KR20170089045A - Method and apparatus for manufacturing steel sheet having martensite phase - Google Patents

Method and apparatus for manufacturing steel sheet having martensite phase Download PDF

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KR20170089045A
KR20170089045A KR1020150183266A KR20150183266A KR20170089045A KR 20170089045 A KR20170089045 A KR 20170089045A KR 1020150183266 A KR1020150183266 A KR 1020150183266A KR 20150183266 A KR20150183266 A KR 20150183266A KR 20170089045 A KR20170089045 A KR 20170089045A
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steel sheet
cooling
martensite
coil
heated
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한인석
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주식회사 포스코
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Priority to KR1020150183266A priority Critical patent/KR20170089045A/en
Priority to EP16879266.1A priority patent/EP3395964A4/en
Priority to CN201680074983.0A priority patent/CN108431249A/en
Priority to PCT/KR2016/014817 priority patent/WO2017111399A1/en
Priority to JP2018532216A priority patent/JP2019505667A/en
Publication of KR20170089045A publication Critical patent/KR20170089045A/en

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    • C21METALLURGY OF IRON
    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
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    • C21D1/18Hardening; Quenching with or without subsequent tempering
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    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18Hardening; Quenching with or without subsequent tempering
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    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/56General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering characterised by the quenching agents
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    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
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    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
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    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
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    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
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    • C21D8/00Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
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    • C21D9/00Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
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    • C21D9/00Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
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    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
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    • C21D9/68Furnace coilers; Hot coilers
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    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
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    • C21DMODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
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    • C21D2211/00Microstructure comprising significant phases
    • C21D2211/008Martensite

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Abstract

The present invention relates to a method and apparatus to produce a martensite-containing steel sheet, comprising: a step of preparing a steel sheet in a coil form in which at least a part of austenite is transformed into martensite upon water cooling; a step of heating the steel coil such that at least a part of a microstructure of the steel sheet becomes austenite; and a step of cooling the heated steel sheet coil at a cooling rate of 500 C/sec or more while transferring the steel sheet at a transfer speed of 300 mpm or more, and transforming at least a part of the austenite to martensite. Accordingly, the present invention is able to more economically produce the martensite-containing steel sheet which is less transformed.

Description

마르텐사이트 함유 강판의 제조방법 및 장치{METHOD AND APPARATUS FOR MANUFACTURING STEEL SHEET HAVING MARTENSITE PHASE}TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a martensite-containing steel sheet,

본 발명은 자동차 구조용 강에 사용되는 마르텐사이트 함유 강판의 제조방법 및 장치에 관한 것으로서, 보다 상세하게는 배치식으로 가열하고 연속식으로 냉각하여 마르텐사이트 함유 강판을 제조하는 방법 및 장치에 관한 것이다.
The present invention relates to a method and an apparatus for producing a martensite-containing steel sheet used for automotive structural steel, and more particularly, to a method and apparatus for producing a martensite-containing steel sheet by batchwise heating and cooling continuously.

경량화를 통한 높은 연비와 엄격한 안전 규제를 만족하기 위해 고강도 자동차 구조용 강에 대한 수요가 증가하고 있다. Demand for high strength automotive structural steel is increasing to satisfy high fuel efficiency and strict safety regulations through light weight.

일반적으로 고강도강을 제조하기 위해서 비철금속이나 희토류 등의 합금원소를 첨가한다. In general, an alloy element such as a non-ferrous metal or a rare earth is added to produce a high strength steel.

그러나, 합금원소를 첨가할 경우에는 제조비용이 상승하고 제조 효율성 및 제품 가공성(예컨대, 용접성)이 나빠지는 등의 문제가 있다. However, when alloying elements are added, there is a problem that the manufacturing cost is increased and the manufacturing efficiency and product processability (for example, weldability) are deteriorated.

이러한 이유로 합금 성분을 최소로 하면서 열처리 공정에서 급속 냉각함으로써 강의 강도를 향상시키기 위한 시도가 행해지고 있다. For this reason, attempts have been made to improve the strength of steel by rapid cooling in a heat treatment process while minimizing the alloy component.

