CN1075407C - Steel continuous casting crystallizer fluxing agent, evaluating method, casting mould for testing and continuous casting method - Google Patents
Steel continuous casting crystallizer fluxing agent, evaluating method, casting mould for testing and continuous casting method Download PDFInfo
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- CN1075407C CN1075407C CN97125394A CN97125394A CN1075407C CN 1075407 C CN1075407 C CN 1075407C CN 97125394 A CN97125394 A CN 97125394A CN 97125394 A CN97125394 A CN 97125394A CN 1075407 C CN1075407 C CN 1075407C
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Abstract
The present invention provides an evaluation method, a casting mould for evaluating and a continuous casting method for a crystallizer fluxing agent to obtain a casting sheet with no crack on the surface, good surface characteristic and no defect in the continuous casting of medium carbon steel SUS420, SUS. The crystallizer fluxing agent of the present invention can reappear fine crystals and high crystallization rate during the solidification of the crystallizer flux agent flowing between the casting mould and the casting sheet. The method of the present invention can make the crystallizer flux agent cooled slowly in the casting mould, and can reduce the variation of local heat flow bundles. The evaluation method and the casting mould for evaluating of the present invention can exactly observe the molten state of the crystallizer flux agent, and find out the correlation of observed results and the properties of the surface of the casting sheet.
Description
The present invention relates to crystallizer fluxing agent and continuous casing, use the present invention, big (C) of amount of contraction in the casting sheet process of setting when continuous casting: in the continuous casting of the medium carbon steel of 0.06～0.20 weight %, SUS420 (martensitic stainless steel, for example 13%Cr stainless steel) and SUS304 (austenite stainless steel, for example 13%Cr8%Ni stainless steel), can obtain good, the flawless casting sheet of surface texture of surperficial flawless (transverse crack, longitudinal crack).
The invention still further relates to adding method that the crystallizer fluxing agent in the mold estimates in advance and the viewing test mold that is used for this evaluation when the continuous casting of above-mentioned steel to.
In the prior art, when the continuous casting of steel, the crystallizer fluxing agent that adds in the mold has various effects.That is 1. molten steel surface insulation, to being cast.2. prevent the in-mold molten steel surface oxidation and dissolve the foreign material that float rapidly.3. help lubricating between mold and casting sheet.4. the optimal heat dissipation capacity of sheet etc. is cast in control.
Because these effects of flux can make the surperficial zero defect of casting sheet, form beautiful cast(ing) surface, especially in order to ensure the stability and the yield rate that improves the casting sheet of casting operation in the continuous casting operation, crystallizer fluxing agent is indispensable.
Crystallizer fluxing agent is powdery or graininess normally, and its composition is generally with CaO, SiO
2Be main, other also comprises Al
2O
3, alkaline-earth metal and alkali-metal compound (oxide, carbonate, fluoride etc.).In order to regulate melt temperature, viscosity etc., also interpolation is used to regulate the carbon of fusion speed.Granular flux is with the certain shapes of maintenance such as bonding agent of organic and inorganic matter.
Recently, above-mentioned 4. on, when the carbon content of steel is about the continuous casting of medium carbon steel of 0.1 weight % (generally being 0.06～0.20%), in process of setting, produce rapid solidification shrinkage along with the δ that comprises peritectic reaction → γ metamorphosis, the casting sheet leaves mold and produces local solidification, and this is the reason that crackle appears in the surface.In order to prevent this phenomenon, should control the heat dissipation capacity of mold, reduce heat stream, make its slow cooling but.
As slow cooling method but, open in flat 7-214263 number the Japanese patent gazette spy, be to add ZrO, TiO
2, CeO
2, with CaO/SiO
2Set lowly, the crystallization control degree is not too high.Open in flat 7-164120 number the spy, be to add Cr metal or its compound powder, like this, the beginning temperature is separated out in crystallization in the time of can improving the solidifying of crystallizer fluxing agent, and can make crystallization separate out the beginning temperature and be not limited to the maintenance of cooling velocity ground necessarily (if the thickness of solid flux is certain, then have certain heat radiation), its slow cooling but also can evenly be cooled off, can prevent face crack.
But, in medium carbon steel (C:0.06～0.20 weight %),, open in flat 7-214263 number, because cooling velocity not necessarily, is very difficult so will obtain certain crystallization rate the spy even adopt above-mentioned known method.For example, can not prevent face crack fully owing to the change of the molten steel face height in the mold, casting speed etc.
In addition, open in flat 7-164120 number the spy, though have the function of the high and even cooling velocity of crystallization degree, but because crystallization start temperature uprises, the lubricity of whole mold inner face lowers, and the formation of complete housing postpones, and produces constraint, above-mentioned prior art the danger of fracture arranged, so can not be dealt with problems fully.
In addition because the fixing S in the crystallizer fluxing agent, so, need resemble the spy open in clear 63-61108 number to the restriction of S, raise the cost thus.
The following describes the fusion test method of existing crystallizer fluxing agent.
The coagulating property of the powder of the size distribution of crystallizer fluxing agent, loose specific weight etc. or the characteristic of graininess, viscosity, molten condition, the membranaceous crystallizer fluxing agent when especially casting between casting sheet and the mold how, promptly, crystallizer fluxing agent is that crystalline or noncrystalline matter and crystallization are column crystal or equiaxed crystal, are thick or small etc. in curdled appearance, and the quality of casting sheet surface texture is had a significant impact.
Therefore, when reality is used, must measure above-mentioned each characteristic, correctly grasp them.
