A method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel

Abstract

The present invention provides a method for constructing a prediction model for the high-order energy of the ductile-brittle transition of high-strength structural steel. By conducting Charpy impact tests, dynamic tearing tests and tensile tests, a correlation analysis is conducted on the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition, and a prediction model for the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition is established. The present invention establishes a correlation model between the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition and tensile performance characterization parameters through the correlation analysis of the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition. The prediction model can be established through the tensile performance parameters measured at room temperature, and can achieve quantitative evaluation of the high-order energy of the ductile-brittle transition of high-strength structural steel, providing a technical basis for the improvement and improvement of the toughness and fracture resistance design of high-strength structural steel. The prediction model has a clear physical mechanism, is simple to construct and is quick to use.

Description

Technical Field

[0001] The present invention relates to the technical field of material fracture failure research, and in particular to a method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel. Background Art

[0002] Strength is the ability of metal materials to resist deformation and damage under external forces, and is an important mechanical performance indicator in engineering technology; plasticity is the ability of metal materials to undergo plastic deformation before fracture. The plastic deformation generated before metal fracture consists of two parts: uniform deformation and concentrated plastic deformation. Commonly used plasticity indicators are elongation after fracture and cross-sectional shrinkage. Plasticity indicators are usually not directly used for structural design, but plasticity can relax local stress at the crack tip, which is beneficial to prevent crack expansion; and toughness is the ability of metal materials to absorb energy during the failure deformation process and fracture process. It is a combination of strength and plasticity. The better the toughness, the less likely it is to cause brittle fracture.

[0003] Among them, fracture toughness is a parameter of material toughness that prevents macro cracks from becoming unstable and breaking. It has nothing to do with the size, shape, or applied stress of the crack itself, but is only related to the material itself, heat treatment, and processing technology. It is the critical value of the stress intensity factor. Impact toughness reflects the ability of metal materials to resist external impact loads. It depends not only on the material and its state, but also on the shape and size of the specimen. For the same material, the longer and sharper the notch, the greater the stress concentration at the notch, and the easier it is to deform and break. Fracture toughness must be measured by a special test, and the test method is complex and the test cost is high. The impact toughness test method is simple and relatively low-cost, and has become the most commonly used method for evaluating material toughness.

[0004] The main test methods for measuring impact toughness include the Charpy impact test and the dynamic tear test. The Charpy impact test is more sensitive than other mechanical property testing methods in examining material quality, internal defects, and workmanship, and is currently the most commonly used test method for evaluating the impact toughness of high-strength structural steel. The dynamic tear test, on the other hand, features larger specimens and a sharper notch than the impact test, and is closer to actual performance, making it an effective method for evaluating the impact toughness of high-strength structural steel.

[0005] Impact absorption energy and dynamic tear energy, measured through Charpy impact and dynamic tear tests, are used as parameters to characterize the impact toughness of high-strength structural steel. Their higher-order energies depend not only on the material's strength but also closely on its plasticity. Establishing a quantitative relationship between these higher-order energies, such as impact absorption energy and dynamic tear energy, and strength and plasticity is crucial for effectively improving material toughness. However, prior art has yet to establish a quantitative relationship between these higher-order energies and strength and plasticity in a material's impact toughness. Summary of the Invention

[0006] In view of this, the present invention aims to propose a calculation model for the high-order energy of ductile-brittle transition in Charpy impact test and dynamic tearing test of high-strength structural steel, and realize the prediction and evaluation of the high-order energy of ductile-brittle transition of impact specimens and the high-order energy of ductile-brittle transition of dynamic tearing specimens through the tensile property characterization parameters obtained at room temperature. At the same time, the correlation equation between the high-order energy and the tensile property characterization parameters established by this model is used to further reveal the physical meaning of the high-order energy, and provide a technical basis for the toughness improvement and fracture resistance design of high-strength structural steel.

