envelope (42) of through holes, arranged along the orifice axis (40) of the matrix (23), and their lateral periphery is closed. (See reference) Figure 3 and Figure 4 As can be seen, when EMAT(1) is operating, the emitted HF electromagnetic field (HFEMF) induces multiple closed induced current loops (43). When EMAT is in Figure 3 In the transmission mode shown, the latter is either emitted by HF alternating current (AC) at the ultrasonic frequency in the HF coil (6); and / or when EMAT is in Figure 4 In the receiving mode shown, the latter is emitted by material eddy currents (14) at ultrasonic frequencies in the material being inspected (3). The induced current loop (43) is located within the active thin-layer skin (48) surrounding each HF active thin layer (29) of the perforated matrix laminated magnetic core (22). As shown... Figure 6 As shown, they are arranged according to loop mapping (LM), which defines the topology, distribution and relative positions of all induced current loops (43).

[0115] refer to Figure 2 The following characteristics of EMAT(1) were observed. Each magnetic via (41) in each HF active thin layer (29) is located between a first edge face (36) facing the surface under inspection (8) and a second edge face (37) facing the HF coil (6). Each magnetic via (41) of the slotted cylindrical aperture (39) contains no hard material. In particular, no electrical conductor passes through it. Reference Figure 6 As can be seen, the loop mapping (LM) is topologically discrete and consists of multiple induced current loops (43) in each HF active thin layer (29) (or such group of active thin layers) that are far apart from each other. Reference Figure 3 As can be seen, the induced current loops (43) (or such loop groups) are induced within the active thin-layer skin (48) on the outer edge (33) of the HF active thin layer (29). Each of them is arranged along a plane parallel to the stack plane (27) and substantially perpendicular to the surface of the material (3) being examined. They are substantially parallel and separated from each other between their respective HF active thin layers (29). They surround and rotate around the magnetic via (41) of their HF active thin layer (29). Reference Figure 6 As can be seen, the perforated matrix laminated core (22) located between two adjacent HF active thin layers (29) (or groups) and each core-spacing slice (49) on its surface has no induced current loop (43), or more generally, no induced current.

[0116] refer to Figure 3As can be seen, the emitted HF electromagnetic field (HFEMF) and the perforated matrix laminated core (22) are configured such that when EMAT (1) is operating, the HF core magnetic field (HFIMF) has a large component of the HF core transverse magnetic field (MFTHF), which is perpendicular to the stack plane (27), perpendicular to each HF active layer (29), and substantially parallel to the surface of the material under inspection (3). The HF magnetic flux (MFHF) within the perforated matrix laminated core (22) has a large component perpendicular to the core axis (38) and parallel to the surface of the material under inspection (3). Therefore, it is not perpendicular to the surface under inspection (8) of the material under inspection (3). The closed induced current loop (43) is generated by the HF core transverse magnetic field (MFTHF) on the outer edge (33) of each HF active layer (29).

[0117] refer to Figure 5 and Figure 6 It is understandable that a dual physical effect of combination and interaction occurs within the perforated matrix laminated magnetic core (22). On the one hand, each of the multiple parallel and topologically discrete induced current loops (43) in each perforated HF active thin layer (29) generates a high-frequency magnetic field. This separately and locally increases the discrete and selective high-frequency magnetic coupling between the narrow local active portion (44) of the surface under inspection (8) facing its first edge (36) and the HF coil (6). The parallel induced current loops (43) of the HF active thin layer (29) contribute to the overall reduction of the high-frequency magnetoresistance of the EMAT (1). On the other hand, the inner periphery (45) of each magnetic via (41) in each HF active thin layer (29) of the matrix (23) generates a thermally conductive and convection surface (46) at the center of its HF active thin layer (29). This produces an internal thermal cooling effect to dissipate a portion of the local electrical and thermal energy generated by the specific induced current loop (43) of each HF active thin layer (29). This helps improve the efficiency of EMAT(1).

[0118] refer to Figure 5We see that the perforated matrix laminated core (22) is separated from its HF active thin layer (29) by a passive thin layer (53). Each perforated HF active thin layer (29) (or such group of active thin layers) of the matrix (23) is separated from the adjacent HF active thin layer by at least one piece of the second group (54) of passive thin layers (53) made of electrically insulating material at the level of adjacent core spacing slices (49). Each passive thin layer (53) is perforated by spacer vias (57). Each passive thin layer (53) is positioned and configured such that the magnetic vias (41) in the first group (28) of the HF active thin layers (29) of the matrix (23) and the spacer vias (57) in the second group (54) of the passive thin layers (53) of the matrix (23) are aligned parallel to the matrix axis (25). They form a slotted cylindrical aperture (39) by their alignment and their combination.

[0119] This configuration of the electromagnetic acoustic transducer (EMAT) (1) has the following characteristics. Each spacer via (57) in each passive layer (53) is located between a first edge face (36) facing the material being inspected (3) and a second edge face (37) facing the HF coil (6). There is no rigid material inside each spacer via (57) of the slotted cylindrical aperture (39). In particular, no electrical conductor passes through it. It is understood that the inner periphery of each spacer via (57) in each passive layer (53) of the matrix (23) freely forms a thermally conductive and convection surface (46) within the center of the passive layer (53). This creates an internal thermal cooling effect in the spacer via (57) to dissipate a portion of the electrical and thermal energy generated by the induced current loop (43) of the adjacent HF active layer (29). This contributes to improving the efficiency of the EMAT (1).

[0120] like Figure 5 As shown, the present invention proposes that for each passive thin layer (53), the outer periphery edge (33) of its periphery is not covered with any conductive material on its surface. In this way, the slotted edge surface (34) of the perforated matrix laminated magnetic core (22) is not continuously covered with conductive layers and / or made of conductive layers, but rather it consists of alternating edges and rims, one side made of conductive rings around the HF active thin layer (29) and the other side made of insulating rings around the passive thin layer (53).

[0121] According to a preferred embodiment of the present invention, it appears Figure 5In the EMAT (1), the perforated matrix laminated magnetic core (22) includes cooling devices (58). These generate a cooling flow (59) of heat transfer fluid (60) at a cooling temperature (TF). This cooling flow (59) is forced through slotted cylindrical orifices (39) of the matrix (23). This configuration of the EMAT (1) has the following characteristics. The cooling flow (59) is configured to pass continuously through one of the magnetic through-holes (41) of the first group (28), or through at least one of the spacer through-holes (57) of the second group (54). It runs along all the hole wall surfaces (62) of each consecutive magnetic through-hole (41) and / or each spacer through-hole (57) of the matrix (23). It is understood that this increases the internal thermal cooling effect in each HF active thin layer (29) of the matrix (23); each of which undergoes an induced current loop (43) and heat dissipation. The present invention proposes that the cooling temperature (TF) of the cooling flow (59) be adjusted to be significantly lower (at least 50°C lower) than the specific Curie temperature (TC) of the magnetic material of each porous HF active thin film (29).

[0122] refer to Figure 7 An advantageous alternative embodiment of the EMAT (1) of the present invention can be seen. At least one (and preferably multiple) sheet (24) of the perforated matrix laminated magnetic core (22) is pierced by buffer holes (63); or is provided with buffer slots (64). These openings pass through an annular wall (65) formed between their through holes (41, 57) and portions of their first edge faces (36) facing the material being inspected (3) in a direction parallel to the stack plane (27). This creates buffer recesses (66) between the through holes (41, 57) of the sheet (24) and the first edge faces (36) facing the material being inspected (3). A cooling device (58) is configured to extract a buffer fluid flow (67) from the cooling flow (59) flowing through the through holes (41, 57). The extracted buffer fluid flow (67) flows under pressure through the buffer recesses (66). This creates a lifting air buffer (70) between the perforated matrix laminated core (22) and the material under inspection (3) at the level of the buffer recess (66) facing the material under inspection (3). This lifts the perforated matrix laminated core (22) above the material under inspection (3) with a buffer gap (68). This arrangement is reliable. It provides automatic mechanical adjustment of the buffer gap (68). Understandably, this arrangement significantly reduces conduction between the material under inspection (3) and the perforated matrix laminated core (22) and the heat transferred toward the active components. This arrangement eliminates friction. It significantly increases the operating time and availability of the EMAT (1) by limiting wear between maintenance phases.

