WO2013095005A1 - Non-magnetic high manganese steel sheet with high strength and manufacturing method thereof - Google Patents

Non-magnetic high manganese steel sheet with high strength and manufacturing method thereof Download PDF

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Publication number
WO2013095005A1
WO2013095005A1 PCT/KR2012/011168 KR2012011168W WO2013095005A1 WO 2013095005 A1 WO2013095005 A1 WO 2013095005A1 KR 2012011168 W KR2012011168 W KR 2012011168W WO 2013095005 A1 WO2013095005 A1 WO 2013095005A1
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WIPO (PCT)
Prior art keywords
steel sheet
less
high strength
manganese steel
magnetic
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PCT/KR2012/011168
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French (fr)
Korean (ko)
Inventor
김성규
진광근
오필용
황현규
Original Assignee
주식회사 포스코
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Priority claimed from KR1020110141738A external-priority patent/KR20130073736A/en
Priority claimed from KR1020110142433A external-priority patent/KR20130074384A/en
Application filed by 주식회사 포스코 filed Critical 주식회사 포스코
Priority to JP2014548662A priority Critical patent/JP6002779B2/en
Priority to CN201280064011.5A priority patent/CN104011248B/en
Priority to US14/367,480 priority patent/US20150211088A1/en
Priority to EP12859366.2A priority patent/EP2796585B1/en
Publication of WO2013095005A1 publication Critical patent/WO2013095005A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium

Definitions

  • the present invention relates to a high-strength high manganese steel sheet having nonmagnetic properties that can be used for an electric power generator such as a switchboard and a transformer.
  • Ferritic or martensitic stainless steel may be used to increase the strength, but since the ferritic or martensitic stainless steel has high magnetic properties, not only does power loss due to eddy currents occur, but the price is very expensive. have.
  • One aspect of the present invention is to provide a high-strength high manganese steel sheet and a method for manufacturing the same having excellent strength and formability, as well as excellent nonmagnetic properties.
  • the austenitic stability is increased to secure nonmagnetic properties, and A1 or the like is added to prevent carbon from forming carbides, thereby providing a high manganese steel which makes austenite more stable. It has the advantage of excellent moldability. Thus, it provides sufficient rigidity for use as structural members such as large transformers.
  • Figure 1 (a) is a photograph of observing the microstructure of Inventive Example 1-7 and (b) Comparative Example 1-4.
  • 2 (a) and 2 (b) are XRD graphs measuring the degree of image stability of Inventive Steel 2-1 and Comparative Steel 2-1, respectively.
  • FIG. 3 are photographs of the microstructures of the inventive steels 2-1 and Comparative steels 2-1, respectively. Best Mode for Implementation of the Invention
  • the loss due to the eddy currents of the material exposed to the electromagnetic field is closely related to the magnetism of the material.
  • magnetism is proportional to permeability ( ⁇ ).
  • the present inventors have studied in depth, and in order to have high strength and nonmagnetic properties, the inventors have invented high manganese steel having high austenite stability by adding manganese (Mn) and carbon (C) to steel.
  • Mn manganese
  • C carbon
  • the austenite phase stability is increased, and the addition of aluminium suppresses the slip deformation due to the formation and dislocation of ⁇ -martensite during deformation, thereby providing excellent strength and elongation (formability).
  • the present invention will be described in detail.
  • the steel sheet of the present invention satisfies the following composition (hereinafter increased%) Carbon (C): 0.4-0.9%
  • Mn Manganese
  • Mn is an important element that plays a role in stabilizing austenite tissue and contains 10% or more in the present invention. If it is less than 10%, ⁇ '-martensite phase is present, and the nonmagnetic property is deteriorated. If it is more than 25%, manufacturing atoms are greatly increased. There is a problem of deterioration. Therefore, the content of Mn is preferably 10-25%.
  • the A1 is an element effective to prevent the formation of carbides, and improves formability by adjusting the fraction of twins.
  • carbon is contained in an amount of 0.01% or more because it acts as an important element to prevent carbide formation in order to stabilize the austenite and improve nonmagnetic properties.
  • it exceeds 8.03 ⁇ 4 the manufacturing cost increases, and the surface quality of the product is lowered due to the formation of excessive ⁇ oxide, so that the content is preferably 0.01-8.0%.
  • the Si is an element that does not significantly affect the lamination defect energy, and is usually used as a deoxidizer or contained in a general steelmaking process, and if it is to be removed, it contains 0.01% because excessive cost occurs, If the content exceeds 2.0%, the manufacturing cost increases, and the surface quality of the product is reduced due to the formation of excessive oxide, the content is preferably 0.01-2.0%. Titanium (Ti): 0.05-0.2%
  • the Ti is added to ensure strength and formability as a component that reacts with nitrogen inside the steel to precipitate nitride and form twins.
  • the Ti forms a precipitated phase to increase the strength.
  • Ti is small to wind contained 0.05% or more, but if it exceeds 0 .23 ⁇ 4 are formed to precipitate the excess can be a micro-cracks formed during cold rolling, can lead to deterioration of the formability and weldability. Therefore, the content of Ti is preferably 0.05 to 0.2%.
  • the S needs to be controlled to 0.05% or less for the control of inclusions.
  • the upper limit thereof is preferably 0.05%.
  • P is an element that segregation easily occurs to promote cracking during casting. In order to prevent this, it is preferable to control to 0.8% or less. If the content of P exceeds 0.8%, castability may deteriorate, so the upper limit is 0.8%. desirable .
  • N is an element which is indispensably added to the atmosphere during the steelmaking process. Reducing the N to less than 0.003% is an excessive cost in the process, when the content is more than 0.01% because it forms a nitride to lower the formability, it is not preferable. Therefore, the content of N is preferably 0.003-0.01%. The remainder contains Fe and inevitable impurities.
  • carbides are contained in the microstructure of 1% by volume or less.
  • carbon must be dissolved in an atomic state, thereby securing austenite stability. In other words, when carbon is present in steel in the form of carbides, the austenite has low stability, high permeability, and inferior magnetic properties.
  • the number of steels and carbides is as small as possible, and it is desirable to form one volume 3 ⁇ 4 or less.
  • the carbide is preferably included in less than 1% by volume even after the heat treatment.
  • the heat treatment includes not only heat treatment existing in the manufacturing process of the steel sheet, but also heat treatment performed in the process of using the steel pipe.
  • the steel sheet of the present invention has an austenite structure, in order to maintain the austenite structure in order to maintain nonmagnetic in external energy such as heat treatment. Therefore, the steel sheet of the present invention has an austenite structure, and it is preferable that carbides are formed in part (1% by volume or less) depending on the heat treatment conditions.
