Controllable loading device and method for small-sized metal samples under high pressure environment

Abstract

This invention discloses a controllable loading device and method for small-sized metal samples under high pressure, comprising: an autoclave; an environmental control system; a controllable loading system, wherein a sample clamp holds metal samples of different shapes and sizes to be tested and fixes them inside the autoclave; an electronic testing machine is connected to the loading pair and drives the loading pair to move axially; an electrical signal measurement system, wherein a constant voltage source applies a constant voltage to the metal sample to be tested and the loading pair, and a signal acquisition device monitors the current value of the metal sample to be tested and / or the loading pair in real time; wherein the electronic testing machine controls the loading pair to move within the autoclave until it contacts the metal sample to be tested; when the current value monitored by the signal acquisition device exceeds a threshold, the loading start point is determined. This invention effectively solves the measurement accuracy and loading control problems of traditional solutions.

Description

Technical Field

[0001] This invention belongs to the field of performance evaluation of high-end equipment materials, and particularly relates to a controllable loading device and manufacturing method for small-sized metal samples under high pressure. Background Technology

[0002] High-pressure fluid conditions are prevalent in extremely harsh environments across certain industrial sectors. Typical scenarios include the high-temperature, high-pressure water / gas environment of nuclear power systems, the low-temperature, high-pressure seawater environment of deep-sea engineering, and the high-pressure gaseous hydrogen environment of hydrogen transportation and storage facilities. When metallic structural materials are exposed to these environments, they are highly susceptible to performance aging and even failure under the coupled effects of load and corrosion. Therefore, industry and academia have conducted extensive laboratory research to elucidate the relevant aging and failure mechanisms, ensuring the structural integrity and safety of industrial installations during service.

[0003] In experimental research, some scenarios require in-situ loading of samples under high pressure. Traditional methods typically load large samples by connecting them to an external testing machine via a connecting rod. However, this method has significant limitations for small samples: because small samples bear lower loads, the frictional force during the connecting rod transmission accounts for a significant proportion, sometimes even exceeding the actual load on the sample, making it impossible for the testing machine to accurately measure the force on the sample. Furthermore, traditional methods for determining the loading initiation point rely on load monitoring, i.e., locating the loading start point through the linear increase in force with deformation. Failure of load measurement directly renders this method ineffective. Summary of the Invention

[0004] Based on the shortcomings of the existing technology, the present invention provides a controllable loading device and method for small-sized metal samples under high pressure, which effectively solves the problems of measurement accuracy and loading control in traditional solutions.

[0005] This application provides a controllable loading device for small-sized metal samples under high pressure, including:

[0006] The autoclave achieves a sealed high-pressure environment through a sealing structure.

[0007] An environmental control system, connected to the autoclave, is used to regulate the environmental parameters of the autoclave.

[0008] The controllable loading system includes an electronic testing machine, a loading pair, and a sample clamp. The sample clamp holds metal samples of different shapes and small sizes to be tested and fixes them inside the autoclave. The electronic testing machine is connected to the loading pair and drives the loading pair to move axially.

[0009] An electrical signal measurement system includes a constant voltage source and a signal acquisition device; the constant voltage source applies a constant voltage to the metal sample under test and the loading pair, and the signal acquisition device monitors the current value between the metal sample under test and the loading pair in real time;

[0010] The electronic testing machine controls the loading pair to move within the autoclave until it contacts the metal sample to be tested; when the current value monitored by the signal acquisition device exceeds the threshold, the starting point of sample loading is determined.

[0011] In some embodiments, the signal acquisition device includes wires; the wires are electrically connected to the metal sample to be tested and the loading pair respectively; and the connection points of the wires with the metal sample to be tested and the loading pair are located at positions that do not affect the force on the metal sample to be tested.

[0012] In some embodiments, the connection point between the wire and the metal sample to be tested is the position where the sample holder clamps the metal sample to be tested, and the connection point between the wire and the loading pair is located on a plane of the loading pair away from the metal sample to be tested.

[0013] In some embodiments, the signal acquisition device further includes a displacement sensor and a prompter disposed outside the autoclave. The displacement sensor is connected to the loading pair and measures the displacement of the loading pair. The prompter provides an audible or photoelectric prompt when the sample loading start point is determined.

