JP4593317B2 - Method for producing grain-oriented electrical steel sheet with excellent magnetic properties - Google Patents

Description

  The present invention relates to a method for producing a grain-oriented electrical steel sheet excellent in both iron loss and magnetic flux density used as an iron core material for motors and transformers.

  The grain-oriented electrical steel sheets that are currently on the market are mainly those in which the orientation of crystals in the steel sheet is accumulated at a high level in the {110} <001> orientation (hereinafter referred to as the Goth orientation). In order to increase the degree of accumulation, complicated processes such as primary recrystallization, decarburization annealing, and secondary recrystallization are precisely controlled, and since this condition affects the degree of accumulation in the Goss direction, much research has been done. However, it is also a know-how in terms of manufacturing technology and is very important.

  A special feature of metallurgy is the use of fine precipitates called inhibitors in secondary recrystallization, which utilizes the effect of suppressing grain growth caused by this and the disappearance of this effect due to heat treatment. The secondary recrystallization is caused to increase the accumulation in the Goth direction. However, with such a conventional control method, the Goss orientation accumulation degree requires a complicated process, and the process conditions become very strict. It becomes very sensitive to the conditions, the productivity is lowered, and the grain-oriented electrical steel sheet is made a very expensive material.

  In Patent Document 1, the atmosphere and heating rate during annealing, Patent Document 2 controls slab heating conditions and nitriding, and Patent Document 3 precisely controls the heating rate during secondary recrystallization. A negative impact on productivity is inevitable. Further, although these techniques attempt to improve the characteristics in consideration of the structure of the steel sheet at the time of primary recrystallization, mainly the primary recrystallization grain size, the effect is small and the relaxation of manufacturing conditions cannot be achieved. Moreover, it cannot be said that the control to the target Goth direction is sufficient. Further, Patent Document 4 is intended to control the crystal orientation of the primary recrystallized steel sheet within a specific range, but the orientation control guidelines are ambiguous and the control method is not preferable, so that a sufficient effect is obtained. It has not reached.

JP 2004-115858 A JP 2004-204336 A JP 2004-218042 A JP 2002-60842 A

  The present invention has been made in view of such a situation. In particular, in order to increase the accumulation of the final Goss orientation in the crystal orientation, the primary recrystallization texture is preferably controlled, so that the conventional grain-oriented electrical steel sheet is not used. It provides good characteristics that were not obtained.

(1) In mass%, C: 0.040% or less, Si: 0.05 to 6.5%, Mn: 3.0% or less, Al: 3.5% or less, S: 0.055% or less, P: 0.25% or less, N: 0.040% or less, the molten steel consisting of the remainder Fe and inevitable impurities is solidified into a steel piece having a thickness of 50 mm or more by casting, and then 500 ° C or more in the hot rolling process Rolling is performed in a temperature range of F ° C. or lower. In rolling in the temperature range, rolling is performed in the rolling pass excluding the cumulative strain (logarithmic strain) H and each pass outlet temperature T (° C.) due to reduction and the final pass. The relationship between the time t (second) until the start of the subsequent rolling pass or the time t (second) until the start of water cooling after the final pass rolling in the case of the final pass is expressed by the following equation 2
T <F−H × 10−t × 10 Equation 2
In the rolling in the temperature range, at least one of the rolling passes, the shear strain or shear strain / ((thickness direction compressive strain)) in the steel sheet surface layer during rolling is 0.2 or more. , non-recrystallized structure in a surface layer 1/4 region in hot-rolled sheet time is remaining, further pickling, by performing the non-recrystallized structure is cold-rolling remains reduction of 50% or more remaining, cold rolled Integrated strength of {411} <148> orientation / integrated strength of {411} <011> orientation ≧ 4.0 and integrated strength of {411} <148> orientation at the surface layer 1/4 or the surface layer side of the plate A method for producing a grain-oriented electrical steel sheet characterized by satisfying ≧ 4.0 and secondary recrystallization of the cold-rolled sheet.
(2) In mass%, C: 0.040% or less, Si: 0.05 to 6.5%, Mn: 3.0% or less, Al: 3.5% or less, S: 0.055% or less, P: 0.25% or less, N: 0.040% or less, the molten steel consisting of the remainder Fe and inevitable impurities is solidified into a steel piece having a thickness of 50 mm or more by casting, and then 500 ° C or more in the hot rolling process Rolling is performed in a temperature range of F ° C. or lower. In rolling in the temperature range, rolling is performed in the rolling pass excluding the cumulative strain (logarithmic strain) H and each pass outlet temperature T (° C.) due to reduction and the final pass. The relationship between the time t (second) until the start of the subsequent rolling pass or the time t (second) until the start of water cooling after the final pass rolling in the case of the final pass is expressed by the following equation 2
T <F−H × 10−t × 10 Equation 2
In the rolling in the temperature range, at least one of the rolling passes, the shear strain or shear strain / ((thickness direction compressive strain)) in the steel sheet surface layer during rolling is 0.2 or more. , non-recrystallized structure in a surface layer 1/4 region in hot-rolled sheet time is remaining, further pickling, by performing the non-recrystallized structure is cold-rolling remains reduction of 50% or more remaining, cold rolled as the maximum value for the orientation distribution in the plate surface of the integrated intensity of the <411> // ND orientation steel surface layer 1/4 or than at the site of the surface layer side of the plate are present at least four, the cold-rolled plate two A method for producing a grain-oriented electrical steel sheet, characterized by performing next recrystallization.
(3) In the method for producing a grain- oriented electrical steel sheet according to (1) or (2) , in rolling in a temperature range of F ° C. or lower in hot rolling, shear strain or shear strain at the steel sheet surface layer / (sheet thickness direction compression) For a rolling pass having a (strain) of 0.2 or more, the region where the shear strain or shear strain / (sheet thickness direction compressive strain) is 0.2 or more reaches 10% or more of the total plate thickness in the plate thickness during rolling. by way directional electromagnetic, wherein to Rukoto to satisfy integrated intensity ≦ 2.0 {111} <211> orientation at the site of the surface layer 1/4 or above the surface layer side of the cold-rolled plate A method of manufacturing a steel sheet.
(4) In the method for manufacturing a grain- oriented electrical steel sheet according to any one of the items (1) to (3), {411} <148 at the surface layer 1/4 position of the cold-rolled sheet or the surface layer side thereof. A method for producing a grain-oriented electrical steel sheet, characterized in that the accumulated strength in the orientation is at least twice the accumulated strength at the thickness center of the steel plate.
(5) In the method for producing a grain- oriented electrical steel sheet according to any one of (1) to (4) , the cold-rolled sheet satisfies (B0 + B90) /2−B45≦0.040. Method for producing an electrical steel sheet.
Here, for each variable, the magnetic flux densities / T in the 0 °, 45 °, and 90 ° directions from the rolling direction when the induced current density is 5000 A / m are B 0, B 45, and B 90, respectively.
(6) In the manufacturing method of the grain- oriented electrical steel sheet according to any one of the items (1) to (5) , the steel component is mass%, and further contains Cu + Nb + Cr + B + Ni + Co + Mo + Ti: 0.2 to 8.0%. A method for producing a grain-oriented electrical steel sheet characterized by the above.
(7) In the manufacturing method of the grain- oriented electrical steel sheet according to any one of the items (1) to (6) , the steel component is in mass%, and Cu: 0.2 to 8.0%, Nb: 0. 0.1-4.0%, Cr: 1.0-15.0%, B: 0.0020-0.0150%, Ni: 0.2-8.0%, Co: 0.2-8.0 %, Mo: 0.2-8.0%, Ti: Any one or more of 0.2-2.0% are contained, The manufacturing method of the grain-oriented electrical steel sheet characterized by the above-mentioned.
(8) In the method for producing a grain- oriented electrical steel sheet according to any one of (1) to (7) , the steel component is in mass%, and one of W, Sn, Sb, Mg, Ca, Ce, and REM. Or the manufacturing method of the grain-oriented electrical steel sheet characterized by containing 2 or more types in total 0.5% or less.
(9) In the method for producing a grain- oriented electrical steel sheet according to any one of (1) to (8) , the steel components are the same except that the entire rolling pass of hot rolling is performed at F ° C or higher. In comparison with the steel plate produced in the process, the integrated strength of {411} <148> orientation at the surface layer 1/4 position of the cold-rolled sheet or the position on the surface layer side thereof is more than doubled. A method for producing a grain-oriented electrical steel sheet.
Here, F is represented by the following formula 1 depending on the components of the steel plate.
F = 820 + (10 × Si + 50 × Cu + 50 × Nb + 10 × Cr + 5000 × B + 10 × Ni + 20 × Co + 40 × Mo + 20 × Ti) Formula 1

