KR20040056300A - Method for manufacturing high manganese steel using strip casting method - Google Patents
Method for manufacturing high manganese steel using strip casting method Download PDFInfo
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- KR20040056300A KR20040056300A KR1020020082903A KR20020082903A KR20040056300A KR 20040056300 A KR20040056300 A KR 20040056300A KR 1020020082903 A KR1020020082903 A KR 1020020082903A KR 20020082903 A KR20020082903 A KR 20020082903A KR 20040056300 A KR20040056300 A KR 20040056300A
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- 229910000617 Mangalloy Inorganic materials 0.000 title claims abstract description 32
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 26
- 238000005266 casting Methods 0.000 title claims abstract description 22
- 238000000034 method Methods 0.000 title claims description 16
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 36
- 239000010959 steel Substances 0.000 claims abstract description 36
- 239000007789 gas Substances 0.000 claims abstract description 10
- 230000005499 meniscus Effects 0.000 claims abstract description 10
- 238000007711 solidification Methods 0.000 claims abstract description 9
- 230000008023 solidification Effects 0.000 claims abstract description 9
- 239000011572 manganese Substances 0.000 claims abstract description 8
- 238000005096 rolling process Methods 0.000 claims abstract description 8
- 229910001208 Crucible steel Inorganic materials 0.000 claims abstract description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 7
- 239000001301 oxygen Substances 0.000 claims abstract description 7
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 238000005098 hot rolling Methods 0.000 claims description 12
- 238000007789 sealing Methods 0.000 abstract description 2
- 238000005097 cold rolling Methods 0.000 description 6
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 4
- 239000010960 cold rolled steel Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 210000001787 dendrite Anatomy 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 238000007712 rapid solidification Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 229910000859 α-Fe Inorganic materials 0.000 description 2
- 238000000137 annealing Methods 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000000879 optical micrograph Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000013585 weight reducing agent Substances 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
- B22D11/0622—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by two casting wheels
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/128—Accessories for subsequent treating or working cast stock in situ for removing
-
- 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
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- 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
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Metal Rolling (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
박판주조법에 의한 고망간강의 제조방법이 제공된다.Provided is a method of manufacturing high manganese steel by sheet casting.
본 발명은, 롤갭을 두고 서로 맞서 위치되는 쌍롤, 이 쌍롤 양끝단부에 설치된 에지댐 및 용강 탕면을 차단하여 실링하는 메니스커스 실드를 포함하는 쌍롤형 박판주조기의 쌍롤사이에 고망간강 제조용 용강을 공급하여 박판을 제조하는 박판주조공정에 있어서,The present invention provides a molten steel for manufacturing high-manganese steel between a pair of rolls of a thin-rolled sheet caster including a pair of rolls positioned against each other with a roll gap, an edge dam provided at both ends of the pair of rolls, and a meniscus shield for sealing the molten steel surface. In the sheet casting process of manufacturing a thin plate,
상기 메니스커스 실드내 용강탕면위의 분위기가스중의 산소농도: 0.1% 이하 및 롤닙에서의 압하력: 0.5 -2.0 Ton으로 유지하면서, 중량%로 C : 1.5% 이하, Mn : 15 - 35%, Al : 0.1 - 6.0%, 잔부 Fe 및 불가피한 불순물로 이루어진 용강을 100oC/sec이상의 응고속도로 연속주조하여 주편을 제조하고, 이어, 상기 제조된 주편을 10%이상의 압하율로 열간압연하는 것을 특징으로 하는 이방성을 저감시킬 수 있는 고강도 및 고인성 고망간강 제조방법에 관한 것이다.Oxygen concentration in the atmospheric gas on the molten steel surface in the meniscus shield: 0.1% or less and rolling force in roll nip: 0.5 -2.0 Ton, while maintaining the weight in C: 1.5% or less, Mn: 15-35% , Al: 0.1-6.0%, remainder Fe and unavoidable impurities continuously cast a molten steel at a solidification rate of 100 o C / sec or more to manufacture a cast steel, and then hot-rolled the produced cast steel at a rolling rate of 10% or more It relates to a high strength and high toughness high manganese steel production method that can reduce the anisotropy characterized by.
