TWI673122B - Continuous casting method of steel and method for manufacturing thin steel sheet - Google Patents

Continuous casting method of steel and method for manufacturing thin steel sheet Download PDF

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TWI673122B
TWI673122B TW107128928A TW107128928A TWI673122B TW I673122 B TWI673122 B TW I673122B TW 107128928 A TW107128928 A TW 107128928A TW 107128928 A TW107128928 A TW 107128928A TW I673122 B TWI673122 B TW I673122B
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steel
continuous casting
molten steel
nozzle
slag
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TW201919792A (en
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横山英樹
田宮堅一郎
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日商杰富意鋼鐵股份有限公司
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10Supplying or treating molten metal
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D37/00Controlling or regulating the pouring of molten metal from a casting melt-holding vessel
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/06Ferrous alloys, e.g. steel alloys containing aluminium
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/20Recycling

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Continuous Casting (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

本發明提供一種可抑制微小的礦渣系夾雜物的生成並提高鋼的清潔度的鋼的連續鑄造方法。本發明為一種自澆斗6經由餵槽1而向連續鑄造鑄模14內供給熔鋼15來連續鑄造的鋼的連續鑄造方法,所述鋼的連續鑄造方法的特徵在於:自在長頸噴嘴5的側面開口的氣體流路向在長頸噴嘴5內通過的熔鋼流供給流量Q(NL/min)的氮氣,所述流量Q滿足以下的式(1):2≦Q/W<200×H1/2×D3/2...(1) The present invention provides a continuous casting method of steel that can suppress the generation of minute slag-based inclusions and improve the cleanliness of steel. The present invention is a continuous casting method for continuously casting steel that is supplied from a hopper 6 through a trough 1 to a continuous casting mold 14 by supplying molten steel 15 into the continuous casting mold 14. The continuous casting method for steel is characterized by: The side-opened gas flow path supplies nitrogen gas at a flow rate Q (NL / min) to the molten steel stream passing through the long-necked nozzle 5, and the flow rate Q satisfies the following formula (1): 2 ≦ Q / W <200 × H 1 / 2 × D 3/2 ... (1)

此處,Q:氮氣流量(NL/min)、W:熔鋼流通量(t/min)、H:長頸噴嘴浸漬深度(m)、D:長頸噴嘴內徑(m)。 Here, Q: nitrogen flow rate (NL / min), W: molten steel flow rate (t / min), H: long neck nozzle immersion depth (m), and D: long neck nozzle inner diameter (m).

Description

鋼的連續鑄造方法及薄鋼板的製造方法 Continuous casting method of steel and manufacturing method of thin steel plate

本發明是有關於一種鋼的連續鑄造方法,特別是有關於一種使用在長頸噴嘴(long nozzle)處的氣體吹入的礦渣(slag)流出判定技術的連續鑄造方法與使用該連續鑄造方法的薄鋼板的製造方法,所述長頸噴嘴用以自澆斗(ladle)向連續鑄造餵槽(tundish)內注入熔鋼。 The present invention relates to a continuous casting method for steel, and more particularly, to a continuous casting method using a slag outflow determination technology using a gas blown at a long nozzle and a method using the continuous casting method. In a method for manufacturing a thin steel plate, the long neck nozzle is used to inject molten steel into a continuous casting tank from a ladle.

高清潔度鋼的連續鑄造中,在自澆斗向餵槽內注入熔鋼時,如圖1所示,經由設置於澆斗底部的澆斗上噴嘴7、澆斗滑動噴嘴8及長頸噴嘴5而將熔鋼注入至餵槽內熔鋼中,藉此防止熔鋼的空氣氧化或餵槽礦渣19的捲入。 In the continuous casting of high-cleanness steel, when molten steel is injected from a hopper into a feeding tank, as shown in FIG. 1, via a nozzle 7 on the bottom of the hopper, a sliding nozzle 8 and a long neck nozzle 5) The molten steel is injected into the molten steel in the feeding tank, thereby preventing the air of the molten steel from being oxidized or the slag 19 of the feeding tank being entangled.

專利文獻1、專利文獻2中記載有偵測澆斗礦渣的流出的技術。該技術中,使用圖2所例示的礦渣流出偵測裝置,並使惰性氣體在澆斗噴嘴或長頸噴嘴中流動,藉由惰性氣體的流量或背壓的變化來偵測因澆斗礦渣混入至熔鋼流中所引起的吸引力的變化。藉此,儘早偵測礦渣流出,從而減低成為餵槽內的熔鋼的再氧化的原因的澆斗礦渣的流入量。 Patent Documents 1 and 2 describe techniques for detecting the outflow of a slag in a bucket. In this technology, the slag outflow detection device illustrated in FIG. 2 is used, and an inert gas is flowed in the funnel nozzle or the long-neck nozzle, and the mixing of the slag due to the funnel is detected by the change of the inert gas flow rate or the back pressure. To the change in attraction caused in the molten steel stream. Thereby, the slag outflow is detected as early as possible, thereby reducing the inflow amount of the slag in the hopper, which is the cause of the reoxidation of the molten steel in the feed tank.

專利文獻3中記載有熔鋼淨化方法,其中,為了減低氧化鋁夾雜物,而向餵槽內的熔鋼中投入包含CaO/Al2O3為1.5以上 的夾雜物吸收劑與含有SiO2的熔點降低劑的粉末,從而在熔鋼表面形成沈澱物化礦渣,並使所上浮的氧化鋁夾雜物吸附於礦渣中。 Patent Document 3 describes a method for purifying molten steel. In order to reduce alumina inclusions, molten steel in a feed tank is charged with an inclusion absorbent containing CaO / Al 2 O 3 of 1.5 or more and a SiO 2 containing The powder of the melting point reducing agent forms a precipitated slag on the surface of the molten steel, and causes the floating alumina inclusions to be adsorbed in the slag.

專利文獻4中記載有氣體吹入條件,其目的在於:藉由吹入惰性氣體而使長頸噴嘴內的壓力高於大氣壓,(1)防止由空氣的吸入所引起的熔鋼的再氧化,(2)長頸噴嘴內的惰性氣體的壓力變得過大,而相對於長頸噴嘴的浸漬深度,長頸噴嘴內的熔融金屬液面位置過度降低,藉此防止大量的惰性氣體上浮(沸騰(boiling))至長頸噴嘴的周圍而產生礦渣的捲入。 Patent Document 4 describes gas blowing conditions, the purpose of which is to make the pressure in the long neck nozzle higher than atmospheric pressure by blowing in an inert gas, (1) to prevent the reoxidation of molten steel caused by the inhalation of air, (2) The pressure of the inert gas in the long-necked nozzle becomes too large, and the molten metal liquid position in the long-necked nozzle is excessively lowered relative to the immersion depth of the long-necked nozzle, thereby preventing a large amount of inert gas from floating (boiling (boiling ( boiling)) to the periphery of the long neck nozzle to cause slag entrainment.

專利文獻5中揭示有提高了氮濃度的強度及加工性等優異的罐用鋼板。專利文獻6中揭示有用以向熔鋼中添加氮的、與專利文獻1、專利文獻2類似的礦渣流出偵測方法,且記載有如下方法:自設置於澆斗底部的噴嘴的較用於吹入礦渣流出偵測用的氣體的開孔更靠下游側的開孔吹入含氮的氣體來加氮。 Patent Document 5 discloses a steel sheet for cans which is excellent in strength, workability, and the like in which the nitrogen concentration is increased. Patent Document 6 discloses a method for detecting slag outflow similar to Patent Document 1 and Patent Document 2 for adding nitrogen to molten steel, and describes a method in which a nozzle provided at the bottom of a hopper is more suitable for blowing. The openings of the gas for detecting the outflow of slag are further blown into the openings on the downstream side with nitrogen-containing gas to add nitrogen.

[現有技術文獻] [Prior Art Literature] [專利文獻] [Patent Literature]

[專利文獻1]日本專利特開昭61-262454號公報 [Patent Document 1] Japanese Patent Laid-Open No. 61-262454

[專利文獻2]日本專利特開平2-70372號公報 [Patent Document 2] Japanese Patent Laid-Open No. 2-70372

[專利文獻3]日本專利特開平4-111952號公報 [Patent Document 3] Japanese Patent Laid-Open No. 4-111952

[專利文獻4]日本專利特開平2-187239號公報 [Patent Document 4] Japanese Patent Laid-Open No. 2-187239

[專利文獻5]日本專利特開2007-177315號公報 [Patent Document 5] Japanese Patent Laid-Open No. 2007-177315

[專利文獻6]日本專利特開平4-75767號公報 [Patent Document 6] Japanese Patent Laid-Open No. 4-75767

