A quantitative prediction method and system for micro-scale plastic deformation behavior of magnesium alloys

Abstract

The present invention discloses a quantitative prediction method and system for micro-scale plastic deformation behavior of magnesium alloys, the method comprising: obtaining grain orientation distribution data of magnesium alloy materials; obtaining initial parameter values ​​of four deformation modes, namely basal slip, cylindrical slip, conical slip and tensile twinning; importing the grain orientation distribution data and the initial parameter values ​​of the four deformation modes into a quantitative prediction model for micro-scale plastic deformation behavior of magnesium alloys, and sequentially performing the following calculation steps: calculating the Schmidt factors of the four deformation modes; calculating the starting stress values ​​of the four deformation modes; starting the deformation mode with the smallest starting stress value; calculating the starting stress difference between adjacent grains; calculating the deformation transfer factor between adjacent grains; and calculating the deformation response indicator factor. The present invention can predict the starting deformation mode of each grain of magnesium alloy and the stress-strain transfer behavior of adjacent grains, and then quantitatively analyze the formation position and expansion path of strain bands in the micro-scale, providing a basis for optimizing alloy properties.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic deformation of metal materials, and in particular to a quantitative prediction method and system for micro-scale plastic deformation behavior of magnesium alloys. Background Art

[0002] The density of magnesium alloy is 1.8g / cm 3 , is the structural metal with the lowest density. In addition, magnesium alloys also have the characteristics of high specific strength, high specific stiffness, good heat dissipation performance, and good shock absorption performance. They can be widely used in aerospace, rail transportation, new energy vehicles, drones and other fields. However, compared with aluminum alloys, magnesium alloys have poor plasticity and are prone to local severe plastic deformation during loading, forming strain bands, which in turn cause fractures. Therefore, it is of great significance to establish a quantitative prediction method for the microscale plastic deformation behavior of magnesium alloys and quantitatively predict the quantitative relationship between the microstructure of magnesium alloy materials and the macroscopic strain bands, which is of great significance for evaluating the service performance of magnesium alloy materials and then optimizing the microstructure of magnesium alloy materials in a targeted manner.

[0003] In the process of implementing the technical method of the embodiment of the present invention, the inventor of this patent found at least the following technical problems in the prior art:

[0004] Crystal plasticity models can analyze the macroscopic plastic deformation behavior of materials from the perspectives of dislocation slip, twinning initiation, and microscopic work hardening effects. However, the fracture behavior of magnesium alloy materials is not only related to intracrystalline deformation behaviors such as dislocation slip and twinning activity, but also to the stress and strain transfer behavior between adjacent grains. Since crystal plasticity models do not consider the stress and strain transfer effects between grains and cannot present the spatial distribution of the plastic deformation behavior of a single grain, it is difficult for existing technologies to achieve quantitative prediction of the microscopic plastic deformation behavior of magnesium alloy materials. Summary of the invention

[0005] The embodiments of the present invention provide a method and system for quantitatively predicting the micro-scale plastic deformation behavior of a magnesium alloy. Compared with the prior art, the present invention establishes a quantitative relationship between the microstructure of the magnesium alloy and the slip and twinning activity of each grain in the material, and the stress-strain transfer behavior between adjacent grains in the step of predicting the micro-scale plastic deformation behavior of the magnesium alloy, and establishes a quantitative prediction model for the micro-scale plastic deformation behavior of the magnesium alloy based on the quantitative relationship. The model predicts the deformation mode initiated by each grain of the magnesium alloy during loading and the deformation transfer behavior between adjacent grains in the form of a numeralized surface distribution, thereby solving the problem that the prior art is difficult to achieve quantitative prediction of the micro-scale plastic deformation behavior of magnesium alloy materials.

[0006] An embodiment of the present invention provides a quantitative prediction method for micro-scale plastic deformation behavior of magnesium alloys, comprising:

[0007] Step 1: Obtain grain orientation distribution data of magnesium alloy materials;

[0008] Step 2: When the stress-strain curve obtained by the crystal plasticity model simulation is consistent with the stress-strain curve obtained by the experimental test, the initial parameter values ​​of the four deformation modes of basal slip, cylindrical slip, cone slip and tensile twinning in the optimized crystal plasticity model are obtained, including the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress;

[0009] Step 3: Import the grain orientation distribution data and the initial parameter values ​​of the four deformation modes into the quantitative prediction model of micro-scale plastic deformation behavior of magnesium alloys, and perform the following calculation steps in sequence:

[0010] Calculation step 1: Based on the grain orientation distribution data, calculate the Schmidt factors of basal slip, cylindrical slip, cone slip and tensile twinning within the grain;

