CN115383071B - Quenching process design method - Google Patents
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Abstract
The invention provides a quenching process design method, which comprises the following steps: calculating the temperature of the quenching medium at the end of quenching according to the temperature field of the casting blank in the quenching process, the given initial quenching medium temperature, the quenching medium capacity and the quenching time; establishing a corresponding relation among the initial quenching medium temperature, the quenching medium temperature at the end of quenching and the quenching medium capacity; according to the corresponding relation, the capacity of the quenching medium in the quenching process of the continuous casting blank is designed according to the preset initial quenching medium temperature, the preset quenching medium temperature at the end of quenching and the preset quenching temperature rise threshold value. The invention can solve the problem that a reasonable design method of a groove type quenching process capable of accurately simulating the quenching process is lacking at present.
Description
Technical Field
The invention relates to the technical field of continuous casting processing, in particular to a quenching process design method.
Background
The surface quenching technology in the continuous casting process is an effective technology for solving the problems of high-temperature hot-feeding surface hot cracking or wide-thick plate corner cracking of continuous casting billets of various steels, and can remarkably improve the production efficiency and reduce the production cost. The surface quenching process simulation model has important effects on quantitative research of surface quenching process parameters, equipment type selection design and the like, and can obviously improve the effectiveness and quality of the design, thereby ensuring the final use effect of the surface quenching technology.
In the surface quenching simulation process, the temperature of the quenching medium has a remarkable influence on the heat exchange coefficient, so that the calculation result, the process research and the like are influenced, particularly, for water-cooling trough type quenching, the temperature of the quenching medium in the quenching device is a changing process in the quenching process of the continuous casting billet, the temperature of the quenching medium is continuously increased on the basis of the initial temperature due to the release of heat of a casting billet, and if the temperature of the quenching medium is calculated according to the constant temperature of the quenching medium, the result is greatly deviated from the actual situation, and the distortion of the process research is caused, so that the simulation method is very necessary to process.
The design of the quantity of the quenching medium in the quenching device can bring decisive influence to the quenching effect, firstly, the quantity of the quenching medium in the quenching device must ensure the complete immersion of the continuous casting blank, on the basis, if the quantity of the quenching medium is selected to be smaller, the excessive temperature rise of the quenching medium in the quenching process can be caused, the quenching effect is influenced, the surface quenching target can not be reached, and even the defect of the casting blank is caused; if the amount of the quenching medium is selected to be larger, the increase of the amount of the quenching medium of the quenching system is brought, and the system load is increased.
Because of the lack of a searchable method capable of accurately simulating the quenching process, a reasonable design method of a cooling tank type quenching process is rapidly proposed.
Disclosure of Invention
In view of the above problems, the present invention aims to provide a design method of a quenching process, so as to solve the problem that a reasonable design method of a trough-type quenching process capable of accurately simulating a quenching process is lacking at present.
The invention provides a quenching process design method, which comprises the following steps:
S1, calculating the temperature of a quenching medium at the end of quenching according to a casting blank temperature field in the quenching process, the given initial quenching medium temperature, the quenching medium capacity and the quenching time;
s2, establishing a corresponding relation among the initial quenching medium temperature, the quenching medium temperature at the end of quenching and the quenching medium capacity;
S3, designing the capacity of the quenching medium in the quenching process of the continuous casting billet according to the corresponding relation, the preset initial quenching medium temperature, the preset quenching medium temperature at the end of quenching and the preset quenching temperature rise threshold value;
The preset quenching temperature rise threshold value is a reasonable process value of the temperature difference between the quenching medium temperature and the preset initial quenching medium temperature at the end of the preset quenching.
