Laser cladding temperature field analysis method based on finite element simulation method

Abstract

The invention discloses a laser cladding temperature field analysis method based on a finite element simulation method. A metal flat plate is used as a research object. ANSYS software is adopted for simulation. A laser cladding process is simulated by constructing a finite element model and a refined mesh in combination with a moving Gaussian heat source and birth-death unit technology, and simulated laser heating is applied to the surface of a part as a thermal load. The ANSYS processing unit calculates a simulation result, and the postprocessor displays temperature field distribution. Simulated and actual coating cross section molten pool shapes are compared, it is found that the size of a simulation model is highly consistent with the size of an actual molten pool, the maximum error is only 9%, and the reliability of numerical simulation is verified. According to the method, a solid theoretical basis and an effective simulation means are provided for the metal laser cladding process, the process research level is improved, and the development cost is reduced. The method has an important value for practical engineering application, and provides a scientific basis for optimizing the laser cladding technology.

Description

Technical Field

[0001] The invention belongs to the technical field of laser cladding simulation, and relates to a laser cladding temperature field analysis method based on a finite element simulation method. Background Art

[0002] During the laser cladding process, a short-lived high-temperature molten pool will be generated. Exploring the temperature field of the molten pool is of great reference significance for laser cladding processing. However, due to the rapid formation and disappearance of the molten pool and the high center temperature, the processing involves multiple disciplines such as thermodynamics and fluid mechanics, as well as the influence of environmental factors such as air convection, it is difficult to accurately and efficiently explore the surface temperature, especially the internal temperature.

[0003] Numerical simulation technology establishes an experimental model according to the actual situation of the research, adds external conditions such as magnetic field, force field, thermal field, fluid field, etc. to the model, and then solves, statistics and analyzes the simulation data with the help of electronic computers. In the study of temperature field problems such as laser cladding parts, numerical simulation can effectively solve the problems of traditional experimental measurement and obtain experimental results intuitively and accurately. In the computer numerical simulation process of laser cladding processing, the basic methods used include finite difference method (FDM), finite element method (FEM), direct difference method (DFDM) and boundary element method (BEM). Finite difference method is a numerical method that discretizes continuous physical fields into grid points, approximates the derivative terms of differential equations with difference formulas, and solves the distribution of physical fields. In laser cladding processing, it can be used to simulate the temperature and flow of the molten pool, but when dealing with complex shapes and boundary conditions, the meshing and differential formula design need to be careful, which increases the difficulty; the direct difference method is simpler, and the differential equations are directly established on the grid points and solved iteratively. However, it also has limitations when dealing with complex shapes and boundary conditions, and assumptions and simplifications are required; the boundary element method is based on the boundary integral equation, which converts the boundary conditions into integral equations and uses boundary discrete points to solve them. The calculation amount is small, but it is difficult to deal with internal physical fields, and complex boundary integral equations and solution techniques need to be established. In laser cladding, the boundary element method is often used to simulate the heat exchange and flow between the molten pool and the environment.

[0004] The finite element method is a more advanced and flexible numerical method. It divides the continuum into a series of small units (such as triangles, quadrilaterals, etc.) based on the variational principle and the idea of ​​discrete processing, and establishes a local coordinate system and interpolation function in each unit. By solving the local equations of each unit and combining them into a global set of equations, the physical field distribution of the entire continuum can be obtained. The finite element method has great flexibility and adaptability and can handle various complex shapes and boundary conditions. In laser cladding processing, the finite element method is widely used to simulate the temperature field, stress field and fluid field of the molten pool. Since this method can accurately discretize the continuum, more accurate and reliable simulation results can be obtained. However, the existing finite element simulation method has low accuracy when dealing with systems with faster cladding speeds. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a laser cladding temperature field analysis method based on the finite element simulation method, thereby solving the technical problem of low accuracy of the finite element simulation method in the prior art when processing a system with a faster cladding speed.

[0006] The present invention is achieved through the following technical solutions: A laser cladding temperature field analysis method based on finite element simulation method comprises the following steps: S1: Obtain the thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate and the cladding coating material, and obtain the process parameters in the metal cladding production process; S2: Import the obtained thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate material and the cladding coating material as well as the process parameters in the metal cladding production process into the ANSYS software, establish a simulation model of the metal cladding simulation process, and determine the simulation parameters; S3: Utilizing the obtained thermophysical property parameters, geometric dimension parameters and process parameters of the substrate and cladding layer materials in the metal cladding production process, and calculating the temperature field of the laser cladding process of the substrate according to the simulation model, the analysis process of the laser cladding temperature field is completed; in the calculation process, a Gaussian surface heat source distribution function is selected for simulation, and a moving heat source and a unit birth and death method are used to simulate the gradual cladding and accumulation process of the cladding layer material.

