A method for coupled calculation of temperature and stress fields in laminar cooling of strip steel

Abstract

The application discloses a strip steel laminar cooling temperature field and stress field coupling calculation method, comprising the following steps: determining a phase change model considering deformation influence; establishing a strip steel three-dimensional geometric model in a laminar cooling process based on ANSYS-APDL language; performing mesh division; performing temperature field and stress field coupling solution calculation, and combining the phase change model considering deformation influence to determine whether phase change occurs, if phase change occurs, calculating current node phase change conversion rate and phase change latent heat; processing simulation calculation results to obtain a strip steel laminar cooling process temperature-time curve diagram and stress-time curve diagram, and ferrite, pearlite or bainite transformation amount. Compared with traditional laminar cooling temperature field and stress field coupling calculation, the application considers the influence of finishing deformation on phase change, and is more in line with actual conditions; compared with operation by using a finite element interface, the macro command established by using the APDL language can repeat modeling of the same type of problem by changing parameters, which is time-saving and efficient.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a method for calculating the coupling of temperature field and stress field in laminar cooling of strip steel based on ANSYS-APDL language, considering the influence of deformation. Background Technology

[0002] High-strength beam steel, characterized by its "high strength and thinness," is increasingly being used in automotive structural components to reduce vehicle weight and fuel consumption.

[0003] However, as strength increases, during the laminar cooling process after finishing rolling, uneven cooling in the width direction generates thermal stress, leading to residual stress within the material. Besides thermal stress, uneven phase transformation also generates structural stress within the strip. The combination of these two factors is the main cause of residual stress in high-strength beam steel. Residual stress generated during cooling can lead to poor strip shape at the time of shipment, or lateral bending after cutting by downstream users, resulting in a lower product qualification rate.

[0004] Currently, researchers calculate the residual stress of high-strength beam steel by establishing a coupled calculation model of temperature and stress fields during laminar cooling. In terms of phase transformation stress, they only consider ferrite, pearlite, or bainite phase transformations, without considering the influence of finishing rolling deformation on phase transformation. If the influence of finishing rolling deformation is not considered when calculating the phase transformation incubation period, it will lead to discrepancies between the judgment of phase transformation occurrence conditions and the actual situation. Summary of the Invention

[0005] This invention provides a method for calculating the coupling of temperature field and stress field in laminar cooling of strip steel, in order to solve the technical problem that the existing technology does not consider the influence of finishing rolling deformation when calculating the phase transformation incubation period, resulting in a difference between the judgment of the phase transformation occurrence conditions and the actual situation.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] On one hand, the present invention provides a method for coupled calculation of temperature and stress fields in laminar cooling of strip steel, the method comprising:

[0008] Determine the phase transition model that takes into account the effects of deformation;

[0009] A three-dimensional geometric model of strip steel for laminar cooling process was established based on ANSYS-APDL language;

[0010] Material parameters and element types are determined using the ANSYS-APDL language, and the model is meshed.

[0011] Based on the ANSYS-APDL language, simulation parameters are defined, and the temperature and stress fields are coupled and calculated using the meshed three-dimensional geometric model of the strip. Combined with the phase transformation model that considers the influence of deformation, it is determined whether a phase transformation has occurred. If a phase transformation has occurred, the phase transformation conversion rate and latent heat of phase transformation at the current node are calculated.

[0012] The simulation results are processed using ANSYS APDL language to obtain temperature-time curves and stress-time curves of the strip laminar cooling process, as well as the ferrite, pearlite, or bainite transformation variables.

[0013] Furthermore, determining the phase transition model that considers the effects of deformation includes:

[0014] The isothermal transformation curve of supercooled austenite in the strip was obtained through phase transformation experiments;

[0015] Based on the isothermal transformation curve of supercooled austenite, the incubation period for the transformation of austenite to ferrite, pearlite, and bainite, considering the influence of deformation, is obtained; wherein...

[0016] Incubation period τ of austenite-ferrite transformation considering deformation effects F The calculation formula is:

[0017]

[0018] In the formula, f is the incubation period for the isothermal transformation from austenite to ferrite obtained from the isothermal transformation curve of supercooled austenite. F (ε,T f Let be the deformation influence function, where ε is the finishing rolling strain, and T is the deformation influence function. f This refers to the finishing rolling deformation temperature.

