KR100501002B1 - A method for manufacturing grain oriented electric steel sheet - Google Patents
A method for manufacturing grain oriented electric steel sheet Download PDFInfo
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- KR100501002B1 KR100501002B1 KR10-2000-0027978A KR20000027978A KR100501002B1 KR 100501002 B1 KR100501002 B1 KR 100501002B1 KR 20000027978 A KR20000027978 A KR 20000027978A KR 100501002 B1 KR100501002 B1 KR 100501002B1
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- C—CHEMISTRY; METALLURGY
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- 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
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- 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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- 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
- C21D8/1233—Cold rolling
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- 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
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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Abstract
본 발명은 방향성 전기강판의 제조방법에 관한 것이고, 방향성 전기강판의 제조방법에 있어서, 고온소둔시 승온단계에서의 속도를 최적화하여, 생산성을 개선시키고 안정적인 자기적 성질을 확보하고자 하는 것을 주된 목적으로 한다.The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet, the method for producing a grain-oriented electrical steel sheet, to improve the productivity in the step of increasing the temperature at the time of high temperature annealing, to improve productivity and to ensure a stable magnetic properties do.
상기 목적을 달성하기 위한 본 발명은, 중량%로, Si:2.9~3.5%, C:0.01~0.06%, Mn:0.05~0.15%, Sol-Al:0.02~0.035%, S:0.025%이하, Cu: 0.1~0.2%, 잔부 Fe 및 기타 불가피한 불순물로 조성되는 강 슬라브를 1360℃ 이하의 온도에서 가열하고 열간압연 및 열연판소둔한 다음, 최종 두께로 2차 냉간압연하고, 1차 재결정소둔, 탈탄소둔 및 질화소둔후 고온소둔을 실시하는 방향성 전기강판의 제조방법에 있어서, The present invention for achieving the above object, in weight%, Si: 2.9 ~ 3.5%, C: 0.01 ~ 0.06%, Mn: 0.05 ~ 0.15%, Sol-Al: 0.02 ~ 0.035%, S: 0.025% or less, Cu: Steel slab composed of 0.1 ~ 0.2%, balance Fe and other unavoidable impurities is heated at a temperature below 1360 ° C, hot rolled and hot rolled annealed, second cold rolled to final thickness, primary recrystallized annealing, In the method for producing a grain-oriented electrical steel sheet subjected to high temperature annealing after decarbonization annealing and nitride annealing,
상기 고온소둔는 상온~950℃범위에서는 25~50℃/hr의 승온속도로 가열하고, 950~1050℃ 구간에서는 5~14℃/hr의 승온속도로 가열하고, 1050~1200℃의 구간에서는 15~25℃/hr의 승온속도로 가열하는 것을 특징으로 하는 방향성 전기강판의 제조방법을 그 기술적 요지로 한다.The high temperature annealing is heated at a temperature increase rate of 25 ~ 50 ℃ / hr in the room temperature ~ 950 ℃ range, heated at a temperature increase rate of 5 ~ 14 ℃ / hr in the 950 ~ 1050 ℃ section, 15 ~ in the section of 1050 ~ 1200 ℃ The technical gist of the method for producing a grain-oriented electrical steel sheet characterized by heating at a temperature increase rate of 25 ℃ / hr.
Description
본 발명은 방향성 전기강판의 제조방법에 관한 것이고, 보다 상세하게는 2차 재결정을 일으키는 고온소둔의 승온단계를 구분하여, 고스집합조직과 일반집합조직의 결정립계 이동도의 차를 극대화 함으로써, 자속밀도를 높을 수 있는 방향성 전기강판의 제조방법에 관한 것이다.The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet, and more specifically, by separating the temperature rising stage of the high temperature annealing causing secondary recrystallization, by maximizing the difference between the grain boundary mobility of the goth and the general assembly structure, magnetic flux density It relates to a method for producing a grain-oriented electrical steel sheet that can be higher.
방향성 전기강판은 주로 변압기 등의 전기기기의 철심용으로 제조된다. 방향성 전기강판에 요구되는 특성은 낮은 철손(core loss)과 높은 자속밀도(magnetic flux density), 그리고 낮은 자왜(magnetostriction)이다. 철손이 낮을수록 전기기기의 에너지 손실이 작고, 자속밀도가 높을수록 전기기기의 효율이 좋아져서 소형화가 가능하다. 또한, 자왜가 작을수록 소음이 작다.A grain-oriented electrical steel sheet is mainly manufactured for iron cores of electrical equipment such as transformers. The properties required for oriented electrical steel sheets are low core loss, high magnetic flux density and low magnetostriction. The lower the iron loss, the smaller the energy loss of the electric device, and the higher the magnetic flux density, the higher the efficiency of the electric device, and thus the miniaturization is possible. In addition, the smaller the magnetostriction, the smaller the noise.
