Acoustic testing system and method for metal pitting process

Abstract

The present invention discloses an acoustic testing system and method for metal pitting corrosion, comprising: a corrosion environment simulation device for providing the corrosion environment required for testing; a stress environment simulation device for providing an internal stress environment under a first type of temperature condition to a test piece during testing; an acoustic emission detection device and an image acquisition device for respectively collecting acoustic emission signals and test images representing the changing state of the test piece's pitting corrosion process during testing; and an information processing device for synchronously acquiring the acoustic emission signals and test images. Based on these signals, information integration and analysis are performed on the pitting corrosion change process of the test piece under the combined conditions of different temperatures, different corrosion intensities, and different stress environments to obtain corresponding analysis results. The system of the present invention can simultaneously observe the influence mechanism of different temperatures, different pitting pit shapes, different stress magnitudes, and different corrosion intensities on the pitting corrosion damage of the test piece, providing a basis for material selection and real-time detection of high-temperature special equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of non-destructive monitoring, and in particular to a metal pitting process acoustic testing system and method. Background Art

[0002] With the rapid development of my country's industrial technology, more and more mechanical equipment has been put into use, leading to an increasing focus on the mechanical properties of the materials used to manufacture these equipment. This is particularly true in fields such as metallurgy, aerospace, special equipment, and petrochemicals, which place higher demands on materials' mechanical properties, such as hardness, ultimate strength, and elastic modulus, in high-temperature environments. Therefore, studying the mechanical properties of various materials in high-temperature environments not only helps to test the safety performance of special equipment in such environments but also provides a basis for the development and use of new materials.

[0003] Pitting corrosion, also known as small hole corrosion, is a form of pitting corrosion in which corrosion is concentrated in a small area on the metal surface and penetrates deep into the metal, even perforating it. Metals with self-passivating characteristics, such as stainless steel, aluminum, and aluminum alloys, often experience pitting corrosion in media containing chloride ions. Carbon steel can also experience pitting corrosion in many media containing chlorine atoms. In industrial production, pitting corrosion is a very harmful type of corrosion. Because the pitting process is very hidden, it is usually difficult to monitor the pitting phenomenon in advance. Once the metal is perforated, it will have a serious impact on the equipment and the production process. Acoustic emission detection technology can monitor the acoustic signals emitted by the equipment in real time. If the acoustic signals generated during the pitting process of the metal can be identified, the pitted areas of the metal can be treated in time to prevent the continued expansion of pitting corrosion, which may lead to equipment damage or more serious accidents.

[0004] Digital image correlation (DIC) utilizes binocular stereo vision technology to track speckle patterns on an object's surface, enabling the measurement of its three-dimensional coordinates, displacement, and strain during deformation. It is primarily used to measure and acquire full-field strain, deformation, displacement, amplitude, and modal information. Acoustic emission (AE) is a dynamic detection method that uses sensors to detect changes in the material, such as crack initiation and propagation, fracture, diffusionless phase transitions, and applied loads, by receiving elastic waves generated within the material.

[0005] The above two methods can only observe speckle or crack propagation from a single level, but the existing technology lacks a damage monitoring system that can integrate complex environments to provide a certain basis for material selection and damage detection of high-temperature special equipment. Summary of the Invention

[0006] In order to solve the above technical problems, an embodiment of the present invention provides an acoustic testing system for a metal pitting corrosion process, comprising: a corrosion environment simulation device for providing the corrosion environment required for the test; a stress environment simulation device for providing an internal stress environment under a first type of temperature condition to the test piece during the test; an acoustic emission detection device and an image acquisition device for respectively collecting acoustic emission signals and test images representing the changing state of the pitting corrosion process of the test piece during the test; and an information processing device for synchronously acquiring the acoustic emission signals and test images. Based on this, an information integration analysis is performed on the pitting corrosion change process of the test piece under the combination of different temperatures, different corrosion intensities and different stress environments to obtain corresponding analysis results.

[0007] Preferably, the stress environment simulation device includes: a stress loading module, which is used to fix the specimen and apply the stress required for the test to both ends of the specimen, wherein the specimen is constructed as a cylindrical structure, and a plurality of grooves are provided on the side walls of the middle section of the specimen; a temperature loading module, which is used to heat the two ends of the middle section of the specimen to provide the temperature conditions required for the test to the middle section of the specimen.

[0008] Preferably, the temperature loading module includes: a first group of coils and a second group of coils respectively fixed at both ends of the middle position of the specimen; a heater, which is connected to the first group of coils and the second group of coils and is used to energize the two groups of coils so as to utilize the principle of electromagnetic induction to enable the two groups of coils to heat the corresponding positions of the specimen.

[0009] Preferably, the stress loading module includes: an in-situ stretching machine, which is used to load the test stress on the specimen that matches the stress environment conditions inside the specimen required for the test; a first stretching clamp and a second stretching clamp respectively arranged at both ends of the in-situ stretching machine, and the first stretching clamp and the second stretching clamp are used to clamp the two end faces of the specimen to fix the specimen.

