Hydrogen intrusion monitoring method and hydrogen intrusion monitoring device

Abstract

This invention provides a hydrogen intrusion monitoring method and apparatus that exhibit good temperature tracking capabilities for test specimens. [Solution] The method and apparatus that enable it are employed, comprising the steps of: attaching a test piece A to a test piece mounting port 23 of an exposure cell 20; exposing test piece A to a test environment; continuously supplying a carrier gas to the hydrogen detection space 13 of the exposure cell 20; and measuring the amount of hydrogen contained in the carrier gas discharged from the hydrogen detection space 13, wherein 40 ≤ F / SD ≤ 900 is satisfied during the step of measuring the amount of hydrogen contained in the carrier gas, and SC / ST ≤ 0.30 is satisfied when the step of exposing test piece A to the test environment is started, where F is the flow rate of the carrier gas supplied to the hydrogen detection space 13, SD is the area of ​​the region of test piece A exposed to the hydrogen detection space 13, SC is the area of ​​the region of test piece A in contact with a solid or liquid, and ST is the surface area of ​​test piece A.

Description

[Technical Field]

[0001] This invention relates to a hydrogen intrusion monitoring method and a hydrogen intrusion monitoring apparatus. [Background technology]

[0002] In recent years, there has been a high demand for miniaturization and weight reduction in mechanical structural components used in automobiles and industrial machinery. Therefore, there is a desire for increased strength in the materials (e.g., steel) used for these mechanical structural components. On the other hand, steel is generally considered to be more susceptible to delayed fracture when stress exceeds 1000 MPa. Delayed fracture refers to the phenomenon where a component suddenly fractures due to the presence of diffusible hydrogen. Delayed fracture is caused by hydrogen intrusion into the steel. High-strength materials applied to mechanical structural components should ideally be steel that does not cause delayed fracture. The effects of hydrogen on strength in high-strength materials other than steel are also being investigated.

[0003] Generally, delayed fracture is a phenomenon in which a component suddenly breaks after a certain amount of time has elapsed since fastening or starting use, in an environment where hydrogen penetrates the component due to corrosion or other reasons. It is difficult to predict the occurrence of this phenomenon. It is believed that three factors influence this phenomenon: material properties, the stress applied to the material during use, and the environment in which hydrogen penetrates.

[0004] However, there is a problem with evaluating environments in which hydrogen may penetrate: evaluation methods and equipment capable of handling various environments have not yet been established. In particular, hydrogen penetration into materials takes several years on a long timescale, making measurement under practical conditions impractical.

[0005] Therefore, to perform evaluations of atmospheric exposure in a short period of time, combined cycle corrosion (CCT) tests are sometimes employed. A CCT test is an accelerated test that speeds up corrosion reactions. By measuring the amount of hydrogen that penetrates into the steel material through a CCT test, the amount of hydrogen penetration into the steel material can be evaluated. CCT tests often involve rapid changes in temperature and humidity in order to accelerate each reaction. When performing a hydrogen permeation test and evaluating hydrogen penetration in an atmosphere with such rapid environmental changes, the amount of hydrogen penetration cannot be evaluated simply by placing a test specimen in the test atmosphere alone, as in a normal corrosion test. It is necessary to immerse an entire cell incorporating a mechanism for detecting hydrogen into the atmosphere.

[0006] For example, Patent Documents 1 to 3 disclose various methods for evaluating the amount of hydrogen intrusion. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2011-179893 [Patent Document 2] Patent No. 6172097 [Patent Document 3] Patent No. 7417100 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] When a test specimen is placed in a test chamber for CCT testing, already assembled in a cell for evaluating hydrogen penetration, the specimen's ability to track temperature fluctuations within the chamber deteriorates. The more components attached to the specimen to be evaluated, the greater the heat capacity of the cell it is assembled in. As a result, heat loss from the specimen to the cell worsens the specimen's ability to track temperature. Therefore, it becomes difficult to evaluate the specimen by keeping it at a predetermined temperature.

[0009] In the techniques described in Patent Documents 1 and 2, the electrochemical hydrogen permeation method cannot be used if the solution freezes and loses its conductivity, so it is necessary to select a solution that can be used at low temperatures. In addition, since a strong base of NaOH is used for measurement, which requires background subtraction using a reference cell, if the test specimen is perforated due to damage or corrosion of the cell, the strong base may leak out of the test system and have an adverse effect on the environment. Furthermore, due to the influence of the heat capacity of the solvent, there is a possibility that the temperature of the component used for evaluation will differ from the temperature of the actual environment. Thus, in addition to the need to pay attention to the handling of the testing machine and the environment in which the testing machine can withstand, it is difficult to perform measurements with good temperature tracking for the measurement sample using the techniques described in Patent Documents 1 and 2.

