Simplified test method, prediction method and prediction system for crack arrest toughness of material

Abstract

The invention belongs to the technical field of material performance testing, and particularly relates to a simplified test method, a prediction method and a prediction system for the crack arrest toughness of a material, and the test method comprises the following steps: obtaining a crack arrest toughness sample containing precracks of a target material and physical parameters of the sample under preset conditions; the method comprises the following steps: under a preset condition, carrying out multiple loading and unloading crack arrest toughness tests on a sample in an incomplete unloading manner to obtain loading and unloading test data in each loading and unloading process, the loading and unloading test data comprising load data, crack opening displacement data, cyclic loading times and crack length data; according to a preset validity verification condition, performing validity verification on the obtained loading and unloading test data, and screening and determining key parameter data for calculating crack arrest toughness; calculating crack arrest toughness data according to preset conditions, the key parameter data and the physical parameters of the sample; the testing method is simple, low in cost and high in efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of material performance testing, and specifically relates to a simplified testing method, prediction method and prediction system for material crack arrest toughness, providing accurate testing and evaluation technical support for the safety assessment of key nuclear power equipment. Background Art

[0002] In nuclear power plants, the safe operation of critical equipment such as the reactor pressure vessel (RPV) and steam generator (SG) is crucial to preventing catastrophic accidents. To meet these requirements, pressure vessel materials must be able to resist brittle fracture (i.e., rapid crack propagation) under high external loads and internal stresses, while also being able to inhibit crack propagation. This capability is particularly important when the material has initial defects or cracks are generated during the manufacturing process, effectively preventing fatal accidents.

[0003] Furthermore, the impact toughness of some large forgings (such as the central area of the thick-walled cylinder and lower head) does not meet regulatory requirements. In conjunction with the long-life material performance requirements of the RCC-M specification, "Rules for the Design and Construction of Mechanical Equipment for Nuclear Island of Pressurized Water Reactor Nuclear Power Plants," the risk of fracture toughness degradation caused by thermal aging needs to be focused on. Such defects can cause brittle fracture of key pressure-bearing components during long-term service, significantly reducing crack tolerance, especially under transient conditions. The ASTM E1221-23 standard provides a standard crack arrest fracture toughness test method, but this method is complex, time-consuming, and costly, making it unsuitable for rapid engineering testing. Summary of the Invention

[0004] In view of the above shortcomings of the prior art, the object of the present invention is to provide a simplified testing method, prediction method and prediction system for material crack arrest toughness that is simple, low-cost and highly efficient.

[0005] To achieve the above and other related purposes, the present invention provides a simplified testing method for crack arrest toughness of a material, comprising the following steps:

[0006] Obtain the crack arrest toughness specimen of the target material containing prefabricated cracks and the physical parameters of the specimen under preset conditions;

[0007] Under preset conditions, multiple loading and unloading crack arrest toughness tests are performed on the specimen using an incomplete unloading method to obtain loading and unloading test data during each loading and unloading process. The loading and unloading test data includes load data, crack opening displacement data, number of cyclic loading cycles, and crack length data.

[0008] According to preset validity verification conditions, the obtained loading and unloading test data are validated, and key parameter data for calculating crack arrest toughness are screened and determined;

[0009] The crack arrest toughness data is calculated based on preset conditions, key parameter data, and physical parameters of the sample.

[0010] In one embodiment of the present invention, in the step of obtaining a crack arrest fracture toughness specimen of a target material containing prefabricated cracks and the physical parameters of the specimen under preset conditions, the physical parameters include:

[0011] Specimen width, specimen thickness, specimen crack plane net thickness, specimen notch length, and elastic modulus and yield strength of the target material under preset test temperature conditions.

[0012] In one embodiment of the present invention, the step of performing multiple loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner under preset conditions to obtain loading and unloading test data during each loading and unloading process includes:

[0013] According to the physical parameters of the specimen, the crack mouth opening displacement for each loading is calculated;

[0014] Under the conditions of preset test temperature and preset loading rate, the specimen is subjected to multiple cycles of loading and unloading crack arrest toughness test. When the load reaches the calculated crack mouth opening displacement value in each cycle, loading is stopped and unloading is started. Unloading is stopped each time when the unloading reaches the range of 0.2%-10% of the current loading range until crack initiation and crack arrest behavior occur.

[0015] During each loading and unloading process, the crack mouth opening displacement data is collected in real time through the displacement meter, and the loading load data is collected in real time through the sensor;

[0016] The load-crack mouth opening displacement curves of a plurality of specimens are drawn according to the loading load data and the displacement value data.

[0017] In one embodiment of the present invention, the step of validating the obtained loading and unloading test data according to preset validity verification conditions and screening and determining key parameter data for calculating the crack arrest toughness value includes:

[0018] At least five valid test data at different temperatures or at the same temperature are screened out based on the load-crack mouth opening displacement curve of the specimen and preset validity verification conditions, wherein the preset validity verification conditions are verification conditions related to crack extension, unbroken ligaments, and specimen thickness;

[0019] Based on the effective test data, key parameter data for calculating the crack arrest toughness result are determined. The key parameter data include the maximum load, the maximum crack opening displacement, the number of cyclic loading cycles and the crack length in each cyclic loading.

[0020] In one embodiment of the present invention, in the step of selecting at least five valid test data at different temperatures or the same temperature based on the load-crack mouth opening displacement curve of the specimen and the preset validity verification conditions, wherein the preset validity verification conditions are verification conditions related to the crack extension amount, the unbroken ligament and the specimen thickness, the preset validity verification conditions include:

[0021] The crack extension must satisfy the following formula: a a -a0≥βW N ;

[0022] The unbroken ligament must satisfy the following formula: Wa a ≥0.15W, Wa a ≥1.25(K a / R Yd ) 2 ;

[0023] The thickness of the specimen must satisfy the following formula: B≥(K a / R Yd ) 2 ;

[0024] Among them, a a is the average arrest crack length, K a is the crack arrest fracture toughness, R Yd is the dynamic yield strength, a0 is the length of the specimen notch, W is the specimen width, W N is the notch width, β is the correction factor related to the material size; β is the correction factor related to the material size, and a value between 1.5 and 2.0 is selected according to the sample structure.

