Device and method for testing mechanical property of micro sample in high-temperature and high-pressure hydrogen environment

Abstract

The invention discloses a device and a method for testing mechanical properties of a micro sample in a high-temperature and high-pressure hydrogen environment, and belongs to the technical field of testing of mechanical properties in a hydrogen environment, the device comprises a temperature control system, a hydrogen-present micro sample clamp, a high-pressure hydrogen circulating system and a mechanical loading system, a gas standing cavity is arranged in the hydrogen-present micro sample clamp, and the gas standing cavity is of an inverted T-shaped gas passage structure; the upper opening of the gas standing cavity is used for placing a sample, and the openings at the two ends of the gas standing cavity are respectively connected with a high-pressure hydrogen circulating system through pipelines, so that high-pressure hydrogen can circularly flow, the concentration of the hydrogen in contact reaction with the sample is maintained in a stable range, and the volume of the hydrogen in the gas standing cavity is relatively small; the use cost and the explosion risk are effectively reduced, meanwhile, the temperature rising speed is increased, in addition, hydrogen only makes contact with the gas standing cavity and does not make contact with other positions of the hydrogen-containing micro-sample clamp, the contact reaction area is small, and the service life of the hydrogen-containing micro-sample clamp is effectively prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical property testing in hydrogen environment, and in particular to a device and method for testing the mechanical property of a micro-sample in a high-temperature and high-pressure hydrogen environment. Background Art

[0002] In a high-temperature (around 600°C) and high-pressure (around 10MPa) hydrogen environment, hydrogen atoms entering the material will cause hydrogen embrittlement, which will reduce the mechanical and corrosion properties of the material and affect the safety and reliability of the material during long-term service. Therefore, it is necessary to test and evaluate the service performance of the material in a high-temperature and high-pressure hydrogen environment.

[0003] In order to conduct in-situ testing of micro-specimens, a hydrogen environment micro-specimen mechanical properties testing device (publication number CN117169012A) has been developed, which includes a hydrogen environment micro-specimen loading system. The hydrogen environment micro-specimen loading system is composed of a micro-specimen loading system connected to a hydrogen environment chamber, so that a force load can be applied to the micro-specimen through the micro-specimen loading system, and the mechanical properties change parameters of the micro-specimen in a hydrogen environment can be obtained.

[0004] The existing hydrogen environment micro-specimen mechanical property testing device is equipped with a hydrogen environment chamber. The amount of hydrogen used in the test process is large, which not only has high cost but also has a high risk of explosion. In order to reduce the risk of explosion, an inert gas protection chamber is set around the hydrogen environment chamber, but the overall structure is complex, and the heat exchange efficiency between the inert gas protection chamber and the hydrogen environment chamber is low; in addition, the fixture of the micro-specimen loading system is exposed to the hydrogen environment chamber, and the outer wall of the fixture is in contact with the hydrogen in the hydrogen environment chamber, which not only affects the service life of the fixture, but also affects the purity and concentration of the hydrogen due to the reaction between the outer wall of the fixture and the hydrogen, thereby affecting the subsequent micro-specimen testing. Summary of the invention

[0005] In order to solve the technical problems in the above-mentioned background technology that the existing hydrogen environment micro-specimen mechanical properties testing device uses a large amount of hydrogen during the test, has high cost of use, high risk of explosion, low heating efficiency, and short service life of the fixture, the present invention provides a device and method for testing the mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment.

[0006] The technical solution of the present invention is as follows: The invention provides a device for testing mechanical properties of micro-samples in a high-temperature and high-pressure hydrogen environment. The device comprises a temperature control system. A hydrogen micro-sample fixture is arranged in the temperature control system. An air stagnation cavity is arranged inside the hydrogen micro-sample fixture. The air stagnation cavity is an inverted T-shaped airway structure. The upper opening of the air stagnation cavity is used to place the sample. The openings at both ends of the air stagnation cavity are respectively connected to a high-pressure hydrogen circulation system through pipelines. A mechanical loading system is arranged above the hydrogen micro-sample fixture. The mechanical loading system is used to load the sample clamped in the hydrogen micro-sample fixture. The air stagnation cavity is connected to the high-pressure hydrogen circulation system so that the high-pressure hydrogen can circulate and flow, thereby ensuring that the concentration of hydrogen that contacts and reacts with the sample is maintained within a stable range. The volume of hydrogen in the air stagnation cavity is small, thereby effectively reducing the use cost and the risk of explosion, and simultaneously improving the heating speed. In addition, the hydrogen contacts only the air stagnation cavity and does not contact other positions of the hydrogen micro-sample fixture. The contact reaction area is small, thereby effectively improving the service life of the hydrogen micro-sample fixture.