N.P.Goss에 의해 냉간압연법에 의한 방향성 전기강판 제조방법이 발명된 이래 개량을 거듭하여 많은 진보가 있었는데, 이러한 방향성 전기강판의 연구의 역사는 철손저감노력의 역사라 해도 과언이 아니다. 주요한 개선내용을 보면, 제품의 두께를 얇게 하고, 성분에 첨가원소를 다양하게 한다든가 또는 제품에 레이저를 조사하여 자구를 미세하게 하는 방법 등이 있다. 이러한 모든 방법들은 제조원가를 높이고, 작업자들의 노력을 많이 필요로 하는 것들이다.Since the invention of N.P.Goss invented a method of manufacturing oriented electrical steel sheet by cold rolling, many improvements have been made. The history of research on oriented electrical steel sheet is not an exaggeration to say. Major improvements include thinning the product, varying the amount of additives in the components, or minimizing magnetic domains by irradiating the product with a laser. All of these methods increase manufacturing costs and require a lot of labor.
최근에는 자성개선이 한계에 부딪히면서 제조원가 절감을 위한 방안들이 많이 제안되어, 슬라브 저온가열을 특징으로 하는 방향성 전기강판의 제조방법 등이 많이 제안되고 있다. 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.Recently, as magnetic improvement hits the limit, many methods for reducing manufacturing cost have been proposed, and a method of manufacturing a grain-oriented electrical steel sheet having low temperature slab heating has been proposed. 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.
그러나, 상기 방법들은 종래의 2차 재결정 방법을 그대로 차용하고 있어서 생산성이 낮을 뿐 아니라, 제품의 자기적 성질을 안정적으로 확보하는데 어려움이 많다. 즉, 종래기술은 2차 재결정이 시작되는 1000℃까지 15℃/hr의 속도로 승온하거나, 한국특허출원 제98-55320호의 발명에서와 같이, 고온소둔의 승온단계에서 700~1050℃까지의 온도구간의 승온속도는 18~30℃/hr, 1050℃부터 1200℃까지의 온도구간에서는 승온속도를 10~15℃/hr로 하는 방법 등을 사용한 것이다.However, the above methods employ the conventional secondary recrystallization method as it is, so that not only the productivity is low, but also it is difficult to stably secure the magnetic properties of the product. That is, in the prior art, the temperature is raised to a rate of 15 ° C./hr up to 1000 ° C. at which secondary recrystallization starts, or as in the invention of Korean Patent Application No. 98-55320, a temperature of 700 to 1050 ° C. in a temperature rising step of high temperature annealing. The temperature increase rate of the section is 18 ~ 30 ℃ / hr, the temperature increase rate in the temperature range from 1050 ℃ to 1200 ℃ is used a method such as 10 ~ 15 ℃ / hr.
한편, 방향성 전기강판은, 냉간압연이 완료된 후 연속소둔에 의해 자기시효의 원인이 되는 탄소를 줄이고 1차 재결정(primary recrystallization)을 일으킨 다음 5일 정도의 장시간을 필요로 하는 고온소둔 공정에서 2차 재결정을 일으키는데, 방향성 전기강판의 자기적 성질은 2차 재결정에서 형성되는 {110}<001> 집합조직이 얼마나 잘 형성되어 있는가에 달려 있다. 즉, 압연면에 {110}면, 압연방향으로 <001>방향이 정확하게 평행하게 배열되어 있어야 자성이 우수한 것이고, 통상의 방향성 전기강판의 경우에는 이 오차가 7도 이내, 고자속밀도 방향성 전기강판은 3도 이내로 평행하게 배열되어 있다.On the other hand, after the cold rolling is completed, the grain-oriented electrical steel sheet has a secondary annealing in a high temperature annealing process requiring a long time of about 5 days after reducing the carbon which causes the self aging by continuous annealing and causing primary recrystallization. Recrystallization occurs, and the magnetic properties of oriented electrical steel sheets depend on how well the {110} <001> texture is formed in secondary recrystallization. That is, the magnetic field is excellent when the {110} plane and the <001> direction are arranged in parallel in the rolling direction, and the magnetic properties are excellent. In the case of a normal oriented electrical steel sheet, this error is within 7 degrees and a high magnetic flux density oriented electrical steel sheet. Are arranged parallel to within 3 degrees.
이러한, 방향성 전기강판의 고온소둔시 2차 재결정이 일어나는 온도는 통상 1000℃ 이상인데, 고온소둔에서 2차 재결정이 일어나기 전까지의 시간은 약 이틀정도로 매우 길다. 그럼에도 이 온도구간에서 일어나는 야금학적 해석이 충분치 않았다.The temperature at which secondary recrystallization occurs during the high temperature annealing of the grain-oriented electrical steel sheet is usually 1000 ° C. or more, and the time until the secondary recrystallization occurs at high temperature annealing is very long, about two days. Nevertheless, the metallurgical interpretation of this temperature range was not sufficient.
