A prediction model for crack arrest temperature based on ductile-brittle transition temperature of crack arrest steel

Abstract

The present invention relates to the technical field of material fracture failure research, and specifically to a prediction model for crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel, comprising the following specific steps: S1: taking an impact specimen in the thickness direction of a high-strength crack arrest steel plate; S2: performing a series of temperature oscillographic impact tests on the specimen; S3: obtaining the ductile-brittle transition temperature K of the crack initiation work; a ; S4: Measured crack arrest temperature T of high strength crack arrest steel Kca6000 ; S5: Use the ductile-brittle transition temperature K a And crack arrest temperature T Kca6000 Fitting is performed to obtain formula 1: T Kca6000 =A+B*K a ; S6: The ductile-brittle transition temperature K a Substituting into formula 1, we can obtain the corresponding high-strength steel crack arrest temperature T Kca6000 The present invention can simply and effectively predict the crack arrest temperature of high-strength crack arrest steel through a prediction model, without the need for a double tensile test, thus saving test time and cost, and has the characteristics of simplicity and high efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of material fracture failure research, and in particular to a prediction model for crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel. Background Art

[0002] In today's society, the importance of ship crack arresting ability cannot be ignored. With the continuous development of global trade and shipping industry, ships are the main means of maritime transportation, and their safety and reliability are directly related to the safety of personnel and cargo, as well as the protection of the marine environment. Therefore, improving the ship's crack arresting ability is crucial to ensure shipping safety. Ships may face various complex marine environments and climatic conditions during navigation, such as waves, storms, seawater corrosion, etc. These factors may cause cracks or damage to the ship structure, which in turn may cause fracture accidents; large ships such as container ships and cruise ships need to bear significant weight and pressure during transportation. If the ship's crack arresting ability is insufficient, these pressures may cause cracks or fractures in the hull structure, seriously affecting the safety and transportation efficiency of the ship; therefore, the ship's crack arresting ability is of great significance in today's society. By adopting advanced materials and technical means, the ship's crack arresting ability can be continuously improved to ensure the safe and reliable navigation of ships in complex marine environments, providing strong guarantees for the sustainable development of global trade and shipping industry.

[0003] At present, the crack arrest performance of hull steel materials is mainly reflected by crack arrest toughness and crack arrest temperature. The tests of crack arrest toughness and crack arrest temperature come from ESSO test, double tensile test, wide plate tensile test and biaxial tensile test, etc. These test methods have complex sample preparation, high requirements for test equipment, complex stress state and high cost of large-size samples. Therefore, a large number of studies have been carried out at home and abroad, and a variety of correlation models between crack arrest toughness, crack arrest temperature and small-size specimen characterization parameters have been established, such as the correlation model between crack arrest temperature and non-plastic transition temperature, the correlation model between crack arrest temperature CAT and tensile strength Rm, non-plastic transition temperature NDT, ductile-brittle transition characteristic parameter k and plate thickness t, and the correlation model between crack arrest temperature CAT and carbon equivalent Ceq, tensile strength Rm, ductile-brittle transition characteristic parameter lnk and plate thickness t. By establishing the correlation between large-size crack arrest test and small-size test, the basic mechanical performance parameters affecting crack arrest performance are clarified, which points out the direction for further regulation and optimization of crack arrest performance and greatly promotes the development of domestic crack arrest steel. The above-mentioned large number of research results show that the crack arrest temperature of the crack arrest thickness is closely related to the material's impact work ductile-brittle transition characteristic temperature, non-plastic transition temperature, etc. The crack initiation work refers to the energy required to start crack initiation from a crack-free state in steel. This parameter is of great significance in the field of material fracture mechanics because it reflects the material's ability to resist crack initiation. However, there is currently no public report on the influence of the crack initiation work of high-strength crack arrest steel on the crack arrest temperature and the research on the prediction model.

[0004] Publication No.: CN114781113B discloses a prediction model for the crack arrest temperature of a thick high-strength steel plate for shipbuilding, its construction method and application. Starting from the physical mechanism of the gradient temperature type double tensile test process, the influence of strength, plate thickness and non-plastic transition temperature on crack arrest behavior is comprehensively considered, and a crack arrest temperature prediction model based on a small-scale tensile test and a drop hammer test is provided, thereby providing strong technical support for the crack arrest performance control and supply inspection of high-strength steel thick plates. However, the patent is based on a crack arrest temperature prediction model based on a small-scale tensile test and a drop hammer test, and does not involve the influence of crack initiation work on crack arrest temperature.

