Multiphase alloy plastic constitutive model and modeling method

Abstract

The invention discloses a multiphase alloy plastic constitutive model and a modeling method.The modeling method of the multiphase alloy plastic constitutive model comprises the steps that dynamic stress-strain data at different temperatures are obtained by designing a Hopkinson pressure bar experiment, and a JC-TANH constitutive model considering the flow softening effect is adopted; the model parameters are fitted and verified on the basis of experimental data, a data set under a large deformation condition is constructed, parameter determination is performed on the established plastic stress constitutive model on the basis of the data set, and finally construction of the alloy plastic constitutive model considering the dynamic recrystallization effect is completed. The model not only describes the influence of phase change on the material performance, but also can reflect the material softening caused by dynamic recrystallization, and the method provides guidance for the material modeling method considering the microstructure effect, and is of great significance for deeply revealing the microcosmic nature of the deformation and removal mechanism of the cutting material.

Description

Technical Field

[0001] The invention belongs to the field of high temperature deformation and processing of multiphase alloy materials, and in particular relates to a multiphase alloy plastic constitutive model and a modeling method. Background Art

[0002] The material constitutive model, also known as the mechanical constitutive equation of the material, or the stress-strain model of the material, is a mathematical expression that describes the mechanical properties of the material. It is usually described by the stress-strain relationship curve of the material. It mainly includes elastic models, plastic models and failure damage models. In cutting processing, the constitutive model usually refers to the plastic model. The plastic constitutive model usually includes phenomenological models, physical models and composite models of the two. The former is obtained based on the fitting of material stress-strain experimental data, while the latter is obtained by finding the correspondence between the microscopic physical characteristics and macroscopic characteristics during the deformation process of the material. The constitutive model can reflect the basic deformation state of the material, which is of great significance for understanding the deformation mechanism of the material in cutting processing. At the same time, when the material undergoes severe plastic deformation, it is usually accompanied by changes in the microstructure. Therefore, it is necessary to consider the influence of microstructure evolution in the constitutive model.

[0003] The Chinese patent with publication number CN113742934A proposed a method for establishing a constitutive model of duplex stainless steel by considering the martensitic phase transformation, and broadened the strain rate range of the constitutive equation. However, the deformation condition in this method is relatively small (strain is less than 12%), so the established model is obviously not applicable to large deformation conditions such as cutting (strain can reach more than 300%). In addition, the Chinese patent with publication number CN117972903A adds phase transformation effect parameters to the JC constitutive model based on the phase transformation effect of the material, making the model more suitable for practical applications. However, the influence of microstructure considered in this constitutive model is relatively simple.

[0004] In the case of titanium alloys, the material will undergo α Phase transformation β Phase affects the plastic mechanical behavior of the material. In addition, the dynamic recrystallization phenomenon is closely related to the thermal load of the material. During cutting, the material undergoes severe plastic deformation under high temperature and high strain, which inevitably leads to the evolution of microstructures such as material phase change and dynamic recrystallization. Therefore, it is necessary to comprehensively consider the influence of phase change and dynamic recrystallization effects on the macroscopic deformation behavior of the material and construct a material constitutive model that couples multiple microstructure evolution mechanisms. This is of great significance for deeply revealing the microscopic nature of the deformation and removal mechanism of cutting materials. Summary of the invention

[0005] The purpose of the present invention is to provide a plastic constitutive model and modeling method for multiphase alloys, which comprehensively considers the influence of phase transformation and dynamic recrystallization effects on the macroscopic deformation behavior of materials, so as to overcome the shortcomings of the existing models that only consider the microstructure form, and help to reveal the microscopic nature of the deformation and removal mechanism of cutting materials.