이에, 본 발명자들은 상기와 같은 문제점을 해결하기 위하여 연구와 실험을 거듭하고 그 결과에 근거하여 본 발명을 제안하게 된 것으로, 본 발명은 슬라브 저온가열을 특징으로 하는 방향성 전기강판의 제조방법에 있어서, 고온소둔시 2차 재결정에 결정적인 영향을 미치는 승온단계에서의 속도를 최적화하여, 생산성을 개선시키고 안정적인 자기적 성질을 확보하고자 하는 것을 주된 목적으로 한다.Accordingly, the present inventors have repeatedly conducted research and experiments to solve the above problems and propose the present invention based on the results, and the present invention provides a method for manufacturing a grain-oriented electrical steel sheet characterized by low-temperature heating of slabs. In order to improve productivity and secure stable magnetic properties, the main purpose is to optimize the speed in the temperature raising step which has a decisive effect on the secondary recrystallization during high temperature annealing.
본 발명은 중량%로, Si:2.9~3.5%, C:0.01~0.06%, Mn:0.05~0.15%, Sol-Al:0.02~0.035%, S:0.025%이하, Cu: 0.1~0.2%, 잔부 Fe 및 기타 불가피한 불순물로 조성되는 강 슬라브를 1360℃ 이하의 온도에서 가열하고 열간압연 및 열연판소둔한 다음, 최종 두께로 2차 냉간압연하고, 1차 재결정소둔, 탈탄소둔 및 질화소둔후 고온소둔을 실시하는 방향성 전기강판의 제조방법에 있어서, In the present invention, in terms of weight percent, Si: 2.9 to 3.5%, C: 0.01 to 0.06%, Mn: 0.05 to 0.15%, Sol-Al: 0.02 to 0.035%, S: 0.025% or less, Cu: 0.1 to 0.2%, The steel slab composed of the balance Fe and other unavoidable impurities is heated at a temperature below 1360 ° C., hot rolled and hot rolled annealed, secondly cold rolled to a final thickness, and then subjected to high temperature after primary recrystallization annealing, decarbonization annealing and nitriding annealing. In the manufacturing method of the grain-oriented electrical steel sheet which performs annealing,
상기 고온소둔는 상온~950℃범위에서는 25~50℃/hr의 승온속도로 가열하고, 950~1050℃ 구간에서는 5~14℃/hr의 승온속도로 가열하고, 1050~1200℃의 구간에서는 15~25℃/hr의 승온속도로 가열하는 것을 특징으로 하는 방향성 전기강판의 제조방법에 관한 것이다.The high temperature annealing is heated at a temperature increase rate of 25 ~ 50 ℃ / hr in the room temperature ~ 950 ℃ range, heated at a temperature increase rate of 5 ~ 14 ℃ / hr in the 950 ~ 1050 ℃ section, 15 ~ in the section of 1050 ~ 1200 ℃ It relates to a method for producing a grain-oriented electrical steel sheet characterized in that the heating at a temperature increase rate of 25 ℃ / hr.
이하, 본 발명에 대하여 설명한다.EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.
본 발명의 발명자들은, 1차 재결정판과 2차 재결정이 일어나기 직전의 온도인 1000℃ 사이에서 미스오리엔테이션(misorientation)을 관찰하고, 2차 재결정시 일어나는 집합조직의 변화를 조사한 결과, 고온소둔시 승온단계를 구분하여 적용하면 고스 집합조직과 일반집합조직 결정립계의 이동도 차를 극대화하여 자속밀도를 높일 수 있다는 것을 발견하였다. The inventors of the present invention observed the misorientation between the primary recrystallization plate and the temperature immediately before the secondary recrystallization occurs, and the change in the texture structure during the secondary recrystallization. It was found that the magnetic flux density can be increased by maximizing the mobility difference between the goth and general aggregate grain boundaries when applying the different stages.