[0005] Therefore, there is no model in the prior art involving the prediction of crack initiation work on crack arrest temperature, so as to avoid the problems of complex sample preparation, high requirements for test equipment, complex stress state and high cost of large-size samples. Summary of the invention

[0006] In view of this, the present invention aims to propose a prediction model for crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel, so as to solve the problems of complex sample preparation, high requirements for testing equipment, complex stress state and high cost of large-size samples in the test method of crack arrest temperature in the prior art.

[0007] From the perspective of engineering application, the crack arrest temperature has good engineering applicability. On the one hand, the crack arrest temperature can be determined by gradient temperature or isothermal test. Generally, only two tests are needed to determine the crack arrest temperature under one allowable stress condition. On the other hand, by measuring the crack arrest temperature under different working stresses, a crack arrest plate selection chart can be established. Under allowable stress, steel plates with crack arrest temperatures higher than the minimum service temperature have crack arresting ability and can be used for crack arrest plate selection. The engineering application is relatively simple and reliable.

[0008] However, in the prior art, the sample preparation for the crack arrest temperature test method is complex, the test equipment requirements are high, the stress state is complex, and the cost of large-size samples is high; at the same time, some of the existing crack arrest temperature prediction methods are based on the tensile strength R m , non-ductile transition temperature NDT, ductile-brittle transition characteristic parameter k and plate thickness t, some of which are based on carbon equivalent C eq , tensile strength R m , the correlation model of the ductile-brittle transition characteristic parameter lnk and the plate thickness t. The above method involves many parameters, complex calculations, and inconvenient actual experimental operation process.

[0009] In order to address the deficiencies in the prior art, the present invention discloses a method for predicting crack arrest temperature by using a small amount of basic experiments and the formula of crack initiation work and crack arrest temperature. The formula selected by this method has been verified by actual experiments, has high prediction accuracy, can meet the needs of actual engineering applications, and can conveniently and quickly realize the prediction of crack arrest temperature.

[0010] The technical solution of the present invention is implemented as follows: a prediction model for crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel comprises the following specific steps:

[0011] S1: Take the impact specimen in the thickness direction of the high-strength crack arrest steel plate;

[0012] S2: Conduct a series of temperature oscillographic shock tests on the specimen;

[0013] S3: Extract the cracking work at different temperatures, obtain the cracking work ductile-brittle transition characteristic curve, and obtain the cracking work ductile-brittle transition temperature K a ;

[0014] S4: Double tensile test is performed to measure the crack arrest temperature T of high-strength crack arrest steel Kca6000 ;

[0015] S5: Use the ductile-brittle transition temperature K a And crack arrest temperature T Kca6000 Fitting is performed to obtain formula 1: T Kca6000 =A+B*K a ;

[0016] S6: The ductile-brittle transition temperature K a Substituting into formula 1, we can obtain the corresponding high-strength steel crack arrest temperature T Kca6000 .

[0017] Further, in step S1, the steel grade of the high-strength crack-arresting steel plate is EH40, EH47 or EH50, the plate thickness range is 50-100 mm, and samples are taken in the 1 / 4 and 1 / 2 plate thickness directions.

[0018] Furthermore, in step S2, a series of temperature oscillometric shock tests are performed according to standard GB / T 19748, and the data recorded during the test include the test temperature and the crack initiation work KV2.

[0019] Further, in step S3, the relationship between the crack initiation work KV2 of the sample and the ductile-brittle transition temperature k of the crack initiation work is used to obtain formula 2: P = ,

[0020] Where: P: slope of the ductile-brittle transition curve;

[0021] E 上平台 : The upper platform of the crack initiation work in the ductile-brittle transition curve;

[0022] E 下平台 : The lower platform of the crack initiation work in the ductile-brittle transition curve;

[0023] x: temperature.

[0024] Further, in step S3, the crack initiation temperature K of the crack arrest steel plate is a Calculation formula 3: K a = (k1+k2) / 2;

[0025] Where: k1: ductile-brittle transition temperature of crack initiation in 1 / 4 plate thickness direction;

[0026] k2: ductile-brittle transition temperature of crack initiation in 1 / 2 plate thickness direction.

[0027] Furthermore, the ductile-brittle transition temperature K a The range is -100℃~-50℃.

[0028] Further, in step S4, in step S4, a double tensile test is performed according to standard Q725-1181, the double tensile test is performed at least twice, and the temperature and loading force of the test are recorded.

[0029] Further, in step S4, the double tensile test is performed four times at a temperature ranging from -60°C to 0°C.