이러한 급속 냉각방법의 일례로 담금질(Quenching)을 이용한 방법이 있다. 담금질 냉각방법은 일반적으로 강판 1㎜의 경우, 예를 들면, 초당 1000℃의 냉각속도로 강판을 냉각할 수 있는 방법이다. As an example of such a rapid cooling method, there is a method using quenching. The quenching cooling method is generally a method in which the steel sheet can be cooled at a cooling rate of, for example, 1000 占 폚 per 1 mm of the steel sheet.

상기 담금질 냉각공정에서는 냉각수가 저장된 담금질 냉각조를 이용하게 된다.In the quenching and cooling process, a quenching cooling tank in which cooling water is stored is used.

상기 냉각조는 냉각수를 일정한 온도로 유지하기 위한 냉각기와 냉각속도를 높이기 위한 제트 분사 장치를 포함할 수 있다. 이와 같이 강 스트립이 급냉장치인 냉각조를 통과하면서 요구되는 정도의 냉각이 이루어지는 것이다. The cooling bath may include a cooler for maintaining the cooling water at a constant temperature and a jet injector for increasing the cooling rate. As such, the steel strip passes through a cooling bath, which is a quenching device, to achieve a desired degree of cooling.

하지만, 기존의 담금질 냉각장치로 고온의 강판을 담금질하면 강판의 형상이 나빠지는 문제가 있다. However, there is a problem that when the high-temperature steel sheet is quenched by the existing quenching-cooling apparatus, the shape of the steel sheet is deteriorated.

예컨대, 가열대에서 강판은 800℃이상 고온 상태가 되며, 이를 담금질하면 1초만에 상온으로 빠르게 냉각되면서 강판에 길이방향, 폭방향 온도차가 크게 발생하고 따라서 열응력이 크게 발생하여 강판이 변형하게 된다. For example, in a heating zone, a steel sheet is heated to a temperature of 800 ° C or higher. When the steel sheet is quenched, the steel sheet rapidly cools to room temperature within one second, resulting in a large temperature difference in the longitudinal direction and the width direction.

이러한 문제를 해결하여 담금질 공정에서 평탄한 강판 확보를 위해 강판의 장력을 증가시키거나, 냉각수의 수온을 조절하거나, 담금질 시작 시점에서 강판의 온도를 낮추고 페라이트 변태를 방지하기 위해 합금 성분을 추가하는 등의 다양한 방안들이 제시되어 왔다. To solve this problem, it is necessary to increase the tensile strength of the steel sheet in order to obtain a flat steel sheet in the quenching process, to adjust the water temperature of the cooling water, to lower the temperature of the steel sheet at the start of quenching and to add an alloy component to prevent ferrite transformation Various methods have been proposed.

그러나, 기존의 기술을 통해 고온의 강판을 담금질(급냉)하여 양호한 평탄도를 얻는 데에는 한계가 있다. However, there is a limit to obtaining a good flatness by quenching (quenching) a steel sheet at a high temperature through conventional techniques.

한편, 강판을 열처리하는 공정은 배치(Batch)타입과 연속 타입이 있는데, 강판을 코일 상태로 가열 및 냉각하는 배치 타입은 냉각속도가 느리며, 강판을 이동시키면서 가열 및 냉각하는 연속 타입은 열처리 설비가 큰 특징이 있다. On the other hand, there are a batch type and a continuous type in the process of heat treating the steel sheet, and the batch type in which the steel sheet is heated and cooled in the coil state has a slow cooling rate. In the continuous type in which the steel sheet is heated and cooled while moving, There are big features.

일반적으로, 상기 연속타입은 대량 생산에 유리하고, 배치타입은 연속타입에 비하여 소량 생산에 유리하다.
In general, the continuous type is advantageous for mass production, and the batch type is advantageous for small-scale production as compared with the continuous type.

본 발명의 바람직한 일 측면은 배치식으로 가열하고 연속식으로 냉각하여 형상 변형이 적은 마르텐사이트 함유 강판을 보다 경제적으로 제조하는 방법을 제공하고자 하는데, 그 목적이 있다.
A preferred aspect of the present invention is to provide a method for economically manufacturing a martensite-containing steel sheet in which the martensite-containing steel sheet is deformed in a batch manner by heating and cooling continuously to provide a more economical method.

