KR970005199B1 - The making method of low carbon and low nitrogen molten metal - Google Patents

The making method of low carbon and low nitrogen molten metal Download PDF

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KR970005199B1
KR970005199B1 KR1019940038971A KR19940038971A KR970005199B1 KR 970005199 B1 KR970005199 B1 KR 970005199B1 KR 1019940038971 A KR1019940038971 A KR 1019940038971A KR 19940038971 A KR19940038971 A KR 19940038971A KR 970005199 B1 KR970005199 B1 KR 970005199B1
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molten steel
nitrogen
steel
ladle
aluminum
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KR1019940038971A
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KR960023112A (en
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안상복
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김만제
포항종합제철주식회사
신창식
재단법인산업과학기술연구소
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    • 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
    • C21C7/0006—Adding metallic additives
    • 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
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C21C5/34—Blowing through the bath
    • 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
    • C21C7/0025—Adding carbon material
    • 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
    • C21C7/06—Deoxidising, e.g. killing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0003—Monitoring the temperature or a characteristic of the charge and using it as a controlling value
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0028—Regulation
    • F27D2019/0068—Regulation involving a measured inflow of a particular gas in the enclosure

Abstract

The process comprises composition in which the final steel components contain 0.05-0.08 wt.% carbon, 0.3-0.5 wt.% manganese, 0.007-0.013 wt.% nitrogen, 0.02-0.06 wt.% aluminum. The process includes the following steps of; adding nitrogen component by blowing a nitrogen gas with 5.6-8.5 Nm3/min against a molten steel of 250 ton by means of bottom blown converter during the converter refining; forwarding the molten steel to ladle after the converter refining and controlling C, Mn and Al components and the deoxidation of the molten steel by introducing 80-100kg a recarburlizer, 600-800kg Fe-Mn alloy iron, 300-340kg aluminum through an alloy iron hopper; shifting the ladle to BAP(Bubbling, Al-wire feeding & Powder injection)stand and forming nitrogen atmosphere by blowing nitrogen gas with a 0.2-0.3Nm3/min into the inner space of the ladle in the condition of coming and going repression of air; blowing the nitrogen gas with 0.5Nm3/min from the lower part of the ladle and with a pressure of 6-10kgf/cm2, the amount of flowing gas of 0.9-1.1Nm3/min.; and controlling the nitrogen component of the molten steel within a range of goal, carrying out component analysis of the molten steel, followed by fine tuning the remaining alloy components C, Mn and Al within a range of goal by adding the recarburlizer, alloy iron and aluminum to the molten steel in order to control component be less than the range of goal.

Description

저탄소, 질소규제강의 용강제조방법Manufacturing method of molten steel of low carbon, nitrogen regulated steel

제1도는 본 발명의 일실시예에 의한 방법을 실시하기 위한 공정개략도.1 is a process schematic diagram for carrying out a method according to one embodiment of the invention.

제2도는 종래의 방법과 본 발명의 방법에 따른 용강중 질수함량 변화를 나타낸 그래프.Figure 2 is a graph showing the water content change in the molten steel according to the conventional method and the method of the present invention.

* 도면의 주요부분에 대한 부호의 설명* Explanation of symbols for main parts of the drawings

1 : 전로 2 : 용강1: converter 2: molten steel

3 : 전로저취노즐 4 : 전로랜스3: converter lower nozzle 4: converter lance

6 : 합금철 호퍼 8 : 수강레이들6: ferroalloy hopper 8: steel ladle

14 : 레이들 커버 15 : 패킹재14 ladle cover 15 packing material

17 : 상취랜스노즐17: Nozzle Lance Nozzle

본 발명은 컨테이너이 외판재 등에 사용되는 고내후성 저탄소, 질소규제강의 용강제조방법에 관한 것이며, 보다 상세히는 정력단계에서 용강중 질소성분을 효과적으로 첨가하여 저탄소, 질소규제강의 용강을 제조하는 방법에 관한 것이다.The present invention relates to a method for producing molten steel of high weatherability low carbon, nitrogen-regulated steel in which containers are used in outer plate materials, and more particularly, to a method for producing molten steel of low-carbon, nitrogen-regulated steel by effectively adding nitrogen components in molten steel in the energizing step.

일반적으로 전탄소, 질소규제강은 용선을 전로에서 정련한 후 출강되는 용강에 가탄제, 페로망간 등 합금성분 첨가제와 탈산제로서 알루미늄을 첨가시킨 다음 용강의 질소성분을 첨가시켜 최종강중의 질소함량을 약 0.007-0.013중량% 함유시키므로써 제조하게 된다. 저탄소강에 질소함량이 다량 함유하도록 제어된 질소규제강은 강중의 Al과 반응하여 석출된 AlN의 시효경화에 의해 성형성과 강도를 동시에 만족할 수 있어 컨테이너(Container) 등의 고내후성강으로 매우 유용하다.In general, all carbon and nitrogen-regulated steels are refined from molten iron in converters, and alloying additives such as charcoal and ferro-manganese and aluminum are added as deoxidizer and molten steel is added to the molten steel. It is prepared by containing about 0.007-0.013% by weight. Nitrogen-regulated steel, which is controlled to contain a large amount of nitrogen in low carbon steel, can satisfy both formability and strength by aging hardening of AlN precipitated by reacting with Al in steel, which is very useful for high weather resistance steel such as containers. .

