JP6519006B2 - Unidirectional electrical steel sheet, decarburizing plate for unidirectional electrical steel sheet, and method for producing them - Google Patents

Description

  The present invention improves the magnetic properties and glass film adhesion of a unidirectional electromagnetic steel sheet used as a soft magnetic material for an iron core of an electric device.

  A unidirectional steel sheet contains about 2 to 4% of Si, is a steel sheet in which the orientation of crystal grains is highly accumulated in the {110} <001> orientation by secondary recrystallization, and a glass film is formed on the surface, It is laminated to form an iron core, and is used as a member of a power transformer or a rotating machine. As the characteristics, it is required that the iron loss is low, the magnetic flux density is high, and the glass film adhesion is good. In particular, with regard to crystal orientation, by increasing the degree of integration of crystal orientation to the limit, the core loss linked to this is also reduced to the limit.

  The steel sheet is coated with a film (hereinafter referred to as a tension film) for improving the magnetic characteristics by applying tension to the steel plate and securing the core characteristics by insulation between laminated steel plates. Since it is difficult to ensure adhesion even when this tension film is directly applied to steel, a glass film having high adhesion to the tension film is interposed between the tension film and the steel sheet surface. If the adhesion of the glass coating to the base steel plate is poor, the tensile coating may drop off together with the glass coating during steel plate processing.

  Si is added to increase the resistivity of the material and lower the eddy current loss. However, excessive addition causes embrittlement of the steel sheet, which makes production difficult, and therefore, when it is manufactured through a cold rolling process, it is industrially limited to about 3.5% or so. For this reason, a report and a proposal of a steel plate having characteristics of high specific resistance by containing elements other than Si have been made. For example, Patent Documents 1 and 4 attempt to add 2 to 4% of Mn. However, in addition to the change of the inhibitor (mainly MnS) which plays an important role in the secondary recrystallization behavior, this technology contains a large amount of Mn, which is an austenite former element, and thus one of the structures during secondary recrystallization. The part is transformed to the γ phase, and significant deterioration of the degree of orientation integration becomes a problem.

  As a technique relating to improvement of glass film adhesion, Patent Document 2 discloses that a Si-concentrated layer formed by intermediate annealing and contributing to property deterioration is removed after intermediate annealing. However, this technique does not sufficiently improve the adhesion of the glass film.

  In addition, the deterioration of the surface properties of the steel sheet due to cracking during hot rolling due to FeS having a low melting point may cause the deterioration of the glass film adhesion of the final product. Patent document 3 suppresses the crack of the surface of a hot-rolled material by applying a Mo-containing solution to the surface of the steel before hot-rolling and preferentially precipitating the S compound of Mo on the surface of the steel during hot-rolling. It is intended to improve the glass film adhesion of products. However, since it changes the form of the sulfide which adjusts secondary recrystallization behavior as an inhibitor, it is a problem that magnetic defect tends to occur.

JP-A-5-51705 Japanese Patent Application No. 5-201707 JP-A-59-85820 JP-A-9-104923

  The present invention provides a unidirectional steel sheet having low iron loss, high magnetic flux density, and good glass film adhesion, a decarburized sheet for the unidirectional steel sheet as an intermediate product, and a method for producing the same. In steels of components whose specific resistance is increased sufficiently for low iron loss, good secondary recrystallization is generated without secondary transition due to γ transformation and expression of good secondary recrystallization assuming an α single phase state, and further better It is an object to control the element concentration and properties of the surface of the steel before forming the glass film so as to form a glass film.

  In order to satisfy the above-mentioned requirements, the present inventor first carried out a search for a material containing a relatively large amount of Mn, Al, Cu, Mo, Ni, etc. to enhance the specific resistance. These elements have a great effect on inhibitor control which can be said to be the key to secondary recrystallization control, but good secondary recrystallization may sometimes occur if the Mn content is about 1 to 3%. all right.

  As a result of further examination, since Mn also has the action of promoting oxidation, the oxide film produced by the heat treatment during production is remarkably different from the conventional material, and is unevenly formed on the surface of the intermediate product and remains. It was found that the adhesion of the glass coating was deteriorated. And by controlling the existence condition of Mn on the steel plate surface of an intermediate product and the element which affects the oxide film formation, it succeeded in forming a good glass film on the steel plate surface. One-way electrical steel sheets that finally show good glass film adhesion are characterized by the element distribution condition on the glass film surface or the element distribution condition on the decarburizing plate surface as a product, It turned out that it can be specified and the manufacturing method can be further provided. Specifically, it is as follows.