본 발명의 바람직한 다른 일 측면은 배치식으로 가열하고 연속식으로 냉각하여 형상 변형이 적은 마르텐사이트 함유 강판을 보다 경제적으로 제조하는 장치를 제공하고자 하는데, 그 목적이 있다.
Another desirable aspect of the present invention is to provide a device for economically manufacturing a martensite-containing steel sheet which is heated batchwise and continuously cooled to reduce the shape deformation.

본 발명의 바람직한 일 측면은 수냉 시 오스테나이트의 적어도 일부가 마르텐사이트로 변태되는 강판을 코일 형태로 준비하는 단계;A preferred aspect of the present invention is a method for manufacturing a steel sheet, comprising: preparing a steel sheet in the form of a coil in which at least a portion of austenite is transformed into martensite under water cooling;

상기 강판 코일을 강판의 미세조직의 적어도 일부가 오스테나이트가 되도록 가열하는 단계; 및 Heating the steel coil so that at least a part of the microstructure of the steel sheet becomes austenite; And

상기와 같이 가열된 강판 코일을 풀어 300mpm이상의 이송속도로 강판을 이송시키면서 500℃/sec 이상의 냉각속도로 수냉하여 상기 오스테나이트의 적어도 일부를 마르텐사이트로 변태시키는 단계를 포함하는 마르텐사이트 함유 강판의 제조방법에 관한 것이다.
And cooling the steel sheet coil at a cooling rate of 500 DEG C / sec or more while transferring the steel sheet at a conveying speed of 300 mpm or more by loosening the heated steel sheet coil to transform at least a part of the austenite into martensite. ≪ / RTI >

상기 수냉 시 수냉종료온도는 Ms(마르텐사이트 변태개시온도)이하 150℃이상이 바람직하다.
The water-cooling termination temperature in water-cooling is preferably 150 ° C or higher, which is Ms (martensitic transformation start temperature) or lower.

본 발명의 바람직한 다른 일 측면은 강판을 코일 형태로 가열하는 가열로; 가열된 코일을 풀어주는 페이오프릴; 코일로부터 풀려 이송되는 가열된 강판을 냉각하는 냉각장치; 및 냉각된 강판을 감는 코일러를 포함하는 마르텐사이트 함유 강판의 제조장치에 관한 것이다.
Another preferred aspect of the present invention is a heating furnace for heating a steel sheet in the form of a coil; Phage prills releasing the heated coil; A cooling device for cooling a heated steel sheet unreeled from the coil; And a coil for winding a cooled steel sheet.

상기 냉각장치는 강판의 냉각 시 500℃/sec 이상의 냉각속도를 부여하도록 구성될 수 있다.
The cooling device may be configured to give a cooling rate of 500 DEG C / sec or more when cooling the steel sheet.

상기 냉각장치는 가열된 강판을 냉각하는 냉각액이 저장된 냉각조 및 상기 냉각액을 상기 강 스트립을 향해 제트 분사하도록 구비되는 냉각대를 포함할 수 있다.
The cooling device may include a cooling bath in which a cooling liquid for cooling the heated steel plate is stored, and a cooling pad for jetting the cooling liquid toward the steel strip.

상기 페이오프릴과 냉각장치 사이와 냉각장치와 코일러 사이에, 강판을 안내하는 안내롤러를 포함할 수 있다.
And a guide roller for guiding the steel sheet between the phage prill and the cooling device, and between the cooling device and the coil.

본 발명의 바람직한 일 측면에 따르면, 설비 크기를 줄이면서 마트강 제조에 필요한 냉각속도를 만족하여 설비 비용을 최소화할 수 있을 뿐만 아니라 가열과 냉각을 분리함으로써 냉각 공정에서 강 스트립의 이송속도를 높여 500℃/sec 이상의 빠른 냉각에서도 강 스트립의 길이방향 온도구배 변화를 최소화하여 열응력을 감소시켜 강 스트립의 형상 변형을 최소화할 수 있다.
According to a preferred aspect of the present invention, it is possible to minimize the facility cost by satisfying the cooling rate necessary for manufacturing the mart steel while reducing the size of the equipment, and by separating the heating and cooling, the feeding speed of the steel strip in the cooling process is increased to 500 Even in the case of rapid cooling above 캜 / sec, the change in the longitudinal temperature gradient of the steel strip is minimized, thereby reducing the thermal stress and minimizing the shape deformation of the steel strip.

