JP2008261022A - Grain oriented electrical decarburized annealed steel sheet, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carburized annealed sheet capable of stably producing a product sheet on an industrial scale and a method for producing the same, regarding a method for producing a grain oriented electrical steel sheet used as the material for the iron core of an electrical component. <P>SOLUTION: In the carburized annealed sheet, provided that the number density and average grain diameter of the crystal grains in the ä110}<001> orientation are denoted as N and D, respectively, and the number density and average grain diameter of the crystal grains dispersed from the grains in the ä110}<001> are defined as n and d, 8×N×D<SP>3</SP>>n×d<SP>3</SP>is satisfied. The draft in the final cold rolling is controlled to 85 to 93%, and heating speed at 600 to 800°C in carburizing annealing is controlled to ≥80°C/s. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a grain-oriented electrical steel sheet used as an electrical equipment core material, and relates to a decarburized and annealed plate that enables stable production of a good product plate on an industrial scale and a method of manufacturing the same. is there.

  The grain-oriented electrical steel sheet is a steel sheet containing about 2 to 4% Si and highly accumulating the crystal grain orientation of the product in the {110} <001> orientation (goth orientation grain). Low loss (represented by energy loss W17 / 50 with magnetic flux density 1.7T and frequency 50Hz) is required. In particular, recently, there is an increasing demand for reducing power loss from the viewpoint of energy saving, and further reduction of iron loss is desired in grain oriented electrical steel sheets.

  Various techniques have been developed for reducing the iron loss of grain-oriented electrical steel sheets. For example, Patent Document 1 discloses a technique for controlling the nitrogen partial pressure during finish annealing in an intermediate process. Further, Patent Document 2 discloses a technique for improving the crystal orientation of the product plate crystal grains by controlling the texture of the decarburized annealing plate, which is also an intermediate process.

  However, although the magnetic flux density of grain-oriented electrical steel sheets produced in the laboratory is improved by using these technologies, it is stable at the full length of the entire coil when it is manufactured on the scale of several tons on an actual production line. In particular, it is necessary to obtain high magnetic characteristics, and these techniques cannot be used as they are. For this reason, a technique for stably controlling crystal grains having good crystal orientation along with good magnetic properties is required.

Japanese Patent Laid-Open No. 7-278675 Japanese Unexamined Patent Publication No. 7-268469 Japanese Patent Publication No.40-15644 Japanese Patent Laid-Open No. 6-19335

  The present invention relates to a method of manufacturing a grain-oriented electrical steel sheet used as an electrical equipment iron core material, and provides a decarburized and annealed plate that enables stable production of a good product plate on an industrial scale and a method of manufacturing the same. Is.

