CN107876718A - For simulating the experimental provision and experimental method of special heavy plate slow-set - Google Patents
For simulating the experimental provision and experimental method of special heavy plate slow-set Download PDFInfo
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- CN107876718A CN107876718A CN201711153267.4A CN201711153267A CN107876718A CN 107876718 A CN107876718 A CN 107876718A CN 201711153267 A CN201711153267 A CN 201711153267A CN 107876718 A CN107876718 A CN 107876718A
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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
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/124—Accessories for subsequent treating or working cast stock in situ for cooling
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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
- B22D11/22—Controlling or regulating processes or operations for cooling cast stock or mould
- B22D11/225—Controlling or regulating processes or operations for cooling cast stock or mould for secondary cooling
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Abstract
The invention belongs to steel-making continuous casting technical field, more particularly, to a kind of experimental provision and method for being used to simulate special heavy plate slow-set, experimental provision is characterized in that including crystallizer, assemble the thermocouple on this crystallizer, the collector being connected with this thermocouple, the water injector of two cold-zones is arranged on, this water injector includes pressing linearly aligned nozzle, the water knockout drum being connected with this nozzle, the flow controller being connected with this water knockout drum.The present invention realizes the slow-set of molten steel in a crystallizer using static die casting method, after molten steel forms certain thickness initial solidification shell, utilize its detachability, on the relatively low green shell surface being exposed in air of temperature weak water spray is carried out with nozzle, the process of continuous casting special heavy plate slow-set is simulated by slowing down freezing rate stage by stage, the reason for studying the Microstructural evolution of extra-thick plate blank slow-set in casting process, and analyzing the distribution situation of field trash and produce various defects.
Description
Technical field
The invention belongs to steel-making continuous casting technical field, more particularly, to a kind of experiment for being used to simulate special heavy plate slow-set
Device and experimental method.
Background technology
As nuclear power engineering steel, military project ship steel, low welding crack sensibility high-strength steel, special pressure container are used
Steel etc. develops rapidly, and the demand size of heavy slab is increasing.At present, the special thick continuous casting steel billet production technology more than 400mm
Worldwide increasingly it is taken seriously, many enterprises start the life of special thick continuous casting steel billet by technological transformation or new upper casting machine
Production.
Because section is thicker in special thick strand casting process, pulling rate is relatively low, and weak cold mode is taken in two cold-zones, causes special thickness
The plate casting blank solidification time is longer, and its freezing rate is relatively low.Slow-set causes the flowing of interdendritic remnants molten steel to tend to balance stream
Dynamic state, the C, S, the more conventional thick strand of the segregation of P element in strand are serious, and the internal flaw such as loose, shrinkage cavity is also tighter
Weight.
At present, the report in terms of the rarely found thick strand internal flaw control technology about spy, for special thick strand continuous casting skill
Art such as soft reduction technique, solidification end electromagnetic agitating technology, roller row arrange that anti-bulge technology is badly in need of being researched and developed, and close
In special heavy plate solidified structure development law, the segregation and distribution of element, the machine such as the behavior of process of setting precipitate and " cold " meniscus
Reason studies rare report.Certain experiment hand is especially more the absence of in terms of the researchs such as special heavy plate slow-set Thermal-state test
Section.
The content of the invention
It is used to simulate the experimental provision and experimental method of special heavy plate slow-set it is an object of the invention to provide a kind of, can be with
The process of simulation special heavy plate slow-set is realized, to study the Microstructural evolution of extra-thick plate blank slow-set in casting process,
And analyze the distribution situation of field trash and provide a kind of laboratory facilities the reason for producing various defects.
The purpose of the present invention is realized by following technical proposals：
The experimental provision for being used to simulate special heavy plate slow-set of the present invention, it is characterised in that including crystallizer, be assemblied in
Thermocouple on this crystallizer, the collector being connected with this thermocouple, it is arranged on the water injectors of two cold-zones, this water injector
Including by linearly aligned nozzle, the water knockout drum being connected with this nozzle, the flow controller being connected with this water knockout drum.
Described crystallizer includes being arranged on the reeded bottom plate of band of bottom, set in this groove by four pieces of fire resistings
The crystallizer cavity that material crystalline wall is formed and fixed by two pairs of detachable steel bars, the depth of groove of the bottom plate is 2mm-
3mm, one layer of refractory masses I is equipped with below described bottom plate.