상기와 같은 저탄소, 질소규제강의 용강에 질소성분을 첨가하는 종래의 방법으로는 RH 진공탈가스 장치에서 환류가스로 질소를 첨가하는 방법과 아크(ARC) 공정에서 전극봉을 사용하여 용강에 질소를 첨가시키는 방법(일본 특허공개(소) 61-272311)을 들 수 있다.Conventional methods for adding nitrogen to molten steel of low carbon, nitrogen-regulated steel as described above include adding nitrogen to reflux in a RH vacuum degassing apparatus and adding nitrogen to molten steel using electrodes in an arc (ARC) process. And Japanese Patent Laid-Open No. 61-272311.

전자의 경우는 전로경련시 기체 산호를 상취하고, 저취노즐을 통해 Ar 가스를 취입한 다음, 출강시 가탄제, Fe-Mn-N 및 Al 등의 합금철을 첨가시키고, RH 진공 탈가스 처리시 용강의 환류가스로 질소를 사용하여 저탄소, 질소규제강 용강을 제조하는 방법이다. 그러나 RH 진공탈가스장치를 사용하여 환류가스로 질소를 사용하여 첨가하는 경우 50-70torr 정도의 감압상태를 유지하면서 용강의 흡질반응과 탈질반응이 동시에 진행되기 때문에 용강중의 질소성분 증가속도가 상대적으로 낮아 용강 제조시간이 과다하게 소요되어 생산성이 떨어질 뿐만 아니라 용강제조에 부자재인 Fe-Mn-N과 RH 진공탈가스 설비를 사용함에 따른 용강의 제조원가상승의 문제점이 있었다. 한편, 아크 공정에서 전극봉을 사용한 질소첨가방법은 전극봉 하나에 관통공을 설치하고 아크 승온작업중 그 관통공을 통해 질소가스를 용강에 취입시키는 방법으로써 이 방법에 의해 질소를 취입하는 경우 질소가 슬래그층을 통과하여 용강으로 전달되기 때문에 용강내의 질소성분 증가속도가 낮을 뿐만 아니라 질소첨가 도중에 탄소 전극봉에 의해 용강의 탄소성분이 픽-업되며 용강의 승온이 필요하지 않는 경우라도 질소첨가를 위해 용강을 승온시켜야 하는 문제점이 있는 것이다.In the former case, gaseous corals are inhaled during converter convulsions, Ar gas is blown through the low-nozzle nozzles, and carbon steel, Fe-Mn-N, and Al alloys are added during tapping, and RH vacuum degassing treatment It is a method for producing low carbon, nitrogen-regulated molten steel using nitrogen as reflux gas of molten steel. However, when nitrogen is added as reflux gas using the RH vacuum degassing device, the nitrogen adsorption and denitrification reactions of molten steel proceed simultaneously while maintaining a reduced pressure of 50-70 torr. Low molten steel takes too much time to reduce productivity, and there is a problem of rising manufacturing cost of molten steel due to the use of subsidiary Fe-Mn-N and RH vacuum degassing equipment. On the other hand, the method of adding nitrogen using electrodes in the arc process is to install a through hole in one electrode and blow nitrogen gas into the molten steel through the through hole during the arc heating operation. As it passes through to the molten steel, the rate of increase of nitrogen in the molten steel is not only low, but also the carbon component of the molten steel is picked up by the carbon electrode during nitrogen addition, and the molten steel is raised for nitrogen even if the temperature of molten steel is not required. There is a problem that needs to be done.

이에 본 발명의 목적은 상기와 같은 종래의 문제점을 해결한 보다 개선된 저탄소, 질소규제강의 용강제조방법을 제공하는데 있다. 나아가 본 발명의 목적은 용강중 질소성분을 보다 효과적이고도 용이하게 첨가할 수 있는 저탄소, 질소규제강의 용강제조방법을 제공하는데 있다.It is an object of the present invention to provide an improved molten steel manufacturing method of a low carbon, nitrogen-regulated steel that solves the conventional problems as described above. Furthermore, it is an object of the present invention to provide a molten steel manufacturing method of low carbon, nitrogen-regulated steel which can add nitrogen component in molten steel more effectively and easily.

