A device and method for measuring stress corrosion crack growth rate in liquid ammonia environment

Abstract

The invention relates to a device and method for measuring the growth rate of stress corrosion cracks in a liquid ammonia environment. The device comprises a cooling mechanism and a high-pressure autoclave, a clamping member and a stirring blade. The cooling mechanism comprises a transmission member and a low-temperature refrigerator body. The high-pressure autoclave comprises a kettle body. The kettle body is arranged in the low-temperature refrigerator body, and a kettle cover is arranged on the top of the kettle body. A wire hole, an air inlet and an air outlet are provided on the kettle cover. An ammeter is installed on the kettle cover, and two first wires are arranged in the wire hole. The top ends of the two first wires are both connected to the ammeter, and the bottom ends are both extended into the kettle body for connecting a test piece. A pressure gauge is installed on the kettle cover for measuring the pressure in the autoclave. The clamping member is lifted and arranged in the kettle body for clamping the test piece. The stirring blade is rotatably arranged at the bottom of the kettle body. The stirring blade is connected to the transmission member, and the transmission member is used to drive the stirring blade to rotate. The device can effectively measure the growth rate of stress corrosion cracks in low-temperature toxic media, improve the measurement accuracy and efficiency, and facilitate the uniform distribution of liquid ammonia.

Description

Technical Field

[0001] The invention belongs to the technical field of stress corrosion, and in particular relates to a device and a method for measuring the growth rate of stress corrosion cracks in a liquid ammonia environment. Background Art

[0002] In the context of global carbon emission reduction, the research and application of ammonia as a zero-carbon fuel has received increasing attention. In principle, the storage temperature of liquid ammonia can be between -33 and -43°C. The process scheme is determined by controlling its corresponding vaporization pressure. Compared with storage at room temperature, the storage capacity can be increased by 20 times when the storage temperature is between -33 and -43°C.

[0003] Liquid ammonia is one of the working media that can easily cause stress corrosion of steel. Stress corrosion refers to the corrosion damage of metal components under the combined action of stress and corrosive environment. GB / T15970 defines the general environment for studying stress corrosion sensitivity and measuring the growth rate of stress corrosion cracks, but does not define the corrosion test methods under specific conditions such as low temperature and toxic media.

[0004] Liquid ammonia is an easily evaporable, flammable, explosive and moderately hazardous medium. The existing methods for measuring stress corrosion crack growth rate, such as the optical direct measurement method and the back strain method, cannot meet the requirements due to the volatility and toxicity of liquid ammonia. If the sample is placed in liquid ammonia for a period of time and then taken out for observation, the specific time when the crack stops growing cannot be determined, resulting in a large deviation in the measurement results. At present, there is no effective method for measuring stress corrosion crack growth rate under the combined state of low temperature and toxic media. Summary of the invention

[0005] In view of at least one problem in the above-mentioned prior art, the purpose of the present invention is to provide a measuring device and a measuring method for the stress corrosion crack growth rate in a liquid ammonia environment, which can effectively measure the stress corrosion crack growth rate in a low-temperature toxic medium, improve the measurement accuracy and measurement efficiency, and facilitate the uniform distribution of liquid ammonia.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A device for measuring stress corrosion crack growth rate in a liquid ammonia environment, comprising:

[0008] The cooling mechanism comprises a base, a transmission component and a low-temperature refrigerator body which are arranged in sequence;

[0009] The autoclave comprises an autoclave body; the autoclave body is arranged in the main body of the low-temperature freezer, and an autoclave cover is arranged on the top of the autoclave body; the autoclave cover is provided with a wire hole, an air inlet and an air outlet, the air inlet is used to inject ammonia, and the air outlet is used to discharge overflowed ammonia; an ammeter is installed on the autoclave cover, and two first wires are arranged in the wire hole; the top ends of the two first wires are connected to the ammeter, and the bottom ends are extended into the autoclave body for connecting the test piece; the autoclave cover is provided with a pressure gauge for measuring the pressure in the autoclave;

[0010] A clamping member, which is lifted and arranged in the kettle body and is used to clamp the test piece;

[0011] A stirring blade is rotatably arranged at the bottom of the kettle body; the stirring blade is connected to the transmission component, and the transmission component is used to drive the stirring blade to rotate.

[0012] Preferably, the air inlet is connected to an ammonia tank, and the air outlet is connected to a tail gas recovery tank; the tail gas recovery tank is connected to a waste liquid recovery tank;

[0013] The kettle cover is provided with a sealing member, and the sealing member is used for storing and accessing the test piece;

[0014] The sealing component includes a feeding port and a sealing cover, wherein the feeding port is opened on the kettle cover; one side edge of the sealing cover is rotatably connected to one side edge of the feeding port, and the other side edges of the sealing cover are connected to the other side edges of the feeding port by fastening bolts, and the sealing cover is used to open and seal the feeding port; a handle is connected to the sealing cover.

[0015] Preferably, the transmission component comprises a housing, a first motor, a pinion, a gear, a slot seat and a clamping rod;

[0016] The housing is mounted on the base, the first motor is mounted on the housing, the pinion gear and the large gear are both rotatably arranged in the housing; the pinion gear is connected to the first motor and meshes with the large gear; the top center position of the large gear is connected to the clamping rod, the slot seat is arranged on the top surface of the housing, and is fixedly connected to the inner bottom end of the low-temperature refrigerator body;

[0017] The autoclave comprises an outer insulation layer, which is sleeved on the outside of the autoclave body; a socket is arranged at the bottom end of the outer insulation layer, which is plugged into the slot seat;

[0018] The slot seat and the socket are provided with a clamping rod hole, the clamping rod is rotatably arranged in the clamping rod hole, and the top end of the clamping rod is clamped and connected inside the bottom end of the stirring blade.

[0019] Preferably, a support member is provided above the stirring blade, and the clamping member is provided on the support member;

[0020] The supporting member comprises a second motor and a screw rod, wherein the second motor is mounted on the kettle cover; the screw rod is rotatably connected to the second motor and is screwed into a threaded tube; the threaded tube is connected to an annular frame, a foot is arranged at the bottom of the annular frame, and the clamping member is arranged on the annular frame;

[0021] The annular frame is connected to a sleeve, and the sleeve is movably sleeved on the outside of the polished rod; the top end of the polished rod is connected to the kettle cover;

[0022] The sleeve and the polished rod form a pair and are symmetrically arranged on both sides of the lead screw.

[0023] Preferably, a leveling member is arranged between the supporting member and the clamping member, and the leveling member comprises a bracket, a convex block, a top block, a top plate and a first telescopic rod; the bracket is connected to the annular frame, the convex block is connected to the bracket, and a ball head is arranged on the top of the convex block; a hemispherical slot is arranged on the bottom surface of the top block, and the ball head is rotatably arranged in the hemispherical slot; the top plate is connected to the top block; the top and bottom ends of the first telescopic rod are rotatably connected to the first adapter and the second adapter respectively, and the first adapter and the second adapter are connected to the top plate and the annular frame respectively; the clamping member is connected to the top plate;

[0024] The number of the first telescopic rods is four and they are evenly arranged along the axial direction.

