CN116399796A - Construction method of prediction model for ductile-brittle transition high-order energy of high-strength structural steel - Google Patents
Construction method of prediction model for ductile-brittle transition high-order energy of high-strength structural steel Download PDFInfo
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Abstract
The invention provides a construction method of a high-strength structural steel ductile-brittle transition high-order energy prediction model, which is characterized in that a Charpy impact test, a dynamic tearing test and a tensile test are carried out to carry out correlation analysis on the impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy, so that the high-strength structural steel impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy prediction model is established. According to the invention, through the impact ductile-brittle transition high-order energy correlation analysis and the dynamic tearing ductile-brittle transition high-order energy correlation analysis, a correlation model of the impact ductile-brittle transition high-order energy, the dynamic tearing ductile-brittle transition high-order energy and the tensile property characterization parameter is established, the prediction model can be established through tensile property parameters measured at room temperature, the quantitative evaluation of the high-strength structural steel ductile-brittle transition high-order energy can be realized, a technical basis is provided for the improvement and improvement of the high-strength structural steel toughness and the fracture resistance design, and the prediction model has definite physical mechanism, and is simple to construct and quick to use.
Description
Technical Field
The invention relates to the technical field of material fracture failure research, in particular to a construction method of a prediction model for ductile-brittle transition high-order energy of high-strength structural steel.
Background
The strength is the capability of the metal material to resist deformation and damage under the action of external force, and is an important mechanical property index in engineering technology; the plastic is the capability of plastic deformation of the metal material before fracture, the plastic deformation generated before the metal fracture consists of two parts of uniform deformation and concentrated plastic deformation, common plastic indexes are elongation after fracture and reduction of area, the plastic indexes cannot be directly used for structural design, but the plastic can relax the local stress of the crack tip, and the crack expansion is prevented; while toughness is the ability of a metal material to absorb energy during failure deformation and fracture, and is a combination of strength and plasticity, the better the toughness, the less likely brittle fracture will occur.
The fracture toughness is a toughness parameter of the material for preventing the macrocrack from being unstable and damaged, is irrelevant to the size and shape of the crack and the size of the external stress, is only relevant to the material, the heat treatment and the processing technology, and is a critical value of a stress intensity factor; while impact toughness is a property reflecting the resistance of a metal material to external impact loads, and depends not only on the material and its state, but also on the shape and size of the test specimen, and the same material has longer and sharper notches, and the greater the degree of stress concentration at the notches, the easier deformation and fracture. The fracture toughness is measured by a special test, the test method is complex, and the test cost is high. The impact toughness testing method is simple and low in cost, and has become the most common method for evaluating the toughness of materials.
The test method for measuring the impact toughness mainly comprises a Charpy impact test and a dynamic tearing test, and the Charpy impact test has the advantages of being more sensitive than other mechanical property test methods in the aspects of material quality, internal defects, process quality and the like, and is the most commonly used test method for evaluating the impact toughness of high-strength structural steel at present. Compared with the impact test, the dynamic tearing test has larger sample size and higher notch sharpness, is closer to the practical use performance, and is an effective method for evaluating the impact toughness of the high-strength structural steel.
The impact absorption energy and the dynamic tearing energy are measured through the Charpy impact test and the dynamic tearing test and serve as characterization parameters of the impact toughness of the high-strength structural steel, the high-order energy of the high-strength structural steel is closely related to the plasticity of the material and is significant for effectively improving the toughness of the material by establishing the quantitative relation between the impact absorption energy and the dynamic tearing energy and the high-order energy and the strength and the plasticity of the high-strength structural steel. From the prior art, the quantitative relation between the impact toughness high-order energy and the strength and the plasticity of the material is not established.
Disclosure of Invention
In view of the above, the invention aims to provide a calculation model for ductile-brittle transition high-order energy of high-strength structural steel in a Charpy impact test and a dynamic tearing test, and the prediction and evaluation of the ductile-brittle transition high-order energy of the impact test sample and the ductile-brittle transition high-order energy of the dynamic tearing test sample are realized through tensile property characterization parameters obtained at normal temperature, and meanwhile, a correlation equation between the high-order energy and the tensile property characterization parameters is established through the model, so that the physical significance of the high-order energy is further revealed, and a technical basis is provided for the improvement and improvement of the toughness of the high-strength structural steel and the fracture resistance design.
