Method for predicting tensile strength of metal material through Brinell hardness

Abstract

The invention discloses a method for predicting tensile strength of a metal material through Brinell hardness, which comprises the following steps: preparing a Brinell hardness test sample, and carrying out standard Brinell hardness tests of different test forces F1 and F2 on the surface of the test sample to obtain Brinell hardness values HBW1 and HBW2; s2, calculating plastic displacements hr1 and hr2 corresponding to different rated test forces by using the Brinell hardness values HBW1 and HBW2; s3, calculating elastic displacements he1 and he2 corresponding to different rated test forces by using the elastic modulus E and the Poisson ratio v of the material; s4, calculating total displacements h1 and h2 corresponding to different rated test forces F1 and F2 by using the plastic displacements hr1 and hr2 and the elastic displacements he1 and he2; and S5, calculating the tensile strength Rm of the material by using the test forces F1 and F2 and the total displacements h1 and h2. According to the method, the theory and finite element simulation analysis are combined, the relation model between the Brinell hardness and the tensile strength is established, and the method is suitable for obtaining the tensile strength of the ductile metal material through Brinell hardness prediction when a tensile test cannot be carried out.

Description

Technical Field

[0001] The present invention relates to the technical field of material tensile strength prediction, and in particular to a method for predicting the tensile strength of a metal material through Brinell hardness. Background Art

[0002] The strength and hardness of materials are the basic mechanical properties of materials. Both reflect the strength of the comprehensive performance of materials and play an important guiding role in material evaluation and structural design. Among them, the hardness test is relatively simple and does not require tedious sample installation and measurement equipment debugging. In addition, the hardness test uses less material. Generally, multiple hardness tests can be performed on a small surface (such as 2mm×2mm), and even on the residual sample (clamping end) after the tensile test.

[0003] For the tensile strength test of the tensile performance parameter of the material, it is necessary to process a standard large-size tensile sample (total length ≥55mm, diameter ≥5mm), install the sample on the tensile fixture, and ensure the coaxiality and stability of the connection, and then perform a tensile test to obtain the tensile strength of the material. The test requires a lot of raw materials and the test efficiency is slow. So for the situation where raw materials are scarce and the test operation is inconvenient. If the tensile strength of the material can be predicted by the hardness value of the material, this will undoubtedly simplify the test operation, reduce the materials required for the test, and reduce the test cost. For example, the performance test of the fusion reactor material after neutron irradiation, because the material is radioactive after irradiation, it can only be irradiated in a hot room before the material performance test operation. If it is possible to obtain the hardness of the material and obtain its tensile strength at the same time by performing a simple hardness test on it, it will undoubtedly reduce the difficulty of the test operation and improve the utilization rate of irradiation resources.

[0004] Hardness and tensile strength R of the material m There is a certain correspondence between them. Many scholars hope to establish a quantitative correspondence between the two. In 2004, Cheng (Cheng Y, Cheng C, Mater. Scaling, dimensional analysis, and indentation measurements [J]. Mater. Sci. Eng. R, 2004, 44: 91-194.) proposed a theoretical formula for the conversion between hardness and strength. Subsequent scholars have also carried out a lot of research in this direction. However, these hardness and tensile strength conversion relationship models have certain problems: 1. The research method is based on a large amount of test data, and then uses statistics to establish a prediction formula in segments, and its scope of application is small; 2. The test accuracy is not high, and the strength value of the material cannot be effectively predicted; 3. The model is complex, the formula is cumbersome, and the parameters lack clear physical meanings, which makes it difficult to apply in practice.

[0005] In view of this, this application is hereby filed. Summary of the invention

[0006] The problem with the prior art is that the existing hardness and tensile strength conversion relationship model has a small scope of application and low test accuracy. The present invention provides a method for predicting the tensile strength of metal materials through Brinell hardness. Based on the energy equivalence principle, the theory is combined with finite element simulation analysis to establish a relationship model between Brinell hardness and tensile strength. The method is suitable for obtaining the tensile strength of ductile metal materials through Brinell hardness prediction when tensile tests cannot be performed.

