A method, device, medium and product for testing tensile mechanical properties of metal materials

Abstract

The present invention discloses a method, device, medium, and product for testing the tensile mechanical properties of metal materials, relating to the technical field of material mechanical property testing. The method comprises: obtaining a force-deflection curve of a target metal material; determining a first area and a second area based on a first deflection point, a second deflection point, and a third deflection point and the force-deflection curve; calculating the yield strength and tensile strength of the target metal material based on the first area and the second area; calculating material parameters based on the yield strength and tensile strength of the target metal material; and obtaining a true stress-strain curve of the target metal material based on the material parameters and the Hollomon formula. The present invention only requires simple processing of the force-deflection curve of a small punch test to quickly obtain the material's yield strength, tensile strength, and true stress-strain curve. The obtained results are highly accurate and the principle is simple, making them convenient for engineering applications.

Description

Technical Field

[0001] The present invention relates to the technical field of material mechanical property testing, and in particular to a method, device, medium and product for testing the tensile mechanical property of a metal material based on a small punch test. Background Art

[0002] In the study of the neutron irradiation performance of reactor materials, small specimens are essential for evaluating the mechanical properties of materials after irradiation to fully utilize the irradiation space, minimize sample-induced radioactivity, improve irradiation parameter accuracy, and reduce significant costs. Furthermore, in fields such as nuclear power and aerospace, a large number of equipment are exposed to harsh environments such as high temperature, high pressure, and neutron irradiation for long periods of time. Their material properties degrade over time, necessitating regular equipment safety assessments to ensure safe production. Material mechanical properties are key parameters for equipment safety assessments. Traditional mechanical property testing requires a large amount of material, and sampling from in-service equipment damages the overall structure. However, nondestructive testing methods are unable to obtain these parameters. In response to this situation, scientists proposed the small punch test in the 1980s. This technique, a minimally destructive testing method, can obtain mechanical properties of materials using only a small amount of material. After years of development, the small punch test has been adopted in various engineering fields. However, obtaining mechanical property parameters remains challenging due to material nonlinearity and nonlinear specimen geometric deformation. Currently, the main methods for obtaining material tensile properties using the small punch test are empirical correlation methods and finite element inversion methods. The empirical correlation method is simple and easy to operate, but the strength values ​​calculated by this method are less accurate. Although the finite element inversion method has higher accuracy, it requires the user to have finite element inversion technology, which is not conducive to the promotion and use of this method. Summary of the Invention

[0003] The purpose of the present invention is to provide a method, device, medium and product for testing the tensile mechanical properties of metal materials. The yield strength, tensile strength and true stress-strain curve of the material can be quickly obtained by simply processing the test force-deflection curve of a small punch rod. The results obtained are highly accurate and the principle is simple, which is convenient for engineering applications.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for testing the tensile mechanical properties of a metal material, comprising:

[0006] Obtaining a force-deflection curve of a target metal material; the force-deflection curve is obtained by performing a small punch test on the target metal material;

[0007] Determine a first deflection point, a second deflection point, and a third deflection point; the first deflection point, the second deflection point, and the third deflection point are three adjacent points with different positions from left to right on the abscissa of the force-deflection curve;

[0008] Determine a first area and a second area based on the first deflection point, the second deflection point, the third deflection point and the force-deflection curve; the first area is the area of ​​a region enclosed by a vertical line where the first deflection point is located, a vertical line where the second deflection point is located, the abscissa axis of the coordinate system where the force-deflection curve is located, and the force-deflection curve; the second area is the area of ​​a region enclosed by a vertical line where the second deflection point is located, a vertical line where the third deflection point is located, the abscissa axis of the coordinate system where the force-deflection curve is located, and the force-deflection curve;

[0009] Calculating the yield strength and tensile strength of the target metal material according to the first area and the second area;

[0010] Calculating material parameters according to the yield strength and tensile strength of the target metal material;

[0011] The true stress-strain curve of the target metal material is obtained according to the material parameters and the Hollomon formula.

[0012] A computer device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the computer program to implement the steps of the above-mentioned method for testing the tensile mechanical properties of metal materials.

[0013] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for testing the tensile mechanical properties of metal materials.

[0014] A computer program product includes a computer program, which implements the steps of the above-mentioned method for testing the tensile mechanical properties of metal materials when executed by a processor.