Furthermore, it is preferable that the calculating of the quenching medium temperature at the end of quenching according to the casting blank temperature field of the quenching process, the given initial quenching medium temperature, the quenching medium capacity and the quenching time includes:
A1, carrying out real-time tracking calculation on a temperature field in the quenching process of the continuous casting blank through a temperature field calculation model to obtain a continuously-changed casting blank temperature field;
A2, calculating heat conducted from the continuous casting blank in a preset time step according to the casting blank temperature field, the initial quenching medium temperature and the heat exchange coefficient of the surface of the casting blank;
a3, calculating the heat absorbed by the quenching medium in the preset time step according to the heat led out from the continuous casting blank in the preset time step and a preset effective coefficient;
A4, calculating the quenching medium temperature after the preset time step is finished according to the heat absorbed by the quenching medium in the preset time step and the quenching medium temperature corresponding to the quenching medium after the previous preset time step is finished;
A5, repeating the steps A2 to A4 until the quenching is finished, and obtaining the temperature of the quenching medium at the end of the quenching.
In addition, the preferred scheme is that the temperature field calculation model calculates the temperature field of the continuous casting blank by adopting a conversion temperature and conversion enthalpy method, and the method comprises the following calculation formulas:
Heat transfer differential reduction formula:
Wherein ρ is the density of the continuous casting billet, T is the heat transfer time, λ 0 is the heat conductivity coefficient at the reference temperature T 0, φ is the conversion temperature, H is the enthalpy, and x and y are the abscissa and the ordinate of the temperature field respectively;
The enthalpy calculation formula is:
Wherein T 0 is an optional reference temperature, H 0 is a corresponding reference enthalpy, L is latent heat of solidification, c p (τ) is specific heat at temperature τ, and f s is solid fraction;
the conversion temperature and the temperature corresponding relation formula is as follows:
Wherein λ 0 is the thermal conductivity at the reference temperature T 0; lambda (t) is the thermal conductivity at temperature t.
Furthermore, preferably, the calculating the heat derived from the continuous casting slab in the preset time step according to the casting slab temperature field, the initial quenching medium temperature and the heat exchange coefficient of the casting slab surface includes:
In a preset time step, calculating the heat flow of the continuous casting blank according to the continuous casting blank temperature field and the heat exchange coefficient of the surface of the casting blank; wherein the heat exchange coefficient of the casting blank surface and the temperature of the quenching medium are related functions, and h=f (Tw); h is the heat exchange coefficient of the surface of the casting blank, and Tw is the temperature of the quenching medium;
and calculating heat quantity led out from the continuous casting blank in a preset time step according to the heat flow of the continuous casting blank and the initial quenching medium temperature.
Furthermore, preferably, the boundary heat exchange in the quenching process of the continuous casting blank adopts a third type of boundary condition, and the third type of boundary condition is that:
q＝h*(Tsurface-Twater)；
Wherein q is heat flow, h is heat exchange coefficient of the surface of the casting blank, tsurface is surface temperature of the casting blank, theater is temperature after the last time step of the quenching medium is finished, and when the heat flow of the continuous casting blank in the first preset time step is calculated, the temperature of the last preset time step of the quenching medium is the initial quenching medium temperature.
Furthermore, it is preferred that the calculation of the heat quantity derived from the continuous casting slab in a predetermined time step from the heat flow of the continuous casting slab and the initial quenching medium temperature comprises:
calculating the average heat flow of the continuous casting blank by adopting an average heat flow calculation formula;
Wherein, the average heat flow calculation formula is:
Wherein q ave is the average heat flow of the continuous casting billet, q i is the heat flow of each calculation grid preset on the continuous casting billet, and n is the number of calculation grids;
According to the average heat flow of the continuous casting billet, a heat quantity calculation formula is led out of the first continuous casting billet, and the heat quantity led out of the continuous casting billet in a preset time step is calculated;
Wherein, the formula of heat calculation is derived to first continuous casting billet is:
Q＝qave·2(a+b)L·Δt；
Wherein Q is the heat of the continuous casting billet, Q ave is the average heat flow of the continuous casting billet, a and b are the section thickness and width of the continuous casting billet respectively, L is the fixed length of the continuous casting billet, and Deltat is the preset time step.
