The present invention relates to a grain-oriented electrical steel sheet and a method for manufacturing the same. Specifically, the present invention relates to a grain-oriented electrical steel sheet having a tension-applying film containing no chromium and having strain-introduced magnetic domain control, and a method for manufacturing the same.
This application claims priority based on Japanese Patent Application No. 2018-248167 filed in Japan on December 28, 2018, and the contents thereof are incorporated herein by reference.
Background technology
[0002]
Electrical steel sheets are used as the core material of transformers. In a general directional electromagnetic steel sheet, the mother steel sheet contains Si, the crystal grains in the mother steel sheet have {110} planes aligned parallel to the steel plate surface, and the <100> axes are aligned in the rolling direction (goth). It is integrated in the orientation), and the easy-to-magnetize axes are aligned in the longitudinal direction.
[0003]
A general grain-oriented electrical steel sheet has a structure in which multiple magnetic domains (striped magnetic domains) whose magnetization is oriented in the rolling direction are arranged with a magnetic domain wall in between. These domain walls are 180 ° domain walls and are easily magnetized in the rolling direction. Therefore, a general grain-oriented electrical steel sheet has a high magnetic flux density and a low iron loss at a relatively small constant magnetization force.
[0004]
W17 / 50 [W / kg] is generally used as an index of iron loss. W17 / 50 is a value of iron loss generated in the grain-oriented electrical steel sheet when AC-excited so that the maximum magnetic flux density becomes 1.7 T at a frequency of 50 Hz. By reducing the W17 / 50, a more efficient transformer can be manufactured.
[0005]
The outline of the general manufacturing method of grain-oriented electrical steel sheets is explained below. A silicon steel sheet (hot-rolled steel sheet) containing a predetermined amount of Si that has been hot-rolled is annealed by hot-rolled sheet and cold-rolled to obtain a cold-rolled steel sheet having a desired plate thickness. Next, the cold-rolled steel sheet is annealed in a continuous annealing furnace, and decarburization and primary recrystallization (crystal grain size: 7 to 30 μm) are performed (decarburization annealing) to obtain a decarburized annealed steel sheet. Subsequently, an annealing separator containing MgO as a main component is applied to the surface of a decarburized annealed steel sheet (hereinafter, may be simply referred to as a steel sheet), and the steel sheet is wound into a coil shape (outer shape is cylindrical) for finishing. Anneal.
[0006]
In this finish annealing, so-called goth grains whose rolling direction and easy magnetization axis coincide with each other due to the secondary recrystallization phenomenon preferentially grow. As a result, by performing finish annealing, a grain-oriented electrical steel sheet having high crystal orientation (crystal orientation) can be obtained. In order to enhance the accumulation of Goth orientation, a secondary recrystallization process using AlN, MnS or the like as an inhibitor is widely used.
[0007]
In the finish annealing step, the annealing separator applied to the surface of the steel sheet (decarburized annealed steel sheet) and the surface oxide film formed by decarburization annealing are fired to form a primary film (forsterite film). After the finish annealing, the coil is unwound, and the steel sheet is continuously passed through another annealing furnace to perform flattening annealing, and the shape of the steel sheet generated by the finish annealing is corrected and unnecessary strain in the steel sheet is removed. .. Further, by applying a coating liquid to the surface of the steel sheet and baking it, a tension-imparting film that imparts tension and electrical insulation is formed, and a grain-oriented electrical steel sheet is obtained.
[0008]
Forming a film on the surface of a steel sheet is one of the approaches for reducing iron loss. The primary coating is formed on the surface of the steel sheet in order to apply tension to the steel sheet and reduce iron loss as a single steel sheet. In addition, the tension-applying film is provided on the outer layer side of the primary film to apply tension to the steel sheet to reduce iron loss as a single steel sheet, and also to provide electrical insulation between the steel sheets when the steel sheets are laminated and used. It is also formed for the purpose of reducing the iron loss as an iron core by ensuring the properties.
