CN1597182A - Method for producing ultra low carbon steel slab - Google Patents

Method for producing ultra low carbon steel slab Download PDF

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Publication number
CN1597182A
CN1597182A CNA2004100748080A CN200410074808A CN1597182A CN 1597182 A CN1597182 A CN 1597182A CN A2004100748080 A CNA2004100748080 A CN A2004100748080A CN 200410074808 A CN200410074808 A CN 200410074808A CN 1597182 A CN1597182 A CN 1597182A
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China
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magnetic field
mold
generation device
molten steel
field generation
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CNA2004100748080A
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CN1299855C (en
Inventor
系山誓司
藤村俊生
铃木真
上原博英
松崎健
多田睦
三木祐司
山内章
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JFE Engineering Corp
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NKK Corp
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Priority claimed from JP2003307108A external-priority patent/JP4259232B2/en
Priority claimed from JP2003395818A external-priority patent/JP4411945B2/en
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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
    • 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
    • B22D11/14—Plants for continuous casting
    • 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
    • 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
    • B22D11/114—Treating the molten metal by using agitating or vibrating means
    • B22D11/115—Treating the molten metal by using agitating or vibrating means by using magnetic fields
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Continuous Casting (AREA)

Abstract

An ultra-low carbon steel slab having a carbon content of about 0.01 mass percent or less is produced by casting at a casting speed of more than about 2.0 m/min using a mold provided with a casting space having a short side length D of about 150 to about 240 mm and an immersion nozzle provided with discharge spouts each having a lateral width d, the ratio D/d being in the range of from about 1.5 to about 3.0. Accordingly, a ultra-low carbon steel slab can be obtained having superior surface quality without performing slab conditioning such as scarfing.

Description

Produce the method for ultra low carbon steel slab
Invention field
The invention relates to the method for producing the continuous casting ultra low carbon steel slab, particularly be specifically designed to the steel plate of making phone housing and great surface quality like about production.
Description of Related Art
Being used to make the steel plate as phone housing, is the technology that adopts deep draw, and/or makes it to form complicated shape with the method for distortion, must have good formability.Therefore use so-called " ultra-low-carbon steel ", its carbon content is reduced to alap degree.The carbon percentage composition of ultra-low-carbon steel be generally quality 0.01 or lower.In above-mentioned ultra low carbon steel slab, the cold-reduced sheet that is used to make phone housing especially has good surface appearance and colourability.
In the finish-rolling process of producing ultra-low-carbon steel, be through carrying out the operation that oxidation removes carbon content in the molten steel with oxygen.Thereby, also adopt the deoxidation step of removing molten steel institute's dissolved oxygen in oxidation operation, and use deoxidier such as aluminium, magnesium and titanium.In deoxidation step, the oxygen and the deoxidier reaction that are dissolved in the molten steel generate aluminium oxide, magnesia and titanium oxide, and institute's reaction of formation thing remains in the molten steel with the form of non-metallic inclusion.
With plate hot rolling and/or cold rolling one-tenth sheet metal the time,, will form unfavourable defects such as crack and/or shrinkage cavity at surface of thin steel sheet if exist above-mentioned non-metallic inclusion near the plate surface.
In casting process in molten steel surface in addition argon gas and casting powder, to prevent to provide to mold the immersion spray nozzle clogging of molten steel from funnel.The argon gas that is involved in the molten steel only is retained in the molten steel with the form of bubble, perhaps combines with the reaction product of above-mentioned deoxygenated process (below be referred to as " deoxygenation product ") and generates the bubble that is retained in the molten steel.Above-mentionedly either way may produce blemish.In addition, the casting powder that is added is retained in the molten steel, also can produce the formed blemish of similar deoxygenation product.
In the past, the common sheet material of continuous casting is promptly produced cold-reduced sheet through hot rolling without surface treatment.Yet to producing the sheet material of phone housing, about 1 to 4mm thick top layer part is removed, for example, carry out the field trash that scarfing removes the deoxygenation product, bubble, foundry flux, and the analog that can produce blemish after hot rolling carry out hot rolling and cold rolling then.
The scarfing of sheet material has reduced the output as raw-material sheet material as mentioned above, in addition, has also incured loss through delay operation unfriendly.Therefore, produce in the operation of sheet material, made the generation that a lot of trials prevent board surface defect, and these defectives are the reasons that cause defective on the above-mentioned surface of thin steel sheet at continuous casting installation for casting.
The basic thought of these trials mainly arrives (6) point based on following (1):
(1) sheet metal thickness increases, and cross-sectional area increases then, because the sheet material width is restricted when rolling, thereby has reduced casting rate (m/min).Therefore the time of staying of molten steel in mold increases and do not reduce productivity ratio, so chien shih such as deoxygenation product when having increased are cast powder, impurity such as bubble move on to surperficial next from the inside of mold molten steel.
(2) the used continuous casting installation for casting of casting has a vertical member, makes the deoxygenation product, and casting powder, bubble etc. can be better move on to surface and separation from the inside of mold molten steel.
(3) near trough plate, produce horizontal flowing, prevent that impurity in the molten steel is solidified shell and holds back (washing effect) with electromagnetic force.
(4) viscosity of control casting powder suitably is involved in possibility in the molten steel to reduce the casting powder.
The vibration of mold (vertical vibration) when (5) suitably controlling continuous casting, with the generation that reduces solidified shell corner angle in the mold (a kind of because oscillating component solidified shell to the oblique phenomenon of molten steel inclination), then reduce the deoxygenation product, casting powder, the amount that bubble etc. are trapped in corner angle.
(6), enter the bottom of mold with the molten steel that prevents to be mixed with the deoxygenation product with electromagnetic stirr or to entering molten steel the mold and apply electromagnetic force and remain in a standstill and control steel flow from immersing nozzle.
For example, in the disclosed technology of uncensored Japanese patent publication No.5-76993, carbon content is cast on continuous casting installation for casting less than 0.01% molten steel by weight, its longitudinal component be 20m or more than, casting rate be 1.0m/min or more than, surpass 200mm with 4ton/min or above output output thickness, width surpasses the sheet material of 900mm, and described powder viscosity be set at 1.0 the pool or more than, the inert gas speed that immerses nozzle be set at 1L/min or more than, the electromagnetic stirr along continuous straight runs acts in the molten steel zone dark from the trough plate to 1.5m, and speed is 15 to 40cm/sec.This technology is mainly based on above (1), (2), (3), (4) and (6) section content.
In addition, in the disclosed technology of uncensored Japanese patent publication No.7-155902, suitably control the vibration of mold, to restrain the generation of easily field trash being held back corner angle part wherein, these corner angle partly form in the plate surface initial solidification stage.This technology is mainly based on above (5) section content.
Yet still there are some problems in above technology.
Disclosed as uncensored Japanese patent publication No.5-76993, when the sheet material cross-sectional area increases, particularly thickness increases, and when casting rate surpasses 1.5m/min, also is not so good as the minimizing of expection near the plate surface by the defects count that field trash or analog caused.Though being the molten steel flow speed vm of trough plate part, its reason is controlled at optimum value with horizontal electromagnetic force, sheet metal thickness increases the back output and has increased, under the situation of the same casting rate (Vc) and sheet material width (W), the beam speed Vi that immerses nozzle has not increased when increasing with cross-sectional area.So though the variation of molten steel flow speed vm mean value is very little, after its change amount increased, foundry flux more had been rolled in the molten steel.This shows that the cleaning of plate surface is determined by near the molten steel flow speed the trough plate.
In addition, comparatively remarkable from the influence of immersing nozzle ejection steel flow, the housing growth of the short side of mold is postponed to a certain extent.Its reason is in the sheet material continuous casting installation for casting, when the molten steel beam advances mold, so-called " two spout " provides molten steel to distribute along the width of mold casting space equably, the ejection width of this pair of spout is less with respect to the short side length D (corresponding to sheet metal thickness) in the mold, and the flow velocity of molten steel changes on the sheet metal thickness direction.Therefore, the inhomogeneous impact of high flow rate molten steel meeting is along the solidified shell part of short side, and the growth of the above-mentioned solidified shell part of result is delayed.In addition, near the fluctuation of the molten steel flow speed fluctuation of the molten steel flow speed on the sheet metal thickness direction has also caused above-mentioned trough plate to a certain extent.
