0001]The present invention relates to a non-oriented electrical steel sheet.
　The present application, to 07 May 19, 2017, claiming priority based on Japanese Patent Application No. 2017-139765, filed in Japan, the contents of which are incorporated here.
BACKGROUND
[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 generator, need for improvement in the magnetic properties are further strengthened. Electric vehicles and motors for hybrid vehicles, and, in the motor compressor, the tendency is remarkable.
[0003]
　Motor core of motors as described above, the stator is a stator, and consists of a rotor is the rotor. Characteristics required for the stator and rotor composing the motor core is different from each other. The stator, while excellent for magnetic properties (core loss and magnetic flux density) is particularly sought, the rotor is required to have excellent mechanical properties (tensile strength and yield ratio).
[0004]
　Characteristics is obtained between the stator and the rotor are different. Therefore, the non-oriented electrical steel sheet for stator, a non-oriented electrical steel sheet for the rotor, if Wakere build, it is possible to realize the respective desired characteristics. However, to prepare two types of non-oriented electrical steel sheet, which leads to reduction in yield. Therefore, a superior strength required for the rotor, in order to realize a low core loss required for the stator, excellent in strength and non-oriented electrical steel sheet excellent in magnetic properties, have been conventionally studied.
[0005]
　For example, in Patent Documents 1 to 3 below, while achieving excellent magnetic properties as required for the stator, in order to achieve superior strength as determined in the rotor, as chemical components of the steel sheet, silicon the (Si) causes contained many, nickel (Ni) or copper (Cu) like intentionally added to technology element contributing to higher strength has been proposed.
CITATION
Patent Document
[0006]
Patent Document 1: Japanese Patent 2004-300535 JP
Patent Document 2: Japanese Patent 2004-315956 JP
Patent Document 3: Japanese Patent 2008-50686 JP
Summary of the Invention
Problems that the Invention is to Solve
[0007]
　However, in recent years, in order to realize the energy-saving properties required for an electric vehicle or a hybrid vehicle motors, in such a technique disclosed in the above Patent Documents 1 to 3, a low iron loss as stator material not It was sufficient.
[0008]
　Also, the element which promotes high strength such as Ni and Cu as disclosed in the above Patent Documents 1 to 3 are expensive, the positively adding these elements, the production of non-oriented electrical steel sheet cost is increased.
[0009]
　In recent years, in the electric motor of the vehicles or hybrid vehicles, they come to be made much designed to make the motor torque by the speed of the motor rotational speed, further increasing the strength of the rotor is strongly demanded. To ensure the safety of the motor is not only critical property of fracture represented by tensile strength, it should be avoided destruction by fatigue. For that purpose, not just tensile strength, to obtain a high yield stress (i.e., to obtain a high yield ratio) is important. However, even with the technique disclosed in the above Patent Documents 1 to 3, it is difficult to achieve further high strength and high yield ratio of the rotor.
[0010]
　The present invention was made in view of the above problems. An object of the present invention, manufacturing cost is suppressed, it is to provide a non-oriented electrical steel sheet high strength and high yield ratio.
　Preferably, the resulting high strength and punching the non-oriented electrical steel sheet yield ratio to a desired motor core shape (rotor shape and a stator shape), punched non-oriented electromagnetic steel sheet by laminating a plurality desired motor core shape ( forming a rotor shape, and a stator shape), of which, when annealed against those laminated stator shape is to provide a non-oriented electrical steel sheet showing a more excellent magnetic properties.
Means for Solving the Problems
[0011]
　In order to solve the above problems, the present inventors have conducted extensive studies. Specifically, punching the member for the rotor and the stator from the same non-oriented electrical steel sheet, members of the rotor, after laminating to a desired rotor shape, without annealing the laminated body both have a more excellent mechanical properties, also, members for the stator, after laminating to a desired stator shape, the more excellent magnetic properties by performing annealing the laminated body the means to realize, was conducted extensive studies.
[0012]
　Hereinafter, the member for the stator by punching a non-oriented electrical steel sheet into a desired stator shape, the member for punched stator after laminating to a desired stator shape, performed on the resulting laminate that of annealing to be referred to as the "core annealing".
[0013]
　Among the non-oriented electrical steel sheet having the same tensile strength, improved fatigue strength in order to achieve a high yield ratio purpose, non-oriented electrical steel sheet be made to have a upper yield point, potential It is considered as.
