Device and method for testing fracture toughness and crack propagation in molten salt environment

Abstract

The invention discloses a device and a method for testing fracture toughness and crack propagation in a molten salt environment, the device is used for testing a sample body, and the device for testing fracture toughness and crack propagation in the molten salt environment comprises a positioning assembly, a sliding assembly, a driving assembly, a loading assembly and a molten salt environment assembly. According to the device and the method for testing the fracture toughness and the crack propagation in the molten salt environment, the sample body is arranged in the molten salt environment assembly, so that the sample body is completely immersed in the molten salt environment, and the driving assembly is used for applying a torque load in the transverse direction to the sample body; meanwhile, the sliding assembly provides a guiding function for the transverse movement of the loading assembly, so that the fracture toughness and crack propagation test of the sample body in the molten salt corrosion environment can be realized.

Description

Technical Field

[0001] This invention relates to the field of nuclear power plant testing equipment, and in particular to a testing device and method for fracture toughness and crack propagation in a molten salt environment. Background Technology

[0002] With the transformation of China's energy structure, building a power system structure based on new clean energy sources is a major direction for my country's energy transformation. Solar energy, as a clean and renewable energy source, is considered one of the most promising power generation methods today. Concentrating solar power (CSP) is developing particularly rapidly. The temperature changes and corrosiveness of the high-temperature molten salt environment place high demands on the thermal fatigue performance and corrosion resistance of tank and pipeline materials. Therefore, studying the creep and creep fatigue crack propagation mechanical properties and mechanisms of structural materials in high-temperature molten salt environments, and evaluating the crack propagation capacity of materials in high-temperature molten salt environments, can provide theoretical basis and scientific guidance for the design, material selection, maintenance, repair, and replacement of equipment and pipelines in contact with molten salt in CSP power plants.

[0003] Traditional fracture toughness testing devices are mostly designed for ambient temperature or inert gas environments, and cannot simulate high-temperature corrosion conditions such as molten salt reactors and concentrated solar power. Existing vertical structures have shortcomings in high-temperature sealing, molten salt leakage prevention, and sample clamping stability. Existing crack propagation monitoring technologies (such as the DC potential method) are easily affected by corrosive media in molten salt environments, resulting in low accuracy. For the actual working conditions of molten salt thermal storage materials in high-temperature molten salt environments, there is an urgent need for a testing device and method that can accurately simulate fracture toughness and its interaction, monitor crack propagation in real time, and resist molten salt corrosion and leakage. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a test device and test method for fracture toughness and crack propagation in molten salt environment.

[0005] The technical solution adopted by the present invention to solve its technical problem is: to construct a fracture toughness and crack propagation test device in a molten salt environment for testing the specimen body, which includes a positioning component, a sliding component, a driving component, a loading component and a molten salt environment component;

[0006] The sliding component is mounted on the positioning component and movably connected to the positioning component. The driving component is mounted on the positioning component and connected to the sliding component. The loading component is connected to the sliding component and the sample body respectively. The sample body is disposed in the molten salt environment component. The molten salt environment component is used to provide a high-temperature molten salt environment for the sample body.

[0007] The driving component is used to move the sliding component so that the loading component can apply a lateral torque load to the sample body.

[0008] In some embodiments, the molten salt environment assembly includes a molten salt environment high-temperature furnace body, a molten salt tank disposed within the molten salt environment high-temperature furnace body, a heat insulation layer disposed within the molten salt environment high-temperature furnace body, a furnace body support frame connected to the side wall of the molten salt environment high-temperature furnace body, and a COD gauge connected to the molten salt environment high-temperature furnace body, wherein the other end of the furnace body support frame is connected to the positioning assembly.

[0009] The molten salt environment high-temperature furnace body is equipped with an inert gas inlet and an inert gas outlet.

[0010] In some embodiments, the molten salt tank is made of a nickel-based alloy coated with a high-temperature ceramic layer, and the heat insulation layer is a fireproof asbestos heat insulation layer.

[0011] In some embodiments, the positioning assembly includes a chassis, a column, a positioning beam, a connecting beam, and a base;

[0012] The upright is installed on the chassis, the positioning beam and the connecting beam are installed separately on the upright, and the base is installed on the bottom of the chassis.

