Method for determining the ductile-brittle transition temperature of an ion-irradiated material layer of a sample

Abstract

Embodiments of the present application relate to the field of testing strength characteristics of solid materials with mechanical stress, and in particular to a method for determining a ductile-brittle transition temperature of an ion-irradiated material layer of a sample, comprising: irradiating the sample; performing a temperature-controlled small punch test on the irradiated sample to obtain load-displacement data of the sample at different temperatures, and determining mechanical properties of the ion-irradiated material layer of the sample at different temperatures according to the load-displacement data using inverse finite element; determining a deformation energy of the ion-irradiated material layer of the sample within a preset displacement limit range after a maximum load point according to the mechanical properties; and determining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample according to the deformation energy. The method realizes determination of the ductile-brittle transition temperature of the ion-irradiated material layer of the sample; and the method can determine both a higher ductile-brittle transition temperature and a lower ductile-brittle transition temperature, thereby facilitating comprehensive study of the ductile-brittle transition temperature of the metal material.

Description

Technical Field

[0001] Embodiments of this application relate to the field of testing the strength properties of solid materials using mechanical stress, and more specifically to a method for determining the ductile-brittle transition temperature of an ion-irradiated material layer of a sample. Background Technology

[0002] The statements herein are provided merely as background information in connection with this application and do not necessarily constitute prior art.

[0003] The reactor is a neutron irradiation environment. Neutron irradiation causes the ductile-brittle transition temperature of the reactor's metallic materials to increase. This increase in the ductile-brittle transition temperature of metallic materials threatens the safety of the metallic materials and, consequently, the safety of the reactor. Therefore, it is necessary to study the ductile-brittle transition temperature of metallic materials after neutron irradiation.

[0004] However, since neutron irradiation of metallic materials results in low damage rates and easily produces radioactive residues, ion irradiation is currently commonly used to treat samples made of metallic materials and determine the ductile-brittle transition temperature of the irradiated samples to simulate neutron irradiation of metallic materials in a reactor, thereby studying the ductile-brittle transition temperature of metallic materials after neutron irradiation.

[0005] However, current techniques for determining the ductile-brittle transition temperature of materials after ion irradiation still have many limitations. Summary of the Invention

[0006] A brief overview of this application is provided below to offer a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of the application. It is not intended to identify key or essential parts of the application, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0007] To address the aforementioned problems, embodiments of this application provide a method for determining the ductile-brittle transition temperature of an ion-irradiated material layer of a sample, comprising the following steps: S10: irradiating the sample; S20: performing a temperature-controlled small-pump experiment on the irradiated sample to obtain load-displacement data of the sample at different temperatures; S30: determining the mechanical properties of the ion-irradiated material layer of the sample at different temperatures using inverse finite element method based on the load-displacement data; S40: determining the deformation energy within the range from the maximum load point to a preset displacement limit of the ion-irradiated material layer of the sample based on the mechanical properties; S50: determining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample based on the deformation energy.

[0008] The method provided in the embodiments of this application acquires load-displacement data of the irradiated sample at different temperatures and uses the inverse finite element method to determine the mechanical properties of the ion-irradiated material layer of the sample at different temperatures based on the load-displacement data. Thus, based on the mechanical properties, the deformation energy and the ductile-brittle transition temperature of the ion-irradiated material layer of the sample from the maximum load point to the preset displacement limit range can be determined, thereby realizing the determination of the ductile-brittle transition temperature of the ion-irradiated material layer of the sample.

[0009] In related technologies, the small punch test is usually used to determine the ductile-brittle transition temperature of a material. However, due to the influence of liquid nitrogen temperature control, the small punch test in related technologies is difficult to determine the ductile-brittle transition temperature of some metallic materials with low ductile-brittle transition temperatures.

[0010] Compared to the small-pump test in related technologies, the method provided in the embodiments of this application performs a temperature-controlled small-pump test on the irradiated sample and obtains the load-displacement data of the sample at different temperatures. Based on the load-displacement data of the sample at different temperatures, the ductile-brittle transition temperature of the ion-irradiated material layer of the sample is determined. This allows the method provided in the embodiments of this application to determine the ductile-brittle transition temperature of certain metallic materials with high ductile-brittle transition temperatures, as well as the ductile-brittle transition temperature of certain metallic materials with low ductile-brittle transition temperatures. This facilitates a comprehensive study of the ductile-brittle transition temperature of metallic materials using the method provided in the embodiments of this application. Attached Figure Description

[0011] Other objects and advantages of this application will become apparent from the following description of embodiments of this application with reference to the accompanying drawings, and will help to provide a comprehensive understanding of this application.