[0011] Calculation step 2: Based on the initial critical starting stress, progressive hardening rate, initial hardening rate, steady-state starting stress and Schmidt factor of basal slip, cylindrical slip, cone slip and tensile twinning, the starting stress values ​​of basal slip, cylindrical slip, cone slip and tensile twinning in each grain are calculated. The calculation formula is as follows:

[0012] ,

[0013] ,

[0014] in, represents the deformation mode, It can be base slip, cylindrical slip, cone slip or tensile twinning. Indicates deformation mode The starting stress value, Deformation mode In Strain The critical starting stress at Deformation mode The initial critical starting stress, Deformation mode The steady-state starting stress, Deformation mode type The initial hardening rate, Deformation mode The progressive hardening rate, Indicates deformation mode The Schmidt factor of

[0015] Calculation step 3: Compare the starting stress values ​​corresponding to base slip, cylindrical slip, cone slip and tensile twinning, and start the deformation mode with the smallest starting stress value;

[0016] Calculation step 4: Calculate the starting stress difference between adjacent grains. The calculation formula is as follows:

[0017] ,

[0018] in, It indicates the starting stress difference between adjacent grains in magnesium alloy materials during tension or compression. is the critical starting stress required for the tensile or compressive deformation of grain 1 in the magnesium alloy material, is the critical starting stress required for the tensile or compressive deformation of grain 2 in the magnesium alloy material, and grains 1 and 2 are adjacent grains. is the Schmidt factor of the magnesium alloy grain 1 during tensile or compressive deformation, is the Schmidt factor of the grain 2 in the magnesium alloy material when it is stretched or compressed;

[0019] Calculation step 5: Calculate the deformation transfer factor between adjacent grains. The calculation formula is as follows:

[0020] ,

[0021] in, It is the deformation transfer factor when adjacent grains in magnesium alloy are stretched or compressed. is the angle between the slip vectors of adjacent grains, is the angle between the normal directions of the slip surfaces;

[0022] Calculation step 6: Calculate the deformation response indicator factor, the calculation formula is as follows:

[0023] ,

[0024] in, F It is a deformation response indicator factor, which can quantitatively characterize the formation and extension behavior of strain bands during the loading process of magnesium alloys.

[0025] Optionally, the step 1 specifically includes:

[0026] Cutting magnesium alloy samples;

[0027] Electrochemical polishing of magnesium alloy samples;

[0028] EBSD observation was performed on the magnesium alloy samples after surface treatment to obtain grain orientation distribution data.

[0029] Optionally, the step 2 specifically includes:

[0030] Conduct tensile and compression tests on magnesium alloy materials to obtain stress-strain curves of magnesium alloy materials;

[0031] A crystal plasticity model is established based on the Euler angles in the grain orientation distribution data;

[0032] By comparing the stress-strain curve obtained by crystal plasticity model simulation with the stress-strain curve obtained by experimental test, the parameter values ​​of the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, conical slip and tensile twinning in the crystal plasticity model are adjusted until the stress-strain curve obtained by simulation is consistent with the stress-strain curve obtained by experimental test;

[0033] The optimized parameter values ​​of initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, cone slip and tensile twinning are obtained.

[0034] Optionally, the calculation step 3 specifically includes:

[0035] Comparison of the starting stress values ​​of base slip , the starting stress value of cylindrical slip , the starting stress value of cone sliding and the starting stress value of tensile twinning size;

[0036] The deformation mode with the smallest starting stress value is started.

[0037] Optionally, the starting stress value of the base slip The calculation formula is as follows:

[0038] ,

[0039] Among them, the Schmidt factor of basal slip within the grain is calculated based on the grain orientation distribution data ; Basal slip in strain Critical starting stress The calculation formula is as follows:

[0040] .

[0041] Optionally, the starting stress value of the cylindrical slip The calculation formula is as follows:

[0042] ,

[0043] Among them, the Schmidt factor of the cylindrical slip within the grain is calculated based on the grain orientation distribution data ; Cylindrical slip in strain Critical starting stress The calculation formula is as follows:

[0044] .

[0045] Optionally, the starting stress value of the conical surface sliding is The calculation formula is as follows:

[0046] ,

[0047] Among them, the Schmidt factor of the conical slip within the grain is calculated based on the grain orientation distribution data ; Conical surface slip under strain Critical starting stress The calculation formula is as follows:

[0048] .

[0049] Optionally, the starting stress value of the tensile twin The calculation formula is as follows:

[0050] ,

[0051] Among them, the Schmidt factor of tensile twinning within the grain is calculated based on the grain orientation distribution data. ; Tensile twinning in strain Critical starting stress The calculation formula is as follows:

[0052] .

