Conversion method and device for obtaining fracture toughness of pipeline steel from impact toughness of pipeline steel

Abstract

The invention discloses a conversion method and device for obtaining the fracture toughness of pipeline steel from the impact toughness of the pipeline steel, and relates to the technical field of structure evaluation, and the method is characterized by comprising the following steps: obtaining a plurality of existing Charpy impact energy values of the pipeline steel; respectively classifying the plurality of Charpy impact energy values into corresponding preset scenes according to a plurality of preset scenes; converting each Charpy impact energy value, and determining fracture toughness value distribution based on the main curve; converting the fracture toughness value into an elastic-plastic fracture parameter, and establishing a toughness conversion model for converting the Charpy impact energy value into the elastic-plastic fracture parameter; and predicting the fracture toughness value of the target pipeline steel by using the toughness conversion model. Through the conversion method, data of impact toughness and fracture toughness can be associated, the fracture toughness value can be predicted conveniently, the accuracy of the obtained fracture toughness value is improved, the service condition of the pipeline steel can be analyzed more accurately, and integrity evaluation of the pipeline steel can be carried out accurately and effectively.

Description

Technical Field

[0001] The present invention relates to the technical field of structural evaluation, and particularly relates to a conversion method and device for obtaining the fracture toughness of pipeline steel from its impact toughness. Background Art

[0002] This section aims to provide background or context for the embodiments described in the claims. The descriptions herein are not admitted to be prior art merely by virtue of being included in this section.

[0003] Fracture toughness is one of the important material properties of pipeline steel. Generally, fracture mechanics tests are used to obtain the fracture toughness of materials, and fracture toughness data processing is usually based on the master curve method at the reference temperature T0. However, in the field of high-strength pipeline steel, the research and application related to the master curve method are less.

[0004] The Charpy impact energy value CVN and the crack tip opening displacement CTOD are the most commonly used material toughness characterization parameters in engineering at present, and they are also the parameters recommended in ASTM E1291 standard that can be used to determine the reference temperature T0. Among them, the CVN impact absorption energy needs to be converted into an equivalent stress intensity factor through an empirical formula for fracture toughness characterization. The forms of such conversion formulas are diverse, and their conservativeness, accuracy, and applicability are different, and their applications in the girth welds of X80 pipeline steel are worthy of further research.

[0005] For the oil and gas pipelines that have been in service in China for many years, only impact toughness tests were carried out on the toughness characterization of pipeline steel and welds during the construction period, and there is a lack of fracture toughness-related data. However, according to the actual working conditions of oil and gas pipelines, fracture toughness can better reflect the true toughness of pipeline steel. In addition, during the integrity evaluation of the pipeline during its later operation, the fracture toughness parameters of pipeline steel need to be input. Due to the lack of relevant data during the construction period, the same fracture toughness parameters are adopted for pipelines of the same steel grade, which cannot truly reflect the toughness conditions of different pipeline steels, and thus the pipeline integrity evaluation cannot be effectively carried out. Summary of the Invention

[0006] In view of the above technical problems, the present invention provides a conversion method and device for obtaining the fracture toughness of pipeline steel from its impact toughness, which can connect the data of impact toughness and fracture toughness, facilitate the prediction of fracture toughness values, improve the accuracy of the obtained fracture toughness values, and thus more accurately analyze the service conditions of pipeline steel and accurately and effectively carry out the integrity evaluation of pipeline steel.

[0007] To solve the above technical problems, the technical solutions adopted by the present invention include four aspects.

[0008] In the first aspect, a conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness is provided, including the following steps:

[0009] Obtain several existing Charpy impact energy values of pipeline steel;

[0010] Classify several Charpy impact energy values into corresponding preset scenarios according to several preset scenarios respectively;

[0011] Convert each Charpy impact energy value according to the conversion method under its corresponding preset scenario, and determine the distribution of fracture toughness values based on the master curve;

[0012] Convert the fracture toughness value into an elastoplastic fracture parameter, and establish a toughness conversion model for converting the Charpy impact energy value into an elastoplastic fracture parameter;

[0013] Use the toughness conversion model to predict the fracture toughness value of the target pipeline steel.

[0014] In some embodiments, the preset scenarios include a low Charpy impact energy value scenario and a high Charpy impact energy value scenario; the low Charpy impact energy value scenario is that the Charpy impact energy value is within a preset range; the high Charpy impact energy value scenario is that the Charpy impact energy value is greater than a preset threshold;

[0015] The classifying several Charpy impact energy values into corresponding preset scenarios according to several preset scenarios respectively includes:

[0016] Compare each of the Charpy impact energy values with the preset range and the preset threshold in turn;

[0017] When the Charpy impact energy value is within the preset range, classify the Charpy impact energy value into the low Charpy impact energy value scenario;

[0018] When the Charpy impact energy value is greater than the preset threshold, classify the Charpy impact energy value into the high Charpy impact energy value scenario.

