Test method for determining critical fracture stress of pipeline girth welding joint in hydrogen environment

Abstract

The invention belongs to the technical field of hydrogen conveying pipeline performance testing, particularly relates to a testing method for determining critical fracture stress of a pipeline girth welding joint in a hydrogen environment, and aims to solve the problems that an existing testing method is too high in time cost, one-sided in evaluation and the like. The method comprises the following steps: processing a tensile sample of a transverse notch of a ring welding joint in the center of a welding seam to obtain N samples; calculating a notch root sectional area based on a transverse notch size of a ring welding head of a weld center; applying a load to the first sample in an air environment at a displacement rate required by a tensile standard until the first sample is fractured to obtain a maximum load; based on the maximum load, carrying out graded loading and holding tensile tests on the second sample to the Nth sample in sequence at a set stress rate to obtain a critical fracture load of each sample; and calculating critical fracture stress based on a threshold load and the notch root sectional area. According to the method, the accurate critical fracture stress value can be obtained, and the basis is provided for comparison of the hydrogen induced cracking resistance of the pipeline girth welding joint.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen pipeline performance testing technology, specifically involving a test method, system, electronic equipment, and storage medium for determining the critical fracture stress of a pipeline ring weld joint under hydrogen conditions. Background Technology

[0002] Economical, efficient, and safe hydrogen storage and transportation technologies have become a major obstacle to the large-scale development of the hydrogen energy industry, and breakthroughs in hydrogen storage and transportation technologies are urgently needed. Among various hydrogen storage methods, pipeline hydrogen transportation has advantages such as large transport capacity, low energy consumption, and low marginal cost, and is expected to become an important transitional technology towards a "hydrogen economy." However, technical safety issues in the field of hydrogen pipeline transportation are complex and diverse, presenting numerous challenges, including technical issues such as pipeline hydrogen damage and determining the hydrogen blending ratio, as well as management standards.

[0003] In a high-pressure gaseous hydrogen environment, welded joints in pipelines can experience hydrogen-induced cracking during use, leading to low-stress failure. Hydrogen-induced cracking occurs under the combined influence of materials, environment, and stress. Under controllable environmental conditions, the stress level is crucial in determining whether a material will undergo hydrogen-induced cracking. Specifically, for a material, when the amount of hydrogen penetration is constant, there exists a threshold stress value; when the actual stress exceeds this value, hydrogen-induced cracking is likely to occur. If a method can determine the critical stress value for hydrogen-induced cracking of a welded joint under a given environment, then if the actual stress is below this value, the joint can be considered unlikely to crack. Ideally, evaluating welded joints for hydrogen-induced cracking would involve testing actual joints in a real hydrogen service environment, but this is difficult to achieve due to the challenge of simulating such an environment. In laboratory evaluation, representative testing methods include constant load fracture tests, constant strain fracture tests, slow strain rate tensile tests, and fracture mechanics tests. However, these methods suffer from drawbacks such as high time costs, scattered results, and biased evaluations, limiting their practical application in engineering.

[0004] Therefore, existing experimental methods for determining the critical fracture stress of pipe ring weld joints under hydrogen conditions have shortcomings such as high time cost, scattered results, and one-sided evaluation, which have significant limitations in engineering applications. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, namely that some experimental methods for determining the critical fracture stress of pipe ring weld joints under hydrogen conditions suffer from drawbacks such as high time costs, scattered results, and biased evaluations, thus limiting their application in engineering, this invention provides an experimental method for determining the critical fracture stress of pipe ring weld joints under hydrogen conditions. The method includes:

[0006] Tensile specimens with transverse notches at the center of the weld joint are processed to obtain N specimens; the N specimens are completely identical; N is a natural number greater than 1.

[0007] Calculate the root cross-sectional area of ​​the notch based on the transverse notch size of the circumferential weld joint at the weld center;

[0008] The first specimen was subjected to a load in air at the displacement rate required by the tensile standard until fracture, and the maximum load P was obtained. FFS ;

[0009] Based on the maximum load P FFS The critical fracture load of each specimen is obtained by performing graded loading and holding tensile tests on specimens 2 through N sequentially at a set stress rate; the difference between the critical fracture load of specimen n-1 and the critical fracture load of specimen n is not greater than 5%P. FFS When the critical fracture load of the (n-1)th specimen is smaller than the critical fracture load of the nth specimen, the critical fracture load is the threshold load; n is any natural number between 2 and N.