도1(a),(b)에는 상기한 바와 같이, 1차 재결정판과 2차 재결정이 일어나기 직전의 온도인 1000℃ 사이에서 미스오리엔테이션(misorientation)을 미시집합조직 측정기법인 EBSP법을 이용해 관찰한 결과가 나타나 있다. 미스오리엔테이션은 이웃하는 두결정립의 회전방위관계를 나타내는 것으로, 도1(a),(b)의 세로축은 고온소둔이 일어나기 직전의 온도인 1000℃ 시편의 상대적인 미스오리엔테이션분율에서 1차재결정이 일어난 탈탄판의 미스오리엔테이션분율을 빼준것으로서, 상대적인 미스오리엔테이션의 변화를 나타낸다. 이 때, (+)값은 탈탄판에서 2차 재결정소둔을 함에 따라 특정 각도의 미스오리엔테이션 분율이 늘어난 것을 의미하고, (-)는 줄어든 것을 의미한다. 도1(b)에 나타난 바와 같이, 2차 재결정의 핵이 되는 {110}<001>의 미스오리엔테이션 변화를 보면, 20~45도 사이의 미스오리엔테이션은 증가하고, 그 외의 낮거나 높은 각도의 미스오리엔테이션은 감소를 보이지만, 도1(a)의 일반 집합조직의 미스오리엔테이션은 반대의 양상으로 20~45도 사이의 미스오리엔테이션은 고온소둔이 진행됨에 따라 감소를 하고 이보다 높거나 낮은 각도의 미스오리엔테이션은 상대적으로 증가를 보인다. 그 이유는 다음과 같다.1 (a) and (b), as described above, the misorientation was observed between the primary recrystallization plate and the temperature immediately before the secondary recrystallization occurred by using the EBSP method, which is a microassembly measurement technique. The results are shown. The misorientation represents the rotational orientation relationship between two neighboring grains, and the vertical axis in FIGS. 1 (a) and (b) shows the decarburization in which primary recrystallization occurs at the relative misorientation fraction of the specimen at 1000 ° C., which is the temperature just before hot annealing occurs. Subtracted the misorientation fraction of the plate, indicating the relative change in misorientation. At this time, the positive value means that the misorientation fraction of a specific angle increases as the secondary recrystallization annealing in the decarburization plate, and the negative (-) means decrease. As shown in Fig. 1 (b), the change in misorientation of {110} <001>, which is the nucleus of secondary recrystallization, increases the misorientation between 20 and 45 degrees, and other low or high angle misses. Orientation decreases, but the misorientation of the general texture of Figure 1 (a) is reversed. The misorientation between 20 and 45 degrees decreases as the hot annealing progresses. The increase is relatively high. The reason for this is as follows.
결정립의 성장은 결정립계의 성질에 직접적인 영향을 받는데, 결정립계의 성질에서는 이웃하는 결정립계의 회전 방위관계인 회전축과 회전각도가 중요하다. 이웃하는 결정립의 결정립각도가 15도 이하인 소경각입계(low angle grain boundary)와 50도 이상인 고경각입계(high angle grain boundary)는 결정립계의 에너지가 낮아서 확산속도가 느려서 재결정립 성장시 결정립계의 이동속도가 느리다. 미스오리엔테이션 각도인 20~45도 사이의 결정립계는 결정립계의 에너지가 높은데, 이는 석출물이나 철, 규소 등의 원자확산속도가 빨라 결정립계의 이동속도가 빠르게 된다는 것을 의미한다. 즉, 20~45도 사이의 회전관계를 지닌 결정립계는 이동속도가 빠르다.Grain growth is directly affected by the grain boundary properties. In the grain boundary properties, the rotational axis and the rotation angle, which are the rotational orientations of neighboring grain boundaries, are important. The low angle grain boundary with the grain size of neighboring grains less than 15 degrees and the high angle grain boundary with more than 50 degrees have low energy of grain boundary, so the diffusion rate is slow and the grain velocity of grains during recrystallization grows. Is slow The grain boundary between 20 and 45 degrees, which is the misorientation angle, has a high energy of grain boundaries, which means that the atomic diffusion rate of precipitates, iron, silicon, etc. is high, and therefore the movement speed of grain boundaries is high. In other words, the grain boundary having a rotational relationship between 20 and 45 degrees has a fast moving speed.
도1(a),(b)에서 일반 결정립계와 {110}<001>의 의미는, 고온소둔이 진행될수록 2차 재결정이 일어나기 직전의 단계에서 일반 결정립계는 이동도가 빠른 결정립계가 빨리 소멸되어 가는 반면, 2차 재결정의 핵이 되는 {110}<001>은 이동도가 빠른 결정립계가 많아진다는 것을 말하는 것으로, 2차 재결정이 일어날 때에는 일반입계와 {110}<001> 2차 재결정 핵과의 이동도 차이가 커져서 우선적으로 {110}<001>이 2차 재결정된다.1 (a) and (b), the general grain boundary and {110} <001> mean that the grain boundary is rapidly dissipated quickly at the stage just before secondary recrystallization occurs as the high temperature annealing progresses. On the other hand, {110} <001>, which is the nucleus of secondary recrystallization, refers to the increase of grain boundaries with high mobility. When secondary recrystallization occurs, mobility between general grain boundary and {110} <001> secondary recrystallization nucleus is observed. The difference is large and {110} <001> is secondarily recrystallized first.
