EMAT system for detecting surface and internal discontinuities in conductive structures at high temperatures

Abstract

This invention provides an electromagnetic acoustic transducer (EMAT) system for detecting discontinuities on the surface and within thick conductive structures at high temperatures. [Solution] The system comprises a magnet that generates a static magnetic field (SMF) and a high-frequency electric coil (6) for inducing or being induced to induce eddy currents in a material (14). It consists of a perforated matrix array laminated magnetic core (22) made up of a number of open high-frequency active laminates (29) and open insulating passive laminates incorporating ferromagnetic material, positioned between the high-frequency electric coil (6) and the object under inspection (3). Trough holes are made in each laminate, forming grooved cylindrical openings (39). Induction current loops (43) surround each magnetic trough hole (41) in the high-frequency active laminates (29). The cooling means is an EMAT system that forces a heat transfer fluid to pass through the grooved cylindrical openings (39).

Description

Technical Field

[0001] The present invention relates to ultrasonic nondestructive testing (UNDT). Specifically, it relates to an electromagnetic ultrasonic transducer (EMAT) for ultrasonic nondestructive testing (UNDT), its embodiments, and application methods to industry.

[0002] The technical field of the present invention particularly relates to EMAT and comprises the following. a. A vibrationless type of transducer (probe) that induces or receives ultrasonic mechanical vibrations electromagnetically without mechanical vibrations. b. It is used to analyze and study materials using a transmitter, or to induce ultrasonic waves in a conductive test specimen by electromagnetic means, or to irradiate or receive ultrasonic waves to see the inside of the object. c. Also, it relates to International Patent Classification Int. Cl. G01N 29 / 24 and U.S. Patent Nos. Cl. 73 / 643.

Background Art

[0003] The field of the present invention is limited to EMAT that comprises the following. a. It has electromagnetic coupling means installed between the active electromagnetic components of the probe and the inspection object. This increases the coupling of the high-frequency magnetic field between the active electromagnetic components of the probe and the surface of the conductive test specimen through which eddy currents flow. b. The electromagnetic coupling means is of a specific type and is composed of a laminated core formed from a matrix of laminated thin plates incorporating either ferromagnetic or ferrimagnetic material inside. c. The electromagnetic coupling means is of a specific type and has active cooling means. This dissipates the thermal energy generated by the current loop induced on the outer periphery of the laminate of the electromagnetic coupling means.

[0004] The present invention is preferably implemented using a laser EMAT device or an EMAT-EMAT device, and ideally, it should include both an ultrasonic generator consisting of a high-power pulsed laser and an ultrasonic generator, and an ultrasonic EMAT receiver consisting of an ultrasonic generator.

[0005] A preferred use of the present invention is to perform 3D physical scanning and ultrasonic non-destructive UNDT testing on the surface and interior of large structures, thick structures, and parts in production lines. For example, it can be used to inspect for discontinuities on the surface and interior of structures manufactured from conductive materials such as steel slabs during casting in high-temperature environments of 1000°C or higher in production lines.

[0006] The present invention can be used to dynamically optimize the settings of dynamic depressurization (DNS) and dynamic secondary cooling (DSC) parameters at temperatures exceeding 1000°C in the casting of stranded steel wire in a steel mill.

[0007] [Background of the Invention] EMAT is used for non-destructive testing of structures made of conductive materials. Non-destructive testing (NDT) is commonly used to monitor and inspect structures and components of various shapes and sizes without damaging them. However, the types and applications of NDT that can be effectively used are limited by operating conditions, temperature, type of mounting, size of the component being inspected, and structural complexity. The data obtained by conventional NDT systems is not suitable for detecting defects and three-dimensional structures in great depth in large components manufactured at temperatures exceeding 1000°C or under extremely high operating conditions, such as the continuous casting of steel slabs in a steel mill.

[0008] Ultrasonic non-destructive testing (UNDT) is a type of non-destructive testing that uses ultrasound to inspect objects or equipment. In conventional UNDT testing, an ultrasonic probe is applied to the object being inspected. Conventional UNDT uses short-wavelength, high-frequency mechanical waves emitted from an ultrasonic transducer (probe). These waves are irradiated onto the object being inspected, and the waveform is read using the same probe or another machine to detect defects in the structure. The main probes used in UNDT are piezoelectric transducers, laser transducers, and electromagnetic ultrasonic transducers (EMAT). Conventional UNDT testing using piezoelectric elements has many advantages, including safety, flexibility, and cost. However, testing with piezoelectric elements requires coupling and has certain limitations, such as the need for a good surface condition. Therefore, contact between the object being inspected and the probe is necessary. However, in high-temperature testing, the higher the temperature, the more difficult coupling becomes for UNDT piezoelectric testing. Generally, it cannot be performed above 100°C.

[0009] The main prior art of this invention relates to electromagnetic ultrasonic transducers (EMATs). UNDT's EMAT method is based on magnetic coupling. Sound waves are generated within the object being tested and not by contact with the object's surface. EMATs offer significant advantages over conventional piezoelectric transducers. EMATs can generate and receive various waveforms without physical or liquid contact with the object, even in conductive or ferromagnetic materials. This non-contact and non-coupling functionality enhances test reliability because the physical characteristics of the transmission path remain unchanged. Furthermore, the durability specifications required for the position of the part being tested with the EMAT probe are flexible. For these reasons, conventional EMATs are suitable for average test temperatures (up to 600°C) and when the surface condition of the object being tested is poor during operation.

[0010] EMAT consists of two main components: a magnet and a high-frequency electric coil. The magnet can be a permanent magnet or an electromagnet, as long as it generates a static or quasi-static magnetic field. A high-frequency current flows through the electric coil (or electrical circuit), which is generated by the high-frequency magnetic field. The EMAT phenomenon is reversible. Therefore, the same EMAT probe can be used in combination with two functions: irradiating the target with ultrasound and receiving the ultrasound signal emitted by the target. Prior art has shown that EMAT is used in a wide range of applications, including thickness measurement of metal products, defect detection in pipelines, defect detection in rails, and defect detection in steel materials.

[0011] Attaching a wear plate to an EMAT (Electromagnetic Mater) to protect against wear of magnets and electrical coil circuits caused by the movement of the EMAT relative to the object has already been adopted in prior art. The wear plate is generally placed between the object and the magnets and electrical coil circuits of the EMAT. However, a problem with typical wear plates is that they create high reluctance (magnetic resistance) between the magnetic parts of the EMAT and the object.

[0012] Generally, a challenge for EMAT (Electromagnetic Activity Therapy) is that EMAT probes suffer from low magnetic conductivity in both the static magnetic field generated by the magnet and the high-frequency magnetic field they radiate or receive. In prior art, some methods involve introducing a magnetic core made of a ferromagnetic or ferrimagnetic material with a high dielectric constant between the magnetic irradiator and the magnetic receiver, thereby increasing the strength of the induced magnetic field by several hundred or even several thousand times. The magnetic core itself generates a magnetic field, which is then added to the irradiated magnetic field. The amplification effect of the magnetic field depends on the dielectric constant of the magnetic core. It is also known that the presence of a core negatively affects the high-frequency magnetic field due to the eddy currents generated in the core. As a result, a large energy loss occurs that depends on the frequency of the high-frequency magnetic field. If these magnetic cores are connected one by one, the high-frequency magnetic field causes the current flowing through the core to form a closed loop, generating large eddy currents in the high-frequency magnetic field. These eddy currents, due to the resistance of the material, result in a large loss due to the Joule effect. Therefore, conventional technology uses a matrix-type magnet core made by laminating thin sheets (plates) of ferromagnetic or ferrimagnetic magnetic material, separated by thin insulating sheets. The thin insulating passive sheets act as a barrier to prevent eddy currents. As a result, eddy currents circulate within the thickness of these sheets, forming narrow loops perpendicular to the emitted magnetic field.

[0013] To overcome this magnetoresistance, U.S. Patent No. 7,546,770 B2, which uses EMAT, employs a stack of thin magnetic cores. This is a sandwich configuration, consisting of numerous thin ferromagnetic laminated sheets arranged in layers. A thin insulating sheet is sandwiched between the thin ferromagnetic sheets, forming a sandwich-like matrix of stacked magnetic cores. EMAT is specifically described in a configuration in which a high-frequency electric coil induces eddy currents on the surface of the object, but does not receive them. Therefore, it should be noted that this prior art is a probe as a transmitter for EMAT, not a receiver. The stacked magnetic core is placed between the magnet and the object. It is not placed directly opposite the high-frequency electric coil, and the entire outer surface of the stacked magnetic core is covered with a continuous conductive layer made of conductive material. Electric coils in coil shape are known to generate a bundle of magnetic field lines consisting of numerous magnetic field loops parallel to the axis of a circular vortex passing through the inside of the coil. The absolute strength of each magnetic field loop varies and depends on its point of passage and distance from the center of the coil. Furthermore, it is known that high-frequency magnetic field loops generate eddy currents in materials placed near their center, and the direction of these currents is perpendicular to the high-frequency magnetic field loop. As a result, although not described in this prior art, if this EMAT is operated in a high-frequency emitting mode, it can be understood that the electric coil then generates numerous high-frequency magnetic field loops with variable absolute strength, passing through the center of the spiral and oriented toward the magnetic core. The axis of the electric coil described is substantially parallel to the stacked surface of the thin layers. Therefore, the high-frequency alternating magnetic field loops are substantially parallel to the stacked surface of the magnet core made up of stacked thin layers. Consequently, numerous induced current loops are generated on the surface of the conductive layer that completely encloses the magnet core made up of stacked thin layers. These loops are topologically distributed non-uniformly, non-organized, continuous, and non-discretely on the surface of the conductive layer. Depending on their position on the conductive layer, they have variable and non-uniform absolute strengths and are oriented substantially perpendicular to the surface of the stacked thin sheets. Therefore, the current loops generated on the surface of the conductive layer are substantially perpendicular to the stacked thin layers with strong magnetism.As a result, the induced current loop does not surround it. Most current loops that form on the surface of the conductive layer are parallel to the surface in question.

[0014] This prior art laminated magnetic core protects the magnet and the high-frequency electrical coil. It can also improve the transmission of static magnetic flux from the magnet to the object. This laminated magnetic core provides a high-frequency, overall, but blurred, heterogeneous coupling between the high-frequency electrical coil and the eddy currents of the probe and the object surface facing the high-frequency electrical coil. This high-frequency magnetic field coupling is performed overall and homogeneously by the outer continuous conductive layer and not individually by the inner thin ferromagnetic laminated sheet.

[0015] According to this prior art, the high-frequency electric coil is positioned on top of the magnet at a considerable distance from the laminated magnetic core and the object. Such a magnet arrangement results in further losses when transmitting electromagnetic energy between the high-frequency electric coil and the object. While this arrangement of the EMAT's laminated magnetic core minimizes losses from the static magnetic field generated by the magnet, it degrades the quality of the high-frequency magnetic field coupling between the eddy currents on the object's surface facing the probe and the EMAT's high-frequency electric coil. This high-frequency magnetic coupling is uneven in strength, being locally activated at each edge of the ferromagnetic laminate on one hand, and activated at the high-frequency electric coil on the other.

[0016] According to this prior art, the laminated magnetic core is thermodynamically passive. This is because it does not include any active cooling means for the thermal energy generated by the current loop induced on the outer surface of the ferromagnetic laminated core of the magnet. Therefore, this EMAT is not thermally protected and cannot operate continuously and reliably at temperatures above 600°C.

[0017] In conventional EMATs, this protection is ensured by fixing an electromagnetically passive protective plate made of insulating material to the working side of the probe, keeping the part away from the target. The thickness of this protective plate is determined in coordination with mechanical resistance, required operating temperature, and the conductivity efficiency of the EMAT.

[0018] Prior art also provides EMATs with hollow, unlaminated passive magnet cores, which may or may not have cooling mechanisms for operation at high temperatures. However, these prior art EMATs do not combine layers of magma-like heat with cooling mechanisms built into the core, and therefore do not optimize or homogenize the high-frequency magnetic coupling, nor do they minimize the leakage of high-frequency magnetic flux between the high-frequency electric coil and the target.

[0019] Receiving ultrasonic signals in EMAT's receiving mode operates in the same way as in EMAT's irradiation mode. The direction of EMAT during reception can be easily changed electronically. This directivity makes it possible to achieve a high signal-to-noise ratio (S / N ratio) in EMAT operating in receiving mode.

[0020] The operation of conventional EMAT technology was extremely limited in complex environments and under high-temperature conditions exceeding 1000°C. This is because it scans a wide area of ​​a plate-shaped movable structure continuously and in-line from a single point, similar to how it is used for inspecting pipes and rails at low temperatures.

[0021] The second prior art aspect concerns the laser EMAT UNDT. This improves the overall sensitivity of UNDT systems using EMAT and their adaptability to operate at average temperatures up to 600°C. The UNDT requires an ultrasonic generator and an ultrasonic receiver.

