Hydrogen environment slow tensile testing machine and control method thereof

Abstract

The invention relates to a hydrogen environment slow tensile testing machine and a control method thereof, and relates to the technical field of material performance testing. A lifting cross beam, a pressure balancing device and a clamp of the hydrogen environment slow tensile testing machine are sequentially arranged from top to bottom, a sample is installed on the clamp, the sample and the clamp are arranged in a test kettle together, an air inlet and an air outlet are formed in the test kettle, the test kettle is filled with hydrogen through the air inlet and the air outlet, and therefore the sample is subjected to a tensile test in the hydrogen environment. According to the hydrogen environment slow tensile testing machine and the control method thereof, the accuracy of a tensile test of a material in a hydrogen environment can be improved, the operation is simple, and the structural safety is high.

Description

Technical Field

[0001] The present application relates to the technical field of material performance testing, and in particular to a hydrogen environment slow tensile testing machine and a control method thereof. Background Art

[0002] As the proportion of hydrogen in traditional natural gas fuel continues to increase, the risk of hydrogen damage to metal materials such as hydrogen-blended natural gas pipelines and gas turbine hydrogen-exposed components is significantly increasing. Especially under high temperature, high pressure and hydrogen environments, hydrogen atoms can easily penetrate into steel, causing failures such as hydrogen embrittlement and hydrogen blistering. Testing the hydrogen embrittlement resistance of materials under high pressure, high temperature and hydrogen environments is of great significance to the design and manufacture of hydrogen-exposed equipment.

[0003] At present, there are few reports on the effects of hydrogen on the service performance of alloy materials such as fuel pipes, nozzles, combustion chambers, and blades. In related technologies, the main method for testing hydrogen embrittlement performance is to place the sample in a closed environmental chamber and fill it with hydrogen, then take it out and conduct a tensile test. After the sample is taken out of the environmental chamber, hydrogen precipitation will occur, which is different from the service conditions of the material, resulting in inaccurate hydrogen embrittlement performance test results. Summary of the invention

[0004] The purpose of the present application is to provide a hydrogen environment slow tensile testing machine and a control method thereof, which can improve the accuracy of tensile testing of materials in a hydrogen environment.

[0005] In order to achieve the above-mentioned object, in a first aspect, the present invention provides a hydrogen environment slow tensile testing machine, which includes a main frame, a test kettle, a support frame, a pressure balancing device, an electric push rod and a lifting beam; The test kettle comprises a kettle cover and a kettle body, the kettle body is fixedly mounted on the bottom of the main frame, the lifting beam is mounted on the top of the main frame and can move in the vertical direction, one end of the electric push rod is connected to the lifting beam, and the other end of the electric push rod is detachably connected to the kettle cover, and the electric push rod can drive the kettle cover to cover the kettle body; The kettle cover is connected with a support frame, which is used to install the fixture and the sample. One end of the pressure balance device is connected to the lifting beam, and the other end of the pressure balance device passes through the kettle cover and is connected to the fixture. The lifting beam can pull the pressure balance device and the fixture, thereby stretching the sample. At this time, the electric push rod is disconnected from the kettle cover; The test kettle is provided with an air inlet and an air outlet, and hydrogen is filled into the test kettle through the air inlet and the air outlet, so that the sample is subjected to a tensile test in a hydrogen environment.

[0006] In an optional embodiment, the kettle body and kettle cover of the test kettle are sealed with two O-rings, one axial seal and one radial seal; the kettle cover and the pressure balance device are sealed with one O-ring axial seal.

[0007] In an optional embodiment, a filling block is installed on the kettle cover, and the filling block is used to be inserted into the interior of the test kettle to reduce the amount of hydrogen required in the kettle.