[0025] Preferably, the clamping member comprises a slot plate, a cavity is arranged inside the slot plate; the bottom surface of the slot plate is connected to the top plate;

[0026] The groove plate is rotatably provided with a toothed disc inside and movably provided with a first support plate and a second support plate; the first support plate and the second support plate are arranged on both sides of the toothed disc and are both provided with tooth grooves, and the tooth grooves are both engaged with the toothed disc;

[0027] Two opposite side walls of the slot plate are respectively provided with through holes, and the ends of the first support plate and the second support plate extend from the two through holes to the two sides of the outside of the slot plate respectively;

[0028] The first support plate and the second support plate are both connected with clamping plates, and the two clamping plates are respectively arranged on both sides of the outside of the slot plate, and are used to clamp the test piece placed on the slot plate;

[0029] A second telescopic rod is connected between the first support plate and the second support plate and two opposite side walls of the slot plate respectively.

[0030] Preferably, the first telescopic rod comprises a first slot tube, a first spring and a first insertion rod, the first spring is arranged at the inner bottom end of the first slot tube, the first insertion rod is movably arranged at the inner top end of the first slot tube, the bottom end and the top end of the first spring are respectively connected to the bottom end of the first slot tube and the bottom end of the first insertion rod; the top end of the first insertion rod is rotatably connected to the first adapter, and the bottom end of the first slot tube is rotatably connected to the second adapter;

[0031] The second telescopic rod includes a second slot tube, a second spring and a second insertion rod. The first support plate and the second support plate are respectively connected to one end of the second slot tube; the two opposite side walls of the slot plate are respectively connected to one end of the second insertion rod, and the other end of the second insertion rod is movably arranged in the other end of the second slot tube; the second spring is sleeved on the outside of the second slot tube and the second insertion rod.

[0032] Preferably, a flow guide barrel is connected to the kettle body, and at least two flow diversion grids are evenly distributed on the inner wall of the flow diversion barrel, and the flow diversion grids are all semi-spiral.

[0033] A method for measuring the stress corrosion crack growth rate in a liquid ammonia environment is implemented based on the above-mentioned measuring device, comprising the following steps:

[0034] Step S1, processing the material to be tested into a test piece, and prefabricating cracks on the test piece on a fatigue testing machine;

[0035] Step S2: Load the specimen to the set K Ii value;

[0036] Step S3, pasting an epoxy resin conductive adhesive strip on the crack tip of the test piece, and pasting an epoxy resin conductive adhesive strip at a set distance along the crack extension direction;

[0037] Step S4: Load K Ii The test piece is placed on the clamping member in the autoclave, one end of two second wires are respectively connected to the two ends of the epoxy resin conductive tape at the crack tip, and the other ends of the two second wires are respectively connected to the bottom ends of the two first wires; the top ends of the two first wires are connected to the ammeter;

[0038] Step S5, lowering the clamping member to the inner bottom end of the kettle body, and then introducing nitrogen into the kettle body to replace the air in the kettle body; then introducing liquid ammonia into the kettle body to replace the nitrogen in the kettle body, so that the oxygen content in the kettle body is less than a set value; placing the kettle cover on the kettle body, pressurizing the kettle body to a set pressure value, so that the ammonia in the kettle body is liquefied, and the test piece is placed in the liquid ammonia;

[0039] Step S6, placing the autoclave at the inner bottom end of the low-temperature refrigerator body of the temperature-lowering mechanism, and connecting the stirring blade to the transmission member; driving the stirring blade to rotate at the inner bottom end of the autoclave body through the transmission member to stir the liquid ammonia in the autoclave body; then the transmission member stops working, and the liquid ammonia in the autoclave body is cooled to a set temperature through the low-temperature refrigerator body, and then the crack extension time of the test piece is started to be timed;

[0040] Step S7, observing the reading of the ammeter, when the reading of the ammeter is zero, it indicates that the epoxy resin conductive adhesive strip is broken, and the crack has extended to the position where the epoxy resin conductive adhesive is located; at this time, the kettle cover is opened, the clamping member is raised and moved to the top of the kettle body, and the test piece is taken out; the cracks on the surface of the test piece are observed through a reading microscope, the crack extension length and crack extension time are recorded, and the crack extension rate is calculated;

[0041] Step S8, reconnecting one end of the two second conductive wires to the two ends of the next epoxy resin conductive tape in the crack extension direction, and repeating steps S5 to S8 until the crack extension rate is lower than the set value.

[0042] Preferably,

[0043] In step S1, the length of the prefabricated crack is controlled until the dimension of the side that crosses the incision is a set percentage of the thickness of the specimen or a set thickness, whichever is greater; the set percentage of the thickness of the specimen is 2.5% of the thickness of the specimen;

[0044] In step S3, the diameter of the epoxy resin conductive tape is 0.5 mm, and the set distance is set to 2 mm;

[0045] In step S5, the oxygen content in the kettle is less than 1 mg / L;

[0046] After step S8, steps S9 and S10 are performed:

[0047] Step S9: Load the specimen with different K Ii value, and repeat steps S2 to S8;

[0048] Step S10: Obtain the stress intensity factor K corresponding to when the crack growth rate drops to a set value I , is the threshold value K of stress corrosion crack extension of the material in low temperature liquid ammonia environment Iscc .

[0049] The present invention adopts the above technical solution, which has the following advantages:

[0050] 1. The device and method for measuring the stress corrosion crack growth rate in a liquid ammonia environment provided by the present invention can solve the problem that the stress corrosion crack growth rate in a low-temperature toxic medium cannot be measured in the prior art, and can perform experiments on multiple specimens; can reduce the vibration interference of the specimens during the experiment, improve the accuracy of the experimental results, and shorten the experimental cycle; can optimize the structural layout inside the kettle body, ensure uniform distribution of liquid ammonia, and reduce stress concentration caused by excessively high or low local liquid ammonia concentrations.

[0051] 2. The device and method for measuring the stress corrosion crack growth rate in a liquid ammonia environment provided by the present invention can guide the liquid ammonia inside the autoclave through the cooperation of the guide barrel and the stirring blade arranged in the autoclave, thereby optimizing the layout inside the autoclave; making the liquid ammonia distribution more uniform, and reducing the stress concentration caused by excessively high or low local liquid ammonia concentration.

[0052] 3. The device and method for measuring the stress corrosion crack growth rate in a liquid ammonia environment provided by the present invention can center and straighten the specimen through the cooperation of the supporting member, the leveling assembly and the clamping member, so that the position of the specimen is maintained at the inner center of the kettle body; it is convenient to fix or take the specimen and to observe the specimen; through the cooperation between the protrusion, the top block and the multiple first telescopic rods in the supporting member, the specimen can be automatically leveled, and the specimen can be buffered and shock-absorbed, thereby reducing vibration interference during the experiment and improving the accuracy of the experimental results.

[0053] 4. The measuring device and method for stress corrosion crack growth rate in a liquid ammonia environment provided by the present invention can pass through an exhaust gas recovery tank and a waste liquid recovery tank, and dilute hydrochloric acid is filled inside the exhaust gas recovery tank to absorb the liquid ammonia exhaust gas, and the residual gas cylinder can be recovered through the waste liquid recovery tank to prevent discharge into the environment, making the experimental process green and environmentally friendly.

[0054] 5. The method for measuring the growth rate of stress corrosion cracks in a liquid ammonia environment provided by the present invention is to stick an epoxy resin conductive tape at the crack tip of the specimen, and stick one at a preset distance along the crack growth direction, and connect one end of two second wires to the two ends of the epoxy resin conductive tape at the crack tip, respectively, and connect the other ends to the two first wires below the wire holes, respectively, and connect the other ends of the two first wires to an ammeter; by observing the ammeter reading, when the ammeter reading is zero, it indicates that the epoxy resin conductive tape is broken, that is, the crack grows to the position of the epoxy resin conductive tape, and the specific time when the crack stops growing can be determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1It is a connection schematic diagram of the use status of a device for measuring stress corrosion crack growth rate in a liquid ammonia environment provided by one embodiment of the present invention.