[0010] Patent Document 3 describes a method for quantifying the amount of hydrogen in steel without using solvents such as strong bases, but it does not describe the consideration of temperature-following capabilities during corrosion tests using CCT or the like. Therefore, even when using the technology described in Patent Document 3, if measurements are to be taken in environments with drastic temperature changes, sufficient attention must be paid to the handling of the testing equipment and the discrepancy between the temperature of the material and the actual ambient temperature.

[0011] This invention has been made in view of the above-mentioned circumstances, and aims to provide a hydrogen intrusion monitoring method and a hydrogen intrusion monitoring device that exhibit good temperature tracking performance of the test specimen. [Means for solving the problem]

[0012] In other words, the gist of the present invention is as follows: (1) The process involves attaching a test specimen to the test specimen attachment port of an exposure cell having a hydrogen detection space and being provided with a gas inlet, gas outlet, and test specimen attachment port that connect the hydrogen detection space to an external space. The process involves exposing the test specimen attached to the exposure cell to the test environment, Continuously supplying a carrier gas into the hydrogen detection space through the gas inlet of the exposure cell and continuously discharging the carrier gas from the hydrogen detection space through the gas outlet; Measuring the amount of hydrogen contained in the carrier gas discharged from the hydrogen detection space; comprising; The test piece mounting port is sealed by the test piece and a seal disposed between the test piece and the exposure cell; During the step of measuring the amount of hydrogen contained in the carrier gas, the following formula (i) is satisfied; When starting the step of exposing the test piece to the test environment, a hydrogen intrusion monitoring method characterized by satisfying the following formula (ii). 40 ≦ F / SD ≦ 900 …(i) SC / ST ≦ 0.30 …(ii) However, in formula (i) and formula (ii), F is the flow rate of the carrier gas supplied to the hydrogen detection space in units of mm 3 / min; SD is the area in units of mm of the region of the test piece exposed to the hydrogen detection space 2 ; SC is the area in units of mm of the region of the test piece in contact with a solid or liquid 2 ; ST is the surface area of the test piece in units of mm 2 . (2) The test piece has a plate-like shape with a thickness of 2.0 mm or less; The hydrogen intrusion monitoring method according to (1), characterized in that the test piece has a hydrogen gasification promoting film on the detection surface, which is the region exposed to the hydrogen detection space. (3) The amount of hydrogen contained in the carrier gas supplied to the gas inlet is 50 volppb or less; The hydrogen intrusion monitoring method according to (1), characterized in that the flow rate of the carrier gas is constant. (4) The hydrogen intrusion monitoring method according to (1), characterized in that it is carried out outdoors and / or on a moving body. (5) The hydrogen intrusion monitoring method according to (2), characterized in that the hydrogen gasification promoting film is a Ni film, a Pd film, or a stable passive film having a film thickness of 5 nm or more and 500 nm or less. (6) A hydrogen intrusion monitoring device for carrying out the hydrogen intrusion monitoring method according to any one of (1) to (5), a carrier gas supply means, an exposure cell having a hydrogen detection space and provided with a gas inlet, a gas outlet, and a test piece attachment port for communicating the hydrogen detection space with the external space, a hydrogen amount measuring means, a gas supply flow path connecting the carrier gas supply means and the gas inlet of the exposure cell, a gas discharge flow path connecting the hydrogen amount measuring means and the gas outlet of the exposure cell, Characterized by comprising, a hydrogen intrusion monitoring device. (7) The hydrogen intrusion monitoring device according to (6), characterized in that the carrier gas supply means is configured to supply the carrier gas having a hydrogen content of 50 volppb or less. (8) The hydrogen intrusion monitoring device according to (6), characterized in that it is configured to operate outdoors and / or on a moving body. (9) [ The hydrogen intrusion monitoring device according to (6), further comprising a flow rate control means configured to constantly control the flow rate of the carrier gas supplied to the exposure cell.

Advantages of the Invention

[0013] According to the present invention, it is possible to provide a hydrogen intrusion monitoring method and a hydrogen intrusion monitoring device with good temperature tracking properties of a test piece.

Brief Description of the Drawings

[0014] [Figure 1] This is a schematic diagram showing the configuration of an apparatus according to one embodiment of the present invention. [Figure 2] This is a detailed, enlarged view of the area surrounding the test specimen in Figure 1. [Figure 3] Figure 1 is a perspective view of the area surrounding the test specimen. [Figure 4] This is a schematic diagram illustrating the evaluation method for temperature tracking performance using the hydrogen intrusion monitoring device according to this embodiment. [Modes for carrying out the invention]

[0015] This disclosure relates to a method for evaluating the amount of hydrogen that penetrates a component, such as steel, and to an apparatus for evaluating the amount of hydrogen. In particular, this disclosure relates to a hydrogen intrusion monitoring method and apparatus that can continuously monitor the amount of hydrogen that is generated by corrosion of a component and penetrates the component, such as in a corrosive environment which is a real-world usage environment, while having good temperature-following capabilities, and can be implemented without using a medium other than air, so that it is safe even if the measuring medium leaks to the outside.