본 발명에 의한 저탄소, 질소규제강의 용강제조방법은, 최종강 성분이 탄소함량 0.05-0.08중량%, 망간함량 0.3-0.5중량%, 질소함량 0.007-0.013중량%, 알루미늄 함량 0.02-0.06중량%를 포함하여 조성되는 저탄소, 질소규제강의 용강제조방법에 있어서, 전로전연중 전로저취노즐을 통해 용강에 250톤 용강을 기준으로 질소가스를 5.6-8.5Nm3/min로 취입하여 용강중 질소성분을 첨가하는 단계 ; 전로정련후 용강을 수강 레이들로 출강하고 합금철 호퍼를 통해 가탄제 : 80-100kg, 합금철 Fe-Mn : 600-800kg 및 알루미늄 : 300-340kg의 범위로 투입하여 용강의 탈산과 함께 용강중 C, Mn, Al 성분을 조절하는 단계 ; 그후 상기 수강레이들을 BAP(Bubbling, Al-wire feeding Powder injection) 스탠드로 이동시키고 외부로부터의 공기출입을 억제시킨 상태에서 상기 수강 레이들 내부 공간에 질소가스를 0.2-0.3Nm3/min의 유량으로 취입하여 질소분위기를 형성하는 단계 ; 상기 수강레이들 하부로부터 질소가스를 0.5Nm3/min로 취입하고, 수강레이들 상부로부터 질소가스를 압력 6-10kgf/cm2유량 0.9-1.1Nm3/min로 취입하는 단계 ; 및 용강중 질소성분을 목표범위 이내로 제어하고 용강의 성분분석을 행한 다음, 목표범위에 미달되는 성분 조절을 위해 상기 가탄제, 합금철 및 알루미늄을 첨가하여 나머지 합금성분 C, Mn 및 Al을 목표범위 이내로 미세 조정하는 단계 ; 를 포함하여 구성된다.In the molten steel manufacturing method of the low carbon, nitrogen-regulated steel according to the present invention, the final steel component is 0.05-0.08% by weight carbon, 0.3-0.5% by weight manganese, 0.007-0.013% by weight nitrogen, 0.02-0.06% by weight aluminum In the molten steel manufacturing method of the low carbon, nitrogen-regulated steel, including, the nitrogen gas is added to the molten steel at 5.6-8.5 Nm 3 / min based on the 250 ton molten steel through the converter low-lowering nozzle during the converter converter. Doing; After refining the steel, tap the molten steel with the steel ladle and inject it into the range of carbonaceous steel: 80-100kg, ferrous alloy Fe-Mn: 600-800kg and aluminum: 300-340kg through the ferrous alloy hopper. Adjusting the Mn and Al components; Thereafter, the tapping ladles are moved to a BAP (Bubbling, Al-wire feeding Powder injection) stand and nitrogen gas is flowed into the tapping ladle at a flow rate of 0.2-0.3 Nm 3 / min while suppressing air inflow from the outside. Blowing to form a nitrogen atmosphere; Blowing nitrogen gas from the lower portion of the water ladle at 0.5 Nm 3 / min and blowing nitrogen gas from the upper portion of the water ladle at a pressure of 6-10 kgf / cm 2 at a flow rate of 0.9-1.1 Nm 3 / min; And controlling the nitrogen component in the molten steel within the target range and performing component analysis of the molten steel, and then adding the above-described carbonaceous agent, ferrous alloy, and aluminum to control the components that fall below the target range. Fine tuning; It is configured to include.

이하, 본 발명에 대하여 상세히 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

일반적으로 용철에서의 질소거동은 Fe-N-X계에서의 질소용해도 및 용철의 질소흡수속도를 중심으로 다음과 같이 요약될 수 있다.In general, the nitrogen behavior in molten iron can be summarized as follows based on the nitrogen solubility in Fe-N-X and the nitrogen absorption rate of molten iron.

Fe-N-X계에서의 용철의 질소용해반응은 Sievert 법칙에 의해 아래의 식(1)로 표시되며, 질소 1기압하에서의 용해도는 식 (2)로 표시할 수 있다.The nitrogen dissolution reaction of molten iron in Fe-N-X system is represented by the following formula (1) by Sievert's law, and the solubility under one atmosphere of nitrogen can be represented by formula (2).

상기 (2)식으로부터 구한 용철의 질소 용해도는 1600℃에서 약 457ppm이 된다. 그리고, 용철의 질소용해도에 미치는 제(諸) 원소의 영향은 V, Cr, Mn 등이 질소의 용해도를 증가시키며, C, Si, Ni 등은 질소용해도를 감소시킨다.Nitrogen solubility of molten iron determined from the above formula (2) is about 457 ppm at 1600 ° C. In addition, the effect of the secondary element on the nitrogen solubility of molten iron is that V, Cr, Mn and the like increase nitrogen solubility, and C, Si, Ni and the like decrease nitrogen solubility.

또한, 1기압하에서의 용철의 질소흡수 속도는 아래의 식(3)으로 표시할 수 있다.In addition, the nitrogen absorption rate of molten iron under 1 atmosphere can be expressed by the following formula (3).

