Technical field
[0001]
The present invention relates to a method for producing a non-oriented electrical steel sheet and non-oriented electrical steel sheet.
The present application, to 01 May 16, 2017, claiming priority based on Japanese Patent Application No. 2017-005213, filed in Japan, the contents of which are incorporated here.
[0002]
　In recent years, attention has been focused on global environmental problems, a need for a commitment to energy conservation, have been increasing more. Among them, high-efficiency electrical equipment, there has been a strong demand in recent years. Therefore, even in the non-oriented electrical steel sheet is widely used as a core material such as a motor or a generator or a transformer, demand for improvement in the magnetic properties are further strengthened. Recently, electric vehicles and motors and generators for hybrid vehicle efficiency progresses, and, in the motor compressor, the tendency is remarkable.
[0003]
　In order to improve the magnetic properties of non-oriented electrical steel sheet, increasing the electrical resistance of the steel sheet by adding alloying elements in the steel, it is effective to reduce the eddy current loss. Therefore, for example, in Patent Documents 1 to 3 below, was added Si, Al, Mn, an element having an effect of increasing the electrical resistance such as P or the like, reduction improvement (iron loss of magnetic properties, the magnetic flux density, etc. has been conducted to achieve an increase, etc.).
CITATION
Patent Document
[0004]
Patent Document 1: WO 2016/027565
Patent Document 2: Japanese Patent 2016-130360 JP
Patent Document 3: Japanese Patent 2016-138316 JP
Summary of the Invention
Problems that the Invention is to Solve
[0005]
　Here, when considering the addition of alloying elements in the same amount (mass%), except for the large P of adverse cold rolling property, Si is easily increase the electrical resistance, core loss of an effective element in reducing. Therefore, in Patent Document 1 discloses that the Si content is 6 wt% or less, in Patent Document 2 and Patent Document 3, discloses making the Si content 5.0% or less It is. Further, in Patent Documents 1 to 3, the Al content is set to 0.0050% or less, by increasing the electrical resistance Si or Si and Mn, it is also disclosed to reduce the iron loss
[0006]
　However, the present inventors have studied, the steel plate shown in Patent Documents 1 to 3, W 10/400 reduction of high-frequency iron loss, such as (improvement) was not sufficient. The reason is that, although the reduction of the high-frequency iron loss is essential highly alloyed, in Patent Documents 1 to 3 not been studied high-frequency iron loss, the alloy amount required for the high-frequency iron loss reduction and the lower limit value, Si, Al, since the allocation of the proper amount of Mn is not taken into consideration, W 10/400 reduction of high-frequency iron loss such as is considered not sufficient.
[0007]
　The present invention was made in view of the above problems. An object of the present invention, the cold rolling property is good, there is provided a method of manufacturing the magnetic properties, non-oriented electrical steel sheet and non-oriented electrical steel sheet particularly excellent high-frequency iron loss.
Means for Solving the Problems
[0008]
　In order to solve the above problems, the present inventors have conducted extensive studies. As a result, (i) to the Al content is less than a predetermined value, (ii) contributes to the increase of the electrical resistance, that the Mn adversely less to cold rolling property is included together with Si, the good cold while ensuring between rolling resistance was obtained a finding that it is possible to improve the magnetic properties.
　Further, in order to improve further cold rolling property, P, which may lead to a decrease in cold rollability, Sn, it is required to reduce the content of Sb. On the other hand, the present inventors found that when reducing the content of Sn and Sb, is nitrided during finish annealing is promoted, the magnetic properties were obtained even finding that may be reduced. Based on such findings, the inventors of the present inventors have conducted further studies, even if with a reduced content of Sn and Sb, without lowering the magnetic properties, the cold rollability conceive more can be further improved method, and have completed the present invention.
　Summary of the completed invention based on the above findings, as follows.
[0009]
(1) non-oriented electrical steel sheet according to one embodiment of the present invention, the chemical composition, in mass%, C: 0%, greater than 0.0050% or less, Si: 3.0% ~ 4.0%, Mn : 1.0% ~ 3.3%, P: 0% greater than, less than 0.030%, S: 0% greater than, 0.0050% or less, sol. Al: 0%, greater than 0.0040% or less, N: 0%, greater than 0.0040% or less, O: 0.0110% ~ 0.0350%, Sn: 0% ~ 0.050%, Sb: 0% ~ 0.050%, Ti: 0%, greater than 0.0050% or less, containing the balance being Fe and impurities, Sn + Sb: 0.050% or less, Si-0.5 × Mn: 2.0% not less than, O content of mid-thickness portion excluding the surface layer portion ranges to the position of 10μm from the surface and the back surface in the depth direction is less than 0.0100%.
[0010]
Method for producing a non-oriented electrical steel sheet according to another embodiment of (2) the present invention, the chemical composition, in mass%, C: 0%, greater than 0.0050% or less, Si: 3.0% ~ 4. 0%, Mn: 1.0% ~ 3.3%, P: 0% greater, than 0.030%, S: 0%, greater than 0.0050% or less, sol. Al: 0%, greater than 0.0040% or less, N: 0%, greater than 0.0040% or less, O: less than 0.0100%, Sn: 0% ~ 0.050%, Sb: 0% ~ 0.050 % Ti: 0% greater, containing 0.0050% or less, the balance being Fe and impurities, Sn + Sb: 0.050% or less, Si-0.5 × Mn: steel ingot is 2.0% or more and a hot rolling step of the hot-rolled to hot-rolled steel sheet, a hot-rolled sheet annealing step of annealing said hot-rolled steel sheet, the hot-rolled steel sheet after the hot rolled sheet annealing step to cold rolling a cold rolling step of cold-rolled steel sheet, anda finish annealing step performing finishing annealing to said cold-rolled steel sheet, and in the final annealing step, the average in the entire thickness direction of the cold-rolled steel sheet after finish annealing as the O content is 0.0350 wt% or less than 0.0110 wt%, the final annealing conditions are controlled It is.
[0011]
(3) The method of producing non-oriented electrical steel sheet according to the above (2), in the final annealing step, so that the dew point of the atmosphere during the time and soaking temperature increase is in the range of -10 ° C. ~ 40 ° C. it may be controlled to.
Effect of the invention
[0012]
　According to this aspect of the present invention, the non-oriented electrical steel sheet having a good cold rolling resistance and excellent magnetic properties, and a manufacturing method thereof are obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013]
FIG. 1 is a diagram of the structure of non-oriented electrical steel sheet schematically showing according to an embodiment of the present invention.
2 is a diagram schematically showing the structure of the base steel of the non-oriented electrical steel sheet according to the embodiment.
3 is a diagram showing an example of a flow of a method of manufacturing the non-oriented electrical steel sheet according to the embodiment.
DESCRIPTION OF THE INVENTION
[0014]
　Hereinafter, with reference to the drawings will be described in detail one form of a preferred embodiment of the present invention. In the present specification and drawings, components having substantially the same function and structure, and repeated explanation is omitted referring to the figures.
[0015]
(Non-oriented Electromagnetic steel sheets)
　in the non-oriented electrical steel sheet, as described prior, in order to reduce iron loss, in general, increasing the electrical resistance of the steel sheet by containing alloy elements in steel Te reduces the eddy current loss. Here, when considering that the inclusion of alloying elements of the same content (mass%), Si is because easy to increase the electrical resistance, which is an element effective in reducing iron loss. However, the result of the examination by the present inventors, when the Si content exceeds 4.0 mass%, it has been found that cold rolling of non-oriented electrical steel sheet is remarkably lowered.
[0016]
　Further, Al is also an alloying element indicating the increasing effect of the same electrical resistance and the Si. However, the result of the examination by the present inventors, Al also revealed that lowering the cold rolling property as with Si. Also, the Al content is increased, the magnetic properties tend to decrease hysteresis loss is deteriorated. Therefore, in the non-oriented electrical steel sheet, be contained a large amount of Al as an alloying element is difficult. In non-oriented electrical steel sheet, in order to suppress the deterioration of the magnetic properties due to the deterioration of the hysteresis loss, Al content is preferably less.
[0017]
　The present inventors seek methods of improving the cold rollability while suppressing lowering of magnetic properties were conducted extensive studies. As a result, the Al content is set to less than a predetermined value, and the Mn adversely less to cold rolling property that is included together with Si, that it is possible to improve the cold-rolling property and magnetic properties findings were obtained.
　Further, in order to improve further cold rolling property, P, which may lead to a decrease in cold rollability, Sn, it is required to reduce the content of Sb. However, the present inventors have found that reducing the content of Sn and Sb is to promote the nitriding during finish annealing to obtain also finding that may reduce the magnetic properties. The present inventors have conducted further studies, by is properly oxidized surface layer of the steel sheet during finish annealing by suppressing nitriding, the content of Sn and Sb in order to further improve the cold-rollability even when reduced to obtain a finding that can suppress the deterioration of magnetic properties.
[0018]
　In the following, with reference to FIGS. 1 and 2, for and a method of manufacturing the same (non-oriented electrical steel sheet according to the present embodiment) non-oriented electrical steel sheet according to an embodiment of the present invention will be described in detail.
　Figure 1 is a diagram schematically showing the structure of a non-oriented electrical steel sheet according to the embodiment of the present invention, FIG. 2, the structure of the base steel of the non-oriented electrical steel sheet according to the embodiment of the present invention is a diagram schematically showing.
[0019]
　Non-oriented electrical steel sheet 10 according to this embodiment, as schematically shown in FIG. 1, it has a base iron 11 having a predetermined chemical composition. Non-oriented electrical steel sheet according to the present embodiment may comprise only the base steel 11, but the surface of the base steel 11 preferably further has an insulating coating 13.
[0020]
　In the following, first, the base steel 11 of the non-oriented electrical steel sheet 10 according to the present embodiment will be described in detail.
[0021]