對鋼要求高清潔度的方面中,對在薄鋼板製品中產生缺陷的夾雜物的成分進行詳細調查,結果判明,大多檢測到餵槽內的礦渣。若餵槽礦渣系的大型夾雜物存在於薄鋼板製品中,則存在製品缺陷的問題以與氧化鋁團簇系的夾雜物的情況不同的形態變得顯著的情況。該些夾雜物藉由軋製而在軋製方向上延伸得長。此時,在為氧化鋁團簇系的夾雜物的情況下,在微小的氧化鋁的一次粒子基本不發生變形地分散於鋼中的狀態下,其存在範圍在軋製方向上擴展得長。相對於此,在為餵槽礦渣系的大型夾雜物的情況下,在保持連續相的狀態下擴展得薄且長,因此藉由呈層狀薄薄地變形的夾雜物而將表背面側的鋼隔開的部分呈線狀形成。另外,夾雜物的變形能力大幅差於鋼,因此表面側的鋼的厚度顯著變薄。特別是,在面向容器的素材等的0.2mm以下等厚度的薄鋼板製品中,有時藉由彎曲或深衝(deep drawing)等加工,在所述鋼變薄的部分破裂而線狀的瑕疵缺陷顯現化,強烈要求礦渣系夾雜物尺寸的極小化或減低礦渣系夾雜物的含量。 In the aspect that steel requires high cleanliness, the composition of inclusions that cause defects in thin steel plate products was investigated in detail. As a result, it was found that most of the slag in the feed tank was detected. If the large-scale inclusions of the trough slag system are present in the thin steel plate product, the problem of product defects may become significant in a form different from the case of the inclusions of the alumina cluster system. These inclusions are extended in the rolling direction by rolling. At this time, in the case of inclusions of the alumina cluster system, in a state in which the primary particles of minute alumina are dispersed in the steel with substantially no deformation, the existence range thereof is extended in the rolling direction. On the other hand, in the case of large-scale inclusions of the trough-feeding slag system, the thin and long are expanded while the continuous phase is maintained. Therefore, the steel on the front and back sides is thinly deformed by the inclusions in a layered manner. The separated parts are formed in a line shape. In addition, the deformability of inclusions is significantly inferior to that of steel, so the thickness of the steel on the surface side is significantly reduced. In particular, in a thin steel plate product having a thickness of 0.2 mm or less, such as a material facing a container, it may be broken at the thinned portion of the steel by a process such as bending or deep drawing, and may cause linear defects. Defects are manifested, and it is strongly required that the size of the slag-based inclusions be minimized or the content of the slag-based inclusions be reduced.

專利文獻3的方法對於氧化鋁系夾雜物的減低而言有效,且對於如上所述般的0.2mm以下等厚度的容器用的薄鋼板製品用素材的連續鑄造而言亦有效。但是,在專利文獻3的方法中,在使用專利文獻1、專利文獻2的朝向長頸噴嘴的氣體吹入的礦渣流出偵測技術的情況下,有如下擔憂:因上浮至餵槽內的熔鋼表面的氣體氣泡所引起的攪拌而生成礦渣系的夾雜物。 The method of Patent Document 3 is effective for reducing alumina-based inclusions, and is also effective for continuous casting of materials for thin steel plate products for containers having a thickness of 0.2 mm or less as described above. However, in the method of Patent Document 3, when the slag outflow detection technology of the gas blown toward the long-necked nozzle of Patent Document 1 and Patent Document 2 is used, there is a concern: Stirring caused by gas bubbles on the steel surface generates slag-based inclusions.

如專利文獻4般,藉由控制朝向長頸噴嘴的氣體吹入條件來防止沸騰,從而可某程度抑制粗大的礦渣系夾雜物的生成。但是,如在如上所述般的0.2mm以下等厚度的容器用的薄鋼板製品中成為問題的微小的礦渣系夾雜物難以充分減低。 As in Patent Document 4, by controlling the gas blowing conditions toward the long neck nozzle to prevent boiling, the generation of coarse slag-based inclusions can be suppressed to a certain extent. However, it is difficult to sufficiently reduce the fine slag-based inclusions that are a problem in thin steel products for containers having a thickness of 0.2 mm or less as described above.

在如專利文獻5般的製造高氮濃度的製品的情況下,雖亦實施一邊以專利文獻6的方式吹入易溶解於熔鋼中的氮氣並進行加氮一邊進行礦渣流出偵測,但就礦渣系夾雜物的減低的觀點而言,無法獲得充分的效果。 In the case of manufacturing a product with a high nitrogen concentration as in Patent Document 5, although slag outflow detection is also performed while blowing nitrogen that is easily soluble in molten steel in the manner of Patent Document 6 and adding nitrogen, From the viewpoint of reduction of slag-based inclusions, a sufficient effect cannot be obtained.

即,本發明鑒於所述課題而目的在於提供一種可抑制微小的礦渣系夾雜物的生成並提高鋼的清潔度的鋼的連續鑄造方法及使用該連續鑄造方法的薄鋼板的製造方法。 That is, in view of the said subject, this invention aims at providing the continuous casting method of steel which can suppress generation | occurrence | production of minute slag-type inclusions, and improves the cleanliness of steel, and the manufacturing method of the thin steel plate using this continuous casting method.

為了解決所述課題,本發明者等人進行了努力研究,結果可知,餵槽內的礦渣以微小的夾雜物的形式混入至熔鋼中的原因在於:藉由來自長頸噴嘴的礦渣流出偵測用的氣體吹入而小徑的氣體氣泡上浮至餵槽內的礦渣/熔鋼界面。而且,判明先前通常所使用的Ar氣體可成為礦渣系夾雜物減低的障礙。具體而言,Ar氣體不易溶解於熔鋼中,因此在餵槽內熔鋼內以氣泡的形式上浮,於在礦渣/熔鋼界面通過時,會生成微小的熔融礦渣滴。為了解決該問題,本發明者等人進一步進行研究,結果發現,重要的是:在礦渣流出偵測用的氣體吹入中,代替Ar氣體而使用易溶解於熔鋼內的氮氣,而且根據與熔鋼流通量、長頸噴嘴浸漬深度及 長頸噴嘴內徑的關係而將氮氣流量調整為規定的範圍。藉此,在自吹入氣體起至氣泡到達至餵槽內的熔鋼表面的過程中,使氣泡溶解於鋼中,從而可使在餵槽內的礦渣/熔鋼界面通過的氣泡減低或微小化。其結果發現,可抑制因氣泡在餵槽內的礦渣/熔鋼界面通過而引起的微小的礦渣系夾雜物的生成。 In order to solve the problem, the present inventors and other people conducted diligent research, and as a result, it was found that the reason why the slag in the feeding tank is mixed into the molten steel in the form of fine inclusions is that the slag flowing out of the long-necked nozzle detects The test gas is blown in and the small-diameter gas bubbles float up to the slag / steel steel interface in the feed tank. In addition, it was found that Ar gas which has been conventionally used as an obstacle to reduction of slag-based inclusions. Specifically, Ar gas is not easily dissolved in molten steel, so it floats in the form of bubbles in the molten steel in the feed tank, and when passing through the slag / fused steel interface, minute molten slag droplets are generated. In order to solve this problem, the present inventors and others conducted further research, and found that it is important to use nitrogen gas easily dissolved in molten steel instead of Ar gas in the blowing of gas for slag outflow detection. Flow of molten steel, immersion depth of long neck nozzle and The long-necked nozzle has a relationship in which the nitrogen flow rate is adjusted to a predetermined range. Thereby, during the process from the blowing of the gas until the bubbles reach the surface of the molten steel in the feeding tank, the bubbles are dissolved in the steel, so that the bubbles passing through the slag / fused steel interface in the feeding tank can be reduced or minute. Into. As a result, it was found that generation of fine slag-based inclusions caused by the passage of bubbles through the slag / steel interface in the feed tank can be suppressed.

本發明是基於所述見解而完成者,其主旨構成如下所述。 This invention is completed based on the said knowledge, The summary structure is as follows.

[1]一種鋼的連續鑄造方法,其自澆斗經由餵槽而向連續鑄造鑄模內供給熔鋼來連續鑄造,所述鋼的連續鑄造方法的特徵在於:在使長頸噴嘴的前端浸漬於表面被熔融礦渣覆蓋的餵槽內熔鋼中的狀態下,經由該長頸噴嘴而將自所述澆斗供給的熔鋼注入至所述餵槽內熔鋼中,其中所述長頸噴嘴與設置於所述澆斗的底部的噴嘴連通;此時,自在所述長頸噴嘴的側面開口的氣體流路向在所述長頸噴嘴內通過的熔鋼流供給流量Q(NL/min)的氮氣;所述流量Q滿足以下的式(1):2≦Q/W<200×H1/2×D3/2...(1) [1] A continuous casting method for steel, which comprises continuously pouring molten steel into a continuous casting mold from a hopper through a feed trough, and the continuous casting method for steel is characterized by immersing the tip of a long neck nozzle in The molten steel supplied from the hopper is injected into the molten steel in the feeding tank through the long-necked nozzle in a state of the molten steel in the feeding tank whose surface is covered with molten slag. The nozzle provided at the bottom of the hopper is communicated; at this time, nitrogen gas with a flow rate Q (NL / min) is supplied from a gas flow path opened on the side of the long neck nozzle to the molten steel stream passing through the long neck nozzle. ; The flow rate Q satisfies the following formula (1): 2 ≦ Q / W <200 × H 1/2 × D 3/2 ... (1)

此處,Q:氮氣流量(NL/min)、W:熔鋼流通量(t/min)、H:長頸噴嘴浸漬深度(m)、D:長頸噴嘴內徑(m)。 Here, Q: nitrogen flow rate (NL / min), W: molten steel flow rate (t / min), H: long neck nozzle immersion depth (m), and D: long neck nozzle inner diameter (m).

[2]如所述[1]所記載的鋼的連續鑄造方法,其中所述熔 融礦渣至少包含液相礦渣,CaO、SiO2、Al2O3及MgO這四元系中的所述熔融礦渣的組成滿足下述式(2)及式(3):{(%CaO)+(%MgO)}/(%SiO2)≧1...(2) [2] The continuous casting method for steel according to the above [1], wherein the molten slag includes at least a liquid phase slag, the molten slag in a quaternary system of CaO, SiO 2 , Al 2 O 3 and MgO The composition satisfies the following formulas (2) and (3): {(% CaO) + (% MgO)} / (% SiO 2 ) ≧ 1 ... (2)

25≦(%Al2O3)≦45...(3) 25 ≦ (% Al 2 O 3 ) ≦ 45 ... (3)

此處,(%CaO)、(%SiO2)、(%Al2O3)及(%MgO)分別為CaO、SiO2、Al2O3及MgO的質量百分率,且為以合計成為100的方式換算而得的值。 Here, (% CaO), (% SiO 2 ), (% Al 2 O 3 ), and (% MgO) are mass percentages of CaO, SiO 2 , Al 2 O 3, and MgO, respectively, and are 100 in total. The value converted by the method.