[0010] The critical fracture stress is calculated based on the threshold load and the cross-sectional area at the notch root.

[0011] In a preferred embodiment, the method for obtaining the critical fracture load of each specimen by sequentially performing graded loading and tensile tests on specimens 2 to N at a set stress rate includes:

[0012] With each load level being 5% of the maximum load P FFS The load was graded into 20 levels. The first 10 levels were maintained for 2 hours each, and the subsequent 10 levels were maintained for 4 hours each. A tensile test was performed on the second specimen under load, yielding its load-time and stiffness-time curves. Based on these curves, the critical fracture load P of the second specimen was determined. th-2 ;

[0013] Using the critical fracture load of the (n-1)th specimen, which is 5% of the load at each stage, as the load, graded loading was performed. The first 10 stages were held for 2 hours each, and subsequent stages were held for 4 hours each. Load-hold tensile tests were conducted on the nth specimen to obtain its load-time and stiffness-time curves. Based on these curves, the critical fracture load P of the nth specimen was determined. th-n .

[0014] In a preferred embodiment, the process before sequentially performing graded loading and holding tensile tests on specimens 2 through N at a set stress rate includes:

[0015] For the nth specimen, before the graded loading and holding tensile test, the nth specimen is installed on the metal material hydrogen environment compatibility tester. Then, the nitrogen or air in the temperature-controlled high-pressure environment chamber is driven away by three nitrogen purgings, three hydrogen purgings, and a 10-second hydrogen convection program. Pure hydrogen or hydrogen-doped gas with different hydrogen partial pressures at a predetermined pressure is introduced, followed by the graded loading and holding tensile test.

[0016] In a preferred embodiment, after sequentially performing graded loading and holding tensile tests on specimens 2 through N at a set stress rate, the process includes:

[0017] For the nth specimen, after completing the stage loading and tensile test, the gas in the temperature-controlled high-pressure environment chamber is discharged to one atmosphere, and then purged with nitrogen three times before the environment chamber is opened and the nth specimen is taken out.

[0018] In a preferred embodiment, the critical fracture load P of the nth specimen is obtained based on the load-time curve and stiffness-time curve of the nth specimen. th-n The method is as follows:

[0019] The intersection of the two linear regression descending lines of the stiffness-time curve of the nth specimen corresponds to the load at the step on the load-time curve, which is the critical fracture load Pth-n of the nth specimen.

[0020] In a preferred embodiment, the method for calculating the threshold load based on the threshold load and the cross-sectional area at the notch root is as follows:

[0021] σ th =P th / S0;

[0022] Where, σ th P is the critical fracture stress. th Threshold load, S0 is the cross-sectional area at the root of the notch.

[0023] A second aspect of the invention provides a test system for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, the system comprising:

[0024] The specimen processing module is used to process tensile specimens with transverse notches in the circumferential weld joint located at the center of the weld, resulting in N specimens; the N specimens are completely identical; N is a natural number greater than 1.

[0025] The area calculation module is used to calculate the cross-sectional area at the root of the notch based on the transverse notch size of the circumferential weld joint at the weld center.

[0026] The maximum load determination module is used to apply a load to the first specimen in an air environment at the displacement rate required by the tensile standard until fracture, and obtain the maximum load P. FFS ;

[0027] Threshold load calculation module, used to calculate based on maximum load P FFS The critical fracture load of each specimen is obtained by performing graded loading and holding tensile tests on specimens 2 through N sequentially at a set stress rate; the difference between the critical fracture load of specimen n-1 and the critical fracture load of specimen n is not greater than 5%P. FFS When the critical fracture load of the (n-1)th specimen is smaller than the critical fracture load of the nth specimen, the critical fracture load is the threshold load; n is any natural number between 2 and N.

[0028] The fracture stress calculation module is used to calculate the critical fracture stress based on the threshold load and the cross-sectional area at the notch root.

[0029] A third aspect of the present invention provides an electronic device comprising:

[0030] At least one processor; and

[0031] A memory communicatively connected to at least one of the processors; wherein,

[0032] The memory stores instructions that can be executed by the processor to implement the above-described test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions.