[0016] [Hydrogen intrusion monitoring method] The following describes a hydrogen intrusion monitoring method according to one embodiment of this disclosure. While the following description assumes that the component to be measured is made of steel, the component can be made of other metal materials and is not particularly limited to steel.

[0017] The hydrogen intrusion monitoring method according to this embodiment comprises the steps of: attaching a test piece A to the test piece mounting port 23 of an exposure cell 20 having a hydrogen detection space 13 and provided with a gas inlet 15b, a gas outlet 15c, and a test piece mounting port 23 that communicate the hydrogen detection space 13 with the outside space; exposing the test piece A attached to the exposure cell 20 to a test environment; continuously supplying a carrier gas to the hydrogen detection space 13 through the gas inlet 15b of the exposure cell 20 and continuously discharging the carrier gas from the hydrogen detection space 13 through the gas outlet 15c; and measuring the amount of hydrogen contained in the carrier gas discharged from the hydrogen detection space 13. The test piece mounting port 23 is sealed by the test piece A and a seal 21 placed between the test piece A and the exposure cell 20, and the following formula (i) is satisfied during the step of measuring the amount of hydrogen contained in the carrier gas, and the following formula (ii) is satisfied when the step of exposing the test piece A to the test environment is started. 40 ≤ F / SD ≤ 900 …(i) SC / ST ≤ 0.30 …(ii) However, in equations (i) and (ii), F is the amount of the carrier gas supplied to the hydrogen detection space 13, in units of mm 3 The flow rate is in units of / min, and SD is the area of ​​test specimen A exposed to the hydrogen detection space 13, in units of mm. 2 SC is the area in the region of test specimen A that is in contact with a solid or liquid, measured in mm². 2 This is the area, and ST is the area of ​​test piece A, in units of mm. 2 This is the surface area.

[0018] The reason for the poor temperature tracking performance of conventional hydrogen intrusion monitoring systems lies in the presence of solvent in contact with the detection surface of the test specimen. For example, in electrochemical hydrogen permeation methods such as those described in Patent Documents 1 and 2, a large amount of solvent is essential in principle. Liquids have significantly higher specific heat and thermal conductivity than the same volume of gas. Therefore, the systems disclosed in Patent Documents 1 and 2 suffer from poor temperature tracking performance of the test specimen. Furthermore, the hydrogen intrusion monitoring system described in Patent Document 3 uses gas analysis. However, the system described in Patent Document 3 does not take temperature tracking into consideration, and the apparatus is large. Therefore, the technology disclosed in Patent Document 3 has a large heat capacity for the entire apparatus, especially around the measurement test specimen. Consequently, the temperature tracking performance of the test specimen is also poor. The inventors have found that the above-mentioned problem can be solved by reducing the area in contact with the solid or liquid in the test specimen and by adjusting the flow rate of the carrier gas. In other words, the hydrogen intrusion monitoring device according to this embodiment measures the amount of hydrogen using gas analysis without using liquid. Furthermore, the hydrogen intrusion monitoring device according to this embodiment reduces the surface area of ​​solid and liquid in contact with the test specimen. In addition, the hydrogen intrusion monitoring device according to this embodiment adjusts the flow rate of the carrier gas relative to the detection area of ​​the test specimen. This suppresses heat dissipation from the test specimen and improves the temperature tracking ability of the test specimen.

[0019] The hydrogen intrusion monitoring method according to this embodiment will be described in detail below.

[0020] First, in the hydrogen ingress monitoring method according to this embodiment, test piece A is first attached to the exposure cell 20. With test piece A attached, the exposure cell 20 is exposed to the test environment. The exposure cell 20 has a hydrogen detection space 13. The exposure cell 20 is also provided with at least three openings that connect the hydrogen detection space 13 to the external space of the exposure cell 20. The three openings are a gas inlet 15b, a gas outlet 15c, and a test specimen mounting opening 23. A test specimen A is attached to the test specimen mounting port 23 of the exposure cell 20. As will be described later, the test specimen mounting port 23 is sealed by the test specimen A and the seal 21. Through the test specimen mounting port 23, the detection surface A2 of the test specimen A is exposed to the hydrogen detection space 13. Hydrogen generated on the test surface A1 of the test specimen A and entering the interior of the test specimen A is gasified on the test surface A1 and released into the hydrogen detection space 13. The test specimen mounting port 23 is, for example, circular. Gripping means for attaching the test specimen A may be provided around the test specimen mounting port 23. Also, screw holes for attaching the test specimen A may be provided around the test specimen mounting port 23. A carrier gas is supplied to the gas inlet 15b of the exposure cell 20. The carrier gas is also discharged from the gas outlet 15c of the exposure cell 20. The carrier gas continuously passes through the hydrogen detection space 13 from the start to the end of the hydrogen ingress monitoring test. The carrier gas carries the hydrogen released from the detection surface A2 at the test specimen mounting port 23 from the hydrogen detection space 13 to the hydrogen amount measuring means 14. The gas inlet 15b and gas outlet 15c may be provided with fittings to facilitate the attachment and detachment of the flow path for the carrier gas.

