KR100729123B1 - Manufacturing method of low carbon austenitic stainless steel - Google Patents
Manufacturing method of low carbon austenitic stainless steel Download PDFInfo
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- KR100729123B1 KR100729123B1 KR1020050116167A KR20050116167A KR100729123B1 KR 100729123 B1 KR100729123 B1 KR 100729123B1 KR 1020050116167 A KR1020050116167 A KR 1020050116167A KR 20050116167 A KR20050116167 A KR 20050116167A KR 100729123 B1 KR100729123 B1 KR 100729123B1
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- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 21
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 18
- 229910000963 austenitic stainless steel Inorganic materials 0.000 title claims abstract description 16
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 67
- 239000010959 steel Substances 0.000 claims abstract description 67
- 238000007670 refining Methods 0.000 claims abstract description 34
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 28
- 238000005266 casting Methods 0.000 claims abstract description 28
- 229910001220 stainless steel Inorganic materials 0.000 claims abstract description 27
- 239000010935 stainless steel Substances 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 19
- 238000002844 melting Methods 0.000 claims abstract description 17
- 230000008018 melting Effects 0.000 claims abstract description 16
- 238000005261 decarburization Methods 0.000 claims abstract description 9
- 238000009749 continuous casting Methods 0.000 claims abstract description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims abstract description 6
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 6
- VVTSZOCINPYFDP-UHFFFAOYSA-N [O].[Ar] Chemical compound [O].[Ar] VVTSZOCINPYFDP-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 6
- 239000011651 chromium Substances 0.000 claims abstract description 6
- 239000010936 titanium Substances 0.000 claims abstract description 6
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 6
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims abstract description 5
- 239000002994 raw material Substances 0.000 claims abstract description 4
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 3
- 239000002893 slag Substances 0.000 claims description 44
- 238000003756 stirring Methods 0.000 claims description 15
- 239000010459 dolomite Substances 0.000 claims description 10
- 229910000514 dolomite Inorganic materials 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 9
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 7
- 239000010436 fluorite Substances 0.000 claims description 7
- 239000010456 wollastonite Substances 0.000 claims description 6
- 229910052882 wollastonite Inorganic materials 0.000 claims description 6
- 230000004907 flux Effects 0.000 claims description 4
- 229910004261 CaF 2 Inorganic materials 0.000 claims description 3
- 239000011819 refractory material Substances 0.000 claims description 3
- 230000003749 cleanliness Effects 0.000 abstract description 10
- 239000012467 final product Substances 0.000 abstract description 2
- 230000007547 defect Effects 0.000 description 14
- 229910052782 aluminium Inorganic materials 0.000 description 11
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 9
- 239000010703 silicon Substances 0.000 description 9
- 229910052710 silicon Inorganic materials 0.000 description 9
- 230000008569 process Effects 0.000 description 6
- 238000000926 separation method Methods 0.000 description 6
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 229910052596 spinel Inorganic materials 0.000 description 5
- 239000011029 spinel Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 239000010960 cold rolled steel Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 229910005347 FeSi Inorganic materials 0.000 description 3
- 229910000676 Si alloy Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000011575 calcium Substances 0.000 description 3
- 239000000292 calcium oxide Substances 0.000 description 3
- 238000007667 floating Methods 0.000 description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910020068 MgAl Inorganic materials 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 229910052791 calcium Inorganic materials 0.000 description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- -1 magnesium aluminate Chemical class 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- 229910052761 rare earth metal Inorganic materials 0.000 description 2
- 150000002910 rare earth metals Chemical class 0.000 description 2
- 229910001339 C alloy Inorganic materials 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 235000012255 calcium oxide Nutrition 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 238000005345 coagulation Methods 0.000 description 1
- 230000015271 coagulation Effects 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000010405 reoxidation reaction Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/005—Manufacture of stainless steel
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/08—Making cast-iron alloys
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D19/00—Arrangements of controlling devices
- F27D2019/0028—Regulation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D27/00—Stirring devices for molten material
- F27D2027/002—Gas stirring
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Mechanical Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Treatment Of Steel In Its Molten State (AREA)
Abstract
본 발명은 0~30% 크롬과 5~15% 니켈을 함유하며, 타이타늄 함량이 50ppm이하이고 탄소함량이 300ppm이하인 원료를 전기로에서 용해하고 알곤-산소 탈탄법(AOD)으로 정련한 뒤 주조래들 처리를 거쳐 연속주조하는 저탄소 오스테나이트계 스테인레스강의 제조방법에 있어서, 상기 AOD정련로에서 상기 래들처리를 거치는 알루미나 농도를 저감시키는 단계; 및 상기 래들처리에서 상기 연속주조를 거치는 용강 개재물을 저하시키는 단계;를 포함하는 것을 특징으로 하여, 용강 중의 고융점 개재물 발생을 억제하고, 개재물수를 대폭 저감하여 최종 제품의 표면품질을 향상시킬 수 있는 저탄소 오스테나이트계 스테인레스강의 제조방법이다.The present invention contains 0-30% chromium and 5-15% nickel, and the raw material with titanium content of 50 ppm or less and carbon content of 300 ppm or less is melted in an electric furnace and refined by argon-oxygen decarburization (AOD) and then casting ladle A method of manufacturing a low carbon austenitic stainless steel that is continuously cast through a treatment, the method comprising: reducing the alumina concentration subjected to the ladle treatment in the AOD refining furnace; And reducing the molten steel inclusions subjected to the continuous casting in the ladle treatment, to suppress the occurrence of high melting point inclusions in the molten steel and to significantly reduce the number of inclusions to improve the surface quality of the final product. Low carbon austenitic stainless steel.
