KR20040055436A - Method for Manufacturing Extra-Low Carbon Steel - Google Patents

Method for Manufacturing Extra-Low Carbon Steel Download PDF

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KR20040055436A
KR20040055436A KR1020020082113A KR20020082113A KR20040055436A KR 20040055436 A KR20040055436 A KR 20040055436A KR 1020020082113 A KR1020020082113 A KR 1020020082113A KR 20020082113 A KR20020082113 A KR 20020082113A KR 20040055436 A KR20040055436 A KR 20040055436A
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molten steel
slag
ladle
low carbon
phosphorus
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KR1020020082113A
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Korean (ko)
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KR100910496B1 (en
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안북일
박종화
이창현
김해원
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주식회사 포스코
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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
    • C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
    • 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
    • C21C5/36—Processes yielding slags of special composition
    • 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
    • C21C7/072—Treatment with gases
    • 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
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/0025—Charging or loading melting furnaces with material in the solid state
    • F27D3/0026—Introducing additives into the melt

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • Treatment Of Steel In Its Molten State (AREA)

Abstract

PURPOSE: A method for manufacturing ultra-low carbon steel having high tensile strength is provided which is capable of adding phosphorus to molten steel as securing superior quality and high cleanliness of molten steel in steelmaking process. CONSTITUTION: In a method for manufacturing ultra-low carbon steel having high tensile strength by tapping molten steel into ladle and discharging slag after manufacturing molten steel and slag containing 2 to 5 wt.% of phosphorus oxide by charging hot metal containing 3.5 to 4.5 wt.% of C and 0.08 to 0.15 wt.% of P into converter in converter refining process and blowing oxygen into hot metal at a flow rate of 10,000 to 14,000 Nm¬3, the method comprises a step of blowing 1.0 to 2.0 Nm¬3/min of an argon gas into molten steel from the bottom of ladle during tapping; and injecting 100 to 500 kg/ton-slag of subsidiary raw materials comprising 20 to 80 wt.% of aluminum (Al) and 20 to 80 wt.% of calcium carbonate (CaCO3) onto slag in the ladle as blowing 1.0 to 2.0 Nm¬3/min of the argon gas into molten steel from the bottom of the ladle after completing tapping, thereby reducing phosphorus oxide in slag so that phosphorus is added into molten steel.

Description

고장력 극저탄소강의 제조방법{Method for Manufacturing Extra-Low Carbon Steel}Method for Manufacturing Extra High-Low Carbon Steel

본 발명은 냉연소재용 고장력 극저탄소강을 제조하는 방법에 관한 것으로서, 보다 상세하게는 제강공정에서 용강내에 인(P)을 첨가시키는 고장력 극저탄소강의 제조방법에 관한 것이다.The present invention relates to a method for manufacturing high tensile ultra low carbon steel for cold rolled materials, and more particularly, to a method for manufacturing high tensile ultra low carbon steel in which phosphorus (P) is added to molten steel in a steelmaking process.

냉연소재용 고장력 극저탄소강은 자동차의 보강재로 사용되는 소재이므로, 높은 강도를 가져야함과 동시에 가공이 잘 되도록 연성을 가져야 한다.High-strength ultra-low carbon steel for cold-rolled materials is a material used as a reinforcement for automobiles, so it must have high strength and ductility so that it can be processed well.

냉연소재용 고장력 극저탄소강의 제조시에는 통상적으로 강도를 확보하기 위하여 용강중의 인(P)함량을 300ppm이상으로, 연성을 확보하기 위하여 용강중의 탄소(C)함량을 50ppm이하로 제어하고 있다.In the manufacture of high strength ultra low carbon steel for cold rolled materials, phosphorus (P) content in molten steel is generally controlled to 300 ppm or more in order to secure strength, and carbon (C) content in molten steel is controlled to 50 ppm or less in order to secure ductility.