(10) In the method for producing a grain- oriented electrical steel sheet according to any one of (1) to (9), the same except that the steel components are the same and all rolling passes of hot rolling are performed at F ° C or higher. A method for producing a grain-oriented electrical steel sheet, wherein a cold-rolled sheet satisfies B45−B′45 ≧ 0.030 in comparison with the steel sheet manufactured in the process.
Here, for each variable, the magnetic flux density / T in the 45 ° direction from the rolling direction when the induced current density is 5000 A / m is B45. B shows the characteristics of the invention steel and B ′ shows the characteristics of the comparative steel.
(11) In the method for manufacturing a grain- oriented electrical steel sheet according to any one of the items (1) to (10) , when the surface layer 1/4 of the cold-rolled sheet is removed and the thickness is measured by a thickness center layer 1/2 thickness, B45. Is reduced by 0.02 T or more. A method for producing a grain-oriented electrical steel sheet, wherein
(12) (1) - In any of the manufacturing method of the grain-oriented electrical steel sheet according to item (11), the recrystallization of the surface layer 1/4 area hot rolled sheet when cold rolled just before 90% or less A method for producing a grain-oriented electrical steel sheet, comprising:
(13) In the method for producing a grain- oriented electrical steel sheet according to any one of the items (1) to ( 12) , in rolling in a temperature range of F ° C. or lower in hot rolling, shear strain or shear strain in the steel sheet surface layer / The rolling pass whose (thickness direction compressive strain) is 0.2 or more, wherein the diameter of the rolled work roll is 700 mm or less.
In any of the manufacturing method of the grain-oriented electrical steel sheet according to item (14) (1) to (13), in rolling in the temperature range of F ° C. or less in the hot rolling, shear strain or shear strain at the steel sheet surface layer / The method of manufacturing a grain-oriented electrical steel sheet characterized by having a friction coefficient of 0.10 or more for a rolling pass having a (sheet thickness direction compressive strain) of 0.2 or more.
The method of manufacturing a grain-oriented electrical steel sheet according to any one of the paragraphs (15) (1) to (14), in rolling in the temperature range of F ° C. or less in the hot rolling, shear strain or shear strain at the steel sheet surface layer For a rolling pass having a / (sheet thickness direction compressive strain) of 0.2 or more, a shear strain or shear strain / (part of the plate thickness direction compressive strain) has a shear strain rate of 10 / s or more at a site of 0.2 or more. A method for producing a grain-oriented electrical steel sheet, comprising:
The method of manufacturing a grain-oriented electrical steel sheet according to any one of the paragraphs (16) (1) to (15), in rolling in the temperature range of F ° C. or less in the hot rolling, shear strain or shear strain at the steel sheet surface layer / (Sheet thickness direction compressive strain) When performing rolling passes of 0.2 or more multiple times and continuously, the time between each rolling pass is 4.0 seconds or less. Production method.
The method of manufacturing a grain-oriented electrical steel sheet according to any one of the paragraphs (17) (1) to (16), in rolling in the temperature range of F ° C. or less in the hot rolling, shear strain or shear strain at the steel sheet surface layer / (Sheet thickness direction compressive strain) is produced a grain-oriented electrical steel sheet characterized by performing a rolling pass of 0.2 or more several times, thereby making the cumulative total of shear strain on the steel sheet surface layer 0.6 or more. Method.
(18) In the method for producing a grain- oriented electrical steel sheet according to any one of (1) to ( 17) , in rolling in a temperature range exceeding F ° C in hot rolling, the rolling strain is 2.0 or less, or A method for producing a grain-oriented electrical steel sheet, wherein the rolling strain per rolling pass is 0.6 or less, or the time between each rolling pass is 4.0 seconds or more when performing a plurality of continuous passes. .
(19) (1) In the manufacturing method of the grain-oriented electrical steel sheet according to any one of Items to (18), after the final pass of hot rolling, characterized in that the time until the water-cooling start than 2 seconds A method for producing grain-oriented electrical steel sheets.
The method of manufacturing a grain-oriented electrical steel sheet according to any one of the paragraphs (20) (1) to (19), until the cooling rate during water cooling after the final pass of hot rolling a 10 ° C. / s or higher 700 ° C. or less A method for producing a grain-oriented electrical steel sheet, characterized by cooling.
The method of manufacturing a grain-oriented electrical steel sheet according to any one of the paragraphs (21) (1) to (20), cooled with water after the final pass of hot-rolling, cold-rolled without heating to more than 500 ° C., A method for producing a grain-oriented electrical steel sheet, characterized by annealing.
(22) (1) In the manufacturing method of the grain-oriented electrical steel sheet according to any one of Items to (21), after final annealing of 0.5% or more, a direction, which comprises applying a strain of 50% or less Method for producing an electrical steel sheet.

  According to the present invention, a grain-oriented electrical steel sheet excellent in both iron loss and magnetic flux density can be manufactured, which is most suitable for iron core materials for motors and transformers.

  The present invention is described in detail below. The present inventor has studied the optimum manufacturing conditions (especially hot rolling conditions) in order to find a manufacturing method of an electrical steel sheet having good magnetic properties, and applied {411} <148> by applying a low temperature and high pressure hot rolling technique. It was found that very strong accumulation occurred in the vicinity, in which the conventional electromagnetic steel sheet did not show such strong accumulation. Shear deformation during hot rolling plays an important role in the formation of this texture, especially due to shear deformation on the surface of the hot-rolled sheet, and the in-plane average characteristics of the magnetic properties are greatly increased after cold-rolling recrystallization. In addition, it has been found that the magnetic properties in the direction of 45 ° from the rolling direction are remarkably improved, and Japanese Patent Application Nos. 2004-8173, 2276989, and 230693 have been filed.

  While examining the change in the magnetic properties when further growing the material with a unique texture found on the surface layer of this recrystallized plate, this orientation is particularly important when secondary recrystallization occurs. The present invention has been completed by clarifying that extremely selective grain growth with respect to crystal orientation, which is not normally seen, is caused, and that remarkably good magnetic properties not found in conventional steel plates can be obtained. .

  In the conventional technology development, control of the texture before secondary recrystallization has been insufficient. Although the orientation that seems to be theoretically desirable has been proposed, there has been no knowledge about the control method to that orientation and how much control is possible to obtain a practical effect. .

  In the present invention, {411} <148>, technically, the rolling direction is the <011> direction, and the so-called α-fiber orientation further rotated by about 20 ° within the plate surface (α-fiber ± By controlling the accumulation in the 20 ° orientation, the effect of {411} <148> orientation as the primary recrystallization texture was successfully quantified and evaluated. Considering the results, not only the characteristics after secondary recrystallization, but also by controlling this orientation within an appropriate range, good characteristics can be obtained even under much simpler manufacturing conditions than in the past. The present invention has been made on the basis of the knowledge that the effective effect is great.

The present invention not only provides a high rolling reduction at a low temperature by simply lowering the hot rolling temperature, but also provides the amount of strain applied in each pass, the rolling temperature, and the holding time in a high temperature range where recrystallization after rolling can occur. It is characterized by forming a hot-rolled structure that can be optimized by taking into account optimization and sufficient effects on the properties. The main features of the present invention are as follows.
(1) In mass%, C: 0.040% or less, Si: 0.05 to 3.5%, Mn: 3.0% or less, Al: 3.5% or less, S: 0.015% or less, The steel sheet containing P: 0.25% or less and N: 0.040%, in particular, the accumulation strength of {411} <148> and {111} <211> orientations in the steel sheet surface layer portion is limited to a specific range.
(2) Cu, Nb, Cr, which suppresses crystal grain growth during slab heating, and prevents recrystallization from occurring even when a large shear strain is applied to the surface layer in rolling in a relatively high temperature range in hot rolling. An appropriate amount of elements such as Ni is contained.
(3) An unrecrystallized structure is left in the surface layer portion at the time of hot rolling, and cold rolling is performed while the unrecrystallized structure remains.
(4) In rolling in the temperature range below a specific temperature in hot rolling, the rolling pass schedule, the relationship between the high temperature holding time after rolling, the cooling conditions and the like are controlled.
(5) The shear strain or shear strain / ((thickness direction compressive strain) in rolling in a low temperature range below a specific temperature is controlled, particularly considering the strain distribution in the thickness direction.

  Next, the reason for limiting the present invention will be described. All the contents are mass%.

  C is particularly advantageous in the case of a material having a low hot rolling temperature as in the present invention, and the effect of improving the magnetic flux density by controlling the crystal orientation is particularly strong. Further, C remaining as a solid solution C has not only an effect of increasing the strength of the material but also an effect of improving the deformation resistance of the rotor, which is a problem in a high-speed motor by suppressing creep deformation. Since C content deteriorates magnetic properties, it is set to 0.040% or less. Preferably it is 0.030-0.0001%, More preferably, it is 0.020-0.0005%, More preferably, it is 0.010-0.0010%, More preferably, it is 0.008-0.0015%. Of course, like many conventional grain-oriented electrical steel sheets, the amount of carbon contained in the upper process of production is relatively high, decarburization annealing is performed during the production process, and the final product has adverse effects such as magnetic aging. It is not a problem at all for the present invention to reduce the C to such an extent that can be avoided. Further, a technique is known in which carbide is used as an inhibitor in a conventional grain-oriented electrical steel sheet. For this purpose, controlling the C content within the range of the prior art is not a problem for the present invention.

  Si is well known to increase the electrical resistance of steel sheets and reduce iron loss. It is an element that is naturally added to electrical steel sheets, and is applicable to all electrical steel sheets with the current general Si content. Is possible. In view of the balance between magnetic properties and sheet passing properties, the content is set to 0.05 to 6.5%. If it is less than 0.05%, good magnetic properties cannot be obtained, and if it exceeds 6.5%, the plate-passability in the production process is significantly deteriorated due to embrittlement. Preferably it is 0.3-5.5%, More preferably, it is 0.5-4.5%, More preferably, it is 0.8-4.0%. A general grain-oriented electrical steel sheet is manufactured at about 3.0 to 3.5%.

  Mn is an element that reacts with S to form a sulfide. Usually, when Mn is little in the middle, fine MnS may precipitate during hot rolling, which may significantly deteriorate the iron loss and magnetic flux density. However, in the present invention, by controlling the hot rolling conditions within a specific range, an effect of avoiding this adverse effect also appears, and therefore there is no particular lower limit for Mn. On the other hand, Mn has the effect of increasing the electric resistance of the steel sheet and reducing the iron loss as a solid solution Mn, but if it is contained too much, the original saturation magnetic flux density is lowered, so the upper limit is 3.0%. To do. Further, Mn is used as an inhibitor in the form of MnS or the like in conventional grain-oriented electrical steel sheets, and control within the scope of the prior art is not a problem for the present invention.

  Al, like Si, is actively added for the purpose of increasing the electrical resistance of the steel sheet and reducing the iron loss. When Al becomes high, castability deteriorates remarkably, so 3.5% or less. The lower limit is not particularly required, and Al = 0% may be used. However, if the amount is about 0.01 to 0.05%, fine AlN may be formed to deteriorate magnetic characteristics, particularly iron loss. It is. Preferably it is 0.005% or less and 0.1-3.0%, More preferably, it is 0.003% or less and 0.3-2.5%, More preferably, it is 0.002% or less and 0.5-2. 0%, more preferably 0.001% or less and 0.7 to 1.5%. Further, Al is used as an inhibitor in the form of AlN or the like in a conventional grain-oriented electrical steel sheet, and control within the scope of the prior art is not a problem at all for the present invention.

  S is directly related to the amount of sulfide. Although it is possible to suppress grain growth and recrystallization in the hot rolling step aimed by the present invention by forming sulfides in the steel, the hot rolling conditions are appropriately controlled when the content of S is large. However, this is a less preferable means because the amount of precipitation increases, which inhibits the grain growth and deteriorates the iron loss. For this reason, the upper limit is made 0.015%. In order to further improve the magnetic properties of the steel sheet, it is preferably 0.005% or less, more preferably 0.003% or less, still more preferably 0.002% or less, and still more preferably 0.001%. It may be 0%. In addition, sulfide is used as an inhibitor in conventional grain-oriented electrical steel sheets, and controlling the amount of S within the range of the prior art for this purpose is not a problem for the present invention.