[0014] In some embodiments, the sample holder is electrically insulated from the metal sample to be tested by a polymer insulator or a ceramic insulator.

[0015] In some embodiments, the wire is soldered to the metal sample to be tested.

[0016] In some embodiments, the autoclave is made of stainless steel or a nickel-based alloy; the environmental parameters include temperature, pressure, flow rate, solution solute, dissolved gas content, pH, conductivity, or gas composition.

[0017] Secondly, the present invention provides a controllable loading method for small-sized metal samples under high pressure, comprising:

[0018] The metal sample to be tested is fixed inside the autoclave using a sample clamp;

[0019] Shut down the autoclave, inject the medium through the environmental control system, adjust the environmental parameters to the preset range, and maintain the stability of the medium composition;

[0020] A constant voltage is applied between the metal sample to be tested and the loading pair by a constant voltage source and a threshold is determined. The signal acquisition device monitors the current value in real time.

[0021] The loading pair is controlled to move towards the metal sample to be tested until the loading pair contacts the metal sample to be tested and the current value exceeds the current threshold. This is determined as the sample loading start point.

[0022] In some implementations, the loading path includes constant strain rate loading, stepped stress loading, or cyclic loading, and the displacement data is converted into the stress-strain curve of the sample through a finite element simulation model.

[0023] In some embodiments, the current threshold is determined based on the conductivity of the liquid or gas medium inside the autoclave;

[0024] Using the current when the loaded pair is far from the sample as a reference value, when the conductivity of the medium is lower than a preset conductivity threshold, the current threshold range is set to 2 to 10 times the reference value, and a range higher than the current threshold is determined based on the probability of misjudgment; when the conductivity of the medium is higher than the preset conductivity threshold, the current threshold is set to 1 to 2 times the reference value.

[0025] This application provides a controllable loading device and method for small-sized metal samples under high pressure. A constant voltage is applied between the loading pair and the metal sample under test, and the current value is monitored in real time. When the current suddenly increases beyond a threshold, the loading start point can be determined, avoiding the bias caused by traditional reliance on load signals and improving the accuracy and repeatability of loading start point determination. This invention not only improves the reliability and data accuracy of the loading process for small-sized metal samples but also broadens the applicability of this type of sample in the study of mechanical properties under extreme environments such as high pressure, high temperature, and corrosion, thus possessing high experimental value. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the controllable loading device for small-sized metal samples under high pressure provided by the present invention.

[0027] Figure 2 This is a flowchart illustrating the controllable loading method for small-sized metal samples under high pressure provided by the present invention.

[0028] Figure 3 This is a schematic diagram of the model structure of the controllable loading method for small-sized metal samples under high pressure provided by the present invention.

[0029] Figure 4 This is a schematic diagram of the current results for the controllable loading method for small-sized metal samples under high pressure provided by the present invention.

[0030] Figure 5 A schematic diagram of actual test data of air for the controllable loading method of small-sized metal samples under high pressure provided by the present invention;

[0031] Figure 6 A schematic diagram of actual test data in 320°C high-temperature and high-pressure water for the controllable loading method of small-sized metal samples under high pressure environment provided by the present invention;

[0032] In the figure: 1. Connecting rod; 2. Loading pair; 3. Fixture frame; 4. Sample clamping pair; 5. Fixture bolt; 6. Metal sample to be tested; 7. Insulating component. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specifically stated, the relative arrangement, expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0034] This application provides a controllable loading device for small-sized metal samples under high pressure, which effectively solves the problems of measurement accuracy and loading control in traditional solutions.

[0035] Specifically, such as Figure 1 The diagram shows a controllable loading device for small-sized metal samples under high pressure, comprising an autoclave, an environmental control system, a controllable loading system, and an electrical signal measurement system. The autoclave achieves high-pressure environment sealing through a sealed structure. The environmental control system is connected to the autoclave and used to regulate its environmental parameters. The controllable loading system includes an electronic testing machine, a loading pair 2, and a sample clamp, which holds the metal sample 6 to be tested and fixes it inside the autoclave. The electrical signal measurement system includes a constant voltage source and a signal acquisition device. The constant voltage source applies a constant voltage to the metal sample 6 and the loading pair 2, while the signal acquisition device monitors the current value between the metal sample and the loading pair 2 in real time. The electronic testing machine controls the movement of the loading pair 2 within the autoclave until it contacts the metal sample 6. When the current value monitored by the signal acquisition device exceeds a threshold, the sample loading starting point is determined.

