KR101130724B1 - A method for grain-oriented electrical steel sheet with uniform magnetic properties - Google Patents
A method for grain-oriented electrical steel sheet with uniform magnetic properties Download PDFInfo
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- 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
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
- C21D8/1222—Hot rolling
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- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- 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
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- 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
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
- C21D8/1255—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest with diffusion of elements, e.g. decarburising, nitriding
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- 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
- C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
- C21D8/1277—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular surface treatment
- C21D8/1283—Application of a separating or insulating coating
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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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
Abstract
본 발명은 전기강판을 제조함에 있어 열간압연시 마무리압연의 압연율을 적절히 배분하여 코일내의 자성편차를 줄여서 안정적인 자기적 성질을 확보할 수 있는 방향성 전기강판의 제조방법에 관한 것이다. The present invention relates to a method of manufacturing a grain-oriented electrical steel sheet that can secure a stable magnetic properties by reducing the magnetic deviation in the coil by appropriately distributing the rolling ratio of the finish rolling during hot rolling in the production of electrical steel sheet.
본 발명은 중량%로, Si: 2.5～4%, C:0.02~0.08%, Mn: 0.05～0.5, sol-Al:0.023~0.035%, N:0.002~0.01%, P: 0.015～0.035%, S: 0.004～0.010%, 로 이루어지는 슬라브를 1100~1250℃로 재가열하고, 조압연 및 마무리압연으로 이루어지는 열간압연을 실시한 다음, 열연판소둔을 실시하고 냉간압연하여 최종 두께로 한 다음 1차재결정을 겸한 탈탄 및 질화소둔 처리를 동시에 하고 최종 마무리 고온소둔하는 방향성 전기강판의 제조방법에 있어서, In the present invention, by weight%, Si: 2.5-4%, C: 0.02-0.08%, Mn: 0.05-0.5, sol-Al: 0.023-0.035%, N: 0.002-0.01%, P: 0.015-0.035%, S: The slab consisting of 0.004 ~ 0.010%, is reheated to 1100 ~ 1250 ℃, hot rolling consisting of rough rolling and finishing rolling, followed by hot rolling annealing, cold rolling to final thickness and primary recrystallization. In the method of manufacturing a grain-oriented electrical steel sheet subjected to both decarburization and nitride annealing treatment and final high temperature annealing,
상기 열간압연의 마무리 압연은 하기식과 같이 표현되는 열간압연율분포지수 Rd가 0.2이상 2.5이하가 되도록 행하는 것을 특징으로 한다.The finish rolling of the hot rolling is carried out so that the hot rolling ratio distribution index Rd expressed by the following formula is 0.2 or more and 2.5 or less.
열간압연율 분포지수 Rd= (Ra1+Ra2)/(Rb1+Rb2) Hot rolling ratio distribution index Rd = (Ra1 + Ra2) / (Rb1 + Rb2)
Ra1: 열간압연 사상압연 첫 패스의 압연율(%)Ra1: Rolling ratio (%) of the first pass of hot rolling filament rolling
Ra2: 열간압연 사상압연 두번째 패스의 압연율(%)Ra2: Rolling ratio (%) of the second pass of hot rolling filament rolling
Rb1: 열간압연 사상압연 마지막 패스의 압연율(%)Rb1: Rolling ratio (%) of the last pass of hot rolling filament rolling
Rb2: 열간압연 사상압연 마지막에서 두번째 패스의 압연율(%)Rb2: Rolling ratio (%) of the second pass from the end of hot rolling filament rolling
Description
제 1도는 열간압연율 분포지수Rd에 따른 열간압연판의 미세조직 1 shows the microstructure of the hot rolled plate according to the hot rolling ratio distribution index Rd.
제 2도는 열간압연율 분포지수Rd에 따른 자성편차를 나타낸 그림 2 is a diagram showing the magnetic deviation according to the hot rolling index distribution index Rd
본 발명은 변압기, 전동기, 발전기 및 기타 전자기기등의 철심재료로 사용되는 방향성 전기강판에 관한 기술로서, 보다 상세히는 전기강판을 제조함에 있어 열간압연시 마무리압연의 압연율을 적절히 배분하여 코일내의 자성편차를 줄여서 안정적인 자기적 성질을 확보할 수 있는 방향성 전기강판의 제조방법에 관한 것이다. The present invention relates to a oriented electrical steel sheet used as iron core materials for transformers, electric motors, generators, and other electronic devices, and more particularly, in the manufacture of electrical steel sheets, by appropriately distributing the rolling ratio of the finish rolling during hot rolling, The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet capable of securing stable magnetic properties by reducing magnetic deviation.