[0007] The present invention discloses a method for constructing a prediction model for the high-order energy of the ductile-brittle transition of high-strength structural steel. By conducting Charpy impact tests, dynamic tearing tests, and tensile tests, a correlation analysis is performed on the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition, and a correlation model between the high-order energy of the impact ductile-brittle transition, the high-order energy of the dynamic tearing ductile-brittle transition, and the tensile properties is established. The method comprises the following steps:

[0008] Step S1: Establish a calculation model for the high-order energy of impact ductile-brittle transition, tensile strength and cross-sectional shrinkage, as shown in formula (1):

[0009] KV2=α·σ b +β·ψ+θ (1)

[0010] Where KV2 is the high-order energy of the impact ductile-brittle transition, in J; σb is the tensile strength, in MPa; ψ is the cross-sectional reduction rate, expressed in percentage; α, β, and θ are unknown parameters.

[0011] Step S2: Establish a calculation model for the dynamic tearing ductile-brittle transition high-order energy and tensile strength, cross-sectional shrinkage, and elongation after fracture, as shown in formula (2):

[0012] DT=γ·σ b +ρ·δ+η·ψ+μ (2)

[0013] Where DT is the high-order energy of dynamic tearing ductile-brittle transition, in J; σb is the tensile strength, in MPa; δ is the elongation after fracture, expressed in percentage; ψ is the cross-sectional reduction, expressed in percentage; γ, ρ, η, and μ are unknown parameters.

[0014] Step S3: Perform Charpy impact tests, dynamic tear tests, and tensile tests on high-strength structural steels of different strength grades, and fit the relationships between the high-order energy of the impact ductile-brittle transition and the tensile strength and the reduction of area, and the high-order energy of the dynamic tear transition and the tensile strength, the reduction of area, and the elongation after fracture, respectively. The parameter values ​​or parameter ranges of the unknown parameters α, β, θ, γ, ρ, η, and μ are obtained through fitting.

[0015] Furthermore, step S1 includes the following steps:

[0016] Step S11: performing a Charpy impact test on high-strength structural steels of different strength grades to obtain high-order energy of impact ductile-brittle transition, and performing a tensile test on high-strength structural steels of different strength grades to obtain tensile strength and cross-sectional reduction rate;

[0017] Step S12: analyzing the correlation between the high-order energy of the impact ductile-brittle transition and the tensile strength and the reduction of area;

[0018] Step S13: Based on the correlation analysis results, a calculation model of the high-order energy of the impact ductile-brittle transition, the tensile strength, and the reduction of area is established.

[0019] Furthermore, step S2 includes the following steps:

[0020] Step S21: performing dynamic tearing tests on high-strength structural steels of different strength grades to obtain high-order energy of dynamic tearing ductile-brittle transition, and performing tensile tests on high-strength structural steels of different strength grades to obtain tensile strength, section shrinkage, and elongation after fracture;

[0021] Step S22: analyzing the correlation between the high-order energy of dynamic tearing ductile-brittle transition and the tensile strength, cross-sectional shrinkage, and elongation after fracture;

[0022] Step S23: Based on the correlation analysis results, a calculation model of the dynamic tearing ductile-brittle transition high-order energy and the tensile strength, cross-sectional shrinkage, and elongation after fracture is established.

[0023] Furthermore, the Charpy impact test, dynamic tear test and tensile test are all carried out at room temperature.

[0024] Furthermore, the room temperature is 10-30°C.

[0025] Furthermore, the high-strength structural steel is structural steel with a tensile strength between 532 and 828 MPa.

[0026] Furthermore, the high-strength structural steel is high-strength structural steel for ships and bridges.

[0027] Furthermore, with α = -0.085, β = 11.4, and θ = -535, the calculation model of the high-order energy of the impact ductile-brittle transition, the tensile strength, and the reduction of area is:

[0028] KV2=-0.085·σ b +11.4·ψ-535

[0029] Furthermore, with γ = 0.5, ρ = 27.6, η = 111.2, and μ = -7404, the calculation model of the dynamic tearing ductile-brittle transition high-order energy and tensile strength, section reduction, and elongation is:

[0030] DT=0.5·σb +27.6·δ+111.2·ψ-7404.

[0031] Compared with the prior art, the method for constructing a prediction model for the high-order energy of ductile-brittle transition of high-strength structural steel described in the present invention has the following advantages:

[0032] (1) The present invention starts from the characteristics of the high-order energy of the ductile-brittle transition of high-strength structural steel itself, and establishes a correlation model between the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition and the tensile performance characterization parameters through the correlation analysis of the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition. The prediction model can be established by the tensile performance parameters measured at room temperature, which can realize the quantitative evaluation of the high-order energy of the ductile-brittle transition of high-strength structural steel, and provide a technical basis for the improvement and improvement of the toughness and the fracture resistance design of high-strength structural steel.