제강공정에서 용강내 인성분 함량이 300ppm이상인 냉연소재용 고장력 극저탄소강을 제조하기 위해서는 도 1에 나타난 바와 같이, 제선, 전로정련, 출강 및 인합금철(이하, "Fe-P"라고도 칭함)투입, 탈가스 처리 및 연속주조공정을 차례로 거치게 된다.In order to manufacture high tensile ultra low carbon steel for cold rolled materials having a phosphorus content of 300 ppm or more in the steelmaking process, as shown in FIG. 1, steelmaking, converter refining, tapping and alloying iron (hereinafter also referred to as "Fe-P") injection After this, degassing and continuous casting process are carried out.

상기 제선공정에서는 용광로에 철광석을 장입하여 용선을 제조하는데, 이렇게 제조된 용선에는 탄소가 3.5% ~ 4.5%정도 함유되어 있이며, 이러한 용선중의 탄소를 제거하기 위하여 용선을 전로정련공정으로 보내어 용선을 전로에 장입한 후 순산소를 취입함으로써 용선내 탄소를 하기 반응식(1)에 의하여 산화시켜 일정 함량 (0.02~0.05%)까지 제거하여 용강을 제조한다.In the iron making process, the molten iron is manufactured by charging iron ore into the blast furnace. The molten iron thus prepared contains about 3.5% to 4.5% of carbon, and the molten iron is sent to the converter refining process to remove carbon in the molten iron. After charging to the converter by blowing pure oxygen to oxidize the carbon in the molten iron by the following reaction formula (1) to remove a certain content (0.02 ~ 0.05%) to prepare a molten steel.

(반응식 1)(Scheme 1)

C+ 1/2 O2(g) = CO(g) C + 1/2 O 2 (g) = CO (g)

상기와 같이 전로정련을 종료한 후, 용강을 래들(Ladle)로 출강을 하게 되며, 통상적으로 출강중에 용강중의 인성분을 보충하기 위해서 산업적으로 널리 사용되고 있는 Fe-P 합금철등을 투입한다.After finishing the converter refining as described above, the molten steel is tapped into a ladle (Ladle), and the Fe-P alloy iron, which is widely used industrially, to replenish the phosphorus in the molten steel during the tapping.

상기 Fe-P 합금철로는 Fe: 66-77wt%, P: 20-28wt%, Si: 1-2wt%, V: 1-2wt%, 및 Cu: 1-2wt%를 함유하는 함금철이 주로 사용되고 있으며, 그 입도는 10-100mm정도이다.As the Fe-P alloy iron, a ferrous alloy containing Fe: 66-77wt%, P: 20-28wt%, Si: 1-2wt%, V: 1-2wt%, and Cu: 1-2wt% is mainly used. The particle size is about 10-100mm.

상기와 같이 전로정련되어 출강된 용강은 진공 탈가스설비인 RH-TOB(POSB)등으로이송되어 진공상태에서 탄소를 50ppm이하로 제거한 후, 연주공정으로 이송한다.As described above, the molten steel that has been refined and reflowed is transferred to a vacuum degassing facility, such as RH-TOB (POSB), to remove carbon below 50 ppm in a vacuum state, and then transferred to a regeneration process.

상기한 종래방법을 사용하여 냉연소재용 고장력 극저탄소강을 제조하는 경우에는 인성분 보충용으로 Fe-P 합금철을 사용하기 때문에, Fe-P 합금철중에 인성분이외의 규소([Si]), 바나듐([V]), 구리([C])등의 불순성분이 함유되어 있어 이들 성분들의 함량도 동시에 증가시켜 용강중의 불순물의 함량이 증가되는 문제점이 있다.When manufacturing high-strength ultralow carbon steel for cold-rolled materials using the conventional method described above, since Fe-P alloy iron is used for phosphorus supplementation, silicon ([Si]) and vanadium other than phosphorus in Fe-P alloy iron are used. Since impurity components such as ([V]) and copper ([C]) are contained, the content of these components is also increased to increase the content of impurities in the molten steel.

또한, Fe-P 합금철을 투입하는 경우에는 Fe-P 합금철에 함유되어 있는 각 성분들이 하기 반응식(2), (3) 및 (4)와 같이 용강의 용존산소와 반응하여 비금속 개재물을 형성하여 용강의 청정성을 떨어뜨리는 문제점이 있다.In addition, when the Fe-P alloy iron is added, each component contained in the Fe-P alloy iron reacts with dissolved oxygen of molten steel to form a non-metallic inclusion as shown in the following Reaction Formulas (2), (3) and (4). There is a problem to lower the cleanliness of the molten steel.