[0025] In one embodiment of the present invention, the step of calculating the crack arrest toughness value data based on the preset conditions, key parameter data, and physical parameters of the sample includes:

[0026] The loading rate v of the i-th test is calculated according to the following formula i Crack arrest toughness

[0027]

[0028] Where, x = a / W, a is the length of the pre-crack of the specimen (mm), W is the width of the specimen (mm); T j is the test temperature of the jth test (℃), is the maximum opening displacement of the crack mouth in the test (mm), is the maximum load value in the test (kN), v i is the loading rate of the i-th test (mm / min), n iis the number of cyclic loading before crack arrest in the i-th test (times), A, B, C and D are four constants, and i and j are integers.

[0029] In one embodiment of the present invention, when the material of the sample is 18MND 5 steel, the crack arrest toughness The constants in the calculation formula are: A takes a value between 0.01 and 0.05, B takes a value between 1.0×10 4 to 2.0×10 4 C takes values between 0.01 and 0.05 and D takes values between -6 and -11.

[0030] In one embodiment of the present invention, in the step of performing multiple loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner under preset conditions to obtain loading and unloading test data during each loading and unloading process, a Shimadzu testing machine is used to perform loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner.

[0031] In one embodiment of the present invention, the sample is subjected to a plurality of cycles of loading and unloading crack arrest toughness tests under the conditions of a preset test temperature and a preset loading rate. When the load reaches the calculated crack mouth opening displacement value in each cycle, the loading is stopped and the unloading is started. The unloading is stopped each time the load reaches the range of 0.2%-10% of the current loading range until the crack initiation and crack arrest behavior occur.

[0032] The loading rate in the preset loading rate condition is greater than the standard loading rate, wherein the preset loading rate range is within a range of 2 mm / min to 24 mm / minn.

[0033] To achieve the above and other related purposes, the present invention provides a method for predicting crack arrest toughness of a material, comprising the following steps:

[0034] Obtaining crack arrest toughness value data of the sample and test temperature data under preset conditions according to the simplified test method for crack arrest toughness of the material;

[0035] Based on the crack arrest toughness value data and the test temperature data under the preset conditions, the crack arrest reference temperature data is calculated using the maximum likelihood statistical method;

[0036] Based on the crack arrest reference temperature data and crack arrest toughness value data, the master curve-like method is used to predict the crack arrest toughness of the target material at different temperatures.

[0037] In one embodiment of the present invention, the step of calculating the crack arrest reference temperature data based on the crack arrest toughness value data and the test temperature data under preset conditions is calculated by the following formula:

[0038]

[0039] Among them, K ca-S-j is the jth sample at the test temperature T j The crack arrest toughness at , j is the number of specimens, T Kca is the reference temperature for crack arrest.

[0040] In one embodiment of the present invention, the step of predicting the crack arrest toughness of the target material at different temperatures based on the crack arrest reference temperature data and the crack arrest toughness value data in combination with a master curve method includes:

[0041] Based on the crack arrest reference temperature data, crack arrest toughness value data and the following formula, a prediction curve of the material's crack arrest toughness changing with temperature is drawn:

[0042] K ca-p =A1+A2*(A3*exp(TT Kca ));

[0043] Among them, A1, A2 and A3 are the constants of the prediction curve equation, T Kca is the reference temperature for crack arrest.

[0044] In one embodiment of the present invention, when the material of the sample is 18MND 5 steel, in the formula required for drawing the crack arrest toughness prediction curve, the constant values are: A1 takes a value between 70 and 80, A2 takes a value between 5 and 8, and A3 takes a value between 0.1 and 0.5.

[0045] To achieve the above-mentioned and other related purposes, the present invention provides a material crack arrest toughness prediction system, comprising:

[0046] Test data acquisition unit, which obtains the physical parameters of the sample under preset conditions;

[0047] A test control unit, under preset conditions, performs multiple loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner to obtain loading and unloading test data during each loading and unloading process, wherein the loading and unloading test data includes load data, crack opening displacement data, number of cyclic loading cycles, and crack length data;

[0048] A data processing unit verifies the validity of the obtained loading and unloading test data according to preset validity verification conditions, and screens and determines key parameter data for calculating crack arrest toughness;

[0049] Calculate the crack arrest toughness data based on preset conditions, key parameter data, and physical parameters of the sample;

[0050] Based on the crack arrest toughness value data and the test temperature data under the preset conditions, the crack arrest reference temperature data is calculated using the maximum likelihood statistical method;

[0051] Based on the crack arrest reference temperature data and crack arrest toughness value data, the master curve-like method is used to predict the crack arrest toughness of the target material at different temperatures.

[0052] In summary, the simplified test method for material crack arrest toughness provided by the present invention relies on low-cost test equipment and simple operation procedures, and realizes simplified measurement of material crack arrest toughness under low-temperature environment through incomplete unloading technology, which significantly reduces the difficulty and time cost of test operation; this method breaks through the limitations of traditional test conditions, and provides highly reliable basic data support for the full life cycle safety assessment of key nuclear power equipment, effectively solving the engineering test problem of crack arrest toughness of low-alloy steel under complex working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0054] Figure 1 is a flow chart of a method in one embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of the front structure of a sample in one embodiment of the present invention;

[0056] Figure 3 A bottom view of a sample in one embodiment of the present invention;

[0057] Figure 4 A technical roadmap in one embodiment of the present invention;

[0058] Figure 5 : is a crack arrest test curve (load-crack mouth opening displacement curve) in one embodiment of the present invention;

[0059] Figure 6 A deviation diagram of a prediction curve and data prediction points in one embodiment of the present invention;

[0060] Figure 7 A finite element analysis simulation model (including mesh) in the analysis in one embodiment of the present invention;

[0061] Figure 8 A cloud diagram of finite element analysis simulation results in an analysis according to an embodiment of the present invention;

[0062] Description of component numbers: first hole 11, knife edge 12. DETAILED DESCRIPTION

[0063] The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following examples and the features in the examples can be combined with each other unless they conflict. It should also be understood that the terms used in the examples of the present invention are for the purpose of describing specific embodiments, not for the purpose of limiting the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0064] When numerical ranges are given in the examples, it should be understood that unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be used. Unless otherwise defined, all technical and scientific terms used herein are consistent with the prior art as understood by those skilled in the art and the description of the present invention. Any prior art methods, devices, and materials similar or equivalent to those described in the examples of the present invention may also be used to implement the present invention.