[3]如所述[1]或[2]所記載的鋼的連續鑄造方法,其中使用所述熔鋼而製造的鋼鐵製品的氮含量的目標範圍的上限值為50質量ppm以下,以成為與所述上限值相比低10質量ppm以上的氮含量的方式對所述熔鋼進行精煉,然後進行連續鑄造。 [3] The continuous casting method for steel according to the above [1] or [2], wherein the upper limit of the target range of the nitrogen content of the steel product manufactured using the molten steel is 50 mass ppm or less, The molten steel is refined so as to have a nitrogen content of 10 mass ppm or more lower than the upper limit value, and then continuously cast.

[4]如所述[1]或[2]所記載的鋼的連續鑄造方法,其中使用所述熔鋼而製造的鋼鐵製品的氮含量的目標範圍的下限值為80質量ppm以上,以成為高於所述下限值的氮含量的方式對所述熔鋼進行精煉,然後進行連續鑄造。 [4] The continuous casting method for steel according to the above [1] or [2], wherein the lower limit value of the target range of the nitrogen content of the steel product manufactured using the molten steel is 80 mass ppm or more, The molten steel is refined so as to have a nitrogen content higher than the lower limit value, and then continuously cast.

[5]如所述[1]至[4]中任一項所記載的鋼的連續鑄造方法,其中藉由對所述氮氣的流量及/或背壓的變化進行檢測來偵測澆斗礦渣朝向所述餵槽內的流出。 [5] The continuous casting method for steel according to any one of the above [1] to [4], wherein the slag in the funnel is detected by detecting a change in the flow rate and / or back pressure of the nitrogen gas. Outflow towards the feed tank.

[6]一種薄鋼板的製造方法,其特徵在於:將使用如所述[1]至[5]中任一項所記載的鋼的連續鑄造方法而製造的鋼的鑄片 熱軋後,加以冷軋而製造板厚0.2mm以下的容器用鋼板或捲壓加工用鋼板。 [6] A method for manufacturing a thin steel plate, characterized in that a slab of steel manufactured by using the continuous casting method of steel according to any one of [1] to [5] After hot rolling, cold rolling is performed to produce a steel plate for containers or a steel sheet for coiling with a thickness of 0.2 mm or less.

根據本發明的鋼的連續鑄造方法及薄鋼板的製造方法,可抑制微小的礦渣系夾雜物的生成並提高鋼的清潔度。 According to the continuous casting method of steel and the manufacturing method of a thin steel plate of the present invention, it is possible to suppress the generation of minute slag-based inclusions and improve the cleanliness of the steel.

1‧‧‧餵槽 1‧‧‧feed trough

2‧‧‧熔鋼流出孔 2‧‧‧ molten steel outflow hole

3‧‧‧熔融金屬液對接部 3‧‧‧ molten metal butt joint

4‧‧‧堤部 4‧‧‧ embankment

5‧‧‧長頸噴嘴 5‧‧‧long neck nozzle

6‧‧‧澆斗 6‧‧‧ pouring bucket

7‧‧‧澆斗上噴嘴 7‧‧‧ Nozzle on the spout

8‧‧‧澆斗滑動噴嘴 8‧‧‧Sliding Nozzle

8A、12A‧‧‧固定板 8A, 12A‧‧‧Fixing plate

8B、12B‧‧‧滑動板 8B, 12B‧‧‧Sliding plate

9‧‧‧鐵皮 9‧‧‧ iron sheet

10‧‧‧耐火物 10‧‧‧ Refractory

11‧‧‧餵槽上噴嘴 11‧‧‧ Nozzle on the feeding trough

12‧‧‧餵槽滑動噴嘴 12‧‧‧Feeding Sliding Nozzle

13‧‧‧浸漬噴嘴 13‧‧‧Immersion nozzle

14‧‧‧連續鑄造鑄模 14‧‧‧ continuous casting mold

15‧‧‧熔鋼 15‧‧‧ molten steel

16‧‧‧鑄片 16‧‧‧ Cast

17‧‧‧凝固殼 17‧‧‧ frozen shell

18‧‧‧澆斗礦渣 18‧‧‧ Spoon slag

19‧‧‧餵槽礦渣 19‧‧‧Feed trough slag

20‧‧‧氣體配管 20‧‧‧Gas piping

21‧‧‧N2用配管 21‧‧‧N 2 piping

22‧‧‧Ar用配管 22‧‧‧Ar Piping

23、24‧‧‧減壓閥 23, 24‧‧‧ pressure reducing valve

25‧‧‧調節閥 25‧‧‧ Regulating valve

26‧‧‧壓力計 26‧‧‧Pressure gauge

27‧‧‧流量計 27‧‧‧Flowmeter

28‧‧‧記錄計 28‧‧‧Record Meter

H‧‧‧長頸噴嘴浸漬深度 H‧‧‧ Long neck nozzle immersion depth

D‧‧‧長頸噴嘴內徑 D‧‧‧Inner diameter of long neck nozzle

圖1是表示通常的鋼的連續鑄造裝置的熔鋼注入部的概略剖面圖。 FIG. 1 is a schematic cross-sectional view showing a molten steel injection portion of a conventional steel continuous casting apparatus.

圖2是表示本發明的一實施形態的鋼的連續鑄造方法中所使用的連續鑄造裝置的長頸噴嘴及礦渣流出偵測裝置的概要的示意圖。 FIG. 2 is a schematic diagram showing an outline of a long-necked nozzle and a slag outflow detection device of a continuous casting apparatus used in a continuous casting method of steel according to an embodiment of the present invention.

圖3是表示在實驗例1中將熔鋼流通量W設為參數時的、氮氣流量Q與夾雜物密度指數的關係的圖表。 3 is a graph showing the relationship between the nitrogen flow rate Q and the inclusion density index when the molten steel flow rate W is set as a parameter in Experimental Example 1. FIG.

圖4是表示在實驗例1中將熔鋼流通量W設為參數時的、Q/(W×H1/2×D3/2)與夾雜物密度指數的關係的圖表。 FIG. 4 is a graph showing the relationship between Q / (W × H 1/2 × D 3/2 ) and the inclusion density index when the molten steel flow rate W is set as a parameter in Experimental Example 1. FIG.

圖5是表示在實驗例2中將長頸噴嘴內徑D設為參數時的、氮氣流量Q與夾雜物密度指數的關係的圖表。 5 is a graph showing the relationship between the nitrogen flow rate Q and the inclusion density index when the inner diameter D of the long-necked nozzle is set as a parameter in Experimental Example 2. FIG.

圖6是表示在實驗例2中將長頸噴嘴內徑D設為參數時的、Q/(W×H1/2×D3/2)與夾雜物密度指數的關係的圖表。 FIG. 6 is a graph showing the relationship between Q / (W × H 1/2 × D 3/2 ) and the inclusion density index when the inner diameter D of the long neck nozzle is set as a parameter in Experimental Example 2. FIG.

圖7是表示在實驗例3中將長頸噴嘴浸漬深度H設為參數時的、氮氣流量Q與夾雜物密度指數的關係的圖表。 7 is a graph showing a relationship between a nitrogen flow rate Q and an inclusion density index when a long-neck nozzle immersion depth H is set as a parameter in Experimental Example 3. FIG.

圖8是表示在實驗例3中將長頸噴嘴浸漬深度H設為參數時的、Q/(W×H1/2×D3/2)與夾雜物密度指數的關係的圖表。 FIG. 8 is a graph showing the relationship between Q / (W × H 1/2 × D 3/2 ) and the inclusion density index when the long-neck nozzle immersion depth H is set as a parameter in Experimental Example 3. FIG.

本發明的一實施形態的鋼的連續鑄造方法是自澆斗經由餵槽而向連續鑄造鑄模內供給熔鋼來連續鑄造,例如可使用圖1所示的具有熔鋼注入部的通常的連續鑄造裝置,進而使用圖2所示的構成作為礦渣流出偵測裝置來實施。 A continuous casting method for steel according to an embodiment of the present invention is to continuously cast molten steel into a continuous casting mold from a hopper through a feed trough. For example, a conventional continuous casting having a molten steel injection portion as shown in FIG. 1 may be used. The device was implemented using the configuration shown in FIG. 2 as a slag outflow detection device.

圖1所示的連續鑄造裝置為2股(strand)型的鋼坯(slab)連續鑄造裝置,在餵槽1的兩端部設置有朝向鑄模的熔鋼流出孔2,在餵槽1的中央部配置有來自澆斗6的熔鋼的熔融金屬液對接部3。 The continuous casting apparatus shown in FIG. 1 is a two-strand continuous slab continuous casting apparatus. The molten steel outflow holes 2 facing the mold are provided at both ends of the feed tank 1, and the central part of the feed tank 1 is provided. A molten metal abutting portion 3 of molten steel from the hopper 6 is arranged.