[0010] Preferably, the corrosion environment simulation device includes: a corrosion solution pool, a pair of first-type through holes arranged opposite to each other are constructed on the side walls of which, and the specimen passes through the first-type through holes so that the middle section of the specimen is located inside the corrosion solution pool, and the corrosion solution pool is used to hold the corrosion solution; an auxiliary electrode and a reference electrode are respectively inserted into the corrosion solution; an electrochemical workstation electrically connected to the auxiliary electrode, the reference electrode, and the specimen, and is used to provide the corrosion intensity conditions required for the test to the middle section of the specimen by outputting currents of different potentials.

[0011] Preferably, the upper half of the corrosion solution pool is constructed as a rectangular parallelepiped structure, and the lower half of the corrosion solution pool is constructed as an arc-shaped bottom structure, the upper half is connected to the lower half, and the top of the corrosion solution pool is sealed, wherein two second-type through holes are provided on the top of the corrosion solution pool, and the two second-type through holes are used to insert the auxiliary electrode and the reference electrode respectively, the shape of the first-type through hole matches the cross-sectional shape of the specimen, and the gap between the first-type through hole and the specimen is sealed using a pan seal.

[0012] Preferably, the acoustic emission detection device includes: acoustic emission sensors respectively arranged on the side walls at both ends of the specimen, for collecting the acoustic emission signals, the acoustic emission sensors being coupled to the specimen using a coupling agent, and the temperature resistance of the coupling agent meeting the first type of temperature conditions; amplifiers respectively arranged at the rear ends of the acoustic emission sensors, for amplifying the received acoustic emission signals and transmitting the processed signals to an acoustic emission detector; the acoustic emission detector is used to analyze the acoustic emission signals and store the analysis results.

[0013] Preferably, the system also includes an image acquisition device, which comprises: a plurality of industrial cameras, which are respectively arranged at different radial positions in the middle position of the specimen, and are used to collect the test image containing the change state information of the pitting pits on the side wall of the specimen at the corresponding position in real time during the test process, so as to obtain the microscopic morphology information and / or bubble generation information of the corresponding pitting pits during the corrosion process; a main control computer, which is connected to the plurality of industrial cameras, and is used to acquire the test images at different positions, perform feature extraction processing on the test images, and based on this, mark the pitting pit expansion features and bubble generation features, so as to send the test image containing the pitting feature information to the information processing device.

[0014] Preferably, when the cross-section of the specimen is rectangular, grooves of different shapes are respectively provided on the side walls in different directions at the middle section of the specimen, and the shapes include square, circle, triangle and ellipse.

[0015] On the other hand, an embodiment of the present invention also provides an acoustic testing method for a metal pitting corrosion process, which is implemented using the system described above. The method includes: constructing the corrosion environment required for the current test and the internal stress environment that meets the first type of temperature conditions; after starting the test, respectively collecting acoustic emission signals and test images that characterize the changing state of the pitting corrosion process of the specimen; synchronously acquiring the acoustic emission signals and test images, and based on this, performing information integration analysis on the pitting corrosion change process of the specimen under the combined conditions of different temperatures, different corrosion intensities, and different stress environments to obtain corresponding analysis results.

[0016] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0017] The present invention proposes a metal pitting process acoustic testing system and method. The system and method can synchronously detect multiple information such as the stress size, image, and acoustic emission signal at the pitting pit during the initiation and expansion of pitting damage of the specimen material under high temperature stress conditions. By combining the multivariate signals of the entire process of pitting damage of the material, it can effectively simulate the external crack initiation and internal damage mechanism of the specimen material under stress tension under pitting conditions when the system is running in a high temperature environment. At the same time, the connection between the acoustic emission signal and the internal damage is obtained, and the evolution law (damage mechanism) of pitting damage when the material is under tensile stress in a high temperature environment is fully understood. This lays a theoretical foundation for pitting damage monitoring and early warning during the operation of the system, and provides a method basis for material selection and real-time detection of high-temperature special equipment. At the same time, the system can simultaneously observe the influence mechanism of different temperatures, different pitting pit shapes, different stress sizes, and different corrosion intensities on the pitting damage of the specimen. In addition, the present invention also has the characteristics of simple structure, flexible operation, flexible temperature setting, and on-the-go stop. It can be widely used in the study of pitting expansion behavior of metal materials under different temperatures, different loads, different pitting pit shapes, and different corrosion intensities.

[0018] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purposes and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 This is an overall block diagram of the acoustic testing system for the metal pitting corrosion process according to an embodiment of the present application.

[0021] Figure 2 This is a detailed structural diagram of the acoustic testing system for the metal pitting corrosion process according to an embodiment of the present application.

[0022] Figure 3 This is a schematic diagram of the local structure at the middle section of the specimen in the acoustic testing system for the metal pitting corrosion process according to an embodiment of the present application.

[0023] Figure 4 This is a schematic diagram of an example of the effect of the pitting pit shape in the acoustic testing system for the metal pitting process in an embodiment of the present application.

[0024] Figure 5 This is a step diagram of the acoustic testing method for metal pitting corrosion process according to an embodiment of the present application. DETAILED DESCRIPTION

[0025] The following describes the embodiments of the present invention in detail with reference to the accompanying drawings and examples, so that the present invention can fully understand how to apply technical means to solve technical problems and achieve technical effects, and thus implement the invention accordingly. It should be noted that, as long as no conflict exists, the various embodiments of the present invention and the various features of the embodiments can be combined with each other, and the resulting technical solutions are all within the scope of protection of the present invention.

