WO2011004507A1 - 鋼の連続鋳造用モールドフラックスおよびこれを用いた鋼の連続鋳造方法 - Google Patents
鋼の連続鋳造用モールドフラックスおよびこれを用いた鋼の連続鋳造方法 Download PDFInfo
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- WO2011004507A1 WO2011004507A1 PCT/JP2009/064429 JP2009064429W WO2011004507A1 WO 2011004507 A1 WO2011004507 A1 WO 2011004507A1 JP 2009064429 W JP2009064429 W JP 2009064429W WO 2011004507 A1 WO2011004507 A1 WO 2011004507A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/10—Supplying or treating molten metal
- B22D11/108—Feeding additives, powders, or the like
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/076—Use of slags or fluxes as treating agents
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- the present invention relates to a mold flux for continuously casting a billet of steel having a circular cross section, and a continuous casting method using the same.
- a billet having a circular cross section (hereinafter referred to as a “round billet”) is continuously cast, the solidified shell in the mold traps bubbles, and defects resulting from this (hereinafter referred to as “bubble defects”) are round. Often occurs on the surface of the billet. In addition, the thickness of the solidified shell of the round billet grows unevenly, so that vertical cracks often occur on the surface of the round billet.
- the basicity of the mold flux is set to a predetermined value or more. Mold flux is added to the surface of the molten steel in the mold for the purpose of preventing oxidation of the molten steel in the mold of the continuous casting machine and maintaining good lubricity between the mold and the slab.
- Patent Documents 1 to 7 describe mold fluxes that prevent the occurrence of bubble defects or vertical cracks when continuously casting round billets.
- Patent Document 1 discloses a method for suppressing oxidation of Mn in molten steel.
- the method is that of T. in mold flux (mold powder).
- the mass concentration ratio of CaO to SiO 2 (hereinafter also referred to as “basicity”) is increased to 1.0 or more.
- the concentration of CaO is the concentration of CaO in the mold flux obtained by converting all Ca in the mold flux as oxides.
- Patent Document 1 further discloses a method for adjusting the freezing point of the mold flux to a predetermined range, or by setting the MgO concentration to 5 to 15%, the Na 2 O concentration to 4 to 15%, and the F concentration to 5% or less.
- a method for adjusting the viscosity of the mold flux to a predetermined range is disclosed.
- Patent Document 2 the lubricity in the mold is maintained even when a mold flux having a basicity of 0.9 to 1.3 is mixed with a predetermined concentration of carbonate and cast at a high speed of 2 m / min or more.
- a method for adjusting the melting rate of the mold flux is disclosed.
- Patent Document 3 discloses a method in which the basicity of the mold flux is 0.6 to 0.9 in order to prevent the formation of a rim (an air gap between the mold and the solidified shell) in the mold. . Also, by setting the Na 2 O concentration in the mold flux to 5% or less and the F concentration to 1.0 to 7.0%, the melting point of the mold flux is increased to 1423K or more, and the solidified shell is cooled slowly. A method for preventing longitudinal cracks is disclosed.
- Patent Document 4 discloses a method for increasing the heat transfer resistance necessary for slow cooling by promoting crystallization of akermanite in a film existing between a mold and a solidified shell.
- Patent Document 5 gelite is dissolved in akermanite and the composition of the crystal phase is made mellite, thereby increasing the basicity to 1.1 or more without lowering the viscosity, and oxidizing and molding the components in the molten steel.
- a method for preventing the flux from being caught in molten steel is disclosed.
- the mellite is a solid solution of all of akermanite (Ca 2 MgSi 2 O 7 ) and gehlenite (Ca 2 Al 2 SiO 7 ).
- Patent Document 6 discloses that in a basicity range of 1.0 to 1.5, the total concentration of Al 2 O 3 and MgO, the total concentration of alkali metal oxides, the F concentration, the total concentration of FeO and MnO, and S A method for stabilizing crystallization of melite by adjusting the concentration is disclosed.