In above-mentioned each characteristic, the size distribution when powder or graininess, loose specific weight etc. can easily be measured, and the mensuration of the important rerum natura viscosity during molten condition is also carried out than being easier to.
How accurately to grasp the situation in the melting process, also do not have good method so far.The method of available technology adopting is, is the powder compacting of crystallizer fluxing agent triangular pyramidal or cylindrical, is heated and observes its fusion situation in heating furnace.
But this method promptly enables to measure fusion speed and fusion amount etc., also is difficult to grasp the molten condition of crystallizer fluxing agent.Situation after adding in mold when practical operation and the situation in this method differ widely, and therefore, can not observe the delicate molten condition of crystallizer fluxing agent.In addition, because test portion is triangular pyramidal or columniform three-dimensional shape, can not carry out the observation in the extensive visual field on plane.
The spy opens the method that discloses clear 53-70040 number, is that crystallizer fluxing agent is put into crucible, makes its cooling from a direction after the heating scheduled time, with the crucible slit shearing, observes the molten condition of additive.
But, this method, after the complete fusion of the superficial layer of crystallizer fluxing agent, heat energy is delivered to from superficial layer and is positioned at the superficial layer internal layer, the quantity delivered of heat energy is less than on the crystallizer fluxing agent of internal layer of superficial layer (at one time in), promptly enable to measure the whether successively fusion of this layer crystallizer fluxing agent, but, in the superficial layer that same heat energy is evenly supplied with, in the fusion initial stage of this superficial layer, the puddle on superficial layer exists with what kind of ratio and distribution pattern with puddle not, these are crystalline or noncrystalline matter, the situation that superficial layer with what kind of process carries out in the melting process such as fusion can not be learnt.
In addition, open in flat 7-204810 number the spy, disclosed the crystallization rate assay method of melting crystallizer flux, but this is with simple mensuration formula the crystallizer fluxing agent of crystallization to be carried out the mensuration of crystallization rate under given conditions, can not correctly estimate all crystallizer fluxing agents.For example, do not observe the crystalline state of crystal structure, crystallization particle diameter etc.
The present inventor is melted the slag from crystallizer fluxing agent, the generation of the crystallization during to the generation crystallization and freezing and the various key elements of growth thereof are investigated, for example the residual amount that begins temperature and nuclei of crystallization generating capacity and size thereof and become the glassy phase of matrix is separated out in the influence of several additives, particularly crystallization and investigated, also carried out casting evaluation simultaneously.
Its result, (for example the spy opens flat 7-164120 to existing crystallizer fluxing agent, Te Kaiping 7-214263) in, really can prevent that the longitudinal crack of casting sheet from producing, but, according to from the temperature information that is arranged on the thermocouple in the mold, in some change of molten steel face or melt slag caking (promptly, the part of melting crystallizer flux can be adhered to solidification-stack forms beginning portion at the film of melting crystallizer flux top because of the cooling of mold, caking on the mold wall) for a long time, can produce the temperature confusion, can not on the casting sheet, form uniform solidified shell, can send the alarm of fracture thus, even cause fracture because of casting sheet surface solidification shell disrumpent feelings.
As previously mentioned, in the method for prior art, because the molten condition that can not correctly observe crystallizer fluxing agent, so, the relation of the observed result that can not obtain molten condition between with casting sheet surface texture very denying.
Usually, the characteristic difference of crystallizer fluxing agent, also inequality to the influence that casting sheet surface texture is very denied.This results from the molten condition of crystallizer fluxing agent.Therefore, only in order to understand that what-the-hell situation is only, need how to carry out the viewpoint of fusion test method and establish suitable fusion test method from how grasping the molten condition of crystallizer fluxing agent.
This be because, if established the fusion test method of crystallizer fluxing agent, can confirm with the mold of reality and cast the situation that the molten condition between sheet is similar to, then can select to use the flux that is suitable for the steel grade of casting most.
In addition, even adopt specific crystallizer fluxing agent,, just can address the above problem as long as under the state that keeps appropriate relation between viscosity and the continuous casting speed, cast.
The present invention studies the problems referred to above, its purpose is to provide a kind of crystallizer fluxing agent that casts usefulness continuously, the medium carbon steel in the peritectoid territory of longitudinal crack, the casting of SUS420, SUS304 can be stably be easier to produce with this flux, and the crack defect on sheet surface can be prevented to cast.
It is easy and correctly observe fusion test method molten condition, crystallizer fluxing agent of crystallizer fluxing agent and be used for the mold of this fusion test that another object of the present invention provides a kind of energy.
To achieve these goals, the continuous casting of steel of the present invention is characterised in that with crystallizer fluxing agent, as having metal or its compound that makes crystal grain miniaturization effect, added percentage by weight and be 0.2～5.0, particle diameter is Mn or the Mn compound of 0.4 μ m～100 μ m, make that thus the interior crystalline particle diameter of test portion vertical section that obtains with specific crystallizer fluxing agent evaluation method is 0.1～9.0mm, it is more than 70% that the particle of this diameter accounts for the full face ratio of test portion.
As optimal case of the present invention, above-mentioned Mn compound is Fe-Mn, Si-Mn, MnO, Mn
2O
3, Mn
3O
4, MnCO
3And MnSO
4
According to continuous casting crystallizer fluxing agent of the present invention, the crystallization rate of the crystal grain that can improve when flowing into mold and casting crystallizer fluxing agent between sheet and solidify by miniaturization, can realize that the change that slow cooling in the mold is but changed with local heat stream reduces, and can stably cast high-quality steel continuously.