[0019] In some embodiments, the fracture toughness value is denoted as K JC ; when the Charpy impact energy value satisfies the low Charpy impact energy value scenario, the conversion formula for converting the Charpy impact energy value into the fracture toughness distribution is:

[0020]

[0021] In the formula, B is the thickness of the impact test specimen; C V is the minimum Charpy impact energy value at the test temperature; Kmat is the critical stress intensity factor, that is, it represents K JC ;

[0022] When the Charpy impact energy value satisfies the high Charpy impact energy value scenario, use the master curve method to convert the Charpy impact energy value into the fracture toughness value.

[0023] In some embodiments, the low Charpy impact energy value scenario is that the Charpy impact energy value is greater than 3 J and less than 27 J; the high Charpy impact energy value scenario is that the Charpy impact energy value is greater than 27 J.

[0024] In some embodiments, the high Charpy impact energy value scenario includes a first sub-scenario with a complete series of Charpy impact energy values, a second sub-scenario with at least one set of Charpy impact energy values and an upper shelf value at a single temperature, a third sub-scenario with at least one set of Charpy impact energy values at a single temperature and no upper shelf value, and a fourth sub-scenario with no Charpy impact energy value and an upper shelf value; the fracture toughness value distributions based on the master curve are obtained by different reference temperature formulas for the first sub-scenario, the second sub-scenario, the third sub-scenario, and the fourth sub-scenario respectively.

[0025] In some embodiments, when the Charpy impact energy value belongs to the high Charpy impact energy value scenario, the applicable master curve function is:

[0026] K mat = 20 + {11 + 77exp[0.019(T - T0 - T K )}(25 / B) 0.25 [ln(1 / 1 - P f )] 0.25 ;

[0027] where T is the test temperature corresponding to the Charpy impact energy value; T0 is the reference temperature of the fracture toughness master curve, which is obtained by different formulas according to different sub-scenarios; T K is the correction term for the discreteness during the impact toughness - fracture toughness conversion. When the Charpy impact energy value is in the first sub-scenario, T K takes 25 °C. When the Charpy impact energy value is in the second sub-scenario, T K takes 30 °C. If the test can provide evidence to support, T K can also take a lower value; B is the thickness of the impact test specimen; P f is the load of the impact test specimen.

[0028] In some embodiments, when the Charpy impact energy value satisfies the first sub-scenario, the formula for calculating the reference temperature of the fracture toughness master curve of pipeline steel is:

[0029] T0 = T 27J - 18 °C; T0 = T 40J - 24 °C;

[0030] where T 27J and T 40J are the average temperature values of a group of tests, and the minimum Charpy impact energy values in this group of tests are not less than 19 J and 28 J respectively; the standard deviation of T0 is 15 °C;

[0031] When the Charpy impact energy value satisfies the second sub-scenario, the formula for the reference temperature of the fracture toughness master curve is:

[0032]

[0033] In the formula, T 27J is the test temperature when the Charpy impact energy is 27 J; C V US is the upper shelf impact energy; σ Y represents the 0.2% proof or yield strength of the material for which the crack tip opening displacement has been measured;

[0034] When the Charpy impact energy value satisfies the third sub-scenario, the formula for obtaining T 27J is as follows:

[0035]

[0036]

[0037] In the formula, C V is the average value of the Charpy impact energy at the test temperature T CV ; σ Y represents the 0.2% proof or yield strength of the material for which the crack tip opening displacement has been measured; C V US is the upper shelf impact energy. When the upper shelf impact energy is lacking in the third sub-scenario, the maximum value of the Charpy impact energy at the test temperature can be taken, or when the Charpy impact energy and the shear fracture surface rate are available in the third sub-scenario, C V US can be calculated by the following formula:

[0038]

[0039] In the formula, C Vi is the i-th Charpy impact energy value at the test temperature T CV ; SFA is the shear fracture surface rate of the fracture in the impact test; n is the number of available impact test data;

[0040] Then, substitute the T 27J obtained in the third sub-scenario into the formula for the reference temperature of the fracture toughness master curve in the first sub-scenario to calculate the reference temperature;

[0041] When the Charpy impact energy value satisfies the fourth sub-scenario, the formula for obtaining T 27J is as follows:

[0042]

[0043] In the formula, T USTo obtain the lowest test temperature for the behavior on the upper platform, C V US is the impact energy at the upper platform;

[0044] Then, substitute the T obtained in the fourth sub-scenario 27J into the formula for the reference temperature of the fracture toughness master curve in the second sub-scenario to calculate the reference temperature.

[0045] In some embodiments, the conversion of the fracture toughness distribution into an elastoplastic fracture parameter includes:

[0046] converting the fracture toughness value into a critical stress intensity factor;

[0047] converting the critical stress intensity factor into an elastoplastic fracture parameter.

