CN107052292A - It is a kind of that the Hot Charging of Continuous Casting Slab tracking and calculating method calculated is distributed based on thermal physical property parameter - Google Patents
It is a kind of that the Hot Charging of Continuous Casting Slab tracking and calculating method calculated is distributed based on thermal physical property parameter Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
Abstract
The invention provides a kind of Hot Charging of Continuous Casting Slab tracking and calculating method for being distributed and being calculated based on thermal physical property parameter, it is related to a kind of computational methods of online trace model, including acquisition thermal physical property parameter, strand are wide wide to solidified shell growth rhythm relation at diverse location to the solidified shell growth rhythm and strand at 1/2 position offline；Online heat tracking computation model is set up to comprise the following steps：Obtain and read in strand and initially cast condition and casting cycle information；Generate tracking cell；Choose thermal physical property parameter；Tracking cell, which is solved, to be calculated；Non-homogeneous solidification front is calculated；Judge tracking cell position.The computational methods that the present invention is provided are microcosmic and macroscopical unidirectional couplings, only consider influence of the thermal physical property parameter to macroscopical solidification and heat transfer, computational efficiency is substantially increased on the premise of computational accuracy is ensured, the shell thickness of calculating is 5% or so with measured value error, and the deviation of surface temperature value and measured value temperature can be controlled in ± 10 DEG C.
Description
Technical field
The present invention relates to a kind of computational methods of online trace model, and in particular to one kind is distributed meter based on thermal physical property parameter
The Hot Charging of Continuous Casting Slab tracking and calculating method of calculation.
Background technology
The soft reduction technique of continuous casting billet solidifying end and weight Reduction Technology are to be effectively improved center segregation of casting blank and center is dredged
The Main Means of loose problem, and the precondition implemented under slighter compress and weight is the Accurate Prediction to solidification end position.Mesh
It is anti-that the preceding method for being used for determining solidification end position is mainly included in the calculating of line heat-tracking model, method of powder actuated shot, solidification end pressure
Present detection method and at present electromagnetic acoustic detection method still under study for action.And most domestic enterprise locks into the condition limit of equipment
System, is typically employed in the calculating of line heat-tracking model to predict solidification position.
The accuracy that physical parameter in online heat-tracking model is calculated directly influences the accuracy of result of calculation even
The convergence of calculating process.Wherein physical parameter is mainly included：Phase fraction, thermal conductivity factor, specific heat capacity and density etc..It is general
Relational expression generally is varied with temperature using Clyne TW et al. solid rates proposed to the calculating of solid rate in line heat-tracking model：And thermal conductivity factor is generally reduced to fixed value, generally 33W/ (kg DEG C).Density is generally also
Fixed value is taken, i.e., 7000kg/m is taken in liquid phase region3, 7200kg/m is taken in two-phase section3, 7600kg/m is taken in solid phase area3。
Specific heat capacity is also generally chosen fixed value and calculated, solid phase specific heat CS=669.44J/ (kg DEG C), two-phase section specific heat Cm=
772J/ (kg DEG C) and liquid phase specific heat Cl=824.64J/ (kg DEG C) is calculated.Although the mode of this selection is simple real
With, and some parameters may have certain degree of accuracy, but can not correctly reflect the company that physical parameter is varied with temperature
Continuous property.
Some scholars, which propose, uses fully-coupled model, i.e., it is accurate that microcosmic solute segregation couples the method calculated with macroscopic view heat transfer
Temperature field is really calculated, the calculation procedure of fully-coupled model is as follows：
The first step：Cross section first using microtomy by strand along throwing direction is divided into unit grid, for whole
Section can combine boundary condition using the macroscopical solidification and heat transfer method of two dimension, and such as finite element method, finite difference method calculate casting
The solidification and heat transfer of base, in a calculating cycle, by macroscopical solidification and heat transfer model, can obtain temperature, cooling rate of each node etc.
