WO2020192040A1

WO2020192040A1 - Fracture toughness testing device under low-temperature and high-pressure hydrogen charged environment and method thereof

Info

Publication number: WO2020192040A1
Application number: PCT/CN2019/106291
Authority: WO
Inventors: 黄舒; 赵家曦; 周建忠; 马冬辉; 李红宇; 胡磊; 单铭远
Original assignee: 江苏大学
Priority date: 2019-03-22
Filing date: 2019-09-18
Publication date: 2020-10-01
Also published as: CN110018060A

Abstract

Provided is a fracture toughness testing device under low-temperature and high-pressure hydrogen charged environment, comprising a sealed box body and a tensile device, the tensile device is provided on the sealed box body, further comprising a refrigeration assembly, a liquid pressurization assembly, an electrochemical assembly, a detection assembly and an industrial personal computer (32); the liquid pressurization assembly is used for supplying the high pressure electrolyte solution to the interior of the sealed box body; the refrigeration assembly is used for cooling the electrolyte solution; the electrochemical assembly is used for generating hydrogen on the surface of a tensile test sample (21); the detection assembly is used for detecting the pressure and temperature in the sealed box body, and the opening crack state of the tensile test sample (21); the industrial personal computer (32) controls the refrigeration assembly, the liquid pressurization assembly, the electrochemical assembly and the tensile device through collecting and analyzing the information of the detection assembly. The testing device is used for testing the fracture toughness under low-temperature, high-pressure and hydrogen rich environment, a low-temperature, high-pressure and hydrogen rich deep sea environment is effectively simulated, and the reliability of final testing data is improved.

Description

Device and method for testing fracture toughness under low temperature and high pressure hydrogen charging environment

Technical field

The invention relates to the technical field of material mechanics test devices, in particular to a fracture toughness test device and a method under a low-temperature high-pressure hydrogen charging environment.

Background technique

Titanium alloys are widely used in ships and marine engineering due to their good corrosion resistance, weldability and high specific strength. After decades of development, the research and application level of China's marine titanium alloys has been greatly improved, and a relatively complete marine titanium alloy system has been formed, which can meet the requirements of different strength levels for ships, submarines and deep submersibles, and It can be applied to different service positions. However, if titanium alloy components are used in low-temperature and high-pressure hydrogen-containing media for a long time, the erosion of seawater and the cavitation erosion of high-velocity seawater will accelerate the penetration of hydrogen atoms on the surface of the material, which has an impact on material strength, especially fracture toughness. Studies have shown that when titanium alloy components are serviced in a high-pressure hydrogen environment, hydrogen atoms are easily penetrated from the surface of the titanium alloy, thereby forming hydrogen pressure and brittle hydrides, which eventually lead to premature cracking and fracture failure during the service period , Causing major safety accidents. The above problems have largely restricted the application of titanium alloys in deep-sea marine equipment such as submarines and deep-sea vehicles. Therefore, the fracture toughness of titanium alloys under low temperature and high pressure electrochemical hydrogen charging environment is studied, and on this basis, a process to improve the fracture toughness of titanium alloys in extreme service environments is to be found to slow down the fracture toughness of titanium alloys in low temperature, high pressure and deep sea environments. Hydrogen-induced crack initiation and growth rate have very important engineering practical significance.

The Chinese patent proposes a test device for the fracture toughness of materials under normal pressure and high temperature electrochemical hydrogen charging environment, but it does not involve the low temperature and high pressure test environment. In addition, the patent uses a circular heating element on the outer ring of the circular table to provide a water bath heating and heat preservation environment, but the heat exchange medium must first transfer heat to the cylinder wall before it can transfer heat to the gas in the environmental box. For high-pressure gas, the wall of the cylinder is often thick, resulting in that the insulation medium in the jacket cannot effectively heat the gas in the cylinder. The overall thermal efficiency of the structure is low, and the jacket will also dissipate heat along the outer wall, resulting in waste of heat . For another example, the Chinese patent relates to a material fatigue performance test method in a high-pressure hydrogen environment, testing the fatigue performance of the material, but the hydrogen environment in the article is a gaseous hydrogen environment rather than an electrochemical hydrogen charging environment (liquid hydrogen environment).