  • the stacking fault energy (SFE) value is preferably 30 mJ / ciif or more.
  • the lamination defect energy is an energy of an interface between partial potentials formed in the material, and in the present invention, by controlling the content of A1, the lamination defect is controlled, thereby improving the phase stability of the austenite phase. If the stacking defect energy has an appropriate value, the potential and twin are in harmony, and thus the phase stability increases, but if it becomes too low, the potential cannot be generated or moved, and the phase stability decreases. Robbery is done. Therefore, in the present invention, the optimum stacking defect energy is derived to obtain phase stability with moderate strength.
  • the lamination defect energy value is preferably 30 mJ / cuf or more.
  • the method of measuring the stacking defect energy is various, such as X-ray measurement method, transmission electron microscope measurement method, thermodynamic calculation method, etc., thermodynamic calculation method using the thermodynamic data that reflects the influence of the components well, and easy to measure is most preferred.
  • the steel sheet of the present invention has a tensile strength of 800MPa or more, and by securing an elongation of 15% or more, it is desirable to have excellent strength and workability.
  • the heating temperature is too low, it is preferable to heat at a temperature of 1100 ° C. or more because the rolling load may be excessively taken during hot rolling. The higher the degree of heating, the easier the hot rolling. However, the steel with a high content of Mn may cause severe oxidation inside the high-temperature heating yarn, which may lower the surface quality. Therefore, the upper limit of the reheating temperature is preferably 1250 o C. .
  • the hot finish rolling temperature is also easy to roll due to the low deformation resistance at higher temperature, but the higher the rolling degree, the lower the surface quality. Therefore, the temperature is preferably lower than 1000 o C.
  • the temperature is too low. Since it becomes large, it is preferable to carry out at 800 ° C or more.
  • After the hot rolling is subjected to the step of winding. It is preferable to perform the said coiling at 400-700 degreeC .
  • the cooling rate after the said winding is usually slow. If the coiling start temperature is too low, a large amount of cooling water is required for deflection, and the coiling load acts largely so that the coiling start temperature is 400 o C or more.
  • the coiling temperature is preferably 700 ° C. or lower.
  • the hot rolled steel sheet prepared as described above is cold rolled to prepare a molten steel sheet.
  • the rolling reduction during inter rolling is generally determined according to the required thickness of the product.
  • the recrystallization proceeds during the heat treatment after the inter rolling, it is necessary to control the driving force of the recrystallization well. In other words, if the reduction ratio during rolling is too low, the strength of the product is lowered. Therefore, the reduction of the product is performed at a reduction ratio of 30% or more. It is preferable to carry out at a reduction ratio of 60% or less.
  • continuous annealing is performed.
  • the continuous annealing is preferably carried out at 650 ⁇ 900 ° C.
  • Continuous annealing is performed at temperatures above 650 o C where recrystallization occurs It is preferable, but if the annealing temperature is too high, an oxide is formed on the surface, and the peelability with the front / rear connection products which are continuously worked is reduced, so it is preferable to carry out at 900 ° C. or less.
  • VSM records the applied magnetic field applied by the Hall probe, and the magnetization value of the sample is measured by recording the electromotive force obtained when vibrating the sample by Faraday's law. do.
  • VSM is a method of measuring the magnetization value of a sample by detecting the induced electromotive force in the search coil by applying the vibration to the sample by this basic operation and principle.
  • the magnetic properties of the material can be measured simply as a function of magnetic field, temperature and time.
  • the fraction of carbide in the present invention is very small, in the comparative example outside the scope of the present invention it can be seen that the nonmagnetic properties inferior to the fraction of the carbide exceeds 1% by volume. Therefore, it can be seen that excellent nonmagnetic properties can be ensured when the fraction of carbide becomes 1 volume 3 ⁇ 4 or less.
  • Hot finish rolling was performed at 900 ° C., wound at 500 ° C., and then hot-rolled at a rolling reduction rate of 50%, followed by continuous annealing at 800 ° C. to produce a mild steel sheet.
  • Yield strength (YS), tensile strength (TS) and elongation were measured for the ductile steel sheet, and the results are shown in Table 2.
  • SFE stacking fault energy
  • the lamination defect energy (SFE) is 30 mJ / m 2 or more, and the relative permeability is low. That is, it can be seen that excellent nonmagnetic properties can be secured, and that phase stability is high.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
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Abstract

The present invention relates to a non-magnetic high manganese steel sheet with high-strength, which ha superior strength and moldability, and at the same time, can obtain superior non-magnetic characteristics, and a method for manufacturing the same.

Description

【명세서】  【Specification】
【발명의 명칭】  [Name of invention]
비자성 고강도 고망간 강판 및 그 제조방법 Non-magnetic high strength high manganese steel sheet and manufacturing method
【기술분야】 Technical Field
본 발명은 배전반, 변압기 등의 증전기기에 사용될 수 있는 비자성특성을 갖는 고강도 고망간 강판에 관한 것이다. The present invention relates to a high-strength high manganese steel sheet having nonmagnetic properties that can be used for an electric power generator such as a switchboard and a transformer.
[배경기술】  Background Art
배전반， 변압기 등의 소재는 일반적으로 높은 강도와 함께， 우수한 비자성 특성을 필요로 한다. Materials such as switchboards and transformers generally require high strength and excellent nonmagnetic properties.
이러한 조건을 층족하기 위해서, 종래에는 니켈과 크름이 다량 첨가된 스테인리스강이 사용되어 왔다. 그러나， 상기 스테인리스강은 강도가 낮고 가격이 높다는 점이 문제가 있다. In order to satisfy these conditions, stainless steel with a large amount of nickel and cracks has been conventionally used. However, there is a problem that the stainless steel is low in strength and high in price.
강도를 높이기 위해서 페라이트계 또는 마르텐사이트계 스테인리스강이 적용될 수 있으나， 상기 페라이트계 또는 마르텐사이트계 스테인리스강은 높은 자성을 가지기 때문에， 와전류에 의한 전력손실이 발생할 뿐만 아니라， 가격이 매우 비싸다는 단점이 있다. Ferritic or martensitic stainless steel may be used to increase the strength, but since the ferritic or martensitic stainless steel has high magnetic properties, not only does power loss due to eddy currents occur, but the price is very expensive. have.
따라서, 스테인리스강이 갖는 한계를 극복하고， 높은 강도와 우수한 비장자성 특성을 갖는 소재에 대한 요구가 이어지고 있다. Accordingly, there is a demand for a material that overcomes the limitations of stainless steel and has high strength and excellent nonmagnetic properties.