[0021] The test piece A to be attached to the test piece mounting port 23 is preferably in a plate shape with a thickness of 2.0 mm or less, and has a hydrogen gasification promoting film on the detection surface A2, which is the area exposed to the hydrogen detection space 13. The reason for limiting the thickness of test specimen A to 2.0 mm or less is to avoid unnecessarily prolonging the time required for hydrogen to permeate from test surface A1 to detection surface A2. To efficiently permeate hydrogen, the thickness of test specimen A is preferably 1.0 mm or less, or 0.5 mm or less. If the crystal structure of test specimen A is FCC or HCP with a close-packed structure, the thickness of the test specimen is preferably 0.3 mm or less. Furthermore, if the detection surface A2 is not surface-treated before the start of measurement, hydrogen gasification on the detection surface A2 will not proceed easily. Therefore, it is preferable to form a hydrogen gasification promoting film on the detection surface A2 before the start of measurement. The type of hydrogen gasification promoting film is not particularly limited, but by making the hydrogen gasification promoting film a Ni film, Pd film, or stable passivation film with a thickness of 5 nm to 500 nm, hydrogen can be detected stably. Accordingly, the hydrogen gasification promoting film may be a Ni film, Pd film, or stable passivation film with a thickness of 5 nm to 500 nm. This is presumed to be because coatings such as Ni and Pd promote the gasification of hydrogen atoms on the surface, so even if the amount of hydrogen entering is small, hydrogen release on the surface of the test piece can be controlled by internal diffusion.

[0022] Subsequently, test specimen A, attached to the exposure cell 20, is exposed to the test environment. As a result, hydrogen is generated on the test surface A1 due to corrosion, and some of it penetrates into the interior of test specimen A. The hydrogen that has penetrated into the interior of test specimen A then reaches the detection surface A2 and is vaporized.

[0023] At this time, a carrier gas is continuously supplied to the hydrogen detection space 13 through the gas inlet 15b of the exposure cell 20, and the carrier gas is continuously discharged from the hydrogen detection space 13 through the gas outlet 15c.

[0024] Then, the amount of hydrogen contained in the carrier gas emitted from the hydrogen detection space 13 is measured. Here, the total amount of hydrogen generated on the detection surface A2 during the test may be measured, or the amount of hydrogen generated over time while the test surface A1 is exposed to the test environment may be measured.

[0025] Furthermore, the amount of hydrogen in the carrier gas is preferably 50 vol ppb or less to ensure measurement accuracy. The amount of hydrogen in the carrier gas may also be 20 vol ppb or less, 10 vol ppb or less, or 5 vol ppb or less. As long as the amount of hydrogen is within the above range, slight fluctuations in the amount of hydrogen in the carrier gas are permissible, but it is preferable that the amount of hydrogen in the carrier gas remains constant during the test. In addition, both the amount of hydrogen in the carrier gas before it is supplied to the hydrogen detection space 13 and the amount of hydrogen in the carrier gas discharged from the hydrogen detection space 13 may be measured, and the difference between the two may be calculated. For example, the amount of hydrogen in the carrier gas before it is supplied to the hydrogen detection space 13 can be measured using a flow path that does not pass through the exposure cell 20 described later. Furthermore, the flow rate of the carrier gas is preferably kept constant using a mass flow controller or the like to ensure measurement accuracy.

[0026] The specimen mounting port 23 is sealed by the specimen A and the seal 21 placed between specimen A and the exposure cell 20. If the sealing is insufficient, the amount of hydrogen in the exposure cell 20 will be affected by the outside air, making accurate measurement difficult. Furthermore, if the sealing is insufficient, saltwater and corrosion products from the test environment may enter the exposure cell 20. The seal 21 only needs to be capable of sealing the gap between the test specimen A and the exposure cell 20. Preferred examples of the seal 21 are O-rings and gaskets. The material of the seal 21 is not particularly limited, as long as it has low thermal conductivity. The material of the seal 21 may be, for example, silicone or nitrile rubber, and may be appropriately selected depending on the test environment. Furthermore, a sealant may be used in conjunction with the sealant to improve airtightness. The type of sealant is not particularly limited, but for example, it may be made of silicone, polyurethane, or polysulfide.

[0027] While measuring the amount of hydrogen contained in the carrier gas, the relationship between the detection area and the carrier gas flow rate must satisfy equation (i) below. Equation (i) must always be satisfied from the start to the end of the hydrogen ingress monitoring test.