[0033] In a fourth aspect, the present invention provides a computer-readable storage medium storing computer instructions for execution by the computer to implement the above-described test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions.

[0034] The beneficial effects of this invention are:

[0035] (1) The solution of the present invention can obtain an accurate critical fracture stress value, which can be used as a basis for comparing the hydrogen-induced cracking resistance of pipe ring weld joints.

[0036] (2) The solution of the present invention has great practical significance for the existing assessment of the applicability of hydrogen blending in natural gas pipelines or the optimization of welding process for pure hydrogen pipelines.

[0037] (3) The method of the present invention is highly efficient, provides clear and concentrated results, and offers comprehensive evaluation, but it has significant limitations in engineering applications. Attached Figure Description

[0038] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0039] Figure 1This is a schematic diagram of an experimental method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, according to an embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of sampling a transverse notch tensile specimen of a ring welded joint according to an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of the dimensions of a transverse notch tensile specimen of a ring welded head according to an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the sample graded loading tensile scheme according to an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the load-time curve and stiffness-time curve of an embodiment of the present invention;

[0044] Figure 6 This is a transverse notch tensile specimen of a ring welded joint, as an example of an embodiment of the present invention.

[0045] Figure 7 This is a load-time curve and stiffness-time curve of a #1 notched tensile specimen in an embodiment of the present invention.

[0046] Figure 8 This is a load-time curve and stiffness-time curve of a #2 notched tensile specimen in one embodiment of the present invention.

[0047] Figure 9 This is a load-time curve and stiffness-time curve of a #3 notched tensile specimen, as shown in an embodiment of the present invention.

[0048] Figure 10 This is a schematic diagram of the structure of a computer system used to implement the methods, systems, and devices of this application. Detailed Implementation

[0049] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0050] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0051] This invention provides a test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, the method comprising:

[0052] Tensile specimens with transverse notches at the center of the weld joint are processed to obtain N specimens; the N specimens are completely identical; N is a natural number greater than 1.

[0053] Calculate the root cross-sectional area of ​​the notch based on the transverse notch size of the circumferential weld joint at the weld center;

[0054] The first specimen was subjected to a load in air at the displacement rate required by the tensile standard until fracture, and the maximum load P was obtained. FFS ;

[0055] Based on the maximum load P FFS The critical fracture load of each specimen was obtained by performing graded loading and holding tensile tests on specimens 2 through N sequentially at a set stress rate; the critical fracture load of each specimen was determined when the difference between the critical fracture load of specimen n-1 and the critical fracture load of specimen n was not greater than 5%P. FFS When the critical fracture load of the (n-1)th specimen is smaller than the critical fracture load of the nth specimen, the critical fracture load is the threshold load; n is any natural number between 2 and N.

[0056] The critical fracture stress is calculated based on the threshold load and the cross-sectional area at the notch root.

[0057] To more clearly explain the experimental method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, the following is a detailed explanation. Figure 1 The steps in the embodiments of the present invention will be described in detail below.

[0058] The experimental method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions according to the first embodiment of the present invention is described in detail below:

[0059] Tensile specimens with transverse notches at the center of the weld joint were fabricated to obtain N specimens; all N specimens were identical; N was a natural number greater than 1; a sampling diagram is shown below. Figure 2 See the schematic diagram of the notched tensile specimen dimensions. Figure 3 ,

[0060] Calculate the root cross-sectional area of ​​the notch based on the transverse notch size of the circumferential weld joint at the weld center;

[0061] The first specimen was subjected to a load in air at the displacement rate required by the tensile standard until fracture, and the maximum load P was obtained. FFS After the test, the test gas in the environmental chamber was discharged to one atmosphere, and then the environmental chamber was opened to take out the sample.

[0062] Based on the maximum load P FFSThe critical fracture load of each specimen was obtained by performing graded loading and holding tensile tests on specimens 2 through N sequentially at a set stress rate; the critical fracture load of each specimen was determined when the difference between the critical fracture load of specimen n-1 and the critical fracture load of specimen n was not greater than 5%P. FFS At that time, the critical fracture load smaller than the critical fracture load of the (n-1)th specimen is the threshold load; n is any natural number between 2 and N; see the loading diagram. Figure 4 ;

[0063] Specifically, before performing graded loading and holding tensile tests on specimens 2 through N at a set stress rate, the following steps are taken: For specimen n, before performing the graded loading and holding tensile test, specimen n is installed on a metal material hydrogen environment compatibility testing machine. Then, through three nitrogen purgings, three hydrogen purgings, and a 10-second hydrogen convection procedure, the nitrogen or air in the temperature-controlled high-pressure environment chamber is expelled, and pure hydrogen or hydrogen-doped gas with different hydrogen partial pressures at a predetermined pressure is introduced. Subsequently, the graded loading and holding tensile test is performed.