[0056] Figure 2 It is a schematic diagram of the connection structure of a device for measuring stress corrosion crack growth rate in a liquid ammonia environment provided by one embodiment of the present invention.

[0057] Figure 3 The present invention Figure 2 Schematic diagram of the connection structure of the cooling mechanism.

[0058] Figure 4 The present invention Figure 3 Cross-sectional view of the connection structure of the intermediate cooling mechanism.

[0059] Figure 5 The present invention Figure 2 Schematic diagram of the connection structure of the medium and high pressure autoclave.

[0060] Figure 6 The present invention Figure 5 A partial enlarged view of the connection structure of the medium and high pressure autoclave.

[0061] Figure 7 The present invention Figure 4 Cross-sectional view of the connection structure of the outer insulation layer of the medium and high pressure autoclave, the autoclave body, the guide barrel, the socket and the stirring blade.

[0062] Figure 8 The present invention Figure 7 Schematic diagram of the connection structure of the middle guide barrel.

[0063] Fig. 9 The present invention Figure 5 Schematic diagram of the connection structure between the middle support member and the clamping member.

[0064] Fig.10 The present invention Fig. 9 A partial enlarged view of the connection structure of the middle support member.

[0065] Fig.11 The present invention Fig. 9 Cross-sectional view of the connection structure of the clamping member.

[0066] Fig.12 It is a flow chart of a method for measuring stress corrosion crack growth rate in a liquid ammonia environment provided by one embodiment of the present invention.

[0067] Markings in the accompanying drawings:

[0068] 1. Cooling mechanism; 101. Base; 102. Transmission component; 1021. Shell; 1022. First motor; 1023. Pinion; 1024. Gear; 1025. Slot seat; 1026. Clamping rod; 103. Low-temperature freezer body; 2. Autoclave; 201. External insulation layer; 202. Autoclave body; 203. Autoclave cover; 204. Covering component; 2041. Material taking port; 2042. Sealing cover; 2043. Handle; 2044. Fastening bolt; 205. Diversion barrel; 206. Socket; 207. Stirring blade; 208. Supporting component; 2081. Second motor; 2082. Screw rod; 2083. Light rod; 2 084, threaded tube; 2085, ring frame; 2086, sleeve; 2087, foot; 2088, bracket; 2089, protrusion; 20810, top block; 20811, top plate; 20812, first adapter; 20813, first telescopic rod; 20814, second adapter; 209, clamping member; 2091, groove plate; 2092, gear plate; 2093, first support plate; 2094, second support plate; 2095, clamping plate; 2096, second telescopic rod; 3, wire hole; 4, air inlet; 5, pressure gauge; 6, air outlet; 7, ammonia tank; 8, tail gas recovery tank; 9, waste liquid recovery tank; 10, ammeter. DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0070] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "front", "rear", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or component referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. The direction of the arrow in the figure represents the direction of liquid flow.

[0071] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "assembly", "setting", and "connection" 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0072] The present invention provides a device and method for measuring the stress corrosion crack growth rate in a liquid ammonia environment, which can solve the problem that the stress corrosion crack growth rate in a low-temperature toxic medium cannot be measured in the prior art, improve the accuracy of experimental results, shorten the experimental period; optimize the structural layout inside the kettle body, and ensure uniform distribution of liquid ammonia.

[0073] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0074] Example 1

[0075] Please refer to Figures 1 to 7 The present embodiment provides a stress corrosion crack growth rate measuring device in a liquid ammonia environment, comprising a cooling mechanism 1 and an autoclave 2, a clamping member 209 and a stirring blade 207, wherein the cooling mechanism 1 comprises a base 101, a transmission member 102 and a low-temperature refrigerator body 103 arranged in sequence; the autoclave 2 comprises a kettle body 202; the kettle body 202 is arranged in the low-temperature refrigerator body 103, and a kettle cover 203 is arranged on the top of the kettle body 202; the kettle cover 203 is provided with a wire hole 3, an air inlet 4 and an air outlet 6, the air inlet 4 is used to inject ammonia gas, and the air outlet 6 is used to inject ammonia gas. The overflowing ammonia is discharged; the kettle cover 203 is equipped with an ammeter 10, and two first wires are arranged in the wire hole 3; the top ends of the two first wires are connected to the ammeter 10, and the bottom ends are extended into the kettle body 202 for connecting the test piece; the kettle cover 203 is equipped with a pressure gauge 5 for measuring the pressure in the autoclave 2; the clamping member 209 is arranged in the kettle body 202 for clamping the test piece; the stirring blade 207 is rotatably arranged at the bottom of the kettle body 202; the stirring blade 207 is connected to the transmission member 102, and the transmission member 102 is used to drive the stirring blade 207 to rotate.

[0076] In the device for measuring the stress corrosion crack growth rate in a liquid ammonia environment of this embodiment, the base 101 is used to support the transmission member 102. The autoclave 2 is arranged in the cooling mechanism 1. When in use, the autoclave body 202 of the autoclave 2 is used to introduce ammonia gas and pressurize it, and the low-temperature refrigerator body 103 of the cooling mechanism 1 is used to cool the ammonia gas in the autoclave body 202, so that the temperature of the liquid ammonia drops to the set temperature to meet the experimental use standard requirements; the autoclave cover 203 is used to open or close the autoclave body 202; the clamping member 209 is used to rise to the autoclave cover 203 to clamp the specimen on the clamping member 209, or remove the specimen from the clamping member 209; the clamping member 209 is also used to carry the specimen down to the bottom of the autoclave body 202, so that the specimen is placed in the liquid ammonia; the transmission member 102 is used to drive the stirring blade 207 to rotate, thereby stirring the liquid ammonia to make it more evenly distributed. The outer wall of the test piece is processed with an epoxy resin conductive adhesive coating or an epoxy resin conductive adhesive strip, and a second wire is bonded to the epoxy resin conductive adhesive coating or the epoxy resin conductive adhesive strip, and the second wire is connected to the first wire. The pressure gauge 5 is used to measure the pressure in the kettle body 202.

[0077] The transmission member 102 is arranged at the top of the base 101, and the low-temperature freezer body 103 is arranged at the top of the transmission member 102. The kettle cover 203 is screwed to the top of the kettle body 202. For example, the side wall of the kettle cover 203 is provided with an external thread, and the top inner wall of the kettle body 202 is provided with an internal thread. The wire hole 3, the air inlet 4, the pressure gauge 5 and the air outlet 6 can be arranged in sequence at a position on one side of the rear end of the kettle cover 203. The bottom end of the pressure gauge 5 is screwed to the upper surface of the kettle cover 203 through a flange.

[0078] For details, please refer to Figure 1 The air inlet 4 is connected to the ammonia tank 7, and the air outlet 6 is connected to the tail gas recovery tank 8; the tail gas recovery tank 8 is connected to the waste liquid recovery tank 9; the kettle cover 203 is provided with a sealing member 204, and the sealing member 204 is used for storing and accessing the test piece;

[0079] Please refer to Figure 1 , Figure 2 , Figure 5 and Figure 6 The sealing component 204 includes a feeding port 2041 and a sealing cover 2042. The feeding port 2041 is opened on the kettle cover 203; one side edge of the sealing cover 2042 is rotatably connected to one side edge of the feeding port 2041, and the other side edges of the sealing cover 2042 are connected to the other side edges of the feeding port 2041 through fastening bolts 2044. The sealing cover 2042 is used to open and seal the feeding port 2041; a handle 2043 is connected to the sealing cover 2042.