[0007] Preferably, the thermophysical property parameters include thermal conductivity, specific heat capacity, thermal expansion coefficient and elastic modulus.

[0008] Preferably, the geometrical dimension parameters of the substrate include the length, width and thickness of the substrate; the geometrical dimension parameters of the cladding coating material include the width, thickness and position of the cladding layer relative to the substrate.

[0009] Preferably, the process parameters in the metal cladding production process include laser power, cladding speed, cladding depth, cladding width and heat affected zone depth.

[0010] Preferably, in step S2, the obtained thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate material and the cladding coating material and the process parameters in the metal cladding production process are imported into ANSYS software, a simulation model of the metal cladding simulation process is established, and the simulation parameters are determined, specifically: finite element meshing is performed on the components of the established simulation model, and material properties are assigned to the components.

[0011] Preferably, the grid density at the coating position is greater than the grid density at the coating position away from the coating.

[0012] Preferably, the grid size of the coating position is 0.25 mm.

[0013] Preferably, in step S3, the temperature field of the laser cladding process of the substrate is calculated according to the simulation model to complete the analysis process of the laser cladding temperature field, and the analysis process generates a temperature distribution cloud map or a curve graph of temperature change over time.

[0014] Preferably, after step S3, the method further includes comparing and verifying the temperature field results obtained by the laser cladding simulation calculation with the experimental molten pool results.

[0015] Preferably, the temperature field results obtained by the laser cladding simulation calculation are compared and verified with the experimental molten pool results, specifically: the molten pool morphology of the simulated coating cross section is compared with the molten pool morphology of the actual coating cross section, and the parameters in the Gaussian heat source model are corrected so that the error between the simulation results and the experimental results is less than 4%.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a laser cladding temperature field analysis method based on finite element simulation method. The method utilizes ANSYS finite element simulation software to establish an accurate simulation model, and imports thermophysical property parameters and geometric dimension parameters of a metal cladding process substrate and a cladding coating material, as well as process parameters in a metal cladding production process, which ensures the high accuracy of the simulation process, especially when dealing with rapid changes in the temperature field caused by an excessively fast cladding rate, it is possible to capture subtle temperature fluctuations and distribution characteristics; in addition, a Gaussian surface heat source distribution function is used for simulation, and combined with a moving heat source and a unit birth and death method, the method can efficiently simulate the process of gradual cladding and accumulation of cladding layer materials, which not only improves the calculation speed, but also makes the simulation results closer to the actual cladding process, especially at a high cladding rate, it is possible to accurately reflect the dynamic changes of the temperature field; in the laser cladding process, the shape and position of the molten pool may change significantly over time, especially at a high cladding rate, the method can adjust the grid division and simulation parameters as needed to adapt to these changes, thereby ensuring the accuracy of the simulation results. Through this method, the temperature field in the laser cladding process can be predicted and analyzed, and then the cladding process parameters can be optimized. For example, the laser power, scanning speed, spot radius and other parameters can be adjusted to improve the distribution and uniformity of the temperature field, thereby improving the quality and performance of the cladding layer. In summary, the laser cladding temperature field analysis method based on the finite element simulation method has the advantages of high-precision simulation and efficient calculation in the analysis of the laser cladding temperature field with too fast cladding rate. This method uses the simulation model obtained by correct and effective means, and uses the simulation model to obtain the transient temperature field results of the cladding area and the surrounding area, so as to guide the implementation process of the axle metal cladding process and shorten the time required for process experiments to obtain the optimal process parameters.

[0017] Furthermore, the thermophysical property parameters include thermal conductivity, specific heat, thermal expansion coefficient and elastic modulus. By accurately setting the thermal conductivity, a more realistic temperature field change can be simulated, thereby improving the accuracy of the simulation. In laser cladding, the specific heat determines the degree of temperature rise after the material absorbs laser energy. Accurately setting the specific heat helps to more accurately predict the temperature change during the cladding process; by accurately setting the thermal expansion coefficient, the deformation of the cladding layer can be simulated, providing guidance for optimizing the process parameters; by accurately setting the elastic modulus, the deformation of the cladding layer can be more accurately predicted, thereby optimizing the process parameters to reduce deformation; by simultaneously setting multiple thermophysical property parameters such as thermal conductivity, specific heat, thermal expansion coefficient and elastic modulus, the thermal behavior of the material during the laser cladding process can be more comprehensively reflected, which helps to enhance the practicality of the simulation model and make it closer to the actual cladding process.