Description
본 발명은 자동차용 강판등에 사용되는 고강도 및 고인성을 갖는 고망간강을 제조하는 방법에 관한 것으로서, 보다 상세하게는, 박판주조법으로 고망간강 제조시 야기될 수 있는 인장성질의 이방성을 해소할 수 있는 고강도 및 고인성의 고망간강의 제조방법에 관한 것이다.The present invention relates to a method for manufacturing high manganese steel having high strength and high toughness used in steel sheets for automobiles, and more particularly, to solve the anisotropy of tensile properties that may be caused when manufacturing high manganese steel by sheet casting. It relates to a method for producing high strength and high toughness high manganese steel.
자동차용 강판으로는 성형성을 고려하여 기지 조직이 페라이트이며, 불순물을 최대한 저감한 극저탄소강이 사용되어 왔다. 그러나, 극저탄소강의 경우에는 성형성이 높은 반면에 충분한 인성을 가지지 못하고, 또한 강도가 30 kg/mm2로 낮은 단점을 가지고 있다.As a steel sheet for automobiles, the base structure is ferrite in consideration of formability, and ultra-low carbon steel which has reduced impurities as much as possible has been used. However, in the case of ultra low carbon steel, the moldability is high but does not have sufficient toughness, and the strength is low as 30 kg / mm 2 .
최근에 자동차용 강판의 요구 조건으로 자동차의 충돌에서 최소의 충격을 위하여 고인성의 강판이 요구되고 있고, 또한 자동차 경량화를 위하여 고강도 강판을 필요로 하고 있다. 이러한 고강도, 고인성의 강판은 기지 조직이 페라이트인 극저탄소강에서는 달성하기 어려운 것이며, 기지 조직이 오스테나이트인 강에서 TRIP(Transformation Induced Plasticity) 또는 TWIP (Twin Induced Plasticity) 현상을 이용하는 방법에 의하여 달성할 수 있는 것으로 알려져 있다.Recently, high toughness steel sheet is required to minimize impacts in collision of automobiles as a requirement of steel sheet for automobiles, and high strength steel sheet is required for lightening automobiles. Such high strength and high toughness steel sheet is difficult to achieve in the ultra low carbon steel having a base structure of ferrite, and can be achieved by using a transformation induced plasticity (TRIP) or twin induced plasticity (TWIP) phenomenon in steel having a base structure of austenite. It is known that it can.
오스테나이트계 자동차용 강판으로는 대한민국 특허공보 제1994-0007374호에 제시되어 있는 오스테나이트계 고망간강을 들수 있다. 구체적으로 상기 특허공보에는, 중량%로 C : 1.5% 이하, Mn : 15 - 35%, Al : 0.1 - 6.0%, 잔부 Fe 및 불가피한 불순물로 조성되는 고강도 및 고인성의 오스테나이트계 고망간강을 제시하고 있다. 또한 상기 특허공보에서는 Al을 첨가하여 적층결함에너지를 높임에 따라 고망간강이 변형에 의하여 ε-마르텐사이트를 형성하지 않고, 변형유기 쌍정만을 생성하도록 함으로써 고강도 및 고인성을 갖는 고망간강의 제조가 가능함을 개시하고 있다.The austenitic automotive steel sheet may include the austenitic high manganese steel disclosed in Korean Patent Publication No. 194-0007374. Specifically, the patent publication, C: 1.5% or less, Mn: 15-35%, Al: 0.1-6.0% by weight, present a high-strength and high toughness austenitic high manganese steel composed of residual Fe and unavoidable impurities have. In addition, in the above patent publication, high manganese steel does not form ε-martensite by deformation due to the addition of Al to increase the stacking defect energy, and thus it is possible to manufacture high manganese steel having high strength and toughness by generating only modified organic twins. Is starting.
그러나 상기 공보에 제시된 고망간강의 제조방법은 일반적인 강의 생산방법인 용해-연속주조(또는 조괴) -열간압연-냉간압연-소둔열처리를 포함하며, 이러한 공정을 거치므로써, 20 - 27 kg/mm2의 항복강도, 57 - 66 kg/mm2의 인장강도, 및 40 - 60%의 연신률을 갖는 고망간강을 제조한다. 따라서 이러한 고망간강은 극저탄소강에 비하여 기계적 특성이 개선되었으나, 자동차의 배기가스 배출 감소와 연료절감을 위한 경량화를 위해서는 항복강도의 증가가 미흡한 문제점이 있다.However, the manufacturing method of high manganese steel presented in the above publication includes melt-continuous casting (or ingot)-hot rolling-cold rolling-annealing heat treatment, which is a general production method of steel, and through such a process, 20-27 kg / mm 2 A high manganese steel having a yield strength of, a tensile strength of 57-66 kg / mm 2 , and an elongation of 40-60% is produced. Therefore, the high manganese steel has improved mechanical properties compared to the ultra low carbon steel, but there is a problem in that the yield strength is insufficient to reduce the exhaust emission of the automobile and to reduce the weight for fuel saving.