[0053] On the other hand, an embodiment of the present invention further provides a quantitative prediction system for micro-scale plastic deformation behavior of magnesium alloys, comprising:

[0054] A first calculation module is used to calculate the Schmidt factors of basal slip, cylindrical slip, cone slip and tensile twinning within the grain based on the grain orientation distribution data;

[0055] The second calculation module is used to calculate the starting stress values ​​of basal slip, cylindrical slip, conical slip and tensile twinning in each grain based on the initial critical starting stress, progressive hardening rate, initial hardening rate, steady-state starting stress and Schmidt factor of basal slip, cylindrical slip, conical slip and tensile twinning. The calculation formula is as follows:

[0056] ,

[0057] ,

[0058] in, represents the deformation mode, It can be base slip, cylindrical slip, cone slip or tensile twinning. Indicates deformation mode The starting stress value, Deformation mode In Strain The critical starting stress at Deformation mode The initial critical starting stress, Deformation mode The steady-state starting stress, Deformation mode type The initial hardening rate, Deformation mode The progressive hardening rate, Indicates deformation mode The Schmidt factor of

[0059] The third calculation module is used to compare the starting stress values ​​corresponding to the base slip, cylindrical slip, conical slip and tensile twinning, and start the deformation mode with the smallest starting stress value;

[0060] The fourth calculation module is used to calculate the starting stress difference between adjacent grains. The calculation formula is as follows:

[0061] ,

[0062] in, It indicates the starting stress difference between adjacent grains in magnesium alloy materials during tension or compression. is the critical starting stress required for the tensile or compressive deformation of grain 1 in the magnesium alloy material, is the critical starting stress required for the tensile or compressive deformation of grain 2 in the magnesium alloy material, and grains 1 and 2 are adjacent grains. is the Schmidt factor of the magnesium alloy grain 1 during tensile or compressive deformation, is the Schmidt factor of the grain 2 in the magnesium alloy material when it is stretched or compressed;

[0063] The fifth calculation module is used to calculate the deformation transfer factor between adjacent grains. The calculation formula is as follows:

[0064] ,

[0065] in, It is the deformation transfer factor when adjacent grains in magnesium alloy are stretched or compressed. is the angle between the slip vectors of adjacent grains, is the angle between the normal directions of the slip surfaces;

[0066] The sixth calculation module is used to calculate the deformation response indicator factor, and the calculation formula is as follows:

[0067] ,

[0068] in, F It is a deformation response indicator factor, which can quantitatively characterize the formation and extension behavior of strain bands during the loading process of magnesium alloys.

[0069] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0070] At the microscopic scale, during the loading process of magnesium alloy materials, microstructural evolutions such as slip or twinning will occur inside the grains to coordinate the applied strain. The deformation mode initiated by each grain is related to the grain orientation, loading direction and deformation transfer behavior between adjacent grains. The present invention provides a quantitative prediction method for the microscopic plastic deformation behavior of magnesium alloys. By constructing a quantitative relationship between the microstructure of magnesium alloys and the deformation mode initiated within the grains, the deformation transfer behavior between adjacent grains and the formation of macroscopic strain bands, a quantitative prediction model for the microscopic plastic deformation behavior of magnesium alloys is used to predict the deformation mode initiated within each grain of the magnesium alloy material during the loading process and the difficulty of stress-strain transfer between adjacent grains, and then quantitatively analyze the formation position and expansion path of the strain band at the microscopic scale, providing a basis for optimizing the microstructure of magnesium alloys and improving their service performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 This is an initial microstructure diagram of a magnesium alloy material in one embodiment of the present invention;

[0072] Figure 2 The experimental stress-strain curve and the simulated stress-strain curve of the magnesium alloy material under tensile and compressive loading in one embodiment of the present invention;

[0073] Figure 3 A distribution diagram of deformation modes of each grain when a magnesium alloy material is stretched and loaded in an embodiment of the present invention;

[0074] Figure 4 It is a surface distribution diagram of the deformation coordination factor between adjacent grains when the magnesium alloy material is tensile loaded in one embodiment of the present invention;

[0075] Figure 5 It is a surface distribution diagram of the starting stress value of each grain when the magnesium alloy material is tensile loaded in one embodiment of the present invention;

[0076] Figure 6 A surface distribution diagram of the starting stress difference between adjacent grains when the magnesium alloy material is tensile loaded in one embodiment of the present invention;

[0077] Figure 7 is the deformation response indicator factor of the magnesium alloy material under tensile loading in one embodiment of the present invention F Value distribution diagram;

[0078] Figure 8The figure is a simplified flow chart of a method for quantitatively predicting micro-scale plastic deformation behavior of magnesium alloys in one embodiment of the present invention. DETAILED DESCRIPTION

[0079] The embodiments of the present invention provide a method and system for quantitatively predicting the micro-scale plastic deformation behavior of a magnesium alloy, which solves the problem that it is difficult to quantitatively predict the micro-scale plastic deformation behavior of a magnesium alloy material in the prior art.