Described thermocouple is arranged on refractory material crystallizer wall, is in the A faces thermocouple of refractory material crystallizer wall
Axial symmetry is arranged, and A faces thermocouple line space is 80mm-100mm, bottom a line thermocouple apart from bottom 100mm-120mm, in
Between a row thermocouple be arranged on the symmetry axis in A faces, the row thermocouple of both sides two is apart from border 15mm-20mm, in refractory material knot
The arrangement of the B faces thermocouple of brilliant wall is identical with A faces.
Described refractory masses I thickness is 20mm-30mm, particle≤0.088mm of refractory material.
Described crystallizer cavity cavity is that a length-width ratio is (2-3): 1 cuboid.
The refractory material of the refractory material crystallizer wall need to meet α m/ α p=(1/128-1/16) and refractoriness is more than
Under the conditions of 1400 DEG C, wherein α=λ/(ρ Cp).
The fire resisting material particle level proportioning of the refractory material crystallizer wall accounts for 25%-35%, 2mm- for 2.5mm-2mm
1mm's accounts for 30%-35%, accounting for 35%-40% or account for 30%-35% less than 0.088mm.
Described nozzle projected area is 50mm-60mm, and arrangement spacing is 40mm-50mm, distance casting blank identity distance from for
60mm-80mm。
A kind of experimental method for utilizing the experimental provision for simulating special heavy plate slow-set, it is characterised in that include reality
It is as follows to test step：
Step 1：The determination of crystallizer material
Meeting α=(2.676-21.41) × 10-7And refractoriness is more than under the conditions of 1400 DEG C, wherein α=λ/(ρ Cp),
λ represents the thermal conductivity factor of material, and unit W/ (m. DEG C), ρ represent the density of material, units/kg/m3, Cp represents the specific heat of material
Hold, unit J/ (kg. DEG C), can be as the material for making the crystallizer；Such as：Magnesian maximum permissible temperature is 1600
DEG C -1700 DEG C, α=6.857 × 10-7, meet above-mentioned condition, can be as the material for making slow-set crystallizer；Clay material
Maximum permissible temperature is 1350 DEG C -1450 DEG C, α=3.287 × 10-7Meet above-mentioned condition, can be used as and make slow-set crystallization
The material of device；
Step 2：The determination of crystallizer size
Other sizes of crystallizer can according to 4: 1 the likelihood ratio by special heavy plate crystallizer in actual production Size calculation
, and crystallizer wall thickness then foundationUnit：Mm, wherein：λ1Represent Refractory Thermal Conductivity,
Unit (W/ (m. DEG C))；λ2Ormolu thermal conductivity factor is represented as 109, unit (W/ (m. DEG C))；K represents correction factor, and d is represented
Refractory material crystallizer wall thickness, unit mm；d1Safe thickness is represented, generally takes 10mm；d2Represent during use plus
Work amount, typically takes 10mm~15mm.Work as λ1Difference ∈ (0,0.5], (and 0.5,1], (1,1.5], (1.5,2], (2,2.5],
(2.5,3], (3,3.5], (3.5,4], (4,4.5], (4.5,5] } when, k take respectively 400,150,90,65,50,40,35,30,
25,20 }；Such as：When taking magnesia refractories, its thermal conductivity factor λ 1 is 2.1W/ (m. DEG C), therefore magnesia crystallizer wall thickness takes
41mm-47mm；When taking high alumina clay refractory material, its thermal conductivity factor λ1For 0.77W/ (m. DEG C), therefore high alumina clay crystallizer
Wall thickness can be taken as 44mm--50mm；
Step 3：Primary crystallization
Crystallizer is produced according to identified material and size in step 1 and step 2, requires to coordinate according to specific experiment
Induction furnace is poured into a mould；When casting complete starts timing, the time can be byIt is determined that unit min, this when
Between be casting complete after arrive form removal period；Wherein：ε represents correction factor, as crystallizer wall thermal conductivity factor λ (unit (W/
(m. DEG C))) respectively ∈ (0,1], (and 1,3], (3,5], (5,10] } when, ε take respectively 6.2 × 104,5.3 × 104,4.8 ×
104,4.6 × 104 }；E represents initial solidification shell thickness, generally takes 10mm-15mm；C, which represents solidified shell and influenceed by the degree of superheat, is
Number, generally takes 5mm-10mm；Lf represents the latent heat of solidification of steel, and No. 45 steel are 271.7kJ/Kg；ρ represents the density of steel, 7200kg/
m3；λ m represent the thermal conductivity factor of solidified shell, and No. 45 steel are 50.2W/ (m.k)；TSRepresent the solidus temperature of steel, No. 45 steel solid phases