도 1은 본 발명에 부합되는 마르텐사이트 함유 강판의 제조장치의 일례를 나타내는 개략도1 is a schematic view showing an example of an apparatus for producing a martensitic steel sheet according to the present invention

본 발명은 설비 투자와 운영 측면에서 효율적일 뿐만 아니라 강판의 급속 냉각시 강판의 길이 방향 열응력의 집중을 분산하여 최소화함으로써 강 스트립의 형상 변형을 최소화하는 마르텐사이트 함유 강판의 제조방법 및 장치를 제공한다.
The present invention provides a method and an apparatus for manufacturing a martensite-containing steel sheet that is effective not only in facility investment and operation but also minimizes the shape deformation of the steel strip by dispersing and minimizing concentration of longitudinal thermal stress of the steel sheet during rapid cooling of the steel sheet .

본 발명의 바람직한 일 측면에 따라 마르텐사이트 함유 강판을 제조하기 위해서는수냉 시 오스테나이트의 적어도 일부가 마르텐사이트로 변태되는 강판을 코일 형태로 준비한다.
According to a preferred aspect of the present invention, in order to produce a martensite-containing steel sheet, a steel sheet in which at least a part of austenite is transformed into martensite under water cooling is prepared in the form of a coil.

상기 강판으로는 가열시 미세조직의 적어도 일부가 오스테나이트가 되고, 수냉 시 오스테나이트의 적어도 일부가 마르텐사이트로 변태되는 강판으로 충분하고, 특별히 한정되는 것은 아니다.
As the steel sheet, at least a part of the microstructure becomes austenite upon heating, and a steel sheet in which at least a part of austenite is transformed into martensite at the time of water cooling is sufficient, and is not particularly limited.

본 발명에 바람직하게 적용될 수 있는 강판은 마르텐사이트 강판, 듀얼페이즈 강판 및 콤플렉스페이즈 강판 등을 들 수 있다. The steel sheet which can be preferably applied to the present invention includes a martensitic steel sheet, a dual phase steel sheet and a complex phase steel sheet.

강판의 일례는 탄소: 0.05~0.4중량%, 규소: 2중량% 이하, 망간: 1~3 중량%, 인: 0.05중량% 이하, 황: 0.02 중량%이하, 잔부 Fe 및 기타 불순물을 포함하는 강판일 수 있다.
Examples of the steel sheet include a steel sheet containing 0.05 to 0.4% by weight of carbon, 2% by weight or less of silicon, 1 to 3% by weight of manganese, 0.05% by weight or less of phosphorus and 0.02% Lt; / RTI >

상기 강판은 특별히 한정되는 것은 아니지만, 예를 들면, 열연강판 또는 냉연강판일 수 있다.
The steel sheet is not particularly limited, but may be, for example, a hot-rolled steel sheet or a cold-rolled steel sheet.

다음에, 상기와 같이 준비된 강판 코일을 강판의 미세조직의 적어도 일부가 오스테나이트가 되도록 가열한다.
Next, the steel sheet coil prepared as described above is heated so that at least a part of the microstructure of the steel sheet becomes austenite.

상기 강판의 가열조건은 제조하고자 하는 강판에 따라 적절히 제어될 수 있다.The heating conditions of the steel sheet can be appropriately controlled according to the steel sheet to be produced.

예를 들면, 미세조직의 전부를 마르텐사이트로 변태시키기 위해서는 강판의 미세조직이 전부 오스테나이트가 되도록 가열하면 된다.
For example, in order to transform the entire microstructure into martensite, it is sufficient to heat the microstructure of the steel sheet so that all of the microstructure becomes austenite.

강판을 가열하는 경우, 가열온도는 700~900℃, 가열분위기는 환원성 분위기가 바람직하다. 상기 환원성 분위기로 질소 90~98부피%, 수소 2~10부피%일 수 있다. 가열방식은 특별히 한정되는 것은 아니며, 예를 들면, 복사가열로, 라디언트 튜브나 머플타입 가열로 방식을 들 수 있다.When the steel sheet is heated, the heating temperature is preferably 700 to 900 占 폚, and the heating atmosphere is preferably a reducing atmosphere. The reducing atmosphere may be 90 to 98% by volume of nitrogen and 2 to 10% by volume of hydrogen . The heating method is not particularly limited, and examples thereof include radiant heating, radiant tube and muffle type heating furnace.