- Patent Document 7 crystallization of melite is promoted by adjusting the total concentration of Al 2 O 3 and MgO and the TiO 2 concentration within a basicity range of 1.1 to 1.6. , F, Na 2 O, and Li 2 O are adjusted, and a method of simultaneously depositing cuspidine (Ca 4 Si 2 O 7 F 2 ) is disclosed. According to this method, crystallization of melite can be stabilized, and unstable changes in viscosity can be eliminated.
- the stable crystallization of melite is the lubricity between the mold and the round billet and the stable cooling effect of the solidified shell.
- the stability of the crystallization of melilite and the stability of the effect of cooling the solidified shell vary depending on the casting conditions such as the steel type of the round billet, the casting speed, and the cleanliness of the molten steel.
- the methods disclosed in the above-mentioned patent documents are not necessarily sufficient to maintain these stability, and further improvement remains as a problem.
- the present invention has been made in view of the above problems, and an object of the present invention is to provide a mold flux for continuous casting of a round billet that is effective in preventing the occurrence of bubble defects and vertical cracks. It is another object of the present invention to provide a mold flux that makes the crystallization of melite more stable and exhibits more excellent effects in the slow cooling of the solidified shell and the stability of the melt physical properties. Furthermore, it aims at providing the continuous casting method using this mold flux.
- the basicity is an important parameter for adjusting the degree of crystallization of the mold flux.
- the appropriate range of basicity varies depending on the crystal phase to be promoted for crystallization.
- the concentration of the components of the mold in the flux other than CaO and SiO 2 the proper range of the basicity varies variously.
- the concentration of Al 2 O 3 and MgO as constituent components of melite and Na 2 O and Li 2 O as solvent components.
- concentration of F and F the appropriate range of basicity varies in a complex manner.
- the basicity range for promoting crystallization of melite is 1.0 to 1.5 or 1.1 to 1... Regardless of the concentration of each component in the mold flux. Only a certain range of 6 mag was specified, and the influence of the concentration of each component was not considered.
- Al 2 O 3 is a component having a large concentration change in a mold flux when casting a round billet. Further, Al 2 O 3 is a constituent of melite and has a direct influence on the crystallization of melite. For this reason, attention was paid to the change in the composition of melilite due to the Al 2 O 3 concentration.
- melite is a full solid solution of akermanite (Ca 2 MgSi 2 O 7 ) and gehlenite (Ca 2 Al 2 SiO 7 ).
- akermanite Ca 2 MgSi 2 O 7
- gehlenite Ca 2 Al 2 SiO 7
- This change in composition is thought to be due to an increase in the concentration of Al 2 O 3, a concomitant decrease in the concentration of MgO, and an increase in basicity.
- F is preferentially bonded to an alkali metal, and the remaining F is considered to be bonded to Ca.
- Ca is present as an oxide other than those bonded to F.
- the inventors of the present invention have stabilized the crystalline phase such as cuspidine (Ca 4 Si 2 O 7 F 2 ) containing, for example, F, which is evaluated while considering the presence of F. It was found that the present invention is effective not only in the case where it is present in the mold, but also in accurately predicting the mold flux composition in which the mellite is stably present.
- the present invention has been made on the basis of the above knowledge, and the gist of the present invention is the following (1) mold flux for continuous casting of steel and (2) the continuous casting method of steel.
- W T. CaO is T.
- W F is F content
- W Li2O, W Na2O, W K2O are each alkali metal oxides Li 2 O, Na 2 O, K 2 O content of
- W SiO2 is SiO 2 content
- W Al2O3 is the Al 2 O 3 content
- W MgO is the MgO content, and each is represented by mass%.
- the mold flux for continuous casting of steel described in the above (1) may contain one or more of TiO 2 and ZrO 2 , and the total content thereof may be 8% by mass or less.
- the specific water amount is 0.2 to 1.6 L / kg when the slab is subjected to secondary cooling using cooling water.