  P has the effect of increasing the precipitation temperature of Cu or Mn sulfide that precipitates at a relatively low temperature, which is undesirable for the magnetic properties, and therefore can be positively added. On the other hand, since the hardness of the steel sheet is increased and the punchability is strongly affected, the amount of addition is limited by the desired punch hardness. Further, if it is contained excessively, the cold-rollability and the like are remarkably deteriorated, which may hinder the production of the steel sheet, so the upper limit is made 0.25%.

  In the steel containing Al, N is controlled to a low level of about 0.004% or less because a large amount of nitride increases the amount of nitride and hinders crystal grain growth. However, if the Al content is suppressed to about 0.005% or less, this adverse effect does not need to be considered at all. Rather, the effect of making the crystal orientation favorable by dissolving in steel as in C, the creep deformation resistance of the motor core, and the fatigue property in warm are improved, and in the case of Nb-containing steel, recrystallization is performed with NbN. Since it also has the effect of delaying, it can be added positively. However, excessive addition causes a problem of magnetic aging and steel plate defects due to microvoids generated during solidification from molten steel, so the upper limit is made 0.040%. Considering productivity, it is preferably 0.020% or less, more preferably 0.015% or less. From the viewpoint of controlling the crystal orientation, the content is preferably 0.0002% or more, more preferably 0.0005% or more, still more preferably 0.001% or more, still more preferably 0.0015% or more, and still more preferably 0.00. It is 003% or more, more preferably 0.005% or more. In addition, nitride is used as an inhibitor in conventional grain-oriented electrical steel sheets, and controlling the N content within the range of the prior art for this purpose is not a problem for the present invention.

  In the present invention, Cu forms not only solute Cu but also a metal phase mainly composed of Cu in the steel sheet (hereinafter referred to as “Cu metal phase” in this specification), and particularly recrystallization or grain growth of the steel sheet. Used to delay. This range is limited to 0.1 to 8.0%. Preferably it is 0.8 to 4.9%. When the Cu content is low, the recrystallization / grain growth retardation effect is reduced, and the heat treatment conditions for obtaining the recrystallization / grain growth retardation effect are limited to a narrow range, and the degree of freedom in management of production conditions and production adjustment is small. Become. On the other hand, if the Cu content is excessively high, the magnetic properties are greatly affected, and the iron loss is particularly increased. In addition, excessive Cu forms a Cu metal phase in steel in an undesired process depending on the thermal history, for example, forms a relatively coarse Cu metal phase at a high temperature during hot rolling, and adversely affects magnetic properties. In addition, the steel sheet may be excessively hardened or embrittled to significantly deteriorate the sheet-passability and impede productivity. A particularly preferable range is 1.0 to 3.9%. More preferably, it is 1.3-3.4%, More preferably, it is 1.5-2.9%.

  Nb as well as Cu is not only solid solution Nb in the present invention, but also Nb mainly carbon / nitride (hereinafter referred to as “Nb precipitate” in the present specification) is formed in the steel sheet to recrystallize or grain the steel sheet. Used to delay growth. This range is limited to 0.05 to 8.0%. Preferably it is 0.08 to 2.0%. When the Nb content is low, the recrystallization delay effect is reduced and the heat treatment conditions for obtaining the recrystallization / grain growth delay effect are limited to a narrow range, and the degree of freedom in management of production conditions and production adjustment is reduced. On the other hand, if the Nb content is excessively high, the magnetic properties are greatly affected, and the iron loss is particularly increased. On the other hand, although it depends on the C and N contents, excessive Nb forms excessive Nb precipitates in the steel depending on the thermal history and delays recrystallization, but causes deterioration of magnetic properties more than the above Cu metal phase. Cheap. Further, for example, when a relatively coarse Nb precipitate is formed at a high temperature during hot rolling or the like, not only the recrystallization / grain growth delay effect is reduced, but also the adverse effect on the magnetic properties may be increased. A particularly preferable range is 0.1 to 1.5%. More preferably, it is 0.12-1.0%, More preferably, it is 0.15-0.8%.

  Furthermore, Cr, B, Ni, Co, Mo, and Ti are mentioned as elements having the same effect in the above-described Cu, Nb and recrystallization / grain growth delay. These contents are similar to Cu and Nb in consideration of recrystallization / grain growth delay effect and influence on magnetic properties, Cr: 1.0 to 15.0%, B: 0.0020 to 0.0150%, Ni: 0.2-8.0%, Co: 0.2-8.0%, Mo: 0.2-8.0%, Ti: 0.2-2.0%. In order to clearly obtain the recrystallization retardation effect, it is important to contain at least one of these elements in an amount that exhibits the recrystallization / grain growth retardation effect. It is also possible to obtain the intended recrystallization / grain growth delay effect by containing two or more elements in small amounts.

  In addition, Se, W, Sn, Sb, Mg, Ca, Ce, REM, etc., in conventional grain-oriented electrical steel sheets, further improvement of magnetic properties, utilization as inhibitors, control of nitriding and oxidation, surface coating control, Elements known to be added for the purpose of improving additional functions as members such as strength, corrosion resistance and fatigue characteristics, as well as production in the manufacturing process, such as castability, annealing passability, and scrap use, are assumed by known techniques. The addition to a certain amount does not affect the present invention. Rather, there is a case where a favorable effect is exhibited as a synergistic effect. Further, when these elements are inevitably contained from raw materials, scraps, etc., and even when various other trace elements are contained, the effects of the present invention are not affected at all. In other words, needless to mention the influence of these elements, a product can be obtained without any problems in the production process disclosed in the present invention.

  Next, features of the steel of the present invention will be described. The steel of the present invention exhibits very good properties that have not been seen in the final use after secondary recrystallization, but the properties have been considered to be favorable for the properties. It is possible to define the present invention with this degree of integration, but theoretically it is natural that the characteristics improve if the degree of integration in a good orientation is increased. There is a description of this point, and it is difficult to clarify the characteristics of the present invention. Rather, the characteristics of the present invention become clear when defined in a state before secondary recrystallization occurs. In the following description, when using a grain-oriented electrical steel sheet, even if it is not finally secondary recrystallization or secondary recrystallization in a strict sense, before the abnormal grain growth by heat treatment, This will be described from the viewpoint of the texture and magnetic properties in a state in which heat treatment including primary recrystallization annealing is completed from the unrecrystallized structure after cold rolling.

  In the strict sense, the present invention is not applied only in the case of grain growth only by secondary recrystallization, when primary recrystallization and secondary recrystallization occur simultaneously, when tertiary recrystallization occurs, Further, the present invention is applied to all cases where strain-induced grain growth occurs due to strain applied for some reason. Since these may occur at the same time, and it is impossible to completely separate the actual phenomenon by the abnormal grain growth mechanism, in the present invention, the grain size grows significantly and the texture is The target is steel sheets that include processes that vary greatly. In the present invention, such grain growth is representatively described as “secondary recrystallization”, and in part, the phrase “abnormal grain growth” is also used, including the meaning of confirmation. .

  In the description of the characteristics of the present invention, the expression “azimuth accumulated strength” is used, which usually means “ratio to random strength”, which is used when displaying the texture of crystal material. , X-rays, electron beams and neutron beams are commonly used by those skilled in the art.

  The feature of the steel of the present invention is that the texture is controlled at the surface layer portion of the steel sheet, that is, at the steel sheet surface layer 1/4 or at the surface layer side. In addition, if the conditions regarding the texture in the steel sheet surface layer 1/4 or the portion on the surface layer side limited by the present invention are production conditions similar to rolling with a roll, the surface layer portion is more easily satisfied. However, if only a very thin layer of the outermost layer is satisfied, the effect of the invention will be very small. For this reason, it is preferable to satisfy at least 1/10 position of the surface layer, and if it is satisfied at 1/8 position, a sufficient effect can be obtained.

The first feature of the texture is that the accumulation in the α-fiber ± 20 ° orientation is particularly high in the surface layer compared to the conventional steel sheet. It is that it is significantly higher in the part. The α-fiber ± 20 ° azimuth is an orientation obtained by further rotating the so-called α-fiber azimuth in the plate surface by about 20 °, in which the rolling direction is the <011> direction as described above. The {411} <148> orientation, which is an important orientation, is an orientation on the α-fiber ± 20 ° orientation.
First, the necessity and effect of integration in this direction will be described.

  Conventionally, in a grain-oriented electrical steel sheet, a secondary recrystallization mechanism has been proposed due to the grain boundary character, and it has been reported that the actual phenomenon can be explained very well (CLS model). According to this mechanism, in order to develop a Goss orientation preferable as a grain-oriented electrical steel sheet after secondary recrystallization, the primary recrystallization orientation includes several orientations having a Σ9 grain boundary relationship, that is, {111 } <112>, {411} <148>, etc. are suggested to be preferred. However, among these orientations, the integration into {411} <148>, which is a feature of the present invention, is an industrial process that is currently mainstream, namely casting-hot rolling (-hot-rolled sheet annealing)-cold rolling- In the annealing process, the product does not become so high, and a product in which the {411} <148> orientation is remarkably strengthened in the steel sheet after the primary recrystallization has not been put into practical use in general. The present invention discloses a technique for remarkably increasing the degree of integration in α-fiber ± 20 ° azimuth including {411} <148> azimuth at the time of primary recrystallization by a relatively simple method, and its quantitative effect is disclosed. It has been studied and made.

  Furthermore, the feature of the present invention is that the accumulation in this orientation is high in the surface layer portion of the steel sheet. In the manufacturing range which is not particularly special, the peak intensity is in the vicinity of {411} <148> even in the α-fiber ± 20 ° azimuth. Of course, this does not exclude the case where the orientation other than this is a peak, and it is a clear feature of the steel of the present invention that the α-fiber ± 20 ° orientation is higher in the surface layer portion.

