A stainless steel transient sensitization model verification method based on numerical simulation
By creating a virtual heat treatment model and performing numerical simulations to obtain temperature change curves, and substituting them into the sensitization model to calculate the degree of sensitization, the accuracy of the model was verified by combining sample heat treatment. This solved the problem of verifying the accuracy of the stainless steel sensitization model and improved the estimation accuracy of the degree of sensitization.
Patent Information
- Application Number
- CN202211634365.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-12-19
- Publication Date
- 2025-11-28
- Estimated Expiration
- 2042-12-19
AI Technical Summary
In the prior art, stainless steel components are prone to sensitization in high temperature and high pressure corrosive environments, which leads to a decrease in corrosion resistance. Furthermore, the accuracy of sensitization models is difficult to verify, and the heat preservation time cannot be predicted, affecting the accurate estimation of the degree of sensitization.
By creating a virtual model of heat treatment, meshing is performed, and physical properties and numerical simulation parameters are set. Temperature change curves are obtained, which are then substituted into a transient sensitization model to calculate the degree of sensitization. The accuracy of the model is verified by comparing it with the actual sensitization degree of the sample.
The accuracy of the stainless steel sensitization model was verified, the problem of difficulty in predicting the holding time was solved, and the accuracy of sensitization degree estimation was improved.
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Figure CN115910250B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of numerical simulation, and particularly relates to a stainless steel transient sensitization model verification method based on numerical simulation. BACKGROUND
[0002] Stainless steel is widely used in the complex environments of chemical industry, petroleum, pharmaceutical and energy industry due to its excellent chemical stability and good processing performance, which are usually exposed to high temperature, high pressure and corrosion, or operate in the process requiring strict product quality control. In these environments, stainless steel is prone to sensitization effect, resulting in decreased corrosion resistance.
[0003] In engineering, the sensitization degree caused by corresponding temperature and time can be calculated by means of the sensitization model, so as to reduce the loss caused by corrosion due to sensitization of stainless steel. Therefore, the accuracy of the sensitization model greatly affects the estimated sensitization degree, and determining the accuracy of the sensitization model has great significance for the estimation of the sensitization degree.
[0004] However, it is difficult to predict the holding time of each position of the stainless steel component, and when the entity component is heated and data is collected to verify the sensitization model, the residence time in the sensitization temperature interval is difficult to predict due to the long holding time, so that the accuracy of the sensitization model cannot be verified.
[0005] Based on the above problems, a method for verifying the accuracy of the sensitization model is needed. SUMMARY
[0006] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the purposes of the present application is to at least solve one or more of the above-mentioned problems in the prior art, in other words, one of the purposes of the present application is to provide a stainless steel transient sensitization model verification method based on numerical simulation which meets one or more of the above-mentioned needs.
[0007] In order to achieve the above-mentioned purposes of the application, the following technical solutions are adopted in the present application:
[0008] A stainless steel transient sensitization model verification method based on numerical simulation, specifically comprising the following steps:
[0009] S1, determining the heat treatment requirements of the stainless steel component, and creating a heat treatment virtual model;
[0010] S2, performing grid division on the heat treatment virtual model, and defining the physical performance parameters and numerical simulation parameters of the heat treatment virtual model;
[0011] S3, performing heat treatment numerical simulation on the heat treatment virtual model according to the physical performance parameters and the numerical simulation parameters, and obtaining the temperature change curve of the surface of the heat treatment virtual model;
[0012] S4, setting a plurality of verification points on the heat treatment virtual model, and obtaining temperature change curves of the plurality of verification points according to temperature change curves of a surface of the heat treatment virtual model;
[0013] S5, substituting the temperature change curves of the plurality of verification points into the transient sensitization model to calculate a simulated sensitization degree of each verification point;
[0014] S6, setting a sample corresponding to each verification point, simulating a temperature change curve corresponding to the verification point, and performing heat treatment on each sample respectively;
[0015] S7, detecting an actual sensitization degree of each sample;
[0016] S8, determining accuracy of the transient sensitization model according to the simulated sensitization degree of each verification point and the actual sensitization degree of the sample corresponding to the verification point.