(반응식 2)(Scheme 2)

Si+ 2O= SiO2(s) Si + 2 O = SiO 2 (s)

(반응식 3)(Scheme 3)

2V+ 3O= V2O3(s)2 V + 3 O = V 2 O 3 (s)

(반응식 4)(Scheme 4)

2Cu+O= Cu2O(s)2 Cu + O = Cu 2 O (s)

상기한 비금속 개재물들은 냉연과정에서 발현하여 표면흠이나 판파단을 유발하고, 최종 제품의 기계적 성질 및 도색 불량등 품질을 저하시키게 된다.The non-metallic inclusions are expressed in the cold rolling process to cause surface flaws or plate breakage, and deteriorate the quality such as mechanical properties and paint failure of the final product.

본 발명은 상기한 종래기술의 제반 문제점을 해결하기 위하여 연구 및 실험을 행하고, 그 결과에 근거하여 본 발명을 제안하게 된 것으로서, 본 발명은 제강공정에서고장력 극저탄소강을 제조하는 방법에 있어서 용강중의 불순물을 증가시키지 않고 또한 용강의 청정성도 떨어뜨리지 않으면서 용강에 인을 첨가시킬 수 있는 고장력 극저탄소강의 제조방법을 제공하고자 하는데, 그 목적이 있는 것이다.The present invention has been conducted in order to solve the above-mentioned problems of the prior art, and based on the results, the present invention is proposed, the present invention is a molten steel in the method of manufacturing high tensile ultra low carbon steel in the steelmaking process It is an object of the present invention to provide a method for producing high-strength ultra-low carbon steel that can add phosphorus to molten steel without increasing impurities in the molten steel and degrading the cleanliness of molten steel.

도 1은 종래의 냉연소재용 고청정 고장력 극저탄소강을 제조하는 공정을 나타내는 공정도1 is a process chart showing a process for manufacturing a high-cleaning high tensile ultra low carbon steel for a conventional cold rolled material

도 2는 본 발명에 따라 냉연소재용 고청정 고장력 극저탄소강을 제조하는 공정을 나타내는 공정도Figure 2 is a process diagram showing a process for producing a high-cleaning high tensile ultra low carbon steel for cold rolled materials according to the present invention

도 3은 본 발명에 따라 부원료를 투입한 경우에 있어서 탄산칼슘(CaCO3)에 의한 슬래그 내부 CO2가스 거품발생을 나타내는 모식도Figure 3 is a schematic diagram showing the generation of CO 2 gas bubbles in the slag due to calcium carbonate (CaCO 3 ) when the secondary raw material is added according to the present invention

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

본 발명은 전로정련공정에서 C: 3.5~4.5wt% 및 P: 0.08~0.15wt%를 함유하는 용선을 전로에 장입하여 10,000Nm3~ 14,000Nm3의 유량으로 산소를 취입하여 용강 및 인산화물을 함유하는 슬래그를 제조한 다음, 래들로 용강을 출강하고 슬래그를 유출하여 고장력 극저탄소강을 제조하는 방법에 있어서,The invention in a converter refining process C: 0.08 to to by the contents of the molten iron containing 0.15wt% to converter blowing oxygen at a flow rate of 3 ~ 10,000Nm 14,000Nm 3 molten steel, and phosphate: 3.5 ~ 4.5wt% and P In the method of manufacturing the slag containing, and then tapping the molten steel with the ladle and out the slag to produce a high-strength ultra-low carbon steel,