Next, in the disclosed technology of uncensored Japanese patent publication No.7-155902, in order to improve the plate surface quality, it is by casting rate, the negative strip time T that mold amplitude and vibration frequency are determined by adjusting the mold vibrational state, particularly reduces the mold amplitude and increases the mold vibration frequency, be controlled in the particular range, can produce following problem this moment.
When the casting rate of ultra-low-carbon steel is higher than 2.0m/min, when the mold vibration frequency is higher than 185 times/min, the molten steel surface plane can take place suddenly and the anomaly that changes significantly, although this phenomenon is not frequent being observed.Therefore, foundry flux may be rolled in the molten steel, or is solidified shell and holds back, cause then cast the steel-sheet blemish.So, when casting rate surpasses 2.0m/min, produce because the blemish that foundry flux caused through regular meeting.Thereby can not stably produce product with high-quality surface.
As mentioned above, when ultra-low-carbon steel sheet material is used to make phone housing or like, be higher than the high speed casting of 2.0m/min with speed, sheet material is not being carried out under the situation of scarfing, current technology can't stably be produced high-quality sheet material.
Thereby if provide a kind of continuous cast method for preparing Ultra-low carbon sheet material, this method need not to sheet material carry out scarfing just can with in addition the casting rate that is higher than 2.0m/min stably produce the sheet material of great surface quality, this is very useful.
Summary of the invention
The invention provides a kind of method of producing ultra-low-carbon steel sheet material, comprising:
A kind of continuous casting installation for casting is provided, comprises that it is about 150 molds to the casting space of about 240mm that bond length D is installed, and the immersion nozzle that at least one transverse width is the spout of d is installed, wherein D/d ratio arrives in about 3.0 the scope about 1.5;
By immersing nozzle molten steel is incorporated in the mold; And
To be higher than the speed casting molten steel of 2.0mm/min, coming production carbonaceous amount percentage composition is 0.01% or lower ultra-low-carbon steel sheet material in continuous casting installation for casting.
The sheet material continuous cast method preferably can also comprise with 185 times/min or lower frequency vibration mold.The molten steel surface plane is reduced with the possibility that the anomaly that changes significantly produces suddenly.Therefore, when mold during with 185 times/min or lower frequency vibration, the resonance that is taken place between molten steel surface and the mold vibration has reduced, so the defect level that is caused by flux has just reduced.
Casting rate can be about 2.4m/min or faster.The corner angle degree of depth becomes about 0.7mm or littler, just casting rate for about 2.4m/min or when faster the degree of depth of impurity trapped be no more than the corner angle degree of depth.Therefore casting rate is preferably set to 2.4m/min or faster.
As above-mentioned immersion nozzle, generally use cylindrical nozzle (so-called " straight type nozzle ") or two spout nozzle, the front end sealing of this pair spout nozzle, and at the spout that two sub-circulars are installed facing to two minor faces of mold.
In conjunction with sheet metal thickness, when immersing nozzle durability and required flow rate and considering product quality, bond length D is preferably about 2.1 to about 2.9 to the D/d ratio that immerses nozzle spout transverse width d.
Above-mentioned ultra-low-carbon steel sheet material is preferably as the raw material as the cold-reduced sheet of producing phone housing.
Above-mentioned sheet material continuous cast method comprises further that preferably the molten steel in the mold casting space is applied electromagnetic force to remain in a standstill.Following paragraph (A) to (C) applies the method for optimizing that electromagnetic force remains in a standstill as being:
(A) adopt the static magnetic field run through mold thickness and roughly to cover whole mold to produce electromagnetic force and remain in a standstill, wherein used upper end magnetic field generation device and lower end magnetic field generation device.The upper end magnetic field generation device be installed in the mold top that comprises the molten steel surface plane, the lower end magnetic field generation device be installed in the upper end magnetic field generation device below.Immerse nozzle and be installed between the magnetic field generation device of top and bottom, immersion depth is set between about 200 to about 350mm.
(B) use the upper end magnetic field generation device be installed in the mold top that comprises the molten steel surface plane, in running through the whole mold of mold thickness, overlapping static magnetic field and the AC magnetic field of applying produces electromagnetic force and remains in a standstill.Immerse the lower end that nozzle is installed in magnetic field generation device, immersion depth is set between about 200 to about 350mm.
(C) electromagnetic force remains in a standstill and produces in the following way: use the upper end magnetic field generation device, overlapping static magnetic field and the AC magnetic field of applying in running through the whole mold of mold thickness, and, in running through the whole mold of mold thickness, apply static magnetic field by using lower magnetic field generation device.The upper end magnetic field generation device be installed in the mold top that comprises the molten steel surface plane, the lower end magnetic field generation device be installed in the upper end magnetic field generation device below.Immerse nozzle and be installed between the magnetic field generation device of top and bottom, immersion depth is set between about 200 to about 350mm.
Picture specification
Fig. 1 represents the each side according to the present invention, the relation between the casting rate and the corner angle degree of depth;
Fig. 2 represents the each side according to the present invention, deposits trapped substance apart from the relation between the amount of plate surface degree of depth h and trapped substance, and this relation obtains under different casting rates;
Fig. 3 represents the each side according to the present invention, deposits trapped substance apart from the relation between the amount of trough plate distance L and trapped substance, and this relation obtains under different casting rates;
Fig. 4 represents the each side according to the present invention, and sheet metal thickness and casting rate produce the influence of protuberance amount to minor face;
Fig. 5 represents the each side according to the present invention, and sheet metal thickness is to the influence of surface defects of products ratio;
Fig. 6 represents the each side according to the present invention, and casting rate is to the influence of surface defects of products ratio;
Fig. 7 A is respectively the employed suitable mold of each side according to the present invention to 7C, and the schematic diagram that has the mould, for continuous casting of magnetic field generation device;
Fig. 8 is each side according to the present invention, adopts the schematic diagram that exchanges an example of oscillating magnetic field; And
Fig. 9 is each side according to the present invention, adopts the schematic diagram that exchanges an example of travelling-magnetic-field.
Detailed content
We disclose and have suitably controlled casting rate, mould, for continuous casting casting space bond length D, bond length D is to immersing the ratio D/d of nozzle spout transverse width d, and suitably control the vibration frequency of mold when needed, or in MOLTEN STEEL FLOW, use the remain in a standstill sheet material of the content of production Ultra-low carbon preferably of electromagnetism effectively.
The each side according to the present invention, this steel are that carbonaceous amount percentage composition is about 0.01% or lower so-called " ultra-low-carbon steel ".Except other composition of carbon is not particularly limited.But first-selected is a kind of steel that can produce phone housing and like through deep draw technology.An advantage of the invention is, the defective that the steel of being produced are not almost not caused by field trash, field trash almost can not be present in the zone from the plate surface to the certain depth, should not need to be stripped from the zone in subsequent handling.Ultra-low-carbon steel can have many advantages of the present invention thus, in ultra-low-carbon steel, is easy to produce thing as deoxygenation and be formed in fine-processing technique as non-metallic inclusions such as aluminium oxide.
Typical composition in the ultra-low-carbon steel (not comprising composition carbon), below describe for example: the silicon of quality percentage composition about 0.01% to about 0.04%, the manganese of quality percentage composition about 0.08% to % about 0.20, the phosphorus of quality percentage composition about 0.008 to about 0.020, the sulphur of quality percentage composition about 0.003% to about 0.008%, the aluminium of quality percentage composition about 0.015% to about 0.060%, the titanium of quality percentage composition about 0.03% to about 0.080%, the niobium of quality percentage composition about 0.002% to about 0.017%, and the boron of quality percentage composition 0 to about 0.0007%.
According to continuous casting installation for casting of the present invention is a kind of continuous casting installation for casting of producing steel board, can vertically select arbitrarily in deflection continuous casting installation for casting and the crooked continuous casting installation for casting from vertical continuous casting installation for casting.But carry in the equipment in above institute, vertically the deflection continuous casting installation for casting is especially favourable with regard to productivity ratio and product quality.