상기 종래기술의 문제점을 해결하기 위한 기술로서, 본 발명자의 대한민국특허 출원 2002-52073호에 개시된 발명을 들 수 있다. 상기 특허출원에서는 박판주조법의 급속응고 효과를 이용하여, 조직 미세화에 의하여 항복강도를 증가시키는 기술을 제시하고 있다.As a technique for solving the problems of the prior art, the invention disclosed in the Republic of Korea Patent Application No. 2002-52073 of the inventors. The patent application proposes a technique of increasing the yield strength by miniaturizing the tissue by using the rapid solidification effect of the thin plate casting method.
그러나 박판주조법에 의하여 고망간강을 제조하고, 이를 냉연 및 열처리하여 강판을 제조하는 경우에 인장성질에 있어서 냉간압연 방향 (L방향)과 냉간압연 직각방향 (T방향) 간에 연신률에 있어서 커다란 차이를 보이는 이방성이 있는 문제가 있다.However, in the case of manufacturing high manganese steel by sheet casting, cold rolling and heat treatment to produce steel sheet, there is a big difference in elongation between cold rolling direction (L direction) and cold rolling right angle direction (T direction) in tensile properties. There is a problem with anisotropy.
따서 본 발명은 상술한 종래기술의 문제점을 해결하기 위하여 마련된 것으로서, 쌍롤형 박판주조기를 이용하여 고망간강을 제조함에 있어서, 급속응고에 의하여 금속내부의 조직을 미세하게 하여 소재의 항복강도를 개선시킬 뿐만 아니라 열간압연공정을 통하여 연신율 이방성을 해소할 수 있는 고인성 고강도의 고망간강을 제조방법을 제공함에 그 목적이 있다.Accordingly, the present invention is to solve the problems of the prior art described above, in manufacturing high manganese steel using a twin-roll sheet caster, to improve the yield strength of the material by making the internal structure of the metal fine by rapid solidification In addition, it is an object of the present invention to provide a method for producing high toughness high strength manganese steel that can solve the elongation anisotropy through hot rolling process.
도 1은 통상적인 쌍롤형 박판주조기의 개략도1 is a schematic view of a conventional twin roll sheet caster
도 2는 본 발명에 부합하는 쌍롤형 박판주조기의 개략도2 is a schematic view of a twin roll sheet caster according to the present invention;
도 3은 열간압연을 행하지 않은 고망간강 박판의 광학현미경 사진3 is an optical microscope photograph of a high manganese steel sheet without hot rolling
이하, 본 발명을 설명한다.Hereinafter, the present invention will be described.
상술한 바와 같이, 본 발명자등은 대한민국 특허출원 2002-52073호를 통하여 쌍롤식 박판주조기를 이용하여 고강도 및 고인성 고망간강 제조방법을 제시한 바있다. 그러나 이 방법에서는 인장성질에 있어서 냉간압연 방향 (L방향)과 냉간압연 직각방향 (T방향) 간에 연신률에 있어서 커다란 차이를 보이는 이방성이 있는 문제가 있다. 그러므로 본 발명자등은 이러한 문제점을 해결하기 위하여, 연구와 실험을 거듭하였으며, 그 결과, 박판주조법으로 제조된 주편을 10%이상의 압하율로 열간압연을 행하면 이방성이 현저히 개선됨을 발견하고 본 발명을 제시하는 것이다.As described above, the present inventors have proposed a high-strength and toughness high manganese steel manufacturing method using a twin-roll sheet caster through the Republic of Korea Patent Application 2002-52073. However, this method has a problem in that the anisotropy exhibits a large difference in elongation between the cold rolling direction (L direction) and the cold rolling right angle direction (T direction) in tensile properties. Therefore, the present inventors have repeatedly studied and experimented to solve these problems. As a result, the present inventors have found that the anisotropy is remarkably improved when hot-rolled a slab manufactured by the sheet casting method with a reduction ratio of 10% or more. It is.