[0080] In order to better understand the quantitative prediction method and system for the micro-scale plastic deformation behavior of magnesium alloys, the following will be described in detail in conjunction with the drawings and specific implementation methods of the specification. Obviously, the embodiments described in the present invention 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.

[0081] Please refer to the following Figure 8 , a quantitative prediction method for micro-scale plastic deformation behavior of magnesium alloy in an embodiment of the present invention is described in detail.

[0082] Step 1: Obtain grain orientation distribution data of magnesium alloy materials.

[0083] Wherein, step 1 specifically includes the following sub-steps: cutting a magnesium alloy sample; performing electrochemical polishing on the magnesium alloy sample; performing EBSD observation on the surface-treated magnesium alloy sample to obtain grain orientation distribution data.

[0084] In a specific implementation, for example: first, a magnesium alloy sample is cut by wire cutting, and the sample size is: 5 mm (normal to the rolling plate) × 8 mm (rolling direction) × 6 mm (transverse direction of the rolling plate). The surface to be observed (rolling plane) is polished by mechanical polishing until there are no scratches on the surface, and then the sample is electrochemically polished to complete the surface treatment of the magnesium alloy sample. Finally, a scanning electron microscope (SEM) equipped with an electron backscatter diffraction (EBSD) probe is used to observe the surface-treated magnesium alloy sample to obtain grain orientation distribution data. When performing EBSD characterization, the scanning step length is 2μm, the scanning area is 4542μm×3374μm, and the initial microstructure of the magnesium alloy is as follows. Figure 1 As shown. Among them, EBSD is a powerful analytical tool that can quickly and accurately measure crystal orientation. It uses the diffraction phenomenon generated by the interaction between the electron beam in the SEM and the magnesium alloy sample to determine the crystal orientation by analyzing the diffraction pattern. In addition to providing rich grain orientation information, it can also obtain information including grain size, grain boundary type, phase distribution, etc.

[0085] Step 2: When the stress-strain curve obtained by simulating the crystal plasticity model is consistent with the stress-strain curve obtained by the experimental test, the parameter values ​​of the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, cone slip and tensile twinning in the optimized crystal plasticity model are obtained.

[0086] Among them, step 2 specifically includes the following sub-steps: performing tensile and compression tests on the magnesium alloy material, and obtaining the stress-strain curve of the magnesium alloy material through experimental testing; establishing a crystal plasticity model based on the Euler angle in the grain orientation distribution data, and performing tensile and compressive loading simulation on the crystal plasticity model; by comparing the stress-strain curve obtained by simulating the crystal plasticity model with the stress-strain curve obtained by experimental testing, adjusting the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, cone slip and tensile twinning in the crystal plasticity model until the stress-strain curve obtained by simulation and the stress-strain curve obtained by experimental testing are consistent; obtaining the optimized parameter values ​​of the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, cone slip and tensile twinning.

[0087] In the specific implementation process: magnesium alloy tensile and compression samples are cut by wire cutting, and the defects or microcracks caused by wire cutting are removed by mechanical grinding and polishing until there are no scratches on the surface. A universal material mechanical testing machine is used to perform tensile and compression tests on the magnesium alloy tensile and compression samples, respectively, with reference to the room temperature mechanical properties test standards for metal materials (such as GB / T 228-2010 "Room Temperature Tensile Test Method for Metallic Materials"). The stress-strain curve of the magnesium alloy material during the tensile and compression process is obtained by experimental testing.

[0088] Tensile test: Install the prepared magnesium alloy tensile and compression samples on the clamping device of the universal material mechanical testing machine, set the experimental parameters such as the tensile rate and test force measurement range, start the universal material mechanical testing machine, conduct tensile tests on the magnesium alloy tensile and compression samples, and record the test force, displacement and other data. Process the data and use drawing software to draw the stress-strain curve of the magnesium alloy during the tensile process.

[0089] Compression test: Install the prepared magnesium alloy tensile and compression samples on the compression device of the universal material mechanical testing machine, set the test parameters such as compression rate and test force measurement range, start the universal material mechanical testing machine, perform compression tests on the magnesium alloy tensile and compression samples, and record the test force, displacement and other data. Process the data and use drawing software to draw the stress-strain curve of the magnesium alloy during the compression process.

[0090] Extract the Euler angles from the grain orientation distribution data as the orientation data for establishing the crystal plasticity model, and use finite element analysis (FEA) software or dedicated crystal plasticity simulation software to establish the crystal plasticity model, which is a mathematical model that can describe the mechanical behavior of polycrystalline materials under complex stress states. Each pair of Euler angles in the crystal plasticity model corresponds to the orientation of each scanning step in the EBSD characterization, which means that for each scanning point or area in the EBSD data, its corresponding Euler angle needs to be extracted and input into the crystal plasticity model to accurately describe the grain orientation of the area.