Mold is so-called " sheet material mould, for continuous casting ".Its bond length is about 150 to about 240mm.The long edge lengths of mold is not done particular restriction, preferably is substantially equal to the length (especially for the cold-reduced sheet of mobile phone) of common cold-reduced sheet, such as about 900 to 2, and 200mm.The sheet metal thickness of bond length when producing sheet material, long edge lengths is corresponding to the sheet material width.
Vertically the height of mold is not done particular restriction.But because formed solidified shell has certain thickness, even if when casting rate surpasses 2.0m/min, the casting sheet metal can not produce protuberance by mold yet, so highly preferably be set at about 800 to about 1000mm.
A kind of spout that immerses is injected into molten steel the space of mold from funnel as nozzle.The material that immerses nozzle can be the common material as aluminium oxide-graphite.But material has more than and is limited to this.
In addition, about immersing its shape of nozzle, can be the cylindric nozzle of generally being mentioned (so-called " straight type nozzle "), perhaps two spout nozzles, the front end sealing of this pair spout nozzle, and at the spout that two sub-circulars are installed facing to two minor faces of mold.The shape of cross section of spout can be circular, square, or rectangle (laterally longer, perhaps vertically longer), and do not have particular restriction, as long as satisfying the type of situation of the present invention, can use spout Breadth Maximum d.
Also have based on following reason, casting rate is set at more than the 2.0m/min.Casting rate is preferably set to 2.4m/min or faster.
When adopting electromagnetic force that the molten steel in the continuous casting installation for casting mold casting space is remained in a standstill, as a kind of method for optimizing, for example, what uncensored Japanese patent publication No.2-284750 mentioned applies static magnetic field along the long side width in whole mold, what perhaps uncensored Japanese patent publication No.57-17356 mentioned only applies static magnetic field in molten steel ejection position.Here the main thought of JP No.2-284750 and JP No.57-17356 can be combined as a reference.
Be set at about 150 to about 240mm according to the present invention in the bond length (sheet metal thickness) of mold casting space, casting rate is set at 2.0m/min when above, and some different phenomenons of generation are understood in casting.Next, with explanation some new discoveries about the above elephant of withdrawing deposit.Below with field trash, bubble and analog are called " impurity ".
(1) zone of minimizing impurity trapped
The formation of trough plate part initial solidification shell, promptly said " corner angle " are set at more than the 2.0m/min at casting rate Vc, and preferably 2.4m/min or when faster will significantly be restrained.We think that its reason is any constant depth under the molten steel surface plane, the thickness of the solidified shell that forms can and reduce along with casting rate Vc increase, because the influence of molten steel static pressure, the power of effect mould side is greater than the power that corner angle tilt to molten steel, and the latter is caused and depend on its thickness by the thermal contraction of solidified shell.In addition when sheet metal thickness reduces, reducing at the absolute value " sheet metal thickness * temperature difference * thermal coefficient of expansion " of thickness direction upper casing amount of contraction, housing can further obtain restraining to the inclination of molten steel side, and restraining the effect that corner angle tilt at last can be more obvious.
Fig. 1 has represented the influence of casting rate to the corner angle degree of depth.The bond length (sheet metal thickness) that is higher than about 2.0m/min and mold casting space in casting rate is for about 240mm or still less the time, and the corner angle degree of depth becomes 1mm or littler.And for about 2.4m/min or when faster, the corner angle degree of depth becomes 0.7mm or littler in casting rate.
(2) absorption of supression impurity
Be accompanied by process of setting, owing to concentrate on the segregation of the dissolved matter on the solidified shell interface, produced surface tension gradient, the power that this gradient produced makes that impurity is easy to be absorbed or hold back on the solidified shell interface.Therefore attempted reducing the method for the concentration of dissolving elementary sulfur or titanium, the power that improves absorption or impurity trapped has been produced tangible influence.But in some cases, change composition and can have disadvantageous one side,, when reducing titanium, can reduce quality as when reducing sulphur, increasing cost.
According to the present invention, increase casting rate Vc can reduce the power in absorption of solidified shell interface or impurity trapped.Promptly when casting rate Vc is high, as be more than the 2.0m/min, because reduced in the amount of solidifying of trough plate part, the segregation amount has also reduced, so attract the surface tension gradient of impurity also to reduce.So the impurity level that is absorbed or is trapped in the solidified shell avris has also reduced.
(3) minimizing of impurity trapped thickness
Fig. 2 is illustrated in the plate surface part, holds back relation between degree of depth h and the impurity trapped amount apart from the plate surface of impurity trapped.In addition, Fig. 3 represents the impurity trapped amount and apart from the relation between trough plate (molten steel surface) distance L, this value is held back degree of depth h by conversion apart from plate surface and obtained:
h＝k(L/Vc)1/2
In this equation, Vc represents casting rate, and solidifying constant k is 20mmmin -1/2
As seen, it is in the zone of 20mm that impurity is trapped in from the molten steel surface to the degree of depth by housing from Fig. 2 and 3.In addition, holding back the degree of depth and reduce when casting rate increases, when casting rate Vc is 2.0m/min when above, is 1mm or still less apart from the degree of depth of holding back of plate surface.
When holding back the degree of depth is 1mm or still less the time, though impurity is held back by housing, is producing in the subsequent technique of product by hot-rolled process and cold rolling process etc., and these impurity are stripped from and the surface of thin steel sheet oxide skin of casting is eliminated together.The sheet material processing can be do not carried out thus and just flawless product can be obtained.In addition, be 2.4m/min or when above in casting rate, corner angle thickness becomes 0.7mm or still less, holds back degree of depth h and also can not surpass corner angle thickness.So casting rate preferably be set at 2.4m/min or more than.
(4) impurity is held back the minimizing of possibility
Impurity is easy to be solidified shell and holds back the zone from molten steel surface to degree of depth 20mm, and when casting rate increased, solidified shell also reduced in this regional time of staying.Therefore, even if contain same impurity level in molten steel, the possibility that impurity is trapped in the solidified shell has also reduced.For example, when Vc is 3.0m/min, the possibility that impurity is held back has dropped to half when Vc is 1.5m/min.
(5) prevent the preferred mold vibration frequency that the molten steel surface plane changes suddenly
When being higher than the speed casting of about 2.0m/min with Vc, because the thickness of solidified shell further reduces in the mold, thus produced the protuberance phenomenon, although this phenomenon is not clearly.The protuberance phenomenon is exactly solidified shell is pushed to mold under the influence of molten steel static pressure a avris.In the protuberance phenomenon, when the case temperature height, and the type of steel is mild steel, or when comparing the steel with less casing rigidity with the steel of other type, the speed of protuberance (being pushed to mold) becomes than mold vibration velocity height.Mold has a bullet to compensate the volume contraction that is caused by solidification shrinkage and/or thermal contraction usually, when this mold vertical vibration, is accompanied by mold decline solidified shell and measures δ with protuberance bProtuberance.On the contrary, be accompanied by mold and rise, mold is to be substantially equal to δ bThrust δ pPush housing to and make it protuberance.The simple calculating of process, less by the molten steel surface plane variation that stereomutation causes as can be known, approximately less than 1mm.But when above-mentioned phenomenon repeated, the vibration meeting of the vibration on molten steel surface plane and mold was resonated each other.So issue cast steel water surface plane suddenly and the anomaly of wide variation in a few cases.Use the vortex patern flat surface sensor to be not easy to detect this phenomenon, because this anomaly occurs in the limit portion of mold at molten steel surface.But we have found this phenomenon when vibration performance distortion in time of research casting steel board.Particularly, when casting rate is more than the 2.0m/min, and the mold vibration frequency is higher, and when for example being higher than about 185 times/min, above-mentioned anomaly ratio is easier to observe.Thereby foundry flux may be rolled in the molten steel and may be trapped within the solidified shell, produces defective on casting steel-sheet surface then.In view of the above, be about 2.0m/min when above, will increase suddenly by the blemish that foundry flux caused in casting rate.The final blemish that reduces can become very difficult.
But, from the mold vibration frequency and and the flux related defects account for relation between the overall defect ratio, promptly as the ratio of representing unexpected anomaly incidence index, casting rate Vc can find to be set at about 185 times/min or still less the time, even if also can prevent above-mentioned anomaly when to be 2.0m/min above effectively when the mold vibration frequency.