[0064] Specifically, the method for obtaining the critical fracture load of each specimen by sequentially performing graded loading and holding tensile tests on specimens 2 to N at a set stress rate includes: using a maximum load P that is 5% of the maximum load for each load stage. FFS The load was graded into 20 levels. The first 10 levels were maintained for 2 hours each, and the subsequent 10 levels were maintained for 4 hours each. A tensile test was performed on the second specimen under load, yielding its load-time and stiffness-time curves. Based on these curves, the critical fracture load P of the second specimen was determined. th-2 Using the critical fracture load of the (n-1)th specimen, which is 5% of the load at each stage, as the load, graded loading was performed. The first 10 stages were held for 2 hours each, and subsequent stages were held for 4 hours each. Tensile tests were conducted on the nth specimen under load to obtain its load-time and stiffness-time curves. Based on these curves, the critical fracture load P of the nth specimen was determined. th-n .

[0065] The formula for calculating stiffness is: Stiffness = (F 3' -F 1' ) / |(p3-p1)|, where: F 1' and F 3' They are Figure 4 The measured loads at midpoints 1' and 3'; p1 and p3 are respectively Figure 3 Displacement at midpoints 1 and 3.

[0066] Specifically, after performing graded loading and holding tensile tests on specimens 2 to N in sequence at a set stress rate, the following steps are taken: For specimen n, after completing the graded loading and holding tensile test, the gas in the temperature-controlled high-pressure environment chamber is discharged to one atmosphere, and then purged with nitrogen three times before the environment chamber is opened and specimen n is taken out.

[0067] Specifically, in this embodiment, the critical fracture load P of the nth specimen is obtained based on the load-time curve and stiffness-time curve of the nth specimen. th-n The method is as follows: the intersection of the two linear regression descending lines of the stiffness-time curve of the nth specimen corresponds to the load at the step on the load-time curve, which is the critical fracture load P of the nth specimen. th-n Specifically, such as Figure 5 As shown, two marker lines are added to the stiffness-time curve using linear regression. Their intersection point is the transition point from yielding to cracking of the specimen. The load corresponding to the step at the transition point is the critical fracture load P of the nth specimen. th-n .

[0068] Specifically, the third specimen can also be subjected to graded loading and tensile tests with load holding, where each load level ΔP3 = 5%P th-2 Total series = P FFS / △P3, the first 10 levels each have a 2-hour load guarantee, and after level 10, each level has a 4-hour load guarantee.

[0069] Based on the data from the second specimen, the critical fracture load P of the third specimen was determined. th-3 .

[0070] Specifically, the fourth specimen can also be subjected to graded loading and tensile tests based on the third specimen, with each load grade ΔP4 = 5% P. th-3 Total series = P FFS / △P4, the first 10 levels each have a 2-hour load guarantee, and after level 10, each level has a 4-hour load guarantee.

[0071] Based on the data from the second specimen, the critical fracture load P of the fourth specimen was determined. th-4 .

[0072] If necessary, graded loading and tensile tests can be performed on specimens 5 and 6 to obtain their critical fracture load P. th-5 P th-6 ...

[0073] When the difference between the critical fracture loads determined from two consecutive specimens is ≤5% P FFS When the lower of these values ​​is determined, it is taken as the threshold load P. th .

[0074] The critical fracture stress is calculated based on the threshold load and the cross-sectional area at the notch root.

[0075] In this embodiment, the method for calculating the threshold load based on the threshold load and the cross-sectional area at the root of the notch is as follows: σ th =P th / S0;

[0076] Where, σ th P is the critical fracture stress. th Threshold load, S0 is the cross-sectional area at the root of the notch.