[0091] Based on the crystal plasticity theory, the constitutive relations of four deformation mechanisms, namely basal slip, cylindrical slip, cone slip and tensile twinning, are defined. These relations usually include the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress parameters.

[0092] According to the experimental conditions, the tensile and compressive loading conditions are set for the crystal plasticity model, including the loading rate, loading direction, etc. The tensile and compressive loading simulations are performed on the crystal plasticity model to obtain the simulated stress-strain curves.

[0093] By comparing the stress-strain curve obtained by crystal plasticity model simulation with the stress-strain curve obtained by experimental test, if there is a difference between the two, it is necessary to adjust the parameter values ​​of the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, conical slip and tensile twinning in the crystal plasticity model. These parameter values ​​are adjusted iteratively and the simulation is re-performed until the established crystal plasticity model can simulate the stress-strain curve obtained from the experimental test under tensile and compressive loading.

[0094] Once a set of parameters is found that makes the simulation results consistent with the experimental results, these parameters need to be further verified to ensure that they can provide accurate predictions under different loading conditions and material states. The optimized parameter values ​​of the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, cone slip and tensile twinning are recorded and saved for subsequent material property prediction.

[0095] The optimized crystal plasticity model can simulate the stress-strain curves obtained from experimental tests under tensile and compressive loading, such as Figure 2 The optimized parameter values ​​of initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, conical slip and tensile twinning are shown in the following table.

[0096] Fitting parameter value table

[0097]

[0098] Step 3: Import the grain orientation distribution data and the initial parameter values ​​of the four deformation modes into the quantitative prediction model of micro-scale plastic deformation behavior of magnesium alloy, and perform calculation steps 1 to 6 in sequence.

[0099] Calculation step 1: Based on the grain orientation distribution data, calculate the Schmidt factors of basal slip, cylindrical slip, cone slip and tensile twinning within the grain.

[0100] In the specific implementation process, for example, based on the grain orientation distribution data, the orientation matrix or Euler angle of each grain, the slip direction or twinning direction of the basal slip system, cylindrical slip system, cone slip system and twinning system, and the normal direction of the slip plane or twinning plane are obtained. Substitute the above parameters into the calculation formula of the Schmidt factor to calculate the Schmidt factors of the basal slip, cylindrical slip, cone slip and tensile twinning in the grain.

[0101] Calculation step 2: Based on the initial critical starting stress, progressive hardening rate, initial hardening rate, steady-state starting stress and Schmidt factor of basal slip, cylindrical slip, cone slip and tensile twinning, the starting stress values ​​of basal slip, cylindrical slip, cone slip and tensile twinning in each grain are calculated. The calculation formula is as follows:

[0102] ,

[0103] ,

[0104] in, represents the deformation mode, It can be base slip, cylindrical slip, cone slip or tensile twinning. Indicates deformation mode The starting stress value, Deformation mode In Strain The critical starting stress at Deformation mode The initial critical starting stress, Deformation mode The steady-state starting stress, Deformation mode The initial hardening rate, Deformation mode The progressive hardening rate, Indicates deformation mode The Schmidt factor.

[0105] It should be noted that is a positive number greater than 0, The smaller it is, the easier it is to activate this deformation mode.

[0106] Calculation step 3: Compare the starting stress values ​​corresponding to basal slip, cylindrical slip, conical slip and tensile twinning, and start the deformation mode with the smallest starting stress value.

[0107] Among them, calculation step 3 specifically includes the following sub-steps: comparing the starting stress value of base slip , the starting stress value of cylindrical slip , the starting stress value of cone sliding and the starting stress value of tensile twinning size; the deformation mode with the smallest starting stress value will be started.

[0108] During the loading process, the deformation mode with the smallest starting stress value is activated first. Figure 3 As shown, the yellow marked grains initiate tensile twinning, the green grains initiate conical sliding, the light blue grains initiate cylindrical sliding, and the dark blue grains initiate basal sliding.

[0109] like Figure 5 As shown in the figure, the closer the color of the grain is to yellow, the greater the starting stress of the grain; the closer the color of the grain is to dark blue, the smaller the starting stress of the grain, and the easier it is for deformation to start in the grain, and then the starting stress difference between adjacent grains during tension or compression is calculated.

[0110] Starting stress value of base slip The calculation formula is as follows:

[0111] ,

[0112] Among them, the Schmidt factor of basal slip within the grain is calculated based on the grain orientation distribution data ; Basal slip in strain Critical starting stress The calculation formula is as follows:

[0113] .

[0114] Starting stress value of cylindrical slip The calculation formula is as follows:

[0115] ,

[0116] Among them, the Schmidt factor of the cylindrical slip within the grain is calculated based on the grain orientation distribution data ; Cylindrical slip in strain Critical starting stress The calculation formula is as follows:

[0117] .