The fracture toughness of metal is an important index to evaluate the ability of metal materials to resist brittle fracture, and it has been widely used in production. The material safety requirements of titanium alloy key structural parts in the deep sea service environment are high, so the fracture toughness test is indispensable, which is of great significance to ensure the service safety of key structural parts.

Summary of the invention

In view of the shortcomings in the prior art, the present invention provides a fracture toughness test device and method in a low-temperature, high-pressure hydrogen-charged environment, which is used to test the fracture toughness of materials in a low-temperature, high-pressure, hydrogen-rich environment, and provides real-time The electrochemical hydrogen charging environment has formed a relatively complete test program, which can truly and effectively simulate the deep-sea environment of low temperature and high pressure hydrogen-rich, and improve the reliability of the final test data, thus providing the key structural parts of titanium alloy in deep-sea ship engineering at low temperature and high pressure. The application in hydrogen-rich environment provides theoretical and experimental basis.

The present invention achieves the above technical objectives through the following technical means.

A device for testing fracture toughness in a low-temperature and high-pressure hydrogen charging environment includes a closed box body and a stretching device. The closed box body is provided with a stretching device, and also includes a refrigeration component, a liquid pressurizing component, an electrochemical component, and a testing device. Components and industrial computers; the liquid pressurization component is used to provide high-pressure electrolyte solution inside the closed box; the refrigeration component is used to cool the electrolyte solution; the electrochemical component is used to produce Hydrogen; the detection component is used to detect the pressure, temperature and the opening crack state of the tensile specimen in the enclosed box; the industrial computer controls the refrigeration component, the liquid pressurization component, and the electrical component by collecting and analyzing the information of the detection component Chemical components and stretching equipment.

Further, the refrigeration assembly includes a refrigeration elbow and a refrigerator, the refrigeration elbow is placed in a closed box, and the refrigerator is connected to the refrigeration elbow for cooling the electrolyte solution in the closed box.

Further, the liquid pressurizing assembly includes a hydraulic pump, an overflow valve, and a second throttle valve; the hydraulic pump communicates with the closed box body through the overflow valve and the second throttle valve in sequence, and is used to provide The body provides a high-pressure electrolyte solution.

Further, the electrochemical assembly includes an electrochemical workstation and an auxiliary electrode, one end of the electrochemical workstation is connected with the tensile sample, the other end of the electrochemical workstation is connected with the auxiliary electrode, and the auxiliary electrode is inserted into the electrolyte solution.

Further, the detection component includes a pressure sensor, a temperature sensor, a displacement sensor, and a holographic microscope. The pressure sensor is used to measure the pressure inside the enclosed box; the temperature sensor is used to measure the temperature inside the enclosed box; the displacement The sensor is used to measure the opening displacement of the tensile specimen; the holographic microscope is used to observe and photograph the image of the crack propagation change of the tensile specimen; the industrial computer is used to collect and analyze the pressure sensor, temperature sensor, displacement sensor and holographic microscope Information.

Further, it also includes a liquid pressure relief component, which is used to recover the high-pressure electrolyte solution in the closed box.

A method for testing fracture toughness under low temperature and high pressure hydrogen charging environment, including the following steps:

Providing a high-pressure electrolyte solution to the inside of the enclosed box through the liquid pressurizing assembly;

Cooling the high-pressure electrolyte solution inside the enclosed box by a refrigeration component;

Hydrogen is generated on the surface of the tensile sample through electrochemical components;

When the measured value of the detection component reaches the set value range, the industrial computer controls the tensile device to perform a fracture toughness test on the tensile specimen;

During the test, the industrial computer collects the opening displacement of the tensile specimen and the image of the crack propagation change of the tensile specimen through the detection component; the industrial computer obtains the fracture toughness K of the tensile specimen.

Further, the temperature range of the refrigeration component is 10°C to -5°C; the electrolyte solution is a sulfuric acid solution.

The beneficial effects of the present invention are:

1. The device and method for testing fracture toughness in a low-temperature and high-pressure hydrogen charging environment of the present invention uses a closed box to provide a safe and reliable low-temperature and high-pressure electrochemical hydrogen charging environment, and can simultaneously complete compact tensile tests in a hydrogen charging environment This kind of tensile test experiment operation avoids the error influence caused by the experimental gap between the separate operations of the hydrogen charging experiment and the tensile test experiment, and improves the overall experimental operation. At the same time, by setting pressure sensors and temperature sensors, a safe and stable hydrogen charging environment can be realized, and the parameters of the hydrogen charging environment can be adjusted as needed, thereby increasing the authenticity and reliability of the experimental data.