　The present inventors, by utilizing the strain aging of carbon (C), non-oriented electrical steel sheet by noting controlled to have a upper yield point. However, non-oriented electrical steel sheet is generally manufactured, a low content of C which causes a by strain aging of high purity. In particular, the non-oriented electrical steel sheet in which the content of Si is at least 3%, that Si suppresses the formation of carbides, no upper yield point. Also, just the aim of increasing the strength, C, titanium (Ti), in the non-oriented electrical steel sheet element was intentionally contain such niobium (Nb), breakdown phenomenon by a high content of C is produced as well, since carbide is significantly degrade the grain growth during the core annealing, not improved magnetic properties after the core annealing.
　Therefore, so far, it has an upper yield point, and to obtain a non-oriented electrical steel sheet excellent in magnetic properties after the core annealing is difficult.
[0014]
　Based on this viewpoint, the present inventors carried out further studies. As a result, not intentionally contain cost elements, and, in the non-oriented electrical steel sheet having a high Si content, by realizing the breakdown phenomenon by realizing further refinement of the crystal grain size, It was found that even better mechanical properties can be obtained. Further, in the non-oriented electrical steel sheet, if it is possible to suppress the content of elements such as to inhibit the grain growth during the core annealing, the more excellent magnetic properties after the core annealing also becomes possible to improve simultaneously It led to obtain the findings.
　Summary of the completed invention based on the above findings, as follows.
[0015]
[1] non-oriented electrical steel sheet according to one embodiment of the present invention, the chemical composition, in mass%, C: 0.0015% ~ 0.0040 %, Si: 3.5% ~ 4.5%, Al : 0.65% or less, Mn: 0.2% ~ 2.0% , Sn: 0% ~ 0.20%, Sb: 0% ~ 0.20%, P: 0.005% ~ 0.150% , S: 0.0001% ~ 0.0030% , Ti: 0.0030% or less, Nb: 0.0050% or less, Zr: 0.0030% or less, Mo: 0.030% or less, V: 0.0030 % or less, N: 0.0010% ~ 0.0030% , O: 0.0010% ~ 0.0500%, Cu: less than 0.10%, Ni: less than 0.50%, containing the balance Fe and consists impurities, product thickness is a 0.10 mm ~ 0.30 mm, an average crystal grain size is 10 [mu] m ~ 40 [mu] m, the core loss W10 / 800 is not more than 50W / Kg, tensile strength, is 580MPa ~ 700MPa, the yield ratio is 0.82 or more.
[2] non-oriented electrical steel sheet according to [1], C, Ti, Nb, Zr, V content may be satisfies the condition expressed by the following equation (1).
　[C] × ([Ti] + [Nb] + [Zr] + [V]) <0.000010 ··· (1)
　where, in the formula (1), the notation of [X], elemental represents (in weight percent) content of X.
[3] non-oriented electrical steel sheet according to [1] or [2], the annealing temperature 750 ° C. or higher 900 ° C. or less, by annealing at annealing conditions a soaking time of 10 minutes to the range of 180 minutes , the average crystal grain size, 60 [mu] m ~ 150 [mu] m and core loss W10 / 400 may be equal to or less than 11W / Kg.
[4] [1] to [3] is a non-oriented electrical steel sheet according to any one of comprises an upper yield point and lower yield point, the upper yield point 5MPa or more than the lower yield point higher may be.
[5] above [1] to non-oriented electrical steel sheet according to any one of [4], the chemical composition, by mass%, Sn: 0.01% ~ 0.20 %, Sb: 0 .01% to 0.20%, and may contain one or both.
[6] non-oriented electrical steel sheet according to any one of the above [1] to [5] may have an insulating film on the surface.
The invention's effect
[0016]
　According to this aspect of the present invention, the manufacturing cost is suppressed, and it is possible to obtain a non-oriented electrical steel sheet more excellent in magnetic properties after mechanical properties and core annealing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017]
FIG. 1 is an explanatory view of the structure of non-oriented electrical steel sheet schematically showing according to an embodiment of the present invention.
[2] is an explanatory diagram for describing non-oriented electrical steel sheet according to the embodiment.
[3] the stress indicated non-oriented electrical steel sheet according to the embodiment - is an explanatory diagram for explaining strain curve.
[Figure 4] non-oriented electrical steel sheet exhibits stress - is a diagram showing an example of a strain curve.
5 is a flowchart illustrating an example of a flow of a method of manufacturing the non-oriented electrical steel sheet according to the embodiment.
DESCRIPTION OF THE INVENTION
[0018]
　Reference will now be described in detail preferred embodiments 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.