Line is 1337 DEG C；T0Represent the surface temperature of steel billet, 727 DEG C；When taking magnesia refractories, its thermal conductivity factor λ1For 2.1W/
(m. DEG C), therefore the magnesia crystallizer wall dismounting time is 39min-49min；When taking high alumina clay refractory material, its thermal conductivity factor
λ1For 0.77W/ (m. DEG C), therefore it is 47min-57min that high alumina clay crystallizer wall, which removes the time,；Material crystallizer is corresponded to when reaching
Striking time, carry out form removal in next step prepare；Thermocouple collecting temperature variable signal is used within this time, in form removal
When stop temperature acquisition；
Step 4：Secondary cooling
Secondary cooling needs to calculate cooling water volume, can foundationUnit L, wherein：κ is amendment system
Number, value 4.9；A is certain value, value 573.93kJ/kg；M be crystallizer in molten steel quality, units/kg；ρ2For water
Density, value 1000kg/m3；T0The initial temperature of water is represented, takes 25 DEG C；T is water temperature, takes 100 DEG C；C represents water
Specific heat capacity, value are 4.2kJ/ (kg. DEG C)；When quality of molten steel is 100kg-150kg, cooling water volume 595.203L- can obtain
742.805L；Sprayed water using shower nozzle, while A the and B faces of strand are sprayed water using Combined nozzle；The cold-zone of weak cold two is divided to two
The individual stage：First stage injection flow rate is 30L/min-40L/min, time 8min-14min；Second stage injection flow rate is 20L/
Min-30L/min, time 8min-12min；
Step 5：Sampling analysis
Two cold finish treat that casting blank surface temperature is reduced to room temperature (25 DEG C) and can sampled；To being cut completely in the middle part of solidification strand
Piece samples, and by Metallographic Analysis, confirms that slow-set expands Center Equiaxial Crystal area to special heavy plate continuous casting billet, reduces center field trash
Quantity and change tissue growth effect；Study the Microstructural evolution of special heavy plate slow-set, the crystallization of unlike material
Device and weak cold intensity can be that optimization special heavy plate continuous casting process carries to extra-thick plate blank center porosity, the influence of segregation crack
For rational reference proposition；It is determined that being best suitable for the non-metallic material of the crystallizer of molten steel slow-set, slow-set shape is understood
The development law of state undertissue, extra-thick plate blank internal flaw is reduced or eliminated, improve the quality of special heavy plate continuous casting billet.
Advantages of the present invention：
, can be with slow-set by the experimental provision and experimental method that are used to simulate special heavy plate slow-set of the present invention
The mechanical characteristic of special heavy plate continuous casting billet macroscopic view and it is microcosmic organize the formation of rule, enrich high temperature strand, particularly special heavy plate and connect
The rheological theory and Microstructure Evolvement of solid-liquid two-phase section during strand slow-set, it is slow to carry out laboratory special heavy plate
The solid Thermal-state test of rapid hardening is laid a good foundation；Simultaneously for research special heavy plate slow-set under the conditions of solute element distribution situation and
The specific origin cause of formation of internal soundness defect provides enforceable means, therefore has important practical significance.
Brief description of the drawings
Fig. 1 is the structural representation of experimental provision of the present invention.
Fig. 2 is the layout viewing of two cold-zone nozzles of the invention.
Embodiment
The embodiment of the present invention is further illustrated below in conjunction with the accompanying drawings.
As shown in Figure 1, 2, the experimental provision for being used to simulate special heavy plate slow-set of the invention, it is characterised in that including knot
Brilliant device, the thermocouple 2 on this crystallizer is assembled, the collector being connected with this thermocouple 2, the water spray for being arranged on two cold-zones fills
Put, this water injector includes pressing linearly aligned nozzle 7, the water knockout drum being connected with this nozzle 7, is connected with this water knockout drum
Flow controller.