[0033] (2) The prediction model constructed according to the construction method provided by the present invention has a clear physical mechanism. In the subsequent estimation of the high-order energy of the ductile-brittle transition of high-strength structural steel, there is no need to perform Charpy impact test or dynamic tearing test. The high-order energy of the ductile-brittle transition of high-strength structural steel can be evaluated only by tensile test. The prediction model is simple to construct and quick to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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.

[0035] Figure 1 Schematic diagram of the distribution relationship between high-order energy, transition temperature region, and low-order energy in the ductile-brittle transition curve related to impact absorption energy and temperature in an embodiment of the present invention;

[0036] Figure 2 Schematic diagram of the distribution relationship between high-order energy, transition temperature region, and low-order energy in the ductile-brittle transition curve related to dynamic tearing energy and temperature in an embodiment of the present invention;

[0037] Figure 3 Schematic diagram of the structure of the notch and plastic deformation zone on the impact specimen in an embodiment of the present invention;

[0038] Figure 4 Schematic diagram of the structure of the notch and plastic deformation zone on the dynamic tearing specimen in an embodiment of the present invention;

[0039] Figure 5 This is a measured graph of the high-order energy of the impact brittle-ductile transition and the fracture strength in an embodiment of the present invention;

[0040] Figure 6 This is a measured graph of the high-order energy of the impact brittle-ductile transition and the cross-sectional shrinkage rate in an embodiment of the present invention;

[0041] Figure 7 This is a measured graph of the high-order energy of the dynamic tearing brittle-ductile transition and the fracture strength in an embodiment of the present invention;

[0042] Figure 8 This is a measured graph of the high-order energy of dynamic tearing brittle-ductile transition and cross-sectional shrinkage in an embodiment of the present invention;

[0043] Figure 9 This is a measured graph of the high-order energy of dynamic tearing brittle-ductile transition and elongation after fracture in an embodiment of the present invention;

[0044] Figure 10 Schematic diagram comparing the predicted high-order energy of the ductile-brittle impact transition and the measured high-order energy of the ductile-brittle impact transition in an embodiment of the present invention;

[0045] Figure 11 Schematic diagram comparing the predicted high-order energy of dynamic tearing ductile-brittle transition and the measured high-order energy of dynamic tearing ductile-brittle transition in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the technical means, objectives and effects of the present invention easier to understand, embodiments of the present invention are described in detail below with reference to specific figures.

[0047] It should be noted that all terms used in the present invention to indicate direction and position, such as "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "low", "lateral", "longitudinal", "center", etc., are only used to explain the relative position relationship and connection status between the components in a certain specific state (as shown in the accompanying drawings). They are only for the convenience of describing the present invention, and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0048] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical connections; direct connections or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0049] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0050] The present invention discloses a method for constructing a prediction model for the high-order energy of the ductile-brittle transition of high-strength structural steel. The method comprises the following steps: performing a Charpy impact test, a dynamic tearing test, and a tensile test, performing a correlation analysis on the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition, and establishing a correlation model between the high-order energy of the impact ductile-brittle transition, the high-order energy of the dynamic tearing ductile-brittle transition, and the tensile properties.

[0051] Step S1: Establish a calculation model for the high-order energy of impact ductile-brittle transition, tensile strength and cross-sectional shrinkage, as shown in formula (1):

[0052] KV2=α·σ b +β·ψ+θ (1)

[0053] Where KV2 is the high-order energy of impact ductile-brittle transition, unit is J; σ b is the tensile strength, in MPa; ψ is the cross-sectional shrinkage, expressed in percentage; α, β, and θ are parameters to be determined;

[0054] Step S2: Establish a calculation model for the dynamic tearing ductile-brittle transition high-order energy and tensile strength, cross-sectional shrinkage, and elongation after fracture, as shown in formula (2):

[0055] DT=γ·σ b +ρ·δ+η·ψ+μ (2)

[0056] Where DT is the high-order energy of dynamic tearing ductile-brittle transition, unit is J; σ b is the tensile strength, in MPa; δ is the elongation after fracture, expressed in percentage; ψ is the reduction of area, expressed in percentage; γ, ρ, η, and μ are unknown parameters;

[0057] Step S3: Performing Charpy impact tests, dynamic tear tests, and tensile tests on high-strength structural steels of different strength grades, fitting the relationships between the high-order energy of the impact ductile-brittle transition and the tensile strength and reduction of area, and the high-order energy of the dynamic tear transition and the tensile strength, reduction of area, and elongation, respectively. The values ​​or ranges of the undetermined parameters α, β, θ, γ, ρ, η, and μ are obtained through fitting. Preferably, the least squares method is used for fitting in this application.