방향성 전기강판이란 결정립의 방위가 (110)[001]방향으로 배향된 집합조직을 가진 전기강판으로서, 압연방향으로 극히 우수한 자기적 특성을 갖기 때문에 변압기, 전동기, 발전기 및 기타 전자기기 등의 철심 재료로 사용된다.A grain-oriented electrical steel sheet is an electrical steel sheet having an aggregate structure in which the grain orientation is oriented in the (110) [001] direction. Since it has extremely excellent magnetic properties in the rolling direction, iron core materials such as transformers, motors, generators, and other electronic devices are used. Used as
방향성 전기강판은 자속밀도와 철손이 뛰어난 것이 요구되고 있다. 자속밀도는 자장의 강도가 1000Amp/m에서 측정하는 B10의 값이 사용되고 철손은 주파수 50Hz에서 1.7 Tesla(테슬러)에서의 kg당 손실(Watt)로 나타낸다. 자속밀도는 클수 록, 철손은 작을수록 특성이 우수하다.The grain-oriented electrical steel sheet is required to have excellent magnetic flux density and iron loss. The magnetic flux density is the value of B10 measured at 1000 Amp / m of the magnetic field, and the iron loss is expressed as loss per kilogram (Watt) at 1.7 Tesla (Tesla) at a frequency of 50 Hz. The higher the magnetic flux density, the smaller the iron loss, the better the characteristics.
N.P.Goss에 의해 냉간압연법에 의한 방향성 전기강판 제조법이 발명된 이래 개량을 거듭하여 많은 진보가 있었다. 방향성 전기강판의 제조방법이 발명된 이래, 최근까지 거의 50여년간 방향성 전기강판의 제조는 슬라브를 분괴 또는 연주공정을 거쳐 슬라브로 만든 다음 슬라브를 열간압연을 위해 1400℃ 전후의 높은 온도로 재가열한 다음 열간압연을 하는 공정을 거쳤다. 열간압연판을 열처리하고 최종두께까지 중간소둔을 포함한 2회 냉간압연 혹은 중간소둔없이 최종두께까지 냉간압연한 다음 1차재결정을 겸한 탈탄소둔을 하고, 2차재결정을 일으키는 고온소둔을 실시한 다음 코팅하는 것이 일반적인 프로세스이다. Since N.P.Goss invented a method for producing oriented electrical steel sheet by cold rolling, many improvements have been made. Since the method of manufacturing the grain-oriented electrical steel sheet was invented, the manufacture of grain-oriented electrical steel sheet for almost 50 years until recently has been made into slabs by the process of milling or casting, and then reheating the slabs to high temperature around 1400 ℃ for hot rolling. Hot rolled process. Heat-treat the hot rolled plate, cold roll to the final thickness twice or cold roll to the final thickness without intermediate annealing to the final thickness, then decarbon annealing as the primary recrystallization, hot annealing causing the secondary recrystallization, and then coating This is a common process.
그러나, 1960년대 말부터, 일본특허공보소46-937, 소46-4085, 소 46-26621등 일본의 고베제강이 슬라브 저온가열에 대한 특허를 출원하였고, 1980년대 초반부터 이를 개선한 특허들이(대한민국 특허공고 1996-63078, 1996-71517, 1997-53791, 1997-37247, 1997-28305, 1997-32747, 그리고 한국 공개특허 1989-13200, 1992-702728, 1990-016461) 다수 출원되어서 기술이 개량되었다. Since the late 1960s, however, Japanese Kobe Steel, such as Japanese Patent Publication Nos. 46-937, 46-8585 and 46-26621, has applied for patents for low-temperature heating of slabs. Korean Patent Publication Nos. 1996-63078, 1996-71517, 1997-53791, 1997-37247, 1997-28305, 1997-32747, and Korean Patent Publications 1989-13200, 1992-702728, 1990-016461) .
즉, 기존의 고온슬라브 가열방식은 재료의 회수율이 낮고, 제조원가가 비싼 반면, 저온 슬라브 가열을 특징으로 하는 이들 방법은 재료의 회수율이 좋고, 후 공정에서도 재료의 손실이 매우 적은 장점이 있고, 고온의 열간압연을 필요로 하지 않아서 열 원단위가 낮아 제조원가를 획기적으로 절감할 수 있다. That is, the conventional high temperature slab heating method has low recovery rate of materials and high manufacturing cost, while these methods characterized by low temperature slab heating have good recovery rate of material and very low loss of material in the post process. Since it does not require hot rolling, the heat source unit is low, and manufacturing cost can be drastically reduced.