여기서 KL' : 겉보기 물질이동계수(cm/sec)Where KL ': apparent mass transfer coefficient (cm / sec)

A : 반응계면적(cm2)A: reaction area (cm 2 )

V : 용철의 체적(cm3)V: Volume of molten iron (cm 3 )

[%N]s,[%B] : 각각 질소의 평형농도 및 실제농도[% N] s, [% B]: Equilibrium and actual concentrations of nitrogen, respectively

그런데 겉보기 물질이동 계수는 표면활성화제(산소, 유황등)가 첨가되면 현저하게 감소된다. 그러나 합금 원소의 경우, 질소용해도에는 영향을 미치지만 물질이동계수에는 영향을 미치지 못하며, 탈산원소(Al, Ti, Si, Mn 등)와 산소가 공존할 경우 물질이동계수가 크게 감소하는 경향을 나타낸다. 또한, 위의 식(3)에서 겉보기 물질이동계수가 일정한 경우, 반응용기가 결정되면 용철의 체적은 반응용기에 따라 결정되므로 용철의 흡질속도를 증가시키기 위해서 반응계면적을 증가시키는 것이 유일한 방법인 것이다.However, the apparent mass transfer coefficient is significantly reduced when surface activators (oxygen, sulfur, etc.) are added. In the case of alloying elements, however, the nitrogen solubility is affected but not the mass transfer coefficient, and when the deoxidation element (Al, Ti, Si, Mn, etc.) and oxygen coexist, the mass transfer coefficient tends to decrease significantly. . In addition, when the apparent material transfer coefficient is constant in Equation (3), when the reaction vessel is determined, the volume of molten iron is determined according to the reaction vessel, so the only method is to increase the reaction surface area to increase the absorption rate of molten iron. .

본 발명자는 상기와 같은 점을 감안하여 본 발명을 완성하기에 이르렀다. 본 발명에서는 전로에서 용강정련시 통상의 불활성가스(Ar 등)를 용강에 취입시키는 대신 질소가스를 일정수준까지 첨가시키고, 정련후 수강레이들로 출강시켜 용강탈산을 진행시킴과 동시에 용강중 C, Mn, Al 성분을 첨가하였으며, 그후 수강레이들을 BAP 스탠드로 옮기고 수강레이들 내부를 외부와 최대한 차단하여 내부분위기 조절을 용이하게 함과 동시에 내부공간에 질소가스를 취입하여 질소분위기를 형성시킨 후 레이들 하부 및 상부로부터 질소를 취입시키고 이때 용강의 심한 교반력으로 나탕부위를 형성시켜 이를 통해서도 용강의 흡질반응을 진행시키므로써 용강중 질소성분을 단시간에 용이하게 목표범위 이내로 첨가시키는 것이다.The present inventors have completed the present invention in view of the above. In the present invention, instead of blowing ordinary inert gas (Ar, etc.) into molten steel during the refining of the converter, nitrogen gas is added to a certain level, and after refining, the molten steel is decanted to proceed with molten steel and at the same time, C, Mn in molten steel. , Al component was added, and then the taps were moved to the BAP stand and the inside of the taps was cut off to the outside to facilitate the control of the atmosphere, and the nitrogen atmosphere was blown into the inner space to form a nitrogen atmosphere. Nitrogen is blown from the lower part and the upper part, and at this time, the molten steel is formed by the strong stirring force, thereby adsorbing the molten steel through the adsorption reaction, and thus the nitrogen component in the molten steel is easily added within the target range in a short time.

제1도는 본 발명의 방법을 실시하기 위한 공정을 예시한 것이다. 먼저, 전로(1) 정련중 전로하단에 형성된 전로 저취노즐(3)을 통해 질소가스를 용강내에 취입하여 용강중의 질소성분을 일정수준까지 되도록 첨가시킨다. 이때, 용강중의 질소성분은 목표량(70-130ppm) 수준 근처에까지 이르도록 용강내에 취입되는 질소가스는 250톤 용강기준으로 5.6Nm3/min의 용강을 취입함이 바람직하다.1 illustrates a process for carrying out the method of the present invention. First, the nitrogen gas is blown into the molten steel through the converter low odor nozzle 3 formed at the bottom of the converter during the refining of the converter 1 and the nitrogen component in the molten steel is added to a predetermined level. At this time, the nitrogen gas blown into the molten steel to reach the target amount (70-130ppm) level near the molten steel is preferably injected into the molten steel of 5.6Nm 3 / min based on the 250 ton molten steel.

전로취련후, 출강구(5)를 통해 용강을 수강레이들(8)로 출강하며, 이때 합금철 호퍼(6)에 기저장된 가탄제, 알루미늄 및 합금철 Fe-Mn을 출강류(7)에 투입시켜 용강탈산을 진행시키면서 용강중 C, Mn, Al 성분을 첨가한다. 전로를 사용하는 제강공정에서는 C : 0.05-0.08중량%, Mn : 0.3-0.5중량%, N : 0.007-0.013중량%, Al : 0.02-0.06중량%인 저탄소 질소규제강의 250톤 용강을 목표로 하는 경우 가탄제 : 80-100kg, Fe-Mn ; 600-800kg 및 Al : 300-340kg 정도 투입하면 적당하다.After the converter is blown, the molten steel is pulled out through the tapping hole 5 into the tapping ladle 8, wherein the carbonaceous, aluminum and ferroalloy Fe-Mn pre-stored in the ferroalloy hopper 6 is transferred to the tapping flow 7. Add C, Mn, and Al components in molten steel while advancing molten steel for deoxidation. In steelmaking processes using converters, 250 tons of low carbon nitrogen-regulated steels with C: 0.05-0.08 wt%, Mn: 0.3-0.5 wt%, N: 0.007-0.013 wt% and Al: 0.02-0.06 wt% If carburizing agent: 80-100kg, Fe-Mn; 600-800kg and Al: about 300-340kg is suitable.