Information；
Second step：In a calculating cycle, according to information such as the temperature of each node, cooling rates, to each node location
Microcosmic solute segregation calculating is carried out, solute segregation distribution and phase fraction at the node location is calculated, and according to phase fraction meter
Calculation obtains the thermal physical property parameter required for macroscopical solidification and heat transfer such as thermal conductivity factor, specific heat capacity, density；
3rd step：Bring each node thermal physical property parameter into next macroscopical solidification and heat transfer calculating cycle, i.e. step one, complete
Cycle calculations.
Because strand number of nodes is more, typically greater than 10000, therefore be required in each calculating cycle carrying out
The microcosmic solute segregation of more than 10000 times is calculated；On the other hand, in order to ensure that grand, micromodel is consistent in time scale
Property, general calculating cycle is all set to 0.01s, and the course of casting is typically greater than 30 minutes, therefore has been needed in whole casting course
Calculated into 180000 Macro-micro Couplings.Obviously, under so huge amount of calculation, it can not possibly realize in line computation.
Therefore, current online heat-tracking model：(1) it is most of to consider that thermal physical property parameter is calculated, even if examining
Thermal physical property parameter is considered, can not consider during casting blank solidification because carbon, silicon, manganese, phosphorus, element sulphur solute segregation are distributed different institutes
Caused physical parameter otherness；(2) the heat tracking on center line can only be considered in sheet billet continuous casting production process, it is impossible to predict
Strand it is wide to non-homogeneous coagulating property, i.e., the wide shell growth speed difference opposite sex to 1/2/ position, 1/4 position and 1/8 position.
In view of the foregoing, the invention provides a kind of it can be considered that causing hot physical property to be joined because solute segregation distribution is different
Number difference, and the online hot tracking and calculating method of the non-homogeneous solidification law of strand can be predicted.
The content of the invention
In order to overcome the shortcomings of that above-mentioned prior art is present, it is distributed and is calculated based on thermal physical property parameter the invention provides one kind
Hot Charging of Continuous Casting Slab tracking and calculating method.
To achieve these goals, the present invention provides following technical scheme：
It is a kind of that the Hot Charging of Continuous Casting Slab tracking and calculating method calculated is distributed based on thermal physical property parameter, including obtain off-line data and build
Vertical strand is wide to the online heat tracking computation model in 1/2 position；
Obtaining off-line data includes herein below：
The thermal physical property parameter of off-line calculation steel：Using steel under the conditions of the different element segregation degree of microcosmic SOLIDIFICATION MODEL calculating
Phase fraction, the thermal physical property parameter of steel is calculated based on the phase fraction, and the thermal physical property parameter includes thermal conductivity factor, density and specific heat
Hold, and the thermal physical property parameter is stored in database；
It is offline to obtain the wide solidified shell growth rhythm at 1/2 position of strand：Strand is obtained using gross segregation detection
The wide strand segregation regularity of distribution on through-thickness at 1/2 position, forms element in steel wide at 1/2 position in strand
The solidified shell growth rhythm of " slab thickness position-element segregation degree " is simultaneously stored in database；
Offline acquisition strand is wide to solidified shell growth rhythm relation at diverse location：According to two-dimentional macroscopical solidification and heat transfer with
Microcosmic solute segregation unity couping computation model obtain strand it is wide to 1/8 position, 1/4 position with it is wide to 1/2 position casting blank solidification base
Shell growth rhythm relation is simultaneously stored in database；
Set up strand wide to the online heat tracking computation model in 1/2 position, comprise the following steps：
Obtain and read in strand and initially cast condition and casting cycle information：Including strand size, composition of steel, pulling rate, mistake
Temperature, length of mould and amount of cooling water, crystallizer are imported and exported water temperature difference, two cold-zones and divided and the real-time water in each area；
Generate tracking cell：In a cycle, a new tracking cell, the tracking are generated in crystallizer meniscus position
The solidification and heat transfer computation interval of unit is the wide solidification and heat transfer to through-thickness on 1/2 position of strand, and single to the tracking