[0022] A typical laser EMAT system combines an ultrasonic generator using a high-power pulsed laser with an EMAT receiving mode as an ultrasonic receiver. Prior art refers to such UNDT (Unified Dynamics Testing) composite devices for detecting discontinuities on the surface and within structures. This is based on the following combined operation: i) An ultrasonic transmitter made with a pulsed laser irradiates the structure with the laser, and when the pulsed laser is absorbed by the structure, it generates ultrasonic surface waves and shear waves in the structure. ii) An ultrasonic receiver consisting of an EMAT in receiving mode detects ultrasonic surface waves and ultrasonic shear waves at the detection point. When a high-energy-density laser is shone on the surface of a component to be inspected, such as a steel plate, it is rapidly heated by local pulses, causing a plasma explosion on the surface. This explosion generates ultrasound throughout the object. The laser also generates two different types of waves. First, there are waves that propagate along the surface of the part or its vicinity. These propagate laterally to the surface of the part and are the strongest detection signal. The other is waves that propagate deeply over a wide area of ​​the object at a wide angle. If the material is conductive, the ultrasonic EMAT receiver of the laser EMAT system detects the generated ultrasound using a combination of a high-frequency electric coil and a magnet. The vibrations of the surface and interior of the object caused by the ultrasonic signal generated by the laser are affected by the discontinuous echo and its location, causing an HF current in the detection circuit of the ultrasonic EMAT receiver via the generated eddy currents. By processing the signal of the current in the high-frequency electric coil and identifying changes and interferences in the received ultrasonic signal caused by discontinuities in the inspected material, the discontinuities on the surface and interior of the object located between the laser and the EMAT ultrasonic receiver can be detected and their location determined.

[0023] The device combined with this UNDT shows better efficiency in detecting discontinuities than the EMAT device alone used for both transmission and reception based on EMAT. This is because the pulsed laser has higher efficiency, directivity, and power as an ultrasonic radiator compared to the transmitters of conventional EMATs. The main drawback of a general laser EMAT system, as shown above, is that the drawbacks of a general EMAT receiver when used as a receiver remain as they are. Lasers can operate at temperatures exceeding 600 °C. However, conventional EMATs of the prior art cannot do so.

[0024] The third aspect of the prior art of the present invention relates to the optimal automatic adjustment of the dynamic soft reduction (DSR) parameter, which is utilized, for example, in the continuous casting of steel parts at a temperature of about 1200 °C in the production of a steelworks, such as the continuous casting of steel slabs or billets. Slabs are usually processed into finished steel products such as plates, sheets, strip rolls, pipes, and tubes.

[0025] When the continuously cast steel solidifies, there is a region that is neither completely solid nor liquid between the solid and liquid phases of the metal. The percentage of solid contained in this "mushy" (semi-solidified region) region changes from liquid to solid depending on the thermal properties and the structure of the steel, and the volume of the steel decreases due to the change in density accompanying the temperature drop during continuous casting. This results in inter-dendritic structural gaps. In the crater of the final solidification, a segregation band occurs in the center. The internal segregation defects generated during the continuous casting of slabs and the porosity in the center of the slabs have a very adverse effect on the properties of the finished steel products subsequently manufactured from the slabs. This central segregation degrades the quality of the steel products, especially thick steel plates. Variations in mechanical properties occur, and defects may occur in the final products.

[0026] Many attempts have been made to reduce or neutralize the drawbacks of continuous casting, such as segregation in the center. A common method is to reduce the casting rate, which of course affects the overall flow rate. Other embodiments of prior art include applying soft reduction ("soft reduction" or light reduction, hereafter SR) in the final stage of solidification, or using dynamic secondary cooling (DSC). The basic idea is to suppress the formation of segregation and porosity in the center by compensating for the shrinkage due to solidification and blocking the pulling flow of the remaining steel. SR must be performed perpendicular to the semi-solidified state of the final solidification process using specialized equipment such as pinch rollers. SR can only be performed in continuous casting where the center has not yet hardened. The optimal point is where the solidification zone ends. The reduction interval must be between the solid-liquid two-phase state of the slab and the solidification of the continuous casting. This is to improve the density and homogeneity of the center of the strand. However, the precise location of this optimal solidification completion point is not well understood and is prone to fluctuations because it occurs during the continuous casting of steel slabs; it remains unclear even in prior art.

[0027] The "Soft Reduction at the End of Solidification" (LSR) method involves estimating multiple intervals close to the reduction area during continuous casting or slab casting, and installing multiple reduction rollers. LSR is a method for gradually reducing the center of continuous casting and preventing void formation in the molten mild steel flow. Static soft reduction (SSR), which involves adjusting the gap of fixed nip rolls, has been adopted in prior art to improve the internal quality of steel slabs in continuous casting. However, since the position of the pinch rollers is fixed, it can only be used with precise casting parameters. In other words, the casting itself needs to be as stable as possible. The fixed reduction area of ​​SSR imposes constraints on the entire casting process. Due to operational considerations, it is difficult to maintain a steady state of casting parameters for a long period of time. Furthermore, casting parameters such as casting speed and superheating degree can change during casting. As a result, the solidification range shifts during the process. Therefore, the operational efficiency of the SSR method is low.

[0028] In the prior art, in order to improve the operational flexibility while maintaining good internal quality, a dynamic soft reduction (DSR) system that takes into account transient casting conditions, an evolutionary solidification process, and the behavior of inspected materials has been proposed. DSR may or may not use dynamic secondary cooling (DSC) in combination, and it has been found that it can minimize segregation and porosity of the casting strand (steel floor slab) more efficiently than SSR. The parameters of DSR need to be carefully defined in order to effectively eliminate central segregation and improve the internal quality of the casting slab. In soft reduction, it is important to accurately set the interval between pinch rollers at the stage of solidification and apply it at the correct position. If DSR is too early, it will only deform the outer surface of the slab and will not effectively penetrate to the center. If it is too late, the slab will completely solidify and the resistance to deformation will become too large, imposing an excessive load on the rollers of the device. The main parameters that affect reduction and determine the efficiency of the dynamic soft reduction position DSR are the slab type, casting speed, steel composition (thermal properties), superheat rate, and cooling rate. In order to achieve an efficient dynamic soft reduction DSR, it is necessary to calculate the internal solidification process and open the interval between pinch rollers from the current and past data of continuous casting, and preferably control its position dynamically.

[0029] Furthermore, it is necessary to supply the following points at the exact time. i) Dynamic 3D mapping (3DM) of the continuously cast slab. ii) 3D position of the central segregation region of the steel slab and the position of segregation defects. At this time, the information obtained from the casting dynamic 3D mapping system (3DMS) is a basic requirement for effectively implementing dynamic soft reduction DSR and dynamic secondary cooling DSC.

[0030] The prior art DSR / DSC system is generally composed of the following means. a. Dynamic 3D (three-dimensional) mapping system (3DMS) for steel casting. b. Computerized DSR Optimization System (DSRM). This system generates dynamic DSR optimization parameters (PCSD) based on dynamic 3D mapping (3DM) and casting parameters obtained from the 3DMS system. c. Digital DSR Activator (ASR). This dynamically adjusts the DSR Action Parameter (PASD) using a function of the PCSD generated by DSRM. d. Optional, a DSC optimization system (DSCM). This generates dynamic DSC optimization parameters (PCSC) based on the dynamic 3D mapping (3DM) and casting parameters provided by the 3DMS system. e. Optional, a Digital DSC Activator (ASC). This dynamically adjusts the DSC operating parameter (PASC) of the DSC's water flow velocity using a function of the PCSC generated by the DSCM.

[0031] The algorithm for the computer-based optimization model DSRM needs to comprehensively consider three parameters crucial for DSR deceleration: the position and shape of the deceleration section, its dynamics and deceleration rate, and the spacing between the rollers in the deceleration section.

[0032] Conventional dynamic 3D mapping systems (3DMS) for steel casting operate only in simulation, as follows: a. Numerical simulation prediction based on theoretical algorithms. It also uses mathematical models of heat transfer and solidification within the continuous casting of slabs as a basis. b. Detection of the precise location of the semi-solidified (massy) portion in the central part of the continuous casting of the slab and the location of discontinuities, rather than the physical detection of actual dynamic 3D mapping (3DM) of the interior of the cast steel slab.

[0033] Recent variations of the prior art dynamic 3D mapping system (3DMS) for cast steel are based on the algorithmic interpretation of 2D thermal tracking data, and this system was developed to utilize the external heat of continuous casting of slabs.

[0034] Prior art dynamic 3D mapping systems (3DMS) for steel casting do not provide objective, accurate, and reliable definitions regarding the location of the central semi-solid region of the slab, segregation defects, or 3D mapping of discontinuities in the reduction and solidification zones during continuous casting of slabs. While parameters for soft reduction DSR, such as reduction position and shape, dynamic reduction ratio, and spacing of the reduction rollers, are adjusted in prior art, these are based on theoretical models that are not objective, and may even be blindly reliant, on the central semi-solid region and the internal discontinuities of continuous casting of slabs. As a result, DSR and DSC parameters are often inappropriate or ineffective in continuous casting. Furthermore, segregation and excessive porosity during solidification in the central part of continuously cast slabs cannot be adjusted by dynamic soft reduction or secondary dynamic cooling.

[0035] [Problems that this invention aims to solve] From the analysis of the prior art described above, it became clear that a different approach is needed to address the following technical challenges of non-destructive ultrasonic testing (UNDT). a. Solve the following three technical challenges with a single EMAT probe. i. To increase the energy transfer of the high-frequency magnetic field between the electric coil and the eddy currents generated on the surface of the object, maximize the high-frequency magnetic coupling, and minimize the leakage of the magnetic flux of the high-frequency magnetic field. ii. Provides topological homogeneity of the high-frequency electromagnetic coupling between the electric coil and the eddy current on the surface of the object being inspected facing the probe. iii. The object being tested can operate at temperatures exceeding 1000°C. b. The following two technical challenges will be addressed by a single UNDT device. i. Optimize the resolution for detecting discontinuities on the surface and in depths of thick metal. ii. The object being tested can operate at temperatures exceeding 1000°C. c. The following two technical challenges will be comprehensively addressed using a 3D scanner for conductive structures. i. Provides line-by-line 3D scanning of large, thick conductive moving structures such as metallurgical slabs, and generates high-resolution 3D mapping by providing the location of surface and deep discontinuities. ii. Even in challenging environments, the equipment can operate at temperatures exceeding 1000°C. d. This system enables the optimal automatic adjustment of the DSR operation parameters (PASD) for dynamic soft reduction (DSR) and the DSC operation parameters (PASC) for dynamic secondary cooling (DSC) in the continuous casting of steel slabs in steel mills, based on objective observations of the inside of the cast slabs. Furthermore, it solves the following four technical challenges in a single device. i. Continuously provide dynamic 3D mapping (3DM) of the interior of cast slabs. ii. The location of the central semi-solidified zone of the slab or segregation defect is defined based on actual 3D data, not on predictions from numerical simulations using theoretical algorithms based on mathematical models. iii. Based on 3D physical observation, the position of the reduction point of the cast slab is precisely detected. iv. Improve the accuracy and reliability of automatic adjustment of dynamic soft reduction (DNS) and dynamic secondary cooling (DSC) parameters at temperatures exceeding 1000°C for continuously cast slab wires. This will reduce segregation defects and porosity in the central semi-solid region during the fusion of steel slab wire structures in the continuous casting process at steel mills.

[0036] [How to solve the problem] In short, the present invention provides an electromagnetic ultrasonic probe (EMAT) for detecting discontinuities on the surface and inside of conductive inspection materials. This provides a technical solution to the technical problem described in (a) above. This is a counterintuitive approach to those skilled in the art and differs from the configuration of conventional EMATs using a multilayer magnetic core. The technical solution of the present invention lies in the following: a. The present invention does not seek to reduce the area of ​​eddy current loops within the high-frequency active laminate (29) of the perforated matrix multilayer magnetic core (22). On the contrary, the present invention increases the area and effect of the induced current loops (43) induced in the high-frequency active laminate (29), thereby generating a complex and interactive dual physical effect within the perforated matrix multilayer magnetic core (22). By arranging and oriented these loops in a topologically appropriate manner, the coupling efficiency and homogeneity can be improved, thereby enhancing the performance of EMAT (1). b. The transmitted EMAT is not configured as follows: i) The HF magnetic field loop induced by the high-frequency electric coils of the magnetic core is substantially parallel to the lamination plane of the thin sheets of the laminated magnetic core. ii) Numerous induced current loops are distributed only on the surface of the continuous conductive layer surrounding the core of the multilayer magnetic material. iii) The induced current loops are topologically distributed non-uniformly, disorganizedly, continuously and non-discretely across the entire surface of the conductive layer. iv) The induced current loop is substantially perpendicular to the laminated surface of the thin plate. Conversely, in this invention, the transmitting EMAT is i) The alternating magnetic field loop induced by the high-frequency electric coil within the magnetic core is configured to be substantially perpendicular to the laminated surface of the thin plates of the laminated magnetic core, and the induced current loop occurs only in the peripheral part of the high-frequency thin plate, and is parallel to the plane of the thin plate surrounding the periphery, and therefore perpendicular to the surface of the object being inspected. iii) The induced current loops are topologically distributed discretely but homogeneously around the high-frequency thin plate. iv) The induced current loop is substantially parallel to the laminated surface of the thin sheets. c. This EMAT is not configured so that the high-frequency laminate becomes a solid sheet. On the contrary, the high-frequency laminate has a hole running through its center, and a current loop rotates around this hole perpendicular to the axis. d. EMAT is not composed of an electric high-frequency coil made of a coil circuit, but is separate from the laminated magnetic core, isolated from the magnetic core by a magnet, and continuously transmits a variable high-frequency magnetic field flux of non-uniform absolute strength in transmission mode to the conductive layer surrounded by high-frequency lamellae of the magnetic core. In contrast, in this invention, EMAT is composed of an electric coil consisting of a high-frequency meander circuit composed of a series of parallel sections of conductors. The magnetic core is not covered by a continuous conductive layer. A current of similar strength flows through each conductive section, but in the opposite direction to the adjacent conductive section. The electric conductors are alternately superimposed directly above and on the upper edge of the high-frequency laminate of the laminated magnetic core. In transmission mode, the high-frequency electric coil emits a vertical variable magnetic field flux that is as strong as the high-frequency laminate. e. In this invention, during transmission, adjacent high-frequency laminates are surrounded by induced current loops rotating in opposite directions. Therefore, on the front surfaces of the object facing each high-frequency active laminate of the laminated magnetic core, a high-frequency variable magnetic field flux is induced in the opposite direction for each high-frequency active laminate, but the intensity is equal on the front surfaces facing adjacent high-frequency active laminates. Thus, an eddy current matrix consisting of parallel vectors with substantially equal intensity but opposite direction is induced on the surface of the object being inspected facing the laminated magnetic core. This topology configuration improves the resolution of the EMAT.