[0019] The incubation period τ of austenite to pearlite transformation considering deformation effects P The calculation formula is:

[0020]

[0021] In the formula, To determine the incubation period for the isothermal transformation from austenite to pearlite, based on the isothermal transformation curve of supercooled austenite, f P (ε,T f Let be the deformation influence function, where ε is the finishing rolling strain, and T is the deformation influence function. f This refers to the finishing rolling deformation temperature.

[0022] Incubation period τ for austenite to bainite transformation considering deformation effects B The calculation formula is:

[0023]

[0024] In the formula, f is the incubation period for the isothermal transformation of austenite to bainite obtained from the isothermal transformation curve of supercooled austenite. B (ε,T f Let be the deformation influence function, where ε is the finishing rolling strain, and T is the deformation influence function. f This refers to the finishing rolling deformation temperature.

[0025] Based on the isothermal transformation curve of supercooled austenite, the values ​​of b and n in the kinetic equation of austenite phase transformation are calculated using the following formula;

[0026]

[0027]

[0028] In the formula, t s t e V represents the start and end times of the phase transformation at a specific temperature T in the isothermal transformation curve of supercooled austenite. s V e These are the phase transition variables at the corresponding time points.

[0029] Furthermore, the establishment of a three-dimensional geometric model of the strip steel for the laminar cooling process based on the ANSYS-APDL language includes:

[0030] The length, width, and height of the strip are defined and assigned values ​​using the APDL language.

[0031] Use the BLOCK command in the APDL language to create a three-dimensional geometric model of the strip.

[0032] Furthermore, the process of determining material parameters and element types based on the ANSYS-APDL language and meshing the model includes:

[0033] Use the MP command in the APDL language to define the material of the strip, use MPTEMP to define the temperature table, and use MPDATA to define the thermal conductivity K, specific heat C, elastic modulus EX, Poisson's ratio PRXY and coefficient of thermal expansion ALPX at different temperatures.

[0034] Use the ET command in the APDL language to define the cell type as SOLID5;

[0035] The LESIZE command in the APDL language is used to define the mesh size for each edge of the strip, and then the VMESH command is used to mesh the three-dimensional geometric model of the strip.

[0036] Furthermore, the simulation parameters are defined based on the ANSYS-APDL language, and the temperature and stress fields are coupled and calculated using the meshed three-dimensional geometric model of the strip. Combined with the phase transformation model considering deformation effects, it is determined whether a phase transformation has occurred. If a phase transformation has occurred, the phase transformation conversion rate and latent heat of phase transformation at the current node are calculated, including:

[0037] Based on the ANSYS-APDL language, laminar cooling process parameters and finishing rolling deformation parameters are defined to determine the initial temperature field, convection boundary conditions, and structural boundary conditions of the strip.

[0038] The total solution time T, the time step dt, and other output options are determined using the ANSYS-APDL language. After saving the model, the coupled temperature and stress field calculations for each time step begin. The other output options include the result output frequency and file format.

[0039] The macro file for phase transformation calculation, which considers the influence of deformation and is written in ANSYS-APDL language, is called to perform phase transformation calculations. The temperature value of each node at the current time is obtained and substituted into the phase transformation model that considers the influence of deformation to determine whether a ferrite phase transformation, pearlite phase transformation, or bainite phase transformation has occurred. If a phase transformation has occurred, the phase transformation conversion rate and latent heat of phase transformation at the current node are calculated, and the latent heat of phase transformation is loaded into the thermal boundary conditions of the next time step in the form of heat generation rate. Then, the temperature field and stress field coupling of the next time step is performed until the phase transformation is completed.

[0040] Furthermore, the process parameters for laminar cooling and finishing rolling deformation, defined using the ANSYS-APDL language, and the determination of the initial temperature field, convective boundary conditions, and structural boundary conditions for the strip include:

[0041] The APDL language is used to define and assign values ​​to the laminar flow cooling process parameters, which include the length of the laminar flow cooling water section, the number of water sections, the length of the air cooling section, the water temperature, and the strip speed.

[0042] The APDL language is used to define and assign values ​​to the finishing mill deformation parameters; wherein, the finishing mill deformation parameters include the temperature and deformation amount of the final finishing mill pass;

[0043] Use the NSEL and IC commands in the APDL language to apply an initial temperature field to the strip.