[0018] Furthermore, the geometrical dimension parameters of the substrate include the length, width and thickness of the substrate; the geometrical dimension parameters of the cladding coating material include the width, thickness and position of the cladding layer relative to the substrate. By accurately setting the geometrical dimension parameters of the substrate and the cladding coating material, their shapes and sizes can be accurately described, thereby ensuring a high degree of consistency between the simulation model and the actual situation, which helps to improve the accuracy of the simulation results and make the simulation results more reflective of the temperature field changes in the actual laser cladding process. Accurate setting of geometric dimension parameters is helpful for reasonable meshing in the simulation model. The density of the mesh directly affects the accuracy and efficiency of the simulation calculation. By meshing according to the geometric dimensions of the substrate and the cladding layer, it is possible to ensure that a finer mesh is obtained in key areas (such as near the molten pool), thereby improving the simulation accuracy. Through the simulation model, the formation effect of the cladding layer under different geometric dimension parameters can be predicted, including the width, thickness and position of the cladding layer relative to the substrate, which is helpful for preliminary screening and optimization of process parameters before actual production to reduce trial and error costs. Accurate setting of geometric dimension parameters helps to reduce the amount of calculation in the simulation process, thereby improving the simulation efficiency. Through reasonable meshing and parameter setting, the simulation time can be shortened and the calculation cost can be reduced while ensuring the simulation accuracy.

[0019] Furthermore, the process parameters in the metal cladding production process include laser power, cladding speed, melt depth, melt width and heat-affected zone depth. Laser power is a key factor affecting the quality of the cladding layer and the temperature field distribution. By setting the laser power parameter, the heating effect of the laser beam on the substrate and the cladding material can be accurately simulated, so as to more accurately predict the formation of the molten pool, the evolution of the temperature field and the microstructure of the cladding layer. The cladding speed determines the accumulation rate of the cladding material on the substrate. By reasonably setting the cladding speed parameter, the formation process of the cladding layer under different accumulation rates can be simulated, and then its influence on the temperature field, the molten pool morphology and the quality of the cladding layer can be evaluated; the melt depth and melt width are important parameters reflecting the geometric characteristics of the cladding layer. Through simulation calculation, the specific values ​​of the melt depth and melt width under different process parameters can be obtained, so as to more intuitively understand the formation effect and geometric morphology of the cladding layer; the heat-affected zone is the area where the substrate is affected by heat during the laser cladding process and the organization and performance change. By setting the heat-affected zone depth parameter, the influence of laser cladding on the substrate can be evaluated, providing a theoretical basis for optimizing process parameters and reducing the heat-affected zone; through simulation, the influence of different process parameter combinations on the quality of the cladding layer, temperature field distribution and heat-affected zone depth can be analyzed. According to the simulation results, the process parameters can be optimized, such as adjusting the laser power, cladding speed, etc., to obtain the best cladding effect. The setting of these parameters not only improves the simulation accuracy and reliability, but also helps to guide process optimization and quality control.

[0020] Further, in step S2, the obtained thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate material and the cladding coating material and the process parameters in the metal cladding production process are imported into the ANSYS software to establish a simulation model of the metal cladding simulation process and determine the simulation parameters, specifically: finite element meshing is performed on the components of the established simulation model, and material properties are assigned to the components at the same time. Finite element meshing is to divide the simulation model into multiple small units for numerical calculation. Through reasonable meshing, it can be ensured that the simulation model has sufficient accuracy in key areas (such as near the molten pool, heat-affected zone, etc.), so as to more accurately simulate the temperature field changes and cladding layer formation process during the laser cladding process. The fineness of the meshing directly affects the accuracy of the simulation results. Finer meshes can provide more calculation nodes, thereby more accurately describing the distribution of temperature fields and stress fields.

[0021] Furthermore, the mesh density at the cladding position is greater than the density of the mesh at the position far from the cladding. The cladding position is a key area in the laser cladding process, and the changes in its physical fields such as temperature field and stress field are relatively complex. By increasing the mesh density in this area, more detailed changes, such as temperature gradient and stress concentration, can be captured, thereby improving the accuracy of the simulation. At a position far from the cladding, the temperature change is relatively small, and the change of the physical field is also relatively gentle. Therefore, these areas can be divided with a coarser mesh to reduce the amount of calculation. However, at the cladding position, due to the drastic temperature change, if a coarser mesh is used, the calculation error may increase. By increasing the mesh density, this error can be reduced and the accuracy of the simulation can be improved. In the simulation process, the amount of calculation is proportional to the mesh density. If the entire model is divided with a very fine mesh, the amount of calculation will increase sharply, thereby extending the calculation time. By adopting an uneven mesh division method, that is, using a fine mesh at the cladding position and a coarse mesh at a position far from the cladding, the calculation efficiency can be optimized and the calculation time can be shortened while ensuring accuracy. In the case of limited computing resources, reasonable mesh division can make full use of computing resources and avoid waste. Dedicating more computing resources to critical areas, such as cladding locations, ensures that simulation results in these areas are more accurate and reliable.