【발명의 상세한 설명】  [Detailed Description of the Invention]
[기술적 과제] 본 발명의 일측면은 우수한 강도 및 성형성을 갖는 동시에， 우수한 비자성특성을 확보한 고강도 고망간 강판과 이를 제조하는 방법을 제공하고자 하는 것이다. 【기술적 해결방법】 [Technical Challenges] One aspect of the present invention is to provide a high-strength high manganese steel sheet and a method for manufacturing the same having excellent strength and formability, as well as excellent nonmagnetic properties. Technical Solution
【유리한 효과】 Advantageous Effects
본 발명에 의하면， 오스테나이트 안정도를 크게 하여 비자성을 확보하고， A1 등을 첨가하여 탄소가 탄화물 형성되는 것을 방지하여 오스테나이트를 더욱 안정하도톡 한 고망간강을 제공함으로서， 높은 강도를 가짐과 동시에 성형성이 우수한 장점이 있다. 따라서, 대형 변압기 등의 구조부재로 사용하기에 충분한 강성을 제공한다. According to the present invention, the austenitic stability is increased to secure nonmagnetic properties, and A1 or the like is added to prevent carbon from forming carbides, thereby providing a high manganese steel which makes austenite more stable. It has the advantage of excellent moldability. Thus, it provides sufficient rigidity for use as structural members such as large transformers.
【도면의 간단한 설명】  [Brief Description of Drawings]
도 1의 (a)는 발명예 1-7을 (b)는 비교예 1-4의 미세조직을 관찰한사진임. Figure 1 (a) is a photograph of observing the microstructure of Inventive Example 1-7 and (b) Comparative Example 1-4.
도 2의 (a)와 (b)는 각각 발명강 2-1과 비교강 2-1의 상안정도를 측정한 XRD 그래프임. 2 (a) and 2 (b) are XRD graphs measuring the degree of image stability of Inventive Steel 2-1 and Comparative Steel 2-1, respectively.
도 3의 (a)와 (b)는 각각 발명강 2—1과 비교강 2-1의 미세조직을 관찰한사진임. 【발명의 실시를 위한 최선의 형태] (A) and (b) of FIG. 3 are photographs of the microstructures of the inventive steels 2-1 and Comparative steels 2-1, respectively. Best Mode for Implementation of the Invention
전자기장에 노출되는 소재의 와전류에 의한 손실은 소재의 자성과 밀접한 관계가 있다. 자성이 클수록 와전류 발생이 커져 손실이 증가하게 된다. 일반적으로 자성은 투자율 (μ)에 비례한다. 즉, 투자율이 클수록 자성이 증가한다. 투자율은 자기화시키는 자기장 (Η)에 대한 유도자기장 (Β)의 비， 즉 μ=Β/Η의 식으로 정의된다. 다시 발해 투자율을 줄이면 소재의 자성이 감소하여 전기장에 노출된 경우 표면에 와전류 손실이 방지되므로 에너지 효율이 증가한다. 따라서， 배전반과 변압기 등의 소재는 자성이 없는 비자성 강판을 사용하는 것이 에너지 손실을 방지하는 유리하다 . 이에 본 발명자들은 깊이 연구한 결과, 고강도와 비자성 특성을 갖추기 위해서, 강 중에 망간 (Mn) 및 탄소 (C)를 첨가하여 오스테나이트 안정성을 높게한 고망간강을 발명하기에 이르게 되었다. 본 발명에서는 탄소 및 망간의 함량을 제어함으로써， 오스테나이트 상안정도를 높였고, 알루니늄을 첨가하여 변형 중 ε-마르텐사이트의 형성 및 전위로 인한 슬립 변형을 억제하여, 우수한 강도 및 연신율 (성형성) 뿐만 아니라， 우수한 비자성특성을 가질 수 있게 되었다. 이하， 본 발명에 대하여 상세히 설명한다. 먼저， 본발명의 강판에 대하여， 상세히 설명한다. 본 발명의 강판은 하기 조성을 만족한다 (이하, 증량 %) 탄소 (C): 0.4-0.9% The loss due to the eddy currents of the material exposed to the electromagnetic field is closely related to the magnetism of the material. The greater the magnetism, the greater the eddy current generation, resulting in increased losses. In general, magnetism is proportional to permeability (μ). In other words, the greater the permeability, the greater the magnetism. Permeability is defined as the ratio of the induced magnetic field (Β) to the magnetizing magnetic field (Η), ie μ = Β / Η. When the emission rate is reduced again, the magnetism of the material decreases, This prevents eddy current losses on the surface, increasing energy efficiency. Therefore, it is advantageous to use a nonmagnetic magnetic sheet for magnetic materials such as switchboards and transformers to prevent energy loss. Accordingly, the present inventors have studied in depth, and in order to have high strength and nonmagnetic properties, the inventors have invented high manganese steel having high austenite stability by adding manganese (Mn) and carbon (C) to steel. In the present invention, by controlling the content of carbon and manganese, the austenite phase stability is increased, and the addition of aluminium suppresses the slip deformation due to the formation and dislocation of ε-martensite during deformation, thereby providing excellent strength and elongation (formability). As well as excellent non-magnetic properties. Hereinafter, the present invention will be described in detail. First, the steel sheet of the present invention will be described in detail. The steel sheet of the present invention satisfies the following composition (hereinafter increased%) Carbon (C): 0.4-0.9%
C는 강 내의 오스테나이트 조직을 확보하는데 필요한 원소로서， 오스테나이트의 안정도를 층분하 확보하기 위해서， 0.4% 이상 첨가하는 것이 바람직하다. 그러나， C의 양이 0.9%를 초과하는 경우에는 탄화물이 과도하게 석출되어 오히려 비자성 특성이 저하될 뿐만 아니라， 주조성이 열화되는 문제가 있다. 따라서， 상기 C의 함량은 0.4~0.9%인 것이 바람직하다. 망간 (Mn): 10-25% Mn은 오스테나이트 조직을 안정화 시키는 역할을 하는 중요한 원소로 본 발명에서는 10% 이상 포함한다. 10% 미만에서는 α'-마르텐사이트상이 존재하게 되어 비자성특성이 저하되고, 25%를 초과하는 경우에는 제조원자가 크게 증가하고, 공정상 열간압연 단계에서 가열시 내부산화가 심하게 발생되어 표면품질이 저하되는 문제가 있다. 따라서, 상기 Mn의 함량은 10~25%인 것이 바람직하다. C is an element necessary for securing the austenite structure in the steel, and it is preferable to add 0.4% or more in order to secure the layer stability of the austenite. However, when the amount of C exceeds 0.9%, carbides are excessively precipitated, rather the nonmagnetic properties are lowered, and castability is deteriorated. Therefore, the content of C is preferably 0.4 to 0.9%. Manganese (Mn): 10-25% Mn is an important element that plays a role in stabilizing austenite tissue and contains 10% or more in the present invention. If it is less than 10%, α'-martensite phase is present, and the nonmagnetic property is deteriorated. If it is more than 25%, manufacturing atoms are greatly increased. There is a problem of deterioration. Therefore, the content of Mn is preferably 10-25%.
