A method and system for predicting the fracture toughness of weld zones
By establishing a fracture toughness prediction model and combining the microstructure information and mechanical property tests of the weld area specimen, the problem of inaccurate prediction of weld area fracture toughness in the existing technology is solved, and efficient and simple weld safety evaluation is achieved.
Patent Information
- Application Number
- CN202311502128.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-10
- Publication Date
- 2025-10-28
- Estimated Expiration
- 2043-11-10
AI Technical Summary
Existing technologies cannot accurately predict the fracture toughness of different microstructure regions in the weld zone of pipelines, resulting in inaccurate evaluation of the service safety of the weld zone. Furthermore, existing methods are complex or difficult to promote.
A fracture toughness prediction model incorporating crack propagation tortuosity was established. By acquiring micro-region information of different microstructures in the weld zone sample, heat treatment was performed using the same steel grade material, mechanical properties were tested, crack propagation morphology was measured, and the results were input into the fracture toughness prediction model to predict the fracture toughness of different micro-regions.
It enables efficient and concise prediction of fracture toughness of different micro-regions in the weld zone at different temperatures, thus improving the accuracy of weld safety evaluation.
Smart Images
Figure CN119985901B_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of pipeline inspection and evaluation technology, and in particular to a method and system for predicting the fracture toughness of weld zones. Background Technology
[0002] In recent years, accidents caused by cracking in pipeline weld zones have occurred frequently. In the service safety evaluation of weld zones of metal pipelines, fracture toughness is one of the input parameters in the safety evaluation model, and its accuracy is crucial to the evaluation results of metal pipeline welds.
[0003] Currently, the fracture toughness of materials is mainly obtained through two methods: experimentation and numerical simulation. Experimentation is one method, which is further divided into the multi-sample method and the single-sample method. The multi-sample method requires a large number of samples to obtain a single fracture toughness value, is time-consuming, and results in significant numerical dispersion. The single-sample compliance method involves multiple loading / unloading cycles on a single sample to obtain the fracture toughness resistance curve. This method involves test compliance correction, crack propagation size calculation, and derivation of the fracture toughness formula, requiring a strong theoretical foundation and complex calculation process, making it difficult to generalize.
[0004] Furthermore, regardless of whether it's the single-sample method or the multi-sample method, for weld zone specimens, since the entire weld zone typically contains different micro-regions with different microstructures such as the weld zone, coarse-grained fusion zone, and fine-grained fusion zone, the obtained experimental data can only qualitatively characterize the overall fracture toughness of the weld zone, and cannot accurately describe the fracture toughness of a specific micro-region within the weld zone. Secondly, using finite element analysis or even molecular dynamics to simulate the microstructure and atomic-scale behavior of materials can yield stress distribution, deformation, and fracture toughness indicators for materials with different microstructures at different temperatures. However, this method involves a high level of expertise and is more difficult to implement.
[0005] Currently, existing technologies typically do not consider the influence of microstructure in different regions of the weld zone on fracture toughness, and no quantitative prediction method applicable to fracture toughness in different microstructure regions has been established domestically or internationally, making it impossible to achieve accurate safety assessment of the weld zone. Therefore, how to predict the fracture toughness of weld zones with different microstructures based on a single sample using a simple and reliable method is crucial in the service safety assessment of pipeline weld zones. Summary of the Invention
[0006] The purpose of this disclosure is to provide a method and system for predicting the fracture toughness of weld zone regions, so as to achieve accurate and efficient prediction of the fracture toughness of different microstructure regions in the weld zone.
[0007] To achieve the above objectives, this disclosure provides a method for predicting the fracture toughness of weld zones, comprising:
[0008] Establish a fracture toughness prediction model that includes crack propagation tortuosity;
[0009] Information on different micro-regions of the weld area sample was obtained, and heat treatment was performed on the same steel grade material for different micro-regions to obtain test blocks with different micro-regions.
[0010] Mechanical properties of micro-region specimens with different microstructures were tested, and crack propagation morphology related to fracture toughness was obtained for the micro-region specimens with different microstructures.