[0022] Furthermore, the mesh size of the cladding position is 0.25 mm. In the laser cladding process, the mesh refinement of the cladding position to 0.25 mm can significantly improve the accuracy of simulation and processing. This fine mesh division helps to optimize the laser cladding parameters, such as laser power and scanning rate, to achieve better cladding effect and coating performance. Finer meshes can capture more temperature gradient details, making the simulation results closer to the actual situation. Based on the accurate simulation results, the process parameters of laser cladding can be adjusted to obtain the best cladding effect and coating performance. Through fine mesh division and simulation optimization, errors and material waste caused by improper process parameters can be reduced.

[0023] Further, in step S3, the temperature field of the laser cladding process of the substrate is calculated according to the simulation model, and the analysis process of the laser cladding temperature field is completed. The analysis process generates a temperature distribution cloud map or a temperature change curve over time. Through the temperature distribution cloud map, the temperature distribution at different positions during the laser cladding process can be intuitively seen. This graphical display method makes the change of the temperature field easier to understand and analyze. The temperature change curve over time shows how the temperature of a specific position or area changes over time. This helps to understand the heating and cooling rates during the laser cladding process, as well as the amplitude and frequency of temperature fluctuations. By comparing the temperature field distribution and temperature change curves under different process parameters, the influence of these parameters on the laser cladding process can be accurately analyzed. This helps to optimize the process parameters and improve the quality and performance of the cladding layer. By analyzing the changes in the temperature field, potential problems that may occur, such as thermal cracks, deformation, etc., can also be predicted. This helps to take corresponding preventive measures in the actual production process and reduce production risks.

[0024] Further, after step S3, it also includes comparing and verifying the temperature field results obtained by the laser cladding simulation calculation with the experimental molten pool results. By comparing the simulation results with the experimental results, the accuracy of the simulation model in simulating the temperature field of the laser cladding process can be verified. This helps to improve the credibility of the simulation model so that it can be more reliably used for subsequent analysis and optimization work. During the comparison and verification process, if it is found that there is a significant difference between the simulation results and the experimental results, the reasons can be further analyzed to find potential problems or deficiencies in the simulation model. This helps to correct and improve the simulation model and improve its accuracy and applicability. By comparing the temperature field results of the simulation and the experiment, the influence of different process parameters on the laser cladding process can be more accurately understood. This helps to guide the adjustment and optimization of the process parameters to obtain better cladding effect and coating performance. Traditional process parameter optimization often requires a lot of experiments to explore and adjust. By combining simulation and experiment, the trial and error cost can be reduced to a certain extent and the optimization efficiency can be improved.

[0025] Furthermore, the temperature field results obtained by the laser cladding simulation calculation are compared and verified with the experimental molten pool results. Specifically, the simulated coating cross-sectional molten pool morphology is compared with the actual coating cross-sectional molten pool morphology, and the parameters in the Gaussian heat source model are corrected so that the error between the simulation results and the experimental results is less than 4%. By comparing the simulated coating cross-sectional molten pool morphology with the actual coating cross-sectional molten pool morphology, the accuracy of the simulation model in simulating the molten pool morphology during laser cladding can be intuitively evaluated. This helps to discover deficiencies in the simulation model and make corrections accordingly, thereby improving the accuracy of the simulation model. The Gaussian heat source model is one of the commonly used heat source models in laser cladding simulation. By comparing and verifying, and adjusting the parameters in the Gaussian heat source model (such as peak heat flux intensity, heat flux concentration coefficient, etc.) according to the actual molten pool morphology, the simulation results can be made closer to the experimental results, thereby improving the prediction ability of the simulation model. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a flow chart of the simulation analysis method of the metal cladding temperature field; Figure 2 This is the geometric model diagram of laser cladding temperature field simulation (overall); Figure 3 It is the geometric model diagram of laser cladding temperature field simulation (cladding layer); Figure 4 It is a schematic diagram of Gaussian surface heat source distribution model; Figure 5 This is a schematic diagram of mesh division for the laser cladding finite element model; Figure 6 It is the transient temperature field cloud diagram at a certain moment (in the direction of the molten pool profile); Figure 7 It is a transient temperature field cloud diagram at a certain moment (laser cladding movement direction). DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0030] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0031] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0032] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings: Example 1 like Figure 1 As shown, the present invention discloses a laser cladding temperature field analysis method based on finite element simulation method, comprising the following steps: S1: Obtain the thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate and the cladding coating material, and obtain the process parameters in the metal cladding production process; The thermophysical property parameters include thermal conductivity, specific heat capacity, thermal expansion coefficient and elastic modulus.

[0035] The geometrical dimension parameters of the substrate include the length, width and thickness of the substrate; the geometrical dimension parameters of the cladding coating material include the width, thickness and position of the cladding layer relative to the substrate.

[0036] The process parameters in the metal cladding production process include laser power, cladding speed, cladding depth, cladding width and heat affected zone depth.