가열시간은 예를 들면, 코일 폭 600~1400㎜일 경우 20~80시간일 수 있다.
The heating time may be 20 to 80 hours, for example, when the coil width is 600 to 1400 mm.

상기와 같이 가열된 강판 코일을 풀어 300mpm이상의 이송속도로 강판을 이송시키면서 500℃/sec 이상의 냉각속도로 수냉하여 상기 오스테나이트의 적어도 일부를 마르텐사이트로 변태시켜 마르텐사이트 함유 강판을 제조한다.
The steel sheet coil thus heated is unwound, and water is cooled at a cooling rate of 500 DEG C / sec or more while feeding the steel sheet at a feeding speed of 300 mpm or more to transform at least a part of the austenite into martensite to produce a martensite-containing steel sheet.

강판의 이송속도가 300mpm 미만인 경우에는 온도구배와 열응력 감소가 기존 연속소둔방법 대비 불충분하여 형상 개선 효과가 작은 문제가 있다.When the steel sheet has a conveying speed of less than 300 mpm, there is a problem that the temperature gradient and the reduction of the thermal stress are insufficient compared to the conventional continuous annealing method and the effect of improving the shape is small.

강판의 이송속도는 빠를수록 좋지만, 너무 빠른 경우에는 사행제어 및 설비 관리 어려움이 있을 수 있으므로, 그 상한은 800mpm으로 한정하는 것이 바람직하다.The higher the feed rate of the steel sheet is, the faster it is. However, if the steel sheet is too fast, it may be difficult to control the slewing and facilities. Therefore, the upper limit is preferably limited to 800 mpm.

보다 바람직한 강판의 이송속도는 400 ~ 600mpm이다.
More preferably, the feed rate of the steel sheet is 400 to 600 mpm.

상기 강판의 냉각속도가 500℃/sec미만인 경우에는 막비등 영역에서 냉각 편차가 증가하여 강판 형상이 나빠지는 문제가 있다.When the cooling rate of the steel sheet is less than 500 deg. C / sec, there is a problem that the cooling deviation increases in the film burning area and the shape of the steel sheet deteriorates.

한편, 냉각속도가 너무 빠른 경우에는 온도구배와 열응력이 증가하여 강판 형상이 나빠지는 문제가 있을 수 있으므로, 그 상한은 2000℃/sec로 한정하는 것이 바람직하다. 보다 바람직한 강판의 냉각속도는 500~1500℃/sec이다. 가장 바람직한 강판의 냉각속도는 800~1200℃/sec이다.
On the other hand, if the cooling rate is too high, the temperature gradient and the thermal stress may be increased to deteriorate the shape of the steel sheet. Therefore, the upper limit is preferably limited to 2000 ° C / sec. The cooling rate of the steel sheet is more preferably 500 to 1500 DEG C / sec. The most preferable cooling rate of the steel sheet is 800 to 1200 DEG C / sec.

상기 수냉 시 수냉종료온도는 Ms(마르텐사이트 변태개시온도)이하라면, 특별히 한정되는 것은 아니며, 예를 들면 상온일 수 있다.The water-cooling termination temperature in water-cooling is not particularly limited as long as it is not higher than Ms (martensitic transformation start temperature), and may be, for example, room temperature.

셀프 템퍼링을 목적으로 하는 경우에는 상기 수냉 시 수냉종료온도는 Ms(마르텐사이트 변태개시온도)이하 150℃이상이 바람직하다.In the case of self-tempering, it is preferable that the water-cooling end temperature in water-cooling is 150 deg. C or lower which is Ms (martensitic transformation start temperature) or lower.

상기와 같이, 수냉 시 수냉종료온도를 Ms이하, 150℃이상으로 하면, 셀프 템퍼링 되어 별도의 템퍼링 공정 없이 연신율을 향상시키고 강 스트립 표면의 잔류수를 증발시켜 스케일 형성을 방지할 수 있다.
As described above, if the water-cooling termination temperature in water-cooling is Ms or less and 150 占 폚 or more, self-tempering can be performed to improve elongation without additional tempering process and evaporate residual water on the surface of the steel strip to prevent scale formation.

이하, 본 발명에 부합되는 마르텐사이트 함유 강판의 제조장치의 일례를 도 1을 참조하여 설명한다.Hereinafter, an example of an apparatus for producing a martensite-containing steel sheet according to the present invention will be described with reference to Fig.