오스테나이트, 스테인레스강, 저탄소, 청정도, 표면품질 Austenitic, Stainless Steel, Low Carbon, Cleanliness, Surface Quality
Description
도 1은 일반적인 스테인레스강의 제조공정 중 일부를 나타낸 개략도,1 is a schematic view showing a part of a general manufacturing process of stainless steel,
도 2a는 스테인레스강의 경질 개재물의 형상을 나타낸 도면, Figure 2a is a view showing the shape of the hard inclusions of stainless steel,
도 2b는 경질 개재물에 의한 냉연 코일 표면의 결함을 나타낸 도면,2b shows a defect of a cold rolled coil surface with hard inclusions,
도 3은 용강 중 개재물이 생성되는 기구가 개략적으로 도시된 도면,3 is a view schematically showing a mechanism for generating inclusions in molten steel;
도 4는 본 발명의 실시예 및 종래기술에 따른 스테인레스강의 결함지수가 도시된 그래프도면.Figure 4 is a graph showing the defect index of the stainless steel according to the embodiment of the present invention and the prior art.
본 발명은 저탄소 오스테나이트계 스테인레스강의 제조방법에 관한 것으로, 특히 전기로에서 용해된 원료를 알곤-산소 탈탄법(AOD)으로 정련하고 주조래들에서 성분 및 온도 조정한 후 연속주조하는 스테인레스강 정련방법에 있어서, 정련로의 슬래그 염기도(칼슘산화물(CaO)와 실리콘산화물(SiO2)의 비)와 용강 온도를 제어하고, 주조래들의 내화물을 제한하고 래들에서 성분 및 온도 조정 시 슬래그의 유동 성을 높이고 래들 하부로부터 Ar 가스를 취입하여 용강 중 개재물의 부상분리를 용이하게 하고, 주조온도를 조정하여 개재물을 최소화시킴으로써 스테인레스 제품 가공시 개재물에 의해 발생하는 표면 결함을 방지할 수 있도록 하는 것이다.The present invention relates to a method for producing low carbon austenitic stainless steel, in particular, a raw material dissolved in an electric furnace by argon-oxygen decarburization (AOD) and stainless steel refining method of continuous casting after adjusting the components and temperature in the casting ladle To control slag basicity (ratio of calcium oxide (CaO) and silicon oxide (SiO 2 )) and molten steel temperature in the refining furnace, to limit the refractory of the cast ladle and to control the flow of slag when adjusting the components and temperature in the ladle. By raising the Ar gas from the bottom of the ladle to facilitate the separation of the inclusions in the molten steel, and to minimize the inclusions by adjusting the casting temperature to prevent surface defects caused by the inclusions in the processing of stainless products.
일반적으로 오스테나이트계 스테인레스강은 표면 품질이 매우 중요하며, 특히 저탄소 스테인레스강은 연성이 우수해서 쉽게 표면 결함이 일어나는 특성이 있다. 이러한 저탄소 스테인레스강의 표면 결함에 영향을 미치는 인자에는 여러가지가 있지만 그 중에서도 고융점 비금속 개재물의 조성 및 개수 등이 큰 문제가 되고 있다. 즉, 개재물이 제품의 표면에 잔류해 있을 경우 표면을 손상시키거나 균열발생의 원인이 되는 것이다. 그러나, 비금속 개재물은 용강의 탈산 과정과 슬래그 혼입, 재산화 등에 의해서 필연적으로 발생되기 때문에 개재물의 조성을 저융점화하고, 개수를 최소화시키는 방법이 요구되고 있다.In general, austenitic stainless steel has a very important surface quality, especially low carbon stainless steel has excellent ductility, so that the surface defects easily occur. There are many factors affecting the surface defects of such low carbon stainless steel, but among them, the composition and the number of the high melting point non-metallic inclusions are a big problem. In other words, if an inclusion remains on the surface of the product, it may damage the surface or cause cracking. However, since non-metallic inclusions are inevitably generated by deoxidation of molten steel, incorporation of slag, reoxidation, etc., there is a demand for a method of lowering the composition of the inclusions and minimizing the number of inclusions.