　base iron 11 of the non-oriented electrical steel sheet 10 according to this embodiment, the chemical composition, in mass%, C: 0%, greater than 0.0050% or less, Si: 3.0 % ~ 4.0%, Mn: 1.0 % ~ 3.3%, P: 0% greater than, less than 0.030%, S: 0% greater than, 0.0050% or less, sol. Al: 0%, greater than 0.0040% or less, N: 0%, greater than 0.0040% or less, O: 0.0110% ~ 0.0350% , Sn: 0% ~ 0.050%, Sb: 0% ~ 0.050%, Ti: 0%, greater than 0.0050% or less, containing the balance being Fe and impurities, Sn + Sb: 0.050% or less, Si-0.5 × Mn ≧ 2.0 % to satisfy.
[0022]
　In the following, the reason why the chemical composition of the base steel 11 of the present embodiment is defined as above, will be described in detail. In the following, unless otherwise specified, "%" related to the chemical composition denote the "mass%".
[0023]
[C: 0%, greater than 0.0050% or
　less] C (carbon), together with an element which is inevitably contained, an element that causes iron loss deterioration (increase in iron loss). If the C content exceeds 0.0050%, the iron loss deteriorates in non-oriented electrical steel sheet is produced, it is impossible to obtain good magnetic properties. Accordingly, in the non-oriented electrical steel sheet according to the present embodiment, the C content is 0.0050% or less. C content is preferably not more than 0.0040%, more preferably 0.0030% or less. C content is preferably as small as possible, C is an element inevitably contained, the lower limit is 0 percent. Further, when the C content to try to reduce than 0.0005%, a significant increase in cost. Therefore, C content may be 0.0005% or more.
[0024]
[Si: 3.0% ~
　4.0%] Si (silicon), by increasing the electrical resistance of the steel, reduce the eddy current loss, which is an element to improve the high-frequency iron loss. Also, Si, since a large solid-solution strengthening ability is an effective element in increasing the strength of non-oriented electrical steel sheet. In non-oriented electrical steel sheet, high strength, it is necessary from the viewpoint of suppressing deformation and fatigue fracture suppression at the time of high speed rotation of the motor. In order to sufficiently exert such effects, it is necessary to the Si content 3.0% or more. Si content is preferably 3.1% or more, more preferably 3.2% or more.
　On the other hand, when the Si content exceeds 4.0%, the workability is remarkably deteriorated, it becomes difficult to implement a cold-rolled, steel sheet or broken in the course of cold rolling (i.e. , cold rolling is lowered). Therefore, Si content is 4.0% or less. Si content is preferably not more than 3.9%, more preferably not more than 3.8%.
[0025]
[Mn: 1.0% ~
　3.3%] Mn (manganese) is, by increasing the electrical resistance, and reduce eddy current loss, which is an element to improve the high-frequency iron loss. Moreover, Mn, although solid-solution strengthening ability than Si is small, without deteriorating the workability, an element which can contribute to an increase of the strength of the non-oriented electrical steel sheet. In order to sufficiently exert such effects, it is necessary to a Mn content of 1.0% or more. Mn content is preferably 1.2% or more, more preferably 1.4% or more.
　On the other hand, when the Mn content exceeds 3.3%, a reduction in magnetic flux density becomes remarkable. Therefore, Mn content is 3.3% or less. Mn content is preferably not more than 3.0%, more preferably not more than 2.8%.
[0026]
[P: 0% greater, than 0.030%]
　P (phosphorus), in the content of Si and Mn is often high alloy steel, is an element significantly workability is deteriorated difficult cold rolling. Accordingly, P content is less than 0.030% or. P content is preferably not more than 0.020% or, more preferably, 0.010% or less.
　P content is better the less, P is an element inevitably contained, the lower limit is 0 percent. When the P content to try to less than 0.001% leads to a significant increase in cost. Therefore, it is preferable that the lower limit of 0.001% or more. More preferably 0.002% or more.
[0027]
[S: 0%, greater than 0.0050% or less]
　S (sulfur) may increase the iron loss by forming fine precipitates of MnS, which is an element degrading the magnetic properties of non-oriented electrical steel sheet. Therefore, S content should be 0.0050% or less. S content is preferably not more than 0.0040%, more preferably at most 0.0035%.
　S content is preferably as small as possible, S is an element inevitably contained, the lower limit is 0 percent. Also, if an attempt is made lower than 0.0001% of S content leads to significant increase in cost. Thus, S content is preferably 0.0001% or more.
[0028]
[Sol. Al: 0%, greater than 0.0040% or less]
　Al (aluminum), when a solid solution state in the steel, to reduce the eddy current loss by increasing electrical resistance of the non-oriented electrical steel sheet, high-frequency iron loss it is an element to improve. However, in the non-oriented electrical steel sheet according to the present embodiment, positively to contain Mn is an element to increase the electric resistance without deteriorating the workability than Al. Therefore, it is not necessary to contain actively Al. In addition, sol. When Al (acid soluble Al) content exceeds 0.0040% grain growth in the hot-rolled sheet annealing and finish annealing is inhibited fine nitrides in the steel is precipitated, the magnetic characteristics are deteriorated. Therefore, sol. Al content, and 0.0040%. sol. Al content is preferably 0.0030% or less, more preferably 0.0020%.
　Meanwhile, Al is an element inevitably contained, the lower limit is 0 percent. In addition, sol. When the Al content to try to reduce than 0.0001% leads to a significant increase in cost. Therefore, sol. Al content is preferably 0.0001% or more.
[0029]
[N: 0%, greater than 0.0040% or less]
　N (nitrogen) is an element which forms fine nitrides in steel increases the core loss, deteriorating the magnetic properties of non-oriented electrical steel sheet . Therefore, N content is required to be 0.0040%. N content is preferably not more than 0.0030% or, more preferably 0.0020%.
　Meanwhile, N is an element inevitably contained, the lower limit is 0 percent. Moreover, the N content is better the less, when the N content to try to reduce than 0.0001% leads to a significant increase in cost. Therefore, N content is preferably 0.0001% or more. More preferably 0.0003% or more.
[0030]
[O: 0.0110% ~ 0.0350% ]
　Reducing the Sn content and the Sb content in the range to be described later, nitriding of the steel sheet surface during final annealing is promoted. O (oxygen), in order to prevent the nitriding during finish annealing, an element that is introduced into the steel during finish annealing. To prevent nitridation during the final annealing, it is necessary to introduce oxygen as O content is 0.0110% or more in the steel. O content is preferably not less than 0.0115%, more preferably not less than 0.0120%.
　On the other hand, if the O content exceeds 0.0350%, the oxidation layer of the steel sheet surface layer portion formed by the introduction of oxygen becomes thicker, the magnetic characteristics are deteriorated unfavorably. Therefore, O content is less 0.0350%. O content is preferably not more than 0.0330%, more preferably at most 0.0300%.
[0031]