[0026] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions. Also, although a logical order is shown in the flowchart, in some cases, the steps shown or described can be performed in a different order than here.

[0027] With the rapid development of my country's industrial technology, more and more mechanical equipment has been put into use, leading to an increasing focus on the mechanical properties of the materials used to manufacture these equipment. This is particularly true in fields such as metallurgy, aerospace, special equipment, and petrochemicals, which place higher demands on materials' mechanical properties, such as hardness, ultimate strength, and elastic modulus, in high-temperature environments. Therefore, studying the mechanical properties of various materials in high-temperature environments not only helps to test the safety performance of special equipment in such environments but also provides a basis for the development and use of new materials.

[0028] Pitting corrosion, also known as small hole corrosion, is a form of pitting corrosion in which corrosion is concentrated in a small area on the metal surface and penetrates deep into the metal, even causing perforation. Metals with self-passivating characteristics, such as stainless steel, aluminum, and aluminum alloys, often experience pitting corrosion in media containing chloride ions. Carbon steel also experiences pitting corrosion in many media containing chlorine atoms. In industrial production, pitting corrosion is a very harmful type of corrosion. Because the pitting process is very hidden, it is usually difficult to detect pitting in advance. Once perforation occurs in the metal, it will have a serious impact on the equipment and the production process. Acoustic emission detection technology can monitor the acoustic signals emitted by running equipment in real time. If the acoustic signals generated during the pitting process of metal can be identified, the pitted areas of the metal can be treated in a timely manner to prevent the continued expansion of pitting corrosion, which may lead to equipment damage or more serious accidents.

[0029] Digital image correlation (DIC) technology uses binocular stereo vision technology to track the speckle image on the surface of an object to measure the three-dimensional coordinates, displacement, and strain of the object's surface during deformation. It is mainly used to measure and obtain full-field strain, deformation, displacement, amplitude, modality, and other information. Acoustic emission (AE) technology is a dynamic detection method that uses sensors to receive elastic waves generated inside the material to detect changes in the material such as crack initiation and propagation, fracture, diffusionless phase transition, and applied load. The above two methods can only observe speckle or crack propagation from a single level, but the existing technology lacks a damage monitoring instrument that can integrate complex environments to provide a certain basis for material selection and damage detection of high-temperature special equipment.

[0030] In order to solve the above technical problems, the present invention provides an acoustic testing system for metal pitting corrosion process under multi-field coupling based on in-situ visualization. The system includes: a corrosion environment simulation device, a stress environment simulation device, an acoustic emission detection device, an image acquisition device and an information processing device, etc. It can combine digital image correlation and acoustic emission technology to simultaneously monitor the damage evolution process of the test piece material from both image and acoustic aspects, thereby collecting pitting acoustic emission signal samples generated by the material under the simultaneous action of high temperature stress. It can describe the pitting damage changes of the material from a data level with basis, which is conducive to understanding the pitting initiation and expansion process of the material under stress in a high temperature environment, and provide a basis for material selection and damage detection of high-temperature special equipment.

[0031] In addition, since acoustic emission technology is mainly used to monitor the equipment under test in operation, the present invention mainly simulates the metal pitting corrosion of the test piece material in operation (in use), more realistically simulates the environmental conditions in which the metal material is located, and more effectively obtains the acoustic emission signal, thereby extracting images and acoustic features, providing a basis for on-site monitoring and identification of metal pitting corrosion.

[0032] Example 1

[0033] Figure 1 FIG. 1 is an overall block diagram of the acoustic testing system for the metal pitting process according to an embodiment of the present application. Figure 1 As shown, the metal pitting process acoustic testing system of the present invention comprises at least: a corrosion environment simulation device A, a stress environment simulation device B, an acoustic emission detection device C, an image acquisition device D and an information processing device E.

[0034] Specifically, the corrosion environment simulation device A is used to provide the corrosion environment required for the test. That is to say, after the acoustic test of the pitting process is implemented, the corrosion environment simulation device A is used to simulate the corrosion environment conditions required for the current test, so as to ensure that the pitting pits in the specimen material (tested material) have a certain corrosion intensity. The stress environment simulation device B is used to provide the specimen with an internal stress environment under the first type of temperature conditions during the test. In actual application, due to the internal stress of the specimen material, the specimen macroscopically exhibits a certain strength to resist the actual environmental conditions in which the specimen is located. Therefore, the present invention will use the stress environment simulation device B to first simulate the internal stress environment of the specimen during use, and secondly, it is also necessary to simulate the high temperature environment in which the specimen material is located. In an embodiment of the present invention, the first type of temperature environment conditions refers to the actual high temperature environment in which the specimen material is applied. It should be noted that the embodiment of the present invention does not specifically limit the numerical range of the first type of temperature environment conditions. Those skilled in the art can set it according to the temperature range of the actual application environment scenario of the specimen material (for example: it can be set to 0-100°C, or it can be set to 100-200°C, or it can be set to 400-500°C).

[0035] In this way, the present invention utilizes the stress environment simulation device B to couple the stress environment and temperature environment of the specimen to simulate the specimen, which is helpful for understanding the changing state of the pitting corrosion process of the specimen material under high temperature stress conditions.