이러한 이동도의 차이는 고온소둔중 온도가 높을수록 그 차이가 커진다. 도2는 1차 재결정판에서 주된 방위를 차지하는 {111}<112>와 2차 재결정 집합조직인 {110}<001>의 미스오리엔테이션 20~45도의 분율을 1차 재결정판 및 고온소둔중 2차 재결정이 일어나기 전의 상태의 분율을 비교한 것이다. 고온소둔이 진행되면서 온도가 증가할수록 {111}<112>의 방위와 이웃하는 결정립들을 보면, 이동도가 빠른 결정립계가 소멸되어 가고 상대적으로 이동도가 느린 결정립계가 증가하는 반면, {110}<001>은 이동도가 빠른 결정립계가 1차 재결정판에 비해 미약하게 증가한 상태로 2차 재결정온도까지 상승하게 된다. 즉, 2차 재결정이 되는 {110}<001>집합조직은 다른 것에 비해 우선적으로 빨리 성장하게 되고, 온도가 증가할수록 그 차이는 커지게 된다.This difference in mobility becomes larger as the temperature is higher during high temperature annealing. Fig. 2 shows the fraction of the misorientation of 20-45 degrees of {111} <112> which occupies the main orientation in the primary recrystallization plate and {110} <001>, which is the secondary recrystallization texture, in the first recrystallization plate and the second recrystallization during hot annealing. This is a comparison of the fraction of the state before it happened. As the temperature increases as the temperature increases, the orientation of {111} <112> and the neighboring grains show that the fast-moving grain boundaries disappear and relatively slow grain boundaries increase, while {110} <001 > Is increased to the secondary recrystallization temperature with the fast mobility grain boundary increased slightly compared to the primary recrystallization plate. That is, the {110} <001> aggregated tissue that is secondary recrystallized grows preferentially faster than the others, and the difference becomes larger as the temperature increases.
본 발명자들은 이런 점을 고려하여 새로운 2차 재결정 싸이클을 제안한 것으로, 본 발명은 고온소둔의 승온단계를 950℃까지는 승온을 25~50℃/hr의 속도로 가열하고, 950~1050℃의 구간에서는 5~14℃/hr의 속도로 가열하고, 1050~1200℃의 구간에서는 15~25℃/hr로 가열하는 단계로 설정한 것이다.The present inventors have proposed a new secondary recrystallization cycle in view of this point, the present invention heats up the temperature increase step of high temperature annealing up to 950 ℃ at a rate of 25 ~ 50 ℃ / hr, The heating is performed at a rate of 5 to 14 ° C./hr, and the heating is performed at a temperature of 15 to 25 ° C./hr in a section of 1050 to 1200 ° C.
한편, 방향성 전기강판에서 2차 재결정에서 형성된 집합조직의 연구는 최근까지 X-ray를 이용한 pole figure, inverse pole figure, ODF(Orientation Distribution Function) 등이 주를 이루었으나, 최근에는 EBSP를 이용하여 새로운 집합조직연구가 가능하게 되었다. EBSP란 Electron Back Scattered Pattern의 준말로 결정립 하나하나의 결정방위를 측정할 수 있고, 이웃하는 결정립의 회전 방위관계를 계산할 수 있다. 본 발명에서는 특히, 이웃하는 결정립의 회전 방위관계, 즉, 미스오리엔테이션 데이터를 분석하여 이를 산업적으로 이용하였다.On the other hand, the study of the aggregate structure formed by the secondary recrystallization in oriented electrical steel sheet has been mainly focused on the pole figure, the inverse pole figure, and the Orientation Distribution Function (ODF) using X-ray. Collective tissue research is now possible. EBSP is an abbreviation of Electron Back Scattered Pattern to measure the grain orientation of each grain and calculate the rotational orientation of neighboring grains. In the present invention, in particular, the rotation orientation relationship of neighboring grains, that is, misorientation data was analyzed and used industrially.
이하, 수치한정사유 및 제조방법에 대하여 설명한다.Hereinafter, the numerical limitation reason and the manufacturing method will be described.
본 발명의 강 슬라브의 화학성분 중 Si는 그 함량범위를 2.9%~3.5%로 설정하는 것이 바람직하다. 그 이유는 상기 Si의 함량이 2.9% 미만이면 강판의 비저항이 작아져서 철손특성이 나빠지고, 그 함량이 3.5%보다 많으면 강판의 취성이 증가하여 기계적인 성질이 나빠지기 때문이다.In the chemical composition of the steel slab of the present invention, the content of Si is preferably set to 2.9% to 3.5%. The reason is that if the content of Si is less than 2.9%, the specific resistance of the steel sheet decreases, and thus the iron loss characteristics deteriorate. If the content is more than 3.5%, the brittleness of the steel sheet increases and the mechanical properties deteriorate.