在圖1中,將外殼設為鐵皮9,利用耐火物10對該鐵皮9的內側施工而成的餵槽1搭載於餵槽車(未圖示)而配置於連續鑄造鑄模14的上方規定位置。另外,在餵槽1的上方規定位置配置有收容有熔鋼15的澆斗6。在澆斗6的底部設置有澆斗上噴嘴7。包含固定板8A及滑動板8B的澆斗滑動噴嘴8以熔鋼流量控制裝置的形式與該澆斗上噴嘴7的下表面相接地設置。進而,用以阻斷大氣的長頸噴嘴5連接於澆斗滑動噴嘴8的下表面。滑動板8B連接於往返型致動器(未圖示),藉由往返型致動器的動作而在與固定板8A緊密地接觸的狀態下移動。藉由該移動來調整固定板8A的開口部與滑動板8B的開口部的開口部面積,藉此控制自澆斗6向餵槽1的熔鋼注入量。再者,為了防止熔鋼在澆斗上噴 嘴7內凝固而堵塞澆斗上噴嘴7,而在澆斗的移動中,在澆斗上噴嘴7中填塞噴嘴填砂以不使熔鋼侵入。另外,形成熔鋼流出孔2的餵槽上噴嘴11與耐火物10嵌合地設置於餵槽1的底部。包含固定板12A及滑動板12B的餵槽滑動噴嘴12以熔鋼流量控制裝置的形式與該餵槽上噴嘴11的下表面相接地設置。進而,前端浸漬於連續鑄造鑄模14的內部的熔鋼15中的浸漬噴嘴13連接於餵槽滑動噴嘴12的下表面。滑動板12B連接於往返型致動器(未圖示),藉由往返型致動器的動作而在與固定板12A緊密地接觸的狀態下移動。藉由該移動來調整固定板12A的開口部與滑動板12B的開口部的開口部面積,藉此控制自餵槽1向連續鑄造鑄模14的熔鋼供給量。 In FIG. 1, the outer shell is a metal sheet 9, and a feed tank 1 constructed by the refractory 10 on the inner side of the metal sheet 9 is mounted on a tank car (not shown) and disposed at a predetermined position above the continuous casting mold 14. . Moreover, the hopper 6 which accommodates the molten steel 15 is arrange | positioned in the predetermined position above the feed tank 1. As shown in FIG. An upper nozzle 7 is provided on the bottom of the hopper 6. A hopper slide nozzle 8 including a fixed plate 8A and a slide plate 8B is grounded to the lower surface of the hopper upper nozzle 7 in the form of a molten steel flow control device. Further, a long-necked nozzle 5 for blocking the atmosphere is connected to the lower surface of the hopper slide nozzle 8. The slide plate 8B is connected to a reciprocating actuator (not shown), and moves in a state of being in close contact with the fixed plate 8A by the operation of the reciprocating actuator. By this movement, the opening area of the opening portion of the fixed plate 8A and the opening portion of the slide plate 8B is adjusted, thereby controlling the amount of molten steel injected from the hopper 6 into the feed tank 1. Furthermore, in order to prevent molten steel from being sprayed on the hopper The nozzle 7 is solidified inside the nozzle 7 to block the nozzle 7 on the hopper, and the nozzle 7 is filled with sand filling during the movement of the hopper to prevent intrusion of molten steel. In addition, a nozzle 11 on the feed trough forming the molten steel outflow hole 2 is fitted on the bottom of the feed trough 1 to fit the refractory 10. The slot-feeding sliding nozzle 12 including a fixed plate 12A and a sliding plate 12B is provided in the form of a molten steel flow control device in contact with the lower surface of the top nozzle 11 of the slot. Further, an immersion nozzle 13 whose front end is immersed in the molten steel 15 inside the continuous casting mold 14 is connected to the lower surface of the tank sliding nozzle 12. The slide plate 12B is connected to a reciprocating actuator (not shown), and moves in a state of being in close contact with the fixed plate 12A by the operation of the reciprocating actuator. The opening area of the opening of the fixed plate 12A and the opening of the sliding plate 12B is adjusted by this movement, thereby controlling the amount of molten steel supplied from the feed tank 1 to the continuous casting mold 14.

關於餵槽1的底面,位於長頸噴嘴5的正下方的熔融金屬液對接部3的部位最高,另一方面,位於熔融金屬液對接部3的兩側的熔鋼流出孔2的部位最低。熔融金屬液對接部3的底面及熔鋼流出孔2的部位的底面均為水平,自包含熔融金屬液對接部3的水平部至包含熔鋼流出孔2的部位的水平部的底面為傾斜面,在包含熔融金屬液對接部3的水平部的端部分別設置有堤部4。 Regarding the bottom surface of the feed tank 1, the position of the molten metal butt joint 3 located immediately below the long-necked nozzle 5 is the highest, and the position of the molten steel outflow hole 2 located on both sides of the molten metal butt joint 3 is the lowest. The bottom surface of the molten metal liquid butt joint 3 and the bottom surface of the portion of the molten steel outflow hole 2 are horizontal. The bottom surface of the horizontal portion from the horizontal part including the molten metal butt joint 3 to the portion including the molten steel outflow hole 2 is an inclined surface. A bank portion 4 is provided at an end portion of the horizontal portion including the molten metal liquid butt portion 3, respectively.

在使長頸噴嘴5的前端浸漬於表面被餵槽礦渣19(熔融礦渣)覆蓋的餵槽內熔鋼中的狀態下,經由長頸噴嘴5而將自澆斗6供給的熔鋼注入至餵槽內熔鋼中。進而,在使熔鋼15滯留於餵槽1中的狀態下,自餵槽1經由熔鋼流出孔2而向連續鑄造鑄 模14中供給熔鋼15。供給至連續鑄造鑄模14中的熔鋼15與連續鑄造鑄模14接觸而被冷卻,從而形成凝固殼17,將外殼設為凝固殼17且將內部設為未凝固的熔鋼15的鑄片16在連續鑄造鑄模14的下方被連續地拔出,不久直至中心部為止完全凝固而製造鑄片。自澆斗6向餵槽1的熔鋼15的注入流藉由長頸噴嘴5而與大氣阻斷。另外,自餵槽1向連續鑄造鑄模14的熔鋼15的注入流藉由浸漬噴嘴13而與大氣阻斷。另外,澆斗6內熔鋼的表面由澆斗礦渣18覆蓋,餵槽1內熔鋼的表面由餵槽礦渣19覆蓋。 The molten steel supplied from the hopper 6 is injected through the long-necked nozzle 5 into the molten steel while the tip of the long-necked nozzle 5 is immersed in the molten steel in the feeding tank whose surface is covered with the trough-slag 19 (molten slag). Inside the tank is molten steel. Further, in a state where the molten steel 15 is retained in the feed tank 1, the continuous casting is performed from the feed tank 1 through the molten steel outflow hole 2 Molten steel 15 is supplied in a mold 14. The molten steel 15 supplied to the continuous casting mold 14 contacts the continuous casting mold 14 and is cooled to form a solidified shell 17. The outer shell is a solidified shell 17 and the inner part of the molten steel 15 is an unsolidified molten steel 15. The lower part of the continuous casting mold 14 is continuously pulled out, and it is completely solidified until the center part shortly, and a slab is manufactured. The injection flow of the molten steel 15 from the hopper 6 to the feed tank 1 is blocked from the atmosphere by the long-neck nozzle 5. In addition, the injection flow of the molten steel 15 from the feed tank 1 to the continuous casting mold 14 is blocked from the atmosphere by the immersion nozzle 13. In addition, the surface of the molten steel in the hopper 6 is covered by the slag 18 of the hopper, and the surface of the molten steel in the feeding tank 1 is covered by the slag 19 of the feeding slag.

此處,在澆斗6內的熔鋼耗盡的情況下,將空的澆斗與另一收容有經加熱的熔鋼的澆斗交換而進行連續連續鑄造(以下,稱為「連連鑄」)。在澆斗6內的熔鋼耗盡時,澆斗礦渣18流入至長頸噴嘴5內,因此需要儘早偵測澆斗礦渣18來抑制澆斗礦渣18流出至餵槽1內。參照圖2來對該偵測方法進行說明。 Here, when the molten steel in the hopper 6 is depleted, the empty hopper is exchanged with another hopper containing the heated molten steel for continuous continuous casting (hereinafter referred to as "continuous continuous casting"). ). When the molten steel in the hopper 6 runs out, the slag 18 flows into the long-necked nozzle 5, so it is necessary to detect the slag 18 as early as possible to prevent the slag 18 from flowing out into the feeding tank 1. This detection method will be described with reference to FIG. 2.

氣體配管20所劃分的氣體流路在長頸噴嘴5的側面開口,經由該氣體流路而向在長頸噴嘴內通過的熔鋼流中供給惰性氣體。氣體配管20是N2用配管21與Ar用配管22合流而成。藉由對分別設置於N2用配管21、Ar用配管22的減壓閥23、減壓閥24與設置於氣體配管20的調節閥25進行控制而可控制氣體配管20內的惰性氣體的種類及流量。 The gas flow path divided by the gas piping 20 is opened on the side of the long-necked nozzle 5, and an inert gas is supplied to the molten steel flow passing through the long-necked nozzle through the gas flow path. The gas piping 20 is formed by joining the piping 21 for N 2 and the piping 22 for Ar. The types of inert gas in the gas piping 20 can be controlled by controlling the pressure reducing valve 23, the pressure reducing valve 24 provided in the N 2 piping 21, the Ar piping 22, and the regulating valve 25 provided in the gas piping 20, respectively. And traffic.

