Stress corrosion test device for simulating surface thermal shock load and test method thereof

Abstract

The invention discloses a stress corrosion test device for simulating a surface thermal shock load and a test method thereof, and the stress corrosion test device for simulating the surface thermal shock load is provided with a stress corrosion load module, a thermal shock load module and a high-temperature and high-pressure water system. The synergistic effect of the stable stress load, the periodic thermal shock simulation load and the high-temperature and high-pressure water environment is achieved, and the service environment of the primary loop auxiliary pipeline of the nuclear power plant is accurately reproduced. The problem that in the prior art, the surface thermal shock load and the stress corrosion coupling effect cannot be simulated at the same time is solved, a test platform better fitting the actual working condition is provided for material stress corrosion behavior evaluation, and the evaluation result has higher accuracy and reference value.

Description

Technical Field

[0001] This invention relates to the field of stress corrosion evaluation technology for nuclear power structural materials, and in particular to a stress corrosion testing device and method for simulating surface thermal shock loads. Background Technology

[0002] During service, auxiliary pipelines in the primary loop of nuclear power plants are subjected to complex thermal stresses due to thermal stratification, thermal shock, and thermal oscillation, which can lead to stress corrosion cracking and thermal fatigue cracking, posing significant risks. At the junctions of auxiliary pipelines and main pipelines, turbulence has a significant impact; research experience shows that the inward compression of the auxiliary pipeline due to turbulence is several times its diameter. In the mixing zone of hot and cold fluids, the inner surface of the auxiliary pipeline experiences rapid temperature fluctuations. These rapid and drastic temperature changes cause significant thermal stress on the inner surface of the pipeline due to resistance to temperature changes, a phenomenon known as thermal oscillation. This alternating thermal stress on the surface is highly likely to trigger crack initiation. To study the crack initiation behavior of auxiliary pipelines, it is necessary to clarify the impact of the load caused by this thermal oscillation.

[0003] Currently, numerous research methods and significant results have been achieved for pure fatigue testing and pure stress corrosion testing. However, there is a lack of evaluation equipment and methods for assessing the impact of simulated surface thermal shock loads on stress corrosion behavior. Similar patents mainly include methods for identifying transient fatigue in pipelines in the field and for overall hot-cold alternation testing. For example, Chinese Patent Publication No. CN117113750A discloses a method for fatigue analysis and damage management of primary loop pipelines in nuclear power plants based on digital twins. This method classifies and manages transients in the primary loop of nuclear power plants based on their occurrence frequency, performs fatigue analysis on each type of transient, and optimizes the operation control of nuclear power plants based on digital twins. However, this method does not involve specific evaluation tests and cannot be used for evaluating stress corrosion behavior. Chinese Patent Publication No. CN116465723A discloses a multi-field coupled stress corrosion test device and test method for tension wires. The test device can simulate the effects of factors such as wet-dry cycles, freeze-thaw cycles, monotonic / cyclic loading, or coupled salt corrosion environments on the stress corrosion performance of wires such as prestressed steel bars, steel strands, and anchor cables, and explore the corrosion degree and corrosion evolution law of tension wires. However, this patent realizes the overall cooling or heating, and cannot be used to evaluate the stress corrosion behavior of the surface under alternating loads under thermal shock. Therefore, it is not suitable for evaluating the stress corrosion behavior under simulated thermal shock in high-temperature and high-pressure water environments. Similarly, the stress corrosion testing device and working method for materials under simulated marine environment disclosed in Chinese Patent Publication No. CN118010610A evaluates stress corrosion behavior under overall salt spray and dry conditions in marine environments. The stress corrosion testing device and method for steel under constant load under periodic immersion conditions disclosed in Chinese Patent Publication No. CN112903497A evaluates stress corrosion behavior under periodic cycles between corrosive solution immersion and high-temperature drying. Neither of these methods is suitable for evaluating stress corrosion behavior under thermal shock in high-temperature and high-pressure water environments. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a stress corrosion testing device and a testing method for simulating surface thermal shock load.

[0005] The technical solution adopted by the present invention to solve its technical problem is: to construct a stress corrosion test device for simulating surface thermal shock load, which includes a stress corrosion load module, a thermal shock load module and a high temperature and high pressure water system; The stress corrosion load module is used to apply a stable stress load to the test sample, the thermal shock load module is used to apply a periodic rolling load to the surface of the test sample to simulate the thermal shock effect, and the high temperature and high pressure water system is used to achieve the target temperature and pressure required for the test.