스테인레스강의 알곤-산소 탈탄법(AOD)에 의한 정련시에는 산소가스를 용강 중에 취입하여 탄소를 제거하기 때문에 크롬산화물이 생성되며, 이를 환원시키기 위해서 CaO를 주성분으로 하는 염기성 플럭스와 함께 탈산제로써 실리콘 합금(FeSi)을 첨가하고, 탈산 및 개재물의 제거를 촉진하기 위해서 불활성 가스로 용강을 교반시킨다. 그러나 이와 같은 실리콘의 투입에 의한 탈산의 경우, 하기 식 1의 반응에 의해 실리카(SiO2)가 생성되고, 실리콘 합금 내 존재하는 알루미늄이 식 2의 반응에 의해 알루미나(Al2O3)로 되어 용강 내에는 고융점 개재물이 필연적으로 존재하게 된다.In the case of refining stainless steel by argon-oxygen decarburization (AOD), chromium oxide is produced because oxygen gas is blown into molten steel to remove carbon, and silicon alloy is used as deoxidizer together with basic flux containing CaO as a main component to reduce this. (FeSi) is added and the molten steel is stirred with an inert gas to promote deoxidation and removal of inclusions. However, in the case of deoxidation by the addition of silicon, silica (SiO 2 ) is produced by the reaction of Equation 1 below, and the aluminum present in the silicon alloy becomes alumina (Al 2 O 3 ) by the reaction of
[식 1][Equation 1]
[Si] + 2[O] = (SiO2)[Si] + 2 [O] = (SiO 2 )
[식 2][Equation 2]
2[Al] + 3[O] = (Al2O3)2 [Al] + 3 [O] = (Al 2 O 3 )
상기와 같이 생성된 미세한 비금속 개재물들은 1600~1700℃의 용강 내부에서 미세한 고체 입자로 부유하므로, 각 입자들간의 응집, 성장이 어렵고, 부력에 의해 용강 상부로 떠올라 제거되지 못하고 계속 용강 중에 체류하게 된다. 이 개재물들은 AOD 정련로에서 주조래들로 출강될 때, 용강 내로 혼입된 슬래그와 서로 반응하면서 CaO-SiO2-Al2O3-MgO계 저융점 개재물로 변화한다. 그러나 용강 중 알루미늄은 용강 온도 하강에 의해 용해도가 낮아지기 때문에 용강 중 산소와 결합하여 알루미나화 하면서 개재물을 다시 고융점 개재물로 변화시키고, 최종적으로 제품 표면 품질에 악영향을 미치는 슬래그성 개재물과 고융점 스피넬 개재물의 석출상이 결합되어 있는 형상을 보이게 된다. 이러한 개재물의 성분과 개수, 크기 등을 제어하기 위해 여러가지 기술들이 적용되어 왔으나, 이를 실제 공정에 적용하기에는 어려움이 따른다.Since the fine non-metallic inclusions produced as described above are suspended as fine solid particles in the molten steel at 1600-1700 ° C., the coagulation and growth between the particles are difficult and do not float to the upper part of the molten steel by buoyancy and remain in the molten steel. . When these inclusions are cast into cast ladles in an AOD refining furnace, they react with the slag incorporated into the molten steel and change to CaO-SiO 2 -Al 2 O 3 -MgO-based low melting point inclusions. However, aluminum in molten steel has low solubility due to the temperature drop of molten steel, so that the inclusions are transformed into high melting point inclusions by alumina in combination with oxygen in molten steel, and finally slag inclusions and high melting point spinel inclusions that adversely affect the product surface quality. The precipitated phase of the combined shape is shown. Various techniques have been applied to control the composition, number, size, and the like of such inclusions, but it is difficult to apply them to actual processes.
대한민국특허 제2002-0022275호는 진공정련 및 대기압 하에서 오스테나이트 스테인레스 용강의 교반강도를 낮추어 슬래그성 개재물이 용강으로 혼입되는 것을 방지할 수는 있으나, 저탄소 용강과 같이 개재물이 많이 존재할 경우에는 개재물을 부상시켜 제거시키는 것이 더 중요하다. 대한민국특허 제2001-0063536호는 대형 개 재물 형성 방지를 위하여 탈탄 및 실리콘 탈산 후, 실리콘과 알루미늄의 비를 90~180 범위로 하고, 알루미늄 투입과 동시에 슬래그 염기도를 2.3~3.5가 되도록 제어하여, 고Si 함유 스테인레스강에서 높은 청정도를 얻는 것으로써, 특수한 강종에만 가능한 방법으로 일반적인 적용에는 한계가 있다. Korea Patent No. 2002-0022275 can reduce the agitation strength of austenitic stainless molten steel under vacuum refining and atmospheric pressure to prevent the inclusion of slag inclusions into molten steel. More importantly. Korean Patent No. 2001-0063536 discloses a ratio of silicon to aluminum in the range of 90 to 180 after decarburization and silicon deoxidation to prevent formation of large inclusions, and the slag basicity is controlled to be 2.3 to 3.5 at the same time as aluminum is injected. By obtaining high cleanliness in Si-containing stainless steels, there is a limit to general applications in a way that is possible only for special steel grades.