　In general, when the steel sheet at the time of final annealing is nitride, iron loss is increased. On the other hand, when the oxidation of the steel sheet surface, nitride can be suppressed, but the magnetic characteristics are deteriorated by the oxide produced reversed. Therefore, conventionally, oxidizing the steel sheet surface has not been performed. In contrast, in certain component system, and that the oxygen content of the whole is controlled to be 0.0110 to 0.0350 percent, while suppressing nitride, a minimum even deterioration of the magnetic properties due to oxide It suppressed it is a finding of the present inventors have newly found.
[0032]
　0.0350% or less of O content 0.0110% or more as described above, as detailed below, refers to the content of the average in the entire thickness direction of the base steel 11. In non-oriented electrical steel sheet according to the present embodiment, O in the base steel 11 (oxygen) is introduced into the steel mainly during finish annealing. Therefore, most of the introduced oxygen, present in the surface layer portion of the base steel 11 as described in detail below, the distribution of oxygen along the thickness direction is not uniform. Oxygen content than the surface layer portion of the base steel 11 for (O content) will be described again below.
[0033]
[Sn:
0% ~ 0.050%] [Sb: 0% ~
　0.050%] Sn, since Sb is not necessarily contained, the lower limit is 0%.
　Sn (tin) and Sb (antimony), by segregates to the surface of the steel sheet to suppress the nitriding during annealing, is a useful element for securing the lower core loss. Thus, in the non-oriented electrical steel sheet according to the present embodiment, in order to obtain such an effect, it is preferred to incorporate at least one of Sn and Sb in the base steel 11.
　Specifically, Sn content is preferably 0.005% or more, more preferably 0.010% or more. Further, Sb content is preferably 0.005% or more, more preferably 0.010% or more.
　On the other hand, if the content of Sn and Sb exceeds 0.050%, respectively, the cold rolling becomes difficult ductility of the steel matrix is reduced. Therefore, even if to be contained, the content of Sn and Sb is preferably 0.050%, respectively less. Sn content is more preferably 0.040% or less, further preferably 0.030% or less. Further, Sb content is more preferably 0.040% or less, further preferably 0.030% or less.
[0034]
[Sn + Sb: 0.050% or
　less] Sn and Sb, as described above, is an element made too is contained much in the steel matrix 11 and causes deterioration of the cold rollability. In particular, the total content of Sn and Sb exceeds 0.050% reduction in cold rolling property becomes remarkable. Accordingly, the total content of Sn and Sb is 0.050% or less. The total content of Sn and Sb is preferably not 0.040% or less, more preferably 0.030% or less.
[0035]
[Ti: 0%, greater than 0.0050% or
　less] Ti (titanium) is inevitably contained in raw materials of the Si and Mn. Element Ti is the C in the base steel, N, O, etc. combine with TiN, TiC, to form a fine precipitate, such as Ti oxides, deteriorating the magnetic properties to inhibit grain growth during annealing it is. Therefore, Ti content is 0.0050%. Preferably 0.0040% or less, more preferably 0.0030% or less.
　Meanwhile, Ti is an element inevitably contained, the lower limit is 0 percent. Since the the Ti content to try to less than 0.0003% becomes large cost increase, the Ti content is preferably made 0.0003% or more. More preferably. It is 0.0005% or more.
[0036]
　Non-oriented electrical steel sheet according to the present embodiment includes the above elements, and the balance basically in that it consists of Fe and impurities. However, in the non-oriented electrical steel sheet according to the present embodiment, other than the above elements Ni (nickel), Cr (chromium), Cu (copper), and may contain elements such as Mo (molybdenum). Be contained 0.50% or less These elements each, the effect of the non-oriented electrical steel sheet according to the present embodiment is not impaired. In order to accelerate the grain growth during finish annealing of a non-oriented electrical steel sheet, Ca (calcium), Mg (magnesium), La (lanthanum), Ce (cerium), Pr (praseodymium) and Nd (neodymium) the respective 100 ppm (0.0100%) may contain the following ranges.
[0037]
　Further, in addition to the above elements, Pb (lead), Bi (bismuth), V (vanadium), and may contain elements such as As (arsenic), B (boron). Even if these elements are included in the range of 0.0001% to 0.0050%, respectively, the effect of the non-oriented electrical steel sheet according to the present embodiment is not impaired.
[0038]
: [Si-0.5 × Mn 2.0 % or more]
　In oriented electrical steel sheet according to the present embodiment, after controlling the content of each element as described above, and the Si content and Mn content controlled so as to satisfy a predetermined relationship.
　Si is a ferrite phase formation promoting elements (so-called ferrite former element), while it is, the Mn is an alloy element, which is an austenite phase formation promoting elements (so-called austenite former element). Thus, depending on the content of each Si and Mn, the non-oriented electrical steel sheet metal structure changes, non-oriented electrical steel sheet, or a component system having a transformation point, and no component of the transformation point or it becomes. The non-oriented electrical steel sheet according to the present embodiment, it is required to appropriately increase the average crystal grain size in the base steel 11, be no component of the transformation point increases the crystal grain size It becomes an effective means for. Therefore, so as not to have component system the transformation point, the content of each of Si and Mn must satisfy the predetermined relationship.
[0039]
　According to the studies of the present inventors, (in other words, the effect of canceling the ferrite phase formation promoting ability) austenite formation promoting ability of Mn it is believed to 0.5 times the ferrite phase formation promoting ability of Si. Therefore, equal amounts of ferrite phase formation promoting ability in the present embodiment, based on the content of Si, can be expressed as "Si-0.5 × Mn".
[0040]
　If the value of the Si-0.5 × Mn is less than 2.0%, the non-oriented electrical steel sheet, it becomes a component system having a transformation point. As a result, there is a concern that the steel sheet of the metal structure during the process of producing high-temperature treatment is not a ferrite single phase, the magnetic properties of non-oriented electrical steel sheet is lowered. Therefore, the value of the Si-0.5 × Mn has to be 2.0% or more. Preferably, it is 2.1% or more.
　On the other hand, the upper limit of the Si-0.5 × Mn is particularly not intended to define, from the range of the Si content and the Mn content of the non-oriented electrical steel sheet according to the present embodiment, Si-0.5 × the value of Mn can not be more than 3.5%. Therefore, the upper limit of the Si-0.5 × Mn is essentially of 3.5%.
[0041]
　Although the chemical composition component of the base steel in the non-oriented electrical steel sheet according to the present embodiment has been described in detail.
[0042]
　The chemical composition of the base steel in the non-oriented electrical steel sheet, in the case of post-measure, it is possible to utilize various known measurement methods. For example, spark discharge optical emission spectrometry, ICP emission spectrometry, and further, C, combustion in the case of measuring accurately the S - infrared absorption method, O, in the case of N to accurately measure the inert gas fusion - Red outer absorption method / thermal conductivity method may be appropriately used.
[0043]