[0006] In some embodiments, the stress corrosion loading module includes a stress corrosion loader, a stress corrosion loader connecting rod, an autoclave base, a lower stress corrosion clamp, a lower stress corrosion clamp pin, an upper stress corrosion clamp pin, an upper stress corrosion clamp, an upper stress corrosion clamp connecting rod, an autoclave support column, a support top plate, and a connecting rod locking nut. The stress corrosion loader is connected to the stress corrosion lower fixture via a stress corrosion loader connecting rod. The stress corrosion lower fixture is connected to the lower end of the test sample via a stress corrosion lower fixture pin. The upper end of the test sample is connected to the stress corrosion upper fixture via a stress corrosion upper fixture pin. The stress corrosion upper fixture is connected to the support top plate via a stress corrosion upper fixture connecting rod. The support top plate is fixed to the pressure vessel base via the pressure vessel support column. The connecting rod locking nut is used to lock the stress corrosion upper fixture connecting rod.

[0007] In some embodiments, the thermal shock load module includes a thermal shock load loader, a thermal shock load loading connecting rod, a thermal shock load loading adapter plate, a thermal shock load transmission rod, a clamping connecting plate, a clamping spring positioning nut, a clamping rod, a clamping spring, and a cylindrical pressure head; The thermal shock load loading machine is connected to the thermal shock load loading adapter plate via the thermal shock load loading connecting rod. The thermal shock load loading adapter plate is connected to at least two thermal shock load transmission rods. The lower end of each thermal shock load transmission rod is connected to the clamping connecting plate. The clamping connecting plate is connected to the clamping rod. A clamping spring is sleeved on the clamping rod. The compression amount of the clamping spring is adjusted by the clamping spring positioning nut. The cylindrical pressure head is mounted on the clamping connecting plate and contacts the surface of the test sample.

[0008] In some embodiments, the thermal shock load loading adapter plate is provided with a through hole adapted to the thermal shock load transmission rod, the thermal shock load transmission rod is locked and fixed by a nut, and the thermal shock load transmission rod is threadedly connected to the clamping connection plate.

[0009] In some embodiments, the cylindrical pressure head is rotatably connected to the pressing connecting plate via a positioning pin, and the cylindrical pressure head can rotate and roll as the pressing connecting plate moves up and down; The number of cylindrical pressure heads is multiple.

[0010] In this embodiment, a test method for a stress corrosion test apparatus simulating surface thermal shock load is also constructed. Based on the aforementioned stress corrosion test apparatus simulating surface thermal shock load, the method includes the following steps: S1: Install the stress corrosion load module; S2: Start the stress corrosion loader, set the target load through the software, and transfer the stress corrosion load to the test sample through the stress corrosion loader connecting rod and the stress corrosion fixture, so that the test sample reaches the preset stress state. S3: Install the thermal shock load module; S4: Start the high-temperature and high-pressure water system to bring the temperature and pressure in the closed test space up to the target test parameters; S5: Start the thermal shock load loader. Set the amplitude, frequency and cycle parameters through the software. The thermal shock load is transmitted to the cylindrical indenter through the thermal shock load loading connecting rod, thermal shock load loading adapter plate, thermal shock load transmission rod and clamping connecting plate, so that the cylindrical indenter performs periodic rolling on the surface of the test sample. S6: When the preset thermal shock cycle is reached or the test sample breaks, stop the test, cool down and depressurize, and then remove the sample. S7: Conduct experimental analysis on the test samples.

[0011] In some embodiments, in step S1, the stress corrosion loading machine connecting rod and the stress corrosion lower fixture are first installed. Then, the stress corrosion upper fixture connecting rod is passed through the support top plate and suspended by the connecting rod locking nut. The stress corrosion upper fixture is installed on the stress corrosion upper fixture connecting rod. The connecting rod locking nut is adjusted to control the distance between the stress corrosion upper fixture and the stress corrosion lower fixture. Then, the test sample is fixed on the stress corrosion lower fixture and the stress corrosion upper fixture respectively by the stress corrosion lower fixture pin and the stress corrosion upper fixture pin.