  In the present invention, the steel of the present invention is typically characterized by the {411} <148> orientation, and the integrated strength of the {411} <148> orientation at the surface layer portion of the steel plate ≧ 4.0 is defined as the limiting condition. Preferably it is 6.0 or more, More preferably, it is 8.0 or more, and it becomes 10.0 or more on a preferable component and hot rolling conditions, and a very preferable characteristic is acquired. Also, the integrated strength of {411} <148> orientation / integrated strength of {411} <011> orientation ≧ 4.0 in relation to the integrated strength of {411} <011> orientation which is the orientation on α-fiber. .

  Conventionally, in normal industrial processes, integration into α-fiber is relatively simple and there are a few {411} <001> orientations. However, in the present invention, {411} <148> orientations that are not normally developed are used. It is accumulated several times or more, and rather, the development of the {411} <001> orientation that normally exists is suppressed. From this point, it can be said that the height of integration in the {411} <148> direction controlled by the present invention is very unique. Preferably, it is 6.0 or more, more preferably 8.0 or more, and when the components and production conditions are more preferable, it is possible to accumulate more strongly 10.0 times or more than {411} <011>.

  What is interesting here is that when the α-fiber ± 20 ° azimuth characteristic of the present invention increases significantly, the spread from there, that is, the {411} <011> azimuth does not increase as a sub-azimuth. Rather, the {411} <148> orientation tends to increase with a decrease in {411} <011> orientation. Of course, this is not absolute, but from this point, it is preferable that the above-described ratio with respect to the {411} orientation is as large as possible.

  Moreover, in the steel of the present invention, the accumulation in the α-fiber ± 20 ° azimuth is increased, and therefore the accumulation in other azimuths is lowered. One characteristic on the texture is that the α-fiber orientation itself is lowered, but the effect of the invention is that the integrated intensity of {111} <211> orientation is reduced, and {111} <211> Orientation average accumulated intensity <2.0. Preferably it is 1.5 or less, More preferably, it is 1.0 or less, More preferably, it is 0.7 or less. If the texture is outside the above range, the effect of the present invention is reduced.

  The second feature of the texture is that the orientation distribution in the plate surface is more random in a sense than the conventional steel plate for the orientation in which a specific crystal plane is parallel to the plate surface. It is that you are.

  One of the specific orientations is an orientation in which the {411} plane of the crystal is parallel to the plate surface, and is generally an orientation described as {411} orientation or <411> // ND. In the conventional texture control, the accumulation in the direction in which the <011> direction is parallel to the plate rolling direction in the plate surface, generally in the direction called α-fiber, is strong. This azimuth is {411} <011>. However, if the {411} azimuth is accumulated in the {411} <011> azimuth, the intensity distribution in the plate surface with respect to the {411} azimuth is only periodic by 180 °. Since it does not have, the anisotropy in the plate surface becomes strong. In other words, the intensity distribution over the entire circumference in the plate surface with respect to the {411} orientation on the α-fiber shows only two local maximum values.

  In contrast, the present invention has an integrated intensity peak in the vicinity of the {411} <148> direction, not the {411} <011> direction with respect to the {411} direction. When the peak of this orientation becomes clear, the intensity distribution in the plate surface with respect to the {411} orientation shows periodicity in which intervals of about 40 ° and about 140 ° appear alternately, and the anisotropy in the plate surface becomes small. In other words, the intensity distribution over the entire circumference in the plate surface with respect to the {411} orientation shows four local maximum values.

  In the above description of the specific orientation, the {411} orientation has been typically described as the {411} <148> orientation, but the present invention does not limit the orientation in which the integrated strength is maximized. The {411} orientation is characterized by having more local maximum values than the two local maximum values formed by the {411} <011> orientation, and the {411} orientation has four or more local maximum values. I have it. In the {411} orientation, for example, in addition to the above {411} <148>, {411} <011> may also have a peak. In this case, the maximum value is six.

  In the present invention, the number of local maximum values in the integrated intensity distribution in the plate is specified, but in the actual plate, local fluctuations and variations in crystal orientation, measurement conditions, measurement variations, etc., or analysis of measurement data Accumulation strength varies slightly depending on accuracy, etc., and the number of local maximum values is also affected by these conditions. For this reason, in the present invention, the maximum value is defined as follows. The measuring method is not particularly limited, but it is based on a method generally used for measuring a texture. In general, a method using an electron beam or an X-ray is widely used.

  For example, when measuring with X-rays, a sample with a thickness of about 70 μm is usually taken out from the product, but when the product thickness is thin, for example, when such a sample is taken out from a plate with a thickness of about 0.12 mm, it is centered from the outermost layer. The information up to the layer will be included. In such a case, the sample thickness should be made thinner than usual so that the change in texture in the plate thickness direction becomes clear, or a method using an electron beam, such as EBSP, which is difficult to mix information in the thickness direction should be used. It is necessary to be careful.

  Further, in order to obtain the orientation distribution, a numerical analysis process is required. Generally, a three-dimensional texture analysis method called ODF or vector method is used. Measurement conditions and analysis conditions that are generally recognized are sufficient. It is assumed that the intensity distribution in the plate surface with respect to the specific surface is displayed at 72 points on the entire circumference every 5 °. If the number of display points is extremely reduced, the maximum value to be counted in the present invention is overlooked and the number of maximum values is also reduced.If the number is extremely increased, errors such as intensity variations are measured, which is unreasonable. The number of local maxima increases. In addition, regarding the maximum, it is not the intention of the present invention to count even small fluctuations that can ignore the influence on the characteristics. Moreover, even if it is maximum, those with low integration strength do not contribute to the improvement of characteristics expected in the present invention.

  In the present invention, only a maximum having an intensity higher than the average intensity in the plate surface with respect to a specific surface and having an integrated intensity 1.1 times or more of the average value of the minimum integrated intensity on both sides of the maximum is taken as the maximum number. It shall be counted. Alternatively, only the maximum that can be recognized as the maximum when the strength higher than the average strength in the plate surface with respect to the specific surface is shown and the integrated strength is indicated by contour lines of 1.0 intervals is counted as the maximum number.

  Next, characteristics of the steel sheet relating to the steel of the present invention will be described.

The feature of the steel sheet of the present invention is due to the unique texture control as described above in the primary recrystallized steel sheet, and at the time of the primary recrystallized steel sheet, the direction of 45 ° from the rolling direction compared to the conventional primary recrystallized steel sheet. It has excellent characteristics. Hereinafter, descriptions such as 0 ° characteristic, 45 ° characteristic, or 90 ° characteristic simply indicate characteristics in the direction of 0 °, 45 °, or 90 ° from the rolling direction at the time of manufacturing the steel sheet. In addition, regarding each variable below, B ₀ , B ₄₅ , and B ₉₀ are magnetic flux densities (T) in the 0 °, 45 °, and 90 ° directions from the rolling direction when the induced current density is 5000 (A / m). Further, B represents the characteristics of the primary recrystallized steel sheet according to the present invention, and B ′ represents the characteristics of the primary recrystallized steel sheet for comparison.

The specificity of the 45 ° characteristic can be described by the following points. That is, the condition (B ₀ + B ₉₀ ) / 2−B ₄₅ ≦ 0.040 is satisfied. Conventional primary recrystallized steel sheets rarely satisfy these characteristics. Preferably, the value of (B ₀ + B ₉₀ ) / 2−B ₄₅ is 0.030 or less, more preferably 0.020 or less, and still more preferably 0.010 or less. A primary recrystallized steel sheet that does not satisfy these conditions cannot obtain the desired characteristics of the present invention.

  The material characteristic from another aspect is due to the fact that in the steel sheet of the present invention, the texture control described above at the time of primary recrystallization is mainly performed in the surface layer portion of the steel sheet. The primary recrystallized steel sheet relating to the steel sheet of the present invention satisfies the above-mentioned texture and property conditions at the surface layer 1/4 or at the surface layer side. Further, since the texture of the surface layer portion is controlled in particular, there is a considerable difference from the texture of the central portion, which is also a feature of the steel sheet of the present invention. That is, the integrated strength in the {411} <148> orientation at the position of the surface layer 1/4 of the steel plate or the position on the surface layer side thereof is more than twice the integrated strength at the thickness center. Preferably 3 times, more preferably 4 times.

  However, in the present invention, when the texture control that is mainly performed on the surface layer portion is performed in the hot rolling process, the influence is not limited to the central layer because of the deformation method called rolling. For this reason, it should be noted that under the highly preferable conditions of the method of the present invention, the texture control effect equivalent to that of the surface layer portion appears even in the central portion of the steel sheet, and the difference in texture between the surface layer and the central layer may be reduced.

When performing such texture control by rolling at a relatively low temperature range in hot rolling, among normal primary recrystallized steel plates, a steel plate in which all rolling passes in hot rolling are performed at F ° C or higher In the comparison, the integrated strength of {411} <148> orientation at the position of the surface layer 1/4 or the position of the surface layer of the product plate is more than twice. It is preferably 3 times, and if production conditions are very favorable, it can reach 4 times or more. Here, F is represented by the following formula 1 depending on the amount of contained elements expressed in mass%.
F = 820 + (10 × Si + 50 × Cu + 50 × Nb + 10 × Cr + 5000 × B + 10 × Ni + 20 × Co + 40 × Mo + 20 × Ti) (Equation 1)
Further, the 45 ° characteristic satisfies B ₄₅ −B ′ ₄₅ ≧ 0.030 in comparison with the primary recrystallized steel plate in which the steel components are substantially the same and the entire rolling pass of hot rolling is performed at F ° C. or higher. This is very unique. If it is preferably 0.040 or more and 0.050 or more by applying the optimum production conditions described later, very good characteristics can be obtained.

  In addition, in comparison with a steel plate in which the above steel components are substantially the same and the entire rolling pass of hot rolling is performed at F ° C. or higher, it has a great influence on magnetic properties such as cold rolling rate and annealing temperature. If the well-known factors greatly differ, the comparison intended by the present claim makes no sense. Therefore, it is necessary to make these conditions the same within a range that does not cause a large difference in magnetic characteristics. Whether the improvement in characteristics is due to a generally known factor or the effect of the present invention is easy for those skilled in the art who are examining the influence of manufacturing conditions for the purpose of improving characteristics as a normal business. Can be distinguished.