일본특허공고 평8-3125, 일본공개특허 평4-259723, 평4-96858, 평5-295443등 기존의 저온 슬라브 가열기술은 주로 AlN을 입성장억제제로 이용하면서 1차재결정 후 고온소둔전에 암모니아개스를 이용하여 강판에 질소를 집어넣는 소위 질화소둔을 실시하여, 열간압연공정에서 AlN를 만드는 것이 아니라 냉간압연후에 AlN 석출물을 만드는 것이 가장 큰 특징이다. 이러한 기존의 특허들은 질화소둔공정을 따로 실시해야 하므로 생산성이 저하된다. 이를 개선하여 대한민국 공개특허 2001-0060641, 2000-0067565, 2000-0043780, 2000-0040613, 2001-0113064, 2002-0049917, 2003-0053756등의 1차재결정, 탈탄소둔, 질화소둔을 한번에 처리하는 방법등이 많이 제안되었다. Conventional low-temperature slab heating technologies such as Japanese Patent Publication Hei 8-3125, Japanese Patent Publication Hei 4-259723, Hei 4-96858, Hei 5-295443 mainly use AlN as grain growth inhibitor. The most characteristic feature is the formation of AlN precipitates after cold rolling rather than making AlN in the hot rolling process by performing so-called nitride annealing to inject nitrogen into the steel sheet using gas. These existing patents require a separate annealing process, thereby reducing productivity. Improved by this method, such as the first recrystallization, decarbonization annealing, nitride annealing such as Republic of Korea Patent Publication 2001-0060641, 2000-0067565, 2000-0043780, 2000-0040613, 2001-0113064, 2002-0049917, 2003-0053756 This has been proposed a lot.
통상의 열간압연방법은 슬라브를 가열한 다음 조압연한 후 사상압연(마무리압연)을 한다. 이 때, 슬라브를 압연할 때 처음 압연되는 부위와 마지막으로 압연되는 끝 부분은 필연적으로 온도차이가 발생하여 코일길이별 자성편차가 발생한다. 또, 1차재결정과 질화소둔을 동시에 실시하는 방법은 필연적으로 탈탄이 먼저 일어나고, 암모니아 개스에 의한 질화가 뒤따라 일어나므로 강판의 1차재결정립의 분포가 불균일해지는 단점이 있다. 따라서, 고온소둔중 2차재결정이 일어날 때, 1차재결정립의 크기분포에 따라 2차재결정 시작온도가 틀려져 자성이 불균일해지는 문제가 있다.In the usual hot rolling method, the slab is heated and roughly rolled before finishing finishing (finishing rolling). At this time, when rolling the slab, the first rolled portion and the last rolled end portion inevitably generate a temperature difference, and thus a magnetic deviation for each coil length occurs. In addition, the method of simultaneously performing the primary recrystallization and annealing nitride inevitably occurs decarburization first, followed by the nitriding by ammonia gas has a disadvantage in that the distribution of the primary recrystallized grains of the steel sheet is nonuniform. Therefore, when secondary recrystallization occurs during high temperature annealing, the secondary recrystallization start temperature is changed according to the size distribution of the primary recrystallized grains, which causes a problem of non-uniformity in magnetism.
이에 본 발명자들은 상기 문제점을 해결하기 위하여 연구를 거듭한 결과, 여태까지 아무도 주목하지 않았던 열간압연율 분포라는 개념이 이러한 불균일성을 해소하는데 매우 효과적인 것을 발견하였다.Accordingly, the present inventors have repeatedly studied to solve the above problems, and found that the concept of hot rolling ratio distribution, which no one has ever noticed, is very effective in solving such nonuniformity.
따라서 본 발명은 방향성 전기강판을 제조함에 있어서, 열간압연율을 적절히 배분하여 코일내의 자성편차를 줄여서 안정적인 자기적 성질을 확보할 수 있는 방향성 전기강판의 제조방법을 제공하고자 하는데 그 목적이 있다Accordingly, an object of the present invention is to provide a method of manufacturing a grain-oriented electrical steel sheet which can secure a stable magnetic property by appropriately allocating the hot rolling rate to reduce the magnetic deviation in the coil.
상기 목적을 달성하기 위하여 본 발명은 The present invention to achieve the above object
중량%로, Si: 2.5～4%, C:0.02~0.08%, Mn: 0.05～0.5, sol-Al:0.023~0.035%, N:0.002~0.01%, P: 0.015～0.035%, S: 0.004～0.010%, 및 잔부 Fe로 이루어지는 슬라브를 1100~1250℃로 재가열하고, 조압연 및 마무리압연으로 이루어지는 열간압연을 실시한 다음, 열연판소둔을 실시하고 냉간압연하여 최종 두께로 한 다음 1차재결정을 겸한 탈탄 및 질화소둔 처리를 동시에 하고 최종 마무리 고온소둔하는 방향성 전기강판의 제조방법에 있어서, By weight%, Si: 2.5-4%, C: 0.02-0.08%, Mn: 0.05-0.5, sol-Al: 0.023-0.035%, N: 0.002-0.01%, P: 0.015-0.035%, S: 0.004 The slab composed of ˜0.010% and the balance Fe is reheated to 1100 ~ 1250 ° C., hot rolling consisting of rough rolling and finishing rolling, followed by hot rolling annealing, cold rolling to final thickness, and then primary recrystallization. In the method of manufacturing a grain-oriented electrical steel sheet subjected to both decarburization and nitride annealing treatment and final high temperature annealing,
상기 열간압연의 마무리 압연은 오스테나이트와 페라이트가 공존하는 구역중 오스테나이트 분율이 높은 온도영역에서의 압연율이 오스테나이트 분율이 작은 온도에서의 압연율보다 적게하여 압연하는 것을 특징으로 하는 자기적 성질이 균일한 방향성 전기강판의 제조방법을 제공한다.The finish rolling of the hot rolling is characterized in that the rolling rate in the temperature range where the austenite fraction is high in the austenite and ferrite coexisting zone is less than the rolling rate at a temperature where the austenite fraction is small, the magnetic property characterized in that rolling Provided is a method for producing this uniform grain-oriented electrical steel sheet.