[0048] In some embodiments, the conversion of the fracture toughness value into a critical stress intensity factor includes:

[0049] When using the J-integral to measure fracture toughness, the fracture toughness value obtained based on the J-integral is converted into a critical stress intensity factor, and the specific formula is:

[0050]

[0051] In the formula, E represents the elastic modulus; J mat represents the fracture toughness value measured by the J-integral; v represents the Poisson's ratio;

[0052] When the fracture toughness has been obtained based on the crack tip opening displacement using a deep-groove high-constraint specimen, the fracture toughness value obtained based on the crack tip opening displacement is converted into a critical stress intensity factor, and the specific formula is:

[0053]

[0054] In the formula, E represents the elastic modulus; σ Y represents the 0.2% tolerance or yield strength of the material for which the crack tip opening displacement has been measured; δ mat represents the fracture toughness value obtained based on the crack tip opening displacement; E and σ Y are measured at the same temperature as the fracture toughness; the value of m is set to 15, or determined using the following formula:

[0055]

[0056] In the formula, σ Y represents the yield strength of the material measured at the fracture toughness test temperature; σ U represents the tensile strength of the material measured at the fracture toughness test temperature.

[0057] Second aspect, a conversion device for obtaining the fracture toughness from the impact toughness of pipeline steel is provided, including:

[0058] A data acquisition module, configured to acquire a plurality of existing Charpy impact energy values of the pipeline steel;

[0059] A data sorting module, configured to classify a plurality of Charpy impact energy values into corresponding preset scenarios respectively according to a plurality of preset scenarios;

[0060] A conversion module, configured to convert each Charpy impact energy value according to the conversion method under its corresponding preset scenario, and determine the distribution of fracture toughness values based on the master curve;

[0061] A data conversion and model establishment module, configured to convert the fracture toughness value into an elastoplastic fracture parameter, and establish a toughness conversion model for converting the Charpy impact energy value into an elastoplastic fracture parameter;

[0062] An evaluation module, configured to predict the fracture toughness value of the target pipeline steel by using the toughness conversion model.

[0063] Third aspect, an electronic device is provided, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the steps of the foregoing conversion method are implemented.

[0064] Fourth aspect, a computer-readable storage medium is provided. When the computer program is executed by a processor, the steps of the conversion method as described above are implemented.

[0065] Compared with the prior art, one or more embodiments in the above solutions may have the following advantages or beneficial effects:

[0066] This application provides a conversion method and device for obtaining the fracture toughness from the impact toughness of pipeline steel. Through this conversion method, a small amount of existing impact toughness data of pipeline steel can be converted according to different scenarios, so as to be converted into fracture toughness values. The sub-scenario conversion enables the impact toughness values to be converted in different ranges, improves the accuracy of the obtained fracture toughness values, and further enables a more accurate analysis of the service conditions of pipeline steel and a precise and effective integrity evaluation of pipeline steel. Description of the Drawings

[0067] In the following, the present application will be described in more detail based on embodiments and with reference to the drawings;

[0068] Figure 1 It is an exemplary flowchart of a conversion method for obtaining the fracture toughness from the impact toughness of pipeline steel provided in Embodiment 1 of the present invention;

[0069] Figure 2This corresponds to the Figure 1 exemplary flowchart of step S2 shown in

[0070] Figure 3 This corresponds to the Figure 1 exemplary flowchart of step S4 shown in

[0071] Figure 4 comparative example diagram of the CTOD value predicted based on the master curve method and the experimental value in the first embodiment of the present invention;

[0072] Figure 5 schematic block diagram of a conversion device for obtaining the fracture toughness from the impact toughness of pipeline steel provided in the second embodiment of the present invention;

[0073] Figure 6 schematic block diagram of an electronic device provided in the third embodiment of the present invention;

[0074] Figure 7 schematic diagram of a computer-readable storage medium provided in the fourth embodiment of the present invention.

[0075] In the drawings, the same components are denoted by the same reference numerals, and the drawings are not drawn to actual scale. Detailed Embodiment

[0076] The present disclosure will be further described below in conjunction with the embodiments shown in the drawings.

[0077] Embodiment 1:

[0078] The embodiment of the present application discloses a conversion method for obtaining the fracture toughness from the impact toughness of pipeline steel. As Figure 1 shown, it includes the following steps: obtaining a plurality of existing Charpy impact energy values of the pipeline steel; classifying the plurality of Charpy impact energy values into corresponding preset scenarios according to a plurality of preset scenarios; converting each Charpy impact energy value according to the conversion method under its corresponding preset scenario to determine the distribution of the fracture toughness value based on the master curve; converting the fracture toughness value into an elastic-plastic fracture parameter, and establishing a toughness conversion model for converting the Charpy impact energy value into an elastic-plastic fracture parameter; using the toughness conversion model to predict the fracture toughness value of the target pipeline steel. Through this method, it is possible to convert according to different scenarios based on a small amount of existing impact toughness data of the pipeline steel, so as to convert it into a fracture toughness value. The use of scenario-based conversion enables the impact toughness value to be converted in different ranges, improving the accuracy of the obtained fracture toughness value, and further more accurately analyzing the service condition of the pipeline steel and accurately and effectively carrying out the integrity evaluation of the pipeline steel.