[0080] Among them, the ammonia tank 7, the autoclave 2, the tail gas recovery tank 8 and the waste liquid recovery tank 9 are arranged in sequence.

[0081] When testing the specimen, the ammonia tank 7 is connected to the air inlet 4 through the ammonia connecting pipe, and the ammonia is passed into the autoclave 202; by pressurizing the autoclave 2, the internal pressure of which reaches the set pressure, the ammonia inside the autoclave 2 is liquefied. During the liquefaction of ammonia and the experiment, liquid ammonia tail gas will be discharged through the exhaust port 6. The air outlet 6 is connected and communicated with one side of the top of the tail gas recovery tank 8 through the tail gas recovery pipe. The tail gas recovery tank 8 is filled with dilute hydrochloric acid, and one end of the tail gas recovery pipe extends to the inside of the tail gas recovery tank 8 and extends below the liquid level of the dilute hydrochloric acid, and the liquid ammonia tail gas is absorbed by the dilute hydrochloric acid. The other side of the top of the tail gas recovery tank 8 is connected and communicated with the waste liquid recovery tank 9 through the tail gas discharge pipe. The residual volatile gas is discharged into the interior of the waste liquid recovery tank 9 through the tail gas discharge pipe, and the volatile gas and the waste liquid formed are collected by the waste liquid recovery tank 9 to avoid discharge to the environment, making the experiment green and environmentally friendly.

[0082] The sealing cover 2042 is used to cover the material taking port 2041. The sealing cover member 204 facilitates the storage and access of the test piece, avoiding the need to unscrew the kettle cover 203 from the top of the kettle body 202 when placing or removing the test piece during the experiment, which can facilitate the placement or removal of the test piece and improve the operating efficiency.

[0083] The sealing member 204 is arranged at a side position of the front end of the kettle cover 203. The sealing cover 2042 is rotatably connected to the top of the material discharging port 2041 through a hinge. The handle 2043 is fixedly connected to the top center of the sealing cover 2042, and the handle 2043 is used to drive the sealing cover 2042 to open and close. The remaining side edges of the sealing cover 2042 are connected to the remaining side edges of the material discharging port 2041 through at least two fastening bolts 2044. A rubber sealing pad is arranged on the outer side of the bottom surface of the sealing cover 2042, and the rubber sealing pad is used to enhance the sealing performance of the sealing cover 2042.

[0084] Please refer to Figures 2 to 3 and Figure 7 Specifically, the transmission component 102 includes a housing 1021, a first motor 1022, a pinion 1023, a large gear 1024, a slot seat 1025 and a clamping rod 1026; the housing 1021 is mounted on the base 101, the first motor 1022 is mounted on the housing 1021, and the pinion 1023 and the large gear 1024 are both rotatably arranged in the housing 1021; the pinion 1023 is connected to the first motor 1022 and meshes with the large gear 1024; the clamping rod is connected to the top center of the large gear 1024 1026, the slot seat 1025 is arranged on the top surface of the shell 1021 and is fixedly connected to the inner bottom end of the low-temperature freezer body 103; the autoclave 2 includes an outer insulation layer 201, and the outer insulation layer 201 is sleeved on the outside of the autoclave body 202; a socket 206 is arranged at the bottom end of the outer insulation layer 201, and the socket 206 is plugged into the slot seat 1025; the slot seat 1025 and the socket 206 are provided with a clamping rod hole, and the clamping rod 1026 is rotatably arranged in the clamping rod hole, and the top end of the clamping rod 1026 is clamped and connected to the bottom end of the stirring blade 207.

[0085] The kettle body 202 is fixedly connected to the inside of the outer insulation layer 201. The socket 206 is fixedly connected to the bottom center of the outer insulation layer 201. The outer insulation layer 201 is plugged into the inside of the low-temperature freezer body 103. The outer insulation layer 201 is used to insulate the kettle body 202, reduce the heat loss of liquid ammonia during storage, and improve the storage efficiency of liquid ammonia.

[0086] The first motor 1022 is screwed to the upper surface of the housing 1021 through a flange, and the output shaft at the bottom is fixedly connected to the top of the rotating shaft of the pinion 1023 to drive the pinion 1023, the large gear 1024, the clamping rod 1026 and the stirring blade 207 to rotate.

[0087] The clamping rod 1026 is rotatably arranged at the inner center of the slot seat 1025, and the bottom end of the clamping rod 1026 penetrates the bottom center of the low-temperature freezer body 103 and extends to the inside of the shell 1021. The top center of the large gear 1024 is fixedly connected to the bottom end of the clamping rod 1026, and the socket 206 is inserted into the top inner part of the slot seat 1025. The stirring blade 207 is rotatably connected to the inner bottom center of the kettle body 202 through the stirring shaft. The bottom end of the stirring blade 207 is provided with a clamping groove, and the top end of the clamping rod 1026 is clamped and connected in the clamping groove.

[0088] The shell 1021 is fixedly connected to the top of the base 101. The low temperature refrigerator body is fixedly connected to the top of the shell 1021.

[0089] Please refer to Figure 4 , Figure 7 , Fig. 9 and Fig.10 Specifically, a support member 208 is arranged above the stirring blade 207, and a clamping member 209 is arranged on the support member 208; the support member 208 includes a second motor 2081 and a screw rod 2082, and the second motor 2081 is installed on the kettle cover 203; the screw rod 2082 is rotatably connected to the second motor 2081 and is screwed in the threaded tube 2084; the threaded tube 2084 is connected to the annular frame 2085, a base 2087 is arranged at the bottom of the annular frame 2085, and the clamping member 209 is arranged on the annular frame 2085; the annular frame 2085 is connected to the sleeve 2086, and the sleeve 2086 is movably sleeved on the outside of the light rod 2083; the top end of the light rod 2083 is connected to the kettle cover 203; the sleeve 2086 and the light rod 2083 are arranged in pairs and symmetrically on both sides of the screw rod 2082.

[0090] The second motor 2081 is used to drive the screw 2082 to rotate. The screw 2082 is used to drive the threaded tube 2084, the annular frame 2085, the sleeve 2086, the clamping member 209 and the test piece to move up and down. When the sleeve 2086 moves up and down with the annular frame 2085, it plays a guiding role through the light rod 2083, which is conducive to ensuring that the test piece moves vertically up and down. The foot 2087 is used to support the annular frame 2085.

[0091] The clamping member 209 is disposed at the top end of the supporting member 208. The rear end of the annular frame 2085 is fixedly connected to the outer wall of the threaded tube 2084. There are at least two feet 2087, and the plurality of feet 2087 are evenly arranged and fixedly connected to the bottom end of the annular frame 2085. The feet 2087 are fixedly connected to the bottom end of the annular frame 2085, and are at least two and evenly arranged.

[0092] The second motor 2081 is screwed to the center of the rear end of the upper surface of the kettle cover 203 through a flange. An output shaft is arranged at the bottom end of the second motor 2081, and the output shaft is locked and connected to the screw rod 2082 through a coupling. The top end of the screw rod 2082 is rotatably connected to the center of the rear end of the lower surface of the kettle cover 203. The top ends of the two polished rods 2083 are fixedly connected to the lower surface of the kettle cover 203.