[0019]
(For non-oriented electrical steel sheet)
　First, with reference to FIGS. 1 to 5, the non-oriented electrical steel sheet according to an embodiment of the present invention (non-oriented electrical steel sheet according to the present embodiment), detail description to.
　Figure 1 is an explanatory view of the structure of non-oriented electrical steel sheet according to the present embodiment shown schematically. Figure 2 is an explanatory diagram for describing non-oriented electrical steel sheet according to the present embodiment. Figure 3 is a stress indicated non-oriented electrical steel sheet according to the present embodiment - is an explanatory diagram for explaining strain curve. Figure 4 is a stress indicated non-oriented electrical steel sheet - is a diagram showing an example of a strain curve. Figure 5 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.
[0020]
　Non-oriented electrical steel sheet 10 according to this embodiment is a preferred non-oriented electrical steel sheet as a material 10 in the preparation of both the stator and rotor. Non-oriented electrical steel sheet 10 according to this embodiment, as schematically shown in FIG. 1, containing a predetermined chemical components, it has a base iron 11 indicating a predetermined mechanical and magnetic properties. Also, the non-oriented electrical steel sheet 10 according to this embodiment, the surface of the base steel 11 preferably further includes an insulating coating 13.
[0021]
　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.
[0022]

　base iron 11 of the non-oriented electrical steel sheet 10 according to this embodiment, by mass%, C: 0.0015% ~ 0.0040 %, Si: 3.5% ~ 4. 5%, Al: 0.65% or less, Mn: 0.2% ~ 2.0% , P: 0.005% ~ 0.150%, S: 0.0001% ~ 0.0030%, Ti: 0 .0030% or less, Nb: 0.0050% or less, Zr: 0.0030% or less, Mo: 0.030% or less, V: 0.0030% or less, N: 0.0010% ~ 0.0030% , O : 0.0010% ~ 0.0500%, Cu : less than 0.10%, Ni: contained less than 0.50%, one or both of the further Sn or Sb as needed, respectively 0.01 wt% containing 0.2 wt% or less, the balance being Fe and impurities.
[0023]
　The base steel 11 is a steel plate, such as hot-rolled steel sheets and cold-rolled steel sheet, for example.
[0024]
　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, "%" represents "% by mass".
[0025]
[C: 0.0015% ~
　0.0040%] C (carbon) is an element that causes iron loss deteriorates. If the C content exceeds 0.0040%, the iron loss deteriorates in non-oriented electrical steel sheet is produced, it is impossible to obtain good magnetic properties. Therefore, the non-oriented electrical steel sheet 10 according to the present embodiment, the C content, and 0.0040%. C content is preferably 0.0035% or less, more preferably 0.0030% or less.
　On the other hand, C content in the case of less than 0.0015%, the upper yield point is not generated in the non-oriented electrical steel sheet 10, not good yield ratio can not be obtained. Therefore, the non-oriented electrical steel sheet 10 according to the present embodiment, the C content is 0.0015% or more. In non-oriented electrical steel sheet according to the present embodiment, C content is preferably not less than 0.0020%, more preferably 0.0025% or more.
[0026]
[Si: 3.5% ~
　4.5%] Si (silicon) elevates the electrical resistance of the steel to 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 10. In order to sufficiently exhibit the above effects, it is necessary to contain 3.5% or more Si. Preferably, it is 3.6% or more.
　On the other hand, when the Si content exceeds 4.5%, the workability is remarkably deteriorated, it is difficult to carry out cold rolling. Therefore, Si content is 4.5% or less. Si content is preferably not more than 4.0%, more preferably not more than 3.9%.
[0027]
[Al: 0.65% or less]
　Al (aluminum) is to reduce the eddy current loss by increasing electrical resistance of the non-oriented electrical steel sheet is an element effective for improving the high-frequency iron loss. On the other hand, Al is a processability in steel sheet production process, the effects of reducing the, and the magnetic flux density of the product. Therefore, the Al content to 0.65% or less.
　In order to obtain good magnetic properties after the core annealing is it is important to suppress the adverse effect of solid solution Ti, if the Al content is high, the TiN without AlN is precipitated as a nitride Te solid solution Ti increases. If the Al content exceeds 0.50%, the magnetic flux density in the non-oriented electrical steel sheet is significantly lowered, it becomes difficult to carry out cold rolling by embrittlement, magnetic properties after the core annealing There becomes inferior. Therefore, considering the magnetic properties after the core annealing, Al content is preferably set to 0.50% or less. Al content is more preferably 0.40% or less, still more preferably not more than 0.35%.