본 발명에서는 1회 냉연법에 비해 탈탄을 겸한 1차 재결정온도가 낮기 때문에, 상대적으로 탄소의 함량도 낮은 편이 자성에 유리하여, 그 함량범위를 0.01~0.06%로 설정하는 것이 바람직하다. 상기 C가 0.01% 미만으로 첨가되는 경우에는 고온소둔판의 2차 재결정핵이 잘 발달하지 않아 자성이 나빠지고, 반대로 0.06%보다 많이 첨가되면 탈탄이 어려워서 잔류탄소에 의한 자기시효현상이 발생한다. In the present invention, since the primary recrystallization temperature combined with decarburization is lower than that of the single cold rolling method, it is preferable that the relatively low carbon content is advantageous to magnetism, and the content range is set to 0.01 to 0.06%. When the C is added at less than 0.01%, the secondary recrystallization nuclei of the high temperature annealing plate are not well developed, and the magnetic properties are deteriorated. On the contrary, when more than 0.06% is added, decarburization is difficult, resulting in self aging due to residual carbon.
본 발명의 Mn은 0.05~0.15%의 범위로 첨가하는 것이 바람직한데, 그 이유는 상기 Mn의 함량이 0.05%미만이면 1차 재결정립 성장억제에 필요한 MnS화합물의 양이 적을 뿐 아니라, Mn과 결합하지 못한 잉여 S이 결정립계에 편석하여 엣쥐 크랙(edge crack)을 심화시켜 생산성을 저해하기 때문이다. 반대로, 상기 Mn이 0.15%보다 많이 첨가되면, 조대한 MnS가 생겨 1차 재결정 입성장 억제력이 약해진다.The Mn of the present invention is preferably added in the range of 0.05 to 0.15%. The reason is that when the Mn content is less than 0.05%, the amount of MnS compound required for primary recrystallization growth inhibition is not only small, but also combined with Mn. This is because surplus S segregates at the grain boundaries and deepens edge cracks, thereby inhibiting productivity. On the contrary, when the Mn is added more than 0.15%, coarse MnS is generated and the primary recrystallization grain growth inhibiting power is weakened.
본 발명의 S은 0.025%이하로 첨가하는 것이 바람직한데, 그 이유는 상기 S의 함량이 0.025% 보다 많으면 저온 슬라브 가열공정에서 MnS 석출물이 충분히 재고용 되지 않아 후속되는 열간압연공정에서 석출물이 조대해져 충분한 입성장 억제력을 얻는데 불리하기 때문이다.S of the present invention is preferably added in less than 0.025%, because if the content of S is more than 0.025% MnS precipitates in the low-temperature slab heating process is not sufficiently reusable, the precipitate is coarse in the subsequent hot rolling process is sufficient It is because it is disadvantageous in obtaining a grain growth suppression force.
본 발명의 Sol-Al은 총 Al함량에서 산화알루미늄으로 존재하는 Al의 양을 뺀 것을 의미하는데, 그 함량이 0.020% 미만이면 AlN양이 적어 1차 재결정립의 성장억제력이 약해져 고온소둔에서 2차 재결정이 충분히 일어나지 않고, 그 함량이 0.035%보다 많으면 AlN가 조대하게 석출하여 역시 1차 재결정립의 성장억제력이 약해지기 때문에, 상기 Sol-Al의 함량은 0.020~0.035%로 첨가하는 것이 바람직하다. 만일, 슬라브를 1400℃정도의 고온에서 가열하면 Sol-Al양을 0.04%까지 상향이 가능하나, 본 발명에서는 저온가열을 하므로 Sol-Al의 상한이 낮다.Sol-Al of the present invention means that the total Al content minus the amount of Al present as aluminum oxide, if the content is less than 0.020% AlN content is small, the growth inhibitory power of the primary recrystallization is weakened, the secondary at high temperature annealing If the recrystallization does not sufficiently occur and the content is more than 0.035%, AlN precipitates coarsened and the growth inhibitory power of the primary recrystallized grains is weakened. Therefore, the content of Sol-Al is preferably added at 0.020 to 0.035%. If the slab is heated at a high temperature of about 1400 ° C., the amount of Sol-Al can be increased to 0.04%. However, in the present invention, the upper limit of Sol-Al is low because it is heated at low temperature.
또한, Cu는 그 함량이 0.1% 미만이거나 0.2%보다 많으면 2차 재결정이 불안정하여 자성이 나빠지므로, 0.1~0.2%의 범위로 첨가하는 것이 바람직하다.In addition, if the content of Cu is less than 0.1% or more than 0.2%, the secondary recrystallization becomes unstable and the magnetic properties deteriorate. Therefore, it is preferable to add Cu in the range of 0.1 to 0.2%.
상기와 같이 조성된 강 슬라브는 1360℃ 이하의 온도에서 가열하는 것이 바람직한데, 그 이유는 1360℃보다 높은 온도에서 슬라브를 가열하면 열연판에 엣지 크랙이 발생하기 쉽기 때문이다.The steel slab prepared as described above is preferably heated at a temperature of 1360 ° C. or lower, because heating the slab at a temperature higher than 1360 ° C. tends to cause edge cracks in the hot rolled sheet.