Furthermore, since the steel of the present invention improves the overall characteristics of the steel sheet after secondary recrystallization by improving the characteristics of the surface layer portion of the primary recrystallized steel sheet as described above, for example, the surface layer of the primary recrystallized steel sheet If the portion is removed, the effect of the invention is reduced. The amount of deterioration of characteristics depends on the grinding amount of the surface layer. By this, the invention steel is defined, and when the surface layer 1/4 of the primary recrystallized steel sheet is removed and the thickness is measured by the thickness of the central layer 1/2, B ₄₅ is One characteristic of the steel of the present invention is that it decreases by 0.02 T or more. However, if the characteristic texture control of the invention extends to the center of the plate thickness as described above, it is necessary to pay attention because the characteristic deterioration margin due to the surface layer removal becomes small. This is what essentially different from that deterioration of B ₄₅ be removed surface layer in B ₄₅ is low material as in the conventional primary recrystallization steel is small, the steel sheet having such a very good B ₄₅ Is naturally included in the present invention.

  As one method for performing the texture control as described above, it is effective to perform the cold rolling and annealing in the hot rolled sheet with the rolled structure remaining in the surface layer portion. The unrecrystallized structure needs to remain at least in the region of the surface layer 1/4. In other words, even if an unrecrystallized structure remains in the thickness center layer, the effect of the present invention is reduced if the surface layer 1/4 region has a complete recrystallized structure. In order to obtain the effect of the invention more remarkably, it is preferable that a large amount of unrecrystallized structure remains in a portion close to the outermost layer. If the surface layer 1/8 region is completely unrecrystallized structure, the target characteristics are Very good.

  In addition, the effect of the invention is very preferable if the surface layer 1/4 region is completely unrecrystallized, but an effective effect is obtained if the recrystallization rate is 90% or less even if it is not completely unrecrystallized. Needless to say, it is preferably 70% or less, more preferably 50% or less, and further preferably 30% or less.

  It is also useful to partially include a recrystallized structure in the hot-rolled sheet before cold rolling for the following reasons. In other words, depending on the steel composition and hot rolling conditions, when a product is manufactured by cold rolling, primary recrystallization annealing, or secondary recrystallization annealing, which is a fully processed structure, primary recrystallization without abnormal grain growth occurs. There are cases where fine-grained regions where the structure remains almost as it is may remain, which may cause deterioration of magnetic properties, and by controlling the morphology of precipitates, the grain growth during annealing is improved and the magnetic properties are improved. If necessary, a part of the processed structure can be recrystallized by an appropriate heat treatment for the purpose of improving this. Since the conditions vary depending on the steel components, etc., it cannot be generally stated, but those skilled in the art having ordinary techniques can appropriately control the range depending on the control of the hot rolling coil temperature and the annealing conditions of the hot rolled sheet. It is easy to control.

  As a guideline, when the coiling temperature after hot rolling exceeds 750 ° C., a recrystallized structure appears. When continuous hot-rolled sheet annealing is performed, if the Si content is about 1% or less, 700 ° C. If it exceeds 750 ° C., the recrystallized structure will appear if the material has a Si content of about 2% or more. These temperatures can be controlled in a wider temperature range by adding an appropriate amount of an element that exhibits an effect of suppressing recrystallization in hot rolling, particularly Cu and Nb.

  The mechanism for obtaining the effects of the present invention is considered as follows. That is, the crystal rotation is greatly different from that assumed in normal rolling due to deformation mainly of shear deformation applied to the steel sheet surface layer during hot rolling. Specifically, it is generally considered that the α-fiber orientation is strongly developed by crystal rotation by rolling, and when this is further cold-rolled to increase the accumulation in the α-fiber orientation and perform final annealing, secondary re-generation is performed. The {111} <211> orientation that is preferable for crystals develops, but the {111} <011> orientation that is not preferable for magnetism also develops, and the α-fiber orientation itself remains as a recrystallization orientation. Therefore, in the conventional electromagnetic steel sheet, the hot rolled sheet structure is recrystallized, and the process conditions are taken such that the accumulation in the α-fiber direction is eased and the relatively random direction is set before the cold rolling.

  In addition, the unique deformation texture that develops due to shear deformation on the surface of the steel sheet during hot rolling causes the amount of strain on the surface of the steel sheet to be higher than that of the central layer. Therefore, the effect on the final product due to its existence was not taken care of. In contrast, the steel of the present invention consciously retains the strain due to shear deformation applied to the surface layer of the hot-rolled steel sheet, accumulates it by suppressing recrystallization, and is unique in the steel sheet before cold rolling. The crystal orientation is maintained. Specifically, the orientations are accumulated in the vicinity of {311} <233> and {110} <001>.

  When this is cold-rolled, crystal rotation different from that of a general random orientation is caused. In bcc metal, the α-fiber orientation is strongly developed by cold rolling in principle, so that the texture characteristic is not remarkable at the time after cold rolling, but among them, α does not develop so strongly in ordinary materials. This indicates a characteristic that a recrystallization nucleus of −fiber ± 20 ° orientation exists and a specific α-fiber ± 20 ° orientation develops strongly after recrystallization. Other mechanisms are conceivable, but the above mechanism seems to work strongly for the method of performing cold rolling while the hot rolled working structure remains on the steel sheet surface layer described in this specification. It is.

  Thus, if only the {411} <148> orientation is preferentially developed at the time of primary recrystallization, due to the Σ9 grain boundary relationship (CLS model), after secondary recrystallization (abnormal grain growth), The development of Goth direction becomes more remarkable than before.

  Next, in order to obtain the effects of the present invention remarkably, manufacturing conditions that are important limiting factors will be described.

  The grain-oriented electrical steel sheet according to the present invention is obtained by casting molten steel comprising the above-described components into a steel slab, hot-rolling, pickling, cold-rolling, primary recrystallization annealing, and decarburization annealing as necessary. It can be obtained by subsequent recrystallization annealing (or grain growth annealing). In this case, the outline of the process is not greatly different from that of the normal process, but in particular, the effects of the invention can be sufficiently obtained by the following characteristic hot rolling conditions.

  In particular, the temperature range in which strain due to rolling is imparted by hot rolling, the amount of strain imparted, and the holding time in the temperature range where recrystallization may occur after imparting strain are important requirements in the present invention. And by controlling this within the scope of the invention, the effect of the present invention can be obtained accurately.

  Regarding the temperature, it is preferable that a large portion of the hot rolling is performed in a temperature range of F ° C. or lower represented by the following formula 1 determined by the amount of contained elements expressed in mass%.

F = 820 + (10 × Si + 50 × Cu + 50 × Nb + 10 × Cr + 5000 × B + 10 × Ni + 20 × Co + 40 × Mo + 20 × Ti) (Equation 1)
The range below this temperature is referred to as the low temperature range in the present invention. When the temperature is too high, the effect of the present invention is lost. On the other hand, if the temperature range is too low, not only rolling is difficult, but the effect of the invention is also reduced. The lower limit of the rolling temperature is preferably lower in order to suppress the progress of recrystallization of the processed structure formed by rolling in the hot rolling process, but the lower limit of the temperature range is preferably 500 ° C., more preferably 550 from the viewpoint of rollability. ° C, more preferably 600 ° C, more preferably 650 ° C.

  Regarding the hot rolling temperature, there is a problem in terms of workability if the temperature conditions are significantly different from those of general materials manufactured by recrystallizing ordinary hot rolled sheets. Usually, considering the workability when the sheet is passed at the same chance as a general material rolled at a finishing temperature of about 850 to 950 ° C., recrystallization inhibitor elements such as Cu, Nb, and Ni are added. It is preferable to hot-roll in this temperature range.

The upper limit of the temperature range is preferably F-40 ° C, more preferably F-80 ° C, more preferably F-120 ° C, more preferably F-150 ° C, and more preferably F-180 ° C. If it is F-210 degrees C or less, it will become possible to acquire the effect of this invention very notably. If rolling is performed in this temperature range, a preferable temperature range can be maintained by processing heat generation unless it is an extremely low speed and light pressure pass schedule. The rolling conditions in such a low temperature range relate to the rolling temperature, the amount of strain to be applied, and the holding time, and the cumulative strain (logarithmic strain) H, each pass outlet temperature T (° C.) and the time after rolling in the low temperature range. The relationship of t (seconds) is T <F−H × 10−t × 10 (Equation 2)
It is preferable to satisfy. This corresponds to the fact that when T is F or more, recrystallization proceeds during hot rolling, making it difficult to obtain a preferable non-recrystallized structure. Moreover, since the progress of recrystallization is promoted as the strain applied by rolling increases, it is indicated that it is preferable to suppress T by lowering T as H increases.

  Here, t is the time from rolling to the start of the next rolling pass in the rolling pass excluding the final pass, or in the case of the final pass, the time from the final pass to the start of water cooling. This is because recrystallization proceeds with the passage of time after rolling, so if the holding time in the temperature range where recrystallization can occur before rolling or water cooling after the rolling in a certain pass becomes long. It shows that T needs to be lowered in order to suppress recrystallization. Or, needless to say, in other words, the necessity of shortening t in order to suppress recrystallization is also shown.

  With regard to t, when using the current equipment, the roll stand interval and the rolling speed are unambiguously determined except for the final pass. Changing the roll stand interval is not realistic, and changing the rolling speed is Since it affects the productivity, the control factor is very limited. On the other hand, in the case of the final pass, it is the time until the start of water cooling, and depending on the conditions, it is necessary to take equipment measures such as newly installing a water cooling nozzle, but in general, it is a factor for significant control. . In the present invention, the effect becomes remarkable by setting the time from the last pass to the start of water cooling to 2 seconds or less. Preferably it is 1.5 seconds or less, More preferably, it is 1.0 second or less, More preferably, it is 0.5 second or less, More preferably, it is 0.2 second or less.

  It is also effective to increase the cooling rate during water cooling after the final pass in order to suppress the progress of recrystallization of the hot-rolled sheet. Preferably it is 10 degrees C / s or more, More preferably, it is 20 degrees C / s or more, More preferably, you may be 40 degrees C / s or more. The temperature after water cooling becomes the coil winding temperature as it is, and is maintained for a relatively long time in the temperature range in the vicinity thereof. Therefore, it is effective to lower the temperature in order to suppress recrystallization. Although it depends on the components and the amount of strain accumulated in the steel sheet, it is 700 ° C. or lower. Although the coil temperature decreases after winding, the cooling rate is very slow, and when the holding time near the winding temperature is long, it reaches several hours or more. For this reason, when the coiling temperature is close to 700 ° C. with a high purity material, recrystallization may proceed sufficiently. For this reason, it is preferably 650 ° C. or lower, more preferably 600 ° C. or lower, more preferably 550 ° C. or lower, and if it is 500 ° C. or lower, in most cases, the progress of recrystallization stops.

