JP2024037668A - Tensile test device and test piece used for quantitatively evaluating embrittlement behavior in a hydrogen gas environment - Google Patents

Abstract

The present invention provides a tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment, and a test piece used therein. [Solution] A tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment includes (1) a test piece in which a hollow is formed extending from the upper fixed end to the lower fixed end along the longitudinal direction; (2) a lower jig that seals the hollow lower opening and fixes the test piece by removably coupling with the lower fixed end; (4) an upper jig that seals the upper opening and is actuated up and down by a linearly driven actuator to pull the test piece; and (4) a supply formed through the lower jig so as to communicate with the sealed lower opening. The apparatus may further include a gas supply unit connected to the line and filling the hollow space with a predetermined gas at various variable pressures. [Selection diagram] Figure 1

Description

Application for application of Article 30, Paragraph 2 of the Patent Act 1. Academic conference (poster presentation): Korean Society of Mechanical Engineers, Materials and Destruction Division 2022 Spring Academic Conference (Date: June 22nd to June 24th, 2022, Buyong Hotel & Resort, Seogwipo, Seogwipo, Jeju Island) 2. Collection of conference abstracts: Related to the conference in 1 above (Publication date: June 22, 2022) https://sites. google. com/view/ksme2022-mnf/announcement 3. Academic conference (paper presentation): ASME 2022 Pressure Vessels & Piping Conference (held July 17-22, 2022, Las Vegas, Nevada, USA) and its website (published November 4, 2022) https://asmedigitalcollect ion ．． asme. org/PVP/proceedings-abstract/PVP2022/86182/V04BT06A031/1149904? redirectedFrom=PDF

The present invention relates to a tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment and a test piece used therein. Regarding a small-scale tensile testing device that can easily and quantitatively evaluate the embrittlement behavior of metal or non-metallic materials under the gas environment (temperature, pressure) handled, and the test pieces used therein. It is.

In order to urgently solve the serious climate problems caused by greenhouse gases and global warming, countries around the world are enacting various regulations to convert power generation systems centered on fossil energy to new and renewable energy. , proposes and implements various financial support policies.

Among renewable energies, hydrogen energy technology has been gaining momentum in recent years as it has been recognized as a meaningful technological solution to achieving carbon neutrality and a method for reducing various pollutants and particulates. , active research and development is being carried out in the automotive field.

Countries such as South Korea, the United States, Japan, and Germany, which are leaders in automobile technology, are not only researching and developing hydrogen fuel cells installed in automobiles, but also developing hydrogen filling systems and hydrogen fuel cells in order to commercialize and expand the spread of hydrogen fuel cell vehicles. We are also devoting various efforts to research and development on the entire hydrogen ecosystem, including production, storage, and transportation.

However, hydrogen produced in large quantities is a highly explosive and flammable gas, and for efficiency, it is stored and transported after high-pressure treatment, so the durability and stability of the equipment that handles hydrogen cannot be guaranteed. is treated as an important matter that must be taken into account.

Therefore, technologies related to the storage and transportation of high-pressure hydrogen require the structural stability of the storage medium, such as high-pressure containers and transportation piping, and the hydrogen embrittlement of materials used for storing and transporting high-pressure hydrogen. Interest is focused on research on evaluating mechanical properties by hydrogen embrittlement (HE).

Here, hydrogen embrittlement is a phenomenon in which hydrogen atoms, which are very small in size, penetrate and diffuse into the interior of the material under high pressure environments, greatly reducing the ductility of the material. , which will greatly reduce the original mechanical performance and cause serious damage such as premature crack initiation.

Therefore, when determining the suitability of materials to be used in a hydrogen environment, the mechanical properties due to hydrogen embrittlement must be verified and evaluated. Therefore, there is a need for test methods and test equipment that can accurately evaluate hydrogen embrittlement characteristics under a variety of usage environments.

Conventional hydrogen embrittlement evaluation tests, which are compatible with the various usage environments mentioned above, are conducted by injecting hydrogen, etc., at a set pressure into the material charged into a chamber where the temperature can be set. This was mainly done using a high-pressure holding device (autoclave).

However, in the case of testing for explosive gases such as hydrogen, the test equipment itself has to be large and complex in structure to ensure essential safety equipment, making operation and safety management of the equipment difficult, making it difficult to operate and manage safety. The problem was that it was difficult to do so.

In order to solve the above-mentioned problems and promote research and development in ordinary laboratories, the applicant of the present invention has proposed Korean Patent No. 10-1177429 (registration date: August 21, 2012). I have proposed a simple test method such as

According to the conventional simple testing method described above, it is possible to simultaneously obtain a variety of data on the embrittlement behavior of each material in a short time, and it has the advantage of being able to quickly and easily evaluate the embrittlement behavior of materials in a gas environment. be.