[0093] Please refer to Fig. 9 and Fig.10 Specifically, a leveling member is arranged between the supporting member 208 and the clamping member 209, and the leveling member includes a bracket 2088, a protrusion 2089, a top block 20810, a top plate 20811 and a first telescopic rod 20813; the bracket 2088 is connected to the annular frame 2085, the protrusion 2089 is connected to the bracket 2088, and a ball head is arranged on the top of the protrusion 2089; a hemispherical slot is arranged on the bottom surface of the top block 20810, and the ball head is arranged on the hemispherical slot. In the surface card slot; the top plate 20811 is connected to the top block 20810; the top and bottom ends of the first telescopic rod 20813 are rotatably connected to the first adapter 20812 and the second adapter 20814 respectively, and the first adapter 20812 and the second adapter 20814 are respectively connected to the top plate 20811 and the annular frame 2085; the clamping member 209 is connected to the top plate 20811; the first telescopic rod 20813 is set to four, and is evenly arranged along the axial direction.

[0094] The leveling member adjusts the horizontality of the clamping member 209 so that the specimen clamped in the clamping member 209 remains horizontal, which is conducive to more uniform contact between the specimen and the liquid ammonia; and the clamping member 209 is buffered to prevent the specimen from shaking during the experiment.

[0095] The protrusion 2089 supports the top block 20810, and the top block 20810 can rotate on the protrusion 2089. The first adapter 20812 is used to support the top end of the first telescopic rod 20813, and the first telescopic rod 20813 is used to support the top plate 20811. The second adapter 20814 is used to support the bottom end of the first telescopic rod 20813. Through the mutual cooperation between the four first telescopic rods 20813, when one of the first telescopic rods 20813 is contracted, the first telescopic rod 20813 on the other side symmetrical to the contracted first telescopic rod 20813 will extend, so that the clamping member 209 and the test piece installed on the inner side of the top of the clamping member 209 can be automatically leveled; and the clamping member 209 can be buffered and shock-absorbed to reduce vibration interference during the experiment and improve the accuracy of the experimental results.

[0096] The protrusion 2089 is fixedly connected to the top center of the bracket 2088. The top plate 20811 is fixedly connected to the top of the top block 20810. The top plate 20810 is set as a rectangular plate, and the four corners of the top plate 20811 are respectively connected to the top outer side of the four first adapters 20812. The top of the first telescopic rod 20813 is rotatably connected to the inner side of the bottom end of the first adapter 20812, and the bottom is rotatably connected to the inner side of the top of the second adapter 20814. The inner four corners of the annular frame 2085 are respectively connected to the outer side of the bottom ends of the four second adapters 20814. The bracket 2088 is fixedly connected to the inner center of the annular frame 2085.

[0097] Please refer to Fig. 9 and Fig.11 Specifically, the clamping member 209 includes a slot plate 2091, and a cavity is arranged inside the slot plate 2091; the bottom surface of the slot plate 2091 is connected to the top plate 20811; a toothed disc 2092 is rotatably arranged inside the slot plate 2091, and a first support plate 2093 and a second support plate 2094 are movably arranged; the first support plate 2093 and the second support plate 2094 are arranged on both sides of the toothed disc 2092, and both are provided with tooth grooves, and the tooth grooves are engaged with the toothed disc 2092; the two opposite side walls of the slot plate 2091 are divided into The first support plate 2093 and the second support plate 2094 are provided with through holes, and the ends of the first support plate 2093 and the second support plate 2094 extend out from the two through holes to the two sides of the outside of the slot plate 2091 respectively; the first support plate 2093 and the second support plate 2094 are both connected with clamping plates 2095, and the two clamping plates 2095 are respectively arranged on the two sides of the outside of the slot plate 2091, for clamping the test piece placed on the slot plate 2091; the first support plate 2093 and the second support plate 2094 are respectively connected with second telescopic rods 2096 between the two opposite side walls of the slot plate 2091.

[0098] in, Fig.11 The top surface of the slot plate 2091 is not shown. The top surface of the slot plate 2091 is used to place and support the test piece. The internal cavity of the slot plate 2091 and the perforations on the side wall can guide and limit the movement trajectory of the first support plate 2093 and the second support plate 2094.

[0099] When the first support plate 2093 is pulled or pushed in one direction to move, the first support plate 2093 drives the toothed disc 2092 to rotate, and the toothed disc 2092 drives the second support plate 2094 to move in another direction; that is, when the toothed disc 2092 rotates, the first support plate 2093 and the second support plate 2094 move in opposite directions, so that the two clamping plates 2095 respectively arranged on the first support plate 2093 and the second support plate 2094 are moved closer or farther away, so that the two clamping plates 2095 clamp or release the specimen.

[0100] The second telescopic rod 2096 is used to reset the first support plate 2093 and the second support plate 2094 and apply a clamping force toward the specimen to the first support plate 2093 and the second support plate 2094. The clamping force enables the two clamping plates 2095 to clamp the specimen.

[0101] The extension direction of the second telescopic rod 2096 is parallel to the moving direction of the first support plate 2093 and the second support plate 2094. The top surface of the clamping plate 2095 is higher than the top surface of the slot plate 2091 and is used to clamp the test piece.

[0102] The toothed disc 2092 is rotatably connected to the inner center of the groove plate 2091. The bottom surface of the groove plate 2091 is fixed to the top surface of the top plate 20811. The inner side surfaces of the first support plate 2093 and the second support plate 2094 are both provided with tooth grooves. The inner side here refers to the side close to the toothed disc 2092. The top surfaces of the first support plate 2093 and the second support plate 2094 are both connected with a clamping plate 2095.

[0103] Please refer to Figures 9 to 11 Specifically, the first telescopic rod 20813 includes a first slot tube, a first spring and a first plug rod, the first spring is arranged at the inner bottom end of the first slot tube, the first plug rod is movably arranged at the inner top end of the first slot tube, the bottom end and the top end of the first spring are respectively connected to the bottom end of the first slot tube and the bottom end of the first plug rod; the top end of the first plug rod is rotatably connected to the first adapter 20812, and the bottom end of the first slot tube is rotatably connected to the second adapter 20814;

[0104] The second telescopic rod 2096 includes a second slot tube, a second spring and a second insertion rod. The first support plate 2093 and the second support plate 2094 are respectively connected to one end of the second slot tube; the two opposite side walls of the slot plate 2091 are respectively connected to one end of the second insertion rod, and the other end of the second insertion rod is movably arranged in the other end of the second slot tube; the second spring is arranged on the outside of the second slot tube and the second insertion rod.

[0105] Among them, when the second insertion rod slides out from the inside of the second groove tube, the second spring will be stretched as a whole; the elastic deformation of the second spring generates a rebound force, thereby resetting the first support plate 2093 or the second support plate 2094; and the first support plate 2093 and the second support plate 2094 can have a centering clamping force, so that the specimen is center-clamped, so that the specimen is fixed on the top of the groove plate 2091, and it can also be automatically centered and straightened, so that the specimen is at the center of the top of the groove plate 2091; it is beneficial for the contact between the specimen and the liquid ammonia to be more uniform, and it is convenient to fix or take the specimen.

[0106] The bottom end of the first spring is fixedly connected to the bottom end of the first slot tube, and the top end is fixedly connected to the bottom end of the first plug rod. The top end of the first plug rod is rotatably connected to the inner side of the bottom end of the first adapter 20812. The bottom end of the first slot tube is rotatably connected to the inner side of the top end of the second adapter 20814.

[0107] One end of the second spring is connected to one end of the second plunger, and the other end is connected to one end of the second slot tube. One end of the second plunger and one end of the second slot tube are respectively provided with end plates, and the two side surfaces of the end plate of the second plunger are respectively connected to one side wall of the slot plate 2091 and one end of the second spring. The two side surfaces of the end plate of the second slot tube are respectively connected to the opposite side wall of the slot plate 2091 and the other end of the second spring.