[0007] The present invention is achieved through the following technical solutions:

[0008] A method for predicting the tensile strength of a metal material by using Brinell hardness comprises the following steps:

[0009] S1, preparing Brinell hardness test samples, and performing standard Brinell hardness tests with different rated test forces F1 and F2 on the test sample surfaces to obtain Brinell hardness values ​​HBW1 and HBW2 under different rated test forces;

[0010] S2, using the Brinell hardness values ​​HBW1 and HBW2 to calculate the plastic displacement h corresponding to different rated test forces r1 and h r2 ;

[0011] S3, using the material elastic modulus E and Poisson's ratio v, calculate the elastic displacement h corresponding to different rated test forces e1 and h e2 ;

[0012] S4, using plastic displacement h r1 and h r2 , elastic displacement h e1 and h e2 Calculate the total displacements h1 and h2 corresponding to different rated test forces F1 and F2;

[0013] S5, using the test forces F1, F2 and the total displacements h1, h2, calculate the tensile strength R of the material m .

[0014] In a specific embodiment, the Brinell hardness is calculated as follows:

[0015]

[0016] Where, HBW is the Brinell hardness; constant η = 0.102; F is the rated test force of the Brinell hardness; D is the diameter of the Brinell hardness indenter; d is the indentation diameter; h r is the indentation depth, i.e., plastic displacement;

[0017] Therefore, the plastic displacement h r1 and hr2 The calculation formula is as follows:

[0018]

[0019] Where D is the diameter of the Brinell hardness indenter and the constant η is 0.102.

[0020] In a specific embodiment, in step S3, the elastic displacement h e1 and h e2 The calculation formula is as follows:

[0021]

[0022] In a specific implementation, in step S4, the calculation formulas for the total displacements h1 and h2 are as follows:

[0023]

[0024] In a specific embodiment, in step S5, the preliminary predicted tensile strength R of the material is calculated using the test forces F1, F2 and the total displacements h1, h2. m0 , and then make a preliminary prediction of the tensile strength R m0 After correction, the tensile strength R of the material is obtained. m .

[0025] In a specific embodiment, the initial prediction of the tensile strength R m0 The calculation formula is as follows:

[0026]

[0027] Where e is the natural base, coefficients k1 and k3 are determined by finite element calculation, and m and n are parameters related to F1, F2, h1, and h2.

[0028] In a specific embodiment, the tensile strength R m The calculation formula is as follows:

[0029]

[0030] Where a, b, and c are unknown parameters, which are determined by finite element calculation.

[0031] In a specific implementation, the calculation formulas for the parameters m and n are as follows:

[0032]

[0033] Wherein, the coefficients k2 and k4 are determined by a small amount of finite element calculations.

[0034] In a specific implementation, the calculation method of parameters k1, k2, k3, and k4 is as follows:

[0035] (1) Select an appropriate indenter diameter D, establish a finite element analysis model, simulate the indentation test on the material surface, and extract the load-displacement curve of the loading process;

[0036] (2) Set the material elastic modulus E and nominal tensile strength σ y , calculate the indentation load-displacement curves of various strain hardening exponents n, perform power law fitting on the elastic-plastic section of the load-displacement curve, and obtain the coefficients C and m;

[0037]

[0038] (3) Combining formula (7) with the energy equivalent theory formula and combining the obtained coefficients C and m, the parameters k1, k2, k3, and k4 can be calibrated and obtained. The calculation formula is as follows:

[0039]

[0040] In a specific implementation, the parameters a, b, and c are calculated as follows:

[0041] (1) Select the appropriate size of the indenter diameter D, establish a finite element analysis model, set a variety of elastic moduli E, nominal tensile strength σ y and strain hardening index n, corresponding to a variety of different materials, simulate the Brinell hardness test with test forces F1 and F2 on the surfaces of a variety of different materials to obtain the Brinell hardness values ​​of a variety of materials;

[0042] (2) Using formula (5) to obtain the preliminary predicted tensile strength R of various materials m0 , and according to the elastic modulus E of the material, the nominal tensile strength σ y and strain hardening exponent n to calculate the true tensile strength R of the material m ;

[0043]

[0044] (3) R through the quadratic function m With R m0 Perform fitting to obtain parameters a, b, and c.

