CN107838390A - A kind of method for improving big cross section peritectic steel continuous casting billet quality - Google Patents
A kind of method for improving big cross section peritectic steel continuous casting billet quality Download PDFInfo
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- CN107838390A CN107838390A CN201711022570.0A CN201711022570A CN107838390A CN 107838390 A CN107838390 A CN 107838390A CN 201711022570 A CN201711022570 A CN 201711022570A CN 107838390 A CN107838390 A CN 107838390A
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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
- B22D11/18—Controlling or regulating processes or operations for pouring
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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
- B22D11/10—Supplying or treating molten metal
- B22D11/11—Treating the molten metal
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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
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Abstract
The invention discloses a kind of method for improving big cross section peritectic steel continuous casting billet quality, methods described includes being controlled following processing step：（1）Optimize low-alloy peritectoid steel chemical composition；（2）After VD processing, control feeding calcium line carries out final deoxidizing and inclusions class, and soft blow is carried out before casting；（3）Tundish takes full package operation, controls tonnage, avoids the occurrence of low liquid level casting；（4）Tundish degree of superheat when controlling continuous casting throwing, while control the molten steel temperature difference between adjacent two stove；（5）Crystallizer inflow temperature is controlled, passes in and out water temperature difference, while increases mould at narrow taper, compensates peritectic steel amount of contraction；（6）From the peritectic steel mould flux that basicity is higher, viscosity is low, melting rate is high；（7）Control enters the two after-applied electromagnetic agitations of cold-zone 12m, while reduces secondary cooling water.The big cross section peritectic steel surface quality of continuously cast slab and internal soundness of the inventive method casting are largely improved.
Description
Technical field
The invention belongs to metallurgical technology field, and in particular to a kind of side for improving big cross section peritectic steel continuous casting billet quality
Method.
Background technology
Cracks In Continuous Cast Billets be produce defect free slab significant obstacle, especially cast big cross section peritectic steel when, cast
The probability of base mass defect is far longer than the steel grade of other light section types.From carbon iron balance phasor as can be seen that 1495
DEG C when, [C] be 0.09~0.17% iron-carbon alloy peritectic reaction occurs in process of setting, crystallize end when will obtain
Non-equilibrium microstructure containing δ phases, cause to produce local gaps, local " focus " is in crack-sensitivity area.Now export heat compared with
Small, green shell is relatively thin, and surface easily produces depression, and depressed area cooling and setting rate are slower than other positions, cause to come into being
Shell thickness it is uneven, while will also result in the thermograde in solidified shell and stress gradient skewness, this just promotees
The formation of crackle is entered.
Meanwhile for large-section crystallizer, setting rate is relatively slow, liquid core length is longer, impurity element have compared with
The sufficient time is crystallized and migrated, and causes center segregation and center porosity more serious.When continuous casting billet is in process of setting,
The column crystal of preferred growth meets to be formed " bridging " at strand center, and the molten steel of crystal brige bottom cannot get top in solidification shrinkage
Molten steel supplement and form loose or shrinkage cavity, and with center segregation.Center segregation causes enrichment of the impurity element in center portion, and
With the generation of field trash, the mechanical property of finished steel plate can be had a strong impact on.
Art methods be in secondary cooling using the extension of weak cold system Crack prevention, but this can cause it is two cold
Area's casting blank shell decreased growth and green shell surface temperature are of a relatively high.Although such a method can slow down crackle to a certain extent
Further expansion, but the generation of crackle can not be prevented, because most surfaces crackle has been formed in crystallizer, it is clear that
Such a method can not fundamentally solve the generation of Cracks In Continuous Cast Billets.
The content of the invention
, should the technical problem to be solved in the present invention is to provide a kind of method for improving big cross section peritectic steel continuous casting billet quality
Method is controlled by smelting process sublimate, impurity thing controls, the degree of superheat controls, conical degree of crystallizer controls, liquid fluctuating controls
Deng technological measure, and two chill space electromagnetic stirring technologies are combined, eliminate big cross section peritectoid steel continuous casting billet center segregation, crackle, be mingled with
Etc. mass defect, solve the quality problems such as big cross section peritectic steel continuous casting billet face crack, center segregation in common process, improve
Surface quality of continuously cast slab and internal soundness.