[0065] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0066] See also Figure 1-8 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0067] The material crack arrest toughness prediction method can be applied to one or more electronic devices, which are devices that can automatically perform numerical calculations and / or information processing according to pre-set or stored instructions, and whose hardware includes but is not limited to microprocessors, application-specific integrated circuits, programmable gate arrays, digital processors, embedded devices, etc.

[0068] The electronic device may further include a network device and / or a user device, wherein the network device includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud based on cloud computing consisting of a large number of hosts or network servers.

[0069] The ASTM E1221-23 standard provides a test method for crack arrest fracture toughness. The cyclic loading and unloading process places extremely high demands on the dynamic response accuracy of the testing machine, the dimensional accuracy of the specimen processing, the synchronization of the data acquisition system, and the equipment functionality. Furthermore, there is a lack of publicly available literature on the prediction of crack arrest fracture toughness for nuclear power materials. In this case, the parameters that fundamentally influence crack arrest are loading rate, temperature, and specimen structure. From a mechanistic perspective, the key influencing parameters include loading rate (affecting the evolution of the plastic zone at the crack tip), temperature (through the ductile-brittle transition effect, which influences the competition between brittle and ductile fracture), and specimen structure (size effect). The crack arrest toughness of the target material can be determined using an incomplete unloading curve, avoiding the high cost of the traditional single-specimen, multi-cycle method.

[0070] The maximum likelihood statistical method is a parameter estimation method based on a probability model. By maximizing the "likelihood function", the optimal estimate of the unknown parameters is obtained. This method can be used to predict the crack arrest toughness at different temperatures. The maximum likelihood statistical method is a parameter estimation method based on a probability model. Its core is to maximize the "likelihood function" of the observed data (that is, the joint probability density of the data under given parameters) to infer the optimal value of the unknown parameters that is most likely to generate these data. In the field of material fracture mechanics, maximum likelihood estimation can be used to construct and evaluate temperature-dependent probability models. This method can be effectively applied to the prediction and uncertainty quantification of crack arrest toughness at different temperatures. Therefore, in this case, the crack arrest fracture test method of thick-walled pressure vessels was studied in depth in engineering practice to establish a simple test method to provide theoretical support and technical guarantee for the safe operation of nuclear power equipment.

[0071] The master-curve-like method, based on fracture mechanics theory, obtains data on the material's crack arrest toughness under varying loading conditions by testing a series of specimens of varying sizes and shapes. It assumes a functional relationship between the material's crack arrest toughness and factors such as the specimen's geometry and loading rate. By analyzing and fitting the test data, a master-curve-like method is established to describe the material's crack arrest toughness characteristics.

[0072] In structures with gradients in toughness or stress, cracks may initiate in regions of low toughness or high stress (or both) and arrest in regions of higher toughness or lower stress (or both). The crack arrest toughness of the materials discussed in this case is crucial for performance in materials research and development, such as determining the effects of metallurgical variables (such as composition or heat treatment) or manufacturing processes (such as welding or forming) on the crack arrest ability of new or existing materials. In design, this helps with material selection and determines the location and size of reinforcements and crack arrest plates.

[0073] like Figure 2-3 As shown, where H is the sample height, L is the displacement distance of the displacement meter, and W N is the notch width, D is the loading port diameter, S is the single-side groove depth; B is the specimen thickness, W is the specimen width, and a0 is the starting notch length or initial crack size of the specimen.

[0074] See also Figure 1-3 The present invention provides a simplified method for obtaining the crack arrest toughness of a material. The technical roadmap is as follows: Figure 4 As shown, the following steps are included:

[0075] S1: Obtaining a crack arrest toughness specimen of a target material containing prefabricated cracks and physical parameters of the specimen under preset conditions; wherein the step of obtaining the crack arrest toughness specimen of the target material containing prefabricated cracks comprises:

[0076] S11: Obtaining a specimen blank for a crack arrest fracture toughness test of a target material;

[0077] It should be noted that the material is, for example, high-strength low-alloy steel or other materials that meet the test requirements.

[0078] The specimens for the standard crack arrest fracture toughness test are processed according to ASTM E1221-23 "Standard Test Method for Determination of Plane Strain Crack Arrest Fracture Toughness KIa of Ferritic Steels". The specimen thickness should be sufficient to ensure that the crack front reaches plane strain conditions.

[0079] S12: A side groove is made on the obtained sample blank, and the depth of the side groove is at least one-eighth of the thickness of the sample blank; it should be noted that the side groove should be processed after the brittle weld is deposited to control the crack to expand in a specified plane. Therefore, it is necessary to make a side groove on the sample, and the side groove should be processed after the brittle weld is deposited to obtain a rapid expansion of the crack front with an approximately straight line, while the crack arrest section plane is stretched and separated;

[0080] S13: Prefabricate fatigue cracks in the side-grooved specimen blanks, with a crack length of 1.5 mm to 2 mm, to obtain arrest fracture toughness specimens.

[0081] The crack arrest toughness test specimen size of the present invention is as follows: Figure 2-3shown.

[0082] To facilitate crack initiation during cyclic loading and unloading, the GB / T 21143-2014 standard was used to pre-initiate cracks using fatigue loading. The maximum fatigue cycle load was 3.5 kN, the stress ratio was 0.1, and the frequency was 15 Hz. The pre-initiated fatigue crack length was controlled within the range of 1.5-2 mm.

[0083] The step of obtaining the physical parameters of the sample under preset conditions includes:

[0084] S14: Obtaining the ductile-brittle transition temperature data of the target sample;

[0085] The test temperature is selected by first obtaining the non-ductile ductile-brittle transition temperature (TNDT) of the material according to the standard GB / T 229-2020 "Charpy pendulum impact test method for metallic materials".

[0086] S15: Determine the test temperature of the sample according to the ductile-brittle transition temperature data of the material;

[0087] In this test, the test temperature is required to be lower than the TNDT value by 50±10℃ to ensure that the crack arrest toughness of the material can be measured under quasi-static conditions.

[0088] The physical parameters include: sample width W, sample thickness B, sample crack plane net thickness B N , specimen notch length a0, and the elastic modulus E and yield strength R of the target material under the preset test temperature conditions Y , where the sample width W is generally in the range of 2B≤W≤8B.