[0015] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the present invention provides a method, device, medium and product for testing the tensile mechanical properties of metal materials to obtain the force-deflection curve of the target metal material; the force-deflection curve is obtained by performing a small punch test on the target metal material; the first deflection point, the second deflection point and the third deflection point are determined; the first deflection point, the second deflection point and the third deflection point are three adjacent points with different positions from left to right on the horizontal axis of the force-deflection curve; the first area and the second area are determined according to the first deflection point, the second deflection point and the third deflection point and the force-deflection curve; the first area is the first area and the second area is the second area. The area of ​​the region enclosed by the vertical line where the first deflection point is located, the vertical line where the second deflection point is located, the horizontal axis of the coordinate system where the force-deflection curve is located, and the force-deflection curve; the second area is the area enclosed by the vertical line where the second deflection point is located, the vertical line where the third deflection point is located, the horizontal axis of the coordinate system where the force-deflection curve is located, and the force-deflection curve; the yield strength and tensile strength of the target metal material are calculated based on the first area and the second area; the material parameters are calculated based on the yield strength and tensile strength of the target metal material; the true stress-strain curve of the target metal material is obtained based on the material parameters and the Hollomon formula. The present invention only requires simple processing of the force-deflection curve of the small punch test to quickly obtain the yield strength, tensile strength and true stress-strain curve of the material. The obtained results are highly accurate and the principle is simple, which is convenient for engineering application. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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. 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.

[0017] Figure 1 A schematic flow chart of a method for testing the tensile mechanical properties of a metal material provided in Example 1 of the present invention;

[0018] Figure 2 A schematic diagram of a specific implementation process of the method for testing the tensile mechanical properties of metal materials provided in Example 1 of the present invention;

[0019] Figure 3 A schematic structural diagram of a small punch test device provided in Example 1 of the present invention;

[0020] Figure 4 A typical force-deflection curve of the small punch test provided in Example 1 of the present invention;

[0021] Figure 5 A schematic diagram of the area enclosed by the calculated force-deflection curve and the abscissa provided in Example 1 of the present invention;

[0022] Figure 6 The force-deflection curve of the CLF-1 steel small punch test provided in Example 1 of the present invention;

[0023] Figure 7 Comparison results of the true stress-strain curve of CLF-1 steel obtained by the small punch test provided in Example 1 of the present invention and the true stress-strain curve obtained by the uniaxial tensile test;

[0024] Figure 8 This is a diagram of the internal structure of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] The purpose of the present invention is to provide a method, device, medium and product for testing the tensile mechanical properties of metal materials, aiming to simply process the force-deflection curve of a small punch test to quickly obtain the material's yield strength, tensile strength and true stress-strain curve. The results obtained are highly accurate and the principle is simple, which is convenient for engineering applications.

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] Example 1

[0029] like Figure 1 and Figure 2 As shown, a method for testing the tensile mechanical properties of a metal material in this embodiment includes:

[0030] S1: Obtaining a force-deflection curve of a target metal material; the force-deflection curve is obtained by performing a small punch test on the target metal material.

[0031] This embodiment is applicable to ductile metal materials that are macroscopically isotropic and conform to power hardening. Figure 3 The small punch test device shown is tested in accordance with the method recommended by the national standard GB / T29459.2-2012. The metal materials are tested with reference to the method recommended by the national standard GB / T29459.2-2012. Figure 3The upper and lower clamps are used to clamp the specimen. The clamp support is divided into two parts, which are connected by threads. Tightening the threads allows the upper and lower clamps to clamp the specimen. The testing machine then transmits force to the ceramic bead through the pressure rod. The ceramic bead presses down the target metal material specimen, causing the specimen to bend and deform. The ceramic rod records the degree of completeness (i.e., deflection) of the target metal material specimen.

[0032] The target metal material sample has a diameter of D = 10 mm, a thickness of t = 0.5 mm, a radius of the small punch spherical indenter r = 1.25 mm, a lower fixture aperture d = 4 mm, and a lower fixture chamfer of 0.2 mm × 45°. The force-deflection curve is obtained by recording the force applied to the target metal material sample (i.e., the force applied by the pressure rod to the sample downward) and the change in the deflection of the target metal material sample. The obtained force-deflection curve is shown in FIG. Figure 4 shown. Figure 4 A typical force-deflection curve of a small punch test is given, which reflects the response of the material under external force.