Furthermore, it is preferred that the calculation of the heat quantity derived from the continuous casting slab in a predetermined time step from the heat flow of the continuous casting slab and the initial quenching medium temperature comprises:
according to the area of the calculation grid divided on the contact surface of the continuous casting blank and the quenching medium, a second continuous casting blank is adopted to derive a heat calculation formula, and the heat derived from the continuous casting blank in a preset time step is calculated; wherein, the second continuous casting billet heat-derived calculation formula is:
Wherein,
Q is the heat quantity of the continuous casting billet, Q i is the heat flow of each calculation grid preset on the continuous casting billet, deltaS i is the area of each calculation grid, deltat is the preset time step, L is the fixed length of the continuous casting billet, and n is the number of calculation grids.
In addition, preferably, the calculation formula of the heat absorbed by the quenching medium is as follows:
Qw=q×η; wherein Qw is the part of heat which is extracted from the continuous casting billet and absorbed by the quenching medium, and eta is the preset effective coefficient.
Furthermore, preferably, the calculating the quenching medium temperature after the preset time step according to the heat absorbed by the quenching medium in the preset time step and the quenching medium temperature corresponding to the quenching medium after the end of the previous preset time step includes:
calculating the temperature rise value of the quenching medium in the preset time step by adopting a quenching medium temperature rise calculation formula; wherein, the quenching medium temperature rise calculation formula is:
Δt=qw/(w×cp); wherein,
Delta T is an elevated value of the temperature of the quenching medium, qw is a part of heat which is derived from the continuous casting billet and absorbed by the quenching medium, W is the capacity of the quenching medium, and Cp is the specific heat of the quenching medium;
calculating the temperature of the quenching medium after the preset time step is finished through a quenching medium temperature calculation formula after the preset time step is finished; wherein,
The quenching medium temperature after the preset time step is finished is calculated according to the following formula:
Tw＝Tw1+△T；
wherein Tw is the quenching medium temperature after the end of the preset time step, tw1 is the quenching medium temperature corresponding to the beginning of the preset time step, and DeltaT is the temperature rise value of the quenching medium.
Furthermore, preferably, the preset initial quenching medium temperature is not more than 45 ℃; the temperature of the quenching medium at the end of the preset quenching is not more than 60 ℃; the preset quenching temperature rise threshold is not more than 20 ℃; and/or, the quenching medium is water.
According to the technical scheme, the quenching process design method provided by the invention is characterized in that the accurate surface quenching calculation model (namely, the application of the temperature field calculation model in the quenching process) is utilized to calculate the casting blank temperature field in the quenching process, and the quenching medium temperature at the end of quenching is calculated according to the given initial quenching medium temperature, quenching medium capacity and quenching time, so that the corresponding relation among the initial quenching medium temperature, the quenching medium temperature at the end of quenching and the quenching medium capacity under different working conditions is obtained, and then the quenching medium capacity in the continuous casting quenching process is rapidly and accurately designed according to the preset initial quenching medium temperature, the preset quenching medium temperature at the end of quenching and the limiting conditions of the preset quenching temperature rise threshold value, so that the quenching effect is ensured. According to the method provided by the invention, through accurately simulating the surface quenching process, the real-time change of the temperature of the quenching medium is considered, the actual situation is reflected, and the calculation result is more reliable.
To the accomplishment of the foregoing and related ends, one or more aspects of the invention comprise the features hereinafter fully described. The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Furthermore, the invention is intended to include all such aspects and their equivalents.
Drawings
Other objects and attainments together with a more complete understanding of the invention will become apparent and appreciated by referring to the following description taken in conjunction with the accompanying drawings. In the drawings:
FIG. 1 is a schematic flow chart of a quenching process design method according to an embodiment of the invention;
Fig. 2 is a graph showing the trend of temperature rise at various initial water temperatures and water capacities in example 1 according to the present invention.