　Subsequently, referring to FIG. 2, the distribution of oxygen in the base steel 11 of the non-oriented electrical steel sheet 10 according to the present embodiment will be described in detail.
　As briefly mentioned prior, when the non-oriented electrical steel sheet 10 according to this embodiment is manufactured, at the time of finish annealing, the process to appropriately oxidizing a surface layer portion of the steel sheet is performed. Oxidation during finish annealing, so is carried out by controlling the dew point of the annealing atmosphere, an oxygen atom, it will penetrate from the surface toward the base steel 11 inside the base steel 11. As a result, the surface portion of the base iron 11 of the non-oriented electrical steel sheet 10 according to this embodiment, as schematically shown in FIG. 2, the surface oxide portions 11a in a state in which oxygen is concentrated is formed , and the base material portion 11b is a portion other than the surface layer oxidation unit 11a, and the surface oxide portion 11a, so that the content of oxygen (O content) is different.
[0044]
　The thickness t of the surface layer oxide portion 11a shown in FIG. 2 o is, the present inventors have conducted a study in various finish annealing conditions were larger number even μm approximately. Further, in FIG. 2, for convenience of illustration, the ends of the base material portion 11b of the surface layer oxidation unit 11a is illustrated as a flat boundary surface between the actual surface oxidation unit 11a and the base material part 11b it is often not in the flat. Therefore, in the base steel 11, when considering the O content in the portion other than the surface layer oxidation unit 11a, in the present embodiment, in consideration of the non-flatness of the interface between the surface layer oxide portion 11a and the base material portion 11b, except to the position of 10μm along the depth direction from the surface and the back surface of the base steel 11, (in FIG. 2, the thickness t plate thickness central portion remaining b portion where indicated) focusing on the O content in.
[0045]
　In the base iron 11 of the non-oriented electrical steel sheet 10 according to this embodiment, except for the surface layer portion is in the range of up to 10μm position along the depth direction from the surface and the back surface of the steel sheet (base steel 11), mid-thickness O content of the portion is less than 0.0100%. If the O content in the thickness center portion is not less than 0.0100% is undesirable because the magnetic characteristics are deteriorated by an increase in the oxide in the steel. O content of the thickness center portion is preferably not more than 0.0080%, may be 0%.
[0046]
　Prior mentioned, O content in the base steel 11 of 0.0110% - 0.0350% is meant O content of the average in the entire thickness direction of the base steel 11, the thickness center section O content different from the.
　As described above, O content of thickness central portion surface and toward the depth direction from the back surface except to 10μm position of the steel sheet (base steel 11) is a steel ingot in which the base steel under 11 It can be said to be of O content also.
[0047]
　O content of mid-thickness portion from the surface and back toward the depth direction after removal of up to 10μm position of the steel sheet by known methods of chemical polishing or the like (base steel 11), for example, inert gas fusion - by using various known measurement of infrared absorption method / thermal conductivity method, it can be measured.
[0048]
　Further, by the O content of the plate thickness center part, the O content of the average in the entire thickness direction (average oxygen content) are specified, the depth from the surface and the back surface of the steel sheet (base iron 11) of (in other words, O content of the surface layer oxide portion 11a) O content of up to 10μm position in the direction it is possible to calculate the. More specifically, O content of the surface layer oxidation unit 11a is with reference to Fig. 2, can be calculated by the following equation (1).
[0049]
　　Ｏ ｔ＝（２０／ｔ）×Ｏ １０μｍ＋［（ｔ－２０）／ｔ］×Ｏ ｂ　・・・（１）
[0050]
　Here, meanings of the symbols in the above formula (1) are as follows.
　· O t (wt%): Average in the entire thickness direction of the steel sheet O content
　· O 10 [mu] m (wt%): O containing up surface and toward the back side in the depth direction 10 [mu] m position of the steel sheet (base iron) the amount
　· O b (mass%): Sheet (base iron) surface and the portion was removed to 10μm position toward the back side in the depth direction O content
　· t ([mu] m): a base steel thickness
[0051]
　Above with reference to FIG. 2, the distribution of oxygen in the base steel 11 according to the present embodiment has been described in detail.
[0052]