출강이 완료된 후, 수강레이들(8)을 BAP(Bubbling, Al-wire feeding Powder injection) 스탠드로 이동시키고, 수강레이들에 먼저 레이들 커버(14)를 씌운다. 이때, 수강레이들과 레이들 커버 사이에는 패킹재(15, 통상 유리솜 사용)를 설치하여 외부로부터의 공기출입을 최대한 억제시킴으로써, 수강레이들 내부의 분위기 조절이 용이하도록 한다.After the tapping is completed, the tapping ladle 8 is moved to a BAP (Bubbling, Al-wire feeding Powder injection) stand, and the ladle cover 14 is first put on the taping ladle. At this time, the packing material (15, usually using glass wool) is installed between the receiving ladle and the ladle cover to suppress the air inflow from the outside as much as possible, so as to easily control the atmosphere inside the receiving ladle.

레이들 커버에 설치된 분위기 조절 관통공(12)을 통해 수강 레이들 내부 공간(16)에 질소가스를 불어넣어 질소분위기를 형성시킨다. 이때 수강레이들내에 취입되는 질소의 취입속도는 0.2-0.3Nm3/min 정도가 좋다. 그후 레이들 하부노즐(9)을 통해 질소가스를 0.5Nm3/min 속도로 취입시킨다. 그리고, 상취랜스(10)를 용강(2)에 침적시키고, 상취랜스노즐(17)을 통해 질소를 압력 6-10kgf/cm2유량 0.9-1.1Nm3/min로 취입시킨다. 이때, 레이들내 용강의 심한 교반력으로 레이들 슬래그(11)층에 나탕부위(13)가 형성된다. 따라서, 용강중 질소설분은 레이들 하부노즐(9) 및 상취랜스노즐(17)을 통해서 용강에 취입된 질소가스 기포와 용강계면을 통해서 첨가될 뿐만 아니라, 나탕부위(13)을 통해서도 용강의 흡질반응이 진행된다. 이와 같은 방법으로 용강에 질소성분을 첨가할 경우, 반응계면적이 증가되어 용강중 질소성분을 목표범위 이내로 짧은 시간에 용이하게 첨가시킬 수 있다.Nitrogen gas is blown into the water ladle inner space 16 through the atmosphere control through hole 12 installed in the ladle cover to form a nitrogen atmosphere. At this time, the blowing speed of the nitrogen injected into the water ladle is good about 0.2-0.3Nm 3 / min. Thereafter, nitrogen gas is blown through the ladle lower nozzle 9 at a rate of 0.5 Nm 3 / min. Then, the upper lance 10 is immersed in the molten steel 2, and nitrogen is blown through the upper lance nozzle 17 at a pressure of 6-10 kgf / cm 2 flow rate 0.9-1.1 Nm 3 / min. At this time, the bottom part 13 is formed in the ladle slag 11 layer by the severe stirring force of the molten steel in the ladle. Therefore, the nitrogen powder in the molten steel is added not only through nitrogen gas bubbles and molten steel interface blown into the molten steel through the ladle lower nozzle 9 and the upper lance nozzle 17, but also through the molten steel 13 to absorb the quality of the molten steel. The reaction proceeds. When the nitrogen component is added to the molten steel in this manner, the reaction area is increased, and the nitrogen component in the molten steel can be easily added within a target range in a short time.

용강중 질소성분을 목표 범위 이내로 제어하고, 용강성분을 분석한 다음, 용강의 성분조성이 목표에 미달되는 경우, 레이들 커버(14) 상부에 설치된 합금철 호퍼(6)을 통해서 용강에 가탄제, 합금철 및 알루미늄을 첨가하여 나머지 합금성분 C, Nm 및 Al을 목표범위 이내로 미세조정하여 저탄소, 질소규제강의 용강을 제조한다.When nitrogen content in molten steel is controlled within a target range, the molten steel component is analyzed, and when the composition of molten steel does not meet the target, a molten steel is added to the molten steel through the ferroalloy hopper 6 installed on the ladle cover 14. By adding ferroalloy and aluminum, the remaining alloy components C, Nm and Al are finely adjusted within the target range to produce molten steel of low carbon and nitrogen regulated steel.

이하, 본 발명의 실시예에 대하여 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described.