In addition, since a small amount of treated gas is provided at high pressure to a relatively small test piece, it is relatively safe even if some of the treated gas leaks, and with small-scale equipment and low cost, it is possible to This method has the advantage that evaluation data regarding the embrittlement behavior of materials used in a gas environment can be easily obtained based on a small-sized punch test.

However, when evaluating the embrittlement behavior of materials used in a high-pressure hydrogen environment of 35 MPa to 70 MPa, the small punch test directly confirms the effect of hydrogen embrittlement on the tensile strength of the material itself. There is a problem in that it is difficult to obtain quantitative data.

In addition, the equipment itself for the conventional simple test method has certain limitations in that it is not possible to evaluate the specific embrittlement behavior of materials that occurs in low- and high-temperature environments other than room temperature based on the tensile deformation of the material. There is a limit.

Republic of Korea Patent No. 10-1177429 (registration date: August 21, 2012)

The purpose of the present invention is to directly and quantitatively determine the influence of the embrittlement behavior of various materials such as metals, alloys, polymer resins, and ceramics on the tensile strength of the materials themselves when used in various gas environments containing hydrogen. Not only can the hollow space inside the test specimen filled with gas be easily sealed, it can be used for research using only a small amount of gas with small-scale equipment and low cost. It is an object of the present invention to provide a tensile test device capable of quickly and easily evaluating the characteristics of embrittlement behavior in each chamber, and a test piece used therein.

The objects of the invention are not limited to the objects mentioned above, other objects not mentioned can be clearly understood from the description below.

The above purpose is to (1) seal a hollow lower opening through a test piece in which a hollow is formed extending from the upper fixed end to the lower fixed end along the longitudinal direction; and (2) a removable connection with the lower fixed end. (3) a lower jig that fixes the test piece; and (3) an upper jig that seals the hollow upper opening by detachable connection with the upper fixed end and is moved up and down by a linearly driven actuator to pull the test piece. (4) a gas supply unit that is connected to a supply line formed through the lower jig so as to communicate with the sealed lower opening and fills the hollow with predetermined gas at various variable pressures; This is achieved by a tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment, which is characterized by including the following.

The lower jig includes (i) a lower end fastening hole formed in a concave shape in the upper end surface so that the lower fixed end can be screwed, and (ii) a lower end surface outside the lower opening and the lower fixed end. (iii) a double lower O-ring removably installed at the lower part of the lower fastening hole so as to seal the outer peripheral surface thereof; and (iii) a first O-ring formed laterally through the outer peripheral surface of the lower jig. The supply line may include a second conduit formed through a lower part of the lower end fastening hole so that the conduit and the lower opening communicate with each other.

The gas supply unit includes (iv) a flow rate valve coupled to one side of the first pipe line to adjust the flow rate of gas supplied from the outside to the first pipe line, and (v) the first pipe line. and a pressure gauge coupled to the other side of the hollow space to measure the pressure of the gas flowing into the hollow space through the first pipe line.

The upper jig includes (vi) an upper end fastening hole formed in a concave shape in the lower end surface so that the upper fixed end can be screwed, and (vii) an upper end surface outside the upper opening and the upper fixed end. (viii) a double upper O-ring removably provided at the upper part of the upper end fastening hole so as to seal the outer peripheral surface; and a rotating fastening projection.

The tensile test device includes: (5) an insulating container installed so that the upper jig and the lower jig are housed therein; and (6) measuring the temperature inside the insulating container and the temperature of the test piece. The test piece may include a temperature sensor, and (7) a heat transfer device that is wound along the outer peripheral surfaces of the upper jig and the lower jig and heats or cools the test piece to a set temperature.

The heat transfer device may be a cooling pipe in which a low-temperature refrigerant is circulated, or a heating wire that is heated in response to application of a controlled power source.

Another object of the above object is to provide a test piece for use in the tensile test apparatus according to claim 1, wherein (ix) the test piece is formed relatively thin between an upper end part and a lower end part, and the test piece is formed relatively thinly between an upper end part and a lower end part, and (x) a lower fixed end formed at the lower end of the deformed portion with a diameter larger than the deformed portion and screwed to the lower jig of the tensile testing device; (xi) an upper fixed end formed at the upper end of the deformed part so as to be symmetrical with the lower fixed end with respect to the deformed part, and screwed to the upper jig of the tensile testing apparatus; Quantifying embrittlement behavior in a hydrogen gas environment characterized by including a hollow formed through the upper fixed end or the inside of the deformed part to the lower fixed end and filled with a predetermined gas at various variable pressures. This is achieved by using test pieces for the evaluation.