[0017] As a preferred solution, in step S2, the physical performance parameters specifically include:
[0018] specific heat capacity, thermal conductivity, linear expansion coefficient, elastic modulus, shear modulus, Poisson's ratio and yield limit of the heat treatment virtual model.
[0019] As a preferred solution, in step S2, the numerical simulation parameters specifically include:
[0020] surface heat dissipation boundary condition, heat treatment working condition calculation total time, structure convergence setting, displacement convergence value and simulation saving step length of the heat treatment virtual model.
[0021] As a further preferred solution, the surface heat dissipation condition specifically includes:
[0022] environmental temperature, set to 20℃;
[0023] air convection heat transfer coefficient, set to 0.02.
[0024] As a further preferred solution, the heat treatment working condition calculation total time is set to 190800s, the structure convergence setting is displacement criterion, the displacement convergence value is set to 0.1mm, and the simulation saving step length is set to 10 steps.
[0025] As a preferred solution, the verification point is a point on the surface of the heat treatment virtual model, which is in a temperature range of 400℃-850℃ for more than a preset time length.
[0026] As a preferred solution, the sample uses a cubic sample of 10mm*10mm*5mm.
[0027] Compared with the prior art, the present application has the beneficial effects that:
[0028] The method of the present application solves the problem that the holding time of each position of the physical model is difficult to predict by extracting the temperature change curve of each position through numerical simulation, substitutes the numerical simulation result of heat treatment into the sensitization model to obtain the sensitization degree of the position, and then obtains the actual heat treatment sensitization degree by heat treating the stainless steel sample under the same temperature curve; the accuracy of the model is verified by comparing the actual sensitization degree with the simulated sensitization degree. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 It is a flow chart of the stainless steel transient sensitization model verification method based on numerical simulation of the present application;
[0030] Figure 2 It is a shape schematic diagram of the heat treatment virtual model of the present application;
[0031] Figure 3 It is a selection schematic diagram of the verification point of the present application;
[0032] Figure 4 It is a temperature change curve of the A point verification point of the present application;
[0033] Figure 5 It is a temperature change curve of the B point verification point of the present application;
[0034] Figure 6 It is a sample grain boundary schematic diagram of the present application. DETAILED DESCRIPTION
[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.
[0036] In the following description, a plurality of embodiments of the present application are provided, and different embodiments can be replaced or combined, so that the present application can also be considered to include all possible combinations of the same and / or different embodiments described. Therefore, if one embodiment includes features A, B and C, and another embodiment includes features B and D, the present application should also be considered to include one or more embodiments of all other possible combinations of A, B, C and D, although the embodiment may not be explicitly described in the following content.
[0037] The following description provides examples and does not limit the scope, applicability or examples set forth in the claims. Changes can be made to the functions and arrangements of described elements without departing from the scope of the present application. Various processes or components can be appropriately omitted, replaced or added to various examples. For example, the described methods can be performed in different order from the described order, and various steps can be added, omitted or combined. In addition, features described with respect to some examples can be combined into other examples.
[0038] The application provides a stainless steel transient sensitization model verification method based on numerical simulation, a flow of which is as shown in Figure 1 The application provides a stainless steel transient sensitization model verification method based on numerical simulation, a flow of which is as shown in
[0039] S1, determining the heat treatment requirement of the stainless steel component, and creating a heat treatment virtual model. Here, the embodiment creates a heat treatment virtual model of the same size for subsequent simulation through 3D modeling according to the actual size of the stainless steel component required for simulation. In an embodiment of the application, the shape of the heat treatment virtual model is as shown in Figure 2
[0040] S2, meshing the heat treatment virtual model, and defining the physical performance parameters and numerical simulation parameters of the heat treatment virtual model.
[0041] In certain preferred embodiments of the application, in step S2, the physical performance parameters are determined according to the actual material parameters used in production, and specifically include:
[0042] The specific heat capacity, thermal conductivity, linear expansion coefficient, elastic modulus, shear modulus, Poisson's ratio and yield limit of the heat treatment virtual model.