2. The device and method for testing fracture toughness under low temperature and high pressure hydrogen charging environment of the present invention adopts liquid pressurizing components and liquid pressure relief components, and hydraulic components are used to achieve pressurization of electrochemical hydrogen charging solution and after the experiment is completed The pressure relief of high-pressure solution is safe and convenient.

3. The device and method for testing fracture toughness in a low-temperature and high-pressure hydrogen charging environment of the present invention adopts an electrochemical hydrogen charging method to provide a liquid hydrogen-rich environment, by setting refrigeration elbows throughout the entire closed box, and The liquid inlet and outlet pipes on the top cover of the box body are used to transfer the refrigerating medium generated by the refrigerator to the inside of the environmental box for cooling, so as to realize the required low-temperature test environment. The refrigerating medium circulates directly inside the environmental box, reducing The refrigeration link improves the refrigeration efficiency.

4. The device and method for testing fracture toughness under low temperature and high pressure hydrogen charging environment of the present invention uses a holographic microscope with a built-in 3D holographic imaging sensor, which can withstand 100 MPa water pressure. The crack growth of the tensile specimen can be photographed in real time, and the crack growth can be understood from multiple angles. The microscope does not require a time-consuming and laborious calibration process, does not need to be preheated, and can start counting within a few seconds when placed in water.

5. The present invention applies ZM99-01A15 transparent cold insulation coating on the side wall of the closed box, which is convenient and easy to implement, low cost, water is used as a dispersant, no pollution to the environment, can be painted on glass, and has excellent heat preservation effect. Effectively isolate the influence of external ambient temperature on the enclosed box.

Description of the drawings

Fig. 1 is a schematic diagram of the fracture toughness testing device under the low temperature and high pressure hydrogen charging environment of the present invention.

Fig. 2 is an enlarged view of the installation method of the displacement sensor and the tensile specimen according to the present invention.

In the picture:

1- solution tank; 2- pressure reducing valve; 3- first throttle valve; 4- first one-way valve; 5- electromagnetic reversing valve; 6- hydraulic pump; 7- second throttle valve; 8-th Two one-way valves; 9-positioning screw; 10-upper cover; 11-upper sealing O-ring; 12-side wall; 13-refrigeration elbow; 14-displacement sensor; 15-lower sealing O-ring; 16- Lower top cover; 17- lower connecting piece; 18- lower pressing ring; 19- lower compact tensile specimen connecting piece; 20-holographic microscope; 21- tensile specimen; 22- upper compact tensile specimen connecting piece; 23-Upper pressure ring; 24-Upper connector; 25-Overflow valve; 26-Auxiliary electrode; 27-Pressure sensor; 28-Temperature sensor; 29-Inlet pipe; 30-Outlet pipe; 31-Refrigerator; 32-Working condition machine.

detailed description

The present invention will be further described below in conjunction with the drawings and specific embodiments, but the protection scope of the present invention is not limited to this.

As shown in Figure 1 and Figure 2, the fracture toughness test device under low temperature and high pressure hydrogen charging environment of the present invention includes a closed box, a stretching device, a refrigeration component, a liquid pressurizing component, an electrochemical component, a detection component and Industrial computer 32; the closed box is provided with a stretching device, the liquid pressurizing component is used to provide high-pressure electrolyte solution inside the closed box; the refrigeration component is used to cool the electrolyte solution; the electric The chemical component is used to generate hydrogen on the surface of the tensile sample 21; the detection component is used to detect the pressure and temperature in the closed box and the opening crack state of the tensile sample 21; the industrial computer 32 collects and analyzes the detection component Information to control the refrigeration components, liquid pressurization components, electrochemical components and stretching devices.