本實施形態中,在經由長頸噴嘴5而將自澆斗6供給的熔鋼注入至餵槽內熔鋼中時,自氣體配管20向在長頸噴嘴內通過的熔鋼流中供給氮氣。於在長頸噴嘴內僅熔鋼通過的階段中,對 氣體配管20內的氣體流路施加的吸引力為一定,因此設置於氣體配管20的壓力計26或流量計27所示的壓力(背壓)或流量為一定。另一方面,於在長頸噴嘴內熔鋼以外的澆斗礦渣18亦通過時,由於澆斗礦渣18與熔鋼相比為輕量,因此吸引力變小。其結果,壓力計26所示的壓力(通常相對於大氣壓而為負壓)上升,流量計27所示的流量變小。藉由利用記錄計28對此種氮氣的流量及/或背壓的變化進行檢測來偵測澆斗礦渣18朝向餵槽1內的流出。 In the present embodiment, when molten steel supplied from the hopper 6 is injected into the molten steel in the feed tank through the long-necked nozzle 5, nitrogen gas is supplied from the gas pipe 20 to the molten steel stream passing through the long-necked nozzle. In the stage where only molten steel passes through the long neck nozzle, The attractive force applied by the gas flow path in the gas piping 20 is constant. Therefore, the pressure (back pressure) or flow rate indicated by the pressure gauge 26 or the flow meter 27 provided in the gas piping 20 is constant. On the other hand, when the funnel slag 18 other than the molten steel passes through the long-necked nozzle, the funnel slag 18 is lighter in weight than the molten steel, and thus has a lower attractive force. As a result, the pressure (normally a negative pressure with respect to the atmospheric pressure) indicated by the pressure gauge 26 increases, and the flow rate indicated by the flow meter 27 decreases. By detecting the change in the flow rate and / or the back pressure of the nitrogen gas using the recorder 28, the outflow of the slag 18 into the feed tank 1 is detected.

本發明者等人使用圖1、圖2所示的2股型的鋼坯連續鑄造裝置,並將溶解於熔鋼中的氮氣用作澆斗礦渣流出偵測用的朝向長頸噴嘴的吹入氣體,並且在各種熔鋼流通量W(t/min)、長頸噴嘴浸漬深度H(m)及長頸噴嘴內徑D(m)的條件下,對氮氣流量Q(NL/min)給微小夾雜物的生成帶來的影響進行調查。以下,以實驗例1~實驗例3的形式進行說明。 The present inventors used a two-strand continuous slab casting apparatus shown in FIG. 1 and FIG. 2, and used nitrogen dissolved in molten steel as a blowing gas toward a long neck nozzle for detecting slag outflow of a hopper. , And under the conditions of various molten steel flow W (t / min), long neck nozzle immersion depth H (m) and long neck nozzle inner diameter D (m), the nitrogen flow rate Q (NL / min) will be slightly inclusions. Investigate the impact of the generation of objects. Hereinafter, description will be given in the form of Experimental Examples 1 to 3.

在各實驗例中,利用洩漏磁通式的夾雜物感測器對冷軋為板厚0.2mm以下的薄鋼板進行測定,並對粒徑約100μm以上的微小夾雜物在鋼中的個數密度進行評價。如此發現,該夾雜物的個數密度藉由將Q/(W×H1/2×D3/2)設為指標而可統一地整理各種條件下的調查結果。 In each experimental example, an inclusion sensor with a leakage magnetic general formula was used to measure a thin steel sheet that was cold rolled to a thickness of 0.2 mm or less, and the number density of micro inclusions with a particle size of about 100 μm or more in the steel was measured. Evaluate. Thus, it was found that the number density of the inclusions can be used to uniformly sort the results of investigations under various conditions by using Q / (W × H 1/2 × D 3/2 ) as an index.

針對所述夾雜物的個數密度,將Ar氣體用作為朝向長頸噴嘴的吹入氣體,並將熔鋼流通量W設為7.0(t/min)、將長頸噴嘴浸漬深度H設為0.5(m)、將長頸噴嘴內徑D設為0.175(m)、將穩定澆鑄時的Ar氣體流量QAr設為20(NL/min),以將此時的 值設為基準(即1)的指數(夾雜物密度指數)在各種條件下進行評價。 Regarding the number density of the inclusions, Ar gas was used as the blowing gas toward the long neck nozzle, and the molten steel flow rate W was set to 7.0 (t / min), and the long neck nozzle immersion depth H was set to 0.5. (m), the inner diameter D of the long neck nozzle is set to 0.175 (m), the Ar gas flow rate Q Ar at the time of stable casting is set to 20 (NL / min), and the value at this time is used as a reference (ie, 1) The index (inclusion density index) was evaluated under various conditions.

(實驗例1) (Experimental example 1)

首先,將W(t/min)設為參數而變更為5、7、9,在以H為0.4m、以D為0.175m的一定的條件下,對在15~100的範圍內變更Q(NL/min)時的夾雜物密度指數的變化進行調查,將結果示於圖3中。在任一熔鋼流通量W下,均成為隨著氮氣流量Q增大而夾雜物密度指數增大的傾向,另外,在W相對小的情況下,該傾向變得顯著。 First, set W (t / min) as a parameter and change it to 5, 7, or 9. Under a certain condition with 0.4 m for H and 0.175 m for D, change Q (within 15 to 100). The change in the density index of inclusions at NL / min) was investigated, and the results are shown in FIG. 3. At any molten steel flow rate W, there is a tendency that the inclusion density index increases as the nitrogen flow rate Q increases, and this tendency becomes significant when W is relatively small.

因此,將圖表的橫軸變更為與Q一起亦使用W的指標,對W的影響進行各種評價,結果如圖4所示,可知,藉由將Q/(W×H1/2×D3/2)設為指標而可統一地整理各種條件下的調查結果。 Therefore, the horizontal axis of the graph was changed to an index that uses W together with Q, and various influences on W were evaluated. The results are shown in FIG. 4. It can be seen that Q / (W × H 1/2 × D 3 / 2 ) It can be used as an index to uniformly organize the survey results under various conditions.

(實驗例2) (Experimental example 2)

繼而,將長頸噴嘴內徑D(m)設為參數而變更為0.115、0.145、0.175,在以H為0.4m、以W為7t/min的一定的條件下,對在15~80的範圍內變更Q(NL/min)時的夾雜物密度指數的變化進行調查,將結果示於圖5中。在任一長頸噴嘴內徑D下,均成為隨著氮氣流量Q增大而夾雜物密度指數增大的傾向,另外,在D相對小的情況下,該傾向變得顯著。 Next, the long-necked nozzle inner diameter D (m) was set as a parameter and changed to 0.115, 0.145, and 0.175. Under the constant conditions of 0.4 m for H and 7 t / min for W, the range was from 15 to 80. The change in the inclusion density index when Q (NL / min) was changed internally was investigated, and the results are shown in FIG. 5. In any long-neck nozzle inner diameter D, the tendency of the inclusion density index to increase as the nitrogen flow rate Q increases, and this tendency becomes significant when D is relatively small.

因此,將圖表的橫軸變更為與Q一起亦使用D的指標,對D的影響進行各種評價,結果如圖6所示,可知,藉由將Q/(W×H1/2×D3/2)設為指標而可統一地整理各種條件下的調查結果。 Therefore, the horizontal axis of the graph was changed to use the index of D together with Q, and various effects of D were evaluated. The results are shown in FIG. 6. It can be seen that Q / (W × H 1/2 × D 3 / 2 ) It can be used as an index to uniformly organize the survey results under various conditions.

(實驗例3) (Experimental example 3)

繼而,將長頸噴嘴浸漬深度H(m)設為參數而變更為0.2、0.3、0.4、0.5,在以D為0.175m、以W為7t/min的一定的條件下,對在15~80的範圍內變更Q(NL/min)時的夾雜物密度指數的變化進行調查,將結果示於圖7中。在任一長頸噴嘴浸漬深度H下,均成為隨著氮氣流量Q增大而夾雜物密度指數增大的傾向,另外,在H相對小的情況下,該傾向變得顯著。 Next, the long-neck nozzle immersion depth H (m) was set as a parameter and changed to 0.2, 0.3, 0.4, and 0.5. Under certain conditions with D of 0.175 m and W of 7 t / min, the range was 15 to 80. The change of the inclusion density index when Q (NL / min) was changed within the range was investigated, and the results are shown in FIG. 7. At any long-neck nozzle immersion depth H, there is a tendency that the inclusion density index increases as the nitrogen flow rate Q increases, and this tendency becomes significant when H is relatively small.

因此,將圖表的橫軸變更為與Q一起亦使用H的指標,對H的影響進行各種評價,結果如圖8所示,可知,藉由將Q/(W×H1/2×D3/2)設為指標而可統一地整理各種條件下的調查結果。 Therefore, the horizontal axis of the graph was changed to use the index of H together with Q, and various influences on H were evaluated. The results are shown in FIG. 8. It can be seen that Q / (W × H 1/2 × D 3 / 2 ) It can be used as an index to uniformly organize the survey results under various conditions.

如上所述,可知,在將氮氣用作為澆斗礦渣流出偵測用的朝向長頸噴嘴的吹入氣體的情況下,在氮氣流量Q(NL/min)、熔鋼流通量W(t/min)、長頸噴嘴浸漬深度H(m)及長頸噴嘴內徑D(m)的各種工作條件下,藉由將Q/(W×H1/2×D3/2)設為指標而可統一地整理夾雜物密度指數。而且,確認到:藉由將指標值Q/(W×H1/2×D3/2)設為未滿200、更理想為未滿150,與將Ar氣體用作朝向長頸噴嘴的吹入氣體的現有技術相比,可大幅減低夾雜物的個數密度。 As described above, it can be seen that when nitrogen gas is used as the blowing gas toward the long-necked nozzle for detecting the slag outflow of the hopper, the nitrogen flow rate Q (NL / min) and the molten steel flow rate W (t / min ), Long neck nozzle immersion depth H (m) and long neck nozzle inner diameter D (m) under various operating conditions, Q / (W × H 1/2 × D 3/2 ) can be set as an index to Unified inclusion density index. In addition, it was confirmed that by setting the index value Q / (W × H 1/2 × D 3/2 ) to less than 200, more preferably to less than 150, and using Ar gas as a blowing agent toward the long-necked nozzle Compared with the prior art of injecting gas, the number density of inclusions can be greatly reduced.