[0012] In some embodiments, step S3 includes: S31: Connect the thermal shock load loading connecting rod to the thermal shock load loading machine, and then install the thermal shock load loading adapter plate onto the thermal shock load loading connecting rod; S32: Install the thermal shock load transfer rod onto the thermal shock load loading adapter plate; S33: Install the cylindrical indenter onto the clamping connection plate using locating pins, with each pair of thermal shock load transmission rods corresponding to one clamping connection plate; S34: Install the clamping connecting plate below the thermal shock load transmission rod, adjust the height of the clamping connecting plate so that the cylindrical indenter corresponds to the center position of the test sample, and adjust multiple clamping connecting plates to be parallel to each other; S35: Pass the clamping rod through the clamping connecting plate, fit a clamping spring at both ends of each clamping rod, and install the clamping spring positioning nut; S36: Based on the required clamping force for the test and the elastic coefficient of the clamping spring at the test temperature, calculate the target compression of the spring.

[0013] In some embodiments, in step S36, when adjusting the compression amount of the compression spring, the positioning nut of the compression spring is adjusted in a diagonal alternating compression manner so that each compression spring reaches the target compression amount.

[0014] In some embodiments, step S7 includes observing the crack initiation in the contact area between the test sample and the cylindrical indenter, and observing the inward propagation of the crack through a cross-section.

[0015] The present invention offers the following advantages: This stress corrosion testing device simulating surface thermal shock loads, by incorporating a stress corrosion load module, a thermal shock load module, and a high-temperature, high-pressure water system, achieves the synergistic effect of stable stress loads, periodic thermal shock simulation loads, and a high-temperature, high-pressure water environment, accurately replicating the service environment of primary loop auxiliary pipelines in nuclear power plants. It solves the problem that existing technologies cannot simultaneously simulate the coupling effect of surface thermal shock loads and stress corrosion, providing a more realistic testing platform for evaluating the stress corrosion behavior of materials, resulting in more accurate and valuable evaluation results. The testing method of this stress corrosion testing device simulating surface thermal shock loads is clear and logically rigorous, following a process of fixture installation, stress loading, thermal shock module installation, environmental parameter adjustment, thermal shock loading, test termination, and sample analysis, ensuring the orderly connection of each step. By setting parameters such as load, amplitude, and frequency through software, precise control of the testing process is achieved. The setting of test termination conditions balances testing efficiency and data integrity, enabling comprehensive acquisition of stress corrosion behavior data of materials at different testing stages. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present invention and therefore should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort. In the drawings: Figure 1 This is a front view of the overall structure of the stress corrosion testing apparatus for simulating surface thermal shock loads in some embodiments of the present invention; Figure 2 This is a side view of the overall structure of the stress corrosion testing apparatus for simulating surface thermal shock loads in some embodiments of the present invention; Figure 3 This is a schematic diagram of the distribution of multiple cylindrical pressure heads in some embodiments of the present invention. Detailed Implementation

[0017] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific embodiments are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the orientations or positional relationships indicated by terms such as "front," "rear," "upper," "lower," "left," "right," "longitudinal," "horizontal," "vertical," "horizontal," "top," "bottom," "inner," "outer," "head," and "tail" are based on the orientations or positional relationships shown in the accompanying drawings, and are constructed and operated in a specific orientation. They are only for the convenience of describing this technical solution and do not indicate that the device or element referred to must have a specific orientation; therefore, they should not be construed as limitations on this invention.

[0018] It should also be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. When an component is referred to as being "on" or "below" another component, the component can be located "directly" or "indirectly" on the other component, or there may be one or more intermediary components. The terms "first," "second," "third," etc., are only for the convenience of describing this technical solution and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," "third," etc., may explicitly or implicitly include one or more of that feature. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0019] Please see Figures 1 to 3 This is a stress corrosion testing device for simulating surface thermal shock loads, as described in some embodiments of the present invention. It includes a stress corrosion load module, a thermal shock load module, and a high-temperature, high-pressure water system. The stress corrosion load module applies a stable stress load to the test sample 6, while the thermal shock load module applies a periodic rolling load to the surface of the test sample 6 to simulate the thermal shock effect. The stress corrosion load module and the thermal shock load module work synergistically on the same test sample 6. The high-temperature, high-pressure water system is used to achieve the target temperature and pressure required for the test.

[0020] Understandably, this stress corrosion testing device simulating surface thermal shock loads, by setting up a stress corrosion load module, a thermal shock load module, and a high-temperature, high-pressure water system, achieves the synergistic effect of stable stress loads, periodic thermal shock simulation loads, and a high-temperature, high-pressure water environment, accurately replicating the service environment of primary loop auxiliary pipelines in nuclear power plants. It solves the problem that existing technologies cannot simultaneously simulate the coupling effect of surface thermal shock loads and stress corrosion, providing a more realistic testing platform for evaluating the stress corrosion behavior of materials, resulting in more accurate and valuable evaluation results.