[0045] In a specific implementation, for pressure head diameters D of other sizes, k1, k2, k3, and k4 can be recalibrated according to the above method.

[0046] In a specific embodiment, the tensile strength prediction method of the present invention is applicable to a wide range of continuous metal materials with a yield strength of 100 MPa to 1200 MPa.

[0047] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0048] 1. A method for predicting the tensile strength of a metal material by using the Brinell hardness provided in an embodiment of the present invention combines theory with finite element simulation analysis based on the energy equivalence principle to establish a conversion formula between the tensile strength of a metal material and the Brinell hardness. The theoretical model formula is simple and effective and contains few parameters.

[0049] 2. A method for predicting the tensile strength of a metal material by using the Brinell hardness provided by an embodiment of the present invention can predict the tensile strength parameters of the material while obtaining the hardness value through only two Brinell hardness tests, thereby simplifying the test operation, making the test method highly operable, and saving the test cost;

[0050] 3. A method for predicting the tensile strength of a metal material by using the Brinell hardness provided in an embodiment of the present invention provides a method for predicting the tensile strength of a ductile metal material by using the Brinell hardness, which is applicable when a tensile test cannot be performed, such as when a tensile test sample cannot be prepared or the tensile test conditions do not allow, effectively solves engineering problems, and has excellent engineering application prospects;

[0051] 4. A method for predicting the tensile strength of a metal material by using the Brinell hardness provided in an embodiment of the present invention can indirectly obtain the tensile performance parameter tensile strength of the metal material through a hardness test that is simpler and uses less testing materials. The method is suitable for situations in which raw materials for testing are scarce in engineering projects, such as irradiated materials, precious metal materials, and new research and development materials. The method is also suitable for test environments where it is difficult to provide tensile test conditions, such as tensile tests on irradiated materials in a hot chamber and lack of accurate and reliable tensile test equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 A schematic diagram of a Brinell hardness test provided by an embodiment of the present invention;

[0054] Figure 2 A finite element analysis model for Brinell hardness test provided by an embodiment of the present invention;

[0055] Figure 3 A Brinell hardness testing machine provided by an embodiment of the present invention;

[0056] Figure 4 This is a graph of tensile strength prediction results provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0058] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to those of ordinary skill in the art that these specific details need not be employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known materials or methods are not specifically described.

[0059] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0060] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0061] Example 1

[0062] The embodiment of the present invention provides a method for predicting the tensile strength of a metal material by using Brinell hardness, comprising the following steps:

[0063] S1, such as Figure 1 and Figure 3As shown, a Brinell hardness test sample is processed and prepared, a Brinell hardness indenter diameter D is selected, and a Brinell hardness test machine is used to perform two standard Brinell hardness tests with different rated test forces F1 and F2 on the surface of the test sample to obtain the Brinell hardness values ​​HBW1 and HBW2 of the material under two different rated test forces;

[0064] S2, substitute the two hardness values ​​HBW1 and HBW2 into the lower market, and calculate the plastic displacement h corresponding to different rated test forces r1 and h r2 :

[0065]

[0066] Where, constant η = 0.102;

[0067] S3, Substitute the material elastic modulus E and Poisson's ratio v into the following formula to calculate the elastic displacement h corresponding to two different rated test forces e1 and h e2 :

[0068]