[0077] Preferably, the testing machine has the following functions: the ability to perform graded loading and load maintenance under high-pressure gas environment, and the ability to record load-time curves during the test. Preferably, the temperature-controlled high-pressure environment chamber is made of 304 or 316 stainless steel and can simulate the temperature and pressure environment of pure hydrogen or hydrogen-doped pipelines.

[0078] To better illustrate the test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, this application also provides an example, which specifically includes:

[0079] The first step is to form a circumferential weld joint by welding the pipe circumferentially, and then follow the steps outlined below. Figure 2 and Figure 3 A notched tensile test specimen was machined transversely to the circumferential weld joint (i.e., along the pipe axis). See the image below for the machined notched tensile test specimen. Figure 6 Calculate the cross-sectional area S0 at the root of the notch.

[0080] The second step involves loading the #0 notched tensile specimen in air at the displacement rate required by the tensile standard until fracture, and recording the maximum load P. FFS .

[0081] The third step is to exhaust the test gas in the environmental chamber to one atmosphere after the test is completed, and then open the environmental chamber to take out the sample.

[0082] The fourth step involves mounting the #1 notched tensile specimen on a hydrogen environment compatibility testing machine for metallic materials. Then, the nitrogen or air in the temperature-controlled, high-pressure environment chamber is removed through three nitrogen purgings, three hydrogen purgings, and a 10-second hydrogen convection cycle, introducing 10 MPa pure hydrogen gas. A graded loading and holding tensile test is then performed on the #1 specimen at a specific stress rate: maximum load P max =P FFS A total of 20 load levels are applied, with each level having a load ΔP1 = 5%. FFS The first 10 stages have a load-bearing capacity of 2 hours each, and the latter 10 stages have a load-bearing capacity of 4 hours each. See the loading diagram below. Figure 3 .

[0083] Step 5: After the test of specimen #1 is completed, the test gas in the environmental chamber is exhausted to one atmosphere, then purged three times with nitrogen, and the environmental chamber is opened to remove the specimen. The load-time curve and stiffness-time curve are plotted. The stiffness calculation formula is: Stiffness = (F... 3' -F 1' ) / |(p3-p1)|, where: F 1' and F 3' They are Figure 4 The measured loads at midpoints 1' and 3'; p1 and p3 are respectively Figure 4 Displacement at midpoints 1 and 3.

[0084] Step 6: Add two marker lines to the stiffness-time curve using linear regression. The intersection of these lines marks the transition point from yielding to cracking of the specimen. The load corresponding to the step at the transition point is the critical fracture load P of specimen #1. th-1 The test curve for sample #1 is shown below. Figure 7 P th-1 =70%P FFS .

[0085] Step 7: Perform graded loading and holding tensile tests on the #2 notched tensile specimen according to step (4): each load ΔP2 = 5% P th-1 Total series = P FFS / △P2, the first 10 levels each have a 2-hour load guarantee, and after level 10, each level has a 4-hour load guarantee.

[0086] Step 8: Process the data of sample #2 according to steps (5) and (6) to determine its critical fracture load P. th-2 The test curve for sample #2 is shown below. Figure 8 P th-2 =71.5% P FFS .

[0087] Step 9: Perform graded loading and holding tensile tests on the #3 notched tensile specimen according to step (4), with each load stage ΔP3 = 5% P. th-2 Total series = P FFS / △P3, the first 10 levels each have a 2-hour load guarantee, and after level 10, each level has a 4-hour load guarantee.

[0088] Step 10: Process the data of sample #3 according to steps (5) and (6) to determine its critical fracture load P. th-3 The test curve for sample #3 is shown below. Figure 9 P th-3 =70.8% P FFS .

[0089] Step 11: The difference between the critical fracture loads measured for specimens #2 and #3 is ≤5%P. FFSThe lower value of sample #3 was determined as the threshold load: P th =70.8%P FFS .

[0090] Step 12: Calculate the critical fracture stress σ th σ th =P th / S0.

[0091] Although the steps in the above embodiments are described in the above order, those skilled in the art will understand that in order to achieve the effect of this embodiment, different steps do not need to be executed in such order. They can be executed simultaneously (in parallel) or in reverse order. These simple variations are all within the protection scope of this invention.

[0092] The second embodiment of the present invention provides a test system for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, the system comprising:

[0093] The specimen processing module is used to process tensile specimens with transverse notches in the circumferential weld joint located at the center of the weld, resulting in N specimens; the N specimens are completely identical; N is a natural number greater than 1.

