Summary of the invention
Technical problem to be solved by this invention is to propose a kind of special-shaped continuous casting containing manganses low-alloy high strength steel crystallizer protecting residue that solves sticker type breakout and slab surface crack.
The technical scheme of technical solution problem of the present invention is: special-shaped continuous casting containing manganses low-alloy high strength steel crystallizer protecting residue; comprise pre-melted slag, clinker, lithium carbonate, borax, fluorite, manganese carbonate, carbon black, graphite, bentonite, contained chemical analysis percentage by weight is:
CaO 34.0~40.0
SiO
2 31.0~37.0
li
2O 0.4~0.7
B
2O
3 1.5~3.5
MnO 2.0~4.0
Na
2O 2.0~3.0
F
- 2.5~3.5
C 4.5~6.5
MgO <2.5
Al
2O
3 <7.0
Fe
2O
3 <1.5
Described carbon is the mixture of carbon black and graphite, and its weight ratio is 1: 0.8-1.2.
The chemical analysis percentage by weight of described pre-melt is: CaO 44.0~46.0%, SiO
238.0 Al~42.0%,
2O
33.0 Fe~4.0%,
2O
30.5~1.5%, MgO 2.0~3.0%, Na
2O 4.0~6.0% and F
-2.0~4.0%.
The chemical analysis percentage by weight of described clinker is: CaO 62.0~64.0%, SiO
219.0 Al~21.0%,
2O
35.0 Fe~6.0%,
2O
33.5~4.5% and MgO 6.0~7.0%.
Pre-melted slag of the present invention, clinker, lithium carbonate, manganese carbonate, borax, fluorite, carbon black, graphite, bentonitic granularity are all less than 250 orders.
Preparation method of the present invention is: raw material preparation, batching, stirring and evenly mixing, water mill pulping, mist projection granulating, finished product packing, wherein mixing stirring and water mill pulping time are not less than 45 minutes respectively.
The character of special-shaped continuous casting containing manganses low-alloy high strength steel crystallizer protecting residue: fusing point (hemisphere point temperature) is 1100~1140 ℃; 1300 ℃ viscosity is 0.40~0.60 PaS; Setting temperature is 1150~1190 ℃ (temperature-viscosity curve judgements); Burn-off rate is 28~35 seconds (test of slag post method).
Containing the special-shaped base sticker type breakout of manganese Hi-Stren steel is owing to the lack of lubrication to initial solidification shell in the crystallizer causes; Face crack be since the heat conduction between base shell and the crystallizer inhomogeneous due to, and the physicochemical characteristic of crystallizer protecting residue all has a significant impact above-mentioned two basic processes:
1, to the lubricated influence of initial solidification shell: the physical and chemical performance of covering slag, the best infiltration that can influence covering slag as burn-off rate, viscosity and setting temperature, especially viscosity and the setting temperature of covering slag.
2, the heat transfer between crystallizer wall and base shell is influenced: the heat transfer (and heat flow) between crystallizer and base shell can be regulated by adjusting operating parameter.These operating parameters are types of crystallizer cooling water flow and covering slag.With regard to the performance of covering slag, the heat flow of passing the slag film depends on: a) thickness of solid slag film; B) be penetrated into the crystallization behavior of slag film in crystallizer and the base shell gap.Therefore,, select the major criterion of suitable covering slag to be in order to reduce heat transfer: the one, higher setting temperature; The 2nd, the trend that forms crystallizing layer is remarkable.
The crystallization control device conducts heat and uniformity solves the slab surface crack problem exactly.The appearance of crackle is that thermal stress causes in the base shell owing to the Thermal Contraction Coefficient difference between ferrite and the austenite causes, especially distinctive defective during peritectic steel.The inhomogeneous aggravation higher and that conduct heat of heat flow between crystallizer wall and the base shell will cause the longitudinal crack and the star-like crack of strand.
Eliminate the blemish that contains in the manganese Hi-Stren steel casting for shaped blank continuous process bonding and bleed-out accident or cause by crackle; the processing performance of crystallization control device covering slag is considerable; emphasis is the continuity of lubrication and to the controllability of heat flow; key is that covering slag has stable physical performance, as fusing point, viscosity, setting temperature and crystal property.