According to the present invention, the upper part of the test piece is fixed to the lower jig for fixing the test piece by sealing the hollow lower opening formed through the inside of the test piece, and sealing the hollow upper opening. The upper jig, which is detachably connected to the end, pulls the test piece, and the gas supply unit, which is connected to the supply line of the lower jig that communicates with the sealed lower opening, fills the hollow with a predetermined gas at various variable pressures. By doing so, evaluation data on the embrittlement behavior of the test piece can be directly obtained based on the tensile deformation of the test piece, rather than the press-fit bending deformation of the test piece using a small punch.

In addition, we have an upper and lower jig with a simple operating structure, a test piece whose hollow space is easily sealed during the process of attaching and detaching it to the jig, and a test piece whose hollow space is filled with high pressure using only a small amount of gas. The gas supply unit can be realized at low cost and with small-scale equipment, so it can be easily operated in a normal laboratory unit.

In addition, since it is possible to fill a relatively small hollow test piece with high pressure gas using only a small amount of gas, it is possible to conduct a variety of research studies at low cost without any restrictions such as regulations on high pressure gas. Development can be carried out freely, and even if some gas leaks at the end of a test, it can be dealt with safely and quickly.

1 is a perspective view of a tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment and a test piece used therein according to an embodiment of the present invention. FIG. 2 is an exploded view of FIG. 1; FIG. 2 is a cross-sectional view of FIG. 1; FIG. 4 is an operating state diagram showing the process of a test in which the hollow is filled with gas and the test piece is pulled with the state of FIG. 3 as a reference (starting point). FIG. 2 is a partially cutaway perspective view of the tensile test apparatus additionally installed with an insulated container, a temperature sensor, and a cooling pipe to configure a low-temperature test environment. FIG. 2 is a partially cutaway perspective view of the tensile test apparatus further installed with a heat insulating container, a temperature sensor, and a heating wire to configure a high temperature test environment. 2 is a graph comparing tensile stress vs. tensile strain calculated according to a tensile test conducted on a test piece filled with nitrogen N ₂ and hydrogen H ₂ at the same pressure through the tensile test apparatus of FIG. 1. . FIG. 7A is a photograph of a fracture surface showing the damage and fracture mode of a test piece fractured by the tensile test according to FIG. 7A. FIG. 7 is a cross-sectional view of a tensile test device and a test piece used in the test piece with one end clogged, for quantitatively evaluating embrittlement behavior in a hydrogen gas environment, according to a modification of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing the present invention, descriptions of known functions or configurations will be omitted in order to clarify the gist of the present invention.

FIG. 1 is a perspective view of a tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment according to an embodiment of the present invention, and a test piece used therein, and FIG. 2 is a perspective view of a tensile test device shown in FIG. FIG. 3 is an exploded view of the apparatus; FIG. 3 is a cross-sectional view of the tensile test apparatus of FIG. 1; and FIG. FIG. 5 is an operating state diagram showing the process of a test in which a tensile operation is performed, and FIG. FIG. 6 is a partially cutaway perspective view of the tensile test apparatus further installed with an insulated container, a temperature sensor, and a hot wire to configure a high temperature test environment. Figure 7a shows a comparison of the tensile stress-tensile strain curves calculated by the tensile test performed on test pieces filled with nitrogen _N2 and hydrogen _H2 at the same pressure through the tensile test apparatus shown in Figure 1. FIG. 7b is a photograph of the fracture surface showing the damage and fracture mode of the test piece fractured by the tensile test according to FIG. 7a, and FIG. 8 is a photograph of the embrittlement behavior in a hydrogen gas environment according to a modification of the present invention. 1 is a cross-sectional view of a tensile test device for quantitatively evaluating and a test piece used in the test piece, one end of which is closed.

In the description of the invention and the scope of the claims, etc., directions such as up, down, left and right (sideways or sides), front (front, front), and back (behind) are limitations of rights. For the convenience of explanation and not for the purposes of This shall apply unless otherwise specified.

The tensile test device 100 for quantitatively evaluating the embrittlement behavior in a hydrogen gas environment according to the present invention obtains evaluation data regarding the embrittlement behavior of the test piece 110 based on tensile deformation, while achieving low test costs. It was devised to allow ordinary laboratories to carry out a wide variety of research and development freely with limited equipment costs.

The test piece 110 according to the present invention is directly detachably fastened to the tensile test device 100 for quantitatively evaluating the embrittlement behavior described above, and is used to obtain evaluation data on the embrittlement behavior of the material itself. It was devised.