[0037] [Overview of the prefecture] EMAT consists of the following: a. At least one magnet or electromagnet configured to generate a static or quasi-static magnetic field around the object being inspected. b. At least one high-frequency electric coil (or electric circuit) operating at a high frequency, configured as a high-frequency transmitter of the emitted high-frequency electromagnetic field when the EMAT is used for transmission, and as a high-frequency receiver of the emitted high-frequency electromagnetic field when the EMAT is used for reception. c. A matrix consisting of at least one matrix-like laminated magnetic core and a number of laminates periodically stacked along the matrix axis, configured to concentrate and direct the emitted high-frequency electromagnetic field.

[0038] The sandwich-like matrix (23) comprises at least one first group (28) of high-frequency active laminates (29), each laminate insulated from the others and containing a ferromagnetic or ferrimagnetic magnetic material internally. Grooved cylindrical openings (39) penetrate each thin plate (24) of the matrix (23) in a direction substantially parallel to the matrix axis (25) and open into two main matrix surfaces (26), respectively. Multiple magnetic via holes (41) have similar cross-sectional dimensions and are drilled near the center of each high-frequency active laminate (29), aligning to form the grooved cylindrical openings (39). Numerous induced current loops (43) are generated within the high-frequency active laminates (29).

[0039] The distinguishing feature of this EMAT lies in the combination of the following technical means: Each magnetic via hole (41) of each high-frequency active laminate (29) is located between a first side edge surface (36) facing the surface (8) of the material under test (3) and a second side edge surface (37) facing the high-frequency electric coil (6). Each magnetic via hole of the grooved cylindrical opening (39) has no hard material inside, and in particular does not contain any electrical conductors penetrating it, and when the EMAT (1) is in operation, an induced current loop (43) is induced within the active laminate skin (48) at the periphery of the high-frequency active laminate (29).

[0040] In a variation of the embodiment of the present invention, in order to solve the technical problem of (b) above, a laser EMAT probe (LEMAT) is provided that receives and inspects ultrasonic signals emitted from the object to be inspected.

[0041] This LEMAT consists of the following: a. The EMAT according to the present invention, installed in a receiving mode for receiving ultrasonic signals from the object to be examined. b. A laser light source configured to draw a high-energy laser beam to the emission point on the surface of the object to be inspected.

[0042] The laser light source generates ultrasound, specifically primary ultrasound that propagates through the surface, interior, and depths of the object being inspected. This generates secondary ultrasound from echoes resulting from interactions with discontinuities present on or within the object, which propagate through the surface or interior depending on their location. As a result, under the influence of the static magnetic field emitted by the EMAT's magnet, eddy currents are generated in the object by the secondary ultrasound waves. This generates a high-frequency electromagnetic field emitted from the eddy currents in the object, revealing discontinuities on the surface and inside the object.

[0043] In another embodiment of the present invention, to provide a technical solution to the technical problem of (c) above, there is a multi-laser EMAT 3D scanner (MLEMAT) for detecting discontinuities on or inside a cylindrical conductive structure.

[0044] The following is an MLMAT consisting of: a. Conductive structure scanned in 3D. b. A chassis frame configured to surround a conductive structure. c. A multi-laser EMAT probe (LEMAT) fixed on a chassis frame, configured such that each active first edge surface (side edge surface) of the stacked magnetic cores of its matrix faces a conductive structure. d. Means for linearly moving a cylindrical conductive structure relative to the chassis frame.

[0045] A key feature of this MLEMAT is that an aperture loop, formed by imaginary lines connecting the centers of grooved cylindrical openings in adjacent EMAT perforated matrix stacked magnetic cores, surrounds the conductive structure.

[0046] In another embodiment of the present invention, the multi-laser EMAT 3D scanning (MLEMAT) of the present invention is used for automatic adjustment of dynamic soft reduction (DSR) in continuous casting of steel slabs at casting temperatures of 1000°C or higher. This provides a technical solution to the above technical problem (d).

[0047] By continuously passing the steel slab wire through a Dynamic Soft Reduction Device (DSRD), macrosegregation and porosity formation in the central semi-solid region within the steel slab wire are suppressed, dynamically compensating for solidification shrinkage and blocking the suction flow of residual molten metal within the steel slab wire. The high-frequency electrical coil of each laser EMAT in the MLEMAT is connected to a Casting Dynamic Three-Dimensional Mapping System (3DMS). This 3DMS includes an analog-digital processing means (MDAN) configured to couple and process the secondary ultrasonic current radiated to the electrical coil of each laser EMAT in the MLEMAT. This current is induced in each high-frequency electrical coil of the laser EMAT by material eddy currents in the front zone of the inspection material of the steel slab wire. These eddy currents are generated by the interaction between echoes from the laser light source and the surface and internal discontinuities of the material being inspected in the front zone of the first edge face of the laser EMAT. MDAN combines the ultrasonic secondary currents of each EMAT and generates a dynamic 3D mapping (3DM) of the strand structure of the steel slab located in the plane of the frame, based on the combination of multiple ultrasonic secondary currents of each laser EMAT of MLEMAT and numerical analysis. The casting strand DSR optimization system (DSRM) is connected to the 3DMS. The DSRM receives the 3DM of the slab steel and generates dynamic DSR optimization parameters (PCSD) through digital processing. A digital DSR activator (ASR) is connected to the DSRM and dynamically adjusts the DSR action parameters (PASD) as a function of the PCSD generated by the DSRM.

[0048] The distinguishing feature of this MLEMAT lies in the combination of the following technical means: The cooling means of the EMAT of the present invention generates a cooling flow of heat transfer fluid. This cooling fluid is forced into each magnetic via hole in the grooved cylindrical opening of the adjacent EMAT perforated matrix laminated magnetic core of the MLEMAT, and into each spacer via hole, at a cooling temperature (TF) that is more than 50°C lower than the Curie temperature (TC) of the open high-frequency active laminate magnetic material. In this way, dynamic soft reduction (DSR) and dynamic secondary cooling (DSC) are dynamically controlled at casting temperatures of 1000°C or higher.

[0049] These features, embodiments, and advantages of the present invention will be better understood by reading the following detailed description with reference to the accompanying drawings. Throughout the drawings, similar symbols represent the same part. [Brief explanation of the drawing]

[0050] [Figure 1] This is a perspective view of the EMAT probe of the present invention. [Figure 2] This is a cross-sectional view of the EMAT probe of the present invention. [Figure 3] This is a schematic diagram illustrating one operating mode of the high-frequency laminate in the perforated matrix laminated magnetic core of the EMAT probe of the present invention, which is used for transmission. [Figure 4] This is a perspective view showing one operating mode of high-frequency active lamination of the perforated matrix laminated magnetic core of the EMAT probe of the present invention, used in receiving mode. [Figure 5] This is a perspective view showing the perforation matrix laminated magnetic core of the EMAT probe of the present invention, constructed by laminating a high-frequency active laminate and a passive laminate. [Figure 6] Figure 6 is a partial perspective view of the electromagnetic operation of the high-frequency active laminate of the perforated matrix laminated magnetic core of the EMAT probe of the present invention, used in emission mode. [Figure 7]Figure 7 shows another embodiment of the present invention, a perforated matrix laminated magnetic core laminate of an EMAT probe. In this embodiment, the perforated matrix laminated magnetic core is dynamically raised away from the object being inspected. [Figure 8] Figure 8 is a cross-sectional view of the laser EMAT probe (LEMAT) according to the present invention. [Figure 9] Figure 9 is a side view of the multi-laser EMAT 3D scanner (MLEMAT) according to the present invention. [Figure 10] Figure 10 is a cross-sectional view of the multi-laser EMAT 3D scanner (MLEMAT) according to the present invention for automatic adjustment of dynamic soft reduction (DSR) and dynamic secondary cooling (DSC) in continuous casting of molten steel slabs, displayed at the EMAT probe level. [Figure 11] Figure 11 is a cross-sectional perspective view of the Multi-Laser EMAT 3D Scanner (MLEMAT) according to the present invention for automatic adjustment of dynamic soft reduction (DSR) and dynamic secondary cooling (DSC) in continuous casting of molten steel slabs, displayed at the laser light source level. [Figure 12] Figure 12 is a functional block diagram of the multi-laser EMAT 3D scanner (MLEMAT) according to the present invention for automatically adjusting dynamic soft reduction (DSR) and dynamic secondary cooling (DSC) in the continuous casting of molten steel slabs.

[0051] [Modes for carrying out the invention] The embodiments described below relate to an improved EMAT system (1) that can be used for non-destructive testing (NDT) of conductive structures (90) at temperatures above 1000°C.

[0052] Figures 1 and 3 show an electromagnetic ultrasonic probe (EMAT) (1) for detecting surface and internal discontinuities (2) of a conductive object under test (3). Two magnets (4) are configured to generate a static or quasi-static magnetic field (SMF) on the object under test (3). Each magnet (4) can be replaced with an electromagnet. A high-frequency electric coil (6) (or electric circuit) is placed directly above the perforated matrix laminated magnetic core (22). Its winding plane (7) (or circuit plane) is parallel to the local inspection surface (8) of the object under test (3) facing the EMAT (1). The two magnets (4) are placed on either side of the perforated matrix laminated magnetic core (22).

[0053] Figure 3 confirms that EMAT(1) can be used in transmit mode (EM). The high-frequency electric coil (6) is configured as a high-frequency electromagnetic transmitter (9) of the emitted high-frequency electromagnetic field (HFEMF). It is connected to the output of at least one AC current source (11) and generates high-frequency alternating current (AC) at an ultrasonic frequency in the high-frequency electric coil (6). The emitted high-frequency electromagnetic field generates material eddy currents (14) on the surface of the object under inspection (3). As a result of the interaction between the material eddy currents (14) and the static magnetic field (SMF), a Lorentz force (15) at an ultrasonic frequency is generated on the object under inspection (3). In addition, if the object under inspection is a ferrimagnetic material, magnetostriction may also be generated. Furthermore, disturbances in the Lorentz force (15) directly generate an ultrasonic primary wave (17) on the object under inspection (3).

[0054] Figure 4 shows that EMAT(1) can also be used in receiving mode (RM). The high-frequency electric coil (6) is configured as a high-frequency electromagnetic receiver (18), and a secondary ultrasonic current (19) of ultrasonic frequency passes through it. This high-frequency current consists of a secondary ultrasonic electrical signal (88) generated by an emitted high-frequency electromagnetic field (HFEMF) induced by material eddy currents (14). These eddy currents (14) are generated on the inspection surface (8) of the object to be inspected (3) by secondary ultrasound (21) under the influence of an external ultrasonic source and interact with the static magnetic field (SMF). These eddy currents (14) indicate discontinuities (2) on the surface and inside of the object to be inspected (3).

[0055] Looking again at Figures 1 and 2, we can see that a perforated matrix laminated magnetic core (22) is positioned between the inspection surface (8) of the object under inspection (3) and the high-frequency electric coil (6) that directly faces it. The magnetic core (22) of the perforated matrix laminate is configured to concentrate and dielectric the emitted high-frequency electromagnetic field (HFEMF) in the direction of the object under inspection (3) or the direction from which it is coming, depending on whether the EMAT (1) is used for transmission or reception. The EMAT consists of a sandwich-like matrix (23) made up of a number of thin sheets (plates) (24) stacked together. This is stacked between the two main matrix surfaces (26) of the matrix (23) along the matrix axis (25) and parallel to the plan (27) of the stacking. The perforated matrix laminated magnetic core (22) has multiple edge surfaces (35) with laterally adjacent grooves that are substantially perpendicular to the plan (27) of the stacking and extend parallel to the matrix axis (25).

[0056] Looking at Figure 2, we can see that one side of the edge surface (35), namely the first edge surface (36) of the matrix (23), faces the inspection surface (8) of the object to be inspected (3). The other side, namely the second edge surface (37) of the matrix (23), is located substantially opposite the first edge surface (36) and faces the high-frequency electric coil (6).

[0057] Referring to Figures 1 and 5, it can be seen that each laminated thin sheet (24) of the matrix (23) has similar spatial geometry and transverse dimensions to that of adjacent laminated thin sheets (24) of the matrix (23). They have two main transverse sheet surfaces (32), each parallel to the plan (27) of the lamination.