[0036] In this application, the metal sample 6 used for testing is a small-sized metal sample. A small-sized metal sample refers to a metal sample whose load during loading is not significantly greater than the frictional force of the loading link 1, making it impossible to determine the loading initiation point using traditional force values. These generally include thin metal sheets or miniature rods, with forces below tens of Newtons. The loading initiation point is the instant when the loading pair 2 first contacts the sample and begins to apply stress or strain. Traditional methods use sudden changes in force as the basis for judgment, but for small-sized metal samples, the force signal is overwhelmed by friction, making accurate determination impossible.

[0037] The autoclave is made of an alloy material with excellent corrosion resistance, preferably stainless steel or nickel-based alloy, and the material selection and structural design are based on the specific test medium and temperature and pressure requirements. In practical applications, the autoclave can be designed according to the actual purpose, and no specific limitations are made in this application.

[0038] To adapt to various harsh operating conditions, such as the high-temperature and high-pressure water environment of nuclear power plants, the low-temperature and high-pressure seawater environment of deep seas, and the high-pressure gaseous hydrogen environment for hydrogen transportation and storage, the pressure resistance of the autoclave can be designed to range from 30MPa to 100MPa, and the temperature resistance range can reach -50℃ to 700℃, with corresponding expansions available according to experimental requirements. The autoclave body is equipped with media inlet and outlet, pressure detection port, and temperature sensing port, enabling fluid circulation, pressure regulation, and temperature control through external environmental control systems, ensuring long-term stability of the composition and physical parameters of the medium inside the autoclave. Simultaneously, the autoclave structure has undergone finite element strength verification, capable of withstanding internal pressure loads under high-pressure fluid and ensuring no plastic deformation or sealing failure under repeated cyclic loading, thus providing a stable and repeatable high-pressure testing environment for controlled loading of small-sized metal samples.

[0039] The environmental control system is connected to the autoclave and is used to regulate the environmental parameters of the autoclave, enabling the simulation of various testing environments within the autoclave, such as the high-temperature and high-pressure water environment of nuclear power plants, the high-temperature and high-pressure gaseous environment of nuclear power plants, the low-temperature and high-pressure seawater environment of deep seas, and high-pressure hydrogen. The environmental control system can select water-based solutions or gases as the test medium according to experimental requirements and can independently adjust pressure, temperature, and medium composition. Pressure is generally regulated through a high-pressure pump and a back-pressure valve. The high-pressure pump injects the test medium into the autoclave and increases its pressure, while the back-pressure valve maintains stable pressure within the autoclave during loading to ensure long-term repeatability of the test environment. Temperature control is achieved through external heating jackets, heat exchangers, or cooling devices configured on the autoclave to meet the temperature requirements under different experimental conditions. Medium composition control is determined based on the type of medium. When the test medium is a water-based solution, the environmental control system can adjust the solute concentration, dissolved gas content, pH value, and conductivity. When the test medium is a gas, it can adjust and maintain the stable proportion of gas components. During long-term loading tests, the environmental control system can dynamically adjust and monitor the composition and physical parameters of the medium in real time, thereby ensuring that the internal environment of the autoclave is always maintained within the preset range, meeting the experimental requirements for in-situ controllable loading of small-sized metal samples.

[0040] The controllable loading system is used to apply controlled loading to the metal sample 6 located inside the autoclave. The system includes an electronic testing machine, a loading pair 2, and a sample clamp. The electronic testing machine is located outside the autoclave and connected to the loading pair 2 inside via a connecting rod 1, enabling precise and controllable speed to drive the loading pair 2 to move axially. To ensure accurate control of the deformation of small samples during loading, the electronic testing machine possesses high-resolution displacement control capabilities, with control accuracy down to the micrometer level. It can operate in various loading modes, including constant strain rate, stepped loading, and cyclic loading, thus meeting the mechanical loading requirements of different experimental conditions.