[0021] The stress corrosion loading module includes a stress corrosion loader 1, a stress corrosion loader connecting rod 2, an autoclave base 3, a lower stress corrosion clamp 4, a lower stress corrosion clamp pin 5, an upper stress corrosion clamp pin 7, an upper stress corrosion clamp 8, an upper stress corrosion clamp connecting rod 9, an autoclave support column 10, a support top plate 11, and a connecting rod locking nut 12. The stress corrosion loader 1 is connected to the lower stress corrosion clamp 4 via the stress corrosion loader connecting rod 2. The lower stress corrosion clamp 4 is connected to the lower end of the test sample 6 via the lower stress corrosion clamp pin 5. The upper end of the test sample 6 is connected to the upper stress corrosion clamp 8 via the upper stress corrosion clamp pin 7. The upper stress corrosion clamp 8 is connected to the support top plate 11 via the upper stress corrosion clamp connecting rod 9. The support top plate 11 is fixed to the autoclave base 3 via the autoclave support column 10. The connecting rod locking nut 12 is used to lock the upper stress corrosion clamp connecting rod 9.

[0022] Specifically, the stress corrosion loader 1 is used to apply the stress load required for the stress corrosion test. The main function of the stress corrosion loader connecting rod 2 is to transfer the stress load applied by the stress corrosion loader 1 through the autoclave base 3 and then to the stress corrosion lower clamp 4 inside the autoclave. The stress corrosion lower clamp 4 is connected to the test sample 6 through the stress corrosion lower clamp pin 5, transferring the stress load to the test sample 6. The upper part of the test sample 6 is connected to the stress corrosion upper clamp 8 through the stress corrosion upper clamp pin 7. The stress corrosion upper clamp 8 is fixed to the support top plate 11 through the stress corrosion upper clamp connecting rod 9 and the connecting rod locking nut 12. The support top plate 11 is fixed to the autoclave base 3 through the autoclave support column 10. The specific composition and connection relationship of the stress corrosion load module, through the coordinated cooperation of multiple components, realizes the application of a stable stress load to the test sample 6. The clamp and the sample are connected by pins, and the locking and fixing with the connecting rod locking nut 12 ensures the stability and reliability of stress transmission, avoids test errors caused by load transmission deviation during the test, and improves the repeatability and accuracy of the test. Meanwhile, the overall structural design is reasonable, making it easy to install and disassemble, and reducing the difficulty of experimental operations.

[0023] The thermal shock load module includes a thermal shock load loader 13, a thermal shock load loading connecting rod 14, a thermal shock load loading adapter plate 15, a thermal shock load transmission rod 16, a clamping connecting plate 17, a clamping spring positioning nut 18, a clamping rod 19, a clamping spring 20, and a cylindrical pressure head 21. The thermal shock load loader 13 is connected to the thermal shock load loading adapter plate 15 via the thermal shock load loading connecting rod 14. The thermal shock load loading adapter plate 15 is connected to at least two thermal shock load transmission rods 16. The lower end of the thermal shock load transmission rod 16 is connected to the clamping connecting plate 17. The clamping connecting plate 17 is connected to the clamping rod 19. A clamping spring 20 is sleeved on the clamping rod 19. The compression amount of the clamping spring 20 is adjusted by the clamping spring positioning nut 18. The cylindrical pressure head 21 is mounted on the clamping connecting plate 17 and is in contact with the surface of the test sample 6.

[0024] Specifically, the thermal shock load loader 13 is used to apply a periodic load simulating the thermal shock effect. The thermal shock load loading connecting rod 14 transmits the oscillating motion to the thermal shock load loading adapter plate 15, which has four through holes for connecting four thermal shock load transmission rods 16. The thermal shock load transmission rods 16 are threaded at the through holes and tightened at both ends with nuts to prevent loosening during vibration. The lower ends of the thermal shock load transmission rods 16 are threaded to the clamping connecting plate 17. The clamping connecting plate 17 has four through holes for passing through clamping rods 19. A cylindrical pressure head 21 is connected to the center of the clamping connecting plate 17 via a locating pin. A clamping spring 20 is installed on the clamping rod 19, and the compression of the clamping spring 20 is adjusted by a clamping spring locating nut 18 on the outside. The head of the cylindrical pressure head 21 contacts the sample and can rotate with the up-and-down movement of the clamping connecting plate 17, subjecting the surface of the test sample 6 to the rolling action of the cylindrical pressure head 21.