[0011] Based on the crack propagation morphology of the micro-region specimens with different microstructures, information is measured and calculated to obtain the crack propagation tortuosity of the micro-region specimens with different microstructures. This information is then input into the fracture toughness prediction model to predict the fracture toughness of the micro-region specimens with different microstructures. Finally, the predicted distribution of fracture toughness of the micro-regions with different microstructures in the entire weld area specimen is obtained.
[0012] Furthermore, a fracture toughness prediction model incorporating crack propagation tortuosity is established, including:
[0013] Based on the theory of linear elastic fracture mechanics, a fracture toughness model is obtained according to the size of the plastic zone at the crack tip and the tortuosity of crack propagation.
[0014] Based on the fracture toughness model and the fracture toughness relationship model under plane strain conditions, the fracture toughness prediction model is established.
[0015] Furthermore, the fracture toughness model is as follows:
[0016] ,
[0017] Where, E represents fracture toughness, and E represents the elastic modulus. Indicates the amount of uniform deformation. Indicates the size of the plastic zone at the crack tip. Represents the linear length of crack propagation. Represents Poisson's ratio. Indicates the tortuosity of crack propagation;
[0018] The fracture toughness relationship model under the plane strain condition is as follows:
[0019] ,
[0020] Where, This represents the fracture toughness under plane strain conditions. Indicates the yield strength of the material;
[0021] The fracture toughness prediction model is as follows:
[0022] .
[0023] Furthermore, information on different micro-regions of the weld zone specimen was obtained, and for each different micro-region, heat treatment was performed using the same steel grade material to obtain specimens with different micro-regions, including:
[0024] Metallographic specimens of the weld joint, including the entire weld area, were cut and observed using a metallographic microscope to obtain the microstructure and grain size of the weld area, coarse-grained heat-affected zone, and fine-grained heat-affected zone.
[0025] For the weld zone, coarse-grained heat-affected zone, and fine-grained heat-affected zone, heat treatment was performed using the same steel grade material to obtain weld zone specimens, coarse-grained heat-affected zone specimens, and fine-grained heat-affected zone specimens with the same microstructure and grain size.
[0026] Among them, the different micro-regions of the weld zone sample include: weld zone, coarse grain heat-affected zone and fine grain heat-affected zone.
[0027] Furthermore, the mechanical properties of micro-region specimens with different microstructures were tested, and the crack propagation morphology related to fracture toughness of the micro-region specimens with different microstructures was obtained, including:
[0028] Different tissue micro-region specimens were processed to obtain standard tensile specimens and fracture toughness specimens for each tissue micro-region specimen.
[0029] The standard tensile specimen is subjected to standard tensile property tests to obtain the yield strength and uniform deformation of the standard tensile specimen.
[0030] The fracture toughness specimen was subjected to a standard fracture toughness test to obtain the size of the plastic zone at the crack tip and the fracture surface section of the fracture toughness specimen.
[0031] Based on the fracture cross section of the fracture toughness specimen, a fracture cross section specimen is prepared and observed using an optical microscope to obtain the crack propagation morphology of the fracture toughness specimen.
[0032] The mechanical property tests include tensile property tests and fracture toughness tests.
[0033] Furthermore, information on the crack propagation morphology of the fracture toughness specimen is measured to obtain the linear crack length and actual crack length of each micro-region specimen.
[0034] The crack propagation tortuosity of the corresponding micro-region specimen is calculated by using the linear crack length and the actual crack length of each micro-region specimen.
[0035] The crack propagation tortuosity, yield strength, uniform deformation, crack tip plastic zone size, and crack linear length of the micro-region specimens with different microstructures are input into the fracture toughness prediction model to obtain the fracture toughness prediction value of the corresponding micro-region specimen, that is, to obtain the fracture toughness prediction value of the micro-region corresponding to the weld area specimen.
[0036] Furthermore, information is measured based on the crack propagation morphology of the micro-region specimens with different microstructures to obtain the linear crack length and actual crack length of each micro-region specimen, including:
[0037] The fracture cross-section specimens of different micro-regions were observed using an optical microscope, and multiple fields of view were measured to obtain multiple initial crack linear lengths and multiple initial crack actual lengths for each micro-region specimen. The average values were then calculated to obtain the crack linear length and crack actual length for each micro-region specimen.