알루미늄 (A1): 0.01-8.0% Aluminum (A1): 0.01-8.0%
상기 A1은 탄화물이 형성되는 것을 방지하는데 효과적인 원소이고, 쌍정의 분율을 조절하여 성형성을 개선한다. 본 발명에서는 탄소가 고용되어 오스테나이트로 안정화시키기 위해 탄화물 형성을 방지하여 비자성특성을 향상시키는 중요한 원소로 작용하기 때문에 0.01% 이상 포함한다. 그러나， 8.0¾를 초과하는 경우에는 제조비용이 증가하고， 과도^ 산화물의 형성으로 제품의 표면품질이 저하되므로, 그 함량은 0.01-8.0%인 것이 바람직하다. The A1 is an element effective to prevent the formation of carbides, and improves formability by adjusting the fraction of twins. In the present invention, carbon is contained in an amount of 0.01% or more because it acts as an important element to prevent carbide formation in order to stabilize the austenite and improve nonmagnetic properties. However, if it exceeds 8.0¾, the manufacturing cost increases, and the surface quality of the product is lowered due to the formation of excessive ^ oxide, so that the content is preferably 0.01-8.0%.
실리콘 (Si): 0.01-2.0% Silicon (Si): 0.01-2.0%
상기 Si는 적층결함에너지에 크게 영향을 미치지 않는 원소이며， 통상 탈산제로 사용되거나, 일반 제강공정에서 정도 함유되며， 이를 제거하고자 하는 경우에는 과도한 비용이 발생하기 때문에 0.01%를 포함하며， 상기 Si의 함량이 2.0%를 초과하는 경우에는 제조비용이 증가하고， 과도한 산화물의 형성으로 제품의 표면품질이 저하되므로, 그 함량은 0.01-2.0%인 것이 바람직하다. 티타늄 (Ti): 0.05-0.2% The Si is an element that does not significantly affect the lamination defect energy, and is usually used as a deoxidizer or contained in a general steelmaking process, and if it is to be removed, it contains 0.01% because excessive cost occurs, If the content exceeds 2.0%, the manufacturing cost increases, and the surface quality of the product is reduced due to the formation of excessive oxide, the content is preferably 0.01-2.0%. Titanium (Ti): 0.05-0.2%
상기 Ti는 강재 내부에 질소와 반웅하여 질화물을 침전시키고 쌍정을 형성하는 성분으로 강도 및 성형성을 확보하기 위하여 첨가한다. 또한상기 Ti는 석출상을 형성하여 강도를 증가시키는 역할을 한다. 이를 위해서 Ti는 0.05%이상 포함되는 것이 바람작하지만， 0.2¾를 초과하는 경우에는 침전물이 과다하게 형성되어 냉간압연시 미세 크랙이 형성될 수 있으며， 성형성 및 용접성의 악화로 이어질 수 있다. 따라서， 상기 Ti의 함량은 0.05~0.2%인 것이 바람직하다. 보론 (B): 0.0005-0.005% The Ti is added to ensure strength and formability as a component that reacts with nitrogen inside the steel to precipitate nitride and form twins. In addition, the Ti forms a precipitated phase to increase the strength. For this purpose, Ti is small to wind contained 0.05% or more, but if it exceeds 0 .2¾ are formed to precipitate the excess can be a micro-cracks formed during cold rolling, can lead to deterioration of the formability and weldability. Therefore, the content of Ti is preferably 0.05 to 0.2%. Boron (B): 0.0005-0.005%
상기 B는 미량 첨가되는 경우 주편의 입계를 강화하는 역할을 하며， 이를 위해 0.0005%이상 포함하는 것이 바람직하다. 그러나 과도하게 포함되어 있는 경우에는 비용이 증가하므로， 그 함량은 0.0005~0.05%인 것이 바람직하다. 황 (S): 0.05%이하 (0은 제외) When B is added in a small amount, it serves to strengthen the grain boundaries of the cast steel, for this purpose it is preferably included 0.0005% or more. However, if excessively included, the cost increases, the content is preferably 0.0005 ~ 0.05%. Sulfur (S): 0.05% or less (excluding 0)
상기 S는 개재물의 제어를 위하여 0.05% 이하로 제어될 필요성이 있다. 상기 S의 함량이 으 05%를 초과하면 열간취성의 문제가 생길 우려가 있으므로， 그 상한을 0.05%로 하는 것이 바람직하다. 인 (P): 0.8%이하(0은 제외 ) The S needs to be controlled to 0.05% or less for the control of inclusions. When the content of S exceeds 05%, there is a possibility that hot brittleness may occur, so the upper limit thereof is preferably 0.05%. Phosphorus (P): 0.8% or less (excluding 0)
상기 P는 편석이 쉽게 발생되는 원소로 주조시 균열발생을 조장한다. 이를 방지하기 위해서 0.8% 이하로 제어하는 것이 바람직하다. 상기 P의 함량이 0.8%를 초과하면 주조성이 악화될 수 있으므로, 그 상한을 0.8%로 하는 것이 바람직하다 . P is an element that segregation easily occurs to promote cracking during casting. In order to prevent this, it is preferable to control to 0.8% or less. If the content of P exceeds 0.8%, castability may deteriorate, so the upper limit is 0.8%. desirable .