[0108] Please refer to Figure 7 and Figure 8 As shown, specifically, a flow guide barrel 205 is connected to the kettle body 202, and at least two flow diversion grids are evenly distributed on the inner wall of the flow diversion barrel 205, and the flow diversion grids are semi-spiral.

[0109] The guide barrel 205 is fixedly connected to the inside of the kettle body 202. The guide barrel 205 is used to guide the liquid ammonia inside the kettle body 202, optimize the layout inside the kettle body 202, make the liquid ammonia flow evenly to the inside of the kettle body 202, and make the liquid ammonia inside the kettle body 202 more evenly distributed, reducing the stress concentration caused by excessively high or low local liquid ammonia concentration.

[0110] Please refer to Figures 1 to 11In the device for measuring the stress corrosion crack growth rate in a liquid ammonia environment of this embodiment, when it is necessary to measure the stress corrosion crack growth rate of a specimen in a liquid ammonia environment, the second motor 2081 in the support member 208 drives the screw rod 2082 to rotate, thereby driving the threaded tube 2084 to move upward through the screw rod 2082, and driving the annular frame 2085 to rise to the inner top of the kettle body 202; then the specimen prepared in advance is placed in the clamp through the material taking port 2041 in the cover member 204 Before placing, the first support plate 2093 in the clamping member 209 is pulled to one side. When the first support plate 2093 slides to one side, the toothed plate 2092 is driven to rotate through the tooth groove of the first support plate 2093. When the toothed plate 2092 rotates, it drives the second support plate 2094 to slide to the other side, thereby simultaneously moving the first support plate 2093 and the second support plate 2094 outward, so that the two clamping plates 2095 expand outward, and then the test piece is placed on the slot plate 2091. The first support plate 2093 is then released, and the first support plate 2093 and the second support plate 2094 are driven to slide inward at the same time by the rebound force generated by the two second telescopic rods 2096, so as to clamp the outer side of the specimen and align the specimen to the top center of the slot plate 2091; when the specimen is clamped, the second motor 2081 is controlled to rotate in the opposite direction, so as to drive the annular frame 2085 to slide downward, so as to drive the specimen to move to the inner bottom end of the kettle body 202; when the specimen is clamped, the second motor 2081 is controlled to rotate in the opposite direction, so as to drive the annular frame 2085 to slide downward, so as to drive the specimen to move to the inner bottom end of the kettle body 202; After being placed on the clamping member 209, weight can be applied to the top plate 20811 through the self-weight of the specimen and the clamping member 209; the top plate 20811 can be automatically leveled through the mutual cooperation between the multiple first telescopic rods 20813, the protrusions 2089 and the top block 20810; the specimen clamped on the inner side of the clamping member 209 is kept horizontal, and the vibration exerted on the specimen can be buffered, thereby reducing the vibration interference exerted on the specimen during the experiment and improving the accuracy of the experimental results.

[0111] In the device for measuring the stress corrosion crack growth rate in a liquid ammonia environment of this embodiment, before measuring the stress corrosion crack growth rate of the test piece in a liquid ammonia environment, the autoclave 2 is inserted as a whole into the interior of the low-temperature refrigerator body 103 of the cooling mechanism 1, and the socket 206 is plugged into the top interior of the slot seat 1025, so that the clamping rod 1026 is engaged with the bottom end of the stirring blade 207; then the test piece to be tested is clamped to the top of the clamping member 209, and the test piece is centered and straightened by the clamping member 209 and the leveling assembly, and the test piece is clamped and fixed to the top center of the slot plate 2091; after the test piece is installed, the epoxy resin processed on the outer wall of the test piece is Conductive adhesive coating or epoxy resin conductive adhesive strip pasted on the outer wall of the specimen, and a second wire bonded to the epoxy resin conductive adhesive coating or the epoxy resin conductive adhesive strip, connect the wire 2 with the first wire extending from the inside of the wire hole 3; after connecting the wire 1 and the wire 2, the specimen is driven to descend to the inner bottom end of the kettle body 202 through the support member 208, and the specimen is automatically leveled under the cooperation between the protrusion 2089, the top block 20810 and the first telescopic rod 20813, and the clamping member 209 and the specimen are buffered as a whole, so as to reduce the vibration interference to the specimen during the experiment; then the air inlet 4 is passed through the ammonia The connecting pipe is connected to the ammonia tank 7, and the gas outlet 6 is connected to the tail gas recovery tank 8 through the tail gas recovery pipe, and the other side of the top of the tail gas recovery tank 8 is connected to the waste liquid recovery tank 9 through the tail gas discharge pipe; after completing the preparatory work before the experiment, high-purity N2 is introduced into the autoclave 2 to replace the air in the autoclave 2; then liquid ammonia is introduced to replace the N2 in the autoclave 2, so that the oxygen content in the autoclave 2 is less than 1 mg / L; after the liquid ammonia is introduced into the autoclave 2, it is pressurized to the set pressure to liquefy the ammonia inside the autoclave 2; the stirring blade 207 is driven to rotate slowly by the transmission component 102, so as to stir the liquid ammonia inside the autoclave 2; The mutual cooperation between the stirring blade 207 and the guide barrel 205 allows the liquid ammonia to flow evenly into the interior of the kettle body 202, and makes the liquid ammonia inside the kettle body 202 more evenly distributed, avoiding stress concentration, thereby improving the measurement accuracy of the test piece; after the liquid ammonia inside the kettle body 202 is stirred evenly, the transmission component 102 stops working, and then the two first wires in the wire hole 3 are connected to the ammeter 10, and the high-pressure autoclave 2 is cooled through the low-temperature refrigerator body 103, so that the liquid ammonia temperature inside the kettle body 202 can be reduced to the set temperature, and then the timing can be started to start measuring the stress corrosion crack growth rate of the test piece in the liquid ammonia environment.

[0112] Example 2

[0113] Please refer to Figures 1 to 7 and Fig.12A method for measuring the stress corrosion crack growth rate in a liquid ammonia environment is implemented based on the device for measuring the stress corrosion crack growth rate in a liquid ammonia environment as described in Example 1, comprising the following steps:

[0114] Step S1, processing the material to be tested into a test piece, and prefabricating cracks on the test piece on a fatigue testing machine;

[0115] Step S2: Load the specimen to the set K Ii value;

[0116] Step S3, affixing an epoxy resin conductive adhesive strip to the crack tip of the specimen, and affixing an epoxy resin conductive adhesive strip at a set distance along the crack propagation direction;

[0117] Step S4: Load K Ii The test piece is placed on the clamping member 209 in the autoclave 2, one end of the two second wires is connected to the two ends of the epoxy resin conductive tape at the crack tip, and the other ends of the two second wires are connected to the bottom ends of the two first wires; the top ends of the two first wires are connected to the ammeter 10;

[0118] Step S5, lower the clamping member 209 to the inner bottom of the kettle body 202, and then introduce nitrogen into the kettle body 202 to replace the air in the kettle body 202; then introduce liquid ammonia into the kettle body 202 to replace the nitrogen in the kettle body 202, so that the oxygen content in the kettle body 202 is less than a set value; cover the kettle body 202 with the kettle cover 203, pressurize the kettle body 202 to the set pressure value, so that the ammonia in the kettle body 202 is liquefied, and the test piece is placed in the liquid ammonia;

[0119] Step S6, placing the autoclave 2 at the inner bottom end of the low-temperature refrigerator body 103 of the cooling mechanism 1, and connecting the stirring blade 207 to the transmission member 102; driving the stirring blade 207 to rotate at the inner bottom end of the autoclave body 202 through the transmission member 102 to stir the liquid ammonia in the autoclave body 202; then the transmission member 102 stops working, and the liquid ammonia in the autoclave body 202 is cooled to the set temperature through the low-temperature refrigerator body 103, and then the crack extension time of the test piece is started to be timed;

[0120] Step S7, observing the reading of the ammeter 10. When the reading of the ammeter 10 is zero, it indicates that the epoxy resin conductive adhesive strip is broken and the crack has extended to the location of the epoxy resin conductive adhesive. At this time, the kettle cover 203 is opened, the clamping member 209 is raised and moved to the top of the kettle body 202, and the test piece is taken out. The cracks on the surface of the test piece are observed through a reading microscope, the crack extension length and crack extension time are recorded, and the crack extension rate is calculated.