[0030] Furthermore, in step S5, when fitting formula 1, the values ​​of parameters k1 and k2 are not less than two.

[0031] Furthermore, 11 values ​​of parameters k1 and k2 are selected, and the range of values ​​is -100°C-50°C.

[0032] Compared with the prior art, the prediction model of the crack arrest temperature based on the ductile-brittle transition temperature of the crack arrest steel of the present invention has the following advantages:

[0033] 1. The present invention can simply and effectively predict the crack arrest temperature of high-strength crack arrest steel, without the need to conduct a large number of double tensile tests, saving test time and costs. It has the characteristics of simplicity and high efficiency, and provides technical support for the study of the crack arrest performance of high-strength crack arrest steel.

[0034] 2. The present invention establishes the average value of the ductile-brittle transition temperature of the crack initiation work during the 1 / 4 and 1 / 2 thickness direction oscillographic impact of the high-strength crack arrest thick plate and the crack arrest temperature T of the crack arrest steel plate. Kca6000 The correlation model. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0036] Figure 1 The crack initiation work ductile-brittle transition characteristic curve and the crack initiation work ductile-brittle transition temperature in the present invention;

[0037] Figure 2 The crack arrest temperature T of the high-strength crack arrest steel measured by the double tensile test in the present invention is Kca6000 ;

[0038] Figure 3 In the present invention, the ductile-brittle transition temperature k1 and the crack arrest temperature T Kca6000 Relevance;

[0039] Figure 4 The ductile-brittle transition temperature k2 and the crack arrest temperature T2 in the 1 / 2 plate thickness direction of the present invention are Kca6000 Relevance;

[0040] Figure 5 The ductile-brittle transition temperature K of the present invention is a and crack arrest temperature T Kca6000 Relevance;

[0041] Figure 6 The crack arrest temperature T Kca6000 Comparison of predicted values ​​from the prediction model with measured values;

[0042] Description of reference numerals: DETAILED DESCRIPTION

[0043] In order to make the technical means, objectives and effects of the present invention easy to understand, the embodiments of the present invention are described in detail below with reference to specific drawings.

[0044] It should be noted that all the terms used in the present invention to indicate directionality and position, such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "lower", "lateral", "longitudinal", "center", etc., are only used to explain the relative positional relationship and connection status between the components in a certain state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0045] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0047] The present invention discloses a prediction model for crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel, comprising the following specific steps:

[0048] S1: Take the impact specimen in the thickness direction of the high-strength crack arrest steel plate;

[0049] S2: Conduct a series of temperature oscillographic shock tests on the specimen;

[0050] S3: Extract the cracking work at different temperatures, obtain the cracking work ductile-brittle transition characteristic curve, and obtain the cracking work ductile-brittle transition temperature K a ;

[0051] S4: Double tensile test is performed to measure the crack arrest temperature T of high-strength crack arrest steel Kca6000 ;

[0052] S5: Use the ductile-brittle transition temperature K a And crack arrest temperature T Kca6000 Fitting is performed to obtain formula 1: T Kca6000 =A+B*K a ;

[0053] S6: The ductile-brittle transition temperature K a Substituting into formula 1, we can obtain the corresponding high-strength steel crack arrest temperature T Kca6000 .

[0054] By taking samples in the thickness direction of the crack arrest steel plate and conducting a series of temperature oscillographic impact tests, the characteristic curve of the ductile-brittle transition of the crack initiation work and the ductile-brittle transition temperature K of the crack initiation work are obtained. aThen, a small number of double tensile tests were performed to obtain crack arrest temperature data and establish the ductile-brittle transition temperature K a and crack arrest temperature T Kca6000 The relationship model of crack initiation and ductile-brittle transition temperature is established to predict the crack arrest temperature of the crack arrest steel plate.

[0055] Compared with traditional test methods, this setting only requires a small amount of basic tests to quickly predict the crack arrest temperature through the formula, which greatly shortens the test cycle, reduces test costs, and improves work efficiency. It is simple and efficient, and provides technical support for the study of crack arrest performance of high-strength crack arrest steel.

[0056] Specifically, formula 1: T Kca6000 =A+B*K a In the formula, A and B are coefficients of formula 1, and the ductile-brittle transition temperature K is used. a And crack arrest temperature T Kca6000 After fitting, the values ​​of coefficients A and B can be obtained.

[0057] Specifically, in step S1, the steel grade of the high-strength crack-arresting steel plate is EH40, EH47 or EH50, the plate thickness range is 50-100 mm, and samples are taken in the 1 / 4 and 1 / 2 plate thickness directions.