The invention discloses a construction method of a prediction model of high-strength structural steel ductile-brittle transition high-order energy, which is characterized by carrying out a Charpy impact test, a dynamic tearing test and a tensile test, carrying out correlation analysis on the impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy, and establishing a correlation model of the impact ductile-brittle transition high-order energy, the dynamic tearing ductile-brittle transition high-order energy and the tensile property, and comprising the following steps:
step S1: establishing a calculation model of impact toughness and brittleness transition high-order energy, tensile strength and area reduction rate, as shown in (1)
KV 2 ＝α·σ b +β·ψ+θ (1)
Wherein KV2 is impact ductile-brittle transition high-order energy, and the unit is J; sigma b is tensile strength in MPa; psi is the area reduction, expressed as a percentage; alpha, beta and theta are undetermined parameters;
step S2: establishing a calculation model of dynamic tearing ductile-brittle transition high-order energy, tensile strength, area shrinkage and elongation after fracture, as shown in (2)
DT＝γ·σ b +ρ·δ+η·ψ+μ (2)
Wherein DT is dynamic tearing ductile-brittle transition high-order energy, and the unit is J; sigma b is tensile strength in MPa; delta is elongation after break expressed as a percentage; psi is the area reduction, expressed as a percentage; gamma, rho, eta, mu are undetermined parameters;
step S3: and performing a Charpy impact test, a dynamic tearing test and a tensile test according to the high-strength structural steel with different strength grades, fitting the relation between the impact ductile-brittle transition high-order energy and the tensile strength, the area reduction rate and the dynamic tearing transition high-order energy and the tensile strength, the area reduction rate and the elongation after fracture respectively, and obtaining parameter values or parameter ranges of undetermined parameters alpha, beta, theta, gamma, rho, eta and mu through fitting.
Further, step S1 includes the steps of:
step S11: performing a Charpy impact test on the high-strength structural steel with different strength grades to obtain impact toughness and brittleness conversion high-order energy, and performing a tensile test on the high-strength structural steel with different strength grades to obtain tensile strength and reduction of area;
step S12: analyzing the correlation between the impact toughness and brittleness transition high-order energy and the tensile strength and the area reduction rate;
step S13: and according to a correlation analysis result, establishing a calculation model of the high-order energy, the tensile strength and the area reduction rate of the impact ductile-brittle transition.
Further, step S2 includes the steps of:
step S21: carrying out dynamic tearing test on the high-strength structural steel with different strength grades to obtain dynamic tearing ductile-brittle transition high-order energy, and carrying out tensile test on the high-strength structural steel with different strength grades to obtain tensile strength, area 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, the area shrinkage and the elongation after fracture;
step S23: and according to a correlation analysis result, establishing a calculation model of the high-order energy, tensile strength, area shrinkage and elongation after fracture of the dynamic tearing ductile-brittle transition.
Further, the Charpy impact test, dynamic tear test, and tensile test were all performed at room temperature.
Further, the room temperature is 10 to 30 ℃.
Further, the high-strength structural steel is structural steel with tensile strength of 532-828 MPa.
Further, the high-strength structural steel is high-strength structural steel for ships and bridges.