[1]
A unidirectional electromagnetic steel sheet having a glass coating formed on the surface of a base steel sheet,
The base steel sheet is, by mass%, Si: 3.0 to 4.0%, Mn: 1.0 to 3.0%, C: 0.0001 to 0.1%, S: 0.0001 to 0.01%, acid soluble Al: 0.003 to 0.030%, N: 0.0030 to 0.050 %, The balance being composed of Fe and unavoidable impurities, the SM value defined below is 7 or more and less than 50, has 3 or more peaks of Al detection intensity defined below, and is specified below A unidirectional electromagnetic steel sheet having two or more peaks of detected S intensity and having a maximum detected intensity of N measured by GDS of 0.05 or more and less than 0.1.
SM value:
The element strength distribution is measured by GDS from the surface to the inside of the glass film, and in the strength distribution of Si and Mn in the thickness direction, the highest strength of Si concentrated on the surface is Si (S), and the highest strength is Si Let the Mn intensity at the depth at which (S) is detected be Mn (S). Further, the strength in the region where the Si strength and the Mn strength are stable inside the base steel sheet is taken as Si (B) and Mn (B), respectively. From these values, the SM value is calculated by the following equation (1).
SM value = Si (S) / Si (B) * Mn (B) / Mn (S) formula (1)
Peak of Al detection intensity:
The element strength distribution is measured by GDS from the surface to the inside of the glass film, and the maximum value and the minimum value of the Al detection strength are determined in the strength distribution of Al in the plate thickness direction. Among the obtained maximum values, the maximum value of which the intensity difference with the minimum value adjacent to the surface side or the inner side is 10% or more of the minimum value is defined as the peak of the Al detection intensity.
Peak of S detected intensity:
Elemental intensity distribution is measured by GDS from the surface to the inside of the glass film, and the maximum value and the minimum value of the S detection intensity are determined in the intensity distribution of S in the plate thickness direction. Among the obtained local maximums, the local maximum at which the intensity difference between the local minimum adjacent to the surface side or the inner side is 10% or more of the local minimum is defined as the peak of the S detection intensity.
[2]
The base steel sheet further contains, in mass%, Cr: 0.3% or less, Cu: 0.4% or less, P: 0.5% or less, Sn: 0.3% or less, Ni: 1% or less, B, Bi , Te and Se: B + Bi + Se + S + Te total The one-way electrical steel sheet according to [1], which contains one or more elements of 0.015% or less.
[3]
It is a decarburized plate that is an intermediate product of unidirectional magnetic steel plates,
Si: 3.0 to 4.0%, Mn: 1.0 to 3.0%, C: 0.0001 to 0.1%, S: 0.0001 to 0.01%, acid soluble Al: 0.003 to 0.030%, N: 0.0030 to 0.050% in mass%, A decarburizing plate for a unidirectional electromagnetic steel sheet, characterized in that the balance is made of Fe and unavoidable impurities, and the SM value defined below is 4 or more and less than 30.
SM value:
The strength distribution of Si and Mn in the thickness direction is measured by GDS from the surface coated with the oxide film to the inside, and the highest strength of Si concentrated on the surface is Si (S), and the highest strength is Si (S (S) The Mn intensity at the depth at which) is detected is taken as Mn (S). Further, the strength in the region where the Si strength and the Mn strength are stable inside the base steel sheet is taken as Si (B) and Mn (B), respectively. From these values, the SM value is calculated by the following equation (1).
SM value = Si (S) / Si (B) * Mn (B) / Mn (S) formula (1)
[4]
Cr: 0.3% or less, Cu: 0.4% or less, P: 0.5% or less, Sn: 0.3% or less, Ni: 1% or less, B, Bi , Te, and Se: B + Bi + Se + S + Te in total of 0.015% or less The decarburizing plate for a unidirectional magnetic steel sheet according to [3], which contains one or more elements among them.
[5]
A method for producing the grain-oriented electrical steel sheet according to any one of [1] or [2] after hot rolling, cold rolling, decarburizing annealing, and finish annealing,
The maximum reaching temperature of the decarburization annealing is Y: 700 to 900 ° C., residence time at Y-30 ° C. or higher: 4 seconds or less, and thereafter residence at a temperature range of Y-30 ° C. or less, Y-85 ° C. or higher Time: 10 seconds or more, The manufacturing method of a unidirectional electromagnetic steel sheet characterized by the above-mentioned.
[6]
The oxide film on the surface of the steel sheet is removed by one or more steps of pickling, mechanical polishing or chemical polishing between the decarburizing annealing and before the finish annealing, as described in [5]. Manufacturing method of one-way electrical steel sheet.
[7]
A method for producing the grain-oriented electrical steel sheet according to any one of [1] or [2] after hot rolling, cold rolling, decarburizing annealing, and finish annealing,
One or two of B, Al, Te, Mn, Bi, Si, and Cu on the steel sheet surface as at least any one pretreatment of the hot rolling, the cold rolling, the decarburizing annealing, and the finish annealing. The manufacturing method of the unidirectional electromagnetic steel sheet characterized by apply | coating 0.002-0.120 g / m <2> of elements more than seed | species.
[8]
A method for producing a decarburized sheet according to any one of [3] or [4] through hot rolling, cold rolling, decarburizing annealing,
The maximum reaching temperature of the decarburization annealing is Y: 700 to 900 ° C., residence time at Y-30 ° C. or higher: 4 seconds or less, and thereafter residence at a temperature range of Y-30 ° C. or less, Y-85 ° C. or higher Time: 10 seconds or more, The manufacturing method of the decarburizing board for a unidirectional electromagnetic steel sheet characterized by the above-mentioned.
[9]
One or more elements of B, Al, Te, Mn, Bi, Si, and Cu on the steel sheet surface as at least any one pretreatment of the hot rolling, the cold rolling, and the decarburizing annealing. Is applied at 0.002 to 0.120 g / m 2, the method for producing a decarburized sheet for a unidirectional magnetic steel sheet according to [8], characterized in that

  According to the present invention, there is provided a unidirectional steel sheet product sheet having low core loss, high magnetic flux density and good glass film adhesion, a decarburized and annealed sheet for the unidirectional magnetic steel sheet as an intermediate product, and a method of manufacturing them. can get.