In addition, the setting of the lower limit of mold vibration frequency can consider to reduce the zone of impurity trapped, thereby can not increase the corner angle degree of depth, also will consider the constraint fracture that the minimizing that prevents lubricant properties in mold (mold flux consumption) causes.For example, preferably about 0.02 second of negative strip time or more than, negative strip length is preferably about 0.1mm or longer.The negative strip time is the characteristic value of definition mold vibration state, and expression mold decrease speed is higher than a period of time of casting sheet metal decrease speed.The negative strip lengths table is shown between negative strip time internal cast and the casting sheet metal, and mold is through the casting steel-sheet ultimate range of institute's drawing.The vibrational waveform of supposing mold satisfies π Sf/Vc＞1 during for sinusoidal waveform, and wherein S represents the amplitude of mold, and f represents the mold frequency, and Vc represents casting rate.For example, when Vc equals 2.0m/min, when S equals 9mm, the lower limit of mold frequency f be 71cpm (inferior/min), when S equals 5mm, lower limit be 127cpm (inferior/min).The vibrational waveform of mold need not be defined as sinusoidal waveform.Equally, consider the particularity and the controllability of continuous casting installation for casting vibration state, the lower limit of frequency and waveform can be appropriately determin.
(6) prevent minor face protuberance (reason of mold continuous casting space bond length capping)
Though the immersion nozzle that uses satisfies bond length (sheet metal thickness) D of mold casting space to immersing the D/d ratio of nozzle spout transverse width d, when bond length was too big, casting rate Vc surpasses 2.0m/min, and problem can take place.Particularly, the minor face protuberance can cause sheet material shape defect and/or fracture.On the contrary, when bond length is little, when casting rate Vc is high,, thereby produce the dangerous less of fracture because the protuberance through mold sheet material minor face that the molten steel static pressure is caused can be reduced.
But as shown in Figure 4, when bond length (being sheet metal thickness) surpasses 240mm, though casting rate is 2.4m/min, so owing to increase sheet metal thickness and increased from the speed that immerses nozzle molten steel that spout sprays, electromagnetism caused second flow velocity that remains in a standstill has also increased.Then be not easy to restrain the delay of minor face housing growth.The minor face protuberance of mold bottom becomes obviously, thereby has increased the danger (protuberance amount 10mm or more) that produces fracture.
In addition, when bond length (being sheet metal thickness) surpassed 240mm, based on above identical reason, the fluctuation on molten steel surface plane was aggravated by the refluence and time stream of the molten steel jet flow that the minor face from solidified shell flows out, and easily foundry flux was involved in and held back.In addition, because the increase of sheet metal thickness, molten steel is easy at the trough plate position particularly immersing the generation stagnation of nozzle place.The result as shown in Figure 5, the quantity of board surface defect and product defects has increased.
(7) mold continuous casting space bond length is set the reason of lower limit
Mold continuous casting space bond length (sheet metal thickness) had better not be less than about 150mm, and reason is as follows.
On the angle of molten steel surface plane controllability, see, can not obtain above effect (1) when too much when the sheet material cross-sectional area reduces.Its reason is when changing the casting amount, and the fluctuation on molten steel surface plane has increased when producing comparatively large cross-sectional area sheet material.And because molten steel produces ripple, the degree of depth is that the generation of 1mm or more corner angle increases than regular meeting.In addition because the fluctuation on molten steel surface plane is easy to foundry flux is involved in and hold back (referring to Fig. 5).In addition, the external diameter of common immersion nozzle is determined by the sum of considering the determined wall thickness of durability (about 20mm or more), its internal diameter (about 70mm is to about 130mm) determines, be to guarantee that (150mm is thick from 5.4ton/min, 2200mm is wide, speed Vc is 2.1m/min or faster) to the throughput of 14.5ton/min (240mm is thick, and 2200mm is wide, and speed Vc is 3.5m/min or faster).In this case, when bond length D (sheet metal thickness) too hour, the distance too little (less than 20mm) on the long limit of nozzle outer wall and solidified shell, therebetween mobile becomes inhomogeneous and can cause the generation of longitudinal crack.Under extreme case, solidified shell contacts with nozzle and by adhesion, causes rupturing.Therefore the setting of bond length D (sheet metal thickness) is not less than 150mm (the whole outer wall thickness 40mm of internal diameter 70mm+ (20 * 2)+nozzle outer wall and solidified shell grow limit apart from 40mm (20 * 2)).
In addition, the long edge lengths of mold casting space (sheet material width) is not particularly limited, can equals the width (especially for the cold-reduced sheet of mobile phone) of common cold-reduced sheet.Length is preferably about 900 to 2200mm.
Mold vertically highly is not particularly limited.But, highly preferably be set at about 800 to 1000mm, because solidified shell must form with certain thickness, the steel board of casting so just can not swell during by mold, even if casting rate also is like this when 2.0m/min is above.
(8) mold casting space bond length D is to the optimization of the D/d ratio of spout transverse width d.
When molten steel is decelerated, extend at width from the molten steel that immerses the ejection of nozzle spout, up to impacting the minor face housing.But the deceleration and the degree of scatter that impact the jet velocity of minor face housing molten steel depend on the sheet material width W, casting rate Vc and D/d ratio.When the width of jet d that immerses nozzle with respect to mold casting space bond length (sheet material width) D too hour (D/d is too big), at D, when Vc and W increase, the reduction of the ratio of the width of molten steel high speed impact minor face shell area and sheet metal thickness (minor face width).So the growth of solidified shell becomes inhomogeneous and is easy to disturbed.Equally, when increasing, the thickness of solidified shell may rupture when too many.On the other hand, when the width of jet d that immerses nozzle with respect to mold casting space bond length (sheet material width) when D is too big (D/d is too little), at D, when Vc and W increase, because the molten steel injection stream impacted the long limit of solidified shell earlier before impacting the solidified shell minor face, so the growth on the long limit of solidified shell is disturbed, thereby cause the generation of transversal crack and/or oblique crackle.In addition, under the too little certain situation of shell thickness, can rupture.In above two kinds of situations, be difficult to observe the influence of sheet material width.
In addition, molten steel rises after impacting the solidified shell minor face, flow at long edge molten steel surface then, when exceeding optimum range when D/d ratio because in the velocity variations of sheet metal thickness direction, near the trough plate change in flow also can be subjected to influencing to a certain extent, and the mold that the is involved in dosage of fluxing also can increase.
By guaranteeing that the spout maximum lateral width d that throughput determined from about 5.4ton/min to about 14.5ton/min preferably is equal to or less than the internal diameter (70 to 130mm) of the immersion nozzle of being considered by wearability.Thus, best bond length (sheet metal thickness) D (150 to 240mm) of mold casting space and spout transverse width d (70 to 130mm) can determine D/d ratio.When being cast to 300 minutes for a long time or when longer, whole outer wall thickness is preferably set to 25mm * 2=50mm or more.In addition, the distance between mold and the nozzle is preferably set to 40mm or more to guarantee that quality is more stable.Promptly removing the internal diameter desired thickness is 50+40 * 2=130mm.On the other hand, when casting in the short time, whole outer wall thickness can be set at 20mm * 2=40mm, and the distance between mold and the nozzle can be set at about 20mm.Promptly removing the internal diameter desired thickness is 40+20 * 2=80mm.
In table 1, represented the investigation result of D/d ratio to the product quality influence.D/d ratio is preferably set between 1.5 to 3.0.But when considering best sheet metal thickness, when the durability of immersion nozzle and required flow rate, D/d ratio more preferably is set between about 2.1 to about 2.9.