[0009]
Generally, the primary coating is mainly forsterite (Mg 2SiO 4). In this primary coating, in the finish annealing that causes secondary recrystallization in the steel sheet, the annealing separator containing magnesia (MgO) as the main component and the surface oxide film (main component SiO 2) on the mother steel sheet are 1000 to 1200. It reacts and is formed in the process of being heat-treated at ° C for 5 to 50 hours. Also, in general, the tensioning coating contains chromium. This tension-applied film is obtained by applying a coating solution containing, for example, phosphoric acid or phosphate, colloidal silica, and chromic anhydride or chromate to a steel sheet after finish annealing, and baking at 700 to 1000 ° C. for 5 to 120 seconds. , Formed dry.
[0010]
Regarding the primary coating, there is a technology to improve the coating properties such as peeling resistance and insulating properties of the primary coating by adding Ti compounds such as Ti oxide and / or Ti hydroxide to the annealing separator containing MgO. Are known.
[0011]
The technique described in Patent Document 1 is used in the production of directional electromagnetic steel sheets using a material that does not contain an inhibitor-forming component after undergoing decarburization annealing and finish (purification) annealing, and contains MgO and Ti oxides. When finish annealing is performed using an annealing separator to which a Ti compound such as Ti hydroxide is added, good magnetic properties cannot be obtained, especially in view of the problem that the magnetic properties after winding are significantly deteriorated. Annealing.
[0012]
In Patent Document 1, the component composition of the base iron from which the forsterite film is removed is C: 0.0050 mass% or less, Si: 2.0 to 8.0 mass%, and Mn: 0.005 to 1.0 mass%. The amount of Ti (mass%) and the amount of N (mass%) contained in the ground iron from which the forsterite film has been removed are Ti (a) and N (a), respectively. When the amount of Ti (mass%) and the amount of N (mass%) contained in the steel plate having the forsterite film are Ti (b) and N (b), respectively, N (b) ≤ 0.0050 mass%. Moreover, the directional electromagnetic steel plate characterized by N (b) / N (a) ≧ 4 and Ti (b) / Ti (a) ≧ 4 is described.
[0013]
Further, in Patent Document 1, as the annealing separator for forming the forsterite film, 0.5 to 10 parts by mass of a Ti compound is added to 100 parts by mass of MgO: in terms of TIO 2. Is described.
[0014]
As the tension applying film, the above-mentioned tension applying film containing chromium has been generally used, but in response to the growing interest in environmental protection in recent years, a tension applying film containing no chromium has been desired. There is.
[0015]
Patent Document 2 describes that a coating liquid composed of colloidal silica, aluminum phosphate, boric acid and sulfate is used to form an insulating film (tensioning film) containing no chromium.
[0016]
Patent Document 3 proposes a grain-oriented electrical steel sheet that achieves the same high level of moisture absorption resistance and low iron loss as when a chromium-containing coating is applied even when a chromium-free coating is applied as the tension coating. The purpose is to do.
[0017]
Patent Document 3 describes a directional electromagnetic steel plate provided with a forsterite-based base film and a chromium-free phosphate-based tension-applying film on the surface of the steel sheet, and the tension-applied film is Mn after finish baking. A forsterite-based undercoat containing 0.02 g / m 2 or more and 0.20 g / m 2 or less in terms of the amount of grain and 0.01 g / m 2 or more and 0.10 g / m 2 or less in terms of the amount of S. A directional electromagnetic steel plate characterized by being obtained by applying a phosphoric acid-based coating treatment liquid containing no chromium to the surface and baking it is described.
[0018]
In Patent Document 3, in order to form a forsterite-based base film containing Mn and S in terms of the amount of grain, Mg, Ca, Sr, Ba, Na, K, as S-containing additives in the quenching separator, One or more selected from sulfates or sulfides of Mn, Fe, Cu, Sn, Sb and Ni may be contained in a total of 1.5% or more and 20% or less in terms of SO3 amount. Have been described.