질소 (N): 0.003-0.01% Nitrogen (N): 0.003-0.01%
상기 N은 제강 공정 중에 대기와 반웅해서 필수불가결하게 첨가되는 원소이다. 상기 N을 0.003% 미만으로 줄이는 것은 공정상 과도한 비용이 발생하며, 그 함량이 0.01%를 초과하는 경우에는 질화물을 형성하여 성형성을 저하시키므로， 바람직하지 않다. 따라서， 상기 N의 함량은 0.003-0.01%인 것이 바람직하다. 나머지는 Fe 및 불가피한불순물을 포함한다. 본 발명의 강판은 그 미세조직에 탄화물이 1부피 %이하로 포함되어 있는 것이 바람직하다. 본 발명에서 탄소는 원자상태로 고용되어야 하며， 이를 통해 오스테나이트 안정도가 확보된다. 즉, 상기 탄소가 탄화물의 형태로 강중에 존재하게 되면, 오스테나이트의 안정도가 낮아지고, 투자율이 높아져， 비자성 특성이 열위하게 된다. 따라서, 본 발명에서는 강중、탄화물이 가급적 적은 것이 바람직하며, 1부피 ¾ 이하로 형성되는 것이 바람직하다. 특히， 상기 탄화물은 열처리 후에도 1부피 %이하로 포함되는 것이 바람직하다. 상기 열처리는 강판의 제조과정에서 존재하는 열처리 뿐만 아니라， 강관의 사용과정에서 행하여지는 열처리를 포함한다. 한편， 본 발명의 강판은 오스타나이트 조직을 가지며， 열처리 등의 외부에너지에도 비자성을 유지하기 위해, 오스테나이트 조직을 유지하도록 한다. 따라서, 본 발명의 강판은 오스테나이트 조직을 가지며, 열처리 조건에 따라 탄화물이 일부 (1부피 %이하)로 형성되는 것이 바람직하다. 본 발명의 강판은 A1의 함량이 1.3~8.0%인 경우에， 적층결함에너지 (Stacking Fault Energy, SFE) 값이 30mJ/ciif 이상인 것이 바람직하다. 적층결함에너지는 재료 내부에 형성되는 부분전위 사이의 계면이 가지는 에너지로, 본 발명에서는 A1의 함량을 제어함으로서, 적층결함에너자를 제어하고， 이를 통해 오스테나이트상의 상안정성을 향상시킨다. 상기 적층결함에너지가 적당한 값을 가지면 전위와 쌍정이 조화를 이루어 상안정성이 증가하나， 너무 낮아지게 되면 전위가 생성， 이동하지 못하여 상안정성이 감소하고， 반면, 너무 높아지면 전위만으로 변형이 진행되어 강도는 하게 된다. 따라서， 본 발명에서는 적당한 강도를 가지면서 상안정성을 얻기 위해 최적의 적층결함에너지를 도출하게 된 것이다. 상기 적층결함에너지가 30mJ/cuf 미만에서는 쌍정이 성성되어 강도가 상승한다. 그러나， ε-마르텐사이트가 형성된다. 상기 ε-마르텐사이트는 조밀입방구조로 비자성이지만， 통상 α-마르텐사이트를 잘 형성하므로 자성을 증가시킨다. 따라서， 비자성을 유지하면서 쌍정을 형성하여 높은 강도를 가지기 위해서는 적층결함에너지 값이 30 mJ/cuf 이상인 것이 바람직하다. 한편, 상기 적층결함에너지를 측정하는 방법은 X선 측정법， 투과전자현미경 측정법， 열역학계산법 등 다양하며， 성분의 영향을 잘 반영하고， 측정이 용이한 열역학데이터를 이용한 열역학계산법이 가장 바람직하다. N is an element which is indispensably added to the atmosphere during the steelmaking process. Reducing the N to less than 0.003% is an excessive cost in the process, when the content is more than 0.01% because it forms a nitride to lower the formability, it is not preferable. Therefore, the content of N is preferably 0.003-0.01%. The remainder contains Fe and inevitable impurities. In the steel sheet of the present invention, it is preferable that carbides are contained in the microstructure of 1% by volume or less. In the present invention, carbon must be dissolved in an atomic state, thereby securing austenite stability. In other words, when carbon is present in steel in the form of carbides, the austenite has low stability, high permeability, and inferior magnetic properties. Therefore, in the present invention, it is preferable that the number of steels and carbides is as small as possible, and it is desirable to form one volume ¾ or less. In particular, the carbide is preferably included in less than 1% by volume even after the heat treatment. The heat treatment includes not only heat treatment existing in the manufacturing process of the steel sheet, but also heat treatment performed in the process of using the steel pipe. On the other hand, the steel sheet of the present invention has an austenite structure, in order to maintain the austenite structure in order to maintain nonmagnetic in external energy such as heat treatment. Therefore, the steel sheet of the present invention has an austenite structure, and it is preferable that carbides are formed in part (1% by volume or less) depending on the heat treatment conditions. In the steel sheet of the present invention, when the A1 content is 1.3 to 8.0%, the stacking fault energy (SFE) value is preferably 30 mJ / ciif or more. The lamination defect energy is an energy of an interface between partial potentials formed in the material, and in the present invention, by controlling the content of A1, the lamination defect is controlled, thereby improving the phase stability of the austenite phase. If the stacking defect energy has an appropriate value, the potential and twin are in harmony, and thus the phase stability increases, but if it becomes too low, the potential cannot be generated or moved, and the phase stability decreases. Robbery is done. Therefore, in the present invention, the optimum stacking defect energy is derived to obtain phase stability with moderate strength. If the stacking defect energy is less than 30 mJ / cuf, twins are formed and strength increases. However, ε-martensite is formed. The ε-martensite is non-magnetic in a dense cubic structure, but usually increases the magnetism because it forms α-martensite well. Therefore, in order to form twins while maintaining nonmagnetic properties and to have high strength, the lamination defect energy value is preferably 30 mJ / cuf or more. On the other hand, the method of measuring the stacking defect energy is various, such as X-ray measurement method, transmission electron microscope measurement method, thermodynamic calculation method, etc., thermodynamic calculation method using the thermodynamic data that reflects the influence of the components well, and easy to measure is most preferred.
본 발명의 강판은 800MPa 이상의 인장강도를 가지며， 15%이상의 연신율을 확보함으로서， 우수한 강도 및 가공성을 보유하는 것이 바람직하다. The steel sheet of the present invention has a tensile strength of 800MPa or more, and by securing an elongation of 15% or more, it is desirable to have excellent strength and workability.
이하， 본 발명의 제조방법에 대하여 상세히 설명한다. Hereinafter, the manufacturing method of the present invention will be described in detail.
상기 조성을 만족하는 강 슬라브를 1100~1250°C에서 재가열한다. 상기 가열온도가 너무 낮으면， 열간압연시 압연하중이 과도하게 걸릴 수 있기 때문에 1100°C 이상의 온도에서 가열하는 것이 바람직하다. 가열은도가 높을 수록 열간압연이 용이하지만， Mn의 함량이 높은 강은 고온 가열사내부 산화가 심하게 발생되어 표면품질이 저하될 수 있으므로, 상기 재가열 온도의 상한을 1250oC로 하는 것이 바람직하다. Reheat the steel slab that satisfies the composition at 1100-1250 ° C. If the heating temperature is too low, it is preferable to heat at a temperature of 1100 ° C. or more because the rolling load may be excessively taken during hot rolling. The higher the degree of heating, the easier the hot rolling. However, the steel with a high content of Mn may cause severe oxidation inside the high-temperature heating yarn, which may lower the surface quality. Therefore, the upper limit of the reheating temperature is preferably 1250 o C. .