또한, 상기 열간압연의 마무리 압연은 하기식과 같이 표현되는 열간압연율분포지수 Rd가 1.0이상 2.5이하가 되도록 행하는 것을 특징으로 한다.In addition, the finish rolling of the hot rolling is characterized in that the hot rolling ratio distribution index Rd expressed by the following formula is performed to be 1.0 or more and 2.5 or less.
열간압연율 분포지수 Rd= (Ra1+Ra2)/(Rb1+Rb2) Hot rolling ratio distribution index Rd = (Ra1 + Ra2) / (Rb1 + Rb2)
Ra1: 열간압연 사상압연 첫 패스의 압연율(%)Ra1: Rolling ratio (%) of the first pass of hot rolling filament rolling
Ra2: 열간압연 사상압연 두번째 패스의 압연율(%) Ra2: Rolling ratio (%) of the second pass of hot rolling filament rolling
Rb1: 열간압연 사상압연 마지막 패스의 압연율(%)Rb1: Rolling ratio (%) of the last pass of hot rolling filament rolling
Rb2: 열간압연 사상압연 마지막에서 두번째 패스의 압연율(%)
Rb2: Rolling ratio (%) of the second pass from the end of hot rolling filament rolling
이하, 본 발명의 강 성분 및 제조조건에 대하여 설명한다. Hereinafter, the steel component and manufacturing conditions of this invention are demonstrated.
본 발명에서 Si는 비저항치를 증가시켜 철손을 낮추는 역할을 하는 원소로서, 그 함량이 2.5%미만인 경우에는 철손특성이 나빠지고, 4% 보다 과잉 첨가되면 강이 취약해져 냉간압연성이 극히 나빠지므로, 2.5~4%로 첨가하는 것이 바람직하다. In the present invention, Si is an element that serves to lower the iron loss by increasing the specific resistance value, the iron loss characteristics are worse when the content is less than 2.5%, and if excessively added more than 4%, the steel is vulnerable, cold rolling is extremely bad, It is preferable to add at 2.5-4%.
C는 AlN석출물의 미세 고용 분산, 압연조직형성, 냉간압연시 가공에너지 부여 등의 역할을 하는 원소로서, 0.02~0.08%가 바람직하다. 0.02%이하이면 최종제품의 중심부분에 미세결정립이 형성되어 자기적성질이 나빠지고, 0.08%이상이면 1차재결정립이 미세해져서 집합조직형성이 자성에 나쁘게 된다.C is an element which plays a role of fine solid dispersion of AlN precipitate, rolling structure formation, imparting processing energy during cold rolling, and preferably 0.02 to 0.08%. If it is less than 0.02%, fine crystal grains are formed in the center portion of the final product, and the magnetic properties deteriorate. If it is more than 0.08%, the primary recrystallized grains become fine and the formation of aggregates becomes poor in magnetism.
Mn은 재가열시 석출물의 고용온도를 낮추며, 열간압연시 소재 양 끝부분에 생성되는 크랙을 방지의 역할을 하는 원소로서, 이와 같은 작용효과를 얻기 위해서는 0.05%이상 첨가되어야 한다. 그러나, 과잉첨가되면 Mn산화물을 형성하여 철손을 악화하므로, 그 함량범위는 0.05~0.5%로 설정하는 것이 바람직하다.Mn lowers the solid solution temperature of the precipitate during reheating and prevents cracks formed at both ends of the material during hot rolling. It should be added at least 0.05% in order to obtain such an effect. However, when excessively added, Mn oxide is formed to deteriorate iron loss, so the content range is preferably set at 0.05 to 0.5%.
산 가용성Al은 N과 함께 AlN의 석출물을 형성하여 입성장억제력을 확보하는 원소로서, 무게 함량의 곱을 관리하는 것이 자성에 효과적이다. 산가용성Al이 0.023%이하이면 미세한 AlN이 석출하고 0.035%이상이면 AlN이 지나치게 조대하여져 1차재결정립억제효과가 없다. Acid-soluble Al is an element that forms a precipitate of AlN together with N to secure grain growth inhibition. It is effective to manage the product of the weight content. If the acid-soluble Al is less than 0.023%, fine AlN is precipitated, and if it is more than 0.035%, AlN is too coarse, so that there is no primary recrystallization effect.