[0037] S2: Import the obtained thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate material and the cladding coating material as well as the process parameters in the metal cladding production process into the ANSYS software, establish a simulation model of the metal cladding simulation process, and determine the simulation parameters; The obtained thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate material and the cladding coating material as well as the process parameters in the metal cladding production process are imported into the ANSYS software to establish a simulation model of the metal cladding simulation process and determine the simulation parameters, specifically: finite element meshing is performed on the components of the established simulation model, and material properties are assigned to the components.

[0038] In a preferred solution, the grid density at the coating position is greater than the grid density at the position far from the coating position.

[0039] Further more preferably, the grid size of the coating position is 0.25 mm.

[0040] S3: Utilizing the obtained thermophysical property parameters, geometric dimension parameters and process parameters of the substrate and cladding layer materials in the metal cladding production process, and calculating the temperature field of the laser cladding process of the substrate according to the simulation model, the analysis process of the laser cladding temperature field is completed; in the calculation process, a Gaussian surface heat source distribution function is selected for simulation, and a moving heat source and a unit birth and death method are used to simulate the gradual cladding and accumulation process of the cladding layer material.

[0041] The temperature field of the laser cladding process of the substrate is calculated according to the simulation model to complete the analysis process of the laser cladding temperature field, and the analysis process generates a temperature distribution cloud map or a curve diagram of temperature change over time.

[0042] In addition, after step S3, the temperature field result obtained by the laser cladding simulation calculation is compared and verified with the experimental molten pool result.

[0043] Preferably, the temperature field results obtained by the laser cladding simulation calculation are compared and verified with the experimental molten pool results, specifically: the molten pool morphology of the simulated coating cross section is compared with the molten pool morphology of the actual coating cross section, and the parameters in the Gaussian heat source model are corrected so that the error between the simulation results and the experimental results is less than 4%.

[0044] The present invention mainly takes a metal flat plate as the object, uses ANSYS finite element software as the analysis method, establishes a finite element model and a refined grid of the metal flat plate through ANSYS, simulates the laser cladding process through the moving Gaussian surface heat source and the birth-death unit technology, and adds the simulated laser heating to the surface of the part entity in the form of a heat load. The simulation situation is calculated by the ANSYS processing unit and the temperature field result is displayed by the post-processor. The morphology of the simulated coating cross-section molten pool is compared with the morphology of the actual coating cross-section molten pool, and the parameters in the Gaussian heat source model are corrected to make the simulation results and the test results match well.

[0045] Example 2 In order to further explain the scheme of the present invention, it is described by the following examples: A laser cladding temperature field analysis method based on finite element simulation method comprises the following steps: Step 1: Obtain parameter data.

[0046] The substrate material of the metal cladding process is EA4T, and its thermophysical property parameters and geometric size parameters are obtained. The cladding coating powder of the metal cladding process is Inconel625 alloy, and its thermophysical property parameters and geometric size parameters are obtained. The process parameters in the metal cladding production process are obtained. The above parameters are used to determine the geometric model, heat source model, etc. of the metal cladding process, and establish an accurate temperature field calculation finite element model to simulate the metal cladding process.

[0047] Step 2: Simulation model establishment.

[0048] According to the parameters obtained in step 1, a simulation model of the metal cladding process of the metal plate is established using ANSYS; at the same time, the thermophysical properties parameters of the substrate and cladding layer materials, the contact and ambient temperatures, and the parameters of the moving Gaussian surface heat source are determined.

[0049] Step 3: Model simulation process.

[0050] The cladding simulation model in step 2 is used to simulate the metal cladding process to obtain the transient temperature field changes of the substrate and the cladding layer during the entire cladding process.

[0051] Step 4: Compare and verify the simulation results The temperature field results obtained by laser cladding simulation calculation were compared and verified with the experimental molten pool results, and the heat source model parameters were further corrected to make the simulated molten pool morphology as close as possible to the experimental results under the same process parameters.

[0052] To be more specific, the plate used in the metal cladding simulation analysis process is high-speed train axle steel EA4T. The verification method of the simulation model in the production process is as follows: Figures 2 to 7As shown, it includes the following steps: The overall analysis process is as follows Figure 1 As shown: Step 1: Obtain parameters The substrate material of the metal cladding process is EA4T, and its thermophysical property parameters are obtained, including thermal conductivity, specific heat capacity, thermal expansion coefficient, elastic modulus, etc., and its three geometric size parameters of length, width and height are obtained. Figure 3 As shown; the cladding coating powder of the metal cladding process is Inconel625 alloy, and its thermophysical property parameters are obtained, including thermal conductivity, specific heat capacity, thermal expansion coefficient, elastic modulus, etc., and its height, shape, width geometric parameters are obtained as shown in Figure 4 As shown in the figure, the process parameters of metal cladding production are obtained, including laser power, cladding speed, melting depth, melting width, heat affected zone depth, etc.