[0069] S4, the obtained plastic displacement h r1 and h r2 , elastic displacement h e1 and h e2 Substituting into the following formula, we can calculate the total displacements h1 and h2 corresponding to different rated test forces F1 and F2:

[0070]

[0071] S5, substitute the previously calculated (F1, h1) and (F2, h2) into the following formula to calculate the parameters m and n:

[0072]

[0073] In the formula, coefficients k2 and k4 are determined by finite element calculation;

[0074] S6, substitute the previously calculated parameters m, n, (F1, h1) or (F2, h2) into the following formula to calculate the preliminary predicted tensile strength R of the material m0 :

[0075]

[0076] In the formula, e is the natural base, and the coefficients k1 and k3 are determined by finite element calculation;

[0077] Among them, the calculation method of parameters k1, k2, k3, and k4 is as follows:

[0078] (1) Take an appropriate indenter diameter D and establish a reasonable finite element analysis model. Perform an indentation test simulation on the material surface, control the indentation load to be above the Brinell hardness rated load, and extract the load-displacement curve of the loading process;

[0079] (2) The material constitutive relationship adopts the power law hardening model. Given the elastic modulus and nominal yield strength of the material, the indentation load-displacement curves of five different strain hardening exponents n are calculated. The elastic-plastic segment of the load-displacement curve is fitted with a power law to obtain the coefficients C and m;

[0080]

[0081] (3) The above formula is combined with the energy equivalent theory formula, and combined with C and m obtained by fitting the indentation load-displacement curves of 5 different strain hardening exponents n, the parameters k1, k2, k3, and k4 can be calibrated and obtained. The calculation formula is as follows:

[0082]

[0083] S7, use the following formula to preliminarily predict the tensile strength R m0 After correction, the tensile strength R of the material is finally obtained. m :

[0084]

[0085] Where a, b, and c are unknown parameters, which are determined by finite element calculation.

[0086] In a specific implementation, the calculation method of parameters a, b, and c is as follows:

[0087] (1) Select the appropriate size of the indenter diameter D, establish a finite element analysis model, set a variety of elastic moduli E, nominal tensile strength σ y and strain hardening index n, corresponding to a variety of different materials, simulate the Brinell hardness test with test forces F1 and F2 on the surfaces of a variety of different materials to obtain the Brinell hardness values ​​of a variety of materials;

[0088] (2) Using formula (5) to obtain the preliminary predicted tensile strength R of various materials m0 , and according to the elastic modulus E of the material, the nominal tensile strength σ y and strain hardening exponent n to calculate the true tensile strength R of the material m ;

[0089]

[0090] (3) R through the quadratic function m With R m0Perform fitting to obtain parameters a, b, and c.

[0091] In a specific implementation, for pressure head diameters D of other sizes, k1, k2, k3, and k4 can be recalibrated according to the above method.

[0092] In a specific embodiment, the tensile strength prediction method of the present invention is applicable to a wide range of continuous metal materials with a yield strength of 100 MPa to 1200 MPa.

[0093] Example 2

[0094] The embodiment of the present invention provides a finite element calculation verification of a method for predicting the tensile strength of a metal material by using Brinell hardness, comprising the following steps:

[0095] (1) Figure 2 The figure shows the finite element (FEA) simulation model of the axisymmetric Brinell hardness test, with a head diameter of D = 1 mm. The material constitutive relationship adopts a power-law hardening model, and the model parameters are set as elastic modulus E = 200 GPa, strain hardening exponent n (0.1 to 0.5, interval 0.1) and nominal yield strength σ y (200MPa~1000MPa, interval 200MPa). The indenter is loaded by load control, and the load is applied to the Brinell hardness rated load F1=294.2N and F2=98.07N respectively, and then unloaded to no load, and the plastic displacement h after unloading is obtained. r ;

[0096] (2) At the same time, the material constitutive relationship parameters n, K = E n σ y 1-n Substitute the following formula to calculate the true tensile strength R of the material mt , used for subsequent prediction result comparison;