Further, the calculation model of the high-order energy of impact toughness and brittleness transformation, the tensile strength and the area reduction rate are as follows:
KV 2 ＝-0.085·σ b +11.4·ψ-535。
further, γ=0.5, ρ=27.6, η=111.2, μ= -7404, and the calculation model of the high-order energy of the dynamic tear ductile-brittle transition and the tensile strength, the area shrinkage and the elongation after break is:
DT＝0.5·σ b +27.6·δ+111.2·ψ-7404。
compared with the prior art, the construction method of the prediction model for ductile-brittle transition high-order energy of the high-strength structural steel has the following advantages:
(1) According to the invention, from the characteristics of the high-strength structural steel ductile-brittle transition high-order energy, a correlation model of the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition and a tensile property characterization parameter is established through impact ductile-brittle transition high-order energy correlation analysis and dynamic tearing ductile-brittle transition high-order energy correlation analysis, and the prediction model can be established through tensile property parameters measured at room temperature, so that quantitative evaluation of the high-order energy of the high-strength structural steel ductile-brittle transition can be realized, and a technical basis is provided for the improvement and improvement of the toughness of the high-strength structural steel and the fracture resistance design;
(2) According to the prediction model of the construction method framework, which is provided by the invention, the physical mechanism is clear, the high-order energy of the ductile-brittle transition of the high-strength structural steel can be evaluated only by a tensile test without performing a Charpy impact test or a dynamic tearing test when the subsequent high-order energy of the ductile-brittle transition of the high-strength structural steel is estimated, and the prediction model is simple to construct and quick to use.
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In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram showing the distribution of high-order energy, transition temperature region and low-order energy in a ductile-brittle transition curve of impact absorption energy and temperature according to an embodiment of the present invention;
FIG. 2 is a schematic diagram showing the distribution of high-order energy, transition temperature region and low-order energy in a ductile-brittle transition curve of dynamic tear energy and temperature according to an embodiment of the present invention;
FIG. 3 is a schematic view showing the structure of the notch and the plastic deformation zone of the impact specimen according to the embodiment of the present invention;
FIG. 4 is a schematic diagram of the structure of a notch and a plastic deformation zone on a dynamic tear specimen according to an embodiment of the present invention;
FIG. 5 is a graph showing the impact toughness to higher order energy and fracture strength in an embodiment of the present invention;
FIG. 6 is a graph showing the impact toughness transition to higher energy and area reduction in an embodiment of the present invention;
FIG. 7 is a graph showing the dynamic tear toughness to higher order energy and fracture strength in an embodiment of the present invention;
FIG. 8 is a graph showing the dynamic tear toughness transition to higher energy and reduction of area for an embodiment of the present invention;
FIG. 9 is a graph showing the dynamic tear toughness to high energy and elongation after break;
FIG. 10 is a graph showing the comparison of the predicted high-order energy of the impact toughness and brittleness transition with the measured high-order energy of the impact toughness and brittleness transition according to the embodiment of the present invention;
FIG. 11 is a graph showing the predicted high-order dynamic tear ductile-brittle transition in an embodiment of the present invention can be compared with the actually measured high-order energy of the dynamic tearing ductile-brittle transition.
Detailed Description
In order to facilitate understanding of the technical means, objects and effects of the present invention, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
It is to be noted that all terms used for directional and positional indication in the present invention, such as: "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "inner", "outer", "top", "low", "lateral", "longitudinal", "center", etc. are merely used to explain the relative positional relationship, connection, etc. between the components in a particular state (as shown in the drawings), and are merely for convenience of description of the present invention, and do not require that the present invention must be constructed and operated in a particular orientation, and thus should not be construed as limiting the present invention. Furthermore, the description of "first," "second," etc. in this disclosure is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated.
In the description of the present invention, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; may be a mechanical connection; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
In the description of the present specification, reference to the terms "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The invention discloses a construction method of a prediction model of high-strength structural steel ductile-brittle transition high-order energy, which is characterized by carrying out a Charpy impact test, a dynamic tearing test and a tensile test, carrying out correlation analysis on the impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy, and establishing a correlation model of the impact ductile-brittle transition high-order energy, the dynamic tearing ductile-brittle transition high-order energy and the tensile property, and comprising the following steps:
step S1: establishing a calculation model of impact toughness and brittleness transition high-order energy, tensile strength and area reduction rate, as shown in (1)
KV 2 ＝α·σ b +β·ψ+θ (1)
In KV 2 The unit is J for converting high-order energy for impact toughness and brittleness; sigma (sigma) b Tensile strength in MPa; psi is the area reduction, expressed as a percentage; alpha, beta and theta are undetermined parameters;
step S2: establishing a calculation model of dynamic tearing ductile-brittle transition high-order energy, tensile strength, area shrinkage and elongation after fracture, as shown in (2)
DT＝γ·σ b +ρ·δ+η·ψ+μ (2)
Wherein DT is dynamic tearing ductile-brittle transition high-order energy, and the unit is J; sigma (sigma) b Tensile strength in MPa; delta is elongation after break expressed as a percentage; psi is the area reduction, expressed as a percentage; gamma, rho, eta, mu are undetermined parameters;
step S3: and performing a Charpy impact test, a dynamic tearing test and a tensile test according to the high-strength structural steel with different strength grades, fitting the relation between the impact ductile-brittle transition high-order energy and the tensile strength, the area reduction rate and the dynamic tearing transition high-order energy and the tensile strength, the area reduction rate and the elongation after fracture respectively, and obtaining parameter values or parameter ranges of undetermined parameters alpha, beta, theta, gamma, rho, eta and mu through fitting. Preferably, the fitting is performed using the least squares method in the present application.