도 1에 나타난 바와 같이, 본 발명에 부합되는 마르텐사이트 함유 강판의 제조장치(100)은 강판을 코일(10)형태로 가열하는 가열로(1); 가열된 코일(10)을 풀어주는 페이오프릴(2); 코일로부터 풀려 이송되는 가열된 강판을 냉각하는 냉각장치(3); 및 냉각된 강판을 감는 코일러(4)를 포함한다.1, an apparatus 100 for producing a martensite-containing steel sheet according to the present invention comprises a heating furnace 1 for heating a steel sheet in the form of a coil 10; A phage prill 2 for releasing the heated coil 10; A cooling device (3) for cooling a heated steel sheet unloaded from the coil; And a coil 4 for winding the cooled steel sheet.

상기 냉각장치(300)는 가열된 강판을 냉각하는 냉각액이 저장된 냉각조(31) 및 상기 냉각액을 상기 강 스트립을 향해 제트 분사하도록 구비되는 냉각대(32)를 포함할 수 있다.The cooling device 300 may include a cooling bath 31 in which a cooling liquid for cooling a heated steel plate is stored and a cooling base 32 for jetting the cooling liquid toward the steel strip.

상기 냉각장치(3)는 강판의 냉각 시 500℃/sec 이상의 냉각속도를 부여하도록 구성될 수 있다.
The cooling device 3 may be configured to give a cooling rate of 500 DEG C / sec or more when cooling the steel sheet.

상기 페이오프릴(2)과 냉각장치(3) 사이와 냉각장치(2)와 코일러(4) 사이에, 강판을 안내하는 안내롤러(5a),(5b)를 포함할 수 있다.
And guide rollers 5a and 5b for guiding the steel sheet between the phage prill 2 and the cooling device 3 and between the cooling device 2 and the coiler 4. [

도 1에서, 미설명부호 6은 이송대차를 나타내고, 11은 가열로 도어를 나타내고, 33은 냉각조 롤러를 나타낸다.
In Fig. 1, reference numeral 6 denotes a conveyance truck, 11 denotes a heating-roller door, and 33 denotes a cooling roller.

도 1의 마르텐사이트 함유 강판의 제조장치(100)를 사용하여 마르텐사이트 함유 강판을 제조하는 방법에 대하여 설명한다.A method for producing a martensite-containing steel sheet using the apparatus 100 for producing a martensite-containing steel sheet of Fig. 1 will be described.

우선, 가열할 강판 코일(10)을 이송 대차(6)에 크레인 등으로 올려 놓는다.  First, a steel plate coil 10 to be heated is placed on a conveying platform 6 with a crane or the like.

코일을 실은 이송대차(6)가 가열로(1)로 이동한다. 코일(10)을 페이오프릴(2)에 끼우면 이송대차(6)는 가열로(1) 밖으로 나온다. The conveyance truck 6 carrying the coil moves to the heating furnace 1. When the coil 10 is inserted into the printer pulley 2, the conveyance truck 6 comes out of the heating furnace 1.

이후 강판을 안내 롤러(5a), 냉각조 롤러(33), 안내롤러(5b), 코일러(4) 까지 연결한다. 또는, 이미 연결된 강판에 페이오프릴(2)에 새로 끼운 코일(10)의 강판을 용접하여 연결한다. Thereafter, the steel plate is connected to the guide roller 5a, the cooling roller 33, the guide roller 5b and the coil 4. Alternatively, the steel plate of the newly-installed coil 10 is welded to the already connected steel plate and connected to the phage prill 2.

이후, 가열로 도어(11)를 닫고 코일(10)을 가열한다. Thereafter, the heating furnace door 11 is closed and the coil 10 is heated.

예를 들면 가열온도는 700~900℃이며, 내부는 환원성 분위기로 질소 90~98부피%, 수소 2~10부피%일 수 있다.For example, the heating temperature is 700 to 900 占 폚, and the inside can be 90 to 98% by volume of nitrogen and 2 to 10% by volume of hydrogen in a reducing atmosphere.

가열로(1)는 특별히 한정되는 것은 아니며, 복사가열로 라디언트 튜브나 머플타입 가열로 등이 사용될 수 있다.The heating furnace 1 is not particularly limited, and a radiant tube or a muffle type heating furnace can be used as the radiant heating.