In order to solve the above technical problems, the present invention adopts the technical scheme that：One kind can improve big cross section peritectic steel continuous casting
The method of base quality, methods described are included to following processing step：
（1）Optimize low-alloy peritectoid steel chemical composition；
（2）After converter melting, the refining of LF stoves, VD processing, control feeding calcium line carries out final deoxidizing and inclusions class, casting
Preceding carry out soft blow, control the amount of inclusions, form, distribution, it is 0.10~0.14 to ensure T [Ca]/[Al] s；
（3）Tundish takes full package operation, controls tonnage, avoids the occurrence of low liquid level casting；
（4）Caster type is straight circular-arc type continuous casting machine during continuous casting, arc radius 10.5m, controls continuous casting throwing in casting cycle
When the tundish degree of superheat, while control the molten steel temperature difference between adjacent two stove, keep conticaster pulling rate stable；
（5）Crystallizer inflow temperature is controlled, keeps crystallizer disengaging water temperature difference stable at 5~7 DEG C, and liquid level fluctuation of crystallizer is steady
It is scheduled within ± 3mm, while increases mould at narrow taper, compensates peritectic steel amount of contraction；
（6）It is beneficial to crystallizer slow cooling from peritectic steel mould flux, lightened plate floor checking line produces；
（7）After continuous casting billet goes out crystallizer, control enters the two after-applied electromagnetic agitations of cold-zone 12m, improves center segregation, reduces simultaneously
Secondary cooling water.
Step of the present invention（1）The low-alloy peritectoid steel chemical composition of middle optimization forms and weight/mass percentage composition is：Al：
0.020~0.040%, N≤40ppm, O≤20ppm, H≤1.5ppm, S≤0.005%, P≤0.008%.
Step of the present invention（2）Calcium line 2.0-3.0 ㎏/t steel, argon gas soft blow 10-12min are fed after middle VD processing.
Step of the present invention（3）In tundish take full package operation, it is 28-30t to control tonnage.
Step of the present invention（4）Middle continuous-cast blank thickness 300mm and 330mm, strand width is in 1400~2400mm.
Step of the present invention（4）Tundish degree of superheat during middle control casting cycle continuous casting throwing, in first stove casting control
Between bag superheat of liquid steel be 25~45 DEG C, the tundish molten steel degree of superheat control in stable process of billet withdrawal as 15~25 DEG C；Control phase
The molten steel temperature difference is less than 10 DEG C between adjacent two stoves.
Step of the present invention（5）Middle 31-33 DEG C of control crystallizer inflow temperature；Increase mould at narrow taper 0.01-
0.03%/m, compensate peritectic steel amount of contraction.
Step of the present invention（6）The covering slag of middle selection is low speed peritectic steel covering slag, covering slag viscosity：
0.076PaS, melt speed：35（S, 1350 DEG C）, basicity：1.44.The parameter of specific covering slag used is as shown in Table 1 and Table 2：
The low speed peritectic steel crystallizer covering slag main component of table 1（Wt, %）
The low speed peritectic steel crystallizer covering slag physical parameter of table 2
Step of the present invention（7）Middle electromagnetic agitation is roll-type stirring, and stir current 400A, stirring voltage is 380V, frequency
For 12HZ.
The method of the invention is applied to arc, vertical with bending type continuous casting machine type, produces thickness >=300mm big cross section continuous casting
Base.
Heretofore described common process mainly includes the following aspects：（1）Molten steel degree of purity is poor, S, P, O, N,
The impurity such as H and elemental gas content are higher, have had a strong impact on Inner Quality of Billet；（2）Middle bag tonnage is relatively low, generally exists
25t or so, it have impact on the abundant floating of field trash；（3）Crystallizer disengaging water temperature difference is larger, generally higher than 9 DEG C, have impact on strand
Cooling effect, while liquid surface wave momentum is further degrading cc billet surface quality more than 5mm；（4）Shunk for peritectic steel special
Property, do not select suitable taper and mould flux（5）Secondary cooling zone does not apply electromagnetic agitation, and column crystal is flourishing, shadow
Ring Inner Quality of Billet.