또한, 대한민국특허 제2004-0056706호는 개재물 중 알루미나의 농도를 감소시키기 위해 돌로마이트 래들을 이용하는 방법을 제시하고 있으나, 용강 중 개재물의 수를 줄이기에는 곤란하다. 일본특허 제2001-164312호는 산화정련 후에 실리콘 및 타이타늄에 의해 탈산하여, 실리콘 함유량을 0.4%이하로 하고 타이타늄 함량을 0.001/[%질소] 이하로 조절하여 청정도를 향상시킴으로써 연속주조 시 노즐 막힘을 해소하는 방법으로 타이타늄 함량이 높은 경우에만 적용이 가능하고 안정적으로 제어하기 곤란하며 근본적인 청정도 향상 방법으로 보기 어렵다. 일본특허 특개평11-199917호는 실리콘으로 탈산하는 오스테나이트계 스테인레스강에 있어서 칼슘과 희토류금속(REM)을 복합 첨가하여 개재물 성상을 저융점 복합산화물화하여 응고조직 중 비금속개재물을 무해화하는 것으로 성분제어가 매우 어려워 현실성이 없고, 노즐 막힘의 우려가 있다. 일본특허 특개평07-188861호는 Al 함량이 적은 FeSi을 이용하여 용강 중 Al을 조정하고 Ca을 첨가하고 교반시간을 적정히 선정하여 개재물 부상분리를 행하는 방법을 제시하고 있으나 원료 중의 Al을 규제하는 것이 실제 스테인레스강 제조공정에서는 매우 어렵다. 일본 특허 특개평03-267312호, 특개평10-158720호 및 프랑스특허 E.I.7603020603호에서는 정련로 슬래그의 염기도와 슬래그 중 알루미나와 마그네시아의 농도를 규제함으로써 고융점 개재물의 생성을 방지할 수 있다고 하지만, 정련로 슬래그의 조성만을 조정해서는 고융점 개재물의 생성을 억제하기 힘들고 용강 중 칼슘과 산소의 농도비만을 제어할 경우 개재물 형상 제어의 가능성이 낮다.In addition, Korean Patent No. 2004-0056706 discloses a method of using a dolomite ladle to reduce the concentration of alumina in inclusions, but it is difficult to reduce the number of inclusions in molten steel. Japanese Patent No. 2001-164312 deoxidizes with silicon and titanium after oxidative refining to improve the cleanliness by adjusting the silicon content to 0.4% or less and the titanium content to 0.001 / [% nitrogen] or less to improve nozzle clogging during continuous casting. It can be applied only when the titanium content is high as a solution to solve the problem, it is difficult to control stably, and it is difficult to see it as a fundamental improvement method of cleanliness. Japanese Patent Application Laid-Open No. 11-199917 discloses that in austenitic stainless steel deoxidized with silicon, calcium and rare earth metals (REM) are added in combination to make the inclusion properties low-melting complex oxide, thereby making non-metallic inclusions in the solidified structure harmless. Component control is very difficult, so there is no practicality, and there is a fear of clogging the nozzle. Japanese Patent Application Laid-Open No. 07-188861 proposes a method of adjusting Al in molten steel using FeSi having a low Al content, adding Ca, and selecting an agitation time to perform floating separation of inclusions. This is very difficult in the actual stainless steel manufacturing process. In Japanese Patent Laid-Open Nos. 03-267312, 10-158720 and French Patent EI7603020603, the formation of high melting point inclusions can be prevented by regulating the basicity of slag and the concentration of alumina and magnesia in the slag. It is difficult to suppress the formation of high melting point inclusions only by adjusting the composition of refining furnace slag, and when controlling only the concentration ratio of calcium and oxygen in molten steel, the possibility of inclusion shape control is low.
따라서, 본 발명은 전술한 종래의 문제점들을 해결하기 위해 고안된 발명으로, 저탄소 오스테나이트계 스테인레스강의 정련방법에 있어서, 탈탄 및 탈산 과정 후 주조래들로 옮겨진 용강에 대해서, 개재물을 무해화 시킴과 동시에 최대한 부상분리시켜서 포집하므로써, 스테인레스강의 청정도를 향상시킬 수 있는 기술을 제공하고자 한다. 이러한 정련기술을 통해 고융점 개재물의 발생을 억제하여 스테인레스강 가공 시에 개재물의 연성을 향상시키고, 개재물의 수를 최대한 감소하여 개재물에 기인한 표면 결함을 감소시킬 수 있는 저탄소 오스테나이트계 스테인레스강의 제조방법을 제공하는데 발명의 목적이 있다.Therefore, the present invention is an invention designed to solve the above-mentioned conventional problems. In the refining method of low carbon austenitic stainless steel, the molten steel transferred to the casting ladle after the decarburization and deoxidation process is made harmless to the inclusions. It is to provide a technology that can improve the cleanliness of stainless steel by separating and collecting as much as possible. Through this refining technology, the production of low-carbon austenitic stainless steel that can suppress the occurrence of high melting point inclusions, improve the ductility of inclusions when processing stainless steel, and reduce the surface defects caused by inclusions by reducing the number of inclusions as much as possible. It is an object of the invention to provide a method.
상술한 목적을 달성하기 위하여, 본 발명에 따른 저탄소 오스테나이트계 스테인레스강의 청정도 향상방법은, 10~30% 크롬과 5~15% 니켈을 함유하며, 타이타늄 함량이 50ppm이하이고 탄소함량이 300ppm이하인 원료를 전기로에서 용해하고 알곤-산소 탈탄법(AOD)으로 정련한 뒤 주조래들 처리를 거쳐 연속주조하는 저탄소 오스테나이트계 스테인레스강의 제조방법에 있어서, 상기 AOD정련로에서 상기 래들처리를 거치는 알루미나 농도를 저감시키는 단계; 및 상기 래들처리에서 상기 연속주조를 거치는 용강 개재물을 저하시키는 단계;를 포함하는 것을 특징으로 한다.In order to achieve the above object, the method for improving the cleanliness of the low carbon austenitic stainless steel according to the present invention, containing 10 to 30% chromium and 5 to 15% nickel, titanium content of 50ppm or less and carbon content of 300ppm or less In the manufacturing method of low-carbon austenitic stainless steel in which a raw material is dissolved in an electric furnace, refined by argon-oxygen decarburization (AOD), and then continuously cast through a casting ladle, the alumina concentration subjected to ladle treatment in the AOD refining furnace Reducing the; And lowering the molten steel inclusion undergoing the continuous casting in the ladle treatment.