[0006] To achieve the above object, the present invention adopts the following technical solution: a multiphase alloy plastic constitutive modeling method, comprising the following steps: Considering the large deformation conditions of cutting, the material constitutive model that can reflect the large deformation conditions is selected as the transition function, and the parameters of the selected transition function are solved based on the stress-strain data under high temperature and high strain rate; Based on the obtained transition function model parameters, the stress-strain data sets under high temperature, large deformation and high strain rate of each single phase are constructed; Considering the work hardening and dynamic softening effects during material deformation, the plastic stress model of single-phase material is divided into the work hardening-dynamic recovery stage and the dynamic recrystallization stage based on the dynamic recrystallization kinetic equation. Based on the obtained plastic stress model of single-phase material, based on the stress mixing theory and on the assumption of material isotropy, the plastic stress of multiphase material is established as the sum of the product of the volume fraction of each single-phase material and its single-phase plastic stress. Combining the stress-strain data sets of each single phase under high temperature, large deformation and high strain rate, the material parameters in the plastic stress model of single-phase material based on the dynamic recrystallization kinetic equation are solved to obtain the plastic constitutive model of multiphase alloy considering the dynamic recrystallization effect.

[0007] Furthermore, the least squares fitting method is used to solve the parameters of the selected transition function.

[0008] Furthermore, the stress-strain curve data under high temperature and high strain rate are obtained based on Hopkinson pressure bar experiments.

[0009] Furthermore, the expressions for the work hardening-dynamic recovery stage and the dynamic recrystallization stage are:

[0010] in, m For different single phases; s WH-DRV is the plastic stress expression in the work hardening-dynamic recovery stage; s DRX is the plastic stress expression in the dynamic recrystallization stage; s s is the saturation stress; s 0 is the initial stress; s ssis the steady-state stress; k 2 is the dynamic softening coefficient; e c is the critical strain; e p is the peak strain; k d and n d is a material related constant.

[0011] Furthermore, the plastic stress model expression of multiphase materials is:

[0012] in, s is the plastic stress of multiphase material; s m is the different single-phase plastic stress; f m is the volume fraction of different single phases, and its value is related to temperature and can be obtained through test results at different temperatures.

[0013] Furthermore, the obtained voltage signal is processed by wave shifting, and the three-wave method is used to obtain the true stress and strain data of the material. Based on Hooke's law, the plastic stress-strain data is converted, and the material softening caused by adiabatic temperature rise is considered. The curve obtained from the experiment is corrected to obtain the stress-strain experimental curve under temperature and strain rate.

[0014] In addition, the present invention also provides a multiphase alloy plastic constitutive model, which is obtained by using the multiphase alloy plastic constitutive modeling method.

[0015] And the application of a multiphase alloy plastic constitutive model to simulate the work hardening and dynamic softening processes during alloy deformation.

[0016] The present invention can also provide a computer device, including a processor and a memory, the memory is used to store a computer executable program, the processor reads the computer executable program from the memory and executes it, and the processor can implement the above-mentioned multi-phase alloy plasticity constitutive modeling method when executing the computer executable program.

[0017] A computer-readable storage medium is also provided, in which a computer program is stored. When the computer program is executed by a processor, the above-mentioned multi-phase alloy plasticity constitutive modeling method can be implemented.

[0018] Compared with the existing methods, the present invention has the following beneficial technical effects: The present invention provides a constitutive modeling method for plasticity of multiphase alloys considering the dynamic recrystallization effect. Based on the stress mixing theory of multiphase materials, the classical stress-dislocation relationship and the dynamic recrystallization kinetic equation, a plastic stress constitutive model that comprehensively considers phase transformation and dynamic recrystallization is established. The model not only describes the influence of phase transformation on material properties, but also reflects the material softening caused by dynamic recrystallization, which is the basis for revealing the microscopic mechanism of material removal in cutting. Furthermore, taking Ti6Al4V as an example, the present invention realizes accurate modeling of material plastic stress under the combined effects of cutting temperature, large deformation, high strain rate, phase transformation and dynamic recrystallization, providing a theoretical basis for numerical simulation of material deformation, removal process and microstructure evolution in cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the fitting result of the curve of the variation of volume fraction of each phase of Ti6Al4V alloy with temperature in the example of the present invention.