Described crystallizer includes the reeded bottom plate 1 of band for being arranged on bottom, sets resistance to by four pieces in this groove
The crystallizer cavity that fiery material crystalline wall 5 is formed and fixed by two pairs of detachable steel bars 3, the depth of groove of the bottom plate 1 are
2mm-3mm, described bottom plate 1 are equipped with one layer of refractory masses I below.
Described thermocouple 2 is arranged on refractory material crystallizer wall 5, in the thermoelectricity of A faces 4 of refractory material crystallizer wall 5
Even 2 axisymmetricly arrange, and the line space of 4 thermocouple of A faces 2 is 80mm-100mm, and bottom a line thermocouple 2 is apart from bottom 100mm-
120mm, a middle row thermocouple 2 are arranged on the symmetry axis in A faces 4, the row thermocouple 2 of both sides two apart from border 15mm-20mm,
The arrangement of the thermocouple 2 of B faces 6 of refractory material crystallizer wall 5 is identical with A faces 4.
Described refractory masses I thickness is 20mm-30mm, particle≤0.088mm of refractory material.
Described crystallizer cavity cavity is that a length-width ratio is (2-3): 1 cuboid.
The refractory material of the refractory material crystallizer wall need to meet α m/ α ρ=(1/128-1/16) and refractoriness is more than
Under the conditions of 1400 DEG C, wherein α=λ/(ρ Cp).
The fire resisting material particle level proportioning of the refractory material crystallizer wall accounts for 25-35%, 2mm- for 2.5mm-2mm
1mm's accounts for 30-35%, accounting for 35-40% or account for 30-35% less than 0.088mm.
The described projected area of nozzle 7 is 50mm-60mm, and arrangement spacing is 40mm-50mm, distance casting blank identity distance from for
60mm-80mm。
A kind of experimental method for utilizing the experimental provision for simulating special heavy plate slow-set, it is characterised in that include reality
It is as follows to test step：
Step 1：The determination of crystallizer material
Meeting α=(2.676-21.41) × 10-7And refractoriness is more than under the conditions of 1400 DEG C, wherein
α=λ/(ρ Cp), λ represent the thermal conductivity factor of material, and unit W/ (m. DEG C), ρ represent the density of material, and units/kg/
m3, Cp represents the specific heat capacity of material, and unit J/ (kg. DEG C) can be as the material for making the crystallizer；Such as：Magnesian
Maximum permissible temperature is 1600 DEG C -1700 DEG C, α=6.857 × 10-7, meet above-mentioned condition, can be used as and make slow-set crystallization
The material of device；Clay material maximum permissible temperature is 1350 DEG C -1450 DEG C, α=3.287 × 10-7Meet above-mentioned condition, can conduct
Make the material of slow-set crystallizer；
Step 2：The determination of crystallizer size
Other sizes of crystallizer can according to 4: 1 the likelihood ratio by special heavy plate crystallizer in actual production Size calculation
, and crystallizer wall thickness then foundationUnit：Mm, wherein：λ1Represent Refractory Thermal Conductivity,
Unit (W/ (m. DEG C))；λ2Ormolu thermal conductivity factor is represented as 109, unit (W/ (m. DEG C))；K represents correction factor, and d is represented
Refractory material crystallizer wall thickness, unit mm；d1Safe thickness is represented, generally takes 10mm；d2Represent during use plus
Work amount, typically takes 10mm~15mm.Work as λ1Difference ∈ (0,0.5], (and 0.5,1], (1,1.5], (1.5,2], (2,2.5],
(2.5,3], (3,3.5], (3.5,4], (4,4.5], (4.5,5] } when, k take respectively 400,150,90,65,50,40,35,30,
25,20 }；Such as：When taking magnesia refractories, its thermal conductivity factor λ1For 2.1W/ (m. DEG C), therefore magnesia crystallizer wall thickness takes
41mm-47mm；When taking high alumina clay refractory material, its thermal conductivity factor λ1For 0.77W/ (m. DEG C), therefore high alumina clay crystallizer
Wall thickness can be taken as 44mm--50mm；
Step 3：Primary crystallization
The crystallizer with Fig. 1 and Fig. 2 features, root are produced according to identified material and size in step 1 and step 2
Require to coordinate induction furnace to be poured into a mould according to specific experiment；When casting complete starts timing, the time can be by
It is determined that unit min, the time is the period after casting complete to form removal；Wherein：ε represents correction factor, when crystallizer wall is led
Hot coefficient lambda (unit (W/ (m. DEG C))) respectively ∈ (0,1], (and 1,3], (3,5], (5,10] } when, ε take respectively 6.2 × 104,