The mentality of designing of the present invention is as follows：
It is to be formed to be mingled with process of setting that 1. the impurity such as molten steel degree of purity, S, P, O, N, H and elemental gas are controlled in smelting process
Thing induces the principal element of gross segregation and shrinkage porosite.Therefore, ensure the degree of purity of molten steel on source to control gas and be mingled with
The formation of thing has great importance.Aluminium content control in molten steel is 0.020~0.040%, so as to ensure that the deoxidation of molten steel is imitated
Fruit, gas and impurity element control targe are：N≤40ppm, O≤20ppm, H≤1.5ppm, S≤0.005%, P≤0.008%；
Calcium line is fed after VD processing, its feed quantity is 2.0-3.0 ㎏/t steel, and ensures that T [Ca]/[Al] s is 0.10~0.14, before casting
The increase soft blow time is 10-12min, promotes inclusion floating.
2. casting cycle controls the degree of superheat.For big cross section peritectic steel casting of continuous-cast billet, degree of superheat height causes liquid
Solidification shrinkage amount is big, and feeding is difficult, easily causes shrinkage cavity and the mass defect such as loose.Meanwhile degree of superheat height of casting causes to solidify
Time is grown, and solute and impurity element have time enough to separate out, spread, assemble from molten metal, so as to cause serious center
Segregation.Moreover, column crystal prosperity easily occurs in the too high degree of superheat, or even transcrystallization structure is formed, have a strong impact on matter inside strand
Amount.
3. control tundish tonnage.If tundish liquid level is too low, the secondary oxidation of molten steel and big bag beam are easily caused
The appearance of impact zone opening position slag phenomenon.Meanwhile too low tundish liquid level, easily stopper opening position formed whirlpool and then
Cause the fluctuation of mold liquid level and be involved in covering slag.Therefore, when tundish starts casting, need to add in mold powder cover
Between Baogang's liquid level, avoid molten steel is exposed from causing secondary oxidation, after pulling rate is stable, tundish liquid level need to be kept high level, adopted
Full package operation is taken, controls tundish tonnage 28-30t, when changing big bag, control unwraps tundish tonnage >=21t when pouring greatly.
4. control crystallizer disengaging water temperature difference and liquid level fluctuation of crystallizer.When liquid level fluctuation of crystallizer control ± 3mm with
When upper, easily there is the phenomenon of surface longitudinal crack and Surface inclusion in strand.When liquid fluctuating amplitude is more than liquid slag layer thickness, meeting
Melt cinder is hindered uniformly to flow into air gap, it is impossible to lubrication green shell and heat transfer well, to cause surface quality defect.Crystallizer passes in and out water temperature
Difference should control the uniform cooling that casting blank shell can be so effectively facilitated at 5~7 DEG C, the generation of effective Crack prevention.
5. control mould at narrow taper.For big cross section peritectoid steel continuous casting billet, if taper is too small, it is impossible to compensate
Crystallizer surrounding green shell is shunk, and whole narrow side forms air gap, influences the heat conduction of green shell, causes green shell surface serious crackle occur
Etc. mass defect.Therefore, to compensate narrow side because certain linear taper is artificially given on contraction, narrow side caused by Multiple factors, with
Prevent that air gap is produced between green shell and steel plate influences heat derives.
6. select suitable crystallizer protecting residue.If the crystallizer protecting residue viscosity selected is too high, fusing is slow, liquid slag layer
Thickness low LCL, melt cinder are not easy to leak into green shell and copper coin gap, can influence green shell heat transfer, can also cause when serious and cohere bleed-out evil
The generation of sexual behavior event.Therefore, the crystallizer protecting residue of selection should have the characteristic that basicity is higher, viscosity is low, melting rate is high, this
Sample can ensure the direct motion of throwing and the improvement of slab quality.
7. two cold-zones use electromagnetic agitating technology.Big cross section continuous casting billet easily forms dendrite and put up a bridge now in casting cycle
As seriously hindering the feeding of molten steel, influenceing the quality of strand.Therefore, two cold-zones can smash branch using electromagnetic agitating technology
Crystalline substance, expand isometric crystalline region, and then improve Inner Quality of Billet.
Detected according to YB/T 4003, evaluate the continuous casting billet internal flaw level results before and after the present invention is implemented and be shown in Table
3。
The strand of table 3 grading table
Big cross section peritectoid steel continuous casting billet product standard reference of the present invention《YB/T 2012-2014 continuous casting steel machine slabs》, performance inspection
Survey method refers to《The continuous casting plate slab macrostructure defect judge pictures of YB/T 4003》.