[0043] In addition, in step S2, the numerical simulation parameters specifically include:
[0044] The surface heat dissipation boundary condition, heat treatment working condition calculation total time, structure convergence setting, displacement convergence value and simulation saving step length of the heat treatment virtual model.
[0045] Since there is heat dissipation on the surface, the surface heat dissipation boundary condition needs to be set. Heat loss mainly includes radiation and convection between the workpiece surface and the surrounding environment, and is mainly in the form of radiation loss; the higher the temperature, the stronger the radiation effect, and generally in the region with a temperature greater than 1200℃, the radiation loss is greater than the convection heat loss, while below 1200℃, the convection heat dissipation is dominant.
[0046] The ambient temperature in the surface heat dissipation condition is set to 20℃, and the air convection heat transfer coefficient is set to 0.02.
[0047] The heat treatment working condition calculation total time is set to 190800s, the structure convergence setting is set to displacement criterion, the displacement convergence value is set to 0.1mm, the thermodynamic numerical simulation analysis step length is 120, that is, 1950s per step; the simulation saving step length is set to 10 steps, and the calculation result is saved every 10 steps.
[0048] The heat dissipation working condition calculation total time is 10000s, which is set to temperature self-adaption, the structure convergence setting is set to displacement criterion, and the displacement convergence value is 0.1mm.
[0049] S3, according to the physical performance parameters and the numerical simulation parameters, performing numerical simulation on the heat treatment virtual model, and obtaining the temperature change curve of the surface of the heat treatment virtual model. In the heat treatment process, the temperature of each point on the surface of the heat treatment virtual model is collected according to the grid division time, so as to generate the temperature change curve of each point on the surface of the heat treatment virtual model according to the data of each point temperature at each time in the whole heat treatment process.
[0050] S4, setting a plurality of verification points on the heat treatment virtual model, and obtaining the temperature change curve of the verification points according to the temperature change curve of the surface of the heat treatment virtual model. Calling the temperature change curve of each point simulated in step S3, selecting N verification points, and extracting the temperature change curve at the verification points, so as to obtain N groups of simulated temperature fields and temperature change curves.
[0051] In an embodiment of the present application, the selection of two verification points A and B is as shown in Figure 3 .
[0052] The selection of the verification points is the points on the surface of the heat treatment virtual model which are in the temperature range of 400-850 DEG C for more than a preset time length. The points in the temperature range of 400-850 DEG C have a higher sensitization trend, and therefore it is easier to obtain results by comparing with the transient sensitization model.
[0053] S5, substituting the temperature change curves of the verification points into the transient sensitization model to calculate the simulated sensitization degree of each verification point. Substituting the temperature change curve of each verification point in step S4 into the transient sensitization model respectively, and using the transient sensitization model to calculate, so as to obtain the simulated sensitization degree of N verification points.
[0054] Figure 4 、 Figure 5 The temperature change curves of the two verification points A and B selected are Figure 3 , the fitting expression of the heating temperature T and the heating time t in the curve is substituted into the function of the transient sensitization model, the integral function of the sensitization degree is formed, and the simulated sensitization degree of the two verification points can be calculated respectively, wherein x Cr is the chromium content near the grain boundary, that is, the sensitization degree. When the chromium content is below the corrosion resistance limit, the corrosion resistance of the material will be affected.
[0055] S6, setting a sample corresponding to each verification point, and simulating the temperature change curve corresponding to the verification point to heat treat each sample respectively.
[0056] In step S6, a 10mm x 10mm x 5mm cubic sample is used to perform a real heat treatment experiment.
[0057] S7, after the heat treatment of the sample in step S6, the actual sensitization degree of each sample is detected.