Fig. 1 represents the mold shape used in the crystallizer fluxing agent evaluation of the present invention and the stereogram of size.
Fig. 2 is the figure of the melting method summary of expression crystallizer fluxing agent of the present invention.
Fig. 3 (a) is the figure of the mode of operation of expression fusion test stove of the present invention (b).
Fig. 4 (a)～(d) is a stereogram of representing mold used among the present invention.
Fig. 5 (a) is the stereogram of used other mold among expression the present invention (b).
Fig. 6 is the stereogram of used cooling mold among expression the present invention.
Fig. 7 (a)～(f) is the synoptic diagram of the solidified structure of the test portion that obtains with fusion test of the present invention.
Below, with reference to the description of drawings embodiments of the invention.
When adding crystallizer fluxing agent toward mold is interior, crystallizer fluxing agent flows between mold and the casting sheet, is cooled off by mold.Therefore, the crystallizer fluxing agent of inflow solidifies in the mold side, becomes the membranaceous of solid and joins with mold, because the effect of high temperature solidified shell, becomes the film of the liquid condition of fusion in casting sheet side.
The main cause of casting sheet generation longitudinal crack is the thickness deviation because of this solid film and fused film, because this deviation, inhomogeneous from the casting sheet to the heat radiation of mold, in the big part of heat radiation, solidification shrinkage is concentrated, and mold is left in the meniscus bottom in mold, and this part causes set retardation, stress concentrates on herein, produces longitudinal crack along with the recessed of the part of leaving mold.
Therefore, for the slow cooling of casting sheet but, adopt the setting temperature that improves crystallizer fluxing agent usually, the method that film thickness is solidified in thickening realizes slow cooling but, perhaps, crystallizer fluxing agent is carried out pre-fusion handle, it is homogenized, to prevent that casting sheet produces longitudinal crack.
But if improve the setting temperature of crystallizer fluxing agent, on the molten steel face that joins with mold, it is excessive that above-mentioned after crystallizer fluxing agent solidifies melted the slag caking, causes operability to worsen.In addition, because molten steel face change, this is big melts slag and forms the thick slag film that melts at meniscus, this part was cooled off slow, and the formation of the shell that fully solidifies is suppressed, mold just below be unable to bear the static pressure of molten steel, sometimes cause fracture, this is one of reason of fracture generation.
Therefore, the present inventor flows into the flux of fusion in the iron mold shown in Figure 1, investigates its solidified structure, temperature and crystallization generation number and size is separated out in the crystallization of crystallizer fluxing agent when solidifying of fusion studied.Among the figure, material SS41 represents the steel rolling that ordinary construction is used.
The melting method of crystallizer fluxing agent adopts general Muffle furnace shown in Figure 2, and it is operated as (a) of Fig. 3 with (b).
A certain amount of crystallizer fluxing agent 1 (having removed the flux composition of 1g.loss (calcination loss) part) is packed into from the top of top graphite crucible 2.At this moment top graphite crucible 2 is in the decline state, the stop part 5 that is positioned at bottom graphite crucible 3 central parts is being closed, because top graphite crucible 2 is heated conditions, the part of the flux 1 that is loaded into fuse on one side and is run down into 3 interior (Fig. 3 a), the even fusion of flux that crucible 3 is interior of lower crucible.As shown in Figure 2, in the periphery of bottom graphite crucible 3, be provided with the heater 9 that is used to heat this crucible.
Crystallizer fluxing agent 1 is through after certain even fusion retention time, by top crucible 2 is risen, stop part 5 also rises simultaneously, make flux 1 flow out (Fig. 3 b) from the conveying end 4 of bottom graphite crucible 3 instantaneously, as shown in Figure 2, under certain conditions, chew 6 by intervalve and inject the mold 7 that is positioned at the below, the fusion flux that has injected mold is cooled, and becomes the test portion that solidifies of crystallizer fluxing agent.
From mold 7, take out cooled and solidified crystallizer fluxing agent, this test portion is cut off along longitudinal direction, its section detects by an unaided eye.
In order to confirm effect of the present invention, to having the crystallizer fluxing agent of composition shown in the table 1 and rerum natura, after usefulness Fig. 2, dissolving method shown in Figure 3 dissolve the melting crystallizer flux, inject mold shown in Figure 1, take out cooled test portion, this test portion is longitudinally cut off, observe its section.Fig. 7 represents the sketch of this test portion solidified structure of drawing.The fusion test condition is all identical.
(a)～(f) among Fig. 7 is corresponding with the crystallizer fluxing agent A～F of table 1.
Table 1
| The test portion numbering | A | B | C | D | E | F | |
| Composition | SiO 2 | 32.0 | 36.0 | 33.0 | 32.0 | 32.9 | 32.0 |
| Al 2O 3 | 5.0 | 4.0 | 2.0 | 8.0 | 2.0 | 2.0 | |
| CaO | 32.0 | 44.0 | 41.0 | 38.0 | 40.9 | 40.0 | |
| MgO | - | - | - | - | - | - | |
| Na 2O | 20.0 | 4.0 | 11.0 | 9.0 | 11.0 | 11.0 | |
| F -2) | 11.0 | 12.0 | 11.0 | 11.0 | 11.0 | 11.0 | |
| Li 2O | - | - | 2.0 | 2.0 | 2.0 | 2.0 | |
| ZrO 2 | - | - | - | - | - | - | |
| MnO | - | - | - | - | 0.2 | 2.0 | |
| CaO/SiO 2 | 1.00 | 1.22 | 1.24 | 1.22 | 1.25 | 1.25 | |
| Rerum natura | Setting temperature (℃) | 1050 | 1170 | 1170 | 1170 | 1170 | 1170 |
| Viscosity | 0.8 | 1.5 | 0.6 | 1.1 | 0.6 | 0.6 | |
Annotate: (1) viscosity=(at1300 ℃)
(2) F
-Be the content of the F in the additives such as CaF, NaF.In addition, Ca converts as the CaO amount, and Na is as Na
2O measures conversion.