[0013] In some embodiments, the sliding assembly includes a sliding connecting seat connected to the connecting beam, a slide rail connected to the sliding connecting seat, and a pair of sliders movably connected to the slide rail, wherein a steel ball is disposed between the sliders and the slide rail.

[0014] In some embodiments, the drive assembly includes an actuator, a load transmission connecting rod, and a pair of force transmission support rods;

[0015] The actuator is mounted on the positioning beam. The output end of the actuator is connected to the load transmission connecting rod and is used to drive the load transmission connecting rod to perform lifting and lowering movements. One end of the pair of force transmission support rods is simultaneously hinged to the load transmission connecting rod through a rotating component, and the other end of the pair of force transmission support rods is connected to the slider.

[0016] The chassis contains a servo controller that is electrically connected to the actuator.

[0017] In some embodiments, the loading assembly includes a pair of loading connectors separately connected to the pair of sliders, a loading fixture connected to the loading connectors, and a load sensor mounted on the loading connectors, wherein the sample body is mounted on the loading fixture;

[0018] The loading fixture and the molten salt environment high-temperature furnace body adopt a combination of bellows dynamic sealing and graphite gasket static sealing.

[0019] The loading connector is equipped with an inlet for a circulating water cooling system.

[0020] In this embodiment, a test method for a fracture toughness and crack propagation test apparatus in a molten salt environment is also constructed. This method is based on the aforementioned fracture toughness and crack propagation test apparatus in a molten salt environment and includes the following steps:

[0021] S1. Initial cracks of a predetermined length are machined into the sample body;

[0022] S2. Install the sample body on the loading fixture and place it into the molten salt environment high-temperature furnace body. Adjust the positioning components to make the sample body, loading fixture, load sensor, and loading connector on the same force axis.

[0023] S3. Place the molten salt into the inner layer of the molten salt environment high-temperature furnace body, close the molten salt environment high-temperature furnace body, introduce inert gas and circulating cooling water, start the heater to heat up to the target temperature, and apply the initial static load using the actuator after stabilization.

[0024] S4. Initiate dynamic cyclic loading to simulate fatigue load superposition;

[0025] S5. Record the applied load data using a load sensor and record the crack tip propagation displacement data of the specimen body using a COD gauge.

[0026] S6. After the specimen body breaks, the load applied by the actuator is automatically unloaded, the test is stopped, the heater is turned off, and the specimen body is removed.

[0027] S7. The data is fused and processed to output the crack length-time curve, crack length-load curve, fracture toughness, and fatigue crack propagation rate.

[0028] In some embodiments, in step S1, the sample body is processed using wire cutting or fatigue pre-splitting method, and the preset length is 0.5 mm to 2 mm.

[0029] In some embodiments, in step S4, when starting a dynamic cyclic load, the applied load amplitude and the applied load frequency are set.

[0030] The present invention has the following beneficial effects: the fracture toughness and crack propagation test device and method in molten salt environment are achieved by placing the sample body in the molten salt environment component, so that the sample body is completely immersed in the molten salt environment, and applying a lateral torque load to the sample body by the driving component, while providing a guiding function for the lateral movement of the loading component by the sliding component. Attached Figure Description

[0031] 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 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:

[0032] Figure 1 This is a schematic diagram of the overall structure of the fracture toughness and crack propagation test device in a molten salt environment in some embodiments of the present invention.

[0033] Figure 2 This is a schematic diagram of the structure of the molten salt environment component in some embodiments of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of the sliding component in some embodiments of the present invention. Detailed Implementation

[0035] 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.

[0036] 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.

[0037] Please see Figures 1 to 3 This invention relates to a molten salt environment fracture toughness and crack propagation testing device, used for testing a specimen body 4. The device includes a positioning component 1, a sliding component 2, a driving component 3, a loading component 5, and a molten salt environment component 6. The sliding component 2 is mounted on and movably connected to the positioning component 1. The driving component 3 is mounted on the positioning component 1 and connected to the sliding component 2. The loading component 5 is connected to both the sliding component 2 and the specimen body 4. The specimen body 4 is disposed within the molten salt environment component 6, which provides a high-temperature molten salt environment for the specimen body 4. The driving component 3 moves the sliding component 2 to apply a lateral torque load to the specimen body 4 via the loading component 5.