[0008] In an optional embodiment, the pressure balancing device includes an upper tie rod, an upper balancing cylinder, a middle sealing flange, a lower tie rod and a lower balancing cylinder; The lifting beam, upper pull rod, lower pull rod and clamp are connected in sequence from top to bottom, the upper balancing cylinder body is connected to the lower balancing cylinder body through the middle sealing flange, the bottom of the lower balancing cylinder body is connected to the kettle cover through bolts, and the upper pull rod and the lower pull rod are slidably arranged in the upper balancing cylinder body and the lower balancing cylinder body.

[0009] In an optional embodiment, when performing a tensile test, a gas having the same pressure as that in the test kettle is introduced into the lower balance cylinder.

[0010] In a second aspect, the present invention provides a control method for a hydrogen environment slow tensile testing machine, the control method comprising the following steps: S1: Control the electric push rod to drive the kettle cover to descend to the kettle body, and connect the kettle cover and the kettle body with bolts; S2: Perform an air tightness test on the test kettle to check whether the test kettle is leaking; S3: Use a mold temperature controller to adjust the temperature in the test kettle to the test temperature; S4: After the test temperature is reached in the kettle, hydrogen is filled into the test kettle to the test pressure; S5: Perform tensile test; S6: After the test is completed, stop the machine, turn off the mold temperature controller, and relieve the pressure on the pipeline and kettle body.

[0011] In an optional embodiment, S1 includes: During the process of lowering the kettle cover, the lowering speed of the kettle cover is kept constant at first, then gradually reduced, and finally a gap is reserved with the kettle body, and finally the kettle cover and the kettle body are fastened by bolts.

[0012] In an optional embodiment, between S2 and S3, the control method includes the following steps: After the test kettle is leak-free, vacuum evacuation, nitrogen purge and hydrogen purge are performed on the test kettle in sequence, and finally the pressure of the test kettle is stabilized to the preset pressure.

[0013] In an optional embodiment, after S4, the control method includes the following steps: Depressurize the pipeline.

[0014] In an optional embodiment, after S4, S6 includes: After the test is completed, the machine is stopped and the mold temperature controller is turned off; when the temperature in the kettle returns to room temperature, the kettle body is depressurized and after the depressurization is completed, nitrogen is purged in the kettle.

[0015] The beneficial effects of the hydrogen environment slow tensile testing machine and the control method thereof provided in this embodiment include: 1. Set up a test kettle and fill it with hydrogen to make the test kettle reach the test pressure and test temperature. At the same time, place the sample in the hydrogen environment of the test kettle for tensile test. The sample will not produce hydrogen precipitation, which is basically consistent with the service conditions of the sample, thus improving the accuracy of the hydrogen embrittlement performance test results of the sample; 2. Use an electric push rod to drive the kettle cover to close on the kettle body to avoid excessive closing force of the kettle cover on the kettle body and avoid collision and damage between the kettle cover and the kettle body; 3. The overall structure of the testing machine is cleverly designed, easy to disassemble and assemble, the tensile test operation process is simple and highly safe.

[0016] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A schematic structural diagram of a hydrogen environment slow tensile testing machine from a first perspective provided in an embodiment of the present application; Figure 2 A partially enlarged structural schematic diagram of a hydrogen environment slow tensile testing machine provided in an embodiment of the present application; Figure 3 for Figure 2 A schematic diagram of the enlarged structure of part a in the figure; Figure 4 for Figure 2 A schematic diagram of the enlarged structure of part b in the middle; Figure 5 for Figure 2 Schematic diagram of the section structure along the section line AA; Figure 6 for Figure 5 Schematic diagram of the enlarged structure of the local c in the middle; Figure 7 A schematic structural diagram of a second perspective of a hydrogen environment slow tensile testing machine provided in an embodiment of the present application; Figure 8 for Figure 7 A schematic diagram of the section structure along the section line BB; Fig. 9 for Figure 8 The enlarged schematic diagram after omitting the host frame; Fig.10 This is a flow chart of a control method for a hydrogen environment slow tensile testing machine provided in an embodiment of the present application.