[0036] The present invention utilizes the above-mentioned corrosion environment simulation device A and stress environment simulation device B to provide relevant devices for simulating the actual environmental conditions (corrosion conditions and high-temperature stress conditions) applied to the specimen for the current test, thereby completing the construction of the application environment required for the current test.

[0037] Furthermore, the acoustic emission detection device C is used to collect acoustic emission signals that characterize the changing state of the pitting process of the specimen during the test. The image acquisition device D is used to collect test images that characterize the changing state of the pitting process of the specimen during the test. During the test implementation process, the present invention will use the acoustic emission detection device C and the image acquisition device D to simultaneously collect acoustic emission signals and test images for the pitting change process of the pitting pits in the specimen in use. That is to say, during the test implementation process, it is necessary not only to obtain acoustic emission signals, but also to collect corresponding (frame) test images at each data acquisition moment, so as to use the acoustic emission signals and multiple frames of test images obtained during the entire test process to characterize the changing state of each pitting pit in the specimen during the pitting process.

[0038] Furthermore, the information processing device E is used to synchronously acquire acoustic emission signals and test images. Based on this, it performs an integrated analysis of the pitting corrosion process of the specimen under different combinations of temperatures, corrosion intensities, and stress environments to obtain corresponding analysis results. In this embodiment of the present invention, the information processing device E employs a computer device capable of integrating and analyzing the acoustic emission signals and multiple frames of test images transmitted from the acoustic emission detection device C and the image acquisition device D, thereby obtaining corresponding integrated analysis results. These integrated analysis results include, but are not limited to, information such as specimen stress, pit expansion, bubble generation, membrane rupture, and temperature changes.

[0039] Therefore, the metal pitting process acoustic testing system described in the present invention can realize the combination of stress magnitude, images, acoustic emission signals, high temperature and pitting data, so as to study the influence of different corrosion intensities of the specimen material on the initiation and expansion of pitting damage under high temperature stress conditions. At the same time, the images of processes such as bubble generation, film rupture, and pit expansion in the pitting process are combined with the acoustic emission signals to gain an in-depth understanding of the effect of stress on pitting damage under different temperatures and different corrosion intensities.

[0040] Example 2

[0041] Figure 2 This is a specific structural diagram of the acoustic testing system for metal pitting process according to the embodiment of the present application. Figure 1 and Figure 2 The structure and function of each device in the acoustic testing system for metal pitting corrosion process described in the present invention are described.

[0042] like Figure 1 As shown, the stress environment simulation device B includes: a stress loading module B1 and a temperature loading module B2. The stress loading module B1 is used to fix the specimen 3 (refer to Figure 2 ) and applies the required stress to both ends of the specimen 3, so that the corresponding stress is obtained at the middle section of the specimen 3. In the embodiment of the present invention, the middle section of the specimen 3 is a (first) cylindrical structure with a predetermined length, which is cut from the middle position of the axis of the specimen 3, wherein the geometric center point of the specimen 3 coincides with the geometric center point of the middle section.

[0043] It should be noted that in the embodiment of the present invention, the specimen 3 is constructed as a cylindrical structure. Furthermore, the axial length of the specimen 3 must be greater than both the length and width of the end face of the specimen 3. Furthermore, the specimen 3 may be a rectangular column structure, a circular column structure, or other types of column structures, and the present invention does not impose any specific limitations thereon.

[0044] In addition, several grooves were provided in the midsection of the axis of specimen 3 to simulate pitting. These grooves were located at different locations corresponding to a cross section within the midsection. The grooves at different locations were configured in different shapes, including square, circular, triangular, and elliptical. Figure 4 This is a schematic diagram showing an example of the pitting pit shape in the acoustic testing system for the metal pitting process according to an embodiment of the present application. In this example, if the current specimen 3 is a rectangular column, grooves of different shapes need to be set on different side walls corresponding to the middle position (a certain cross section) of the specimen 3. The shapes of these grooves are square, circular, triangular, and elliptical, respectively.

[0045] Furthermore, the temperature loading module B2 is used to heat both ends (two end faces) of the middle section of the specimen 3 , thereby providing the middle section of the specimen 3 with the temperature environment conditions required for the current test.

[0046] Furthermore, in the embodiment of the present invention, a high-temperature-resistant anti-corrosion layer is provided on all side surfaces of the middle section of the specimen 3, except for those already provided with pitting pits. This ensures that the pitting process only corrodes the pitting pits, thus avoiding overall corrosion of the specimen 3. The high-temperature resistance of the anti-corrosion layer satisfies the first type of temperature conditions.

[0047] Thus, the embodiment of the present invention utilizes the aforementioned stress loading module B1 and temperature loading module B2 to respectively provide corresponding temperature and stress conditions to the pitting pits located in the middle section of the specimen 3, thereby facilitating the detection and analysis of the pitting process at the corresponding locations. Thus, the present invention utilizes stress loading module B1 to impart a certain, adjustable stress intensity to the middle section of the specimen 3. Furthermore, the present invention utilizes temperature loading module B2 to impart a certain, adjustable range of high temperature conditions to the middle section of the specimen 3.