상기 출강시 래들 바닥으로부터 1.0~2.0Nm3/분 유량의 아르곤 가스를 취입하고, 그리고 출강이 완료된 후, 래들 바닥으로부터 1.0~2.0Nm3/분 유량의 아르곤 가스를 취입하면서 알루미늄(Al): 20~80wt% 및 탄산칼슘(CaCO3): 20~80wt%로 이루어진 부원료를 100~ 500kg/ton-slag 의 투입량으로 래들내의 슬래그위에 투입하여 슬래그중의 인산화물을 환원시켜 용강에 인을 첨가시키는 것을 특징으로 하는 고장력 극저탄소강의 제조방법에 관한 것이다.When the post-tapping and 1.0 ~ 2.0Nm 3 / min flow rate of argon gas blown from the ladle bottom, and the tapping was complete, aluminum (Al) and 1.0 ~ 2.0Nm 3 / min flow rate of argon gas blown into the ladle from the bottom: 20 ~ 80wt% and calcium carbonate (CaCO 3 ): 20 ~ 80wt% of the feedstock is added to the slag in the ladle at a dose of 100 ~ 500kg / ton-slag to reduce the phosphate in the slag to add phosphorus to the molten steel The present invention relates to a method for producing high tensile ultra low carbon steel.

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

도 2에는 본 발명에 따라 고장력 극저탄소강을 제조하는 공정을 나타내는 공정도가 도시되어 있다.2 is a process diagram illustrating a process for producing high tensile ultra low carbon steel in accordance with the present invention.

도 2에도 나타난 바와 같이, 본 발명은 전로정련공정에서 C: 3.5~4.5wt% 및 P: 0.08~0.15wt%를 함유하는 용선을 전로에 장입하여 10,000Nm3~ 14,000Nm3의 유량으로 산소를 취입하여 용강 및 인산화물을 함유하는 슬래그를 제조한 다음, 래들로 용강을 출강하고 슬래그를 유출하여 고장력 극저탄소강을 제조하는 방법에 바람직하게 적용되는 것이다.As shown in FIG. 2, the present invention charges a molten iron containing C: 3.5 to 4.5 wt% and P: 0.08 to 0.15 wt% in the converter refining process to obtain oxygen at a flow rate of 10,000 Nm 3 to 14,000 Nm 3 . It is preferably applied to a method for producing slag containing molten steel and phosphate, and then tapping molten steel with a ladle and flowing slag to produce high tensile ultra low carbon steel.

본 발명은 하기 표 1의 조성을 갖는 고장력 극저탄소강용 용강의 제조에 바람직하게 적용될 수 있는 것이다.The present invention can be preferably applied to the production of molten steel for high tensile strength ultra-low carbon steel having the composition shown in Table 1 below.

성분ingredient CC MnMn PP AlAl SiSi VV CuCu 함량(wt%)Content (wt%) ≤0.005≤0.005 0.06-1.200.06-1.20 0.03-0.150.03-0.15 0.02-0.060.02-0.06 ≤0.03≤0.03 ≤0.008≤0.008 ≤0.06≤0.06

전로정련공정에서 C: 3.5~4.5wt% 및 P: 0.08~0.15wt%를 함유하는 용선을 전로에 장입하여 10,000Nm3~ 14,000Nm3의 유량으로 산소를 취입하여 용강으로 전로정련하는 경우에는 상기 식(1)에서와 같이 탄소를 산화시켜 CO가스를 형성하고 또한 하기 식(3)에서와 같이 인성분을 산화시켜 인산화물을 형성한다.In the converter refining process, when molten iron containing C: 3.5 to 4.5 wt% and P: 0.08 to 0.15 wt% is charged into the converter and blown with oxygen at a flow rate of 10,000 Nm 3 to 14,000 Nm 3 , the converter is refined to molten steel. Carbon is oxidized as in Formula (1) to form CO gas, and phosphorus component is formed by oxidizing phosphorus component as in Formula (3) below.

(반응식 3)(Scheme 3)

2P+ 5/2 O2(g) = P2O5(s)2 P + 5/2 O 2 (g) = P 2 O 5 (s)

상기와 같이 형성되는 인산화물은 슬래그중에 2∼5wt% 정도 함유되어 있다.The phosphate formed as described above contains 2 to 5 wt% of the slag.