The present invention has been made to solve the above problems, and the gist thereof is as follows.
(1) By mass%, Si: 2.5 to 4.5%, C: 0.02 to 0.10% or less, Al: 0.010 to 0.050%, N: 0.003 to 0.013%, Mn: 0.040 to 0.120%, S: 0.015 to 0.40%, Cu: 0.010 to 0.20%, Ti: 0.0010 to 0.0040%, the balance is a decarburized annealing plate for grain-oriented electrical steel sheets made of Fe and inevitable impurity elements, and {110} <001> oriented crystal grains in the decarburized annealing plate When the number density and average particle diameter of the crystal grains dispersed from N, D, and {110} <001> oriented grains are n and d, respectively, Directional electrical steel sheet decarburized and annealed sheet.
8 × N × D ³ > n × d ³ (1)
(2) By mass%, Si: 2.5 to 4.5%, C: 0.02 to 0.10% or less, Al: 0.010 to 0.050%, N: 0.003 to 0.013%, Mn: 0.040 to 0.120%, S: 0.015 to 0.40%, Cu: 0.010 to 0.20%, Ti: 0.0010 to 0.0040%, the remainder is a slab composed of Fe and inevitable impurity elements at a temperature of 1250 ° C or higher, and after hot rolling, hot-rolled sheet annealing is performed once or intermediate annealing. A series of two or more cold rolling including a cold rolled steel sheet with the final product thickness, followed by secondary recrystallization annealing by applying an annealing separator mainly composed of MgO to the steel sheet surface after subsequent decarburization annealing. In the grain-oriented electrical steel sheet comprising the above process, the final cold reduction rate is 85% to 93%, and the heating rate from 600 to 800 ° C in decarburization annealing is 80 ° C / s or more. A method of manufacturing a grain-oriented electrical steel sheet decarburized and annealed sheet.
(3) In mass%, Si: 2.5 to 4.5%, C: 0.02 to 0.10% or less, Al: 0.010 to 0.050%, N: 0.003 to 0.013%, Mn: 0.040 to 0.120%, S + 0.405Se: 0.005 to 0.020%, Cu: 0.010-0.20%, Ti: 0.0010-0.0040%, the balance is a decarburized annealed sheet for grain-oriented electrical steel sheets composed of Fe and inevitable impurity elements, {110} <001> in the decarburized annealed sheet The number density and average grain size of orientation crystal grains are N, D, and the number density of crystal grains dispersed from {110} <001> orientation grains and the average grain size are n and d, respectively, satisfying equation (1) Good directionality electrical steel sheet decarburized and annealed sheet.
8 × N × D ³ > n × d ³ (1)
(4) By mass%, Si: 2.5 to 4.5%, C: 0.02 to 0.10% or less, Al: 0.010 to 0.050%, N: 0.003 to 0.013%, Mn: 0.040 to 0.120%, S + 0.405Se: 0.005 to 0.020%, Cu: 0.010-0.20%, Ti: 0.0010-0.0040%, the balance is heated at a temperature of 1250 ° C or higher with a slab composed of Fe and inevitable impurity elements, and hot-rolled sheet annealing is performed after hot rolling once or Cold rolled steel sheet with the final product thickness by two or more cold rolling processes including intermediate annealing, followed by secondary recrystallization annealing by applying an annealing separator mainly composed of MgO to the steel sheet surface after subsequent decarburization annealing. In a grain-oriented electrical steel sheet consisting of a series of processes for applying a heat treatment, the final cold rolling reduction is 85% or more, and the heating rate from 600 to 800 ° C. in decarburization annealing is 80 ° C./s or more. A method of manufacturing a grain-oriented electrical steel sheet decarburized and annealed sheet.

  INDUSTRIAL APPLICABILITY The present invention enables production of a good product plate stably on an industrial scale for a grain-oriented electrical steel sheet used as an electrical equipment iron core material.

  Hereinafter, the present invention will be described in detail.

  The present inventors conducted the following experiment in order to invent a decarburized and annealed plate that enables stable production of a good product plate and its manufacturing technology. In a laboratory vacuum melting furnace, by mass, C: 0.08%, Si: 3.2%, Mn: 0.09%, Cu: 0.05%, Al: 0.03%, N: 0.009%, S: 0.029%, Ti: 0.0020 A steel ingot consisting of Fe and the balance of Fe and inevitable impurities was prepared, and after annealing at 1350 ° C. for 1 hour, hot rolling was performed to produce a hot-rolled sheet having a thickness of 2.3 mm. This hot-rolled sheet was annealed at 1140 ° C. for 120 seconds, pickled, and then cold-rolled to a sheet thickness of 0.23 mm. Further, this cold-rolled sheet was subjected to decarburization annealing at 850 ° C. for 120 seconds in wet hydrogen at various heating rates, and an annealing separator mainly composed of MgO was applied in a water slurry. After laminating the steel plates thus obtained, the temperature was raised to 1200 ° C. at a heating rate of 20 ° C./h in a hydrogen / nitrogen mixed atmosphere, and annealing was further performed in hydrogen for 20 hours. Next, after washing this steel plate with water, it was sheared to the size for single-plate magnetic measurement, and an insulating film mainly composed of aluminum phosphate and colloidal silica was applied and baked, and a magnetic flux density B8 (800 A / m magnetic field at 50 Hz) was applied. The magnetic flux density when applied) was evaluated.