It is using beneficial effect caused by above-mentioned technical proposal：1st, by controlling molten steel in smelting process of the present invention
Degree of purity, gas and impurity content are reduced, reduce inclusion content, suppress the generation of segregation from source.Meanwhile at VD
Calcium line is fed after reason and increases the soft blow time, by this come control the amount of inclusions, in the form of, distribution, advantageously reduce field trash and contain
The influence of amount and mitigation field trash to plate property.2nd, the present invention is by controlling tundish low overheat, tundish high level, connecting
Casting machine perseverance pulling rate can keep the stabilization of conticaster technological parameter, avoid because liquid steel temperature difference is big, caused by tundish low liquid level
The phenomenon that strand column crystal is flourishing and field trash increases occur, improve big cross section peritectoid steel continuous casting billet to a certain extent
Quality.3rd, the present invention can be solved effectively by controlling the technological measures such as liquid level fluctuation of crystallizer, narrow side taper, disengaging water temperature difference
Certainly crystallizer uniformly transfer heat, and then the even solidification of molten steel can be promoted, reduce the generation of slab surface crack.Meanwhile control
Liquid level fluctuation of crystallizer is it is possible to prevente effectively from covering slag is involved in molten steel, raising cc billet surface quality.4th, the present invention uses peritectic steel
Mould flux, there is the characteristic that basicity is higher, viscosity is low, melting rate is high, be advantageous to the slow cooling of crystallizer, slab can be mitigated
Crackle produces.5th, two cold-zones of the invention use electromagnetic agitating technology, can improve equiaxial crystal ratio, the column crystal reduced in strand
Area, and then improve the macrostructure of continuous casting billet, improve the quality of continuous casting billet.
Brief description of the drawings
Fig. 1 is the big cross section peritectoid steel continuous casting billet low power micro-organization chart of embodiment 1；
Fig. 2 is that common process produces specification big cross section peritectoid steel continuous casting billet low power micro-organization chart same as Example 1；
Fig. 3 is the big cross section peritectoid steel continuous casting billet low power micro-organization chart of embodiment 2；
Fig. 4 is that common process produces specification big cross section peritectoid steel continuous casting billet low power micro-organization chart same as Example 2；
Fig. 5 is the big cross section peritectoid steel continuous casting billet low power micro-organization chart of embodiment 3；
Fig. 6 is that common process produces specification big cross section peritectoid steel continuous casting billet low power micro-organization chart same as Example 3；
Fig. 7 is the big cross section peritectoid steel continuous casting billet low power micro-organization chart of embodiment 4；
Fig. 8 is that common process produces specification big cross section peritectoid steel continuous casting billet low power micro-organization chart same as Example 4；
Fig. 9 is the big cross section peritectoid steel continuous casting billet low power micro-organization chart of embodiment 5；
Figure 10 is that common process produces specification big cross section peritectoid steel continuous casting billet low power micro-organization chart same as Example 5.
Embodiment
The present invention is described in more detail with specific embodiment below in conjunction with the accompanying drawings.
Embodiment 1
The present embodiment big cross section peritectoid steel continuous casting billet, cross dimensions are 330 × 2400mm, and slab material is Q345R.
The present embodiment big cross section peritectoid steel continuous casting billet production method is as follows：
Molten steel is carried out using converter, then refined through LF stoves, molten steel then is transferred into VD stoves carries out vacuum deaeration degassing,
Vacuum terminates to feed 2.0 ㎏ of calcium line/t steel progress final deoxidizing and inclusions class, soft blow 10min, T before being cast
[Ca]/[Al] s are 0.11, promote inclusion floating.Aluminium content is 0.025% in molten steel, and gas and impurity content are：T
[N]：40ppm, T [O]：15ppm, T [H]：1.5ppm, T [S]：0.003%, T [P]：0.005%.