[0123] refer to Figure 5A variant embodiment of the EMAT (1) of the present invention is shown. The two outer lateral edge surfaces (35) of the two outer sheets located on the matrix surface (26) are formed or covered by conductive capping layers (69) of conductive material (as shown). This configuration of the EMAT (1) has the following characteristics: Through-holes with lateral dimensions similar to magnetic through-holes (41) perforate through each of the two conductive capping layers (69). The sheets (24) of the matrix (23) and the two conductive capping layers (69) are positioned relative to each other such that their plurality of through-holes are aligned to continuously form grooved cylindrical apertures (39).

[0124] According to a preferred variation of the invention, such as in Figure 5 As described, the periphery of each magnetic via (41) formed in each HF active thin layer (29) is rectangular. The center of each magnetic via (41) is substantially located at and centered on the centroid of the HF active thin layer (29). And the periphery of each magnetic via (41) is substantially positioned at a constant ring distance (Rd) from the periphery of the outer edge (33) of its HF active thin layer (29). It can be understood that in this configuration, each HF active thin layer (29) is topologically configured as a rectangular active ring (71) that is thermodynamically cooled by heating from the induced current loop (43) generated around it.

[0125] refer to Figure 1 and Figure 2 This illustrates a preferred alternative embodiment of the EMAT (1) of the present invention. The second edge face (37) of the perforated matrix laminated magnetic core (22) faces directly towards the HF coil (6). No magnet (4) or any other element is positioned between the second edge face (37) of the matrix (23) on one side and the HF coil (6) on the other side.

[0126] refer to Figure 6 Another preferred embodiment of the EMAT (1) of the present invention can be seen. The first group (28) of the HF active thin layers (29) in the HF coil (6) and the matrix (23) is configured such that the orientation, pitch, size and shape of each circuit-facing edge (72) of each HF active thin layer (29) located in the second edge surface (37) of the matrix (23) and facing the HF coil (6) are consistent with and related to the geometric parameters of the orientation, pitch, size and shape of the conductor portion (75) of the HF coil (6) that successively faces each of these circuit-facing edges (72).

[0127] refer to Figure 3The preferred arrangement described above is thus achieved. It can be seen that the HF coil (6) has at least one linear conductor portion (73). This portion is positioned near and directly above the circuit-facing edge (72). It is tangent to the axis of this portion, parallel to the periphery of the HF active thin layer (29), which is located in the second edge face (37) of the matrix (23) facing the HF coil (6). It can be seen that the particularity of this arrangement of the invention lies in the fact that the linear conductor portion (73) and the perforated matrix laminated core (22) are configured such that when the EMAT (1) is operated, the induced current loop (43) is induced in the active thin layer skin (48) surrounding the HF active thin layer (29). It surrounds its magnetic through-hole (41). This provides locally selective HF magnetic coupling between, on the one hand, the HF alternating current (AC) driven in the linear conductor portion (73) extending along the periphery of the HF active thin layer (29) and on the other hand, the material eddy currents (14) generated in the narrow local active portion (44) of the surface under inspection (8) facing the HF active thin layer.

[0128] It is known that the emitted HF electromagnetic field (HFEMF) emitted by the linear conductor section (73) through which the current flows is orthogonal radial. Therefore, the lines of HF magnetic flux (MFHF) are essentially composed of circles surrounding the linear conductor section (73).

[0129] If EMAT(1) is in transmit mode (EM), such as Figure 3 As shown, the HF alternating current (AC) flowing through the linear conductor section (73) generates orthogonal radial magnetic flux organized into loops, creating conductor HF magnetic flux loops (76), thereby generating an HF core transverse magnetic field (MFTHF) that is substantially perpendicular to the HF active thin film (29) facing it. This generates induced current loops (43) on the surface of the active ring (71) of the HF active thin film (29). These induced current loops (43) in turn emit multiple HF magnetic flux loops that generate material eddy currents (14) that are topologically ordered and oriented entirely along axes substantially parallel to the plane of the HF active thin film (29), which faces directly above and near them.

[0130] It is also known that a circular turn supplied with current generates a bundle of magnetic field lines in the form of multiple magnetic flux loops parallel to the axis of the circular turn and passing through its center.

[0131] refer to Figure 4It can be understood that when EMAT (1) is used in receiving mode (RM), the component of material eddy currents (14) generated on the material surface under the influence of an external ultrasonic source, parallel to the stacked plane (27), induces a material HF flux loop (77), generating an HF core transverse magnetic field (MFTHF) substantially perpendicular to the active ring (71) of the HF active thin layer (29) facing these material eddy currents (14). This generates an induced current loop (43) within its active thin layer skin (48). The induced current loop (43) longitudinally surrounding the HF active thin layer (29) then emits multiple HF flux loops that surround the linear conductor portion (73) tangential to it along an axis parallel to a portion of the periphery of the HF active thin layer (29). This inductively generates a secondary ultrasonic electrical signal (88), which generates HF alternating current (AC) in the linear conductor portion (73).

[0132] According to what appears Figure 3 and Figure 6 In a preferred embodiment of the invention, the HF coil (6) is a tortuous circuit (74). It has multiple (at least two) linear conductor sections (73). Figure 6 Four are shown in the diagram. They are parallel and adjacent to each other. Multiple linear conductor portions (73) of the zigzag circuit (74) are successively positioned near and directly above one of the circuit-facing edges (72) of the HF active thin layer (29), which is located in the second edge face (37) of the matrix (23) facing the HF coil (6). They are configured such that the HF alternating current (AC) passing continuously through each of the parallel and adjacent linear conductor portions (73) of the zigzag circuit (74) is oriented in alternating opposite directions. It can be seen that the conductor HF flux loop (76) surrounds each linear conductor portion (73) of the zigzag circuit (74) substantially perpendicularly and penetrates the interior of the HF active thin layer (29) facing it substantially perpendicularly. It can also be seen that this arrangement includes the following features. The linear conductor portion (73) of the zigzag circuit (74) and the perforated matrix laminated core (22) are configured such that when the EMAT (1) is in transmit mode (EM), two adjacent HF active thin layers (29), covered by two adjacent linear conductor portions (73), are traversed by two adjacent induced current loops (43) in their active thin layer skins (48). Each of them consists of alternating HF currents rotating in opposite directions of rotation (78), one clockwise and the other counterclockwise.

[0133] refer to Figure 1As can be seen, the depth (Od) of the slotted cylindrical aperture (39) of the perforated matrix laminated core (22) along its aperture axis (40) is substantially equal to and consistent with the first lateral dimension (FTd) of the HF coil (6) of the EMAT (1). Furthermore, the slotted second edge surface (37) of the perforated matrix laminated core (22) facing the HF coil (6) has a lateral dimension in the direction perpendicular to the aperture axis (40) of the sandwich structure (23), which is substantially equal to and consistent with the second lateral dimension (STd) of the HF coil (6) of the EMAT (1).

[0134] According to a preferred embodiment of the present invention, such as in Figure 5 The sheet geometry (79) of the perforated sheet (24) of the matrix (23) and the combined geometry of its perforated matrix laminated core (22) are chosen to be decorrelated to the wavelength of the main harmonics of the emitted HF electromagnetic field (HFEMF). It can be understood that this prevents mechanical resonance of its perforated matrix laminated core (22) at the ultrasonic frequency of the EMAT (1) operation.

[0135] According to another preferred embodiment of the invention, the sheet geometry (79) of the perforated sheets (24) of the perforated matrix laminated magnetic core (22) is selected such that, at the ultrasonic frequencies of the EMAT (1) operation, they are either much smaller than the wavelength of the ultrasonic waves generated in these sheets (24) or substantially equal to an odd number of quarters of the wavelength of the ultrasonic waves generated in these sheets (24).