상기 재가열 후 열간압연을 행하고， 800~1000oC에서 열긴 마무리 압연을 행한다. 열간 마무리 압연 온도 역시 고온일수록 변형저항이 낮아서 압연이 용이하지만， 압연은도가 높을수록 표면품질은 저하될 수 있기 때문에 1000oC 이하에서 행하는 것이 바람직하고, 그 온도가 너무 낮으며， 압연 중에 부하가 커지므로， 800°C이상에서 행하는 것이 바람직하다. 상기 열간압연 후 권취하는 단계를 거친다. 상기 권취는 400~700oC에서 행하는 것이 바람직하다. 상기 권취 이후의 냉각속도는 통상적으로 느린 경우가 많다. 권취 개시온도가 너무 낮으면 넁각을 위하여 다량의 냉각수가 필요하고， 권취시 하중이 크게 작용하여 권취 개시 온도는 400oC 이상으로 한다. 권취온도가 고온에서는 권취 후 넁각과정 중에 판 표면의 산화피막과 강판 기지조직과의 반응이 진행되어 산세성을 악화시키기 때문에 700oC 이하의 은도에서 행하는 것이 바람직하다. After reheating, hot rolling is performed, and finish rolling opened at 800 to 1000 ° C. is performed. The hot finish rolling temperature is also easy to roll due to the low deformation resistance at higher temperature, but the higher the rolling degree, the lower the surface quality. Therefore, the temperature is preferably lower than 1000 o C. The temperature is too low. Since it becomes large, it is preferable to carry out at 800 ° C or more. After the hot rolling is subjected to the step of winding. It is preferable to perform the said coiling at 400-700 degreeC . The cooling rate after the said winding is usually slow. If the coiling start temperature is too low, a large amount of cooling water is required for deflection, and the coiling load acts largely so that the coiling start temperature is 400 o C or more. When the coiling temperature is high, the reaction between the oxide film on the surface of the plate and the steel sheet matrix structure progresses during the etching process after the coiling, which deteriorates pickling. Therefore, the coiling temperature is preferably 700 ° C. or lower.
상기 열간압연 후 권취 전에 수넁을 행하는 것이 바람직하다. 상기와 같이 제조된 열연강판을 냉간압연하여 넁연강판올 제조한다. 상기 넁간압연시 압하을은 일반적으로， 요구되는 제품의 두께에 따라 결정되지만， 본 발명에서는 넁간압연 후 열처리 과정에서 재결정이 진행되기 때문에 재결정의 구동력을 잘 제어하는 것이 필요하다. 즉, 넁간 압연시의 압하율이 너무 낮으면 제품의 강도가 떨어지므로, 30% 이상의 압하율로 행하고， 압하율이 너무 높게 되면 강도 확보에 유리하지만， 압연기의 부하가 증가하므로, 이를 고려하여， 60%이하의 압하율로 행하는 것이 바람직하다. It is preferable to carry out water soaking before winding after the said hot rolling. The hot rolled steel sheet prepared as described above is cold rolled to prepare a molten steel sheet. The rolling reduction during inter rolling is generally determined according to the required thickness of the product. However, in the present invention, since the recrystallization proceeds during the heat treatment after the inter rolling, it is necessary to control the driving force of the recrystallization well. In other words, if the reduction ratio during rolling is too low, the strength of the product is lowered. Therefore, the reduction of the product is performed at a reduction ratio of 30% or more. It is preferable to carry out at a reduction ratio of 60% or less.
상기 넁간압연 후， 연속소둔을 행한다. 상기 연속소둔은 650~900oC에서 행하는 것이 바람직하다. 연속소둔은 재결정이 층분히 일어나는 650oC 이상에서 행하는 것이 바람직하나， 소둔 온도가 너무 높으면 표면에 산화물이 형성되고, 연속 작업되는 전 /후 연결제품과의 작껍성이 저하되므로, 900oC 이하에서 행하는 것이 바람직하다. After the inter rolling, continuous annealing is performed. The continuous annealing is preferably carried out at 650 ~ 900 ° C. Continuous annealing is performed at temperatures above 650 o C where recrystallization occurs It is preferable, but if the annealing temperature is too high, an oxide is formed on the surface, and the peelability with the front / rear connection products which are continuously worked is reduced, so it is preferable to carry out at 900 ° C. or less.
【발명의 실시를 위한 형태】  [Form for implementation of invention]
이하, 본 발명의 실시예에 대하여 상세히 설명한다. 하기 실시예는 본 발명의 이해를 위한 것으로， 실시예에 의해 본 발명이 한정되는 것은 아니다. Hereinafter, embodiments of the present invention will be described in detail. The following examples are for the understanding of the present invention, and the present invention is not limited by the examples.
(실시예 1) (Example 1)
하기 표 1의 조성을 만족하는 강슬라브를 1200oC로 재가열하고, 900oC에서 열간 마무리 압연을 행하고， 500oC에서 권취한 후， 50¾의 압하율로 냉간압연하고， 800°C로 연속소둔을 행하여， 냉연강판을 제조하였다. Reheating the steel slab satisfying the composition of the following Table 1 to 1200 o C and, 900 o subjected to hot finish rolling at C, and then wound at 500 o C, and cold rolled to a reduction ratio of 50¾, continuous annealing to 800 ° C Was carried out to produce a cold rolled steel sheet.
【표 1】 Table 1
Figure imgf000011_0001
상기 강판의 물리적 성질을 알아보기 위해서， 항복강도, 인장강도 및 연신율을 측정하여 하기 표 2에 나타내었다. 【표 2】
Figure imgf000012_0001
상기 제조된 강판에 대하여， 개재물의 분율과 열처리 조건에 따른 탄화물 분율과 자기장 25kAAn에서의 상대투자율을 측정하였다. 상기 열처리는 제조과정에서의 열처리 또는 강판의 사용중에 있을 수 있는 열처리를 모사한 것이다. 한편ᅳ 투자율은 진공에서의 투자율과 특정 분위기에서의 투자율의 비인 상대투자율로 표시되며， 본 발명에서는 진공과 대기에서의 투자율비인 상대투자율 |^올 측정하였다. 측정은 VSM Vibrating Sample Magnetometer) 장비를 이용하였으며， VSM은 Hall probe에 의해서 가한 인가 자장을 기록하고 시료의 자화 값은 패러데이 법칙에 의해서 시료에 진동을 가할 때 얻어지는 기전력을 기록하여 시료의 자화 값을 측정한다. VSM은 이러한 기본 작동,원리에 의하여 시료에 진동을 가할 시 발생하는 유도기전력을 search coil에서 검출하여 이 기전력에 의해 시료의 자화 값을 측정하는 방법이다. 재료의 자기적 특성을 자기장， 온도， 시간의 함수로 간단히 측정할 수 있으며， 최대 2 테슬라의 자력과
Figure imgf000011_0001
In order to determine the physical properties of the steel sheet, yield strength, tensile strength and elongation were measured and shown in Table 2 below. Table 2
Figure imgf000012_0001
For the produced steel sheet, the fraction of inclusions, the carbide fraction according to the heat treatment conditions, and the relative permeability in the magnetic field of 25 kAAn were measured. The heat treatment simulates a heat treatment in the manufacturing process or heat treatment that may be in use of the steel sheet. On the other hand, the permeability is expressed as relative permeability, which is the ratio of permeability in vacuum and permeability in a specific atmosphere. In the present invention, relative permeability relative to permeability in vacuum and atmosphere was measured. The measurement was performed using a VSM Vibrating Sample Magnetometer. The VSM records the applied magnetic field applied by the Hall probe, and the magnetization value of the sample is measured by recording the electromotive force obtained when vibrating the sample by Faraday's law. do. VSM is a method of measuring the magnetization value of a sample by detecting the induced electromotive force in the search coil by applying the vibration to the sample by this basic operation and principle. The magnetic properties of the material can be measured simply as a function of magnetic field, temperature and time.