[0079] A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness provided by at least one embodiment of the present disclosure can be implemented in the form of software, hardware, firmware, or any combination thereof, and is loaded and executed by a processor in devices such as mobile phones, tablet computers, laptop computers, desktop computers, network servers, etc., so as to accurately obtain the fracture toughness value, and further more accurately analyze the service conditions of pipeline steel and accurately and effectively evaluate the integrity of pipeline steel.

[0080] The following will refer to Figure 1 shown in the figure to describe the conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness provided by at least one embodiment of the present disclosure. This conversion method includes steps S1 to S5.

[0081] S1. Obtain several existing Charpy impact energy values of the pipeline steel.

[0082] In some embodiments, the pipeline steel is the pipeline steel used for the construction of oil and gas transmission pipelines, and the Charpy impact energy value is the data obtained from the impact toughness test carried out on the toughness characterization of the pipeline steel and its welds during the construction period. When obtaining the fracture toughness value of the pipeline steel, the conversion prediction can be carried out based on the impact toughness test data of the pipeline steel during the construction period, so as to accurately obtain the fracture toughness values of each pipeline steel during the construction period, and further more accurately analyze the service conditions of the pipeline steel and accurately and effectively evaluate the pipeline integrity.

[0083] S2. Classify several Charpy impact energy values into corresponding preset scenarios according to several preset scenarios.

[0084] In some embodiments, the preset scenarios include the low Charpy impact energy value scenario and the high Charpy impact energy value scenario; among them, the low Charpy impact energy value scenario is that the Charpy impact energy value is within the preset range; the high Charpy impact energy value scenario is that the Charpy impact energy value is greater than the preset threshold.

[0085] Specifically, step S2, as Figure 2 shown in the figure, includes:

[0086] S21. Compare each of the Charpy impact energy values with the preset range and the preset threshold in turn;

[0087] S22. When the Charpy impact energy value is within the preset range, classify the Charpy impact energy value into the low Charpy impact energy value scenario;

[0088] S23. When the Charpy impact energy value is greater than the preset threshold, classify the Charpy impact energy value into the high Charpy impact energy value scenario.

[0089] In some embodiments, the low Charpy impact energy value scenario is that the Charpy impact energy value is greater than 3 J and less than 27 J; the high Charpy impact energy value scenario is that the Charpy impact energy value is greater than 27 J. With such a setting, a number of Charpy impact energy values greater than 3 J and less than 27 J are classified into the low Charpy impact energy value scenario, and the Charpy impact energy values greater than 27 J are classified into the high Charpy impact energy value scenario. Thus, when converting the impact toughness value to the fracture toughness value subsequently, zoning conversion can be performed according to different ranges of the Charpy impact energy value, making the obtained fracture toughness value more accurate.

[0090] S3. Convert each Charpy impact energy value according to the conversion method under its corresponding preset scenario, and determine the fracture toughness value distribution based on the master curve.

[0091] In some embodiments, after the classification in step S2, it is divided into two major scenarios: the low Charpy impact energy value scenario and the high Charpy impact energy value scenario. Based on this, in step S3, the fracture toughness value is denoted as K JC . When the Charpy impact energy value satisfies the low Charpy impact energy value scenario, the conversion formula for converting the Charpy impact energy value into the fracture toughness distribution is:

[0092]

[0093] In the formula, B is the thickness of the impact test specimen; C V is the minimum Charpy impact energy value at the test temperature; Kmat is the critical stress intensity factor, that is, it represents K JC ;

[0094] When the Charpy impact energy value satisfies the high Charpy impact energy value scenario, the Charpy impact energy value is converted into the fracture toughness value by using the master curve method.

[0095] In some embodiments, the high Charpy impact energy value scenario includes a first sub-scenario with a complete series of Charpy impact energy values, a second sub-scenario with at least one set of Charpy impact energy values at a single temperature and an upper shelf value, a third sub-scenario with at least one set of Charpy impact energy values at a single temperature and no upper shelf value, and a fourth sub-scenario with no Charpy impact energy value and an upper shelf value; the first sub-scenario, the second sub-scenario, the third sub-scenario, and the fourth sub-scenario respectively obtain the fracture toughness value distribution based on the master curve by using different reference temperature formulas.

[0096] Based on the above subdivision of the scenarios, specifically, when the Charpy impact energy value belongs to the high Charpy impact energy value scenario, the applicable master curve function is:

[0097] K mat = 20 + {11 + 77exp[0.019(T - T0 - T K )}(25 / B) 0.25 [ln(1 / 1 - Pf )] 0.25 ;

[0098] In the formula, T is the test temperature corresponding to the Charpy impact energy value; T0 is the reference temperature of the fracture toughness master curve, which is obtained by different formulas according to different sub-scenarios; T K is the correction term for the discreteness during the conversion of impact toughness - fracture toughness. When the Charpy impact energy value is in the first sub-scenario, T K takes 25°C. When the Charpy impact energy value is in the second sub-scenario, T K takes 30°C. If the test can provide evidence to support, T K can also take a lower value; B is the thickness of the impact test specimen; P f is the load of the impact test specimen.