In the drawings, like reference numerals designate similar or corresponding features or functions.
Detailed Description
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details.
Aiming at the problem that a reasonable design method of a groove type quenching process capable of accurately simulating the quenching process is lacking at present, the quenching process design method is provided.
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
In order to illustrate the quenching process design method provided by the invention, fig. 1 shows a flow of the quenching process design method according to an embodiment of the invention; fig. 2 shows the trend of temperature rise at different initial water temperatures and water capacities in example 1 according to the present invention.
As shown in fig. 1 and fig. 2 together, the quenching process design method provided by the invention comprises the following steps:
s1, calculating the quenching medium temperature at the end of quenching according to the casting blank temperature field in the quenching process, the given initial quenching medium temperature, the quenching medium capacity and the quenching time.
As a preferred embodiment of the present invention, calculating the quenching medium temperature at the end of quenching based on the casting blank temperature field of the quenching process, the given initial quenching medium temperature, the quenching medium capacity, and the quenching time includes:
A1, carrying out real-time tracking calculation on a temperature field in the quenching process of the continuous casting blank through a temperature field calculation model to obtain a continuously-changed casting blank temperature field;
A2, calculating heat conducted from the continuous casting blank in a preset time step according to a casting blank temperature field, an initial quenching medium temperature and a heat exchange coefficient of the surface of the casting blank;
A3, calculating the heat absorbed by the quenching medium in the preset time step according to the heat led out from the continuous casting blank in the preset time step and the preset effective coefficient;
A4, calculating the temperature of the quenching medium after the preset time step is finished according to the heat absorbed by the quenching medium in the preset time step and the temperature of the quenching medium corresponding to the quenching medium after the previous preset time step is finished;
A5, repeating the steps A2 to A4 until the quenching is finished, and obtaining the temperature of the quenching medium at the end of the quenching.
As a preferable scheme of the invention, the temperature field calculation model adopts a conversion temperature and a conversion enthalpy method to calculate the temperature field of the continuous casting blank, and comprises the following calculation formulas:
Heat transfer differential reduction formula:
Wherein ρ is the density of the continuous casting billet, T is the heat transfer time, λ 0 is the heat conductivity coefficient at the reference temperature T 0, φ is the conversion temperature, H is the enthalpy, and x and y are the abscissa and the ordinate of the temperature field respectively;
The enthalpy calculation formula is:
Wherein T 0 is an optional reference temperature, H 0 is a corresponding reference enthalpy, L is latent heat of solidification, c p (τ) is specific heat at temperature τ, and f s is solid fraction;
the conversion temperature and the temperature corresponding relation formula is as follows:
Wherein λ 0 is the thermal conductivity at the reference temperature T 0; lambda (t) is the thermal conductivity at temperature t.
As a preferred embodiment of the present invention, calculating heat derived from a continuous casting slab within a preset time step based on a casting slab temperature field, an initial quenching medium temperature, and a heat exchange coefficient of a surface of the casting slab includes:
in a preset time step, calculating the heat flow of the continuous casting blank according to the temperature field of the continuous casting blank and the heat exchange coefficient of the surface of the continuous casting blank; wherein the heat exchange coefficient of the surface of the casting blank and the temperature of the quenching medium are related functions, and h=f (Tw); h is the heat exchange coefficient of the surface of the casting blank, and Tw is the temperature of the quenching medium;
And calculating heat quantity led out from the continuous casting blank in a preset time step according to the heat flow of the continuous casting blank and the initial quenching medium temperature.
And considering the balance of the heat released by the casting blank and the heat absorbed by the quenching medium in each preset time step, and considering the temperature rise of the quenching medium caused by the heat released by the casting blank in each preset time step, determining the temperature of the real-time quenching medium, and taking the temperature as the basis of heat transfer of the next preset time step, thereby ensuring the accuracy of a model calculation result and being closer to the actual situation.