　thickness of the base steel 11 in the non-oriented electrical steel sheet 10 according to the present embodiment (the thickness in FIGS. 1 and 2 t) may reduce high frequency iron loss by reducing the eddy current loss to, it is preferably not more than 0.40 mm. On the other hand, if the thickness t of the base steel 11 is less than 0.10mm, there is a possibility that the sheet passage of annealing line for sheet thickness is thin becomes difficult. Therefore, the thickness t of the base steel 11 in the non-oriented electrical steel sheet 10, or 0.10 mm, is preferably not greater than 0.40 mm. Thickness t of the base steel 11 in the non-oriented electrical steel sheet 10, more preferably, 0.15 mm or more and 0.35mm or less.
[0053]
　Although the base steel 11 of the non-oriented electrical steel sheet 10 according to this embodiment has been described in detail.
[0054]

　Next, the it is preferred insulating coating 13 which non-oriented electrical steel sheet 10 of the present embodiment has will be described briefly.
[0055]
　In order to improve the magnetic properties of non-oriented electrical steel sheet, it is important to reduce iron loss, iron loss, and an eddy current loss and hysteresis loss. By providing the insulating coating 13 on the surface of the base steel 11, it is possible to reduce the eddy current loss of the core to inhibit conduction between the electromagnetic steel plates stacked as core, practically non-oriented electrical steel sheet 10 Furthermore it is possible to improve the magnetic properties.
[0056]
　Here, the insulating film 13 to the non-oriented electrical steel sheet 10 according to this embodiment is provided, as long as it can be used as an insulating film of non-oriented electrical steel sheet, is not particularly limited, a known insulating film it is possible to use. As such an insulating film, for example, an inorganic material as a main component, may be mentioned more complex insulation coating containing an organic material. Here, the composite insulating coating, for example, chromic acid metal salts, phosphoric acid metal salts or colloidal silica, Zr compound, as a main component at least one of inorganic Ti compound or the like, particles of fine organic resin is dispersed it is there insulating coating. In particular, from the viewpoint of the production time of reducing environmental burden has increased with recent demand, the coupling agent of the phosphoric acid metal salt and Zr, or Ti, or an insulating film using these carbonates or ammonium salts as starting materials preferably used.
[0057]
　Adhesion amount of the above-mentioned insulating coating 13 is not particularly limited, for example, 0.1 g / m per side 2 or 2.0 g / m 2 preferably be on the order or less, per side 0.3g / m 2 or more 1.5 g / m 2 and more preferably at most. By forming the insulating film 13 so that the above-described deposition amount, it becomes possible to retain good uniformity. The coating weight of the insulation coating 13, in the case of post-measure, it is possible to use various known measurement methods. Adhesion amount of the insulating coating 13, for example, a non-oriented electrical steel sheet 10 forming the insulating film 13 to remove only the insulating film 13 by immersing the hot alkaline solution, calculated from the mass difference before and after removal of the insulating coating 13 it is possible to.
[0058]