The closed box includes an upper cover 10, a side wall 12, and a lower cover 16. The refrigeration component, the holographic microscope 20, the connecting component and the displacement sensor 14 are placed in the closed box, and the industrial computer 32 controls the above components. A side wall 12 is arranged between the upper top cover 10 and the lower top cover 16, and the three together form a closed space. The side wall 12 is connected to the upper top cover 10 by a positioning screw 9, and the side wall 12 is connected to the lower top cover 16 by a positioning screw 9; an upper sealing O-ring 11 is placed between the upper top cover 10 and the upper end of the side wall 12, and the lower top A lower sealing O-ring 15 is placed between the cover 16 and the lower end of the side wall 12 to block the leakage gap to achieve the purpose of sealing. The upper top cover 10 and the lower top cover 16 are respectively provided with round holes for extending the connection components.

The refrigeration assembly includes a refrigeration elbow 13, a liquid inlet pipe 29, a liquid outlet pipe 30, and a refrigerator 31. The refrigeration elbow 13 is placed in a closed box, and the inlet pipe 29 is connected to the bottom of the refrigeration elbow. The liquid pipe 30 is connected to the top of the refrigeration elbow, and the refrigerator 31 is connected to the liquid inlet pipe 29 and the liquid outlet pipe 30 for cooling the electrolyte solution in the enclosed box.

The liquid booster assembly includes a solution tank 1, a hydraulic pump 6, an overflow valve 25, a second throttle valve 7 and a second one-way valve 8. The solution tank 1 is connected to the hydraulic pump 6, the second throttle valve 7 and The second check valve 8, the overflow valve 25 is connected in parallel with the closed system, and the required system pressure is set to the set pressure of the overflow valve 25. The function of the overflow valve 25 is to maintain the system pressure during the continuous overflow process. Basically unchanged. The pressurizing component is connected with the top cover of the closed box body and is used to provide a high-pressure electrochemical hydrogen charging solution for the closed box body. The liquid pressure relief component includes an electromagnetic reversing valve 5, a first one-way valve 4, a first throttle valve 3, a pressure reducing valve 2 and a solution tank 1. The solution tank 1 is connected to the pressure reducing valve 2 and the first throttle valve 3 in turn , The first one-way valve 4, the electromagnetic reversing valve 5. The electromagnetic reversing valve 5 is in a normally closed state during the test, and is in a normally open state after the test. The pressure relief component is connected to the lower top cover 16 of the closed box body, and is used to relieve the pressure of the high-pressure electrochemical hydrogen charging solution of the closed box body after the test is completed.

The electrochemical assembly includes an electrochemical workstation and an auxiliary electrode 26, one end of the electrochemical workstation is connected to the tensile sample 21, the other end of the electrochemical workstation is connected to an auxiliary electrode 26, and the auxiliary electrode 26 is inserted into the electrolyte solution .

The detection component includes a pressure sensor 27, a temperature sensor 28, a displacement sensor 14 and a holographic microscope 20. The pressure sensor 27 is used to measure the pressure inside the enclosed box; the temperature sensor 28 is used to measure the temperature inside the enclosed box. The displacement sensor 14 is used to measure the opening displacement of the tensile specimen 21; the holographic microscope 20 is used to observe and photograph the image of the crack propagation change of the tensile specimen 21; the industrial computer 32 is used to collect and analyze the pressure sensor 27. Information of temperature sensor 28, displacement sensor 14 and holographic microscope 20.

An upper connecting piece 24, an upper compact tensile specimen connecting piece 22, a tensile specimen 21, a lower connecting piece 17, a lower compact tensile specimen connecting piece 19 and a holographic microscope 20 are installed in the enclosed box; The lower end of the extension specimen connector 22 is provided with a circular hole, which is connected to the upper circular hole of the compact tensile specimen 21 through a round pin. The upper end of the upper compact tensile specimen connector 22 is provided with a threaded hole, which is connected with the upper end through a thread The lower end of the connecting piece 24 is connected, and the upper end of the upper connecting piece 24 is connected to the tensile machine; the upper end of the lower compact tensile specimen connecting piece 19 is provided with a round hole, which is connected to the lower round hole of the tensile specimen 21 through a round pin, The lower end of the lower compact tensile specimen connector 19 is provided with a threaded hole, which is connected to the upper end of the lower connector 17 through a threaded connection, and the lower end of the lower connector 17 is connected to the stretching machine. A round boss is provided on the upper connecting piece 24, an upper pressing ring 23 is placed between the round boss and the upper top cover 10, and a round boss is arranged on the lower connecting piece 17, which is placed between the round boss and the lower top cover 16. The lower pressing ring 18 is used to ensure the displacement and deformation of the sample during the stretching process.