[0038] Understandably, this fracture toughness and crack propagation test device in a molten salt environment, by placing the specimen body 4 in the molten salt environment component 6, so that the specimen body 4 is completely immersed in the molten salt environment, and by applying a lateral torque load to the specimen body 4 through the drive component 3, and by providing a guiding function for the lateral movement of the loading component 5 through the sliding component 2, can realize the fracture toughness and crack propagation test of the specimen body 4 in a molten salt corrosion environment.

[0039] like Figure 2As shown, the molten salt environment component 6 includes a molten salt environment high-temperature furnace body 61, a molten salt tank 62 disposed within the molten salt environment high-temperature furnace body 61, a heat insulation layer 63 disposed within the molten salt environment high-temperature furnace body 61, a furnace support frame 64 connected to the side wall of the molten salt environment high-temperature furnace body 61, and a COD gauge 65 connected to the molten salt environment high-temperature furnace body 61. The other end of the furnace support frame 64 is connected to the positioning component 1. The molten salt environment high-temperature furnace body 61 is provided with an inert gas inlet 611 and an inert gas outlet 612. Specifically, the molten salt environment high-temperature furnace body 61 can provide a high-temperature molten salt environment for the sample body 4 to be tested. The outer shell of the molten salt environment high-temperature furnace body 61 is made of 304 stainless steel. The molten salt tank 62 is made of a nickel-based alloy coated with a high-temperature ceramic layer. The nickel-based alloy coated with a high-temperature ceramic layer has high strength and certain resistance to oxidation and corrosion at high temperatures, and can be heated in three stages during the test to make the heating more uniform. The heat insulation layer 63 is preferably a fireproof asbestos heat insulation layer, which can provide heat insulation. The molten salt environment high-temperature furnace body 61 has an inert gas inlet and outlet reserved above it, ensuring that the test environment is under inert gas protection and avoiding interference from oxygen. The COD gauge 65 can be inserted through the reserved port above the molten salt environment high-temperature furnace body 61. The reserved port adopts a groove design to match and seal with the sensor head of the COD gauge 65. The COD gauge 65, also known as a clip-on extensometer, plays an important role in material fracture mechanics testing. It is mainly used to measure the deformation of notched specimens within the gauge length and is widely used in fatigue pre-crack testing to measure crack length, determine plastic components, and determine compliance, etc.

[0040] like Figure 1 As shown, the positioning assembly 1 includes a chassis 11, a column 12, a positioning beam 13, a connecting beam 14, and a base 15. The column 12 is mounted on the chassis 11, the positioning beam 13 and the connecting beam 14 are separately mounted on the column 12, and the base 15 is mounted on the bottom of the chassis 11. Specifically, the positioning beam 13 is located below the connecting beam 14. The base 15 is placed at the four corners of the bottom of the chassis 11 and can be manually adjusted in height to ensure that the load is applied horizontally.

[0041] like Figure 3 As shown, the sliding assembly 2 includes a sliding connecting seat 21 connected to the connecting beam 14, a slide rail 22 connected to the sliding connecting seat 21, and a pair of sliders 23 movably connected to the slide rail 22. Steel balls 24 are disposed between the sliders 23 and the slide rail 22. The slide rail 22 is an I-shaped fixed track. At the meshing point between the sliders 23 and the slide rail 22, the steel balls 24, coated with lubricating grease, slide relative to each other in a rolling manner. A steel ball replacement port and a lubricating oil addition port are provided.

[0042] like Figure 1As shown, the drive assembly 3 includes an actuator 31, a load transmission connecting rod 32, and a pair of force transmission support rods 33. The actuator 31 is mounted on the positioning beam 13. The output end of the actuator 31 is connected to the load transmission connecting rod 32 and is used to drive the load transmission connecting rod 32 to move up and down. One end of the pair of force transmission support rods 33 is simultaneously hinged to the load transmission connecting rod 32 through a rotating member 34, and the other end of the pair of force transmission support rods 33 is connected to the slider 23. The housing 11 is equipped with a servo controller electrically connected to the actuator 31, which can control the movement of the actuator 31. Specifically, the actuator 31 is a lifting drive motor, which can drive the load transmission connecting rod 32 to move up and down. The rotating member 34 can be a pin. The pair of force transmission support rods 33 are connected into a stable triangular structure through the rotating member 34. The actuator 31 outputs a longitudinal load, which is then transmitted to the force transmission support rods 33 and then converted to a lateral load, thereby achieving the fracture toughness and test state.