[0044] Use the APDL language SFA command to apply the convective heat transfer coefficient h and the ambient temperature Tw to the strip.

[0045] Use the APDL language DA command to apply symmetric displacement constraints to the strip symmetry plane.

[0046] Further, the macro file for phase transformation calculation considering deformation effects, written in ANSYS-APDL language, is invoked to perform phase transformation calculations, obtain the temperature value of each node at the current time, and input into the phase transformation model considering deformation effects to determine whether a ferrite, pearlite, or bainite phase transformation has occurred. If a phase transformation has occurred, the phase transformation conversion rate and latent heat of phase transformation at the current node are calculated, and the latent heat of phase transformation is loaded into the thermal boundary conditions of the next time step as a heat generation rate. Then, temperature and stress field coupling is performed in the next time step until the phase transformation is completed, including:

[0047] Using the APDL language *DO and *ENDDO commands, perform the following computation steps for each node:

[0048] Based on the phase transition model that takes into account the effects of deformation, the incubation period of each node at the current temperature is calculated.

[0049] The following formula is used to accumulate the ratio of time step to phase transformation incubation period to determine whether ferrite, pearlite or bainite has reached the phase transformation start point at the current node temperature and at the current time.

[0050]

[0051] In the formula, dt is the time step, and τ(T) is the isothermal transformation incubation period at the corresponding temperature, which is obtained from the phase transformation experiment of the material. When the sum of the ratios of the two is 1, the austenite undergoes transformation.

[0052] If a phase transformation occurs, the phase transformation variables of ferrite, pearlite, and bainite are calculated using the following formula:

[0053] X = 1 - exp(-bt) n )

[0054] In the formula, X is the transformation variable, t is the time after the phase transformation begins, and b and n are the values ​​of b and n in the kinetic equation of the austenitic phase transformation, which are obtained through phase transformation experiments.

[0055] The latent heat of phase transformation q of ferrite, pearlite, or bainite at the current node is calculated according to the following formula:

[0056]

[0057] In the formula, ρ is the material density, H(T) is the enthalpy of austenite transformation, and ΔX is the amount of austenite transformed per unit time Δt.

[0058] Using the APDL language BF command, the latent heat of phase change at the current node is loaded into the next step's boundary conditions in the form of heat generation rate, and then the next step of temperature field and stress field coupling solution calculation is performed.

[0059] Furthermore, the establishment of the three-dimensional geometric model of the strip steel during the laminar flow cooling process includes:

[0060] A quarter-size model is established based on the symmetry of the strip geometry and boundary conditions.

[0061] The beneficial effects of the technical solution provided by this invention include at least the following:

[0062] This invention can predict the temperature and stress values ​​at different nodes of high-strength beam steel strip during laminar cooling, as well as predict the phase changes of ferrite, pearlite, and bainite. By using the parametric design language APDL of ANSYS finite element software and inputting laminar cooling process parameters, including the length of the water-cooled section, the number of water-cooled sections, the length of the air-cooled section, water temperature, and strip speed, a three-dimensional temperature and stress field model can be established to calculate the temperature and stress fields of the high-strength beam steel and predict the phase changes. Compared with traditional laminar cooling temperature and stress field coupled calculations, this invention considers the influence of finishing rolling deformation on phase transformation, which is more consistent with reality. Compared with operating using the finite element interface, the macro commands established by APDL language in this invention can repeatedly model the same type of problem by changing parameters, making it more time-saving and efficient. Attached Figure Description

[0063] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0064] Figure 1 This is a schematic diagram of the execution flow of the strip laminar cooling temperature field stress field coupling calculation method provided in the embodiments of the present invention;

[0065] Figure 2 This is the TTT curve of the high-strength beam steel provided in the embodiments of the present invention;

[0066] Figure 3 This is the dynamic CCT curve of the high-strength beam steel provided in the embodiments of the present invention;

[0067] Figure 4 This is the temperature-stress versus time curve of the high-strength beam steel provided in the embodiments of the present invention;

[0068] Figure 5 This is the curve showing the change of width temperature difference-phase variable over time for the high-strength beam steel provided in this embodiment of the invention. Detailed Implementation