[0118] Starting stress value of cone slip The calculation formula is as follows:

[0119] ,

[0120] Among them, the Schmidt factor of the conical slip within the grain is calculated based on the grain orientation distribution data ; Conical surface slip under strain Critical starting stress The calculation formula is as follows:

[0121] .

[0122] Starting stress value of tensile twinning The calculation formula is as follows:

[0123] ,

[0124] Among them, the Schmidt factor of tensile twinning within the grain is calculated based on the grain orientation distribution data. ; Tensile twinning in strain Critical starting stress The calculation formula is as follows:

[0125] .

[0126] Calculation step 4: Calculate the starting stress difference between adjacent grains. The calculation formula is as follows:

[0127] ,

[0128] in, It indicates the starting stress difference between adjacent grains in magnesium alloy materials during tension or compression. is the critical starting stress required for the tensile or compressive deformation of grain 1 in the magnesium alloy material, is the critical starting stress required for the tensile or compressive deformation of grain 2 in the magnesium alloy material, and grains 1 and 2 are adjacent grains. is the Schmidt factor of the magnesium alloy grain 1 during tensile or compressive deformation, It is the Schmidt factor of the grain 2 in the magnesium alloy material when it is tensile or compressive deformed.

[0129] It should be noted that and is a positive number greater than 0, or The larger the value, the greater the force required to initiate the deformation mode within Die 1 or Die 2. and A positive number between 0 and 0.5. or The larger the value, the smaller the stress required to start the deformation mode in grain 1 or grain 2. Since the deformation within the grain first occurs in the grain with smaller starting stress and then transfers to the grain with larger starting stress, the larger the starting stress difference, the more difficult it is to transfer deformation between adjacent grains.

[0130] like Figure 6 As shown in the figure, the closer the color of the grain boundary is to yellow, the greater the starting stress difference between adjacent grains, and the more difficult the deformation transfer is; the closer the color of the grain boundary is to dark blue, the smaller the starting stress difference between adjacent grains, and the easier the deformation transfer is.

[0131] Calculation step 5: Calculate the deformation transfer factor between adjacent grains. The calculation formula is as follows:

[0132] ,

[0133] in, It is the deformation transfer factor when adjacent grains in magnesium alloy are stretched or compressed. is the angle between the slip vectors of adjacent grains, is the angle between the normal directions of the slip surfaces.

[0134] It should be noted that the calculation based on the orientation of adjacent grains and Two angle values; is a value between 0 and 1. The larger the value, the easier it is for deformation to be transmitted between adjacent grains.

[0135] like Figure 4 As shown, the closer the grain boundary color is to yellow, the larger the deformation transfer factor is, which means that the deformation transfer between adjacent grains is easier; the closer the grain boundary color is to dark blue, the more difficult the deformation transfer between adjacent grains is.

[0136] Calculation step 6: Calculate the deformation response indicator factor, the calculation formula is as follows:

[0137] ,

[0138] in, F It is a deformation response indicator factor, which can quantitatively characterize the formation and extension behavior of strain bands during the loading process of magnesium alloys. That is, during the loading process of magnesium alloys, strain bands are easily formed at positions with lower deformation response indicator factor F values, and extend along positions with lower deformation response indicator factor F values.

[0139] It should be noted that since the deformation within the grains first occurs in the grains with smaller starting stress and then transfers to the grains with larger starting stress, the greater the starting stress difference, the more difficult it is to transfer deformation between adjacent grains. FThe region with smaller value emerges and moves along the deformation response indicator factor F Areas with smaller values ​​are expanded.

[0140] like Figure 7 As shown, the yellower the grain boundary color, the more it represents the deformation response indicator factor F The larger the value, the closer the grain boundary color is to dark blue, and the deformation response indicator factor is F The smaller the value, the easier it is for strain to initiate in the area with a smaller deformation response indicator factor F value (blue) during loading, and the strain will move along the deformation response indicator factor F. F The area with smaller value expands to form strain band, which in turn induces crack initiation.

[0141] An embodiment of the present invention further provides a quantitative prediction system for micro-scale plastic deformation behavior of magnesium alloys, comprising a first calculation module, a second calculation module, a third calculation module, a fourth calculation module, a fifth calculation module and a sixth calculation module.

[0142] The first calculation module is used to calculate the Schmidt factors of basal slip, cylindrical slip, cone slip and tensile twinning within the grain based on the grain orientation distribution data.