[0007] Preferably, the hydrogen micro-sample fixture comprises an upper clamping seat and a lower clamping seat which are detachably connected, the upper clamping seat comprises a protrusion, the lower clamping seat comprises a receiving groove, the air retention cavity is arranged in the lower clamping seat, and the upper opening of the air retention cavity is communicated with the receiving groove, the protrusion is inserted in the receiving groove and presses the sample, a sealing ring is arranged between the sample and the receiving groove, and the cooperation mode of the protrusion and the receiving groove effectively improves the pressing effect on the sample, and the sealing ring between the sample and the receiving groove ensures the sealing effect and avoids the leakage of hydrogen in the air retention cavity.

[0008] Preferably, a through hole is provided on the upper clamping seat, and the through hole is coaxially arranged with the accommodating groove to facilitate the loading of the sample by the mechanical loading system, and the mechanical loading system loads the sample through the through hole.

[0009] Preferably, the high-pressure hydrogen circulation system includes a gas cylinder and a gas storage tank, the gas cylinder is connected to the gas storage tank through a pipeline, the gas storage tank is provided with a pressure gauge and a first hydrogen concentration sensor, the gas storage tank is connected to the air inlet end of the gas chamber through an air inlet pipe, and the gas storage tank is connected to the exhaust end of the gas chamber through an air outlet pipe, so that the hydrogen concentration can be adjusted in advance before the reaction to ensure the accuracy of the test, and at the same time, it is convenient to monitor the concentration and pressure of the hydrogen online.

[0010] Preferably, an air pressure pump, a first one-way valve and a second hydrogen pressure gauge are sequentially provided on the air inlet pipe along the flow direction of the hydrogen, so as to pump the hydrogen into the air chamber at a set pressure and monitor the hydrogen pressure online at the same time; a first hydrogen pressure gauge, a gas cooling unit, a pressure reducing valve, a third hydrogen pressure gauge and a second one-way valve are sequentially provided on the air outlet pipe along the flow direction of the hydrogen, so as to cool and regulate the pressure of the hydrogen discharged from the air chamber so that the hydrogen can re-enter the gas storage tank for recycling.

[0011] Preferably, the air outlet end of the air chamber is connected to an exhaust gas tank via an exhaust gas pipe, a first valve is provided on the air outlet pipe, a second valve and a second hydrogen concentration sensor are provided on the exhaust gas pipe, the exhaust gas tank can recycle and store the air in the air chamber to avoid the influence of the air on the test, and the second hydrogen concentration sensor can cooperate with the first hydrogen concentration sensor to ensure online monitoring of the air emission level in the air chamber.

[0012] Preferably, the temperature control system includes a high-temperature autoclave, a heating plate and a preheating unit. The hydrogen micro-specimen fixture is placed as a whole in the high-temperature autoclave, the heating plate is arranged on the surrounding side of the high-temperature autoclave, and the preheating unit is arranged on the air inlet pipe. The preheating unit can heat the hydrogen in advance to facilitate the secondary heating of the hydrogen during the secondary heating in the high-temperature autoclave, thereby improving the test efficiency.

[0013] The present invention provides a method for testing the mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment, which is specifically as follows: Assemble the test device and insert the specimen; Connect the gas chamber to the waste gas tank, adjust the hydrogen concentration in the gas storage tank according to the test requirements, start the air pressure pump, use high-pressure hydrogen to discharge the air in the gas chamber into the waste gas tank, compare the hydrogen concentration values ​​of the first hydrogen concentration sensor and the second hydrogen concentration sensor, and close the second valve and the air pressure pump when they meet the requirements; Start the heating plate, open the first valve, start the preheating unit and the air pressure pump, pump hydrogen into the gas cavity through the air pressure pump and circulate it back to the gas storage tank, control the high temperature and high pressure autoclave to reach the required temperature for the test and maintain it for 1 hour; The loading unit loads the sample, and the test is stopped when the test load drops to 75% of the maximum load. After cooling, the sample is taken out and analyzed.