It is a figure which shows the result of GDS of a glass film.

  First, the reasons for limiting the content of each element of the steel sheet of the present invention will be described. These elements are elements that strongly influence the element distribution on the surface of the glass film, which is also a feature of the present invention, and the identification thereof is important. In addition,% means mass% about a component.

Si: 3.0 to 4.0%
In order to increase the specific resistance by increasing the amount of Si and improve the core loss characteristics, the amount is made 3.0% or more. However, in order to control the SM value, which is a feature of the present invention, by controlling the oxidation behavior in the coexistence of Mn, which is a boron oxide element, it is necessary to make it 4.0% or less.

Mn: 1.0 to 3.0%
Mn increases the resistivity and improves the core loss characteristics. If the content is 1.0% or less, the specific oxidation behavior of Mn does not pose a problem, and the problem to be solved by the present invention does not occur, so 1.0% or more is the subject of the present invention. If it exceeds 3.0%, not only does γ transformation occur during finish annealing to inhibit good secondary recrystallization, but it strongly influences the oxidation behavior and distribution of the steel sheet surface, and the shape of SM value, Al, S detection strength is preferable It becomes difficult to control and the glass film adhesion deteriorates.

C: 0.0001 to 0.1%
C needs to be 0.1% or less because it causes magnetic aging and degrades the magnetic properties. Although the effect of the present invention is not lost even if it is not present, the lower limit is made 0.0001% from the viewpoint of reduction cost.

S: 0.0001 to 0.01%
When the content of S exceeds 0.01%, it becomes difficult to make the shape of the S detection intensity which is also a feature of the present invention have two or more peaks, and good glass film adhesion can not be obtained. It is an element that does not have to be contained at all in terms of magnetic properties, but because it is an element that is contained as a trace amount as an impurity, it is difficult to completely eliminate it, and it is practically 0.0001% or more .

Acid soluble Al: 0.003 to 0.030%
Acid-soluble Al is an element that is contained as a trace amount as an impurity, but it is difficult to completely eliminate it. Practically, it is 0.003% or more. When the content is 0.030% or more, it becomes difficult to make the shape of the Al detection intensity which is a feature of the present invention have three or more peaks, and good glass film adhesion can not be obtained.

N: 0.0030 to 0.050%
Since N is an element which is contained as a trace amount as an impurity, it is difficult to make it completely zero. Practically, it is 0.0030% or more. When the content is 0.030% or more, it becomes difficult to make the shape of the Al detection intensity which is a feature of the present invention have three or more peaks, and good glass film adhesion can not be obtained.

  The balance consists of Fe and unavoidable impurities, but in the present invention, Cr, Cu, P, Sn, B, Bi, Ni, and Se may be added if necessary, in addition to the above elements. The content of Cr may be 0.3% or less, Cu may be 0.4% or less, P may be 0.5% or less, Sn may be 0.3% or less, Ni may be 1% or less, B, Bi and Se may be contained in a range of 0.015% or less in total of B + Bi + Se + S + Te.

  Cr improves the oxide film of decarburization annealing, is an element effective for glass film formation, and is added in 0.3% or less. If it exceeds 0.3%, the adhesion of the film is adversely affected.

  Cu is an element effective in increasing core resistance and reducing iron loss. When the amount of addition exceeds 0.4%, the iron loss reducing effect is saturated, and it causes the surface flaw which becomes "kappahage" at the time of hot rolling.

  P is a grain boundary segregating element, and if the addition amount exceeds 0.5%, a problem occurs in the rollability.

  Sn is a grain boundary segregation element. Depending on the conditions of the finish annealing, Al is oxidized by the moisture released from the annealing separator to change the inhibitor strength. Therefore, the magnetic characteristics may fluctuate due to the difference in the coil position. As one of measures against this, there is a method of preventing oxidation by addition of these grain boundary segregation elements, and therefore, Sn can be added in the range of 0.3% or less. On the other hand, if it exceeds 0.3%, it is difficult to be oxidized during decarburization annealing, the formation of a glass film becomes insufficient, and the decarburization annealing property is significantly inhibited.

  Ni is an element effective in increasing the specific resistance and reducing the core loss, and is an element effective in controlling the metal structure of the hot-rolled sheet to improve the magnetic properties. However, if the addition amount exceeds 1%, secondary recrystallization becomes unstable.