- % representing the component composition and concentration (content ratio) of steel and mold flux means “mass%”.
- the crystallization of melilite is stabilized in the mold flux, and it is possible to prevent bubble defects and vertical cracks generated on the surface of the round billet.
- the mold flux composition (basicity) according to the concentration of Al 2 O 3 , it is possible to further stabilize the crystallization of melite.
- a high-quality round billet free from bubble defects and vertical cracks on the surface can be stably produced.
- the mold flux of the present invention includes SiO 2 , T.I. CaO, Al 2 O 3 and MgO are the main components.
- the mold flux contains one or more alkali metal oxides and further contains F.
- the mold flux, freezing point, viscosity, to adjust the surface tension and the like, if desired, can be added TiO 2, ZrO 2, MnO and the like as appropriate.
- the T.V. concentration for SiO 2 concentration W SiO2 in the mold flux For the main component, the T.V. concentration for SiO 2 concentration W SiO2 in the mold flux. CaO concentration W CaO ratio (basicity) T.
- the range of CaO / SiO 2 is 0.7 to 2.0, the concentration W Al2O3 of Al 2 O 3 is 35% or less, and the concentration W MgO of MgO is 20% or less.
- the total concentration of alkali metal oxides is 8% or less, and the concentration WF of F is 7% or less.
- YSiO2 XSiO2 / ( XSiO2 + XCaO + XAl2O3 + XMgO )
- YCaO XCaO / ( XSiO2 + XCaO + XAl2O3 + XMgO )
- YAl2O3 XAl2O3 / ( XSiO2 + XCaO + XAl2O3 + XMgO )
- YMgO XMgO / ( XSiO2 + XCaO + XAl2O3 + XMgO ) (e)
- the basicity (T.CaO / SiO 2 ) range of the mold flux of the present invention is 0.7 to 2.0.
- the basicity suitable for stabilizing the crystallization of melite varies depending on the Al 2 O 3 concentration W Al2O3 as described above. Therefore, the converted basicity (Y CaO / Y SiO2 ) of the mold flux is set within the range described by the above formula (a). This, with increasing Y Al2 O3, in which the proper scope of the terms basicity Y CaO / Y SiO2 to promote crystallization of the melilite is corresponding to that increase.
- the composition of the mold flux is whatever the Al 2 O 3 concentration. Is separated from the crystal phase of akermanite or gehlenite, it becomes difficult to crystallize the mold flux.
- Al 2 O 3 is difficult to remove completely from the mold flux. Further, due to the absorption of inclusions in the molten steel by the mold flux and the oxidation reaction of Al in the molten steel, the concentration of Al 2 O 3 increases in the mold flux during casting.
- the concentration of Al 2 O 3 in the mold flux is set to 35% or less.
- the range of MgO concentration W MgO is 20% or less.
- the concentration of MgO exceeds 20%, the mold flux has a freezing point of 1300 ° C. or higher. In this case, it becomes difficult for the mold flux to function as a lubricant, and it cannot be used for continuous casting. Therefore, the MgO concentration in the mold flux is 20% or less.
- the preferred range for crystallization of akermanite is 5 to 18%, and the more preferred range is 6 to 15%.
- ⁇ Reason for limiting the concentration of alkali metal oxide and F> By adding alkali metal oxide and F to the mold flux, the freezing point or viscosity can be adjusted. If the alkali metal oxide is excessively added to the mold flux, the alkali metal oxide may be excessively sintered in the mold, which may lower the melting rate of the mold flux. Therefore, the concentration of the alkali metal oxide is 8% or less.
- the concentration W F of F is set to 7% or less.
- the concentration of F is preferably 6% or less, and more preferably 5% or less.
- TiO 2 and ZrO 2 may be added to the mold flux of the present invention. These are effective for adjusting the viscosity of the mold flux. Furthermore, ZrO 2 is effective in promoting crystallization of mold flux and reducing nozzle melt damage in a continuous casting machine.