[0058] The grain boundaries of the sample are observed by scanning electron microscopy, and as shown in FIG. 4, line scanning analysis is performed by an energy dispersive spectrometer in the direction perpendicular to the grain boundary to obtain the chromium content near the grain boundary of the sample. Figure 6
[0059] S8, the accuracy of the transient sensitization model is determined according to the simulated sensitization degree of each verification point obtained in step S5 and the actual sensitization degree of the corresponding sample. If the calculated sensitization degree is higher than 20% of the actual sensitization degree and not lower than the actual sensitization degree, it indicates that the transient sensitization model has practical guiding significance in engineering; if the calculated sensitization degree is lower than the actual sensitization degree, the transient sensitization model is not accurate enough, and there may still be a situation of judging non-sensitization but sensitization corrosion in engineering, and the function of the transient sensitization model still needs to be adjusted.
[0060] The above-described embodiments are merely exemplary embodiments of the present disclosure, and cannot limit the scope of the present disclosure. That is, any equivalent changes and modifications made in accordance with the teachings of the present disclosure are still within the scope of the present disclosure. Those skilled in the art will easily think of embodiments of the present disclosure after considering the specification and practicing the disclosure herein. The present application is intended to cover any variations, uses, or adaptive changes of the present disclosure that follow the general principles of the present disclosure and include common knowledge or conventional technical means in the technical field not disclosed by the present disclosure. The specification and examples are only considered as exemplary, and the scope and spirit of the present disclosure are defined by the claims.
Claims
1. A method for verifying a transient sensitization model of stainless steel based on numerical simulation, characterized in that, Specifically, the steps include the following: S1. Determine the heat treatment requirements for stainless steel components and create a virtual model for heat treatment; S2. Mesh the heat treatment virtual model and define the physical performance parameters and numerical simulation parameters of the heat treatment virtual model; S3. Based on the physical performance parameters and numerical simulation parameters, perform heat treatment numerical simulation on the heat treatment virtual model and obtain the temperature change curve of the surface of the heat treatment virtual model. S4. Set several verification points on the heat treatment virtual model, and obtain the temperature change curves of the several verification points according to the temperature change curve of the surface of the heat treatment virtual model. S5. Substitute the temperature change curves of the verification points into the transient sensitization model and calculate the simulated sensitization degree of each verification point. S6. Set up a sample for each verification point, and perform heat treatment on each sample to mimic the temperature change curve of the corresponding verification point. S7. Detect the actual sensitization level of each sample; S8. Determine the accuracy of the transient sensitization model based on the simulated sensitization degree of each verification point and the actual sensitization degree of the corresponding sample.
2. The method for verifying the transient sensitization model of stainless steel based on numerical simulation as described in claim 1, characterized in that, In step S2, the physical performance parameters specifically include: The specific heat capacity, thermal conductivity, coefficient of linear expansion, elastic modulus, shear modulus, Poisson's ratio, and yield strength of the heat treatment virtual model are specified.
3. The method for verifying the transient sensitization model of stainless steel based on numerical simulation as described in claim 1, characterized in that, In step S2, the numerical simulation parameters specifically include: The surface heat dissipation boundary conditions, total calculation time for heat treatment conditions, structural convergence settings, displacement convergence values, and simulation saving step size of the virtual model for heat treatment are specified.
4. The method for verifying the transient sensitization model of stainless steel based on numerical simulation as described in claim 3, characterized in that, The surface heat dissipation conditions specifically include: The ambient temperature is set to 20℃. The convective heat transfer coefficient in the air is set to 0.
02.
5. The method for verifying the transient sensitization model of stainless steel based on numerical simulation as described in claim 3, characterized in that, The total calculation time for the heat treatment condition was set to 190,800 s, the structural convergence was set to the displacement criterion, the displacement convergence value was set to 0.1 mm, and the simulation saving step size was set to 10 steps.
6. The method for verifying the transient sensitization model of stainless steel based on numerical simulation as described in claim 1, characterized in that, The verification point is the point on the surface of the heat treatment virtual model that has been in a temperature range of 400℃-850℃ for more than a preset time.
7. The method for verifying the transient sensitization model of stainless steel based on numerical simulation as described in claim 1, characterized in that, The specimen used is a cubic specimen with dimensions of 10mm × 10mm × 5mm.