　non-oriented electrical steel sheet 10 according to this embodiment, by having the above structure, exhibits excellent magnetic properties. Here, various magnetic properties of showing the non-oriented electrical steel sheet 10 according to this embodiment, Epstein method, defined in JIS C2550, veneer magnetic property measuring method specified in JIS C2556 (Single Sheet Tester: SST ) to with reference, it is possible to measure.
[0059]
　Above with reference to FIGS. 1 and 2, the non-oriented electrical steel sheet 10 according to this embodiment has been described in detail.
[0060]
(Method of manufacturing the non-oriented electrical steel sheet)
　Next, referring to FIG. 3, a method for manufacturing the non-oriented electrical steel sheet 10 according to the present embodiment as described above will be briefly described.
　Figure 3 is a flowchart illustrating an example of a flow of a method of manufacturing the non-oriented electrical steel sheet according to the present embodiment.
[0061]
　In the manufacturing method of the non-oriented electrical steel sheet 10 according to this embodiment is different from the steel ingot having a predetermined chemical composition, hot rolling, hot-rolled sheet annealing, pickling, performed cold rolling, the finish annealing in this order . In the case of forming the insulating film 13 on the surface of the base steel 11, formation of the insulating film after the final annealing is performed. Hereinafter, each step carried out by the method for producing a non-oriented electrical steel sheet 10 according to the present embodiment will be described in detail.
[0062]

　In the method of manufacturing the non-oriented electrical steel sheet according to the present embodiment, first, in mass%, C: 0%, greater than 0.0050% or less, Si: 3.0% ~ 4.0% , Mn: 1.0% ~ 3.3% , P: 0% greater than, less than 0.030%, S: 0% greater than, 0.0050% or less, sol. Al: 0%, greater than 0.0040% or less, N: 0%, greater than 0.0040% or less, O: less than 0.0100%, Sn: 0% ~ 0.050%, Sb: 0% ~ 0.050 % Ti: 0% greater, containing 0.0050% or less, the balance being Fe and impurities, Sn + Sb: 0.050% or less, Si-0.5 × Mn: steel ingot is 2.0% or more (slab) heating, by performing a hot rolling on the heated steel ingot, obtaining a hot-rolled steel sheet (step S101). The heating temperature of the steel ingot when subjected to hot rolling is not particularly intended to define, for example, preferably set to 1050 ℃ ~ 1300 ℃. The heating temperature of the steel ingot is more preferably 1050 ℃ ~ 1250 ℃.
[0063]
　As for the thickness of the hot-rolled steel sheet after hot rolling is not particularly intended to define, in consideration of the final thickness of the base steel, e.g., is preferably about 1.6 mm ~ 3.5 mm . Hot rolling step is preferably ended in the temperature of the steel sheet is in the range of 700 ℃ ~ 1000 ℃. End temperature of hot rolling is more preferably 750 ℃ ​​~ 950 ℃.
[0064]

　After the hot rolling, hot-rolled sheet annealing (annealing for hot-rolled steel sheet) is performed (step S103). In the case of continuous annealing, to the hot-rolled steel sheet, for example, at 750 ° C.-1200 ° C., to implement the annealing comprising soaking 10 seconds to 10 minutes. Also, in the case of box annealing, with respect to hot-rolled steel sheet, for example, at 650 ° C.-950 ° C., to implement the annealing comprising soaking 30 minutes to 24 hours.
[0065]

　after the hot rolled sheet annealing step, the pickling is carried out (step S105). Thus, formed on the surface of the steel sheet during hot-rolled sheet annealing, the scale layer consisting mainly of oxide are removed. If hot rolled sheet annealing is box annealing, from the viewpoint of descaling property, pickling step is preferably carried out before hot-rolled sheet annealing.
[0066]

　After the pickling step (if hot-rolled sheet annealing is carried out in box annealing, when the after hot-rolled sheet annealing step also.), The relative hot rolled steel sheet, cold rolling is performed (step S107). In cold rolling, final thickness of the base steel is at a reduction rate such that less 0.40mm or 0.10 mm, pickled plate removed scales are rolled.
[0067]

　After the cold rolling step, to cold-rolled steel sheet obtained by cold rolling, finish annealing is performed (step S109). In the finish annealing step, so that the average content of O in the entire thickness direction of the cold-rolled steel sheet after annealing the finish becomes less 0.0110 mass% or more 0.0350 wt%, the final annealing conditions are controlled. Therefore, the final annealing process, heating process, the soaking process, including the cooling process, in the final annealing step of the method of manufacturing the non-oriented electrical steel sheet according to the present exemplary engagement embodiment, for each process, needs to be controlled is there.
[0068]
　Specifically, in the course of temperature increase, an average heating rate between 1 ° C. / sec ~ 2000 ° C. / sec. Moreover, the atmosphere in the furnace during heating, H 2 H ratio of from 10 vol% to 100 vol% 2 and N 2 mixed atmosphere of (H 2 + N 2 and = 100 vol%), the dew point of the atmosphere it is preferable to -10 ° C. or higher 40 ° C. or less. The average heating rate is more preferably in the 5 ° C. / sec - 1500 ° C. / sec, H in the atmosphere 2 ratio of, more preferably 15 vol% to 90 vol%. Dew point of the atmosphere is more preferably not -5 ° C. or higher 35 ° C. or less, still more preferably 30 ° C. or less 0 ℃ higher.
　In the method of manufacturing the non-oriented electrical steel sheet according to the present embodiment, the Atsushi Nobori process of the final annealing, the rapid heating. By performing rapid heating of the temperature raising process, the base steel 11, advantageously recrystallized texture to magnetic properties is formed. If the Atsushi Nobori process of the final annealing and rapid heating, in the manufacturing method of the non-oriented electrical steel sheet according to the present embodiment, final annealing is preferably performed by continuous annealing. The average heating rate above, for example, by or using direct heating or radiant tube or using an indirect heating using a known heating method such as electrical heating or induction heating, etc. to others in the case of heating by gas burning , it can be realized.
[0069]
　The soaking process after the heating process, the soaking temperature, and 700 ° C.-1100 ° C., soaking time, 1 second to 300 seconds, atmosphere, H 2 ratio of 10 vol% to 100 vol% in a H 2 and N 2 mixed atmosphere of (H 2 + N 2 and = 100 vol%), it is preferable that the dew point of the atmosphere to -10 ° C. or higher 40 ° C. or less. Soaking temperature is more preferably from 750 ° C.-1050 ° C., H in the atmosphere 2 ratio of, more preferably 15 vol% to 90 vol%. Dew point of the atmosphere is more preferably not -10 ° C. or higher 30 ° C. or less, still more preferably -5 ° C. or higher 20 ° C. or less.
[0070]
　In the cooling process after soaking process, it is preferable to cool the average cooling rate to 200 ° C. or less at 1 ° C. / sec ~ 50 ° C. / sec. The average cooling rate is more preferably from 5 ° C. / sec ~ 30 ° C. / sec.
[0071]
　According to the manufacturing method including the steps described above, it is possible to produce a non-oriented electrical steel sheet 10 according to this embodiment.
[0072]