[0058] Referring to Figures 1 and 5, it can be seen that the combined, continuous, adjacent peripheral edges (33) of the thin sheets (24) form grooved edge surfaces (34) of the matrix (23) surrounding the matrix axis (25). The core axis (38) of the matrix (23) is joined at the center of the first edge surface (36) and the second edge surface (37). This is positioned substantially perpendicular to the matrix axis (25).

[0059] In Figures 5 and 6, it can be seen that the matrix (23) consists of a first multitude (28) of high-frequency active laminates (29) (four are shown in the figures), or a group of such laminates. Each high-frequency active laminate (29) is isolated from the others. It incorporates a magnetic material (particularly ferromagnetic or ferrimagnetic) with high permeability. The magnetic material has a certain Curie temperature (TC). It also has a conductive material on the outside, or its outer edge (33) can be covered with a conductive layer. Grooved cylindrical holes (apertures) (39) are arranged along the aperture axis (40) of the matrix (23), through the thin sheet (24) of the matrix (23), substantially parallel to the matrix axis (25) and perpendicular to the core axis (38). They open to each of the two matrix planes (26). A multitude (41) of magnetic via holes with similar cross-sectional dimensions and closed perimeters are drilled through multiple high-frequency active laminates (29) cut out from the matrix (23) and perforated in the center. This allows each of the multiple high-frequency active laminates (29) cut out from the matrix (23) to penetrate along an axis substantially parallel to the inspection surface (8). This is positioned parallel to the inspection surface (8), thereby forming a grooved cylindrical aperture (39). There is a longitudinal envelope (42) of the via holes along the opening axis (40) of the matrix (23), and its lateral perimeter is closed. In Figures 3 and 4, it can be seen that when the EMAT (1) is operating, an induced current loop (43) is induced by the emitted high-frequency electromagnetic field (HFEMF). As shown in Figure 3, in transmission, this electromagnetic field emits ultrasonic frequency alternating current (AC) from the high-frequency coil (6), and in reception, as shown in Figure 4, ultrasonic frequency material eddy currents (14) are emitted from the object under test (3). The induced current loops (43) are located inside the active laminate skin (48) on the outer periphery of the high-frequency laminate (29) of the perforated matrix laminated magnetic core (22). As shown in Figure 6, this is arranged according to loop mapping (LM), which defines the topology, distribution, and relative position of all induced current loops (43).

[0060] Figure 2 shows that EMAT(1) has the following characteristics: Each magnetic via hole (41) of each high-frequency active laminate (29) is located between a first edge surface (36) facing the surface under test (8) and a second edge surface (37) facing the high-frequency electric coil (6). There are no hard materials inside each magnetic via hole (41) of the grooved cylindrical aperture (39). In particular, there are no electrical conductors. Figure 6 shows that the loop mapping (LM) is topologically discrete and consists of numerous induced current loops (43) of distant high-frequency laminates (29) (or groups thereof). Figure 3 shows that induced current loops (43) (or groups of loops) are generated inside the laminate skin (48) on the peripheral edge (33) of the high-frequency active laminate (29). These are parallel to the stacking plan (27) and perpendicular to the surface of the object under test (3). Furthermore, they are substantially parallel and spaced apart between each high-frequency active laminate (29). This surrounds and rotates the magnetic via holes (41) of the high-frequency laminate (29). In Figure 6, it can be seen that each core-spacing slice (49) and its surface of the perforated matrix laminate magnetic core (22) located between two adjacent high-frequency active laminates (29) (or groups) has no induced current loops (43) and no induced current.

[0061] Figure 3 shows that the emitted high-frequency electromagnetic field (HFEMF) and the magnetic core (22) of the perforated matrix laminate are configured as follows. When the EMAT (1) is operating, the high-frequency core magnetic field (HFIMF) has a significant component of the high-frequency core transverse magnetic field (MFTHF). This is perpendicular to the laminate plan (27), perpendicular to each high-frequency active laminate (29), and substantially parallel to the surface of the material under test (3). The high-frequency magnetic flux (MFHF) within the perforated matrix laminate magnetic core (22) is mostly perpendicular to the core axis (38) and parallel to the surface of the material under test (3), and therefore not perpendicular to the inspection surface (8) of the material under test (3). A closed induced current loop (43) is generated by the HF core transverse magnetic field (MFTHF) on the peripheral edge (33) of each high-frequency active laminate (29).

[0062] In Figures 5 and 6, a complex and interactive dual physical effect occurs within the perforated matrix laminated magnetic core (22). Meanwhile, the multiple parallel and topologically discrete induced current loops (43) of the high-frequency active laminate (29) each independently generate high-frequency magnetic fields, separately and locally increasing discrete and selective high-frequency magnetic coupling between the narrow local active region (44) of the surface under test (8) and the high-frequency electric coil (6), contributing to the mutual reduction of the high-frequency magnetoresistance of the EMAT (1). On the other hand, the inner circumference (45) of the magnetic via hole (41) of the high-frequency active laminate (29) forms a heat conduction and convection surface (46) at the center of the high-frequency active laminate (29), generating an internal thermal cooling effect of the induced current loops (43), contributing to the improvement of the efficiency of the EMAT (1).

[0063] Figure 5 shows a perforated matrix laminate magnetic core (22) having high-frequency active laminates (29) separated by passive laminates (53). Each high-frequency active laminate (29) of the matrix (23) (or group of such active laminates) is separated in adjacent core spacing slices (49) by at least one sheet of a second multitude numeracy (54) of the passive laminate (53) made of electrical insulating material. Each passive laminate (53) is perforated by spacer via holes (57). Each passive laminate (53) is arranged such that the magnetic via holes (41) of the first multitude (28) of the high-frequency active laminate (29) of the matrix (23) and the spacer via holes (57) of the second numeracy (54) of the passive laminate (53) of the matrix (23) are parallel to the matrix axis (25). The arrangement and combination of these elements form a grooved cylindrical opening (39).

[0064] This electromagnetic ultrasonic probe (EMAT) (1) has the following characteristics: Each spacer via hole (57) of each passive laminate (53) is positioned between a first edge surface (36) facing the object under inspection (3) and a second edge surface (37) facing the high-frequency electric coil (6). Each spacer via hole (57) of the grooved cylindrical opening (39) does not contain any rigid material inside. In particular, it does not contain any electrical conductors. The inner circumference of each spacer via hole (57) of each passive laminate (53) of the matrix (23) forms a heat conduction and convection surface (46) at the center of the passive laminate (53). This generates an internal thermal cooling effect in the spacer via hole (57) for the dissipation of electrical and thermal energy generated by the induced current loop (43) of the adjacent high-frequency active laminate (29). This contributes to improving the efficiency of the EMAT (1).

[0065] As shown in Figure 5, it is recommended that the peripheral edges (33) of each passive laminate (53) have no conductive material covering their surface. Thus, the grooved edge surface (34) of the perforated matrix laminated magnetic core (22) is made of a conductive layer, but conversely, it consists of alternating edges with conductive rings around the high-frequency active laminate (29) on the one hand and insulating rings around the passive laminate (53) on the other.

[0066] In the embodiment shown in Figure 5, the perforated matrix laminated magnetic core (22) of EMAT(1) has a cooling means (58) which generates a cooling flow (59) of a heat transfer fluid (60) at a cooling temperature (TF). This cooling flow (59) is forced to pass through grooved cylindrical openings (39) of the matrix (23). EMAT(1) in this configuration has the following features: The cooling flow (59) is configured to pass sequentially through one of the magnetic via holes (41) of the first multitude (28) or through at least one of the spacer via holes (57) of the second multitude (54). It covers all of the wall surfaces (62) of each magnetic via hole (41) and each spacer via hole (57) of the matrix (23). This increases the internal thermal cooling effect in each high-frequency active laminate (29) of the matrix (23). In other words, it undergoes induced current loops (43) and heat dissipation. In this invention, it is ideal to adjust the cooling temperature (TF) of the cooling flow (59) to a temperature (at least 50°C) that is considerably lower than the specific Curie temperature (TC) of the magnetic material of each open-ended high-frequency active laminate (29).

[0067] Figure 7 shows another preferred embodiment of the EMAT(1) of the present invention. At least one (preferably many) (multiple) thin sheets (24) of the perforated matrix stacked magnetic core (22) are perforated by cushion holes (63) or have cushion notches (64). These openings pass between an annular wall (65) formed between via holes (41, 57) and a first edge surface (36) facing the object under inspection (3), in a direction parallel to the stacking plan (27). This forms a cushion recess (66) between the via holes (41, 57) of the thin sheet (24) and the first edge surface (36) facing the object under inspection (3). The cooling method (58) is configured to extract the cushion fluid flow (67) from the cooling flow (59) passing through the via holes (41, 57). This extracted cushion fluid flow (67) is pressurized and flowed into the cushion recess (66). As a result, a lift air cushion (70) is formed between the perforated matrix laminated magnetic core (22) and the object under inspection (3) at the height of the cushion recess (66) facing the object under inspection (3). This lifts the perforated matrix laminated magnetic core (22) above the gap (68) in the cushion of the object under inspection (3). This is a highly reliable method. This allows the cushion gap (68) to be adjusted both dynamically and mechanically. It can be understood that this arrangement significantly reduces the thermal energy conducted between the object under inspection (3) and the perforated matrix laminated magnetic core (22) and to the moving parts. This arrangement eliminates friction. Furthermore, by reducing wear during maintenance, it is possible to significantly improve the operating time and uptime of EMAT (1).

[0068] Figure 5 shows another embodiment of the EMAT(1) of the present invention. Two outer side edge surfaces (35) located on the matrix surface (26) are composed of or covered by a conductive material cover layer (69) (as shown in the figure). The EMAT(1) in this configuration has the following features: Via holes having similar lateral dimensions to the magnetic via holes (41) are perforated in each of the two conductive cover layers (69). The multiple thin sheets (24) of the matrix (23) and the two conductive coating layers (69) are positioned relative to each other such that their multiple via holes form a grooved cylindrical opening (39).

[0069] According to the embodiment shown in Figure 5, the area around each magnetic via hole (41) formed in each high-frequency active laminate (29) is rectangular. The center of each magnetic via hole (41) is located at the center (centroid) of its high-frequency active laminate (29). The area around each magnetic via hole (41) is positioned at a certain distance (Ring Distance, Rd) from the peripheral edge (33) of its high-frequency active laminate (29). In this configuration, each high-frequency active laminate (29) is phase-configured as a rectangular active ring (71) that is thermodynamically cooled from the heating of the induced current loop (43) generated around it.

[0070] Figures 1 and 2 show another embodiment of the EMAT(1) of the present invention. The second edge surface (37) of the perforated matrix laminated magnetic core (22) faces the high-frequency electric coil (6) directly. The magnet (4) is not positioned between the second edge surface (37) of the matrix (23) and the high-frequency electric coil (6).

[0071] Figure 6 shows another embodiment of the EMAT(1) of the present invention. Here, the first multitude (28) of high-frequency electric coils (6) and high-frequency active laminates (29) in the matrix (23) is configured as follows: The orientation, pitch, size, and shape of each edge (72) of the high-frequency active laminate facing the circuit match and correlate with the geometric parameters such as orientation, pitch, size, and shape of the conductivity (75) of the continuously facing high-frequency electric coils (6).

[0072] A preferred configuration of the above is shown in Figure 3. It can be seen that the high-frequency electric coil (6) has at least one fraction of linear conductor (73). The latter is positioned in close proximity to and directly above the edge (72) facing the circuit. It is in contact with the high-frequency active laminate (29) located on the second edge surface (37) of the matrix (23) facing the high-frequency electric coil (6) along a parallel axis present around it. This arrangement is characteristic of the present invention, and the small amount of linear conductor portion (73) and the matrix laminate magnetic core (22) are configured to generate an induced current loop (43) in the active laminate skin (48) on the outer periphery of the high-frequency active laminate (29) when the EMAT (1) is operating. This surrounds a magnetic via hole (41). This results in locally selective high-frequency magnetic coupling between, on the one hand, high-frequency alternating current (AC) generated by linear conductor portions (73) extending along the periphery of the high-frequency active laminate (29), and on the other hand, eddy currents (14) of the material generated in a narrow locally active region (44) of the inspection surface (8) facing the high-frequency active laminate (29).

[0073] It is known that the high-frequency electromagnetic fields (HFEMF) emitted from the linear conductor portion (73) through which the current flows are orthogonal. Therefore, the high-frequency magnetic flux lines (MFHF) are essentially composed of circles surrounding the linear conductor portion (73).

[0074] Figure 3 shows EMAT(1). Here, in transmit mode (EM), the high-frequency alternating current (AC) flowing through the linear conductor portion (73) generates a loop-shaped orthogonal magnetic flux, creating a conductor high-frequency magnetic flux loop (76) and forming a high-frequency core transverse magnetic field (MFTHF) perpendicular to the high-frequency active laminate (29). This generates an induced current loop (43) on the surface of the active ring (71) of the high-frequency active laminate (29). This induced current loop (43) sequentially emits a number of high-frequency magnetic flux loops, generating eddy currents (14). These eddy currents are topologically ordered and all are arranged parallel to the plane of the opposing high-frequency active laminate (29).