[0019]
In addition, as a method for forming a tension-imparting film containing no chromium, Patent Document 4 describes a method of adding an oxide colloid to a coating liquid containing a first phosphate and colloidal silica. Patent Document 5 describes a method of adding a boron compound to a coating liquid containing a first phosphate and colloidal silica. Patent Document 6 describes a method of adding a metal organic acid salt to a coating liquid containing a first phosphate and colloidal silica.
[0020]
Regarding the reduction of iron loss of grain-oriented electrical steel sheets, an approach different from the reduction of iron loss by coating is being considered.
The grain-oriented electrical steel sheet is subjected to strains that extend linearly or are intermittently aligned at regular intervals (constant intervals) in a direction perpendicular to or substantially perpendicular to the rolling direction (conveyance direction) to subdivide magnetic domains. Thereby, the iron loss can be further reduced. In this case, a reflux type magnetic domain whose magnetization is orthogonal to the rolling direction is formed by local strain, and the domain wall spacing (width of the striped magnetic domain) of a substantially rectangular striped magnetic domain is generated from the energy increment in the magnetic domain. It gets narrower. Of the components of iron loss (W17 / 50), eddy current loss has a positive correlation with the 180 ° domain wall spacing. Therefore, based on this principle, so-called strain-introduced magnetic domain control is applied to grain-oriented electrical steel sheets. The iron loss can be reduced.
[0021]
As a method for controlling a strain-introduced magnetic domain, for example, a method using laser irradiation is described in Patent Document 7, a method using electron beam heating is described in Patent Document 8, and a method using ballpoint pen marking is not used. It is described in Patent Document 1.
Prior art literature
Patent documents
[0022]
Patent Document 1: Japanese Patent No. 6354957
Patent Document 2: Japanese Patent Publication No. 57-9631
Patent Document 3: Japanese Patent No. 6031951
Patent Document 4: Japanese Patent Application Laid-Open No. 2000-169972
Patent Document 5: Japanese Patent Application Laid-Open No. 2000-169973
Patent Document 6: Japanese Patent Application Laid-Open No. 2000-178760
Patent Document 7: Japanese Patent Publication No. 58-26406
Patent Document 8: Japanese Patent No. 3023242
Non-patent literature
[0023]
Non-Patent Document 1: K.K. Kuroki et. al. J. Apple. Phys52 (3), (1981) 2422-2424i
Outline of the invention
Problems to be solved by the invention
[0024]
The present inventors have attempted to apply strain-introducing magnetic domain control to a grain-oriented electrical steel sheet having a primary film mainly composed of forsterite and a tension-applying film containing no chromium on the surface of the mother steel sheet.
[0025]
However, through this attempt, the present inventors, when applying strain-introducing magnetic domain control to a grain-oriented electrical steel sheet having a tension-applying film containing no chromium, strains the grain-oriented electrical steel sheet having a tension-applying film containing chromium. We have newly discovered the problem that the effect of reducing iron loss is insufficient compared to the case of applying the introduction type magnetic domain control.
[0026]
The present invention manufactures a grain-oriented electrical steel sheet having a tension-applying film containing no chromium and effectively reducing iron loss by applying strain-introducing magnetic domain control, and the grain-oriented electrical steel sheet. It is intended to provide a suitable method for doing so.
Means to solve problems
[0027]
The gist of the present invention is as follows.
[1] The directional electromagnetic steel sheet according to one aspect of the present invention includes a mother steel sheet, a forsterite-based primary film arranged on the surface of the mother steel sheet, and chromium arranged on the surface of the primary film. A directional electromagnetic steel sheet comprising a phosphate-based tensioning film that does not contain
When the Ti content and S content in mass% in the forsterite-based primary coating are expressed as XTi and XS, respectively.
XTi / XS, which is the ratio of the Ti content to the S content, satisfies the following formula (1).
XTi + XS, which is the sum of the Ti content and the S content, satisfies the following formula (2).
It is characterized by being subjected to strain-introduced magnetic domain control.