  Here, the temperature increase rate in the decarburization annealing was adjusted at a temperature increase rate of 20 to 500 ° C./s in a temperature range of 600 to 800 ° C. using an electric heating method. Furthermore, orientation mapping using an EBSD (electron back-scattering diffraction pattern) apparatus was performed on this decarburized annealed plate, and crystal grains (ND // <110> grains or { 110} grains) were picked up with a likelihood of 5 degrees. At this time, the orientation mapping was performed by collecting 1/10 thickness ND surface of the decarburized plate in 20 fields with a 1 mm2 field at a measurement point interval of 2 μm. The number of {110} face grains picked up at this time was in the range of 1000 to less than 1500. Furthermore, among these crystal grains, {110} <001> orientation crystal grains existing within 5 degrees from the Goss orientation (Miller index {110} <001>) which is a coarse grain orientation of a good product plate Number of grains, average grain size, and number of grains in the range of 20-25 degrees from Goss orientation (hereinafter referred to as D-Goss = disperse Goss: grains dispersed from {110} <001> orientation grains) And the average grain size was derived. The reason for selecting D-Goss oriented grains is that D-Goss grains tend to become coarse grains next to Goss grains, but in that case, the magnetic properties are deteriorated. The method for deriving the average grain size was obtained from the number of measurement points in the crystal grains when orientation mapping was performed. The number of measurement points of each crystal grain can be easily obtained by using commercially available analysis software (for example, manufactured by TSL Solutions).

  Table 1 shows the analysis results of Goss and D-Goss grains in the decarburized annealed plate and the B8 evaluation result of the product plate. As the heating rate increased, the number N of Goss grains increased and the grain size D increased slightly. On the other hand, although the number n and the particle size d of the D-Goss grains were almost constant, they were both larger than the Goss grains. B8 was good at 1.90T or higher at a heating rate of 80 ° C / s or higher.

In the analysis of the primary recrystallization texture of the decarburized plate, the analysis from the X-ray pole figure, which is a conventional measurement method, evaluated the amount corresponding to the total area of crystal grains in any orientation. However, no matter how large the total area of Goss grains (corresponding to ND ² ), if the crystal grain size D is small, it is difficult to become coarse grains thereafter. For this reason, in order to obtain coarse grains with good orientation on the product plate, information on the total area of Goss grains measured by X-rays is not sufficient, and the number of grains N and grain diameter D are set using EBSD or the like. It is necessary to measure separately and perform an evaluation with a greater weighting on D.

Therefore, when considering the parameters ND ³ and nd ³ that gave a larger evaluation to the particle size than the parameters ND ² and nd ² corresponding to the total area, B8 was good when 8ND ³ > nd ³ . The reason for this is that when 8ND ³ <nd ³ , the frequency or grain size of Goss-oriented grains that are likely to become the most coarse grains are too small to be coarse grains, and coarse grain formation is not possible. Presumed to have stabilized. On the other hand, when 8ND ³ > nd ³ , it was judged that a good orientation was obtained because the frequency or grain size sufficient for the Goss grains to become coarse was secured, so it was limited to 8ND ³ > nd ³ .

  Based on the above findings, the present inventors have newly developed a decarburized and annealed plate form that can stably produce a grain-oriented electrical steel sheet having good magnetic properties by appropriately controlling the frequency and particle size of Goss orientation. The present invention was completed by knowledge.

  Next, practical forms in the present invention will be described below. The present invention is applied as a basic production method to a production method using AlN and MnS by Taguchi, Sakakura, etc. as main inhibitors (for example, Patent Document 3). The reason for this is that, as will be described in detail in Example 1, the present technology has found out the form of a decarburized and annealed sheet that can stably obtain good characteristics even when a temperature deviation of the steel sheet from slab heating to hot rolling occurs. This is because a manufacturing method that inevitably completely dissolves AlN and MnS at a slab heating temperature of 1250 ° C. or higher and then finely precipitates as an inhibitor and is used for improving the characteristics is targeted.

  Si is an important element for increasing electric resistance and reducing iron loss. If the content exceeds 4.5%, the material is liable to crack during cold rolling, making rolling impossible. On the other hand, if the Si amount is too low, the electrical resistance decreases and the iron loss in the product increases, so the lower limit is preferably 2.5%, and more preferably 2.8 to 3.5%.

  Although there are various roles of C, if the amount is too small, the crystal grain size at the time of slab heating becomes too large and the iron loss of the product increases. On the other hand, if the amount is too large, the decarburization annealing, which is an intermediate process, is forced to be annealed for a long time, thereby reducing productivity. For this reason, the lower limit is 0.02%, and the upper limit is 0.10%. A more suitable range within this range is 0.05 to 0.09%.