According to the construction method of the high-strength structural steel ductile-brittle transition high-order energy prediction model, from the characteristics of the high-strength structural steel ductile-brittle transition high-order energy, a correlation model of the high-order energy of the impact ductile-brittle transition and the high-order energy of the dynamic tearing ductile-brittle transition and tensile property characterization parameters is established through impact ductile-brittle transition high-order energy correlation analysis and dynamic tearing ductile-brittle transition high-order energy correlation analysis, when the high-strength structural steel ductile-brittle transition high-order energy is predicted, the impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy are obtained through the previously accumulated high-strength structural steel room temperature Charpy impact, dynamic tearing test and tensile property parameters, and are substituted into the parameters (1) and (2) to determine the parameters alpha, beta, theta, gamma, rho, eta and mu. And when the subsequent ductile-brittle transition high-order energy of the high-strength structural steel is estimated, the ductile-brittle transition high-order energy of the high-strength structural steel can be estimated only by a tensile test without performing a Charpy impact test or a dynamic tearing test.
The method for constructing the prediction model for the ductile-brittle transition high-order energy of the high-strength structural steel has the advantages of definite physical mechanism, great reduction in test quantity and calculation quantity for evaluating the ductile-brittle transition high-order energy of the high-strength structural steel, simple construction and quick use.
As an alternative example of the present invention, step S1 includes the steps of:
step S11: performing Charpy impact test on the high-strength structural steel with different strength grades to obtain impact toughness and brittleness conversion high-order energy; carrying out tensile tests on the high-strength structural steel with different strength grades to obtain tensile strength and reduction of area;
step S12: analyzing the correlation between the impact toughness and brittleness transition high-order energy and the tensile strength and the area reduction rate;
step S13: and according to a correlation analysis result, establishing a calculation model of the high-order energy, the tensile strength and the area reduction rate of the impact ductile-brittle transition.
As an example of the present invention, step S2 includes the steps of:
step S21: carrying out dynamic tearing test on the high-strength structural steel with different strength grades to obtain dynamic tearing ductile-brittle transition high-order energy, and carrying out tensile test on the high-strength structural steel with different strength grades to obtain tensile strength, area 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, the area shrinkage and the elongation after fracture;
step S23: and according to a correlation analysis result, establishing a calculation model of the high-order energy, tensile strength, area shrinkage and elongation after fracture of the dynamic tearing ductile-brittle transition.