[0028] 40 ≦ F / SD ≦ 900 …(i)

[0029] In formula (i), F is the flow rate of the carrier gas supplied to the hydrogen detection space 13, in units of mm 3 / min. SD is the area, in units of mm 2 of the region of the test piece A exposed to the hydrogen detection space 13, and is also the area exposed to the carrier gas. In the following, F may be described as the "carrier gas flow rate" and SD as the "detection area".

[0030] The larger SD is, that is, the larger the detection area is, the higher the concentration of hydrogen gas discharged from the test piece A becomes, and the smaller the influence of cooling the test piece A by the carrier gas becomes. The larger F is, that is, the larger the carrier gas flow rate is, the greater the influence of cooling the test piece A by the carrier gas becomes. When F / SD is less than 40, it indicates that the carrier gas flow rate is too small relative to the amount of hydrogen generated from the detection surface A2 of the test piece A. That is, when F / SD is less than 40, the amount of hydrogen in the carrier gas to be measured becomes excessive, and the measurement accuracy of the amount of hydrogen decreases. On the other hand, when F / SD exceeds 900, it indicates that the carrier gas flow rate is excessive. That is, the test piece A is greatly affected by the cooling due to the flow of the carrier gas, and the temperature followability of the test piece A deteriorates. F / SD may be 80 or more, 100 or more, or 200 or more. F / SD may be 800 or less, 700 or less, or 600 or less.

[0031] Also, when exposing the test piece A to the test environment, it is necessary to satisfy the following formula (ii). Note that when exposing the test piece A to the test environment, it refers to the time point when the test piece A or the exposure cell 20 to which it is attached is placed in the test tank of the CCT test apparatus and the atmosphere in the test tank is set as the test atmosphere.

[0032] SC / ST ≦ 0.30 …(ii)

[0033] SC is the area, in units of mm 2This is the area, where ST is the area of ​​test specimen A, in units of mm. 2 This is the surface area.

[0034] The solid or liquid includes, in addition to the seal 21 as illustrated in Figures 2 and 3, a portion of the exposure cell 20, the thermocouple, and the sealant. On the other hand, solids or liquids that adhere to specimen A after the start of its exposure to the test environment are not considered when determining SC. For example, the area of ​​specimen A in contact with the corrosive liquid sprayed onto specimen A is not included in SC. The area of ​​specimen A in contact with corrosion products that adhere to specimen A is also not included in SC. Equation (ii) defines the state of the exposure cell 20 and specimen A at the start of the process of exposing specimen A to the test environment.

[0035] A SC / ST ratio exceeding 0.30 indicates that the area in contact with the component is large relative to the surface area of ​​specimen A. In other words, specimen A is greatly affected by heat dissipation and reheating by the component in contact with it, resulting in reduced temperature tracking performance. SC / ST may be 0.25 or less, 0.2 or less, or 0.15 or less.

[0036] The hydrogen quantity measuring means 14 may be positioned close to the detection surface A2. In this case, transport of the gasified hydrogen on the detection surface A2 is unnecessary. Alternatively, the hydrogen gasified on the detection surface A2 may be transported to the hydrogen quantity measuring means 14 using a carrier gas with a hydrogen content of 50 vol ppb or less and a constant flow rate. This allows for flexible modification of the device configuration. Measurement using a carrier gas is suitable for measuring the change in hydrogen generation amount over time.

[0037] As described above, the hydrogen intrusion monitoring method according to this embodiment does not require a solvent, a special carrier gas, or a vacuum environment. In addition, the hydrogen intrusion monitoring method according to this embodiment can be implemented in various environments. For example, the hydrogen intrusion monitoring method according to this embodiment may be implemented outdoors and / or on a mobile device. That is, test piece A may be installed outdoors. Alternatively, test piece A may be installed on a mobile device. A mobile device is, for example, an automobile, an airplane, or a train. This makes it possible to monitor hydrogen intrusion into steel materials in the actual operating environment of a mobile device, contributing to the optimization of steel material properties according to the application.

[0038] [Hydrogen Intrusion Monitoring Device] The apparatus for implementing the hydrogen intrusion monitoring method according to this embodiment, as illustrated in Figures 1 to 3, comprises a carrier gas supply means 11, an exposure cell 20 having a hydrogen detection space 13 and provided with a gas inlet 15b, a gas outlet 15c, and a test piece mounting port 23 that connect the hydrogen detection space 13 to the outside space, a hydrogen amount measuring means 14, a gas supply channel connecting the carrier gas supply means 11 and the gas inlet 15b of the exposure cell 20, and a gas discharge channel connecting the hydrogen amount measuring means 14 and the gas outlet 15c of the exposure cell 20.