[0136] According to another preferred configuration of the invention, such as Figure 2 As shown, the first grooved edge surface (36) of the perforated matrix laminated magnetic core (22), facing the material under inspection (3) and parallel to the grooved cylindrical aperture (39), is covered or covered with an insulating layer (81) made of an electrically insulating material (as shown). One side of the insulating layer (81) is arranged facing the grooved cylindrical aperture (39) and covers the edge of the first edge surface (36), which belongs to the periphery of each HF active thin layer (29).

[0137] The EMAT (1) of the present invention and its variants explained above provide a technical solution to the above-mentioned technical problem (a). The EMAT (1) increases the energy transfer of the emitted HF electromagnetic field (HFEMF). It maximizes HF magnetic coupling and minimizes magnetic flux leakage of the emitted HF electromagnetic field (HFEMF) between the HF coil (6) and the material eddy currents (14) generated on the surface of the material under inspection (3). It ensures the surface topological uniformity of this high-frequency electromagnetic coupling efficiency between the HF coil (6) and the material eddy currents (14) of the material under inspection facing the transducer. It operates at high temperatures above 1000°C on the material under inspection (3).

[0138] refer to Figure 8 As can be seen, the laser EMAT probe (LEMAT) (82) inspects the material (3) by receiving ultrasonic signals from the material being inspected (3). The LEMAT comprises the following combination: i) an electromagnetic acoustic transducer (EMAT) (1) according to the invention as described above, and ii) a laser source (84). The EMAT (1) is configured in receive mode (RM) for receiving secondary ultrasonic electrical signals (88) from the material being inspected (3). The HF coil (6) is configured as an HF electromagnetic receiver (18). Figure 4 As shown, the secondary ultrasonic electrical signal (88) is electrically induced by the emitted HF electromagnetic field (HFEMF), which is emitted by the material under inspection (3) and generated by material eddies (14), which are generated in the material under inspection (3) by the secondary ultrasonic wave (21). These material eddies (14) represent surface and / or internal discontinuities (2) of the material under inspection (3). Figure 8 As shown, the perforated matrix laminated magnetic core (22) is located between the HF coil (6) of the EMAT (1) and a local surface of the material under inspection (3). It faces directly towards the HF coil (6). It maintains a protective gap (83) between the material under inspection (3) and the HF coil (6). It reduces the magnetic reluctance of the EMAT (1). It is protected by active thermodynamics from the high temperature and difficult surface conditions of the material under inspection (3). The laser source (84) is configured to draw a high-energy laser beam (85) at a target point (86) on the surface of the material under inspection (3). The laser beam (85) generates primary ultrasonic waves (17) that propagate on and / or inside the material under inspection (3). This results in the generation of secondary ultrasonic waves (21), which are caused by the echoes of the primary ultrasonic waves (17) interacting with discontinuities (2) on and / or inside the material under inspection (3). These secondary ultrasonic waves (21) propagate on and / or inside the material under inspection (3). These result in material eddies (14) on the surface of the material being inspected (3), which are caused by the mechanical vibration of secondary ultrasonic waves (21) under the influence of the static magnetic field (SMF) generated by the magnet (4) of the EMAT (1). This leads to the induction of the emitted HF electromagnetic field (HFEMF) emitted by the material eddies (14) present on the surface of the material being inspected (3), representing the geometry and location of the surface and interior discontinuities (2) of the material being inspected (3). Processing this emitted HF electromagnetic field (HFEMF) by the EMAT (1) generates a secondary ultrasonic electrical signal (88) in the HF coil (6).

[0139] refer to Figure 4EMAT (1) was configured in receive mode, and the laser EMAT probe (LEMAT) (82) was found to have the following technical characteristics. Under the influence of the laser source (84), multiple remote induced current loops (43) are induced in the active thin layer skin (48) on the outer edge (33) of each HF active thin layer (29) of the perforated matrix laminated magnetic core (22) by the emitted HF electromagnetic field (HFEMF) emitted by the material eddy current (14) in the material under inspection (3). Figure 6 As shown, these eddy current loops (43) of each HF active thin layer (29) (or group) are spaced apart from each other. These eddy current loops (43) rotate around and about a magnetic active ring (71) surrounding a magnetic through-hole (41) of the HF active thin layer (29). They are located between a first edge surface (36) facing the material being inspected (3) and a second edge surface (37) facing the HF coil (6). They are positioned substantially perpendicular to these two edge surfaces (36, 37).

[0140] It should be understood that in this LEMAT (82), a dual physical effect of combination and interaction occurs within the perforated matrix laminated core (22). On the one hand, such as Figure 4 Each of the multiple discrete and parallel induced current loops (43) in each porous HF active thin film (29) (or group) generates a high-frequency magnetic field. This increases the high-frequency magnetic coupling between the locally effective portion (44) of the surface under inspection (8) facing the first edge surface (36) and the HF coil (6), respectively and locally. This homogenizes the high-frequency coupling and contributes to the overall reduction of the high-frequency magnetoresistance of the EMAT (1) through interaction. On the other hand, as... Figure 5 As it appears, the inner periphery (45) of each magnetic via (41) in each HF active thin layer (29) of the matrix (23) generates an internal free thermal conduction and convection surface (46) at the center of its HF active thin layer (29). This produces an internal thermal cooling effect to dissipate a portion of the electrical and thermal energy generated by the induced current loop (43) of its particular HF active thin layer (29). This contributes to improving the efficiency of the EMAT (1).

[0141] The LEMAT (82) of the present invention provides a technical solution to the above-mentioned technical problem (b). It optimizes the resolution of surface, subsurface and deep subsurface discontinuities (2) in thick metal structures. It operates at high temperatures (3) on the inspected material above 1000°C.

[0142] refer to Figure 9A multi-laser EMAT 3D scanner (MLEMAT) (89) can be seen for detecting surface and / or internal discontinuities (2) within a moving cylindrical conductive structure (90). The MLEMAT (89) comprises: a) the conductive structure (90) to be 3D scanned; b) a chassis frame (93); c) a probe group (96) made of at least two laser EMAT probes (LEMAT) (82) according to the invention; and d) a displacement device (97). The conductive structure (90) to be 3D scanned is made of a conductive material to be inspected (3). It has a cylindrical structure generated along a structural axis (91) and a substantially constant structural cross section (92). The chassis frame (93) is configured to surround the conductive structure (90) at a frame distance (Fd). Its frame plane (95) is substantially perpendicular to the structural axis (91) of the conductive structure (90). The displacement device (97) is configured to move the cylindrical conductive structure (90) linearly relative to the chassis frame (93) along the displacement direction (Md) (which is substantially coincident with the structural axis (91)).

[0143] The Multi-Laser EMAT 3D Scanner (MLEMAT) (89) has a reference Figure 10 The following features appear: the aperture loop (99) formed by the virtual line at the center of each continuous slotted cylindrical aperture (39) of the perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the laser EMAT probe (LEMAT) (82) connecting MLEMAT (89) surrounds the conductive structure (90).

[0144] It can also be seen that a probe group (96) made of laser EMAT probes (82) is fixed on the chassis frame (93) and positioned and configured in such a position that multiple adjacent first edge surfaces (36) facing the material (3) to be inspected, adjacent to the perforated matrix stacked magnetic core (22) of each adjacent laser EMAT probe (LEMAT) (82), are juxtaposed, substantially in contact with each other, and form a substantially continuous grooved inspection ring (100). The grooved inspection ring (100) surrounds and covers the periphery of the conductive structure (90) in the structural cross section (92) of the conductive structure (90) near the frame plane (95).