[0048] like Figure 2 As shown, the stress loading module B1 includes: an in-situ stretching machine 1 and a plurality of stretching clamps 2. In an embodiment of the present invention, the in-situ stretching machine 1 adopts an in-situ stretching machine with a slow pulling function. In an embodiment of the present invention, the slow pulling rate is preferably 3μm / min to 5μm / min. The in-situ stretching machine 1 is used to load the test stress that matches the stress environment conditions inside the specimen required for the current test to the specimen 3 during the test implementation process. A stretching clamp 2 is provided at each end of the in-situ stretching machine 1, namely a first stretching clamp and a second stretching clamp. The first stretching clamp 2 and the second stretching clamp 2 are used to clamp the two end faces of the specimen 3 to achieve the purpose of fixing the specimen 3. In this way, the left and right ends of the specimen 3 are respectively clamped by the stretching clamps.

[0049] The temperature loading module B2 includes: several groups of coils 9 and heaters 8. A first group of coils 9 and a second group of coils 9 are respectively provided at both ends (two end faces) of the middle section of the specimen 3. The first group of coils 9 and the second group of coils 9 are both heating coils and are fixed at both ends (two end faces) of the middle section of the specimen 3. In an embodiment of the present invention, the heater 8 adopts a high-frequency induction heating device, which is electrically connected to the first group of coils 9 and the second group of coils 9, respectively. The heater 8 is used to apply power to the two groups of coils during the test implementation process, so as to utilize the principle of electromagnetic induction so that the two groups of coils heat the corresponding positions of the specimen 3, and further make the temperature of the middle section of the specimen 3 meet the first type of temperature conditions. In this way, the two groups of coils control the temperature of the middle section of the specimen 3 through the heat conductivity of the metal.

[0050] Continue to refer Figure 2 The corrosion environment simulation device A includes a corrosion solution tank 4, a reference electrode 5, an auxiliary electrode 6, and an electrochemical workstation 7. The corrosion solution tank 4 is used to hold the corrosion solution required for testing. A pair of first-type through-holes facing each other are formed on the sidewalls of the corrosion solution tank 4. When the specimen 3 passes through the pair of first-type through-holes, the middle section of the specimen 3 is located within the corrosion solution tank 4. Specifically, after the specimen 3 passes through the pair of first-type through-holes, the plurality of pitting pits located in the middle section of the specimen 3 are located within the corrosion solution.

[0051] Furthermore, the shapes of the pair of first-type through-holes match the cross-sectional shape of specimen 3, and the gap between the first-type through-holes and specimen 3 is sealed with a flood seal to prevent leakage of the corrosive solution during testing. For example, assuming specimen 3 is a rectangular column, the two first-type through-holes are rectangular through-holes for inserting specimen 3, and the gap between the rectangular through-holes and specimen 3 is sealed with a flood seal to prevent leakage of the corrosive solution.

[0052] Furthermore, reference electrode 5 and auxiliary electrode 6 are respectively inserted into the corrosive solution within corrosive solution tank 4. Electrochemical workstation 7 is electrically connected to specimen 3, reference electrode 5, and auxiliary electrode 6 via wires. Electrochemical workstation 7 is used to provide the required corrosion intensity conditions for testing to the central region of specimen 3 by outputting currents at different potentials. Thus, the present invention utilizes corrosion environment simulation device A to impart a certain, adjustable corrosion intensity to the corrosive solution.

[0053] Furthermore, the etching solution pool 4 is made of organic glass and is made as thin as possible, and is divided into two parts, an upper part and a lower part. The upper part of the etching solution pool 4 is a rectangular parallelepiped structure, and the lower part of the etching solution pool 4 is an arc-shaped bottom structure (refer to FIG. Figure 3), the upper half is connected to the lower half, and the top of the etching solution pool 4 is sealed. The top of the etching solution pool 4 is provided with two second-type through-holes, which are used to insert the auxiliary electrode 6 and the reference electrode 5, respectively. Thus, the structural design of the etching solution pool 4 can prevent the non-experimental part from corroding and generating acoustic emission signals, which would interfere with the corrosion signal of the tensile specimen 3. At the same time, it also prevents the volatilization of the etching solution and avoids interference with the imaging of the industrial camera 13 described below.

[0054] like Figure 2 As shown, the acoustic emission detection device C includes: a plurality of acoustic emission sensors 10, a plurality of amplifiers 11, and an acoustic emission monitor 12. In this embodiment of the present invention, preferably, two acoustic emission sensors 10 are provided, one on each end wall of the specimen 3, and each employs a high-temperature-resistant acoustic emission sensor. Specifically, the two acoustic emission sensors 10 are located in close proximity to the two end faces of the specimen 3. The acoustic emission sensors 3 are used to collect acoustic emission signals at corresponding locations. In this embodiment of the present invention, each acoustic emission sensor 10 is coupled to the specimen 3 using a coupling agent, wherein the coupling agent's temperature resistance meets the aforementioned first-class temperature conditions.

[0055] Furthermore, corresponding amplifiers are provided at the rear ends of the two acoustic emission sensors 10. In other words, each acoustic emission sensor 10 is connected to a corresponding amplifier 11. The amplifier 11 is used to amplify the received acoustic emission signals and transmit the processed signals to the acoustic emission detector 12.