[0058] The method for constructing a prediction model for the high-order energy of the ductile-brittle transition of high-strength structural steel disclosed in the present invention starts from the characteristics of the high-order energy of the ductile-brittle transition of high-strength structural steel itself, and establishes a correlation model between the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition and the tensile performance characterization parameters through the correlation analysis of the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition. When predicting the high-order energy of the ductile-brittle transition of high-strength structural steel, the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition are obtained by previously accumulated room temperature Charpy impact, dynamic tearing test and tensile performance parameters of high-strength structural steel of different strength grades, and are substituted into formulas (1) and (2) to determine the parameters α, β, θ, γ, ρ, η, μ. When subsequently estimating the high-order energy of the ductile-brittle transition of high-strength structural steel, there is no need to perform Charpy impact test or dynamic tearing test, and the high-order energy of the ductile-brittle transition of high-strength structural steel can be evaluated only by tensile test.

[0059] The method for constructing a prediction model for the higher-order energy of the ductile-brittle transition of high-strength structural steel disclosed in the present invention has a clear physical mechanism, greatly reduces the amount of experiments and calculations required to evaluate the higher-order energy of the ductile-brittle transition of high-strength structural steel, is simple to construct, and is quick to use.

[0060] As an optional example of the present invention, step S1 includes the following steps:

[0061] Step S11: performing a Charpy impact test on high-strength structural steels of different strength grades to obtain high-order energy of impact ductile-brittle transition; performing a tensile test on high-strength structural steels of different strength grades to obtain tensile strength and cross-sectional reduction rate;

[0062] Step S12: analyzing the correlation between the high-order energy of the impact ductile-brittle transition and the tensile strength and the reduction of area;

[0063] Step S13: Based on the correlation analysis results, a calculation model of the high-order energy of the impact ductile-brittle transition, the tensile strength, and the reduction of area is established.

[0064] As an example of the present invention, step S2 includes the following steps:

[0065] Step S21: performing dynamic tearing tests on high-strength structural steels of different strength grades to obtain high-order energy of dynamic tearing ductile-brittle transition, and performing tensile tests on high-strength structural steels of different strength grades to obtain tensile strength, section shrinkage, and elongation after fracture;

[0066] Step S22: analyzing the correlation between the high-order energy of dynamic tearing ductile-brittle transition and the tensile strength, cross-sectional shrinkage, and elongation after fracture;

[0067] Step S23: Based on the correlation analysis results, a calculation model of the dynamic tearing ductile-brittle transition high-order energy and the tensile strength, cross-sectional shrinkage, and elongation after fracture is established.