[0145] In a preferred embodiment of the Multi-Laser EMAT 3D Scanner (MLEMAT) (89), as referenced Figure 11Each MLEMAT (82) laser source (84) consists of an optical fiber (101) fixed to the frame plane (95) with a target end (102) facing the conductive structure (90). Each optical fiber (101) is connected to a laser generator (103). This configuration of the multi-laser EMAT 3D scanner (MLEMAT) (89) has the following characteristics: A laser target loop (104), consisting of a virtual line connecting the target ends (102) of each adjacent laser EMAT probe (LEMAT) (82) of the MLEMAT (89), surrounds the conductive structure (90) and is substantially parallel to the aperture loop (99).

[0146] In a preferred alternative embodiment of the multi-laser EMAT 3D scanner (MLEMAT) (89) of the present invention, it is operated to detect surface and / or internal discontinuities (2) of a metallurgical plate (105). A conductive structure (90) then forms a cylindrical metallurgical plate (105) movable relative to the MLEMAT (89). An aperture loop (99), consisting of a virtual line at the center of each continuous slotted cylindrical aperture (39) of the perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) connecting the MLEMAT (89), surrounds the movable cylindrical metallurgical plate (105).

[0147] In another preferred embodiment of the Multi-Laser EMAT 3D Scanner (MLEMAT) (89) of the present invention, it is used to detect surface and / or internal discontinuities (2) of a moving cylindrical slab (105) continuously cast in a steel mill at a casting temperature (TS) above 1000°C. The porous HF active thin layer (29) of each perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the MLEMAT (89) is made of a magnetic material, such as a ferromagnetic or ferrimagnetic type, with a Curie temperature (TC) below the casting temperature (TS). This Multi-Laser EMAT 3D Scanner (MLEMAT) (89) has the following characteristics: Figure 10 As shown, each slotted cylindrical aperture (39) of each perforated matrix laminated core (22) of each adjacent LEMAT (82) of MLEMAT (89) is connected to a cooling device (58), which generates a cooling flow (59) of heat transfer fluid (60). At a cooling temperature (TF) that is significantly lower (at least 50°C lower) than the Curie temperature (TC) of the magnetic material of the porous HF active thin layer (29), the heat transfer fluid (60) is forced under pressure into each through-hole (41, 57) of the slotted cylindrical aperture (39) of each perforated matrix laminated core (22) of each adjacent LEMAT (89) of MLEMAT (89).

[0148] The MLEMAT (89) of the present invention and its variations detailed above provide a technical solution to the above-described technical problem (c). The MLEMAT performs continuous 3D scanning of a line from a single location on a large, thick, moving conductive structure (90) (e.g., a metallurgical plate (105)), producing a 3D map of the structure observed at high resolution, including providing locations of surface and subsurface discontinuities (2). It operates at high temperatures (above 1000°C) on the material under inspection (3).

[0149] refer to Figure 12 As can be seen above, the multi-laser EMAT 3D scanner (MLEMAT) (89) according to the present invention is configured to automatically adjust the dynamic parameters of the dynamic soft reduction (DSR) of the billet of a steel slab (105) continuously cast in a steel mill at a casting temperature (TS) above 1000°C. The billet of the steel slab (105) is continuously pushed by the dynamic soft reduction device (DSRD) to suppress the formation of macroscopic segregation zones and void zones within the billet of the steel slab (105); thereby dynamically compensating for the solidification shrinkage of the steel and interrupting the absorption flow rate of residual molten metal in the central mushy zone (106) of the steel slab (105).

[0150] This MLMAT (89) is coupled to a dynamic soft reduction device (DSRD), which includes: i) a dynamic 3D mapping system (3DMS) that generates a dynamic 3D mapping (3DM) of the billet (105); ii) a computer DSR optimization system (DSRM) that generates dynamic DSR optimization parameters (PCSD) based on the dynamic 3D mapping (3DM) and continuous casting parameters; and iii) a digital DSR activator (ASR) that dynamically adjusts the DSR action parameters (PASD) of the dynamic soft reduction device (DSRD) based on the PCSD generated by the DSRM.

[0151] This multi-laser EMAT 3D scanner (MLEMAT) (89) has the following features. The HF coils (6a, 6b, 6) of each EMAT (1a, 1b, 1) of each laser EMAT (82a, 82b, 82) of the MLEMAT (89) are respectively connected to a dynamic 3D mapping system (3DMS). They transmit to it secondary ultrasonic electrical signals (88a, 88b, 88) induced in each HF coil (6a, 6b, 6) by material eddies (14) on the frontal area (110) of the inspected material (3) of the steel slab (105) partially facing each EMAT (1a, 1b, 1). The DSR optimization system (DSRM) is equipped with an analog and digital processing unit (MDAN). The MDAN is configured to receive multiple secondary ultrasonic currents (19a, 19b, 19) including those in each HF coil (6) passing through each laser EMAT (82a, 82b, 82) of the MLEMAT (89). MDAN is also configured to identify variations and disturbances in each secondary ultrasonic electrical signal (88a, 88b, 88) of each laser EMAT (82a, 82b, 82) caused by discontinuities (2) in the local active portions (44a, 44b, 44) of each laser EMAT (82a, 82b, 82) of the inspected material (3), and to digitally derive and generate the defect frontal topology (DTa, DTb, DT) of the local active portion (44a, 44b, 44). MDAN is also configured to combine and digitally analyze the combined signals of multiple secondary ultrasonic electrical signals (88a, 88b, 88) in the front area (110) facing the inspection ring (100) in the structural section (92) of the frame plane (95), digitally combine the defect front topology (DTa, DTb, DT), and digitally generate a three-dimensional dynamic 3D mapping (3DM) of the interior of the slab (105) physically observed by MLEMAT (89).

[0152] like Figure 10 As shown, the cooling device (58) generates a cooling flow (59) of heat transfer fluid (60), which is pushed under pressure into each through hole (41, 57) of the slotted cylindrical aperture (39) of each perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the MLEMAT (89); this is carried out at a cooling temperature (TF) significantly lower than (at least 50°C lower) the Curie temperature (TC) of the magnetic material of the porous HF active thin layer (29).

[0153] It is understandable that, due to the MLEMAT (89), the DSR action parameters (PASD) of the dynamic soft reduction device (DSRD) can be dynamically adjusted in an optimized manner based on the dynamic 3D mapping (3DM) of the slab (105) of the steel billet physically observed by the MLEMAT (89), which is carried out at casting temperatures (TS) above 1000°C.

[0154] refer to Figure 12 A variant of the Multi-Laser EMAT 3D Scanner (MLEMAT) (89) is shown for automatically adjusting the dynamic parameters of Dynamic Soft Reduction (DSR), which further allows for dynamic secondary cooling (DSC) of the billet of a steel slab (105) continuously cast in a steel mill at casting temperatures (TS) above 1000°C. The MLEMAT (89) is coupled to a Dynamic Secondary Cooling Device (DSCD), which further includes a Computerized DSC Optimization System (DSCM) that generates dynamic DSC optimization parameters (PCSC) for dynamic secondary cooling (DSC) based on a dynamic 3D mapping (3DM) of the billet of the steel slab (105) through the combination and digital analysis of multiple secondary ultrasonic electrical signals (88a, 88b, 88) in each laser EMAT (82a, 82b, 82) of the MLEMAT (89) and the analysis of casting parameters in the structural section (92) of the frame plane (95). It also includes a digital DSC activator (ASC) based on the PCSC generated by the DSCM (which is based on the dynamic 3D mapping (3DM) physically observed by MLEMAT (89)) and the DSC action parameters (PASC) that dynamically adjust the molten steel flow rate of the dynamic secondary cooling (DSC).

[0155] The MLEMAT (89) of the present invention, which automatically adjusts DSR and / or DSC, provides a technical solution to the aforementioned technical problem (d). It ensures that the DSR action parameters (PASD) of the dynamic soft reduction (DSR) and / or the DSC action parameters (PASC) of the dynamic secondary cooling (DSC) of the continuously cast slab (105) in the steel mill are automatically adjusted based on the observed internal state of the slab. It continuously supplies a dynamic 3D mapping (3DM) of the observed internal state of the slab (105). It continuously defines the location of the central mushy region (106) and its segregation defects of the molten slab (105) in a 3D mode and observation method based on 3D physical observation, rather than simply providing it through numerical simulation prediction based on theoretical algorithms of mathematical models. It accurately detects the location of the reduction point of the observed slab (105) based on 3D physical observation. It improves the accuracy and reliability of automatic adjustment of the parameters of dynamic soft pressure (DSR) and dynamic secondary cooling (DSC) of continuously cast steel slabs (105) at temperatures above 1000°C. It enables the reduction of segregation defects and voids in the central mushy zone (106) of the molten steel slab (105) flow structure during continuous casting in steel plants.