[0143] The second calculation module is used to calculate the starting stress values ​​of basal slip, cylindrical slip, conical slip and tensile twinning in each grain based on the initial critical starting stress, progressive hardening rate, initial hardening rate, steady-state starting stress and Schmidt factor of basal slip, cylindrical slip, conical slip and tensile twinning. The calculation formula is as follows:

[0144] ,

[0145] ,

[0146] in, represents the deformation mode, It can be base slip, cylindrical slip, cone slip or tensile twinning. Indicates deformation mode The starting stress value, Deformation mode In Strain The critical starting stress at Deformation mode The initial critical starting stress, Deformation mode The steady-state starting stress, Deformation mode type The initial hardening rate, Deformation mode The progressive hardening rate, Indicates deformation mode The Schmidt factor.

[0147] The third calculation module is used to compare the starting stress values ​​corresponding to the base slip, cylindrical slip, cone slip and tensile twinning, and start the deformation mode with the smallest starting stress value.

[0148] The fourth calculation module is used to calculate the starting stress difference between adjacent grains. The calculation formula is as follows:

[0149] ,

[0150] in, It indicates the starting stress difference between adjacent grains in magnesium alloy materials during tension or compression. is the critical starting stress required for the tensile or compressive deformation of grain 1 in the magnesium alloy material, is the critical starting stress required for the tensile or compressive deformation of grain 2 in the magnesium alloy material, and grains 1 and 2 are adjacent grains. is the Schmidt factor of the magnesium alloy grain 1 during tensile or compressive deformation, It is the Schmidt factor of the grain 2 in the magnesium alloy material when it is tensile or compressive deformed.

[0151] The fifth calculation module is used to calculate the deformation transfer factor between adjacent grains. The calculation formula is as follows:

[0152] ,

[0153] in, It is the deformation transfer factor when adjacent grains in magnesium alloy are stretched or compressed. is the angle between the slip vectors of adjacent grains, is the angle between the normal directions of the slip surfaces.

[0154] The sixth calculation module is used to calculate the deformation response indicator factor, and the calculation formula is as follows:

[0155] ,

[0156] in, F It is a deformation response indicator factor, which can quantitatively characterize the formation and extension behavior of strain bands during the loading process of magnesium alloys.

[0157] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A quantitative prediction method for micro-scale plastic deformation behavior of magnesium alloys, characterized in that: include: Step 1: Obtain grain orientation distribution data of magnesium alloy materials; Step 2: When the stress-strain curve obtained by the crystal plasticity model is consistent with the stress-strain curve obtained by the experimental test, the initial parameter values ​​of the four deformation modes of basal slip, cylindrical slip, cone slip and tensile twinning in the optimized crystal plasticity model are obtained, including the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress; Step 3: Import the grain orientation distribution data and the initial parameter values ​​of the four deformation modes into the quantitative prediction model of micro-scale plastic deformation behavior of magnesium alloys, and perform the following calculation steps in sequence: Calculation step 1: Based on the grain orientation distribution data, calculate the Schmidt factors of basal slip, cylindrical slip, cone slip and tensile twinning within the grain; Calculation step 2: Based on the initial critical starting stress, progressive hardening rate, initial hardening rate, steady-state starting stress and Schmidt factor of basal slip, cylindrical slip, cone slip and tensile twinning, the starting stress values ​​of basal slip, cylindrical slip, cone slip and tensile twinning in each grain are calculated. The calculation formula is as follows: ， ， in, represents the deformation mode, It can be base slip, cylindrical slip, cone slip or tensile twinning. Indicates deformation mode The starting stress value, Deformation mode In Strain The critical starting stress at Deformation mode The initial critical starting stress, Deformation mode The steady-state starting stress, Deformation mode type The initial hardening rate, Deformation mode The progressive hardening rate, Indicates deformation mode The Schmidt factor of Calculation step 3: Compare the starting stress values ​​corresponding to base slip, cylindrical slip, cone slip and tensile twinning, and start the deformation mode with the smallest starting stress value; Calculation step 4: Calculate the starting stress difference between adjacent grains. The calculation formula is as follows: ， in, It indicates the starting stress difference between adjacent grains in magnesium alloy materials during tension or compression. is the critical starting stress required for the tensile or compressive deformation of grain 1 in the magnesium alloy material, is the critical starting stress required for the tensile or compressive deformation of grain 2 in the magnesium alloy material, and grains 1 and 2 are adjacent grains. is the Schmidt factor of the magnesium alloy grain 1 during tensile or compressive deformation, is the Schmidt factor of the grain 2 in the magnesium alloy material when it is stretched or compressed; Calculation step 5: Calculate the deformation transfer factor between adjacent grains. The calculation formula is as follows: ， in, It is the deformation transfer factor when adjacent grains in magnesium alloy are stretched or compressed. is the angle between the slip vectors of adjacent grains, is the angle between the normal directions of the slip surfaces; Calculation step 6: Calculate the deformation response indicator factor, the calculation formula is as follows: ， in, F It is a deformation response indicator factor, which can quantitatively characterize the formation and extension behavior of strain bands during the loading process of magnesium alloys.