  B, Bi, Te and Se adversely affect the magnetic properties, so the sum of B + Bi + Se + S + Te is preferably 0.015% or less. If the addition amount exceeds 1%, the magnetic flux density of the product is lowered. Further, for the purpose of preventing the occurrence of cracking in hot rolling, it is desirable to add Mn / (S + Se + B + Bi + Te) ≧ 4 in relation to the total amount of S and Se.

  Next, the element distribution which is the feature of the present invention will be described. The unidirectional electrical steel sheet of the present invention has an SM value defined in the following of 7 or more and less than 50, has 3 or more peaks of Al detection intensity defined below, and an S detection intensity defined below In a grain-oriented electrical steel sheet containing Mn at a relatively high concentration by having a peak of at least 2 and the highest detection strength of N measured by GDS being 0.05 or more and less than 0.1, It is compatible with glass film adhesion. In addition, the grain-oriented electrical steel sheet of the present invention can be manufactured by finish annealing a decarburized sheet (intermediate product) having an SM value defined in the following of 4 or more and less than 30.

  First, as an analysis example regarding each definition of the present invention, an example of element distribution on the surface of a steel sheet in the process of manufacture in conventional steel and invention steel is shown in FIG. FIG. 1 shows the results of GDS analysis of the steel sheet surface of a grain-oriented electrical steel sheet before applying a tension film. The surface layer is analyzed including the glass coating formed on the surface of the base steel sheet. In FIG. 1, the upper diagram shows Mn: 1% (high manganese: present invention example), the lower diagram shows Mn: 0.1% (low manganese: comparative example), the left diagram shows the right diagram. It is what expanded the vertical axis (analysis strength). In the left figure, the strength of Si does not appear because it exceeds the range of the vertical axis. In addition, at the initial stage of measurement in GDS measurement, intensity fluctuations occur due to abnormal discharge where the discharge becomes unstable. For example, in the surface layer region (near sputtering time 0), a strong peak of Si appears temporarily, but there is no actual concentration change, and it is a constant value. Therefore, the intensity in the initial range of measurement is a peak unrelated to the present invention. In addition, in FIG. 1, although the result of GDS analysis of the steel plate surface of a grain-oriented electrical steel sheet was shown, the decarburizing board also shows the behavior similar to a grain-oriented electrical steel sheet.

  Si and Mn are elements which are relatively easily oxidized as an element contained in a considerable amount in a steel sheet. An annealing separator containing Mg is applied to the steel sheet to be finish-annealed, and the reaction between the separator and the steel sheet takes place during finish annealing to form a glass film, but in particular for Si, Mg and O in the separator It reacts with O in the atmosphere and contributes to the formation of forsterite. It is the point of the present invention to control the behavior of Si and Mn in this process, and the distribution is characteristic.

  In the decarburized plate before finish annealing and the glass coating after finish annealing, as shown in FIG. 1, a peak of Si detection strength is observed in the surface layer portion of the steel plate (near sputtering time 20 to 30). At the same time, at this peak position, in the conventional steel (low Mn steel), the change in Mn detection strength is not so large, but in the invention steel (high Mn steel), a significant decrease in the Mn concentration is observed. Such differences in the behavior of Mn are believed to be due to the diffusion of Mn during forsterite formation and the behavior of discharge from the film, but as a result, the distribution behavior of such Si and Mn is considered in the present invention. Together with heat treatment conditions and pretreatment conditions, it is thought to affect the depth of the unevenness of the interface between the glass coating and the steel plate to improve the adhesion, and if the SM value specified in the present invention is 7 or more and less than 50, Good glass film adhesion can be obtained. In the present invention, such a difference in behavior is defined by the SM value.

  Also, a clear difference can be confirmed in the distribution of Al. Generally, it is known that the Al distribution on the surface of a grain-oriented electrical steel sheet before application of a tension film shows two peaks: a peak attributed to a glass coating and a peak attributed to a base material. However, in the invention steel, this peak is more than three complex and is clearly different from conventional steels. Although the reason is unclear, the conventional steel has a simple distribution but the invention steel is complicated, as with Al for S.

  Although the relation between the number of peaks of detected strength of Al and S and the adhesion is not clear, the increase of the number of peaks in combination with the heat treatment condition and the pre-treatment condition in the present invention promotes the complication of oxide form. It is considered that the unevenness of the interface between the glass coating made of oxide and the steel sheet is considered to be fine, and the peak of Al detection intensity specified in the present invention is 3 or more and the peak of S detection intensity is 2 or more. Glass film adhesion can be obtained. In the present invention, such a difference in behavior is defined by the number of Al and S peaks. As a result of these, three-dimensional unevenness at the interface between the glass coating and the steel plate is in a deep, fine and complicated form, and is considered to be effective in improving the adhesion by the so-called anchor effect.

  Further, although not shown, a clear difference was observed between the conventional material and the invention material as to the maximum value of the detection strength of N near the surface. In addition, about the relationship between the maximum value of the detection intensity of N, and the adhesiveness of a glass film, it proves in the Example mentioned later.