As shown in Figure 7, (a) and (b) are vitrifying degree height, have the crystallizer fluxing agent of high-lubricity, and setting temperature is height or low all vitreous easily.
(c), (d) is crystallinity height, slow cooling crystallizer fluxing agent but, though its quality is good, but because its crystallinity (column crystal) height, poor lubricity, it is more to produce binding fracture alarm, and its crystallinity is big, and the generation of melting the slag caking is also big, operability is poor, and the situation that produces fault is more.
(e), (f) overcome the shortcoming of above-mentioned (a)～(d), its effect is to prevent at (c) and the 9mm hypercolumn crystallization that (d) can see or the hypertrophy of granular crystal, the crystallization when solidifying of the crystallizer fluxing agent of fusion is not grown very greatly, and the miniaturization that becomes, thereby the heat radiation of its crystallization is lower than (c), (d), and can obtain high-lubricity.
From the section observed result of the melting and solidification test portion of above-mentioned crystallizer fluxing agent as can be known, the crystallizer fluxing agent of the (a) and (b) section among Fig. 7 is applicable to general crackle sensitivity few carbon aluminium-killed steel, high-carbon steel or SUS430 (ferrite stainless steel, for example 17%Cr stainless steel) etc.
The crystallizer fluxing agent of (c) among Fig. 7, (d) section, generally be used for medium carbon steel, SUS420, SUS304 that solidification shrinkage is big etc., but exist above-mentioned problem have shown in (e) among Fig. 7, (f) etc. the specific section of axle crystal grain and miniaturization, problem does not take place in it when being used for medium carbon steel, SUS420, SUS304 etc., be best suited for, this is distinguished.Therefore, according to this result,, can adopt the flux of above-mentioned (e), (f) section as the continuous casting crystallizer fluxing agent of medium carbon steel etc.
As previously mentioned, the present inventor draws such opinion in the evaluation test of crystallizer fluxing agent: temperature is separated out in the crystallization when solidifying as crystallizer fluxing agent one of crystallizer fluxing agent characteristic value, fusion and crystallization generates number and granularity is the key factor that the decision crystallizer fluxing agent is very denied.
As can be seen from Figure 7, different crystallizer fluxing agent characteristics, the generation of the crystal grain of the solidified structure that obtains in evaluation test has very big-difference, can carry out the evaluation of crystallizer fluxing agent with this difference.Can estimate according to this, various crystallizer fluxing agents are used to be suitable for its steel grade, in addition, also can make the crystallizer fluxing agent that is suitable for steel grade by select or the assembly of composition etc.
As previously mentioned with as test portion central portion rip cutting along its length disconnected, observe its section.According to this observed result, crystallization with 0.1～9.0mm particle diameter accounts for full basal area more than 70%, can be used as crystallizer fluxing agent of the present invention.
In order to satisfy the above-mentioned section particle diameter that solidifies, in the crystallizer fluxing agent composition, except the various compositions that contain usually, preferably suitably be furnished with the metal or its compound powder that make section crystal grain miniaturization effect.This metal for example can be Mn, also can be its compound.
In order to bring into play effect, the minimum 0.2wt% that should be of its addition, mostly be most 5.0wt%, if this particle diameter is big, then when cooperating, be not easy to mix and be not easy and dissolve fully, can not get the homogeneously crystallized of molten condition, cause inhomogeneous cooling and insufficient lubrication, so its particle diameter is to get final product more than the 0.4 μ m, is no more than 100 μ m at most.
Add the fixedly S in the crystallizer fluxing agent of these additives, so, needn't resemble above-mentioned spy and open the clear 63-81103 the restriction of S, crystallizer fluxing agent cheaply can be provided.From the prior art aspect, this is a surprising invention.And, only need few addition just can bring into play sufficient characteristic.Which kind of shape (powder, extrude particle, sphere) is all no problem, but to melt slag minimum in order to make, and is preferably made the hollow particle shape.
The evaluation test of the crystallizer fluxing agent among the present invention is under given conditions, and the test portion section of cooled and solidified is observed, and judges the good of crystallizer fluxing agent.From crystallizer fluxing agent be molten to the injection mold, wait in the evaluation test the specific of mold, must obtain the result of repeatability.
As above-mentioned specified conditions, be the dissolution time of melting crystallizer flux and temperature when injecting, for example use dissolver shown in Figure 2, in 15 minutes, to dissolve, the temperature when injecting mold was finished injection at 2 seconds with interior in 1400～1450 ℃ of scopes.
From mold 7, take out the crystallizer fluxing agent of cooled and solidified, cut off this test portion, the tissue of its section that detects by an unaided eye along longitudinal direction, see the generation state of crystal grain, grasp crystallizer fluxing agent and be in which kind of state, estimate, judge whether the steel grade that is suitable for casting.When mold injects, consider the cooling of melting crystallizer flux, must as far as possible promptly handle.For each crystallizer fluxing agent test portion, if this asynchronism(-nization) then can influence the crystal grain situation occurred after solidifying, produce big error in relatively at test portion, lost meaning relatively, can produce the deviation of evaluation, become insignificant evaluation even.