[0097]

[0098] (3) The plastic displacement h after unloading is obtained by FEA calculation r Substitute it into the Brinell hardness calculation formula to calculate the true Brinell hardness value of the material;

[0099]

[0100] (4) According to the Brinell hardness value, the plastic displacement h corresponding to different rated loads can be calculated by the above formula. r , because in the finite element verification process, the plastic displacement h rIt can be directly obtained through finite element calculation results, so this step can be ignored. Substitute the material elastic modulus E and Poisson's ratio v into the following formula to calculate the elastic displacement h corresponding to different rated test forces F e , and then the total displacements h1 and h2 corresponding to different rated test forces F are obtained;

[0101]

[0102] (5) Substituting the previously calculated (F1, h1) and (F2, h2) into the following formula, the parameters m and n can be calculated;

[0103]

[0104] Where k2 and k4 are shown in Table 1;

[0105] (6) Substituting m, n, (F1, h1) or (F2, h2) into the following formula, the tensile strength R of the material can be calculated: m0 , and then correct it to get the final predicted R m ;

[0106]

[0107] Wherein k1, k2, k3, k4, a, b, and c are as shown in Table 1.

[0108] Table 1 Parameters of tensile strength prediction formula

[0109]

[0110]

[0111] Compare the predicted material tensile strength R m Compared with the standard uniaxial tensile test tensile strength R mt ,like Figure 4 As shown, it can be seen that the predicted value is highly correlated with the true value, the prediction effect is good, and the prediction result is accurate and reliable.

[0112] Example 3

[0113] The embodiment of the present invention provides an experimental verification of a method for predicting the tensile strength of a metal material by using the Brinell hardness, comprising the following steps:

[0114] (1) A total of three materials, CLF-1, P92, and SA302B, were selected to prepare Brinell hardness samples. According to the method provided by the Brinell hardness standard, the three materials were subjected to Brinell hardness tests with a head diameter of D = 1 mm, rated loads F1 = 294.2 N and F2 = 98.07 N, i.e., hardness tests of two scales, HBW1 / 30 and HBW1 / 10, to obtain accurate Brinell hardness values ​​of the materials. At the same time, standard uniaxial tensile tests were performed on the three materials to obtain the true tensile strength R of the materials. mt , used for subsequent comparative verification;

[0115] (2) Substitute the obtained hardness value into the following formula to calculate the corresponding plastic displacement h r ;

[0116]

[0117] (3) Substituting the material elastic modulus E and Poisson's ratio v into the following formula, the elastic displacement h corresponding to different rated test forces F can be calculated. e , and then the total displacements h1 and h2 are obtained;

[0118]

[0119] (4) Substituting the previously calculated (F1, h1) and (F2, h2) into the following formula, the parameters m and n can be calculated;

[0120]

[0121] Where k2 and k4 are shown in Table 1;

[0122] (5) Substituting m, n, (F1, h1) or (F2, h2) into the following formula (4) can calculate the tensile strength R of the material: m0 , and then correct it to get the final predicted R m ;

[0123]

[0124] Wherein k1, k3, a, b, and c are as shown in Table 1.

[0125] Compare the material tensile strength R predicted by this method m And the material's true tensile strength R mt As shown in Table 2, it can be seen that the predicted value is highly correlated with the true value, the prediction effect is good, and the prediction result is accurate and reliable.

[0126] Table 2 Prediction results of tensile strength

[0127]

[0128] In the embodiments 2 and 3 of the present invention, the finite element verification and experimental verification methods of the tensile strength prediction method are respectively carried out. There is no need to carry out the time-consuming and material-consuming uniaxial tensile test. Through a simple Brinell hardness test, while obtaining the two Brinell hardness values ​​of the material, the tensile strength of the key performance parameter of the material can also be accurately predicted.