[0038] Furthermore, when performing tensile property tests and fracture toughness tests on standard tensile specimens and fracture toughness specimens respectively, tests are conducted at different temperatures to obtain the yield strength, uniform deformation, size of the plastic zone at the crack tip, fracture cross section, and crack propagation morphology at different temperatures.
[0039] By measuring and calculating the information of the crack propagation morphology, the linear length of the crack, the actual length of the crack, and the crack propagation tortuosity of the micro-region specimens with different structures at different temperatures were obtained.
[0040] The crack propagation tortuosity, yield strength, uniform deformation, crack tip plastic zone size, and crack linear length of micro-region specimens with different microstructures at different temperatures are input into the fracture toughness prediction model to obtain the corresponding fracture toughness prediction values of the micro-region specimens at different temperatures.
[0041] Based on the same inventive concept, this disclosure also provides a prediction system for the fracture toughness of weld zones, comprising:
[0042] Establish model units to build a fracture toughness prediction model that includes crack propagation tortuosity;
[0043] The heat treatment unit is used to obtain information on different micro-regions of the weld area sample and to perform heat treatment on different micro-regions using the same steel grade material to obtain test blocks with different micro-regions.
[0044] The test acquisition unit is used to test the mechanical properties of micro-region specimens with different structures, and obtain the crack propagation morphology related to fracture toughness of micro-region specimens with different structures.
[0045] The prediction unit is used to measure and calculate information based on the crack propagation morphology of the micro-region specimens with different microstructures, obtain the crack propagation tortuosity of the micro-region specimens with different microstructures, and input it into the fracture toughness prediction model to predict the fracture toughness of the micro-region specimens with different microstructures, and finally obtain the predicted distribution of fracture toughness of different micro-regions of the entire weld area specimen.
[0046] Based on the same inventive concept, embodiments of the present invention also provide an electronic device, including: a memory and a processor; the processor is used to read and execute a computer program stored in the memory to implement the aforementioned method for predicting the fracture toughness of weld zones.
[0047] Based on the same inventive concept, embodiments of the present invention also provide a computer storage medium storing computer-executable instructions, which, when executed, implement the aforementioned method for predicting the fracture toughness of weld zones.
[0048] The technical effects and advantages of this disclosure are as follows: Taking into account the influence of intrinsic fracture resistance and extrinsic fracture resistance on the fracture toughness of different microstructure regions in the weld zone, a fracture toughness prediction model based on the tensile properties of the weld zone and the crack propagation tortuosity is established. Through efficient and simple methods and means, the fracture toughness of different microstructure regions in the weld zone at different temperatures can be predicted, which can provide more accurate data for weld safety evaluation, thereby improving the accuracy of the evaluation.
[0049] Other features and advantages of this disclosure will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the disclosure. The objects and other advantages of this disclosure may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description
[0050] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0051] Figure 1 This invention discloses a method for predicting the fracture toughness of weld zones according to an embodiment of the present invention.
[0052] Figure 2 This is a schematic diagram illustrating the tensile properties of the weld zone in an embodiment of this disclosure;
[0053] Figure 3 This is a schematic diagram showing the actual length and linear length of crack propagation in the weld zone in an embodiment of this disclosure;
[0054] Figure 4 This is a schematic diagram comparing the crack propagation paths in the weld zone at different temperatures in the embodiments of this disclosure;
[0055] Figure 5 This is a schematic diagram comparing the predicted and measured values of fracture toughness in the weld zone at different temperatures in an embodiment of this disclosure.
[0056] Figure 6 This is a schematic diagram of a prediction system for the fracture toughness of weld zones according to an embodiment of the present disclosure;
[0057] Figure 7 This is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. Detailed Implementation
[0058] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.