따라서 본 발명은, 롤갭을 두고 서로 맞서 위치되는 쌍롤, 이 쌍롤 양끝단부에 설치된 에지댐 및 용강 탕면을 차단하여 실링하는 메니스커스 실드를 포함하는 쌍롤형 박판주조기의 쌍롤사이에 고망간강 제조용 용강을 공급하여 박판을 제조하는 박판주조공정에 있어서,Accordingly, the present invention provides a molten steel for manufacturing high-manganese steel between a pair of rolls of a thin-rolled sheet caster including a pair of rolls positioned against each other with a roll gap, an edge dam provided at both ends of the pair of rolls, and a meniscus shield for sealing the molten steel surface. In the sheet casting process of supplying a thin plate,
상기 메니스커스 실드내 용강탕면위의 분위기가스중의 산소농도: 0.1% 이하 및 롤닙에서의 압하력: 0.5 -2.0 Ton으로 유지하면서, 중량%로 C : 1.5% 이하, Mn : 15 - 35%, Al : 0.1 - 6.0%, 잔부 Fe 및 불가피한 불순물로 이루어진 용강을 100oC/sec이상의 응고속도로 연속주조하여 주편을 제조하고,Oxygen concentration in the atmospheric gas on the molten steel surface in the meniscus shield: 0.1% or less and rolling force in roll nip: 0.5 -2.0 Ton, while maintaining the weight in C: 1.5% or less, Mn: 15-35% , Al: 0.1-6.0%, the molten steel consisting of the remaining Fe and unavoidable impurities continuously cast at a solidification rate of 100 o C / sec or more,
이어, 상기 제조된 주편을 10%이상의 압하율로 열간압연하는 것을 특징으로 하는 이방성을 저감시킬 수 있는 고강도 및 고인성 고망간강 제조방법에 관한 것이다.Next, the present invention relates to a high strength and high toughness manganese steel manufacturing method that can reduce the anisotropy, characterized in that the hot-rolled at least 10% of the produced cast steel.
이하, 첨부도면을 참조하여 본 발명을 설명한다.Hereinafter, the present invention will be described with reference to the accompanying drawings.
도 1은 통상적인 박판주조공정에 이용될 수 있는 쌍롤형 박판 주조기의 일례이다. 도 1에 나타난 바와 같이, 통상적인 쌍롤형 박판 주조기는 롤갭을 두고 서로 맞서 위치되는 쌍롤(1), 이 쌍롤(1) 양끝단부에 설치된 에지댐(7) 및 용강 탕면을 차단하여 실링하는 메니스커스 실드(5)를 포함하여 구성된다. 또한 상기 에지댐(7)은 용강이 롤배럴 측면으로 누출되는 것을 방지하는 댐역할을 하며, 상기 메니스커스 실드(5)는 용강산화를 방지하기 위해 공급된 불활성가스를 실링할 수 있는 밀폐된 공간을 부여하는 역할을 한다.1 is an example of a twin roll type sheet casting machine that can be used in a conventional sheet casting process. As shown in FIG. 1, a conventional twin roll type sheet casting machine seals a pair of rolls (1) positioned against each other with a roll gap, an edge dam (7) provided at both ends of the pair rolls (1), and a molten steel surface. It comprises a curse shield (5). In addition, the edge dam 7 serves as a dam to prevent the molten steel from leaking to the side of the roll barrel, and the meniscus shield 5 is hermetically sealed to seal the inert gas supplied to prevent molten steel oxidation. It serves to give space.
한편, 도 1에서, 부호 "2"은 래들을 나타내고, 부호 "3"은 턴디쉬를 나타내고, 부호 "4"은 침지노즐을 나타내고, 부호 "6"은 브러쉬 롤을 나타내고, 부호 "8"은 박판을 나타내고, 부호 "9"는 핀치롤을 나타내고, 부호"10"은 수냉장치를 나타내고, 그리고 부호 "11"은 권취코일을 나타낸다.1, reference numeral "2" denotes a ladle, reference numeral "3" denotes a tundish, reference numeral "4" denotes an immersion nozzle, reference numeral "6" denotes a brush roll, and reference numeral "8" denotes A thin plate is shown, "9" represents a pinch roll, "10" represents a water cooling device, and "11" represents a winding coil.