Table 1
Sequence number Sheet metal thickness D (mm) Sheet material width W (mm) Casting rate Vc (m/min) Immerse nozzle spout transverse width d (mm) ??D/d Mold amplitude s (net amplitude) (mm) Mold vibration frequency f (inferior/minute) ???tn *???(s) Electromagnetism remains in a standstill Plate surface crackle number (〉=5mm) (/m 2????) Cold-reduced sheet surface defect rate (%) Rupture Remarks
????1 ????220 ?1100-1800 ????2.4 ????60 ??3.67 ????7 ??160 ??0.098 Class1 ????65 ???2.1 At minor face fracture BO Comparative Examples
????2 ????220 ?1100-1800 ????2.4 ????70 ??3.14 ????7 ??160 ??0.098 Class1 ????23 ????0 Not Comparative Examples
????3 ????220 ?1100-1800 ????2.4 ????75 ??2.93 ????7 ??160 ??0.098 Class1 ????0 ????0 Not Embodiment
????4 ????220 ?1100-1800 ????2.4 ????80 ??2.75 ????7 ??160 ??0.098 Class1 ????0 ????0 Not Embodiment
????5 ????220 ?1100-1800 ????2.4 ????130 ??1.69 ????7 ??160 ??0.098 Class1 ????5 ????0 Not Embodiment
????6 ????235 ?1100-1800 ????2.4 ????88 ??2.67 ????7 ??160 ??0.098 Type 2 ????0 ????0 Not Embodiment
????7 ????235 ?1100-1800 ????2.4 ????100 ??2.35 ????7 ??160 ??0.098 Type 2 ????0 ????0 Not Embodiment
????8 ????235 ?1100-1800 ????2.4 ????120 ??1.96 ????7 ??160 ??0.098 Type 2 ????1 ????0 Not Embodiment
????9 ????235 ?1100-1800 ????2.4 ????160 ??1.47 ????7 ??160 ??0.098 Type 2 ??≥100 ???23.5 At long limit fracture BO Comparative Examples
Class1: EMBR type 2:EMLS tn *=60/f-tp tp=60/ (π Sf) * acos (1000Vc/ π Sf) COMP.EX: Comparative Examples
(9) electromagnetic force remains in a standstill
When casting rate Vc for about 2.4m/min or when above, perhaps throughput for about 7ton/min or more for a long time though D/d passes through optimization, can be observed the increase a little of product defects rate.
As mentioned above, preferably can be again remain in a standstill, under the effect that remains in a standstill, can make operation more stable and can improve quality with electromagnetic force.。
For the method for using electromagnetic force to remain in a standstill, the technology that can adopt above-mentioned uncensored Japanese patent publication No.2-284750 and JP No.57-17356 to be announced.
Schematically show in the 7C at Fig. 7 A and to be applicable to the mould, for continuous casting that has magnetic field generation device of the present invention.
Fig. 7 A represents that magnetic field generation device 1 is installed in the mold top that comprises the molten steel surface plane and preset distance place thereunder, to apply static magnetic field dividing two sections.Fig. 7 B represents that 2 of magnetic field generation devices are installed in the mold top that comprises the molten steel surface plane, applies the magnetic field of static magnetic field and AC magnetism place stack.Fig. 7 C represents that magnetic field generation device 2 is installed in the mold top that comprises the molten steel surface plane, and applying the magnetic field static and stack of AC magnetism place, magnetic field generation device 1 is installed in magnetic field generation device 2 below preset distances and sentences and apply static magnetic field.
In above-mentioned various magnetic field generation devices, when being used as the device that produces static magnetic field, the magnetic density value of D.C. magnetic field is preferably set to about 1000 to about 7000 Gausses.This value can be applied to two kinds of situations, promptly when two devices are installed at two ends up and down and only when device of lower end installation.
Have two kinds for AC magnetic field, promptly exchange oscillating magnetic field and exchange travelling-magnetic-field, in the present invention, these two kinds are all preferably used.
Fig. 8 represents to exchange phase place alternating current almost respect to one another in the oscillating magnetic field and acts on magnetic field in the adjacent coil, perhaps the alternating current of same phase acts on the magnetic field in the coil direction coil respect to one another, inserts in adjacent coil like this and has produced magnetic field.When exchanging oscillating magnetic field and D.C. magnetic field mutual superposition, can reduce the local flow in the molten steel.Mark 3 expression dc coils in the drawings, mark 4 expression AC coils, mark 5 expression molds, mark 6 expression molten steel (oblique line is partly represented the zone that flow velocity is slow).
In addition, exchanging travelling-magnetic-field is that alternating current by 360 °/N of upset acts on a kind of magnetic field on the adjacent N coil.As shown in Figure 9, N=3 (120 ° of phase differences) and can obtain high frequency in general the use.As mentioned above, when exchanging oscillating magnetic field and D.C. magnetic field mutual superposition, can reduce local flow in the molten steel.
When adopting the aforesaid magnetic field generation device that can produce AC magnetic field, the magnetic density value of its AC magnetic field is preferably set to about 100 to about 1000 Gausses, and the frequency of oscillating magnetic field is preferably set to about 1 to about 10Hz.
Also have, when adopting the device that can produce static magnetic field and AC magnetic field stack, the magnetic density value of its D.C. magnetic field is preferably set to about 1000 to about 7000 Gausses, and the magnetic density value of its AC magnetic field is preferably set to about 100 to about 1000 Gausses.
As mentioned above, with the electromagnetic force of magnetic field generation device molten steel is formed during continuous casting and remain in a standstill.Reason below in conjunction with restriction working condition of the present invention illustrates the aforesaid new discovery of casting process in mold.
(10) nozzle immersion depth (distance of upper end from the molten steel surface to the spout)
Circulation state in the mold in the molten steel changes according to the nozzle immersion depth and changes.Particularly, very fast from the speed that immerses the nozzle outflow when casting speed is high, so its immersion depth will be optimized.When immersion depth too hour, the flowing velocity of molten steel surface is too high.Thereby be involved in flux easily.On the other hand, when immersion depth was too big, the flowing velocity of molten steel surface was too slow, and the clean result at solidified shell interface weakens.Thereby bubble and field trash are held back easily.
So, based on above consideration, the optimization of nozzle immersion depth is studied, find that the scope of nozzle immersion depth is set in about 200mm to about 350mm.
In addition, for the material that immerses nozzle as mentioned above, preferably use common material as aluminium oxide-graphite.But material has more than and is limited to this.
For immersing nozzle as mentioned above, generally use cylindrical nozzle or two spout nozzle, the front end sealing of this pair spout nozzle, and at the spout that two sub-circulars are installed facing to two minor faces of mold.The shape of cross section of spout can be circular, and square, or rectangle (laterally longer, perhaps vertically longer), and do not have particular restriction can use as long as Breadth Maximum d satisfies the type of the nozzle configuration that the present invention the following describes.
As already explained, flux is involved in or field trash when swimming in the molten steel, more than (5), (6) and (8) section also being involved in of foundry flux can be reduced to minimum degree, more than (2) and (4) section can restrain impurity and be trapped in the solidified shell, even when impurity is trapped, its apart from the degree of depth of molten steel surface also can owing to above (1) and (3) thereby section becomes the more shallow defective of avoiding.Thus, in process of production, particularly in the sheet material heating process, sheet material top layer impurity peel off and removal can become easy.
Therefore, by above (6), (7), (8) and (9) section can stably reach above effect, and obtains high productivity ratio.
Example 1
The continuous casting installation for casting of being prepared with the condition among table 2A and the 2B carries out continuous casting, wherein there is different bond length in the continuous casting space of mold, 110mm (carrying out the continuous casting installation for casting test) is arranged, 200,215,220,235, and the sheet material type of 260mm different-thickness such as (carrying out the buckling production of continuous casting installation for casting), and 400mm (carrying out continuous casting installation for casting production) is arranged, with 900 to 2200mm different sheet material width such as (carrying out the continuous casting installation for casting buckling produce).In this operation, the height of mold is 900mm (carrying out the continuous casting installation for casting test) and 700mm (carrying out the continuous casting installation for casting test), immersing nozzle is two spout nozzles of being made by aluminium oxide-graphite material, its wall thickness is 25mm, nozzle configuration is square (this moment, sheet metal thickness was 220mm or still less) or circular (this moment, sheet metal thickness surpassed 220mm), the ejection angle is 20 ° of steady state values downwards, and nozzle immersion depth (distance of upper end from the molten steel surface to the spout) is set at 200 to 250mm.The setting temperature of the foundry flux material that uses is 1000, and viscosity was 0.05 to 0.2Pa.s (0.5 to 2.0 pool) at 1300 o'clock, basicity (CaO/SiO 2) be 1.0.In addition, the degree of superheat of molten steel is set at 10 to 30 in the funnel.The composition that also has molten steel, it has the composition of ultra-low-carbon steel, carbonaceous amount percentage composition is 0.0005% to 0.0090%, and siliceous amount percentage composition is less than 0.05%, and manganese quality percentage composition is less than 0.50%, phosphorus quality percentage composition is less than 0.035%, sulphur quality percentage composition is less than 0.020%, and aluminium quality percentage composition is 0.005% to 0.060%, and titanium quality percentage composition is less than 0.080%, niobium quality percentage composition is less than 0.050%, and boron quality percentage composition is less than 0.0030%.The mold vibrational waveform is a sinusoidal waveform in addition.