[0089] S2: Under preset conditions, the sample is subjected to multiple loading and unloading crack arrest toughness tests using an incomplete unloading method to obtain loading and unloading test data during each loading and unloading process. The loading and unloading test data includes load data F, crack opening displacement data V, number of cyclic loading times n, and crack length data a. a ;

[0090] S21: Test preparation. During the test, use a wedge with a small taper angle and a split pin arrangement. To reduce the impact of friction on the test results, it is necessary to select a suitable low-temperature lubricant, such as polytetrafluoroethylene strips or molybdenum disulfide (dry and grease). Frosted treatment (sandblasting) of the sliding surface helps to avoid scratches.

[0091] Among them, the cotter pin must be long enough to contact the entire thickness of the specimen, and the cotter pin radius must be large enough to avoid plastic indentation of the specimen, and the wedge must be long enough to produce the expected maximum opening displacement. At the same time, it is necessary to ensure that no solidification occurs during the cooling process to prevent solidification between the specimen and the fixture. The cooling and holding time are determined according to the overall thickness of the specimen, the lower pad, and the upper pressure plate. For every 25mm increase in the total thickness, the holding time needs to be increased by half an hour. In each separate test, the holding time is calculated from the time when the temperature in the temperature box reaches the specified test temperature. The shortest holding time is 30 minutes. When each specimen is tested, it is necessary to ensure that the holding time meets the minimum requirement to ensure uniform temperature distribution in the thickness direction of the specimen.

[0092] S22: Loading and unloading test under displacement control conditions, at the selected loading rate v i (mm / min) conditions,

[0093] By pressing the wedge into the cotter pin, an opening force is applied to the crack notch of the specimen to expand the crack. Each time a specific crack mouth opening displacement value is reached, loading is stopped and unloading begins. The crack mouth opening displacement value to be reached in each unloading step is shown in formula (1). Based on the physical parameters of the specimen, the crack mouth opening displacement for each loading is calculated. In this step, the crack mouth opening displacement (V n ) max :

[0094]

[0095] Where, E is the elastic modulus of the material at the test temperature (MPa), n is the number of unloading cycles (times), V n is the crack mouth opening displacement required for the nth unloading (mm), R Y is the yield strength of the material at the test temperature (MPa), W is the width of the specimen (mm), B is the thickness of the specimen (mm), and B N is the net thickness of the crack plane of the specimen (mm), f(x) is a function related to the structure; the value range of the specimen structure adopted in the present invention is between 0.1 and 0.5, for example, 0.1 or 0.2 or 0.3 or 0.4 or 0.5; wherein, the function of the specimen notch is to generate crack initiation under opening displacement (or wedging force), thereby allowing crack propagation of an appropriate length before crack arrest; different materials require different specimen notch preparations; the a0 value of the starting notch is usually in the range of 0.30W≤a0≤0.40W, but sometimes it is useful to use a value as low as 0.20W; a lower initial a0 / W value will result in a faster and more significant decrease in the crack driving force during crack propagation, which helps to arrest the crack at a shorter final crack length.

[0096] Furthermore, in this test, a Shimadzu testing machine was used to conduct a loading-unloading crack arrest toughness test on the specimens using an incomplete unloading method. Shimadzu testing machines are materials testing equipment and come in a variety of models, such as electronic universal testing machines, desktop single-column testing machines, and hydraulic universal testing machines. It should be understood that other testing machines that meet the requirements of this case could also be used.

[0097] Furthermore, the loading rate in the preset loading rate condition is greater than the standard loading rate, wherein the preset loading rate range is within 1 mm / min to 25 mm / minn, for example, 2 mm / min or 5 mm / min or 10 mm / min or 15 mm / min or 20 mm / min.

[0098] It should be noted that by additionally considering the effect of loading rate on crack arrest toughness and adopting a loading rate beyond the standard test method, the temperature and test time of the crack arrest test are reduced. The present invention allows a loading rate range of 2-24 mm / min.

[0099] S23: Under the conditions of preset test temperature and preset loading rate, the specimen is subjected to multiple cyclic tests of loading and unloading crack arrest toughness test. When the load reaches the calculated crack mouth opening displacement value in each cycle, loading is stopped and unloading is started. Unloading is stopped each time the unloading reaches the range of 0.1%-20% of the current loading range. The specific load loading range is 0.1% or 2% or 3% or 4% or 5% or 6% or 7% or 8% or 9% or 10% or 11% or 12% or 13% or 14% or 15%, until crack initiation and crack arrest behavior occur. It should be noted that, based on the cyclic loading-unloading process required by the standard, since some equipment cannot completely overcome the influence of friction between loading fixtures on the test test, this case adopts an incomplete unloading method to perform loading-unloading cycles, and tests are carried out under incomplete unloading conditions until crack initiation and crack arrest behavior occur. That is, force is applied to the wedge until a rapid crack initiates, or until the crack opening displacement (measured by a clip gauge) reaches a predetermined value; if rapid fracture does not initiate before the recommended maximum displacement is reached, the specimen is unloaded, but incompletely, and then reloaded in the same manner as before, and force is applied again until a rapid crack initiates or the opening displacement reaches a specified value; in each loading cycle, the allowed recommended maximum opening displacement value is increased sequentially until a rapid crack initiates or the test is terminated; wherein the recommended maximum opening displacement value is calculated by the above formula (1).

[0100] S24: During each loading and unloading process, the displacement meter collects the crack mouth opening displacement data in real time, and the sensor collects the loading load data in real time. The crack arrest test curve (load-crack mouth opening displacement curve) in this case is as follows: Figure 5 As shown;

[0101] It should be noted that, in the test data collection and curve recording, during the cyclic loading-unloading process, a low-temperature extensometer installed on the blade of the specimen was used to collect and measure the crack mouth opening displacement data caused by the wedge method in real time. At the same time, the Shimadzu testing machine system was used to collect the loading load in the crack arrest test in real time; the displacement meter should measure the opening displacement at 0.25W from the load line (away from the crack tip). It should be understood that other instruments that meet the use requirements can also be used in this case, such as the (Nilos) ultra-light extensometer.

[0102] It should be further explained that the use of Shimadzu testing machine can avoid the use of a complicated complete unloading process. The Shimadzu testing machine can reduce the difficulty of crack arrest toughness testing and save testing costs. Even if the testing machine fails to achieve complete unloading conditions, the crack arrest toughness test of the material can still be completed, and test data that meets the requirements of the material crack arrest toughness calculation can be obtained.

[0103] S25: drawing load-crack mouth opening displacement curves of a plurality of specimens according to the loading load data and displacement value data; it should be noted that a data processing unit may perform preliminary analysis to generate and record load-crack mouth opening displacement curves.