N의 양은 20ppm이상 100ppm이하로 하는 것이 바람직하다. N의 양이 100ppm이상이면 압연성을 해치고 AlN이 조대해져 자성이 나빠진다. 정확한 원인은 불명하나 N의 양이 20ppm이하이면 경험적으로 2차재결정이 일어나지 않는다. It is preferable that the amount of N be 20 ppm or more and 100 ppm or less. If the amount of N is 100 ppm or more, the rolling property is impaired, AlN coarsens, and the magnetism deteriorates. The exact cause is unknown, but if the N content is less than 20ppm, no secondary recrystallization takes place empirically.
P는 1차재결정의 입성장을 억제하는데 부분적으로 유용한 원소로서, 0.015～0.035%첨가하는 것이 효과적이다. 0.015%이하이면 효과가 없고, 0.035%이상이면 취성이 증가하여 압연성을 해친다. P is an element useful in part to suppress grain growth of primary recrystallization, and it is effective to add 0.015 to 0.035%. If it is 0.015% or less, it is ineffective and if it is 0.035% or more, brittleness will increase and a rolling property will be impaired.
S는 0.004～0.01%로 하는 것이 바람직한데 , 0.004%이하로 관리하려면 제강의 비용이 증가하고, 0.01%이상이면 MnS석출물이 형성되어 1차재결정립이 미세해져서 2차재결정의 발달에 불리하다.S is preferably 0.004% to 0.01%. To manage less than 0.004%, the cost of steelmaking increases, and if it is 0.01% or more, MnS precipitates are formed and the primary recrystallized grains become fine, which is disadvantageous for the development of secondary recrystallization.
상기와 같이 조성된 강슬라브는, 바람직하게는 열간압연성과 자기적특성 확보 측면을 고려하여 1100～1250℃의 온도범위에서 재가열하게 되는데, 그 이유는 슬라브 가열온도가 1100℃미만이면 열간압연부하가 심하여 후반부에 열간압연율을 가져가는 것이 어렵고 1250℃를 초과하면 AlN의 미세석출로 자성이 나빠지기 때문에 상기 범위로 재가열해야 한다.The steel slab formed as described above is preferably reheated at a temperature range of 1100 to 1250 ° C in consideration of hot rolling and securing magnetic properties. The reason is that when the slab heating temperature is less than 1100 ° C, the hot rolling load is reduced. It is difficult to bring the hot rolling rate in the second half, and when it exceeds 1250 ° C., the magnetism deteriorates due to the microprecipitation of AlN, so it must be reheated in the above range.
또한, 재가열후 이루어지는 열간압연은 조압연과 사상압연으로 이루어지는데 이들은 연속적으로 이루어지되 아래식으로 이루어지는 사상압연의 압연율 분포를 0.2이상 2.5이하, 특히 바람직하기로는 1.0이상 2.5이하로 유지하면서 수행되도록 하는 것이 바람직하다. 만약, 압연율 분포가 1.0미만일 경우에는 압연기의 부하가 심하며 코일형상제어가 아주 어렵고, 2.5를 초과하면 코일내의 품질편차를 줄이는데 효과가 없기 때문이다.In addition, hot rolling after reheating is composed of rough rolling and filament rolling, which are continuously performed so that the rolling ratio distribution of the filamentous rolling made by the following equation is maintained at 0.2 or more and 2.5 or less, particularly preferably 1.0 or more and 2.5 or less. It is desirable to. If the rolling ratio distribution is less than 1.0, the load of the rolling mill is severe and the coil shape control is very difficult. If the rolling ratio is greater than 2.5, it is not effective in reducing the quality deviation in the coil.
열간압연율 분포지수; Rd= (Ra1+Ra2)/(Rb1+Rb2)Hot rolling ratio distribution index; Rd = (Ra1 + Ra2) / (Rb1 + Rb2)
Ra1: 열간압연 사상압연 첫 패스의 압연율(%) Ra1: Rolling ratio (%) of the first pass of hot rolling filament rolling
Ra2: 열간압연 사상압연 두번째 패스의 압연율(%)Ra2: Rolling ratio (%) of the second pass of hot rolling filament rolling
Rb1: 열간압연 사상압연 마지막 패스의 압연율(%)Rb1: Rolling ratio (%) of the last pass of hot rolling filament rolling
Rb2: 열간압연 사상압연 마지막에서 두번째 패스의 압연율(%)
Rb2: Rolling ratio (%) of the second pass from the end of hot rolling filament rolling
열간압연후 권취온도는 500℃ 이상 700℃이하로 관리한다. 500℃미만이면 열간압연후 급냉을 해야하므로 코일형상이 좋지 않고 700℃를 초과하면 탄화물이 조대하게 석출하여 후속공정에서 집합조직을 제어하는 것이 어렵다. After hot rolling, the coiling temperature is controlled between 500 ℃ and 700 ℃. If the temperature is less than 500 ℃, it is necessary to quench after hot rolling. If the coil shape is not good, if it exceeds 700 ℃, carbides are coarsened and it is difficult to control the texture in the subsequent process.