[0129] The present invention obtains various mechanical properties of materials through a simpler test method, greatly improves the utilization rate of materials, is suitable for testing the performance of materials after irradiation, reduces the cost of testing the radiation resistance performance, has a wide range of applications, and has significant engineering application value.

[0130] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of 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 predicting the tensile strength of a metal material by Brinell hardness, characterized in that: The steps include: S1, preparing Brinell hardness test samples, and performing standard Brinell hardness tests with different rated test forces F1 and F2 on the test sample surfaces to obtain Brinell hardness values ​​HBW1 and HBW2 under different rated test forces; S2, using the Brinell hardness values ​​HBW1 and HBW2 to calculate the plastic displacement h corresponding to different rated test forces r1 and h r2 ; S3, using the material elastic modulus E and Poisson's ratio v, calculate the elastic displacement h corresponding to different rated test forces e1 and h e2 ; S4, using plastic displacement h r1 and h r2 , elastic displacement h e1 and h e2 Calculate the total displacements h1 and h2 corresponding to different rated test forces F1 and F2; S5, using the test forces F1, F2 and the total displacements h1, h2, calculate the tensile strength R of the material m .

2. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 1, characterized in that: In step S2, the plastic displacement h r1 and h r2 The calculation formula is as follows: Where D is the diameter of the Brinell hardness indenter and the constant η is 0.

102.

3. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 2, characterized in that: In step S3, the elastic displacement h e1 and h e2 The calculation formula is as follows:

4. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 3, characterized in that: In step S4, the calculation formulas of the total displacements h1 and h2 are as follows:

5. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 4, characterized in that: In step S5, the preliminary predicted tensile strength R of the material is calculated using the test forces F1, F2 and the total displacements h1, h2. m0 , and then make a preliminary prediction of the tensile strength R m0 After correction, the tensile strength R of the material is obtained. m .

6. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 5, characterized in that: Preliminary prediction of tensile strength R m0 The calculation formula is as follows: Where e is the natural base, coefficients k1 and k3 are determined by finite element calculation, and m and n are parameters related to F1, F2, h1, and h2.

7. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 6, characterized in that: Tensile strength R m The calculation formula is as follows: Where a, b, and c are unknown parameters, which are determined by finite element calculation.

8. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 6, characterized in that: The calculation formulas for parameters m and n are as follows: Wherein, the coefficients k2 and k4 are determined by a small amount of finite element calculations.

9. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 8, characterized in that: The calculation method of parameters k1, k2, k3, k4 is as follows: (1) Select an appropriate indenter diameter D, establish a finite element analysis model, simulate the indentation test on the material surface, and extract the load-displacement curve of the loading process; (2) Set the material elastic modulus E and nominal tensile strength σ y , calculate the indentation load-displacement curves of various strain hardening exponents n, perform power law fitting on the elastic-plastic section of the load-displacement curve, and obtain the coefficients C and m; (3) Combining formula (7) with the energy equivalent theory formula and combining the obtained coefficients C and m, the parameters k1, k2, k3, and k4 can be calibrated and obtained. The calculation formula is as follows:

10. The method for predicting the tensile strength of metal materials by Brinell hardness according to claim 7, characterized in that: The calculation method of parameters a, b, and c is as follows: (1) Select the appropriate size of the indenter diameter D, establish a finite element analysis model, set a variety of elastic moduli E, nominal tensile strength σ y and strain hardening index n, corresponding to a variety of different materials, simulate the Brinell hardness test with test forces F1 and F2 on the surfaces of a variety of different materials to obtain the Brinell hardness values ​​of a variety of materials; (2) The method of claim 6 is used to obtain the preliminary predicted tensile strength R of various materials. m0 , and according to the elastic modulus E of the material, the nominal tensile strength σ y and strain hardening exponent n to calculate the true tensile strength R of the material m ; (3) R through the quadratic function m With R m0 Perform fitting to obtain parameters a, b, and c.

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