[0053] As axle steel, EA4T has good strength, toughness and cladding performance, and is an excellent axle steel material. Inconel625 alloy has excellent corrosion resistance, wear resistance and fatigue performance, which can effectively increase the service life of the axle.

[0054] The ambient temperature of the cladding process was set to room temperature, i.e. 20°C.

[0055] Step 2: Simulation model establishment According to the material property parameters of the substrate and cladding coating obtained in step 1 and the process parameters of the cladding process, the simulation model of the metal cladding simulation process is established using ANSYS software, including the mesh model such as Figure 5 and determine the detailed simulation parameters, including the parameters of the Gaussian moving heat source, such as Figure 6 As shown; Step 3, simulation process Using the material properties and geometrical dimension parameters of the substrate and the cladding layer and the cladding process parameters obtained in step 1, the temperature field of the laser cladding process of the metal plate is calculated according to the simulation model in step 2; Step 4: Compare and verify the simulation results The temperature field results obtained by laser cladding simulation calculation were compared and verified with the experimental molten pool results, and the heat source model parameters were further corrected to make the simulated molten pool morphology as close as possible to the experimental results under the same process parameters.

[0056] Step 2 specifically includes the following steps: Finite element meshing is performed on the established geometric components. When meshing, the components are meshed in reasonable sizes in order to improve the calculation accuracy and appropriately reduce the calculation amount of the simulation model. Assign material properties to the components. During the cladding simulation calculation process, the physical properties of the material, including density, thermal conductivity, elasticity, specific heat capacity, plasticity, and thermal expansion coefficient, also change with the change of temperature. That is, the nonlinear factors of the material are fully considered in the calculation.

[0057] The simulation model generation module includes a grid module and a material property module, wherein: the grid module is used to perform grid processing on the simulation geometric model; the material property module is used to assign material properties.

[0058] In addition, setting boundary conditions includes a load definition module and a boundary condition definition module, wherein: the load definition module is used to define the external load that the finite element model is actually subjected to, including setting the space step and time step, and applying the load; the boundary condition module is used to define the boundary conditions of the finite element model.

[0059] Example 3 In order to further explain the scheme of the present invention, it is described by the following examples: The present invention uses ANSYS finite element software as an analysis method. ANSYS is a powerful engineering simulation software. It is based on the finite element analysis (FEA) method and is widely used in the analysis of complex systems such as structure, heat, fluid, electromagnetic and multi-physical field coupling. The software integrates three modules: pre-processing, solver and post-processing, providing users with a one-stop solution. In the pre-processing stage, users can easily build geometric models, define material properties, divide grids, and apply boundary conditions and loads. ANSYS provides a rich unit library and material models that can accurately simulate the physical and mechanical behaviors of various engineering materials. The solver is the core of the ANSYS software, which uses advanced numerical algorithms, such as direct methods, iterative methods, etc., to solve discretized finite element models. By solving linear or nonlinear equations, the response of the system under various working conditions, such as displacement, stress, temperature, etc., can be obtained.

[0060] The establishment of a finite element model (FEM) is the core of simulation. This step mainly simplifies a complex actual structure (such as a metal plate) into a mathematical model composed of multiple small units (i.e., finite elements). Each unit is connected to each other through nodes and bears physical quantities such as force and displacement. This model can simulate the behavior of real structures under conditions such as force and temperature changes. In ANSYS, establishing a finite element model usually includes defining material properties (such as elastic modulus, Poisson's ratio, etc.), geometry, boundary conditions, and loads. For metal plates, establishing a finite element model can understand the distribution of physical quantities such as stress, strain, and displacement under various conditions, which is of great significance for design optimization, strength verification, and other aspects.

[0061] Mesh Refinement is a key step to further optimize the finite element model. The mesh is the basic component of the finite element model, which determines the accuracy and computational efficiency of the simulation. Mesh refinement means increasing the number of units in the model to make the mesh denser, so that it can more accurately capture the detailed features of the structure.

[0062] During the laser cladding process, the energy distribution of the laser beam usually presents a Gaussian distribution, that is, the energy at the center is high and the energy at the edge is low. Therefore, the Gaussian heat source model can more accurately reflect the energy distribution of the laser beam. In ANSYS, by setting the parameters of the Gaussian heat source model (such as heat source intensity, heat source size, etc.), the moving heating process of the laser beam on the surface of the part can be simulated. As the laser beam moves, the heat source model forms a continuous heating track on the surface of the part, thereby simulating the heating effect during the laser cladding process.