The present invention controls the dual alkalinity of covering slag in 1.10~1.20 scopes, guarantees that promptly the slag film forms under the good glassy state in the crystallizer, has certain crystallizing power again simultaneously, improves the lubricated and heat transfer between base shell and the crystallizer, secondly, adopts li
2O, MnO, B
2O
3, Na
2O and CaF
2The method of multiple flux is regulated covering slag fusing point and viscosity, wherein li
2O is an important flux, to reducing covering slag viscosity and fusing point highly significant, while Li
2O can also strengthen the ability that covering slag absorbs field trash, stablizes the physical property of covering slag, Li in the covering slag of the present invention
2O content control range is 0.4~0.7%; Contain a certain amount of MnO in the covering slag and help reducing to contain of the influence of manganese steel liquid the covering slag physical property, thus the lubricated and heat transfer of stablizing slag film in the casting process, and MnO content control range is 2.0~4.0% in the covering slag of the present invention; B
2O
3Except having the effect that reduces covering slag fusing point and viscosity, importantly have the ability of oxide inclusion in the strong absorption steel, stablize the physical property of covering slag, B in the covering slag of the present invention
2O
3The content control range is 1.5~3.5%; Na as GPF (General Protection False slag flux important component
2Content can not be too high in covering slag of the present invention for O, avoids separating out nepheline in the slag film on the one hand, destroys the glass properties of slag film, reduces the Na in the covering slag
2O content also can improve the surface tension of covering slag simultaneously, helps separating of covering slag and molten steel, reduces casting billet surface slag inclusion and dry slag, Na in the covering slag of the present invention
2O content control range is 2.0~3.0%, Na
2O remains adjusting fusing point and viscosity in the effect of covering slag; It is to reduce slag viscosity that F in the covering slag mainly acts on, and improves the melt cinder flowability, but will pay special attention to control the F-content in the covering slag in the present invention, if CaF in the slag
2Too high levels can cause separating out of high-melting-point thing such as cuspidine, destroys the glass of slag, and lubricating condition is worsened; the F ion concentration is too high in addition also can cause serious erosion to stretching into the formula mouth of a river; reduce mouth of a river service life, for this reason, F content control range is 2.5~3.5% in the covering slag of the present invention.At last, claimed exactly slag melts fast, forms enough liquid slag layers and guarantees certain slag consumption.The requirement mixed carbon comtent can not be too high, but can not be low excessively, otherwise the liquid slag layer and the sinter layer that form are too thick, make that the slagging scorification bar is serious, hinders the even inflow of covering slag.Therefore, join the carbon mode and adopt the compound carbon of joining, kind is selected big and fast carbon black and the graphite of burning velocity of specific area for use, and C content control range is 4.5~6.5% in the covering slag of the present invention.MgO, Al
2O
3And Fe
2O
3For raw material is brought composition into, require respectively less than 2.5%, 7.0% and 1.5%.
Join selecting for use and characteristics of slag base-material.The performance of covering slag depends on the selection of system slag base-material, and conventional machine mixes slag and mainly adopts multiple raw material to mix, and has influence on performance variation owing to the back that is heated produces decomposition of chemical compounds, has influenced the stability of slag.This research is selected to join the slag base-material with pre-melted type slag and clinker as covering slag, owing to reduced the allocation ratio of raw material, the stability of Slag Properties is improved.
The present invention compared with prior art, it is good to have a cc billet surface quality, the characteristics that the sticker type breakout accident is few.
The specific embodiment
Below in conjunction with embodiment the present invention is done detailed explanation.
Embodiment 1:
Covering slag chemical analysis: CaO 36.4%, SiO
232.4%, li
2O 0.7%, B
2O
33.4%, MnO 3.9%, Na
2O 2.9%, F
-3.4%, C 6.4%, and MgO 2.4%, Al
2O
36.7%, Fe
2O
31.4%.The covering slag physical property: 1117 ℃ of fusing points, 1300 ℃ viscosity 0.56 PaS, 1162 ℃ of setting temperatures, burn-off rate are 34 seconds.
Embodiment 2:
Covering slag chemical analysis: CaO 37.3%, SiO
234.1%, li
2O 0.6%, B
2O
33.2%, MnO 3.5%, Na
2O 2.4%, F
-3.0%, C 5.9%, and MgO 2.3%, Al
2O
36.5%, Fe
2O
31.2%.The covering slag physical property: 1128 ℃ of fusing points, 1300 ℃ viscosity 0.53 PaS, 1173 ℃ of setting temperatures, burn-off rate are 32 seconds.
Embodiment 3:
Covering slag chemical analysis: CaO 38.7%, SiO
235.2%, li
2O 0.6%, B
2O
32.5%, MnO 2.3%, Na
2O 2.7%, F
-3.2%, C 5.5%, and MgO 2.1%, Al
2O
36.1%, Fe
2O
31.1%.The covering slag physical property: 1130 ℃ of fusing points, 1300 ℃ viscosity 0.51 PaS, 1177 ℃ of setting temperatures, burn-off rate are 30 seconds.
Embodiment 4:
Covering slag chemical analysis: CaO 39.7%, SiO
234.5%, li
2O 0.5%, B
2O
31.9%, MnO 2.8%, Na
2O 2.6%, F
-2.9%, C 4.8%, and MgO 2.2%, Al
2O
36.8%, Fe
2O
31.3%.The covering slag physical property: 1138 ℃ of fusing points, 1300 ℃ viscosity 0.44 PaS, 1184 ℃ of setting temperatures, burn-off rate are 29 seconds.
Embodiment 1-4 pours into a mould on horse steel 750mm * 450mm * big special-shaped billet continuous casting machine of 120mm and contains the manganese Hi-Stren steel, and the slag consumption when pulling rate is stabilized in 0.75m/min. is 0.85kg/T steel, molten steel surface liquid slag layer thickness 8~12mm.Show that through site test results when this covering slag used, spreadability, heat insulating ability and meltdown property performance were good in crystallizer; Four face heat outputs are stable and even in the crystallizer; In the casting process, the covering slag stable performance, the highest company waters the stove number and reaches 60 stoves, because of the stocking that slab surface crack causes is scrapped less than 5.0 kilograms of/ton steel no adhesion bleed-out accident.