[0059] To address the shortcomings of existing technologies, this disclosure provides a method for predicting the fracture toughness of weld zones, such as... Figure 1 As shown, it includes the following steps:
[0060] Step S1: Establish a fracture toughness prediction model that includes crack propagation tortuosity, specifically including:
[0061] Based on the theory of linear elastic fracture mechanics, and according to the size of the plastic zone at the crack tip (i.e., crack propagation resistance) and the crack propagation tortuosity (i.e., crack propagation path), the fracture toughness model is obtained as follows:
[0062] (1),
[0063] Where, E represents fracture toughness, and E represents the elastic modulus. Indicates the amount of uniform deformation. Indicates the size of the plastic zone at the crack tip. Represents the linear length of crack propagation. Represents Poisson's ratio. This indicates the degree of tortuosity in crack propagation.
[0064] Based on the fracture toughness model and the fracture toughness relationship model under plane strain conditions, the fracture toughness prediction model is established.
[0065] The fracture toughness relationship model under plane strain conditions is as follows:
[0066] (2),
[0067] In the formula, This represents the fracture toughness under plane strain conditions. Indicates the yield strength of the material. This represents fracture toughness, and E represents the elastic modulus, with a value of 210 GPa. This represents Poisson's ratio, with a value of 0.3.
[0068] Combining formulas (1) and (2), the fracture toughness prediction model is obtained as follows:
[0069] (3),
[0070] In the formula, Indicates fracture toughness. Indicates the amount of uniform deformation. Indicates the size of the plastic zone at the crack tip. Represents the linear length of crack propagation. Indicates the tortuosity of crack propagation. This indicates the yield strength of the material.
[0071] Step S2: Obtain microstructure information of different microregions in the weld area sample, and perform heat treatment on different microregions using the same steel grade material to obtain corresponding microstructure specimens; specifically including:
[0072] Metallographic specimens of the weld joint containing the entire weld area were cut and observed using a metallographic microscope to obtain the microstructure and grain size of the weld area, coarse-grained heat-affected zone, and fine-grained heat-affected zone, as well as the microstructure and grain size of these three micro-regions.
[0073] For the weld zone, coarse-grained heat-affected zone, and fine-grained heat-affected zone, heat treatment was performed using the same steel grade material to obtain weld zone specimens, coarse-grained heat-affected zone specimens, and fine-grained heat-affected zone specimens respectively.
[0074] Among them, the different micro-regions of the weld zone sample include: weld zone, coarse grain heat-affected zone and fine grain heat-affected zone.
[0075] It is important to note that the size of the test block should be sufficient to produce at least the number of specimens required for both the tensile test and the fracture toughness test.
[0076] Step S3: Test the mechanical properties of micro-region specimens with different microstructures to obtain the crack propagation morphology related to fracture toughness for each micro-region specimen; specifically including:
[0077] Step S301: Process the micro-region specimens of different tissues to obtain standard tensile specimens and fracture toughness specimens for each type of micro-region specimen; perform standard tensile property tests on the standard tensile specimens, such as... Figure 2 As shown, the yield strength and uniform deformation of the standard tensile specimen are obtained; a standard fracture toughness test is performed on the fracture toughness specimen to obtain the size of the plastic zone at the crack tip and the fracture surface section. Specifically:
[0078] Different micro-region specimens were sampled and processed into standard tensile specimens in the shape of round bars. The standard tensile specimens had a diameter of 8 mm and a gauge length of 40 mm. The standard tensile specimens were placed on a tensile testing machine, and the temperature was controlled by an environmental chamber. In this embodiment, liquid nitrogen was used to control the temperature. According to the standard GB / T228.1-2021, the standard tensile specimens were subjected to tensile performance tests at different temperatures to obtain the yield strength and uniform deformation of the standard tensile specimens at different temperatures.
[0079] Similarly, samples from different micro-regions were processed into fracture toughness specimens. The fracture toughness specimens were 60 mm long, 5 mm thick, and 10 mm wide. The fracture toughness specimens were placed on an MTS testing machine, and the temperature was controlled by an environmental chamber. In this embodiment, liquid nitrogen was used to control the temperature. The fracture toughness specimens were subjected to fracture toughness tests at different temperatures in accordance with the standard GB / T21143-2014 to obtain the size of the plastic zone at the crack tip and the fracture surface section of the fracture toughness specimens at different temperatures.
[0080] It is important to note that when performing tensile property tests and fracture toughness tests on standard tensile specimens and fracture toughness specimens respectively, the test temperature should remain consistent for both tests each time the test temperature is changed.