5.3 × 104,4.8 × 104,4.6 × 104 }；E represents initial solidification shell thickness, generally takes 10mm-15mm；C represent solidified shell by
The degree of superheat influences coefficient, generally takes 5mm-10mm；Lf represents the latent heat of solidification of steel, and No. 45 steel are 271.7kJ/Kg；ρ represents steel
Density, 7200kg/m3；λ m represent the thermal conductivity factor of solidified shell, and No. 45 steel are 50.2W/ (m.k)；TSRepresent the solidus temperature of steel
Degree, No. 45 steel solidus are 1337 DEG C；T0Represent the surface temperature of steel billet, 727 DEG C；When taking magnesia refractories, its heat conduction
Coefficient lambda1For 2.1W/ (m. DEG C), therefore it is 39min-49min that magnesia crystallizer wall, which removes the time,；When taking high alumina clay refractory material
When, its thermal conductivity factor λ1For 0.77W/ (m. DEG C), therefore it is 47min-57min that high alumina clay crystallizer wall, which removes the time,；When reaching
The striking time of corresponding material crystallizer, form removal is carried out to prepare in next step；The collecting temperature of thermocouple 2 is used within this time
Variable signal, stop temperature acquisition in form removal；
Step 4：Secondary cooling
Secondary cooling needs to calculate cooling water volume, can foundationUnit L, wherein：κ is amendment system
Number, value 4.9；A is certain value, value 573.93kJ/kg；M be crystallizer in molten steel quality, units/kg；ρ2For water
Density, value 1000kg/m3；T0The initial temperature of water is represented, takes 25 DEG C；T is water temperature, takes 100 DEG C；C represents water
Specific heat capacity, value are 4.2kJ/ (kg. DEG C)；When quality of molten steel is 100kg-150kg, cooling water volume 595.203L- can obtain
742.805L；Sprayed water using Fig. 2 shower nozzle, while A the and B faces of strand are sprayed water using Fig. 2 Combined nozzles；Weak cold two
Cold-zone is in two stages：First stage injection flow rate is 30L/min-40L/min, time 8min-14min；Second stage is sprayed water
Measure as 20L/min-30L/min, time 8min-12min；
Step 5：Sampling analysis
Two cold finish treat that casting blank surface temperature is reduced to room temperature (25 DEG C) and can sampled；To being cut completely in the middle part of solidification strand
Piece samples, and by Metallographic Analysis, confirms that slow-set expands Center Equiaxial Crystal area to special heavy plate continuous casting billet, reduces center field trash
Quantity and change tissue growth effect；Study the Microstructural evolution of special heavy plate slow-set, the crystallization of unlike material
Device and weak cold intensity can be that optimization special heavy plate continuous casting process carries to extra-thick plate blank center porosity, the influence of segregation crack
For rational reference proposition；It is determined that being best suitable for the non-metallic material of the crystallizer of molten steel slow-set, slow-set shape is understood
The development law of state undertissue, extra-thick plate blank internal flaw is reduced or eliminated, improve the quality of special heavy plate continuous casting billet.
Embodiment 1：The experiment of slow-set is carried out in magnesia crystallizer
Step 1：The determination of crystallizer material
Material of the maximum permissible temperature more than or equal to 1400 DEG C is chosen according to requirement of the crystallizer material to temperature；Magnesia,
Clay matter, siliceous and chrome refractory meet the requirements；Magnesia refractories is chosen, material maximum permissible temperature is 1600
DEG C -1700 DEG C, thermal conductivity factor λ is 2.1W/ (m. DEG C), density p 2450kg/m3, specific heat capacity Cp is 1250J/ (kg. DEG C), by α
=λ/(ρ Cp) obtains α=6.857 × 10-7；α ∈ (2.676 × 10-7,21.41 × 10-7), therefore magnesia refractories can be with
As the material for making slow-set crystallizer；
Step 2：The determination of crystallizer size
According to the crystallizer size that can produce 420mm × 2020mm extra-thick plate blanks, it is 4: 1 according to geometric similarity ratio and can embodies
Extra-thick plate blank flakiness ratio be 2.5: 1 requirement, calculate the fertile strand size of use for laboratory crystallizer for 106mm ×
265mm, the size using size of plate blank as crystallizer inner boundary；Selected magnesia refractories, its thermal conductivity factor λ1For 2.1W/ (m.