[0019] Icons: 1-main frame; 2-test kettle; 21-kettle cover; 211-air inlet; 212-air outlet; 22-kettle body; 221-ball valve; 23-insulation layer; 24-filling block; 25-support frame; 3-pressure balancing device; 31-upper pull rod; 32-outer shell; 33-water jacket; 34-upper balance cylinder; 35-middle sealing flange; 36-lower pull rod; 37-lower balance cylinder; 4-electric push rod; 5-lifting beam; 6-clamp; 7-sample. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0021] In the description of this application, it should be noted that the terms "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the application is usually placed when in use, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0022] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] Please refer to Figures 1 to 9The present embodiment provides a hydrogen environment slow tensile testing machine, which includes a main frame 1, a test kettle 2, a support frame 25, a pressure balancing device 3, an electric push rod 4 and a lifting beam 5.

[0024] Among them, please refer to Figures 3 to 9 The test kettle 2 includes a kettle cover 21, a kettle body 22 and an insulation layer 23. The kettle body 22 is fixedly installed at the bottom of the main frame 1, and the insulation layer 23 is covered on the kettle body 22. The lifting beam 5 is installed on the top of the main frame 1 and can move in the vertical direction. The maximum moving stroke of the lifting beam 5 can be designed to be 60 mm, and a limiting device for the lifting beam 5 is set on the main frame 1.

[0025] One end of the electric push rod 4 is connected to the lifting beam 5, and the other end of the electric push rod 4 is detachably connected to the kettle cover 21, and the electric push rod 4 can drive the kettle cover 21 to cover the kettle body 22. The kettle cover 21 is connected to a support frame 25, and the support frame 25 is used to install the fixture 6 and the sample 7.

[0026] During the equipment assembly process, the specific working mode of the electric push rod 4 is: 1) Before the kettle body 22 and the kettle cover 21 are closed, the movement of the lifting beam 5 is stopped, and the electric push rod 4 is used to drive the kettle cover 21 to slowly cover the kettle body 22 to avoid excessive closing force of the kettle cover 21 on the kettle body 22; 2) When installing the fixture 6 after the kettle is opened, the electric push rod 4 is used to drive the kettle cover 21 to rise, so that the support frame 25 on the kettle cover 21 extends, which is convenient for installing the fixture 6 on the support frame 25.

[0027] During the tensile test, the specific working mode of the electric push rod 4 is: 1) Before the test, the connection between the electric push rod 4 and the kettle cover 21 must be disconnected, that is, the pin connecting the lower end of the electric push rod 4 and the kettle cover 21 must be loosened, and the lower end of the electric push rod 4 must be separated from the kettle cover 21 to avoid damage to the electric push rod 4 when the lifting beam 5 is raised or lowered; 2) After the test is completed, the lower end of the electric push rod 4 must be connected to the kettle cover 21, and the bolts and nuts connecting the kettle body 22 and the kettle cover 21 must be removed, and then the lifting beam 5 is raised to open the kettle.

[0028] One end of the pressure balancing device 3 is connected to the lifting beam 5, and the other end of the pressure balancing device 3 passes through the kettle cover 21 and is connected to the clamp 6. The lifting beam 5 can pull the pressure balancing device 3 and the clamp 6, thereby stretching the sample 7. At this time, the electric push rod 4 is disconnected from the kettle cover 21.

[0029] The kettle cover 21 of the test kettle 2 is provided with an air inlet 211 and an air outlet 212 , and the test kettle 2 is filled with hydrogen through the air inlet 211 and the air outlet 212 , so that the sample 7 is subjected to a tensile test in a hydrogen environment.