[0025] Driven by the thermal shock load loader 13, the periodic motion is transmitted to the cylindrical indenter 21 through a multi-stage transmission component, achieving periodic rolling of the surface of the test sample 6 and accurately simulating the thermal shock effect. The design of the clamping spring 20 and the clamping spring positioning nut 18 allows for flexible adjustment of the clamping force to meet the load requirements under different test conditions. The arrangement of multiple thermal shock load transmission rods 16 ensures the uniformity of load transmission and avoids the influence of uneven local force on the test results. In addition, the thermal shock load loading adapter plate 15 has through holes adapted to the thermal shock load transmission rods 16, which are locked in place by nuts and threadedly connected to the clamping connection plate 17. The locking of the nuts at both ends effectively prevents the components from loosening due to vibration during the test, ensuring the stability and continuity of the thermal shock load transmission. The threaded connection structure between the thermal shock load transmission rods 16 and the clamping connection plate 17 is simple and reliable, facilitating installation, debugging, and subsequent maintenance, while also improving the overall structural strength and service life of the module.

[0026] The cylindrical indenter 21 is rotatably connected to the clamping connecting plate 17 via a locating pin. The cylindrical indenter 21 can rotate and roll as the clamping connecting plate 17 moves up and down. This rotatable connection reduces frictional damage between the indenter and the sample surface, better reflecting the stress state of the pipe surface during actual thermal shock. The rotational rolling method ensures the load is evenly applied to the sample surface, avoiding localized stress concentration and further improving the realism of the thermal shock simulation and the accuracy of the test results. To improve experimental efficiency, multiple cylindrical indenters 21 can be used. By setting multiple cylindrical indenters 21 and conducting multiple sets of tests in parallel, each cylindrical indenter 21 can be set with a different clamping force. A single test can obtain the influence of multiple clamping forces on the initiation of stress corrosion cracks.

[0027] In this embodiment, a test method for a stress corrosion test apparatus simulating surface thermal shock load is also constructed. Based on the aforementioned stress corrosion test apparatus simulating surface thermal shock load, the method includes the following steps: S1: Install the stress corrosion load module, that is, install the stress corrosion loader connecting rod 2, the stress corrosion lower clamp 4, the stress corrosion upper clamp connecting rod 9, and the stress corrosion upper clamp 8. Fix the test sample 6 between the stress corrosion lower clamp pin 5 and the stress corrosion upper clamp pin 7. S2: Start the stress corrosion loader 1, set the target load through the software, and transfer the stress corrosion load to the test sample 6 through the stress corrosion loader connecting rod 2 and the stress corrosion clamp 4, so that the test sample 6 reaches the preset stress state. S3: Install the thermal shock load module, that is, install the thermal shock load loading connecting rod 14, the thermal shock load loading adapter plate 15, the thermal shock load transmission rod 16, the clamping connecting plate 17 and the cylindrical pressure head 21, and adjust the clamping spring positioning nut 18 so that the clamping spring 20 reaches the preset compression amount. S4: Start the high-temperature and high-pressure water system to bring the temperature and pressure in the closed test space up to the target test parameters; S5: Start the thermal shock load loader 13, and set the amplitude, frequency and cycle parameters through the software. The thermal shock load is transmitted to the cylindrical pressure head 21 through the thermal shock load loading connecting rod 14, thermal shock load loading adapter plate 15, thermal shock load transmission rod 16 and clamping connecting plate 17, so that the cylindrical pressure head 21 performs periodic rolling on the surface of the test sample 6. S6: When the preset number of thermal shock cycles is reached or the test sample 6 breaks, stop the test, cool down and depressurize, and then remove the sample. S7: Conduct experimental analysis on test sample 6.

[0028] The stress corrosion testing apparatus for simulating surface thermal shock loading presents a clear and logically rigorous testing method. The experiment follows a sequence of steps: fixture installation, stress loading, thermal shock module installation, environmental parameter adjustment, thermal shock loading, test termination, and sample analysis, ensuring seamless integration of each stage. By setting parameters such as load, amplitude, and frequency through software, precise control of the testing process is achieved. The defined test termination conditions balance experimental efficiency and data integrity, enabling comprehensive acquisition of stress corrosion behavior data of materials at different testing stages.