- the addition amount of TiO 2 and ZrO 2 is preferably set to 8% or less in total of the TiO 2 concentration W TiO2 and ZrO 2 concentration W ZrO2. If the concentration exceeds 8%, the freezing point or viscosity of the mold flux becomes excessively high, and sufficient lubricity in the mold cannot be obtained.
- One method for reducing the change in the composition of the mold flux during casting is to add MnO to the mold flux in advance.
- the concentration of MnO in the mold flux increases when Mn in the molten steel is oxidized to MnO.
- the addition of MnO to the mold flux works effectively in that the increase in the MnO concentration is suppressed by increasing the activity of MnO in the mold flux in advance.
- the MnO concentration is desirably 5% or less. If the MnO concentration is higher than 5%, the viscosity of the mold flux is excessively lowered, so that the mold flux is entangled in the molten steel in the mold.
- ⁇ CaO source, SiO 2 source and Al 2 O 3 source As a CaO source, a SiO 2 source, or an Al 2 O 3 source, a CaSi alloy, a metal Si, or a CaAl alloy can be blended in the mold flux, respectively. These metals and alloys oxidize in the high temperature mold and eventually become oxides. The heat generated during oxidation effectively acts to keep the molten steel warm. Iron oxide may be applied as a combustor for these metals and alloys, and may be blended in the mold flux.
- the continuous casting method of steel of the present invention is a method of casting a round billet using the above-described continuous casting mold flux of the present invention.
- the specific water amount of secondary cooling (the amount of water used for secondary cooling per kg of slab) is preferably 0.2 to 1.6 L / kg. If it is less than 0.2 L / kg, the roundness of the round billet (slab) is impaired, so that it is difficult to make a pipe using the round billet. If it exceeds 1.6 L / kg, the surface of the round billet is excessively cooled, and cracking may occur on the surface when correcting the curvature of the round billet that occurs during casting.
- Test method 1-1 About Mold Flux
- Table 1 basicity in addition to the composition (component concentration) (T.CaO / SiO 2), in terms of the basicity of (Y CaO / Y SiO2) and Y CaO / Y SiO2 defined by the equation (a) The range is also listed.
- Samples B, E, J, M, Q, T, W, and Y are compositions within the composition range defined in the present invention, and are examples of the present invention.
- Samples A, D, G, H, L, P, S, and V are comparative examples in which the value of Y CaO / Y SiO 2 is out of the range defined by the above formula (a).
- Samples C, F, K, N, R, U, and X are comparative examples in which the value of Y CaO / Y SiO 2 deviates significantly from the range defined by the above formula (a).
- Example 2 was adopted.
- Sample Z was a comparative example in which the F concentration deviated higher than the range defined in the present invention, and the classification in Table 1 was Comparative Example 3.
- Each sample was heated in a crucible, and the viscosity at 1300 ° C. and the freezing point were measured using a vibrating piece type viscometer. Moreover, after measuring the viscosity and the freezing point, the properties of the sample solidified in the crucible were observed.
- the round billet was made of medium carbon steel having a cross-sectional diameter of 225 mm, a C concentration of 0.10 to 0.23%, and an Mn concentration of 0.60 to 1.40%.
- the drawing speed was in the range of 2.0 to 2.4 mm / min.
- Test results 2-1 About Mold Flux As shown in Table 2, the evaluation index for mold flux was the freezing point of each sample, the viscosity at 1300 ° C., and the properties after solidification.
- the mold flux of the example of the present invention had a freezing point of 1176 to 1249 ° C. and a viscosity at 1300 ° C. of about 2 to 7 poise. Further, mellite was precipitated in all the samples after solidification.
- the mold flux of Comparative Example 1 has a freezing point of 1084 to 1176 ° C., which is lower than the mold flux of the example of the present invention, and the sample after solidification was basically glassy.
- the mold fluxes of Comparative Example 2 each had a freezing point of 1300 ° C. or higher, and could not be used for continuous casting.
- evaluation indexes for continuous casting of round billet were bubble defects, vertical cracks, and mold temperature fluctuation.