[0039] Regarding exposure cell 20: In the hydrogen ingress monitoring device 1 according to this embodiment, an exposure cell 20 is used as the monitoring site, configured such that the area of ​​the exposed portion of the test piece A to be evaluated is known. Specifically, the exposure cell 20 is connected to a flow rate control means 12 (e.g., a mass flow controller) and supplies a carrier gas to the detection surface A2 of the test piece A. The material of the exposure cell 20 is not particularly limited as long as it is a material that can withstand the monitoring environment, and can be appropriately selected according to the monitoring environment. For example, a non-metallic material with high airtightness, such as acrylic resin, is preferred.

[0040] For test specimen A, a thin steel plate with a thickness of 2.0 mm or less is used. Hydrogen taken into test specimen A from the test surface A1 permeates through test specimen A and is gasified at the detection surface A2. This hydrogen is taken up by a carrier gas and transported to the hydrogen amount measuring means 14.

[0041] When attaching test specimen A to the exposure cell 20, it is desirable that the gripping member 22 does not directly contact test specimen A, but is attached to the exposure cell 20 only via the seal 21, as shown in Figure 2. Although not shown in Figure 2, it is desirable that the gripping member 22 and the exposure cell 20 be connected by a fastener. By adopting this configuration, the contact area of ​​solid or liquid that comes into contact with test specimen A can be reduced.

[0042] When mounting, the surface area of ​​test piece A relative to the contact area with the solid or liquid on its surface should be as small as possible. The specific relationship is as described above.

[0043] Although not shown in Figures 1 to 3, a thermocouple may be attached to test specimen A for the purpose of monitoring its temperature. Alternatively, a non-contact infrared thermometer may be used to monitor the temperature of test specimen A. This prevents an increase in SC caused by attaching a temperature monitoring device to test specimen A, thus preventing heat loss.

[0044] Furthermore, it is preferable that the exposure cell 20 be equipped with a mechanism capable of measuring the temperature and atmospheric pressure of the test specimen A. This allows monitoring of the environment to which the test surface A1 is exposed. The exposure cell 20 also includes a configuration for separating the detection surface A2 from the test environment while exposing the test surface A1 to the test environment. The detection surface A2 is exposed to the test system inside the apparatus, i.e., a series of airtight systems from the carrier gas supply means 11 to the hydrogen amount measuring means 14, and the exposure cell 20 constitutes a part of the airtight system.

[0045] Regarding the carrier gas supply means 11, the flow rate control means 12, and the gas flow path: The carrier gas supply means 11 and the flow rate control means 12 supply the carrier gas and control the flow rate of the carrier gas in order to quantify the amount of hydrogen. The carrier gas supply means 11 is not particularly limited and can be, for example, a gas cylinder containing any carrier gas with a hydrogen content of 50 vol ppb or less. In this case, the measurement accuracy can be further improved. On the other hand, when the hydrogen intrusion monitoring device 1 is mounted on a mobile body and operated for a long period of time, the carrier gas supply means 11 may have a mechanism that inhales air from the atmosphere, burns the hydrogen gas to 50 vol ppb or less in an air purifier, and then discharges the air. The carrier gas supply means 11 may further include a filter to remove moisture generated when the hydrogen gas is burned, as well as dust and other particles that are inhaled. The carrier gas can be an inert gas such as nitrogen and argon.

[0046] After the carrier gas is generated by the carrier gas supply means 11, the flow rate of the carrier gas is adjusted to a constant value within a predetermined range by the flow rate control means 12, which is connected to the carrier gas supply means 11 by the gas flow path 15a. The flow rate can be appropriately selected according to the specifications of the hydrogen amount measuring means 14.

[0047] The gas flow path connects the carrier gas supply means 11, the flow rate control means 12, the exposure cell 20, and the hydrogen amount measuring means 14, as shown in the carrier gas flow path G, thereby forming a test system inside the device, i.e., a series of airtight systems from the carrier gas supply means 11 to the hydrogen amount measuring means 14. The material of the gas flow path is preferably one that does not generate gases that would affect the sensitivity of the sensor, for example, acrylic resin. A switch mechanism may be provided in the gas flow path to monitor several types of cells with the same sensor. The connections between the gas flow path and other components can also be appropriately selected for the same purpose as the flow path.

[0048] As described above, the hydrogen intrusion monitoring device 1 according to this embodiment does not require a strong base solvent, a special carrier gas, or a vacuum environment. Therefore, the hydrogen intrusion monitoring device 1 according to this embodiment may be configured to operate outdoors and / or on a mobile device. This makes it possible to monitor hydrogen intrusion into steel materials in the actual operating environment of the mobile device, contributing to the optimization of steel material properties according to the application.

[0049] The hydrogen ingress monitoring device 1 according to this embodiment may further include a flow path that does not pass through the exposure cell 20. By using this, the standard state of the hydrogen amount measuring means 14 can be identified. This makes it possible to calculate the difference between the amount of hydrogen contained in the carrier gas supplied from the carrier gas supply means 11 and the amount of hydrogen contained in the carrier gas discharged from the exposure cell 20.