  Acid-soluble Al and N are essential elements because they combine to form AlN and function as an inhibitor. The range of acid-soluble Al is 0.010 to 0.050%, and the range of N is 0.003 to 0.013%. Below these lower limits, the function of AlN as an inhibitor is too weak to cause secondary recrystallization, and when the upper limit is exceeded, the secondary recrystallization temperature becomes too high and secondary recrystallization failure occurs. More appropriate amounts in this range are 0.020-0.035% for acid-soluble Al and 0.006-0.010% for N.

  Mn and S also bind to MnS and function as an inhibitor, which is an essential element. The range of Mn is 0.040 to 0.120%, and the range of S is 0.015 to 0.040%. Below these lower limits, the function of MnS as an inhibitor is too weak to cause secondary recrystallization, and when the upper limit is exceeded, it is necessary to increase the slab heating temperature for complete solution formation or increase the annealing time. The upper load becomes larger. More appropriate amounts in this range are 0.060-0.090% for Mn and 0.020-0.030% for S.

  When MnSe is used as described in Patent Document 4 as an alternative to MnS, the range is 0.005 to 0.020% with S + 0.405Se. Here, the coefficient 0.405 is the atomic weight ratio of S and Se. At this time, the Se content is preferably 0.010 to 0.030%, and the S content is preferably 0.001 to 0.010%. Below these lower limits, the function as an MnSe-based inhibitor is too weak to cause secondary recrystallization, and when the upper limit is exceeded, it is necessary to increase the slab heating temperature for complete solution formation or to increase the annealing time. The operational burden increases. A more appropriate amount within this range is 0.007 to 0.012% for S + 0.405Se, and the Se amount at this time is more preferably 0.014 to 0.022%, and the S amount is more preferably 0.002 to 0.005%.

  Cu forms a sulfide or Se compound to assist the inhibitors MnS and MnSe. When the lower limit is less than 0.010%, the effect of the auxiliary inhibitor cannot be obtained, which is not preferable. If it exceeds 0.20% of the upper limit value, the amount of Cu bonded to S or Se becomes too large, and the necessary minimum MnS or MnSe cannot be secured, causing a characteristic defect. A more appropriate amount of Cu in this range is 0.020 to 0.15%.

  Although Ti forms precipitates TiN, it does not act as a preferred inhibitor because of its excessively high thermal stability, and remains in the product plate, causing deterioration of properties. For this reason, the upper limit value needs to be 0.0040%. In addition, manufacturing a product with an excessively low amount of Ti causes a large cost increase from the viewpoint of raw materials and processes, so the lower limit was set to 0.0010%. A more appropriate amount of Ti in this range is 0.0015 to 0.0030%.

  Sn, Sb, Bi, B, Pb, Mo, Cr, Te, V, etc. exist as inhibitor constituent elements other than AlN, MnS, or MnSe, but these may be added. In particular, Sn and Sb are highly useful because they are concentrated at the grain boundaries and interfaces, and when added in an amount of about 0.02 to 0.15%, the characteristics are often stabilized.

  Subsequently, each condition of each manufacturing process will be described.

  The lower limit temperature of the slab heating temperature was 1250 ° C. As described above, the present invention is a knowledge of the form of the decarburized and annealed sheet that can stably obtain good characteristics even when a temperature deviation of the steel sheet from slab heating to hot rolling occurs. This is because the target is a manufacturing method in which AlN and MnS are solutely dissolved at a slab heating temperature of 1250 ° C. or more and then finely precipitated as an inhibitor and used for improving characteristics. Although the upper limit is not particularly specified, it is preferably 1450 ° C. or less for facility measures. Further, a more preferable temperature range within this range is 1300 ° C. or higher, and more preferably 1330 ° C. or higher.