[0058] Crack arrest steel is mainly used in the hatch coaming top plate, web plate, upper deck, side top plate of ultra-large container ships, as well as the longitudinal bones of the torsion box, the torsion box deck and other positions of the entire ship that are subjected to the greatest stress and alternating load intensity. Therefore, the steel plate is required to have high strength, high low-temperature toughness, high strain, high crack arrest, good welding performance and processability, etc. High-strength and thick steel plates are generally used in the hull of container transport ships. While meeting the performance requirements, high-strength and thick steel plates make the stress state of the steel plate change from a plane stress state to a plane strain state, and the material's crack resistance decreases. By selecting high-strength crack arrest steel for thick plates and sampling at 1 / 4 and 1 / 2 of the thickness direction, the representativeness of the test is ensured, and the performance differences of the steel plates at different thickness positions can be reflected. At present, the domestic high-strength crack arrest steel grades are generally EH40, EH47 or EH50. The method of the present invention can cover the crack arrest temperature prediction within this range, and the test results can be obtained quickly through fewer tests.

[0059] The setting requires sampling at specific locations for testing, which can compare the test results at these locations, understand the differences in the crack arrest performance of steel plates at different locations, provide a basis for material application and design, better evaluate the crack arrest performance of steel plates when subjected to impact loads, and ensure that the performance of steel plates in actual applications meets the requirements.

[0060] Preferably, when the plate thickness of the high-strength crack arrest steel is 80 mm, the sample is processed into a round bar sample with a gauge length of 50 mm and a diameter of 14 mm.

[0061] The sampling requirements of this setting can better obtain the performance characteristics of the entire steel plate, meet the test processing requirements, reduce the test size error, eliminate the test result deviation caused by the sample size error, and improve the accuracy and comparability of the test data.

[0062] Specifically, in step S2, a series of temperature oscillographic impact tests are performed according to standard GB / T 19748, and the data recorded during the test include the test temperature and the crack initiation work KV2.

[0063] The test standard can better control the progress of the test, reduce errors in the test process, and improve the test accuracy; the oscillographic impact test is carried out on the sample at a series of temperatures, and the change of the crack initiation work at different temperatures is obtained by changing the test temperature, which is convenient for drawing a schematic diagram of the crack initiation work and the test temperature, and is helpful for the subsequent fitting of the relationship between the crack initiation work and the ductile-brittle transition temperature of the crack initiation work.

[0064] Preferably, in step S2, a series of temperature oscillographic shock tests are performed 8 times, and the temperature range is -240°C to 0°C.

[0065] The set temperature range can cover various stages of fracture of high-strength crack arrest steel, ensuring that sufficient test data are obtained through the oscillographic impact test to obtain the ductile-brittle transition temperature of the crack initiation work; the number of tests is set to 8 times, so that there are sufficient test data for the fracture tests at each stage, avoiding the impact of abnormal single test data on the performance evaluation of the material, reducing test errors, and improving test accuracy.

[0066] Specifically, in step S3, the relationship between the crack initiation work KV2 of the sample and the ductile-brittle transition temperature k of the crack initiation work is used to obtain formula 2: P = ,

[0067] Where: P: slope of the ductile-brittle transition curve;

[0068] E 上平台 : The upper platform of the crack initiation work in the ductile-brittle transition curve;

[0069] E 下平台 : The lower platform of the crack initiation work in the ductile-brittle transition curve;

[0070] x: temperature.

[0071] The ductile-brittle transition temperatures k1 and k2 at 1 / 4 and 1 / 2 of the thickness of the steel plate can be calculated by using formula 2 and the crack initiation work. 上平台 、E 下平台 , P and x can be quickly obtained by fitting a small amount of experimental data.

[0072] This setting uses data obtained from a small amount of basic tests to obtain the ductile-brittle transition temperatures k1 and k2 at different crack initiation times according to Formula 1, avoiding a large number of tests to obtain material performance parameters, helping to save time and reduce costs.

[0073] Specifically, in step S3, the crack initiation temperature K of the crack arrest steel plate is a Calculation formula 3: K a = (k1+k2) / 2;

[0074] Where: k1: ductile-brittle transition temperature of crack initiation in 1 / 4 plate thickness direction;

[0075] k2: ductile-brittle transition temperature of crack initiation in 1 / 2 plate thickness direction.