[0081] Step S302: Based on the fracture surface section of the fracture toughness specimen at different temperatures, prepare a fracture surface section specimen and observe it using an optical microscope to obtain the crack propagation morphology of the corresponding fracture surface section specimen at different temperatures. Specifically:
[0082] A 10×10×2mm thin slice was taken near the fracture section of the fracture toughness specimen. After polishing with metallographic sandpaper, it was mechanically polished with 1.5μm diamond polishing paste, followed by electrolytic polishing. After polishing, the fracture toughness specimen was rinsed with ethanol solution, dried, and then the fracture section specimen was placed under an optical microscope to obtain the crack propagation morphology.
[0083] The specific conditions for electropolishing are: voltage of 35V, time of 40s, and electrolyte of 4% perchloric acid and ethanol solution.
[0084] Step S4: Measure and calculate the crack propagation morphology of the crack toughness specimens of different micro-regions at different temperatures to obtain the crack propagation tortuosity of the specimens of different micro-regions at different temperatures, and input the data into the fracture toughness prediction model to predict the fracture toughness of the specimens of different micro-regions at different temperatures. In other words, the predicted distribution of fracture toughness of different micro-regions of the entire weld area specimen at different temperatures is finally obtained.
[0085] Step S401 involves measuring and calculating the crack propagation morphology of crack toughness specimens with different microstructures at different temperatures to obtain the crack propagation tortuosity of the specimens with different microstructures at different temperatures, including:
[0086] Observation was performed using an optical microscope, and measurements were taken at five fields of view of fracture cross-section specimens from different micro-regions at each temperature. Multiple initial crack linear lengths and multiple initial crack actual lengths were obtained for each micro-region specimen at each temperature, and their average values were calculated. This yielded the linear crack length and actual crack length for each micro-region specimen at each temperature. Figure 3 As shown.
[0087] Step S402: Calculate the crack propagation tortuosity of the corresponding micro-region specimen at different temperatures using the linear crack length and actual crack length of each micro-region specimen at different temperatures.
[0088] The crack propagation tortuosity, yield strength, uniform deformation, crack tip plastic zone size, and crack linear length of micro-region specimens with different microstructures at different temperatures are input into the fracture toughness prediction model to obtain the fracture toughness prediction values of the corresponding micro-region specimens at different temperatures, that is, to obtain the fracture toughness prediction values of the corresponding micro-regions of the weld area specimens at different temperatures.
[0089] The predicted fracture toughness value of each microstructure microregion specimen can represent the predicted fracture toughness value of the microstructure microregion of the weld zone specimen with the same microstructure. Furthermore, by comparing the measured and predicted fracture toughness values of different microstructure microregions of the weld zone specimen, such as... Figure 5 As shown, the maximum error in this embodiment is less than 8%, meaning that the prediction method disclosed herein has high accuracy.
[0090] Based on the same inventive concept, this disclosure also provides a system for predicting the fracture toughness of weld zones, such as... Figure 6 As shown, it includes:
[0091] Establish model units to build a fracture toughness prediction model that includes crack propagation tortuosity;
[0092] The heat treatment unit is used to obtain information on different micro-regions of the weld area sample and to perform heat treatment on different micro-regions using the same steel grade material to obtain test blocks with different micro-regions.
[0093] The test acquisition unit is used to test the mechanical properties of micro-region specimens with different structures, and obtain the crack propagation morphology related to fracture toughness of micro-region specimens with different structures.
[0094] The prediction unit is used to measure and calculate information based on the crack propagation morphology of the micro-region specimens with different microstructures, obtain the crack propagation tortuosity of the micro-region specimens with different microstructures, and input it into the fracture toughness prediction model to predict the fracture toughness of the micro-region specimens with different microstructures, and finally obtain the predicted distribution of fracture toughness of different micro-regions of the entire weld area specimen.
[0095] Regarding the system in the above embodiments, the specific manner in which each unit module performs operations has been described in detail in the embodiments related to the method, and will not be elaborated here.