실시예Example

본 실시예에서는 하기 표 1과 같은 조성을 갖는 저탄소, 질소규제강의 용강을 제조하기 위해 250ton 전로(1)와 250ton 수강레이들(8)을 사용하였다. 이때, 정련전 용선의 성분은 C : 4.5%, Si : 0.3%, Mn : 0.3%, P : 0.1%, S : 0.01%이었으며, N과 Al은 거의 존재하지 않았다. 먼저, 250ton 전로(1)에 용선과 스크랩을 장입하고, 전로취련개시와 동시에 저취노즐(3)을 통해 질소가스를 5.6Nm3/min로 취입시키고, 전로취련 70% 시점에서 질소가스의 취입유량을 8.5Nm3/min로 증가시켰다. 전로종점에서 용강중 질소함량은 61ppm였다. 전로로부터 수강레이들로 용강을 출강시키면서, 합금철 호퍼(6)를 통해 가탄제 90kg, 합금철 Fe-Mn 700kg 및 알루미늄 320kg을 출강류(7)에 첨가시켰다. 수강레이들을 BAP 스탠드로 이동시킨 후, 수강레이들에 레이들 커버(14)를 씌웠다. 이때, 수강레이들과 레이들 커버 사이에 유리솜(패킹재, 15)을 삽입시켜 외부로 부터의 공기출입을 최소화하여 수강레이들 내부공간(16)의 질소분위기 형성이 용이하도록 하였다.In this embodiment, a 250ton converter 1 and a 250ton steel ladle 8 were used to manufacture molten steel of low carbon and nitrogen regulated steel having a composition as shown in Table 1 below. At this time, the components of the molten iron before refining were C: 4.5%, Si: 0.3%, Mn: 0.3%, P: 0.1%, S: 0.01%, N and Al were almost absent. First, the molten iron and scrap are charged into a 250 ton converter (1), the nitrogen gas is blown at 5.6 Nm 3 / min through the low bleed nozzle (3) at the beginning of the converter blow, and the blown flow rate of nitrogen gas at the 70% point of the converter blow. Increased to 8.5 Nm 3 / min. Nitrogen content in molten steel was 61ppm at the converter termination point. 90 kg of charcoal, 700 kg of Fe-Mn and 320 kg of aluminum were added to the tapping stream 7 through the ferroalloy hopper 6 while tapping the molten steel from the converter. After moving the tap ladle to the BAP stand, the tap ladle 14 was placed on the tap ladle. At this time, by inserting a glass wool (packing material, 15) between the receiving ladle and the ladle cover to minimize the air inflow from the outside to facilitate the formation of the nitrogen atmosphere in the inner space 16 of the receiving ladle.

레이들 커버에 설치된 분위기 조절관통공(12)을 통해 수강레이들 내부공간(16)으로 질소가스를 0.2-0.3Nm3/min로 취입하여 수강레이들 내부공간에 질소분위기를 형성시켰다. 그리고, 레이들 하부노즐(9)을 통해 질소가스를 0.5Nm3/hr 취입시키면서, 상취랜스(10)을 용강(2)에 침적시키고, 상취랜스노즐(17)을 통해 질소를 압력 7.5kgf/cm2, 유량 1.0Nm3/min로 취입시켰다.Nitrogen gas was blown at 0.2-0.3 Nm 3 / min into the receiving ladle inner space 16 through the atmosphere control through hole 12 installed in the ladle cover to form a nitrogen atmosphere in the inner ladle space. The upper lance 10 is deposited on the molten steel 2 while blowing nitrogen gas through the ladle lower nozzle 9 at 0.5 Nm 3 / hr, and the pressure is 7.5 kgf / cm 2, the flow rate was blown to 1.0Nm 3 / min.

BAP 스탠드에서 정련처리를 개시하기 직전에 용강시료를 채취하여 질소성분을 분석한 결과, 질소함량이 66ppm이였으며, 이로부터 전로종점으로부터 BAP 스탠드에서의 정련개시 직전까지 10분도안 용강중 질소함량이 5ppm 증가되었음을 확인하였다. 그리고, BAP 스탠드에서 용강을 정련처리하는 동안 용강중 질소함량 변화를 측정하기 위하여 용강시료를 5분간격으로 채취, 분석하였다. 용강중 질소함량은 정련시간 5, 10, 14, 20분에 싯점에서 각각 73, 83, 95, 105ppm으로 측정되었으며, 이를 제2도에 그래프로 나타내었다. 제2도에 도시된 바와 같이 용강중 질소성분의 증대속도는 분당 2.13ppm에 달하였다. 이후 용강중 질소성분이 목표범위 이내로 첨가된 것을 확인한 후, 알루미늄 60kg을 용강에 첨가시켜 용강중 알루미늄 함량을 0.043중량%로부터 0.055중량%로 미세조정함으로서, 저탄소, 질소규제강의 용강제조를 완료하였다.As a result of analyzing the nitrogen content of molten steel sample just before starting the refining process in the BAP stand, the nitrogen content was 66 ppm, and from this converter point, the nitrogen content in the molten steel was 5 ppm within 10 minutes from the converter end point to just before starting the refining process. It was confirmed that the increase. In addition, molten steel samples were collected and analyzed at intervals of 5 minutes to measure the nitrogen content change in molten steel during the refining of molten steel in the BAP stand. Nitrogen content in molten steel was measured at 73, 83, 95, and 105 ppm at 5, 10, 14, and 20 minutes of refining time, respectively, and the graph is shown in FIG. As shown in FIG. 2, the rate of increase of nitrogen in molten steel reached 2.13 ppm per minute. Then, after confirming that the nitrogen component in the molten steel was added within the target range, 60 kg of aluminum was added to the molten steel to finely adjust the aluminum content of the molten steel from 0.043% by weight to 0.055% by weight, thereby completing molten steel production of low carbon and nitrogen regulated steel.