[0076] The ductile-brittle transition temperature K of high strength crack arrest steel a It is obtained by calculating the average value of the sum of the ductile-brittle transition temperatures at 1 / 4 and 1 / 2 of the thickness of the steel plate.

[0077] This setting can more comprehensively reflect the toughness transition characteristics of the crack arrest steel plate throughout the entire thickness range, which helps to more accurately evaluate the overall performance of the material; reduce the error in measuring the ductile-brittle transition temperature of the crack initiation work at a single location, and improve the accuracy of the evaluation.

[0078] Preferably, the ductile-brittle transition temperature K a The range is -100℃~-50℃.

[0079] The setting crack initiation temperature is ductile-brittle transition temperature K a The test material can meet the equipment requirements in low temperature environments, making it suitable for practical applications of high-strength crack-arrest steel. At the same time, the model prediction accuracy is higher in this range.

[0080] Specifically, in step S4, the double tensile test is performed according to standard Q725-1181.

[0081] The test standard can better control the progress of the test, reduce errors in the test process, and improve the test accuracy; the oscillographic impact test is carried out on the sample at a series of temperatures, and the change of the crack initiation work at different temperatures is obtained by changing the test temperature, which is convenient for drawing a schematic diagram of the crack initiation work and the test temperature, and is helpful for the subsequent fitting of the relationship between the crack initiation work and the ductile-brittle transition temperature of the crack initiation work.

[0082] Specifically, in step S4, the double tensile test is performed at least twice, and the temperature and loading force of the test are recorded.

[0083] By repeating the same test conditions many times, more data points can be collected to verify the repeatability of the test, reduce the accidental errors that may be caused by a single test, obtain different crack arrest temperatures of materials under different loads, and fit the relationship between different loads and crack arrest temperatures of the material, which can be better used for evaluating the mechanical properties of the material and quickly obtaining the crack arrest temperature.

[0084] Preferably, the double tensile test is performed four times at a temperature ranging from -60°C to 0°C.

[0085] Through four double tensile tests, the accurate crack arrest temperature of the test material can be obtained to avoid the influence of too few tests and too large single error on the test results, and it is convenient to obtain the curve between the crack arrest temperature and the load; the temperature range is selected within the actual application range of the double tensile test, which can better test the mechanical properties of the test material during use.

[0086] This setting enables the double tensile test to obtain more accurate mechanical properties of the material with only a small number of tests, greatly reducing the number of tests, saving test time and reducing test costs.

[0087] Specifically, in step S5, when fitting formula 1, the values ​​of parameters k1 and k2 are no less than two.

[0088] Through at least two sets of test data, the ductile-brittle transition temperature of the crack initiation work at 1 / 4 and 1 / 2 of the thickness direction of the test material is obtained, and the correlation between the crack arrest temperature and the ductile-brittle transition temperature of the crack initiation work is obtained, and then the crack arrest temperature of the crack-arrested thick plate is predicted and evaluated by using the crack initiation work, providing a technical basis for the evaluation of the crack arrest temperature of the crack-arrested thick plate.

[0089] Preferably, 11 values ​​of parameters k1 and k2 are selected, and the range of values ​​is -100°C-50°C.

[0090] The setting of multiple groups of test data can avoid the problem of too few tests and too large single error affecting the test results, which helps to improve the accuracy of the test, can better fit the correlation between the crack arrest temperature and the crack initiation temperature, and improve the prediction accuracy of the model.

[0091] Specifically, in step S5, A and B are coefficients obtained during the fitting process.

[0092] Specifically, the crack arrest temperature T is based on the average value of the ductile-brittle transition temperature of the crack initiation work in the 1 / 4 and 1 / 2 plate thickness directions. Kca6000 The relative deviation of the prediction model is no more than 9%.

[0093] The crack arrest temperature T obtained by the prediction model of the present invention Kca6000The relative deviation from the measured value can be used to determine whether there are abnormal conditions during the test, such as errors caused by operation, errors caused by test processing, or defects in the sample itself. A set of data can be retained in the double tensile test to verify whether the test results are correct and improve the accuracy of the test.

[0094] This setting can verify the accuracy of the test process, avoid interference with the test results due to errors in the sample or test process, and improve the reliability of the test results.