Equation (1) 0.10 ≤ XTi / XS ≤ 10.00
Equation (2) XTi + XS ≧ 0.10 mass%
[2] The method for manufacturing grain-oriented electrical steel sheets according to another aspect of the present invention is the method for manufacturing grain-oriented electrical steel sheets according to the above [1].
After heating the slab, the slab is hot-rolled to obtain a hot-rolled steel sheet, and a hot-rolling process.
The hot-rolled sheet annealing process to obtain an annealed steel sheet by subjecting the hot-rolled steel sheet to annealing.
Cold pressure on the annealed steel sheet A cold rolling process to obtain a cold-rolled steel sheet by rolling,
The decarburization annealing step of obtaining a decarburized annealed steel sheet by subjecting the cold-rolled steel sheet to decarburization annealing,
A finish annealing step of applying a annealing separator to the surface of the decarburized annealed steel sheet and heating it to form a forsterite-based primary film to obtain a finish annealed steel sheet.
A tension-imparting film forming step of forming a chromium-free phosphate-based tension-applying film by applying a coating liquid to the surface of the finished annealed steel sheet and baking it.
A magnetic domain control process in which strain-introduced magnetic domain control is applied to a steel sheet on which a phosphate-based tension-applying film that does not contain chromium is formed.
Equipped with
The annealing separator is mainly MgO, and the Ti-containing compound is 1.0 part by mass or more and 15.0 parts by mass or less in terms of TIO 2 with respect to 100 parts by mass of MgO in the annealing separator, and the S-containing compound is CaS. Including 0.20 parts by mass or more and 10.0 parts by mass or less in terms of conversion
The coating liquid contains a mixture containing two or more of the group consisting of aluminum phosphate, magnesium phosphate, nickel phosphate, cobalt phosphate and barium phosphate, with respect to 100 parts by mass of the mixture in terms of solid content. , 40 to 70 parts by mass of colloidal silica, optionally 2 to 50 parts by mass of phosphoric acid, and no chromium.
The invention's effect
[0028]
According to the above aspect of the present invention, a grain-free phosphate-based tension-applying film is provided, and a strain-introduced magnetic domain control is applied to effectively reduce iron loss. A suitable method for manufacturing a steel sheet and the grain-oriented electrical steel sheet can be provided. According to the above aspect of the present invention, even if the object to which the strain-introduced magnetic domain control is applied is a grain-oriented electrical steel sheet having a phosphate-based tension-applying film containing no chromium, the iron loss of the grain-oriented electrical steel sheet is caused. It can be effectively reduced. Therefore, not only is it chrome-free and has an excellent environmental protection effect, but also iron loss reduction due to the coating structure including the forsterite-based primary coating and the chromium-free phosphate-based tension-applying coating, and the strain-introduced magnetic domain. Due to the synergistic effect with the iron loss reduction by control, a grain-oriented electrical steel sheet having an excellent iron loss reduction effect can be obtained.
A brief description of the drawing
[0029]
FIG. 1 is a diagram schematically showing a coating structure of a grain-oriented electrical steel sheet according to the present embodiment.
FIG. 2 is an example of strain-introduced magnetic domain control, in which linear strains extending in a direction perpendicular to or substantially perpendicular to the rolling direction are repeatedly arranged in the rolling direction at regular intervals on a directional electromagnetic steel plate. It is a figure which shows the structure schematically.
FIG. 3 is another example of strain-introduced magnetic domain control, in which a group of point-like strains aligned in a direction perpendicular to or substantially perpendicular to the rolling direction are formed on a directional electromagnetic steel plate at regular intervals in the rolling direction. It is a figure which shows typically the structure which was repeatedly arranged.
Embodiment for carrying out the invention
[0030]
Although the present inventors apply strain-introduced magnetic domain control to grain-oriented electrical steel sheets having a chromium-free phosphate-based tension-applying film, the forsterite-based primary film has a desired amount of Ti and It has been found that when S is contained, the effect of reducing iron loss is improved.