[0063] The birth-death element method is a numerical method used to simulate the gradual addition or removal of material. During the laser cladding process, cladding material is added layer by layer to the surface of the part as the laser beam moves and the molten pool forms. The birth-death element method can simulate this process by gradually activating or "killing" elements to reflect the addition or removal of material. Before the simulation starts, all cladding layer elements are set to a "dead" state, that is, they do not participate in the calculation. As the laser beam moves and the heating process proceeds, the elements within the irradiation range of the laser beam are gradually activated to participate in the calculation. In this way, the gradual addition of cladding material and the formation of the molten pool during laser cladding can be simulated.

[0064] Thermal load refers to the heat or temperature gradient acting on an object, which will cause thermal deformation and thermal stress of the object. In ANSYS, the simulated laser heating effect is applied to the surface of the part in the form of thermal load. By setting the size, distribution and time-varying law of the thermal load, the temperature distribution and changes on the surface of the part during the laser cladding process can be simulated. During the simulation, as the laser beam moves and the heating process proceeds, the thermal load is gradually applied to the activated unit. The simulation is calculated by the processing unit of ANSYS, and the temperature field results are displayed by the post-processor, so as to obtain the temperature distribution and changes on the surface of the part during the laser cladding process.

[0065] Use ANSYS postprocessor tools, such as Plot or Graph, to display temperature field results. You can choose to display the temperature field distribution of the entire model, or you can choose to display the temperature distribution on a specific section or path. Different colors or contour lines can be used to represent different temperature ranges. If you need to view the temperature of a specific node or element, you can use the QueryResults tool. Select the node or element and view its temperature value. In transient thermal analysis, you can generate a curve of temperature variation over time on a specific node or path. Use ANSYS's Time-History Postprocessor tool, select the corresponding node or path, and set the time range. Generate and display a curve of temperature variation over time.

[0066] The above process specifically includes the following steps: Step 1: Obtain parameter data.

[0067] The substrate material of the metal cladding process is EA4T, and its thermophysical property parameters and geometric size parameters are obtained. The cladding coating powder of the metal cladding process is Inconel625 alloy, and its thermophysical property parameters and geometric size parameters are obtained. The process parameters in the metal cladding production process are obtained. The above parameters are used to determine the geometric model, heat source model, etc. of the metal cladding process, and establish an accurate temperature field calculation finite element model to simulate the metal cladding process.

[0068] Step 2: Simulation model establishment.

[0069] According to the parameters obtained in step 1, a simulation model of the metal cladding process of the metal plate is established using ANSYS; at the same time, the thermophysical properties parameters of the substrate and cladding layer materials, the contact and ambient temperatures, and the parameters of the moving Gaussian surface heat source are determined.

[0070] Step 3: Model simulation process.

[0071] The cladding simulation model in step 2 is used to simulate the metal cladding process to obtain the transient temperature field changes of the substrate and the cladding layer during the entire cladding process.

[0072] Step 4: Compare and verify the simulation results The temperature field results obtained by laser cladding simulation calculation were compared and verified with the experimental molten pool results, and the heat source model parameters were further corrected to make the simulated molten pool morphology as close as possible to the experimental results under the same process parameters.

[0073] A further technical solution is that the specific contents of step 1 include: The chemical composition of the substrate material EA4T, the geometric dimensions of the substrate and the cladding layer; the moving Gaussian surface heat source model is selected for the determination of the laser heat source. The laser power is 1200W, the cladding speed is 0.05m / s, and the initial laser spot diameter is 1.2mm.

[0074] The technical solution for further analysis is that the specific content of the process of establishing the metal cladding simulation model in step 2 is as follows.

[0075] The size of the substrate is 110mm*100mm*10mm, the cladding layer is arranged in the center of the width direction of the substrate, the cladding layer size is 1.525mm wide, 0.194mm high, 30.5mm long, the outer contour is an arc, the grid is dense at the cladding position, and the grid is gradually sparse away from the cladding position to balance the relationship between calculation accuracy, convergence and calculation time cost. The minimum grid size is about 0.25 mm, and the entire model contains 85,000 units; the material thermophysical properties assigned include density, thermal conductivity, elasticity, specific heat capacity, plasticity, and thermal expansion coefficient; the ambient temperature is room temperature 20℃.

[0076] Establishment of surface effect units: For the surfaces to which heat loads need to be applied, use the selected SURF152 unit and divide the surface effect units, then select the surface effect units just divided and apply convection boundary conditions to them.

[0077] The "life and death unit technology" is used to numerically simulate the dynamic evolution process of synchronous powder feeding high-speed laser cladding. First, a finite element analysis model of high-speed cladding ultra-thin coating is constructed, and mesh division and unit sequence grouping are performed; then, the load step and time step are defined, and the large deformation setting option is turned on to "kill" all coating units in advance before the simulation calculation (that is, suppress unit behavior); secondly, the heat source loading movement speed with the time step is set, and the dead units in the heat source area are "activated" one by one in a time sequence. The technical solution for further analysis is that the specific content of the temperature field of the simulation process in step 3 is as follows.