[0156] Beneficial effects of the present invention

[0157] The MLEMAT (89) of this invention for DSR and DSC provides valuable industrial advantages in the non-destructive automatic control of hot-cast slabs in the steel industry:

[0158] a. It can be operated at casting temperatures of steel slabs that may exceed 1200°C.

[0159] b. It can perform continuous 3D mapping of steel slab castings at speeds up to 1 meter per second.

[0160] c. It allows for a direct transition between steel flow casting and steel rolling without cooling the steel slab to a maximum of 100°C for NDT using ordinary instruments.

[0161] d. It saves the gas that is usually used to reheat steel slabs at 1200°C after NDT and before rolling.

[0162] e. It provides a continuous 3D mapping observed from the slab casting of steel slabs for automatic dynamic adjustment of continuous casting equipment parameters.

[0163] f. It consistently identifies all types (internal and surface) of discontinuities in the slab casting of steel slabs with high clarity and reliability, along with their coordinates.

[0164] g. It improves the standardization, quality control, and accuracy of quality grading in steel slab production, thereby increasing the added value of continuous casting.

[0165] h. It provides automatic, precise, and real-time adjustment of the DSR and / or DSC dynamic parameters for continuously cast steel slabs.

[0166] i. It provides early detection of discontinuities in steel slabs, and it automatically allows them to be oriented toward previous production processes based on their quality by bringing considerable savings in time, energy, materials and labor.

[0167] j. It can improve the performance and productivity of steel casting machines by 7% or more.

[0168] k. Due to its compact structure, it can be installed without requiring major structural modifications to the steel plant's existing casting equipment.

[0169] Industrial applicability

[0170] This invention has industrial applications in the metallurgical industry, particularly in the steel industry, for DSR and / or DSC quality testing and automatic adjustment of hot-cast slabs in continuous steel casting production lines at temperatures exceeding 1000°C, as well as for quality control of semi-finished products in the metallurgical industry. It also has industrial applications in the railway industry for high-speed control of railway rails and wheelset installation control. Furthermore, this invention has industrial applications in the oil and gas, chemical, and nuclear industries for online testing of pipelines, drilling equipment, and facilities in hazardous and / or high-temperature environments.

[0171] Although only certain features of the invention have been illustrated and described herein, many modifications and variations will become apparent to those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and variations that enter into the true spirit of the invention.

Claims

1. An electromagnetic acoustic transducer (1) for detecting surface and internal discontinuities (2) in a conductive material under inspection (3), characterized in that, include: a. At least one magnet (4) or electromagnet configured to generate a static or quasi-static magnetic field in the material being inspected (3); b. At least one HF coil (6), the latter being of this type: i. If the EMAT (1) is used in the transmission mode, an HF electromagnetic transmitter (9) configured to transmit an HF electromagnetic field is connected to at least one AC current output source (11) to drive the HF AC current in the HF coil (6) at an ultrasonic frequency. • The emitted HF electromagnetic field is induced in the direction of the material being inspected (3). • Material eddies (14) are generated on the surface of the material being inspected (3). • Lorentz force (15) is generated in the material under inspection (3) at an ultrasonic frequency through the interaction of the material eddy current (14) with the static magnetic field and / or magnetostriction. • Its disturbance directly generates primary ultrasonic waves (17) in the material being inspected (3); ii. and / or, if EMAT (1) is used in receiving mode, it is configured as an HF electromagnetic receiver (18), which is then passed through by a secondary ultrasonic electrical signal (88) at the ultrasonic frequency. • Generated by the emitted HF electromagnetic field. • Sensing by the material eddy current (14), which is generated on the surface (8) of the material under inspection (3) by secondary ultrasonic waves (21) under the influence of the ultrasonic source, interacting with the static magnetic field, and representing the surface and interior discontinuities (2) of the material under inspection (3). c. At least one perforated matrix laminated magnetic core (22), configured to concentrate and direct the emitted HF electromagnetic field toward or from the material under inspection (3); of a type including a sandwich matrix (23). i. Composed of a plurality of laminated sheets (24) periodically stacked along a matrix axis (25), these sheets (24) being positioned between two principal matrix faces (26) of the sandwich matrix (23), the matrix faces being parallel to its stacking plane (27), ii. Having a plurality of adjacent lateral edge faces (35) that extend substantially perpendicular to the stacking plane (27) and perpendicular to the matrix axis (25); • A transverse edge face, the first edge face (36) of the matrix (23), facing the inspected surface (8) of the inspected material (3). • Another lateral edge surface (35), the second edge surface (37) of the matrix (23), is substantially opposite to the first edge surface (36) and faces the HF coil (6). iii. Each laminated sheet (24) of the matrix (23) • It has a spatial geometry and lateral dimensions similar to the adjacent slices (24) in the matrix (23); and, • It has two main transverse sheet surfaces (32), which are parallel to the stacking plane (27). iv. wherein the consecutive adjacent peripheral edges (33) of each sheet (24) constitute the grooved edge surface (34) of the matrix (23), the grooved edge surface surrounding the axis (25) of the matrix, and, v. Define the core axis (38) of the matrix (23), which substantially connects the centers of the first edge surface (36) and the second edge surface (37); and is positioned substantially perpendicular to the matrix axis (25); d. The mezzanine matrix (23), the mezzanine matrix comprising a first group (28) of at least one HF active thin layer (29) (or such a group of thin layers), each of which i. isolated from each other, ii. The exterior is bonded with a conductive material; and / or the outer periphery (33) is covered with a conductive layer from the outside, and iii. The interior is bonded with a magnetic material of the ferromagnetic or ferrimagnetic type and has a Curie temperature (TC). The electromagnetic acoustic transducer (1) is characterized by the following features: a. Includes a grooved cylindrical opening (39), wherein the grooved cylindrical opening (39) i. Passing through each sheet (24) of the matrix (23), along the aperture axis (40) of the sandwich matrix (23), the aperture axis being substantially parallel to the matrix axis (25) and perpendicular to the core axis (38), and, ii. Make an opening on each of the two transverse matrix faces (26); b. Includes multiple magnetic through holes (41), the multiple magnetic through holes (41) i. They have similar cross-sectional dimensions, ii. A perforation is made along an axis substantially parallel to the surface under inspection (8) and located substantially at the center of each of the plurality of porous HF active thin layers (29) in the matrix (23). iii. A longitudinal envelope (42) of through holes arranged along the orifice axis (40) of the matrix (23), the transverse periphery of which is continuously closed, and, iv. Alignment, to form the grooved cylindrical aperture (39) through alignment; and, c. Includes multiple closed-loop induced current circuits (43), which, when the EMAT (1) operates, include multiple closed-loop induced current circuits. i. Induced by the emitted HF electromagnetic field, which is emitted by the HF alternating current at the ultrasonic frequency in the HF coil (6) and / or by the material eddy current (14) at the ultrasonic frequency in the material being inspected (3), ii. Within the active thin-layer skin (48) surrounding each HF active thin layer (29) of the perforated matrix laminated magnetic core (22), iii. According to the loop mapping arrangement, the loop mapping defines the topology and relative positions of all induced current loops (43); d. Each magnetic via (41) in each HF active thin layer (29) is located between the first edge surface (36) facing the surface under inspection (8) and the second edge surface (37) facing the HF coil (6); e. Each magnetic through-hole (41) of the grooved cylindrical aperture (39) contains no hard material, and in particular no electrical conductor passes through it; f. The loop mapping is topologically discrete, consisting of multiple discrete parts of the induced current loop (43) of the HF active thin film (29) that are far apart from each other; g. The induced current loop is far away (43). i. Induced within the active laminate skin (48) on the peripheral edge (33) of the HF active thin layer (29), ii. Each is arranged in a plane along a loop parallel to the stacking plane (27) and substantially perpendicular to the surface of the material being inspected (3); iii. They are substantially parallel and separated from each other between their respective HF active thin layers (29), iv. A magnetic via (41) surrounding and rotating around its HF active thin layer (29); and, a. The perforated matrix laminated core (22) located between two adjacent HF active thin layers (29) and each core spacer slice (49) on its surface has no induced current loop (43). This results in a dual physical effect of combination and interaction within the perforated matrix laminated magnetic core (22): a. Each of the multiple parallel and topologically discrete induced current loops (43) in each porous HF active thin film (29), i. Generate high-frequency magnetic fields respectively ii. To increase discrete and selective high-frequency magnetic coupling between the narrow local active portion (44) of the surface under inspection (8) facing the HF active thin layer (29) and the HF coil (6), respectively and locally, and iii. Mutual reduction of high-frequency magnetoresistance involved in the EMAT (1); b. The inner periphery (45) of each magnetic via (41) in each HF active thin layer (29) of the matrix (23). i. Free thermally conductive and convection surfaces (46) are generated at the center of its HF active thin layer (29). ii. To generate an internal thermal cooling effect to dissipate a portion of the local electrical and thermal energy generated by the specific induced current loop (43) of its specific HF active thin layer (29), and, iii. Participate in improving the efficiency of the EMAT(1).

2. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that, in: a. Each of the porous HF active thin films (29) of the matrix (23) is separated from the adjacent HF active thin films by at least one piece of the second group (54) of passive thin films (53) made of electrically insulating material at the level of the adjacent core-pitch slices (49); b. Each passive thin layer (53) is perforated by a spacer through-hole (57), and, c. Each passive thin layer (53) is positioned and configured such that: i. The magnetic vias (41) in the first group (28) of the HF active thin layer (29) of the matrix (23) and the spacer vias (57) in the second group (54) of the passive thin layer (53) of the sandwich matrix (23). ii. Aligned parallel to the matrix axis (25) to form the grooved cylindrical aperture (39) through their alignment and combination; The electromagnetic acoustic transducer (1) is characterized by the following features: a. Each spacer via (57) in each passive thin layer (53) is located between the following i. Facing the first edge surface (36) of the material being inspected (3), and, ii. The second edge surface (37) facing the HF coil (6); and, b. Each spacer through-hole (57) of its grooved cylindrical orifice (39). i. There are no hard materials inside. ii. and especially, no electrical conductors pass through it; Thus, the inner periphery of each spacer via (57) in each passive thin layer (53) of the matrix (23) a. A heat-conducting and convection surface (46) is generated inside the center of the passive thin layer (53). b. It generates an internal thermal cooling effect in the spacer through-hole (57) to dissipate a portion of the electrical and thermal energy generated by the induced current loop (43) of the adjacent HF active thin layer (29), and participates in improving the efficiency of the EMAT (1).

3. The electromagnetic acoustic transducer (1) according to claim 2, characterized in that, For at least one passive thin layer (53). a. Its outer perimeter (33) is not covered by any conductive material on its surface; b. In this way, the slotted edge surface (34) of the perforated matrix laminated magnetic core (22) is not continuously covered with and / or composed of conductive layers, but rather consists of alternating edges and rims, one being made of conductive rings around the HF active thin layer (29) and the other being made of insulating rings around the passive thin layer (53).

4. The electromagnetic acoustic transducer (1) according to claim 2, characterized in that, The type also includes: a. Cooling device (58), the cooling device i. A cooling flow (59) that generates a heat transfer fluid (60) at a cooling temperature. ii. Configured such that the cooling flow (59) is forced through the slotted cylindrical orifice (39) of the matrix (23); The electromagnetic acoustic transducer (1) is characterized by the following features: a. The cooling flow (59) is configured as follows: i. continuously through at least one magnetic through-hole (41) of the first group (28), or through at least one spacer through-hole (57) of the second group (54). ii. All hole wall surfaces (62) along each consecutive magnetic through hole (41) and / or each spacer through hole (57) of the matrix (23). ii. Enhance the internal thermal cooling effect in each HF active thin layer (29) of the matrix (23); each of which undergoes an induced current loop (43) and heat dissipation; and, b. The cooling temperature of the cooling flow (59) is more than 50°C lower than the specific Curie temperature of the magnetic material of each porous HF active thin layer (29).

5. The electromagnetic acoustic transducer (1) according to claim 4, characterized in that... The following combinations: a. At least one sheet (24) of the perforated matrix laminated magnetic core (22) i. Pierced by a buffer hole (63), or provided with a buffer slot (64) that passes through an annular wall (65) formed between its through hole (41, 57) and the portion facing the first edge surface (36) of the material being inspected (3) in a direction parallel to the stacking plane (27). ii. A buffer recess (66) is formed between the through-holes (41, 57) of the sheet (24) and the first edge surface (36) facing the material to be inspected (3); and, b. The cooling device (58) is configured as follows: i. Extract the buffer fluid flow (67) from the cooling flow (59) flowing through the through holes (41, 57). ii. The extracted buffer fluid flow (67) is made to flow under pressure through the buffer recess (66). iii. A lifting air buffer (70) is generated at the level of the buffer recess (66) facing the material under inspection (3) between the perforated matrix laminated magnetic core (22) and the material under inspection (3), and, iv. Therefore, the perforated matrix laminated magnetic core (22) is raised above the material being inspected (3) with a buffer gap (68).

6. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that... The following combinations: a. The two outer sheet surfaces (35) of the two outer sheets located on the matrix surface (26) are formed or covered by a conductive coating layer (69) of conductive material; b. A through-hole with a lateral dimension similar to that of the magnetic through-hole (41) passes through each of the two conductive capping layers (69); c. The plurality of sheets (24) and two conductive capping layers (69) of the matrix (23) are positioned relative to each other such that their plurality of through holes are aligned to continuously form the grooved cylindrical aperture (39).

7. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that... The following combinations: a. The periphery of each magnetic via (41) in each HF active thin layer (29) is rectangular.

8. The electromagnetic acoustic transducer (1) according to claim 7, characterized in that... The following combinations: a. The center of each magnetic via (41) is substantially located at the centroid of its HF active thin film (29); and, b. The periphery of each magnetic via (41) is substantially positioned at a constant circumferential distance from the periphery of its HF active thin film (29); c. In this way, each HF active thin layer (29) is topologically configured as a rectangular active ring (71) that is thermodynamically cooled by heating from the induced current loop (43) generated around it.

9. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that: a. The second edge surface (37) of the perforated matrix laminated magnetic core (22) directly faces the HF coil (6), and, b. No magnet is positioned between the second edge surface (37) of the matrix (23) on one side and the HF coil (6) on the other side.

10. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that: a. Orientation, pitch, size, and shape of each circuit-facing edge (72) of each HF active thin layer (29) located in the second edge surface (37) of the matrix (23) and facing the HF coil (6); b. The geometric parameters are consistent with and related to the orientation, pitch, size and shape of the conductor portion (75) of the HF coil (6) which is successively oriented toward each of these circuit edges (72).

11. The electromagnetic acoustic transducer (1) according to claim 10, characterized in that, in: a. The HF coil (6) has at least one linear conductor portion (73); and, b. The linear conductor portion (73) is positioned near and directly above the circuit-facing edge (72) and is tangent along an axis parallel to the periphery of the portion near the HF active thin layer (29), which is located in the second edge surface (37) of the matrix (23) facing the HF coil (6); The electromagnetic acoustic transducer (1) is characterized in that the linear conductor portion (73) and the perforated matrix laminated magnetic core (22) are configured such that when the EMAT (1) is operated, the induced current loop (43) is activated. a. Induced in the active thin layer skin (48) surrounding the HF active thin layer (29); b. Around its magnetic through-hole (41). c. This will result in localized selective HF magnetic coupling between the following locations: i. HF alternating current driven in the linear conductor portion (73) extending along the periphery of the HF active thin layer (29), and, ii. Material eddies (14) generated in the local active portion (44) of the surface under inspection (8) facing the HF active thin layer.