[0030] Among them, the test kettle 2 can be made of A286 material, and its maximum working pressure can reach 70MPa, and the working temperature is -55~+100℃. The installation method of the test kettle 2 is bolt-fastened. The sealing method of the kettle body 22 and the kettle cover 21 of the test kettle 2 is 2 O-ring seals, 1 axial seal, and 1 radial seal; the sealing method of the kettle cover 21 and the pressure balance device 3 is 1 O-ring axial seal. The installation form of the test kettle 2 is that the kettle body 22 is at the bottom and the kettle cover 21 is at the top. The bottom opening of the kettle body 22, the thermocouple, extensometer cable (high temperature penetration), etc. are all on the opening of the kettle body 22. When operating in the test kettle 2, the kettle cover 21 is required to be lifted until the support frame 25 in the kettle is completely exposed. Please refer to Figure 8 and Fig. 9 When conducting a hydrogen environment test, a filling block 24 (three filling blocks 24 are provided) may be installed on the kettle cover 21 to reduce the amount of hydrogen required in the kettle.

[0031] The inlet and outlet water pipes on the insulation layer 23 are equipped with a ball valve 221. When cooling or heating operations are required, the ball valve 221 must be opened. At the same time, observe whether there is any leakage at the beginning, and confirm that there is no leakage before heating. Specifically, the temperature control method for the kettle body 22 can adopt the oil bath heating method, and inject a certain temperature of heat transfer oil into the insulation layer 23 through the mold temperature controller to achieve the purpose of heating or cooling the medium in the test kettle 2. The temperature control method uses the temperature of the heat transfer oil in the mold temperature controller to indirectly control the temperature of the medium in the test kettle 2. If the temperature of the medium in the test kettle 2 is too high or too low, the temperature of the heat transfer oil in the mold temperature controller can be appropriately adjusted.

[0032] The pressure balancing device 3 includes an upper pull rod 31, a housing 32, and a water jacket 33 (please refer to Figures 2 to 4 ), upper balancing cylinder 34, middle sealing flange 35, lower tie rod 36 and lower balancing cylinder 37. Among them, the lifting beam 5, upper tie rod 31, lower tie rod 36 and clamp 6 are connected in sequence from top to bottom. The upper balancing cylinder 34 is connected to the lower balancing cylinder 37 through the middle sealing flange 35, the bottom of the lower balancing cylinder 37 is connected to the kettle cover 21 through bolts, the shell 32 is covered on the upper balancing cylinder 34 and the lower balancing cylinder 37, and the upper tie rod 31 and the lower tie rod 36 are slidably arranged in the upper balancing cylinder 34 and the lower balancing cylinder 37. Among them, a water jacket 33 is also arranged on the shell 32 to facilitate water circulation cooling in the shell 32.

[0033] It is worth noting that when conducting the tensile test, gas with the same pressure as that in the test kettle 2 must be introduced into the lower balance cylinder 37 so that balance can be achieved and the data obtained can be correct.

[0034] The fixture 6 used in this embodiment can be a rod slow tensile fixture, and of course can also be a fracture toughness specimen fixture, a fatigue crack extension specimen fixture, a low-cycle fatigue specimen fixture, etc.

[0035] Please refer to Fig.10 This embodiment also provides a control method for the above-mentioned hydrogen environment slow tensile testing machine. After the hydrogen environment slow tensile testing machine is assembled and the sample 7 and the fixture 6 are installed, the control method includes the following steps: S1: Control the electric push rod 4 to drive the kettle cover 21 to descend to the kettle body 22, and connect the kettle cover 21 and the kettle body 22 with bolts.

[0036] Specifically, the electric push rod 4 is operated with one hand, and the kettle cover 21 is held with the other hand to slowly lower the kettle cover 21. Since the gap between the inner diameter of the kettle body 22 and the clamp 6 is small, special attention should be paid to avoid the kettle body 22 hitting the clamp 6 when lowering.

[0037] The bolts on the kettle body 22 pass through the kettle cover 21, and the kettle body 22 is connected to the kettle cover 21. When the kettle cover 21 is lowered, slow down when the two are close to each other, and do not let the kettle cover 21 hit the kettle body 22. A little gap is reserved on the contact surface of the two.