[0012] Figure 1 These are the load-displacement data of the irradiated sample at a certain temperature.

[0013] Figure 2 This is a schematic diagram of the low-temperature brittle segment fitting line, which shows the relationship between deformation energy and test temperature in the low-temperature brittle segment, and the high-temperature toughness segment fitting line, which shows the relationship between deformation energy and test temperature in the high-temperature toughness segment, determined using the method provided in the embodiments of this application.

[0014] Figure 3 These are load-displacement data for irradiated samples at different temperatures.

[0015] Figure 4 This is a schematic diagram of the small punch experimental apparatus used in the method provided in the embodiments of this application.

[0016] Explanation of reference numerals in the attached figures: 100. Small punch experimental apparatus; 10. Fixture; 20. Punch rod; 30. Chamber; 301. Nitrogen inlet; 40. Connecting rod; 50. Temperature control device.

[0017] It should be noted that the accompanying drawings are not necessarily drawn to scale, but are shown only in a schematic manner without affecting the reader's understanding. Detailed Implementation

[0018] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from the content of this application.

[0019] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the equipment structure and / or processing steps closely related to the solution according to this application are shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0020] When treating metallic materials with ion irradiation, because the penetrating power of ion irradiation is lower than that of neutron irradiation, only a portion of the sample thickness is irradiated. Usually, to study the ductile-brittle transition temperature of metallic materials, the ductile-brittle transition temperature of the irradiated portion of the sample should be determined. However, the methods in related technologies are usually used to determine the overall ductile-brittle transition temperature of the sample, which means that the methods in related technologies cannot determine the ductile-brittle transition temperature of the portion of the sample that is irradiated with ions.

[0021] To address the aforementioned issues, embodiments of this application provide a method for determining the ductile-brittle transition temperature of an ion-irradiated material layer in a sample.

[0022] The method for determining the ductile-brittle transition temperature of an ion-irradiated material layer of a sample according to embodiments of this application may include the following steps: S10: irradiating the sample; S20: performing a temperature-controlled small-pump experiment on the irradiated sample to obtain load-displacement data of the sample at different temperatures; S30: determining the mechanical properties of the ion-irradiated material layer of the sample at different temperatures using inverse finite element method based on the load-displacement data; S40: determining the deformation energy of the ion-irradiated material layer of the sample within the range from the maximum load point to a preset displacement limit based on the mechanical properties; S50: determining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample based on the deformation energy.

[0023] The method provided in the embodiments of this application acquires load-displacement data of the irradiated sample at different temperatures and uses the inverse finite element method to determine the mechanical properties of the ion-irradiated material layer of the sample at different temperatures based on the load-displacement data. Thus, based on the mechanical properties, the deformation energy and the ductile-brittle transition temperature of the ion-irradiated material layer of the sample from the maximum load point to the preset displacement limit range can be determined, thereby realizing the determination of the ductile-brittle transition temperature of the ion-irradiated material layer of the sample.

[0024] In related technologies, the small punch test is usually used to determine the ductile-brittle transition temperature of a material. However, due to the influence of liquid nitrogen temperature control, the small punch test in related technologies is difficult to determine the ductile-brittle transition temperature of some metallic materials with low ductile-brittle transition temperatures.

[0025] Compared to the small-pump test in related technologies, the method provided in the embodiments of this application performs a temperature-controlled small-pump test on the irradiated sample and obtains the load-displacement data of the sample at different temperatures. Based on the load-displacement data of the sample at different temperatures, the ductile-brittle transition temperature of the ion-irradiated material layer of the sample is determined. This allows the method provided in the embodiments of this application to determine the ductile-brittle transition temperature of certain metallic materials with high ductile-brittle transition temperatures, as well as the ductile-brittle transition temperature of certain metallic materials with low ductile-brittle transition temperatures. This facilitates a comprehensive study of the ductile-brittle transition temperature of metallic materials using the method provided in the embodiments of this application.