[0031]
Even when strain-introduced magnetic domain control is applied to grain-oriented electrical steel sheets having a chromium-free phosphate-based tension-applying film, the content of Ti and S contained in the forsterite-based primary film is appropriate. The reason why the effect of reducing iron loss is improved by adjusting to is presumed as follows.
When strain-introducing magnetic domain control is applied to a directional electromagnetic steel sheet having a phosphate-based tension-applying film containing chromium, the chromium in the tension-applying film is exposed to laser irradiation or electron beam heating in the steel sheet. It is considered that the action of retaining the strain can be effectively exhibited. On the other hand, when strain-introduced magnetic domain control is applied to a directional electromagnetic steel sheet having a chromium-free phosphate-based tension-applying film, laser irradiation or electron beam heating causes strain to remain in the steel sheet. It is considered that the action is not fully expressed.
[0032]
On the other hand, when a chromium-free phosphate-based tension-imparting film is provided on the mother steel sheet, an appropriate amount of Ti and S is contained in the forsterite-based primary film under the tension-applying film. Therefore, it is considered that Ti and S can effectively exhibit the action of residual strain in the steel sheet by laser irradiation, electron beam heating, or the like.
[0033]
The directional electromagnetic steel sheet according to the present embodiment includes a mother steel sheet, a forsterite-based primary film arranged on the surface of the mother steel sheet, and a chromium-free phosphate arranged on the surface of the primary film. A directional electromagnetic steel sheet comprising a system tensioning coating, wherein the Ti content and the S content in% by mass in the forsterite-based primary coating are expressed as XTi and XS, respectively. XTi / XS, which is the ratio of the amount to the S content, satisfies the following formula (1), and XTi + XS, which is the sum of the Ti content and the S content, satisfies the following formula (2). It is characterized by being controlled.
Equation (1) 0.10 ≤ XTi / XS ≤ 10.00
Equation (2) XTi + XS ≧ 0.10 mass%
[0034]
Further, the directional electromagnetic steel sheet according to the present embodiment has a hot rolling step of obtaining a hot-rolled steel sheet by heating the slab and then hot-rolling the slab, and hot-rolling sheet annealing on the hot-rolled steel sheet. A hot-rolled plate bleeding step to obtain an annealed steel sheet, a cold-rolling step to obtain a cold-rolled steel sheet by cold-rolling the annealed steel sheet, and decarburization and annealing to the cold-rolled steel sheet. A forsterite-based primary film is formed and a finished annealed steel sheet is obtained by applying a decarburization separating agent to the surface of the decarburized and annealed steel sheet and heating to obtain a decarburized and annealed steel sheet. A finish annealing step, a tension applying film forming step of forming a chromium-free phosphate-based tension applying film by applying a coating liquid to the surface of the finish annealed steel sheet and baking, and the chromium-free step. A steel plate having a phosphate-based tension-imparting film formed thereof is provided with a magnetic zone control step for performing strain-introducing magnetic zone control. , Ti-containing compound is contained in 1.0 part by mass or more and 15.0 parts by mass or less in terms of TiO 2, and S-containing compound is contained in 0.20 part by mass or more and 10.0 parts by mass or less in terms of CaS. It contains a mixture containing two or more of the group consisting of aluminum, magnesium phosphate, nickel phosphate, cobalt phosphate and barium phosphate, and contains 40 to 40 parts of colloidal silica with respect to 100 parts by mass of the mixture in terms of solid content. It can be produced by a production method characterized by containing 70 parts by mass, optionally containing 2 to 50 parts by mass of phosphor, and not containing chromium.
[0035]
Hereinafter, the grain-oriented electrical steel sheet (hereinafter, may be abbreviated as “oriented electrical steel sheet”) and the manufacturing method thereof according to the present embodiment will be described.
In the following explanation, when the numerical range is expressed as "lower limit value to upper limit value", it means "greater than or equal to the lower limit value and less than or equal to the upper limit value" unless otherwise specified.