2 K to 1273 K 온도 범위의 빠른 측정이 가능하다. 또한 분말， 박막， 단결정, 액체 등의 대부분 형태의 시료를 측정할 수 있는 장점이 있어 자성 측정방법으로 널리 사용되고 있다. Fast measurement in the 2 K to 1273 K temperature range is possible. In addition, it has the advantage of measuring most types of samples such as powder, thin film, single crystal and liquid. It is widely used.
【표 3] [Table 3]
Figure imgf000013_0001
상기 표 3의 결과에서 알 수 있듯이， 열처리 조건이 400oC에서 1시간 동안 행한 경우에, 탄화물의 분율이 1부피 ¾ 이하인 경우에는 투자율이 1.05 이하로서, 우수한 비자성 특성을 갖는 것을 알 수 있다. 또한, 보다 가혹한 열처리 조건인 600°C에서 5시간동안 열처리 행한 경우에도， 탄화물의 분율이 1부피 % 이하인 경우에는 투자율이 1.10을 넘지 않는 것을 확인할 수 있었다. 한편， 상기 발명예 1-7과 비교예 1-3의 미세조직을 관찰하여 이를 각각 도 1(a) 및 (b)에 나타내었다. 도 1에 나타난 바와 같이， 본 발명예에서는 탄화물의 분율이 매우 적으나， 본 발명의 범위를 벗어난 비교예에서는 탄화물의 분율이 1부피 %를 초과하여 비자성특성이 열위에 있음을 알 수 있다. 따라서, 탄화물의 분율이 1부피 ¾이하가 되는 경우에， 우수한 비자성특성을 확보할 수 있음을 확인할 수 있다.
Figure imgf000013_0001
As can be seen from the results in Table 3, when the heat treatment conditions were performed for 1 hour at 400 ° C., when the carbide fraction is 1 volume ¾ or less, the permeability is 1.05 or less, it can be seen that it has excellent nonmagnetic properties. . In addition, even when the heat treatment was performed for 5 hours at more severe heat treatment conditions 600 ° C., it was confirmed that the permeability does not exceed 1.10 when the carbide fraction is less than 1% by volume. Meanwhile, the microstructures of Inventive Examples 1-7 and Comparative Examples 1-3 were observed and shown in FIGS. 1 (a) and (b), respectively. As shown in Figure 1, the fraction of carbide in the present invention is very small, in the comparative example outside the scope of the present invention it can be seen that the nonmagnetic properties inferior to the fraction of the carbide exceeds 1% by volume. Therefore, it can be seen that excellent nonmagnetic properties can be ensured when the fraction of carbide becomes 1 volume ¾ or less.
(실시예 2) ᅳ Example 2
하기 표 4의 조성 (중량 %)을 만족하는 강슬라브를 1200°C로 재가열하고, Reheat the steel slab that satisfies the composition (% by weight) of Table 4 below at 1200 ° C.,
900oC에서 열간 마무리 압연을 행하고， 500oC에서 권취한 후， 50%의 압하율로 넁간압연하고, 800oC로 연속소둔을 행하여， 넁연강판을 제조하였다. Hot finish rolling was performed at 900 ° C., wound at 500 ° C., and then hot-rolled at a rolling reduction rate of 50%, followed by continuous annealing at 800 ° C. to produce a mild steel sheet.
【표 4] [Table 4]
Figure imgf000014_0001
Figure imgf000014_0001
Figure imgf000015_0001
상기 넁연강판에 대해， 항복강도 (YS), 인장강도 (TS) 및 연신율을 측정하여 그 결과를 표 2에 나타내었다. 또한， 적층결함에너지 (SFE)를 측정하여 그 결과를 나타내었으며， 상대투자율을 측정하여 그 결과를 표 5에 함께 나타내었다. 상대투자율은 50kA/m의 자장에서 측정하였고， 다른 조건은 상기 실시예 1과 동일한 조건에서 실시하였다.
Figure imgf000015_0001
Yield strength (YS), tensile strength (TS) and elongation were measured for the ductile steel sheet, and the results are shown in Table 2. In addition, the results of the measurement of the stacking fault energy (SFE) were shown, and the relative permeability was measured and the results are shown in Table 5 together. Relative permeability was measured in a magnetic field of 50 kA / m, other conditions were carried out under the same conditions as in Example 1.
【표 5】 Table 5
Figure imgf000015_0002
Figure imgf000015_0002
Figure imgf000016_0001
상기 표 5의 결과에서 알 수 있듯이， 본 발명의 범위를 만족하는 발명예는 모두 적층결함에너지 (SFE)가 30 mJ/m2 이상인 동시에， 상대 투자율이 낮음을 알 수 있다. 즉， 우수한 비자성특성을 확보할 수 있으며， 상안정성이 높다는 것을 알 수 있었다. 이에 비해, 비교예는 상기 적층결함에너지 또는 상대 투자율 중 어느 하나의 효과를 확보하기 어려운 문제가 있음을 알 수 있다. 한편， 도 2는 각각 상기 발명예 2-1과 비교예 2-1의 XRD를 분석한 그래프이다. 도 2(a)와 (b)는 각각 발명예와 비교예의 상안정도를 특정하고, 적층결함에너지의 영향을 확인하으며， 도 3의 (a)와 (b)는 각각 상기 발명예 1- 1과 비교예 1—1의 미세조직을 관찰한 것이다. 도 2 및 3로부터， 본 발명의 범위를 만족하는 발명예는 전범위에 고른 쌍정이 발생한 것을 알 수 있고 이를 통해 우수한 상안정성을 갖는 것을 확인할 수 있다. 반면, 비교예는 적층결함에너지가 낮아 변형 후 쌍정 발생이 커지고， 일부 결정빌에서 쌍정이 발생.하지 않는 것을 확인할 수 있다.