Next, each parameter defined in the present invention will be described.
(SM value)
The SM value defined in the present invention is determined as follows.
As for the SM value of the glass coating surface, for the unidirectional electromagnetic steel sheet from which the tensile coating has been peeled or the unidirectional electromagnetic steel sheet before applying the tensile coating, the GDS covers the glass coating to the base steel (base steel sheet) Measure the elemental intensity distribution. In addition, with regard to the SM value of the surface of the decarburized sheet, the decarburized sheet with the surface oxide film just after decarburization in the production process of the grain-oriented electrical steel sheet extends from the steel sheet surface to the inside of the steel sheet in the thickness direction Measure the elemental intensity distribution. In this intensity distribution, Si is observed to be concentrated on the surface, and its maximum intensity is taken as Si (S). Let Mn strength at that depth be Mn (S). Further, the strength in the region where the Si strength and the Mn strength are stable inside the base steel sheet is taken as Si (B) and Mn (B), respectively. From these values, the SM value is calculated by the following equation (1).
SM value = Si (S) / Si (B) * Mn (B) / Mn (S) formula (1)

(Peak of Al detection intensity)
The “peak of detected Al intensity” in the present invention is determined as follows.
First, based on the result of measuring the element strength distribution in the thickness direction from the surface of the glass coating to the inside of the steel sheet as described above, the maximum value and the minimum value of the Al detection strength are determined in the strength distribution of Al in the thickness direction. Among the obtained maximum values, the maximum value of which the intensity difference with the minimum value adjacent to the surface side or the inner side is 10% or more of the minimum value is defined as the peak of the Al detection intensity. The number of peaks of Al detection intensity is determined from the number of peaks that have appeared. Thereby, the influence of the intensity change due to the measurement variation can be excluded, and the appropriate number of peaks representing the feature of the present invention can be determined.

(S peak of detected intensity)
The "S detection intensity peak" in the present invention is determined as follows.
First, based on the result of measuring the element strength distribution in the thickness direction from the glass coating surface to the inside of the steel sheet as described above, the maximum value and the minimum value of the S detection strength are determined in the strength distribution of S in the thickness direction. Among the obtained local maximums, the local maximum at which the intensity difference between the local minimum adjacent to the surface side or the inner side is 10% or more of the local minimum is defined as the peak of the S detection intensity. The number of peaks of S detection intensity is determined from the number of peaks that have appeared. Thereby, the influence of the intensity change due to the measurement variation can be excluded, and the appropriate number of peaks representing the feature of the present invention can be determined.

The conditions of each parameter in the present invention will be described in detail below.
The SM value on the surface of the glass coating or decarburized sheet seems to simply depend only on the Si and Mn contents of the steel sheet, but as described above, the control of the Mn distribution behavior and the Si distribution behavior on the surface is the present invention It does not necessarily tend to coincide with the amount added. Rather, it changes greatly due to the heat treatment history described later, application of an aqueous solution in the middle of the process, removal of an oxide film, and the like, and the control is performed by these. In the present invention, the SM value on the surface of the glass coating is set to 7 or more and less than 50, and the SM value on the surface of the decarburized plate is set to 4 or more and less than 30. In the case of a unidirectional electromagnetic steel sheet, if the SM value of the surface of the glass film is not within this range, it becomes difficult to realize good glass film adhesion. In addition, when the SM value on the surface of the decarburized plate is not within this range, it becomes difficult to manufacture a unidirectional electromagnetic steel sheet having an SM value of 7 to less than 50 on the surface of the glass film.

  The peak number of Al detection intensity was 3 or more. Below 2 peaks, the features and effects unique to the present invention are not exhibited. Although the upper limit of the number of peaks is not limited, it is necessary that the distribution state has an intensity change that can be recognized as a peak.

  The number of peaks of S detection intensity was 2 or more. The single peak does not exhibit the features and effects unique to the present invention. Although the upper limit of the number of peaks is not limited, it is necessary that the distribution state has an intensity change that can be recognized as a peak.

  The detection maximum intensity of N is 0.05 or more and less than 0.1. With respect to the maximum detection strength of N, the effect of the present invention is not exhibited when it is 0.05 or less, and when it is 0.1 or more, the inhibitor strength becomes too large as described later, so that secondary recrystallization becomes difficult.

  In the present invention, the distribution of Al, S and N on the surface of the steel plate is controlled. If the distribution of these elements is high, the inhibitor that affects secondary recrystallization changes in that region, which may have an unexpected adverse effect on the magnetic properties. This effect should also be taken into account when the upper limit of the specified limit is reached, in particular.

  Next, manufacturing conditions of the present invention will be described. Although not limited to the following, representative conditions are described.

  The unidirectional magnetic steel sheet of the present invention is a generally known method for producing a unidirectional magnetic steel sheet: melting, hot rolling, hot rolled sheet annealing, pickling, cold rolling, decarburizing annealing, It can manufacture according to the process of nitriding annealing according to, annealing separator application, and finish annealing. Moreover, the decarburized board of this invention used as the intermediate product which manufactures a grain-oriented electrical steel sheet can be manufactured by the process of melt | dissolution, hot rolling, hot-rolled board annealing, pickling, cold rolling, and decarburizing annealing. The electromagnetic steel slab is obtained by melting steel by a converter or an electric furnace or the like, vacuum degassing the molten steel if necessary, and then performing continuous casting or ingot-post-rolling. It should be noted that the slab composition and the composition of the final product are different in a general method of producing a grain-oriented electrical steel sheet. In particular, the contents of C, S, N, and Al are reduced by purification in a decarburization step or finish annealing. There is also an element such as Mg whose content is increased by coating with an annealing separator or the like.