[0050] A sampler may be included in the hydrogen intrusion monitoring device 1 according to this embodiment. The sampler is a device for injecting a fixed volume of hydrogen-containing carrier gas into a column, which will be described later. The sampler may be a flow path switching device, or it may be a device that injects carrier gas into a base flow path, such as a syringe.

[0051] Furthermore, a column may also be included in the hydrogen intrusion monitoring device 1 according to this embodiment. The column is a device for separating gases in a mixed gas. Typically, a column has a configuration in which a stationary phase packing material is filled into a long, narrow pipe, and separates gases by adsorption and distribution between the stationary phase and each gas component.

[0052] Furthermore, an air pump to facilitate the flow of carrier gas may be included in the hydrogen intrusion monitoring device 1 according to this embodiment. It is preferable to select an air pump with a capacity higher than the flow rate controlled by the flow rate control means 12, and with a flow rate lower than the processing capacity of the air purifier.

[0053] The hydrogen intrusion monitoring device and method described above allow for continuous monitoring of the amount of hydrogen generated by corrosion on the surface of steel materials and penetrating into the steel material in actual operating environments such as corrosive environments for mobile bodies. This can be done without using a medium other than air, without the need for a reference cell, regardless of the environment, and with good temperature tracking capabilities. As a result, the amount of hydrogen generated by corrosion on the surface of a component and incorporated into the component can be quantified using a hydrogen permeation method on the mobile body or in the field, and the amount of hydrogen permeation can be measured. This allows for the determination of the surface hydrogen content of the component in an actual environment, and by performing an evaluation in conjunction with the critical diffusibility hydrogen content evaluation described in Patent Document 1, it becomes possible to verify the possibility of failure due to hydrogen embrittlement of the component and its applicability. [Examples]

[0054] Examples of this embodiment are described below. Note that the examples described below are just examples of the present invention, and the present invention is not limited to these examples.

[0055] The apparatus configured as shown in Figures 1 to 3 was assembled, and the temperature tracking performance of the hydrogen intrusion monitoring apparatus and hydrogen intrusion monitoring method was investigated.

[0056] In this embodiment, the hydrogen sensor of the hydrogen intrusion monitoring device 1 is a semiconductor sensor gas chromatograph (model number: SGHA-P3-A1) manufactured by NISSA FIS Co., Ltd. This sensor gas chromatograph samples gas every two minutes, separates hydrogen from the carrier gas using gas chromatography, and quantifies the amount of hydrogen using a hot-wire semiconductor sensor.

[0057] Air from which hydrogen gas was removed by an air purifier was used as the carrier gas. The flow rate of the carrier gas was controlled to a constant level using a mass flow controller, and the amount of hydrogen contained in the carrier gas that passed through the exposure cell was quantified using the semiconductor sensor mentioned above.

[0058] The steel material used as the test specimen was SCM435. A 20kg ingot was vacuum melted and processed into a 2mm thick hot-rolled sheet by hot rolling. The hot-rolled sheet was then heated to 900°C and subjected to oil quenching, followed by tempering at 550°C for 1 hour. Subsequently, a 0.5mm thick base plate of the test specimen was machined from the hot-rolled sheet, and both sides of the base plate were polished to a mirror finish. A 100nm thick Ni coating was applied to the detection surface of the resulting test specimen, and this was used for both tests. The test surface was a 12mm diameter circle. An O-ring was used for sealing, and silicone sealant was used to improve the adhesion of the O-ring to the test specimen. The sealant application area was determined by preparing a frame corresponding to the test specimen in advance and applying the sealant within that frame.

[0059] The temperature tracking performance was evaluated using the procedure shown in Figure 4 and below. First, the temperature at one-second intervals from 25°C to 45°C when the test specimen is placed directly into the temperature-controlled chamber without being attached to the exposure cell is plotted and set as the reference value FB. Subsequently, the test specimen is attached to the exposure cell, and the temperature change from 25°C to 45°C is plotted every second to obtain a graph like the solid line in Figure 4. The horizontal axis represents time in units of s, and the vertical axis represents the temperature of the test specimen in units of °C. From the obtained graph, the area FT of the region indicated by the shaded area in Figure 4 is calculated in units of °C·s. Based on the relationship between FT and FB obtained through the above procedure, the temperature tracking capability is determined as follows. If FT ≥ 2 × FB, the temperature tracking performance is considered poor, and the result is judged as "bad". If FT < 2 × FB, the temperature tracking performance is considered good, and the result is judged as "good". If FT < 1.5 × FB, the temperature tracking performance is considered very good, and the rating is set to "great".

[0060] Table 1 shows the evaluation results of the temperature tracking performance of the sample piece using the hydrogen intrusion monitoring method.