　After the final annealing, if necessary, the formation process of the insulating coating are performed (step S111). Here, the step of forming the insulating film, is not particularly limited, using known insulation coating treatment solution as described above may be carried out coating and drying of the treatment liquid by a known method.
[0073]
　Surface of the base steel 11 where the insulating film is formed, prior to applying the treatment solution, etc. or by degreasing alkali, hydrochloric, sulfuric, etc. pickling treatment with phosphoric acid and the like, may be subjected to any pretreatment and it may be the surface remains after annealing finish without performing these pre-treatment.
[0074]
　Above with reference to FIG. 3, a method for manufacturing the non-oriented electrical steel sheet according to the present embodiment has been described in detail.
Example
[0075]
　Hereinafter, while showing an embodiment, a method of manufacturing a non-oriented electrical steel sheet and non-oriented electrical steel sheet according to the present invention will be specifically described. Examples shown below is only one example of a method for producing a non-oriented electrical steel sheet and non-oriented electrical steel sheet according to the present invention, the non-oriented electrical steel sheet and a manufacturing method of the non-oriented electrical steel sheet according to the present invention is It is not limited to the following examples.
[0076]
(Experimental Example 1)
　contains a composition shown in Table 1, the steel slab balance being Fe and impurities, was heated to 1150 ° C., it was rolled to 2.0mm thick by hot rolling. Subsequently, the hot rolled steel sheet in the annealing furnace of a continuous annealing type, after the soaking temperature is soaking time at 1000 ° C. was hot-rolled sheet annealing of 40 seconds, of 0.25mm thickness by performing cold rolling cold It was rolled steel sheet. The cold-rolled steel sheet to, soaking time at a soaking temperature of 1000 ° C. is performed finish annealing of 15 seconds. Thereafter, further mainly of phosphoric acid metal salts, by applying and baking a solution containing an emulsion of acrylic resin on both surfaces of the steel sheet to produce a non-oriented electrical steel sheet by forming a composite insulating coating.
[0077]
　When said finishing annealing, in all test numbers, the temperature raising process, the atmosphere of the soaking process 20 vol% H 2 +80 vol N% 2 was controlled such that the atmosphere. Further, dew point, Test No. 1 is -30 ° C., Test No. 2 + 5 ° C., Test No. 3 + 15 ° C., Test No. 4 + 45 ° C., Test No. 5 + 15 ° C., Test No. 6 -15 ° C., the test number 7 was + 45 ℃. The average heating rate of 20 ° C. / sec in the temperature elevation process at the time of final annealing, the average cooling rate in the cooling process was 20 ° C. / sec. After finish annealing was cooled to 200 ° C. or less.
[0078]
　In Table 1, "Tr." Represents that which does not contain intended the appropriate elements. The underlined indicates that is out of the range of the present invention.
[0079]
　Then, for each of the non-oriented electrical steel sheet produced by Epstein method specified in JIS C2550, the magnetic flux density B 50 and the iron loss W 10/400 was assessed. The results obtained are shown together in Table 1.
[0080]
[Table 1]

[0081]
　Table 1 As is apparent from the finish O content after annealing Test No. deviated to lower than the range of the present invention 1, and Test No. 4 O content after finish annealing is disengaged to be higher than the range of the present invention test No. 7 and test No. 5 O content falls off higher than the present invention range in the mid-thickness portion, the core loss and / or magnetic flux density was inferior. On the other hand, O content of finishing the steel sheet after annealing Test No. 2 is within the scope of the present invention, test number 3, and Test No. 6, and the iron loss and magnetic flux density were both excellent.
[0082]
(Experimental Example 2)
　containing the composition shown in Table 2, the steel slab and the balance being Fe and impurities, was heated to 1160 ° C., was rolled to 2.0mm thick by hot rolling. Subsequently, the hot rolled steel sheet soaking temperature is 1000 ° C., it was annealed hot-rolled sheet in the annealing furnace of a continuous annealing expression under conditions soaking time of 40 seconds, of 0.25mm thickness by performing cold rolling cold to obtain a rolled steel sheet. Then, to this cold-rolled steel sheet, the soaking temperature is 1000 ° C., was finish annealing under conditions soaking time of 15 seconds. Thereafter, further mainly of phosphoric acid metal salts, by applying and baking a solution containing an emulsion of acrylic resin on both surfaces of the steel sheet to produce a non-oriented electrical steel sheet by forming a composite insulating coating.
[0083]
　When said finishing annealing, in all test numbers, the temperature raising process, the atmosphere of the soaking process 20 vol% H 2 +80 vol N% 2 was controlled such that the atmosphere. Dew point was + 10 ℃. The average heating rate of 30 ° C. / sec in the temperature elevation process at the time of final annealing, the average cooling rate in the cooling process was 20 ° C. / sec. After finish annealing was cooled to 200 ° C. or less.
[0084]
　In Table 2, the "Tr." Represents that which does not contain intended the appropriate elements. The underlined indicates that is out of the scope of the present invention.
[0085]
　Then, for each of the non-oriented electrical steel sheet produced by Epstein method specified in JIS C2550, the magnetic flux density B 50 and the iron loss W 10/400 was assessed. The results obtained are shown together in Table 2.
[0086]
[Table 2]