Molten steel is cast in tundish at 1575 DEG C, and the tundish degree of superheat is 55 DEG C.During continuous casting throwing, steel in tundish
1540 DEG C of coolant-temperature gage, the degree of superheat are 20 DEG C；The molten steel temperature difference is less than 10 DEG C between controlling adjacent two stove.After pulling rate is stable, by
Between bag tonnage rise to 29t, and tundish covering flux is covered into molten steel face, avoids molten steel secondary oxidation.Crystallization is adjusted before casting
The narrow side taper of device, increase taper 0.01%/m on the basis of ordinary steel, to compensate strand contraction.The crystallizer inflow temperature is controlled to be
32 DEG C, it is ensured that disengaging water temperature difference ensures that molten steel uniformly cools down at 5~7 DEG C.
After continuous casting billet goes out crystallizer, into two cold-zone 12m after put into electromagnetic agitation, electromagnetic agitation is roll-type stirring, stirring
Electric current is 400A, and stirring voltage is 380V, frequency 12HZ, improves casting blank solidification tissue, promotes the formation of equiax crystal, further
Improve slab quality.
Fig. 1 is the Cross Section of CC Billet low power micro-organization chart of the present embodiment production, and Fig. 2 is the continuous casting billet of common process production
Section low power micro-organization chart.Comparison diagram 1 is visible with Fig. 2, and the strand of common process production, center segregation is more serious, tissue
It is uneven and shrinkage cavity be present.Split using the big cross section peritectoid steel continuous casting billet center segregation of method of the present invention production, intergranular
Line, solidified structure etc. all be improved significantly.
Detected according to YB/T 4003, the present invention implements front and rear continuous casting billet internal flaw level results and is shown in Table 4.
The strand of table 4 grading table
Embodiment 2
The present embodiment big cross section peritectoid steel continuous casting billet, cross dimensions are 300 × 2400mm, and slab material is Q690D.
The present embodiment big cross section peritectoid steel continuous casting billet production method is as follows：
Molten steel is carried out using converter, then refined through LF stoves, molten steel then is transferred into VD stoves carries out vacuum deaeration degassing,
Vacuum terminates to feed 2.2 ㎏ of calcium line/t steel progress final deoxidizing and inclusions class, soft blow 11min, T before being cast
[Ca]/[Al] s are 0.13, promote inclusion floating.Aluminium content is 0.030% in molten steel, and gas and impurity content are：T
[N]：40ppm, T [O]：20ppm, T [H]：1.5ppm, T [S]：0.004%, T [P]：0.004%.
Molten steel is cast in tundish at 1570 DEG C, and the tundish degree of superheat is 50 DEG C.During continuous casting throwing, steel in tundish
1545 DEG C of coolant-temperature gage, the degree of superheat are 25 DEG C；The molten steel temperature difference is less than 10 DEG C between controlling adjacent two stove.After pulling rate is stable, by
Between bag tonnage rise to 30t, and tundish covering flux is covered into molten steel face, avoids molten steel secondary oxidation.Crystallization is adjusted before casting
The narrow side taper of device, increase taper 0.02%/m on the basis of ordinary steel, to compensate strand contraction.The crystallizer inflow temperature is controlled to be
32 DEG C, it is ensured that disengaging water temperature difference ensures that molten steel uniformly cools down at 5~7 DEG C.
After continuous casting billet goes out crystallizer, into two cold-zone 12m after put into electromagnetic agitation, electromagnetic agitation is roll-type stirring, stirring
Electric current is 400A, and stirring voltage is 380V, frequency 12HZ, improves casting blank solidification tissue, promotes the formation of equiax crystal, further
Improve slab quality.
Fig. 3 is the Cross Section of CC Billet low power micro-organization chart of the present embodiment production, and Fig. 4 is the continuous casting billet of common process production
Section low power micro-organization chart.Comparison diagram 3 is visible with Fig. 4, and the strand of common process production, center segregation is more serious, tissue
Uneven and column crystal is more flourishing.Using method of the present invention production big cross section peritectoid steel continuous casting billet center segregation,
Intercrystalline crack, solidified structure etc. all be improved significantly.
Detected according to YB/T 4003, the present invention implements front and rear continuous casting billet internal flaw level results and is shown in Table 5.
The strand of table 5 grading table
Embodiment 3
The present embodiment big cross section peritectoid steel continuous casting billet, cross dimensions are 330 × 2100mm, and slab material is AB/EQ70.