Member enters the initialization of trip temperature and position；
Specifically, generating tracking cell using microtomy, microtomy refers to divide whole strand streamline along throwing direction
For many tracking cell, it is believed that streamline is made up of the tracking cell of continuous " birth ".By " the base age " of tracking cell, initially
It is temperature, position, residing cooling zone, associated with the temperature field of unit by the primary condition such as water and process condition, so that with
Track unit and time correlation, dynamic is turned to from static state.Each tracking cell represents the temperature of a tangent plane on streamline throwing direction
Distribution, all tracking cell linkages get up can just describe a dynamic temperature field；
Choose thermal physical property parameter：In a tracking cell, initially cast condition and casting cycle of the strand is called to believe
Breath determines slab thickness position, and the corresponding element segregation degree of the thickness position is selected in database, and according to the element
Degree of segregation calls the corresponding thermal physical property parameter in the position of this in database；
Tracking cell, which is solved, to be calculated：In a cycle, the thermal physical property parameter is called, to casting since mold liquid level
All tracking cell in the wide whole strand length to 1/2 position of base complete a Temperature calculating；
Non-homogeneous solidification front is calculated：Grown and advised by the wide solidified shell at 1/2 position of the strand obtained
Rule and the strand it is wide to 1/8 position, 1/4 position with wide to 1/2 position casting blank solidification shell growth rule relation, acquisition strand
The wide solidified shell growth rhythm to 1/4 and 1/8 position；
Judge tracking cell position：It is total that the casting overall length recorded when being generated according to tracking cell subtracts the casting at current time
Long calculate obtains the position that tracking cell is reached within this cycle, and position is saved in the attribute of the tracking cell, root
Boundary condition is chosen according to the tracking cell position, while judge last tracking cell position, if last
The position of tracking cell exceedes casting machine length, that is, thinks that it removes air cooling zone, all properties of this tracking cell are eliminated, deleted
Except tracking cell, otherwise continue next computation of Period.
Preferably, the gross segregation detection uses in-situ study or drilling cuttings sampling analysis method.
Preferably, set up One-dimensional On-line heat tracking computation model and carry out the Temperature calculating, for each Suo Shu with
Track unit carries out solidification and heat transfer calculating, and its governing equation is：
In formula, L is latent heat of solidification coefficient, and value is 2.72 × 105J/kg, ρ are the density of steel；C is the specific heat capacity of steel；k
For the thermal conductivity factor of steel；T is the node temperature of steel；fsFor the solid phase fraction of steel.
What the present invention was provided, which is distributed the beneficial effect calculated based on thermal physical property parameter, is：Apply the present invention to dynamic draught
In system, the more accurate Temperature Distribution of press down system and curdled appearance can be supplied to.So dynamic draught system can be with
Complete dynamic pressure process by accurate curdled appearance, and can specify rational two cold by accurate Temperature Distribution
Area's cooling system.The shell thickness that the present invention is calculated is 5% or so, the surface temperature value and measured value of calculating with measured value error
The deviation of temperature can be controlled in ± 10 DEG C.
The method that the present invention is provided calculates more quick, convenient, is mainly reflected in following three points：
(1) this method is microcosmic and macroscopical unidirectional couplings, i.e., only consider shadow of the thermal physical property parameter to macroscopical solidification and heat transfer
Ring, therefore grand, micromodel time unification need not be considered, time step 5s can be set, has broken time step 0.01s pact
Beam；
(2) this method establishes one-dimensional macroscopic solidification and heat transfer computation model, and nodes reduce two quantity than Two-Dimensional Heat
Level；
(3) thermal physical property parameter is stored in database by this method, is combined in macroscopical solidification and heat transfer calculating process and is calculated position
The element segregation situation put directly invokes corresponding thermal physical property parameter, and the micromodel calculating for eliminating magnanimity derives hot physical property again
The time of parameter.
The computational methods of the present invention can take into full account that strand diverse location physical property is joined compared with conventional heat tracking computation model
Several otherness, so as to more accurately describe casting blank solidification process.