  Although it seems difficult to write in this way, the main point is that it is necessary to suppress recrystallization of the steel sheet, and based on the general knowledge that recrystallization occurs easily under conditions of high strain, high temperature, and long time. Just determine the conditions. These conditions change when the product specifications such as pass schedule, hot-rolled sheet thickness, etc., and the steel composition according to the application change, so it is impossible to define them unconditionally, including (Equation 1) as a guideline. However, a person skilled in the art having ordinary metallurgy knowledge can easily determine the conditions for each specification and application after several trials.

  In particular, the kind of strain imparted by hot rolling in a low temperature region is also an important requirement in the present invention. The strain needs to have a large shear strain, and the shear strain or shear strain at the steel sheet surface layer / (sheet thickness direction compressive strain) needs to be 0.2 or more. Preferably it is 0.3 or more, More preferably, it is 0.4 or more, More preferably, it is 0.6 or more, More preferably, it is 0.8 or more, More preferably, it is 1.0 or more. By controlling the rolling temperature and shear strain in this way, it is possible to obtain a very specific effect that could not be obtained when rolling at low temperature or when applying a large strain without considering the rolling temperature. It becomes possible.

  The conditions relating to the rolling temperature and the rolling strain described here are hereinafter referred to as “shear strain conditions in a low temperature region”. With regard to “shear strain conditions in a low temperature region”, in particular, regarding the conditions regarding strain, it is necessary to satisfy the surface layer of the plate during hot rolling when the strain is applied during hot rolling. Although these can be actually measured, since it takes time, it is also possible to use a generally recognized numerical calculation such as a finite element method. Generally, temperature and strain have a distribution in the plate thickness direction, and the value of shear strain or shear strain / (plate thickness direction compressive strain) specified by the present invention varies depending on the position in the plate thickness direction. It is normal to be.

  In consideration of this distribution, it is preferable that the region satisfying the “shear strain condition in the low temperature region” reaches 10% or more of the total plate thickness in the plate thickness during rolling. More preferably, it is 20% or more, more preferably 25% or more, and there is no particular limitation, but when the strain or temperature distribution on the front and back surfaces of the plate is symmetrical with respect to the center of the plate thickness, the surface layer 25% or more means 50% or more in the total thickness, and a sufficient effect can be obtained. More preferably, it is 30% or more, more preferably 40% or more, and it is needless to say that the total thickness preferably satisfies this condition.

  A rolling pass that generates a shear strain that satisfies such a “shear strain condition in a low temperature range” can be controlled by changing a friction coefficient, a roll diameter, and the like in the pass. It is preferable that the friction coefficient is 0.05 or more and the diameter of the rolled work roll is 700 mm or less. The friction coefficient is more preferably 0.10 or more, more preferably 0.15 or more, further preferably 0.20 or more, more preferably 0.25 or more, more preferably 0.30 or more, and further preferably 0.40 or more. More preferably, it is 0.50 or more. The diameter of the rolled work roll is more preferably 600 mm or less, further preferably 500 mm or less, more preferably 400 mm or less, further preferably 300 mm or less, and further preferably 250 mm or less.

  In the present invention, the conditions are not particularly limited, but it is also possible to impart shear strain by so-called “different circumferential speed rolling” that makes a difference in the rotational speed of the upper and lower rolls during rolling. In this case as well, it goes without saying that the temperature, the amount of strain, and the like must be within the scope of the present invention in order to obtain the effects of the present invention. Such different peripheral speed rolling is not carried out in a general rolling operation, but its effect is well known as a technique for controlling shear strain, and to the target characteristics in the present invention. As described above, as described above, it can be expected to exert the same changes and effects as the control of the hot rolling conditions in which the conditions are described in detail in the present invention. Needless to say, in different peripheral speed rolling, the effect increases as the peripheral speed difference increases, as is well known in principle.

  In the present invention, the strain rate of the shear strain that satisfies the “shear strain condition in a low temperature range”, the integrated value when applied multiple times, and the time interval are important. Usually, since distortion is given by continuous multi-pass rolling, this will be described below. It is preferable that the strain rate of each rolling pass is 10 / s or more with respect to the rolling pass satisfying the “shear strain condition in a low temperature region”. More preferably, it is 20 / s or more, More preferably, it is 40 / s or more, More preferably, it is 80 / s or more, More preferably, it is 120 / s or more, More preferably, it is 180 / s or more, More preferably, it is 260 / s or more.

  Further, when the rolling pass satisfying the “shear strain condition in the low temperature region” is performed a plurality of times, the effect of the invention is particularly effective when the total number of shear strains satisfying the “shear strain condition in the low temperature region” is 0.6 or more. It is remarkable. More preferably 0.8 or more, more preferably 1.0 or more, more preferably 1.5 or more, further preferably 2.0 or more, more preferably 2.5 or more, more preferably 3.0 or more, further preferably Is 3.3 or more, more preferably 3.5 or more. Furthermore, when rolling passes that satisfy the “shear strain condition in a low temperature region” are performed a plurality of times and continuously, the time between the rolling passes is preferably 4.0 seconds or less. More preferably, it is 3.0 seconds or less, More preferably, it is 2.0 seconds or less, More preferably, it is 1.0 second or less, More preferably, it is 0.5 second or less.

  Although the cause of the influence of the conditions for imparting these strains is not clear, although it is in the low temperature range, the recovery and recrystallization proceed at least during or immediately after rolling in this temperature range. This is probably because accumulation and crystal rotation do not occur efficiently. In particular, in addition to ultra-low C, N, and S, as in recent materials, high-purity materials including Ti and Cu and other trump elements cause recovery and recrystallization behavior faster than conventional materials. Such consideration is important.

  The steel of the present invention has a specific texture at the time of primary recrystallization by causing a specific crystal rotation in the surface layer of the steel sheet by rolling in the low temperature range described above. By providing an appropriate amount, an important effect of suppressing the remaining of a fine structure remaining after secondary recrystallization and possibly inhibiting magnetic properties is also exhibited. This fine structure is not phagocytosed by the secondary recrystallized grains, and basically has the same orientation as the primary recrystallized structure. Therefore, the characteristics deteriorate after the secondary recrystallization. This effect exerts a preferable effect by reducing the temperature in a temperature range slightly exceeding F ° C. according to (Equation 1). This temperature range is referred to as an intermediate temperature range in the present invention. Although this temperature exceeds F ° C., it is necessary to be careful because the effect is reduced when the temperature is too high as will be described later. Preferably it is F + 150 degrees C or less, More preferably, it is F + 100 degrees C or less, More preferably, it is F + 50 degrees C or less.

  The strain applied in this intermediate temperature range is set to 3.0 or less. However, since the effect of the present invention is manifested by a large distortion in the low temperature range, it is preferable that the distortion in the mid range does not exceed the distortion in the low temperature range. The amount of strain is preferably 2.0 or less, more preferably 1.5 or less, still more preferably 1.0 or less, and still more preferably 0.5 or less.

  The lower limit is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more in order to reduce the anisotropy of the final product and to suppress ridging that is a problem particularly in non-transformed steel. . Further, when rolling in the middle temperature region is performed in a plurality of passes, the average strain per pass is 0.6 or less, preferably 0.5 or less, more preferably 0.4 or less.

  These preferable ranges also depend on the time between passes of rolling in a high temperature range, and the time between passes is preferably 4.0 seconds or more. If one of these conditions is satisfied, an effect of reducing ridging can be obtained, but it goes without saying that the effect becomes more remarkable if two or more conditions are satisfied.

  This strain imparted in the middle temperature range destroys the texture caused by the columnar structure formed during casting, and then immediately rolled in the low temperature range, thereby removing the fine grain structure that had been a problem in low temperature hot rolling. Demonstrate the effect.

  The mechanism by which the method of the present invention is effective for suppressing the residual fine grain structure is not clear, but is considered as follows. That is, it seems that one of the causes is that the rolling conditions in the middle temperature range are the conditions under which recrystallization occurs slightly, and the crystal structure before the rolling in the low temperature range starts substantially fine. Furthermore, by applying a special deformation to the microstructure that has been rolled in the middle temperature range by shear strain in the low temperature range, spatial uneven distribution of similar crystal orientations that cause the microstructure to remain, what are called colonies Seems to be destroyed. This effect is very favorable especially for high-Si materials that are non-transformed steels, and this effect cannot be realized by the prior art. The present invention improves the integration in the orientation represented by the {411} <148> orientation. This is a characteristic effect of steel.

  Since the occurrence of the above phenomenon depends on the amount of strain applied, the thickness of the steel slab before hot rolling is required to some extent. In this invention, the thickness of the steel piece before hot rolling shall be 20 mm or more. Preferably it is 50 mm or more, Preferably it is 100 mm or more, More preferably, it is 150 mm or more, More preferably, it is 200 mm or more.

  When the thickness of the steel slab is 20 mm or less, even when hot rolling under low temperature and high pressure within the scope of the present invention is performed, {100} texture resulting from the columnar structure formed with solidification during casting remains. The texture effect characteristic of the present invention cannot be exhibited.

  The cause of this is not clear, but the amount of strain in the low temperature range, which is a feature of the present invention, is within the scope of the invention in order to destroy the {100} orientation having very strong in-plane anisotropy caused by the columnar structure. Even if this is not sufficient, it is considered that a large strain is required in the total hot rolling.

  The manufacturing process of the steel slab is not particularly limited, but it is best from the viewpoint of cost that it is manufactured by continuous casting from a normal melting process. Moreover, it is preferable that the heating temperature of the slab at the time of hot rolling shall be 1250 degrees C or less. This is because the precipitates, particularly sulfides and nitrides are coarsened to be harmless and effective in reducing iron loss, and the thermal history is favorable for low temperature rolling, which is a feature of the present invention.

  In other words, if the slab is heated at 1200 ° C. or higher as in the normal hot rolling conditions, the slab is removed from the heating furnace when trying to obtain a heat history such that most of the rolling required in the present invention is performed in a low temperature region. This is because it is necessary to perform cooling after taking out, which hinders cost and productivity. Preferably it is 1100 degrees C or less, More preferably, it is 1000 degrees C or less.