[0078] After applying the Gaussian heat source, the temperature of the cladding layer rises rapidly with the increase of analysis time. In a short period of time of 0~0.03s, the maximum temperature in the center of the molten pool rises from room temperature to about 2200℃. Then, as the analysis time continues to increase, the laser heat source begins to move according to the cladding speed. Due to the effect of heat accumulation, the maximum temperature of the molten pool rises to about 2500℃ at the end of cladding at 0.61s. After the cladding process is completed, that is, after the heat source is removed, the model temperature drops rapidly at an extremely high cooling rate, and gradually forms a stable temperature field, and finally returns to room temperature.

[0079] In the results of metal cladding simulation, the depth of penetration is 0.066mm and the depth of heat affected zone is 0.199mm. The temperature field cloud diagram (penetration direction) at a certain moment is as follows: Figure 7 shown.

[0080] In the metal cladding test results, the penetration depth is 0.069 mm and the depth of the heat affected zone is 0.221 mm.

[0081] The error between the simulation result and the experimental result of the metal cladding melting depth is about 4%, and the error between the simulation result and the experimental result of the metal cladding heat affected zone depth is about 9%, and the errors of both are less than 10%, which shows that the simulation results of the metal cladding temperature field are in good agreement with the experimental results.

[0082] from Figure 7 From the temperature field cloud diagram (heat source movement direction) at a certain moment, it can be seen that the heat affected zone near the cladding layer is small, which is also in line with the significant characteristics of high-speed laser cladding.

[0083] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A laser cladding temperature field analysis method based on finite element simulation method, characterized in that: The following steps are involved: S1: Obtain the thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate and the cladding coating material, and obtain the process parameters in the metal cladding production process; S2: Import the obtained thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate material and the cladding coating material as well as the process parameters in the metal cladding production process into the ANSYS software, establish a simulation model of the metal cladding simulation process, and determine the simulation parameters; S3: using the obtained thermophysical property parameters, geometric dimension parameters of the substrate and the cladding layer material and the process parameters in the metal cladding production process, and calculating the temperature field of the laser cladding process of the substrate according to the simulation model, to complete the analysis process of the laser cladding temperature field; In the calculation process, a Gaussian surface heat source distribution function is selected for simulation, and a moving heat source and a unit birth and death method are used to simulate the gradual cladding and accumulation process of the cladding layer material.

2. The laser cladding temperature field analysis method based on finite element simulation method according to claim 1 is characterized in that: The thermophysical property parameters include thermal conductivity, specific heat capacity, thermal expansion coefficient and elastic modulus.

3. The laser cladding temperature field analysis method based on finite element simulation method according to claim 1 is characterized in that: The geometrical dimension parameters of the substrate include the length, width and thickness of the substrate; the geometrical dimension parameters of the cladding coating material include the width, thickness and position of the cladding layer relative to the substrate.

4. The laser cladding temperature field analysis method based on finite element simulation method according to claim 1 is characterized in that: The process parameters in the metal cladding production process include laser power, cladding speed, cladding depth, cladding width and heat affected zone depth.

5. The laser cladding temperature field analysis method based on finite element simulation method according to claim 1 is characterized in that: In step S2, the obtained thermophysical property parameters and geometric dimension parameters of the metal cladding process substrate material and the cladding coating material and the process parameters in the metal cladding production process are imported into the ANSYS software to establish a simulation model of the metal cladding simulation process and determine the simulation parameters, specifically: finite element meshing is performed on the components of the established simulation model, and material properties are assigned to the components.

6. The laser cladding temperature field analysis method based on finite element simulation method according to claim 5 is characterized in that: The mesh density at the cladding location is greater than that at the location far from the cladding.

7. The laser cladding temperature field analysis method based on finite element simulation method according to claim 5 is characterized in that: The grid size at the coating location is 0.25 mm.

8. The laser cladding temperature field analysis method based on finite element simulation method according to claim 1 is characterized in that: In step S3, the temperature field of the laser cladding process of the substrate is calculated according to the simulation model to complete the analysis process of the laser cladding temperature field, and the analysis process generates a temperature distribution cloud map or a curve chart of temperature change over time.

9. The laser cladding temperature field analysis method based on finite element simulation method according to claim 1 is characterized in that: After step S3, the method further includes comparing and verifying the temperature field result obtained by the laser cladding simulation calculation with the experimental molten pool result.

10. The laser cladding temperature field analysis method based on finite element simulation method according to claim 9, characterized in that: The temperature field results obtained by laser cladding simulation calculation were compared and verified with the experimental molten pool results. Specifically, the molten pool morphology of the simulated coating cross section was compared with the molten pool morphology of the actual coating cross section, and the parameters in the Gaussian heat source model were corrected so that the error between the simulation results and the experimental results was less than 4%.

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