Brief description of the drawings
Fig. 1 is microcosmic SOLIDIFICATION MODEL schematic diagram of the invention；
Fig. 2 Q345b steel solidifies phase transformation figure；
Fig. 3 is online heat-tracking model schematic flow sheet；
Influence of Fig. 4 carbons to model：(a) specific heat capacity, (b) thermal conductivity factor, (c) density (d) shell growth rule；
Fig. 5 is the shell thickness change feelings for the diverse location that heat-tracking model of the present invention is calculated with traditional heat-tracking model
Condition；
Fig. 6 is in-situ study sample position；
Fig. 7 is the two-dimensional distribution of carbon element content；
Fig. 8 is the two-dimensional distribution of phosphorus element content；
Fig. 9 is the two-dimensional distribution of sulfur content.
Embodiment
Below in conjunction with the accompanying drawings, the embodiment to the present invention is further described.Following examples are only used for more
Technical scheme is clearly demonstrated, and can not be limited the scope of the invention with this.
Embodiment 1
The invention provides a kind of Hot Charging of Continuous Casting Slab tracking and calculating method for being distributed and being calculated based on thermal physical property parameter, including obtain
Off-line data and to set up strand wide to 1/2 position (strand is wide to center) online heat tracking computation model；
Obtaining off-line data includes herein below：
(1) thermal physical property parameter of off-line calculation steel：Under the conditions of the different element segregation degree of microcosmic SOLIDIFICATION MODEL calculating
The phase fraction of steel, the thermal physical property parameter of steel is calculated based on phase fraction, and thermal physical property parameter includes thermal conductivity factor, density and specific heat capacity,
And thermal physical property parameter is stored in database, circular is as follows：
Step one：Microcosmic SOLIDIFICATION MODEL is set up based on regular hexagon dendrite cross section, steel grade is calculated in process of setting
In each phase fraction, governing equation is as follows：
In formula,For solute concentrations of the element i in solid phase, %；T is time, s；It is solute element i in solid phase
In diffusion coefficient, m2/s；
Steel grade each phase fraction in process of setting is calculated by microcosmic SOLIDIFICATION MODEL, i.e., calculates the liquid of steel grade respectively
Phase fraction fl, solid phase fraction fs, ferrite phase fraction fa, solid solution phase fraction fδWith austenite phase fraction fγ；
Step 2：Each phase fraction of the steel grade obtained using step 1 in process of setting, calculates the physical property ginseng of steel grade
Number, including thermal conductivity factor, density and specific heat capacity, formula are as follows：
K=(1-fl)ks+(1+m)flkl (2)
kl=35 (W/Km) (3)
In formula：K is the thermal conductivity factor of steel, W/Km；ksAnd klRespectively the convection conduct heat coefficient of steel grade and liquid phase heat conduction system
Number, flFor the liquid phase fraction of steel grade, m is empirical, and value is 4；TlFor the liquidus temperature of steel grade, T is the node temperature of steel grade
Degree, wc、wSi、wMnCarbon content, silicone content and manganese content respectively in steel grade, %；
C=Cafa+Cδfδ+Cγfγ+Clfl (5)
Cδ=441.3942+0.17744236T (7)
Cγ=429.8495+0.01497T (8)
Cl=842.6157 (9)
In formula：C is the specific heat capacity of steel grade, J/ (kg DEG C)；Cl、Ca、CδAnd CγThe respectively liquid phase of steel grade, ferrite, solid
The specific heat of solution and austenite, J/ (kg DEG C)；fl、fa、fδAnd fγThe respectively liquid phase of steel grade, ferrite, solid solution and Ovshinsky
Body phase fraction；
ρ=ρlfl+ρδfδ+ργfγ (10)
ρl=7100-73wc-(0.8-0.09wc)(T-1550)(13)
In formula：ρ is the density of steel grade, kg/m3；wcFor the carbon content in steel grade, %；ρl、ρδAnd ργThe respectively liquid of steel grade
The density of phase, solid solution phase and austenite phase, kg/m3；
(2) it is offline to obtain the wide solidified shell growth rhythm at 1/2 position of strand：Casting is obtained using gross segregation detection
The wide strand segregation regularity of distribution on through-thickness at 1/2 position of base, forms element in steel wide at 1/2 position in strand
The solidified shell growth rhythm of " slab thickness position-element segregation degree " is simultaneously stored in database, in the present embodiment, macroscopic view
Segregation detection uses in-situ study method；
Specifically, the wide solute segregation on 1/2 thickness of strand is determined using in-situ study method, and will " slab thickness position
Put-element segregation degree " relation stores to database to call.Fig. 6 is in-situ study sample position, and Fig. 7 to Fig. 9 is respectively
Carbon, phosphorus, the in-situ study testing result of element sulphur.