[0026] The sample can be a structural material from the reactor, such as cladding material.

[0027] In some embodiments, in step S10, a high-energy heavy ion beam can be used to irradiate the sample through a gradient de-energizing device.

[0028] In some embodiments, in step S10, 20% of the sample thickness is irradiated while the remaining 80% is not irradiated, thereby forming a layered composite sample consisting of an irradiated layer and an unirradiated substrate.

[0029] Specifically, the thickness of the irradiated portion of the sample can be 25~100μm.

[0030] In some embodiments, in step S30, the mechanical properties of the ion-irradiated material layer of the sample at different temperatures can be determined based on the aforementioned determined changes by determining the change in load as a function of displacement data of the irradiated sample at a certain temperature.

[0031] Specifically, see Figure 1 , Figure 1 These are the load-displacement data of the irradiated sample at a certain temperature. Figure 1Curve 201 in the figure represents the change of load on the sample with displacement at that temperature; Figure 1 Point 21 on curve 201 represents the maximum load point of the ion-irradiated material layer of the sample, and the shaded area represents the preset displacement limit range, thus enabling the calculation based on... Figure 1 Curve 201 in the figure determines the mechanical properties of the ion-irradiated material layer of the sample at this temperature.

[0032] In some embodiments, in step S40, the preset displacement limit range can be the displacement range corresponding to the process in which the load borne by the ion-irradiated material layer of the sample decreases from the maximum load point to 80% of the maximum load point.

[0033] See Figure 2 , Figure 2 This is a schematic diagram of the low-temperature brittle segment fitting line, which shows the relationship between deformation energy and test temperature in the low-temperature brittle segment, and the high-temperature toughness segment fitting line, which shows the relationship between deformation energy and test temperature in the high-temperature toughness segment, determined using the method provided in the embodiments of this application. Figure 2 The fitted line 41 in the figure represents the fitted line for the relationship between deformation energy and test temperature in the low-temperature brittle segment. Figure 2 The fitting line 42 in the figure represents the fitting line for the relationship between deformation energy and test temperature in the high-temperature toughness section.

[0034] In some embodiments, step S50 may further include the following steps: S51: determining the low-temperature brittle segment fitting line for the relationship between deformation energy and test temperature in the low-temperature brittle segment; S52: determining the high-temperature toughness segment fitting line for the relationship between deformation energy and test temperature in the high-temperature toughness segment; S53: determining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample based on the low-temperature brittle segment fitting line and the high-temperature toughness segment fitting line.

[0035] In related technologies, the ductile-brittle transition temperature of a metal material is usually determined only by the low-temperature fitting line of the relationship between the deformation energy of the metal material in the low-temperature brittle range and the test temperature, or the high-temperature fitting line of the relationship between the deformation energy of the metal material in the high-temperature ductile range and the test temperature. This results in low accuracy of the determined ductile-brittle transition temperature of the metal material.

[0036] The embodiments of this application, by determining the low-temperature brittle segment fitting line (relationship between deformation energy and test temperature in the low-temperature brittle segment) and the high-temperature toughness segment fitting line (relationship between deformation energy and test temperature in the high-temperature toughness segment), and determining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample based on the low-temperature brittle segment fitting line and the high-temperature toughness segment fitting line, can improve the accuracy of the determined ductile-brittle transition temperature of the ion-irradiated material layer of the sample. Simultaneously, by determining the low-temperature brittle segment fitting line and the high-temperature toughness segment fitting line, and then determining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample based on these fitting lines, the adverse effects of liquid nitrogen temperature control on small punch experiments can be overcome, thereby enabling the determination of the ductile-brittle transition temperature of certain metallic materials with relatively low ductile-brittle transition temperatures.

[0037] In some embodiments, in step S51 or S52, the deformation energy and the test temperature conform to the following relationship: .

[0038] In the formula, Let T represent the deformation energy, A and B represent the test temperature, and A and B represent the fitting parameters. In this embodiment, the above relationship makes the fitting lines for the low-temperature brittle segment determined in step S51 and the fitting lines for the high-temperature toughness segment determined in step S52 closer to the actual working conditions of the ion-irradiated material layer of the sample in the low-temperature brittle segment and the high-temperature toughness segment, thereby improving the accuracy of the determined fitting lines for the low-temperature brittle segment and the high-temperature toughness segment, and further improving the determined ductile-brittle transition temperature of the ion-irradiated material layer of the sample.