[0014] Preferably, when the difference between the indications of the first hydrogen pressure gauge and the second hydrogen pressure gauge is greater than 0.5 MPa, it is determined that the gas in the gas chamber is leaking, and the test is automatically stopped, thereby reducing safety hazards.

[0015] Preferably, the hydrogen is preheated in advance in the air inlet pipe, and is further heated by a heating plate after entering the air chamber, thereby improving the heating efficiency and safety of the hydrogen.

[0016] It can be seen from the above technical solutions that the advantages of the present invention are: 1. A gas stagnation cavity is set in the micro-sample fixture in the presence of hydrogen, so that the gas stagnation cavity is connected to the high-pressure hydrogen circulation system, so that the high-pressure hydrogen can circulate, ensuring that the concentration of hydrogen in contact with the sample is maintained within a stable range. The volume of the gas stagnation cavity is small, and the amount of hydrogen required in the test area is small, which effectively reduces the use cost and explosion risk, and improves the heating rate. In addition, the hydrogen only contacts the gas stagnation cavity and does not contact other positions of the micro-sample fixture in the presence of hydrogen. The contact reaction area is small, which effectively improves the service life of the micro-sample fixture in the presence of hydrogen.

[0017] 2. The preheating unit is arranged on the air inlet pipe to preheat the hydrogen in the air inlet pipe. Through the cooperation between the preheating unit and the heating plate, the heating time of the hydrogen in the high-temperature and high-pressure autoclave is effectively shortened, the heating efficiency is improved, and the circulating hydrogen can quickly reach the experimental temperature in the gas chamber. At the same time, the preheating unit and the heating plate do not directly heat the hydrogen, but exchange heat with the hydrogen through the pipe wall and the autoclave wall, avoiding the risk of hydrogen explosion.

[0018] 3. A first hydrogen pressure gauge and a second hydrogen pressure gauge are respectively provided at both ends of the gas chamber. The gas leakage in the gas chamber is monitored online by the indication difference between the first hydrogen pressure gauge and the second hydrogen pressure gauge, which effectively improves the safety during the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present invention, the accompanying drawings required for use in the description will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0020] Figure 1 The overall structure schematic diagram (partial cross-section) of a micro-specimen mechanical property testing device in a high-temperature and high-pressure hydrogen environment according to one or more embodiments of the present invention; Figure 2 for Figure 1 A schematic diagram of a local enlarged structure at the fixture position of the structure shown; The components represented by the reference numerals in the figure are: 1. Loading unit; 2. Punch rod; 3. First hydrogen pressure gauge; 4. High temperature and high pressure autoclave; 5. Heating plate; 6. Hydrogen micro sample fixture; 7. Base; 8. Preheating unit; 9. Second hydrogen pressure gauge; 10. First one-way valve; 11. Air pressure pump; 12. Gas cylinder; 13. Gas storage tank; 14. Air pressure gauge; 15. Second one-way valve; 16. Third hydrogen pressure gauge; 17. Pressure reducing valve; 18. Gas cooling unit; 19. Inlet pipe; 20. Outlet pipe; 21. Air retention cavity; 22. Sealing ring; 23. Sample; 24. Ceramic ball; 25. Lower clamp seat; 26. Upper clamp seat; 27. Bolt; 28. Waste gas tank; 29. ​​Waste gas pipe; 30. First valve; 31. Second valve; 32. First hydrogen concentration sensor; 33. Second hydrogen concentration sensor. DETAILED DESCRIPTION

[0021] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in this specific embodiment. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of them. Based on the embodiments in this patent, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this patent.

[0022] Example 1 In a typical embodiment of the present invention, Figure 1-Figure 2 As shown, a device for testing the mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment is proposed, comprising: a high-pressure hydrogen circulation system, a temperature control system, a mechanical loading system and a hydrogen micro-specimen fixture 6, wherein the high-pressure hydrogen circulation system is connected to the hydrogen micro-specimen fixture 6 through a pipeline, the interior of the hydrogen micro-specimen fixture 6 has a gas retention cavity 21 that allows hydrogen to pass through, the hydrogen in the gas retention cavity 21 is used to contact the lower surface of the sample 23 clamped by the hydrogen micro-specimen fixture 6 to provide a high-pressure hydrogen environment, the temperature control system is used to control the temperature of the sample 23 and the hydrogen to provide a high-temperature testing environment, and the mechanical loading system is used to load the upper surface of the sample 23 clamped in the hydrogen micro-specimen fixture 6.