여기서, 상기 알루미나 농도를 저감시키는 단계는, 상기 AOD정련로의 슬래그 염기도를 1.7~1.8로 조정하고, 상기 슬래그 중 알루미나 농도를 3% 이하로 하며, 상기 래들 내화물의 재료로써 돌로마이트재를 사용하는 것을 특징으로 한다.Here, the step of reducing the alumina concentration, the slag basicity of the AOD refining furnace is adjusted to 1.7 ~ 1.8, the alumina concentration of the slag to 3% or less, using a dolomite material as the material of the ladle refractory material It features.
또한, 상기 용강 개재물을 저하시키는 단계는, 상기 AOD정련로 조업 후의 용강 온도를 1700~1750℃로 제한하며, 상기 주조래들 슬래그의 염기도를 1.5~1.6으로 조정하고, 용강 교반 시간을 15~20분으로 하면서 용강 교반 강도를 압력단위로 3.5~4bar가 되도록 하여, 주조 대기 시간을 20분 이상으로 하면서 주조 온도를 스테인레스강의 용융온도보다 40~50℃ 높게 제어하는 것을 특징으로 하며, 이때, 상기 래들 슬래그의 염기도는, 상기 래들의 슬래그 무게를 용강 무게의 1.5~2.0%가 되도록 조절하고, 규회석(CaO-SiO2계 플럭스)과 형석(CaF2)을 상부로부터 투입함으로써 이루어진다.In addition, the step of lowering the molten steel inclusions, limiting the molten steel temperature after the operation of the AOD refining furnace to 1700 ~ 1750 ℃, adjust the basicity of the cast ladle slag to 1.5 ~ 1.6, molten steel stirring time 15 ~ 20 It is characterized in that the molten steel stirring strength is set to 3.5 ~ 4bar in pressure unit while the minutes, the casting standby time is 20 minutes or more while controlling the casting temperature 40 ~ 50 ℃ higher than the melting temperature of stainless steel, wherein the ladle The slag basicity is made by adjusting the slag weight of the ladle so as to be 1.5 to 2.0% of the molten steel weight and injecting wollastonite (CaO-SiO 2 based flux) and fluorite (CaF 2 ) from the top.
이하, 본 발명의 바람직한 실시예에 따른 저탄소 오스테나이트계 스테인레스강의 제조방법을 첨부된 도면을 참조하여 상세히 설명한다.Hereinafter, a method of manufacturing a low carbon austenitic stainless steel according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.
도 1은 일반적인 스테인레스강의 제조공정 중 일부를 나타낸 개략도이며, 도 2a는 스테인레스강의 경질 개재물의 형상을 나타낸 도면이고, 도 2b는 경질 개재물에 의한 냉연 코일 표면의 결함을 나타낸 도면이다.1 is a schematic view showing a part of a general stainless steel manufacturing process, Figure 2a is a view showing the shape of the hard inclusions of stainless steel, Figure 2b is a view showing a defect of the cold rolled coil surface by the hard inclusions.
스테인레스강 제조 시 전기로를 거쳐 AOD정련로에서 탈탄할 때에, 크롬, 철 등의 유가금속들이 산화되어 용강 성분의 손실을 야기한다. 따라서, 이들의 환원제 로써 실리콘 합금(FeSi)을 이용하며, 이 경우, 도 2a와 같은 형상의 고융점의 마그네슘 알루미네이트계의 스피넬(MgAl2O4) 개재물이 발생하여, 도 2b에 나타난 것과 같은 제품의 표면 결함 또는 가공 시의 균열을 야기한다. When decarburizing an AOD refining furnace via an electric furnace in the production of stainless steel, valuable metals such as chromium and iron are oxidized to cause loss of molten steel components. Therefore, silicon alloys (FeSi) are used as these reducing agents, and in this case, high melting point magnesium aluminate-based spinel (MgAl 2 O 4 ) inclusions as shown in FIG. 2A are generated, as shown in FIG. 2B. It causes surface defects in the product or cracks during processing.
이러한 스테인레스강의 정련과정에서의 개재물 생성 원인은 다음과 같다. The cause of inclusions in the refining process of the stainless steel is as follows.
정련로 환원기에 환원제로 투입된 실리콘은 산소와 반응하여 실리카(SiO2)를 형성한다. 실리콘을 환원제로 이용하는 경우에도, 알루미늄 함유 물질을 포함하고 있기 때문에 용강 중 알루미늄의 농도가 일정치 이상이 되는 경우에는 마그네슘 알루미네이트계 스피넬 또는 알루미나(Al2O3) 개재물이 생성된다. Silicon injected as a reducing agent in the refining furnace reducer reacts with oxygen to form silica (SiO 2 ). Even when silicon is used as the reducing agent, since the aluminum-containing material is contained, when the concentration of aluminum in the molten steel is higher than or equal to a predetermined value, magnesium aluminate-based spinel or alumina (Al 2 O 3 ) inclusions are produced.