[0039] See Figure 2 In some embodiments, in step S53, the ductile-brittle transition temperature of the ion-irradiated material layer of the sample can be determined by the following steps: determining the intersection point of the low-temperature brittle segment fitting line and the high-temperature toughness segment fitting line based on the fitting line of the low-temperature brittle segment and the fitting line of the high-temperature toughness segment; and determining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample based on the temperature represented by the intersection point of the low-temperature brittle segment fitting line and the high-temperature toughness segment fitting line. In the embodiments of this application, by determining the temperature represented by the intersection point of the low-temperature brittle segment fitting line and the high-temperature toughness segment fitting line, the critical temperature at which the ion-irradiated material layer of the sample transitions from brittle to tough can be determined, i.e., the ductile-brittle transition temperature of the ion-irradiated material layer of the sample is determined; furthermore, by determining the temperature represented by the intersection point of the low-temperature brittle segment fitting line and the high-temperature toughness segment fitting line, the ductile-brittle transition temperature of the ion-irradiated material layer of the sample can be determined, which helps to reduce the difficulty of determining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample.

[0040] Specifically, see Figure 2 The ductile-brittle transition temperature of the ion-irradiated material layer of the sample can be determined by identifying the temperature corresponding to the intersection of fitting line 41 and fitting line 42.

[0041] In some embodiments, the temperature range in step S20 can be -180°C to 20°C. In such embodiments, the temperature range includes both the temperature at which the ion-irradiated material layer of the sample exhibits toughness and the temperature at which the ion-irradiated material layer of the sample exhibits brittleness. Therefore, performing small punch tests within this temperature range is beneficial for obtaining the ductile-brittle transition temperature of the ion-irradiated material layer of the sample from toughness to brittleness, and helps to improve the accuracy of the obtained ductile-brittle transition temperature.

[0042] In some embodiments, in step S20, the different temperatures can be -180°C, -140°C, -100°C, -60°C, -20°C, and 20°C, respectively. In such embodiments, the above temperature settings allow for multiple experiments to be conducted on both ion-irradiated material layers of samples exhibiting toughness and brittleness, ensuring that the experiments on the ion-irradiated material layers of the samples include the toughness-ductile-brittle transition and brittleness property transition process, which is beneficial to improving the accuracy of the determined ductile-brittle transition temperature. Furthermore, the above temperature settings, which increase in a 40°C gradient, are beneficial for fitting the deformation to the test temperature. Simultaneously, they are also beneficial for changing the test temperature when deviations occur in the load-displacement data corresponding to the test temperature, in order to obtain sufficient load-displacement data with deviations that meet the fitting requirements.

[0043] Specifically, see Figure 3 , Figure 3 These are load-displacement data for irradiated samples at different temperatures. Figure 3 Curves 31, 32, 33, 34, 35, and 36 represent the load-displacement variation of the irradiated sample at 20℃, -20℃, -60℃, -100℃, -140℃, and -180℃, respectively. Figure 3 It can be seen that the load on the irradiated samples at the aforementioned temperatures exhibits the same trend with displacement, both conforming to the laws of mechanics. Therefore, they can all be determined according to... Figure 3 The curves in the graph are used to determine the mechanical properties of the ion-irradiated material layer of the sample at the temperature corresponding to each curve.

[0044] See Figure 4 , Figure 4This is a schematic diagram of the small punch experimental apparatus 100 used in the method provided in the embodiments of this application. In some embodiments, in step S20, the small punch experimental apparatus 100 used for temperature-controlled small punch experiments on irradiated samples may include a clamp 10, a punch 20, a punching ball, a housing 30, a connecting rod 40, and a temperature control device 50. The clamp 10 is disposed inside the housing 30, and the sample is disposed inside the clamp 10; the punch 20 is connected to the connecting rod 40 and is configured to compress the punching ball; the connecting rod 40 passes through the temperature control device 50 and is connected to an external testing machine; the housing 30 has a liquid nitrogen inlet, and the temperature control device 50 is used to determine the current temperature of the housing 30 and, based on the current temperature and the desired temperature, determine the amount of liquid nitrogen input into the housing 30 to control the temperature inside the housing 30. In such an embodiment, by setting a temperature control device 50 to determine the amount of liquid nitrogen input into the chamber 30 based on the current temperature and the desired temperature, the temperature inside the chamber 30 can be controlled at the desired temperature so that the experiment can be carried out at the desired temperature. This helps to ensure the reliability and accuracy of the load-displacement data obtained from the experiment, and further helps to ensure the reliability and accuracy of the ductile-brittle transition temperature of the ion-irradiated material layer of the obtained sample.