Tested the maximum minor face protuberance amount of the dissimilar sheet materials of producing, the maximum corner angle degree of depth, plate surface greatest drawback amount and whether produce fracture.The result is illustrated in the table 3, and maximum minor face protuberance amount is preferably 10mm or still less, and more excellent is 5mm or still less.The maximum corner angle degree of depth is preferably 1mm or still less, and more excellent is 0.7mm or still less.
In addition, in table 3, also listed the measurement result (sheet metal thickness is 0.8mm) of cold-reduced sheet blemish ratio, described cold-reduced sheet obtains by following steps: above-mentioned steel plate was heated 2 to 2.5 hours down at 1100 to 1200 ℃ respectively, carry out hot rolling then, cold rolling and anneal according to commonsense method at last.
In addition, studied and summed up the influence of casting rate to board surface defect and cold-reduced sheet blemish.Its result as shown in Figure 6.
In subsequent handling, plate surface is ground away 1mm, and with the #1000 sand papering, with the mixed liquor corrosion of hydrochloric acid and hydrogen peroxide, the maximum quantity of board surface defect is that observed bubble on the unit are (diameter 0.2mm or bigger) is (individual/m then 2), the number of aluminium oxide mass (diameter 500 μ m or bigger) and slag (comprising foundry flux, diameter 0.5mm or bigger).
In addition, the blemish of cold-reduced sheet ratio is a ratio, is the defects count on the percentage basis, as by watering the scratch that is cast as and the chip ratio to whole defectives.Defects count is that top and the bottom end surface every 1000m measured on cold-reduced sheet.
When the fracture of at least one place took place in the casting, the generation of fracture was "Yes" under each condition.
In addition, electromagnetic force remain in a standstill " Class1 " refer to bottom end vicinity at mold and be applied to static magnetic field generation device (EMBR) in the whole mold, electromagnetic force remain in a standstill " type 2 " refer to immersing nozzle spout place and be applied to static magnetic field generation device (EMLS) in the whole mold, the technology that " Class1 " of employing and " type 2 " are announced based on uncensored Japanese patent publication No.2-284750 and JP No.57-17356 respectively.
Negative strip time tn is the characteristic value of definition mold vibration state, and expression mold decrease speed is higher than a period of time of casting sheet metal decrease speed.From table 3 and Fig. 6 as can be seen, when casting sheet material according to the present invention, or even higher in casting rate, when surpassing about 2.0m/min, the board surface defect degree is lighter, does not almost detect the cold-reduced sheet blemish, even if its quantity of defectiveness also seldom.
From above-mentioned example as can be seen, according to the present invention, preferably can optimize process conditions to reach following condition:
(1) by the molten steel static pressure relative force that the mold wall produces is increased, acts near the shell that freezes solidly on the mold molten steel surface,
(2) field trash on the interface of solidified shell, slag, the absorption of flux and bubble obtains restraining, and the possibility of impurity trapped reduces, and
(3) be trapped into that the degree of depth of impurity reduces as much as possible in the solidified shell.
Thereby, even under high speed, cast, as still can obtain high production rate and stable operation when being higher than about 2.0m/min, need not the high-quality sheet material that surface treatment just can be provided for making the cold-reduced sheet of phone housing.
Example 2
The molten steel (about 300 tons) that fusing and process RH handle in converter, produce sheet material by the continuous casting installation for casting continuous casting, wherein continuous casting installation for casting is equipped with the magnetic field generation device of Fig. 7 A in the 7C, the composition of molten steel is: carbonaceous amount percentage composition is 0.0015%, siliceous amount percentage composition 0.02%, manganese quality percentage composition 0.08%, phosphorus quality percentage composition 0.015%, sulphur quality percentage composition 0.004%, aluminium quality percentage composition is 0.04%, titanium quality percentage composition 0.04%, all the other are iron and other unavoidable impurities.Working condition in this example is listed in the table 2.Immersing nozzle is that nozzle configuration is square two spout nozzles, and spraying angle downwards is 15 °.
Segregation and the non-metallic inclusion and the cold rolling back blemish that causes by foundry flux of plate surface have been measured then.Measurement result is listed in the table 3.
Surface segregation is by the every 1m of range estimation behind sheet material grinding and etching work procedure 2Segregation quantity infer.In addition, non-metallic inclusion extracts from the place of 1/4th degree of depth below the casting surface of thin steel sheet with the particulate extraction method.Measure the weight of field trash then.Also have, the coil surface defective of cold rolling formation is through range estimation, and sampling is also analyzed.Can obtain the defects count that causes by flux.For purpose relatively, the surface segregation that is caused by flux, field trash amount and defects count are reduced to index, the worst result who obtains in all conditions is taken as index 10.Each result satisfies on the basis of linear dependence hypothesis ratio to the worst result at them.
In table 3 as can be seen, according to the present invention, work as casting rate, the continuous casting space bond length D of mold, the nozzle immersion depth, bond length D is suitably controlled the ratio D/d that immerses nozzle spout transverse width d simultaneously, and the molten steel in the mold is adopted suitably electromagnetism viscous flow, surface segregation amount then, non-metallic inclusion amount and the defect level that has the casting auxiliary agent to cause can reduce.
When the intensity of oscillating magnetic field was too high, the flux that is involved in molten steel surface increased, and caused surface quality to descend.In addition, when frequency was too high, magnetic field can not be caught up with in the molten steel surface plane, and the clean result of solidified shell is weakened, and can cause number of bubbles and inclusion defects to increase.