As a preferred scheme of the invention, the boundary heat exchange in the quenching process of the continuous casting blank adopts a third type of boundary conditions, wherein the third type of boundary conditions are as follows:
q＝h*(Tsurface-Twater)；
Wherein q is heat flow, h is heat exchange coefficient of the surface of the casting blank, tsurface is surface temperature of the casting blank, theater is temperature after the last time step of the quenching medium is finished, and when the heat flow of the continuous casting blank in the first preset time step is calculated, the temperature of the last preset time step of the quenching medium is the initial quenching medium temperature.
The initial quenching medium temperature is known, so that the heat flow of the continuous casting blank in each preset time step can be calculated, and then the quenching medium temperature at the end of quenching is finally calculated.
As a preferred aspect of the present invention, calculating the heat derived from the continuous casting slab in a preset time step based on the heat flow of the continuous casting slab and the initial quenching medium temperature includes:
calculating the average heat flow of the continuous casting blank by adopting an average heat flow calculation formula;
Wherein, the average heat flow calculation formula is:
Wherein q ave is the average heat flow of the continuous casting billet, q i is the heat flow of each calculation grid preset on the continuous casting billet, and n is the number of calculation grids;
According to the average heat flow of the continuous casting billet, a heat quantity calculation formula is led out of the first continuous casting billet, and the heat quantity led out of the continuous casting billet in a preset time step is calculated;
Wherein, the formula of heat calculation is derived to first continuous casting billet:
Q＝qave·2(a+b)L·Δt；
Wherein Q is the heat of the continuous casting billet, Q ave is the average heat flow of the continuous casting billet, a and b are the section thickness and width of the continuous casting billet respectively, L is the fixed length of the continuous casting billet, and Deltat is the preset time step.
As a preferred aspect of the present invention, calculating the heat derived from the continuous casting slab in a preset time step based on the heat flow of the continuous casting slab and the initial quenching medium temperature includes:
according to the area of a calculation grid divided on the contact surface of the continuous casting billet and the quenching medium, adopting a second continuous casting billet to lead out a heat calculation formula, and calculating the heat led out from the continuous casting billet in a preset time step; wherein, the second continuous casting billet heat-derived calculation formula is:
Wherein,
Q is the heat quantity of the continuous casting billet, Q i is the heat flow of each calculation grid preset on the continuous casting billet, deltaS i is the area of each calculation grid, deltat is the preset time step, L is the fixed length of the continuous casting billet, and n is the number of calculation grids.
The heat quantity led out by the continuous casting blank can be calculated by adopting the two calculation modes.
As a preferred embodiment of the present invention, the calculation formula of the amount of heat absorbed by the quenching medium is:
Qw=q×η; wherein Qw is the part of heat which is extracted from the continuous casting billet and absorbed by the quenching medium, and eta is the preset effective coefficient.
As a preferred embodiment of the present invention, calculating the quenching medium temperature after the end of the preset time step according to the amount of heat absorbed by the quenching medium in the preset time step and the corresponding quenching medium temperature after the end of the previous preset time step includes:
calculating the temperature rise value of the quenching medium in a preset time step by adopting a quenching medium temperature rise calculation formula; wherein, the quenching medium temperature rise calculation formula is:
Δt=qw/(w×cp); wherein,
Delta T is an elevated value of the temperature of the quenching medium, qw is a part of heat which is derived from the continuous casting billet and absorbed by the quenching medium, W is the capacity of the quenching medium, and Cp is the specific heat of the quenching medium;
calculating the temperature of the quenching medium after the preset time step is finished through a quenching medium temperature calculation formula after the preset time step is finished; wherein,
The quenching medium temperature calculation formula after the end of the preset time step is as follows:
Tw＝Tw1+△T；
wherein Tw is the quenching medium temperature after the end of the preset time step, tw1 is the quenching medium temperature corresponding to the beginning of the preset time step, and DeltaT is the temperature rise value of the quenching medium.