[0096] Based on the same inventive concept, this disclosure also provides an electronic device, the structure of which is as follows: Figure 7 As shown, it includes: a memory and a processor, wherein the processor is used to read and execute the computer program stored in the memory to implement the aforementioned method for predicting the fracture toughness of weld zones.
[0097] Based on the same inventive concept, this disclosure also provides a computer storage medium storing computer-executable instructions, which, when executed, implement the aforementioned method for predicting the fracture toughness of weld zones.
[0098] Finally, it should be noted that the above description is only a preferred embodiment of this disclosure and is not intended to limit this disclosure. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.
Claims
1. A method for predicting the fracture toughness of weld zones, characterized in that, include: Establish a fracture toughness prediction model that includes crack propagation tortuosity; Information on different micro-regions of the weld area sample was obtained, and heat treatment was performed on the same steel grade material for different micro-regions to obtain test blocks with different micro-regions. Mechanical properties of micro-region specimens with different microstructures were tested, and crack propagation morphology related to fracture toughness was obtained for the micro-region specimens with different microstructures. Information is measured and calculated based on the crack propagation morphology of the micro-region specimens with different microstructures to obtain the crack propagation tortuosity of the micro-region specimens with different microstructures, and input into the fracture toughness prediction model to predict the fracture toughness of the micro-region specimens with different microstructures, and finally obtain the predicted distribution of fracture toughness of different micro-regions of the entire weld area sample. The establishment of a fracture toughness prediction model that includes crack propagation tortuosity includes: Based on the theory of linear elastic fracture mechanics, a fracture toughness model is obtained according to the size of the plastic zone at the crack tip and the tortuosity of crack propagation; based on the fracture toughness model and the fracture toughness relationship model under plane strain conditions, the fracture toughness prediction model is established. The fracture toughness model is as follows: ， In the formula, E represents fracture toughness, and E represents the elastic modulus. Indicates the amount of uniform deformation. Indicates the size of the plastic zone at the crack tip. Represents the linear length of crack propagation. Represents Poisson's ratio. Indicates the tortuosity of crack propagation; in, The fracture toughness relationship model under the plane strain condition is as follows: ， Where, This represents the fracture toughness under plane strain conditions. Indicates the yield strength of the material; The fracture toughness prediction model is as follows: 。 2. The method for predicting the fracture toughness of weld zones according to claim 1, characterized in that, Information on different microstructures of the weld zone samples was obtained, and for each microstructure, heat treatment was performed using the same steel grade material to obtain corresponding microstructure specimens, including: Metallographic specimens of the weld joint, including the entire weld area, were cut and observed using a metallographic microscope to obtain the microstructure and grain size of the weld area, coarse-grained heat-affected zone, and fine-grained heat-affected zone. For the weld zone, coarse-grained heat-affected zone, and fine-grained heat-affected zone, heat treatment was performed using the same steel grade material to obtain weld zone specimens, coarse-grained heat-affected zone specimens, and fine-grained heat-affected zone specimens with the same microstructure and grain size. Among them, the different micro-regions of the weld zone sample include: weld zone, coarse grain heat-affected zone and fine grain heat-affected zone.
3. The method for predicting the fracture toughness of weld zones according to claim 1, characterized in that, Mechanical properties were tested on micro-region specimens with different microstructures, and the crack propagation morphology related to fracture toughness was obtained for the micro-region specimens with different microstructures, including: Different tissue micro-region specimens were processed to obtain standard tensile specimens and fracture toughness specimens for each tissue micro-region specimen. The standard tensile specimen is subjected to standard tensile property tests to obtain the yield strength and uniform deformation of the standard tensile specimen. The fracture toughness specimen was subjected to a standard fracture toughness test to obtain the size of the plastic zone at the crack tip and the fracture surface section of the fracture toughness specimen. Based on the fracture cross section of the fracture toughness specimen, a fracture cross section specimen is prepared and observed using an optical microscope to obtain the crack propagation morphology of the fracture toughness specimen. The mechanical property tests include tensile property tests and fracture toughness tests.