[0020] Figure 2 This is the comprehensive stress-strain curve obtained from the Hopkinson pressure bar experiment of Ti6Al4V alloy in the example of the present invention.

[0021] Figure 3 The comparison results between the comprehensive stress-strain curve obtained by fitting the JC-TANH constitutive equation and the experimental results for the Ti6Al4V alloy in the example of the present invention.

[0022] Figure 4a The Ti6Al4V alloy in the present invention α The stress-strain data set under high temperature, high strain rate and large deformation conditions is obtained based on the JC-TANH constitutive equation; Figure 4b The Ti6Al4V alloy in the present invention β The stress-strain data set under high temperature, high strain rate and large deformation conditions was obtained based on the JC-TANH constitutive equation.

[0023] Figure 5 The plastic constitutive curve of Ti6Al4V alloy considering the dynamic recrystallization effect in the example of the present invention is compared with the experimental curve and the JC-THAN constitutive curve. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0025] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0026] Embodiment 1, the present invention provides a constitutive modeling method of multiphase alloy plasticity considering dynamic recrystallization effect, which specifically comprises the following steps: Step 1) Considering the work hardening and dynamic softening effects during material deformation, the plastic stress model of single-phase material is divided into two stages based on the dynamic recrystallization kinetic equation, including the work hardening-dynamic recovery (WH-DRV) stage and the dynamic recrystallization (DRX) stage, and its expression is:

[0027] in, m For different phases; s WH-DRV is the plastic stress expression in the work hardening-dynamic recovery stage; s DRX is the plastic stress expression in the dynamic recrystallization stage; s s is the saturation stress; s 0 is the initial stress; s ss is the steady-state stress; k 2 is the dynamic softening coefficient; e c is the critical strain; e p is the peak strain; k d and n d is a material related constant.

[0028] Step 2) Based on the plastic stress model of the single-phase material obtained in step 1), based on the stress mixing theory and the assumption of material isotropy, it is considered that the overall plastic stress of the multiphase material is equal to the sum of the product of the volume fraction of each single-phase material and its single-phase plastic stress. Therefore, the expression of the plastic stress model of the multiphase material is:

[0029] in, s is the plastic stress of multiphase material; s m is the different single-phase plastic stress; f m is the volume fraction of different single phases, and its value is related to temperature and can be obtained through test results at different temperatures.

[0030] Step 3) Design a Hopkinson pressure bar experiment. By designing the shape of the specimen, as well as the relevant experimental temperature and strain rate, carry out a dynamic experiment. After the obtained voltage signal is processed by wave shifting, the three-wave method is used to obtain the real stress and strain data of the material. Based on Hooke's law, the plastic stress-strain data is converted, and the material softening caused by adiabatic temperature rise is considered. The curve obtained in the experiment is corrected accordingly, and finally the stress-strain experimental curves at different temperatures and strain rates are obtained, laying the foundation for the acquisition of material parameters. Step 4), considering that the plastic strain of the material in the chip and the machined surface area during the cutting process is large (the large plastic strain of the material in the present invention refers to the strain can reach more than 300%), and the actual plastic strain of the Hopkinson pressure bar test (less than 30%) cannot meet the cutting deformation condition, so the material constitutive model that can reflect the large deformation condition is selected as the transition function. Here, the JC-TANH model is selected as the transition function, and its expression is as follows:

[0031] in, ; ; s is the plastic stress; e is the plastic strain; is the plastic strain rate; As the reference strain rate, the present invention takes 0.001 s -1 ; T r and T m are room temperature and material melting temperature respectively; A , B , n , C and m They are yield strength, hardening modulus, strain hardening coefficient, strain rate hardening coefficient and thermal softening coefficient, which are intrinsic parameters of the material and have different values ​​for different phase components based on the mixed theory; a , s , r , d and b is the model correction coefficient, which mainly works under large deformation conditions. Here it is assumed that the coefficient is the same under different phase compositions.