2. The method according to claim 1, characterized in that The step 1 specifically includes: Cutting magnesium alloy samples; Electrochemical polishing of magnesium alloy samples; EBSD observation was performed on the magnesium alloy samples after surface treatment to obtain grain orientation distribution data.

3. The method according to claim 1, characterized in that The step 2 specifically includes: Conduct tensile and compression tests on magnesium alloy materials to obtain stress-strain curves of magnesium alloy materials; A crystal plasticity model is established based on the Euler angles in the grain orientation distribution data; By comparing the stress-strain curve obtained by crystal plasticity model simulation with the stress-strain curve obtained by experimental test, the parameter values ​​of the initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, conical slip and tensile twinning in the crystal plasticity model are adjusted until the stress-strain curve obtained by simulation is consistent with the stress-strain curve obtained by experimental test; The optimized parameter values ​​of initial critical starting stress, progressive hardening rate, initial hardening rate and steady-state starting stress of basal slip, cylindrical slip, cone slip and tensile twinning are obtained.

4. The method according to claim 1, characterized in that The calculation step 3 specifically includes: Comparison of the starting stress values ​​of base slip , the starting stress value of cylindrical slip , the starting stress value of cone sliding and the starting stress value of tensile twinning size; The deformation mode with the smallest starting stress value is started.

5. The method according to claim 4, characterized in that The starting stress value of the base slip The calculation formula is as follows: ， Among them, the Schmidt factor of basal slip within the grain is calculated based on the grain orientation distribution data ; Basal slip in strain Critical starting stress The calculation formula is as follows: 。 6. The method according to claim 4, characterized in that The starting stress value of the cylindrical slip The calculation formula is as follows: ， Among them, the Schmidt factor of the cylindrical slip within the grain is calculated based on the grain orientation distribution data ; Cylindrical slip in strain Critical starting stress The calculation formula is as follows: 。 7. The method according to claim 4, characterized in that The starting stress value of the cone slip The calculation formula is as follows: ， Among them, the Schmidt factor of the conical slip within the grain is calculated based on the grain orientation distribution data ; Conical surface slip under strain Critical starting stress The calculation formula is as follows: 。 8. The method according to claim 4, characterized in that The starting stress value of the tensile twin The calculation formula is as follows: ， Among them, the Schmidt factor of tensile twinning within the grain is calculated based on the grain orientation distribution data. ; tensile twinning in strain Critical starting stress The calculation formula is as follows: 。 9. A quantitative prediction system for micro-scale plastic deformation behavior of magnesium alloys, characterized in that: include: A first calculation module is used to calculate the Schmidt factors of basal slip, cylindrical slip, cone slip and tensile twinning within the grain based on the grain orientation distribution data; The second calculation module is used to calculate the starting stress values ​​of basal slip, cylindrical slip, conical slip and tensile twinning in each grain based on the initial critical starting stress, progressive hardening rate, initial hardening rate, steady-state starting stress and Schmidt factor of basal slip, cylindrical slip, conical slip and tensile twinning. The calculation formula is as follows: ， ， in, represents the deformation mode, It can be base slip, cylindrical slip, cone slip or tensile twinning. Indicates deformation mode The starting stress value, Deformation mode In Strain The critical starting stress at Deformation mode The initial critical starting stress, Deformation mode The steady-state starting stress, Deformation mode type The initial hardening rate, Deformation mode The progressive hardening rate, Indicates deformation mode The Schmidt factor of The third calculation module is used to compare the starting stress values ​​corresponding to the base slip, cylindrical slip, conical slip and tensile twinning, and start the deformation mode with the smallest starting stress value; The fourth calculation module is used to calculate the starting stress difference between adjacent grains. The calculation formula is as follows: ， in, It indicates the starting stress difference between adjacent grains in magnesium alloy materials during tension or compression. is the critical starting stress required for the tensile or compressive deformation of grain 1 in the magnesium alloy material, is the critical starting stress required for the tensile or compressive deformation of grain 2 in the magnesium alloy material, and grains 1 and 2 are adjacent grains. is the Schmidt factor of the magnesium alloy grain 1 during tensile or compressive deformation, is the Schmidt factor of the grain 2 in the magnesium alloy material when it is stretched or compressed; The fifth calculation module is used to calculate the deformation transfer factor between adjacent grains. The calculation formula is as follows: ， in, It is the deformation transfer factor when adjacent grains in magnesium alloy are stretched or compressed. is the angle between the slip vectors of adjacent grains, is the angle between the normal directions of the slip surfaces; The sixth calculation module is used to calculate the deformation response indicator factor, and the calculation formula is as follows: ， in, F It is a deformation response indicator factor, which can quantitatively characterize the formation and extension behavior of strain bands during the loading process of magnesium alloys.

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