S2, establishing a corresponding relation among the initial quenching medium temperature, the quenching medium temperature at the end of quenching and the quenching medium capacity.
The method is used for designing the quenching medium capacity in the continuous casting blank quenching process by establishing the corresponding relation among different initial quenching medium temperatures, quenching medium temperatures at the quenching end and quenching medium capacities.
S3, according to the corresponding relation, designing the capacity of the quenching medium in the quenching process of the continuous casting blank according to the preset initial quenching medium temperature, the preset quenching medium temperature at the end of quenching and the preset quenching temperature rise threshold value.
The preset quenching temperature rise threshold value is a reasonable process value of the temperature difference between the quenching medium temperature and the preset initial quenching medium temperature at the end of preset quenching.
As a preferred aspect of the present invention, the initial quenching medium temperature is preset to be not more than 45 ℃; the temperature of the quenching medium is not more than 60 ℃ when the preset quenching is finished; the preset quenching temperature rise threshold is not more than 20 ℃; and/or the quenching medium is water.
Taking a water cooling tank quenching process as an example, the initial water temperature in the water cooling tank is not more than 45 ℃, the water temperature rising degree in the quenching process is not more than 20 ℃, and the water temperature after the quenching is finished is not more than 60 ℃. According to the process design criterion, the process design of the capacity of the cooling water in the water cooling tank can be performed on the basis of the accurate surface quenching calculation model, so that the quenching effect is ensured.
The following examples are presented to further illustrate the invention so that those skilled in the art may better understand the advantages and features of the invention.
Example 1:
Taking the industrial production of continuous casting water-cooling trough type quenching of small square billets in a certain factory as an example, wherein the section of a continuous casting billet is 180mm x 180mm, the specified length is 12m, the steel grade is 40Cr, and the process quenching time is 30s.
Under the two conditions that the initial water temperature in the water cooling tank at the beginning of quenching is 35 ℃ and 40 ℃, by using the method provided by the invention, (wherein the effective coefficient eta takes 1), the temperature rise condition under the condition of different water capacities in the water cooling tanks can be obtained, and the calculation result is shown in figure 2.
As can be seen from fig. 2, under the condition of the same quenching time and the same initial water temperature, the temperature rise of the cooling water in the surface quenching process is reduced along with the increase of the water capacity in the water cooling tank, and the quenching effect is more ensured. In fig. 2, although the temperature rise of the initial water temperature at 40 ℃ is smaller than that at 35 ℃, the water temperature after quenching at 40 ℃ is generally larger than that at 35 ℃, which indicates that the quenching effect at 35 ℃ is better.
The process design criteria according to the invention: the water temperature rising degree in the cooling process is not more than 20 ℃, the water temperature after the quenching is finished is not more than 60 ℃, and the water capacity in the water cooling tank is required to be more than 4T according to the specific situation of the embodiment.
According to the quenching process design method, the casting blank temperature field in the quenching process is calculated by using the accurate surface quenching calculation model (namely, the application of the temperature field calculation model in the quenching process), and the quenching medium temperature at the end of quenching is calculated according to the given initial quenching medium temperature, quenching medium capacity and quenching time, so that the corresponding relation among the initial quenching medium temperature, the quenching medium temperature at the end of quenching and the quenching medium capacity under different working conditions is obtained, and then the quenching medium capacity in the continuous casting quenching process is rapidly and accurately designed according to the preset initial quenching medium temperature, the preset quenching medium temperature at the end of quenching and the limiting conditions of the preset quenching medium temperature rise threshold, so that the quenching effect is ensured. According to the method provided by the invention, through accurately simulating the surface quenching process, the real-time change of the temperature of the quenching medium is considered, the actual situation is reflected, and the calculation result is more reliable.