[0094] The area calculation module is used to calculate the cross-sectional area at the root of the notch based on the transverse notch size of the circumferential weld joint at the weld center.

[0095] The maximum load determination module is used to apply a load to the first specimen in an air environment at the displacement rate required by the tensile standard until fracture, and obtain the maximum load P. FFS ;

[0096] Threshold load calculation module, used to calculate based on maximum load P FFS The critical fracture load of each specimen is obtained by performing graded loading and holding tensile tests on specimens 2 through N sequentially at a set stress rate; the difference between the critical fracture load of specimen n-1 and the critical fracture load of specimen n is not greater than 5%P. FFS When the critical fracture load of the (n-1)th specimen is smaller than the critical fracture load of the nth specimen, the critical fracture load is the threshold load; n is any natural number between 2 and N.

[0097] The fracture stress calculation module is used to calculate the critical fracture stress based on the threshold load and the cross-sectional area at the notch root.

[0098] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process and related descriptions of the system described above can be found in the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0099] It should be noted that the test system for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions provided in the above embodiments is only an example of the division of the above functional modules. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the modules or steps in the embodiments of the present invention can be further decomposed or combined. For example, the modules in the above embodiments can be merged into one module, or further divided into multiple sub-modules to complete all or part of the functions described above. The names of the modules and steps involved in the embodiments of the present invention are only for distinguishing the various modules or steps and are not considered as an improper limitation of the present invention.

[0100] An electronic device according to a third embodiment of the present invention includes:

[0101] At least one processor; and

[0102] A memory communicatively connected to at least one of the processors; wherein,

[0103] The memory stores instructions that can be executed by the processor to implement the above-described test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions.

[0104] A fourth embodiment of the present invention provides a computer-readable storage medium storing computer instructions, which are executed by the computer to implement the above-described test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions.

[0105] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process and related descriptions of the electronic devices and storage media described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0106] Those skilled in the art will recognize that the modules and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. The programs corresponding to the software modules and method steps can be placed in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROMs, or any other form of storage medium known in the art. To clearly illustrate the interchangeability of electronic hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in electronic hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the invention.

[0107] The following is for reference. Figure 10 It shows a schematic diagram of the structure of a computer system for implementing the methods, systems, and devices of this application. Figure 10 The server shown is merely an example and should not impose any limitations on the functionality and scope of use of the embodiments of this application.

[0108] like Figure 10 As shown, the computer system includes a Central Processing Unit (CPU) 601, which can perform various appropriate actions and processes based on programs stored in Read Only Memory (ROM) 602 or programs loaded from storage section 608 into Random Access Memory (RAM) 603. The RAM 603 also stores various programs and data required for system operation. The CPU 601, ROM 602, and RAM 603 are interconnected via a bus 604. An Input / Output (I / O) interface 605 is also connected to the bus 604.

[0109] The following components are connected to I / O interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN (Local Area Network) card, modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to I / O interface 605 as needed. A removable medium 611, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 610 as needed so that computer programs read from it can be installed into storage section 608 as needed.

[0110] Specifically, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 609, and / or installed from removable medium 611. When the computer program is executed by central processing unit (CPU) 601, it performs the functions defined in the methods of this application. It should be noted that the computer-readable medium described above in this application can be a computer-readable signal medium or a computer-readable storage medium, or any combination of the two. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this application, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in connection with an instruction execution system, apparatus, or device. In this application, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on a computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0111] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0112] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0113] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0114] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0115] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, characterized in that, The method includes: Tensile specimens with transverse notches at the center of the weld joint are processed to obtain N specimens; the N specimens are completely identical; N is a natural number greater than 1. Calculate the root cross-sectional area of ​​the notch based on the transverse notch size of the circumferential weld joint at the weld center; The first specimen was subjected to a load in air at the displacement rate required by the tensile standard until fracture, and the maximum load P was obtained. FFS ; Based on the maximum load PFFS, graded loading and holding tensile tests were performed on specimens 2 through N at a set stress rate to obtain the critical fracture load of each specimen; the critical fracture load of specimen n-1 was determined when the difference between the critical fracture load of specimen n and the critical fracture load of specimen n was not greater than 5%P. FFS When the critical fracture load of the (n-1)th specimen is smaller than the critical fracture load of the nth specimen, the critical fracture load is the threshold load; n is any natural number between 2 and N. The critical fracture stress is calculated based on the threshold load and the cross-sectional area at the notch root.