상기에서 제조한 용강으로부터 주조하기전 용강시료를 채취하고 분석한 결과, 용강중 합금성분은 각각 탄소 0.06중량%, 망간 0.4중량%, 질소 108ppm임을 확인하였다. 이는 하기 표 1에 개시된 일반적인 저탄소, 질소규제강의 조성과 일치한 것이다. 상기 결과로부터 BAP 스탠드 정련종료로부터 주조개시까지 용강중 질소는 13ppm 증가되며, 알루미늄은 0.004중량% 감소됨을 확인할 수 있다.As a result of collecting and analyzing a molten steel sample before casting from the molten steel prepared above, it was confirmed that the alloy components in the molten steel were 0.06 wt% carbon, 0.4 wt% manganese, and 108 ppm nitrogen, respectively. This is consistent with the composition of the general low carbon, nitrogen-regulated steel disclosed in Table 1 below. From the above results, it can be seen that nitrogen in molten steel is increased by 13 ppm and aluminum is reduced by 0.004 wt% from the completion of BAP stand refining to the start of casting.

한편, 본 발명의 방법과 비교하기 위하여 250톤 전로와 250톤 RH를 사용하고, 본 발명과 동일한 조성을 갖는 용선을 이용하여 저탄소, 질소규제강을 제조하였다. 즉, 종래방법에서는 전로취련중 저취가스로 Ar을 사용하였는데, 이때, 전로출강직전 용강성분은 질소 24ppm이었다. 그리고, 출강시 출량류(5)에 가탄제 90kg, 페로망간 550kg, 알루미늄 320kg, 질화망간 250kg을 첨가하였다. 출강이 완료된 수강레이들(8)을 RH로 이동시키고, 용강시료를 채취하여 성분을 분석한 결과, 질소가 69ppm이였다. 즉, 출강시 용강류에 질화망간을 첨가함으로써, 용강의 질소함량이 45ppm 증가되었다. RH에서는 용강환류가스로 질소를 3Nm3/min 취입시켰으며, 이 가스유량은 본 발명보다도 약 50% 더 많은 것이다. RH에서 총처리시간을 30분으로 하고, 매 10분 간격으로 시료를 채취하여 성분을 분석하고 질소성분을 제2도에 그래프로 나타내었다. 정련 20분 싯점에서 용강에 알루미늄 60kg을 첨가하여 알루미늄 성분을 증가시켰으며, 3분 처리후 용강정련을 완료하였다. 정련중 10분, 20분 및 30분 싯점에서의 용강중 질소함량은 각각 72, 75, 79ppm이였으며, 매분당 질소 성분 증가속도는 매분당 0.33ppm으로 본 발명의 매분당 2.13ppm 보다 현저하게 낮음을 알 수 있었고, 처리 30분에서의 용강성분은 탄소 0.062중량%, 망간 0.41중량%, 알루미늄 0.058중량%, 질소 79ppm으로 하기 표 1에 게시된 일반적인 저탄소, 질소규제강의 조성과 일치하는 것이다.On the other hand, in order to compare the method of the present invention using a 250 ton converter and 250 ton RH, using a molten iron having the same composition as the present invention, a low carbon, nitrogen-regulated steel was prepared. That is, in the conventional method, Ar was used as the low odor gas during the converter blasting, wherein the molten steel component immediately before the converter exited was 24 ppm of nitrogen. In addition, 90 kg of charcoal, 550 kg of ferro-manganese, 320 kg of aluminum, and 250 kg of manganese nitride were added to the quantity of water discharged at the time of tapping. The tapping ladle (8) having completed tapping was moved to RH, and a molten steel sample was collected to analyze the components. As a result, nitrogen was 69 ppm. That is, by adding manganese nitride to the molten steel during tapping, the nitrogen content of the molten steel was increased by 45 ppm. In RH, 3 Nm 3 / min of nitrogen was blown into the molten steel reflux gas, which is about 50% more than the present invention. The total treatment time at RH was 30 minutes, and samples were taken every 10 minutes to analyze the components and the nitrogen components are shown in the graph in FIG. 60 kg of aluminum was added to the molten steel at 20 minutes of refining to increase the aluminum content. After 3 minutes of treatment, the molten steel was completed. Nitrogen contents in molten steel at the 10, 20, and 30 minutes of refining were 72, 75, and 79 ppm, respectively, and the rate of increase of nitrogen content per minute was 0.33 ppm per minute, which is significantly lower than 2.13 ppm per minute of the present invention. It was found that the molten steel component at 30 minutes of treatment was 0.062% by weight of carbon, 0.41% by weight of manganese, 0.058% by weight of aluminum, and 79ppm of nitrogen, which is consistent with the composition of general low carbon and nitrogen-regulated steels listed in Table 1 below.