[0069] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0070] First Embodiment

[0071] First, it should be noted that both the finishing rolling deformation temperature and the amount of deformation will cause changes in the internal distortion energy of the material, thus affecting the phase transformation incubation period. If the influence of finishing rolling deformation is not considered when calculating the phase transformation incubation period, the judgment of the phase transformation occurrence conditions will differ from the actual situation. Therefore, in the coupled calculation of the laminar cooling temperature and stress fields of high-strength beam steel, the influence of finishing rolling deformation on the phase transformation needs to be considered. Based on this, this embodiment provides a coupled calculation method for the laminar cooling temperature and stress fields of strip steel considering the deformation effect based on the ANSYS-APDL language. In this embodiment, the strip steel specifically refers to high-strength beam steel.

[0072] This method can be implemented by an electronic device, and its execution flow is as follows: Figure 1 As shown, it includes the following steps:

[0073] S1, Determine the phase transition model that takes into account the effects of deformation;

[0074] Specifically, in this embodiment, the implementation process of S1 is as follows:

[0075] S11, the isothermal transformation curve (TTT curve) of the supercooled austenite in the strip steel was obtained through phase transformation experiments. Specifically, using thermodynamic software (Jmatpro software) and a Gleeble thermal simulation testing machine, the TTT curve and dynamic CCT curve of the high-strength beam steel were obtained through phase transformation experiments. The TTT curve of the high-strength beam steel is shown below. Figure 2 As shown, the dynamic CCT curve of high-strength beam steel is as follows: Figure 3 As shown.

[0076] S12, the curve is processed, and based on the isothermal transformation curve of supercooled austenite, the incubation period for the transformation of austenite to ferrite, pearlite, and bainite, considering the influence of deformation, is obtained; wherein...

[0077] Isothermal Transformation Incubation Period of Austenite to Ferrite The calculation formula is:

[0078]

[0079] In the formula, F1, F2, and F3 are formula coefficients, and T is the strip temperature;

[0080] Incubation period τ of austenite-ferrite transformation considering deformation effects F The calculation formula is:

[0081]

[0082] In the formula, f is the incubation period for the isothermal transformation from austenite to ferrite obtained from the isothermal transformation curve of supercooled austenite. F (ε,T f Let be the deformation influence function, where ε is the finishing rolling strain, and T is the deformation influence function. f This refers to the finishing rolling deformation temperature.

[0083] Incubation period of isothermal transformation from austenite to pearlite Calculation formula:

[0084]

[0085] In the formula, P1, P2, and P3 are formula coefficients, and T is the strip temperature;

[0086] The incubation period τ of austenite to pearlite transformation considering deformation effects P The calculation formula is:

[0087]

[0088] In the formula, To determine the incubation period for the isothermal transformation from austenite to pearlite, based on the isothermal transformation curve of supercooled austenite, f P (ε,T f Let be the deformation influence function, where ε is the finishing rolling strain, and T is the deformation influence function. f This refers to the finishing rolling deformation temperature.

[0089] Isothermal transformation period from austenite to bainite Calculation formula:

[0090]

[0091] In the formula, B1, B2, and B3 are formula coefficients, and T is the strip temperature;

[0092] Incubation period τ for austenite to bainite transformation considering deformation effects B The calculation formula is:

[0093]

[0094] In the formula, f is the incubation period for the isothermal transformation of austenite to bainite obtained from the isothermal transformation curve of supercooled austenite. B (ε,T f Let be the deformation influence function, where ε is the finishing rolling strain, and T is the deformation influence function. f This refers to the finishing rolling deformation temperature.

[0095] Based on the isothermal transformation curve of supercooled austenite, the values ​​of b and n in the kinetic equation (Avrami equation) of austenite phase transformation are calculated using equations (7) and (8);

[0096]

[0097]

[0098] In the formula, t s t e V represents the start and end times of the phase transformation at a specific temperature T in the isothermal transformation curve of supercooled austenite. s V e These are the phase transition variables at the corresponding time points.

[0099] S2, a three-dimensional geometric model of strip steel for laminar cooling process is established based on ANSYS-APDL language;

[0100] Specifically, in this embodiment, the implementation process of S2 is as follows:

[0101] S21, use APDL language to define and assign values ​​to the strip dimensions of length, width and height; wherein, in this embodiment, the strip length L = 2000mm, width B = 1300mm and thickness H = 8mm.