열연판소둔은 상온에서부터 가열하여 최고도달온도 700~1100℃사이의 온도에서 2분이하로 유지한다. 700℃이하이면 열연판 미세조직이 불균일하여 자성이 나쁘고, 1100℃이상이면 석출물의 분포가 불균일하여 자성편차가 심하다. Hot-rolled sheet annealing is heated from room temperature and kept below 2 minutes at the temperature between 700 ~ 1100 ℃. If the temperature is less than 700 ° C., the hot rolled plate microstructure is non-uniform, and the magnetic properties are poor.
열연판소둔후 냉간압연을 실시하여 최종두께로 만든 다음 암모니아가스가 포함된 수소 및 질소의 습윤분위기하에서 탈탄소둔 및 질화를 겸하여 1차재결정소둔을 실시한다. 본 발명자들의 실험결과에 의하면 800℃이하이면 자성이 좋지 않은 것으로 나타났다. 910℃이상이면 2차재결정이 일어나지 않아서 좋지 않다. After hot-rolled sheet annealing, cold rolling is carried out to the final thickness, and then primary recrystallization annealing is performed in combination with decarbonization and nitriding in a wet atmosphere of hydrogen and nitrogen containing ammonia gas. According to the experimental results of the present inventors, the magnetic properties were not good at less than 800 ℃. Above 910 ° C, secondary recrystallization does not occur, which is not good.
그 후, 소둔분리제를 슬러리 상태로 하여 코타롤로 도포하고 700℃이하의 온도에서 건조한 다음 권취하여 대형코일로 만든다. Thereafter, the annealing separator is applied in a slurry state and coated with cotarol, dried at a temperature of 700 ° C. or less, and then wound to make a large coil.
상기 소둔분리제의 도포후에는, 최종 마무리 고온소둔을 실시하는데, 전 구간을 25% 이하의 질소함유 수소분위기로 하고 700～1200℃구간의 승온율을 15℃/hr이상 유지하면서 1200±10℃의 온도에서 20시간 이상 균열한 후 냉각하는 식으로 행하는 것이 바람직하다. After application of the annealing separator, the final finishing high temperature annealing is carried out. The entire section is subjected to a hydrogen atmosphere containing nitrogen of 25% or less, and the temperature rising rate of 700 to 1200 ° C is maintained at 1200 ± 10 ° C over 15 ° C / hr. It is preferable to carry out by cooling after cracking for 20 hours or more at the temperature of.
그 후, 최종적으로 인산염, 콜로이달실리카 및 무수크롬산 등으로 구성된 코팅제를 도포한다.
Thereafter, a coating agent consisting of phosphate, colloidal silica, chromic anhydride and the like is finally applied.
열간압연은 조압연과 사상압연으로 나누어진다. 통상 열간압연이라면 사상압연을 가르킨다. 열간압연은 6패스의 연속압연으로 이루어진다. 종래의 열간압연방법은 앞쪽에서 압연율을 크게하고 마지막 압연에서는 형상개선을 위해 압연율을 작게 가지고 간다. Hot rolling is divided into rough rolling and finishing rolling. Normally, hot rolling refers to filament rolling. Hot rolling consists of six passes of continuous rolling. In the conventional hot rolling method, the rolling rate is increased from the front side, and the last rolling method has a small rolling rate for shape improvement.
방향성 전기강판의 통상 탄소함량은 0.02~0.08%이고 이때 오스테나이트와 페라이트 2상구역이 된다. 온도가 1100℃일 때 오스테나이트 분율이 가장크고 탄소함량에 따라 최고 20~30%의 오스테나이트 분율을 가진다. 800℃이하가 되면 페라이트 단상으로 된다. 페라이트에 비해 오스테나이트상은 훨씬 단단한 조직이다. 열간압연은 1050℃에 시작되므로 앞 패스의 압연율을 크게 하면 할수록 오스테나이트 분율이 큰 온도영역에서 압연이 되므로 페라이트와 오스테나이트데 축적되는 에너지가 틀리므로 후속공정에서 미세조직이 불균일해지는 원인이 된다. Typical carbon content of oriented electrical steel sheet is 0.02 ~ 0.08%, and it becomes austenite and ferrite two-phase zone. At a temperature of 1100 ° C, the austenite fraction is the largest and has an austenitic fraction of up to 20-30%, depending on the carbon content. It becomes a ferrite single phase below 800 degreeC. Compared to ferrite, the austenite phase is a much harder tissue. Since hot rolling starts at 1050 ° C, the larger the rolling rate of the front pass, the more the austenite fraction is rolled in the temperature range, so the energy accumulated in ferrite and austenite is different, which causes the microstructure to be uneven in the subsequent process. .