  The above-mentioned slab piece becomes a hot-rolled sheet by subsequent hot rolling. The hot-rolled sheet thickness is not particularly specified because it is related to the cold rolling rate described later, but it is usually preferable to set the thickness to 1.6 to 3.3 mm. Next, this hot-rolled sheet is cold-rolled immediately or after a short time annealing. Here, short-time annealing is performed in a temperature range of 750 to 1200 ° C. for 30 seconds to 10 minutes, and this annealing is effective for enhancing the magnetic properties of the product. In the cold rolling, if the final cold rolling reduction ratio is 85% or more and 93% or less, the cold rolling may be performed twice with annealing. If the final cold rolling reduction is less than 85%, the Goss orientation increases, but the characteristics deteriorate, and if it exceeds 93%, the Goss orientation decreases significantly, making it difficult to form coarse grains on the product plate. Absent. A more preferable rolling reduction within this range is 86 to 92%. Moreover, you may perform an aging process in the range of 100-300 degreeC, and may perform a tandem rolling in the said temperature range as needed for a characteristic improvement.

  Decarburization annealing is performed in a humidified atmosphere containing hydrogen and nitrogen, and it is essential for product characteristics to reduce C to 20 ppm or less. During this time, the cold-rolled structure in the inner layer of the steel sheet causes primary recrystallization, but effective Goss orientation grains are controlled by the temperature increase rate control in the recrystallization temperature range, that is, the temperature range of 600 to 800 ° C, from the recovery of the structure at this time. The ratio increases, and a decarburized and annealed plate necessary for the production of a stable and good product plate can be obtained. In this case, effective Goss orientation grains can be secured by setting the temperature rising rate to 80 ° C./s or more, but the temperature rising rate is more preferably in the range of 100 to 500 ° C./s.

  Thereafter, a powder containing MgO as a main component is applied and coiled. Next, batch-type finish annealing is performed on this coil, and then the unwinding powder removal, slurry liquid mainly composed of aluminum phosphate and colloidal silica are applied and baked to complete the product of grain-oriented electrical steel sheet. it can.

  The finish annealing is a step of expressing good coarse grains that are important in the manufacture of grain-oriented electrical steel sheets, and is usually performed in a hydrogen-nitrogen mixed atmosphere. Among these, in the crystal grain coarsening temperature range of 850 to 1150 ° C, it is preferable to set the heating rate to about 5 to 30 ° C / h, and further, annealing is performed at a temperature of 1150 to 1200 ° C for about 20 hours. By diffusing N, S, Se or the like out of the steel plate, the magnetic properties of the product plate can be improved.

  After the finish annealing, the coil is unwound to remove the powder, and then the insulating coating is formed and the steel plate is annealed for flattening, sheared into a coil having a predetermined width and weight, and then shipped as a product.

<Example 1>
In a laboratory vacuum melting furnace, in mass%, C: 0.07%, Si: 3.3%, Mn: 0.08%, Cu: 0.08%, Al: 0.03%, N: 0.008%, S: 0.028%, Ti: 0.0025 A steel ingot composed of%, Sn: 0.08%, the remaining Fe and inevitable impurities was prepared, heated at 1320 and 1360 ° C. for 1 hour, and then hot-rolled to prepare a hot rolled sheet having a thickness of 2.8 mm. This hot-rolled sheet was annealed at 1100 ° C. for 100 seconds, pickled, and then cold-rolled to a sheet thickness of 0.27 mm. Furthermore, this cold-rolled sheet was decarburized and annealed in wet hydrogen at 840 ° C. for 150 seconds, an annealing separator mainly composed of MgO was applied as a water slurry, and 1190 ° C. × 20 under various heating conditions. Finished annealing for hours. The steel plate thus obtained was washed with water, sheared to a single-plate magnetic measurement size, coated with an insulating film mainly composed of aluminum phosphate and colloidal silica, and baked to obtain a magnetic flux density B8 (800 A / 50 Hz at 50 Hz). The magnetic flux density when a magnetic field of m was applied was evaluated.