그러나, 본 발명에 의한 방법은 종래방법에 비하여 최종용강중의 질소첨가 속도가 훨씬 빠름을 알 수 있다. 즉, 본 발명의 방법에 의하면 저탄소, 질소규제강의 용강을 종래의 방법보다 보다 용이하게 제조하면서도, 고가의 합금철 질화망간을 절약하고, 정련시간을 약 10분 단축시킴으로써 보다 저렴하게 제조할 수 있는 효과가 있는 것이다.However, the method according to the present invention can be seen that the rate of nitrogen addition in the final molten steel is much faster than the conventional method. That is, according to the method of the present invention, while manufacturing molten steel of low carbon and nitrogen-regulated steel more easily than the conventional method, it is possible to manufacture cheaper by saving expensive manganese nitride and shortening the refining time by about 10 minutes. It works.

Claims (1)

최종강성분이 탄소함량 0.05-0.08중량%, 망간함량0.3-0.5중량%, 질소함량 0.007-0.013중량%, 알루미늄 함량 0.02-0.06중량%를 포함하여 조성되는 저탄소, 질소규제강의 용강제조방법에 있어서, 전로정련중 전로저취노즐을 통해 용강에 250톤 용강을 기준으로 질소가스를 5.6-8.5Nm3/min로 취입하여 용강중 질소성분을 첨가하는 단계 ; 전로정련후 용강을 수강레이들로 출강하고 합금철 호퍼를 통해 가탄제 : 80-100kg, 합금철 Fe-Mn : 600-800kg 및 알루미늄 : 300-340kg의 범위로 투입하여 용강의 탈산과 함께 용강중 C, Mn, Al 성분을 조절하는 단계 ; 그후 상기 수강레이들을 BAP(Bubbling, Al-wire feeding Powder injection) 스탠드로 이동시키고 외부로부터의 공기출입을 억제시킨 상태에서 상기 수강레이들 내부공간에 질소가스를 0.2-0.3Nm3/min의 유량으로 취입하여 질소분위기를 형성하는 단계 ; 상기 수강레이들 하부로부터 질소가스를 0.5Nm3/min로 취입하고, 수강레이들의 상부로부터 질소가스를 압력 6-10kgf/cm2, 유량 0.9-1.1Nm3/min로 취입하는 단계 ; 및 용강중 질소성분을 목표범위 이내로 제어하고 용강의 성분분석을 행한 다음, 목표범위에 미달되는 성분조절을 위해 용강에 상기 가탄제, 합금철, 및 알루미늄을 첨가하여 나머지 합금성분 C, Mn 및 Al을 목표범위 이내로 미세조정하는 단계 ; 를 포함하는 저탄소, 질소규제강의 용강제조방법.In the molten steel manufacturing method of low carbon, nitrogen-regulated steel, the final steel composition is composed of 0.05-0.08% by weight of carbon, 0.3-0.5% by weight of manganese, 0.007-0.013% by weight of nitrogen, 0.02-0.06% by weight of aluminum, Injecting nitrogen gas into the molten steel at 5.6-8.5 Nm 3 / min based on the 250 ton molten steel through the converter low blowing nozzle during the refining of the converter; After refining the steel, the molten steel is pulled out with the steel ladle, and the alloy is added into the range of 80-100kg, ferrous alloy Fe-Mn: 600-800kg, and aluminum: 300-340kg through the ferrous alloy hopper. Adjusting the Mn and Al components; Thereafter, the tapping ladles are moved to a BAP (Bubbling, Al-wire feeding Powder injection) stand and nitrogen gas is flowed into the tapping ladle at a flow rate of 0.2-0.3 Nm 3 / min while suppressing air inflow from the outside. Blowing to form a nitrogen atmosphere; Blowing nitrogen gas from the bottom of the water ladle at 0.5 Nm 3 / min, and blowing nitrogen gas from the top of the water ladle at a pressure of 6-10 kgf / cm 2 and a flow rate of 0.9-1.1 Nm 3 / min; And controlling the nitrogen component in the molten steel within the target range and performing component analysis of the molten steel, and then adding the above-described carbonaceous agent, ferroalloy, and aluminum to the molten steel to control the components below the target range. Fine tuning within the target range; Molten steel manufacturing method of low carbon, nitrogen-regulated steel comprising a.
KR1019940038971A 1994-12-29 1994-12-29 The making method of low carbon and low nitrogen molten metal KR970005199B1 (en)

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KR100901966B1 (en) * 2002-12-28 2009-06-10 주식회사 포스코 Refining method of low carbon high nitrogen steel
KR20190077754A (en) * 2017-12-26 2019-07-04 주식회사 포스코 Method for Refining Low Carbon and High Manganese Steel

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KR100862030B1 (en) * 2001-12-22 2008-10-07 주식회사 포스코 Atmosphere corrosion resisting steel producting method in mini mill process

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100901966B1 (en) * 2002-12-28 2009-06-10 주식회사 포스코 Refining method of low carbon high nitrogen steel
KR20190077754A (en) * 2017-12-26 2019-07-04 주식회사 포스코 Method for Refining Low Carbon and High Manganese Steel

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