2. The test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions according to claim 1, characterized in that, The method for obtaining the critical fracture load of each specimen by sequentially performing graded loading and tensile tests on specimens 2 to N at a set stress rate includes: With each load level being 5% of the maximum load P FFS The load was graded into 20 levels. The first 10 levels were maintained for 2 hours each, and the subsequent 10 levels were maintained for 4 hours each. A tensile test was performed on the second specimen under load, yielding its load-time and stiffness-time curves. Based on these curves, the critical fracture load P of the second specimen was determined. th-2 ; Using the critical fracture load of the (n-1)th specimen, which is 5% of the load at each stage, as the load, graded loading was performed. The first 10 stages were held for 2 hours each, and subsequent stages were held for 4 hours each. Load-hold tensile tests were conducted on the nth specimen to obtain its load-time and stiffness-time curves. Based on these curves, the critical fracture load P of the nth specimen was determined. th-n .

3. The test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions according to claim 2, characterized in that, Before performing graded loading and holding tensile tests on specimens 2 through N at a set stress rate, the following steps are included: For the nth specimen, before the graded loading and holding tensile test, the nth specimen is installed on the metal material hydrogen environment compatibility tester. Then, the nitrogen or air in the temperature-controlled high-pressure environment chamber is driven away by three nitrogen purgings, three hydrogen purgings, and a 10-second hydrogen convection program. Pure hydrogen or hydrogen-doped gas with different hydrogen partial pressures at a predetermined pressure is introduced, followed by the graded loading and holding tensile test.

4. The test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions according to claim 2, characterized in that, After performing graded loading and holding tensile tests on specimens 2 through N sequentially at a set stress rate, the following steps were taken: For the nth specimen, after completing the stage loading and tensile test, the gas in the temperature-controlled high-pressure environment chamber is discharged to one atmosphere, and then purged with nitrogen three times before the environment chamber is opened and the nth specimen is taken out.

5. The test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions according to claim 4, characterized in that, The critical fracture load P of the nth specimen is obtained based on the load-time curve and stiffness-time curve of the nth specimen. th-n The method is as follows: The intersection of the two linear regression descending lines of the stiffness-time curve for the nth specimen corresponds to the load at the step on the load-time curve, which is the critical fracture load P of the nth specimen. th-n .

6. The test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions according to claim 5, characterized in that, The method for calculating the threshold load based on the threshold load and the cross-sectional area at the root of the notch is as follows: σ th =P th / S0; Where, σ th P is the critical fracture stress. th Threshold load, S0 is the cross-sectional area at the root of the notch.

7. A test system for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, characterized in that, The system includes: The specimen processing module is used to process tensile specimens with transverse notches in the circumferential weld joint located at the center of the weld, resulting in N specimens; the N specimens are completely identical; N is a natural number greater than 1. The area calculation module is used to calculate the cross-sectional area at the root of the notch based on the transverse notch size of the circumferential weld joint at the weld center. The maximum load determination module is used to apply a load to the first specimen in an air environment at the displacement rate required by the tensile standard until fracture, and obtain the maximum load P. FFS ; The threshold load calculation module is used to obtain the critical fracture load of each specimen by performing graded loading and holding tensile tests on specimens 2 to N sequentially at a set stress rate based on the maximum load PFFS. The critical fracture load is determined when the difference between the critical fracture load of specimen n-1 and the critical fracture load of specimen n is no greater than 5%P. FFS When the critical fracture load of the (n-1)th specimen is smaller than the critical fracture load of the nth specimen, the critical fracture load is the threshold load; n is any natural number between 2 and N. The fracture stress calculation module is used to calculate the critical fracture stress based on the threshold load and the cross-sectional area at the notch root.

8. An electronic device, characterized in that, include: At least one processor; And a memory communicatively connected to at least one of the processors; wherein the memory stores instructions executable by the processor to implement the test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that are executed by the computer to implement the test method for determining the critical fracture stress of a pipe ring weld joint under hydrogen conditions, as described in any one of claims 1-6.

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