The applicant carries out a Charpy impact test and a dynamic tearing test on different strength structural steel materials, wherein the ductile-brittle transition curve of the impact absorption energy is shown in figure 1, the ductile-brittle transition curve of the dynamic tearing energy is shown in figure 2, and the ductile-brittle transition of the high strength structural steel is divided into three stages: an upper plateau region, a transition temperature region, a lower plateau region. When the temperature is higher than a certain temperature, the absorption energy of the material is basically kept unchanged, the energy is called as 'high-order energy', and the fracture of the material is full plastic fracture, namely an upper platform area; when the temperature is lower than a certain temperature, the absorption energy of the material is basically kept unchanged, the energy is called as low-order energy, and the fracture of the material is full brittle fracture, namely a lower platform area; the intermediate region of the "high-order energy" and the "low-order energy" is a transition temperature region, in which the fracture of the material is an elastoplastic hybrid fracture. As can be seen from fig. 1 and 2, when the test temperature is maintained above a certain temperature, the ductile-brittle transition higher-order energy of the material remains unchanged, so that the ductile-brittle transition higher-order energy of the material can be accurately detected without considering the temperature change. It should be noted that, each point in fig. 5 shows a correspondence between the impact toughness and brittleness transition higher-order energy and the breaking strength (tensile strength) corresponding to the same material; FIG. 6 shows the correspondence between the impact toughness and brittleness transition higher-order energy and the area reduction rate of the same material at each point; each point in fig. 7 shows the correspondence between the high-order energy of the dynamic tear ductile-brittle transition and the breaking strength (tensile strength) corresponding to the same material; FIG. 8 shows the correspondence between the dynamic tear ductile-brittle transition higher-order energy and the reduction of area for the same material at each point; the correspondence between the high-order energy of the dynamic tear ductile-brittle transition and the elongation after break corresponding to the same material in fig. 9. It should be noted that, the formulas (1) and (2) may be obtained by a large number of experiments to obtain graphs as shown in fig. 5 to 9, analyzing the correlation between the above parameters, and then performing fitting by using an existing fitting scheme, which may be performed using existing fitting software such as origin, etc., and is not limited herein.
In the upper platform area, the Charpy impact test sample and the dynamic tearing test sample are all plastic fracture, the front end of the notch of the test sample is subjected to the whole process from elastic deformation and plastic deformation to fracture under the impact load, and the measured absorption energy is not only related to the material strength, but also closely related to the material plasticity, namely the impact absorption energy and the dynamic tearing energy are comprehensive reflection of the material strength and the plasticity. The structure of the notch and the plastic deformation zone on the Charpy impact specimen is shown in fig. 3, and the structure of the notch and the plastic deformation zone on the dynamic tear specimen is shown in fig. 4.
Based on the analysis, the invention obtains the correlation analysis of the performance parameters, the impact absorption energy and the dynamic tearing energy through a tensile test, establishes a calculation model of the high-strength structural steel ductile-brittle transition high-order energy, and can carry out calculation prediction of the material ductile-brittle transition high-order energy by only carrying out the tensile test in the subsequent detection, thereby obviously reducing the test amount and the calculation amount for obtaining the material ductile-brittle transition high-order energy. As shown in fig. 5 and 6, the impact ductile-brittle transition high-order energy of the high-strength structural steel with different strength levels has an obvious linear relation with the area reduction rate, and meanwhile, the impact ductile-brittle transition high-order energy has a certain relation with the breaking strength of the material. Wherein the breaking strength of the material can be characterized by the tensile strength. And establishing a prediction model of the high-order energy of the impact ductile-brittle transition according to the correlation. As shown in fig. 7, 8 and 9, the high-order energy of dynamic tearing ductile-brittle transition of the high-strength structural steel with different strength levels has an obvious linear relation with the reduction of area, meanwhile, the high-order energy of dynamic tearing ductile-brittle transition has a certain relation with the breaking strength of the material, the breaking strength of the material can be represented by the tensile strength, in addition, compared with a Charpy impact test, the expansion path of a dynamic tearing sample is longer, the elongation after breaking has a certain influence on the absorption energy, and a prediction model of the high-order energy of the impact ductile-brittle transition, the reduction of area, the tensile strength and the elongation after breaking can be established.
The high-order energy and the tensile strength and the area shrinkage rate of the impact ductile-brittle transition and the calculation model of the high-order energy and the tensile strength, the area shrinkage rate and the elongation after fracture of the dynamic tearing ductile-brittle transition are established through the analysis, when the subsequent ductile-brittle transition high-order energy of the high-strength structural steel is predicted, the fracture toughness test, the Charpy impact test and the dynamic tearing test are not needed, the prediction can be performed only through the tensile test, the method is simple and convenient, and the test quantity and the calculation quantity are reduced.
As an example of the present invention, the charpy impact test, dynamic tear test and tensile test were all performed at room temperature. As can be seen from the accompanying drawings 1 and 2, the upper limit of the temperature in the transition temperature region is far lower than the room temperature in the conventional test, so that the impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy of the high-strength structural steel can be accurately predicted by measuring the tensile strength, the area shrinkage and the elongation after fracture at the room temperature, the temperature during the test is not required to be adjusted intentionally, the experimental conditions are simplified, and the prediction estimation efficiency is improved. The room temperature is 10 to 30 ℃, preferably 25 ℃.