[0104] S3: According to preset validity verification conditions, the obtained loading and unloading test data are validated, and key parameter data for calculating crack arrest toughness are screened and determined;

[0105] S31: Filter out at least five valid test data at different temperatures or the same temperature based on the load-crack mouth opening displacement curve of the specimen and preset validity verification conditions, wherein the preset validity verification conditions are verification conditions related to crack extension, unbroken ligaments, and specimen thickness; the preset validity verification conditions are shown in Table 1 below:

[0106] Table 1 Criteria for the effective application of crack arrest fracture test data

[0107]

[0108] Among them, a a is the average arrest crack length, K a is the crack arrest fracture toughness, R Yd is the dynamic yield strength, a0 is the length of the specimen notch, W is the specimen width, W N is the notch width, β is the correction factor related to the material size; β is the correction factor related to the material size, and a value between 1.5 and 2.0 is selected according to the sample structure.

[0109] It should be noted that in order to ensure the reliability of the test data, it is necessary to conduct data validity judgment so that the test data meets the requirements of the application criteria. The judgment basis is shown in Table 1, and multiple crack arrest tests need to be performed at different temperatures (or the same temperature). Due to the difference between the incomplete unloading method and the standard method, in order to ensure the accuracy of the subsequent test data, at least five or more valid data at different temperatures (or the same temperature) need to be obtained; among them,

[0110] Arrest crack size a a It is defined by the average of multiple measurements made on the heat-stained fracture surface at the following locations: the center of the specimen thickness (mid-thickness) and the mid-point between the mid-thickness and the bottom of the side groove on each side. Due to the irregularity of the crack front, it may be difficult to determine the crack length at a specific location. It is recommended to use the center as the reference at each measurement location and N The visual average measurement is made on a strip of / 4. For the crack arrest, the position of the crack arrest can be marked by heat coloring at a temperature of 260℃ to 370℃. When measuring the crack arrest size, the heat-colored fracture surface should be checked first to determine whether there are any irregularities sufficient to exclude the test results. Tunneling, failure to follow the side groove on one or both sides, and the presence of large unbroken ligaments on the fracture surface can all lead to K a The wrong result.

[0111] S32: Based on the effective test data, determine the key parameter data for calculating the crack arrest toughness results. The key parameter data affecting the calculation of the incomplete unloading test method include the maximum load Fm, the maximum crack opening displacement Vm, the number of cyclic loading times n and the crack length a (mm) in each cyclic loading.

[0112] It should be noted that in the analysis of the crack arrest toughness test data, the load-crack mouth opening displacement curves obtained from multiple tests were analyzed to obtain the key parameter data for calculating the crack arrest toughness results.

[0113] By obtaining the key parameter data, the material is calculated at the selected loading rate v i The crack arrest toughness obtained using the simplified test method The details are as follows:

[0114] S4: Calculate the crack arrest toughness data based on the preset conditions, key parameter data, and physical parameters of the sample. In this step, the loading rate v of the i-th test is calculated according to the following formula: i Crack arrest toughness The calculation formula is as follows:

[0115]

[0116] Where, x = a / W, a is the length of the pre-crack of the specimen (mm), W is the width of the specimen (mm); T j is the test temperature of the jth test (℃), is the maximum opening displacement of the crack mouth in the test (mm), is the maximum load value in the test (kN), v i is the loading rate of the i-th test (mm / min), n i is the number of cyclic loading before crack arrest in the i-th test (times), A, B, C and D are four constants, and i and j are integers.

[0117] As an optional embodiment of this case, when the material of the sample is 18MND 5 steel, the crack arrest toughness The constants in the calculation formula are: A takes a value between 0.01 and 0.05, B takes a value between 1.0×10 4 to 2.0×10 4 C takes a value between 0.01 and 0.05 and D takes a value between -6 and -10, wherein A is, for example, 0.01 or 0.02 or 0.03 or 0.04; B is, for example, 1.0×10 4 or 1.2×10 4 or 1.3 × 10 4 or 1.4×10 4 or 1.1×10 4 or 1.5×10 4 or 1.6×10 4 or 1.7 × 10 4 or 1.8×10 4 or 1.9×10 4 or 2.0×10 4 ; C is, for example, 0.01 or 0.02 or 0.03 or 0.04 or 0.05; A is, for example, -6 or -7 or -8 or -9 or -10 or -11.

[0118] The present invention provides a method for predicting crack arrest toughness of a material, comprising the following steps:

[0119] Acquire crack arrest toughness value data and test temperature data under preset conditions according to the simplified method for acquiring crack arrest toughness of the material;

[0120] S5: Calculate crack arrest reference temperature data using the maximum likelihood statistical method based on the crack arrest toughness value data and the test temperature data under preset conditions;

[0121] The step of calculating the crack arrest reference temperature data based on the crack arrest toughness value data and the test temperature data under the preset conditions is calculated by the following formula:

[0122]

[0123] Among them, K ca-s-j is the jth sample at the test temperature T j The crack arrest toughness at , j is the number of specimens, T Kca is the reference temperature for crack arrest.

[0124] It should be noted that in the calculation of the crack arrest reference temperature, the crack arrest toughness tolerance range is based on the scatter of data. The statistical maximum likelihood method is used to perform statistical analysis on the crack arrest toughness results and set the crack arrest reference temperature T Kca Replaces the traditional standard reference temperature T0.

[0125] S6: Based on the crack arrest reference temperature data and the crack arrest toughness value data, a master curve-like method is used to predict the crack arrest toughness of the target material at different temperatures. This step includes the following steps:

[0126] According to the crack arrest reference temperature data, crack arrest toughness value data and the following formula, the crack arrest toughness K of the material is plotted. ca-p Prediction curve with temperature change:

[0127] K ca-p =A1+A2*(A3*exp(TT Kca )) (4)

[0128] Among them, A1, A2 and A3 are constants of the prediction curve equation.

[0129] It should be noted that the prediction curve of the present invention and the data prediction point deviation analysis Figure 6 As shown; in the process of drawing the crack arrest toughness prediction curve, the reference material fracture toughness main curve prediction method is used to perform data processing and analysis using the calculation results of the crack arrest reference temperature data and the crack arrest toughness value data, and the crack arrest toughness of the material at different temperatures is predicted. The prediction curve of the crack arrest toughness changing with temperature is specifically shown in the above formula (4).