상기 슬라브가열 이후의 공정에서 고온소둔 전까지의 제조방법은 통상의 고자속밀도 방향성 전기강판의 제조방법과 같이 실시한다. 즉, 열간압연에 의해 2.3mm의 두께로 열연판을 만든 다음 열연판 소둔을 실시하고, 최종 두께인 0.3mm로 2차 냉간압연한 후, 수소와 질소의 혼합 습윤분위기로 탈탄을 겸한 1차 재결정 소둔을 하고 수소와 질소의 혼합분위기에서 질화소둔을 실시하거나, 수소, 질소와 암모니아의 혼합 습윤분위기로 탈탄, 질화를 겸한 1차 재결정 소둔을 동시에 실시한다.The manufacturing method before the high temperature annealing in the process after the slab heating is performed in the same manner as the manufacturing method of a conventional high magnetic flux density oriented electrical steel sheet. That is, the hot rolled sheet is made to a thickness of 2.3 mm by hot rolling, followed by annealing of the hot rolled sheet, and secondary cold rolling to a final thickness of 0.3 mm, followed by primary recrystallization as decarburization in a mixed wet atmosphere of hydrogen and nitrogen. Annealing is carried out and annealing is carried out in a mixed atmosphere of hydrogen and nitrogen, or primary recrystallization annealing is carried out at the same time as a mixed wet atmosphere of hydrogen, nitrogen and ammonia.
다음, 고온소둔은 본 발명의 특징이 되는 공정으로, 승온단계를 구분하는 식으로 실시한다. 즉, 상온~950℃까지는 승온을 25~50℃/hr의 속도로 가열하고, 950~1050℃의 구간에서는 5~14℃/hr의 속도로 가열하고, 1050~1200℃의 구간에서는 15~25℃/hr로 가열하여 실시하는데, 그 이유는 다음과 같다.Next, the high temperature annealing is a process that is a feature of the present invention, is carried out in a manner of distinguishing the temperature rising step. That is, the temperature is heated to a rate of 25 ~ 50 ℃ / hr up to room temperature ~ 950 ℃, heated at a rate of 5 ~ 14 ℃ / hr in a section of 950 ~ 1050 ℃, 15 ~ 25 in a section of 1050 ~ 1200 ℃ The heating is carried out at ° C / hr, but the reason is as follows.
상온~950℃까지의 미스오리엔테이션 분포와 1차 재결정판의 미스오리엔테이션의 분포는 그리 크지 않으므로 이 구간의 승온속도는 최대한 빨리 가져가는 것이 좋다. 이 구간의 승온속도가 25℃/hr 미만이면 급속승온의 생산성 향상효과가 작고, 50℃/hr보다 빠르면 코일형태로 고온소둔을 실시함에 있어 코일 내외부의 온도편차가 심하여 자성이 불균일해 진다.The distribution of the misorientation from room temperature to 950 ℃ and the misorientation of the primary recrystallization plate is not so large. If the temperature increase rate of this section is less than 25 ℃ / hr, the productivity improvement effect of rapid temperature increase is small, and if it is faster than 50 ℃ / hr in the high temperature annealing in the form of a coil, the temperature deviation inside and outside the coil is severe, the magnetic nonuniformity.
950~1050℃구간에서 미스오리엔테이션의 분포가 집합조직 별로 크게 달라지므로, 이 구간의 승온속도는 5~14℃/hr로 서서히 가열한다. 승온속도가 5℃/hr 미만이면 1차 재결정립의 성장이 일어나서, 2차 재결정 구간의 구동력이 약해져서 2차 재결정이 불안정해지고, 14℃/hr 보다 빠른 경우에는 {110}<001>과 일반 집합조직간의 미스오리엔테이션 분포차이에 의한 결정립계 이동도의 차이를 크게 줄 수 없어 자성이 나빠진다.Since the distribution of misorientation varies greatly between aggregates in the 950-1050 ℃ section, the heating rate is slowly heated to 5-14 ℃ / hr. If the temperature increase rate is less than 5 ℃ / hr, the growth of the primary recrystallization occurs, the driving force of the secondary recrystallization section is weakened, the secondary recrystallization becomes unstable, if faster than 14 ℃ / hr {110} <001> and the general set The difference in grain boundary mobility due to the difference in misorientation distribution between the tissues can not be greatly reduced, resulting in deterioration of the magnetism.
1050~1200℃의 구간에서 승온속도를 15℃/hr 미만으로 할 경우는 생산성이 불필요하게 낮게 되고, 25℃/hr 보다 빠르게 할 경우는 2차 재결정이 불안정해진다.If the temperature increase rate is less than 15 ℃ / hr in the section of 1050 ~ 1200 ℃, productivity becomes unnecessarily low, and if faster than 25 ℃ / hr secondary recrystallization becomes unstable.