The quenching process design method proposed according to the present invention is described above by way of example with reference to the accompanying drawings. It will be appreciated by those skilled in the art that various modifications may be made to the quench process design methodology set forth above without departing from the spirit of the invention. Accordingly, the scope of the invention should be determined from the following claims.
Claims (9)
1. The quenching process design method is characterized by comprising the following steps:
S1, calculating the quenching medium temperature at the end of quenching according to a continuous casting blank temperature field in the quenching process, the given initial quenching medium temperature, the quenching medium capacity and the quenching time, wherein the method comprises the following steps:
a1, carrying out real-time tracking calculation on a temperature field in the quenching process of the continuous casting billet through a temperature field calculation model to obtain a continuously-changed continuous casting billet temperature field;
A2, calculating heat conducted from the continuous casting billet in a preset time step according to the continuous casting billet temperature field, the initial quenching medium temperature and the heat exchange coefficient of the continuous casting billet surface;
a3, calculating the heat absorbed by the quenching medium in the preset time step according to the heat led out from the continuous casting blank in the preset time step and a preset effective coefficient;
A4, calculating the quenching medium temperature after the preset time step is finished according to the heat absorbed by the quenching medium in the preset time step and the quenching medium temperature corresponding to the quenching medium after the previous preset time step is finished;
A5, repeating the steps A2-A4 until the quenching is finished, and obtaining the temperature of the quenching medium at the end of the quenching;
s2, establishing a corresponding relation among the initial quenching medium temperature, the quenching medium temperature at the end of quenching and the quenching medium capacity;
S3, designing the capacity of the quenching medium in the quenching process of the continuous casting billet according to the corresponding relation, the preset initial quenching medium temperature, the preset quenching medium temperature at the end of quenching and the preset quenching temperature rise threshold value;
The preset quenching temperature rise threshold value is a reasonable process value of the temperature difference between the quenching medium temperature and the preset initial quenching medium temperature at the end of the preset quenching; the temperature of the preset initial quenching medium is not more than 45 ℃; the temperature of the quenching medium at the end of the preset quenching is not more than 60 ℃; the preset quenching temperature rise threshold is not more than 20 ℃.
2. The quenching process design method as claimed in claim 1, wherein,
The temperature field calculation model calculates the temperature field of the continuous casting blank by adopting a conversion temperature and conversion enthalpy method, and comprises the following calculation formulas:
Heat transfer differential reduction formula:
Wherein ρ is the density of the continuous casting billet, T is the heat transfer time, λ 0 is the heat conductivity coefficient at the reference temperature T 0, φ is the conversion temperature, H is the enthalpy, and x and y are the abscissa and the ordinate of the temperature field respectively;
The enthalpy calculation formula is:
Wherein T 0 is an optional reference temperature, H 0 is a corresponding reference enthalpy, L is latent heat of solidification, c p (τ) is specific heat at temperature τ, and f s is solid fraction;
the conversion temperature and the temperature corresponding relation formula is as follows:
Wherein λ 0 is the thermal conductivity at the reference temperature T 0; lambda (t) is the thermal conductivity at temperature t.
3. The method of claim 1, wherein calculating the heat derived from the continuous casting in the predetermined time step based on the continuous casting temperature field, the initial quenching medium temperature, and the heat transfer coefficient of the continuous casting surface comprises:
In a preset time step, calculating the heat flow of the continuous casting blank according to the continuous casting blank temperature field and the heat exchange coefficient of the continuous casting blank surface; wherein the heat exchange coefficient of the continuous casting billet surface and the temperature of the quenching medium are related functions, h=f (Tw); wherein h is the heat exchange coefficient of the surface of the continuous casting billet, and Tw is the temperature of the quenching medium;
and calculating heat quantity led out from the continuous casting blank in a preset time step according to the heat flow of the continuous casting blank and the initial quenching medium temperature.