[0056] Furthermore, the acoustic emission detector 12 utilizes a multi-channel acoustic emission tester. Connected to all amplifiers 11, the acoustic emission detector 12 analyzes each received acoustic emission signal and stores the analysis results. Specifically, in this embodiment of the present invention, each acoustic emission signal is analyzed for signal sampling accuracy, maximum sampling rate, data throughput, minimum signal level, maximum signal level, and signal frequency range, generating corresponding analysis results. The acoustic emission detector then packages each acoustic emission signal and its analysis results, sending them to an information processing device E connected to the acoustic emission detector 12 for integrated analysis.

[0057] Reference again Figure 2, the image acquisition device D includes: a number of industrial cameras 13 and a main control computer 14. In an embodiment of the present invention, the number of industrial cameras 13 configured is consistent with the number of configured pitting pits, so that each industrial camera 13 will monitor the pitting process change state of the corresponding pitting pit to record the pitting process in real time. Specifically, a number of industrial cameras are respectively arranged at different radial positions in the middle area of the specimen 3, and are used to collect test images of the pitting pits at the corresponding positions in real time during the test process, so as to obtain microscopic morphology information and / or bubble generation information of the corresponding pitting pits during the corrosion process. Among them, the test image corresponding to the pitting pits at the corresponding position contains information on the changing state of the pitting pits at the current position during the corrosion process. In addition, a number of industrial cameras 13 are fixed with tripods respectively. In addition, a number of industrial cameras 13 are respectively aimed at the pitting pits on the side walls of the tensile specimen 3 in different positions, and simultaneously collect images of the specimen surface.

[0058] Figure 3 This is a schematic diagram of the local structure of the middle section of the test piece in the acoustic testing system for metal pitting process according to the embodiment of the present application. Figure 3 It can be seen from the figure that when the specimen 3 is a rectangular column, the specimen 3 is provided with corresponding grooves on the side walls in different directions (see Figure 3 ) are used to simulate pitting pits in different orientations. Furthermore, each industrial camera 13 is aligned with the corresponding pitting pit. Four industrial cameras 13 are aligned with four surfaces in corresponding orientations, simultaneously capturing images of the microscopic morphology and bubble generation of different pitting pits during the corrosion process.

[0059] Furthermore, several industrial cameras 13 are connected to a main control computer 14 via signal cables. The main control computer 14 is integrated with acquisition and analysis software. After acquiring test images from different orientations, the main control computer 14 uses the acquisition and analysis software to perform feature extraction on each test image frame, marking pit expansion features and bubble generation features. The test images containing pitting feature information are then transmitted to the information processing device E.

[0060] In addition, a temperature monitoring module (not shown) is provided on one side of the specimen. This temperature monitoring module is connected to the information processing device E. The temperature monitoring module includes a thermocouple (the thermocouple is provided on one side of the specimen material) and a signal processing circuit connected to the thermocouple. The temperature monitoring module is used to collect the real-time temperature of the specimen material and transmit this temperature information to the information processing device E, which then uses the information processing device E to obtain real-time temperature data of the specimen and monitor temperature changes of the specimen.

[0061] Furthermore, the information processing device E is connected to the main control computer 14 and the acoustic emission detector 13. During the test, it is used to simultaneously obtain acoustic emission signals from different paths and their analysis results, as well as test images containing pitting characteristic information from different orientations. This information is then integrated, analyzed, and processed to obtain information on the dynamic changes in pitting stress, the extended characteristics of pitting pits of different shapes, the characteristics of bubble generation in pitting pits of different shapes, and the temperature changes of pitting pits of different shapes. Furthermore, after receiving the acoustic emission signals from different paths and their analysis results, the information processing device E is also used to store this information in a computer to establish a sample database. Furthermore, the information processing device E is also connected to the in-situ stretching machine 1 to store the stress loading conditions recorded by the in-situ stretching machine 1.

[0062] In this way, the present invention uses the above-mentioned metal pitting process acoustic testing system to study the effects of different pitting shapes and different corrosion intensities on the initiation and expansion of pitting damage of the specimen material under high temperature stress conditions. At the same time, the images of processes such as bubble generation, membrane rupture, and pit expansion in the pitting process are combined with the acoustic emission signals to gain an in-depth understanding of the effect of stress on pitting damage under different temperatures, different pit shapes, and different corrosion intensities.

[0063] Example 3

[0064] Based on the acoustic testing system for metal pitting corrosion process described in the above-mentioned embodiment 1 and embodiment 2, the present invention further proposes an acoustic testing method for metal pitting corrosion process. Figure 5 This is a step diagram of the acoustic testing method for the metal pitting process according to an embodiment of the present application. Figure 5 As shown, the acoustic testing method for the metal pitting corrosion process of the present invention includes the following steps: step S510 constructs the corrosion environment required for the current test (installs the corrosion environment simulation device A) and the internal stress environment that meets the first type of temperature conditions (installs the stress environment simulation device B); step S520 starts the test, uses the acoustic emission detection device C to collect acoustic emission signals that characterize the changing state of the specimen's pitting corrosion process, and simultaneously uses the image acquisition device D to collect test images that characterize the changing state of the specimen's pitting corrosion process; step S530 uses the information processing device E to synchronously obtain the acoustic emission signals and the test images, based on which, the pitting corrosion change process of the specimen under the combination of different temperatures, different corrosion intensities and different stress environments is subjected to information integration analysis to obtain corresponding analysis results.