  In the case of producing a final product having the components of the invention steel grade, in general, the slab composition is, by mass%, C: 0.01 to 0.08%, Si: 3.0 to 4.0%, Mn: 1.0 to 3.0%, S: 0.0030 -0.01%, acid-soluble Al: 0.003 to 0.030%, N: 0.0030 to 0.050%, the balance being composed of Fe and unavoidable impurities. It is difficult for a person skilled in the art to determine the slab composition in consideration of the manufacturing conditions for controlling the magnetic characteristics and the composition change in the manufacturing process in order to obtain the final product having the target composition and the magnetic characteristics. is not.

  Slab heating is performed prior to hot rolling. In the present invention, general hot rolling conditions are applied. The slab heated at the above-mentioned temperature is subsequently hot-rolled into a hot-rolled sheet of the required thickness. With respect to the subsequent steps, normal manufacturing conditions may be applied except for the steps described below.

  In the present invention, as described above, a good glass film is formed by controlling the oxidation behavior on the surface of the base steel material until the formation of the glass film. In particular, the amount of oxygen at the time after decarburization annealing is one indicator of the effect of the present invention. In the present invention, the effects of the present invention are likely to appear in the case of 0.1 to 2.3 g / m 2. Decarburization annealing is an important step in controlling this oxidation behavior. In order to exert the effects of the present invention, Y: 700 to 900 ° C., residence time at Y-30 ° C. or more, where Y ° C. is the maximum temperature reached after cold rolling, as a temperature history in decarburizing annealing. The invention effect can be sufficiently obtained by setting the residence time in a temperature range of Y-30 ° C. or less and Y-85 ° C. or more after 10 seconds or more. The annealing atmosphere is not particularly limited, but it is preferable to set the degree of oxidation (PH2O / PH2) to more than 0.15 and 1.1 or less. Although the reason is not clear, when oxidation is performed in the above heat history and atmosphere, Ti and B are easily concentrated at the interface between the oxide film and the steel plate in the decarburized plate, and as a result, the glass film formed later Adhesion is improved. Moreover, although the reason is unclear, the effect of the present invention becomes remarkable when the heating rate of decarburizing annealing is set to 75 to 125 ° C./sec.

  Furthermore, in the present invention, in the production process of a grain-oriented electrical steel sheet manufactured through hot rolling, cold rolling, decarburizing annealing, and finish annealing, or unidirectionality manufactured through hot rolling, cold rolling, and decarburizing annealing. In the process of producing a decarburized sheet for a magnetic steel sheet, B, Al, Te, Mn, Bi, Si in the pretreatment of one or more steps of hot rolling, cold rolling, decarburizing annealing or finish annealing. The surface concentration of each element is increased by applying 0.002 to 0.120 g / m 2 of one or two or more elements of Cu to change the oxidation behavior when the steel sheet is heat-treated, and a glass film or a decarburized sheet It is possible to preferably control the element distribution state at The method of application is not particularly limited. In addition to ion plating and plating, it is possible to apply commonly used methods such as application in sulfide, oxide, hydroxide solutions, gel-like, sol-like, and colloidal suspensions. . For example, a compound such as B 2 O 3, Al 2 O 3, TeCl 4, KMnO 4, Bi 2 O 3, SiO 2, CuS, etc. is used as a solvent in water, acetone, methanol etc. to make an aqueous solution or suspension using properties such as oxidative acid solubility. It can be applied as In consideration of handling of the steel sheet, etc., it is preferable to dry particularly when a wet coating method is applied. In the present practical manufacturing method, there is an annealing separator application as a step of applying a special substance to the surface of a steel sheet, but it is possible to mix the above-mentioned element or a compound containing an element to the annealing separator and apply it. is there.

Furthermore, the effect of the present invention is preferable by removing a part of the oxide film on the surface of the steel sheet by one or more steps of pickling, mechanical polishing or chemical polishing between decarburizing annealing and before finish annealing. You can get it. That is, it is effective to remove the outermost surface of the oxide film while leaving a part of the oxide film.
As the pickling solution, inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid are effective. Although the pickling conditions are not particularly defined, the effects of the present invention appear depending on the degree of oxide film removal, so it is necessary to determine the conditions in consideration of temperature, time and concentration. It is easy for those skilled in the art who carry out the pickling even in ordinary steps to set these conditions appropriately. However, since pickling in the present invention is light pickling, it may not be uniform pickling with inorganic acid alone, and it is possible that uniform pickling is possible by mixing 0.1 to 5% of hydrofluoric acid with inorganic acid. Become. A preferable condition in consideration of the practical range is immersion in an aqueous solution of H 2 SO 4 at 40 ° C. or less and at a concentration of 5% or less for 10 seconds or less. Under these conditions, a pickling weight loss of 1 to 10 g / m 2 can be obtained. In addition, you may combine physical methods, such as mechanical polishing, such as pickling and brush grinding, as a process of oxide film removal. In addition, the case where nitriding annealing is inserted between decarburization annealing and finish annealing is also assumed. In such a case, the oxide film can be removed after decarburization annealing and after nitriding annealing.