4. The quenching process design method according to claim 1, wherein the boundary heat exchange of the continuous casting billet quenching process adopts a third type of boundary conditions, and the third type of boundary conditions are as follows:
q＝h*(Tsurface-Twater)；
Wherein q is heat flow, h is heat exchange coefficient of the surface of the continuous casting billet, tsurface is surface temperature of the continuous casting billet, theater is temperature after the last time step of the quenching medium is finished, and when the heat flow of the continuous casting billet in the first preset time step is calculated, the temperature of the last preset time step of the quenching medium is the initial quenching medium temperature.
5. A quenching process design method according to claim 3, wherein calculating the heat derived from the continuous casting slab in a preset time step based on the heat flow of the continuous casting slab and the initial quenching medium temperature comprises:
calculating the average heat flow of the continuous casting blank by adopting an average heat flow calculation formula;
Wherein, the average heat flow calculation formula is:
Wherein q ave is the average heat flow of the continuous casting billet, q i is the heat flow of each calculation grid preset on the continuous casting billet, and n is the number of calculation grids;
According to the average heat flow of the continuous casting billet, a heat quantity calculation formula is led out of the first continuous casting billet, and the heat quantity led out of the continuous casting billet in a preset time step is calculated;
Wherein, the formula of heat calculation is derived to first continuous casting billet is:
Q＝qave·2(a+b)L·Δt；
Wherein Q is the heat of the continuous casting billet, Q ave is the average heat flow of the continuous casting billet, a and b are the section thickness and width of the continuous casting billet respectively, L is the fixed length of the continuous casting billet, and Deltat is the preset time step.
6. A quenching process design method according to claim 3, wherein calculating the heat derived from the continuous casting slab in a preset time step based on the heat flow of the continuous casting slab and the initial quenching medium temperature comprises:
according to the area of the calculation grid divided on the contact surface of the continuous casting blank and the quenching medium, a second continuous casting blank is adopted to derive a heat calculation formula, and the heat derived from the continuous casting blank in a preset time step is calculated; wherein, the second continuous casting billet heat-derived calculation formula is:
Wherein,
Q is the heat quantity of the continuous casting billet, Q i is the heat flow of each calculation grid preset on the continuous casting billet, deltaS i is the area of each calculation grid, deltat is the preset time step, L is the fixed length of the continuous casting billet, and n is the number of calculation grids.
7. The quenching process design method according to claim 1, wherein the calculation formula of the amount of heat absorbed by the quenching medium is:
Qw=q×η; wherein Qw is the part of heat which is extracted from the continuous casting billet and absorbed by the quenching medium, and eta is the preset effective coefficient.
8. The quenching process design method according to claim 1, wherein calculating the quenching medium temperature after the preset time step according to the heat absorbed by the quenching medium in the preset time step and the quenching medium temperature corresponding to the quenching medium after the end of the previous preset time step comprises:
calculating the temperature rise value of the quenching medium in the preset time step by adopting a quenching medium temperature rise calculation formula; wherein, the quenching medium temperature rise calculation formula is:
Δt=qw/(w×cp); wherein,
Delta T is an elevated value of the temperature of the quenching medium, qw is a part of heat which is derived from the continuous casting billet and absorbed by the quenching medium, W is the capacity of the quenching medium, and Cp is the specific heat of the quenching medium;
calculating the temperature of the quenching medium after the preset time step is finished through a quenching medium temperature calculation formula after the preset time step is finished; wherein,
The quenching medium temperature after the preset time step is finished is calculated according to the following formula:
Tw＝Tw1+△T；
wherein Tw is the quenching medium temperature after the end of the preset time step, tw1 is the quenching medium temperature corresponding to the beginning of the preset time step, and DeltaT is the temperature rise value of the quenching medium.
9. The quenching process design method as claimed in claim 1, wherein,
The quenching medium is water.
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| CN1128182A (en) * | 1994-01-10 | 1996-08-07 | 梯品斯股份有限公司 | Intermediate thickness twin slab caster and inline hot strip and plate line |
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