[0061] [Table 1]

[0062] In this embodiment, measurement examples No. 1 to No. 6 shown in Table 1 were examined by adjusting F / S and C / ST. As a result of the comparison, No. 3 to No. 5 based on this embodiment all showed good temperature tracking performance. In No. 1, although equation (ii) was satisfied, equation (i) was not satisfied, and the temperature tracking performance was poor due to the effect of cooling by the carrier gas. On the other hand, in No. 2 and No. 6, although equation (i) was satisfied, equation (ii) was not satisfied, and heat dissipation and reheating occurred from the area in contact with the solid or liquid on the surface of the test piece, resulting in poor temperature tracking performance of the test piece. [Industrial applicability]

[0063] By using the hydrogen intrusion monitoring method and hydrogen intrusion monitoring device of the present invention, it becomes possible to continuously monitor the amount of hydrogen generated due to corrosion of components and entering the components in corrosive environments, etc., in the actual operating environment of a mobile body, while maintaining good temperature tracking capabilities for the components. [Explanation of symbols]

[0064] 1. Hydrogen intrusion monitoring device 11. Carrier gas supply means 12 Flow rate control means 13 Hydrogen detection space 14. Means for measuring hydrogen content 15a Gas flow path 15b Carrier gas inlet 15c Carrier gas outlet 20 Exposed Cells 21 stickers 22 Gripping material 23 Test specimen mounting opening A Test specimen A1 Test surface A2 Detection surface G Carrier gas distribution route

Claims

1. The process involves attaching a test specimen to the test specimen attachment port of an exposure cell having a hydrogen detection space and being provided with a gas inlet, gas outlet, and test specimen attachment port that connect the hydrogen detection space to an external space. The process involves exposing the test specimen attached to the exposure cell to the test environment, A step of continuously supplying a carrier gas to the hydrogen detection space through the gas inlet of the exposure cell, and continuously discharging the carrier gas from the hydrogen detection space through the gas outlet, A step of measuring the amount of hydrogen contained in the carrier gas discharged from the hydrogen detection space, Equipped with, The specimen mounting opening is sealed by the specimen and a seal placed between the specimen and the exposure cell. During the step of measuring the amount of hydrogen contained in the carrier gas, the following equation (i) is satisfied, A hydrogen ingress monitoring method characterized in that when the step of exposing the test specimen to the test environment is initiated, the formula (ii) is satisfied. 40≦F / SD≦900…(i) SC / ST≦0.30…(ii) However, in equations (i) and (ii), F is the amount of the carrier gas supplied to the hydrogen detection space, in units of mm ３ This is the flow rate in min. SD is the area of ​​the test specimen exposed to the hydrogen detection space, measured in mm. ２ This is the area in that region. SC is the area in contact with the solid or liquid in the test specimen, measured in mm. ２ This is the area in that region. ST is the unit of the test piece, in mm ２ This is the surface area.

2. The aforementioned test specimen has a plate-like shape with a thickness of 2.0 mm or less. The hydrogen intrusion monitoring method according to claim 1, characterized in that the test specimen has a hydrogen gasification promoting coating on the detection surface which is the region exposed to the hydrogen detection space.

3. The amount of hydrogen contained in the carrier gas supplied to the gas inlet is set to 50 vol ppb or less. The hydrogen intrusion monitoring method according to claim 1, characterized in that the flow rate of the carrier gas is kept constant.

4. The hydrogen intrusion monitoring method according to claim 1, characterized in that it is carried out outdoors and / or on a mobile device.

5. The hydrogen intrusion monitoring method according to claim 2, characterized in that the hydrogen gasification promoting film is a Ni film, a Pd film, or a stable passivation film with a thickness of 5 nm to 500 nm.

6. A hydrogen intrusion monitoring device for carrying out the hydrogen intrusion monitoring method described in any one of claims 1 to 5, Carrier gas supply means, An exposure cell having a hydrogen detection space and provided with a gas inlet, gas outlet, and test specimen mounting port that connect the hydrogen detection space to the outside space, A means for measuring hydrogen content, A gas supply channel connecting the carrier gas supply means and the gas inlet of the exposure cell, The hydrogen quantity measuring means and the gas discharge channel connecting the gas outlet of the exposure cell, A hydrogen intrusion monitoring device characterized by comprising the following features.

7. The hydrogen intrusion monitoring device according to claim 6, characterized in that the carrier gas supply means is configured to supply the carrier gas having a hydrogen content of 50 vol ppb or less.

8. The hydrogen intrusion monitoring device according to claim 6, characterized in that it is configured to operate outdoors and / or on a mobile device.

9. The hydrogen intrusion monitoring device according to claim 6, further comprising a flow rate control means configured to control the flow rate of the carrier gas supplied to the exposure cell to a constant level.

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