본 발명자들은 여태까지 아무도 주목하지 않았던 열간압연율 분포라는 개념이 이러한 불균일성을 해소하는데 매우 효과적인 것을 발견하였다. 즉 열간압연, 특히 200~250mm 슬라브를 100mm이하로 하는 조압연과 마지막 두께까지 압연하는 사상압연중 사상압연의 압연율 배분이 매우 중요한 것을 발견하였다. 본 발명자들은 사상압연의 처음 2패스 압연율의 합과 마지막 2패스의 압연율의 합의 비율로 압연율 배분을 지수화시켰다. 열간압연율분포지수는 다음 식과 같다. The inventors have found that the concept of hot rolling ratio distribution, which no one has ever noticed, is very effective in solving this nonuniformity. That is, it was found that the distribution ratio of hot rolling, in particular rough rolling having a slab of 200 to 250 mm or less and 100 m, of finishing rolling during finishing rolling to the final thickness, is very important. The inventors indexed the rolling rate distribution by the ratio of the sum of the first two pass rolling rates of finishing rolling and the sum of the rolling rates of the last two passes. The hot rolling rate distribution index is given by the following equation.
Rd: 열간압연율 분포지수 (Rolling ratio Distribution)
Rd: Rolling ratio Distribution
Rd= (Ra1+Ra2)/(Rb1+Rb2)Rd = (Ra1 + Ra2) / (Rb1 + Rb2)
Ra1: 열간압연 사상압연 첫 패스의 압연율(%)Ra1: Rolling ratio (%) of the first pass of hot rolling filament rolling
Ra2: 열간압연 사상압연 두번째 패스의 압연율(%)Ra2: Rolling ratio (%) of the second pass of hot rolling filament rolling
Rb1: 열간압연 사상압연 마지막 패스의 압연율(%)Rb1: Rolling ratio (%) of the last pass of hot rolling filament rolling
Rb2: 열간압연 사상압연 마지막에서 두번째 패스의 압연율(%)
Rb2: Rolling ratio (%) of the second pass from the end of hot rolling filament rolling
본 발명자들이 조사한 바에 의하면 Rd(Rolling ratio Distribution)값을 0.2이상 2.5이하로 관리하는 것이 바람직하다. According to the inventors' investigation, it is preferable to manage Rd (Rolling ratio Distribution) value to 0.2 or more and 2.5 or less.
오스테나이트 분율이 높을 때의 압연율 Ra1과 Ra2를 작게하고, 오스테나이트 분율이 작은 마지막 두 패스에서 압연율 높게 가져감으로서 페라이트 영역에서 압연율을 크게 하고, 오스테나이트역에서 압연율을 작게하여 조직을 균일하게 하고 전단변형을 많이 주는 것이 자성의 불균일성을 해소하는 것으로 나타났다.When the austenitic fraction is high, the rolling ratios Ra1 and Ra2 are made small, and in the last two passes where the austenitic fraction is small, the rolling ratio is increased to increase the rolling ratio in the ferrite region, and to reduce the rolling ratio in the austenitic region. Uniformity and high shear strain were found to solve the magnetic nonuniformity.
압연후반부에 열간압연율을 많이 줄수록 전단변형량이 많이 축적된다. 방향성 전기강판의 최종 집합조직인 {110}<001> Goss결정립은 열간압연에서 전단변형에 의해 발생된다. 열연판 소둔의 목적은 열연판에서 Goss 결정립의 강도증가와 미세조직의 균일화이다. 열간압연에서 전단변형량이 많으면 열간압연판의 미세조직이 균일해진다. The more the hot rolling rate is decreased in the latter part of the rolling, the more the shear strain accumulates. The {110} <001> Goss grain, the final texture of oriented electrical steel sheets, is produced by shear deformation in hot rolling. The purpose of the hot-rolled sheet annealing is to increase the strength of Goss grains and to homogenize the microstructure in the hot-rolled sheet. If the amount of shear deformation in hot rolling is large, the microstructure of the hot rolled sheet becomes uniform.
제 1도에 열간압연패스 압연부하에 따라 미세조직이 달라지는 것을 나타냈다. Rd값이 3.0일 때는 중심부와 표면부의 미세조직차가 뚜렸하고, 표면층의 재결정이 잘 발달되지 않은 것에 비해, Rd값이 1.0일 때는 재결정부위가 표면부부터 중심부까지 골고루 잘 발달되어 있다. 따라서, Rd값을 0.2이상 2.5이하로 관리하는 것이 바람직하지만, 특히 본 발명에서는 실험결과에 따라 1.0이상 2.5이하로 관리하는 것이 가장 바람직하다.1 shows that the microstructure varies according to the hot rolling pass rolling load. When the Rd value is 3.0, the microstructure difference between the center part and the surface part is wide, and the recrystallization of the surface layer is not well developed, whereas when the Rd value is 1.0, the recrystallization part is well developed from the surface part to the center part. Therefore, although it is preferable to manage Rd value to 0.2 or more and 2.5 or less, it is most preferable to manage to 1.0 or more and 2.5 or less especially according to the experiment result in this invention.