[0036]
FIG. 1 is a diagram schematically showing a coating structure of a grain-oriented electrical steel sheet according to this embodiment. As shown in FIG. 1, in the grain-oriented electrical steel sheet according to the present embodiment, a forsterite-based primary film 2 and a chromium-free phosphate-based tension-applying film 3 are formed on the surface of the grain steel sheet 1. It has a layered structure laminated in this order. Further, although not shown in FIG. 1, the grain-oriented electrical steel sheet according to the present embodiment is subjected to strain-introduced magnetic domain control. Hereinafter, the layer structure of the grain-oriented electrical steel sheet according to the present embodiment will be described in detail. In the following description, the reference numerals in the drawings are omitted except when the drawings are referred to.
[0037]
[Mother steel plate]
The chemical composition and metallographic structure of the grain steel sheet are not particularly limited as long as the easy-to-magnetize axes are aligned in a certain direction and function as a grain-oriented electrical steel sheet.
[0038]
The chemical composition of the mother steel sheet is not particularly limited, but for example, by mass%,
Si: 0.8% -7.0%,
C: Over 0%, 0.085% or less,
Acid-soluble Al: 0% to 0.065%,
N: 0% to 0.012%,
Mn: 0% to 1%,
Cr: 0% to 0.3%,
Cu: 0% -0.4%,
P: 0% -0.5%,
Sn: 0% to 0.3%,
Sb: 0% to 0.3%,
Ni: 0% to 1%,
S: 0% to 0.03%,
Se: 0% to 0.015%
It is preferable that the balance is composed of Fe and impurities.
The chemical composition of the mother steel sheet is preferable for controlling the crystal orientation to a Goss texture integrated in the {110} <001> orientation.
The above chemical composition is a chemical composition measured at a depth at which the chemical composition of the mother steel sheet is stable.
[0039]
Of the elements in the mother steel sheet, Si and C are essential elements. Acid-soluble Al is a preferable element to be contained in order to obtain a high-efficiency GO material (oriented electrical steel sheet having excellent magnetic properties). N, Mn, Cr, Cu, P, Sn, Sb, Ni, S and Se are selective elements. Since these selective elements may be contained according to the purpose, it is not necessary to limit the lower limit value, and the lower limit value may be 0%. Further, even if these selective elements are contained as impurities, the effect obtained by the grain-oriented electrical steel sheet according to the present embodiment is not impaired. The chemical composition of the base steel sheet consists of essential elements and selective elements, as well as the balance Fe and impurities.
[0040]
In the present embodiment, the "impurity" means an element that is inevitably mixed from ore, scrap, or the manufacturing environment as a raw material when the base steel sheet is industrially manufactured.
[0041]
In addition, grain-oriented electrical steel sheets generally undergo purification annealing (finish annealing) during secondary recrystallization. In purification annealing, inhibitor-forming elements are discharged out of the system. In particular, the contents of N and S are significantly reduced, and the N content and S content after finish annealing are 50 ppm or less. Under normal finish annealing conditions, the N content and S content after finish annealing are 20 ppm or less, and further 10 ppm or less.
[0042]
The chemical composition of the mother steel sheet may be measured by a general analysis method for steel. For example, the chemical composition of the mother steel sheet may be measured using ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrum). Specifically, for example, a 35 mm square test piece is obtained from the position of the center of the plate thickness of the mother steel plate after the coating (primary coating and tension applying coating) is removed, and the ICPS-8100 manufactured by Shimadzu Corporation (measuring device) is used. It can be specified by measuring under the conditions based on the calibration curve prepared in advance. In addition, C and S may be measured by using the combustion-infrared absorption method, and N may be measured by using the inert gas melting-thermal conductivity method. The acid-soluble Al may be measured using a filtrate obtained by thermally decomposing the sample with an acid.
The test piece was immersed in an aqueous NaOH solution, the aqueous NaOH solution was heated to 80 ° C. to remove the tension-imparting film, and then the test piece was immersed in 10% dilute sulfuric acid at 80 ° C. for 3 minutes to dissolve the primary film. , The film may be removed.