[0121] Step S8, reconnecting one end of the two second wires to the two ends of the next epoxy resin conductive tape in the crack extension direction, and repeating steps S5 to S8 until the crack extension rate is lower than the set value.

[0122] In a specific application, in step S1, the length of the prefabricated crack is controlled until the size of the side that crosses the incision is a set percentage of the thickness of the specimen or a set thickness, whichever is greater; the set percentage of the thickness of the specimen is 2.5% of the thickness of the specimen;

[0123] In step S3, the diameter of the epoxy resin conductive tape is 0.5 mm, and the set distance is set to 2 mm;

[0124] In step S5, the oxygen content in the kettle 202 is less than 1 mg / L;

[0125] After step S8, steps S9 and S10 are performed:

[0126] Step S9: Load the specimen with different K Ii value, and repeat steps S2 to S8;

[0127] Step S10: Obtain the stress intensity factor K corresponding to when the crack growth rate drops to a set value I , is the threshold value K of stress corrosion crack extension of the material in low temperature liquid ammonia environment Iscc .

[0128] Among them, K Ii is the initial stress intensity factor, K Iscc It is the critical stress intensity factor for the specimen to crack.

[0129] Please refer to Figures 1 to 12 , wherein, in step S1, the material to be tested is processed into a test piece, and the test piece is pre-cracked on a fatigue testing machine;

[0130] When processing the specimen, the material to be tested is processed into a standard T-WOL specimen according to the dimensions specified in GBT15970. T-WOL means T-wedge loading, which is a geometric shape of a prefabricated crack specimen.

[0131] In step S2, the T-WOL specimen is loaded to a predetermined K according to GBT15970. Ii Value, record load K Ii The corresponding initial crack length a 0.

[0132] In step S5, the liquid ammonia tail gas is absorbed by dilute hydrochloric acid, and the residual volatile gas is recovered by the waste liquid recovery tank 9.

[0133] In step S6, the socket 206 at the bottom end of the outer insulation layer 201 is plugged into the top end of the slot seat 1025, so that the clamping rod 1026 is engaged with the bottom end of the stirring blade 207, thereby driving the stirring blade 207 to slowly rotate at the bottom end of the inner part of the kettle body 202 through the transmission component 102, so as to stir the liquid ammonia inside the autoclave 2 and make the liquid ammonia evenly distributed.

[0134] In step S7, when the reading of the ammeter 10 is zero, the cover member 204 is opened, the test piece is lifted to the bottom end of the material taking port 2041 by the support member 208, and the test piece is taken out; crack growth rate = crack growth length ÷ crack growth time.

[0135] In step S8, one end of the two second wires are respectively reconnected to the two ends of the next epoxy resin conductive strip in the crack propagation direction, and the specimen is re-fixed to the inner side of the top end of the clamping member 209; the specimen is placed back into the liquid ammonia through the supporting member 208, and the sealing cover 2042 in the sealing member 204 is re-locked; the autoclave 2 is re-pressurized to the set pressure, and after the internal temperature of the autoclave body 202 is adjusted to the low temperature required for the experiment, the timing is started again and the reading of the ammeter 10 is observed; when the reading of the ammeter 10 is zero again, the specimen is taken out and observed again, and this step is repeated until the crack propagation rate is lower than the preset value.

[0136] In step S9, different K Ii The specimens with different stress intensity factors have different crack extension lengths.

[0137] In step S10, after the crack propagates, the crack tip intensity factor decreases and the crack propagation rate decreases.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for measuring the growth rate of stress corrosion cracks in a liquid ammonia environment, characterized in that: include: A cooling mechanism (1) comprises a base (101), a transmission component (102) and a low-temperature refrigerator body (103) which are arranged in sequence; A high pressure autoclave (2), comprising a autoclave body (202); the autoclave body (202) is arranged in the low temperature freezer body (103), and a autoclave cover (203) is arranged on the top of the autoclave body (202); the autoclave cover (203) is provided with a wire hole (3), an air inlet (4) and an air outlet (6), the air inlet (4) is used to inject ammonia gas, and the air outlet (6) is used to discharge overflow ammonia gas; an ammeter (10) is installed in the autoclave cover (203), and two first wires are arranged in the wire hole (3); the top ends of the two first wires are connected to the ammeter (10), and the bottom ends of the two first wires are extended into the autoclave body (202) for connecting to a test piece; a pressure gauge (5) is installed in the autoclave cover (203) for measuring the pressure in the autoclave (2); A clamping member (209), which is arranged in a lifting manner in the kettle body (202) and is used to clamp the test piece; a stirring blade (207) rotatably disposed at the bottom of the kettle body (202); the stirring blade (207) is connected to the transmission component (102), and the transmission component (102) is used to drive the stirring blade (207) to rotate; A support member (208) is disposed above the stirring blade (207), and the clamping member (209) is disposed on the support member (208); The supporting member (208) comprises a second motor (2081) and a screw rod (2082); the second motor (2081) is mounted on the kettle cover (203); the screw rod (2082) is rotatably connected to the second motor (2081) and is screwed into a threaded tube (2084); the threaded tube (2084) is connected to an annular frame (2085); a foot (2087) is provided at the bottom of the annular frame (2085); and the clamping member (209) is provided on the annular frame (2085); The annular frame (2085) is connected to a sleeve (2086), and the sleeve (2086) is movably sleeved on the outside of the polished rod (2083); the top end of the polished rod (2083) is connected to the kettle cover (203); The sleeve (2086) and the polished rod (2083) are arranged in pairs and symmetrically on both sides of the lead screw (2082); A leveling member is provided between the support member (208) and the clamping member (209), and the leveling member comprises a bracket (2088), a convex block (2089), a top block (20810), a top plate (20811) and a first telescopic rod (20813); the bracket (2088) is connected to the annular frame (2085), the convex block (2089) is connected to the bracket (2088), and a ball head is provided at the top end of the convex block (2089); a hemispherical slot is provided on the bottom surface of the top block (20810) , the ball head is rotatably arranged in the hemispherical slot; the top plate (20811) is connected to the top block (20810); the top and bottom ends of the first telescopic rod (20813) are rotatably connected to the first adapter (20812) and the second adapter (20814) respectively, and the first adapter (20812) and the second adapter (20814) are respectively connected to the top plate (20811) and the annular frame (2085); the clamping member (209) is connected to the top plate (20811); The first telescopic rods (20813) are arranged in four numbers and are evenly arranged along the axial direction; The clamping member (209) comprises a slot plate (2091), a cavity being arranged inside the slot plate (2091); the bottom surface of the slot plate (2091) is connected to the top plate (20811); The groove plate (2091) is internally provided with a toothed disc (2092) for rotation and is movably provided with a first support plate (2093) and a second support plate (2094); the first support plate (2093) and the second support plate (2094) are arranged on both sides of the toothed disc (2092) and are both provided with tooth grooves, and the tooth grooves are both meshed with the toothed disc (2092); Two opposite side walls of the slot plate (2091) are respectively provided with through holes, and ends of the first support plate (2093) and the second support plate (2094) respectively extend from the two through holes to two sides of the outside of the slot plate (2091); The first support plate (2093) and the second support plate (2094) are both connected to a clamping plate (2095), and the two clamping plates (2095) are respectively arranged on two sides of the outside of the slot plate (2091) and are used to clamp the test piece placed on the slot plate (2091); A second telescopic rod (2096) is connected between the first support plate (2093) and the second support plate (2094) and two opposite side walls of the slot plate (2091); The kettle body (202) is connected to a flow guide barrel (205), and at least two flow diversion grids are evenly distributed on the inner wall of the flow diversion barrel (205), and the flow diversion grids are all in a semi-spiral shape.