4. The method for predicting the fracture toughness of weld zones according to claim 3, characterized in that, The crack propagation morphology of the fracture toughness specimen was measured to obtain the linear crack length and actual crack length of each micro-region specimen. The crack propagation tortuosity of the corresponding micro-region specimen is calculated by using the linear crack length and the actual crack length of each micro-region specimen. The crack propagation tortuosity, yield strength, uniform deformation, crack tip plastic zone size, and crack linear length of the micro-region specimens with different microstructures are input into the fracture toughness prediction model to obtain the fracture toughness prediction value of the corresponding micro-region specimen, that is, to obtain the fracture toughness prediction value of the micro-region corresponding to the weld area specimen.
5. The method for predicting the fracture toughness of weld zones according to claim 4, characterized in that, Based on the crack propagation morphology of micro-region specimens with different microstructures, information is measured to obtain the linear crack length and actual crack length of each micro-region specimen, including: The fracture cross-section specimens of different micro-regions were observed using an optical microscope, and multiple fields of view were measured to obtain multiple initial crack linear lengths and multiple initial crack actual lengths for each micro-region specimen. The average values were then calculated to obtain the crack linear length and crack actual length for each micro-region specimen.
6. A method for predicting the fracture toughness of weld zones according to claim 4 or 5, characterized in that, When performing tensile property tests and fracture toughness tests on standard tensile specimens and fracture toughness specimens respectively, tests are conducted at different temperatures to obtain the yield strength, uniform deformation, size of the plastic zone at the crack tip, fracture cross section, and crack propagation morphology at different temperatures. By measuring and calculating the information of the crack propagation morphology, the linear length of the crack, the actual length of the crack, and the crack propagation tortuosity of the micro-region specimens with different structures at different temperatures were obtained. The crack propagation tortuosity, yield strength, uniform deformation, crack tip plastic zone size, and crack linear length of micro-region specimens with different microstructures at different temperatures are input into the fracture toughness prediction model to obtain the corresponding fracture toughness prediction values of the micro-region specimens at different temperatures.
7. A prediction system for the fracture toughness of weld zones, characterized in that, include: Establish model units to build a fracture toughness prediction model that includes crack propagation tortuosity; The heat treatment unit is used to obtain information on different micro-regions of the weld area sample and to perform heat treatment on different micro-regions using the same steel grade material to obtain test blocks with different micro-regions. The test acquisition unit is used to test the mechanical properties of micro-region specimens with different structures, and obtain the crack propagation morphology related to fracture toughness of micro-region specimens with different structures. The prediction unit is used to measure and calculate information based on the crack propagation morphology of the micro-region specimens with different microstructures, obtain the crack propagation tortuosity of the micro-region specimens with different microstructures, and input it into the fracture toughness prediction model to predict the fracture toughness of the micro-region specimens with different microstructures, and finally obtain the predicted distribution of fracture toughness of different micro-regions of the entire weld area specimen. Specifically, the model unit is used to: obtain a fracture toughness model based on the linear elastic fracture mechanics theory, according to the size of the plastic zone at the crack tip and the tortuosity of crack propagation; and establish the fracture toughness prediction model based on the fracture toughness model and the fracture toughness relationship model under plane strain conditions. in, The fracture toughness model is as follows: ， Where, E represents fracture toughness, and E represents the elastic modulus. Indicates the amount of uniform deformation. Indicates the size of the plastic zone at the crack tip. Represents the linear length of crack propagation. Represents Poisson's ratio. Indicates the tortuosity of crack propagation; The fracture toughness relationship model under the plane strain condition is as follows: ， Where, This represents the fracture toughness under plane strain conditions. Indicates the yield strength of the material; The fracture toughness prediction model is as follows: 。 8. An electronic device, wherein, include: Memory, processor; The processor is configured to read and execute the computer program stored in the memory to implement the method for predicting the fracture toughness of weld zones as described in any one of claims 1-6.
9. A computer-readable storage medium, wherein, The computer-readable storage medium stores computer-executable instructions, which, when executed, implement the method for predicting the fracture toughness of weld zones as described in any one of claims 1-6.
Citation Information
Patent Citations
TC18 titanium alloy basketweave microstructure fracture toughness prediction method
CN105651603A
Method and apparatus for dynamically and safely determining corrosive defects inside conveying pipeline
CN107063991A