[0023] The hydrogen micro-sample fixture 6 includes an upper clamp seat 26 and a lower clamp seat 25. The upper clamp seat 26 is a convex structure, and the lower clamp seat 25 is a concave structure that matches the shape of the upper clamp seat 26. Specifically, the lower surface of the upper clamp seat 26 is provided with a downward protrusion, and the upper surface of the lower clamp seat 25 is provided with a receiving groove that matches the protrusion, and the sample 23 is used to be placed in the receiving groove.

[0024] like Figure 2As shown, an air retention cavity 21 is further provided inside the lower clamp seat 25. The air retention cavity 21 is located directly below the receiving groove on the upper surface of the lower clamp seat 25, and the air retention cavity 21 is communicated with the receiving groove. The air retention cavity 21 is an inverted T-shaped airway structure (which can also be understood as a "╩" shape). Specifically, the air retention cavity 21 includes a transverse airway and a vertical airway. The transverse airway transversely penetrates the lower clamp seat 25, and both ends of the transverse airway are communicated with the high-pressure hydrogen circulation system through pipelines. The vertical airway is vertically arranged above the transverse airway, and the vertical airway is communicated with the transverse airway. The upper opening of the vertical airway is communicated with the receiving groove of the lower clamp seat 25, so as to allow the high-temperature and high-pressure hydrogen to contact the surface of the sample 23.

[0025] The setting of the gas chamber 21 and its connection with the high-pressure hydrogen circulation system enable the high-pressure hydrogen to circulate, ensuring that the concentration of hydrogen in contact with the sample 23 is maintained within a stable range, and the volume of hydrogen in the gas chamber 21 is small, which effectively reduces the use cost and explosion risk, while increasing the heating rate. In addition, the hydrogen only contacts the gas chamber 21 in the lower clamping seat 25, and does not contact other positions of the hydrogen micro-sample fixture 6. The contact reaction area is small, which effectively increases the service life of the hydrogen micro-sample fixture 6.

[0026] The bottom of the lower clamp seat 25 is connected to the base 7 so as to support the lower clamp seat 25 through the base 7. An O-shaped sealing ring 22 is provided in the receiving groove of the lower clamp seat 25. The sample 23 is placed on the sealing ring 22. The raised portion of the upper clamp seat 26 is inserted into the receiving groove and presses the sample 23. The sealing ring 22 plays a sealing role to prevent hydrogen leakage. The upper clamp seat 26 and the lower clamp seat 25 are fixedly connected by bolts 27. A through hole is provided on the upper clamp seat 26. The through hole is coaxially arranged with the receiving groove, and the mechanical loading system is inserted in the through hole.

[0027] Specifically, the mechanical loading system includes a loading unit 1, a punch rod 2 and a ceramic ball 24. The punch rod 2 is inserted into the through hole of the upper clamp seat 26. The ceramic ball 24 is placed in the through hole of the upper clamp seat 26, and the ceramic ball 24 is located below the punch rod 2. The upper end of the punch rod 2 is connected to the loading unit 1. The loading unit 1 applies force to the ceramic ball 24 through the punch rod 2, and then loads the sample 23 below it through the ceramic ball 24.

[0028] The high-pressure hydrogen circulation system includes a pressure pump 11, a gas cylinder 12 and a gas storage tank 13. There are several gas cylinders 12. The gas cylinders 12 are used to store hydrogen. The gas cylinders 12 are connected to the gas storage tank 13 through pipelines to transport hydrogen to the gas storage tank 13, and then adjust the hydrogen concentration in advance before the reaction to ensure the accuracy of the test. The gas storage tank 13 is provided with a barometer 14 and a first hydrogen concentration sensor 32 to monitor the hydrogen concentration and pressure in the gas storage tank 13 at all times.

[0029] The gas storage tank 13 is connected to the openings at both ends of the gas chamber 21 in the lower clamp seat 25 through a circulation pipeline to realize the circulation flow of hydrogen in the gas chamber 21. Figure 2 As shown, the circulation pipeline includes an air inlet pipe 19 and an air outlet pipe 20. The exhaust port of the gas storage tank 13 is connected to the air inlet end of the transverse air channel of the air chamber 21 through the air inlet pipe 19, and the air inlet of the gas storage tank 13 is connected to the exhaust end of the transverse air channel of the air chamber 21 through the air outlet pipe 20, thereby realizing the circulation flow of hydrogen.