[0032] Furthermore, based on the stress-strain data obtained in step 3), the least squares method is used to fit and solve the parameters in the JC-TANH constitutive model. The solution method is as follows:

[0033] in, is the parameter vector value of different phases; N The number of curves used to optimize the parameters, here are the curves at different temperatures; M is the number of data points on each curve used to optimize the parameters, here are the different strain values ​​on the curve; For the i The first curve j The plastic stress measured at the point; i and j Here it corresponds to different temperatures and strains; For the i The first curve j The stress calculated according to the JC-TANH constitutive equation at point can be expressed as:

[0034] in, For the i The first curve m Volume fraction of phase; For the m The plastic stress of the phase was calculated using the JC-TANH constitutive equation.

[0035] Furthermore, on the basis of obtaining the transition function model parameters, the strain results were substituted into the JC-TANH constitutive model expression at different temperatures and strain rates to construct the stress-strain data sets of each single phase at high temperature, large deformation and high strain rate. Furthermore, based on the constructed stress-strain data set, the relevant material parameters in the plastic stress expression in step 1) are solved.

[0036] Furthermore, on the basis of completing the parameter solution, the plastic constitutive model of the multiphase alloy considering the dynamic recrystallization effect is finally constructed based on step 2), and compared and verified with the experimental results and the JC-TANH model results.

[0037] Based on the above-mentioned constitutive modeling method of multiphase alloy plasticity considering the dynamic recrystallization effect, taking Ti6Al4V alloy as an example, it mainly includes α and β Phase, specifically including the following steps: Step 1: Considering the work hardening and dynamic softening effects of Ti6Al4V alloy deformation, the plastic stress model of single-phase material is divided into two stages based on the dynamic recrystallization kinetic equation, and its expression is:

[0038] in, m For different phases, here is Ti6Al4V alloy α andβ Mutually; s WH-DRV is the plastic stress expression in the initial deformation stage; s DRX is the plastic stress expression in the dynamic recrystallization stage; s s is the saturation stress; s 0 is the initial stress; s ss is the steady-state stress; k 2 is the dynamic softening coefficient; e c is the critical strain; e p is the peak strain; k d and n d is a material related constant.

[0039] Step 2: Based on the plastic stress model of the single-phase material obtained in step 1, the plastic stress model of the Ti6Al4V alloy material is established based on the stress mixing theory. Its expression is:

[0040] in, s is the plastic stress of Ti6Al4V alloy material; s α and s β Ti6Al4V alloy α and β Plastic stress of phase; f α and f β Ti6Al4V alloy α and β The volume fraction of the phase, whose value is related to temperature, can be obtained through test results at different temperatures.

[0041] By observation Figure 1 The curve in the form of Arrhenius function is used to calculate the Ti6Al4V alloy β The phase fraction is used for curve fitting, and its expression is:

[0042] in, O , P , U and V are the parameters that need to be fitted; R is the gas constant, 8.314 J·mol -1 ·K-1 ; T is temperature / °C, when °C, f β = 1; for β The initial value of the phase volume fraction, the Ti6Al4V alloy used in this study, is .

[0043] The least square method is used to fit the parameters in the above expression. The results are shown in Table 1 and the fitted curve is shown in Figure 1 .

[0044] Table 1 β Phase volume fraction fitting parameter table

[0045] Step 3: Design the Hopkinson bar test. By designing the shape of the specimen, as well as the relevant experimental temperature and strain rate, a dynamic experiment is carried out. The experimental parameters are shown in Table 2. Finally, the stress-strain experimental curves at different temperatures and strain rates are obtained. Figure 2 .

[0046] Table 2 Hopkinson pressure bar test parameters

[0047] Step 4: Considering the large deformation conditions of cutting, the JC-TANH model is selected as the transition function to calibrate and correct the material constitutive model parameters, and the Ti6Al4V alloy is obtained based on the least squares method. α Harmony β The parameters of the phase are shown in Table 3, and the final fitting stress-strain curve is shown in Figure 3 .