[0033] S2: Determine a first deflection point, a second deflection point and a third deflection point; the first deflection point, the second deflection point and the third deflection point are three adjacent points with different positions from left to right on the horizontal coordinate of the force-deflection curve.

[0034] S3: Determine the first area and the second area based on the first deflection point, the second deflection point, the third deflection point and the force-deflection curve; the first area is the area of ​​the area enclosed by the vertical line where the first deflection point is located, the vertical line where the second deflection point is located, the horizontal axis of the coordinate system where the force-deflection curve is located, and the force-deflection curve; the second area is the area of ​​the area enclosed by the vertical line where the second deflection point is located, the vertical line where the third deflection point is located, the horizontal axis of the coordinate system where the force-deflection curve is located, and the force-deflection curve.

[0035] exist Figure 5 In the example, select three deflection points in sequence (the first deflection point u A , the second deflection point u B , the third deflection point u C ), calculate the area enclosed by the force-deflection curve and the horizontal coordinate between two adjacent deflection points, and obtain two area values, namely the first area A1 and the second area A2. Figure 5 The force-deflection curve in is Figure 4 The force-deflection curve is shown.

[0036] It should be noted that this embodiment is applicable to metal materials with different elastic moduli. The yield strength and tensile strength of the materials are bilinearly related to the two areas under the force-deflection curve. The three deflection points selected in this embodiment range from 0.1 mm to the deflection corresponding to the crack initiation point of the target metal material sample.

[0037] S4: Calculating the yield strength and tensile strength of the target metal material according to the first area and the second area.

[0038] S5: Calculating material parameters according to the yield strength and tensile strength of the target metal material.

[0039] S6: Obtaining a true stress-strain curve of the target metal material according to the material parameters and the Hollomon formula.

[0040] The calculation formula for the yield strength described in S4 is as follows:

[0041] R p0.2 =w a ×A1+w b ×A2+w c (1);

[0042] Among them, R p0.2 is the yield strength of the target metal material; A1 is the first area; A2 is the second area; w a 、w b and w c is the model constant.

[0043] The calculation formula of the tensile strength described in S4 is as follows:

[0044] R m =w d ×A1+w e ×A2+w f (2);

[0045] Among them, R m is the tensile strength; A1 is the first area; A2 is the second area; w d 、w e and w f is the model constant.

[0046] Substituting the calculated first area A1 and second area A2 into equations (1) and (2) yields the yield strength and tensile strength of the target metal material. The small punch test force at the same deflection exhibits a bilinear relationship with the yield strength and tensile strength of the material.

[0047] The above w a ~w f is the model constant, and the value of the model constant is related to the first deflection point u A , the second deflection point u B and the third deflection point u C The model constants can be obtained through finite element simulation calibration. For example, when the three deflections u are selected A ,uB and u C When taking 0.1mm, 0.45mm and 1.0mm respectively, w a ~w f The values ​​of are 6.347, -1.168, -73.069, -0.706, 1.316 and -5.245 respectively. In this embodiment, only w a ~w f After recalibrating the model constants, this method can be used to process small punch test data with different thicknesses, different lower fixture sizes, and different radii of spherical indenters.

[0048] In S5, material parameters are calculated based on the yield strength and tensile strength of the target metal material, specifically including:

[0049] The hardening index is calculated based on the yield strength and tensile strength of the target metal material; the calculation formula of the hardening index is as follows:

[0050] ε 0.2 =R p0.2 / E+0.002(3);

[0051]

[0052] Among them, ε 0.2 is the true strain corresponding to the yield strength; R p0.2 is the yield strength of the target metal material; E is the elastic modulus of the target metal material, which can be determined by referring to relevant literature, for example, the elastic modulus of steel is about 200 GPa; e is a natural constant; n is the hardening index; R m For tensile strength.

[0053] The strength coefficient is calculated based on the hardening index and the tensile strength; the hardening index and the strength coefficient constitute the material parameters. The calculation formula of the strength coefficient is as follows:

[0054] K=R m ·e n / n n (5);

[0055] Among them, K is the strength coefficient; R m is the tensile strength; e is the natural constant; n is the hardening index.