The present embodiment big cross section peritectoid steel continuous casting billet production method is as follows：
Molten steel is carried out using converter, then refined through LF stoves, molten steel then is transferred into VD stoves carries out vacuum deaeration degassing,
Vacuum terminates to feed 2.5 ㎏ of calcium line/t steel progress final deoxidizing and inclusions class, soft blow 11min, T before being cast
[Ca]/[Al] s are 0.12, promote inclusion floating.Aluminium content is 0.033% in molten steel, and gas and impurity content are：T
[N]：35ppm, T [O]：15ppm, T [H]：1.5ppm, T [S]：0.002%, T [P]：0.005%.
Molten steel is cast in tundish at 1580 DEG C, and the tundish degree of superheat is 60 DEG C.During continuous casting throwing, steel in tundish
1543 DEG C of coolant-temperature gage, the degree of superheat are 15 DEG C；The molten steel temperature difference is less than 10 DEG C between controlling adjacent two stove.After pulling rate is stable, by
Between bag tonnage rise to 28t, and tundish covering flux is covered into molten steel face, avoids molten steel secondary oxidation.Crystallization is adjusted before casting
The narrow side taper of device, increase taper 0.01%/m on the basis of ordinary steel, to compensate strand contraction.The crystallizer inflow temperature is controlled to be
32 DEG C, it is ensured that disengaging water temperature difference ensures that molten steel uniformly cools down at 5~7 DEG C.
After continuous casting billet goes out crystallizer, into two cold-zone 12m after put into electromagnetic agitation, electromagnetic agitation is roll-type stirring, stirring
Electric current is 400A, and stirring voltage is 380V, frequency 12HZ, improves casting blank solidification tissue, promotes the formation of equiax crystal, further
Improve slab quality.
Fig. 5 is the Cross Section of CC Billet low power micro-organization chart of the present embodiment production, and Fig. 6 is the continuous casting billet of common process production
Section low power micro-organization chart.Comparison diagram 5 is visible with Fig. 6, and the strand of common process production, center segregation is more serious, tissue
It is uneven and shrinkage cavity be present.Split using the big cross section peritectoid steel continuous casting billet center segregation of method of the present invention production, intergranular
Line, solidified structure etc. all be improved significantly.
Detected according to YB/T 4003, the present invention implements front and rear continuous casting billet internal flaw level results and is shown in Table 6.
The strand of table 6 grading table
Embodiment 4
The present embodiment big cross section peritectoid steel continuous casting billet, cross dimensions are 330 × 1400mm, and slab material is Q690E.
The present embodiment big cross section peritectoid steel continuous casting billet production method is as follows：
Molten steel is carried out using converter, then refined through LF stoves, molten steel then is transferred into VD stoves carries out vacuum deaeration degassing,
Vacuum terminates to feed 2.4 ㎏ of calcium line/t steel progress final deoxidizing and inclusions class, soft blow 10min, T before being cast
[Ca]/[Al] s are 0.10, promote inclusion floating.Aluminium content is 0.020% in molten steel, and gas and impurity content are：T
[N]：25ppm, T [O]：10ppm, T [H]：1.0ppm, T [S]：0.005%, T [P]：0.008%.
Molten steel is cast in tundish at 1573 DEG C, and the tundish degree of superheat is 52 DEG C.During continuous casting throwing, first stove tundish
Interior 1542 DEG C of liquid steel temperature, the degree of superheat are 45 DEG C；The molten steel temperature difference is less than 10 DEG C between controlling adjacent two stove.After pulling rate is stable,
Tundish tonnage is risen into 30t, and tundish covering flux is covered into molten steel face, avoids molten steel secondary oxidation.Adjusted before casting
Mould at narrow taper, increase taper 0.01%/m on the basis of ordinary steel, to compensate strand contraction.Control crystallizer enters water temperature
Spend for 33 DEG C, it is ensured that disengaging water temperature difference ensures that molten steel uniformly cools down at 5~7 DEG C.
After continuous casting billet goes out crystallizer, into two cold-zone 12m after put into electromagnetic agitation, electromagnetic agitation is roll-type stirring, stirring
Electric current is 400A, and stirring voltage is 380V, frequency 12HZ, improves casting blank solidification tissue, promotes the formation of equiax crystal, further
Improve slab quality.