In some examples of the invention, the high strength structural steel is structural steel having a tensile strength between 532 and 828 MPa.
As one example, the high-strength structural steel is high-strength structural steel for ships and bridges.
The following are specific examples:
the working process of the invention is utilized:
1. the tensile test is carried out on high-strength structural steel with different strength grades according to GB/T228.1-2010 'part 1 room temperature test method of metal material tensile test', tensile strength and area reduction rate of tensile performance parameters are obtained, meanwhile, the room temperature impact test is carried out according to GB/T229-2020 'Charpy impact test of metal material', and impact toughness and brittleness conversion high-order energy is obtained, and the result is shown in Table 1.
TABLE 1 tensile Property parameters and impact toughness to brittle transition higher order energies
2. Substituting the data in table 1 into formula (1), fitting by using a least square method, obtaining undetermined parameters as shown in table 2, and predicting the parameters as shown in formula (3), wherein the prediction result is shown in fig. 4.
Table 2 calculation of the values of the parameters to be determined in the model
| Parameters (parameters) | α | β | θ |
| Numerical value | -0.085 | 11.4 | -535 |
KV 2 ＝-0.085·σ b +11.4·ψ-535 (3)
3. The tensile test is carried out on high-strength structural steel with different strength grades according to GB/T228.1-2010 'part 1 room temperature test method of metal material tensile test', tensile strength, area shrinkage and elongation after fracture of tensile performance parameters are obtained, meanwhile, the room temperature dynamic tearing test is carried out according to GB/T5482-2007 'part 1 dynamic tearing test method of metal material', and the high-order energy of dynamic tearing ductile-brittle transition is obtained, and the result is shown in Table 3.
TABLE 3 tensile property parameters and dynamic tear ductile-brittle transition higher order energies
4. Substituting the data in table 3 into formula (2), fitting by least square method, obtaining undetermined parameters as shown in table 4, predicting model form as shown in formula (4), and predicting result as shown in fig. 4.
Table 4 calculation of the values of the parameters to be determined in the model
| Parameters (parameters) | γ | ρ | η | μ |
| Range | 0.5 | 27.6 | 111.2 | -7404 |
DT＝0.5·σ b +27.6·δ+111.2·ψ-7404 (4)
According to the method for constructing the prediction model of the ductile-brittle transition high-order energy of the high-strength structural steel material in the embodiment, two prediction models of the formula (3) and the formula (4) are constructed, the comparison situation of the result of predicting the ductile-brittle transition high-order energy of the impact calculated by the formula (3) and the measured value is shown in fig. 10, and the comparison situation of the result of predicting the dynamic tearing ductile-brittle transition high-order energy calculated by the formula (4) and the measured value is shown in fig. 11. The prediction model established by the construction method provided by the invention has good prediction effect and higher accuracy, and can accurately predict the impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy of the high-strength structural steel only by a tensile test at room temperature, thereby realizing quantitative evaluation of the ductile-brittle transition high-order energy of the high-strength structural steel.