[0102] S22. Use the BLOCK command in the APDL language to create a three-dimensional geometric model of the strip.

[0103] It should be noted that in establishing the three-dimensional geometric model of the strip during the cooling process, this embodiment establishes a quarter model based on the geometric symmetry of the strip.

[0104] S3, based on the ANSYS-APDL language, determines material parameters and element types, and performs mesh generation on the model;

[0105] Specifically, in this embodiment, the implementation process of S3 is as follows:

[0106] S31, using the MP command in the APDL language, defines the material of the strip steel, uses MPTEMP to define the temperature table, the temperature range is from 30℃ to 1050℃, and uses MPDATA to define the thermal conductivity K, specific heat C, elastic modulus EX, Poisson's ratio PRXY and coefficient of thermal expansion ALPX at different temperatures.

[0107] S32 uses the ET command in the APDL language to define the cell type as SOLID5;

[0108] S33, using the LESIZE command in the APDL language, define the mesh size for each edge of the strip, and then use the VMESH command to mesh the three-dimensional geometric model of the strip; wherein, the mesh size in this embodiment is: 60 cells in the length direction, 26 cells in the width direction, and 4 cells in the thickness direction.

[0109] S4. Based on the ANSYS-APDL language, the simulation parameters are defined. The temperature field and stress field coupling solution is calculated using the three-dimensional geometric model of the strip with completed mesh generation. Combined with the phase transformation model that considers the influence of deformation, it is determined whether a phase transformation has occurred. If a phase transformation has occurred, the phase transformation conversion rate and latent heat of phase transformation at the current node are calculated.

[0110] Specifically, in this embodiment, the implementation process of S4 is as follows:

[0111] S41, based on the ANSYS-APDL language, defines laminar cooling process parameters and finishing rolling deformation parameters, and determines the initial temperature field, convection boundary conditions, and structural boundary conditions of the strip, including:

[0112] S411 uses the APDL language to define and assign values ​​to laminar flow cooling process parameters; among them, laminar flow cooling process parameters include laminar flow cooling water cooling section length, number of water cooling sections, air cooling section length, water temperature, strip speed v, etc.

[0113] Specifically, in this embodiment, the length of the laminar flow cooling water section is 5700mm, the number of water sections is 15, the length of the air cooling section is 28000mm, the water temperature is 40℃, and the strip speed is v = 5.6m / s.

[0114] S412, use APDL language to define and assign values ​​to the finishing mill deformation parameters; wherein, the finishing mill deformation parameters include the temperature of the final finishing mill pass and the amount of deformation, etc.

[0115] Specifically, in this embodiment, the temperature of the final pass of finishing rolling is 910°C, and the deformation is 0.15.

[0116] S413 uses the APDL language NSEL and IC commands to apply an initial temperature field to the strip.

[0117] Specifically, in this embodiment, the initial temperature field of the strip is 830-890℃.

[0118] S414, using the APDL language SFA command to apply the convective heat transfer coefficient h and ambient temperature Tw to the strip;

[0119] Specifically, in this embodiment, h is 50-3000W / (m²). 2 ·℃), Tw is 40℃.

[0120] S415, using the APDL language DA command to apply symmetric displacement constraints to the strip symmetry plane of the structure.

[0121] S42, based on the ANSYS-APDL language, determine the total solution time T, the time step dt, and other output options, and after saving the model, start the coupled temperature and stress field solution calculation for each time step; wherein, the other output options include the result output frequency and file format;

[0122] In this embodiment, the APDL language TIME command is used, setting the total solution time T to 7.8s and the time step dt to 0.01s. The APDL language *DO and *ENDDO commands are used to perform a temperature-stress field coupling solution every 0.01s. After each solution, the phase transition calculation macro file in S43 is called once.

[0123] S43 calls the macro file for phase transformation calculation considering deformation effects, written in ANSYS-APDL language, to perform phase transformation calculations, obtain the temperature value of each node at that moment, and input it into the phase transformation model considering deformation effects to determine whether ferrite, pearlite, or bainite phase transformation has occurred. If a phase transformation has occurred, the phase transformation conversion rate and latent heat of phase transformation at that node are calculated, and the latent heat of phase transformation is loaded into the thermal boundary conditions of the next time step in the form of heat generation rate. Then, the temperature field and stress field coupling of the next time step is performed until the phase transformation is completed.