- Table 3 shows the solidification point of the mold flux used, the viscosity at 1300 ° C., the basicity, and the specific water amount of secondary cooling during casting.
- the specific water amount of the secondary cooling was basically constant with 1.2 L / kg as a standard.
- continuous casting was performed under three kinds of conditions with secondary cooling specific water amounts of 1.2, 0.2, and 1.6 L / kg.
- ⁇ indicates that there was no defect, ⁇ indicates that maintenance was required, and X indicates that the product could not be made even by maintenance. It shows that.
- ⁇ indicates that the fluctuation was small and stable, ⁇ indicates that there was a slight fluctuation, but an operation that would reduce the casting speed was unnecessary, and x indicates fluctuation. It is large and shows that it has been forced to reduce the casting speed.
- the mold fluxes of Comparative Example 1 had a low basicity. Therefore, in the round billet obtained using these mold fluxes, bubble defects were scattered on the surface. All of the round billets were evaluated as x for bubble defects, and could not be made into products even by care.
- the round billet obtained using the mold fluxes of Comparative Examples 1 and 3 had a vertical crack evaluation of ⁇ or x, and vertical cracks occurred on the surface to various degrees.
- the round billet obtained using the samples G and V having a freezing point of about 1100 ° C. or less had a wide open vertical crack and had to be handled as scrap.
- Sample Z which is Comparative Example 3
- the crystallization that occurs in the film becomes unstable, so that the mold temperature fluctuates greatly and a breakout prediction alarm is activated.
- Samples P and S which are Comparative Example 1, all had a freezing point of 1176 ° C. or lower, which was lower than the mold flux of the present invention example. For this reason, the obtained round billet had slight dents and vertical cracks, which required maintenance. Although the casting could be continued, the mold temperature fluctuated slightly.
- the crystallization of melilite is stabilized in the mold flux, and it is possible to prevent bubble defects and vertical cracks generated on the surface of the round billet.