The evaluation mold that uses among the present invention for example is the mold with size shown in Figure 1, and the material of mold should have high pyroconductivity, can obtain complete test portion along the whole height of mold with this mold.
The evaluation of using among the present invention has very important significance with mold, it influences the correct evaluation of crystallizer fluxing agent, so, must be make the crystallizer fluxing agent that adds in the continuous casting mold between mold and casting sheet, become membranaceous, and can bring into play the mold of lubricant.
As previously mentioned, the present invention is based on such opinion, that is, make the crystallizer fluxing agent cooling of fusion, in its cooling procedure, generate the surface texture of the state influence casting sheet of crystallization.So, be suitable for measuring the evaluation mold of melting crystallizer flux crystallization rate, must have the shape of the cooling of tilting.
The present inventor has done various researchs to the mold that is suitable for tilting cooling, and its result develops mold of the present invention.
So-called inclination cooling is meant the cooling of tilting in the short transverse amount of cooling water.The height ratio of crystallized domains is only estimated in cooling before, and inclination cooling of the present invention will be estimated crystal structure (for example column crystal, equiax crystal etc.), crystallization particle diameter and such three aspects of crystallization area occupation ratio.
See evaluation mold of the present invention from vpg connection,, constitute that the temperature difference of mold wall (thermal capacity is poor) must change continuously in short transverse by part that is subjected to quenching and the mold wall that be connected as a body by gradually cold part in order to realize cooling.Making this structure can have various forms, and the present inventor is in order to represent the crystallization rate of cooled test portion rightly, and considers that from the viewpoint of easy grasp test portion a kind of shape of used mold as shown in Figure 4.
Fig. 4 a is illustrated in the cast structure that the cylindrical mold central portion is wearing the turbination hole, and the melting crystallizer flux is injected in the mold, and the bottom is by quenching, and past more top is cold gradually.The test portion that obtains with the mold of this shape when in order to observe its vertical section crystalline state it being cut off, can cut off from any position by the conical bottom center of face, so easily.
Fig. 4 b represents wearing the mold structure in handstand pyramid hole.With Fig. 4 a similarly, past more top is cooled gradually.When taking the vertical section test portion, can cut off by awl diagonal center, bottom surface.
Fig. 4 c represents wearing the mold structure of del groove, when taking test portion, will omit the central portion rip cutting and observe its section.In the mold shown in above-mentioned Fig. 4 a, 4b, the 4c, when taking test portion,, can easily from mold, take out test portion with the upper and lower inversion rotation of mold.
Fig. 4 d represents is with the both sides of mold shown in Fig. 4 c situation removably.
Fig. 5 a, Fig. 5 b are the variation of mold structure, are wearing circle (angle) hole at rounding (angle) frustum mold central portion, are used to form test portion cylindrical, corner post shape.Can carry out along the different inclination cooling of the thermal capacity of mold longitudinal direction with this mold.
Also can do to become that the uphill casting mould is arranged to mold, have the uphill casting mould following advantage to be arranged in operating aspect.That is, mold is become shape of the no end, be placed on the chassis 11, inject the crystallizer fluxing agent of fusion and make test portion, when taking out test portion,, just can easily take out as long as after chassis 11 taken off, down push test portion from mold top.The cut-out of test portion and similarly above-mentioned, along the bottom surface or upper central portion cut off and to get final product.
The test material shape of representing among Fig. 4, Fig. 5 is pyramid or corner post shape, this means it can is polygonal except triangle.
As shown in Figure 6, the temperature effect of gas outside mold is subjected to is equipped with the water cooling plant 10 that cools off mold self on mold, and this is effective for repeatability.
The material of mold is not particularly limited, and can use metal systems such as iron, copper, also can use pottery, porcelain system, but from the casting sheet with continuous casting homophylic viewpoint is arranged, and is easier to make with iron and steel.
Below, in order to confirm the effect of crystallizer fluxing agent of the present invention,, carried out the foundry trial of casting sheet with continuous casting machine to embodiment and comparative example.
In table 2 and the table 3, the chemical composition value and the physics value of employed crystallizer fluxing agent in expression embodiment and the comparative example.In table 4 and the table 5, the surface texture of the operating condition in the continuous casting of this flux of expression employing, the operability when using, casting sheet and use result's overall merit.
Embodiment 1～19th, adopts crystallizer fluxing agent of the present invention, and comparative example 20～23rd adopts the present invention's crystallizer fluxing agent in addition.
Adopt the raw material of various forms.That is, shown in table 2,3 raw material pattern hurdle, show A, B, C, D4 kind pattern, its difference is as follows.
A: pre-fusion raw material
Only use and dissolved the raw material of powder stock (pre-fusion).
B: silico-calcium
Artificial calcium silicates raw material.Because not conforming to has flux, increase the flux addition with the back adding method.Though raw material is cheap, S content height.Therefore, avoid being used for medium carbon steel.Among the present invention, harmful S is fixed with the MnS form, so, this raw material can be used.
C: a part of pre-fusion raw material+flux
The pattern that the raw material that has dissolved powder stock is mixed with flux.
D: wollastonite+flux
Can be the natural CaOSiO of producing
2As middle carbon is the pattern that powder stock uses.