12. The electromagnetic acoustic transducer (1) according to claim 11, characterized in that, in: a. The HF coil (6) is of the type having multiple linear conductor sections (73) that are parallel to each other and adjacent to each other, such as a zigzag circuit (74). b. Multiple parallel linear conductor sections (73) i. Continuously positioned near and directly above the circuit-facing edge (72) of the HF active thin layer (29), the circuit-facing edge being located in the second edge surface (37) of the matrix (23) facing the HF coil (6), and, ii. The configuration is such that the HF alternating current passing continuously through parallel and adjacent linear conductor sections (73) is directed in alternating opposite directions; c. At least one conductor HF flux loop (76) surrounds each linear conductor section (73) substantially perpendicularly and penetrates substantially perpendicularly into the interior of the HF active thin layer (29) facing it; The electromagnetic acoustic transducer (1) is characterized in that the linear conductor portion (73) of the HF coil (6) and the perforated matrix laminated magnetic core (22) are configured such that when the EMAT (1) is in the emission mode: a. Two adjacent HF active thin layers (29) are covered by two adjacent linear conductor portions (73). b. In its active thin skin (48), there are two adjacent induced current loops (43), each of which consists of alternating HF currents rotating in opposite directions (78) around the aperture axis (40) through which its magnetic through hole (41) rotates, one clockwise and the other counterclockwise.

13. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that... The following combinations: a. The depth of the slotted cylindrical aperture (39) of its perforated matrix laminated magnetic core (22) along its aperture axis (40), b. The first lateral dimension of at least one HF coil (6) of the EMAT (1) is substantially equal to and consistent with that of the EMAT (1).

14. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that... The following combinations: a. Its perforated matrix laminated magnetic core (22) faces the slotted second edge surface (37) of the HF coil (6). b. It has a lateral dimension in a direction perpendicular to the orifice axis (40) of the matrix (23), the lateral dimension being substantially equal to and consistent with the second lateral dimension of at least one HF coil (6) of the EMAT (1).

15. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that... The following combination: the sheet geometry of the perforated sheet (24) of its perforated matrix laminated magnetic core (22) and / or the combined geometry of its perforated matrix laminated magnetic core (22) are selected as follows: a. Decorcorrelate with the wavelength of the primary harmonic of the emitted HF electromagnetic field, and, b. To prevent its perforated matrix laminated magnetic core (22) from mechanically resonating at the ultrasonic frequency of the EMAT (1) operation.

16. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that... The following combination: the sheet geometry (79) of the perforated sheet (24) of its perforated matrix laminated magnetic core (22) at the ultrasonic frequency of EMAT (1) operation: a. Either smaller than the wavelength of the ultrasound generated in these sheets (24), b. Or it is essentially equal to an odd number of quarters of the wavelength of the ultrasound waves generated in these sheets (24).

17. The electromagnetic acoustic transducer (1) according to claim 1, characterized in that, For this type: the perforated matrix laminated magnetic core (22) facing the material under inspection (3) and parallel to the slotted cylindrical aperture (39) has its first grooved edge surface (36) covered or covered by an insulating layer (81) made of an electrically insulating material; the EMAT (1) is further characterized in that one side of the insulating layer (81) is... a. Arranged facing the grooved cylindrical opening (39), and, b. Cover the periphery of the porous HF active thin film (29) on the edge belonging to the first edge surface (36).

18. A laser EMAT probe (82) for inspecting the material (3) by receiving ultrasonic signals from a conductive material (3), characterized in that, Including the following combinations: a. The electromagnetic acoustic transducer (1) according to any one of claims 1 to 17. i. Configured in receiving mode for receiving ultrasonic signals from the material being inspected (3), ii. Its HF coil (6) is configured as an HF electromagnetic receiver (18). • The HF electromagnetic field emitted by the material under inspection (3) is sensed. • Generated by the material eddies (14), which are generated in the material under inspection (3) by secondary ultrasonic waves (21), representing the surface and / or interior discontinuities (2) of the material under inspection (3), and, iii. Its perforated matrix laminated magnetic core (22) • Located between the HF coil (6) of the EMAT (1) and the local surface of the material being inspected (3), and, • Directly facing the HF coil (6); b. A laser source (84), said laser source being configured to: i. Draw a high-energy laser beam (85) at the target point (86) on the surface of the material being inspected (3). ii. Generating ultrasonic waves, said ultrasonic waves being generated as primary ultrasonic waves (17) propagating on the surface and / or inside the material being inspected (3), and, iii. Leading to the generation of secondary ultrasound (21), said secondary ultrasound (21) being caused by the echo of the primary ultrasound (17) interacting with discontinuities (2) on and / or inside the material under inspection (3), propagating on the surface and / or inside the material under inspection (3), iv. This causes material eddies (14) to form on the surface of the material being inspected (3), which are generated by the mechanical vibration of the secondary ultrasonic waves (21) under the influence of the static magnetic field emitted by the magnet (4) of the EMAT (1), and, v. The induction of an emitted HF electromagnetic field HF that causes the material eddy current (14) present on the surface of the material under inspection (3) to be emitted, representing the geometry and position of the surface and interior discontinuities (2) of the material under inspection (3). The laser EMAT probe (82) is characterized in that: a. Multiple parallel and far-away induced current loops (43). i. Under the influence of the laser source (84), the emitted HF electromagnetic field emitted by the material eddy current (14) at the ultrasonic frequency of the material under inspection (3) is induced. ii. Within the active thin layer skin (48) on the peripheral edge (33) of each HF active thin layer (29) of the perforated matrix laminated magnetic core (22); b. These induced current loops (43) of each HF active thin film (29) i. spaced apart from each other, ii. Each is arranged in a plane along a loop parallel to the stacking plane (27) and substantially perpendicular to the surface of the material being inspected (3); iii. Rotate around and about the magnetic via (41) of its HF active thin layer (29); iv. Located between the first edge surface (36) facing the material being inspected (3) and the second edge surface (37) facing the HF coil (6), and v. Positioned essentially perpendicular to the two edge faces (36, 37); This results in a dual physical effect of combination and interaction within the perforated matrix laminated magnetic core (22): a. Each of the multiple parallel and topologically discrete induced current loops (43) in each HF active thin layer (29), i. Generate high-frequency magnetic fields respectively ii. Increase the high-frequency magnetic coupling between the narrow local active portion (44) of the surface under inspection (8) facing its HF active thin layer (29) and the HF coil (6) locally and discretely, and, iii. To homogenize the high-frequency coupling and reduce the overall high-frequency magnetoresistance of the EMAT (1) through interaction, and improve the resolution (1) of the EMAT. b. The inner periphery (45) of each magnetic via (41) in each HF active thin layer (29) of the matrix (23). i. An internal free thermal conduction and convection surface (46) is generated at the center of its HF active thin layer (29), and, ii. To generate an internal thermal cooling effect to dissipate a portion of the local electrical and thermal energy generated by the induced current loop (43) of its specific HF active thin layer (29), and, iii. Participate in improving the efficiency of the EMAT(1).