DEG C), it can obtain magnesia crystallizer wall thickness with wall thickness calculation formula and take 45mm；Needed to pour into a mould 100kg molten steel according to requirement of experiment,
Being poured into a mould the crystallizer in scope (crystallizer is highly higher than actual molten steel liquid level 80mm-100mm) safely by m=ρ V is highly
550mm；So finally determine that magnesia crystallization implement body size is 106mm × 265mm × 550mm, wall thickness 45mm.
Step 3：Primary crystallization
According to the specific size of above-mentioned crystallizer, design and produce fourplatemold mould；It is according to granularmetric composition,
2.5mm-1mm person accounts for 60%-65% (wherein 2.5mm-2mm's accounts for 25%-35%, and 2mm-1mm's accounts for 30%-35%), is less than
0.088mm's accounts for 35%-40% or accounts for the crystallizer that 30%-35% produces magnesian；Assembled according to Fig. 1 and Fig. 2 modes
Crystallizer, when molten steel poring rate is 0.7m/s, the degree of superheat is 45 DEG C, and gate location enters at crystallizer cross-section center position
Row casting；Treat that casting is completed to spread one layer of 20mm covering slag and opening temperature signal receiving device on molten steel surface, record at any time
The change of Fig. 2 positions temperature；According to striking time formula, it is 45min to calculate the safe striking time of magnesia crystallizer, has been poured
Start to remove crystallizer wall into rear timing 45min；
Step 4：Secondary cooling
Crystallizer wall is removed, carries out water-spraying control according to the mounted shower nozzles of Fig. 2, wherein Fig. 2 shower nozzles spray regime is 50
×50mm2, two shower nozzle spacing are 40mm；Strand A faces according to Fig. 2 arrange 10 rows 5 arrange, B faces according to Fig. 2 arrange 10 rows 2 arrange into
Row water spray；When quality of molten steel is 100kg, cooling water volume 595.203L can obtain by water calculation formula；Utilize Fig. 2 shower nozzle
Water spray, while A the and B faces of strand are sprayed water using Fig. 2 Combined nozzles；The cold-zone of weak cold two is in two stages：First rank
Section injection flow rate is 35L/min, time 10min；Second stage injection flow rate is 25L/min, time 10min；
Step 5：Sampling analysis
Two cold finish treat that casting blank surface temperature is reduced to room temperature (it is 25 DEG C to survey casting blank surface temperature with temperature-measuring gun) and can sampled；
To 200mm carries out section sampling in the middle part of solidification strand completely, materialsed respectively from corner and center, low power and scanning are done to sample
Electronic Speculum, confirm that slow-set expands Center Equiaxial Crystal area to special heavy plate continuous casting billet, reduce quantity and the change of center field trash
The effect of tissue growth.Study the Microstructural evolution of special heavy plate slow-set, the crystallizer and weak cold intensity pair of unlike material
The influence of extra-thick plate blank center porosity, segregation crack, and then rational reference can be provided for optimization special heavy plate continuous casting process and built
View.
Contrasted by microexamination, it is found that sample Center Equiaxial Crystal area is significantly greater than columnar zone, this shows institute of the present invention
The slow-set apparatus and method of offer are applied to research special heavy plate slow-set problem.
The present invention realizes the slow-set of molten steel in a crystallizer using static die casting method, and certain thickness is formed in molten steel
After the initial solidification shell of degree, using its detachability, carried out on the relatively low green shell surface being exposed in air of temperature with nozzle 7 weak
Water spray, the process of continuous casting special heavy plate slow-set is simulated by slowing down freezing rate stage by stage.Study special in casting process
The Microstructural evolution of heavy slab slow-set, and analyze field trash distribution situation and produce various defects the reason for.In reality
During testing, the change of temperature is recorded by thermocouple 2, analyzes the relation between the microstructure of green shell and thermal conductivity factor.It is logical
Metallographic Analysis is crossed, confirms that slow-set to expanding Center Equiaxial Crystal area, promotes the floating of field trash and changes tissue growth process
Effect.Slow-set Thermal-state test is carried out by using the crystallizer of unlike material and the shower nozzle of different intensities of cooling, it is determined that
Formation rule and influence of the slow-set on special heavy plate tissue.