[0068] The applicant conducted Charpy impact tests and dynamic tear tests on structural steel materials with different strengths. The ductile-brittle transition curves of the impact absorption energy are as follows: Figure 1 As shown in the figure, the ductile-brittle transition curve of dynamic tearing energy is as follows: Figure 2 As shown, the ductile-brittle transition of high-strength structural steel is divided into three stages: upper platform zone, transition temperature zone, and lower platform zone. When the temperature is higher than a certain temperature, the absorbed energy of the material remains basically unchanged, and this energy is called "high-order energy". At this time, the fracture of the material is fully plastic fracture, which is the upper platform zone; when the temperature is lower than a certain temperature, the absorbed energy of the material remains basically unchanged, and this energy is called "low-order energy". At this time, the fracture of the material is fully brittle fracture, which is the lower platform zone; the area between "high-order energy" and "low-order energy" is the transition temperature zone, and the fracture of the material within this temperature range is a mixed elastic-plastic fracture. Figure 1 and Figure 2 It can be seen that when the test temperature is kept above a certain temperature, the ductile-brittle transition high-order energy of the material remains unchanged. Therefore, the ductile-brittle transition high-order energy of the material can be accurately detected without considering the temperature change. It should be noted that Figure 5 Each point in the graph represents the corresponding relationship between the high-order energy of the impact ductile-brittle transition and the fracture strength (tensile strength) of the same material. Figure 6 Each point in the graph represents the corresponding relationship between the high-order energy of the impact ductile-brittle transition and the cross-sectional shrinkage rate for the same material. Figure 7 Each point in the figure represents the corresponding relationship between the dynamic tearing ductile-brittle transition high-order energy and the fracture strength (tensile strength) of the same material. Figure 8 Each point in the figure represents the corresponding relationship between the dynamic tearing ductile-brittle transition high-order energy and the cross-sectional shrinkage rate for the same material. Figure 9 The corresponding relationship between the dynamic tearing ductile-brittle transition high-order energy and the elongation after fracture for the same material. It should be noted that formula (1) and formula (2) can be obtained through a large number of experiments. Figures 5 to 9 , analyze the correlation between the above parameters, and then fit them through the existing fitting scheme to obtain formula (1) and formula (2). The existing fitting scheme can be performed using existing fitting software such as origin, etc., and is not limited here.

[0069] In the upper platform area, both the Charpy impact specimen and the dynamic tearing specimen are fully plastic fractures. Under the impact load, the front end of the notch of the specimen undergoes the whole process from elastic deformation, plastic deformation to fracture. The measured absorbed energy is not only related to the material strength, but also closely related to the material plasticity. That is, the impact absorption energy and dynamic tearing energy are a comprehensive reflection of the material strength and plasticity. Among them, the structure of the notch and plastic deformation area on the Charpy impact specimen is as follows: Figure 3 As shown in the figure, the structure of the notch and plastic deformation area on the dynamic tearing specimen is as follows: Figure 4 shown.

[0070] Based on the above analysis, the present invention obtains the performance parameters and the correlation analysis of the impact absorption energy and dynamic tearing energy through tensile testing, and establishes a calculation model for the high-order energy of the ductile-brittle transition of high-strength structural steel. In subsequent tests, only tensile testing is required to calculate and predict the high-order energy of the ductile-brittle transition of the material, which significantly reduces the amount of testing and calculation required to obtain the high-order energy of the ductile-brittle transition of the material. Figure 5 、 Figure 6 As shown in Figure 2, there is an obvious linear relationship between the high-order energy of impact ductile-brittle transition and the cross-sectional shrinkage of high-strength structural steels of different strength grades. At the same time, the high-order energy of impact ductile-brittle transition also has a certain relationship with the fracture strength of the material. Among them, the fracture strength of the material can be characterized by the tensile strength. Based on the above correlation, a prediction model for the high-order energy of impact ductile-brittle transition is established. Figure 7 、 Figure 8 、 Figure 9 As shown in the figure, there is an obvious linear relationship between the high-order energy of dynamic tearing ductile-brittle transition and the cross-sectional shrinkage of high-strength structural steels of different strength grades. At the same time, there is a certain relationship between the high-order energy of dynamic tearing ductile-brittle transition and the fracture strength of the material. The fracture strength of the material can be characterized by the tensile strength. In addition, compared with the Charpy impact test, the dynamic tearing specimen has a longer extension path, and the elongation after fracture has a certain influence on the absorbed energy. A prediction model for the high-order energy of impact ductile-brittle transition and cross-sectional shrinkage, tensile strength, and elongation after fracture can be established.

[0071] Through the above analysis, calculation models for the high-order energy of impact ductile-brittle transition and tensile strength and cross-sectional reduction rate, as well as the high-order energy of dynamic tearing ductile-brittle transition and tensile strength, cross-sectional reduction rate and elongation after fracture were established. In the subsequent prediction of the high-order energy of ductile-brittle transition of high-strength structural steel, there is no need to conduct fracture toughness tests, Charpy impact tests and dynamic tearing tests. Only tensile tests are needed for prediction, which is simple and convenient, and reduces the amount of testing and calculation.