[0043] like Figure 1 and Figure 2 As shown, the loading assembly 5 includes a pair of loading connectors 51 separately connected to a pair of sliders 23, a loading clamp 52 connected to the loading connectors 51, and a load sensor 53 mounted on the loading connectors 51. The specimen body 4 is mounted on the loading clamp 52. The loading clamp 52 passes through the outer shell of the molten salt environment high-temperature furnace body 61 and the molten salt tank 62, thereby transferring the torque load to the specimen body 4. The loading clamp 52 and the molten salt environment high-temperature furnace body 61 are sealed by a combination of bellows dynamic sealing and graphite gasket static sealing to ensure that the molten salt does not leak. The loading connectors 51 are provided with a circulating water cooling system inlet 511 for circulating cooling water to enter. The load sensor 53 is used to detect the applied load data during the test. The load sensor 53, loading connectors 51, loading clamp 52, and specimen body 4 are arranged on the same horizontal line.

[0044] In this embodiment, a test method for a fracture toughness and crack propagation test apparatus in a molten salt environment is also constructed. Based on the aforementioned fracture toughness and crack propagation test apparatus in a molten salt environment, the method includes the following steps:

[0045] S1. Initial cracks of a predetermined length are machined into the sample body 4;

[0046] S2. Install the sample body 4 on the loading fixture 52 and place it inside the molten salt environment high temperature furnace body 61. Adjust the positioning component 1 so that the sample body 4, the loading fixture 52, the load sensor 53, and the loading connector 51 are on the same force axis.

[0047] S3. Place the molten salt into the inner layer of the molten salt environment high-temperature furnace body 61, close the molten salt environment high-temperature furnace body 61, introduce inert gas and circulating cooling water, start the heater to heat up to the target temperature, and apply the initial static load using the actuator after stabilization.

[0048] S4. Initiate dynamic cyclic loading to simulate fatigue load superposition;

[0049] S5. Record the applied load data through load sensor 53 and record the crack tip propagation displacement data of the specimen body 4 through COD gauge 65.

[0050] S6. After the specimen body 4 breaks, the load applied by the actuator is automatically unloaded, the test is stopped, the heater is turned off, and the specimen body 4 is removed.

[0051] S7. The data is fused and processed to output the crack length-time curve, crack length-load curve, fracture toughness, and fatigue crack propagation rate.

[0052] Specifically, in step S1, the specimen body 4 is processed using wire cutting or fatigue pre-splitting method, with a preset length of 0.5 mm to 2 mm. In step S4, when starting the dynamic cyclic load, the applied load amplitude and applied load frequency are set.

[0053] This fracture toughness and crack propagation testing device and method in a molten salt environment solves the problem of long-term testing in molten salt at high temperatures due to sealing leakage by using a horizontal tension loading method. It can also place a COD gauge 65 above the molten salt environment to directly measure the crack tip displacement without being corroded by the molten salt environment, thus enabling fracture toughness and crack propagation testing in a high-temperature molten salt environment.

[0054] 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 test apparatus for fracture toughness and crack propagation in a molten salt environment, used for testing a specimen body (4), characterized in that, It includes a positioning component (1), a sliding component (2), a driving component (3), a loading component (5), and a molten salt environment component (6); The sliding component (2) is mounted on the positioning component (1) and is movably connected to the positioning component (1). The driving component (3) is mounted on the positioning component (1) and connected to the sliding component (2). The loading component (5) is connected to the sliding component (2) and the sample body (4) respectively. The sample body (4) is disposed in the molten salt environment component (6). The molten salt environment component (6) is used to provide a high-temperature molten salt environment for the sample body (4). The driving component (3) is used to drive the sliding component (2) to move, so as to drive the loading component (5) to apply a lateral torque load to the sample body (4).

2. The test apparatus for fracture toughness and crack propagation in a molten salt environment according to claim 1, characterized in that, The molten salt environment component (6) includes a molten salt environment high-temperature furnace body (61), a molten salt tank (62) disposed in the molten salt environment high-temperature furnace body (61), a heat insulation layer (63) disposed in the molten salt environment high-temperature furnace body (61), a furnace body support frame (64) connected to the side wall of the molten salt environment high-temperature furnace body (61), and a COD gauge (65) connected to the molten salt environment high-temperature furnace body (61). The other end of the furnace body support frame (64) is connected to the positioning component (1). The molten salt environment high-temperature furnace body (61) is provided with an inert gas inlet (611) and an inert gas outlet (612).