[0130] Furthermore, in step S22, due to the unavoidable friction in the test system, during the unloading process of cyclic loading and unloading, unloading is stopped when unloading reaches 0.2%-10% of the load range of the test equipment, and unloading is performed after loading to the maximum crack mouth opening displacement of each step of loading specified by the standard.

[0131] Furthermore, in step S31, the correction coefficient β related to the material size selects different values according to different sample structures while meeting the data validity application criteria, and the value range is between 1.4-2.0. For the sample size selected in the present invention, the value is, for example, 1.4 or 1.5 or 1.6 or 1.7 or 1.8.

[0132] Furthermore, in step S4, the crack arrest toughness calculation formula is used to obtain the material crack arrest toughness through the incomplete unloading cyclic loading curve in the test curve that does not meet the standard test conditions, and to predict the crack arrest toughness of the material at all temperatures through statistical methods. For the numerical calculation of the crack arrest toughness of 18MND 5 steel for nuclear power, the constants of the present invention are A taking a value between 0.01 and 0.05, B taking a value of 1.0×10 4 to 2.0×10 4 C takes values between 0.01 and 0.05 and D takes values between -6 and -11.

[0133] Furthermore, in step S6, for the crack arrest toughness prediction curve formula for 18MND 5 steel for nuclear power, the constants in the crack arrest toughness prediction curve formula are: A1 takes a value between 70 and 80, A2 takes a value between 5 and 8, and A3 takes a value between 0.1 and 0.5, where, for example, A1 is 70 or 71 or 72 or 73 or 74 or 75 or 76 or 77 or 78 or 78 or 80; A2 is, for example, 5 or 6 or or 7 or 8; and A3 is 0.1 or 0.2 or 0.3 or 0.4 or 0.5.

[0134] The present invention provides a material crack arrest toughness prediction system, comprising a test data acquisition unit, a test control unit and a data processing unit;

[0135] The test data acquisition unit collects physical parameters of the sample under preset conditions; for example, the physical parameters of the sample can be measured manually and input into the test equipment manually, or the test equipment's own measurement sensor can automatically collect data; for example, the size can be measured by a laser micrometer or an electronic vernier caliper integrated module;

[0136] Under preset conditions, the test control unit controls the testing machine to perform multiple loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner, and detects the loading and unloading test data through its own detection module, or collects the loading and unloading test data through the test data acquisition unit to obtain the loading and unloading test data in each loading and unloading process, so as to obtain the loading and unloading test data in each loading and unloading process, wherein the loading and unloading test data includes load data, crack opening displacement data, number of cyclic loading cycles and crack length data; for example, a bidirectional force sensor can be used to collect load, a displacement meter can collect crack opening displacement data, and an acoustic emission sensor array can locate crack initiation and arrest points; a dual CCD camera can capture the crack tip strain field; and a counter can count the number of cyclic loading cycles.

[0137] The data processing unit verifies the validity of the obtained loading and unloading test data according to preset validity verification conditions, and screens and determines key parameter data for calculating crack arrest toughness;

[0138] Calculate the crack arrest toughness data based on preset conditions, key parameter data, and physical parameters of the sample;

[0139] Based on the crack arrest toughness value data and the test temperature data under the preset conditions, the crack arrest reference temperature data is calculated using the maximum likelihood statistical method;

[0140] Based on the crack arrest reference temperature data and the crack arrest toughness value data, the master curve method is used to predict the crack arrest toughness of the target material at different temperatures;

[0141] The test data acquisition unit, the test control unit, and the data processing unit are electrically or digitally connected, and relevant curves can be generated by a curve generator. Furthermore, a human-computer interaction interface can be included, where the terminal is controlled via a touch screen and the load-displacement curve and predicted curve are displayed in real time on the screen.

[0142] The present invention enables the crack arrest toughness of low alloy steel to be tested under conditions of low testing cost and simple operation of testing equipment. It innovatively proposes a simplified calculation method for obtaining the crack arrest toughness of materials at low temperatures under incomplete unloading conditions, which reduces the difficulty of the test, and the simple testing process also saves time costs. At the same time, a set of methods based on maximum likelihood statistics has been developed, which can predict the crack arrest toughness curve of the material with less data, providing reliable input parameter data for the safety assessment of key nuclear power equipment.

[0143] Implementation Cases:

[0144] The pressure-bearing components of the steam generator (SG) lower head of a pressurized water reactor nuclear power plant are analyzed as a case study. The material of this SG head is 18MND 5, and its chemical composition is shown in Table 2.

[0145] Table 2 Chemical composition of a certain 18MND 5 material

[0146]

[0147] Based on GB / T 228.1-2010 "Metallic materials tensile test part 1: test method at room temperature", the standard adopted for low temperature tensile test is GB / T 228.2-2015 "Metallic materials tensile test part 3: test method at low temperature". The 18MND 5 material tensile curve is obtained by testing the standard tensile specimen to obtain the mechanical properties, elastic modulus E and yield strength R of the material. Y The values are shown in Table 3.

[0148] Table 3 Low temperature test results of a low alloy steel at different temperatures

[0149]

[0150] 1) Standard crack arrest fracture toughness test specimen processing

[0151] The specimen blank size is determined according to ASTM E1221-23, and the specimen blank is processed to ensure the surface roughness and dimensional error requirements. Based on the standard requirements, two first holes 11 are drilled at the two ends of the front of the specimen to facilitate fatigue loading when prefabricating fatigue cracks; an additional cutting edge 12 is cut at the center of the front end to install the low-temperature extensometer. According to GB / T21143-2014, the fatigue crack length of the compact tensile specimen is expected to be 2.5 mm. Figure 2-3 shown.

[0152] 2) Fixture assembly

[0153] The overall installation layout of the loading system is that the specimen is placed on the pad, the load is applied to the wedge, and the wedge loading is achieved by moving the loading component of the test equipment; the pad should be thick enough to avoid contact between the wedge and the lower platform of the testing machine; a small-taper wedge is used in conjunction with a cotter pin, and the wedge length must be long enough to ensure that the crack opening displacement reaches the maximum value.

[0154] The extensometer was installed according to the extensometer installation method of ISO 12737-1996 to ensure that the installation method of the extensometer and the specimen did not change during the crack propagation process. After injecting liquid nitrogen into the insulation box, wait until the internal temperature of the low-temperature box reaches -110℃ and stabilizes, and then keep it warm for another half an hour.