In order to concretely realize the above-mentioned functions and effects, a tensile test apparatus 100 for quantitatively evaluating embrittlement behavior according to an embodiment of the present invention is equipped with a test piece as shown in FIGS. 1 to 3. 110, a lower jig 120, an upper jig 130, and a gas supply section 140. The first mode uses a test piece 110 at room temperature, and as shown in FIGS. A second method may further include a transmitter and the like and use a heated or cooled test piece 110.

Each of the above-mentioned configurations will be specifically explained below.

First, the test piece 110 is a component whose sealed interior is filled with a small amount of gas G at high pressure to undergo tensile deformation while it is removably attached to the tensile testing apparatus 100 of the present invention. It can be made from a variety of materials that can be used in gaseous environments, including hydrogen, such as metals, alloys, polymer resins, and ceramics.

In order to attach the test piece 110 for the tensile test and to form a sealed space for filling the gas G, the deformed part 116 and the lower part are fixed, as shown in the enlarged views of FIGS. 1 and 8. It may include an end 112, an upper fixed end 114, a hollow S, and the like.

Here, in order to guide the test piece 110 to stretch and break in accordance with the operation of the tensile testing apparatus 100 of the present invention, the deforming part 116 is provided between the upper end and the lower end of the test piece 110. The component is formed with a small diameter and, as mentioned above, can be fabricated integrally with the lower fixed end 112 and upper fixed end 114 described below using a variety of materials.

The lower fixed end 112 has a larger diameter than the deformed part 116 described above, is formed at the lower end of the deformed part 116, and is removably coupled to the lower jig 120 (lower end fastening hole 124) of the tensile testing apparatus 100 according to the present invention. It is a component that

As shown in FIGS. 2 and 3, the outer circumferential surface of the lower fixed end 112 is formed with a male screw thread that is screwed together with the female thread formed on the inner circumferential surface of the lower end fastening hole 124. A tightening adjustment hole 112a into which a tool such as a torque wrench or a spanner is inserted may be formed at the upper end of the end 112.

Due to the lower fixed end 112 having the above-described structure, the screw connection force with the lower jig 120 can be precisely adjusted from the outside according to test conditions, etc. Also, the test piece 110 can be firmly fixed.

The upper fixed end 114 has a larger diameter than the deformed portion 116 described above, and is formed at the upper end of the deformed portion 116, that is, at a position symmetrical to the lower fixed end 112 described above with respect to the deformed portion 116. This is a component that is removably connected to the upper jig 130 (upper end fastening hole 134) of the tensile test apparatus 100 according to the above.

As shown in FIG. 3, the outer peripheral surface of the upper fixed end 114 is also formed with a male screw thread that is screwed together with the female thread formed on the inner peripheral surface of the upper end fastening hole 134. A tightening adjustment hole 114a into which a tool such as a torque wrench or a spanner is inserted may be formed at the lower end.

With the upper fixed end 114 structured as described above, the screw connection force of the upper jig 130 can be precisely adjusted from the outside according to the test conditions, etc., and when the tensile test apparatus 100 according to the present invention is operated, Piece 110 can be pulled firmly upwards.

The hollow S is located inside the specimen 110 in order to ensure that the high pressure contact and embrittlement behavior between the gas G and the specimen 110 takes place in the same conditions as the gaseous environment in which the material of the specimen 110 is used. It is an empty space installed in the space, and can be filled with various gases G at variable pressures through a gas supply unit 140 connected as will be described later.

As shown in FIG. 3, the hollow S according to the embodiment of the present invention is formed to penetrate in the longitudinal direction from the above-mentioned upper fixed end 114 to the lower fixed end 112, has an upper opening S2 formed on the upper side, and has an upper opening S2 on the lower side. A lower opening S1 may be formed in the lower opening S1.

However, as shown in FIG. 8, such a hollow S is formed so that the upper part is closed, that is, it is formed to penetrate from the inside of the deformed part 116 to the lower fixed end 112 along the longitudinal direction, It may be a closed structure in which only the lower opening S1 is formed.

This modified structure of the test piece 110 simplifies the sealing work of the hollow S when attaching and detaching the test piece 110 to the upper fixed end 114, increasing the simplicity and efficiency of the test, while also preventing gas G leakage. This is to further reduce the risk of

As seen above, the test piece 110 according to the embodiment of the present invention is made of the same material as API (American Petroleum Institute) X70 steel pipe for transportation of crude oil or gas, suitable for direct transportation and storage applications for aggressive hydrogen. I will do it.

Here, the test piece 110 was manufactured to a compact standard with a length of 33 mm, an outer diameter of the deformed part 116 of 6.35 mm, and an inner diameter of the hollow S of 2 mm so that it could be easily handled in a normal laboratory. The outer circumferential surfaces of the upper fixed end 114 and the lower fixed end 112 can be formed with M12 (outer diameter 12 mm; pitch 1.75 mm) standard threads (external threads).