가열시간은 코일 폭 600~1400㎜일 경우 20~80시간이다.
The heating time is 20 to 80 hours when the coil width is 600 to 1400 mm.

코일 내부까지 필요한 온도에 도달하면 페이오프릴(2)과 코일러(4)를 가동하여 강 판이 냉각장치(3)의 냉각조(31)를 지나도록 한다. 냉각조(31)는 냉각을 위한 냉매로 물이 채워져 있다. 또한 냉각조 안에 강 스트립 전/후면에 냉매를 분사하는 냉각대(32)가 구비되어 있어 500℃/sec 이상의 속도로 강판을 냉각한다. When the necessary temperature is reached up to the inside of the coil, the phage prill 2 and the coil 4 are operated so that the steel plate passes through the cooling bath 31 of the cooling device 3. The cooling bath 31 is filled with water as cooling medium for cooling. Further, a cooling base 32 for spraying a coolant on the front and rear surfaces of the steel strip is provided in the cooling bath to cool the steel plate at a rate of 500 ° C / sec or more.

냉각 시에 강판의 이송속도는 통상의 연속소둔공정 이송속도 200mpm보다 1.5배 빠른 300mpm이상, 바람직하게는 2~3배 빠른 400~600mpm이다. The conveying speed of the steel sheet during cooling is 400 to 600 mpm, which is more than 300 mpm, preferably 2 to 3 times faster than the normal continuous annealing process conveying speed of 1.5 to 1.5 times faster than 200 mpm.

이를 통해 통상의 연속열처리공정에서는 예를 들면, 담금질 급냉시 강 스트립 온도구배가 300℃/meter 이나 본 발명에서는 150~100℃/meter로 감소하여, 열응력도 감소한다. 수치해석 결과 속도가 2배 증가시 열응력은 1/3로 감소한다. 따라서 냉각속도가 통상의 연속소둔 담금질공정에서 냉각속도 1000℃/sec과 동일함에도 강판 형상이 양호할 수 있다. 한편, 냉각시 강 스트립 이송속도가 빠르므로 코일 전체를 냉각하는데 걸리는 시간은 약 4분 정도로 짧다.
As a result, in a conventional continuous heat treatment process, for example, the steel strip temperature gradient during quenching and quenching is reduced to 300 ° C / meter, but in the present invention, 150 ° C to 100 ° C / meter. Numerical results show that the thermal stress decreases by one-third when the speed is doubled. Therefore, the steel sheet shape can be good even though the cooling rate is the same as the cooling rate of 1000 DEG C / sec in the ordinary continuous annealing for quenching process. On the other hand, since the steel strip feeding speed is fast during cooling, the time taken to cool the entire coil is as short as about 4 minutes.

1: 가열로, 2: 페이오프릴, 3: 냉각장치, 4: 코일러, 5(a),5(b): 안내롤러, 31: 냉각조, 32: 냉각대1: heating furnace 2: phage prill 3: cooling device 4: coiler 5 (a) 5 (b): guide roller 31: cooling bath 32:

Claims (11)