[0029] In step S1, first install the stress corrosion loader connecting rod 2 and the stress corrosion lower clamp 4. Then, pass the stress corrosion upper clamp connecting rod 9 through the support top plate 11 and suspend it through the connecting rod locking nut 12. Install the stress corrosion upper clamp 8 onto the stress corrosion upper clamp connecting rod 9. Adjust the connecting rod locking nut 12 to control the distance between the stress corrosion upper clamp 8 and the stress corrosion lower clamp 4. Then, fix the test sample 6 onto the stress corrosion lower clamp 4 and the stress corrosion upper clamp 8 respectively through the stress corrosion lower clamp pin 5 and the stress corrosion upper clamp pin 7. Specifically, first install the stress corrosion loader connecting rod 2, then install the stress corrosion lower clamp 4. Then, pass the stress corrosion upper clamp connecting rod 9 through the support top plate 11 and suspend it through the connecting rod locking nut 12. Finally, install the stress corrosion upper clamp 8 onto the stress corrosion upper clamp connecting rod 9. Next, install the test sample 6. By adjusting the locking nut 12 of the connecting rod, control the distance between the upper stress corrosion fixture 8 and the lower stress corrosion fixture 4, so that the test sample 6 can be fixed to the upper stress corrosion fixture 8 by the upper stress corrosion fixture pin 7 and fixed to the lower stress corrosion fixture 4 by the lower stress corrosion fixture pin 5.

[0030] Step S3 includes: S31: Connect the thermal shock load loading connecting rod 14 to the thermal shock load loading machine 13, then install the thermal shock load loading adapter plate 15 onto the thermal shock load loading connecting rod 14 and fix it with nuts on both sides; S32: Install the thermal shock load transfer rod 16 onto the thermal shock load loading adapter plate 15 and secure it on both sides with nuts; S33: Install the cylindrical pressure head 21 onto the clamping connection plate 17 using the positioning pin. Each pair of thermal shock load transmission rods 16 corresponds to one clamping connection plate 17. S34: Install the clamping connecting plate 17 below the thermal shock load transmission rod 16, adjust the height of the clamping connecting plate 17 so that the cylindrical indenter 21 corresponds to the center position of the test sample 6, and adjust the multiple clamping connecting plates 17 to be parallel to each other. S35: Pass the clamping rod 19 through the clamping connecting plate 17, and fit a clamping spring 20 at both ends of each clamping rod 19, and install the clamping spring positioning nut 18; S36: Based on the required clamping force for the test and the elastic coefficient of the clamping spring 20 at the test temperature, calculate the target compression of the spring.

[0031] The specific implementation of step S3 is as follows: First, connect the thermal shock load loading connecting rod 14 to the thermal shock load loading machine 13. Then, install the thermal shock load loading adapter plate 15 onto the thermal shock load loading connecting rod 14 and fix it with nuts on both sides. Next, install the four thermal shock load transmission rods 16 onto the thermal shock load loading adapter plate 15, and also tighten them with nuts on both sides. Then, install the two cylindrical pressure heads 21 onto the clamping connecting plate 17 through positioning pins. Then, install the clamping connecting plate 17 below the thermal shock load transmission rods 16, with each pair of thermal shock load transmission rods 16 corresponding to one clamping connecting plate 17. The height of the clamping connecting plate 17 needs to be adjusted so that the cylindrical pressure head 21 corresponds to the center position of the test sample 6. The two clamping connecting plates 17 on the left and right sides need to be adjusted to be parallel to each other to prevent eccentricity. Then, pass the four clamping rods 19 through the two clamping connecting plates 17. Next, attach compression springs 20 to both ends of each compression rod 19, and then install compression spring positioning nuts 18 to compress and fix the compression springs 20. The compression amount of the compression springs 20 needs to be set according to the test conditions. For example, if a compression force of 20N is required, then the springs on each compression rod 19 need to apply a force of 5N. Then, according to Hooke's law and combined with the elastic coefficient of the compression springs 20 at the test temperature, the compression amount of the compression springs 20 is calculated. For example, if each compression spring 20 needs to be compressed by 5mm, then adjust each compression spring positioning nut 18 to make the compression amount of the compression springs 20 reach 5mm.

[0032] In step S36, when adjusting the compression of the clamping springs 20, the clamping spring positioning nuts 18 are adjusted in a diagonal alternating compression manner to ensure that each clamping spring 20 reaches the target compression. Adjusting the compression of the clamping springs 20 using a diagonal alternating compression method effectively avoids uneven force distribution or eccentricity problems during the installation of the clamping springs 20, ensuring that the compression of each clamping spring 20 is consistent, thereby guaranteeing a uniform distribution of the clamping force applied to the sample surface by the cylindrical indenter 21. This adjustment method is simple to operate and has significant effects, further improving the uniformity and stability of the thermal shock load application, and providing a guarantee for the accuracy of the test results.