The invention provides a construction method of a high-strength structural steel ductile-brittle transition high-order energy prediction model, which is used for determining the ductile-brittle transition high-order energy of a high-strength structural steel material, and a technical basis is provided for the toughness improvement, the improvement and the fracture resistance design of the high-strength structural steel by means of impact ductile-brittle transition high-order energy correlation analysis and dynamic tearing ductile-brittle transition high-order energy correlation analysis based on the characteristics of the high-strength structural steel ductile-brittle transition high-order energy per se.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (9)
1. The construction method of the prediction model for the high-strength structural steel ductile-brittle transition high-order energy is characterized by comprising the following steps of performing a Charpy impact test, a dynamic tearing test and a tensile test, performing correlation analysis on the impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy, and establishing a correlation model between the impact ductile-brittle transition high-order energy and the dynamic tearing ductile-brittle transition high-order energy and tensile property, wherein the method comprises the following steps of:
step S1: establishing a calculation model of impact toughness and brittleness transition high-order energy, tensile strength and area reduction rate, as shown in (1)
KV 2 ＝α·σ b +β·ψ+θ (1)
In KV 2 The unit is J for converting high-order energy for impact toughness and brittleness; sigma (sigma) b Tensile strength in MPa; psi is the area reduction, expressed as a percentage; alpha, beta and theta are undetermined parameters;
step S2: establishing a calculation model of dynamic tearing ductile-brittle transition high-order energy, tensile strength, area shrinkage and elongation after fracture, as shown in (2)
DT＝γ·σ b +ρ·δ+η·ψ+μ (2)
Wherein DT is dynamic tearing ductile-brittle transition high-order energy, and the unit is J; sigma (sigma) b Tensile strength in MPa; delta is elongation after break expressed as a percentage; psi is the area reduction, expressed as a percentage; gamma, rho, eta, mu are undetermined parameters;
step S3: and performing a Charpy impact test, a dynamic tearing test and a tensile test according to the high-strength structural steel with different strength grades, fitting the relation between the impact ductile-brittle transition high-order energy and the tensile strength, the area reduction rate and the dynamic tearing transition high-order energy and the tensile strength, the area reduction rate and the elongation after fracture respectively, and obtaining parameter values or parameter ranges of undetermined parameters alpha, beta, theta, gamma, rho, eta and mu through fitting.
2. The method for constructing the prediction model for ductile-brittle transition high-order energy of high-strength structural steel according to claim 1, wherein the step S1 comprises the following steps:
step S11: performing a Charpy impact test on the high-strength structural steel with different strength grades to obtain impact toughness and brittleness conversion high-order energy, and performing a tensile test on the high-strength structural steel with different strength grades to obtain tensile strength and reduction of area;
step S12: analyzing the correlation between the impact toughness and brittleness transition high-order energy and the tensile strength and the area reduction rate;
step S13: and according to a correlation analysis result, establishing a calculation model of the high-order energy, the tensile strength and the area reduction rate of the impact ductile-brittle transition.
3. The method for constructing the prediction model for ductile-brittle transition high-order energy of high-strength structural steel according to claim 1, wherein the step S2 comprises the following steps:
step (a) S21: carrying out dynamic tearing test on the high-strength structural steel with different strength grades to obtain dynamic tearing ductile-brittle transition high-order energy, and carrying out tensile test on the high-strength structural steel with different strength grades to obtain tensile strength, area 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, the area shrinkage and the elongation after fracture;
step S23: and according to a correlation analysis result, establishing a calculation model of the high-order energy, tensile strength, area shrinkage and elongation after fracture of the dynamic tearing ductile-brittle transition.
4. The method for constructing a prediction model for ductile-brittle transition high-order energy of high-strength structural steel according to claim 1, wherein the Charpy impact test, the dynamic tear test and the tensile test are all performed at room temperature.
5. The method for constructing a prediction model for ductile-brittle transition high-order energy of high-strength structural steel according to claim 4, wherein the room temperature is 10-30 ℃.
6. The method for constructing a prediction model for ductile-brittle transition high-order energy of high-strength structural steel according to claim 1, wherein the high-strength structural steel is structural steel with tensile strength of 532-828 MPa.
7. The method for constructing a prediction model for ductile-brittle transition of high-strength structural steel according to claim 1, wherein the high-strength structural steel is high-strength structural steel for ships and bridges.
8. The method for constructing the prediction model of the ductile-brittle transition high-order energy of the high-strength structural steel according to claim 1, wherein the calculation model of the ductile-brittle transition high-order energy, the tensile strength and the area reduction rate of the impact is as follows:
KV 2 ＝-0.085·σ b +11.4·ψ-535。
9. the method for constructing the prediction model of the ductile-brittle transition high-order energy of the high-strength structural steel according to claim 1, wherein the calculation model of the high-order energy of the dynamic tearing ductile-brittle transition and the tensile strength, the area shrinkage and the elongation after fracture is as follows:
DT＝0.5·σ b +27.6·δ+111.2·ψ-7404。
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