이하, 실시예를 통하여 본 발명을 설명한다.Hereinafter, the present invention will be described through examples.
(실시예1)Example 1
Si:3.15%, C:0.05%, Mn:0.12%, Sol-Al:0.028%, S:0.007%, Cu:0.1%를 포함하는 방향성 전기강판을 제강, 연주를 거쳐 슬라브를 만든 다음, 열간압연을 거쳐 2.3mm두께의 열연판을 제조하였다. 열연판을 산세하여 1100℃에서 4분간 열연판소둔을 실시한 후, 냉간압연하여 0.3mm 두께로 만든다. 1차 재결정 소둔과 질화소둔을 실시한 후, 하기 표1과 같은 조건에 따라 2차 재결정이 일어나는 고온소둔을 실시한 후 자기적 성질을 측정하고, 그 결과를 또한 하기 표1에 나타내었다.Slabs are made by steelmaking and performance of oriented electrical steel sheets containing Si: 3.15%, C: 0.05%, Mn: 0.12%, Sol-Al: 0.028%, S: 0.007%, and Cu: 0.1%, followed by hot rolling. The hot rolled plate having a thickness of 2.3 mm was prepared. The hot rolled sheet is pickled and subjected to hot rolled sheet annealing at 1100 ° C. for 4 minutes, followed by cold rolling to a thickness of 0.3 mm. After performing primary recrystallization annealing and nitride annealing, after performing high temperature annealing in which secondary recrystallization occurs according to the conditions shown in Table 1 below, the magnetic properties were measured, and the results are also shown in Table 1 below.
자기적 성질의 측정은 자장의 세기가 1000Amp/m일 때, 자속밀도의 값 B10(Tesla)을 기준으로 삼았다.The measurement of the magnetic properties was based on the value of magnetic flux density B 10 (Tesla) when the magnetic field strength was 1000Amp / m.
상기 표1에서 알 수 있는 바와 같이, 구간별 승온속도가 본 발명범위에서 벗어난 비교재(1)~(10)은 본 발명재(1)~(7) 대비 낮은 자속밀도를 나타내었다. 특히, 비교재(2),(3)은 상온~950℃구간에서의 승온속도를 빠르게 하여, 길이별 자성편차기 심하게 나타났고, 비교재(7),(8)은 1050~1200℃의 구간, 즉 고온구간에서의 승온속도를 느리게 하여, 제조원가가 높게 나타났다.As can be seen from Table 1, the comparative materials (1) to (10) that the temperature increase rate for each section is out of the range of the present invention showed a lower magnetic flux density than the present invention (1) to (7). Particularly, the comparative materials (2) and (3) increased the temperature increase rate in the section of room temperature to 950 ° C., and the magnetic deviation of each length appeared severely, and the comparative materials (7) and (8) showed a section of 1050 to 1200 ° C. In other words, the temperature rising rate in the high temperature section was slowed down, the manufacturing cost was high.
상기한 바와 같은 본 발명에 의하면, 미스오리엔테이션의 변화를 이용함으로써, 효과적으로 생산성도 우수하게 자속밀도가 높은 방향성 전기강판을 제조할 수 있는 효과가 있는 것이다. According to the present invention as described above, by using the change in misorientation, there is an effect that can effectively produce a grain-oriented electrical steel sheet with high magnetic flux density with excellent productivity.
도1(a),(b)는 탈탄판과 2차 재결정 직전의 고온소둔판에 있어서 미스오리엔테이션의 분포를 비교한 그림이다.1 (a) and (b) are diagrams comparing the distribution of misorientation in the decarburized plate and the hot annealing plate immediately before the secondary recrystallization.
도2는 {111}<112>와 {110}<001>의 1차 재결정 및 고온소둔중 20~45도의 미스오리엔테이션 분율을 나타낸 그래프이다.FIG. 2 is a graph showing the misorientation fraction of 20 to 45 degrees during primary recrystallization and high temperature annealing of {111} <112> and {110} <001>.
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| JPH07252532A (en) * | 1994-03-16 | 1995-10-03 | Nippon Steel Corp | Production of grain oriented electrical steel sheet having excellent magnetic characteristic |
| EP0947597A2 (en) * | 1998-03-30 | 1999-10-06 | Nippon Steel Corporation | Method of producing a grain-oriented electrical steel sheet excellent in magnetic characteristics |
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| EP0378131A2 (en) * | 1989-01-07 | 1990-07-18 | Nippon Steel Corporation | A method of manufacturing a grain-oriented electrical steel strip |
| JPH07252532A (en) * | 1994-03-16 | 1995-10-03 | Nippon Steel Corp | Production of grain oriented electrical steel sheet having excellent magnetic characteristic |
| EP0947597A2 (en) * | 1998-03-30 | 1999-10-06 | Nippon Steel Corporation | Method of producing a grain-oriented electrical steel sheet excellent in magnetic characteristics |
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