  Finally, a tension film is applied to the steel sheet subjected to the above-mentioned treatment, and is shipped and used as a final product.

  Hereinafter, examples of the present invention will be described. The conditions adopted in the examples are an example for confirming the practicability and effects of the present invention, and are not limited thereto. Various conditions can be adopted without departing from the present invention as long as the object of the present invention is achieved.

  C: 0.004%, Si: 3.8%, S: 0.002%, Al: 0.007%, N: 0.0080%, and the balance to molten iron of Fe: Mn: 0.77 to 3.16% and the eight steel grades of A to H changed. Was used as a 2.6 mm thick hot-rolled sheet. From the hot-rolled sheet, cold rolling, decarburizing annealing and finish annealing were performed to produce a grain-oriented electrical steel sheet. In the electromagnetic steel sheet, the composition of the slab (Table 1) and the composition of the product plate (Table 2) are described because the components change during melting and in the process up to the product. Underlines indicate outside the scope of the invention.

  For the hot-rolled sheet, 8 g / cm 3 of a 5% dilute aqueous solution of a compound containing Si 3 N 4 as a main component was uniformly applied to the surface of the material. Hot rolled sheet annealing was performed at 1000 ° C. × 30 seconds, and then cold rolled to 0.23 mm. Thereafter, decarburization annealing was performed to produce a decarburized plate, and further, through finish annealing, a grain-oriented electrical steel sheet was manufactured. After the decarburization step, the oxide film was removed by gentle pickling. A 9% dilute aqueous solution of a compound containing MnS and AlTe is uniformly applied to the surface of the material and dried, and then a material capable of applying an annealing separating agent mainly made of MgO is blown away with a gas capable of nitriding. Annealing was performed at 1200 ° C. for 20 hours by heating. The conditions of decarburization annealing, the conditions of pickling after decarburization annealing, and the coating conditions of the aqueous solution at the time of finish annealing are shown in Tables 3-8.

The glass plate and the decarburized plate obtained in the middle process were analyzed by GDS. Maximum reaching temperature at decarburization temperature, (Maximum reaching temperature -30) ° C Staying time, (Maximum reaching temperature -30) ° C or less (Maximum reach temperature -85) Staying time in temperature range or higher, Pickling Regarding the relationship between the number of times of processing, the combination of elements contained in the dilute aqueous solution and the amount of application and the possibility of secondary recrystallization performed at any time before final annealing, the results are shown in Table 3 Shown in 8. A general index B8 / Bs obtained by dividing the magnetic flux density B8 obtained from the SST measurement by the saturation magnetic flux density Bs was used as a reference as a measure of the presence or absence of secondary recrystallization. Four types of evaluations were made, ○ (good) of 0.85 or more, 二 for which B8 / Bs did not reach the definition, △ for secondary recrystallization, and x for those not for secondary recrystallization. In addition, for evaluation of adhesion to glass film, φ10 bending was carried out, and the one in which the bent portion was peeled entirely was judged by ×, peeled by 3 to 5 cm 2 by Δ, 1 to 3 cm 2 by ○, and 1 cm 2 or less by ◎. . The ones that meet the good judgment are the maximum reaching temperature 700-900 ° C at decarburization temperature rising, (maximum reaching temperature -30) ° C over 4s or less, (maximum reaching temperature -30) ° C or less (maximum reaching temperature- 85) Staying time in a temperature range of 10 ° C. or higher, 1 time or more of pickling treatment times before the final annealing, 1 time or more of B, Al, Te, Mn, Bi, Si, or Cu at any time It was a case where 0.002-0.120 g / m <2> of 2 or more types of elements were apply | coated.

Claims (9)