[0155] 3) Obtaining load-displacement curve based on incomplete unloading

[0156] Set as Figure 5 The loading mode of the test equipment shown is displacement-controlled. The loading speed is controlled to maintain a constant load of 2 mm / min and 12 mm / min (according to the specification requirements of ASTM E1221-23, the displacement speed of the testing machine beam is 2-12 mm / min, and 2 mm / min is selected here). The wedge is installed in the upper chuck. As the loading device moves, the wedge loads the cotter pin. The crack opening displacement measured by the extensometer during the loading process and the load measured by the force sensor in the force system are recorded in real time to record the data points and draw a load-displacement curve.

[0157] 4) Data processing of load-crack mouth opening displacement curve test

[0158] According to Figure 5The test curve shown is used to obtain the key parameter data for calculating the crack arrest toughness results. The key parameter data that affect the calculation of the incomplete unloading test method include the maximum load Fm in each cyclic loading, the number of cyclic loading times n, the crack length a (mm), the maximum crack mouth opening displacement Vm, etc., and the crack arrest toughness of the material at the selected loading rate is calculated based on the obtained key parameter data. Among them, after obtaining 5-7 groups of data that meet the successful criterion of the crack arrest test, the data is fitted and analyzed, and the following crack arrest toughness can be obtained. Calculation formula:

[0159]

[0160] 5) Calculation of crack arrest fracture toughness prediction curve

[0161] Crack arrest toughness at different temperatures Substituting it into formula (6), with maximum likelihood estimation as the core methodological framework, for low-alloy steel used in thick-walled pressure vessels, the maximum likelihood method is used, combined with the test data, to obtain a normal distribution with logarithmic dispersion, and the numerical value XX of the crack arrest reference temperature data is obtained.

[0162]

[0163] Then the numerical value XX of the crack arrest reference temperature data is brought into equation (7) to predict the crack arrest toughness of the material at different temperatures, and the following is obtained: Figure 6 The full-temperature crack arrest toughness prediction curve is shown in the figure, which points out the crack arrest toughness values of the material at each temperature calculated by formula (5).

[0164] K ca-p =73+6.3*(0.2*exp(TT Kca )) (7)

[0165] Among them, T Kca is the crack arrest reference temperature T Kca , A1, A2 and A3 are constants of the prediction curve equation.

[0166] 6) Crack arrest behavior simulation analysis

[0167] Finally, ABAQUS software was used to establish Figure 7 The finite element model of the specimen with the same size is shown in the figure. The effect of stress wave caused by the instantaneous load of the wedge method on crack propagation is analyzed during the crack arrest process. The simulation results are shown in the figure below. Figure 8As shown in the figure, the stress wave propagation process generates tensile and compressive waves on the crack. After the crack is initiated by the wedge insertion method, these waves promote and inhibit crack propagation, respectively, causing the crack to accelerate and decelerate. Different loading speeds will cause different gravitational wave propagation phenomena, which have different effects on the overall crack arrest behavior.

[0168] The simplified test method for the crack arrest toughness of low alloy steel with incomplete unloading during cyclic loading and unloading of the present invention overcomes many inconveniences in existing specifications: 1) ASTM E1221-23 requires the preparation of high-precision pre-crack specimens, and the use of side grooves and wedge-loaded specimens to achieve planar tensile separation. This destructive test results in high material costs for a single test and a long test cycle; 2) The standard does not cover test methods for the entire temperature range, and each test can only evaluate the crack arrest toughness at a single temperature point. If multi-temperature data is to be obtained, it is necessary to rely on an independent environmental chamber (such as a liquid nitrogen refrigeration system) to conduct multiple tests. In the nuclear industry, crack arrest fracture toughness test methods and fracture toughness data have clear application areas and broad market prospects.

[0169] The present invention also provides a computer-readable storage medium having computer-readable instructions stored thereon. When the computer-readable instructions are executed by a processor of a computer, the computer is caused to execute the steps of the method.

[0170] Among them, the memory includes at least one type of readable storage medium, and the readable storage medium includes a flash memory, a mobile hard disk, a multimedia card, a card-type memory (for example: SD or DX memory, etc.), a magnetic memory, a disk, an optical disk, etc. In some embodiments, the memory can be an internal storage unit of an electronic device, such as a mobile hard disk of the electronic device. In other embodiments, the memory can also be an external storage device of an electronic device, such as a plug-in mobile hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the electronic device. Furthermore, the memory can also include both an internal storage unit and an external storage device of the electronic device. The memory can not only be used to store application software and various types of data installed in the electronic device, such as the code of the simplified material crack arrest toughness acquisition method program, etc., but can also be used to temporarily store data that has been output or is to be output.

[0171] In some embodiments, the processor may be composed of an integrated circuit, for example, a single packaged integrated circuit, or a plurality of packaged integrated circuits with the same or different functions, including one or more central processing units (CPUs), microprocessors, digital processing chips, graphics processors, and a combination of various control chips. The processor is the control core (Control Unit) of the electronic device, connecting the various components of the entire electronic device using various interfaces and lines, and executing the programs or modules stored in the memory (for example, executing the simplified method for obtaining the crack arrest toughness of materials, etc.), as well as calling the data stored in the memory, to perform various functions of the electronic device and process data.

[0172] The processor executes the operating system of the electronic device and various installed applications. The processor executes the applications to implement the steps of the simplified method for obtaining the crack arrest toughness of materials, such as the steps shown in the simplified method for obtaining the crack arrest toughness of materials.

[0173] Exemplarily, the computer program may be divided into one or more modules, which are stored in the memory and executed by the processor to implement the present invention. The one or more modules may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program in the electronic device. For example, the computer program may be divided into multiple modules.

[0174] The integrated unit implemented as a software functional module can be stored in a computer-readable storage medium. The software functional module, stored in a storage medium, includes instructions for causing a computer device (which can be a personal computer, computing device, or network device, etc.) or a processor to perform some of the functions of the simplified method for obtaining the crack arrest toughness of a material as described in various embodiments of the present invention.

[0175] The bus may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. The bus is configured to enable connection and communication between the memory and at least one processor, etc.