[0075] Furthermore, it is known that in a circular turn where current is supplied, a bundle of magnetic field lines is generated in the form of numerous magnetic flux loops passing through the center, parallel to the axis.

[0076] Figure 4 shows that when EMAT(1) is used in receiving mode (RM), the eddy current (14) component parallel to the stacking plan (27) generated on the surface of the material induces a high-frequency flux loop (77) that creates a high-frequency core transverse magnetic field (MFTHF) under the influence of an external ultrasonic source. Due to the influence of the external ultrasonic source, the high-frequency flux loop (77) is generated, and a high-frequency core transverse magnetic field (MFTHF) is formed perpendicular to the active ring (71) of the high-frequency active laminate (29) facing the eddy current (14). This forms an induced current loop (43) within the skin (48) of the active laminate. This induced current loop (43) surrounding the high-frequency active laminate (29) in the longitudinal direction then emits a number of high-frequency flux loops surrounding fractions of the linear conductor portion (73) that are in contact with the periphery of the high-frequency active laminate (29). This inductively generates a secondary ultrasonic electrical signal (88), which in turn generates a high-frequency alternating current (AC) in the linear conductor portion (73).

[0077] In another embodiment shown in Figures 3 and 6, the high-frequency electric coil (6) is a meander circuit (74). It has a number of (at least two) adjacent linear conductor portions (73) through which high-frequency alternating current (AC) flows alternately in opposite directions (four shown in Figure 6). They are parallel to each other and adjacent. The linear conductor portions (73) of the meander circuit (74) are close to and directly above the circuit-facing edge (72) of the high-frequency active laminate (29) located on the second edge surface (37) of the matrix (23) facing the high-frequency electric coil (6). These are configured such that the high-frequency alternating current (AC) passing sequentially through the linear conductors (73) parallel to the meander circuit (74) alternately faces opposite directions. It can be seen that the high-frequency conductive flux loop (76) substantially perpendicularly surrounds the linear conductive portion (73) of the meander circuit (74) and substantially perpendicularly penetrates the interior of the high-frequency active laminate (29) facing it. It also has the following features: The linear conductive portion (73) of the meander circuit (74) and the perforated matrix laminated magnetic core (22) are configured to traverse the active laminate skin (48) by adjacent induced current loops (43) when the EMAT (1) is in transmit mode (EM). These each generate induced current loops (43) that rotate in opposite directions (78) around an aperture axis (40) passing through a magnetic via hole (41). One is clockwise and the other is counterclockwise.

[0078] Figure 1 shows that the depth (Od) of the grooved cylindrical opening (39) of the perforated matrix multilayer magnetic core (22) along its opening axis (40) is substantially equal to the first transverse dimension (FTd) of the high-frequency electric coil (6) of the EMAT (1). Furthermore, the grooved second edge surface (37) of the hole in the matrix multilayer magnetic core (22) facing the high-frequency electric coil (6) is substantially equal to the second transverse dimension (STd) of the high-frequency electric coil (6) of the EMAT (1) in a direction perpendicular to the aperture axis (40) of the sandwich (23).

[0079] According to another embodiment shown in Figure 5, the geometric tolerance (79) of the perforated thin sheet (24) of the matrix (23) and the coupled geometric tolerance of the perforated matrix laminated magnetic core (22) are adjusted to be decorrelated to the wavelength of the major harmonics of the emitted high-frequency electromagnetic field (HFEMF). This prevents mechanical resonance of the perforated matrix laminated magnetic core (22) at the ultrasonic frequencies when the EMAT (1) is operating.

[0080] According to another embodiment, the sheet geometric tolerance (79) of the perforated laminated thin sheets (24) of the perforated matrix laminated magnetic core (22) is adjusted to be much smaller than the wavelength of ultrasound generated in the laminated thin sheets (24), or substantially equal to an odd number of quarters of the wavelength of ultrasound generated in these laminated thin sheets (24).

[0081] According to another embodiment of the present invention shown in Figure 2, the first grooved first edge surface (36) of a perforated matrix laminated magnetic core (22) facing the object to be inspected (3) and positioned parallel to the grooved cylindrical opening (39) is covered by an insulating layer (81) (as shown) made of an electrical insulating material, or is covered by the electrical insulating material itself. One side of the insulating layer (81) is positioned facing the grooved cylindrical opening (39) and covers the edge of the first edge surface (36) that belongs to the outer periphery of each of the high-frequency active laminates (29).

[0082] The EMAT(1) of the present invention and the above example provide a technical solution to the above technical problem (a). This EMAT(1) increases the energy transfer of the emitted high-frequency electromagnetic field (HFEMF). It maximizes the high-frequency magnetic coupling between the high-frequency coil (6) and the material eddy currents (14) generated on the surface of the object under inspection (3), and minimizes leakage of the magnetic flux of the emitted high-frequency electromagnetic field. Furthermore, it ensures the homogeneity of the topology of the high-frequency electromagnetic field coupling between the high-frequency coil (6) and the material eddy currents (14) of the object under inspection facing the probe. Moreover, it can operate at high temperatures of the object under inspection (3) exceeding 1000°C.

[0083] As shown in Figure 8, the laser EMAT probe (LEMAT) (82) examines the object to be examined (3) by receiving an ultrasonic signal from it. LEMAT is composed of the following combinations. i) The electromagnetic ultrasonic probe (EMAT) (1) according to the present invention described above, and ii) A laser light source (84). The EMAT (1) is set to receiving mode (RM) for receiving the secondary ultrasonic electrical signal (88) of the object under inspection (3). The high-frequency electric coil (6) is configured as a high-frequency electromagnetic receiver (18). As shown in Figure 4, this secondary ultrasonic electrical signal (88) is electrically induced by the emitted high-frequency electromagnetic field (HFEMF) emitted from the object under inspection (3). This is generated by eddy currents (14) generated in the object under inspection (3) by the secondary ultrasound (21). These eddy currents (14) indicate discontinuities (2) on the surface or inside the object under inspection (3). As shown in Figure 8, the perforated matrix laminated magnetic core (22) is positioned between the high-frequency electric coil (6) of the EMAT (1) and the object under inspection (3). It faces the high-frequency coil (6) directly. Furthermore, it also ensures a protective gap (83) between the object under inspection (3) and the high-frequency coil (6). This reduces the magnetic reluctance of the EMAT (1). Furthermore, it protects the object being inspected (3) from high temperatures and surface conditions. The laser light source (84) is configured to project a high-energy laser beam (85) onto the emission point (86) on the surface of the object being inspected (3). The laser beam (85) generates primary ultrasound (17) that propagates through the surface and interior of the object being inspected (3). Then, due to the interaction between the primary ultrasound (17) and the discontinuities (2) on the surface and interior of the object being inspected (3), secondary ultrasound (21) is generated. This secondary ultrasound wave (21) propagates through the surface and interior of the object being inspected (3). This secondary ultrasound wave (21) is affected by the static magnetic field (SMF) generated by the magnet (4) of the EMAT (1), and the mechanical vibration of the secondary ultrasound wave (21) generates eddy currents (14) on the surface of the object being inspected (3). This induces a high-frequency electromagnetic field (HFEMF) emitted by the material eddy currents (14) present on the surface of the object to be inspected (3), which indicates the shape and location of discontinuities (2) on the surface and inside the object to be inspected (3). By processing this emitted high-frequency electromagnetic field (HFEMF) through the EMAT (1), a secondary ultrasonic electrical signal (88) is generated in the high-frequency electric coil (6).

[0084] In Figure 4, EMAT(1) is set to receiving mode, and the laser EMAT probe (LEMAT)(82) has the following technical features: Emitted high-frequency electromagnetic fields (HFEMF) emitted from material eddy currents (14) of the material being inspected (3) by the laser (84) induce remotely induced current loops (43) on the skin (48) of the active laminate on the peripheral edge (33) of each high-frequency active laminate (29) of the perforated matrix laminated magnetic core (22). In Figure 6, these induced current loops (43) of the high-frequency active laminate (29) (or group) are spaced apart from one another. These eddy current-induced loops (43) surround the magnetic via holes (41) of the high-frequency active laminate (29) and rotate around the magnetic active ring (71). It is located between the first edge surface (36) facing the material being inspected (3) and the second edge surface (37) facing the high-frequency coil (6). It is substantially perpendicular to these two edge faces (36, 37).

[0085] In this LEMAT (82), it can be seen that a complex and interactive dual physical effect occurs within the perforated matrix laminated magnetic core (22). On the other hand, as shown in Figure 4, multiple discrete and parallel-flowing induced current loops (43) in the perforated high-frequency active laminate (29) (or group thereof) separately generate high-frequency magnetic fields. This increases the high-frequency magnetic coupling between the locally active portion (44) of the inspection surface (8) facing the first edge surface (36) and the high-frequency electric coil (6). This homogenizes the high-frequency coupling and acts to reduce the high-frequency magnetic reluctance of EMAT (1). On the other hand, as shown in Figure 5, a free heat conduction and convection surface (46) is generated at the center of each high-frequency active laminate (29) on the inner circumference (45) of each magnetic via hole (41) of each high-frequency active laminate (29) of the matrix (23). This results in an internal thermal cooling effect that dissipates some of the electrical energy and heat energy generated by the induced current loop (43) of that particular high-frequency active laminate (29). This contributes to improving the efficiency of EMAT (1).

[0086] The LEMAT(82) of the present invention provides a technical solution to the above technical problem (b). It optimizes the detection of surface and internal discontinuities (2) in thick metal structures. It can be used even when the object to be inspected (3) is at a high temperature exceeding 1000°C.

[0087] Figure 9 shows a multi-laser EMAT 3D scanner (MLEMAT) (89) for detecting discontinuities (2) on the surface or inside a cylindrical conductive structure (90). The MLEMAT (89) consists of a) a conductive structure (90) to be 3D scanned, b) a chassis frame (93), c) a group of probes (96) consisting of at least two laser EMAT probes (LEMAT) (82) according to the present invention, and d) a displacement means (97). The conductive structure (90) to be 3D scanned is made of a conductive object to be inspected (3). It has a cylindrical structure generated along a structural axis (91) and a structural part (92). The chassis frame (93) is configured to surround the conductive structure (90) by a frame distance (Fd). Its frame plane (95) is substantially perpendicular to the structural axis (91) of the conductive structure (90). The displacement means (97) is configured to move the cylindrical conductive structure (90) linearly relative to the chassis frame (93) along a displacement direction (Md) that substantially coincides with the structural axis (91).

[0088] This multi-laser EMAT 3D scanner (MLEMAT) (89) has the following features as shown in Figure 10. Furthermore, the aperture loop (99) is composed of virtual lines, which are formed by the center (39) of the groove-shaped cylindrical opening. This groove-shaped cylindrical opening is located in the perforated matrix stacked magnetic core (22) of each EMAT (1) adjacent to the laser EMAT probe (LEMAT) (82) of the MLEMAT (89), and surrounds the conductive structure (90).

[0089] Furthermore, the group of probes (96) consisting of laser EMAT probes (82) is fixed on the chassis frame (93). This arrangement adjacent to the first edge surface (36) is adjacent to the laser EMAT probe (LEMAT) (82) perforated matrix stacked magnetic core (22) and forms a continuous grooved inspection ring (100) facing the object to be inspected (3). This grooved inspection ring (100) surrounds the outer circumference of the conductive structure (90) in the structural part (92) of the conductive structure (90) near the frame surface (95).

[0090] In the embodiment of the multi-laser EMAT 3D scanner (MLEMAT) (89) shown in Figure 11, the laser source (84) of each MLEMAT (82) is composed of an optical fiber (101) fixed to the frame plane (95) and having an emission end (102) facing the conductive structure (90). This optical fiber (101) is connected to a laser generator (103). The multi-laser EMAT 3D scanner (MLEMAT) (89) with this configuration has the following features: A laser emission loop (104), formed by imaginary lines connecting the emission 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).

[0091] In another embodiment of the multi-laser EMAT 3D scanner (MLEMAT) (89) of the present invention, it is used to detect discontinuities (2) on the surface or inside a metal slab (105). The conductive structure (90) is a cylindrical metallurgical slab (105) which is movable relative to the MLEMAT (89). An aperture loop (99) is formed by imaginary lines connecting the centers of the grooved cylindrical apertures (39) of the perforated matrix stacked magnetic cores (22) of each EMAT (1) adjacent to the laser EMAT probe (LEMAT) (82) of the MLEMAT (89) and surrounds this cylindrical metal slab (105).

[0092] In another embodiment of the multi-laser EMAT 3D scanner (MLEMAT) (89) of the present invention, discontinuities (2) on the surface and inside of a continuously cast cylindrical steel slab (105) cast at a casting temperature (TS) above 1000°C are used. The high-frequency active laminate (29) of the perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the MLEMAT (89) is made of a magnetic material of the ferromagnetic or ferrimagnetic type having a Curie temperature (TC) lower than the casting temperature (TS), for example. As shown in Figure 10, each grooved cylindrical opening (39) is connected to a cooling means (58). This heat-transferring fluid (60) is injected into each via hole (41, 57) at a cooling temperature (TF) more than 50°C lower than the Curie temperature (TC) of the magnetic material of the perforated high-frequency active laminate (29).