본 발명에서는 전로정련을 마친 후, 전로내에 인산화물(P2O5)을 함유한 슬래그를 용강과 함께 래들로 출강한 다음, 래들 상부로 부상된 슬래그 위에 인보다 산소와의 친화력이 큰 알루미늄(Al)과 탄산칼슘(CaCO3)을 적정 비로 배합한 부원료를 투입하여, 슬래그와 부원료가 잘 섞이도록 함으로써, 인산화물을 알루미늄으로 환원시켜서 용강에 순수한 인 성분을 증가시킨다.In the present invention, after finishing the converter refining, the slag containing phosphate (P 2 O 5 ) in the converter is pulled out with the molten steel as a ladle, and then the aluminum having a greater affinity for oxygen than phosphorus on the slag floated to the upper ladle Subsidiary materials containing Al) and calcium carbonate (CaCO 3 ) are added in an appropriate ratio, so that the slag and the subsidiary materials are mixed well, thereby reducing the phosphate to aluminum to increase the pure phosphorus component in the molten steel.

특히, 출강이 시작되면 용강에 비해 밀도가 작은 슬래그가 래들 상부로 충분히 부상되고, 슬래그와 부원료가 잘 혼합되어 반응이 촉진될 수 있도록 불활성 가스인 아르곤(Ar)가스를 래들 바닥으로부터 1.0~2.0Nm3/분 유량으로 취입하는 것이 바람직하다.Particularly, when the tapping starts, slag, which is less dense than molten steel, floats to the upper part of the ladle sufficiently, and the argon (Ar) gas, which is an inert gas, is 1.0 to 2.0 Nm from the bottom of the ladle so that the slag and the subsidiary materials are mixed well to promote the reaction. It is preferable to blow at 3 / min flow rate.

래들 바닥으로부터 1.0~2.0Nm3/분 유량의 아르곤 가스 취입은 출강 후 상기 부원료의 투입시에도 행해진다.Argon gas blowing at a flow rate of 1.0 to 2.0 Nm 3 / min from the bottom of the ladle is also performed at the time of adding the subsidiary materials after tapping.

상기 아르곤 가스 취입 유량이 너무 적은 경우에는 용강내로의 아르곤 가스의 취입이 곤란하고, 너무 큰 경우에는 슬래그와 용강이 래들밖으로 유출될 우려가 있기 때문에 상기 아르곤 가스 취입 유량은 1.0~2.0Nm3/분으로 설정하는 것이 바람직하다.If the argon gas blowing flow rate is too small, it is difficult to blow the argon gas into the molten steel. If the argon gas blowing flow rate is too large, the slag and molten steel may flow out of the ladle, so the argon gas blowing flow rate is 1.0 to 2.0 Nm 3 / min. It is preferable to set to.

상기와 같이 불활성 가스인 아르곤(Ar)가스를 래들 바닥으로부터 취입하면서 알루미늄(Al)과 탄산칼슘(CaCO3)을 함유하는 부원료를 투입하는 경우에는 알루미늄과 산소의 친화력이 인의 산소 친화력보다 크므로, 투입된 상기 부원료중 알루미늄은 하기 식(4)와 같은 반응을 일으켜서 슬래그중의 인산화물을 환원시켜서 용강에 인성분을 공급한다.As described above, when an auxiliary material containing aluminum (Al) and calcium carbonate (CaCO 3 ) is introduced while argon (Ar) gas, which is an inert gas, is injected from the bottom of the ladle, the affinity between aluminum and oxygen is greater than the oxygen affinity of phosphorus. The aluminum in the added subsidiary material reacts as shown in the following formula (4) to reduce the phosphate in the slag to supply the phosphorus component to the molten steel.

(반응식 4)(Scheme 4)

3/5 P2O5(s) + 2Al= 6P+ Al2O3(s)3/5 P 2 O 5 (s) + 2 Al = 6 P + Al 2 O 3 (s)

또한, 부원료중 탄산칼슘은 인산화물의 환원반응에는 직접 관여하지 않으며, 900℃이상의 고온 슬래그중에 투입되면 하기 식(5)와 같은 반응을 일으키면서, 슬래그 내부에 CO가스 거품을 형성하여 슬래그와 알루미늄의 반응을 촉진시킨다.In addition, calcium carbonate in the subsidiary material does not directly participate in the reduction reaction of phosphate, and when injected into hot slag of 900 ° C. or higher, it causes a reaction as shown in Equation (5) below, and forms CO gas bubbles inside the slag to form slag and aluminum. Promote the reaction.