The lower jig 120 is removably connected to the lower fixed end 112 of the test piece 110 described above, seals the lower opening S1 of the hollow S, and serves as a component for fixing the test piece 110, as shown in FIGS. As shown in FIG. 3, it can be configured to include a lower end O-ring 126, a supply line 122, and the like.

Here, the lower end fastening hole 124 is formed in a concave shape from the upper end surface of the lower jig 120 so as to accommodate the above-mentioned lower fixed end 112, and is a component for firmly fixing the test piece 110. The female thread formed along the surface forms a threaded connection with the male thread of the lower fixed end 112 described above.

The lower end O-ring 126 is a component that is removably installed at the bottom of the lower end fastening hole 124 in order to double seal the lower opening S1 of the hollow S described above, and as shown in FIGS. 1 and 2. In addition, it may have a double structure including a first lower O-ring that contacts the lower end surface of the lower fixed end 112 and a second lower O-ring that surrounds the outer peripheral surface of the lower end of the lower fixed end 112.

Here, the first lower O-ring is a ring-shaped component made of an elastic material such as rubber or silicone, and is inserted into a mounting hole (ring-shaped recess) formed on the lower surface of the lower end fastening hole 124. It is installed and comes into contact with the outer lower end surface of the lower opening S1.

Such a first lower O-ring acts to seal the lower opening S1 from the outside by pressurizing the outer lower end surface of the lower opening S1 as the screw fastening of the lower fixed end 112 described above progresses. It turns out.

The second lower O-ring is a ring-shaped component made of an elastic material such as rubber or silicone, and is a mounting hole formed in a groove shape along the inner peripheral surface of the lower part of the lower end fastening hole 124. It is inserted into a ring-shaped recess) and is placed in contact with the outer circumferential surface of the lower fixed end 112.

Such a second lower O-ring is configured to press the outer peripheral surface of the lower fixed end 112 as the screw fastening of the lower fixed end 112 described above progresses, thereby opening the lower opening S1 to the first lower O-ring described above. At the same time, it acts as an overlapping seal.

The first and second lower O-rings as described above are replaced as appropriate, depending on the test conditions for gas G (temperature, pressure, etc.) and taking into consideration the temperature resistance, durability, hardness, etc. of the O-ring itself. By doing so, a strong sealing force against the gas G filled in the hollow S can be formed.

The supply line 122 is connected to the lower fixed end so that as the screw fastening of the lower fixed end 112 progresses, the lower opening S1 sealed by the lower end O-ring 126 and the storage tank that supplies the gas G from the outside communicate with each other. This is a component in the shape of a conduit formed through the tool 120.

Such a supply line 122 is formed including a first conduit 122b and a second conduit 122a, which are formed by drilling the main body of the lower jig 120, as shown in FIG. 3 and the like.

Here, the first conduit 122b is a conduit-shaped component connected to an external storage tank, a gas supply section 140, etc. to be described later, and is formed to penetrate laterally from the outer peripheral surface of the lower jig 120. sell.

As described above, the second conduit 122a has a conduit shape that is formed so that the lower opening S1 whose periphery is doubly sealed communicates with the first conduit 122b described above. The element may be formed through a lower part of the lower end fastening hole 124 .

The upper jig 130 is removably connected to the upper fixed end 114 described above, seals the upper opening S2 of the hollow S, and is moved up and down by a linearly driven actuator (not shown) to move the test piece 110. The tensioning component may include an upper end fastening hole 134, an upper end O-ring 136, a fastening protrusion 132, etc., as shown in FIG. 3 and the like.

Here, the upper end fastening hole 134 is a component that is formed in a concave shape from the lower end surface of the upper jig 130 so as to accommodate the above-mentioned upper fixed end 114, and securely fixes the test piece 110 to the upper jig 130. , the female thread formed along the inner peripheral surface forms a threaded connection with the male thread of the upper fixed end 114 described above.

The upper end O-ring 136 is exactly the same as the lower end O-ring 126, and is a component that is removably installed above the above-mentioned upper end fastening hole 134 in order to double-seal the upper opening S2 of the hollow S described above. As shown in FIGS. 1 and 2, it may have a double structure including a first upper O-ring and a second upper O-ring.

Here, the first upper O-ring is a ring-shaped component made of an elastic material such as rubber or silicone, and is inserted into a mounting hole (ring-shaped recess) formed on the upper surface of the upper end fastening hole 134. It is installed and comes into contact with the outer circumferential surface of the upper opening S2.