其中,若相對於熔鋼流通量W而過度減小氮氣流量Q,則存在如下情況:在穩定注入時,礦渣流出偵測用氣體的吹入壓力(負壓)亦擺動而不穩定,從而難以判定伴隨礦渣流出的吹入壓力的上升。因此,為了使氮氣的吹入壓力穩定而可在短時間內 精度良好地判定礦渣流出,較佳為將Q/W設為2以上、更理想為3以上。 Among them, if the nitrogen flow rate Q is excessively reduced with respect to the molten steel flow W, there are cases in which, during stable injection, the blowing pressure (negative pressure) of the slag outflow detection gas also fluctuates and becomes unstable, making it difficult. It was determined that the blowing pressure accompanying the slag outflow increased. Therefore, in order to stabilize the blowing pressure of nitrogen, To determine the slag outflow with good accuracy, Q / W is preferably set to 2 or more, and more preferably 3 or more.

即,藉由將Q/W設為滿足下述式(1)的範圍,在將氮氣用作礦渣流出偵測用氣體的情況下,可在短時間內精度良好地判定礦渣流出,且可抑制因餵槽礦渣而引起的微小夾雜物的生成。 That is, by setting Q / W to a range satisfying the following formula (1), when nitrogen is used as the slag outflow detection gas, the slag outflow can be accurately determined in a short time, and the slag outflow can be suppressed. Formation of fine inclusions caused by slag feeding.

2≦Q/W<200×H1/2×D3/2...(1) 2 ≦ Q / W <200 × H 1/2 × D 3/2 ... (1)

Q:氮氣流量(NL/min) Q: nitrogen flow (NL / min)

W:熔鋼流通量(t/min) W: molten steel flow (t / min)

H:長頸噴嘴浸漬深度(m) H: long neck nozzle immersion depth (m)

D:長頸噴嘴內徑(m) D: Inner diameter of long neck nozzle (m)

關於所述式(1)的條件式,實驗性確認到:可應用於W為4t/min~12t/min、H為0.2m~0.8m、D為0.1m~0.25m的範圍廣的條件中,並且可判定礦渣流出且對於微小夾雜物的抑制而言有效。 Regarding the conditional expression of the formula (1), it has been experimentally confirmed that it can be applied to a wide range of conditions where W is 4t / min to 12t / min, H is 0.2m to 0.8m, and D is 0.1m to 0.25m. And, it can be judged that slag outflow is effective for the suppression of small inclusions.

再者,在所述調查中,作為為了將餵槽內的熔鋼與大氣阻斷而添加至餵槽內的餵槽助熔劑,使用表1所示的組成者,在開放澆斗上噴嘴時,根據流入至餵槽內的噴嘴填砂的量及熔鋼朝向餵槽的流入量來添加。 In addition, in the above-mentioned investigation, as the feed flux for the tank to be added to block the molten steel in the feed tank from the atmosphere, a composition shown in Table 1 was used. It is added according to the amount of sand filling in the nozzle flowing into the feeding tank and the inflow amount of molten steel toward the feeding tank.

[表1] [Table 1]

餵槽礦渣是將如下成分組合而合成:所添加的餵槽助熔劑、SiO2為主要成分的噴嘴填砂、Al2O3為主要成分且自鋼中上浮的脫氧產物、CaO及Al2O3為主要成分且含有SiO2、MgO、FeO等的澆斗礦渣的流入成分以及通常對高氧化鋁質耐火物實施MgO塗佈的餵槽的內襯耐火物的溶解成分等。因此,藉由各自的混合比例的變化或礦渣與熔鋼的反應,餵槽礦渣的組成發生變化。該些的結果,餵槽礦渣的組成在CaO、SiO2、Al2O3及MgO這四元系中,以{(%CaO)+(%MgO)}/(%SiO2)≧1且25≦(%Al2O3)≦45的範圍在連續鑄造中推移。此處,(%CaO)、(%SiO2)、(%Al2O3)及(%MgO)分別為CaO、SiO2、Al2O3及MgO的質量百分率,且為以該些的合計成為100的方式換算而得的值。將餵槽礦渣的組成的例子示於表2中。 Slot-feeding slag is synthesized by combining the following components: added slot-feeding flux, nozzle sand filling with SiO 2 as the main component, deoxidation products with Al 2 O 3 as the main component and floating from steel, CaO and Al 2 O 3 is a main component and contains inflow components of the funnel slag including SiO 2 , MgO, FeO, etc., and dissolved components of the refractory lining of a feed tank in which a high alumina refractory is generally coated with MgO. Therefore, the composition of the feed slag is changed by the change of the respective mixing ratio or the reaction of the slag and the molten steel. As a result of these results, in the quaternary system of CaO, SiO 2 , Al 2 O 3 and MgO, the composition of the trough slag was {(% CaO) + (% MgO)} / (% SiO 2 ) ≧ 1 and 25 The range of ≦ (% Al 2 O 3 ) ≦ 45 changes during continuous casting. Here, (% CaO), (% SiO 2 ), (% Al 2 O 3 ), and (% MgO) are the mass percentages of CaO, SiO 2 , Al 2 O 3, and MgO, respectively, and are the totals of these. It is a value converted to 100. Table 2 shows examples of the composition of the trough slag.

所述組成範圍的礦渣中,在餵槽內的熔鋼溫度下,產生 大量的低黏度的液相,可高效地吸收自熔鋼上浮的Al2O3系夾雜物,並且熔鋼中的Al被礦渣氧化而可抑制Al2O3系夾雜物增加。 In the slag in the composition range, a large amount of a low-viscosity liquid phase is generated at the molten steel temperature in the feeding tank, and the Al 2 O 3 series inclusions floating from the molten steel can be efficiently absorbed, and the Al in the molten steel can be absorbed. Oxidation by slag can suppress the increase of Al 2 O 3 based inclusions.

此時,作為本發明的對象的鋼主要為鋼中Al含量為0.005質量%~0.06質量%的Al脫氧鋼,但未必限定於此。在理想為特別減低餵槽礦渣系的夾雜物的情況下,可不限於所述Al脫氧鋼地應用本發明。 At this time, the steel to be the subject of the present invention is mainly an Al deoxidized steel having an Al content in the steel of 0.005 mass% to 0.06 mass%, but it is not necessarily limited to this. In the case where it is desirable to particularly reduce the inclusions of the slag-based slag system, the present invention is not limited to the Al deoxidized steel.

如上所述般的流動性高的礦渣中,因由自熔鋼中上浮的氣泡所引起的攪拌而容易產生微小的礦渣系夾雜物,因此對於朝向長頸噴嘴的吹入氣體而言,需要代替Ar氣體而使用易溶解於熔鋼中的氮氣,並且限制為與工作條件對應的適當的氮氣吹入速度。 As mentioned above, slag with high fluidity is liable to generate minute slag-based inclusions due to agitation caused by air bubbles floating in the self-melting steel. Therefore, it is necessary to replace Ar for the gas blowing toward the long-neck nozzle. As the gas, nitrogen that is easily soluble in molten steel is used, and the nitrogen blowing rate is limited to an appropriate nitrogen blowing rate according to the operating conditions.

其中,在代替Ar氣體而將氮氣用作礦渣流出偵測用氣體的情況下,無法避免鋼中氮濃度的上升。因此,在精煉階段中,需要事先使氮濃度充分降低,理想為以成為與使用熔鋼而製造的鋼鐵製品的氮含量的目標範圍的上限值相比低10質量ppm以上的氮含量的方式對該熔鋼進行精煉。因此,在該上限值為50質量ppm以下的情況下,在轉爐等的精煉步驟中,需要注意使供於連續鑄造中的熔鋼的氮含量充分降低來決定所使用的副原料或各種製程氣體種類、合金添加方法等。 Among them, when nitrogen gas is used instead of Ar gas as a gas for detecting slag outflow, an increase in nitrogen concentration in steel cannot be avoided. Therefore, in the refining stage, it is necessary to sufficiently reduce the nitrogen concentration in advance, and it is desirable that the nitrogen content is 10 mass ppm or more lower than the upper limit of the target range of the nitrogen content of the steel product manufactured by using molten steel. This molten steel is refined. Therefore, when the upper limit value is 50 mass ppm or less, in the refining step such as a converter, care must be taken to sufficiently reduce the nitrogen content of the molten steel used in continuous casting to determine the auxiliary raw materials or various processes to be used. Gas type, alloy addition method, etc.

另外,在目標氮含量例如高至80質量ppm以上的鋼種的連續鑄造中,先前使用向長頸噴嘴中吹入大量的氮氣來加氮的方法。但是,本發明的方法中,未必能夠增大吹入長頸噴嘴中的氮氣流量,而未必能夠確保充分的加氮量。因此,在目標氮含量 的下限值為80質量ppm以上的鋼種的連續鑄造中,亦需要在精煉階段中以成為高於該下限值的氮含量的方式決定精煉方法、副原料、添加合金等。 Further, in the continuous casting of a steel type having a target nitrogen content of, for example, as high as 80 mass ppm or more, a method of adding nitrogen by blowing a large amount of nitrogen into a long-necked nozzle has previously been used. However, in the method of the present invention, the flow rate of nitrogen gas to be blown into the long-necked nozzle may not necessarily be increased, and a sufficient amount of nitrogen may not be ensured. Therefore, the target nitrogen content In continuous casting of a steel type having a lower limit value of 80 mass ppm or more, it is also necessary to determine a refining method, an auxiliary material, an added alloy, and the like in the refining stage so that the nitrogen content is higher than the lower limit value.