본 발명에서는 먼저, 고망간강 제조용 용강을 노즐을 통해 2개의 회전하는 롤(1) 사이에 주입하고, 주입된 용강은 롤(1)과 접촉하여 응고각을 형성하고 롤이 회전함에 따라 롤 최근접점(롤닙)에서 만나 박판(주편)(8)을 형성한다. 상기 롤(1) 사이에 주입되는 고망간강용 용강은 일반적인 강종과 같이 고망간강을 용해로에서 용해한 후 래들에 수강한 다음, 수강된 용강의 2차 정련을 위한 정련 설비에서 온도 조정 및 미세 성분조정등을 행한 것이다.In the present invention, first, molten steel for manufacturing high manganese steel is injected between two rotating rolls 1 through a nozzle, and the injected molten steel is in contact with the roll 1 to form a solidification angle and the roll closest contact as the roll rotates. (Roll nip) meets to form a thin plate (cast) 8. The molten steel for high manganese steel injected between the rolls (1) is melted in a melting furnace, as in general steel grades, and then received in a ladle, followed by temperature adjustment and fine composition adjustment in a refining facility for secondary refining of the molten steel. Is done.
본 발명에 적용되는 고망간강 제조를 위한 용강은, 중량%로 C : 1.5% 이하, Mn : 15 - 35%, Al : 0.1 - 6.0%, 잔부 Fe 및 불가피한 불순물로 조성되는 것이 바람직하다. 또한 이러한 용강을 이용하여 박판으로 제조(주조)시 용강의 응고속도를100oC/sec 이상되도록 설정하는 것이 바람직하다. 주조시 응고속도를 100oC/sec 이상으로 해야만, 주편 즉, 박판의 수지상정 간격이 5 마이크론 이하가 될 수 있기 때문이다.Molten steel for the production of high manganese steel applied to the present invention is preferably composed of C: 1.5% or less, Mn: 15-35%, Al: 0.1-6.0%, balance Fe and inevitable impurities in weight%. In addition, it is preferable to set the solidification rate of the molten steel to be 100 o C / sec or more when manufacturing the molten steel using such molten steel. This is because the solidification rate at the time of casting must be 100 o C / sec or more, so that the dendrite spacing of the cast, i.e., sheet, can be 5 microns or less.
또한 본 발명에서는, 크랙이 없는 양호한 박판(주편)(8)을 제조하기 위해서는 용탕면을 완전히 덮을 수 있고 가스를 공급할 수 있는 메니스커스 실드(5)를 사용한다. 그리고, 이때 사용하는 분위기 가스가 중요한데, 분위기 가스를 적절히 유지하므로써 용탕의 산화를 방지하고, 응고시의 용강 메니스커스와 주조롤 계면의 계면에너지를 변화시켜 응고를 균일하게 할 수 있다.In addition, in this invention, in order to manufacture the favorable thin plate (casting) 8 without a crack, the meniscus shield 5 which can completely cover a molten surface and can supply gas is used. In addition, although the atmospheric gas used at this time is important, by appropriately maintaining the atmospheric gas, oxidation of the molten metal can be prevented, and solidification can be made uniform by changing the interface energy between the molten steel meniscus and the casting roll interface during solidification.
본 발명에서는 이러한 분위기 가스로서 아르곤이나 질소등의 불활성 가스를 사용할 수 있으며, 용탕의 산화를 방지하기 위하여는 분위기 가스중 산소농도를 0.1% 이하로 제어하여야 한다. 만일 분위기 가스중 산소농도가 0.1%를 초과하는 경우에는 산소에 의하여 주편에 결함이 발생하고, 초기응고가 방해를 받게 되어 크랙발생의 원인이 될 수 있다.In the present invention, an inert gas such as argon or nitrogen may be used as the atmosphere gas, and in order to prevent oxidation of the molten metal, the oxygen concentration in the atmosphere gas should be controlled to 0.1% or less. If the oxygen concentration in the atmospheric gas exceeds 0.1%, oxygen may cause defects in the cast steel, and the initial coagulation may be disturbed, causing cracks.