2. The device for measuring the stress corrosion crack growth rate in a liquid ammonia environment according to claim 1, characterized in that: The air inlet (4) is connected to an ammonia tank (7), and the air outlet (6) is connected to an exhaust gas recovery tank (8); the exhaust gas recovery tank (8) is connected to a waste liquid recovery tank (9); The kettle cover (203) is provided with a sealing component (204), and the sealing component (204) is used for storing and accessing the test piece; The sealing component (204) comprises a material taking port (2041) and a sealing cover (2042); the material taking port (2041) is provided on the kettle cover (203); one side edge of the sealing cover (2042) is rotatably connected to one side edge of the material taking port (2041); the other side edges of the sealing cover (2042) are connected to the other side edges of the material taking port (2041) via fastening bolts (2044); the sealing cover (2042) is used to open and seal the material taking port (2041); and a handle (2043) is connected to the sealing cover (2042).

3. The device for measuring stress corrosion crack growth rate in liquid ammonia environment according to claim 1, characterized in that: The transmission component (102) comprises a housing (1021), a first motor (1022), a small gear (1023), a large gear (1024), a slot seat (1025), and a clamping rod (1026); The housing (1021) is mounted on the base (101), the first motor (1022) is mounted on the housing (1021), and the pinion gear (1023) and the large gear (1024) are both rotatably disposed in the housing (1021); the pinion gear (1023) is connected to the first motor (1022) and meshes with the large gear (1024); the center position of the top of the large gear (1024) is connected to the clamping rod (1026), and the slot seat (1025) is disposed on the top surface of the housing (1021) and is fixedly connected to the inner bottom end of the low-temperature refrigerator body (103); The autoclave (2) comprises an outer thermal insulation layer (201), wherein the outer thermal insulation layer (201) is sleeved on the outside of the autoclave body (202); a socket (206) is provided at the bottom end of the outer thermal insulation layer (201), and the socket (206) is plugged into the slot seat (1025); The slot seat (1025) and the socket (206) are provided with a latch rod hole, the latch rod (1026) is rotatably disposed in the latch rod hole, and the top end of the latch rod (1026) is latched and connected to the inside of the bottom end of the stirring blade (207).

4. The device for measuring stress corrosion crack growth rate in liquid ammonia environment according to claim 1, characterized in that: The first telescopic rod (20813) comprises a first slot tube, a first spring and a first insertion rod, the first spring being arranged at the inner bottom end of the first slot tube, the first insertion rod being movably arranged at the inner top end of the first slot tube, the bottom end and the top end of the first spring being respectively connected to the bottom end of the first slot tube and the bottom end of the first insertion rod; the top end of the first insertion rod is rotatably connected to the first adapter (20812), and the bottom end of the first slot tube is rotatably connected to the second adapter (20814); The second telescopic rod (2096) comprises a second slot tube, a second spring and a second insertion rod; the first support plate (2093) and the second support plate (2094) are respectively connected to one end of the second slot tube; the two opposite side walls of the slot plate (2091) are respectively connected to one end of the second insertion rod, and the other end of the second insertion rod is movably arranged in the other end of the second slot tube; the second spring is sleeved on the outside of the second slot tube and the second insertion rod.

5. A method for measuring the stress corrosion crack growth rate in a liquid ammonia environment, characterized in that: The method is implemented based on the measuring device according to any one of claims 1 to 4, comprising the following steps: Step S1, processing the material to be tested into a test piece, and prefabricating cracks on the test piece on a fatigue testing machine; Step S2: Load the specimen to the set K Ii value; Step S3, pasting an epoxy resin conductive adhesive strip on the crack tip of the test piece, and pasting an epoxy resin conductive adhesive strip at a set distance along the crack extension direction; Step S4: Load K Ii The test piece is placed on the clamping member (209) in the autoclave (2), one end of two second wires are respectively connected to the two ends of the epoxy resin conductive tape at the crack tip, and the other ends of the two second wires are respectively connected to the bottom ends of the two first wires; the top ends of the two first wires are connected to the ammeter (10); Step S5, lowering the clamping member (209) to the inner bottom end of the kettle body (202), then introducing nitrogen into the kettle body (202) to replace the air in the kettle body (202); then introducing liquid ammonia into the kettle body (202) to replace the nitrogen in the kettle body (202), so that the oxygen content in the kettle body (202) is less than a set value; placing the kettle cover (203) on the kettle body (202), pressurizing the kettle body (202) to a set pressure value, so that the ammonia in the kettle body (202) is liquefied, and the test piece is placed in the liquid ammonia; Step S6, placing the autoclave (2) at the bottom end of the low-temperature refrigerator body (103) of the cooling mechanism (1), and connecting the stirring blade (207) to the transmission component (102); driving the stirring blade (207) to rotate at the bottom end of the autoclave body (202) through the transmission component (102) to stir the liquid ammonia in the autoclave body (202); then the transmission component (102) stops working, and the liquid ammonia in the autoclave body (202) is cooled to a set temperature through the low-temperature refrigerator body (103), and then starting to count the crack extension time of the test piece; Step S7, observing the reading of the ammeter (10); when the reading of the ammeter (10) is zero, it indicates that the epoxy resin conductive adhesive strip is broken, and the crack has extended to the location of the epoxy resin conductive adhesive; at this time, the kettle cover (203) is opened, the clamping member (209) is raised and moved to the top of the kettle body (202), and the test piece is taken out; the cracks on the surface of the test piece are observed through a reading microscope, the crack extension length and crack extension time are recorded, and the crack extension rate is calculated; Step S8, reconnecting one end of the two second conductive wires to the two ends of the next epoxy resin conductive tape in the crack extension direction, and repeating steps S5 to S8 until the crack extension rate is lower than the set value.

6. The method for measuring the stress corrosion crack growth rate in a liquid ammonia environment according to claim 5, characterized in that: In step S1, the length of the prefabricated crack is controlled until the dimension of the side that crosses the incision is a set percentage of the thickness of the specimen or a set thickness, whichever is greater; the set percentage of the thickness of the specimen is 2.5% of the thickness of the specimen; In step S3, the diameter of the epoxy resin conductive tape is 0.5 mm, and the set distance is set to 2 mm; In step S5, the oxygen content in the kettle (202) is less than 1 mg / L; After step S8, steps S9 and S10 are performed: Step S9: Load the specimen with different K Ii value, and repeat steps S2 to S8; Step S10: Obtain the stress intensity factor K corresponding to when the crack growth rate drops to a set value I , is the threshold value K of stress corrosion crack extension of the material in low temperature liquid ammonia environment Iscc .

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