[0056] S6 obtains the true stress-strain curve of the target metal material according to the material parameters and the Hollomon formula, specifically including:

[0057] The true stress-strain curve of the target metal material is obtained according to the strength coefficient, the hardening index and the Hollomon formula; the Hollomon formula is as follows:

[0058]

[0059] Wherein, σ is the stress of the target metal material; E is the elastic modulus of the target metal material; ε is the strain; n is the hardening index; K is the strength coefficient; σ y It is the initial stress at which the target metal material undergoes plastic deformation.

[0060] The true stress-strain curve obtained in this embodiment is shown in FIG. Figure 7 shown.

[0061] According to the yield strength, tensile strength and true stress-strain curve obtained in the above steps, a rapid evaluation of the radiation resistance of metal materials based on small specimens can be achieved, which is helpful for the research and development of radiation-resistant metals. At the same time, the small punch test is a micro-destructive testing method. The yield strength, tensile strength and true stress-strain curve obtained in the above steps can also be used for safety assessment of in-service pressure equipment.

[0062] The following is a detailed description of the process of obtaining the true stress-strain curve using CLF-1 steel as an example:

[0063] use Figure 3 The small punch test device shown in the figure is used to test CLF-1 steel according to the method recommended by the national standard GB / T29459.2-2012. The force acting on the sample and the deflection change of the sample are recorded by the pressure rod and the ceramic rod respectively. Figure 6 The force-deflection curve of the CLF-1 steel small punch test is obtained; the three deflection points u A ,u B and u C Take 0.1mm, 0.45mm and 1.0mm in turn, refer to Figure 5, and calculate the values ​​of A1 and A2 as 193.4 and 564.1 respectively. Substitute A1 and A2 into formula (1) and formula (2), and then calculate the yield strength value of 495.6MPa and the tensile strength of 600.8MPa from the small punch test. The yield strength and tensile strength obtained from the standard uniaxial tensile test are 485.9MPa and 627.8MPa respectively. In general, the yield strength and tensile strength obtained from the small punch test have an error within 5%. Substitute the yield strength and tensile strength obtained from the small punch test into formula (3) to formula (5), and the true stress-strain curve of the material can be calculated. Figure 7Comparison of the true stress-strain curve for CLF-1 steel obtained from a small punch test and a uniaxial tensile test. These results demonstrate that the yield strength, tensile strength, and true stress-strain curve calculated using this embodiment are highly accurate. Furthermore, the experimental procedure and calculation method are relatively simple, making them suitable for practical engineering applications.

[0064] In actual use, if the sample size, test fixture size, and indenter radius do not conform to this implementation plan, this method is also applicable. a ~w f The model constants can be recalibrated.

[0065] This embodiment proposes a method for testing the tensile mechanical properties of metal materials by a small punch test based on correlation analysis. This embodiment relates to the field of mechanical property testing of irradiated materials and materials of equipment in long-life service.

[0066] It can be used for mechanical property testing of radiation-resistant materials and safety assessment of pressure-bearing equipment in harsh environments.

[0067] Based on correlation analysis and finite element simulation, this embodiment proposes a technical theoretical system for obtaining material yield strength, tensile strength and true stress-strain curve by small punch test, which solves the problem of material nonlinearity and geometric deformation nonlinearity faced in the process of obtaining material tensile mechanical properties by small punch test. The principle is simple, easy to understand, high in precision, and convenient for engineering application. This method can quantitatively evaluate the effect of neutron irradiation on the tensile mechanical properties of materials, overcoming the shortcomings of standard tensile specimens being too large to enter the irradiation channel, large radioactive dose, and large irradiation gradient, which is beneficial to the research and development of high-temperature resistant and radiation-resistant materials in my country and the rapid evaluation of mechanical properties. At the same time, this embodiment can also perform micro-damage sampling and testing on in-service components to achieve quantitative evaluation of service degradation of material mechanical properties, ultimately providing data support for the safety assessment of in-service equipment. It also has significant advantages for micro-damage detection of mechanical properties of materials in service pressure-bearing equipment and characterization of mechanical properties of precious metals.

[0068] Example 2

[0069] A computer device includes: a memory, a processor, and a computer program stored in the memory and executable on the processor. The processor executes the computer program to implement the steps of a method for testing the tensile mechanical properties of a metal material in Example 1.

[0070] Example 3

[0071] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a method for testing the tensile mechanical properties of a metal material in Example 1.

[0072] Example 4

[0073] A computer program product includes a computer program, which, when executed by a processor, implements the steps of a method for testing the tensile mechanical properties of a metal material in Example 1.