[0041] Loading assembly 2 is a loading component located inside the autoclave, directly contacting the metal sample 6 to be tested. The end of the loading assembly can be configured with a suitable geometry based on the force-bearing surface of the metal sample 6, ensuring uniform force application upon contact. Alternatively, a loading assembly of appropriate material and shape can be selected according to the testing objective. Generally, loading assembly 2 is made of a highly conductive and corrosion-resistant metal material, such as titanium alloy or stainless steel, to ensure stable operation in high-pressure corrosive media and maintain good electrical connection performance when in contact with the metal sample 6. Force is transmitted between loading assembly 2 and the electronic testing machine via connecting rod 1. While the force on connecting rod 1 is relatively low during the loading of small samples, the electronic testing machine compensates for the frictional force of connecting rod 1 through closed-loop displacement control. The small force applied to connecting rod 1 by the metal sample 6 does not cause deformation of connecting rod 1, nor does it affect the precise control of connecting rod 1 and loading assembly 2 by the electronic testing machine. The overall loading process maintains high precision, improving the accuracy of the loading start point determination.

[0042] The sample clamp is used to hold small-sized metal samples inside the autoclave and maintain their stability under stress during loading. Because the size and shape of the metal samples 6 to be tested vary considerably, replaceable clamping sub-modules are used to meet the diverse sample shape requirements and improve the adaptability of the sample clamp. For example... Figure 1 As shown, the sample fixture is applied to a thin sheet-like metal sample 6. It includes a fixture frame 3, a sample clamping assembly 4, and clamping bolts 5. These components work together via the clamping bolts 5 to fix the metal sample in the fixture. To prevent electrical signal interference between the metal sample 6 and the loading assembly 2, the sample fixture has a polymer or ceramic insulating component 7 on the contact surface with either the metal sample 6 or the loading assembly 2. After the sample is placed in the fixture frame 3 and electrically isolated by the insulating component 7, the sample clamping assembly 4 is fixed to the fixture frame 3 by the clamping bolts 5, ensuring the metal sample is stable within the fixture. The sample fixture as a whole possesses sufficient mechanical strength and rigidity, and its deformation is negligible throughout the experiment, thus not interfering with the mechanical response of the sample.

[0043] The electrical signal measurement system solves the problem that the loading start point cannot be determined by traditional force values ​​for small-sized metal samples during loading. The electrical signal measurement system includes a constant voltage source, signal acquisition equipment, and a prompting device. By forming an independent circuit between the loading pair 2 and the metal sample 6 under test and monitoring the current change in real time, it can accurately determine the moment of first contact between the loading pair 2 and the metal sample 6 under test.

[0044] A constant voltage source is located outside the autoclave and is electrically connected to the loading assembly 2 and the metal sample 6 to be tested via wires. It can continuously apply a constant voltage during loading. The output voltage range of the constant voltage source is generally 0.01~1V, allowing for electrical signal measurement without affecting the microscopic properties of the metal sample. When the conductivity of the medium inside the autoclave is low, the lowest possible voltage is selected to eliminate the influence of voltage on material properties. The wires are fixed to the metal sample 6 and the loading assembly 2 by welding or crimping. The connection positions are selected to avoid affecting the loading force, thus preventing interference from differences in medium conductivity on electrical signal detection. In this application, the connection point between the wires and the metal sample is the position where the sample clamp holds the metal sample, thereby reducing the pulling force on the wire connection during loading, preventing loosening or breakage, and ensuring that the voltage output from the constant voltage source is stably applied to the sample. The connection point between the wire and the loading pair is located on a plane away from the metal sample under test, preventing the wire connection from having an additional impact on the stress distribution of the metal sample under test, ensuring the accuracy of stress transfer during mechanical loading, and avoiding experimental data distortion due to local contact stress. The wire is externally encased in a polymer or ceramic insulating tube, extending to the outside of the autoclave through a penetration part, and connected to the constant pressure source and signal acquisition equipment.