(3) need offline acquisition strand wide to solidified shell growth rhythm relation at diverse location for sheet billet continuous casting：Root
It is wide to 1/8 position, 1/4 position and width that strand is obtained according to the macroscopical solidification and heat transfer of two dimension and microcosmic solute segregation unity couping computation model
To 1/2 position casting blank solidification shell growth rule relation and it is stored in database, figure e give Q345b steel, and pulling rate is
The solidification process of diverse location under the conditions of 0.83m/min pulling rates.
Solidification change relational expression using the wide position of face 1/8 of MATLAB software regression fits and Kuan Mian centers is as follows：
a1=1.324e+19
B1=34.58
C1=1.843
A2=2.405e+04
B2=69.19
C2=16.51
In formula：δ1/8、δcenterThe shell thickness of 1/8 position and strand center, mm are represented respectively；X is represented away from bent moon
The value in face, a1, a2, b1, b2, c1 and c2 are the coefficient values that fitting is obtained, and relational expression is stored in database to adjust in line computation
With.
The above-mentioned data storage obtained offline is stayed in when line computation needs and directly transferred in database.
As shown in figure 3, setting up, strand is wide to be comprised the following steps to the online heat tracking computation model in 1/2 position：
Step 1：Obtain and read in strand and initially cast condition and casting cycle information：Including strand size, composition of steel, drawing
Speed, the degree of superheat, length of mould and amount of cooling water, crystallizer are imported and exported water temperature difference, two cold-zones and divided and the real-time water in each area；
Step 2：Generate tracking cell：In a cycle, a new tracking cell is generated in crystallizer meniscus position,
The solidification and heat transfer computation interval of the tracking cell is the wide solidification and heat transfer to through-thickness on 1/2 position of strand, and to tracking
Unit enters the initialization of trip temperature and position, and initialization flow is as follows：
Set up the primary condition and boundary condition of online heat-tracking model：
(3-1) primary condition
T0=Ttundish (14)
In formula：T0For node initial temperature, DEG C；TtundishFor pouring temperature, DEG C；
(3-2) boundary condition
The boundary condition at strand center, according to the symmetry of Slab Heat, the distribution of section temperature is distributed with Central Symmetry,
I.e.：
The boundary condition of casting billet surface：
In formula：qn、qwIt is the heat flux by casting billet surface leptoprosopy and wide face, W/m respectively2；X and Y are respectively that cross section is narrow
Side and the overall length of broadside, m, k is thermal conductivity factor, W/Km；
(a) boundary condition of crystallizer
Heat transfer boundary condition of the strand in crystallizer is set as：
In formula：Q is the heat flow density of crystallizer, MW/m2, A and B are the undetermined coefficient of crystallizer；Z is strand apart from bent moon
The distance in face, m；
(b) boundary condition of two cold-zones
The heat that strand and support roller thermal contact conductance are passed out, is handled, two is cold using the method for increase convection coefficient
The equivalent heat flow density formula in area is as follows：
Q=hw(Ts-Tw)+σε[(Ts+273.15)4-(Tw+273.15)4] (20)
hw=[1570W0.55(1-0.0075Tw)]/Cm (21)
In formula：hwFor comprehensive convection transfer rate, W/ (m DEG C)；T is the surface temperature of strand, DEG C, TsFor solidus temperature
Degree, DEG C；TwFor cooling water or environment temperature, DEG C；σ is Boltzmann constant 5.67 × 10-8W/(m2·K4)；ε is casting billet surface
Blackness, it is jet density, L/ (m generally to take 0.8, W2S), CmFor empirical coefficient, value is 4.4；
(c) boundary condition of air cooling zone
Continuous casting enters mainly being radiated by way of casting billet surface radiant heat transfer in air cooling zone, and heat flow density formula is such as
Under：
Q=σ ε [(Ts+273.15)4-(Tw+273.15)4] (22)
In formula, σ is Boltzmann constant 5.67 × 10-8W/(m2·K4), ε is the blackness of casting billet surface, generally takes 0.8, Tw
For cooling water or environment temperature；