關於將以所述方式連續鑄造的鑄片熱軋後,冷軋為板厚0.2mm以下而製造的容器用鋼板或捲壓加工用鋼板,與將Ar氣體用作礦渣流出偵測用氣體的先前的方法相比,因礦渣系的微小夾雜物減低而由壓製加工後的線狀瑕疵所引起的不良率大幅減低至1/2以下。 The hot-rolled slabs continuously cast in the above-mentioned manner are cold-rolled to a steel sheet for containers or rolled steel sheets having a thickness of 0.2 mm or less, as compared to the conventional method using Ar gas as a slag outflow detection gas. Compared with the method, the defect rate caused by the linear defects after the pressing process is greatly reduced to 1/2 or less because the slag-based fine inclusions are reduced.

[實施例] [Example]

藉由使用圖1、圖2所示的2股型的鋼坯連續鑄造裝置來連續鑄造面向容器的素材的低碳鋁脫氧鋼,而實施對本發明例與比較例進行比較的實驗。 Experiments comparing the examples of the present invention with the comparative examples were carried out by continuously casting a low-carbon aluminum deoxidized steel of a container-facing material using a two-strand continuous slab continuous casting apparatus shown in FIGS. 1 and 2.

利用容量300噸的轉爐對在鐵水預備處理中實施了脫磷處理的鐵水進行脫碳,將所獲得的熔鋼在未脫氧狀態下受鋼至澆斗。其後,將鋁灰添加至澆斗內的礦渣上而使礦渣還原改質,然後,利用RH脫氣裝置添加鋁來對熔鋼進行脫氧,從而進行二次精煉。經過二次精煉而獲得表3所示的成分的熔鋼後,利用2股的垂直彎曲鋼坯連續鑄造機來製造作為熱軋用的素材的厚度260mm的鋼坯鑄片。如圖1所示,自澆斗6的底部的澆斗上噴嘴7經由長頸噴嘴5而向容量50噸的餵槽1中注入熔鋼。進而,自餵槽1的底部的餵槽上噴嘴11經由浸漬噴嘴13而注入至連續鑄造鑄模14中,拔出鑄片16,並在表4所示的各條件下實施連續鑄造。 以將連續鑄造鑄模內的熔鋼位準保持為一定的方式自動控制餵槽滑動噴嘴12的開度,並且在穩定澆鑄時,以將餵槽內的熔鋼量保持為一定的方式自動控制澆斗滑動噴嘴8的開度。來自澆斗的熔鋼流通量W是藉由在單位時間的期間所拔出的鑄片的質量與餵槽內熔鋼質量的增加量的和來算出。 A 300-ton converter was used to decarburize the molten iron subjected to dephosphorization treatment in the molten iron preliminary treatment, and the obtained molten steel was subjected to steel to a hopper in a non-deoxidized state. After that, aluminum ash was added to the slag in the hopper to reduce and modify the slag, and then, aluminum was added using a RH degassing device to deoxidize the molten steel to perform secondary refining. After secondary refining to obtain molten steel having the composition shown in Table 3, a 260-mm-thick slab cast slab was produced using a two-strand vertical bending slab continuous casting machine as a material for hot rolling. As shown in FIG. 1, molten steel is injected into a feeding tank 1 having a capacity of 50 tons from a nozzle 7 on the bottom of the hopper 6 through a long neck nozzle 5. Furthermore, the upper-feeding-chamber nozzle 11 from the bottom of the feeding tank 1 was injected into the continuous casting mold 14 through the immersion nozzle 13, the slab 16 was pulled out, and continuous casting was performed under each condition shown in Table 4. Automatically control the opening degree of the sliding nozzle 12 of the feeding tank in such a way that the level of molten steel in the continuous casting mold is kept constant, and automatically control the pouring in such a way that the amount of molten steel in the feeding tank is kept constant during stable casting The opening degree of the bucket sliding nozzle 8. The molten steel flow rate W from the hopper is calculated by the sum of the mass of the slab pulled out during the unit time and the amount of increase in the molten steel mass in the feed tank.

在來自澆斗的熔鋼注入中,使用圖2中示意性示出概要的裝置,自設置於長頸噴嘴5的上部的氣體吹入孔吹入礦渣流出偵測用的氣體。此時,基於測定氣體的吹入壓力及氣體的吹入速 度而得的結果,判定來自澆斗的熔鋼注入末期的澆斗礦渣流出,從而結束來自澆斗的熔鋼的注入,並進行澆斗交換。將氮氣或氬氣用作礦渣流出偵測用的氣體,利用減壓閥23或減壓閥24調整為規定的供給壓後,在穩定澆鑄時,將調整為規定的吹入速度Q(NL/min)的調節閥25的開度保持為一定,利用設置於調節閥25的下游側(長頸噴嘴的吹入孔側)的壓力計26及流量計27來測定氣體的吹入壓力及吹入速度。若在來自澆斗的熔鋼注入的末期,澆斗礦渣混入至注入流,則由長頸噴嘴內的下落流所引起的吸引力減小,氣體的吹入壓力上升,並且氣體的吹入速度降低。因此,對該些吹入壓力及吹入速度的至少任一者進行偵測而結束澆斗的熔鋼注入,並交換澆斗來繼續進行連連鑄。 In the molten steel injection from a hopper, a device schematically shown in FIG. 2 is used, and a gas for detecting slag outflow is blown from a gas blowing hole provided in an upper portion of the long neck nozzle 5. At this time, based on the measurement gas injection pressure and gas injection speed As a result, it is determined that the slag flowing out of the slag at the end of the molten steel injection from the hopper ends, thereby ending the injection of the molten steel from the hopper and performing hopper exchange. Nitrogen or argon is used as a gas for detecting slag outflow, and after adjusting to a predetermined supply pressure using a pressure reducing valve 23 or a pressure reducing valve 24, it is adjusted to a predetermined blowing rate Q (NL / The opening degree of the control valve 25 is kept constant, and the pressure and pressure of the gas are measured using a pressure gauge 26 and a flow meter 27 provided downstream of the control valve 25 (side of the long-neck nozzle). speed. If at the end of the molten steel injection from the hopper, the slag in the hopper is mixed into the injection flow, the attractive force caused by the falling flow in the long neck nozzle is reduced, the gas injection pressure is increased, and the gas injection speed is increased. reduce. Therefore, at least one of these blowing pressures and blowing speeds is detected, the molten steel injection of the hopper is ended, and the hopper is exchanged to continue the continuous casting.

在任一試驗條件下,餵槽助熔劑使用表1所示的組成者,且根據噴嘴填砂及熔鋼朝向餵槽的流入量來添加,其結果,餵槽礦渣的組成在CaO、SiO2、Al2O3及MgO這四元系中,以{(%CaO)+(%MgO)}/(%SiO2)≧1且25≦(%Al2O3)≦45的範圍在連續鑄造中推移,從而實現上浮至熔鋼/礦渣界面附近的夾雜物的吸收促進。關於餵槽礦渣的組成,在來自澆斗的熔鋼注入量成為澆斗內的初始的熔鋼量的10%、50%及90%的各時間點,自餵槽採取試樣,並藉由螢光X射線分析裝置來分析而求出。 Under any test conditions, the composition of the tank feeding flux is shown in Table 1, and is added according to the nozzle sand filling and the inflow of molten steel toward the feeding tank. As a result, the composition of the tank slag is CaO, SiO 2 , In the quaternary system of Al 2 O 3 and MgO, continuous casting is performed in a range of ((% CaO) + (% MgO)) / (% SiO 2 ) ≧ 1 and 25 ≦ (% Al 2 O 3 ) ≦ 45. This promotes the absorption of inclusions that float up to the vicinity of the molten steel / slag interface. Regarding the composition of the slag in the feed tank, samples were taken from the feed tank at various time points when the molten steel injection amount from the hopper became 10%, 50%, and 90% of the initial molten steel amount in the hopper. It is obtained by analysis by a fluorescent X-ray analyzer.

針對目標氮濃度(鋼製品的氮含量的目標範圍)低的鋼種A及目標氮濃度高的鋼種B,如表4般變更連續鑄造時的礦渣流出偵測用氣體的氣體種類及氣體吹入速度Q(NL/min)、長頸噴 嘴的內徑D(m)及浸漬深度H(m)、來自澆斗的熔鋼流通量W(t/min)各條件,並實施各發明例及各比較例。 For the steel type A with a low target nitrogen concentration (target range of nitrogen content of steel products) and the steel type B with a high target nitrogen concentration, change the gas type and gas blowing speed of the slag outflow detection gas during continuous casting as shown in Table 4. Q (NL / min), long neck spray Each condition of the inside diameter D (m) and the immersion depth H (m) of the nozzle, and the molten steel flow rate W (t / min) from the hopper, was implemented for each invention example and each comparative example.

在目標氮濃度低的鋼種A中,將氮氣用作礦渣流出偵測用氣體的發明例1及比較例2中,為了減低熔鋼的氮含量,在轉爐精煉時,不使用通常添加的焦炭作為熱源,作為熱源,使用相對昂貴的土壤石墨或矽鐵合金。在目標氮濃度高的鋼種B中,實施了本發明的發明例2中,為了事先充分提高2次精煉階段中的熔鋼的氮含量,而在RH處理後,添加氮化錳,並且吹入氮氣,攪拌熔鋼來進行成分調整。 In Steel Type A with a low target nitrogen concentration, Inventive Example 1 and Comparative Example 2 in which nitrogen was used as a slag outflow detection gas, in order to reduce the nitrogen content of the molten steel, the coke that is usually added is not used as The heat source, as the heat source, uses relatively expensive soil graphite or ferrosilicon. In the steel type B with a high target nitrogen concentration, invented Example 2 of the present invention, in order to sufficiently increase the nitrogen content of the molten steel in the two refining stages in advance, after the RH treatment, manganese nitride was added and blown in Nitrogen, stirring the molten steel to adjust the composition.