  In addition, from the viewpoint of lowering the rolling temperature, although it may be a factor in inhibiting productivity, it has been required at the time of secondary recrystallization using a conventional inhibitor sufficiently, 1300 ° C. or higher, and further 1350 The effect of the present invention is not lost even if slab heating at a temperature of ℃ or higher is performed.

  As a process after hot rolling, it is necessary to perform cold rolling with an unrecrystallized structure remaining, and it is not necessary to dare to perform hot-rolled sheet annealing generally performed with some materials. When the temperature is raised due to some necessity such as improvement of the plate passing property, it is unnecessary to worry that recrystallization proceeds and the effect of the present invention is lost unless the temperature is raised to 500 ° C. or higher. Cold rolling and annealing may be performed as usual. After cold rolling, recrystallization annealing, film formation, etc. are performed in the same steps as those for ordinary grain-oriented electrical steel sheets. These conditions are not particularly limited with respect to the effects of the present invention, but when the above hot rolling conditions are applied, the cold rolling rate is preferably 50% or more from the viewpoint of improving the magnetic flux density. If the cold rolling rate is too low, the texture development characteristic of the present invention may hardly occur.

  The effects of the present invention improve magnetic flux density, reduce iron loss and improve stress sensitivity. These are basically considered to be the effects of the texture improvement in the present invention. Further, Cu, Nb, Ni and the like added as recrystallization inhibiting elements exhibit effects such as precipitation strengthening in addition to solid solution strengthening, and are effective as high-strength electrical steel sheets.

  In addition, the technology of the present invention is applied to a manufacturing process that uses decarburization annealing or the action of an inhibitor during secondary recrystallization, which has been generally performed in the manufacture of conventional grain-oriented electrical steel sheets. However, the manufacturing process is not limited to that of the conventional grain-oriented electrical steel sheet. That is, for example, when the amount of C is lowered in the degassing process at the time of molten steel, and when secondary recrystallization (abnormal grain growth) is caused without using a decarburizing process or a particularly conscious inhibitor In addition, it is possible to obtain a grain-oriented electrical steel sheet having very good characteristics after secondary recrystallization (abnormal grain growth).

  When decarburization is not required, primary recrystallization can be performed in a normal continuous annealing line, and productivity is improved. In addition, when the inhibitor is not used, the degree of orientation accumulation may be somewhat inferior to that using the inhibitor, but secondary recrystallization is completed at a relatively low temperature and in a short time. Therefore, it can be applied without using a special annealing furnace, and precise control of the atmosphere and heating temperature is not required. Further, it is not necessary to use an annealing separator, and secondary recrystallization (abnormal grain growth) in a normal continuous annealing line is possible, and a significant reduction in production cost is achieved.

  In the present invention, the characteristic of the primary recrystallized steel sheet characteristic is that the characteristic in the 45 ° direction is excellent, but strictly speaking, the best characteristic is not in the 45 ° direction but may be deviated from this. This is natural because the magnetic properties are due to the influence of all the crystals in the steel sheet having various orientations other than the α-fiber ± 20 ° orientation characteristic of the present invention. However, the influence is small, and the present invention describes that the 45 ° direction characteristic is typically excellent.

The characteristics describing the characteristics are “magnetic flux density in the direction of 0 °, 45 °, 90 ° from the rolling direction when the induced current density is 5000 A / m”, that is, B ₀ , B ₄₅ , B _90. It is possible to describe other characteristics. For example, it can be defined by the magnetic flux density when the induced current density is different. In this case, naturally, the absolute value of the defined value is also different. Furthermore, the effect of the invention can be evaluated not by the magnetic flux density but by iron loss, magnetostriction, and the like.

  Depending on the target characteristics, the magnitude of the absolute value may be reversed, for example, the iron loss shows the lowest value in the direction in which the magnetic flux density is highest. These characteristics are closely related to each other and qualitative relations are well known, and can be easily assumed by those skilled in the art having general knowledge. “Rolling when the induced current density is 5000 A / m” This is essentially the same as the present invention evaluated by “the magnetic flux density in the directions of 0 °, 45 °, and 90 ° from the direction”.

Examples will be described below. The magnetic properties of the primary recrystallized steel sheet were measured in the direction of 0 °, 45 °, and 90 ° from the coil rolling direction with a sample having a size of 55 mm × 55 mm. The magnetic flux density was evaluated by commonly used B ₅₀ and W _15/50 . B ₀ , B ₄₅ , B ₉₀ , and B _ave are magnetic flux densities in directions of 0 °, 45 °, and 90 °, respectively, and {(0 ° characteristic) + 2 * (45 ° characteristic) + (90 ° characteristic)} / 4. Means the in-plane average magnetic flux density. The texture was measured by X-ray at the surface 1/8 site and the center of the sample and analyzed by a three-dimensional vector method.

  Determination of “shear strain conditions in a low temperature region”, determination on the thickness of the shear region, shear strain rate, and cumulative shear strain were determined by FEM calculation. The FEM calculation was performed under a pass condition such as a roll diameter and temperature using a model in which a steel material to be rolled was equally divided into 20 in the plate thickness direction. The determination was made based on the results for the part corresponding to the position of the surface layer 1/4. If it is a normal condition, if it is judged on the surface layer side from this, the amount of shear strain will increase, and it will be easier to satisfy the conditions of the present invention. It will be difficult to satisfy. In the present invention, the texture change in the thickness direction of the actually manufactured plate and the influence on the characteristics are considered, and the determination is made at a 1/4 position of the plate thickness.

It is well known that the iron loss shows an inverse correlation with the magnetic flux density. The display in each direction is omitted, and {(0 ° characteristic) + 2 × (45 ° characteristic) + (90 ° characteristic)} / 4 is obtained. The in-plane average value obtained is shown. After secondary recrystallization, the magnetic properties of the sample collected from the central part of the coil width were investigated by the Epstein method. The characteristics were evaluated by the magnetic flux density B ₈ when excited at 800 A / m and the iron loss W _17/50 when excited by alternating current up to 1.7 T at 50 Hz.

Conditions 1 to 5 in Tables 2 to 7 are as follows.
(Condition 1)
×: There is no rolling pass that satisfies the “shear strain condition in the low temperature region”. ○: There is at least one pass that satisfies the “shear strain condition in the low temperature region” (condition 2).
In rolling in a temperature range exceeding F ° C in hot rolling,
-Rolling strain is 2.0 or less,
-Rolling strain per rolling pass is 0.6 or less,
-The time between each rolling pass is 4.0 seconds or more when performing multiple passes continuously.
X: Not satisfied at all ○: At least one satisfied (Condition 3)
Ratio of the strength of {411} <148> orientation at the 1/4 position of the surface layer with a steel plate in which the steel components are substantially the same and the entire rolling pass of hot rolling is performed at F ° C or higher (Condition 4)
For B _45, reduction amount when the removal of both surface layers 1/4 (Condition 5)
For B _45, the difference between experimental steps of the steel sheet steel components substantially same as and total rolling pass of hot rolling is performed at F ° C. or more, to produce a regular grain oriented electrical steel sheet and non-oriented electrical steel sheet It is almost the same as the case. The steel was melted and formed as a continuous cast slab, hot rolled, pickled, cold rolled, annealed, and the properties were measured at the time of the primary recrystallized steel sheet. Annealing was performed in a decarburizing atmosphere as necessary. Then, if necessary, annealing in a nitriding atmosphere and an annealing separator were applied, followed by secondary recrystallization annealing, and if necessary, a film was formed on the surface to obtain a product plate, and the characteristics were evaluated. Hot rolling, which is an important point in the present example, was performed by rough hot rolling 6 passes, finishing hot rolling 6 passes or 7 passes, and each pass was evaluated for conformity to the production method of the present invention.

<Example 1>
As an inhibitor of secondary recrystallization, the effect of the present invention was examined in the case of a production method according to a grain-oriented electrical steel sheet produced mainly using nitride formed by nitriding. The slab of steel A having the components shown in Table 1 was heated to 1150 ° C. and hot rolled to a plate thickness of 2.3 mm. Table 2 shows the hot rolling conditions. Then, it cold-rolled to 0.22 mm thickness. This cold-rolled sheet was annealed in a decarburizing atmosphere at 820 ° C. for 120 seconds to obtain a primary recrystallized steel sheet having a C content of 0.002%, and this property was evaluated. Thereafter, annealing was performed at 750 ° C. for 30 seconds in an ammonia-containing atmosphere, so that the amount of nitrogen in the steel sheet was 0.025%. Next, after applying an annealing separator containing MgO as a main component, a final annealing was performed at 1200 ° C. for 20 hours for secondary recrystallization. Table 3 shows the characteristic values of the secondary recrystallized steel sheet. The comparative material is a grain-oriented electrical steel sheet that is currently shipped to the market, but the superior characteristics of the steel sheet according to the method of the present invention can be understood by comparing with this.

<Example 2>
The effect of the present invention was studied when a sulfide or nitride dissolved by high-temperature slab heating was finely precipitated in a subsequent process and produced by a method according to a grain-oriented electrical steel sheet used as an inhibitor during secondary recrystallization. The steel B slab whose composition is shown in Table 1 was heated to 1330 ° C., and then hot-rolled with a thickness of 2.0 mm by hot rolling shown in Table 4.

Next, after making the plate thickness 0.30 mm by cold rolling, primary recrystallization annealing was performed in a decarburizing atmosphere at 890 ° C. for 30 seconds to obtain a primary recrystallized steel sheet having a C content of 0.001%. evaluated. Next, an annealing separator containing MgO: 95% and TiO ₂ : 5% was applied as a water slurry to the steel sheet, and subjected to secondary recrystallization annealing at 1150 ° C. for 3 hours. A coating solution containing phosphate-chromate-colloidal silica at a mass ratio of 3: 1: 3 was applied to the surface of the finish-annealed plate obtained as described above, and baked at 800 ° C. The obtained results are also shown in Table 5. The comparative material is a grain-oriented electrical steel sheet that is currently shipped to the market, but the superior characteristics of the steel sheet according to the method of the present invention can be understood by comparing with this.