[0030] It is understandable that the circulation pipeline and the air retention chamber 21 can be connected and fixed by threaded connection, while ensuring the sealing of the connection position.

[0031] Among them, an air pressure pump 11, a first one-way valve 10 and a second hydrogen pressure gauge 9 are sequentially arranged on the air inlet pipe 19 along the flow direction of hydrogen. The air pressure pump 11 is used to adjust the pressure of hydrogen entering the air chamber 21, and the second hydrogen pressure gauge 9 is used for online monitoring to ensure the accuracy of hydrogen pressure regulation. The first one-way valve 10 is used to limit the flow direction of hydrogen to prevent hydrogen from flowing back. A first hydrogen pressure gauge 3, a gas cooling unit 18, a pressure reducing valve 17, a third hydrogen pressure gauge 16 and a second one-way valve 15 are sequentially provided on the outlet pipe 20 along the flow direction of hydrogen. The first hydrogen pressure gauge 3 is used to detect the pressure of hydrogen discharged from the gas chamber 21 to the outside, the gas cooling unit 18 is used to cool the hydrogen, the pressure reducing valve 17 is used to reduce and regulate the hydrogen pressure, the third hydrogen pressure gauge 16 is used for online detection of the hydrogen pressure after pressure reduction, and when it does not meet the requirements, it is convenient to adjust the pressure regulating valve 17, and the second one-way valve 15 is used to limit the flow direction of hydrogen so that the hydrogen flows back into the gas storage tank 13 without backflow.

[0032] The outlet end of the air chamber 21 is also connected to an exhaust pipe 29, and the air chamber 21 is connected to the exhaust tank 28 through the exhaust pipe 29. A first valve 30 is provided on the outlet pipe 20, and a second valve 31 is provided on the exhaust pipe 29 to control the on-off switching between the air chamber 21 and the outlet pipe 20 and the exhaust pipe 29, thereby controlling the flow direction of the gas.

[0033] The exhaust pipe 29 is provided with a second hydrogen concentration sensor 33. Before the test begins, the exhaust pipe 29 can be connected to the accumulating chamber 21, and hydrogen can be transported into the accumulating chamber 21 through the gas storage tank 13. The air in the accumulating chamber 21 can be discharged by high-pressure hydrogen to ensure the purity of the gas environment in the accumulating chamber 21. The discharged gas enters the exhaust tank 28 through the exhaust pipe 29. During the discharge process, the data can be compared with the first hydrogen concentration sensor 32 through the second hydrogen concentration sensor 33. When the data are the same, the air discharge is completed, and the exhaust pipe 29 can be cut off and connected to the outlet pipe 20.

[0034] It is understandable that, in order to ensure the accuracy of data comparison, in other embodiments, the first hydrogen concentration sensor 32 may be disposed on the intake pipe 19, and the specific location of the sensor is not subject to excessive restrictions.

[0035] The temperature control system includes a high-temperature autoclave 4, a heating plate 5 and a preheating unit 8. The hydrogen micro-sample fixture 6 is placed as a whole in the high-temperature autoclave 4. The heating plate 5 is arranged on the side of the high-temperature autoclave 4 to heat the inside of the high-temperature autoclave 4, thereby heating the sample 23 and the hydrogen.

[0036] The preheating unit 8 is arranged on the air inlet pipe 19 to preheat the hydrogen in the air inlet pipe 19. Through the cooperation between the preheating unit 8 and the heating plate 5, the heating time of the hydrogen in the high-temperature and high-pressure autoclave 4 is effectively shortened, and the heating efficiency is improved. At the same time, the preheating unit 8 and the heating plate 5 do not directly heat the hydrogen, but exchange heat with the hydrogen through the pipe wall and the autoclave wall, thereby avoiding the risk of explosion of hydrogen.

[0037] It can be understood that the preheating unit 8 and the gas cooling unit 18 are both existing structures. For example, the preheating unit 8 can be a structure such as an electric heating wire wound around the intake pipe 19, and the gas cooling unit 18 can be a water cooling sleeve structure, etc. The specific structural form can be determined according to actual design requirements, and no excessive restrictions are made here.