[0038] Apply high-temperature lithium-based grease to the high-pressure sealing nuts and gaskets, and tighten the bolts manually; and tighten the bolts diagonally.

[0039] S2: Perform an airtightness test on the test kettle 2 to check whether the test kettle 2 is leaking.

[0040] Specifically, use the air circuit system to inflate the test kettle 2; if the test kettle 2 leaks, tighten the bolts again with a torque wrench; if the leakage cannot be eliminated by tightening the bolts, remove all the nuts of the test kettle 2 after removing the pressure in the kettle, and tighten the bolts of the test kettle 2 diagonally again; if the leakage still cannot be eliminated, remove the bolts and then remove the kettle cover 21, carefully check whether the sealing surface is damaged, and make sure that the sealing surface is not damaged, then reconnect the kettle cover 21 and the kettle body 22, and continue to inflate to check for leakage; repeat the above process until the test kettle 2 is leak-free.

[0041] The air tightness test of the test kettle 2 is carried out with nitrogen or oil-free dry air, and the test pressure is 1.05 to 1.1 times the design pressure. The test pressure should be gradually increased step by step. When the pressure rises to half of the test pressure, the pressure should be stopped and the pipeline should be fully checked. If there is no leakage or other abnormal phenomenon, the pressure can be gradually increased by 10% of the test pressure. The pressure should be stabilized for 5 minutes each time until the specified test pressure is reached, and then the pressure is stabilized for 5 minutes. It is qualified if there is no deformation after inspection. The air tightness test consists of two detection stages, high and low pressure. When the pressure reaches the test pressure, the pressure is maintained for 5 minutes, and the pressure is reduced to the design pressure. First, the welds and joints are checked, and all the welds and interfaces of the pipeline are brushed with leak detection liquid. If no bubbles are found, it means there is no leakage; then the pressure is maintained, and the test time should be no less than 30 minutes; after no pressure drop, the pressure is reduced to zero. The second test pressure is 2Mpa±10%, and the test time should be no less than 30 minutes. It is qualified if no leakage and no pressure drop are detected.

[0042] This embodiment uses nitrogen or helium to conduct the leakage test. The leakage rate (A) can be calculated as follows:

[0043] Where A is the average hourly leakage rate, t is the test time, p1 and p2 are the absolute pressures at the beginning and end of the test, respectively, and T1 and T2 are the absolute temperatures at the beginning and end of the test, respectively.

[0044] When using helium for leakage test, the pressure should be maintained for more than 1 hour, and the average hourly leakage rate should be less than 0.5% to be judged as qualified.

[0045] After the test kettle 2 is leak-free, vacuuming, nitrogen purging and hydrogen purging operations may be performed on the test kettle 2 in sequence, and finally the pressure of the test kettle 2 is stabilized to a preset pressure, where the preset pressure is less than the rated maximum pressure of the test kettle 2.

[0046] Among them, after the vacuum operation, the nitrogen purge operation fills the entire pipeline system and the test kettle 2 with nitrogen, and the pressure relief begins after the pressure in the pipeline system and the test kettle 2 reaches the preset value. The purpose of the vacuum operation and the nitrogen purge operation is to purge the system with nitrogen, replace the air in the pipeline, and reduce the oxygen content.

[0047] The pressure of nitrogen purge should be 0.1MPa~0.3Mpa, the gas velocity should not be less than 20m / s, and a white paint plate should be installed at the exhaust port for inspection. It should be qualified if there is no rust or other debris on the plate within 10 minutes. After the test and purge are qualified, nitrogen should be used to replace the oxygen content to less than 1%, and the nitrogen filling should be maintained at 0.2MPa.

[0048] After the nitrogen purge operation, the hydrogen purge operation fills the entire pipeline system and the test kettle 2 with hydrogen, and starts to release the pressure after the pressure in the pipeline system and the test kettle 2 reaches the preset value. The purpose of the hydrogen purge is to purge the system with hydrogen, replace the nitrogen in the pipeline, and increase the hydrogen concentration.