[0048] Table 3 Optimized Ti6Al4V alloy α and β Constitutive model parameters of phase

[0049] Step 5: Based on step 4, considering different temperatures and strain rates, the strain results are substituted into the JC-TANH constitutive model expression to construct the stress-strain data set under high temperature, large deformation and high strain rate for each single phase. The temperature and strain rate used to construct the data set are shown in Table 4. α Harmony β The stress-strain curve of the phase is shown in Figure 4a and Figure 4b .

[0050] Table 4 Temperature and strain rate used to construct the data set

[0051] Step 6: Based on the constructed stress-strain data set, solve the relevant material parameters in the plastic stress expression in step 1. After completing the parameter solution, the two-phase ( α+β ) alloy plastic constitutive model and compared it with the experimental results and the JC-TANH model results. Figure 5 shown.

[0052] In summary, the present invention provides a modeling method for the plastic constitutive behavior of multiphase alloys facing high temperature, high strain and large deformation processes. Aiming at the different phase compositions of the alloy and the dynamic recrystallization effect in cutting, based on the stress mixing theory of multiphase materials, the classical stress-dislocation relationship and the dynamic recrystallization kinetic equation, a plastic stress constitutive model that comprehensively considers phase transformation and dynamic recrystallization is established. The model not only describes the influence of phase transformation on material properties, but also reflects the softening of materials caused by dynamic recrystallization. Taking Ti6Al4V alloy as an example, the dynamic stress-strain data at different temperatures are obtained by designing a Hopkinson pressure bar experiment, and the JC-TANH constitutive model considering the flow softening effect is adopted. The model parameters are fitted and verified based on the experimental data, and a data set under large deformation conditions is constructed. Based on the data set, the parameters of the plastic stress constitutive model established by the present invention are determined, and finally the construction of the plastic constitutive model of Ti6Al4V alloy considering the dynamic recrystallization effect is completed. By using the plastic constitutive model and modeling method of a multiphase alloy proposed in the present invention, a plastic constitutive model coupled with multiple microstructural mechanisms can be constructed according to the actual volume fraction of each phase of the multiphase alloy and the influence of dynamic recrystallization. The model is applicable to material processing processes with high temperature, high strain rate and large deformation conditions.

[0053] Embodiment 2: The present invention can also provide a plastic constitutive model of a multiphase alloy constructed based on the above modeling method.

[0054] At the same time, the multiphase alloy plastic constitutive model can be used to simulate the work hardening and dynamic softening processes during alloy deformation.

[0055] In addition, the present invention can also provide a computer device, including a processor and a memory, the memory is used to store a computer executable program, the processor reads part or all of the computer executable program from the memory and executes it, and when the processor executes part or all of the computer executable program, the multi-phase alloy plasticity constitutive modeling method described in the present invention can be implemented.

[0056] On the other hand, the present invention provides a computer-readable storage medium, in which a computer program is stored. When the computer program is executed by a processor, the constitutive modeling method of multi-phase alloy plasticity of the present invention can be implemented.

[0057] The computer device may be a laptop computer, a desktop computer or a workstation.

[0058] The processor described in the present invention may be a central processing unit (CPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC) or a readily available field programmable gate array (FPGA).

[0059] The memory of the present invention may be an internal storage unit of a laptop computer, a desktop computer or a workstation, such as a memory or a hard disk; or an external storage unit, such as a mobile hard disk or a flash memory card.

[0060] Computer-readable storage media may include computer storage media and communication media. Computer storage media include volatile and non-volatile, removable and non-removable media implemented by any method or technology for storing information such as computer-readable instructions, data structures, program modules or other data. Computer-readable storage media may include: read-only memory (ROM), random access memory (RAM), solid-state drive (SSD) or optical disk, etc. Among them, random access memory may include resistance random access memory (ReRAM) and dynamic random access memory (DRAM).