또한, 환원 정련 과정과 정련로에서 주조래들로 옮겨지는 과정에서 용강 중으로 슬래그가 현탁하게 되는데, 이 현탁된 슬래그 입자들이 개재물 성장의 핵으로서 작용하게 된다. 실리카와 스피넬, 알루미나 및 슬래그 입자들이 서로 반응하여 개재물을 이루게 되며, 주조 래들로 옮겨진 용강의 온도가 주조 공정에서 응고될 때까지 지속적으로 하강하면서 알루미늄의 산화반응이 개재물의 조성 변화를 일으켜, 개재물 중 알루미나의 농도를 높이게 된다. In addition, slag is suspended in molten steel during the reduction refining process and the transfer from the refining furnace to the casting ladle, and the suspended slag particles act as nuclei for inclusion growth. Silica, spinel, alumina and slag particles react with each other to form inclusions, and the oxidation of aluminum causes a change in the inclusions as the temperature of the molten steel transferred to the casting ladle continues to drop until it solidifies in the casting process. It will increase the concentration of alumina.
이러한 과정이 도 3에 개략적으로 도시되어 있다.This process is schematically illustrated in FIG. 3.
이때 개재물 중 알루미나의 농도는 슬래그 염기도, 용강 중 알루미늄 농도, 래들 내화물의 재료, 슬래그 중 알루미나의 농도에 의존한다. 한편 용강 청정도에 가장 큰 영향을 미치는 용강 중 개재물의 수는 슬래그 염기도, AOD 조업 후의 온도, 용강 교반 시간, 용강 교반 강도, 주조 대기 시간 및 주조 온도에 의존한다. The concentration of alumina in the inclusion depends on the slag basicity, the aluminum concentration in molten steel, the material of the ladle refractory, and the concentration of alumina in the slag. On the other hand, the number of inclusions in molten steel that has the greatest influence on the cleanliness of molten steel depends on slag basicity, temperature after AOD operation, molten steel stirring time, molten steel stirring strength, casting waiting time and casting temperature.
따라서, 본 발명은 크게 개재물 중 알루미나의 농도를 저감하는 방법과 용강 중 개재물의 수를 줄이는 방법으로 구성된다. Accordingly, the present invention is largely composed of a method of reducing the concentration of alumina in inclusions and a method of reducing the number of inclusions in molten steel.
개재물 중 알루미나의 농도를 저감하기 위해서 정련로의 슬래그 염기도를 1.7~1.8로 조정하고, 용강 중 알루미늄 농도를 30ppm 이하로 한정하고, 래들 내화물의 재료로써 돌로마이트재를 사용하고, 정련로 슬래그 중 알루미나의 농도를 3% 이하로 조절해야 한다. In order to reduce the concentration of alumina in the inclusions, the slag basicity of the refining furnace is adjusted to 1.7 to 1.8, the aluminum concentration in the molten steel is limited to 30 ppm or less, the dolomite material is used as the material of the ladle refractories, and the alumina in the refining slag is used. The concentration should be adjusted below 3%.
또한, 용강 중 개재물의 수를 줄이기 위해서 주조래들 슬래그의 염기도를 1.5~1.6으로 조정하고, 정련로 조업 후의 용강 온도를 1700~1750℃로 제한하고, 용강 교반 시간을 15~20분으로 하면서 용강 교반 강도를 압력단위로 3.5~4bar가 되도록 조정해야 하고, 주조 대기 시간을 20분 이상으로 하면서 주조 온도를 스테인레스강의 용융온도(1450℃)보다 40~50℃ 높게 제어하여야 한다.In addition, in order to reduce the number of inclusions in the molten steel, the basicity of the cast ladle slag is adjusted to 1.5 to 1.6, the molten steel temperature after the refining operation is limited to 1700 to 1750 ° C, and the molten steel stirring time is set to 15 to 20 minutes. The stirring strength should be adjusted to 3.5 ~ 4bar in pressure unit, and the casting temperature should be controlled 40 ~ 50 ℃ higher than the melting temperature (1450 ℃) of stainless steel while the casting waiting time is 20 minutes or more.
본 발명에서 정련로의 슬래그 염기도를 1.7~1.8로 한정한 것은 염기도 1.8 초과에서는 개재물 중 스피넬(MgAl2O4) 개재물 발생율이 급격히 증가하기 때문이며, 슬래그 염기도 1.7 미만에서는 용강 중 산소가 높아져서 강 중의 개재물수를 증가시키고, 슬래그의 유황 제거 능력을 현저하게 감소시켜 스테인레스강의 표면품질을 저하시킨다. 또한, 정련로 슬래그 중 알루미나의 농도가 3% 초과하여 증가한 경우에는 용강 중 알루미늄의 농도증가를 야기시키고 결과적으로 개재물의 알루미나 농도를 증가시키게 된다.In the present invention, the slag basicity of the refining furnace is limited to 1.7 to 1.8 because the incidence rate of spinel (MgAl 2 O 4 ) inclusions among the inclusions increases sharply above the basicity of 1.8, and the oxygen inclusions in the molten steel increase when the slag baseness is less than 1.7. Increasing the number and significantly reducing the slag's ability to remove sulfur deteriorates the surface quality of stainless steels. In addition, when the concentration of alumina in the refining slag increases by more than 3%, it causes an increase in the concentration of aluminum in the molten steel and consequently increases the alumina concentration of inclusions.