Step 3：Choose thermal physical property parameter：In a tracking cell, strand is called initially to cast condition and casting cycle
Information determines slab thickness position, and the corresponding element segregation degree of the thickness position is selected in database, and inclined according to element
Analysis degree calls the corresponding thermal physical property parameter in the position of this in database；
Step 4：Tracking cell, which is solved, to be calculated：In a cycle, above-mentioned thermal physical property parameter is called, is opened from mold liquid level
All tracking cell in the whole strand length to 1/2 position wide to strand that begins complete a Temperature calculating, specific to calculate
Method is as follows；
Set up One-dimensional On-line heat tracking computation model and carry out Temperature calculating, solidification biography is carried out for each tracking cell
Heat is calculated, and its governing equation is：
In formula, L is latent heat of solidification coefficient, and value is 2.72 × 105J/kg, ρ are the density of steel, kg/m3；C is the specific heat of steel
Hold, J/ (kg DEG C)；K is the thermal conductivity factor of steel, W/Km；T is the node temperature of steel, DEG C；fsFor the solid phase fraction of steel；
Step 5：It is wide wide to the solidified shell growth rhythm and above-mentioned strand at 1/2 position by the strand obtained
To 1/8 position, 1/4 position, to 1/2 position casting blank solidification shell growth rule relation, strand is obtained with wide wide to 1/4 and 1/8
The solidified shell growth rhythm put；
Step 6：Judge tracking cell position：The casting overall length recorded when being generated according to tracking cell subtracts current time
Casting overall length, which is calculated, obtains the position that tracking cell is reached within this cycle, and position is saved in the attribute of the tracking cell
In, boundary condition is chosen according to above-mentioned tracking cell position, while last tracking cell position is judged, if finally
The position of one tracking cell exceedes casting machine length, that is, thinks that it removes air cooling zone, all properties of this tracking cell are disappeared
Remove, delete tracking cell, otherwise continue next computation of Period.
1 to Fig. 5 the flow of the online heat-tracking model based on thermal physical property parameter is carried out specifically below in conjunction with the accompanying drawings
It is bright：
The Interface Moving master that micromodel in the calculating of physical parameter, Fig. 1 is completed by the micromodel in Fig. 1 and Fig. 2
If being calculated using Current Temperatures and interface and obtaining TlWithTemperature is contrasted and determined, TlWithSteel is represented respectively
δ/γ phase in version start temperature in liquidus temperature and process of setting, is often accomplished by carrying out once by a time step Δ t
The deterministic process of Interface Moving.In δ/l and γ/l interfaces, the T calculated when liquid phaselTemperature is less than Current Temperatures, will be from liquid phase
Separate out δ or γ phases.Simultaneously at δ/γ interfaces, calculated when δ phases nodeTemperature is higher than Current Temperatures, will be separated out from δ phases
γ phases.The δ phases that model hypothesis are separated out first in process of setting, though this hypothesis does not meet the error of actual only very little,
When C content is higher,Higher than actual temperature, after first δ phase is produced, it can change at once in next time step Δ t
For γ phases.Microcosmic SOLIDIFICATION MODEL will not only complete the movement to interface in each time step, in addition it is also necessary to according to nonmetallic folder
The balanced reaction equation of debris production is come the precipitation that judges and calculate non-metallic inclusion.Thermal physical property parameter computing module is main
It is to calculate phase composition, then completes by phase composition, temperature and solute concentration that thermal conductivity factor, specific heat capacity and density are calculated and deposited
Storage, is the physical parameter value such as the corresponding solid rate of this composition of steel, thermal conductivity factor under Current Temperatures.