[0045] In some embodiments, the liquid nitrogen inlet is configured to be connected to a liquid nitrogen supply unit outside the housing 30 via a pipeline, so that liquid nitrogen supplied by the liquid nitrogen supply unit can enter the housing 30 through the pipeline and the liquid nitrogen inlet to change the temperature inside the housing 30.

[0046] Liquid nitrogen supply components, for example, are self-pressurized liquid nitrogen tanks.

[0047] In some embodiments, the temperature control device 50 is disposed on the housing 30.

[0048] In some embodiments, the temperature control device 50 may include a control system disposed on the housing 30 and a temperature sensor disposed inside the housing 30, wherein the control system and the temperature sensor are communicatively connected. The control system is used to control the amount of liquid nitrogen input into the housing 30, and the temperature sensor is used to measure the current temperature inside the housing 30; the current temperature inside the housing 30 measured by the temperature sensor can be transmitted to the control system, so that the control system can control the rate at which liquid nitrogen is input into the housing 30 based on the temperature difference between the current temperature and the desired temperature.

[0049] The temperature sensor is, for example, a PT100 platinum resistance thermometer.

[0050] In some embodiments, the temperature control accuracy of the control system can be ±0.5℃.

[0051] In some embodiments, the connecting rod 40 is configured to pass through the housing 30 and connect to an external testing machine.

[0052] In some embodiments, the housing 30 is provided with a through hole for the connecting rod 40 to pass through, so that the connecting rod 40 can be connected to an external testing machine after passing through the through hole; a temperature control device is provided in the through hole formed in the housing 30.

[0053] In some embodiments, the chamber 30 has a nitrogen inlet 301. Before performing step S20, nitrogen is introduced into the chamber 30 through the nitrogen inlet 301, causing the air inside the chamber 30 to be expelled. In such an embodiment, by expelling the air inside the chamber 30 before performing step S20, moisture retention inside the chamber 30 can be avoided. This prevents condensation from forming on the surfaces of the clamp 10, the punch 20, the chamber 30, and the connecting rod 40 after liquid nitrogen is introduced into the chamber 30, thereby improving the accuracy of the load-displacement data of the acquired sample.

[0054] In some embodiments, the nitrogen inlet 301 is configured to be connected to a high-purity nitrogen supply via a pipeline, so that the nitrogen supplied by the high-purity nitrogen supply can enter the housing 30 through the pipeline and the nitrogen inlet 301.

[0055] In some embodiments, a continuous heating unit is integrated in the contact area between the connecting rod 40 and the temperature control device 50 to compensate for heat buildup on the connecting rod 40 and prevent frost formation on its surface. In this embodiment, by providing a continuous heating unit to compensate for heat buildup on the connecting rod 40, the surface temperature of the connecting rod 40 can be maintained above the ambient dew point temperature, preventing frost formation on the surface of the connecting rod 40. This avoids errors in the load-displacement data obtained in experiments due to frost formation on the connecting rod 40, ensuring the accuracy of the obtained load-displacement data, and thus ensuring the accuracy of the ductile-brittle transition temperature of the ion-irradiated material layer of the obtained sample.

[0056] In some embodiments, the continuous heating unit is disposed in the through hole formed in the housing 30.

[0057] In some embodiments, the continuous heating unit is configured to heat the connecting rod 40 in sections so that the temperature inside and outside the box 30 can change gradually, reducing the temperature gradient inside and outside the box 30, thereby reducing cold leakage inside the box 30 and helping to keep the temperature inside the box 30 stable for a long time.

[0058] In some embodiments, a continuous heating unit is activated before liquid nitrogen is introduced into the chamber 30 through the liquid nitrogen inlet, so as to prevent cold leakage and frost formation while the temperature inside the chamber 30 changes stably.