- the composition (basicity) of the mold flux is defined according to the concentration of Al 2 O 3 , it is possible to further stabilize the crystallization of melite.
- a high-quality round billet free from bubble defects and vertical cracks on the surface can be stably produced.
- the mold flux for continuous casting of steel of the present invention can be widely applied to continuous casting of slabs including round billets.
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Abstract
Description
(CaF2)+(Na2O)→(CaO)+2(NaF) …(A)
質量%で表される含有率で、T.CaO含有率のSiO2含有率に対する比「T.CaO/SiO2」が0.7~2.0、Al2O3含有率が35%以下、MgO含有率が20%以下、アルカリ金属酸化物の合計含有率が8%以下、およびF含有率が7%以下であるモールドフラックスであって、
下記(b)~(e)式で示される各含有率分率が、下記(a)式を満たすことを特徴とする鋼の連続鋳造用モールドフラックス。
0.63+2.51×YAl2O3≦YCaO/YSiO2≦1.23+2.51×YAl2O3 …(a)
ここで、
YSiO2=XSiO2/(XSiO2+XCaO+XAl2O3+XMgO) …(b)
YCaO=XCaO/(XSiO2+XCaO+XAl2O3+XMgO) …(c)
YAl2O3=XAl2O3/(XSiO2+XCaO+XAl2O3+XMgO) …(d)
YMgO=XMgO/(XSiO2+XCaO+XAl2O3+XMgO) …(e)
である。
また、
XCaF2=(WF-1.27×WLi2O-0.613×WNa2O-0.403×WK2O)×2.05 …(f)
XCaO=WT.CaO-XCaF2×0.718 …(g)
XSiO2=WSiO2 …(h)
XAl2O3=WAl2O3 …(i)
XMgO=WMgO …(j)
である。
ここで、WT.CaOはT.CaO含有率、WFはF含有率、WLi2O、WNa2O、WK2Oはそれぞれアルカリ金属酸化物であるLi2O、Na2O、K2Oの含有率、WSiO2はSiO2含有率、WAl2O3はAl2O3含有率、WMgOはMgO含有率であり、それぞれ質量%で表される。
〈モールドフラックスの組成の範囲について〉
本発明のモールドフラックスは、SiO2、T.CaO、Al2O3およびMgOを主成分とする。また、モールドフラックスは、アルカリ金属酸化物を1種または2種以上、さらにFを含有する。また、モールドフラックスは、凝固点、粘度、表面張力などの調整のため、必要に応じて、TiO2、ZrO2、MnO等を適宜添加することができる。
0.63+2.51×YAl2O3≦YCaO/YSiO2≦1.23+2.51×YAl2O3 …(a)
YSiO2=XSiO2/(XSiO2+XCaO+XAl2O3+XMgO) …(b)
YCaO=XCaO/(XSiO2+XCaO+XAl2O3+XMgO) …(c)
YAl2O3=XAl2O3/(XSiO2+XCaO+XAl2O3+XMgO) …(d)
YMgO=XMgO/(XSiO2+XCaO+XAl2O3+XMgO) …(e)
XCaF2=(WF-1.27×WLi2O-0.613×WNa2O-0.403×WK2O)×2.05 …(f)
XCaO=WT.CaO-XCaF2×0.718 …(g)
XSiO2=WSiO2 …(h)
XAl2O3=WAl2O3 …(i)
XMgO=WMgO …(j)
上述のように、本発明のモールドフラックスの塩基度(T.CaO/SiO2)の範囲は、0.7~2.0である。この範囲において、meliliteの結晶化を安定させるのに好適な塩基度は、上述のようにAl2O3の濃度WAl2O3によって変化する。そのため、モールドフラックスの換算塩基度(YCaO/YSiO2)は、上記(a)式により記載される範囲内に設定する。これは、YAl2O3の上昇とともに、meliliteの結晶化を促進するための適正な換算塩基度YCaO/YSiO2の範囲が上昇することに対応したものである。
MgOは、akermaniteを結晶化させるために、モールドフラックスの初期組成において添加することが有効である。本発明のモールドフラックスにおいて、MgOの濃度WMgOの範囲は20%以下である。モールドフラックスは、MgOの濃度が20%を超えて大きいと、凝固点が1300℃以上になる。この場合、モールドフラックスは、潤滑剤としての機能を果たすことが困難になり、連続鋳造に使用することができない。そのため、モールドフラックス中のMgOの濃度は、20%以下とする。この濃度範囲において、akermaniteの結晶化に好適な範囲は5~18%、さらに好適な範囲は6~15%である。