[0099] Specifically, when the Charpy impact energy value meets the first sub-scenario, that is, there is a complete Charpy impact energy value in this scenario, the formula for calculating the reference temperature of the fracture toughness master curve of pipeline steel is:

[0100] T0 = T 27J - 18°C;

[0101] T0 = T 40J - 24°C;

[0102] In the formula, T 27J and T 40J are the average temperature values of a group of tests. In this group of tests, the minimum Charpy impact energy values are not less than 19 J and 28 J respectively; the standard deviation of T0 is 15°C;

[0103] When the Charpy impact energy value meets the second sub-scenario, that is, in this scenario, there is at least one set of Charpy impact energy values and upper shelf values at a single temperature. The formula for calculating the reference temperature of the fracture toughness master curve is:

[0104]

[0105] In the formula, T 27J is the test temperature when the Charpy impact energy value is 27 J; C V US is the upper shelf impact energy; σ Y represents the 0.2% tolerance or yield strength of the material for which the crack tip opening displacement has been measured.

[0106] When the Charpy impact energy value meets the third sub-scenario, that is, in this scenario, there is at least one set of Charpy impact energy values at a single temperature, but there is no upper shelf value. At this time, first obtain T 27J , T 27J The acquisition formula is as follows:

[0107]

[0108]

[0109] Wherein, C V is the average value of the Charpy impact energy at the test temperature T CV ; σ Y represents the 0.2% proof or yield strength of the material for which the crack tip opening displacement has been measured; C V US is the upper shelf impact energy. When the upper shelf impact energy is lacking in the third sub-scenario, the maximum value of the Charpy impact energy at the test temperature can be taken, or when the Charpy impact energy and the shear fracture area ratio are available in the third sub-scenario, C V US can be obtained by the following formula:

[0110]

[0111] Wherein, C Vi is the i-th Charpy impact energy value at the test temperature T CV ; SFA is the shear fracture area ratio of the fracture surface of the impact test; n is the number of available impact test data;

[0112] Then, substitute the T 27J obtained in the third sub-scenario into the formula for the reference temperature of the fracture toughness master curve in the first sub-scenario to calculate the reference temperature.

[0113] When the Charpy impact energy value meets the fourth sub-scenario, that is, there is no Charpy impact energy value but there is an upper shelf value, first obtain T 27J , T 27J The acquisition formula is as follows:

[0114]

[0115] Wherein, T US is the lowest test temperature at which the upper shelf behavior is obtained, C V US is the upper shelf impact energy;

[0116] Then, substitute the T 27J obtained in the fourth sub-scenario into the formula for the reference temperature of the fracture toughness master curve in the second sub-scenario to calculate the reference temperature.

[0117] When there are Charpy impact energy values at multiple temperatures, use the Charpy impact energy value at the lowest test temperature and substitute it into the acquisition formula of T 27J in the third sub-scenario for calculation.

[0118] Meanwhile, to minimize the conservatism caused by inhomogeneous materials, the tests for calculating the upper platform impact value shall be no less than three, and the maximum shall not be greater than 120% of the average value.

[0119] S4. Convert the fracture toughness value into an elastic-plastic fracture parameter, and establish a toughness conversion model for converting the Charpy impact energy value into an elastic-plastic fracture parameter.

[0120] In some embodiments, converting the fracture toughness value into an elastic-plastic fracture parameter, as Figure 3 shown, includes:

[0121] S41. Convert the fracture toughness value into a critical stress intensity factor;

[0122] S42. Convert the critical stress intensity factor into an elastic-plastic fracture parameter.

[0123] Specifically, when using the J-integral to measure the fracture toughness, the fracture toughness value obtained based on the J-integral is converted into a critical stress intensity factor, and the specific formula is:

[0124]

[0125] In the formula, E represents the elastic modulus; J mat represents the fracture toughness value measured by the J-integral; v represents the Poisson's ratio;

[0126] When the fracture toughness has been obtained based on the crack tip opening displacement using a deep-groove high-constraint specimen, the fracture toughness value obtained based on the crack tip opening displacement is converted into a critical stress intensity factor, and the specific formula is:

[0127]

[0128] In the formula, E represents the elastic modulus; σ Y represents the 0.2% tolerance or yield strength of the material for which the crack tip opening displacement has been measured; δ mat represents the fracture toughness value obtained based on the crack tip opening displacement; E and σ Y are measured at the same temperature as the fracture toughness; the value of m is set to 15, or determined using the following formula:

[0129]

[0130] In the formula, σ Y represents the yield strength of the material measured at the fracture toughness test temperature; σ U represents the tensile strength of the material measured at the fracture toughness test temperature.

[0131] Through the conversion relationship between the stress intensity factor and the fracture toughness value, the fracture toughness value is converted into an elastoplastic fracture parameter. Furthermore, the elastoplastic fracture parameter CTOD (δ) is used as the main parameter to control the fatigue crack growth in this area, which is convenient and accurate for evaluating the fracture toughness of this pipeline steel.