[0093] This MLEMAT (89) and its modifications detailed above provide a technical solution to the technical challenge (c) described above. The MLEMAT performs a continuous three-dimensional scan of a large, thick movable conductive structure (90), such as a metallurgical slab (105), from a single location, generating a high-resolution 3D map of the structure, including providing the location of surface and deep discontinuities (2). Furthermore, it can be used even at high temperatures, such as when the temperature of the object being inspected (3) exceeds 1000°C.

[0094] Figure 12 shows a multi-laser EMAT 3D scanner (MLEMAT) (89). It is configured to automatically adjust the parameters of dynamic soft reduction (DSR) for steel slabs (105) continuously cast at casting temperatures (TS) exceeding 1000°C in a steel mill. The continuous casting of steel slabs (105) uses a dynamic soft reduction device (DSRD) to suppress the formation of macrosegregation zones and porosity zones that occur during the continuous casting of steel slabs (105). This dynamically compensates for the solidification shrinkage of the steel and blocks the suction flow of molten metal remaining in the central massy zone (106) of the steel slab (105).

[0095] This MLMAT(89) is coupled to a dynamic soft reduction device (DSRD) which consists of the following components: i) A dynamic 3D mapping system (3DMS) is used to generate a continuous casting dynamic 3D mapping (3DM) of a steel slab (105). ii) A computerized DSR optimization system (DSRM) that generates dynamic DSR optimization parameters (PCSD) based on dynamic 3D mapping (3DM) and continuous casting parameters. It has a digital DSR activator (ASR) that dynamically adjusts the DSR action parameters (PASD) of a dynamic soft reduction device (DSRD) based on the PCSD generated by the DSRM.

[0096] This multi-laser EMAT 3D scanner (MLEMAT) (89) has the following features: The high-frequency electric coils (6a, 6b, 6) of the laser EMATs (82a, 82b, 82) and EMATs (1a, 1b, 1) of the MLEMAT (89) are each connected to a dynamic 3D mapping system (3DMS). Eddy currents (14) in the material on the front (110) of the inspection target (3) of the steel slab (105) facing a portion of each EMAT (1a, 1b, 1) transmit secondary ultrasonic electrical signals (88a, 88b, 88) dielectric by the high-frequency electric coils (6a, 6b, 6). The DSR optimization system (DSRM) includes analog and digital processing means (MDAN). MDAN is configured to receive numerous secondary ultrasonic electrical signals (88a, 88b, 88) contained in the secondary ultrasonic electrical currents (19a, 19b, 19) traversing each high-frequency electrical coil (6) of the laser EMAT (82a, 82b, 82) of the MLEMAT (89). MDAN is also configured to identify changes and perturbations in each secondary ultrasonic electrical signal (88a, 88b, 88) of the laser EMAT (82a, 82b, 82) caused by discontinuities (2) in partially activated fractions (44a). From the object under inspection (3) facing each laser EMAT (82a, 82b, 82), the frontal topology (DTa, DTb, DT) of the defect at this locally activated site (44a, 44b, 44) is digitally estimated and generated. Furthermore, MDAN digitally synthesizes the Frontal Topology of Defects (DTa, DTb, DT) to digitally generate a 3D mapping (dynamic 3D mapping (3DM)) of the interior of the continuous casting of the steel slab (105) physically observed with MLEMAT (89). Based on the combination of the synthesized signals of multiple secondary ultrasonic electrical signals (88a, 88b, 88) and digital analysis, the signals of multiple secondary ultrasonic electrical signals are analyzed in the frontal zone (110) facing the inspection ring (100) in the structural part (92) of the frame surface (95).

[0097] In Figure 10, the cooling means (58) generates a cooling flow (59) of heat transfer fluid (60) that is forced under pressure into the via holes (41, 57) of the grooved cylindrical opening (39) of each perforated matrix laminated magnetic core (22) in each adjacent EMAT (1) of the MLEMAT (89). This results in a cooling temperature (TF) that is more than 50°C lower than the Curie temperature (TC) of the magnetic material of the perforated high-frequency active laminate (29).

[0098] Thanks to MLEMAT(89), it can be seen that the DSR action parameters (PASD) of the dynamic soft reduction device (DSRD) can be dynamically adjusted in an optimal manner at casting temperatures (TS) above 1000°C, based on the dynamic 3D mapping (3DM) of the continuous casting of steel slabs (105) physically observed by MLEMAT(89).

[0099] Figure 12 shows a variation (89) of the multi-laser EMAT 3D scanner (MLEMAT) that automates the dynamic parameters of dynamic soft reduction (DSR) to further enable the setting of dynamic secondary cooling (DSC) for steel slabs (105) continuously cast at casting temperatures (TS) exceeding 1000°C. The MLMAT (89) is coupled to a dynamic secondary cooling system (DSCD) that includes a computerized DSC optimization system (DSCM), which generates DSC optimization parameters (PCSC) for dynamic secondary cooling based on dynamic 3D mapping (3DM) that physically observes the continuous casting of the steel slabs (105). This is done on the structural parts (92) of the frame surface (95) by digital analysis of a combination of signals from multiple secondary ultrasonic electrical signals (88a, 88b, 88) in each Laser-EMAT (82a, 82b, 82). Furthermore, it is equipped with a digital DSC activator (ASC) that dynamically adjusts the DSC action parameters (PASC) of the dynamic secondary cooling (DSC) water flow rate based on the PCSC generated by the DSCM. This is done based on dynamic 3D mapping (3DM) physically observed by MLEMAT(89).

[0100] The MLEMAT (89) for automatic adjustment of DSR and DSC of the present invention provides a technical solution to the above technical problem (d). Specifically, it ensures automatic adjustment of the DSR action parameters (PASD) of dynamic soft reduction (DSR) and the DSC action parameters (PASC) of dynamic secondary cooling (DSC) based on the results of observing the interior of a steel slab (105) continuously cast in a steel mill. It continuously supplies a dynamic 3D mapping (3DM) of the interior during the continuous casting of the steel slab (105) while observing it. The position of the central massy zone (semi-solidified area) (106) and its segregation defects in the continuous casting of the molten steel slab (105) are defined based on 3D physical observation using 3D modes and observation methods, and are not provided by numerical simulation predictions using theoretical algorithms based on mathematical models. It is possible to accurately detect the deceleration point of the continuous casting of the steel slab (105) based on three-dimensional physical observation. Furthermore, it is possible to improve the accuracy and reliability of the automatic adjustment of dynamic soft reduction (DSR) and dynamic secondary cooling (DSC) parameters for steel slabs (105) continuously cast at temperatures above 1000°C. This makes it possible to reduce segregation defects and porosity in the central massy zone (106) of the molten steel slab (105) during the continuous casting process at steel mills.

[0101] [Effects of the invention] The MLEMAT(89) for DSR and DSC of the present invention provides valuable industrial advantages in the non-destructive automatic control of continuous casting of hot hardening of steel slabs in the steel industry. a. It can operate even in environments where the casting temperature of the steel slab exceeds 1200°C. b. It is possible to continuously perform 3D mapping of cast steel slabs at a maximum speed of 1 m / s. c. From casting to rolling of steel slabs, NDT can be performed using general equipment without cooling the steel slabs up to 100°C. d. After NDT, it is possible to save gas used to reheat the slab to 1200°C before rolling. e. Provide 3D mappings continuously generated from the continuous casting of steel slabs in order to automatically and dynamically adjust the parameters of the continuous casting equipment. f. The types and coordinates of discontinuous surfaces (internal and surface) in cast steel slabs can be identified continuously with high precision and reliability. g. This makes it possible to improve the accuracy of standardization, quality control, and quality evaluation of the manufactured steel slabs, thereby increasing the added value of continuous casting. h. It is possible to dynamically and precisely adjust the dynamic parameters of DSR and DSC of continuously cast steel slabs in real time. i. Early detection of discontinuities in steel slabs significantly reduces time, energy, materials, and labor, enabling orientation to preceding production processes according to quality. j. Improve the performance and productivity of steel casting machines by more than 7%. k. Due to its compact size, it can be installed without making major structural changes to existing casting equipment.

[0102] [Industrial applicability] This invention has industrial applications in the metallurgical industry, particularly in the steel industry, for quality inspection of hot hardening of steel slabs at temperatures above 1000°C in continuous steel casting lines, automatic adjustment of DSR and DSC, and quality control of semi-finished products in the metallurgical industry. It can also be applied in the railway industry for high-speed control of railway rails and wheelset mounting control. Furthermore, this invention can be applied in the oil and gas industry, chemical industry, and nuclear industry for inline testing of pipes, pipelines, drilling equipment, and machinery in hazardous and high-temperature environments.

[0103] While this specification illustrates and describes only certain features of the present invention, it will be apparent to those skilled in the art that many other variations and modifications are possible. Therefore, it should be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the invention.

Claims

1. An electromagnetic acoustic transducer (EMAT) (1) for detecting surface and internal discontinuities (2) in an electrically conductive material (3) under test, a. At least one magnet (4) or electromagnet configured to generate a static or quasi-static magnetic field (SMF) within the material under test (3), b. At least one high-frequency electric coil (6), wherein the coil is of the following type: i. In either case, when EMAT (1) is used in transmit mode (EM), it is configured as a high-frequency electromagnetic transmitter (9) of a radiated high-frequency electromagnetic field (HFEMF) and is connected to the output of at least one AC current source (11), and a high-frequency alternating current (AC) at an ultrasonic frequency is passed through the high-frequency electric coil (6), - A radiated high-frequency electromagnetic field (HFEMF) is induced in the direction of the material under inspection (3), - Material eddy currents (14) are generated on the surface of the material to be inspected (3), - The interaction between the material eddy current (14) and the static magnetic field (SMF) and / or magnetostriction generates an ultrasonic frequency Lorentz force (15) within the material under inspection (3), - This disturbance directly generates primary ultrasound (17) within the material being examined (3), ii. and / or, when EMAT(1) is used in receiving mode (RM), it is configured as a high-frequency electromagnetic receiver (18), and A secondary ultrasonic electrical signal (88) of ultrasonic frequency passes through the high-frequency electrical coil (6), and the signal is • Generated by radiated radio frequency electromagnetic fields (HFEMF), - Under the influence of the ultrasonic source, secondary ultrasonic waves (21) interact with the static magnetic field (SMF), which induce material eddy currents (14) generated on the surface (8) of the material under inspection (3), c. A perforated matrix stacked magnetic core (22) of the type comprising a sandwich-like matrix (23) configured to direct radiated high-frequency electromagnetic fields (HFEMF) toward the material under test (3), or to concentrate and guide radiated high-frequency electromagnetic fields (HFEMF) coming from the material under test (3), i. It consists of a number of thin plates (24) periodically stacked along the matrix axis (25), the thin plates (24) being positioned between the two main matrix planes (26) of the sandwich-like matrix (23) and parallel to its stacking plane (27), ii. Having a plurality of adjacent side edge surfaces (35) that are substantially perpendicular to the stacking plane (27) and extending perpendicular to the matrix axis (25), - On the other hand, the first side edge surface (36) of the matrix (23) faces the surface (8) of the material to be inspected (3), - The other side, the second side edge surface (37) of the matrix (23) is located substantially opposite to the first side edge surface (36) and faces the high-frequency electric coil (6), iii. Each thin plate (24) of the matrix (23) is - Having a spatial geometry and lateral dimensions similar to adjacent thin plates (24) within the matrix (23), - It has two main surfaces (32) parallel to the stacked plane (27), iv. The combination of the continuous adjacent periphery (33) of each thin plate (24) constitutes the groove-like edge surface (34) of the matrix (23) surrounding the matrix axis (25). v. Define the core axis (38) of the matrix (23), which substantially connects the centers of the first side edge surface (36) and the second side edge surface (37) and is positioned substantially perpendicular to the matrix axis (25). d. The sandwich-like matrix (23) includes at least one first group (28) of high-frequency active laminates (29) or a group thereof, and each laminate is i. They are insulated from each other, ii. An electrically conductive material is incorporated externally, and / or its periphery (33) is covered externally with an electrically conductive layer. iii. Containing a ferromagnetic or ferrimagnetic magnetic material internally, and having a Curie temperature (TC), The electromagnetic acoustic transducer (EMAT) (1) further: a. Equipped with a grooved cylindrical opening (39), i. Along the opening axis (40) of the sandwich-like matrix (23), in a direction substantially parallel to the matrix axis (25) and perpendicular to the core axis (38), the thin plates (24) of the matrix (23) are penetrated. ii. Openings are provided in each of the two main matrix surfaces (26), b. Equipped with multiple magnetic via holes (41), i. Having similar cross-sectional dimensions, ii. Near the center of each high-frequency active laminate (29) of the matrix (23), a hole is drilled along an axis substantially parallel to the surface under inspection (8), iii. It has a longitudinal outer shape (42) of a via hole, the outer shape is arranged along the opening axis (40) of the matrix (23), and its lateral peripheral edge is continuously closed. iv. Aligned to form a grooved cylindrical opening (39), c. The system comprises multiple closed inductive current loops (43), which, when EMAT (1) is in operation, i. Emitted by the radiated high-frequency electromagnetic field (HFEMF) emitted by the high-frequency alternating current (AC) in the high-frequency electric coil (6) at ultrasonic frequencies and / or by the radiated high-frequency electromagnetic field (HFEMF) emitted by the material eddy current (14) in the material under test (3), ii. Located within the active laminate skin (48) at the periphery of each high-frequency active laminate (29) of the perforated matrix laminated magnetic core (22), iii. Arranged according to loop mapping (LM) which defines the topology and relative position of the induced current loop (43), d. Each magnetic via hole (41) of each high-frequency active laminate (29) is located between a first side edge surface (36) facing the surface under inspection (8) and a second side edge surface (37) facing the high-frequency electric coil (6). e. Each magnetic via hole (41) of the grooved cylindrical opening (39) has no hard material inside, and in particular does not contain any electrical conductors passing through it. f. The loop mapping (LM) is topologically discrete and consists of multiple discrete portions of induced current loops (43) of spaced-apart high-frequency active laminates (29) (or a group of such high-frequency active laminates), g. The separated induced current loop (43) is i. Induced into the active laminate skin (48) at the periphery (33) of the high-frequency active laminate (29), ii. Arranged along a loop plane that is parallel to the laminated plane (27) and substantially perpendicular to the surface of the material under inspection (3), iii. They are substantially parallel and spaced apart from each other between each high-frequency active laminate (29). iv. Surrounding the magnetic via hole (41) and rotating around it, h. The core spacing layer (49) of each perforated matrix laminated magnetic core (22), which is located between two adjacent high-frequency active laminates (29) (or groups), has no induced current loops (43) on its surface. As a result, a complex and interactive dual physical effect occurs within the perforated matrix stacked magnetic core (22). a. Multiple parallel and topologically discrete induced current loops (43) of each high-frequency active laminate (29) are, i. Generate high-frequency magnetic fields independently, ii. To separately and locally increase discrete and selective high-frequency magnetic coupling between the narrow local active region (44) of the surface under inspection (8) and the high-frequency electric coil (6), iii. Contributes to the mutual reduction of high-frequency magnetoresistance in EMAT(1), b. The inner circumference (45) of each magnetic via hole (41) is i. A free heat conduction and convection surface (46) is formed in the center of the high-frequency active laminate (29). ii. An internal thermal cooling effect is generated that dissipates a portion of the electrical and thermal energy produced by the induced current loop (43), iii. Contributes to improving the efficiency of EMAT(1), An electromagnetic acoustic transducer (EMAT) (1) characterized by the above.