It has been saved in from figure 3, it can be seen that calculating obtained physical parameter in database.Within each cycle, generation
One new tracking cell, and enter the initialization of the attributes such as trip temperature and position to new tracking cell.In a cycle, from
Mold liquid level starts to complete a Temperature calculating to all tracking cell in whole strand length.Boundary condition is basis
The location of unit calculates to choose the cooling parameter of relevant position, and physical parameter is to be read from database according to temperature
Take corresponding physical parameter.And the Temperature Distribution and setting condition of unit are saved in the attribute array of tracking cell.Calculate
The position that each unit is reached within this cycle, and position is saved in the attribute of tracking cell, while to last list
Member is judged, if the position of last unit removes air cooling zone, all properties of this tracking cell is eliminated, deleted
Except tracking cell.Online heat-tracking model calculates obtained result and passes to dynamic draught Controlling model and dynamic in process of production
State Control Model to Secondary Cooling, the two models further according to the data of Temperature Distribution and curdled appearance calculate and completed to pressure and two
The control operation of cold-zone.
Fig. 4 compares the otherness of thermal physical property parameter and corresponding solidification under the conditions of different carbon contents by taking carbon as an example
The otherness of shell growth rule.If Fig. 4 (a)-(c) is as can be seen that when carbon content changes, the specific heat capacity of strand, lead
Hot coefficient, density are differed, therefore casting blank shell growth rhythm is also differed as shown in Fig. 4 (d).In view of in casting process
Concrete condition be divided into 6 different zones from inner arcuate surface to strand center, it is true according to the element segregation average value in six regions
Its fixed corresponding thermal physical property parameter, and bring into the calculating of online heat-tracking model.
Fig. 5 is the shell thickness change feelings for the diverse location that heat-tracking model of the present invention is calculated with traditional heat-tracking model
Condition, in figure, the shell thickness that model of the present invention is calculated at 20.5m positions is 116mm, using traditional heat-tracking model in this position
The shell thickness for putting calculating is 129mm, and shoot-pin test result is 119mm, and the error of model of the present invention is 2.5%, and traditional mould
The error of type is 4.4%, it can be seen that this model calculating accuracy is more preferable.
Embodiment described above is only the present invention preferably embodiment, protection scope of the present invention not limited to this,
Any those skilled in the art in the technical scope of present disclosure, the technical scheme that can be become apparent to
Simple change or equivalence replacement, belong to protection scope of the present invention.
Claims (3)
1. it is a kind of based on thermal physical property parameter be distributed calculate Hot Charging of Continuous Casting Slab tracking and calculating method, it is characterised in that including obtain from
Line number evidence and to set up strand wide to the online heat tracking computation model in 1/2 position；
Obtaining off-line data includes herein below：
The thermal physical property parameter of off-line calculation steel：The phase point of steel under the conditions of different element segregation degree is calculated using microcosmic SOLIDIFICATION MODEL
Rate, the thermal physical property parameter of steel is calculated based on the phase fraction, and the thermal physical property parameter includes thermal conductivity factor, density and specific heat capacity,
And the thermal physical property parameter is stored in database；
It is offline to obtain the wide solidified shell growth rhythm at 1/2 position of strand：Using gross segregation detection obtain strand it is wide to
The strand segregation regularity of distribution at 1/2 position on through-thickness, forms element in steel wide to " strand at 1/2 position in strand
The solidified shell growth rhythm of thickness position-element segregation degree " is simultaneously stored in database；
Offline acquisition strand is wide to solidified shell growth rhythm relation at diverse location：According to two-dimentional macroscopical solidification and heat transfer with it is microcosmic