[0124] Specifically, in this embodiment, the implementation process of S43 is as follows:

[0125] Using the APDL language *DO and *ENDDO commands, perform the following computation steps for each node:

[0126] S431, calculate the incubation period of each node at the current temperature according to equations (2), (4), and (6);

[0127] S432, use formula (9) to accumulate the ratio of time step and phase transformation incubation period, and determine whether ferrite, pearlite or bainite has reached the phase transformation start point at the current node temperature and at the current time.

[0128]

[0129] In the formula, dt is the time step, and τ(T) is the isothermal transformation incubation period at the corresponding temperature, which is obtained from the phase transformation experiment of the material. When the sum of the ratios of the two is 1, the austenite undergoes a transformation (a phase transformation of ferrite, pearlite or bainite).

[0130] S433, if a phase transformation occurs, the phase transformation variables of ferrite, pearlite, and bainite are calculated using the following formula:

[0131] X = 1 - exp(-bt) n (10)

[0132] In the formula, X is the transformation variable, t is the time after the phase transformation begins, and b and n are the values ​​of b and n in the kinetic equation of the austenitic phase transformation, which are obtained through phase transformation experiments.

[0133] S434, calculate the latent heat of phase transformation q of ferrite, pearlite, or bainite at the current node according to the following formula:

[0134]

[0135] In the formula, ρ is the material density, H(T) is the enthalpy of austenite transformation, and ΔX is the amount of austenite transformed per unit time Δt.

[0136] In S435, using the APDL language BF command, the latent heat of phase change of this node is loaded into the next boundary condition in the form of heat generation rate. Repeat S42 to perform the next temperature field stress field coupling solution calculation.

[0137] S5 processes the simulation results using ANSYS APDL language to obtain temperature-time curves and stress-time curves of the strip laminar cooling process, as well as the ferrite, pearlite, or bainite transformation variables.

[0138] Among them, the temperature stress-time curve is as follows: Figure 4 As shown.

[0139] The curve of temperature difference-phase change over time is shown below. Figure 5 As shown.

[0140] In summary, this embodiment provides a method for coupled calculation of temperature and stress fields in laminar cooling of strip steel, considering the influence of deformation. It can predict the temperature and stress values ​​at different nodes of high-strength beam steel strip during laminar cooling, as well as predict the phase changes of ferrite, pearlite, and bainite. By using the parametric design language APDL of ANSYS finite element software and inputting laminar cooling process parameters, including the length of the water-cooled section, the number of water-cooled sections, the length of the air-cooled section, water temperature, and strip speed, a three-dimensional temperature and stress field model can be established to calculate the temperature and stress fields of the high-strength beam steel and predict the phase changes. Compared with traditional coupled calculations of temperature and stress fields in laminar cooling, this method considers the influence of finishing rolling deformation on phase transformation, which is more consistent with reality. Compared with operations using the finite element interface, the macro commands established using APDL language in this method can repeatedly model the same type of problem by changing parameters, making it more time-saving and efficient.

[0141] Second Embodiment

[0142] This embodiment provides an electronic device, which includes a processor and a memory; wherein the memory stores at least one instruction, which is loaded and executed by the processor to implement the method of the first embodiment.

[0143] The electronic device can vary considerably depending on its configuration or performance, and may include one or more processors (central processing units, CPUs) and one or more memories, wherein the memories store at least one instruction that is loaded by the processor and executed in accordance with the above method.

[0144] Third Embodiment

[0145] This embodiment provides a computer-readable storage medium storing at least one instruction, which is loaded and executed by a processor to implement the method of the first embodiment described above. The computer-readable storage medium may be a ROM, random access memory, CD-ROM, magnetic tape, floppy disk, or optical data storage device, etc. The instruction stored therein can be loaded and executed by a processor in a terminal.

[0146] Furthermore, it should be noted that the present invention can be provided as a method, apparatus, or computer program product. Therefore, embodiments of the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, embodiments of the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code.