Claims (9)
1. a kind of experimental provision for being used to simulate special heavy plate slow-set, it is characterised in that including crystallizer, assembling crystallizes herein
Thermocouple on device, the collector being connected with this thermocouple, the water injector of two cold-zones is arranged on, this water injector is including pressing
Linearly aligned nozzle, the water knockout drum being connected with this nozzle, the flow controller being connected with this water knockout drum.
2. the experimental provision according to claim 1 for being used to simulate special heavy plate slow-set, it is characterised in that described knot
Brilliant device includes the reeded bottom plate of band for being arranged on bottom, sets being made up of four pieces of refractory material crystallizer walls in this groove
And the crystallizer cavity fixed by two pairs of detachable steel bars, the depth of groove of the bottom plate are 2mm-3mm, below described bottom plate
It is equipped with one layer of refractory masses I.
3. the experimental provision according to claim 1 for being used to simulate special heavy plate slow-set, it is characterised in that described heat
Galvanic couple is arranged on refractory material crystallizer wall, is axisymmetricly arranged in the A faces thermocouple of refractory material crystallizer wall, A faces heat
Galvanic couple line space is 80mm-100mm, and bottom a line thermocouple is apart from bottom 100mm-120mm, middle row thermocouple arrangement
On the symmetry axis in A faces, the row thermocouple of both sides two is apart from border 15mm-20mm, in the B faces thermocouple of refractory material crystallizer wall
Arrangement it is identical with A faces.
4. the experimental provision according to claim 2 for being used to simulate special heavy plate slow-set, it is characterised in that described is resistance to
Fiery material layer I thickness is 20mm-30mm, particle≤0.088mm of refractory material.
5. the experimental provision according to claim 2 for being used to simulate special heavy plate slow-set, it is characterised in that described knot
Brilliant device cavity cavity is that a length-width ratio is (2-3): 1 cuboid.
6. the experimental provision according to claim 2 for being used to simulate special heavy plate slow-set, it is characterised in that the fire resisting
The refractory material of material crystalline wall need to meet α m/ α p=(1/128-1/16) and refractoriness is more than under the conditions of 1400 DEG C, wherein α
=λ/(ρ Cp).
7. the experimental provision for being used to simulate special heavy plate slow-set according to claim 2 or 6, it is characterised in that described resistance to
The fire resisting material particle level proportioning of fiery material crystalline wall accounts for 25%-35% for 2.5mm-2mm, and 2mm-1mm's accounts for 30%-
35%, accounting for 35%-40% or account for 30%-35% less than 0.088mm.
8. the experimental provision according to claim 1 for being used to simulate special heavy plate slow-set, it is characterised in that described spray
Mouth projected area is 50mm-60mm, and arrangement spacing is 40mm-50mm, and distance casting blank identity distance is from for 60mm-80mm.
9. a kind of experimental method for utilizing the experimental provision for simulating special heavy plate slow-set, it is characterised in that include experiment
Step is as follows：
Step 1：The determination of crystallizer material
Meeting α=(2.676-21.41) × 10-7And refractoriness is more than under the conditions of 1400 DEG C, wherein α=λ/(ρ Cp), λ generations
The thermal conductivity factor of table material, unit W/ (m. DEG C), ρ represent the density of material, units/kg/m3, Cp represents the specific heat capacity of material, single
Position J/ (kg. DEG C), can be as the material for making the crystallizer；Such as：Magnesian maximum permissible temperature is 1600 DEG C -1700
DEG C, α=6.857 × 10-7, meet above-mentioned condition, can be as the material for making slow-set crystallizer；Clay material highest allows
Temperature is 1350 DEG C -1450 DEG C, α=3.287 × 10-7Meet above-mentioned condition, can be as the material for making slow-set crystallizer；
Step 2：The determination of crystallizer size
Other sizes of crystallizer can according to 4: 1 likelihood ratio by the Size calculation of special heavy plate crystallizer in actual production and
Come, and crystallizer wall thickness then foundationUnit：Mm, wherein：λ1Refractory Thermal Conductivity is represented, it is single
Position (W/ (m. DEG C))；λ2Ormolu thermal conductivity factor is represented as 109, unit (W/ (m. DEG C))；K represents correction factor, and d represents resistance to
Fiery material crystalline wall thickness, unit mm；d1Safe thickness is represented, generally takes 10mm；d2Represent processing during use
Amount, typically takes 10mm~15mm.Work as λ1Difference ∈ (0,0.5], (and 0.5,1], (1,1.5], (1.5,2], (2,2.5], (2.5,
3], (3,3.5], (3.5,4], (4,4.5], (4.5,5] } when, k take respectively 400,150,90,65,50,40,35,30,25,
20}；Such as：When taking magnesia refractories, its thermal conductivity factor λ1For 2.1W/ (m. DEG C), therefore magnesia crystallizer wall thickness takes 41mm-
47mm；When taking high alumina clay refractory material, its thermal conductivity factor λ1For 0.77W/ (m. DEG C), therefore high alumina clay crystallizer wall thickness can
It is taken as 44mm--50mm；
Step 3：Primary crystallization
Crystallizer is produced according to identified material and size in step 1 and step 2, is required to coordinate sensing according to specific experiment
Stove is poured into a mould；When casting complete starts timing, the time can be byIt is determined that unit min, the time are
The period of form removal is arrived after casting complete；Wherein：ε represents correction factor, as crystallizer wall thermal conductivity factor λ (unit (W/ (m.