또한, 주조래들 내화물로 알루미나계열의 산화물을 사용할 경우, 내화물이 슬래그와 반응하여 슬래그 중 알루미나(Al2O3)의 농도가 높아지게 되며, 용강 중 알루미늄의 농도를 증가시켜 결과적으로 개재물의 알루미나 농도를 증가시키기 때문 에 돌로마이트재 내화물을 사용하는 것이 바람직하다. In addition, when an alumina-based oxide is used as the casting ladle refractory, the refractory reacts with the slag, thereby increasing the concentration of alumina (Al 2 O 3 ) in the slag, increasing the concentration of aluminum in the molten steel, and consequently the alumina concentration of the inclusions. It is preferable to use a dolomite material refractory because it increases.
한편, 슬래그의 염기도를 1.5~1.6으로 조정할 경우 용강 내 부유하는 미세한 슬래그 입자들의 응집이 용이해져서 부상분리에 의한 개재물 제거가 원활해진다. 따라서, 정련로에서 주조래들로 이송한 후, 주조래들의 슬래그 무게를 용강 무게의 1.5~2.0%가 되도록 조절하고, 규회석(CaO-SiO2계 플럭스, CaO/SiO2=0.8~1.0)과 형석(CaF2)을 상부로부터 투입하여 슬래그의 염기도를 조정하여야 한다. On the other hand, when the slag basicity is adjusted to 1.5 to 1.6, the flocculation of the fine slag particles suspended in the molten steel is facilitated, and the removal of inclusions by floating separation is smoothed. Therefore, after the transfer from the refining furnace to the casting ladle, the slag weight of the casting ladle is adjusted to 1.5 ~ 2.0% of the molten steel, and the wollastonite (CaO-SiO 2 flux, CaO / SiO 2 = 0.8 ~ 1.0) and Fluorite (CaF 2 ) should be added from the top to adjust the slag basicity.
정련로 조업 후의 용강 온도를 1700℃이상으로 할 경우 개재물의 부상분리 속도를 크게 증가시키나, 1750℃ 초과에서는 내화물의 용손이 심해져서 용강의 청정도를 악화시킨다. 또한, 용강 교반 시간을 15~20분으로 하면서 용강 교반 강도를 압력단위로 3.5~4bar가 되도록 조정해야 충분한 개재물의 부상분리가 이루어진다. 이때, 용강 교반 강도가 3.5bar 미만인 경우에는 개재물의 부상분리가 이루어지지 않을 정도로 교반 효율이 감소하고 또한 4bar 초과인 경우에는 용강의 교반이 과도하여 용강이 주조래들에서 넘치는 현상이 발생하게 된다. 주조 대기 시간을 20분 이상으로 하면서 주조 온도를 스테인레스강의 용융온도(1450℃)보다 40~50℃ 높게 제어하여야 스테인레스강의 고청정성을 확보할 수 있다.When the temperature of molten steel after the refining operation is higher than 1700 ° C, the flotation separation rate of inclusions is greatly increased, but when the temperature of molten steel is higher than 1750 ° C, melting of the refractory becomes severe and worsens the cleanliness of the molten steel. In addition, while the molten steel stirring time to 15 to 20 minutes, the molten steel stirring strength should be adjusted to 3.5 to 4 bar in pressure units to achieve sufficient separation of inclusions. In this case, when the stirring strength of the molten steel is less than 3.5bar, the stirring efficiency is reduced to the extent that no floating separation of the inclusions is made, and when the molten steel is more than 4bar, the stirring of the molten steel is excessive, so that the molten steel overflows from the casting ladle. The casting wait time is 20 minutes or more and the casting temperature is controlled to be 40 ~ 50 ℃ higher than the melting temperature (1450 ℃) of stainless steel to ensure high cleanliness of stainless steel.
이하 본 발명의 실시예를 설명한다.Hereinafter, embodiments of the present invention will be described.