Table 2A
Sequence number Bond length (sheet metal thickness) D (mm) Sheet material width W (mm) Casting rate Vc (m/min) Molten steel throughput (ton/min) Spout transverse width d (mm) ??D/d Mold amplitude S (net amplitude) (mm) Mold vibration frequency f (inferior/minute) ??Tn *??(s)
Minimum of a value Maximum Minimum of a value Maximum
????1 ????220 ????900 ????1950 ????1.0 ????1.6 ????3.4 ????80 ??2.75 ????6 ????120 ??0.177
????2 ????220 ????900 ????1950 ????1.5 ????2.3 ????5.1 ????80 ??2.75 ????6 ????130 ??0.134
????3 ????220 ????900 ????1950 ????1.8 ????2.3 ????6.1 ????80 ??2.75 ????6 ????150 ??0.112
????4 ????220 ????900 ????1950 ????2.0 ????3.1 ????6.7 ????80 ??2.75 ????6 ????185 ??0.099
????5 ????220 ????900 ????1950 ????2.1 ????3.3 ????7.1 ????80 ??2.75 ????5 ????170 ??0.075
????6 ????220 ????900 ????1950 ????2.2 ????3.4 ????7.4 ????80 ??2.75 ????5 ????180 ??0.072
????7 ????220 ????1200 ????1950 ????1.5 ????3.1 ????5.1 ????80 ??2.75 ????9 ????190 ??0.129
????8 ????220 ????1200 ????1950 ????1.8 ????3.7 ????6.1 ????80 ??2.75 ????9 ????190 ??0.124
????9 ????220 ????1200 ????1950 ????2.0 ????4.1 ????6.7 ????80 ??2.75 ????9 ????190 ??0.120
????10 ????220 ????1200 ????2200 ????2.3 ????4.8 ????8.7 ????80 ??2.75 ????9 ????160 ??0.124
????11 ????220 ????1200 ????2200 ????2.3 ????4.3 ????8.7 ????80 ??2.75 ????9 ????185 ??0.115
????12 ????220 ????1200 ????1840 ????2.3 ????4.8 ????7.3 ????80 ??2.75 ????9 ????195 ??0.112
????13 ????220 ????1200 ????1500 ????2.3 ????4.8 ????6.0 ????80 ??2.75 ????9 ????205 ??0.108
????14 ????220 ????900 ????1950 ????2.1 ????3.3 ????7.1 ????80 ??2.75 ????6 ????160 ??0.096
????15 ????220 ????900 ????1950 ????2.2 ????3.4 ????7.4 ????80 ??2.75 ????7 ????160 ??0.107
????16 ????220 ????900 ????1950 ????2.3 ????3.6 ????7.7 ????80 ??2.75 ????7 ????160 ??0.102
????17 ????220 ????900 ????2200 ????2.5 ????3.9 ????9.5 ????80 ??2.75 ????6 ????160 ??0.071
????18 ????220 ????900 ????2200 ????2.7 ????4.2 ????10.3 ????80 ??2.75 ????8 ????160 ??0.100
????19 ????220 ????900 ????2000 ????3.0 ????4.7 ????10.4 ????80 ??2.75 ????9 ????160 ??0.101
????20 ????220 ????900 ????1950 ????3.5 ????5.4 ????11.8 ????80 ??2.75 ????9 ????160 ??0.086
????21 ????110 ????400 ????400 ????2.5 ????0.9 ????0.9 ????30 ??3.67 ????6 ????160 ??0.071
????22 ????200 ????900 ????1950 ????2.5 ????3.5 ????7.7 ????70 ??2.86 ????6 ????160 ??0.071
????23 ????215 ????900 ????1950 ????2.5 ????3.8 ????8.2 ????88 ??2.44 ????6 ????160 ??0.071
????24 ????235 ????900 ????1950 ????2.5 ????4.2 ????9.0 ????88 ??2.67 ????6 ????160 ??0.071
????25 ????250 ????900 ????1950 ????2.5 ????4.4 ????9.6 ????88 ??2.84 ????6 ????160 ??0.071
????26 ????260 ????900 ????1950 ????2.5 ????4.6 ????9.9 ????88 ??2.95 ????6 ????160 ??0.071
????27 ????220 ????1200 ????1950 ????2.5 ????5.2 ????8.4 ????80 ??2.75 ????6 ????160 ??0.071
????28 ????235 ????1200 ????1950 ????2.5 ????5.5 ????9.0 ????88 ??2.67 ????7 ????160 ??0.093
????29 ????235 ????1200 ????1950 ????1.5 ????3.3 ????5.4 ????88 ??2.67 ????7 ????185 ??0.123
????30 ????235 ????1200 ????1950 ????2.1 ????4.6 ????7.6 ????88 ??2.67 ????6 ????180 ??0.096
????31 ????235 ????1200 ????2200 ????2.5 ????5.5 ????10.1 ????130 ??1.81 ????6 ????185 ??0.080
????32 ????220 ????900 ????2200 ????2.5 ????3.9 ????9.5 ????80 ????2.75 ????6 ????185 ????0.080
????33 ????220 ????900 ????2200 ????2.5 ????3.9 ????9.5 ????80 ????2.75 ????6 ????185 ????0.080
????34 ????220 ????900 ????2200 ????2.5 ????3.9 ????9.5 ????80 ????2.75 ????6 ????185 ????0.080
????35 ????220 ????900 ????2200 ????2.5 ????3.9 ????9.5 ????80 ????2.75 ????6 ????185 ????0.080
????36 ????220 ????900 ????1950 ????2.1 ????3.3 ????7.1 ????80 ????2.75 ????6 ????160 ????0.096
????37 ????220 ????900 ????2000 ????3.0 ????4.7 ????10.4 ????80 ????2.75 ????9 ????160 ????0.101
Class1: oscillating magnetic field, type 2: conversion magnetic field
Table 2B
Sequence number Immerse nozzle depth (mm) The AC magnetic field type Upper end AC magnetic field (Gauss) Upper end D.C. magnetic field (Gauss) Lower end D.C. magnetic field (Gauss)
????1 ????280 Do not have ????0 ????0 ????0
????2 ????280 Do not have ????0 ????0 ????0
????3 ????280 Do not have ????0 ????0 ????0
????4 ????280 Do not have ????0 ????0 ????0
????5 ????280 Do not have ????0 ????0 ????0
????6 ????280 Do not have ????0 ????0 ????0
????7 ????280 Class1 ????1000 ????1000 ????0
????8 ????280 Class1 ????700 ????1000 ????0
????9 ????280 Class1 ????500 ????1000 ????0
????10 ????280 Class1 ????300 ????1000 ????0
????11 ????280 Class1 ????300 ????1000 ????0
????12 ????280 Class1 ????300 ????1000 ????0
????13 ????280 Class1 ????300 ????1000 ????0
????14 ????280 Class1 ????300 ????1000 ????0
????15 ????280 Class1 ????300 ????1000 ????0
????16 ????280 Class1 ????300 ????1000 ????0
????17 ????280 Class1 ????0 ????1000 ????1500
????18 ????280 Class1 ????0 ????1500 ????2000
????19 ????280 Class1 ????0 ????2000 ????2500
????20 ????280 Class1 ????0 ????2500 ????3000
????21 ????280 Class1 ????0 ????0 ????0
????22 ????280 Class1 ????200 ????1000 ????0
????23 ????280 Class1 ????200 ????1000 ????0
????24 ????280 Class1 ????200 ????1000 ????0
????25 ????280 Class1 ????200 ????1000 ????0
????26 ????280 Class1 ????200 ????1000 ????0
????27 ????280 Do not have ????0 ????0 ????0
????28 ????280 Do not have ????0 ????0 ????0
????29 ????280 Type 2 ????600 ????0 ????0
????30 ????280 Type 2 ????600 ????1000 ????0
????31 ????280 Type 2 ????600 ????1000 ????0
????32 ????180 Class1 ????200 ????1000 ????0
????33 ????200 Class1 ????200 ????1000 ????0
????34 ????350 Class1 ????200 ????1000 ????0
????35 ????370 Class1 ????200 ????1000 ????0
????36 ????280 Class1 ????300 ????1000 ????1500
????37 ????280 Class1 ????300 ????1000 ????1500
Table 3
Sequence number Maximum minor face protuberance amount (mm) The maximum corner angle degree of depth (mm) The maximum blemish quantity of sheet material (/m 2) Surface defect rate (%) Produce fracture The powder defective accounts for overall defect ratio (%) Remarks
????1 ????0 ????3.5 ???3.10 Not ????49 Comparative Examples 1
????2 ????1 ????2.7 ????185 ???2.35 Not ????24 Comparative Examples 2
????3 ????1 ????2.6 ????120 ???1.23 Not ????20 Comparative Examples 3
????4 ????2 ????1.5 ????90 ???0.30 Not ????36 Comparative Examples 4
????5 ????2 ????1.1 ????55 ???0.15 Not ????0 Embodiment 1
????6 ????1 ????0.7 ????45 ???0.05 Not ????3 Embodiment 2
????7 ????1 ????3.0 ???3.10 Not ????33 Comparative Examples 5
????8 ????1 ????2.9 ???1.54 Not ????20 Comparative Examples 6
????9 ????2 ????2.2 ???0.50 Not ????16 Comparative Examples 7
????10 ????4 ????0.8 ???0 Not ????0 Embodiment 3
????11 ????4 ????0.9 ???0.11 Not ????5 Embodiment 4
????12 ????3 ????1.3 ???2.6 Not ????74 Comparative Examples 8
????13 ????3 ????1.3 ???4.1 Not ????85 Comparative Examples 9
????14 ????2 ????1.0 ????50 ???0 Not ????0 Embodiment 5
????15 ????3 ????0.6 ????30 ???0 Not ????0 Embodiment 6
????16 ????3 ????0.5 ????20 ???0 Not ????0 Embodiment 7
????17 ????3 ????0.2 ????10 ???0 Not ????0 Embodiment 8
????18 ????5 ????0.2 ????3 ???0 Not ????0 Embodiment 9
????19 ????5 ????0.1 ????3 ???0 Not ????0 Embodiment 10
????20 ????6 ????0.2 ????5 ???0 Not ????0 Embodiment 11
????21 ????1 ????1.4 ????70 Not Comparative Examples 10
????22 ????1 ????0.1 ????15 ???0.02 Not ????0 Embodiment 12
????23 ????2 ????0.2 ????11 ???0 Not ????0 Embodiment 13
????24 ????5 ????0.3 ????13 ???0 Not ????0 Embodiment 14
????25 ????10 ????0.8 ????25 ???0.3 Not ????4 Comparative Examples 11
????26 ????15 ????1.1 ????60 ???0.4 Not ????60 Comparative Examples 12
????27 ????9 ????0.7 ???0.03 Be ????15 Embodiment 15
????28 ????9 ????0.6 ???0.05 Not ????21 Embodiment 16
????29 ????0 ????2.5 ???5.90 Not ????37 Comparative Examples 13
????30 ????1 ????0.8 ???0 Not ????0 Embodiment 17
????31 ????2 ????0.4 ???0 Not ????0 Embodiment 18
????32 ????2 ????0.4 ???0.05 Not ????33 Embodiment 19
????33 ????2 ????0.4 ???0 Not ????0 Embodiment 20
????34 ????2 ????0.4 ???0 Not ????0 Embodiment 21
????35 ????2 ????0.6 ???1.5 Not ????67 Comparative Examples 14
????36 ????2 ????1.0 ????20 ???0 Not ????0 Embodiment 22
????37 ????3 ????0.5 ????12 ???0 Not ????0 Embodiment 23
*Blank space: do not have measure CO M.EX.: Comparative Examples

Claims (24)

1. method of producing ultra-low-carbon steel sheet material comprises:
A kind of continuous casting installation for casting is provided, comprises that having bond length D is about 150 molds to the casting space of about 240mm, and have the immersion nozzle that at least one transverse width is the spout of d, wherein D/d ratio arrives in about 3.0 the scope about 1.5;
By immersing nozzle molten steel is incorporated in the mold; And
To be higher than the casting rate casting molten steel of about 2.0mm/min, coming production carbonaceous amount percentage composition is about 0.01% or lower ultra-low-carbon steel sheet material in continuous casting installation for casting.