DEG C))) respectively ∈ (0,1], (and 1,3], (3,5], (5,10] } when, ε take respectively 6.2 × 104,5.3 × 104,4.8 × 104,
4.6×104}；E represents initial solidification shell thickness, generally takes 10mm-15mm；C represents solidified shell is influenceed coefficient by the degree of superheat, is led to
Often take 5mm-10mm；Lf represents the latent heat of solidification of steel, and No. 45 steel are 271.7kJ/Kg；ρ represents the density of steel, 7200kg/m3；λm
The thermal conductivity factor of solidified shell is represented, No. 45 steel are 50.2W/ (m.k)；TSThe solidus temperature of steel is represented, No. 45 steel solidus are
1337℃；T0Represent the surface temperature of steel billet, 727 DEG C；When taking magnesia refractories, its thermal conductivity factor λ1For 2.1W/ (m.
DEG C), therefore the magnesia crystallizer wall dismounting time is 39min-49min；When taking high alumina clay refractory material, its thermal conductivity factor λ1For
0.77W/ (m. DEG C), therefore the high alumina clay crystallizer wall dismounting time is 47min-57min；Tearing open for material crystallizer is corresponded to when reaching
The mould time, form removal is carried out to prepare in next step；Thermocouple collecting temperature variable signal is used within this time, is stopped in form removal
Only temperature acquisition；
Step 4：Secondary cooling
Secondary cooling needs to calculate cooling water volume, can foundationUnit L, wherein：κ is correction factor, is taken
It is worth for 4.9；A is certain value, value 573.93kJ/kg；M be crystallizer in molten steel quality, units/kg；ρ2For the close of water
Degree, value 1000kg/m3；T0The initial temperature of water is represented, takes 25 DEG C；T is water temperature, takes 100 DEG C；C represents the specific heat of water
Hold, value is 4.2kJ/ (kg. DEG C)；When quality of molten steel is 100kg-150kg, cooling water volume 595.203L- can obtain
742.805L；Sprayed water using shower nozzle, while A the and B faces of strand are sprayed water using Combined nozzle；The cold-zone of weak cold two is divided to two
The individual stage：First stage injection flow rate is 30L/min-40L/min, time 8min-14min；Second stage injection flow rate is 20L/
Min-30L/min, time 8min-12min；
Step 5：Sampling analysis
Two cold finish treat that casting blank surface temperature is reduced to room temperature (25 DEG C) and can sampled；Taken to carrying out section in the middle part of solidification strand completely
Sample, by Metallographic Analysis, confirm that slow-set expands Center Equiaxial Crystal area to special heavy plate continuous casting billet, reduce the number of center field trash
Amount and the effect for changing tissue growth；Study special heavy plate slow-set Microstructural evolution, the crystallizer of unlike material and
Weak cold intensity can provide conjunction to extra-thick plate blank center porosity, the influence of segregation crack for optimization special heavy plate continuous casting process
The reference proposition of reason；It is determined that being best suitable for the non-metallic material of the crystallizer of molten steel slow-set, understand under slow-set state
The development law of tissue, extra-thick plate blank internal flaw is reduced or eliminated, improve the quality of special heavy plate continuous casting billet.
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