[0065] The specific implementation process of the acoustic testing method for metal pitting corrosion according to the embodiment of the present invention is described below:

[0066] S1, connect the industrial camera 13 and the acoustic emission tester 12 to the computer 15, turn on the power, select a suitable acoustic emission threshold, and calibrate the sensitivity of the high temperature sensor 10 using a lead breaking experiment;

[0067] S2, pre-treating the tensile specimen 3 in advance by prefabricating a small groove in the center of each of the four surfaces of the tensile specimen. The shapes of the small grooves are square, circular, triangular, and elliptical. This step is to concentrate stress in the pitting area. In addition, all surfaces of the middle section of the tensile specimen 3 except the pitting are provided with a high-temperature resistant anti-corrosion layer, thereby corroding the pitting and preventing overall corrosion of the tensile specimen.

[0068] S3, passing the tensile test piece 3 through the corrosion solution pool 4, and then fixing it on the tensile fixture 2, and the gap between the tensile test piece 3 and the corrosion solution pool 4 is sealed by a flood seal to prevent leakage of the corrosion solution;

[0069] S4, four industrial cameras 13 are respectively aimed at the four surfaces of the tensile specimen to simultaneously capture the microscopic morphology of different pits during the corrosion process and the images of bubble generation;

[0070] S5, fix two sets of heating coils 9 to the left and right sections of the tensile specimen 3, and transfer heat to the middle section of the tensile specimen through the heat conductivity of metal, thereby reducing the impact of the heating device on the test area;

[0071] S6, after preparation is completed, start the in-situ stretching machine 1, slowly apply stress to the tensile specimen 3 through the in-situ stretching machine 1, and use the in-situ stretching machine 1 to record the stress loading situation, and store the data in the computer;

[0072] S7, during the stress loading process, the pitting grooves on the surface of the specimen are corroded using an electrochemical pitting system. The two sets of heating coils 9 are powered by a high-frequency induction heater 8, and the required temperature can be adjusted through a control console on the high-frequency induction heater 8;

[0073] S8, the acoustic emission signal is obtained by the acoustic emission sensor 10 in the acoustic emission system, and then the signal is amplified by the amplifier 11 and transmitted to the acoustic emission tester 12 for analysis and storage, and finally the acoustic emission signal is transmitted to the computer 15 for storage to establish a sample database;

[0074] S9, using the industrial camera 13 in the digital image testing system to continuously capture surface images of the tensile test piece 3, and simultaneously capture the microscopic morphology of different pits during the corrosion process and images of bubble generation, and then transmit them to the main control computer 14, and the acquisition and analysis software on the main control computer 14 performs information acquisition and analysis;

[0075] S10, the statistical data are integrated and analyzed by the computer 15 to obtain experimental information such as stress, pit expansion, bubble generation, temperature change, etc., thereby realizing the combination of stress, image, acoustic emission signal, high temperature and pitting data.

[0076] The embodiment of the present invention proposes a metal pitting process acoustic testing system. The system can synchronously detect multiple information such as the stress size, image, and acoustic emission signal at the pitting pit during the initiation and expansion of pitting damage of the specimen material under high temperature stress conditions. By combining the multivariate signals of the entire process of pitting damage of the material, it can effectively simulate the external crack initiation and internal damage mechanism of the specimen material under stress tension under pitting conditions when the system is running under high temperature environment, and simultaneously obtain the connection between the acoustic emission signal and the internal damage, fully understand the pitting damage evolution law (damage mechanism) of the material under tensile stress under high temperature environment, lay a theoretical foundation for pitting damage monitoring and early warning during system operation, and provide a method basis for material selection and real-time detection of high temperature special equipment. At the same time, the system can simultaneously observe the influence mechanism of different temperatures, different pitting pit shapes, different stress sizes, and different corrosion intensities on the pitting damage of the specimen. In addition, the present invention also has the characteristics of simple structure, flexible operation, flexible temperature setting, and stop-and-go operation, and can be widely used in the study of pitting expansion behavior of metal materials under different temperatures, different loads, different pitting pit shapes, and different corrosion intensities.

[0077] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by anyone skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

[0078] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should extend to equivalent substitutions of these features understood by those skilled in the relevant art. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0079] References in this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Therefore, appearances of the phrases "one embodiment" or "an embodiment" in various places throughout this specification do not necessarily refer to the same embodiment.