[0176] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A simplified test method for crack arrest toughness of materials, characterized in that: The following steps are involved: Obtain the crack arrest toughness specimen of the target material containing prefabricated cracks and the physical parameters of the specimen under preset conditions; Under preset conditions, multiple loading and unloading crack arrest toughness tests are performed on the specimen using an incomplete unloading method to obtain loading and unloading test data during each loading and unloading process. The loading and unloading test data includes load data, crack opening displacement data, number of cyclic loading cycles, and crack length data. According to preset validity verification conditions, the obtained loading and unloading test data are validated, and key parameter data for calculating crack arrest toughness are screened and determined; The crack arrest toughness data is calculated based on preset conditions, key parameter data, and physical parameters of the sample.

2. The simplified testing method for crack arrest toughness of materials according to claim 1, characterized in that: In the step of obtaining a crack arrest fracture toughness specimen of the target material containing prefabricated cracks and the physical parameters of the specimen under preset conditions, the physical parameters include: Specimen width, specimen thickness, specimen crack plane net thickness, specimen notch length, and elastic modulus and yield strength of the target material under preset test temperature conditions.

3. The simplified testing method for crack arrest toughness of materials according to claim 1, characterized in that: The steps of performing multiple loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner under preset conditions to obtain loading and unloading test data during each loading and unloading process include: According to the physical parameters of the specimen, the crack mouth opening displacement for each loading is calculated; Under the conditions of preset test temperature and preset loading rate, the specimen is subjected to multiple cycles of loading and unloading crack arrest toughness test. When the load reaches the calculated crack mouth opening displacement value in each cycle, loading is stopped and unloading is started. Unloading is stopped each time when the unloading reaches the range of 0.2%-10% of the current loading range until crack initiation and crack arrest behavior occur. During each loading and unloading process, the crack mouth opening displacement data is collected in real time through the displacement meter, and the loading load data is collected in real time through the sensor; The load-crack mouth opening displacement curves of a plurality of specimens are drawn according to the loading load data and the displacement value data.

4. The simplified testing method for crack arrest toughness of materials according to claim 3, characterized in that: The step of validating the obtained loading and unloading test data according to preset validity verification conditions and screening and determining key parameter data for calculating the crack arrest toughness value includes: At least five valid test data at different temperatures or at the same temperature are screened out based on the load-crack mouth opening displacement curve of the specimen and preset validity verification conditions, wherein the preset validity verification conditions are verification conditions related to crack extension, unbroken ligaments, and specimen thickness; Based on the effective test data, key parameter data for calculating the crack arrest toughness result are determined. The key parameter data include the maximum load, the maximum crack opening displacement, the number of cyclic loading cycles and the crack length in each cyclic loading.

5. The simplified testing method for crack arrest toughness of materials according to claim 1, characterized in that: The step of calculating the crack arrest toughness value data based on the preset conditions, key parameter data, and physical parameters of the sample includes: The loading rate v of the i-th test is calculated according to the following formula i Crack arrest toughness Where, x = a / W, a is the length of the pre-crack of the specimen (mm), W is the width of the specimen (mm); T j is the test temperature of the jth test (℃), is the maximum opening displacement of the crack mouth in the test (mm), is the maximum load value in the test (kN), v i is the loading rate of the i-th test (mm / min), n i is the number of cyclic loading before crack arrest in the i-th test (times), A, B, C and D are four constants, i and j are integers; and / or, when the specimen is made of 18MND 5 steel, the crack arrest toughness The constants in the calculation formula are: A takes a value between 0.01 and 0.05, B takes a value between 1.0×10 4 to 2.0×10 4 C takes values between 0.01 and 0.05 and D takes values between -6 and -11.

6. The simplified testing method for crack arrest toughness of materials according to claim 1, characterized in that: In the step of performing multiple loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner under preset conditions to obtain loading and unloading test data during each loading and unloading process, a Shimadzu testing machine is used to perform loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner.

7. A method for predicting crack arrest toughness of a material, characterized in that: The steps include: Obtaining crack arrest toughness value data of the sample and test temperature data under preset conditions according to the simplified test method for crack arrest toughness of materials according to any one of claims 1 to 6; Based on the crack arrest toughness value data and the test temperature data under the preset conditions, the crack arrest reference temperature data is calculated using the maximum likelihood statistical method; Based on the crack arrest reference temperature data and crack arrest toughness value data, the master curve-like method is used to predict the crack arrest toughness of the target material at different temperatures.

8. The method for predicting crack arrest toughness of a material according to claim 7, characterized in that: The step of calculating the crack arrest reference temperature data based on the crack arrest toughness value data and the test temperature data under the preset conditions is calculated by the following formula: Among them, K ca-S-j is the jth sample at the test temperature T j The crack arrest toughness at , j is the number of specimens, T Kca is the reference temperature for crack arrest.

9. The method for predicting crack arrest toughness of a material according to claim 7, characterized in that: The step of predicting the crack arrest toughness of the target material at different temperatures based on the crack arrest reference temperature data and the crack arrest toughness value data in combination with the master curve method includes: According to the crack arrest reference temperature data, crack arrest toughness value data and the following formula, the crack arrest toughness K of the material is plotted. ca-P Prediction curve with temperature change: K ca-p =A1+A2*(A3*exp(T-T Kca )); Among them, T Kca is the crack arrest reference temperature, A1, A2 and A3 are the constants of the prediction curve equation; And / or, when the material of the specimen is 18MND 5 steel, in the formula required for drawing the crack arrest toughness prediction curve, the constants are: A1 takes a value between 70 and 80, A2 takes a value between 5 and 8, and A3 takes a value between 0.1 and 0.

5.

10. A material crack arrest toughness prediction system, characterized in that: include: Test data acquisition unit, which obtains the physical parameters of the sample under preset conditions; A test control unit, under preset conditions, performs multiple loading and unloading crack arrest toughness tests on the sample in an incomplete unloading manner to obtain loading and unloading test data during each loading and unloading process, wherein the loading and unloading test data includes load data, crack opening displacement data, number of cyclic loading cycles, and crack length data; A data processing unit verifies the validity of the obtained loading and unloading test data according to preset validity verification conditions, and screens and determines key parameter data for calculating crack arrest toughness; Calculate the crack arrest toughness data based on preset conditions, key parameter data, and physical parameters of the sample; Based on the crack arrest toughness value data and the test temperature data under the preset conditions, the crack arrest reference temperature data is calculated using the maximum likelihood statistical method; Based on the crack arrest reference temperature data and crack arrest toughness value data, the master curve-like method is used to predict the crack arrest toughness of the target material at different temperatures.

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