Such a first upper O-ring acts to seal the upper opening S2 from the outside by pressurizing the outer upper end surface of the upper opening S2 in accordance with the progress of screw fastening of the upper fixed end 114 described above. .

The second upper O-ring is a ring-shaped component made of an elastic material such as rubber or silicone, and is inserted into a mounting hole (ring-shaped recess) formed in the upper inner peripheral surface of the upper end fastening hole 134. The upper fixed end 114 is placed in contact with the outer circumferential surface of the upper fixed end 114.

Such a second upper O-ring is configured to press the outer peripheral surface of the upper fixed end 114 in accordance with the progress of screw fastening of the upper fixed end 114, thereby opening the upper opening S2 together with the first upper O-ring. , will perform the action of overlapping and sealing.

Like the lower O-ring, the upper O-ring 136 as described above is replaced as appropriate depending on the test conditions for gas G (temperature, pressure, etc.) and taking into consideration the temperature resistance, durability, hardness, etc. of the O-ring itself. By using it, it becomes possible to form a strong sealing force against the gas G filled in the hollow S.

However, as shown in FIG. 8, the upper part is closed, that is, the deformed part 116 is formed to penetrate from the inside of the deformed part 116 along the longitudinal direction to the lower fixed end 112, and only the lower opening S1 is formed. In the case of a hollow S structure, there is no risk of gas G leaking through the upper opening S2, so the above-mentioned upper O-ring can be omitted.

The fastening protrusion 132 is inserted from the small diameter portion of the upper end of the upper jig 130 so that the upper jig 130 can be easily separated from and connected to the operating end 10 of the actuator, which is fixedly installed so as to reciprocate up and down. It is a component formed to protrude outward in the radial direction.

As shown in FIG. 2, etc., such a fastening protrusion 132 can be attached to and detached from the operating end 10 of the actuator, which is provided with a locking hole with an opening on the side, while rotating. It consists of a protrusion structure that is engaged and connected, particularly a large diameter portion in the shape of a disk or short cylinder.

The test piece 110 screwed in advance to the upper jig 130 by the fastening protrusion 132 having the above-mentioned lateral (horizontal) locking structure is coupled with the upper jig 130 being laterally engaged with the operating end 10. do. Thereafter, a screw connection can be formed with the lower jig 120 while rotating relative to the upper jig 130, so that the researcher can more easily attach and detach the test piece 110.

In the present invention, the actuator may be any commercially available (commercialized or commercially available) device that performs linear movement in the vertical direction by a control unit (not shown) that controls the operation of the gas supply unit 140, which will be described later. A type of power unit is also acceptable.

For example, the actuator may be a hydraulic cylinder capable of accurate linear control with strong pressure, or a ball screw screwed to drive linearly in accordance with the rotation of a screw shaft connected to a motor.

The working end 10 of such an actuator is equipped with a load cell (not shown) that measures in real time the tensile force applied to the test piece 110 in response to the upward movement of the upper jig 130. The data will be sent to the control unit.

The control unit in the present invention is a component that is electrically connected to an actuator, a flow valve 142 (described later), a pressure gauge 144, a temperature sensor 160, a heat transfer device, etc., controls the operation of these, and processes generated data. Information processing and sequence control can be realized as a programmable information processing unit, such as an MCU (micro controller unit), a microcomputer, an Arduino, or a PLC (programmable logic controller).

The gas supply unit 140 is connected to the supply line 122 of the lower jig 120 that communicates with the sealed lower opening S1, and is a component that fills the hollow S with a predetermined gas G at various variable pressures, as shown in FIGS. As shown in 3 etc., it can be configured to include a flow rate valve 142, a pressure gauge 144, etc.

The flow valve 142 is connected to one side of the first pipe line 122b, and is connected to an external storage tank to adjust the amount of gas G supplied to the first pipe line 122b. The degree of opening and closing can be controlled by the control unit.

By using the flow valve 142 and the control unit, the amount of gas G filled into the hollow S can be adjusted in various ways.

The pressure gauge 144 is a component that is coupled to the other side of the first conduit 122b, opposite to the flow valve 142 described above, and measures the pressure of the gas G that has flowed into the hollow S via the first conduit 122b. As a result, data regarding the pressure of the gas G measured in real time by the pressure gauge 144 can be transmitted to the control unit.

On the other hand, the first form according to the embodiment of the present invention including the above-described configuration acquires evaluation data on the embrittlement behavior of the test piece 110 heated or cooled to a specific temperature, rather than the test piece 110 at room temperature (gas environment). In order to do this, it can be modified into a second form that further includes a heat insulating container 150, a temperature sensor 160, a heat transfer device, etc., as shown in FIGS. 5 and 6.