The method for testing fracture toughness under low temperature and high pressure hydrogen charging environment of the present invention includes the following steps:

First, a pair of precision knife holes are processed on the tensile specimen 21 for precise installation of the displacement sensor. The surface is then polished and polished, and cleaned by ultrasonic in alcohol for later use. The tensile specimen 21 is 75mm long, 72mm wide, and 30mm thick. The diameter of the upper and lower round holes is 15mm, the crack length is 40mm, and the crack tip opening angle is 60°.

Prepare 0.5mol/L H ₂ SO ₄ solution as an electrolyte solution, and add 1.25 g/L Na ₄ P ₂ O ₇ *10H ₂ O to the solution as a poisoning agent to promote more absorbable hydrogen atoms to diffuse into the metal base in vivo.

The lower top cover 16 of the closed box is connected to the side wall 12 through the positioning screw 9 and the refrigeration elbow is put in at the same time. Subsequently, the lower end of the upper compact tensile specimen connector 22 is connected to the upper circular hole of the tensile specimen 21 through a round pin, and the upper end of the upper compact tensile specimen connector 22 is connected to the lower end of the upper connector 24 through a threaded connection , The upper end of the upper connecting piece 24 is connected to the tensile machine; the upper end of the lower compact tensile specimen connecting piece 19 is connected to the lower round hole of the tensile specimen 21 through a round pin, and the lower end of the lower compact tensile specimen connecting piece 22 It is connected to the upper end of the lower connecting piece 17 through a threaded connection, and the lower end of the lower connecting piece 17 is connected to the stretching machine. The top cover 10 of the closed box is connected with the side wall 12 through the positioning screw 9 to realize the sealing of the entire device. Among them, a pressure sensor 27, a temperature sensor 28, a displacement sensor 14 and an auxiliary electrode 26 are installed on the top cover 10 of the closed box.

Connect refrigeration components, high-pressure liquid booster components, high-pressure liquid pressure relief components and electrochemical workstations.

The closed box is filled with high-pressure liquid through the liquid pressurizing component; the industrial computer 32 controls the hydraulic pump 6, the overflow valve 25, the second throttle valve 7, the overflow valve 25 and the second one-way valve 8 to reduce the required system pressure Set as the set pressure of the overflow valve 25, the function of the overflow valve 25 is to keep the system pressure basically unchanged during the continuous overflow process. While filling the high-pressure liquid, observe the indication of the pressure sensor 27. When the pressure is close to the test pressure, adjust the second throttle valve 7 to control the flow of the high-pressure liquid into the closed cavity until the test pressure is reached.

The high-pressure electrochemical hydrogen charging solution in the closed box is refrigerated by the refrigerating component; the industrial computer 32 controls the refrigerating machine 31. Observe the value of the temperature sensor 28 until the temperature of the closed box meets the test requirements.

The industrial computer 32 starts the electrochemical workstation to perform an electrochemical hydrogen charging test operation on the tensile sample 21, the auxiliary electrode 26 is connected to the negative electrode of the electrochemical workstation, and the tensile sample 21 is connected to the positive electrode of the electrochemical workstation. Hydrogen is electrolyzed from the surface of the tensile sample 21, and the hydrogen enters the target material sample through permeation and diffusion. When the predetermined hydrogen charging time is reached, the tensile machine is started, and the fracture toughness test is performed on the target material sample. Record the test data of the displacement sensor in the test until the target material sample is completely broken and stop the test. The load-opening displacement curve obtained in the test is processed according to the GB4161-84 standard to obtain the fracture toughness K of the compact tensile sample, and Combined with the dynamic image of fatigue crack growth taken online by the CCD image acquisition system to understand the dynamic process of specimen fracture.

Pour the high-pressure electrochemical hydrogen charging solution: the pressure relief component is connected to the lower top cover 16 of the closed box, and after the test is over, the high-pressure electrochemical hydrogen charging solution of the closed box is released.

The side wall of the closed box is painted with ZM99-01A15 transparent cold-preservation layer paint for heat preservation of the electrochemical hydrogen charging solution in the closed box, and the temperature range of the refrigeration component is 10°C to -5°C. The electrochemical hydrogen charging time is 72 hours, the current density used is 50 mA/cm ² , and the pressure value of the closed box is in the range of 35-50 MPa.