수냉 시 오스테나이트의 적어도 일부가 마르텐사이트로 변태되는 강판을 코일 형태로 준비하는 단계;
상기 강판 코일을 강판의 미세조직의 적어도 일부가 오스테나이트가 되도록 가열하는 단계; 및
상기와 같이 가열된 강판 코일을 풀어 300mpm이상의 이송속도로 강판을 이송시키면서 500℃/sec 이상의 냉각속도로 수냉하여 상기 오스테나이트의 적어도 일부를 마르텐사이트로 변태시키는 단계를 포함하는 마르텐사이트 함유 강판의 제조방법.
Preparing a steel sheet in the form of a coil in which at least a part of austenite is transformed into martensite during water cooling;
Heating the steel coil so that at least a part of the microstructure of the steel sheet becomes austenite; And
And cooling the steel sheet coil at a cooling rate of 500 DEG C / sec or more while transferring the steel sheet at a conveying speed of 300 mpm or more by loosening the heated steel sheet coil to transform at least a part of the austenite into martensite. Way.
제1항에 있어서, 상기 강판의 이송속도는 300 ~800mpm인 것을 특징으로 하는 마르텐사이트 함유 강판의 제조방법.
The method for producing a martensite-containing steel sheet according to claim 1, wherein the steel sheet has a conveying speed of 300 to 800 mpm.
제1항 또는 제2항에 있어서, 상기 수냉 시 수냉종료온도는 Ms(마르텐사이트 변태개시온도)이하인 것을 특징으로 하는 마르텐사이트 함유 강판의 제조방법.
The method for producing a martensite-containing steel sheet according to claim 1 or 2, wherein the water-cooling termination temperature during water cooling is Ms (martensitic transformation start temperature) or lower.
제1항 또는 제2항에 있어서, 상기 수냉 시 수냉종료온도는 Ms(마르텐사이트 변태개시온도)이하 150℃이상인 것을 특징으로 하는 마르텐사이트 함유 강판의 제조방법.
The method for producing a martensite-containing steel sheet according to claim 1 or 2, wherein the water-cooling termination temperature during water cooling is 150 ° C or higher, which is Ms (martensitic transformation start temperature) or lower.
제1항에 있어서, 상기 강판의 냉각속도는 800 ~ 1200℃/sec인 것을 특징으로 하는 마르텐사이트 함유 강판의 제조방법.
The method for producing a martensite-containing steel sheet according to claim 1, wherein the cooling rate of the steel sheet is 800 to 1200 ° C / sec.
제1항에 있어서, 상기 강판은 마르텐사이트 강판, 듀얼페이즈 강판 및 콤플렉스페이즈 강판 중 어느 하나인 것을 특징으로 하는 마르텐사이트 함유 강판의 제조방법.
The method for producing a martensite-containing steel sheet according to claim 1, wherein the steel sheet is one of a martensite steel sheet, a dual phase steel sheet and a complex phase steel sheet.
제1항에 있어서, 상기 강판은 탄소: 0.05~0.4중량%, 규소: 2중량% 이하, 망간: 1~3 중량%, 인: 0.05중량% 이하, 황: 0.02 중량%이하, 잔부 Fe 및 기타 불순물을 포함하는 것임을 특징으로 하는 마르텐사이트 함유 강판의 제조방법.
The steel sheet according to claim 1, wherein the steel sheet comprises 0.05 to 0.4% by weight of carbon, 2 to 3% by weight of silicon, 1 to 3% by weight of manganese, 0.05% Wherein the martensite-containing steel sheet contains impurities.
강판을 코일 형태로 가열하는 가열로; 가열된 코일을 풀어주는 페이오프릴; 코일로부터 풀려 이송되는 가열된 강판을 냉각하는 냉각장치; 및 냉각된 강판을 감는 코일러를 포함하는 마르텐사이트 함유 강판의 제조장치.
A heating furnace for heating the steel plate in the form of a coil; Phage prills releasing the heated coil; A cooling device for cooling a heated steel sheet unreeled from the coil; And a coil for winding the cooled steel sheet.
제8항에 있어서, 상기 냉각장치는 강판의 냉각 시 500℃/sec 이상의 냉각속도를 부여하도록 구성되는 것을 특징으로 하는 마르텐사이트 함유 강판의 제조장치.
The apparatus for manufacturing a martensite-containing steel sheet according to claim 8, wherein the cooling device is configured to give a cooling rate of 500 ° C / sec or more during cooling of the steel sheet.
제8항에 있어서, 상기 냉각장치는 가열된 강판을 냉각하는 냉각액이 저장된 냉각조 및 상기 냉각액을 상기 강 스트립을 향해 제트 분사하도록 구비되는 냉각대를 포함하는 것을 특징으로 하는 마르텐사이트 함유 강판의 제조장치.
9. The martensite-containing steel sheet according to claim 8, wherein the cooling device comprises a cooling bath in which a cooling liquid for cooling a heated steel sheet is stored, and a cooling belt for jetting the cooling liquid toward the steel strip Device.
제8항에 있어서, 상기 페이오프릴과 냉각장치 사이와 냉각장치와 코일러 사이에, 강판을 안내하는 안내롤러가 구비되어 있는 것을 특징으로 하는 마르텐사이트 함유 강판의 제조장치.The apparatus for manufacturing a martensite-containing steel sheet according to claim 8, wherein a guide roller for guiding the steel sheet is provided between the phage prill and the cooling device, and between the cooling device and the coil.
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