モールドフラックスにアルカリ金属酸化物およびFを添加することにより、凝固点または粘度を調節することができる。アルカリ金属酸化物は、モールドフラックスに過剰に添加すると、鋳型内で過剰に焼結し、かえってモールドフラックスの溶融速度を低下させる可能性がある。そのため、アルカリ金属酸化物の濃度は、8%以下とする。
本発明のモールドフラックスには、TiO2およびZrO2の1種以上を添加してもよい。これらはモールドフラックスの粘性の調整に有効である。さらにZrO2は、モールドフラックスの結晶化の促進や、連続鋳造機のノズル溶損の軽減に有効である。TiO2およびZrO2の添加量は、TiO2の濃度WTiO2およびZrO2の濃度WZrO2の合計で8%以下とすることが望ましい。8%を超えて大きい濃度とすると、モールドフラックスの凝固点または粘度が過度に高くなり、鋳型内の潤滑性が十分に得られない。
鋳造中のモールドフラックスの組成変化を小さくする方法の一つとして、あらかじめモールドフラックス中にMnOを添加しておくことが挙げられる。モールドフラックス中のMnOの濃度は、溶鋼中のMnが酸化してMnOとなることにより増加する。モールドフラックスへのMnOの添加は、モールドフラックス中のMnOの活量をあらかじめ増大させることにより、MnOの濃度の上昇を抑制する点で有効に作用する。
CaO源、SiO2源またはAl2O3源として、それぞれCaSi合金、金属SiまたはCaAl合金を、モールドフラックスに配合することができる。これらの金属および合金は、高温の鋳型内において酸化し、最終的には酸化物となる。酸化の際の発熱が、溶鋼の保温に有効に作用する。これらの金属および合金の助燃剤として、酸化鉄を適用し、モールドフラックスに配合してもよい。
本発明の鋼の連続鋳造方法は、上述の本発明の連続鋳造用モールドフラックスを用いて丸ビレットを鋳造する方法である。
本発明の鋼の連続鋳造方法において、二次冷却の比水量(鋳片1kgあたりの二次冷却に用いる水の量)は、0.2~1.6L/kgが望ましい。0.2L/kg未満では、丸ビレット(鋳片)の真円度が損なわれるため、この丸ビレットを用いた製管が困難となる。1.6L/kgを超えて大きいと丸ビレットの表面が過度に冷却され、鋳造時に生じた丸ビレットの湾曲を矯正する際に、表面に割れが生じることがある。
1-1.モールドフラックスについて
丸ビレットの連続鋳造試験を行うために、表1に示す24種類の組成のモールドフラックスを試料として作製した。表1には、組成(成分濃度)に加えて塩基度(T.CaO/SiO2)、換算塩基度(YCaO/YSiO2)および上記(a)式により規定されるYCaO/YSiO2の範囲も記載している。
丸ビレットは、湾曲型の連続鋳造機を使用し、表1に示すモールドフラックスを用いて鋳造した。ただし、比較例2のモールドフラックスは、後述のように連続鋳造に使用できなかった。丸ビレットは、断面の直径が225mmであり、C濃度が0.10~0.23%、Mn濃度が0.60~1.40%の中炭素鋼からなるものであった。引き抜き速度は、2.0~2.4mm/minの範囲とした。
2-1.モールドフラックスについて
モールドフラックスについての評価指標は、表2に示すように、各々の試料の凝固点、1300℃における粘度および凝固後の性状とした。
丸ビレットの連続鋳造についての評価指標は、表3に示すように、気泡性欠陥、縦割れおよび鋳型温度の変動とした。表3には、これらの評価指標に加えて、使用したモールドフラックスの凝固点、1300℃における粘度、塩基度および鋳造時の二次冷却の比水量を示した。二次冷却の比水量は1.2L/kgを標準として、基本的に一定とした。ただし、試料Jのモールドフラックスを用いた試験では、二次冷却の比水量を1.2、0.2および1.6L/kgとした3種類の条件で連続鋳造を行った。
Claims (4)
- SiO2、T.CaO、Al2O3およびMgOを主成分とし、アルカリ金属酸化物を1種または2種以上、さらに成分Fを含有し、
質量%で表される含有率で、T.CaO含有率のSiO2含有率に対する比「T.CaO/SiO2」が0.7~2.0、Al2O3含有率が35%以下、MgO含有率が20%以下、アルカリ金属酸化物の合計含有率が8%以下、およびF含有率が7%以下であるモールドフラックスであって、
下記(b)~(e)式で示される各含有率分率が、下記(a)式を満たすことを特徴とする鋼の連続鋳造用モールドフラックス。
0.63+2.51×YAl2O3≦YCaO/YSiO2≦1.23+2.51×YAl2O3 …(a)
ここで、
YSiO2=XSiO2/(XSiO2+XCaO+XAl2O3+XMgO) …(b)
YCaO=XCaO/(XSiO2+XCaO+XAl2O3+XMgO) …(c)
YAl2O3=XAl2O3/(XSiO2+XCaO+XAl2O3+XMgO) …(d)
YMgO=XMgO/(XSiO2+XCaO+XAl2O3+XMgO) …(e)
である。
また、
XCaF2=(WF-1.27×WLi2O-0.613×WNa2O-0.403×WK2O)×2.05 …(f)
XCaO=WT.CaO-XCaF2×0.718 …(g)
XSiO2=WSiO2 …(h)
XAl2O3=WAl2O3 …(i)
XMgO=WMgO …(j)
である。