[0072] As an example of the present invention, the Charpy impact test, dynamic tear test and tensile test are all carried out at room temperature. Figure 1 and attached Figure 2As can be seen from the figure, the upper limit of the transition temperature range is much lower than the room temperature under conventional testing. Therefore, the tensile strength, reduction of area, and elongation measured at room temperature can accurately predict the high-order energy of the impact ductile-brittle transition and the dynamic tearing ductile-brittle transition of high-strength structural steel. There is no need to deliberately adjust the test temperature, which simplifies the experimental conditions and improves the efficiency of the prediction and estimation. The room temperature is 10-30°C, preferably 25°C.

[0073] In some examples of the present invention, the high-strength structural steel is structural steel with a tensile strength between 532 and 828 MPa.

[0074] As an example, the high-strength structural steel is high-strength structural steel for ships and bridges.

[0075] The following are specific embodiments:

[0076] Utilize the working process of the present invention:

[0077] 1. According to GB / T228.1-2010 "Tensile tests on metallic materials - Part 1 - Room temperature test methods", tensile tests were carried out on high-strength structural steels of different strength grades to obtain the tensile performance parameters tensile strength and cross-sectional reduction rate. At the same time, according to GB / T229-2020 "Charpy impact test on metallic materials", room temperature impact tests were carried out to obtain the high-order energy of impact ductile-brittle transition. The results are shown in Table 1.

[0078] Table 1 Tensile properties and higher-order energies of impact ductile-brittle transition

[0079]

[0080] 2. Substitute the data in Table 1 into formula (1) and use the least squares method to fit. The obtained parameters are shown in Table 2. The form of the prediction model is shown in formula (3). The prediction results are shown in Figure 4 shown.

[0081] Table 2 Undetermined parameter values ​​in the calculation model

[0082] parameter α β θ Numerical -0.085 11.4 -535

[0083] KV2=-0.085·σ b +11.4·ψ-535 (3)

[0084] 3. According to GB / T228.1-2010 “Tensile tests on metallic materials—Part 1—Room temperature test methods”, tensile tests were carried out on high-strength structural steels of different strength grades to obtain the tensile performance parameters tensile strength, cross-sectional reduction, and elongation after fracture. At the same time, according to GB / T 5482-2007 “Metallic materials—Dynamic tear test methods”, room temperature dynamic tear tests were carried out to obtain the high-order energy of dynamic tearing ductile-brittle transition. The results are shown in Table 3.

[0085] Table 3 Tensile property parameters and dynamic tearing ductile-brittle transition high-order energy

[0086]

[0087] 4. Substitute the data in Table 3 into formula (2) and use the least squares method to fit. The obtained parameters are shown in Table 4. The form of the prediction model is shown in formula (4). The prediction results are shown in Figure 4 shown.

[0088] Table 4 Undetermined parameter values ​​in the calculation model

[0089] parameter γ ρ η μ scope 0.5 27.6 111.2 -7404

[0090] DT=0.5·σ b +27.6·δ+111.2·ψ-7404 (4)

[0091] According to the prediction model construction method of the high-strength structural steel material ductile-brittle transition high-order energy described in the above embodiment, two prediction models such as formula (3) and formula (4) are constructed. The comparison between the predicted impact ductile-brittle transition high-order energy calculated by the above formula (3) and the measured value is shown as follows: Figure 10 As shown in the figure, the comparison between the predicted dynamic tearing ductile-brittle transition high-order energy calculated by the above formula (4) and the measured value is shown in the figure. Figure 11 As shown in the figure, the prediction model established by the construction method provided by the present invention has good prediction effect and high accuracy. It can accurately predict the impact ductile-brittle transition high-order energy and dynamic tearing ductile-brittle transition high-order energy of high-strength structural steel only through tensile testing at room temperature, thus achieving quantitative evaluation of the ductile-brittle transition high-order energy of high-strength structural steel.

[0092] The method for constructing a prediction model for the ductile-brittle transition higher-order energy of high-strength structural steel described in the present invention provides a rapid prediction model for determining the ductile-brittle transition higher-order energy of high-strength structural steel materials. Starting from the characteristics of the ductile-brittle transition higher-order energy of high-strength structural steel itself, through the impact ductile-brittle transition higher-order energy correlation analysis and the dynamic tearing ductile-brittle transition higher-order energy correlation analysis, a correlation model of the impact ductile-brittle transition higher-order energy and the dynamic tearing ductile-brittle transition higher-order energy and tensile performance characterization parameters is established. The prediction model can be established through the tensile performance parameters measured at room temperature, and can realize the quantitative evaluation of the ductile-brittle transition higher-order energy of high-strength structural steel, providing a technical basis for the toughness improvement and fracture resistance design of high-strength structural steel.