The embodiments are the preferred embodiments of the present invention, but the present invention is not limited to the above-mentioned embodiments. Without departing from the essence of the present invention, any obvious improvements, substitutions, or substitutions can be made by those skilled in the art. All variants belong to the protection scope of the present invention.

Claims

A device for testing fracture toughness under a low-temperature and high-pressure hydrogen charging environment, comprising a closed box body and a stretching device, the closed box body is provided with a stretching device, and is characterized in that it also includes a refrigeration component, a liquid pressurizing component, an electric Chemical components, detection components, and industrial computers (32); the liquid pressurizing components are used to provide high-pressure electrolyte solution inside the closed box; the refrigeration components are used to cool the electrolyte solution; the electrochemical components are used Hydrogen is generated on the surface of the tensile sample (21); the detection component is used to detect the pressure and temperature in the closed box and the open crack state of the tensile sample (21); the industrial computer (32) collects and analyzes the detection The component information controls the refrigeration component, the liquid pressurizing component, the electrochemical component and the stretching device.
The fracture toughness test device in a low-temperature and high-pressure hydrogen charging environment according to claim 1, wherein the refrigeration assembly includes a refrigeration elbow (13) and a refrigerator (31), and the refrigeration elbow (13) is placed In the enclosed box, the refrigerator (31) is connected with the refrigeration elbow (13) for cooling the electrolyte solution in the enclosed box.
The fracture toughness test device in a low temperature and high pressure hydrogen charging environment according to claim 1, wherein the liquid pressurizing component includes a hydraulic pump (6), an overflow valve (25) and a second throttle valve (7). ); The hydraulic pump (6) is communicated with the closed box through an overflow valve (25) and a second throttle valve (7) in turn, and is used to provide a high-pressure electrolyte solution for the closed box.
The fracture toughness test device under low temperature and high pressure hydrogen charging environment according to claim 1, wherein the electrochemical component includes an electrochemical workstation and an auxiliary electrode (26), and one end of the electrochemical workstation is connected to a tensile sample (21) Connection, the other end of the electrochemical workstation is connected with the auxiliary electrode (26), and the auxiliary electrode (26) is inserted into the electrolyte solution.
The fracture toughness test device under low temperature and high pressure hydrogen charging environment according to claim 1, wherein the detection component includes a pressure sensor (27), a temperature sensor (28), a displacement sensor (14) and a holographic microscope (20). ), the pressure sensor (27) is used to measure the pressure inside the closed box; the temperature sensor (28) is used to measure the temperature inside the closed box; the displacement sensor (14) is used to measure the tensile specimen (21) the opening displacement; the holographic microscope (20) is used to observe and shoot the image of the crack propagation change of the tensile specimen (21); the industrial computer (32) is used to collect and analyze the pressure sensor (27), temperature Sensor (28), displacement sensor (14) and holographic microscope (20) information.
The device for testing fracture toughness in a low-temperature and high-pressure hydrogen charging environment according to claim 1, further comprising a liquid pressure relief component, and the liquid pressure relief component is used to recover the high-pressure electrolyte solution in the enclosed box.
A test method of a fracture toughness test device under a low temperature and high pressure hydrogen charging environment according to claim 1, characterized in that it comprises the following steps:

Providing a high-pressure electrolyte solution to the inside of the enclosed box through the liquid pressurizing assembly;

Cooling the high-pressure electrolyte solution inside the enclosed box by a refrigeration component;

Hydrogen is generated on the surface of the tensile sample (21) through electrochemical components;

When the measured value of the detection component reaches the set value range, the industrial computer (32) controls the tensile device to perform a fracture toughness test on the tensile specimen (21);

During the test, the industrial computer (32) collects the opening displacement of the tensile specimen (21) and the image of the crack propagation change of the tensile specimen (21) through the detection component; the industrial computer (32) obtains Find the fracture toughness K of the tensile specimen (21).
The method for testing fracture toughness in a low-temperature and high-pressure hydrogen charging environment according to claim 7, wherein the temperature range of the refrigeration component is 10°C to -5°C; and the electrolyte solution is a sulfuric acid solution.