The steel of continuous casting adopts medium carbon steel (C:0.1%) among the embodiment 1～5 and 9～19, adopt SUS304 among the embodiment 6,7, adopts SUS420 among the embodiment 8.Adopt medium carbon steel (C:0.1%) in the comparative example 20～23.
From the result of table 4 and table 5 as can be known, crystallizer fluxing agent of the present invention does not crack on the good and casting sheet that obtains of operability, even S content height does not have any harmful effect yet.
And in the comparative example 20～23 since the test portion section proterties of crystallizer fluxing agent do not resemble the present invention crystal grain by miniaturization, its result, the surface texture of casting sheet worsens, and also cracks, and defective work is many, need repair the processing of cut-out crackle generating unit etc. to the casting sheet.
Below, the embodiment of continuous casing of the present invention is described.
The composition of used steel is as shown in table 6 among the embodiment.The composition of employed crystallizer fluxing agent and rerum natura are shown in table 2 and table 3.In table 4 and table 5, show the operating condition of continuous casting and the surface texture of the operability when using, casting sheet and use result's overall merit.
The plate of casting is of a size of 250 * 1000mm, and billet bloom size is 160 * 160mm.Casting speed is more than the 1.6m/min, satisfies the scope of the invention.
In the table 2, embodiment 1,2,5,9,11 and 12 is in the high-speed casting of intermediate carbon steel sheet, contains 0.2% and 0.5%MnO (scaled value) person, and consequently, quality and operability are all good.Embodiment 10 is in the high-speed casting of intermediate carbon steel sheet, contains 1.0%MnO (scaled value) person, and consequently, even S content height, quality and operability are also all good.
Embodiment the 3, the 4th, in the casting of intermediate carbon steel sheet, contains 1.0% and 2.0%MnO (scaled value) person, and consequently, quality and operability are all good, though embodiment 3 S content high results are also good.
Embodiment the 6, the 7th, in the high-speed casting of SUS304 steel billet and plate, contains 1.0%MnO (scaled value) person, and embodiment 8 is in the high-speed casting of SUS420 plate, contains 1.0%MnO (scaled value) person, and consequently, quality and operability are all good.
Shown in embodiment 13～18,, also can obtain enough good result even part of raw materials is pre-fusion+flux type.Shown in embodiment 19, do not do the basis, and adopt natural wollastonite with the pre-fusion raw material, though its quality not exclusively meets the demands, also obtain enough good result.
And no matter the outer comparative example 20～23 of the scope of the invention that does not contain MnO is plate, steel billet, on casting sheet surface longitudinal crack has taken place all, needs the post processing of the finishing of casting sheet, the cut-out of crackle part etc., does not meet the demands.
As other rerum natura, implemented setting temperature and be 1050～1300 ℃ test, consequently, even solidify, still keep mobile in casting sheet side in the mold side, have sufficient lubricating function, problems such as fracture take place, can carry out stable operation.
Among the present invention, be to be purpose in high-speed casting, to keep good casting sheet surface texture, so, be that stretching casting sheet more than the 1.2m/min is an object with continuous casting speed.
The present inventor does big change with various η, V, setting temperature and has carried out foundry trial, and the result between the viscosity of casting speed and crystallizer fluxing agent, must satisfy certain relational expression.Its scope is represented as shown in the formula (1).
η×V≤4 (1)
In the formula, η=viscosity (1300 ℃ of poise at)
V=casting speed (m/min).
If surpass this value, then be not easy to prevent to cast the face crack of sheet, impair the surface texture of casting sheet.
[table 2]
| Embodiment | |||||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | ||
| Type of feed 1) | A | A | B | A | A | A | A | A | A | B | A | A | |
| Become | SiO 2 | 32.5 | 32.5 | 32.0 | 30.0 | 32.5 | 30.0 | 30.0 | 30.0 | 30.0 | 30.0 | 32.5 | 32.5 |
| Al 2O 3 | 2.0 | 1.5 | 1.5 | 1.0 | 2.0 | 1.0 | 1.0 | 1.0 | 4.5 | 2.0 | 4.0 | 2.0 | |
| CaO | 40.5 | 40.5 | 40.0 | 42.0 | 40.5 | 42.0 | 42.0 | 42.0 | 42.0 | 42.0 | 40.5 | 40.5 | |
| MgO | 0.5 | 0.5 | - | - | 0.5 | - | - | - | - | - | - | - | |
| Na 2O | 10.5 | 10.5 | 10.5 | 10.0 | 10.5 | 10.0 | 10.0 | 10.0 | 10.0 | 11.0 | 9.5 | 8.5 | |
| F -5) | 11.0 | 11.0 | 10.5 | 10.0 | 11.0 | 10.0 | 10.0 | 10.0 | 10.0 | 11.0 | 10.0 | 9.0 | |
| Li 2O | 2.0 | 2.0 | 2.0 | - | 2.0 | - | - | - | 2.0 | 2.0 | 2.0 | 1.0 | |
| ZrO 2 | - | - | 2.0 | 5.0 | - | 5.0 | 5.0 | 5.0 | - | - | - | 5.0 | |
| Become | MnO (scaled value) | 0.2 | 0.5 | 2.0 | 1.0 | 0.2 | 1.0 | 1.0 | 1.0 | 0.5 | 1.0 | 0.5 | 0.5 |
| TiO 2+Sro | - | 0.5 | - | 1.0 | - | 1.0 | 1.0 | 1.0 | - | - | - | - | |
| S | ＜0.1 | ＜0.1 | ＜0.3 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.3 | ＜0.1 | ＜0.1 | |
| CaO/SiO 2 | 1.25 | 1.25 | 1.25 | 1.40 | 1.25 | 1.40 | 1.40 | 1.40 | 1.40 | 1.40 | 1.25 | 1.25 | |
| MnO powder particle footpath (μ m) | 23 | 23 | 0.5 | 10 | 80 | 23 | 23 | 23 | 1.0 | 1.0 | 5.0 | 20 | |
| Rerum natura | Setting temperature (℃) | 1170 | 1170 | 1180 | 1230 | 1170 | 1170 | 1170 | 1170 | 1200 | 1250 | 1100 | 1210 |
| Viscosity 2) | 0.6 | 0.6 | 0.8 | 1.0 | 0.6 | 0.6 | 0.6 | 0.6 | 1.0 | 0.6 | 1.2 | 1.0 | |
| Test portion section proterties 3) | e | e | f | f | e | f | f | f | e | f | e | e | |
| Occupation rate 4) | 75 | 80 | 85 | 90 | 75 | 90 | 90 | 90 | 90 | 90 | 85 | 85 |
Annotate: 1) type of feed=A: pre-fusion raw material, B: silico-calcium raw material, C: a part of pre-fusion raw material+flux, D: wollastonite+flux
Annotate 2) viscosity=(1300 ℃ of at), 3) classification among section proterties=Fig. 4,4) occupation rate=percent crystallization in massecuite accounts for the ratio of test portion section, 5) F-has been to use CaF
2, NaF person.