[0132] Furthermore, a conversion model for converting the Charpy impact energy value into the toughness of the elastoplastic fracture parameter is established. This conversion model is a conversion model for converting the Charpy impact energy value into the toughness of the elastoplastic fracture parameter determined based on the master curve method.

[0133] S5. Use the toughness conversion model to predict the fracture toughness value of the target pipeline steel.

[0134] In some embodiments, the test data submitted for inspection at each port of a certain gas transmission pipeline are adopted. The Charpy impact energy values and the crack tip opening displacement characteristic values at 3 points are selected and compared with the predicted values of the toughness conversion model. Among them, for the missing yield strength in the data, the standard nominal minimum value is taken, and for the missing tensile strength, the average value is taken. The obtained results are shown in Tables 1, 2, and 3 below:

[0135] Table 1 Nominal minimum values of yield strength and tensile strength of X70 and X80 steel grades

[0136] Grade Yield strength / MPa Tensile strength / MPa Test temperature / °C X80 555 679 20 X70 485 625 20

[0137] Table 2 CVN values and material strength values of 10 weld joints

[0138]

[0139]

[0140] The impact energy of the 10 groups of data in Table 2 is all greater than 27 J. Since there is only one set of impact energy values at a single temperature, there is no complete series of impact energy curves and no upper platform impact energy value. According to formulas (2), (6), (7), (10), (11), and (12), the prediction results of the upper and lower boundaries and the median CTOD (δ) based on the master curve are obtained in Table 3. Compared with the CTOD values obtained from the test, as can be seen from the figure, the CVN-CTOD prediction interval based on the master curve distribution basically conforms to the distribution of the test values.

[0141] Table 3 Test values and predicted values of CTOD for 10 weld joints

[0142]

[0143] Such as Figure 4As shown in the figure, it is a comparison between the CTOD values predicted by the toughness conversion model based on the master curve method and the test values. It can be seen from the comparison that the prediction interval of the toughness conversion model based on the master curve method basically conforms to the distribution of the test values, improving the accuracy of predicting the fracture toughness value, and further more accurately analyzing the service conditions of pipeline steel and accurately and effectively carrying out pipeline integrity evaluation.

[0144] The conversion method for obtaining the fracture toughness from the impact toughness of pipeline steel provided by the embodiments of the present disclosure can convert according to different scenarios based on a small amount of existing impact toughness data of pipeline steel, so as to be converted into fracture toughness values. The scenario-based conversion enables the impact toughness values to be converted in different ranges, improving the accuracy of the obtained fracture toughness values, and further more accurately analyzing the service conditions of pipeline steel and accurately and effectively carrying out the integrity evaluation of pipeline steel.

[0145] Embodiment Two:

[0146] At least one embodiment of the present disclosure also provides a conversion device for obtaining the fracture toughness from the impact toughness of pipeline steel. Each module in this device corresponds to the steps in the above method, and the effects achieved and the problems solved have been described and will not be elaborated here. This conversion device, as Figure 5 shown, includes:

[0147] A data acquisition module 11, configured to acquire a plurality of existing Charpy impact energy values of pipeline steel;

[0148] A data sorting module 12, configured to classify a plurality of Charpy impact energy values into corresponding preset scenarios respectively according to a plurality of preset scenarios;

[0149] A conversion module 13, configured to convert each Charpy impact energy value according to the conversion method under its corresponding preset scenario to determine the distribution of fracture toughness values based on the master curve;

[0150] A data conversion and model establishment module 14, configured to convert the fracture toughness values into elastoplastic fracture parameters and establish a toughness conversion model for converting Charpy impact energy values into elastoplastic fracture parameters;

[0151] An evaluation module 15, configured to predict the fracture toughness value of the target pipeline steel by using the toughness conversion model.

[0152] In some embodiments, the output end of the data acquisition module 11 is connected to the input end of the data sorting module 12, the output end of the data sorting module 12 is connected to the input end of the conversion module 13, the output end of the conversion module 13 is connected to the input end of the data conversion and model establishment module 14, and the output end of the data conversion and model establishment module 14 is connected to the input end of the evaluation module 15.

[0153] Among them, the output ends of the conversion module 13 and the evaluation module 15 can both be connected to a display device (such as a display) to present the optimization result to the staff through the screen.

[0154] In some embodiments, the device can be a part of software or can be implemented in combination with corresponding hardware, which will not be elaborated here.

[0155] Embodiment III:

[0156] Some embodiments of the present disclosure further provide an electronic device, such as Figure 6 As shown, the electronic device includes a memory 21 and a processor 22. A computer program is stored on the memory 21. When the computer program is executed by the processor, it executes the steps of the conversion method provided in any one of the embodiments of the present disclosure.

[0157] In some embodiments, the processor 22 is used to execute all or part of the steps in the conversion method of any one of the embodiments of the present disclosure. The memory 21 is used to store various types of data, which may include, for example, instructions of any application program or method in the electronic device, as well as data related to the application program.