[0038] Example 2 In another typical embodiment of the present invention, a method for testing the mechanical properties of micro-specimens in a high temperature and high pressure hydrogen environment is proposed, which is as follows: Place the sealing ring 22 in the receiving groove of the lower clamp seat 25 of the hydrogen micro-sample fixture 6, and place the sample 23 to be tested on the sealing ring 22, assemble the upper and lower clamp seats, and use bolts 27 to press the upper and lower clamp seats, and place the assembled hydrogen micro-sample fixture 6 in the high-temperature autoclave 4 and fix it through the base 7; First, close the first valve 30 on the gas outlet pipe 20, and open the second valve 31 on the exhaust pipe 29, so that the gas chamber 21 is connected to the exhaust tank 28, and adjust the hydrogen concentration in the gas storage tank 13 according to the test requirements. When the hydrogen concentration adjustment meets the requirements, start the air pressure pump 11, and pump hydrogen into the gas chamber 11 according to the set pressure through the air pressure pump 11. The hydrogen pressure is monitored by the second hydrogen pressure gauge 9, and the air in the gas chamber 11 is discharged into the exhaust tank 28 by high-pressure hydrogen. Compare the pressure values ​​of the first hydrogen concentration sensor 32 and the second hydrogen concentration sensor 33. When the pressure values ​​are the same or similar, it proves that the air in the gas chamber 21 is discharged. Then close the second valve 31 and the air pressure pump 11; The heating plate 5 is started, the first valve 30 is opened, and the preheating unit 8 and the air pressure pump 11 are started. The hydrogen is pumped into the gas chamber 21 by the air pressure pump 11. During the pumping process, the preheating unit 8 preheats the hydrogen in the air inlet pipe 19 in advance. The preheated hydrogen enters the gas chamber 21 and contacts the sample 23. During this period, the heating plate 5 further heats the hydrogen in the gas chamber 21, so that the hydrogen in the gas chamber 21 is quickly heated to a specified temperature, so that the sample 23 is in a high-temperature and high-pressure hydrogen environment. Under the action of the air pressure pump 11, the hydrogen in the gas chamber 21 flows into the gas outlet pipe 20 and flows back to the gas storage tank 13. In order to realize the circulation and reuse of hydrogen, the high-temperature autoclave 4 is controlled to reach the required temperature for the test and maintained for 1 hour. While hydrogen is pumped into the gas cavity 21, the loading unit 1 loads the sample 23 through the punch 2 and the ceramic ball 24, and the displacement-load curve is recorded; when the test load drops to 75% of the maximum load, the test is stopped (when the difference between the readings of the first hydrogen pressure gauge 3 and the second hydrogen pressure gauge 9 is greater than 0.5MPa, it is determined that the gas in the gas cavity 21 of the hydrogen micro-sample fixture 6 is leaking, and the test is automatically stopped), the sample 23 is taken out after cooling, and the recorded displacement-load curve and the deformation and cracking morphology of the sample 23 are analyzed.

[0039] When the hydrogen pump enters the air cavity 21, the readings of the first hydrogen pressure gauge 3 and the second hydrogen pressure gauge 9 are read, and the air pressure value in the air cavity 21 is adjusted by adjusting the flow rate and pressure of the air pressure pump 11 and controlling the pressure reducing valve 17 on the air outlet pipe 20 to maintain the air pressure at the state required for the test.

[0040] In this embodiment, the size of the sample 23 is 10 mm in diameter and 0.5 mm in thickness to achieve the purpose of micro-damage sampling; the volume of the "╩"-shaped air retention cavity 21 in the lower clamp seat 25 of the hydrogen micro-sample clamp 6 is about 5 cubic centimeters, and the amount of hydrogen required in the test area is small, reducing safety hazards. The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for testing the mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment, comprising: The temperature control system is characterized in that a hydrogen micro-sample fixture (6) is provided in the temperature control system, an air chamber (21) is provided inside the hydrogen micro-sample fixture (6), the air chamber (21) is an inverted T-shaped airway structure, the upper opening of the air chamber (21) is used to place a sample (23), the openings at both ends of the air chamber (21) are respectively connected to a high-pressure hydrogen circulation system through pipelines, and a mechanical loading system is provided above the hydrogen micro-sample fixture (6), and the mechanical loading system is used to load the sample (23) clamped in the hydrogen micro-sample fixture (6).