[0045] The signal acquisition device is connected in series with the constant voltage source circuit to monitor the current change between the loading pair 2 and the metal sample in real time. The sampling frequency can reach above 1kHz, thus ensuring that transient current surge signals can be captured during the loading process. The loading pair 2 moves slowly towards the metal sample 6 under the drive of the electronic testing machine. When the loading pair 2 has not yet contacted the sample, the circuit consisting of the constant voltage source, the metal sample 6, and the loading pair 2 is in an approximately open-circuit state, and the current is extremely low. Once the loading pair 2 contacts the sample, the resistance decreases, and the current increases instantaneously. The signal acquisition device detects this current surge and compares it with a preset threshold. When the current value exceeds the preset threshold, it is determined that the loading pair 2 has formed a stable electrical contact with the sample, and the prompting device immediately sends a signal to alert the operator. This determination process does not depend on the magnitude of the load on the sample and can effectively overcome the force signal distortion problem caused by the friction of the connecting rod 1.

[0046] Figure 3 The model was created using finite element method (FEM) software. The outer spherical structure represents water, the inner hollow columnar structure is loading pair 2 (made of 316 stainless steel), and the flat strip structure is the metal sample 6 to be tested (also made of 316 stainless steel). A 1V DC voltage was applied between loading pair 2 and the metal sample 6, and the distance between them was varied. The current between them was calculated, and the results were plotted. Figure 4 It can be seen that as the distance between the two decreases, the current remains basically stable. When the two come into contact, the current suddenly increases by about 7 orders of magnitude. The change in the current signal before and after is significant, which can effectively indicate the position of the contact point.

[0047] The current threshold is determined based on the conductivity characteristics of the medium inside the autoclave. For air or gas environments, due to the extremely low conductivity of the medium, the current is very low before the loading device 2 contacts the sample. The contact current threshold can be set to 100 to 10,000 times the open-circuit current of the signal acquisition device to determine the starting point. For highly conductive media such as water-based solutions, a small leakage current may exist in the circuit before the loading device 2 contacts the metal sample 6. The contact current threshold can be set to 10 to 1,000 times the open-circuit current to ensure accurate determination. For newly conducted experiments, it is advisable to combine simulation and pre-experimentation to determine the variation of the current signal with distance in order to clarify the optimal threshold range.

[0048] In practice, such as Figure 2 As shown, the following controllable loading method is adopted:

[0049] Step S1: The metal sample 6 to be tested is fixed in the autoclave using a sample clamp;

[0050] Step S2: Shut down the autoclave, inject the medium through the environmental control system, adjust the environmental parameters to the preset range, and maintain the stability of the medium composition;

[0051] Step S3: Apply a constant voltage between the metal sample to be tested and the loading pair using a constant voltage source and determine the threshold value. The signal acquisition device monitors the current value in real time.

[0052] Step S4: Control the loading pair 2 to move towards the metal sample 6 to be tested until the loading pair 2 contacts the metal sample 6 to be tested and the current value exceeds the threshold, which is determined as the loading start point.

[0053] In actual operation, the electronic testing machine drives the loading pair 2 via connecting rod 1 to slowly approach the metal sample 6 fixed in the sample holder. A constant voltage source continuously applies a constant voltage between the loading pair 2 and the sample, and the signal acquisition device records the current value in real time. When the loading pair 2 first makes electrical contact with the metal sample 6, the current suddenly increases to exceed the threshold, and the prompting device immediately activates, such as a buzzer sounding or an indicator light illuminating, prompting the operator to record the displacement of the loading pair 2. The displacement sensor can accurately measure the displacement of the loading pair 2, and this moment is the loading start point of the sample. Through this method of determining the loading start point based on electrical signals, the loading start point can still be accurately determined even when the force on small-sized samples is extremely low and the friction of connecting rod 1 is not negligible, providing a reliable benchmark for subsequent controlled loading. This process works in conjunction with the autoclave and environmental control system to ensure that the sample is loaded in situ in a stable high-pressure environment, and the measurement of electrical signals is not affected by the conductivity of the medium, exhibiting high versatility and reliability.

[0054] Also includes:

[0055] Apply constant strain rate loading, stepped stress loading, or cyclic loading to the sample.