2. according to the method for claim 1, also comprise with about 185 times/min or lower frequency vibration mold.
3. according to the method for claim 1, casting rate is about 2.4m/min or faster.
4. according to the method for claim 1, it immerses nozzle is two spout nozzles.
5. according to the method for claim 1, D/d ratio is about 2.1 to about 2.9.
6. according to the method for claim 1, ultra-low-carbon steel sheet material is the raw material as the cold-reduced sheet of producing phone housing.
7. according to the method for claim 1, also comprise and adopt electromagnetic force that the molten steel in the mold casting space is remained in a standstill.
8. according to the method for claim 7, wherein adopt the static magnetic field that runs through mold thickness and roughly cover whole mold to produce electromagnetic force and remain in a standstill, comprising upper end magnetic field generation device and lower end magnetic field generation device,
The upper end magnetic field generation device be installed in the mold top that comprises the molten steel surface plane, the lower end magnetic field generation device be installed in the upper end magnetic field generation device below.And
Immerse nozzle and be installed between the magnetic field generation device of top and bottom, immersion depth is set between about 200 to about 350mm.
9. according to the method for claim 7, wherein adopt and run through the stack of static magnetic field and AC magnetic field in whole mold of mold thickness and produce electromagnetic force and remain in a standstill, its magnetic field generation device is installed in the mold top that comprises the molten steel surface plane, and
Immerse the lower end that nozzle is installed in magnetic field generation device, immersion depth is set between about 200 to about 350mm.
10. according to the method for claim 7, wherein adopt and run through the stack of static magnetic field and AC magnetic field in whole mold of mold thickness and produce electromagnetic force and remain in a standstill, what use is the upper end magnetic field generation device, in addition, in mold, produce static magnetic field with the lower end magnetic field generation device running through on the mold thickness
The upper end magnetic field generation device be installed in the mold top that comprises the molten steel surface plane, the lower end magnetic field generation device be installed in the upper end magnetic field generation device below, and
Immerse nozzle and be installed between the magnetic field generation device of top and bottom, immersion depth is set between about 200 to about 350mm.
11. method according to claim 1, wherein molten steel comprises mass percent about 0.01% or carbon still less, the silicon of quality percentage composition about 0.01% to about 0.04%, the manganese of quality percentage composition about 0.08% to about 0.20%, the phosphorus of quality percentage composition about 0.008% to about 0.020%, the sulphur of quality percentage composition about 0.003% to about 0.008%, the aluminium of quality percentage composition about 0.015% to about 0.060%, the titanium of quality percentage composition about 0.03% to about 0.080%, the niobium of quality percentage composition about 0.002% to about 0.017%, and the boron of quality percentage composition 0 to about 0.0007%, all the other are iron and unavoidable impurities.
12. according to the method for claim 11, wherein molten steel comprises the carbon of mass percent 0.0005% to 0.0090%.
13. a method of producing ultra-low-carbon steel sheet material comprises:
Molten steel is incorporated into one has the mold that bond length D is about 150 to about 240mm casting space by immersing nozzle, it immerses nozzle and has the spout that at least one transverse width is d, and wherein D/d ratio arrives in about 3.0 the scope about 1.5; And
To be higher than the speed casting molten steel of 2.0mm/min, coming production carbonaceous amount percentage composition is about 0.01% or lower ultra-low-carbon steel sheet material in continuous casting installation for casting.
14., also comprise with 185 times/min or lower frequency vibration mold according to the method for claim 13.
15. according to the method for claim 13, casting rate is about 2.4m/min or faster.
16. according to the method for claim 13, it immerses nozzle is two spout nozzles.
17. according to the method for claim 13, D/d ratio is about 2.1 to about 2.9.
18. according to the method for claim 13, ultra-low-carbon steel sheet material is the raw material as the cold-reduced sheet of producing phone housing.
19., also comprise and adopt electromagnetic force that the molten steel in the mold casting space is remained in a standstill according to the method for claim 13.
20. according to the method for claim 19, wherein adopt the static magnetic field run through mold thickness and roughly to cover whole mold to produce electromagnetic force and remain in a standstill, comprising upper end magnetic field generation device and lower end magnetic field generation device,
The upper end magnetic field generation device be installed in the mold top that comprises the molten steel surface plane, the lower end magnetic field generation device be installed in the upper end magnetic field generation device below.And
Immerse nozzle and be installed between the magnetic field generation device of top and bottom, immersion depth is set between about 200 to about 350mm.
21. according to the method for claim 19, wherein adopt and run through the stack of static magnetic field and AC magnetic field in whole mold of mold thickness and produce electromagnetic force and remain in a standstill, its magnetic field generation device is on the mold top that comprises the molten steel surface plane, and
Immerse the lower end that nozzle is installed in magnetic field generation device, immersion depth is set between about 200 to about 350mm.
22. method according to claim 19, wherein adopt and run through the stack of static magnetic field and AC magnetic field in whole mold of mold thickness and produce electromagnetic force and remain in a standstill, what use is the upper end magnetic field generation device, in addition, also adopt electromagnetic field generation device in running through the whole mold of mold thickness, to produce static magnetic field
The upper end magnetic field generation device be installed in the mold top that comprises the molten steel surface plane, the lower end magnetic field generation device be installed in the upper end magnetic field generation device below, and
Immerse nozzle and be installed between the magnetic field generation device of top and bottom, immersion depth is set between about 200 to about 350mm.
23. method according to claim 13, wherein molten steel comprises mass percent about 0.01% or carbon still less, the silicon of quality percentage composition about 0.01% to about 0.04%, the manganese of quality percentage composition about 0.08% to about 0.20%, the phosphorus of quality percentage composition about 0.008% to about 0.020%, the sulphur of quality percentage composition about 0.003% to about 0.008%, the aluminium of quality percentage composition about 0.015% to about 0.060%, the titanium of quality percentage composition about 0.03% to about 0.080%, the niobium of quality percentage composition about 0.002% to about 0.017%, and the boron of quality percentage composition 0 to about 0.0007%, all the other are iron and unavoidable impurities.
24. according to the method for claim 23, wherein molten steel comprises the carbon of mass percent 0.0005% to 0.0090%.
CNB2004100748080A 2003-08-29 2004-08-30 Method for producing ultra low carbon steel slab Expired - Lifetime CN1299855C (en)

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