[0147] Embodiments of the present invention are described with reference to flowchart illustrations and / or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0148] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing terminal device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing terminal equipment to cause a series of operational steps to be performed on the computer or other programmable terminal equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable terminal equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0149] It should also be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0150] Finally, it should be noted that the above description represents a preferred embodiment of the present invention. It should be pointed out that although preferred embodiments have been described, those skilled in the art, once they understand the basic inventive concept of the present invention, can make various improvements and modifications without departing from the principles described herein. These improvements and modifications should also be considered within the scope of protection of the present invention. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the embodiments of the present invention.

Claims

1. A strip steel laminar cooling temperature field stress field coupling calculation method, characterized in that, The application relates to a method for simulating a strip steel laminar cooling process. The method comprises the following steps: determining a phase change model considering deformation influence; establishing a three-dimensional geometric model of strip steel in a laminar cooling process based on ANSYS-APDL language; determining material parameters and element types based on ANSYS-APDL language, and carrying out mesh division on the model; defining simulation parameters based on ANSYS-APDL language, carrying out temperature field and stress field coupling calculation on the three-dimensional geometric model of the strip steel after mesh division, and judging whether phase change occurs or not by combining the phase change model considering deformation influence; if phase change occurs, calculating the current node phase change conversion rate and phase change latent heat; processing the simulation calculation results based on ANSYS APDL language to obtain the temperature-time curve and stress-time curve of the strip steel in the laminar cooling process, and the ferrite, pearlite or bainite transformation amount; the phase change model considering deformation influence comprises the following steps: obtaining the supercooled austenite isothermal transformation curve of the strip steel through phase change experiment; The incubation period τ of austenite to ferrite transformation considering the effect of deformation F The calculation formula is: In the formula, is the incubation period of austenite to ferrite isothermal transformation obtained from the supercooled austenite isothermal transformation curve, f F (ε, T f ) is a deformation influence function, wherein ε is the finish rolling strain, T f is the finish rolling deformation temperature; Inception period τ of austenite to pearlite transformation considering the effect of deformation P The calculation formula is: In the formula, is the incubation period of austenite to pearlite isothermal transformation obtained from the supercooled austenite isothermal transformation curve, f P (ε, T f ) is a deformation influence function, where ε is the finish rolling strain, T f is the finish rolling deformation temperature; Incubation period τ of austenite to bainite transformation considering the effect of deformation B The calculation formula is: In the formula, is the incubation period of austenite to bainite isothermal transformation obtained from the supercooled austenite isothermal transformation curve, f B (ε, T f ) is a deformation influence function, wherein ε is the finish rolling strain, T f is the finish rolling deformation temperature; obtaining the incubation period of austenite to ferrite, pearlite and bainite transformation considering deformation influence according to the supercooled austenite isothermal transformation curve; wherein, In the formula, t s , t e are the phase transformation start time and phase transformation end time corresponding to a certain temperature T in the supercooled austenite isothermal transformation curve, V s , V e are the phase transformation quantities corresponding to the time.

2. The strip steel laminar cooling temperature field-stress field coupling calculation method of claim 1, wherein, calculating the b value and n value in the kinetics equation of austenite phase change according to the supercooled austenite isothermal transformation curve by using the following formula; the three-dimensional geometric model of the strip steel in the laminar cooling process based on ANSYS-APDL language comprises the following steps: defining and assigning the length, width and height of the strip steel by using APDL language; 3. The strip steel laminar cooling temperature field-stress field coupling calculation method of claim 1, wherein, creating the three-dimensional geometric model of the strip steel by using the BLOCK command in the APDL language. the steps of determining material parameters and element types based on ANSYS-APDL language, and carrying out mesh division on the model comprise the following steps: defining the material of the strip steel by using the MP command in the APDL language, defining the temperature table by using MPTEMP, and defining the thermal conductivity K, the specific heat C, the elastic modulus EX, the Poisson's ratio PRXY and the thermal expansion coefficient ALPX at different temperatures by using MPDATA; defining the element type as SOLID5 by using the ET command in the APDL language; 4. The strip steel laminar cooling temperature field-stress field coupling calculation method of claim 1, wherein, defining the mesh size of each edge of the strip steel by using the LESIZE command in the APDL language, and carrying out mesh division on the three-dimensional geometric model of the strip steel by using the VMESH command. the steps of defining simulation parameters based on ANSYS-APDL language, carrying out temperature field and stress field coupling calculation on the three-dimensional geometric model of the strip steel after mesh division, and judging whether phase change occurs or not by combining the phase change model considering deformation influence; if phase change occurs, calculating the current node phase change conversion rate and phase change latent heat, comprise the following steps: defining the laminar cooling process parameters and the finishing deformation parameters based on ANSYS-APDL language, determining the initial temperature field of the strip steel, the convection boundary condition and the structure boundary condition; determining the total calculation time T, each time step dt and other output options based on ANSYS-APDL language, and starting the temperature field and stress field coupling calculation of each time step after saving the model; wherein, the other output options include the result output frequency and the file format. The macro file considering deformation influence written based on ANSYS-APDL language is called to perform phase change calculation, and the temperature value of each node at the current time is obtained, which is brought into the phase change model considering deformation influence to judge whether ferrite phase change, pearlite phase change or bainite phase change occurs, and if phase change occurs, the phase change conversion rate and phase change latent heat of the current node are calculated, and the phase change latent heat is loaded to the thermal boundary condition of the next time step in the form of heat generation rate, and then the next time step temperature field and stress field coupling is performed until the phase change is completed.