[0056] After the electrical signal measurement system determines the loading start point, the electronic testing machine continues to drive the loading pair 2 in closed-loop control mode, applying a preset loading path to the metal sample 6 under test, achieving a fully controllable mechanical loading process. The loading path can be selected from various methods, such as constant strain rate loading, stepped stress loading, or cyclic loading, depending on the experimental objective. For constant strain rate loading, the electronic testing machine controls the movement speed of the loading pair 2 according to a set micrometer-level displacement increment, ensuring that the deformation of the metal sample 6 under test increases uniformly throughout the loading process, suitable for analyzing the continuous deformation characteristics of materials. For stepped stress loading, the loading pair 2 can be gradually loaded according to a certain displacement or strain interval, and maintained at each level for a period of time, to study the creep behavior and residual strain accumulation characteristics of the sample under stress-maintaining conditions. Cyclic loading mode studies the fatigue performance and elastoplastic recovery ability of materials through repeated loading and unloading paths. Applying constant loads or cyclic alternating loads to samples under specific corrosive environments allows for the study of stress corrosion and corrosion fatigue characteristics of small-sized samples under such environments.

[0057] To further obtain the mechanical response of the material, the relationship between the displacement of the loading pair 2 and the strain of the sample can be calculated using finite element simulation or theoretical formulas. For example, when the metal sample 6 to be tested is a thin sheet with a standard geometric shape, the displacement of the loading pair 2 can be directly converted into the axial stress and strain of the sample using material mechanics formulas; when the geometric shape of the metal sample 6 to be tested is complex, the stress and strain distribution of the sample can be calculated by establishing a finite element model based on the displacement of the loading pair 2 and the constraint conditions of the fixture.

[0058] Furthermore, the present invention can also simultaneously adjust the environmental parameters inside the autoclave during the loading process, such as changing the medium temperature, pressure or gas composition, thereby simulating the multi-factor coupling effect scenario under real service conditions and better mimicking the mechanical data of metal materials in complex environments.

[0059] Taking an alloy sheet sample with a length of 30 mm, a width of 2 mm, and a thickness of 0.2 mm as an example, multiple sets of loading experiments were conducted in air and high-pressure aqueous solution environments. Traditional methods for determining the starting point through load curves cannot achieve this test, but the present invention can accurately determine the loading starting point. Figure 5 , Figure 6Actual test data were presented in air and in 320°C high-temperature, high-pressure water. To eliminate the influence of voltage values, the vertical axis was converted to resistance values ​​(voltage / current). The results of five repeated tests showed that the resistance value exhibited abrupt changes of approximately five orders of magnitude at the same location, indicating that the method is reproducible and reliable. The standard deviations of the five measurements in air and in high-temperature, high-pressure water were 0.39 and 1.1 micrometers, respectively. The 95% confidence interval for the contact point determined by the five measurements in high-temperature, high-pressure water was calculated to be ±2.2 micrometers. Furthermore, comparing the contact point locations measured in air and in high-temperature, high-pressure water revealed a deviation of approximately 20 micrometers, indicating that the entire device did indeed deform during the heating and pressurization process. Therefore, the contact point measured in air cannot be used as the contact point location under high-temperature, high-pressure water, further highlighting the necessity of this invention.

[0060] The method of this invention has been experimentally verified to significantly improve the accuracy of determining the loading initiation point for small-sized metal samples. Furthermore, verification in different media such as air, aqueous solution, and high-pressure hydrogen shows that the controllable loading method of this invention is environmentally adaptable; the threshold only needs to be adjusted according to the conductivity of the medium to operate stably, unaffected by differences in environmental conductivity.

[0061] This application provides a controllable loading device and method for small-sized metal samples under high pressure. A constant voltage is applied between the loading pair and the metal sample under test, and the current value is monitored in real time. When the current suddenly increases beyond a threshold, the loading start point can be determined, avoiding the bias caused by traditional reliance on load signals and improving the accuracy and repeatability of loading start point determination. This invention not only improves the reliability and data accuracy of the loading process for small-sized metal samples but also broadens the applicability of this type of sample in the study of mechanical properties under extreme environments such as high pressure, high temperature, and corrosion, thus possessing high experimental value.