[0087]
　Test number Si content is outside the higher than the range of the content of the present invention ranges Test No. 8 deviated to be higher than, Sn content Test No. 11 deviated to be higher than the range of the present invention, Sn + Sb of the present invention 12, and the test numbers 14 to P content deviates to a higher than the range of the present invention, since each broken during cold rolling, could not magnetometry. sol. Al content Test No. 19 range Test No. 15 deviated to be higher than, Ti is deviated to be higher than the present invention the scope of the present invention was inferior and the iron loss and magnetic flux density. Mn content Test No. 18 deviated to lower than the present invention range, the iron loss was inferior. On the other hand, Test Nos 9,10,13,16 and 17 are within the scope of the present invention is the chemical composition of the steel sheet is capable of cold rolling, the iron loss and magnetic flux density was superior.
[0088]
(Experimental Example 3)
　containing the composition shown in Table 3, the steel slab balance being Fe and impurities, was heated to 1150 ° C., was rolled to 2.0mm thick by hot rolling. Subsequently, the hot rolled steel sheet soaking temperature is 1000 ° C., it was annealed hot-rolled sheet in the annealing furnace of a continuous annealing expression under conditions soaking time of 40 seconds, of 0.25mm thickness by performing cold rolling cold to obtain a rolled steel sheet. Then, the cold-rolled steel sheet, the soaking temperature is 800 ° C., was finish annealing under conditions soaking time of 15 seconds. Thereafter, further mainly of phosphoric acid metal salts, by applying and baking a solution containing an emulsion of acrylic resin on both surfaces of the steel sheet to produce a non-oriented electrical steel sheet by forming a composite insulating coating. Subsequently, the obtained steel sheets were subjected to stress relief annealing of 750 ° C. × 2 hr.
[0089]
　Here, when the above-mentioned finish annealing, in all test number, Atsushi Nobori process, the atmosphere of the soaking process 15 vol% H 2 +85 vol N% 2 was controlled such that the atmosphere. Dew point was + 10 ℃. The average heating rate of 20 ° C. / sec in the temperature elevation process at the time of final annealing, and the average cooling rate in the cooling process and 15 ° C. / sec. After finish annealing was cooled to 200 ° C. or less.
[0090]
　In Table 3, the "Tr." Represents that which does not contain intended the appropriate elements. The underlined indicates that is out of the scope of the present invention.
[0091]
　Then, for each of the non-oriented electrical steel sheet produced by Epstein method specified in JIS C2550, the magnetic flux density B 50 and the iron loss W 10/400 was assessed. The results obtained are shown together in Table 3.
[0092]
[table 3]

[0093]
　First, the magnetic properties of each test number in Experimental Example 3 was performed stress relief annealing is generally excellent when compared with the magnetic properties of each test number in Experimental Example 1 and Experimental Example 2 that have not performed stress relief annealing although it is, test Nos 20, 22 and 24 in the range of the present invention is particularly chemical composition of the steel sheet, iron loss and magnetic flux density was superior. On the other hand, Si-0.5 × Mn test No. 21 deviated to lower than the present invention range, were inferior in the iron loss and magnetic flux density. Also, Test No. 23 S content is out to enhance the scope of the present invention, as compared with Test No. 20 and 22 within the scope of the invention that are substantially the same composition except for S, iron loss and the magnetic flux density theft was inferior. As described above, even when performing the stress relief annealing, a non-oriented steel sheet according to the present invention it was found to exhibit excellent magnetic properties.
[0094]
　Having described in detail preferred embodiments of the present invention with reference to the accompanying drawings, the present invention is not limited to such an example. It would be appreciated by those skilled in the relevant field of technology of the present invention, within the scope of the technical idea described in the claims, it is intended to cover various changes and modifications , also such modifications are intended to fall within the technical scope of the present invention.
Industrial Applicability
[0095]
　According to the present invention, the non-oriented electrical steel sheet having a good cold rolling resistance and excellent magnetic properties, and therefore a manufacturing method thereof can be obtained, it has high industrial applicability.
DESCRIPTION OF SYMBOLS
[0096]
　10 non-oriented electrical steel sheets
　11 base steel
　11a superficial oxidation unit
　11b preform section
　13 insulation coating

The scope of the claims
[Requested item 1]
　Chemical composition, in
　mass%, C: 0%, greater than 0.0050% or
　less,
　Si: 3.0% ~ 4.0%, Mn: 1.0% ~
　3.3%, P: 0% greater, less than Pasento
　0.030, S: 0 Pasento than, 0.0050% or
　less, Sol. Al: 0%, greater than 0.0040% or
　less, N: 0%, greater than 0.0040% or
　less, O:
　0.0110% ~ 0.0350%, Sn: 0% ~ 0.050%,
　Sb: 0%
　0.050% ~, Ti: 0%, greater than 0.0050% or less,
containing the balance being Fe and
　impurities, Sn + Sb: 0.050% or
　less, Si-0.5 × Mn: 2.0% greater than or equal and,
　O content of mid-thickness portion excluding the surface layer portion is in the range of the depth direction from the surface and back to the position of 10μm is less than 0.0100%
non-directional, characterized in that electromagnetic steel sheet.
[Requested item 2]
　Chemical composition, in mass%, C: 0%, greater than 0.0050% or less, Si: 3.0% ~ 4.0% , Mn: 1.0% ~ 3.3%, P: 0% greater, less than 0.030%, S: 0% greater than, 0.0050% or less, sol. Al: 0%, greater than 0.0040% or less, N: 0%, greater than 0.0040% or less, O: less than 0.0100%, Sn: 0% ~ 0.050%, Sb: 0% ~ 0.050 % Ti: 0% greater, containing 0.0050% or less, the balance being Fe and impurities, Sn + Sb: 0.050% or less, Si-0.5 × Mn: steel ingot is 2.0% or more and a hot rolling step of the hot-rolled to hot-rolled steel sheet,
　a hot-rolled sheet annealing step of annealing said hot-rolled steel sheet,
　the hot-rolled steel sheet after the hot rolled sheet annealing step to cold rolling a cold rolling step of cold-rolled steel sheet,
　the recrystallization annealing step performing finishing annealing to said cold-rolled steel sheet
comprises,
　in the final annealing step, the average in the entire thickness direction of the cold-rolled steel sheet after finish annealing as the O content is 0.0350 wt% or less than 0.0110 wt%, the final annealing conditions are controlled Is,
the manufacturing method of the non-oriented electrical steel sheet, characterized in that.
[Requested item 3]
　And in the final annealing step, the dew point of the atmosphere during heating and during soaking are controlled so as to be in the range of -10 ° C. ~ 40 ° C.
The non-oriented electrical steel sheet according to claim 2, characterized in that the method of production.