2. a. Each perforated high-frequency active laminate (29) of the matrix (23) is separated from other adjacent ones at the level of the adjacent core spacing layer (49) by at least one sheet of a second plurality (54) of passive laminates (53) made of an electrical insulating material. b. Each passive laminate (53) is perforated by a spacer via hole (57), c. Each passive laminate (53) is arranged and configured as follows: i. The magnetic via holes (41) of the high-frequency active laminate (29) of the first group (28) of the matrix (23) and the spacer via holes (57) of the passive laminate (53) of the second group (54) of the sandwich-like matrix (23) are ii. Aligned parallel to the matrix axis (25), and by alignment and joining, a grooved cylindrical opening (39) is formed. a. Each spacer via hole (57) of each passive laminate (53) is i. The first side edge surface (36) facing the material to be inspected (3), ii. Located between the second side edge surface (37) facing the high-frequency electric coil (6), b. Each spacer via hole (57) that constitutes the grooved cylindrical opening (39) is i. It does not contain any hard material inside, ii. In particular, not including any electrical conductors that penetrate it, In this way, the inner circumference of each spacer via hole (57) of each passive laminate (53) of the matrix (23) a. A heat conduction and convection surface (46) is formed inside the center of the passive laminate (53). b. An internal thermal cooling effect is generated within the spacer via hole (57), dissipating a portion of the electrical and thermal energy generated by the induced current loop (43) of the adjacent high-frequency active laminate (29), and contributing to an improvement in the efficiency of EMAT (1). The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

3. For at least one passive laminate (53), preferably all passive laminates, a. The peripheral portions (33) of those peripheries are free from any conductive material covering their surfaces. b. As a result, the grooved edge surface (34) of the perforated matrix laminated magnetic core (22) is not continuously covered and / or constituted by a conductive layer, but rather has a configuration in which the edge portions are alternately arranged, consisting on the one hand a conductive ring around the high-frequency active laminate (29) and on the other hand an insulating ring around the passive laminate (53). The electromagnetic acoustic transducer (EMAT) (1) according to feature 2.

4. An electromagnetic acoustic transducer (EMAT) (1) according to claim 1, further comprising the following: a. The device is equipped with a cooling means (58), and the cooling means is i. Generate a cooling flow (59) of the heat transfer fluid (60) at the cooling temperature (TF), ii. The cooling flow (59) is configured to be forced to pass through the grooved cylindrical opening (39) of the matrix (23), The electromagnetic acoustic transducer (EMAT) (1) further: a. The cooling flow (59) is i. It is configured to alternately pass through at least one magnetic via hole (41) of the first group (28) and at least one spacer via hole (57) of the second group (54), ii. Configured to flow across the entire front surface along all hole walls (62) of each consecutive magnetic via hole (41) and / or each spacer via hole (57) of the matrix (23), iii. The matrix (23) is configured to increase the internal thermal cooling effect in each high-frequency active laminate (29), and each laminate is subject to an induced current loop (43) and heat generation. b. The cooling temperature (TF) of the cooling flow (59) is more than 50°C lower than the intrinsic Curie temperature (TC) of the magnetic material of each perforated high-frequency active laminate (29). The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

5. a. At least one (preferably more) thin plates (24) of the perforated matrix laminated magnetic core (22) are i. The annular wall (65) formed between each via hole (41, 57) and the portion of the first side edge surface (36) facing the material under inspection (3) is perforated by a cushion hole (63) penetrating in a direction parallel to the laminated plane (27), or is provided with a cushion notch (64), ii. A cushion recess (66) is formed between the via holes (41, 57) of the thin plate (24) and the first side edge surface (36) facing the material to be inspected (3). b. The cooling means (58) is i. Extract the Cushing fluid flow (67) from the cooling flow (59) flowing through the via holes (41, 57), ii. The extracted cushion fluid flow (67) is flowed under pressure through the cushion recess (66), iii. At the location of the cushion recess (66) facing the material to be inspected (3), a lift air cushion (70) is generated between the perforated matrix laminated magnetic core (22) and the material to be inspected (3). iv. This configuration lifts the perforated matrix laminated magnetic core (22) above the material under inspection (3) via the cushion gap (68). The electromagnetic acoustic transducer (EMAT) (1) according to feature 4.

6. a. The outer sheet surfaces (32) of the two outer thin plates located on the matrix surface (26) are composed of or covered by a conductive coating layer (69) made of an electrically conductive material. b. Via holes having the same cross-sectional dimensions as the magnetic via hole (41) are formed penetrating each of the two conductive coating layers (69), c. The multiple thin plates (24) of the matrix (23) and the two conductive coating layers (69) are positioned relative to each other such that their multiple via holes are continuously aligned to form a grooved cylindrical opening (39). The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

7. a. The periphery of each magnetic via hole (41) in each high-frequency active laminate (29) is rectangular. The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

8. a. The center of each magnetic via hole (41) is substantially located at the center of gravity of each high-frequency active laminate (29), b. The periphery of each magnetic via hole (41) is substantially located at a constant ring distance (Rd) from the periphery of each high-frequency active laminate (29). c. Thus, each high-frequency active laminate (29) is topologically configured as a rectangular active ring (71) that is thermodynamically cooled from the heating of the induced current loop (43) generated around it. The electromagnetic acoustic transducer (EMAT) (1) according to feature 7.

9. a. The second side edge surface (37) of the perforated matrix laminated magnetic core (22) is directly opposite the high-frequency electric coil (6), b. No magnet is placed between the second side edge surface (37) of the matrix (23) and the high-frequency electric coil (6). The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

10. a. The orientation, pitch, size, and shape of each circuit-facing edge (72) of each high-frequency active laminate (29), which is located on the second side edge surface (37) of the matrix (23) and faces the high-frequency electric coil (6), b. The geometric parameters, including orientation, pitch, size, and shape, of the conductor portion (75) of the high-frequency electric coil (6) that sequentially faces each of the circuit opposing edges (72) are consistent with and correlate with each other. The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

11. a. The high-frequency electric coil (6) has at least one linear conductor portion (73), b. The linear conductor portion (73) is It is located on the second side edge surface (37) of the matrix (23) and is positioned near and directly above the circuit-facing edge (72) of the high-frequency active laminate (29) that faces the high-frequency electric coil (6), Furthermore, it is arranged along an axis parallel to the peripheral edge of the high-frequency active laminate (29) so as to be in contact with the circuit-facing edge (72), This electromagnetic acoustic transducer (EMAT) (1) is characterized in the following combinations: The linear conductor portion (73) and the perforated matrix laminated magnetic core (22) are such that when EMAT (1) is in operation, the induced current loop (43) a. Induced into the active laminate skin (48) at the periphery of the high-frequency active laminate (29), b. Surrounding the magnetic via hole (41), c. This is configured to form a localized and selective high-frequency magnetic coupling between the following: i. A high-frequency alternating current (AC) driven within the linear conductor portion (73) extending along and on the periphery of the high-frequency active laminate (29), and ii. Material eddy currents (14) generated in the local active region (44) of the surface (8) to be inspected facing the high-frequency active laminate (29), Forms a high-frequency magnetic coupling between them. The electromagnetic acoustic transducer (EMAT) (1) according to claim 10.

12. a. The high-frequency electric coil (6) is of a type having multiple linear conductor portions, each consisting of at least two linear conductor portions (73), which are parallel and adjacent to each other, and are, for example, like a meander circuit (74). b. The plurality of parallel linear conductor portions (73) are, i. Located on the second side edge surface (37) of the matrix (23) and facing the high-frequency electric coil (6), sequentially arranged near the circuit-facing edge portion (72) of the high-frequency active laminate (29), and positioned directly above it, ii. The high-frequency alternating current (AC) flowing sequentially from the parallel and adjacent linear conductor portions (73) is configured to be directed alternately in opposite directions. c. At least one conductive high-frequency flux loop (76) substantially perpendicularly surrounds each linear conductor portion (73) and substantially perpendicularly penetrates into the interior of the opposing high-frequency active laminate (29), This electromagnetic acoustic transducer (EMAT) (1) is characterized in that the linear conductor portion (73) of the high-frequency electric coil (6) and the perforated matrix laminated magnetic core (22) are such that when the EMAT (1) is in transmit mode (EM), a. Two adjacent high-frequency active laminates (29) each having two adjacent linear conductor portions (73) positioned above each other, b. Within each active laminate skin (48), two adjacent induced current loops (43) pass through each of these induced current loops (43), each of which consists of a high-frequency alternating current rotating in opposite directions (78) around an opening axis (40) passing through each magnetic via hole (41), one clockwise and the other counterclockwise. The electromagnetic acoustic transducer (EMAT) (1) according to feature 11.

13. a. The opening depth (Od) of the grooved cylindrical opening (39) of the perforated matrix laminated magnetic core (22), along the opening axis (40), is b. The first cross-sectional dimension (FTd) of at least one high-frequency electric coil (6) of EMAT (1) is substantially equal to and coincides with the first cross-sectional dimension (FTd) of EMAT (1). The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

14. a. The grooved second side edge surface (37) of the perforated matrix laminated magnetic core (22) that faces the high-frequency electric coil (6) is: b. The transverse dimension of the matrix (23) in the direction perpendicular to the aperture axis (40) is substantially equal to and coincides with the second transverse dimension (STd) of at least one high-frequency electric coil (6) of the EMAT (1). The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

15. The sheet geometric dimensions of the perforated thin plate (24) of the perforated matrix laminated magnetic core (22) and / or the overall geometric dimensions of the perforated matrix laminated magnetic core (22) are: a. Decorrelate from the wavelengths of the main harmonics of the radiated radio frequency electromagnetic field (HFEMF), b. To prevent mechanical resonance of the perforated matrix laminated magnetic core (22) at the operating ultrasonic frequency of EMAT (1), Selected, The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

16. The sheet geometric dimensions of the perforated thin plate (24) of the perforated matrix laminated magnetic core (22) are, at the operating ultrasonic frequency of EMAT (1), a. The wavelength is smaller than the wavelength of the ultrasound generated within the thin plate (24), or b. Substantially equal to an odd multiple of one-quarter of the wavelength of the ultrasound generated within the thin plate (24), The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

17. An electromagnetic acoustic transducer (EMAT) (1) of which a grooved first side edge surface (36) of a perforated matrix laminated magnetic core (22) facing the material under test (3) and parallel to the grooved cylindrical opening (39) is covered or coated with an insulating layer (81) made of an electrical insulating material, One side of the insulating layer (81) is a. Arranged to face the grooved cylindrical opening (39), b. The edge portion belonging to the first side edge surface (36) covers the periphery of each perforated high-frequency active laminate (29), The electromagnetic acoustic transducer (EMAT) (1) according to feature 1.