[0080] Although the embodiments disclosed above are for facilitating understanding of the present invention, the contents described are merely embodiments adopted for facilitating understanding of the present invention and are not intended to limit the present invention. Any person skilled in the art of the present invention may make any modifications and changes in the form and details of the implementation without departing from the spirit and scope of the present invention. However, the scope of patent protection of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A metal pitting process acoustic testing system, characterized in that: include: A corrosion environment simulation device, which is used to provide the corrosion environment required for the test; A stress environment simulation device, which is used to provide the test piece with an internal stress environment under the first type of temperature conditions during testing; An acoustic emission detection device and an image acquisition device, which are used to respectively collect acoustic emission signals and test images representing the changing state of the pitting corrosion process of the test piece during the test; An information processing device is used to synchronously acquire the acoustic emission signal and the test image, based on which, the pitting change process of the specimen under the combination conditions of different temperatures, different corrosion intensities and different stress environments is subjected to information integration analysis to obtain corresponding analysis results, wherein, by analyzing the dynamic change information of the stress size of pitting pits of different shapes, the expansion characteristic information of pitting pits of different shapes, the bubble generation characteristic information at pitting pits of different shapes, and the temperature change information of pitting pits of different shapes, the influence of different pitting shapes and different corrosion intensities of the specimen material on the initiation and expansion of pitting damage under high temperature stress conditions is studied, and at the same time, the images containing bubble generation, film rupture, and pitting pit expansion characteristics in the pitting process are combined with the acoustic emission signal to gain an in-depth understanding of the effect of stress on pitting damage under the combination conditions of different temperatures, different pit shapes, and different corrosion intensities, wherein, The stress environment simulation device comprises: A stress loading module, which is used to fix the specimen and apply the stress required for the test to both ends of the specimen, wherein the specimen is constructed as a cylindrical structure, and a plurality of grooves are provided at different positions on the side wall of the middle section of the specimen to simulate pitting pits by using the plurality of grooves; a temperature loading module, which is used to heat both ends of the middle section of the specimen to provide the temperature conditions required for the test at the middle section of the specimen; The image acquisition device comprises: Several industrial cameras are respectively arranged at different radial positions in the middle of the test piece, and are used to collect the test images containing the changing state information of the pitting pits on the side wall of the test piece at the corresponding positions in real time during the test process, so as to obtain the microscopic morphology information and bubble generation information of the corresponding pitting pits during the corrosion process; A main control computer is connected to the plurality of industrial cameras and is used to obtain the test images in different orientations, perform feature extraction processing on the test images, and based on this, mark pit expansion features and bubble generation features, thereby sending the test images containing pitting feature information to the information processing device.

2. The system according to claim 1, wherein: The temperature loading module includes: a first set of coils and a second set of coils respectively fixed at two ends of the middle section of the test piece; The heater is connected to the first group of coils and the second group of coils and is used to energize the two groups of coils so as to utilize the principle of electromagnetic induction to enable the two groups of coils to heat corresponding positions of the test piece.

3. The system according to claim 1, wherein: The stress loading module includes: an in-situ tensile machine for applying a test stress to the specimen that matches the internal stress environment conditions of the specimen required for the test; A first stretching clamp and a second stretching clamp are respectively arranged at both ends of the in-situ stretching machine, and the first stretching clamp and the second stretching clamp are used to clamp both end surfaces of the specimen to fix the specimen.

4. The system according to any one of claims 1 to 3, characterized in that The corrosion environment simulation device comprises: A corrosive solution pool having a pair of first-type through holes disposed opposite to each other on its sidewalls, wherein the test piece passes through the first-type through holes so that the middle portion of the test piece is located inside the corrosive solution pool, and the corrosive solution pool is used to contain the corrosive solution; an auxiliary electrode and a reference electrode respectively inserted into the corrosion solution; The electrochemical workstation electrically connected to the auxiliary electrode, the reference electrode, and the test piece is used to provide the corrosion intensity conditions required for the test to the middle section of the test piece by outputting currents of different potentials.

5. The system according to claim 4, characterized in that The upper half of the corrosion solution pool is constructed as a rectangular parallelepiped structure, and the lower half of the corrosion solution pool is constructed as an arc-shaped bottom structure. The upper half is connected to the lower half, and the top of the corrosion solution pool is sealed. Two second-type through holes are provided on the top of the corrosion solution pool, and the two second-type through holes are used to insert the auxiliary electrode and the reference electrode, respectively. The shape of the first-type through hole matches the cross-sectional shape of the specimen, and the gap between the first-type through hole and the specimen is sealed using a pan seal.

6. The system according to any one of claims 1 to 3, characterized in that: The acoustic emission detection device comprises: Acoustic emission sensors are respectively provided on the side walls at both ends of the specimen, for collecting the acoustic emission signals, the acoustic emission sensors are coupled to the specimen using a coupling agent, and the temperature resistance of the coupling agent meets the first type of temperature conditions; An amplifier is provided at the rear end of each acoustic emission sensor, for amplifying the received acoustic emission signal and transmitting the processed signal to the acoustic emission detector; The acoustic emission detector is used to analyze the acoustic emission signal and store the analysis result.

7. The system according to claim 1, wherein: When the cross-section of the test piece is rectangular, grooves of different shapes are respectively provided on the side walls at different positions of the middle section of the test piece, and the shapes include square, circle, triangle and ellipse.

8. A method for acoustic testing of metal pitting corrosion, characterized in that: The method is implemented using the system according to any one of claims 1 to 7, and the method includes: Construct the corrosion environment required for the current test and the internal stress environment that meets the first type of temperature conditions; After the test begins, acoustic emission signals and test images representing the changing state of the specimen's pitting corrosion process are collected respectively; The acoustic emission signals and test images are acquired synchronously, and based on them, information integration analysis is performed on the pitting corrosion change process of the specimen under the combined conditions of different temperatures, different corrosion intensities and different stress environments to obtain corresponding analysis results.

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