3. The test apparatus for fracture toughness and crack propagation in a molten salt environment according to claim 2, characterized in that, The molten salt tank (62) is made of a nickel-based alloy coated with a high-temperature ceramic layer, and the heat insulation layer (63) is a fireproof asbestos heat insulation layer.

4. The test apparatus for fracture toughness and crack propagation in a molten salt environment according to claim 2, characterized in that, The positioning component (1) includes a chassis (11), a column (12), a positioning crossbeam (13), a connecting crossbeam (14), and a base (15); The column (12) is installed on the chassis (11), the positioning beam (13) and the connecting beam (14) are installed separately on the column (12), and the base (15) is installed at the bottom of the chassis (11).

5. The test apparatus for fracture toughness and crack propagation in a molten salt environment according to claim 4, characterized in that, The sliding assembly (2) includes a sliding connecting seat (21) connected to the connecting beam (14), a slide rail (22) connected to the sliding connecting seat (21), and a pair of sliders (23) movably connected to the slide rail (22). A steel ball (24) is provided between the slider (23) and the slide rail (22).

6. The test apparatus for fracture toughness and crack propagation in a molten salt environment according to claim 5, characterized in that, The drive assembly (3) includes an actuator (31), a load transmission connecting rod (32), and a pair of force transmission support rods (33); The actuator (31) is mounted on the positioning beam (13). The output end of the actuator (31) is connected to the load transmission connecting rod (32) and is used to drive the load transmission connecting rod (32) to perform lifting and lowering movements. One end of a pair of force transmission support rods (33) is simultaneously hinged to the load transmission connecting rod (32) through a rotating member (34). The other end of the pair of force transmission support rods (33) is connected to the slider (23). The chassis (11) is equipped with a servo controller that is electrically connected to the actuator (31).

7. The test apparatus for fracture toughness and crack propagation in a molten salt environment according to claim 5, characterized in that, The loading assembly (5) includes a pair of loading connectors (51) separately connected to a pair of sliders (23), a loading fixture (52) connected to the loading connectors (51), and a load sensor (53) mounted on the loading connectors (51), wherein the sample body (4) is mounted on the loading fixture (52); The loading fixture (52) and the molten salt environment high temperature furnace body (61) are connected by a combination of bellows dynamic sealing and graphite gasket static sealing. The loading connector (51) is provided with a circulating water cooling system inlet (511).

8. A test method for a fracture toughness and crack propagation test apparatus in a molten salt environment, based on the fracture toughness and crack propagation test apparatus in a molten salt environment as described in any one of claims 1 to 7, characterized in that, Including the following steps: S1. Initial cracks of a preset length are machined into the sample body (4); S2. Install the sample body (4) on the loading fixture (52) and place it inside the molten salt environment high temperature furnace body (61). Adjust the positioning component (1) so that the sample body (4), loading fixture (52), load sensor (53), and loading connector (51) are on the same force axis. S3. Place the molten salt into the inner layer of the molten salt environment high temperature furnace body (61), close the molten salt environment high temperature furnace body (61), introduce inert gas and circulating cooling water, start the heater to heat up to the target temperature, and apply the initial static load using the actuator after stabilization. S4. Initiate dynamic cyclic loading to simulate fatigue load superposition; S5. Record the applied load data through the load sensor (53) and record the crack tip propagation displacement data of the specimen body (4) through the COD gauge (65); S6. After the specimen body (4) breaks, the load applied by the actuator is automatically unloaded, the test is stopped, the heater is turned off, and the specimen body (4) is removed. S7. The data is fused and processed to output the crack length-time curve, crack length-load curve, fracture toughness, and fatigue crack propagation rate.

9. The test method for the fracture toughness and crack propagation test apparatus in a molten salt environment according to claim 8, characterized in that, In step S1, the sample body (4) is processed by wire cutting or fatigue pre-splitting method, and the preset length is 0.5 mm to 2 mm.

10. The test method for the fracture toughness and crack propagation test apparatus in a molten salt environment according to claim 8, characterized in that, In step S4, when starting the dynamic cyclic load, the applied load amplitude and the applied load frequency are set.

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