[0033] In step S7, the experimental analysis includes observing the crack initiation at the contact area between the test sample 6 and the cylindrical indenter 21 via surface observation, and observing the inward propagation of the crack via cross-section. The combined approach of surface and cross-sectional observation allows for comprehensive acquisition of information on crack initiation and propagation. Surface observation provides a direct view of the crack initiation location, number, and morphology, while cross-sectional observation offers in-depth analysis of crack propagation depth and path. The combination of these two methods makes the experimental analysis results more comprehensive and accurate, providing rich data support for evaluating the stress corrosion performance of materials and contributing to a deeper understanding of the influence mechanism of thermal shock loads on the stress corrosion behavior of materials.

[0034] This invention, through the synergistic effect of a stress corrosion load module, a thermal shock load module, and a high-temperature, high-pressure water system, accurately simulates the service environment of primary loop auxiliary pipelines in nuclear power plants. It can accurately evaluate the stress corrosion behavior of materials under surface thermal shock loads, providing reliable experimental data support for the safety design and life assessment of nuclear power pipelines. Furthermore, the device has a reasonable structural design, is easy to operate, and has standardized experimental procedures, demonstrating good practicality and potential for wider application.

[0035] It is understood that the above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can freely combine the above technical features without departing from the concept of the present invention, and can also make several modifications and improvements, all of which fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made with respect to the scope of the claims of the present invention should fall within the scope of the claims of the present invention.

Claims

1. A stress corrosion testing apparatus for simulating surface thermal shock loads, characterized in that, Includes a stress corrosion load module, a thermal shock load module, and a high-temperature, high-pressure water system; The stress corrosion load module is used to apply a stable stress load to the test sample (6), the thermal shock load module is used to apply a periodic rolling load to the surface of the test sample (6) to simulate the thermal shock effect, and the high temperature and high pressure water system is used to achieve the target temperature and pressure required for the test.

2. The stress corrosion testing apparatus for simulating surface thermal shock loads according to claim 1, characterized in that, The stress corrosion load module includes a stress corrosion loader (1), a stress corrosion loader connecting rod (2), an autoclave base (3), a stress corrosion lower clamp (4), a stress corrosion lower clamp pin (5), a stress corrosion upper clamp pin (7), a stress corrosion upper clamp (8), a stress corrosion upper clamp connecting rod (9), an autoclave support column (10), a support top plate (11), and a connecting rod locking nut (12). The stress corrosion loading machine (1) is connected to the stress corrosion lower clamp (4) via the stress corrosion loading machine connecting rod (2). The stress corrosion lower clamp (4) is connected to the lower end of the test sample (6) via the stress corrosion lower clamp pin (5). The upper end of the test sample (6) is connected to the stress corrosion upper clamp (8) via the stress corrosion upper clamp pin (7). The stress corrosion upper clamp (8) is connected to the support top plate (11) via the stress corrosion upper clamp connecting rod (9). The support top plate (11) is fixed to the high pressure vessel base (3) via the high pressure vessel support column (10). The connecting rod locking nut (12) is used to lock the stress corrosion upper clamp connecting rod (9).

3. The stress corrosion testing apparatus for simulating surface thermal shock loads according to claim 2, characterized in that, The thermal shock load module includes a thermal shock load loader (13), a thermal shock load loading connecting rod (14), a thermal shock load loading adapter plate (15), a thermal shock load transmission rod (16), a clamping connecting plate (17), a clamping spring positioning nut (18), a clamping rod (19), a clamping spring (20), and a cylindrical pressure head (21). The thermal shock load loading machine (13) is connected to the thermal shock load loading adapter plate (15) via the thermal shock load loading connecting rod (14). The thermal shock load loading adapter plate (15) is connected to at least two thermal shock load transmission rods (16). The lower end of the thermal shock load transmission rod (16) is connected to the clamping connecting plate (17). The clamping connecting plate (17) is connected to the clamping rod (19). The clamping spring (20) is sleeved on the clamping rod (19). The compression amount of the clamping spring (20) is adjusted by the clamping spring positioning nut (18). The cylindrical pressure head (21) is installed on the clamping connecting plate (17). The cylindrical pressure head (21) is in contact with the surface of the test sample (6).