[0158] The processor 22 can be implemented by an application specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller, a microprocessor or other electronic components, and is used to execute the conversion method in Embodiment I above.

[0159] The memory 21 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0160] Embodiment 4:

[0161] Some embodiments of the present disclosure also provide a computer-readable storage medium, as Figure 7 shown, a computer program 31 is stored on the readable storage medium, and when the computer program 31 is executed by a processor, the steps of the conversion method provided in any embodiment of the present disclosure are implemented.

[0162] In some embodiments, the storage medium may be a tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of the machine-readable storage medium would include electrical connections based on 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 fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0163] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and a pointing device (e.g., a mouse or a trackball) through which the user can provide input to the computer. Other kinds of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, speech input, or tactile input).

[0164] The systems and techniques described herein can be implemented in a computing system including backend components (e.g., as a data server), or a computing system including middleware components (e.g., an application server), or a computing system including frontend components (e.g., a user computer having a graphical user interface or a web browser through which the user can interact with an implementation of the systems and techniques described herein), or a computing system including any combination of such backend components, middleware components, or frontend components. The components of the system can be interconnected to each other by digital data communication in any form or medium (e.g., a communication network). Examples of communication networks include: local area network (LAN), wide area network (WAN), and the Internet.

[0165] A computer system can include a client and a server. The client and the server are generally far from each other and usually interact through a communication network. The client - server relationship is created by computer programs running on the respective computers and having a client - server relationship with each other. The server can be a cloud server, or a server of a distributed system, or a server incorporating a blockchain.

[0166] An embodiment of the present invention also provides a computer program product, including a computer program / instructions which, when executed by a processor, implement the steps of the conversion method provided in any one of the embodiments of the present disclosure.

[0167] The various embodiments in the present disclosure are described in a progressive manner. For the same or similar parts among the various embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments.

[0168] The protection scope of the present disclosure is not limited to the above - mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present disclosure without departing from the scope and spirit of the present disclosure. If these changes and modifications fall within the scope of the claims of the present disclosure and their equivalent technologies, the intention of the present disclosure also includes these changes and modifications.

Claims

1. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness, characterized in that It includes the following steps: Obtain several existing Charpy impact energy values of pipeline steel; Classify several Charpy impact energy values into corresponding preset scenarios respectively according to several preset scenarios; Convert each Charpy impact energy value according to the conversion method under its corresponding preset scenario, and determine the distribution of fracture toughness values based on the master curve; Convert the fracture toughness value into an elastic-plastic fracture parameter, and establish a toughness conversion model for converting the Charpy impact energy value into an elastic-plastic fracture parameter; Use the toughness conversion model to predict the fracture toughness value of the target pipeline steel.

2. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness according to claim 1, characterized in that The preset scenarios include a low Charpy impact energy value scenario and a high Charpy impact energy value scenario; the low Charpy impact energy value scenario is that the Charpy impact energy value is within a preset range; the high Charpy impact energy value scenario is that the Charpy impact energy value is greater than a preset threshold; The classifying several Charpy impact energy values into corresponding preset scenarios respectively includes: Compare each of the Charpy impact energy values with the preset range and the preset threshold in turn; When the Charpy impact energy value is within the preset range, classify the Charpy impact energy value into the low Charpy impact energy value scenario; When the Charpy impact energy value is greater than the preset threshold, classify the Charpy impact energy value into the high Charpy impact energy value scenario.

3. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness according to claim 1, characterized in that, The fracture toughness value is denoted as K JC ; When the Charpy impact energy value satisfies the low Charpy impact energy value scenario, the conversion formula for converting the Charpy impact energy value into the fracture toughness distribution is: where B is the thickness of the impact test specimen; C V is the minimum Charpy impact energy value at the test temperature; Kmat is the critical stress intensity factor, which represents K JC ; When the Charpy impact energy value meets the high Charpy impact energy value scenario, use the master curve method to convert the Charpy impact energy value into a fracture toughness value.

4. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness according to claim 2, characterized in that, The low Charpy impact energy value scenario is that the Charpy impact energy value is greater than 3J and less than 27J; the high Charpy impact energy value scenario is that the Charpy impact energy value is greater than 27J.

5. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness according to claim 3, characterized in that, The high Charpy impact energy value scenario includes a first sub-scenario with a complete series of Charpy impact energy values, a second sub-scenario with at least one set of Charpy impact energy values at a single temperature and an upper shelf value, a third sub-scenario with at least one set of Charpy impact energy values at a single temperature and no upper shelf value, and a fourth sub-scenario with no Charpy impact energy value and an upper shelf value; the first sub-scenario, the second sub-scenario, the third sub-scenario, and the fourth sub-scenario respectively obtain the distribution of fracture toughness values based on the master curve using different reference temperature formulas.

6. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness according to claim 3, characterized in that, When the Charpy impact work value belongs to the high Charpy impact work value scenario, the applicable master curve function is: K mat = 20 + {11 + 77exp[0.019(T - T0 - T K )}(25 / B) 0.25 [ln(1 / 1 - P f )] 0.25 ; Wherein, T is the test temperature corresponding to the Charpy impact energy value; T0 is the reference temperature of the fracture toughness master curve, which is obtained by different formulas according to different sub-scenarios; T K is the correction term for the discreteness during the conversion of impact toughness - fracture toughness. When the Charpy impact energy value is in the first sub-scenario, T K takes 25°C. When the Charpy impact energy value is in the second sub-scenario, T K takes 30°C. If the test can provide evidence to support, T K can also take a lower value; B is the thickness of the impact test specimen; P f is the load of the impact test specimen.

7. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness according to claim 5, characterized in that When the Charpy impact energy value meets the first sub-scenario, the formula for calculating the reference temperature of the pipeline steel fracture toughness master curve is: T0 = T 27J -18 °C; T0 = T 40J -24 °C; where T 27J and T 40J are the average temperature values of a set of tests, in which the minimum Charpy impact energy values of this set of tests are not less than 19 J and 28 J respectively; the standard deviations of T0 are both 15 °C; When the Charpy impact energy value meets the second sub-scenario, the formula for the reference temperature of the fracture toughness master curve is: Wherein, T 27J is the test temperature when the Charpy impact energy value is 27 J; C V US is the upper shelf impact energy; σ Y represents the 0.2% proof or yield strength of a material for which the crack tip opening displacement has been determined; When the Charpy impact work value meets the third sub-scenario, the acquisition formula of T 27J is as follows: Where C V is the average Charpy impact energy at the test temperature T CV ; σ Y represents the 0.2% proof or yield strength of the material for which the crack tip opening displacement has been determined; C V US is the upper shelf impact energy. When the upper shelf impact energy is lacking in the third sub-scenario, the maximum Charpy impact energy at the test temperature may be taken, or when the Charpy impact energy and shear fracture area ratio are available in the third sub-scenario, C V US can be calculated by the following formula: Where C Vi is the i-th Charpy impact energy value at the test temperature T CV ; SFA is the shear fracture surface rate of the fracture in the impact test; n is the number of available impact test data; Then substitute the T obtained in the third sub-scenario 27J into the formula for the reference temperature of the fracture toughness master curve in the first sub-scenario to calculate the reference temperature; When the Charpy impact energy value meets the fourth sub-scenario, the acquisition formula of T 27J is as follows: Where T US is the lowest test temperature for obtaining the behavior of the upper platform, and C V US is the impact work of the upper platform; Then substitute the T obtained in the fourth sub-scenario 27J into the formula for the reference temperature of the fracture toughness master curve in the second sub-scenario to calculate the reference temperature.

8. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness according to claim 1, characterized in that The converting the fracture toughness distribution into an elastic-plastic fracture parameter includes: Convert the fracture toughness value into a critical stress intensity factor; Convert the critical stress intensity factor into an elastic-plastic fracture parameter.

9. A conversion method for obtaining the fracture toughness of pipeline steel from its impact toughness according to claim 1, characterized in that, The converting the fracture toughness value into a critical stress intensity factor includes: When using the J-integral to measure the fracture toughness, the fracture toughness value obtained based on the J-integral is converted into a critical stress intensity factor, and the specific formula is: In the formula, E represents the elastic modulus; J mat represents the fracture toughness value measured by the J-integral; v represents the Poisson's ratio; When the fracture toughness has been obtained based on the crack tip opening displacement using a deep-groove high-constraint specimen, the fracture toughness value obtained based on the crack tip opening displacement is converted into a critical stress intensity factor, and the specific formula is: where E represents the elastic modulus; σ Y represents the 0.2% proof or yield strength of the material for which the crack tip opening displacement has been measured; δ mat represents the fracture toughness value obtained based on the crack tip opening displacement; E and σ Y are measured at the same temperature as the fracture toughness; the value of m is set to 15, or is determined using the following formula: where σ Y represents the yield strength of the material measured at the fracture toughness test temperature; σ U represents the tensile strength of the material measured at the fracture toughness test temperature.

10. A conversion device for obtaining the fracture toughness of pipeline steel from its impact toughness, characterized in that, It includes: A data acquisition module for obtaining several existing Charpy impact energy values of pipeline steel; A data sorting module for sorting a number of Charpy impact work values into corresponding preset scenarios respectively according to a number of preset scenarios; A conversion module for converting each Charpy impact work value according to the conversion method under its corresponding preset scenario to determine the distribution of fracture toughness values based on the master curve; A data conversion and model establishment module for converting the fracture toughness values into elastoplastic fracture parameters and establishing a toughness conversion model for converting Charpy impact work values into elastoplastic fracture parameters; An evaluation module for evaluating the target pipeline steel according to the toughness conversion model.

11. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, the steps of the conversion method described in any one of claims 1 to 9 are implemented.

12. A computer-readable storage medium, characterized in that, When the computer program is executed by the processor, the steps of the conversion method described in any one of claims 1 to 9 are implemented.

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