Solute segregation unity couping computation model acquisition strand is wide to give birth to 1/8 position, 1/4 position with wide to 1/2 position casting blank solidification green shell
Long rule relation is simultaneously stored in database；
Set up strand wide to the online heat tracking computation model in 1/2 position, comprise the following steps：
Obtain and read in strand and initially cast condition and casting cycle information：Including strand size, composition of steel, pulling rate, the degree of superheat,
Length of mould and amount of cooling water, crystallizer are imported and exported water temperature difference, two cold-zones and divided and the real-time water in each area；
Generate tracking cell：In a cycle, a new tracking cell, the tracking cell are generated in crystallizer meniscus position
Solidification and heat transfer computation interval be the wide solidification and heat transfer to through-thickness on 1/2 position of strand, and the tracking cell is entered
Trip temperature and the initialization of position；
Choose thermal physical property parameter：In a tracking cell, call the strand initially cast condition and casting cycle information it is true
Determine slab thickness position, the corresponding element segregation degree of the thickness position is selected in database, and according to the element segregation
Degree calls the corresponding thermal physical property parameter in the position of this in database；
Tracking cell, which is solved, to be calculated：In a cycle, the thermal physical property parameter is called, it is wide to strand since mold liquid level
All tracking cell into the whole strand length of 1/2 position complete a Temperature calculating；
Non-homogeneous solidification front is calculated：By the wide solidified shell growth rhythm at 1/2 position of the strand obtained and
The strand it is wide to 1/8 position, 1/4 position with wide to 1/2 position casting blank solidification shell growth rule relation, obtain strand it is wide to
The solidified shell growth rhythm of 1/4 and 1/8 position；
Judge tracking cell position：The casting overall length recorded when being generated according to tracking cell subtracts the casting overall length meter at current time
Calculation obtains the position that tracking cell is reached within this cycle, and position is saved in the attribute of the tracking cell, according to institute
State tracking cell position and choose boundary condition, while last tracking cell position is judged, if last is tracked
The position of unit exceedes casting machine length, that is, thinks that its removes air cooling zone, all properties of this tracking cell are eliminated, delete with
Track unit, otherwise continues next computation of Period.
2. according to claim 1 be distributed the Hot Charging of Continuous Casting Slab tracking and calculating method calculated, its feature based on thermal physical property parameter
It is, the gross segregation detection uses in-situ study or drilling cuttings sampling analysis method.
3. according to claim 1 be distributed the Hot Charging of Continuous Casting Slab tracking and calculating method calculated, its feature based on thermal physical property parameter
It is, sets up One-dimensional On-line heat tracking computation model and carry out the Temperature calculating, carried out for tracking cell each described
Solidification and heat transfer is calculated, and its governing equation is：
<mrow>
<mi>&rho;</mi>
<mi>c</mi>
<mfrac>
<mrow>
<mo>&part;</mo>
<mi>T</mi>
</mrow>
<mrow>
<mo>&part;</mo>
<mi>t</mi>
</mrow>
</mfrac>
<mo>=</mo>
<mfrac>
<mo>&part;</mo>
<mrow>
<mo>&part;</mo>
<mi>x</mi>
</mrow>
</mfrac>
<mrow>
<mo>(</mo>
<mi>k</mi>
<mfrac>
<mrow>
<mo>&part;</mo>
<mi>T</mi>
</mrow>
<mrow>
<mo>&part;</mo>
<mi>x</mi>
</mrow>
</mfrac>
<mo>)</mo>
</mrow>
<mo>+</mo>
<mi>&rho;</mi>
<mi>L</mi>
<mfrac>
<mrow>
<mo>&part;</mo>
<msub>
<mi>f</mi>
<mi>s</mi>
</msub>
</mrow>
<mrow>
<mo>&part;</mo>
<mi>t</mi>
</mrow>
</mfrac>
</mrow>
In formula, L is latent heat of solidification coefficient, and value is 2.72 × 105J/kg, ρ are the density of steel；C is the specific heat capacity of steel；K is steel
Thermal conductivity factor；T is the node temperature of steel；fsFor the solid phase fraction of steel.
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Application publication date: 20170818 Assignee: MCC SOUTHERN CONTINUOUS CASTING TECHNOLOGY ENGINEERING Co.,Ltd. Assignor: Northeastern University Contract record no.: X2020210000038 Denomination of invention: A calculation method of continuous casting slab heat tracing based on distribution calculation of thermophysical parameters Granted publication date: 20190326 License type: Common License Record date: 20201223 |