[0062] Through the above-described process, this invention not only solves the problem of accurately determining the loading initiation point for small-sized metal samples, but also enables precise controlled loading in complex environments such as high pressure, high temperature, and corrosion, obtaining accurate and reliable mechanical property data. This method can be widely applied to the performance research of structural materials in extreme environments such as nuclear power, deep sea, and hydrogen energy, providing a solid experimental foundation for material service safety assessment and life prediction.

[0063] The above descriptions are merely some embodiments of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A controllable loading device for small-sized metal samples under high pressure, characterized in that, include: The autoclave achieves a sealed high-pressure environment through a sealing structure. An environmental control system, connected to the autoclave, is used to regulate the environmental parameters of the autoclave. A controllable loading system includes an electronic testing machine, a loading pair, and a sample clamp. The sample clamp holds metal samples of different shapes and small sizes to be tested and fixes them inside the autoclave. The electronic testing machine is connected to the loading pair and drives the loading pair to move axially. The sample clamp is electrically insulated from the metal sample to be tested by a polymer insulating component or a ceramic insulating component. An electrical signal measurement system includes a constant voltage source and a signal acquisition device; the constant voltage source applies a constant voltage to the metal sample under test and the loading pair, and the signal acquisition device monitors the current value between the metal sample under test and the loading pair in real time; The signal acquisition device includes wires; the wires are respectively connected to the metal sample to be tested and the load auxiliary electrical connection. Furthermore, the connection point between the wire and the metal sample to be tested and the loading pair is set at a position that does not affect the force on the metal sample to be tested; the connection point between the wire and the metal sample to be tested is the position where the sample clamp holds the metal sample to be tested, and the connection point between the wire and the loading pair is located on a plane of the loading pair away from the metal sample to be tested; The electronic testing machine controls the loading pair to move within the autoclave until it contacts the metal sample to be tested; when the current value monitored by the signal acquisition device exceeds the threshold, the starting point of sample loading is determined.

2. The controllable loading device for small-sized metal samples under high pressure according to claim 1, characterized in that, The signal acquisition device also includes a displacement sensor and a prompter installed outside the autoclave. The displacement sensor is connected to the loading pair and measures the displacement of the loading pair. The prompter provides an audible or photoelectric prompt when the sample loading start point is determined.

3. The controllable loading device for small-sized metal samples under high pressure environment according to claim 1, characterized in that, The wire is soldered to the metal sample to be tested.

4. The controllable loading device for small-sized metal samples under high pressure as described in claim 1, characterized in that, The autoclave is made of stainless steel or nickel-based alloy; the environmental parameters include temperature, pressure, flow rate, solute in solution, dissolved gas content, pH, conductivity, or gas composition.

5. A controllable loading method for small-sized metal samples under high pressure, characterized in that, The controllable loading device for small-sized metal samples under high pressure as described in any one of claims 1 to 4 includes: The metal sample to be tested is fixed inside the autoclave using a sample clamp; Shut down the autoclave, inject the medium through the environmental control system, adjust the environmental parameters to the preset range, and maintain the stability of the medium composition; A constant voltage is applied between the metal sample to be tested and the loading pair by a constant voltage source and a threshold is determined. The signal acquisition device monitors the current value in real time. The loading pair is controlled to move towards the metal sample to be tested until the loading pair contacts the metal sample to be tested and the current value exceeds the current threshold. This is determined as the sample loading start point.

6. The controllable loading method for small-sized metal samples under high pressure according to claim 5, characterized in that, The loading paths include constant strain rate loading, stepped stress loading, or cyclic loading. The displacement data is converted into the stress-strain curve of the sample through a finite element simulation model.

7. The controllable loading method for small-sized metal samples under high pressure according to claim 5, characterized in that, The current threshold is determined based on the conductivity of the liquid or gas medium inside the autoclave; Using the current when the loaded pair is far from the sample as a reference value, when the conductivity of the medium is lower than a preset conductivity threshold, the current threshold range is set to 100 to 10000 times the reference value, and a range higher than the current threshold is determined according to the probability of misjudgment; when the conductivity of the medium is higher than the preset conductivity threshold, the current threshold is set to 10 to 1000 times the reference value.

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