Here, the heat insulating container 150 is a capsule-shaped component installed so that the upper jig 130 and the lower jig 120 are housed therein, and suppresses internal heat from being released to the outside. It can be made of ceramic, synthetic resin, or composite materials that are durable in high and low temperature environments and can prevent heat loss to the outside.

Such a heat insulating container 150 may have a structure that allows the specimen 110, the upper jig 130, and the lower jig 120 to be combined or separated without interfering with the upper jig 130, which is linearly driven upward. The specific shape is not particularly limited.

The temperature sensor 160 is a pair of components provided inside the insulation container 150 in order to measure the temperature inside the insulation container 150 and the temperature of the test piece 110. It can be a commercially available sensor that converts into an electrical signal such as.

A control unit electrically connected to such a temperature sensor 160 receives temperature data measured in real time by the temperature sensor 160, and controls the operation of a heat transfer device described below based on the received temperature data. It turns out.

The heat transfer device is a component that is provided along the outer peripheral surfaces of the upper jig 130 and the lower jig 120 and heats or cools the test piece 110 to a set temperature, and a low-temperature refrigerant R is circulated inside. It can be configured with a cooling pipe 170a, a hot wire 170b that is heated in response to an application from a controlled power source, or the like.

Here, the cooling pipe 170a for cooling the inside of the test piece 110 and the heat insulating container 150 has a configuration corresponding to an evaporator in a commercially available cooling system, which is composed of a compressor, a condenser, an evaporator, etc. There may be.

As shown in FIG. 5, the cooling pipe 170a is arranged in the form of a coil that wraps around the lower jig 120 and the upper jig 130 inside the heat insulating container 150, and then is cooled from the outside by operation control by the control unit. Upon receiving the refrigerant R, the inside of the heat insulating container 150 is cooled to the set temperature.

As shown in FIG. 6, the heating wire 170b is installed in the form of a pad surrounding the lower jig 120 and the upper jig 130 inside the heat insulating container 150, and then the control power source is turned on under operation control by the control unit. As a result, the inside of the heat insulating container 150 is heated to the set temperature.

A series of processes (Slow Strain Rate Tensile Test (SSRT, Tensile Test)) The embrittlement behavior of the test piece 110 in a gas environment at room temperature, low temperature, or high temperature can be confirmed in the form (evaluation data) as shown in the graph of FIG. 7A.

The process of a series of tensile tests using the quantitative evaluation tensile test apparatus 100 according to the embodiment of the present invention is as follows.

First, the test piece 110 may be screwed to the separated lower jig 120 and upper jig 130, respectively, to seal the lower opening S1 and the upper opening S2.

At this time, after the test piece 110 is screwed to the lower jig 120 to seal the lower opening S1, the upper jig 130 is rotated and fastened.

Next, a process of filling the inside of the hollow S with the gas G at a set pressure via the gas supply unit 140 can be performed. At this time, hydrogen gas is filled in a space that is open or has explosion-proof equipment.

Next, the assembly of the lower jig 120 and the upper jig 130 to which the test piece 110 is screwed is carried into a normal laboratory, and is attached to the operating end 10 of the actuator and the base frame 20 at the lower end, respectively. A fastening process may be performed to lock and secure the device.

At this time, a process of controlling the operation of the heat transfer device may be selectively performed based on the temperature measured by the temperature sensor 160 in order to realize a set low or high temperature gas environment.

Next, while the hollow S is filled with the gas G at a set pressure, the upper jig 130 can be moved upward until the test piece 110 breaks.

Finally, the tensile stress applied to the test piece 110 as the upper jig 130 moves upward is measured via a load cell, and the tensile strain of the test piece 110 is measured and graphed in the form shown in FIG. 7a. The process of

As described above, after completing the graph in FIG. 7a and the test in FIG. 7b obtained through the tensile test apparatus 100 for quantitative evaluation according to the embodiment of the present invention, observations (electronic Microscope), the following evaluation data and effects can be expected.

First, if we connect the tensile stress-tensile strain graph for the test piece 110 (see Figure 7a) with the observation of the fracture mode and fracture surface of the test piece 110 after the test completion (see Figure 7b), we can qualitatively The degree of hydrogen embrittlement resistance can be confirmed, and it is possible to classify the ductile-brittle transition behavior due to embrittlement of the material of the test piece 110 according to the test temperature.

Second, the reduction of area (RA) of the test piece 110, which is calculated by measuring the cross-sectional area of the broken end of the test piece 110 before and after the tensile test (SSRT) using the present invention, is After calculating the inert gas such as nitrogen gas, argon or helium, and the test target gas such as hydrogen (RAH2, RAN2), calculate the relative reduction of area (RRA) which is the ratio of these. If it is derived as follows, it can be used as an index for selecting hydrogen-resistant brittle materials.