또한, 롤닙에서의 압하력은 최소한으로 유지하여 고온 변형에 의한 크랙의 발생을 억제하여야 한다. 따라서, 본 발명에 있어서 롤닙에서의 압하력은 0.5~2.0 Ton 이하로 설정하는 것이 바람직하다.In addition, the rolling force in the roll nip should be kept to a minimum to suppress the occurrence of cracks due to high temperature deformation. Therefore, in this invention, it is preferable to set the rolling force in a roll nip to 0.5-2.0 Ton or less.
이어, 본 발명에서는 상기와 같은 공정으로 제조된 두께 2~6mm의 주편을 10%이상의 압하율로 열간압연처리하며, 이러한 열간압연공정을 통하여 제조된 주편의연신율 이방성을 개선할 수 있다. 그러나 이러한 열간압연에 따른 효과를 얻기 위해서는 적어도 10%이상의 압하율을 필요하다.Subsequently, in the present invention, hot rolling is performed on the slabs having a thickness of 2 to 6 mm manufactured by the above process at a rolling reduction ratio of 10% or more, and the elongation anisotropy of the manufactured slabs can be improved through such hot rolling process. However, in order to obtain the effects of such hot rolling, a reduction ratio of at least 10% is required.
바람직하게는 상기 압하율을 10~50%로 제한하는 것이다.Preferably, the reduction ratio is limited to 10 to 50%.
본 발명에서는 상기와 같이 제조된 주편을 1000 ~ 1300℃ 온도범위에서 재가열한후, 열간압연할 수도 있으며, 아울러, 도 2와 같이 박판주조장치에 온라인으로 장착되어 있는 열간압연기(12)를 이용하여 열간압연을 행할 수도 있다.In the present invention, after reheating the cast slab manufactured as described above in the temperature range of 1000 ~ 1300 ℃, it may be hot rolled, and also, using a hot rolling mill 12 mounted online on the sheet casting apparatus as shown in FIG. Hot rolling may also be performed.
이후, 본 발명에서는 이러한 열간압연된 강판을 냉간압연하고, 이를 다시 재결정 열처리하여 최종 냉간압연 강판으로 제조한다. 이와 같이 제조된 본 발명의 고망간 박판은 높은 강도와 인성을 가질뿐만 아니라 연신율 이방성이 개선된 우수한 기계적특성을 가질 수 있다.Subsequently, in the present invention, the hot rolled steel sheet is cold rolled, and recrystallized and heat-treated again to prepare a final cold rolled steel sheet. Thus prepared high manganese thin plate of the present invention may have not only high strength and toughness but also excellent mechanical properties with improved elongation anisotropy.
이하, 실시예를 통하여 본 발명을 보다 상세히 설명한다.Hereinafter, the present invention will be described in more detail with reference to Examples.
(실시예)(Example)
표 1과 같은 조성을 갖는 고 망간강을 용해하고, 박판 연주기를 이용하여 두께 2.45 mm의 박판을 제조하였다. 이 때, 응고속도는 100oC/sec 이상으로, 메니스커스 실드 내부의 산소농도는 0.07% 이었고, 롤닙부에서의 압하력은 1.2 Ton 이었다.A high manganese steel having a composition as shown in Table 1 was dissolved, and a thin plate having a thickness of 2.45 mm was prepared using a thin plate player. At this time, the solidification rate was 100 ° C / sec or more, the oxygen concentration in the meniscus shield was 0.07%, the rolling force at the roll nip was 1.2 Ton.
이렇게 제조된 박판에 대하여 수지상정의 간격을 조사한 결과, 수지상정의 간격은 대부분 3.0 ~ 5.0 마이크론이었다.As a result of investigating the spacing of the dendrite with respect to the thin plate thus prepared, the spacing of the dendrite was mostly 3.0 to 5.0 microns.
그리고 이러한 박판주조법으로 제조된 고망간강 박판중 하나를 압하율 70%로 냉간압연하고, 이를 800℃ 2분간 열처리하여 최종 냉간압연 박판을 제조하였다.One of the high manganese steel sheets manufactured by the sheet casting method was cold rolled at a reduction ratio of 70%, and then heat-treated at 800 ° C. for 2 minutes to prepare a final cold rolled sheet.