[0061] The above description shows and describes several preferred embodiments of the invention, but as mentioned above, it should be understood that the invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall be within the scope of protection of the claims attached to the invention without departing from the spirit and scope of the invention.

Claims

1. A constitutive modeling method for plasticity of a multiphase alloy, characterized in that: The following steps are involved: Considering the large deformation conditions of cutting, the material constitutive model that can reflect the large deformation conditions is selected as the transition function, and the parameters of the selected transition function are solved based on the stress-strain data under high temperature and high strain rate; Based on the obtained transition function model parameters, the stress-strain data sets under high temperature, large deformation and high strain rate of each single phase are constructed; Considering the work hardening and dynamic softening effects during material deformation, the plastic stress model of single-phase material is divided into the work hardening-dynamic recovery stage and the dynamic recrystallization stage based on the dynamic recrystallization kinetic equation. Based on the obtained plastic stress model of single-phase materials, based on the stress mixing theory and the assumption of material isotropy, the plastic stress of multiphase materials is the sum of the product of the volume fraction of each single-phase material and its single-phase plastic stress; Combining the stress-strain data sets of each single phase under high temperature, large deformation and high strain rate, the material parameters in the plastic stress model of single-phase material based on the dynamic recrystallization kinetic equation are solved to obtain the plastic constitutive model of multiphase alloy considering the dynamic recrystallization effect.

2. The constitutive modeling method of multiphase alloy plasticity according to claim 1, characterized in that: The least squares fitting method is used to solve the parameters of the selected transition function.

3. The constitutive modeling method of multiphase alloy plasticity according to claim 1, characterized in that: The stress-strain curve data under high temperature and high strain rate are obtained based on Hopkinson pressure bar experiments.

4. The constitutive modeling method of multiphase alloy plasticity according to claim 1, characterized in that: The expressions for work hardening-dynamic recovery stage and dynamic recrystallization stage are: in, m For different single phases; σ WH-DRV is the plastic stress expression in the work hardening-dynamic recovery stage; σ DRX is the plastic stress expression in the dynamic recrystallization stage; σ s is the saturation stress; σ 0 is the initial stress; σ ss is the steady-state stress; k 2 is the dynamic softening coefficient; ε c is the critical strain; ε p is the peak strain; k d and n d is a material related constant.

5. The constitutive modeling method of multiphase alloy plasticity according to claim 1, characterized in that: The plastic stress model expression of multiphase materials is: in, σ is the plastic stress of multiphase material; σ m is the different single-phase plastic stress; f m is the volume fraction of different single phases, and its value is related to temperature and can be obtained through test results at different temperatures.

6. The constitutive modeling method of multiphase alloy plasticity according to claim 1, characterized in that: The obtained voltage signal is processed by wave shifting, and the three-wave method is used to obtain the real stress and strain data of the material. Based on Hooke's law, the plastic stress-strain data is converted, and the material softening caused by adiabatic temperature rise is considered. The curve obtained in the experiment is corrected to obtain the stress-strain experimental curve under temperature and strain rate.

7. A plastic constitutive model for a multiphase alloy, characterized in that: The multiphase alloy is obtained by using the constitutive modeling method of plasticity of any one of claims 1 to 6.

8. An application of a plastic constitutive model for a multiphase alloy, characterized in that: Used to simulate the work hardening and dynamic softening processes during alloy deformation.

9. A computer device, characterized in that: The invention comprises a processor and a memory, wherein the memory is used to store a computer executable program, the processor reads the computer executable program from the memory and executes it, and when the processor executes the computer executable program, the multiphase alloy plasticity constitutive modeling method according to any one of claims 1 to 7 can be realized.

10. A computer-readable storage medium, characterized in that: A computer program is stored in the computer-readable storage medium, and when the computer program is executed by a processor, the constitutive modeling method of multi-phase alloy plasticity as described in any one of claims 1 to 7 can be implemented.

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