*RRA=RAH2/RAN2
(RAH2: cross-sectional shrinkage rate determined in an environment of hydrogen gas _H2 , RAN2: cross-sectional shrinkage rate determined in an environment of inert gas _N2 )

Although specific embodiments of the invention have been described and illustrated, it is understood that the invention is not limited to the embodiments described and may be modified and modified in various ways without departing from the spirit and scope of the invention. is obvious to those skilled in the art. Therefore, such modifications or variations should not be understood as separate from the technical idea or viewpoint of the present invention, but should fall within the scope of the claims of the present invention.

10: Working end of actuator, 20: Base frame,
100: Tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment,
110: Test piece, 112: Lower fixed end,
112a, 114a: Tightening adjustment hole, 114: Upper fixed end,
116: Deformed part, S: Hollow, S1: Lower opening, S2: Upper opening,
120: Lower jig, 122: Supply line,
122a: second pipe line, 122b: first pipe line, 124: lower end fastening hole,
126: Lower end O-ring, 130: Upper jig, 132: Fastening protrusion,
134: Upper fastening hole, 136: Upper O-ring,
140: gas supply unit, 142: flow valve, 144: pressure gauge,
G: gas, 150: heat insulating container, 160: temperature sensor,
170a: cooling pipe (heat transferer), R: refrigerant,
170b: Heating wire (heat transfer device)

Claims (7)

A test piece having a hollow penetratingly formed from the upper fixed end to the lower fixed end along the longitudinal direction;
a lower jig that seals the hollow lower opening and fixes the test piece by removably coupling with the lower fixed end;
an upper jig that seals the hollow upper opening through a detachable connection with the upper fixed end, and is actuated up and down by a linearly driven actuator to pull the test piece;
a gas supply unit that is connected to a supply line formed through the lower jig so as to communicate with the sealed lower opening, and fills the hollow with a predetermined gas at various variable pressures;
A tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment. The lower jig is
a lower end fastening hole formed in a concave shape on the upper end surface so that the lower fixed end is fastened with a screw;
a double lower end O-ring that is removably installed at the lower part of the lower fastening hole so as to seal the outer lower end surface of the lower opening and the outer peripheral surface of the lower fixed end;
and a second conduit formed to penetrate through a lower part of the lower end fastening hole so that a first conduit formed to penetrate laterally from the outer circumferential surface of the lower jig and the lower opening communicate with each other. the supply line consisting of;
A tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment according to claim 1. The gas supply section includes:
a flow valve coupled to one side of the first pipe line to adjust the flow rate of gas supplied to the first pipe line from the outside;
and a pressure gauge coupled to the other side of the first pipe line to measure the pressure of the gas flowing into the hollow via the first pipe line;
A tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment according to claim 2. The upper jig is
an upper fastening hole formed in a concave shape on the lower end surface so that the upper fixed end is fastened with a screw;
a double upper end O-ring installed in the upper part of the upper fastening hole so as to be attachable and detachable so as to seal the outer upper end surface of the upper opening and the outer circumferential surface of the upper fixed end;
a fastening protrusion that removably engages and rotates laterally with respect to the operating end of the actuator;
A tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment according to claim 1. The tensile test device includes:
a heat insulating container installed so that the upper jig and the lower jig are accommodated therein;
a temperature sensor that measures the temperature inside the heat insulating container and the temperature of the test piece;
and a heat transfer device that heats or cools the test piece to a set temperature by winding it along the outer peripheral surfaces of the upper jig and the lower jig;
A tensile test device for quantitatively evaluating embrittlement behavior in a hydrogen gas environment according to claim 1. The heat transfer device includes:
The tensile test for quantitatively evaluating embrittlement behavior in a hydrogen gas environment according to claim 5, wherein the tensile test is a cooling pipe in which a low-temperature refrigerant circulates or a hot wire heated by application of a control power source. Device. A test piece used in the tensile test device according to claim 1,
a deformable part that is formed relatively thin between the upper end and the lower end and stretches and breaks in accordance with the operation of the tensile test device;
a lower fixed end formed at the lower end of the deformable part with a diameter larger than that of the deformable part, and screwed to a lower jig of the tensile testing device;
an upper fixed end formed at an upper end of the deformed part so as to be symmetrical with the lower fixed end with respect to the deformed part, and screwed to an upper jig of the tensile testing apparatus;
a hollow formed penetrating from the inside of the upper fixed end or the deformed part to the lower fixed end and filled with a predetermined gas at various variable pressures;
A test piece for quantitatively evaluating embrittlement behavior in a hydrogen gas environment.