[0059] In some embodiments, the housing 30 is provided with a structure that cooperates with the slide rail, so that the housing 30 can move at different positions. Since the housing 30 is set on the base slide rail of the universal testing machine, the embodiments of this application, by providing a structure on the housing 30 that cooperates with the base slide rail of the universal testing machine, enable the housing 30 to move relative to the universal testing machine, so as to move the housing 30 to a position that is convenient for placing samples and to a position for conducting experiments, thereby facilitating sample injection into the housing 30 and facilitating the conduct of small punch tests.

[0060] In some embodiments, the housing 30 is configured to form a sealing door for sealing the housing 30 after a sample is placed inside the housing 30.

[0061] In some embodiments, when the sealing door opens the housing 30, the sample is placed inside the housing 30; after the sample is placed inside the housing 30, the sealing door closes the housing 30.

[0062] Regarding the embodiments of this application, it should also be noted that, without conflict, the embodiments of this application and the features in the embodiments can be combined with each other to obtain new embodiments.

[0063] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A method for determining the ductile-brittle transition temperature of an ion-irradiated material layer in a sample, characterized in that, It includes the following steps: S10: Irradiate the sample; S20: Perform a temperature-controlled small punch experiment on the irradiated sample to obtain load-displacement data of the sample at different temperatures; S30: Based on the load-displacement data, the mechanical properties of the ion-irradiated material layer of the sample at different temperatures are determined using the reverse finite element method. S40: Based on the mechanical properties, determine the deformation energy within the preset displacement limit range after the maximum load point of the ion-irradiated material layer of the sample; S50: Determine the ductile-brittle transition temperature of the ion-irradiated material layer of the sample based on the deformation energy.

2. The method according to claim 1, characterized in that, The S50 step also includes the following steps: S51: Determine the low-temperature brittle segment fitting line for the relationship between the deformation energy and the test temperature in the low-temperature brittle segment; S52: Determine the high-temperature toughness section fitting line for the relationship between the deformation energy and the test temperature in the high-temperature toughness section; S53: Determine the ductile-brittle transition temperature of the ion-irradiated material layer of the sample based on the fitting line of the low-temperature brittle segment and the fitting line of the high-temperature tough segment.

3. The method according to claim 2, characterized in that, In step S51 or S52, the deformation energy and the test temperature conform to the following relationship: ， In the formula, The deformation energy is represented by T, the test temperature is represented by A and B, and the fitting parameters are represented by B.

4. The method according to claim 2, characterized in that, In step S53, the ductile-brittle transition temperature of the ion-irradiated material layer of the sample is determined by the following steps: Based on the fitted line of the low-temperature brittle segment and the fitted line of the high-temperature tough segment, determine the intersection point of the fitted line of the low-temperature brittle segment and the fitted line of the high-temperature tough segment. The ductile-brittle transition temperature of the ion-irradiated material layer of the sample is determined based on the temperature represented by the intersection point.

5. The method according to claim 1, characterized in that, In step S20, the range of different temperatures is -180℃ to 20℃.

6. The method according to claim 5, characterized in that, In step S20, the different temperatures are -180℃, -140℃, -100℃, -60℃, -20℃, and 20℃.

7. The method according to claim 1, characterized in that, In step S20, the small punch experimental apparatus used for the temperature-controlled small punch experiment on the irradiated sample includes: Fixtures, punches, stamping balls, housing, connecting rods, and temperature control devices. The clamp is disposed inside the box, and the sample is disposed inside the clamp; The punch rod is connected to the connecting rod and is configured to compress the stamped ball. The connecting rod passes through the temperature control device and is connected to an external testing machine. The chamber has a liquid nitrogen inlet. The temperature control device is used to determine the current temperature of the chamber and, based on the current temperature and the desired temperature, determine the amount of liquid nitrogen to be input into the chamber in order to control the temperature inside the chamber.

8. The method according to claim 7, characterized in that, The chamber has a nitrogen inlet. Before performing step S20, nitrogen is introduced into the chamber through the nitrogen inlet, so that the air inside the chamber is expelled.

9. The method according to claim 7, characterized in that, A continuous heating unit is integrated in the contact area between the connecting rod and the temperature control device to compensate for the heat of the connecting rod and prevent frost from forming on its surface.

10. The method according to claim 7, characterized in that, The housing is equipped with a structure that cooperates with a slide rail, so that the housing can move in different positions.

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