ここで、WT.CaOはT.CaO含有率、WFはF含有率、WLi2O、WNa2O、WK2Oはそれぞれアルカリ金属酸化物であるLi2O、Na2O、K2Oの含有率、WSiO2はSiO2含有率、WAl2O3はAl2O3含有率、WMgOはMgO含有率であり、それぞれ質量%で表される。 - TiO2およびZrO2の1種以上を含有し、その合計の含有率が8質量%以下であることを特徴とする請求項1に記載の鋼の連続鋳造用モールドフラックス。
- 請求項1または2に記載の連続鋳造用モールドフラックスを用いて丸鋳片を鋳造することを特徴とする鋼の連続鋳造方法。
- 冷却水を用いて鋳片に二次冷却を施す際に比水量を0.2~1.6L/kgとすることを特徴とする請求項3に記載の鋼の連続鋳造方法。
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EP09760453.2A EP2441541A4 (en) | 2009-07-07 | 2009-08-18 | Mold flux for continuous casting of steel and method for continuous casting of steel using same |
KR1020107000846A KR101247459B1 (ko) | 2009-07-07 | 2009-08-18 | 강의 연속 주조용 몰드 플럭스 및 이것을 이용한 강의 연속 주조 방법 |
JP2009536546A JP5136994B2 (ja) | 2009-07-07 | 2009-08-18 | モールドフラックスを用いた鋼の連続鋳造方法 |
CN200980100098.5A CN102006950B (zh) | 2009-07-07 | 2009-08-18 | 钢的连铸用保护渣的制造方法及使用该保护渣的钢的连铸方法 |
BRPI0903505-2A BRPI0903505B1 (pt) | 2009-07-07 | 2009-08-18 | Pó fluxante para lingotamento contínuo de aço |
US12/618,932 US20110005705A1 (en) | 2009-07-07 | 2009-11-16 | Mold flux for continuously casting steel and method of continuously casting steel using the same |
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CN113714476A (zh) * | 2021-08-30 | 2021-11-30 | 湖南华菱湘潭钢铁有限公司 | 一种改善小方坯表面质量的工艺方法 |
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EP3372325B1 (en) * | 2015-11-05 | 2020-07-08 | Nippon Steel Corporation | Mold flux for continuous casting and continuous casting method using it |
CN107498014B (zh) * | 2017-09-06 | 2019-11-15 | 中南大学 | 一种含ZrO2汽车用TWIP钢保护渣及其应用 |
CN113939376B (zh) * | 2019-06-04 | 2023-04-11 | 杰富意钢铁株式会社 | 含Al亚包晶钢的连续铸造用保护渣和连续铸造方法 |
CN113953473B (zh) * | 2021-11-22 | 2022-12-30 | 天津荣程联合钢铁集团有限公司 | 一种连铸结晶器用保护渣及其制备方法 |
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JP2003326342A (ja) * | 2002-05-15 | 2003-11-18 | Sumitomo Metal Ind Ltd | 鋼の連続鋳造用モールドパウダ |
JP2005052881A (ja) * | 2003-08-07 | 2005-03-03 | Sumitomo Metal Ind Ltd | 鋼の連続鋳造方法 |
JP2007203364A (ja) * | 2006-02-06 | 2007-08-16 | Sumitomo Metal Ind Ltd | 鋼の連続鋳造用モールドパウダー |
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See also references of EP2441541A4 * |
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CN113714476A (zh) * | 2021-08-30 | 2021-11-30 | 湖南华菱湘潭钢铁有限公司 | 一种改善小方坯表面质量的工艺方法 |
CN113714476B (zh) * | 2021-08-30 | 2023-01-24 | 湖南华菱湘潭钢铁有限公司 | 一种改善小方坯表面质量的工艺方法 |
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