5. The strip steel laminar cooling temperature field-stress field coupling calculation method of claim 1, wherein, The laminar cooling process parameters and finishing deformation parameters are defined and valued by using the APDL language; wherein the laminar cooling process parameters include the laminar cooling water cooling section length, the water cooling section quantity, the air cooling section length, the water temperature and the strip speed; The laminar cooling process parameters are defined and valued by using the APDL language; wherein the laminar cooling process parameters include the laminar cooling water cooling section length, the water cooling section quantity, the air cooling section length, the water temperature and the strip speed; The finishing deformation parameters are defined and valued by using the APDL language; wherein the finishing deformation parameters include the finishing last pass temperature and deformation amount; The initial temperature field of the strip is applied by using the APDL language NSEL command and IC command; The convective heat transfer coefficient h and the environment temperature Tw of the strip are applied by using the APDL language SFA command; The symmetric displacement constraint of the structure of the symmetric surface of the strip is applied by using the APDL language DA command.

6. The strip steel laminar cooling temperature field-stress field coupling calculation method of claim 1, wherein, The macro file considering deformation influence written based on ANSYS-APDL language is called to perform phase change calculation, and the temperature value of each node at the current time is obtained, which is brought into the phase change model considering deformation influence to judge whether ferrite phase change, pearlite phase change or bainite phase change occurs, and if phase change occurs, the phase change conversion rate and phase change latent heat of the current node are calculated, and the phase change latent heat is loaded to the thermal boundary condition of the next time step in the form of heat generation rate, and then the next time step temperature field and stress field coupling is performed until the phase change is completed, including: The following calculation steps are performed for each node by using the APDL language *DO and *ENDDO commands: The incubation period of each node at the current temperature is calculated based on the phase change model considering deformation influence; The ratio of the time step and the phase change incubation period is accumulated by using the following formula to judge whether the ferrite, pearlite or bainite reaches the phase change starting point at the current temperature and time; If phase change occurs, the phase conversion amount of ferrite, pearlite and bainite is calculated by using the following formula: The phase change latent heat q of the current node ferrite, pearlite or bainite is calculated according to the following formula: X = 1 - exp(-bt n ) The phase change latent heat q of the current node ferrite, pearlite or bainite is calculated according to the following formula: The phase change latent heat q of the current node ferrite, pearlite or bainite is calculated according to the following formula: The phase change latent heat q of the current node ferrite, pearlite or bainite is calculated according to the following formula: The phase change latent heat q of the current node ferrite, pearlite or bainite is calculated according to the following formula: The latent heat of phase transition of the current node is loaded on the boundary condition of next step in the form of heat generation rate by using APDL language BF command, and then the next step of temperature field and stress field coupling solution calculation is carried out.

7. The strip laminar cooling temperature field and stress field coupled calculation method according to any one of claims 1 to 6, characterized in that, The strip steel three-dimensional geometric model of the established laminar cooling process includes: According to the symmetry of the strip steel geometric shape and the boundary condition, a quarter model is established.

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