4. The stress corrosion testing apparatus for simulating surface thermal shock loads according to claim 3, characterized in that, The thermal shock load transfer plate (15) is provided with a through hole that is adapted to the thermal shock load transmission rod (16). The thermal shock load transmission rod (16) is locked and fixed by a nut. The thermal shock load transmission rod (16) is threadedly connected to the pressing connection plate (17).

5. The stress corrosion testing apparatus for simulating surface thermal shock loads according to claim 3, characterized in that, The cylindrical pressure head (21) is rotatably connected to the pressing connecting plate (17) via a positioning pin. The cylindrical pressure head (21) can rotate and roll as the pressing connecting plate (17) moves up and down. The number of cylindrical pressure heads (21) is multiple.

6. A test method for a stress corrosion testing apparatus simulating surface thermal shock load, based on the stress corrosion testing apparatus for simulating surface thermal shock load as described in any one of claims 1 to 5, characterized in that, Including the following steps: S1: Install the stress corrosion load module; S2: Start the stress corrosion loader (1), set the target load through the software, and transfer the stress corrosion load to the test sample (6) through the stress corrosion loader connecting rod (2) and the stress corrosion clamp (4) so ​​that the test sample (6) reaches the preset stress state; S3: Install the thermal shock load module; S4: Start the high-temperature and high-pressure water system to bring the temperature and pressure in the closed test space up to the target test parameters; S5: Start the thermal shock load loading machine (13), set the amplitude, frequency and cycle parameters through the software, and the thermal shock load is transmitted to the cylindrical indenter (21) through the thermal shock load loading connecting rod (14), thermal shock load loading adapter plate (15), thermal shock load transmission rod (16) and clamping connecting plate (17), so that the cylindrical indenter (21) performs periodic rolling on the surface of the test sample (6); S6: When the preset thermal shock cycle is reached or the test sample (6) breaks, stop the test, cool down and depressurize, and then remove the sample; S7: Conduct experimental analysis on the test sample (6).

7. The test method of the stress corrosion test apparatus for simulating surface thermal shock load according to claim 6, characterized in that, In step S1, first install the stress corrosion loading machine connecting rod (2) and the stress corrosion lower clamp (4), then pass the stress corrosion upper clamp connecting rod (9) through the support top plate (11) and suspend it through the connecting rod locking nut (12), install the stress corrosion upper clamp (8) on the stress corrosion upper clamp connecting rod (9), adjust the connecting rod locking nut (12) to control the distance between the stress corrosion upper clamp (8) and the stress corrosion lower clamp (4), and then fix the test sample (6) on the stress corrosion lower clamp pin (5) and the stress corrosion upper clamp pin (7) respectively.

8. The test method of the stress corrosion test apparatus for simulating surface thermal shock load according to claim 6, characterized in that, Step S3 includes: S31: Connect the thermal shock load loading connecting rod (14) to the thermal shock load loading machine (13), and then install the thermal shock load loading adapter plate (15) onto the thermal shock load loading connecting rod (14); S32: Install the thermal shock load transfer rod (16) onto the thermal shock load loading adapter plate (15); S33: Install the cylindrical pressure head (21) onto the clamping connection plate (17) through the positioning pin. Each pair of thermal shock load transmission rods (16) corresponds to one clamping connection plate (17). S34: Install the clamping connection plate (17) below the thermal shock load transmission rod (16), adjust the height of the clamping connection plate (17) so that the cylindrical indenter (21) corresponds to the center position of the test sample (6), and adjust the multiple clamping connection plates (17) to be parallel to each other; S35: Pass the clamping rod (19) through the clamping connecting plate (17), and put the clamping spring (20) on both ends of each clamping rod (19) and install the clamping spring positioning nut (18). S36: Based on the required clamping force for the test and the elastic coefficient of the clamping spring (20) at the test temperature, the target compression of the spring is calculated.

9. The test method of the stress corrosion test apparatus for simulating surface thermal shock load according to claim 8, characterized in that, In step S36, when adjusting the compression amount of the compression springs (20), the positioning nut (18) of the compression springs is adjusted in a diagonal alternating compression manner so that each compression spring (20) reaches the target compression amount.

10. The test method of the stress corrosion test apparatus for simulating surface thermal shock load according to claim 6, characterized in that, In step S7, the experimental analysis includes observing the crack initiation in the contact area between the test sample (6) and the cylindrical indenter (21) on the surface, and observing the inward propagation of the crack through the cross section.

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