[table 3]
| Embodiment | Comparative example | |||||||||||
| 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | ||
| Type of feed 1) | C | C | C | C | C | C | D | C | C | A | A | |
| Become | SiO 2 | 32.5 | 32.5 | 30.0 | 30.0 | 30.0 | 32.5 | 30.0 | 32.0 | 36.0 | 33.0 | 32.0 |
| Al 2O 3 | 2.0 | 1.5 | 1.0 | 4.5 | 2.0 | 4.0 | 1.0 | 5.0 | 4.0 | 2.0 | 8.0 | |
| CaO | 40.5 | 40.5 | 42.0 | 42.0 | 42.0 | 40.5 | 42.0 | 32.0 | 44.0 | 41.0 | 39.0 | |
| MgO | 0.5 | 0.5 | - | - | - | - | - | - | - | - | - | |
| Na 2O | 10.5 | 10.5 | 10.0 | 10.0 | 11.0 | 9.5 | 10.0 | 20.0 | 4.0 | 11.0 | 9.0 | |
| Divide | F - | 11.0 | 11.0 | 10.0 | 10.0 | 11.0 | 10.0 | 10.0 | 11.0 | 12.0 | 11.0 | 11.0 |
| Li 2O | 2.0 | 2.0 | - | 2.0 | 2.0 | 2.0 | - | - | - | 2.0 | 2.0 | |
| ZrO 2 | - | - | 5.0 | - | - | - | 5.0 | - | - | - | - | |
| MnO (scaled value) | 0.2 | 0.2 | 1.0 | 0.5 | 1.0 | 0.5 | 1.0 | - | - | - | - | |
| TiO 2+Sro | - | - | 1.0 | - | - | - | 1.0 | - | - | - | - | |
| S | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | 0.3 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | ＜0.1 | |
| CaO/SiO 2 | 1.25 | 1.25 | 1.25 | 1.40 | 1.40 | 1.25 | 1.40 | 1.00 | 1.22 | 1.24 | 1.22 | |
| MnO powder particle footpath (μ m) | 0.5 | 0.5 | 0.4 | 0.4 | 0.4 | 0.4 | 0.5 | - | - | - | - | |
| Rerum natura | Setting temperature (℃) | 1170 | 1170 | 1230 | 1200 | 1250 | 1100 | 1230 | 1050 | 1170 | 1170 | 1170 |
| Viscosity 2) | 0.6 | 0.6 | 0.8 | 1.0 | 0.6 | 1.2 | 1.0 | 0.8 | 1.5 | 0.6 | 1.1 | |
| Test portion section proterties 3) | e | e | f | e | f | e | f | (a) | (b) | (c) | (d) | |
| Occupation rate 4) | 75 | 80 | 90 | 90 | 90 | 85 | 90 | 0 | 10 | 95 | 80 |
Annotate: 1) type of feed=A: pre-fusion raw material, B: silico-calcium raw material, C: a part of pre-fusion raw material+flux, D: wollastonite+flux
Annotate 2) viscosity=(1300 ℃ of at), 3) classification among section proterties=Fig. 4,4) occupation rate=percent crystallization in massecuite accounts for the ratio of test portion section, 5) F-has been to use CaF
2, NaF person.