18. A laser EMAT probe (LEMAT) (82) for inspecting a conductive material (3) by receiving an ultrasonic signal from the material (3) to be inspected, comprising the following combination: a. An electromagnetic acoustic transducer (EMAT) (1) according to any one of claims 1 to 17, i. Configured in receiving mode (RM) to receive ultrasonic signals from the material under inspection (3), ii. The high-frequency electric coil (6) is configured as a high-frequency electromagnetic receiver (18), - The high-frequency electric coil (6) is induced by the radiated high-frequency electromagnetic field (HFEMF) emitted from the material under inspection (3), Furthermore, it is generated by material eddy currents (14) generated within the material under inspection (3) by secondary ultrasonic waves (21) representing discontinuities (2) on the surface and / or inside the material under inspection (3), iii. The perforated matrix stacked magnetic core (22) is, - It is located between the high-frequency electric coil (6) and the local surface of the material under inspection (3), and - it is directly opposite the high-frequency electric coil (6), b. Laser source (84), i. A high-energy laser beam (85) is irradiated at the firing point (86) on the surface of the material to be inspected (3), ii. Generate ultrasound that produces primary ultrasound (17) that propagates through the surface and / or interior of the material to be inspected (3), iii. The primary ultrasound (17) is generated by reflection when it interacts with the surface and / or internal discontinuities (2) of the material under inspection (3), causing secondary ultrasound (21) to propagate through the surface and / or interior of the material under inspection (3). iv. Under the action of a static magnetic field (SMF) radiated by the magnet (4) of EMAT (1), the mechanical vibration of secondary ultrasonic waves (21) induces the generation of material eddy currents (14) on the surface of the material under inspection (3), v. It is configured to induce a radiated high-frequency electromagnetic field (HFEMF) that is emitted by material eddy currents (14) present on the surface of the material under inspection (3) and represents the shape and location of the discontinuities (2) on the surface and inside the material under inspection (3), The laser EMAT probe (LEMAT) (82) is characterized by the following: a. Multiple parallel and spaced-apart induced current loops (43), i. Under the action of the laser source (84), the radiated high-frequency electromagnetic field (HFEMF) emitted by the material eddy currents (14) generated at ultrasonic frequencies in the material under inspection (3) is used to detect the following: ii. The perforated matrix stacked magnetic core (22) includes those that are guided into the active stacked skin (48) at the periphery (33) of each high-frequency active stack (29), b. These induced current loops (43) of each high-frequency active laminate (29) are i. They are arranged spaced apart from each other, ii. They are arranged along loop planes that are parallel to the stacking plane (27) and substantially perpendicular to the surface of the material under inspection (3), iii. Surrounding the magnetic via holes (41) of each high-frequency active laminate (29), and rotating around them, iv. Located between the first side edge surface (36) facing the material under inspection (3) and the second side edge surface (37) facing the high-frequency electric coil (6), v. It is positioned substantially perpendicular to the two side edge surfaces (36, 37), As a result, a complex and interactive dual physical effect occurs within the perforated matrix stacked magnetic core (22). a. Multiple parallel and topologically discrete induced current loops (43) of each high-frequency active laminate (29) are, i. Generate high-frequency magnetic fields independently, ii. Independently, locally, and discretely, the high-frequency magnetic coupling between the narrow local active region (44) of the surface under inspection (8) facing the high-frequency active laminate (29) and the high-frequency electric coil (6) is increased. iii. By homogenizing and reciprocating high-frequency coupling, it contributes to the overall reduction of high-frequency magnetoresistance and also contributes to improving the resolution of EMAT(1). b. The inner circumference (45) of each magnetic via hole (41) in each high-frequency active laminate (29) of the matrix (23) is: i. A free heat conduction and convection surface (46) is formed in the center of the high-frequency active laminate (29), ii. An internal thermal cooling effect is generated that dissipates a portion of the local electrical and thermal energy generated by the inductive current loop (43) inherent to the high-frequency active laminate (29), iii. Contributes to improving the efficiency of EMAT(1), A laser EMAT probe (LEMAT) (82) characterized by the above.

19. A multi-laser EMAT three-dimensional scanner (MLEMAT) (89) for detecting the surface and / or internal discontinuities (2) of a movable cylindrical conductive structure (90), a. A conductive structure (90) that is scanned in three dimensions, i. The test material (3) consists of an electrically conductive material, ii. Having a cylindrical structure formed along the structural axis (91), iii. Having a substantially constant structural cross-section (92), b. Chassis frame (93), i. It is configured to surround the conductive structure (90) at a frame distance (Fd), ii. The frame plane (95) is substantially perpendicular to the structural axis (91) of the conductive structure (90), c. A group of probes (96) comprising at least two laser EMAT probes (LEMAT) (82) as described in claim 18, wherein each laser EMAT probe (LEMAT) (82) is i. Fixed to the chassis frame (93), ii. The first side edge surface (36) of each perforated matrix stacked magnetic core (22) is positioned to face the conductive structure (90), d. Displacement means (97), i. The cylindrical conductive structure (90) is positioned relative to the chassis frame (93). ii. A device configured to move linearly along a displacement direction (Md) that substantially coincides with the structural axis (91), The aforementioned multi-laser EMAT three-dimensional scanner (MLEMAT) (89) further, a. Open loop (99), i. The laser EMAT probe (LEMAT) (82) of MLEMAT (89) is formed by imaginary lines connecting the centers of each consecutive grooved cylindrical opening (39) of each adjacent EMAT (1) perforated matrix stacked magnetic core (22), ii. Surrounding the conductive structure (90), A multi-laser EMAT three-dimensional scanner (MLEMAT) (89) characterized by being equipped with the above.

20. The probe group (96) of the multi-laser EMAT three-dimensional scanner (MLEMAT) (89), consisting of laser EMAT probes (LEMAT) (82), is mounted and arranged on the chassis frame (93) and configured to have the following positional relationship: a. The juxtaposition of multiple first side edge surfaces (36) of the perforated matrix stacked magnetic cores (22) of adjacent laser EMAT probes (LEMAT) (82) facing the material under inspection (3) is such that they are substantially adjacent to each other. b. In the structural cross-section (92) of the conductive structure (90) adjacent to the frame plane (95), a substantially continuous grooved inspection ring (100) is formed that surrounds and covers the periphery of the conductive structure (90). The multi-laser EMAT three-dimensional scanner (MLEMAT) according to feature 19 (89).

21. a. The laser source (84) of each laser EMAT probe (LEMAT) (82) is fixed to the frame plane (95) and consists of an optical fiber (101) having a firing end (102) facing the conductive structure (90). b. Each optical fiber (101) is connected to a laser generator (103), The aforementioned multi-laser EMAT three-dimensional scanner (MLEMAT) (89) further, a. A laser emission loop (104) comprising imaginary lines connecting the emission ends (102) of each adjacent laser EMAT probe (LEMAT) (82) of the MLEMAT (89), b. Surrounding the conductive structure (90) and substantially parallel to the opening loop (99), The multi-laser EMAT three-dimensional scanner (MLEMAT) according to feature 19 (89).

22. This is for detecting discontinuities (2) on the surface and / or inside of a metallurgical slab (105), a. The conductive structure (90) is a cylindrical metallurgical slab (105) that is movable relative to the MLEMAT (89), The aforementioned multi-laser EMAT three-dimensional scanner (MLEMAT) (89) further, a. An aperture loop (99) is formed by imaginary lines connecting the centers of each continuous grooved cylindrical aperture (39) of each adjacent perforated matrix stacked magnetic core (22) of the MLEMAT (1) laser EMAT probe (LEMAT) (82) of the MLEMAT (89), and surrounds the movable cylindrical metallurgical slab (105). The multi-laser EMAT three-dimensional scanner (MLEMAT) according to feature 19 (89).

23. This is for detecting discontinuities (2) on the surface and / or inside of a steel slab (105), a. The conductive structure (90) is a movable cylindrical steel slab (105) cast slab that is continuously cast at a casting temperature (TS) exceeding 1000°C in a steel manufacturing plant. b. The perforated high-frequency active laminate (29) of each perforated matrix laminated magnetic core (22) of each adjacent EMAT (1) of the MLEMAT (89) is made of, for example, a ferromagnetic or ferrimagnetic type of magnetic material and has a Curie temperature (TC) lower than the casting temperature (TS), The aforementioned multi-laser EMAT three-dimensional scanner (MLEMAT) (89) further, Each grooved cylindrical opening (39) of each perforated matrix stacked magnetic core (22) of each adjacent EMAT (1) is connected to a cooling means (58) that generates a cooling flow (59) of a heat transfer fluid (60). a. The cooling flow (59) is pushed under pressure into each via hole (41, 57) of each grooved cylindrical opening (39). b. The cooling flow (59) has a cooling temperature (TF) that is more than 50°C lower than the Curie temperature (TC) of the magnetic material of the perforated high-frequency active laminate (29). The multi-laser EMAT three-dimensional scanner (MLEMAT) according to feature 22 (89).

24. This system is for automatically adjusting the dynamic parameters of the dynamic soft reduction (DSR) of cast steel slabs (105) that are continuously cast at casting temperatures (TS) exceeding 1000°C in a steel manufacturing plant. a. The cast slab of the steel slab (105) is continuously passed through a dynamic soft reduction device (DSRD) in order to dynamically compensate for the solidification shrinkage of the steel and to block the suction flow rate of residual molten metal in the central massy zone (106), thereby suppressing the formation of macrosegregation regions and porosity regions within the cast slab of the steel slab (105). b. The MLEMAT (89) is coupled to the Dynamic Soft Reduction Device (DSRD), which is, i. A dynamic three-dimensional mapping system (3DMS) for generating dynamic three-dimensional mapping (3DM) of a cast steel slab (105), ii. A computerized DSR optimization system (DSRM) that generates dynamic DSR optimization parameters (PCSD) based on the dynamic three-dimensional mapping (3DM) and casting parameters, c. The digital DSR actuator (ASR) dynamically adjusts the DSR operating parameters (PASD) of the dynamic soft reduction device (DSRD) based on the PCSD generated by the DSRM. The aforementioned multi-laser EMAT three-dimensional scanner (MLEMAT) (89) further, a. The high-frequency electric coils (6a, 6b, 6) of each laser EMAT (82a, 82b, 82) of the MLEMAT (89) are each connected to a dynamic three-dimensional mapping system (3DMS), and the secondary ultrasonic electrical signals (88a, 88b, 88) induced in each high-frequency electric coil (6a, 6b, 6) by material eddy currents (14) in the front region (110) of the material under inspection (3) of the steel slab (105) locally facing each EMAT (1a, 1b, 1) are transmitted to the system. b. The DSR optimization system (DSRM) comprises analog and digital processing means (MDAN), and said means are i. Receive the multiple secondary ultrasonic electrical signals (88a, 88b, 88) contained in the secondary ultrasonic current (19a, 19b, 19) passing through each high-frequency electric coil (6a, 6b, 6) of each laser EMAT (82a, 82b, 82) of MLEMAT (89), ii. The changes and perturbations of each secondary ultrasonic electrical signal (88a, 88b, 88) caused by discontinuities (2) in the local active regions (44a, 44b, 44) of the material under inspection (3) facing each laser EMAT (82a, 82b, 82) are identified, and the defect front topology (DTa, DTb, DT) in the local active region (44a, 44b, 44) is digitally derived and generated from there. iii. The defect front topology (DTa, DTb, DT) is digitally combined, and based on the combination of combined signals of multiple secondary ultrasonic electrical signals (88a, 88b, 88) and digital analysis, a three-dimensional dynamic three-dimensional mapping (3DM) of the inside of the cast steel slab (105) in the front region (110) facing the inspection ring (100) in the structural cross section (92) of the frame plane (95) is digitally generated as physically observed by MLEMAT (89). c. The cooling means (58) generates a cooling flow (59) of the heat transfer fluid (60), and the cooling flow (59) i. Each of the adjacent EMATs (1a, 1b, 1) of the MLEMAT (89) is pushed under pressure into each via hole (41, 57) of each grooved cylindrical opening (39) of each perforated matrix stacked magnetic core (22), ii. The cooling temperature (TF) is at least 50°C lower than the Curie temperature (TC) of the magnetic material of the perforated high-frequency active laminate (29), d. This allows the DSR operating parameters (PASD) of the dynamic soft reduction device (DSRD) to be optimally and automatically adjusted based on the dynamic three-dimensional mapping (3DM) of the steel slab (105) cast slab, which is physically observed by MLEMAT (89) under conditions where the casting temperature (TS) exceeds 1000°C. The multi-laser EMAT three-dimensional scanner (MLEMAT) according to the feature described in 23 (89).

25. This system enables automatic adjustment of the dynamic parameters of the dynamic soft reduction (DSR) of cast steel slabs (105) continuously cast at casting temperatures (TS) exceeding 1000°C in a steel manufacturing plant, and further enables the setting and startup of dynamic secondary cooling (DSC). The MLEMAT (89) is coupled to a dynamic secondary cooling system (DSCD), and the system further... a. A computerized DSC optimization system (DSCM) configured to generate dynamic DSC optimization parameters (PCSC), wherein the PCSC is i. For the cast steel slab (105) in the structural cross section (92) of the frame plane (95), based on the combination of coupled signals of multiple secondary ultrasonic electrical signals (88a, 88b, 88) from each laser EMAT (82a, 82b, 82) of MLEMAT (89) and digital analysis, a dynamic three-dimensional mapping (3DM) physically observed by MLEMAT (89) is performed. ii. It is produced based on the casting parameters, b. A digital DSC actuator (ASC) configured to dynamically adjust the DSC operating parameters (PASC) related to the water flow rate of the dynamic secondary cooling (DSC) based on the PCSC generated by the DSC optimization system (DSCM) and based on the dynamic three-dimensional mapping (3DM) physically observed by MLEMAT (89). The multi-laser EMAT three-dimensional scanner (MLEMAT) according to the feature described in 24 (89).

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