2. The device for testing mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment according to claim 1 is characterized in that: The hydrogen micro-sample fixture (6) comprises an upper clamp seat (26) and a lower clamp seat (25) which are detachably connected, the upper clamp seat (26) comprising a protrusion, the lower clamp seat (25) comprising a receiving groove, an air retention cavity (21) being arranged in the lower clamp seat (25), and an upper opening of the air retention cavity (21) being communicated with the receiving groove, the protrusion being inserted into the receiving groove and pressing the sample (23), and a sealing ring (22) being arranged between the sample (23) and the receiving groove.

3. The device for testing mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment according to claim 2, characterized in that: The upper clamping seat (26) is provided with a through hole, which is coaxially arranged with the receiving groove, and the mechanical loading system passes through the through hole to load the sample (23).

4. The device for testing mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment according to claim 1, characterized in that: The high-pressure hydrogen circulation system comprises a gas cylinder (12) and a gas storage tank (13); the gas cylinder (12) is connected to the gas storage tank (13) via a pipeline; the gas storage tank (13) is provided with a pressure gauge (14) and a first hydrogen concentration sensor (32); the gas storage tank (13) is connected to the gas inlet end of the gas chamber (21) via an inlet pipe (19); and the gas storage tank (13) is connected to the gas outlet end of the gas chamber (21) via an outlet pipe (20).

5. The device for testing mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment according to claim 4, characterized in that: An air pressure pump (11), a first one-way valve (10) and a second hydrogen pressure gauge (9) are sequentially provided on the air inlet pipe (19) along the flow direction of the hydrogen gas, and a first hydrogen pressure gauge (3), a gas cooling unit (18), a pressure reducing valve (17), a third hydrogen pressure gauge (16) and a second one-way valve (15) are sequentially provided on the air outlet pipe (20) along the flow direction of the hydrogen gas.

6. The device for testing mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment according to claim 4, characterized in that: The gas outlet end of the gas retention cavity (21) is connected to an exhaust gas tank (28) via an exhaust gas pipe (29); a first valve (30) is provided on the gas outlet pipe (20); and a second valve (31) and a second hydrogen concentration sensor (33) are provided on the exhaust gas pipe (29).

7. The device for testing mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment according to claim 4, characterized in that: The temperature control system comprises a high-temperature autoclave (4), a heating plate (5) and a preheating unit (8); the hydrogen-prone micro-sample fixture (6) is placed as a whole in the high-temperature autoclave (4); the heating plate (5) is arranged on the peripheral side of the high-temperature autoclave (4); and the preheating unit (8) is arranged on the air inlet pipe (19).

8. A method for testing the mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment, characterized in that: The device for testing mechanical properties of micro-specimens in a high temperature and high pressure hydrogen environment as described in any one of claims 1 to 7 is used, specifically as follows: Assembling the test device and placing the test specimen (23); The gas chamber (21) is connected to the waste gas tank (28), the hydrogen concentration in the gas storage tank (13) is adjusted according to the test requirements, the air pressure pump (11) is started, and the air in the gas chamber (21) is discharged into the waste gas tank (28) using high-pressure hydrogen, and the pressure values ​​of the first hydrogen concentration sensor (32) and the second hydrogen concentration sensor (33) are compared. When the pressure values ​​meet the requirements, the second valve (31) and the air pressure pump (11) are closed; Start the heating plate (5), open the first valve (30), and start the preheating unit (8) and the air pressure pump (11), pump hydrogen into the gas chamber (21) through the air pressure pump (11) and circulate it back into the gas storage tank (13), control the high temperature and high pressure autoclave (4) to reach the required temperature for the test and maintain it for 1 hour; The loading unit (1) loads the sample (23), and the test is stopped when the test load drops to 75% of the maximum load. After cooling, the sample (23) is taken out and analyzed.

9. The method for testing mechanical properties of micro-specimens in a high-temperature and high-pressure hydrogen environment according to claim 8, characterized in that: When the difference between the indications of the first hydrogen pressure gauge (3) and the second hydrogen pressure gauge (9) is greater than 0.5 MPa, it is determined that there is gas leakage in the gas chamber (21), and the test is automatically stopped.

10. The method for testing mechanical properties of micro-specimens in a high temperature and high pressure hydrogen environment according to claim 8, characterized in that: The hydrogen is preheated in advance in the air inlet pipe (19), and is further heated by the heating plate (5) after entering the air retention cavity (21).

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