[table 4]
| The casting steel grade | Embodiment | ||||||||||||
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | ||
| Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | SUS 304 | SUS3 04 | SUS4 20 | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | ||
| Operating condition | Casting size (mm) | 250 × 1000 | 250 × 1000 | 150 × 150 | 140 × 140 | 250 × 1000 | 150 × 150 | 200 × 1000 | 200 × 1000 | 250 × 1000 | 250 × 1000 | 250 × 1000 | 250 × 1000 |
| Casting speed m/min | 2.0 | 1.6 | 2.5 | 3.0 | 2.0 | 2.0 | 1.4 | 1.2 | 2.5 | 2.5 | 1.6 | 1.6 | |
| Estimate | Behaviour's industry property 5) | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ○ | ◎ | ◎ |
| Casting sheet surface texture 5) | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ○ | ◎ | ◎ | |
| Overall merit 5) | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ◎ | ○ | ◎ | ◎ | |
Annotate: 5) evaluation=◎; Best, zero; Good, △; Generally, *; Bad
[table 5]
| Embodiment | Comparative example | |||||||||||
| 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | ||
| The casting steel grade | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | Medium carbon steel | |
| Operating condition | Casting size (mm) | 250 × 1000 | 250 × 1000 | 140 × 140 | 250 × 1000 | 250 × 1000 | 250 × 1000 | 140 × 140 | 250 × 1000 | 250 × 1000 | 150 × 150 | 140 × 140 |
| Casting speed m/min | 2.0 | 1.6 | 3.0 | 2.5 | 2.5 | 1.6 | 3.0 | 1.6 | 1.8 | 2.0 | 1.6 | |
| Estimate | Behaviour's industry property 5) | ○ | ○ | ○ | ○ | ○ | ○ | ○ | ○ | ○ | ○ | ○ |
| Casting sheet surface texture 5) | ○ | ○ | ○ | ○ | ○ | ○ | ○ | × | × | △ | △ | |
| Overall merit 5) | ○ | ○ | ○ | ○ | ○ | ○ | ○ | △ | △ | △ | △ | |
Annotate: 5) evaluation=◎; Best, zero; Good, △; Generally, *; Bad
[table 6]
| Chemical composition | |||||||
| Steel grade | C | Si | Mn | P | S | Ni | Cr |
| Medium carbon steel | 0.10 | 0.2 | 0.5 | 0.02 | 0.01 | tr | tr |
| SUS420 | 0.15～0.30 | 0.5 | 0.5 | 0.02 | 0.01 | 0.1 | 13.0 |
| SUS304 | 0.03 | 0.5 | 1.0 | 0.02 | 0.01 | 8.0 | 18.0 |
As mentioned above, continuous casting according to the present invention is with crystallizer fluxing agent and continuous casing, the crystallization rate of the crystal grain that can improve when flowing into mold and casting crystallizer fluxing agent between sheet and solidify by miniaturization, can realize that the change that slow cooling in the mold is but changed with local heat stream reduces, and can stably cast high-quality steel continuously.
In addition, according to the present invention, available easy method is carried out the evaluation of crystallizer fluxing agent, in estimating, this uses suitable evaluation mold, can observe the molten condition of crystallizer fluxing agent exactly, and can correctly estimate the characteristic of crystallizer fluxing agent before use, so, can produce the second best in quality casting sheet with level and smooth beautiful cast(ing) surface.
Claims (2)
1. the continuous casting crystallizer fluxing agent of steel, it is characterized in that, as having metal or its compound that makes crystal grain miniaturization effect, added percentage by weight and be 0.2～5.0, particle diameter is Mn or the Mn compound of 0.4 μ m～100 μ m, make that thus the interior crystalline particle diameter of test portion vertical section that obtains with specific crystallizer fluxing agent evaluation method is 0.1～9.0mm, it is more than 70% that the particle of this diameter accounts for the full face ratio of test portion.
2. the continuous casting crystallizer fluxing agent of steel as claimed in claim 1 is characterized in that, above-mentioned Mn compound is Fe-Mn, Si-Mn, MnO, Mn
2O
3, Mn
3O
4, MnCO
3And MnSO
4
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97125394A CN1075407C (en) | 1997-12-12 | 1997-12-12 | Steel continuous casting crystallizer fluxing agent, evaluating method, casting mould for testing and continuous casting method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97125394A CN1075407C (en) | 1997-12-12 | 1997-12-12 | Steel continuous casting crystallizer fluxing agent, evaluating method, casting mould for testing and continuous casting method |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 01121664 Division CN1233488C (en) | 2001-06-20 | 2001-06-20 | Steel continuous casting method |
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| Publication Number | Publication Date |
|---|---|
| CN1219447A CN1219447A (en) | 1999-06-16 |
| CN1075407C true CN1075407C (en) | 2001-11-28 |
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|---|---|---|---|
| CN97125394A Expired - Fee Related CN1075407C (en) | 1997-12-12 | 1997-12-12 | Steel continuous casting crystallizer fluxing agent, evaluating method, casting mould for testing and continuous casting method |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1049117A (en) * | 1989-07-31 | 1991-02-13 | 重庆大学 | Presmelting vitrification continuous casting protective slag and production technology thereof |
| CN1021710C (en) * | 1991-01-19 | 1993-07-28 | 张家玮 | High accuracy force transmission device |
| CN1082957A (en) * | 1992-07-18 | 1994-03-02 | 东北工学院 | With the wollastonite is the pouring in steel smelting covering slag of base-material |
| CN1130110A (en) * | 1994-11-11 | 1996-09-04 | 日本钢管株式会社 | Casting powder for steel continuous casting |
-
1997
- 1997-12-12 CN CN97125394A patent/CN1075407C/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1049117A (en) * | 1989-07-31 | 1991-02-13 | 重庆大学 | Presmelting vitrification continuous casting protective slag and production technology thereof |
| CN1021710C (en) * | 1991-01-19 | 1993-07-28 | 张家玮 | High accuracy force transmission device |
| CN1082957A (en) * | 1992-07-18 | 1994-03-02 | 东北工学院 | With the wollastonite is the pouring in steel smelting covering slag of base-material |
| CN1130110A (en) * | 1994-11-11 | 1996-09-04 | 日本钢管株式会社 | Casting powder for steel continuous casting |
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| CN1219447A (en) | 1999-06-16 |
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