A unidirectional electromagnetic steel sheet having a glass coating formed on the surface of a base steel sheet,
The base steel sheet is, by mass%, Si: 3.0 to 4.0%, Mn: 1.0 to 3.0%, C: 0.0001 to 0.1%, S: 0.0001 to 0.01%, acid soluble Al: 0.003 to 0.030%, N: 0.0030 to 0.050 %, The balance being composed of Fe and unavoidable impurities, the SM value defined below is 7 or more and less than 50, has 3 or more peaks of Al detection intensity defined below, and is specified below A unidirectional electromagnetic steel sheet having two or more peaks of detected S intensity and having a maximum detected intensity of N measured by GDS of 0.05 or more and less than 0.1.
SM value:
The element strength distribution is measured by GDS from the surface to the inside of the glass film, and in the strength distribution of Si and Mn in the thickness direction, the highest strength of Si concentrated on the surface is Si (S), and the highest strength is Si Let the Mn intensity at the depth at which (S) is detected be Mn (S). Further, the strength in the region where the Si strength and the Mn strength are stable inside the base steel sheet is taken as Si (B) and Mn (B), respectively. From these values, the SM value is calculated by the following equation (1).
SM value = Si (S) / Si (B) * Mn (B) / Mn (S) formula (1)
Peak of Al detection intensity:
The element strength distribution is measured by GDS from the surface to the inside of the glass film, and the maximum value and the minimum value of the Al detection strength are determined in the strength distribution of Al in the plate thickness direction. Among the obtained maximum values, the maximum value of which the intensity difference with the minimum value adjacent to the surface side or the inner side is 10% or more of the minimum value is defined as the peak of the Al detection intensity.
Peak of S detected intensity:
Elemental intensity distribution is measured by GDS from the surface to the inside of the glass film, and the maximum value and the minimum value of the S detection intensity are determined in the intensity distribution of S in the plate thickness direction. Among the obtained local maximums, the local maximum at which the intensity difference between the local minimum adjacent to the surface side or the inner side is 10% or more of the local minimum is defined as the peak of the S detection intensity. The base steel sheet further contains, in mass%, Cr: 0.3% or less, Cu: 0.4% or less, P: 0.5% or less, Sn: 0.3% or less, Ni: 1% or less, B, Bi , Te and Se: B + Bi + Se + S + Te total The grain-oriented electrical steel sheet according to claim 1, characterized in that it contains one or more elements of 0.015% or less. It is a decarburized plate that is an intermediate product of unidirectional magnetic steel plates,
Si: 3.0 to 4.0%, Mn: 1.0 to 3.0%, C: 0.0001 to 0.1%, S: 0.0001 to 0.01%, acid soluble Al: 0.003 to 0.030%, N: 0.0030 to 0.050% in mass%, A decarburizing plate for a unidirectional electromagnetic steel sheet, characterized in that the balance is made of Fe and unavoidable impurities, and the SM value defined below is 4 or more and less than 30.
SM value:
The strength distribution of Si and Mn in the thickness direction is measured by GDS from the surface coated with the oxide film to the inside, and the highest strength of Si concentrated on the surface is Si (S), and the highest strength is Si (S (S) The Mn intensity at the depth at which) is detected is taken as Mn (S). Further, the strength in the region where the Si strength and the Mn strength are stable inside the base steel sheet is taken as Si (B) and Mn (B), respectively. From these values, the SM value is calculated by the following equation (1).
SM value = Si (S) / Si (B) * Mn (B) / Mn (S) formula (1) Cr: 0.3% or less, Cu: 0.4% or less, P: 0.5% or less, Sn: 0.3% or less, Ni: 1% or less, B, Bi , Te, and Se: B + Bi + Se + S + Te in total of 0.015% or less The decarburizing plate for a grain-oriented electrical steel sheet according to claim 3, which contains one or more elements among them. A method of manufacturing the grain-oriented electrical steel sheet according to any one of claims 1 or 2 through hot rolling, cold rolling, decarburizing annealing, and finish annealing,
The maximum reaching temperature of the decarburization annealing is Y: 700 to 900 ° C., residence time at Y-30 ° C. or higher: 4 seconds or less, and thereafter residence at a temperature range of Y-30 ° C. or less, Y-85 ° C. or higher Time: 10 seconds or more, The manufacturing method of a unidirectional electromagnetic steel sheet characterized by the above-mentioned.   The method according to claim 5, wherein the oxide film on the surface of the steel sheet is removed by one or more steps of pickling, mechanical polishing or chemical polishing between the decarburizing annealing and the finish annealing. Manufacturing method of one-way electrical steel sheet. A method of manufacturing the grain-oriented electrical steel sheet according to any one of claims 1 or 2 through hot rolling, cold rolling, decarburizing annealing, and finish annealing,
One or two of B, Al, Te, Mn, Bi, Si, and Cu on the steel sheet surface as at least any one pretreatment of the hot rolling, the cold rolling, the decarburizing annealing, and the finish annealing. The manufacturing method of the unidirectional electromagnetic steel sheet characterized by apply | coating 0.002-0.120 g / m <2> of elements more than seed | species. A method for producing a decarburized sheet according to any one of claims 3 or 4 through hot rolling, cold rolling and decarburizing annealing,
The maximum reaching temperature of the decarburization annealing is Y: 700 to 900 ° C., residence time at Y-30 ° C. or higher: 4 seconds or less, and thereafter residence at a temperature range of Y-30 ° C. or less, Y-85 ° C. or higher Time: 10 seconds or more, The manufacturing method of the decarburizing board for a unidirectional electromagnetic steel sheet characterized by the above-mentioned.   One or more elements of B, Al, Te, Mn, Bi, Si, and Cu on the steel sheet surface as at least any one pretreatment of the hot rolling, the cold rolling, and the decarburizing annealing. The method of manufacturing a decarburized sheet for a unidirectional magnetic steel sheet according to claim 8, wherein 0.002 to 0.120 g / m 2 of the metal is applied.

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