이하, 실시예를 통하여 본 발명을 보다 구체적으로 설명한다.
Hereinafter, the present invention will be described in more detail with reference to Examples.
실시예Example
다음 표와 같은 성분계로 이루어지는 강을 1150℃로 슬라브 가열후 2.3mm두께로 열간압연하였다. 열간압연은 6패스로 나누어 연속하여 실시하였다. Steel consisting of the component system as shown in the following table was hot rolled to 2.3 mm thickness after slab heating at 1150 ° C. Hot rolling was performed continuously by dividing into six passes.
열간압연판을 1100℃에서 1분간 열처리하고 냉간압연하여 0.3mm 두께로 만들었다. 냉간압연판을 850℃에서 3분간 질소와 수소, 그리고 암모니아가 혼합된 습윤분위기에서 탈탄과 1차재결정 그리고 질화를 겸한 열처리를 실시하였다. 고온소둔은 수소와 질소의 혼합분위기에서 1200℃까지 시간당 15℃로 승온하는 열처리조건으로 하였다. 고온소둔에서 2차재결정을 일으킨 후 절연코팅하고 철손을 측정하였다. The hot rolled plate was heat treated at 1100 ° C. for 1 minute and cold rolled to a thickness of 0.3 mm. The cold rolled plate was heated at 850 ° C for 3 minutes in a wet atmosphere containing nitrogen, hydrogen, and ammonia, followed by decarburization, primary recrystallization, and nitriding. The high temperature annealing was performed under a heat treatment condition in which the temperature was raised to 15 ° C. per hour up to 1200 ° C. in a mixed atmosphere of hydrogen and nitrogen. After recrystallization at high temperature annealing, insulation coating and iron loss were measured.
열간압연율 분포를 상기 열간압연율분포지수로 하여 변화시켰다. 열간압연율이 자기적성질에 미치는 불균일성은 방향성 전기강판코일내에 철손이 가장 좋은 부위와 가장나쁜 부위 편차로 나타냈다. 자성의 편차는 다음식과 같다.
The hot rolling ratio distribution was changed as the hot rolling ratio distribution index. The nonuniformity of the hot rolling rate on the magnetic properties was represented by the best iron loss and the worst iron deviation in the oriented electrical steel coil. The magnetic deviation is as follows.
자성편차=(가장 높은 철손값 - 가장 낮은철손)/코일철손평균
Magnetic deviation = (highest iron loss-lowest iron loss) / coil iron loss average
또한 Rd값을 낮게 가져갈 경우 자성의 불균일성은 줄어들지만 후반부의 압연율이 필연적으로 증가하게 되어 코일형상이 좋지 않다. 따라서 너무 낮을 경우 형상불량률이 급격히 나빠진다. 가능한 Rd값은 0.2이상, 특히 1.0이상이다. 자성편차는 Rd값이 2.5이상이 되면 제 2도의 그림과 같이 자성편차가 급격히 커진다.In addition, if the Rd value is lowered, the magnetic nonuniformity is reduced, but the rolling ratio of the latter part inevitably increases, so that the coil shape is not good. Therefore, if it is too low, the shape defect rate deteriorates sharply. Possible Rd values are at least 0.2, in particular at least 1.0. If the Rd value is 2.5 or more, the magnetic deviation rapidly increases as shown in FIG.
[표1] 실험에 사용된 슬라브 조성계[Table 1] Slab composition meter used in the experiment
상기한 바와 같은 본 발명에 의하면, 방향성 전기강판의 열간압연율을 적절히 배분하여 코일내의 자성편차를 줄여서 안정적인 자기적 성질을 확보할 수 있는 효과가 있다. 이러한 효과는 열간압연시 오스테나이트와 페라이트가 공존하는 구역중 오스테나이트 분율이 높은 온도영역에서 압연율을 적게하고 열간압연시 전단변형을 많이 주어 미세조직을 균일하게 하는 것에 의해 발생한다.According to the present invention as described above, there is an effect that by appropriately distributing the hot rolling rate of the grain-oriented electrical steel sheet to reduce the magnetic deviation in the coil to ensure a stable magnetic properties. This effect is caused by reducing the rolling rate in the high austenite fraction in the region where austenite and ferrite coexist during hot rolling and giving a lot of shear deformation during hot rolling to make the microstructure uniform.
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| JP2002348612A (en) | 2001-05-23 | 2002-12-04 | Nippon Steel Corp | Method for manufacturing grain-oriented electromagnetic steel sheet without needing decarburization annealing |
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