[실시예]EXAMPLE
도 1에 도시된 바와 같은 전기로-AOD 정련로-주조래들-연속주조 공정을 통한 저탄소 오스테나이트계 스테인레스강(18.5%Cr)의 제조 공정에서 스크랩, 페로크롬(FeCr)을 원료로 하여 90톤 전기로에서 용해하고, AOD 정련로에서 알곤-산소 혼합가스를 이용한 탈탄 정련을 실시하였다. 탈탄 정련 후 산화된 크롬을 환원 및 회수 하기 위하여 실리콘과 함께 생석회와 형석을 첨가하고, 알곤 가스를 불어 환원 정련을 행한 후 주조래들로 이송하였다. 주조래들에서는 용강상부의 슬래그를 용강무게의 1.5~2.0%가 되도록 제거하고 규회석과 형석을 투입하여 슬래그의 염기도를 1.5~1.6이 되도록 조절하였다. 알곤 가스를 래들 하부로부터 3.5~4bar가 되도록 15~20분간 취입하여 교반을 실시하면서 최종 성분 및 온도 조정을 행하였다. In the manufacturing process of low-carbon austenitic stainless steel (18.5% Cr) through an electric furnace-AOD refining furnace-casting ladle-continuous casting process as shown in FIG. It melt | dissolved in the tone electric furnace, and decarburization refine | purification using the argon-oxygen mixed gas was performed in the AOD refinery. In order to reduce and recover the oxidized chromium after decarburization, quicklime and fluorite are added together with silicon, and argon gas is blown to reduce refining and then transferred to the casting ladle. In the casting ladle, the slag of the upper part of the molten steel was removed to 1.5-2.0% of the molten steel weight, and the basicity of the slag was adjusted to 1.5-1.6 by adding wollastonite and fluorspar. Argon gas was blown for 15 to 20 minutes from the bottom of the ladle to 3.5 to 4 bar, and final components and temperature were adjusted while stirring.
그 후 연속주조와 열간압연 및 냉간압연을 거쳐 스테인레스강의 냉연강판을 제조하였고 냉연강판의 표면을 육안검사하여 냉연강판 표면의 개재물에 의해 발생한 결함의 발생율을 조사하여 이를 0에서 10사이의 수준으로 구분한 스테인레스강의 결함 지수로 나타내었다. After that, stainless steel cold rolled steel was manufactured through continuous casting, hot rolling, and cold rolling. The surface of the cold rolled steel sheet was visually inspected to investigate the incidence of defects caused by inclusions on the surface of the cold rolled steel sheet. It is represented by the defect index of one stainless steel.
하기 표1에 실시예에서 사용한 저탄소 오스테나이트 스테인레스강의 성분을 나타내었다.Table 1 shows the components of the low carbon austenitic stainless steel used in the examples.
하기 표 2에 실험조건과 그에 따른 냉연강판 표면의 결함지수를 나타내었다.Table 2 shows the experimental conditions and the defect index of the resulting cold rolled steel sheet.
본 발명의 실시예 및 종래기술의 예를 비교해 보면, 본 발명에 따른 스테인레스강에서의 결함지수가 현저히 개선된 것을 알 수 있다. 평균 7.1이었던 결함지수가 평균 1.0으로 대폭 낮아져서 스테인레스강의 청정도가 60%정도 향상되었음을 알 수 있다. 상기 표 2의 결과는 도 4에 그래프로 도시되었으며, 이로부터 본 발명에 의한 용강 중 개재물 저감효과의 타당성을 입증할 수 있다. 또한 도 4로부터 냉연코일 간의 결함지수 편차도 크게 줄어든 것을 알 수 있어, 조업 관리 측면에서도 매우 유리하다는 것을 알 수 있다.Comparing the embodiment of the present invention and the example of the prior art, it can be seen that the defect index in the stainless steel according to the present invention is significantly improved. The defect index, which was 7.1 on average, was drastically lowered to 1.0, indicating that the cleanliness of stainless steel was improved by 60%. The results of Table 2 are shown in a graph in Figure 4, from which it can be demonstrated the validity of the inclusion reduction effect in the molten steel according to the present invention. In addition, it can be seen that the deviation of the defect index between the cold rolled coil is greatly reduced, it is also very advantageous in terms of operation management.
본 발명의 기술 사상은 상기 바람직한 실시예에 따라 구체적으로 기술되었으나, 상기한 실시예는 그 설명을 위한 것이며, 그 제한을 위한 것이 아님을 주지해야 한다. 또한, 본 발명의 기술분야에서 당업자는 본 발명의 기술 사상의 범위 내에서 다양한 실시예가 가능함을 이해할 수 있을 것이다.Although the technical spirit of the present invention has been described in detail according to the above-described preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, those skilled in the art will understand that various embodiments are possible within the scope of the technical idea of the present invention.
이상에서 설명한 바와 같이, 본 발명에 의한 저탄소 오스테나이트계 스테인레스강의 제조방법에 의하여 AOD정련로 환원 후의 슬래그 염기도 및 래들 정련 시의 규회석과 형석 투입, 교반 강도와 시간, 용강 온도 조절 등을 행함으로써, 용강 중의 고융점 개재물 발생을 억제하고, 개재물수를 대폭 저감하여 최종 제품의 표면품질을 향상시키는 효과가 있다.As described above, the slag basicity after reduction by AOD refining and wollastonite and fluorite in ladle refining, stirring strength and time, molten steel temperature control, etc. are carried out by the method for producing low carbon austenitic stainless steel according to the present invention. There is an effect of suppressing the occurrence of high melting point inclusions in the molten steel, significantly reducing the number of inclusions to improve the surface quality of the final product.
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| EP3358029A4 (en) * | 2015-09-29 | 2019-05-22 | Nisshin Steel Co., Ltd. | HIGH STRENGTH STAINLESS STEEL SHEET HAVING EXCELLENT FATIGUE CHARACTERISTICS AND METHOD FOR MANUFACTURING THE SAME |
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