[0049] S3: Use a mold temperature controller to raise the temperature in the test kettle 2 to the test temperature.

[0050] Specifically, the mold temperature controller is turned on to perform oil bath heating or cooling on the kettle body 22. During this period, the pressure in the kettle must be observed. If the pressure in the kettle reaches the maximum pressure required for the test, exhaust and pressure reduction must be performed.

[0051] S4: After the test temperature is reached in the kettle, hydrogen is filled into the test kettle 2 to the test pressure.

[0052] Specifically, after the temperature in the kettle reaches the test temperature, the gas system is used again to fill the test kettle 2 with hydrogen to the test pressure.

[0053] After that, the pipeline can also be depressurized. First, the pipeline outside the test kettle 2 is vented and depressurized to avoid excessive depressurization affecting system safety. At this time, except for the high-pressure hydrogen left in the test kettle 2, the remaining pipelines have been depressurized separately, reducing the potential explosion energy of the system during the test.

[0054] S5: Perform a tensile test.

[0055] Specifically, after the pressure and temperature meet the test requirements, the test software is started and the tensile test operation is performed according to the software manual.

[0056] S6: After the test is completed, the machine is stopped, the mold temperature controller is turned off, and the pipeline and the kettle body 22 are depressurized.

[0057] Specifically, after the test is completed, the machine is stopped and the mold temperature controller is turned off; when the temperature in the kettle returns to room temperature, the kettle body 22 is depressurized slowly, and after the depressurization is completed, nitrogen is purged in the kettle.

[0058] The high-pressure hydrogen in the test kettle 2 is vented and depressurized to avoid excessive depressurization that affects system safety. When the pressure of the test kettle 2 returns to normal pressure, the steps of vacuuming and nitrogen purging are repeated until the hydrogen content in the test kettle 2 is reduced to a safe level.

[0059] After that, the hydrogen environment slow tensile testing machine can be disassembled, and the clamp 6 and the sample 7 can be removed.

[0060] The beneficial effects of the hydrogen environment slow tensile testing machine and the control method thereof provided in this embodiment include: 1. Set up a test kettle 2 and fill it with hydrogen to make the test kettle 2 reach the test pressure and test temperature. At the same time, place the sample 7 in the hydrogen environment of the test kettle 2 for tensile test. The sample 7 will not produce hydrogen precipitation, which is basically consistent with the service conditions of the sample 7, thereby improving the accuracy of the hydrogen embrittlement performance test results of the sample 7; 2. The electric push rod 4 is used to drive the kettle cover 21 to cover the kettle body 22, so as to avoid excessive closing force of the kettle cover 21 on the kettle body 22, and to avoid collision and damage between the kettle cover 21 and the kettle body 22; 3. The overall structure of the testing machine is cleverly designed, easy to disassemble and assemble, the tensile test operation process is simple and highly safe.

[0061] It should be noted that, in the absence of conflict, the features in the embodiments of this application may be combined with each other.

[0062] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A hydrogen environment slow tensile testing machine, characterized in that: The hydrogen environment slow tensile testing machine comprises a main frame (1), a test kettle (2), a support frame (25), a pressure balancing device (3), an electric push rod (4) and a lifting beam (5); The test kettle (2) comprises a kettle cover (21) and a kettle body (22); the kettle body (22) is fixedly mounted on the bottom of the main frame (1); the lifting beam (5) is mounted on the top of the main frame (1) and can move in a vertical direction; one end of the electric push rod (4) is connected to the lifting beam (5); the other end of the electric push rod (4) is detachably connected to the kettle cover (21); the electric push rod (4) can drive the kettle cover (21) to cover the kettle body (22); The support frame (25) is connected to the kettle cover (21), and the support frame (25) is used to install the clamp (6) and the sample (7). One end of the pressure balancing device (3) is connected to the lifting beam (5), and the other end of the pressure balancing device (3) passes through the kettle cover (21) and is connected to the clamp (6). The lifting beam (5) can pull the pressure balancing device (3) and the clamp (6), thereby stretching the sample (7). At this time, the electric push rod (4) is disconnected from the kettle cover (21); The test kettle (2) is provided with an air inlet (211) and an air outlet (212), and the test kettle (2) is filled with hydrogen through the air inlet (211) and the air outlet (212), so that the sample (7) is subjected to a tensile test in a hydrogen environment.