  Here, the temperature increase rate in the decarburization annealing was adjusted in a temperature range of 600 to 800 ° C. within a range of 20 to 360 ° C./s using an electric heating method. The decarburized annealed plate is polished so that a 1 / 10-thick ND surface appears, then orientation mapping is performed using an EBSD device, and crystal grains having a <110> direction with respect to the plate surface have a likelihood of 5 degrees. I picked up at. At this time, the ND mapping of 1/10 thickness of the decarburized plate was sampled in 10 fields with a 1 mm2 field of view at a measurement point interval of 2 μm. The number of {110} face grains picked up at this time was in the range of 500 to less than 700. Further, among these crystal grains, the number of grains existing within 5 degrees from the Goss orientation (Miller index {110} <001>), the average crystal grain size, and the range from 20 to 25 degrees from the Goss orientation. The number of D-Goss grains present and the average grain size were derived. The method for deriving the average grain size was obtained from the number of measurement points in the crystal grains when orientation mapping was performed.

Table 2 shows the experimental conditions, and Table 3 shows the analysis results of Goss and D-Goss grains and the B8 evaluation results of the product plate. In Samples C to F and H to J that satisfy 80 ° C./s or higher, 8ND ³ > nd ³ and B8 was 1.90 T or higher even at 1320 ° C. where the slab heating temperature was low. This example means that good product characteristics can be stably obtained when 8ND ³ > nd ³ even if the slab heating temperature fluctuates somewhat in the actual operating conditions.

<Example 2>
In a laboratory vacuum melting furnace, by mass, C: 0.09%, Si: 3.1%, Mn: 0.08%, Cu: 0.02%, Al: 0.03%, N: 0.009%, S: 0.025%, Ti: 0.0013 A steel ingot comprising%, Sb: 0.05%, the balance Fe and inevitable impurities was prepared, heated at 1380 ° C. for 1 hour, and then hot-rolled to prepare a hot rolled sheet having a thickness of 1.4 to 3.8 mm. This hot-rolled sheet was annealed at 1080 ° C. for 120 seconds, pickled, and then cold-rolled to a thickness of 0.23 mm. Furthermore, when decarburizing and annealing this cold-rolled sheet, the temperature range from 600 to 800 ° C was increased at a rate of 250 ° C / s and annealed in wet hydrogen at 840 ° C for 120 seconds. An annealing separator as a component was applied in a water slurry. Furthermore, after finishing annealing at 1200 ° C for 20 hours, the steel sheet was washed with water, sheared to the size for single-plate magnetic measurement, and an insulating film mainly composed of aluminum phosphate and colloidal silica was applied and baked, and the magnetic flux density B8 (magnetic flux density when applying a magnetic field of 800 A / m at 50 Hz) was evaluated. The analysis method of decarburized annealing plate by EBSD was performed in the same manner as in Example 1.

Table 4 shows the relationship between the cold rolling reduction ratio, the analysis results of Goss and D-Goss grains, and the B8 evaluation results of the product plate. When the cold rolling reduction ratio was 93% or less, 8ND ³ > nd ³ and B8 was 1.90T or more, which was favorable (Claim 1). In particular, when the cold rolling rate was 85% or more, B8 was 1.92 T or more, which was even better (Claims 1 and 2). Details of the reason why B8 was better at a cold rolling rate of 85% or more are unclear, but it is presumed that the crystal orientation other than Goss was good for coarse grain formation.

<Example 3>
In the laboratory vacuum melting furnace, in mass%, C: 0.08%, Si: 3.4%, Mn: 0.08%, Cu: 0.09%, Al: 0.03%, N: 0.008%, S: 0.003%, Se: 0.003 %, Ti: 0.0022%, Sb: 0.05%, balance Fe and inevitable impurities ingot is made, heated at 1410 ° C for 1 hour, hot rolled to produce a 2.3mm thick hot rolled sheet did. This hot-rolled sheet was annealed at 1000 ° C for 60 seconds, then cold rolled to a thickness of 1.6 mm, further annealed at 1050 ° C for 120 seconds, pickled, and then cold-rolled for all sheets The thickness was 0.23 mm. At this time, the final cold rolling reduction ratio was 86%. When decarburizing and annealing the cold-rolled sheet, the temperature range from 600 to 800 ° C is raised at various speeds, and annealing is performed in wet hydrogen at 850 ° C for 120 seconds, with MgO as the main component. An annealing separator was applied in a water slurry. Further, after finishing annealing at 1200 ° C for 20 hours, after washing the steel plate with water, shearing to the size for single plate magnetic measurement, applying and baking an insulating film mainly composed of phosphate and colloidal silica, magnetic flux density B8 (magnetic flux density when applying a magnetic field of 800 A / m at 50 Hz) was evaluated. The analysis method of decarburized annealing plate by EBSD was performed in the same manner as in Example 1.