<Example 3>
Examining the effect of the present invention when a secondary recrystallization inhibitor is not used in accordance with conventional grain-oriented electrical steel sheets but is produced by secondary recrystallization (abnormal grain growth) at a relatively low temperature in a short time. did. In this method, in particular, since the process was simplified, the decarburization annealing was performed. Steel CJ shown in Table 1 was made into a slab by continuous casting, and subjected to hot rolling, cold rolling, primary recrystallization annealing, and secondary recrystallization annealing (abnormal grain growth annealing) under the conditions shown in Table 6. Table 7 shows the characteristics at the time of the primary recrystallized steel sheet and the characteristic values of the secondary recrystallized (abnormal grain growth) steel sheet. By comparing among the same components, the excellent characteristics of the steel sheet according to the method of the present invention can be understood.

Claims (22)

In mass%, C: 0.040% or less, Si: 0.05 to 6.5%, Mn: 3.0% or less, Al: 3.5% or less, S: 0.055% or less, P: 0 .25% or less, N: 0.040% or less, molten steel consisting of the balance Fe and unavoidable impurities is solidified into a steel piece having a thickness of 50 mm or more by casting, and then 500 ° C. or more and F ° C. or less in the hot rolling process In the rolling in the temperature range, the cumulative strain (logarithmic strain) H due to the reduction and each pass outlet temperature T (° C.), and in the rolling pass excluding the final pass, The relationship between the time t (second) until the start of the rolling pass or the time t (second) until the start of water cooling after the final pass rolling in the case of the final pass is expressed by the following formula 2
T <F−H × 10−t × 10 Equation 2
In the rolling in the temperature range, at least one of the rolling passes, the shear strain or shear strain / ((thickness direction compressive strain)) in the steel sheet surface layer during rolling is 0.2 or more. In addition, the non-recrystallized structure remains in the 1/4 layer of the surface layer at the time of hot rolling, and after pickling , the product is cooled by performing cold rolling with a reduction rate of 50% or more with the non-recrystallized structure remaining. at the site of the surface layer 1/4 or above the surface layer side of the rolled sheet {411} <148> integration intensity / {411} orientation <011> integrated intensity ≧ 4.0 and {411} orientation <148> orientation integration of A method for producing a grain-oriented electrical steel sheet characterized by satisfying strength ≧ 4.0 and secondary recrystallization of the cold-rolled steel sheet. In mass%, C: 0.040% or less, Si: 0.05 to 6.5%, Mn: 3.0% or less, Al: 3.5% or less, S: 0.055% or less, P: 0 .25% or less, N: 0.040% or less, molten steel consisting of the balance Fe and unavoidable impurities is solidified into a steel piece having a thickness of 50 mm or more by casting, and then 500 ° C. or more and F ° C. or less in the hot rolling process In the rolling in the above temperature range, the cumulative strain (logarithmic strain) H due to the reduction and each pass outlet temperature T (° C.), and in the rolling pass excluding the final pass, The relationship between the time t (second) until the start of the rolling pass or the time t (second) until the start of water cooling after the final pass rolling in the case of the final pass is expressed by the following formula 2
T <F−H × 10−t × 10 Equation 2
In the rolling in the temperature range, at least one of the rolling passes, the shear strain or shear strain / ((thickness direction compressive strain)) in the steel sheet surface layer during rolling is 0.2 or more. , non-recrystallized structure in a surface layer 1/4 region in hot-rolled sheet time is remaining, further pickling, by performing the non-recrystallized structure is cold-rolling remains reduction of 50% or more remaining, cold rolled as the maximum value for the orientation distribution of the <411> // the plate surface of the integrated intensity of the ND orientation steel surface layer 1/4 or than at the site of the surface layer side of the plate are present at least four, the cold-rolled steel sheet two A method for producing a grain-oriented electrical steel sheet, characterized by performing next recrystallization. 3. The method for producing a grain- oriented electrical steel sheet according to claim 1 , wherein the shear strain or shear strain / (sheet thickness direction compressive strain) in the steel sheet surface layer is 0 in rolling in a temperature range of F ° C. or less in hot rolling. For a rolling pass that is 2 or more, by making the region where the shear strain or shear strain / (plate thickness direction compressive strain) is 0.2 or more reaches 10% or more of the total plate thickness in the plate thickness at the time of rolling. the method of the grain-oriented electrical steel sheet, wherein to Rukoto to satisfy integrated intensity ≦ 2.0 {111} <211> orientation at the site of the surface layer 1/4 or above the surface layer side of the cold-rolled plate. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 3, the integrated strength of {411} <148> orientation at the surface layer 1/4 position of the cold-rolled sheet or the surface layer side thereof. Is a method for producing a grain-oriented electrical steel sheet, characterized in that is at least twice the integrated strength at the thickness center of the steel sheet. The method for producing a grain- oriented electrical steel sheet according to any one of claims 1 to 4, wherein the cold-rolled sheet satisfies (B0 + B90) /2-B45≤0.040. Method.
Here, for each variable, the magnetic flux densities / T in the 0 °, 45 °, and 90 ° directions from the rolling direction when the induced current density is 5000 A / m are B 0, B 45, and B 90, respectively. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 5 , the steel component is in mass%, and further contains Cu + Nb + Cr + B + Ni + Co + Mo + Ti: 0.2 to 8.0%. Method for producing an electrical steel sheet. The method for manufacturing a grain- oriented electrical steel sheet according to any one of claims 1 to 6, wherein the steel component is in mass%, Cu: 0.2 to 8.0%, and Nb: 0.1 to 4. 0%, Cr: 1.0 to 15.0%, B: 0.0020 to 0.0150%, Ni: 0.2 to 8.0%, Co: 0.2 to 8.0%, Mo: 0 The manufacturing method of the grain-oriented electrical steel sheet characterized by containing any 1 or more types of 0.2-8.0%, Ti: 0.2-2.0%. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 7 , the steel component is mass%, and one or more of W, Sn, Sb, Mg, Ca, Ce, and REM are used. The manufacturing method of the grain-oriented electrical steel sheet characterized by containing 0.5% or less in total. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 8, it was manufactured in the same process except that the steel components were the same and all rolling passes of hot rolling were performed at F ° C or higher. Directional electromagnetic wave characterized in that the integrated strength of {411} <148> orientation at the surface layer 1/4 position of the cold-rolled sheet or the surface layer side of the cold-rolled sheet is more than twice in comparison with the steel sheet. A method of manufacturing a steel sheet.
Here, F is represented by the following formula 1 depending on the components of the steel plate.
F = 820 + (10 × Si + 50 × Cu + 50 × Nb + 10 × Cr + 5000 × B + 10 × Ni + 20 × Co + 40 × Mo + 20 × Ti) Formula 1 In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 9, it was manufactured in the same process except that the steel components were the same and all rolling passes of hot rolling were performed at F ° C or higher. A method for producing a grain-oriented electrical steel sheet, wherein the cold-rolled sheet satisfies B45−B′45 ≧ 0.030 in comparison with the steel sheet.
Here, for each variable, the magnetic flux density / T in the 45 ° direction from the rolling direction when the induced current density is 5000 A / m is B45. B shows the characteristics of the invention steel and B ′ shows the characteristics of the comparative steel. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 10, when the surface layer 1/4 of the cold-rolled sheet is removed and measurement is performed with a sheet thickness center layer 1/2 thickness, B45 is 0.02T or more. A method for producing a grain-oriented electrical steel sheet, characterized in that it decreases. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 11, a recrystallization rate of a surface quarter region is 90% or less at the time of hot rolling immediately before cold rolling. A method for producing a grain-oriented electrical steel sheet. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 12 , in rolling in a temperature range of F ° C or lower in hot rolling, shear strain or shear strain at a steel sheet surface layer / (sheet thickness direction) A method for producing a grain-oriented electrical steel sheet, characterized in that a rolling work roll has a diameter of 700 mm or less for a rolling pass having a compressive strain of 0.2 or more. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 13 , in rolling in a temperature range of F ° C or lower in hot rolling, shear strain or shear strain at a steel sheet surface layer / (sheet thickness direction) A method for producing a grain-oriented electrical steel sheet, wherein a friction coefficient is 0.10 or more for a rolling pass having a compressive strain (0.2) or more. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 14 , in rolling in a temperature range of F ° C or lower in hot rolling, shear strain or shear strain in a steel sheet surface layer / (sheet thickness direction) A rolling pass having a compressive strain of 0.2 or more has a shear strain rate of 10 / s or more at a portion where the shear strain or shear strain / (thickness direction compressive strain) is 0.2 or more. A method for producing a grain-oriented electrical steel sheet. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 15 , in rolling in a temperature range of F ° C or less in hot rolling, shear strain or shear strain in a steel sheet surface layer / (sheet thickness direction) A method for producing a grain-oriented electrical steel sheet, characterized in that a time between rolling passes is 4.0 seconds or less when a rolling pass having a compressive strain of 0.2 or more is continuously performed a plurality of times. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 16 , in rolling in a temperature range of F ° C or lower in hot rolling, shear strain or shear strain at a steel sheet surface layer / (sheet thickness direction) A method for producing a grain-oriented electrical steel sheet, wherein a rolling pass having a compressive strain of 0.2 or more is performed a plurality of times, and a cumulative total of shear strain on the steel sheet surface layer is 0.6 or more. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 17 , in rolling in a temperature range exceeding F ° C in hot rolling, a rolling strain is 2.0 or less, or one rolling pass. A method for producing a grain-oriented electrical steel sheet, characterized in that the rolling strain is about 0.6 or less, or the time between each rolling pass is 4.0 seconds or more when performing a plurality of continuous passes. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 18 , the time until the start of water cooling after the final pass of hot rolling is 2 seconds or less. Production method. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 19 , the cooling rate at the time of water cooling after the final pass of hot rolling is set to 10 ° C / s or more and cooled to 700 ° C or less. A method for producing a grain-oriented electrical steel sheet. In the manufacturing method of the grain- oriented electrical steel sheet according to any one of claims 1 to 20 , after water cooling after the final pass of hot rolling , the steel sheet is cold-rolled without being heated to 500 ° C or more and annealed. A method for producing a grain-oriented electrical steel sheet. The method of manufacturing a grain-oriented electrical steel sheet according to any one of claims 1 to 21, the final annealing after 0.5% or more, the production of grain-oriented electrical steel sheet, which comprises applying a strain of 50% or less Method.