(반응식 5)(Scheme 5)

CaCO3(s) + Heat(900℃) = CaO(s) + CO2(g)CaCO 3 (s) + Heat (900 ° C) = CaO (s) + CO 2 (g)

슬래그 내부 CO가스 거품에 의한 슬래그와 알루미늄 반응의 모식도를 도 3나타내었다.The schematic diagram of the slag and aluminum reaction by the slag of CO gas bubbles inside is shown in FIG. 3.

본 발명에 있어서 중요한 점은 슬래그중 인산화물의 환원을 위해서 투입한 알루미늄이 슬래그가 아닌 용강중의 용존산소와 반응해서는 안된다는 것이다.An important point in the present invention is that aluminum introduced for the reduction of phosphate in slag should not react with dissolved oxygen in molten steel other than slag.

왜냐하면, 용강의 용존산소와 반응할 경우 하기 식(6)와 같이 용강내 비금속 개재물인 알루미나(Al2O3)를 형성하여 용강의 청정도를 나쁘게 하기 때문이다.This is because, when reacting with dissolved oxygen of molten steel, alumina (Al 2 O 3 ), which is a non-metallic inclusion in molten steel, is degraded as shown in Equation (6) below, resulting in poor cleanliness of molten steel.

(반응식 6)(Scheme 6)

2Al+ 3O= Al2O3(s)2 Al + 3 O = Al 2 O 3 (s)

상기 부원료에 함유되는 알루미늄은 상기한 바와 같이 슬래그중의 인산화물(P2O5)을 환원시켜서 용강에 순수한 인 성분을 증가시키는 작용을 하는 것으로서, 그 양이 너무 적으면, 알루미늄에 의한 인산화물의 환원반응이 미약하여 용강으로의 복린이 미약하고, 너무 많은 경우에는 슬래그중의 인산화물의 환원 뿐만 아니라 용강중의 산소와 반응하여 Al2O3등의 비금속개재물을 형성하여 용강의 청정성을 떨어뜨리므로, 상기 부원료중의 알루미늄의 함량은 20~80wt%로 설정하는 것이 바람직하다.The aluminum contained in the secondary raw material acts to reduce the phosphate (P 2 O 5 ) in the slag to increase the pure phosphorus component in the molten steel, as described above, if the amount is too small, phosphate by aluminum Poor lean to the molten steel is weak due to the weak reduction reaction, and if too much, the cleanness of the molten steel is reduced by forming a non-metallic inclusion such as Al 2 O 3 by reacting with the oxygen in the molten steel as well as reducing the phosphate in the slag. Therefore, the content of aluminum in the secondary material is preferably set to 20 ~ 80wt%.

상기 부원료중에 함유되어 있는 탄산칼슘(CaCO3)은 상기한 바와 같이 CO2가스를 발생시켜 슬래그를 교반시켜 알루미늄에 의한 P2O5의 환원반응을 촉진시키고, CaO에 의하여 비금속개재물을 제거하여 용강의 청정성을 향상시키는 작용을 한다.Calcium carbonate (CaCO 3 ) contained in the secondary raw material generates CO 2 gas as described above to agitate the slag to promote the reduction reaction of P 2 O 5 by aluminum, and remove the non-metallic inclusions by CaO to molten steel It works to improve the cleanliness of the.

상기 탄산칼슘(CaCO3)의 함량이 너무 적은 경우에는 상기한 탄산칼슘(CaCO3)의 효과를 충분히 얻을 수 없고, 너무 많은 경우에는 알루미늄양이 너무 적어서 알루미늄에 의한 인산화물의 환원반응을 충분히 얻을 수 없으므로, 상기 탄산칼슘(CaCO3)의 함량은 20~80wt%로 설정하는 것이 바람직하다.When the content of calcium carbonate (CaCO 3 ) is too small, the effects of the calcium carbonate (CaCO 3 ) may not be sufficiently obtained, and when too much, the amount of aluminum is too small to sufficiently obtain a reduction reaction of phosphate by aluminum. Since it can not be, the content of the calcium carbonate (CaCO 3 ) is preferably set to 20 to 80wt%.