Fig. 7 is the Cross Section of CC Billet low power micro-organization chart of the present embodiment production, and Fig. 8 is the continuous casting billet of common process production
Section low power micro-organization chart.Comparison diagram 7 is visible with Fig. 8, and the strand of common process production, center segregation is more serious, tissue
Uneven and thick column crystal hypertrophy.The big cross section peritectoid steel continuous casting billet center produced using method of the present invention
Segregation, intercrystalline crack, solidified structure etc. all be improved significantly.
Detected according to YB/T 4003, the present invention implements front and rear continuous casting billet internal flaw level results and is shown in Table 7.
The strand of table 7 grading table
Embodiment 5
The present embodiment big cross section peritectoid steel continuous casting billet, cross dimensions are 300 × 1400mm, and slab material is Q345R-HIC.
The present embodiment big cross section peritectoid steel continuous casting billet production method is as follows：
Molten steel is carried out using converter, then refined through LF stoves, molten steel then is transferred into VD stoves carries out vacuum deaeration degassing,
Vacuum terminates to feed 3.0 ㎏ of calcium line/t steel progress final deoxidizing and inclusions class, soft blow 12min, T before being cast
[Ca]/[Al] s are 0.14, promote inclusion floating.Aluminium content is 0.040% in molten steel, and gas and impurity content are：T
[N]：15ppm, T [O]：9ppm, T [H]：0.8ppm, T [S]：0.003%, T [P]：0.004%.
Molten steel is cast in tundish at 1577 DEG C, and the tundish degree of superheat is 58 DEG C.During continuous casting throwing, first stove tundish
Interior 1541 DEG C of liquid steel temperature, the degree of superheat are 25 DEG C；The molten steel temperature difference is less than 10 DEG C between controlling adjacent two stove.After pulling rate is stable,
Tundish tonnage is risen into 28t, and tundish covering flux is covered into molten steel face, avoids molten steel secondary oxidation.Adjusted before casting
Mould at narrow taper, increase taper 0.03%/m on the basis of ordinary steel, to compensate strand contraction.Control crystallizer enters water temperature
Spend for 31 DEG C, it is ensured that disengaging water temperature difference ensures that molten steel uniformly cools down at 5~7 DEG C.
After continuous casting billet goes out crystallizer, into two cold-zone 12m after put into electromagnetic agitation, electromagnetic agitation is roll-type stirring, stirring
Electric current is 400A, and stirring voltage is 380V, frequency 12HZ, improves casting blank solidification tissue, promotes the formation of equiax crystal, further
Improve slab quality.
Fig. 9 is the Cross Section of CC Billet low power micro-organization chart of the present embodiment production, and Figure 10 is the continuous casting of common process production
Base section low power micro-organization chart.Comparison diagram 9 is visible with Figure 10, the strand of common process production, center segregation and intercrystalline crack
It is more serious, uneven microstructure.Using the big cross section peritectoid steel continuous casting billet center segregation of method of the present invention production, intergranular
Crackle, solidified structure etc. all be improved significantly.
Detected according to YB/T 4003, the present invention implements front and rear continuous casting billet internal flaw level results and is shown in Table 8.
The strand of table 8 grading table
Above example is only to illustrative and not limiting technical scheme, although entering with reference to above-described embodiment to the present invention
Go detailed description, it will be understood by those within the art that：Still the present invention can be modified or equally replaced
Change, any modification or partial replacement without departing from the spirit and scope of the present invention, it all should cover will in right of the invention
Ask among scope.
Claims (10)
- A kind of 1. method for improving big cross section peritectic steel continuous casting billet quality, it is characterised in that methods described is included to following work Skill step：（1）Optimize low-alloy peritectoid steel chemical composition；（2）After converter melting, the refining of LF stoves, VD processing, control feeding calcium line carries out final deoxidizing and inclusions class, casting Preceding carry out soft blow, control the amount of inclusions, form, distribution, it is 0.10~0.14 to ensure T [Ca]/[Al] s；（3）Tundish takes full package operation, controls tonnage, avoids the occurrence of low liquid level casting；（4）Caster type is straight circular-arc type continuous casting machine during continuous casting, arc radius 10.5m, controls continuous casting throwing in casting cycle When the tundish degree of superheat, while control the molten steel temperature difference between adjacent two stove, keep conticaster pulling rate stable；（5）Crystallizer inflow temperature is controlled, keeps crystallizer disengaging water temperature difference stable at 5~7 DEG C, and liquid level fluctuation of crystallizer is steady It is scheduled within ± 3mm, while increases mould at narrow taper, compensates peritectic steel amount of contraction；（6）It is beneficial to crystallizer slow cooling from peritectic steel mould flux, lightened plate floor checking line produces；（7）After continuous casting billet goes out crystallizer, control enters the two after-applied electromagnetic agitations of cold-zone 12m, improves center segregation, reduces simultaneously Secondary cooling water.