[0074] Example 5

[0075] A computer device, which may be a database, may have an internal structure as shown in FIG. Figure 8 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O) and a communication interface. The processor, memory and input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and computer program in the non-volatile storage medium. The database of the computer device is used to store pending transactions. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a method for testing the tensile mechanical properties of a metal material in Example 1.

[0076] It should be noted that the object information (including but not limited to object device information, object personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in the present invention are all information and data authorized by the object or fully authorized by all parties, and the collection, use and processing of relevant data must comply with the relevant laws, regulations and standards of relevant countries and regions.

[0077] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided by the present invention may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processor involved in each embodiment provided by the present invention may be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, etc., but are not limited to these.

[0078] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A method for testing the tensile mechanical properties of metal materials, characterized in that: include: Obtaining a force-deflection curve of a target metal material; the force-deflection curve is obtained by performing a small punch test on the target metal material; Determine a first deflection point, a second deflection point, and a third deflection point; the first deflection point, the second deflection point, and the third deflection point are three adjacent points with different positions from left to right on the abscissa of the force-deflection curve; Determine a first area and a second area based on the first deflection point, the second deflection point, the third deflection point and the force-deflection curve; the first area is the area of ​​a region enclosed by a vertical line where the first deflection point is located, a vertical line where the second deflection point is located, the abscissa axis of the coordinate system where the force-deflection curve is located, and the force-deflection curve; the second area is the area of ​​a region enclosed by a vertical line where the second deflection point is located, a vertical line where the third deflection point is located, the abscissa axis of the coordinate system where the force-deflection curve is located, and the force-deflection curve; The yield strength and tensile strength of the target metal material are calculated based on the first area and the second area; the yield strength is calculated as follows: R p0.2 =w a ×A1+w b ×A2+w c ; Among them, R p0.2 is the yield strength of the target metal material; A1 is the first area; A2 is the second area; w a 、w b and w c is the model constant; The calculation formula of the tensile strength is as follows: R m =w d ×A1+w e ×A2+w f ; Among them, R m is the tensile strength; A1 is the first area; A2 is the second area; w d 、w e and w f is the model constant; Calculating material parameters according to the yield strength and tensile strength of the target metal material; The true stress-strain curve of the target metal material is obtained according to the material parameters and the Hollomon formula.

2. A method for testing the tensile mechanical properties of metal materials according to claim 1, characterized in that: The material parameters are calculated based on the yield strength and tensile strength of the target metal material, specifically including: Calculating a hardening index based on the yield strength and tensile strength of the target metal material; A strength coefficient is calculated based on the hardening index and the tensile strength; the hardening index and the strength coefficient constitute the material parameters.

3. A method for testing the tensile mechanical properties of metal materials according to claim 2, characterized in that: Obtaining the true stress-strain curve of the target metal material according to the material parameters and the Hollomon formula specifically includes: The true stress-strain curve of the target metal material is obtained according to the strength coefficient, the hardening index and the Hollomon formula; the Hollomon formula is as follows: Wherein, σ is the stress of the target metal material; E is the elastic modulus of the target metal material; ε is the strain; n is the hardening index; K is the strength coefficient; σ y It is the initial stress at which the target metal material undergoes plastic deformation.

4. A method for testing the tensile mechanical properties of metal materials according to claim 2, characterized in that: The calculation formula of the hardening index is as follows: e 0.2 =R p0.2 / E+0.002; Among them, ε 0.2 is the true strain corresponding to the yield strength; R p0.2 is the yield strength of the target metal material; E is the elastic modulus of the target metal material; e is the natural constant; n is the hardening index; R m For tensile strength.

5. A method for testing the tensile mechanical properties of metal materials according to claim 2, characterized in that: The calculation formula of the strength coefficient is as follows: K=R m ·e n / n n ; Among them, K is the strength coefficient; R m is the tensile strength; e is the natural constant; n is the hardening index.

6. A computer device comprising: A memory and a processor with a computer program stored in the memory and capable of running on the processor, characterized in that the processor executes the computer program to implement the steps of a method for testing the tensile mechanical properties of a metal material as described in any one of claims 1-5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for testing the tensile mechanical properties of a metal material as described in any one of claims 1 to 5 are implemented.

8. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for testing the tensile mechanical properties of a metal material as described in any one of claims 1 to 5 are implemented.

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