본 발명에 따라 아르곤(Ar)가스를 래들 바닥으로부터 취입하면서 알루미늄(Al)과 탄산칼슘(CaCO3)을 함유하는 부원료를 투입하여 용강중에 인을 첨가하는 경우에는 용강에 순수한 인성분을 증가시킴은 물론 합금철을 투입할 경우에 발생하는 불순물의 용강내 혼입을 방지하여 용강의 품질을 확보하고, 용강내에 비금속개재물을 발생시키지 않으므로써 고청정성을 확보할 수 있게 된다.According to the present invention, when argon (Ar) gas is blown from the bottom of the ladle and the phosphorus is added to the molten steel by adding an auxiliary material containing aluminum (Al) and calcium carbonate (CaCO 3 ), the pure phosphorus component is increased in the molten steel. Of course, it is possible to secure the quality of the molten steel by preventing the mixing of impurities in the molten steel generated when the alloy iron is added, and to ensure high cleanliness by not generating non-metallic inclusions in the molten steel.

이하, 실시예를 통하여 본 발명을 보다 구체적으로 설명한다.Hereinafter, the present invention will be described in more detail with reference to Examples.

(실시예)(Example)

280ton 생산 용량의 전로에서 하기 표 2의 조성을 갖는 냉연 고장력강을 제조하기위하여 탄소함량이 4.0%, 인함량이 0.1%인 용선을 전로에 장입하고, 13,000Nm3의 순산소를 용강에 초음속으로 취입하여 용강으로 전로정련하였다.In order to manufacture a cold rolled high tensile strength steel having the composition shown in Table 2 in the converter of 280ton production capacity, a molten iron having a carbon content of 4.0% and a phosphorus content of 0.1% was charged into the converter, and pure oxygen of 13,000 Nm 3 was blown into the molten steel at supersonic speed. The converter was refined.

성분ingredient CC MnMn PP AlAl 함량(wt%)Content (wt%) 0.0040.004 0.090.09 0.070.07 0.040.04

이 때, 슬래그중의 인산화물은 3wt%정도였다.At this time, the phosphorus in the slag was about 3wt%.

래들 바닥으로부터 1.0~2.0Nm3/분 유량의 아르곤 가스를 불어 넣으면서, 상기와 같이 전로정련된 용강을 래들로 출강하였다.While the argon gas was blown at a flow rate of 1.0 to 2.0 Nm 3 / min from the bottom of the ladle, the molten steel, which was previously refined as above, was tapped into the ladle.

상기와 같이 출강 및 슬래그 유출이 완료된 후, 래들 바닥으로부터 1.0~1.2Nm3/분 유량의 아르곤 가스를 불어 넣으면서 하기 표 3의 부원료 배합비 및 투입량으로 부원료를 슬래그 위에 투입하여 인산화물을 환원시켜 용강중의 인을 증가시켰다.After the tapping and slag outflow is completed as described above, while blowing argon gas at a flow rate of 1.0 to 1.2 Nm 3 / min from the bottom of the ladle, the subsidiary materials are added to the slag at the sub-mixture blending ratios and amounts shown in Table 3 below to reduce phosphoric acid in molten steel. Increased phosphorus.

상기 부원료 투입전, 후의 용강중의 인[P]의 변화량 및 부원료 투입전, 후의 용강중의 산소 감소량을 측정하고, 그 결과를 하기 표 3에 나타내었다.The amount of change in phosphorus [P] in the molten steel before and after the addition of the subsidiary material and the amount of oxygen reduction in the molten steel before and after the subsidiary material were measured, and the results are shown in Table 3 below.