- A kind of 2. method for improving big cross section peritectic steel continuous casting billet quality according to claim 1, it is characterised in that institute State step（1）Middle optimization low-alloy peritectoid steel chemical composition composition and weight/mass percentage composition are：Al：0.020~0.040%, N≤ 40ppm, O≤20ppm, H≤1.5ppm, S≤0.005%, P≤0.008%.
- A kind of 3. method for improving big cross section peritectic steel continuous casting billet quality according to claim 1, it is characterised in that institute State step（2）Calcium line 2.0-3.0 ㎏/t steel, argon gas soft blow 10-12min are fed after middle VD processing.
- A kind of 4. method for improving big cross section peritectic steel continuous casting billet quality according to claim 1, it is characterised in that institute State step（3）In tundish take full package operation, it is 28-30t to control tonnage.
- A kind of 5. method for improving big cross section peritectic steel continuous casting billet quality according to claim 1, it is characterised in that institute State step（4）Middle continuous-cast blank thickness 300mm and 330mm, strand width is in 1400~2400mm.
- 6. a kind of method for improving big cross section peritectic steel continuous casting billet quality according to claim 1-5 any one, its It is characterised by, the step（4）Tundish degree of superheat during middle control casting cycle continuous casting throwing, the first middle Baogang of stove casting control The liquid degree of superheat is 25~45 DEG C, and it is 15~25 DEG C that the tundish molten steel degree of superheat is controlled in stable process of billet withdrawal；Control adjacent two stove Between the molten steel temperature difference be less than 10 DEG C.
- 7. a kind of method for improving big cross section peritectic steel continuous casting billet quality according to claim 1-5 any one, its It is characterised by, the step（5）Middle 31-33 DEG C of control crystallizer inflow temperature；Increase mould at narrow taper 0.01-0.03%/ M, compensate peritectic steel amount of contraction.
- 8. a kind of method for improving big cross section peritectic steel continuous casting billet quality according to claim 1-5 any one, its It is characterised by, the step（6）The covering slag of middle selection is low speed peritectic steel covering slag, covering slag viscosity：0.076PaS, melt Speed：35（S, 1350 DEG C）, basicity：1.44.
- 9. a kind of method for improving big cross section peritectic steel continuous casting billet quality according to claim 1-5 any one, its It is characterised by, the step（7）Middle electromagnetic agitation stirs for roll-type, and stir current 400A, stirring voltage is 380V, and frequency is 12HZ。
- 10. a kind of method for improving big cross section peritectic steel continuous casting billet quality according to claim 1-9 any one, its It is characterised by, methods described is applied to arc, vertical with bending type continuous casting machine type, produces thickness >=300mm big cross section continuous casting billet.
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| CN109136742A (en) * | 2018-07-13 | 2019-01-04 | 舞阳钢铁有限责任公司 | S355G8+M-Z35 super thick ultra-wide continuous casting billet and its production method |
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| CN109136782B (en) * | 2018-09-25 | 2020-11-03 | 邯郸钢铁集团有限责任公司 | Control method for casting blank longitudinal crack of 1000 MPa-grade cold-rolled strip steel |
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| CN111360220A (en) * | 2020-04-07 | 2020-07-03 | 山东钢铁集团日照有限公司 | Method for controlling surface quality of continuous casting peritectic steel ultra-wide slab |
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| US11192176B1 (en) | 2020-06-17 | 2021-12-07 | University Of Science And Technology Beijing | Method for improving center segregation and surface crack of continuous casting medium thick slab of peritectic steel |
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| CN115519083B (en) * | 2022-08-26 | 2024-05-10 | 江苏利淮钢铁有限公司 | Control method for surface quality of 15CrMoG continuous casting square billet of tube blank steel |
| CN115747672A (en) * | 2022-10-20 | 2023-03-07 | 北京首钢股份有限公司 | Peritectic steel and preparation method thereof |
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