[0043]
[Manufacturing method of mother steel sheet (decarburized annealed steel sheet)]
The method for manufacturing the grain steel sheet is not particularly limited, and a conventionally known method for manufacturing grain-oriented electrical steel sheet can be appropriately selected and manufactured. Preferred specific examples include, for example, (1) a hot-rolling step of heating a slab having the above-mentioned chemical composition to 1000 ° C. or higher and hot-rolling to obtain a hot-rolled steel sheet, and (2) a hot-rolled steel sheet. The hot-rolled sheet is annealed to obtain an annealed steel sheet by hot-rolling the sheet by heating to 1000 to 1200 ° C., and (3) the annealed steel sheet is cold-rolled once or twice or more with intermediate annealing sandwiched between them. The cold-rolled steel sheet is obtained by cold-rolling to obtain a cold-rolled steel sheet, and (4) the cold-rolled steel sheet is decarburized and annealed by heating to 700 to 900 ° C. in a wet hydrogen-inert gas atmosphere. Examples thereof include a manufacturing method comprising a decarburization and rolling step to obtain.
If necessary, a step of nitriding annealing may be provided during the decarburization annealing step or after the decarburization annealing step. The conditions for nitriding annealing may be general conditions. For example, it has nitriding ability such as ammonia.

The scope of the claims
[Claim 1]
Mother steel plate and
Forsterite-based primary coating placed on the surface of the mother steel plate,
A grain-oriented electrical steel sheet provided with a chromium-free phosphate-based tension-applying film arranged on the surface of the primary film.
When the Ti content and S content in mass% in the forsterite-based primary coating are expressed as XTi and XS, respectively.
XTi / XS, which is the ratio of the Ti content to the S content, satisfies the following formula (1).
XTi + XS, which is the sum of the Ti content and the S content, satisfies the following formula (2).
A grain-oriented electrical steel sheet characterized by being subjected to strain-introduced magnetic domain control.
Equation (1) 0.10 ≤ XTi / XS ≤ 10.00
Equation (2) XTi + XS ≧ 0.10 mass%
[Claim 2]
The method for manufacturing grain-oriented electrical steel sheets according to claim 1.
After heating the slab, the slab is hot-rolled to obtain a hot-rolled steel sheet, and a hot-rolling process.
The hot-rolled sheet annealing process to obtain an annealed steel sheet by subjecting the hot-rolled steel sheet to annealing.
A cold rolling process to obtain a cold-rolled steel sheet by cold-rolling the annealed steel sheet,
The decarburization annealing step of obtaining a decarburized annealed steel sheet by subjecting the cold-rolled steel sheet to decarburization annealing,
A finish annealing step of applying a annealing separator to the surface of the decarburized annealed steel sheet and heating it to form a forsterite-based primary film to obtain a finish annealed steel sheet.
A tension-imparting film forming step of forming a chromium-free phosphate-based tension-applying film by applying a coating liquid to the surface of the finished annealed steel sheet and baking it.
A magnetic domain control process in which strain-introduced magnetic domain control is applied to a steel sheet on which a phosphate-based tension-applying film that does not contain chromium is formed.
Equipped with
The annealing separator is mainly MgO, and the Ti-containing compound is 1.0 part by mass or more and 15.0 parts by mass or less in terms of TIO 2 with respect to 100 parts by mass of MgO in the annealing separator, and the S-containing compound is CaS. Including 0.20 parts by mass or more and 10.0 parts by mass or less in terms of conversion
The coating liquid contains a mixture containing two or more of the group consisting of aluminum phosphate, magnesium phosphate, nickel phosphate, cobalt phosphate and barium phosphate, with respect to 100 parts by mass of the mixture in terms of solid content. , 40-70 parts by mass of colloidal silica, optionally 2-50 parts by mass of phosphoric acid, and no chromium
A method for manufacturing grain-oriented electrical steel sheets.