Table 5 shows the relationship between the heating rate, the analysis results of Goss and D-Goss grains, and the B8 evaluation results of the product plate. When the heating rate was 80 ° C or higher, 8ND ³ > nd ³ , and it was highly possible that the Goss grains became stable and coarse after finishing annealing at the time of decarburization annealing. Actually, B8 after finish annealing was 1.90 T or more, which was good.

Claims (4)

In mass%, Si: 2.5 to 4.5%, C: 0.02 to 0.10% or less, Al: 0.010 to 0.050%, N: 0.003 to 0.013%, Mn: 0.040 to 0.120%, S: 0.015 to 0.40%, Cu: 0.010 ~ 0.20%, Ti: 0.0010 ~ 0.0040%, the balance is a decarburized annealed sheet for grain-oriented electrical steel sheets composed of Fe and inevitable impurity elements, and the number density of {110} <001> oriented grains in the decarburized annealed sheet When the average particle diameter is N, D, the number density of crystal grains dispersed from {110} <001> oriented grains, and the average particle diameter is n, d, good directional electromagnetic waves satisfying the formula (1) Steel sheet decarburized annealed plate.
8 × N × D ³ > n × d ³ (1)   In mass%, Si: 2.5 to 4.5%, C: 0.02 to 0.10% or less, Al: 0.010 to 0.050%, N: 0.003 to 0.013%, Mn: 0.040 to 0.120%, S: 0.015 to 0.40%, Cu: 0.010 ~ 0.20%, Ti: 0.0010 ~ 0.0040%, the balance is Fe and inevitable impurity element slab is heated at a temperature of 1250 ° C or higher, hot-rolled sheet annealed after hot rolling, or twice including intermediate annealing After a cold rolled steel sheet with the final product thickness by cold rolling as described above, after the subsequent decarburization annealing, an annealing separator mainly composed of MgO is applied to the steel sheet surface and secondary recrystallization annealing is performed. A good directional electromagnetic steel characterized in that the final cold rolling reduction is 85% or more and 93% or less, and the heating rate from 600 to 800 ° C in decarburization annealing is 80 ° C / s or more. Manufacturing method of steel plate decarburized annealing plate. In mass%, Si: 2.5 to 4.5%, C: 0.02 to 0.10% or less, Al: 0.010 to 0.050%, N: 0.003 to 0.013%, Mn: 0.040 to 0.120%, S + 0.405Se: 0.005 to 0.020%, Cu: 0.010 to 0.20%, Ti: 0.0010 to 0.0040%, the balance is a decarburized annealing plate for grain-oriented electrical steel sheets made of Fe and inevitable impurity elements, and {110} <001> oriented crystal grains in the decarburized annealing plate When the number density and average particle diameter of the crystal grains dispersed from N, D, and {110} <001> oriented grains are n and d, respectively, Directional electrical steel sheet decarburized and annealed sheet.
8 × N × D ³ > n × d ³ (1)   In mass%, Si: 2.5 to 4.5%, C: 0.02 to 0.10% or less, Al: 0.010 to 0.050%, N: 0.003 to 0.013%, Mn: 0.040 to 0.120%, S + 0.405Se: 0.005 to 0.020%, Cu: 0.010 to 0.20%, Ti: 0.0010 to 0.0040%, the remainder is a slab composed of Fe and inevitable impurity elements at a temperature of 1250 ° C or higher, and after hot rolling, hot-rolled sheet annealing is performed once or intermediate annealing. A series of two or more cold rolling including a cold rolled steel sheet with the final product thickness, followed by secondary recrystallization annealing by applying an annealing separator mainly composed of MgO to the steel sheet surface after subsequent decarburization annealing. In the grain-oriented electrical steel sheet comprising the above process, the final cold rolling reduction is 85% to 93%, and the heating rate from 600 to 800 ° C. in the decarburization annealing is 80 ° C./s or more. A method of manufacturing a grain-oriented electrical steel sheet decarburized and annealed sheet.