利用連續鑄造機而製成作為熱軋用的鋼素材的鋼坯後,對該些鋼坯在熱精加工溫度:890℃、捲取溫度:650℃下進行熱軋,加以酸洗後,以軋製率92%實施冷軋,從而製成板厚0.14mm。繼而,利用連續退火爐升溫至退火溫度760℃後,實施以平均冷卻速度5℃/s冷卻至500℃的連續退火。其後,以軋製率1.5%實施回火軋製後,將藉此所獲得的鋼板通板至具有可檢測至夾雜物直徑100μm的洩漏磁通式的夾雜物感測器的製造生產線,藉此進行夾雜物指數(單位質量的鋼中的直徑100μm以上的夾雜物的個數密度除以將氬氣用作礦渣流出偵測用氣體的比較例1時的值並指數化而得的值)的評價。 After continuous casting machine is used to produce slabs as steel materials for hot rolling, these slabs are hot rolled at hot finishing temperature: 890 ° C and coiling temperature: 650 ° C, pickled and rolled. The cold rolling was performed at a rate of 92% to obtain a plate thickness of 0.14 mm. Then, the temperature was increased to 760 ° C in a continuous annealing furnace, and then continuous annealing was performed to cool to 500 ° C at an average cooling rate of 5 ° C / s. Thereafter, after temper rolling at a rolling rate of 1.5%, the steel sheet thus obtained was passed through to a manufacturing production line for an inclusion sensor having a leakage magnetic general formula capable of detecting inclusion diameters of 100 μm. The index of inclusions is obtained by dividing the number density of inclusions with a diameter of 100 μm or more in steel per unit mass by the value obtained by dividing and indexing the value of Comparative Example 1 using argon as a gas for detecting slag outflow. evaluation of.

將氮氣用作礦渣流出偵測用氣體並設為滿足Q/(W×H1/2×D3/2)<200的條件的發明例1、發明例2中,夾雜物指數大幅減低,將所獲得的鋼板製品壓製加工成食罐用容器而得的 製品的由線狀瑕疵所引起的不良率大幅減低至1/2。 Inventive Example 1 and Inventive Example 2 using nitrogen as a gas for detecting slag outflow and satisfying the condition of Q / (W × H 1/2 × D 3/2 ) <200, the inclusion index was significantly reduced, and The defect rate due to linear defects of the obtained steel plate product obtained by press-processing into a container for food cans was significantly reduced to 1/2.

即便將氮氣用作礦渣流出偵測用氣體亦不滿足Q/(W×H1/2×D3/2)<200的條件的比較例2、比較例3中,未確認到夾雜物指數的減少,壓製加工後的製品的由線狀瑕疵所引起的不良率亦與使用氬氣的比較例1為相同程度。 In Comparative Example 2 and Comparative Example 3, which did not satisfy the condition of Q / (W × H 1/2 × D 3/2 ) <200 even when nitrogen was used as the slag outflow detection gas, no decrease in the inclusion index was confirmed. The defective rate due to linear defects of the product after pressing is also about the same as that of Comparative Example 1 using argon.

在任一試驗條件下,來自澆斗的熔鋼注入末期中的礦渣流出偵測用氣體的吹入壓的變化的偵測狀況均良好,且澆斗礦渣的流出偵測亦無問題。 Under any of the test conditions, the detection condition of the change in the blowing pressure of the slag outflow detection gas in the late stage of molten steel injection from the hopper was good, and the slag outflow detection was no problem.

[產業上的可利用性] [Industrial availability]

根據本發明的鋼的連續鑄造方法及薄鋼板的製造方法,可抑制微小的礦渣系夾雜物的生成並提高鋼的清潔度。 According to the continuous casting method of steel and the manufacturing method of a thin steel plate of the present invention, it is possible to suppress the generation of minute slag-based inclusions and improve the cleanliness of the steel.

Claims (6)

一種鋼的連續鑄造方法,其自澆斗經由餵槽而向連續鑄造鑄模內供給熔鋼來連續鑄造,所述鋼的連續鑄造方法的特徵在於:在使長頸噴嘴的前端浸漬於表面被熔融礦渣覆蓋的餵槽內熔鋼中的狀態下,經由所述長頸噴嘴而將自所述澆斗供給的熔鋼注入至所述餵槽內熔鋼中,其中所述長頸噴嘴與設置於所述澆斗的底部的噴嘴連通;此時,自在所述長頸噴嘴的側面開口的氣體流路向在所述長頸噴嘴內通過的熔鋼流供給流量Q(NL/min)的氮氣;所述流量Q滿足以下的式(1):2≦Q/W<200×H1/2×D3/2...(1)此處,Q:氮氣流量(NL/min)、W:熔鋼流通量(t/min)、H:長頸噴嘴浸漬深度(m)、D:長頸噴嘴內徑(m)。A continuous casting method of steel that supplies molten steel into a continuous casting mold through a feed trough to continuously cast. The continuous casting method of the steel is characterized in that the tip of a long neck nozzle is immersed in the surface and melted In the state of molten steel in the feed tank covered by slag, the molten steel supplied from the ladle is injected into the molten steel in the feed tank via the long-necked nozzle, wherein the long-necked nozzle is provided with The nozzle at the bottom of the ladle is in communication; at this time, the gas flow path opened at the side of the long-necked nozzle supplies a flow rate Q (NL / min) of nitrogen to the molten steel flow passing through the long-necked nozzle; The flow rate Q satisfies the following formula (1): 2 ≦ Q / W <200 × H 1/2 × D 3/2 ... (1) Here, Q: nitrogen flow rate (NL / min), W: melting Steel flux (t / min), H: Long-neck nozzle immersion depth (m), D: Long-neck nozzle inner diameter (m). 如申請專利範圍第1項所述的鋼的連續鑄造方法,其中所述熔融礦渣至少包含液相礦渣,CaO、SiO2、Al2O3及MgO這四元系中的所述熔融礦渣的組成滿足下述式(2)及式(3):{(%CaO)+(%MgO)}/(%SiO2)≧1...(2) 25≦(%Al2O3)≦45...(3)此處,(%CaO)、(%SiO2)、(%Al2O3)及(%MgO)分別為CaO、SiO2、Al2O3及MgO的質量百分率,且為以合計成為100的方式換算而得的值。The continuous casting method of steel according to item 1 of the patent application scope, wherein the molten slag contains at least a liquid phase slag, the composition of the molten slag in the quaternary system CaO, SiO 2 , Al 2 O 3 and MgO Satisfy the following formula (2) and formula (3): {(% CaO) + (% MgO)} / (% SiO 2 ) ≧ 1 ... (2) 25 ≦ (% Al 2 O 3 ) ≦ 45. .. (3) Here, (% CaO), (% SiO 2 ), (% Al 2 O 3 ) and (% MgO) are the mass percentages of CaO, SiO 2 , Al 2 O 3 and MgO, respectively, and are A value converted so that the total becomes 100. 如申請專利範圍第1項或第2項所述的鋼的連續鑄造方法,其中使用所述熔鋼而製造的鋼鐵製品的氮含量的目標範圍的上限值為50質量ppm以下,以成為與所述上限值相比低10質量ppm以上的氮含量的方式對所述熔鋼進行精煉,然後進行連續鑄造。The continuous casting method of steel according to item 1 or 2 of the patent application range, wherein the upper limit value of the target range of nitrogen content of the steel products manufactured using the molten steel is 50 mass ppm or less, so as The molten steel is refined in such a manner that the upper limit value is lower than the nitrogen content of 10 mass ppm or more, and then continuous casting is performed. 如申請專利範圍第1項或第2項所述的鋼的連續鑄造方法,其中使用所述熔鋼而製造的鋼鐵製品的氮含量的目標範圍的下限值為80質量ppm以上,以成為高於所述下限值的氮含量的方式對所述熔鋼進行精煉,然後進行連續鑄造。The continuous casting method of steel according to item 1 or item 2 of the patent application range, wherein the lower limit of the target range of the nitrogen content of the steel products manufactured using the molten steel is 80 mass ppm or more to become high The molten steel is refined at the lower limit of the nitrogen content, and then continuous casting is performed. 如申請專利範圍第1項或第2項所述的鋼的連續鑄造方法,其中藉由對所述氮氣的流量及/或背壓的變化進行檢測來偵測澆斗礦渣朝向所述餵槽內的流出。The continuous casting method of steel according to item 1 or item 2 of the patent application scope, wherein the detection of the change in the flow rate and / or back pressure of the nitrogen gas is used to detect the pouring slag toward the feeding tank Outflow. 一種薄鋼板的製造方法,其特徵在於:將使用如申請專利範圍第1項至第5項中任一項所述的鋼的連續鑄造方法而製造的鋼的鑄片熱軋後,加以冷軋而製造板厚0.2mm以下的容器用鋼板或捲壓加工用鋼板。A method of manufacturing a thin steel plate, characterized by hot rolling a steel slab manufactured by using the continuous casting method of steel according to any one of the patent application items 1 to 5, followed by cold rolling In addition, a steel plate for a container or a steel plate for crimping with a thickness of 0.2 mm or less is manufactured.
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