19. A multi-laser EMAT 3D scanner (89) for detecting surface and / or internal discontinuities (2) within a moving cylindrical conductive structure (90), characterized in that, Including the following combinations: a. Conductive structure to be 3D scanned (90). i. Made of conductive material to be inspected (3), ii. It has a cylindrical structure generated along the structural axis (91), iii. It has a substantially constant structural cross section (92); b. Chassis frame (93). i. is configured to surround the conductive structure (90) at a frame distance. ii. Its frame plane (95) is substantially perpendicular to the structural axis (91) of the conductive structure (90). c. A probe group (96) made of at least two laser EMAT probes (82) according to claim 18, wherein each laser EMAT probe (82) i. Fixed to the chassis frame (93), and, ii. Positioned and configured in such a location that each first edge face (36) of its perforated matrix laminated core (22) faces the conductive structure (90); d. Displacement device (97), the displacement device being configured as follows: i. To move the cylindrical conductive structure (90) linearly relative to the chassis frame (93), ii. Along the displacement direction, the displacement direction substantially coincides with the structural axis (91); The multi-laser EMAT 3D scanner (89) is characterized by: a. Orifice circuit (99). i. Composed of virtual lines at the center of each continuous slotted cylindrical aperture (39) of the perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the laser EMAT probe (82) connecting the MLEMAT (89), ii. Surrounding the conductive structure (90).

20. The multi-laser EMAT 3D scanner (89) according to claim 19, characterized in that, The probe group (96) made from the laser EMAT probe (82) is attached to the chassis frame (93), positioned and configured in such a location that: a. A plurality of adjacent first edge surfaces (36) facing the material under inspection (3) adjacent to the perforated matrix stacked magnetic core (22) of each adjacent laser EMAT probe (82) are juxtaposed and substantially in contact with each other; and, b. A substantially continuous grooved inspection ring (100) is formed, which surrounds and covers the periphery of the conductive structure (90) in a structural section (92) near the frame plane (95) of the conductive structure (90).

21. The multi-laser EMAT 3D scanner (89) according to claim 19, characterized in that, For the following types: a. The laser source (84) of each MLEMAT (82) consists of an optical fiber (101) fixed to the frame plane (95) and has a target end (102) facing the conductive structure (90); and, b. Each optical fiber (101) is connected to the laser generator (103); The multi-laser EMAT 3D scanner (89) is characterized by a laser target circuit (104). a. Consists of virtual lines connecting the target ends (102) of each adjacent laser EMAT probe (82) of the MLEMAT (89), b. Surrounding the conductive structure (90) and substantially parallel to the orifice loop (99).

22. The multi-laser EMAT 3D scanner (89) according to claim 19, used for detecting surface and / or internal discontinuities (2) in a metallurgical slab (105), characterized in that, in: a. The conductive structure (90) is a cylindrical metallurgical slab (105) that is movable relative to the MLEMAT (89); The multi-laser EMAT 3D scanner (89) is characterized by: a. The aperture loop (99), formed by the virtual line of the center of each continuous slotted cylindrical aperture (39) of the perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the laser EMAT probe (82) connecting the MLEMAT (89), surrounds the movable cylindrical metallurgical slab (105).

23. The multi-laser EMAT 3D scanner (89) according to claim 22, used for detecting surface and / or internal discontinuities (2) in a steel slab (105), characterized in that, For the following types: a. The conductive structure (90) is a moving cylindrical billet of a steel slab (105) continuously cast in a steel mill at a casting temperature above 1000°C, and, b. The porous HF active thin layer (29) of each perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the MLEMAT (89) is made of a magnetic material, such as a ferromagnetic or ferrimagnetic type, with a Curie temperature lower than the casting temperature. The multi-laser EMAT 3D scanner (89) is characterized in that each slotted cylindrical aperture (39) of each perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the MLEMAT (89) is connected to a cooling device (58) that generates a cooling flow (59) of a heat transfer fluid (60). a. Under pressure, the slotted cylindrical aperture (39) of each perforated matrix laminated core (22) of each adjacent EMAT (1) of the MLEMAT (89) is pushed into each through hole (41, 57); b. At a cooling temperature that is more than 50°C lower than the Curie temperature of the magnetic material of the porous HF active thin film (29).

24. The multi-laser EMAT 3D scanner (89) according to claim 23, used for automatically adjusting the dynamic parameters of the slab (105) continuously cast in a steel mill at a casting temperature above 1000°C under dynamic soft pressure, characterized in that, For the following types: a. The steel slab (105) is continuously pushed by a dynamic soft pressing device to suppress the formation of macrosegregation zone and void zone in the steel slab (105), thereby dynamically compensating for the solidification shrinkage of the steel and interrupting the absorption flow rate of residual molten metal in the central pasty zone (106). b. The MLMAT (89) is coupled to the dynamic soft-pressurization device, which includes: i) A dynamic 3D mapping system that generates a dynamic 3D mapping of the steel slab (105) casting; ii) A computer-based DSR optimization system that generates dynamic DSR optimization parameters based on the dynamic 3D mapping and continuous casting parameters; and c. A digital DSR activator that dynamically adjusts the DSR action parameters of the dynamic soft-press device based on the PCSD generated by the DSRM; The multi-laser EMAT 3D scanner (89) features the following combination of characteristics: a. The HF coils (6a, 6b, 6) of each laser EMAT (82a, 82b, 82) of the MLEMAT (89) are respectively connected to the dynamic 3D mapping system and transmit to it the secondary ultrasonic electrical signals (88a, 88b, 88) induced in each HF coil (6a, 6b, 6) by the material eddies (14) on the front area (110) of the inspected material (3) of the steel slab (105) partially facing each EMAT (1a, 1b, 1). b. The DSR optimization system is equipped with analog and digital processing devices, which are configured for... i. Receive multiple secondary ultrasonic electrical signals (88a, 88b, 88) comprising secondary ultrasonic currents (19a, 19b, 19) in each HF coil (6) passing through each laser EMAT (82a, 82b, 82) of the MLEMAT (89), and, ii. Identify the variations and disturbances in each secondary ultrasonic electrical signal (88a, 88b, 88) of each laser EMAT (82a, 82b, 82) caused by discontinuities (2) in the local active portions (44a, 44b, 44) of the inspected material (3) facing each laser EMAT (82a, 82b, 82), and digitally derive and generate the defect frontal topology (DTa, DTb, DT) of the local active portions (44a, 44b, 44), and, iii. Based on the combination and digital analysis of multiple secondary ultrasonic electrical signals (88a, 88b, 88), in the front area (110) facing the inspection ring (100) of the structural section (92) of the frame plane (95), the defect front topology (DTa, DTb, DT) is digitally combined, and a three-dimensional dynamic 3D mapping of the interior of the steel slab (105) as physically observed by the MLEMAT (89) is digitally generated; and, c. The cooling device (58) generates a cooling flow (59) of the heat transfer fluid (60), the heat transfer fluid i. Under pressure, push into each through hole (41, 57) of each perforated matrix laminated core (22) of each adjacent EMAT (1) of the MLEMAT (89) into each slotted cylindrical aperture (39); ii. At a cooling temperature that is significantly lower than the Curie temperature of the magnetic material in the porous HF active thin film (29); d. Thus, the DSR action parameters of the dynamic soft pressing device can be dynamically and automatically adjusted in an optimized manner based on the dynamic 3D mapping of the slab (105) of the steel billet physically observed by the MLEMAT (89), which is carried out at casting temperatures above 1000°C.

25. The multi-laser EMAT 3D scanner (89) according to claim 24, for automatically adjusting dynamic parameters under dynamic soft pressure, which further allows for dynamic secondary cooling of the slab (105) in the steel mill at casting temperatures above 1000°C, characterized in that... The MLEMAT (89) is coupled to a dynamic secondary cooling device, which further includes: a. A computer-based DSC optimization system generates dynamic DSC optimization parameters based on the following: i. In the structural section (92) of the frame plane (95), through combination and digital analysis of the combined signals of multiple secondary ultrasonic electrical signals (88a, 88b, 88) in each laser EMAT (82a, 82b, 82) of the MLEMAT (89), a dynamic 3D mapping based on the physical observation of the slab (105) is obtained. ii. and based on casting parameters; b. A digital DSC activator, based on the PCSC generated by the DSC optimization system, dynamically adjusts the DSC action parameters of the dynamic secondary cooling molten steel flow rate, the PCSC being based on a dynamic 3D mapping physically observed by the MLEMAT (89).

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