부원료 투입량(kg/ton-slag)Feedstock input (kg / ton-slag) 부원료 배합비(wt%)Subsidiary Compounding Ratio (wt%) 용강중 [P]증가량(중량%)[P] increase in molten steel (wt%) 용강산소감소량(ppm)Molten Oxygen Reduction (ppm) 알루미늄aluminum 탄산칼슘Calcium carbonate 150150 00 100100 0.0000.000 00 2020 8080 0.0030.003 00 4040 6060 0.0050.005 00 6060 4040 0.0080.008 00 8080 2020 0.0110.011 00 100100 00 0.0120.012 7070 300300 00 100100 0.0000.000 00 2020 8080 0.0050.005 00 4040 6060 0.0090.009 00 6060 4040 0.0130.013 00 8080 2020 0.0170.017 00 100100 00 0.0190.019 8080 480480 00 100100 0.0000.000 00 2020 8080 0.0080.008 00 4040 6060 0.0150.015 00 6060 4040 0.0200.020 00 8080 2020 0.0230.023 00 100100 00 0.0250.025 9595 600600 00 100100 0.0000.000 00 2020 8080 0.0110.011 1010 4040 6060 0.0200.020 3030 6060 4040 0.0280.028 6060 8080 2020 0.0310.031 9595 100100 00 0.0320.032 120120

상기 표 3에 나타난 바와 같이, 본 발명에 부합되는 조건으로 부원료를 투입하는 경우에는 산소함량의 감소없이 용강중의 [P]함량을 증가시킬 수 있음을 알 수 있다.As shown in Table 3, it can be seen that in the case of adding the sub-materials under the conditions consistent with the present invention, the [P] content in the molten steel can be increased without decreasing the oxygen content.

한편, 본 발명을 벗어나는 경우에는 [P]함량의 증가가 미약하거나 또는 산소함량이 감소됨을 알 수 있다.On the other hand, in the case of departing from the present invention it can be seen that the increase in the [P] content is weak or the oxygen content is reduced.

상술한 바와 같이, 본 발명은 제강공정에서 고장력 극저탄소강을 제조하는 방법에 있어서 전로정련공정에서 우수한 용강 품질 및 고청정성을 확보하면서 용강중에 인을 첨가시킬 수 있는 효과가 있는 것이다.As described above, the present invention has the effect of adding phosphorus to molten steel while ensuring excellent molten steel quality and high cleanliness in the converter refining process in the method of manufacturing high tensile ultra low carbon steel in the steelmaking process.

Claims (1)

전로정련공정에서 C: 3.5~4.5wt% 및 P: 0.08~0.15wt%를 함유하는 용선을 전로에 장입하여 10,000 ~ 14,000Nm3의 유량으로 산소를 취입하여 용강 및 2-5wt%의 인산화물을 함유하는 슬래그를 제조한 다음, 래들로 용강을 출강하고 슬래그를 유출하여 고장력 극저탄소강을 제조하는 방법에 있어서,In the converter refining process, a molten iron containing C: 3.5 to 4.5 wt% and P: 0.08 to 0.15 wt% is charged into the converter, and oxygen is blown at a flow rate of 10,000 to 14,000 Nm 3 to obtain molten steel and 2-5 wt% of phosphate. In the method of manufacturing a slag containing, and then tapping the molten steel with the ladle and out the slag to produce a high-strength ultra-low carbon steel, 상기 출강시 래들 바닥으로부터 1.0~2.0Nm3/분 유량의 아르곤 가스를 취입하고, 그리고 출강이 완료된 후, 래들 바닥으로부터 1.0~2.0Nm3/분 유량의 아르곤 가스를 취입하면서 알루미늄(Al): 20~80wt% 및 탄산칼슘(CaCO3): 20~80wt%로 이루어진 부원료를 100~ 500kg/ton-slag 의 투입량으로 래들내의 슬래그위에 투입하여 슬래그중의 인산화물을 환원시켜 용강내에 인을 첨가하는 것을 특징으로 하는 고장력 극저탄소강의 제조방법When the post-tapping and 1.0 ~ 2.0Nm 3 / min flow rate of argon gas blown from the ladle bottom, and the tapping was complete, aluminum (Al) and 1.0 ~ 2.0Nm 3 / min flow rate of argon gas blown into the ladle from the bottom: 20 ~ 80wt% and calcium carbonate (CaCO 3 ): A feedstock of 20-80wt% is added to the slag in the ladle at a dose of 100-500kg / ton-slag to reduce phosphorus in the slag to add phosphorus in the molten steel. Manufacturing method of high tensile ultra low carbon steel
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