이와 같이 제조한 냉간압연 박판의 광학현미경 사진을 도 3에 나타내었는데, 충분히 재결정이 일어난 조직을 보여주고 있으며, 이때의 결정입도는 대략 10um이하로 미세함을 알 수 있다. 아울러, 상기와 같이 얻어진 냉연강판을 인장시험하여 기계적 성질을 측정하였으며, 그 결과를 표 2에 나타내었다.The optical micrograph of the cold rolled thin plate thus prepared is shown in FIG. 3, showing a sufficiently recrystallized structure, and the grain size at this time is about 10 μm or less. In addition, the tensile properties of the cold rolled steel sheet obtained as described above were measured to measure the mechanical properties, the results are shown in Table 2.
한편, 박판주조법으로 제조된 고망간강 주조박판들을 1200℃로 재가열하고 표 2와 같은 압하율로 열간압연하였으며, 열간압연된 판재를 다시 70% 냉간압연한후, 800℃ 2분 재결정 열처리하여 최종 냉연판을 제조하였다. 이러한 열간압연단계를 거쳐 제조된 냉연강판의 기계적 성질을 측정하여, 그 결과를 표 2에 나타내었다.Meanwhile, the high-manganese steel cast sheets produced by the sheet casting method were reheated to 1200 ° C. and hot rolled at the reduction ratios as shown in Table 2. The hot rolled sheet was again cold-rolled by 70%, followed by recrystallization heat treatment at 800 ° C. for 2 minutes, and finally cold rolling. Plates were prepared. The mechanical properties of the cold rolled steel sheet manufactured through the hot rolling step were measured, and the results are shown in Table 2.
표 2에 나타난 바와 같이, 박판주조법으로 제조된 주편에 열간압연을 행하지 않은 비교예의 경우, 고망간강 박판의 강도가 높은 반면에 연신률은 T방향과 L 방향에 따라 심각한 이방성을 나타내었다. 다시 말하면, L 방향은 57 - 60%의 매우 우수한 성질을 보이는 반면에, T 방향은 10% 이하의 낮은 연신률을 보여 이방성이 심각하였다.As shown in Table 2, in the comparative example in which the hot-rolled slabs manufactured by the sheet casting method were not subjected to hot rolling, the high manganese steel sheet had high strength while the elongation exhibited severe anisotropy in the T and L directions. In other words, the L direction showed a very good property of 57-60%, while the T direction showed a low elongation of 10% or less, which showed severe anisotropy.
이에 반하여, 박판주조법으로 제조된 주편에 10% 이상의 압하율로 열간압연을 본 발명예의 경우, 제조된 박판의 강도가 높을뿐만 아니라 이방성이 현저히 개선됨을 나타내었다. 즉, 항복강도는 50 kg/mm2, 인장강도는 80 kg/mm2, 그리고 연신률은 T, L 방향 모두 55% 이상의 높은 연신률을 보여 매우 우수한 기계적 성질을 가지는 냉연강판을 얻을 수 있음을 알 수 있다.On the contrary, in the case of the present invention, hot rolling was carried out at a reduction ratio of 10% or more on the cast steel sheet produced by the sheet casting method, and the anisotropy was remarkably improved as well. In other words, the yield strength is 50 kg / mm 2 , the tensile strength is 80 kg / mm 2 , and the elongation is higher than 55% in both the T and L directions, resulting in a cold rolled steel sheet having excellent mechanical properties. have.
상술한 바와 같이, 본 발명은 박판주조법으로 얻어진 고망간강 박판주편을 다시 열간압연처리함으로써 우수한 강도와 인성뿐만 아니라 연신율 이방성을 현저하게 개선할 수 있는 고망간강 제조방법을 제공함에 유용한 효과가 있다.As described above, the present invention has a useful effect in providing a high manganese steel manufacturing method that can significantly improve the elongation anisotropy as well as excellent strength and toughness by hot-rolling the high manganese steel sheet cast obtained by the thin plate casting method.
또한 이러한 우수한 물성을 갖는 고망간을 자동차 제조에 이용함으로써 자동차 경량화와 배기가스량의 저감 뿐만 아니라, 연료절감에도 기여할 수 있는 효과가 있는 것이다.In addition, by using high manganese having such excellent physical properties in automobile manufacturing, there is an effect that can contribute to not only the weight reduction of the automobile and the reduction of the exhaust gas, but also the fuel saving.
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