[0095] Example 1

[0096] 1. According to GB / T 19748 "Instrumented test method for Charpy V-notch pendulum impact test of metallic materials", samples were taken from different batches of high-strength crack arrest steel plates in the 1 / 4 and 1 / 2 thickness directions, and the wave impact test was carried out to obtain the crack initiation work at different temperatures, such as Figure 1 As shown, the crack initiation work ductile-brittle transition temperature is calculated using formula 2, and the average value of the crack initiation work ductile-brittle transition temperature K in the 1 / 4 and 1 / 2 directions is calculated using formula 3 a ;like Figure 2 As shown in the figure, according to Q725-1181, double tensile tests were performed on different batches of high-strength crack arrest steel plates to obtain the crack arrest temperature T Kca6000 .

[0097] Table 1 Crack initiation temperature and crack arrest temperature in the 1 / 4 and 1 / 2 plate thickness direction

[0098]

[0099] 2. Substitute the data in Table 1 into Formula 2 for linear fitting, as shown in Figure 3-5 The obtained parameters are shown in Table 2, and the form of the prediction model is shown in Formula 4. Crack arrest temperature T Kca6000 The predicted and measured values ​​are shown in Figure 6 , crack arrest temperature T Kca6000 The predicted values ​​and measured values ​​are shown in Table 3. The crack arrest temperature T based on the average value of the ductile-brittle transition temperature of the crack initiation work in the 1 / 4 and 1 / 2 plate thickness directions Kca6000 The relative deviation of the prediction model is no more than 9%.

[0100] Table 2 Undetermined parameter values ​​in the calculation model

[0101]

[0102] Formula 4: T Kca6000 =A+B*K a

[0103] Table 3 Crack arrest temperature T based on the average value of ductile-brittle transition temperature of crack initiation work in 1 / 4 and 1 / 2 plate thickness direction Kca6000 Predicted and measured values

[0104]

[0105] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A prediction model for crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel, characterized in that: The following steps are involved: S1: Samples are taken at 1 / 4 and 1 / 2 plate thickness directions of high-strength crack arrest steel. The steel grade of the high-strength crack arrest steel plate is EH40, EH47 or EH50, and the plate thickness range is 50-100mm; S2: Conduct a series of temperature oscillographic shock tests on the specimen; S3: Extract the crack initiation work at different temperatures, obtain the crack initiation work ductile-brittle transition characteristic curve, and obtain the crack initiation work ductile-brittle transition temperature Ka; the calculation formula of the crack initiation work ductile-brittle transition temperature Ka of the crack arrest steel plate is 3: Ka=(k1+k2) / 2; Where: k1: ductile-brittle transition temperature of crack initiation in 1 / 4 plate thickness direction; k2: ductile-brittle transition temperature of crack initiation in the 1 / 2 plate thickness direction; S4: Double tensile test: A small number of tests are carried out according to standard Q725-1181. The double tensile test is carried out at least twice, and the test temperature and loading force are recorded. The crack arrest temperature T of high-strength crack arrest steel is measured. Kca6000 ; S5: Use the crack initiation temperature Ka and crack arrest temperature T Kca6000 Fitting is performed to obtain formula 1: T Kca6000 =A+B*ka; S6: Substituting the ductile-brittle transition temperature ka into formula 1, the corresponding high-strength steel crack arrest temperature T can be obtained. Kca6000 .

2. The prediction model of crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel according to claim 1 is characterized in that: In step S2, a series of temperature oscillographic impact tests are performed according to standard GB / T 19748, and the data recorded during the test include test temperature and crack initiation work KV2.

3. The prediction model of crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel according to claim 2 is characterized in that: In step S3, the relationship between the crack initiation work KV2 and the ductile-brittle transition temperature k of the sample is used to obtain formula 2: P = ; Where: P: slope of the ductile-brittle transition curve; E 上平台 : The upper platform of the crack initiation work in the ductile-brittle transition curve; E 下平台 : The lower platform of the crack initiation work in the ductile-brittle transition curve; x: temperature.

4. The prediction model of crack arrest temperature based on the ductile-brittle transition temperature of crack arrest steel according to claim 1 is characterized in that: The range of the ductile-brittle transition temperature Ka is -100℃~-50℃.

5. The prediction model of crack arrest temperature based on ductile-brittle transition temperature of crack arrest steel according to claim 1, characterized in that: In step S4, the double tensile test is performed four times at a temperature ranging from -60°C to 0°C.

6. The prediction model of crack arrest temperature based on ductile-brittle transition temperature of crack arrest steel according to claim 1, characterized in that: In step S5, when fitting formula 1, the values ​​of parameters k1 and k2 are not less than two.

7. The prediction model of crack arrest temperature based on ductile-brittle transition temperature of crack arrest steel according to claim 6, characterized in that: There are 11 values ​​for parameters k1 and k2, ranging from -100°C to 50°C.

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