[0093] The above description is only a preferred embodiment of the present invention and is 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 scope of protection of the present invention.

Claims

1. A method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel, characterized in that: By conducting Charpy impact tests, dynamic tearing tests, and tensile tests, the correlation analysis of the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition is carried out, and a correlation model of the high-order energy of the impact ductile-brittle transition, the high-order energy of the dynamic tearing ductile-brittle transition, and the tensile properties is established, including the following steps: Step S1: Establish a calculation model for the high-order energy of impact ductile-brittle transition, tensile strength and cross-sectional shrinkage, as shown in Equation (1): （1） Where KV2 is the high-order energy of impact ductile-brittle transition, unit is J; σ b is the tensile strength, in MPa; ψ is the cross-sectional shrinkage, expressed in percentage; α, β, and θ are parameters to be determined; Step S2: Establish a calculation model for the dynamic tearing ductile-brittle transition high-order energy and tensile strength, cross-sectional shrinkage, and elongation after fracture, as shown in Equation (2): （2） Where DT is the high-order energy of dynamic tearing ductile-brittle transition, unit is J; σ b is the tensile strength, in MPa; δ is the elongation after fracture, expressed in percentage; ψ is the reduction of area, expressed in percentage; γ, ρ, η, and μ are unknown parameters; Among them, Charpy impact test, dynamic tear test and tensile test are carried out on high-strength structural steel with different strength grades, and the relationship between the high-order energy of impact ductile-brittle transition and tensile strength and cross-sectional reduction rate, and the relationship between the high-order energy of dynamic tear transition and tensile strength, cross-sectional reduction rate and elongation after fracture are fitted respectively. The parameter values ​​or parameter ranges of the unknown parameters α, β, θ, γ, ρ, η and μ are obtained through fitting.

2. The method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel according to claim 1, characterized in that: Step S1 includes the following steps: Step S11: performing a Charpy impact test on high-strength structural steels of different strength grades to obtain high-order energy of impact ductile-brittle transition, and performing a tensile test on high-strength structural steels of different strength grades to obtain tensile strength and cross-sectional reduction rate; Step S12: analyzing the correlation between the high-order energy of the impact ductile-brittle transition and the tensile strength and the reduction of area; Step S13: Based on the correlation analysis results, a calculation model of the high-order energy of the impact ductile-brittle transition, the tensile strength, and the reduction of area is established.

3. The method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel according to claim 1, characterized in that: Step S2 includes the following steps: Step S21: performing dynamic tearing tests on high-strength structural steels of different strength grades to obtain high-order energy of dynamic tearing ductile-brittle transition, and performing tensile tests on high-strength structural steels of different strength grades to obtain tensile strength, section shrinkage, and elongation after fracture; Step S22: analyzing the correlation between the high-order energy of dynamic tearing ductile-brittle transition and the tensile strength, cross-sectional shrinkage, and elongation after fracture; Step S23: Based on the correlation analysis results, a calculation model of the dynamic tearing ductile-brittle transition high-order energy and the tensile strength, cross-sectional shrinkage, and elongation after fracture is established.

4. The method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel according to claim 1, characterized in that: The Charpy impact test, dynamic tear test and tensile test are all carried out at room temperature.

5. The method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel according to claim 4, characterized in that: The room temperature is 10-30°C.

6. The method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel according to claim 1, characterized in that: The high-strength structural steel is a structural steel with a tensile strength between 532 and 828 MPa.

7. The method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel according to claim 1, characterized in that: The high-strength structural steel is high-strength structural steel for ships and bridges.

8. The method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel according to claim 1, characterized in that: α=-0.085, β=11.4, θ=-535, the calculation model of the high-order energy of the impact ductile-brittle transition, tensile strength and cross-sectional reduction rate is: 。 9. The method for constructing a prediction model for high-order energy of ductile-brittle transition of high-strength structural steel according to claim 1, characterized in that: γ=0.5, ρ=27.6, η=111.2, μ=-7404, the calculation model of the dynamic tearing ductile-brittle transition high-order energy and tensile strength, cross-sectional reduction rate, and elongation after fracture is: 。

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