Figure imgf000016_0001
As can be seen from the results of Table 5, all the invention examples satisfying the scope of the present invention can be seen that the lamination defect energy (SFE) is 30 mJ / m 2 or more, and the relative permeability is low. That is, it can be seen that excellent nonmagnetic properties can be secured, and that phase stability is high. On the other hand, it can be seen that the comparative example has a problem that it is difficult to secure the effect of any one of the lamination defect energy and the relative permeability. 2 is a graph analyzing the XRD of Inventive Example 2-1 and Comparative Example 2-1, respectively. 2 (a) and (b) specify the degree of stability of the invention example and the comparative example, respectively, and confirm the effect of the stacking fault energy, Figure 3 (a) and (b) is the invention example 1-1 And the microstructure of Comparative Example 1-1. 2 and 3, the invention examples satisfying the scope of the present invention can be seen that evenly generated twins in the entire range, it can be confirmed that having excellent phase stability through this. On the other hand, in the comparative example, it is confirmed that the twinning occurs after deformation due to low stacking defect energy, and twins do not occur in some crystal bills.

Claims

【청구의 범위】 [Range of request]
【청구항 1】  [Claim 1]
중량 %로, C: 0.4-0.9%, Mn: 10-25%, A1： 0.01-8.0%, Si: 0.01-2.0%, Ti： 0.05-0.2%, Si: 0.01-2.0%, B: 0.0005-0.005%, S: 0.05%이하 (0은 제외)， P: 0.8%이하(0은 제외)， N: 0.003-0.01%, 나머지는 Fe 및 불가피한 불순물을 포함하는 비자성 고강도 고망간 강판. By weight%, C: 0.4-0.9%, Mn: 10-25%, A1: 0.01-8.0%, Si: 0.01-2.0%, Ti: 0.05-0.2%, Si: 0.01-2.0%, B: 0.0005- A nonmagnetic high strength high manganese steel sheet containing 0.005%, S: 0.05% or less (excluding 0), P: 0.8% or less (excluding 0), N: 0.003-0.01%, and the rest are Fe and unavoidable impurities.
【청구항 2】  [Claim 2]
청구항 1에 있어서， ᅳ The method according to claim 1, ᅳ
상기 강판의 미세조직 중 탄화물의 분율이 1부피 % 이하인 비자성 고강도 고망간 강판. A nonmagnetic high strength manganese steel sheet having a carbide fraction of 1% by volume or less in the microstructure of the steel sheet.
【청구항 3】  [Claim 3]
청구항 1에 있어서, The method according to claim 1,
상기 강판의 상대투자율이 25kA/m의 자장에서 1.10 이하인 비자성 고강도 고망간 강판. A nonmagnetic high strength high manganese steel sheet having a relative permeability of the steel sheet of 1.10 or less in a magnetic field of 25 kA / m.
【청구항 4】  [Claim 4]
청구항 1에 있어서, The method according to claim 1,
상기 A1의 함량이 1.3~8.0¾인 경우， 적층결함에너지가 30 mJ/cin2 이상인 비자성 고강도 고망간 강판. When the content of A1 is 1.3 ~ 8.0¾, laminated defect energy of 30 mJ / cin 2 or more non-magnetic high strength high manganese steel sheet.
【청구항 5】  [Claim 5]
청구항 4에 있어서， The method according to claim 4,
상기 강판은 50kA/m의 자장에서 상대투자율이 1.05 이하인 비자성 고강도 고망간 강판. The steel sheet is a nonmagnetic high strength high manganese steel sheet having a relative permeability of 1.05 or less in a magnetic field of 50 kA / m.
【청구항 6] [Claim 6]
청구항 1에 있어서， The method according to claim 1,
상기 강판의 인장강도는 800MPa 이상이고， 연신율이 15%이상인 비자성 고강도 고망간 강판. The tensile strength of the steel sheet is 800MPa or more, non-magnetic high strength high manganese steel sheet having an elongation of 15% or more.
【청구항 7】  [Claim 7]
중량 ¾로， C: 0.4-0.9%, Mn: 10-25%, A1： 0.01-8.0%, Si:. 0.01-2.0%, Ti： 0.05-0.2%, Si: 0.01-2.0%, B: 0.0005-0.005%, S: 0.05>이하 (0은 제외)， P: 0.8%이하(0은 제외), N: 0.003-0.01%, 나머지는 Fe 및 불가피한 불순물을 포함하는 강 슬라브를 1100~1250°C로 재가열하는 단계; 상기 재가열된 강 슬라브를 열간압연하고， 800~950°C에서 마무리 압연하는 열간압연하는 단계 ; With weight ¾, C: 0.4-0.9%, Mn: 10-25%, A1: 0.01-8.0%, Si :. 0.01-2.0%, Ti: 0.05-0.2%, Si: 0.01-2.0%, B: 0.0005-0.005%, S: 0.05> or less (excluding 0), P: 0.8% or less (excluding 0), N: Reheating the steel slab comprising 0.003-0.01%, the remainder Fe and unavoidable impurities to 1100-1250 ° C .; Hot rolling the reheated steel slab and hot rolling finish-rolling at 800 to 950 ° C .;
상기 열간압연된 강판을 400~700oC에서 권취하는 단계; Winding the hot rolled steel sheet at 400 ° C. to 700 ° C .;
30~60)의 압하율로 냉간압연하는 단계 ; Cold rolling at a reduction ratio of 30 to 60);
상기 냉간압연된 강판을 650~900°C에서 연속소둔하는 단계 를 포함하는 비자성 고강도 고망간 강판의 제조방법 . Method for producing a non-magnetic high strength high manganese steel sheet comprising the step of continuously annealing the cold-rolled steel sheet at 650 ~ 900 ° C.
PCT/KR2012/011168 2011-12-23 2012-12-20 Non-magnetic high manganese steel sheet with high strength and manufacturing method thereof WO2013095005A1 (en)

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JP2014548662A JP6002779B2 (en) 2011-12-23 2012-12-20 Non-magnetic high-strength high-manganese steel sheet and method for producing the same
CN201280064011.5A CN104011248B (en) 2011-12-23 2012-12-20 There is the non magnetic high manganese steel sheet for heavy electric machinery and the manufacture method thereof of high intensity
US14/367,480 US20150211088A1 (en) 2011-12-23 2012-12-20 Non-magnetic high manganese steel sheet with high strength and manufacturing method thereof
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KR1020110142433A KR20130074384A (en) 2011-12-26 2011-12-26 High strength and high manganese steel sheet having excellent non-magnetic property and method for manufacturing the same
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