2. The hydrogen environment slow tensile testing machine according to claim 1, characterized in that: The sealing method between the kettle body (22) and the kettle cover (21) of the test kettle (2) is two O-ring seals, one axial seal and one radial seal; the sealing method between the kettle cover (21) and the pressure balancing device (3) is one O-ring axial seal.

3. The hydrogen environment slow tensile testing machine according to claim 1, characterized in that: A filling block (24) is installed on the kettle cover (21), and the filling block (24) is used to be inserted into the interior of the test kettle (2) to reduce the amount of hydrogen required in the kettle.

4. The hydrogen environment slow tensile testing machine according to claim 1, characterized in that: The pressure balancing device (3) comprises an upper pull rod (31), an upper balancing cylinder (34), a middle sealing flange (35), a lower pull rod (36) and a lower balancing cylinder (37); The lifting beam (5), the upper pull rod (31), the lower pull rod (36) and the clamp (6) are connected in sequence from top to bottom, the upper balancing cylinder body (34) is connected to the lower balancing cylinder body (37) via the middle sealing flange (35), the bottom of the lower balancing cylinder body (37) is connected to the kettle cover (21) via bolts, and the upper pull rod (31) and the lower pull rod (36) are slidably arranged in the upper balancing cylinder body (34) and the lower balancing cylinder body (37).

5. The hydrogen environment slow tensile testing machine according to claim 4, characterized in that: When performing the tensile test, gas having the same pressure as that in the test kettle (2) is introduced into the lower balancing cylinder (37).

6. A control method for a hydrogen environment slow tensile testing machine, characterized in that: The control method comprises the following steps: S1: controlling the electric push rod (4) to drive the kettle cover (21) to descend to the kettle body (22), and connecting the kettle cover (21) and the kettle body (22) by bolts; S2: performing an air tightness test on the test kettle (2) to check whether the test kettle (2) is leaking; S3: using a mold temperature controller to raise the temperature in the test kettle (2) to the test temperature; S4: After the test temperature is reached in the kettle, hydrogen is filled into the test kettle (2) to the test pressure; S5: Perform tensile test; S6: After the test is completed, the machine is stopped, the mold temperature controller is turned off, and the pipeline and the kettle body (22) are depressurized.

7. The control method of the hydrogen environment slow tensile testing machine according to claim 6, characterized in that: S1 includes: During the process of lowering the kettle cover (21), the lowering speed of the kettle cover (21) is first kept constant, then gradually reduced, and finally a gap is reserved with the kettle body (22), and finally the kettle cover (21) and the kettle body (22) are fastened by bolts.

8. The control method of the hydrogen environment slow tensile testing machine according to claim 6, characterized in that: Between S2 and S3, the control method comprises the following steps: After the test kettle (2) is leak-free, the test kettle (2) is subjected to vacuuming, nitrogen purging and hydrogen purging in sequence, and finally the pressure of the test kettle (2) is stabilized to a preset pressure.

9. The control method of the hydrogen environment slow tensile testing machine according to claim 8, characterized in that: After S4, the control method comprises the following steps: Depressurize the pipeline.

10. The control method of the hydrogen environment slow tensile testing machine according to claim 9, characterized in that: Following S4, S6 includes: After the test is completed, the machine is stopped and the mold temperature controller is turned off; when the temperature in the kettle returns to room temperature, the kettle body (22) is depressurized, and after the depressurization is completed, nitrogen is purged in the kettle.

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