　On the other hand, the lower limit of the Al content is particularly may be 0% does not necessarily correspond to the Al content to less than 0.0005%, the load in the steel is high, the cost is increased. Therefore, Al content is preferably 0.0005% or more. Further, in the case of obtaining the effect of improving the high-frequency iron loss, Al content is preferably not less 0.10% or more, more preferably 0.20% or more.
[0028]
[Mn: 0.2% ~
　2.0%] Mn (manganese) is, by increasing the electrical resistance of the steel to reduce the eddy current loss, which is an element effective for improving the high-frequency iron loss. In order to sufficiently exhibit the above effects, it is necessary to contain 0.2% or more Mn. Also, when the Mn content is less than 0.2%, by fine sulfide (MnS) is deposited, since the grain growth at the time of core annealing is deteriorated, unfavorably. Mn content is preferably 0.4% or more, more preferably 0.5% or more.
　On the other hand, when the Mn content exceeds 2.0%, a reduction in magnetic flux density becomes remarkable. Therefore, Mn content is 2.0% or less. Mn content is preferably not more than 1.7%, more preferably 1.5% or less.
[0029]
[P: 0.005% ~
　0.150%] P (phosphorus) is solid-solution strengthening ability is large, an effect also has an element to increase the advantageous {100} texture on the improvement of the magnetic properties in addition, it is an extremely effective element in order to achieve both high strength and high magnetic flux density. Furthermore, an increase in the {100} texture, so also contribute to reducing the anisotropy of mechanical properties in the plate surface of the non-oriented electrical steel sheet 10, P is punching the non-oriented electrical steel sheet 10 It has the effect of improving the dimensional accuracy of the time. Such strength, magnetic properties and, in order to obtain the effect of improving the dimensional accuracy, it is necessary that the P content is 0.005% or more. P content is preferably 0.010% or more, more preferably 0.020% or more.
　On the other hand, if the P content exceeds 0.150%, the ductility of the non-oriented electrical steel sheet 10 is significantly reduced. Therefore, the P content is 0.150% or less. P content is preferably not 0.100% or less, and more preferably not more than 0.080%.
[0030]
[S: 0.0001% ~
　0.0030%] S (sulfur) is an element to increase the iron loss by forming fine precipitates of MnS, deteriorating the magnetic properties of non-oriented electrical steel sheet 10 . Therefore, S content should be as 0.0030% or less. S content is preferably 0.0020% or less, and more preferably is 0.0010% or less.
　On the other hand, if an attempt is made lower than 0.0001% of S content is only unnecessarily increases costs. Thus, S content is 0.0001% or more. S content is preferably not 0.0003% or more, more preferably 0.0005% or more.
[0031]
[Ti: 0.0030% or less]
　Ti (titanium) is an element that can inevitably mixed in steel, is an element which forms inclusions bound to the carbon and nitrogen (carbides, nitrides). If the carbide is formed, grain growth in the core annealing is inhibited, the magnetic characteristics are deteriorated. Therefore, Ti content is to 0.0030% or less. Ti content is at 0.0015% or less, more preferably it is 0.0010% or less.
　On the other hand, Ti content may be 0%, but if an attempt is made lower than 0.0005%, unnecessarily increase the cost. Therefore, Ti content is preferably set to 0.0005% or more.
[0032]
[Nb: 0.0050% or
　less] Nb (niobium) is an element contributing to strengthening by forming inclusions bound to the carbon and nitrogen (carbides, nitrides). However, Nb is an expensive element, the content is set to 0.0050%. Further, Nb is also an element degrading the magnetic properties by inhibiting the grain growth in the core annealing. Therefore, considering the magnetic properties after the core annealing, Nb content is preferably set to 0.0030% or less. Nb content is preferably not more than 0.0010%, more preferably no measurable (tr.) (Including 0%).
[0033]
[Zr: 0.0030% or
　less] Zr (Zirconium) is an element contributing to strengthening by forming inclusions bound to the carbon and nitrogen (carbides, nitrides). However, Zr is also an element degrading the magnetic properties by inhibiting the grain growth in the core annealing. Accordingly, Zr content is to 0.0030% or less. Zr content is preferably not more than 0.0010%, more preferably no measurable (tr.) (Including 0%).
[0034]
[Mo: 0.030% or
　less] Mo (molybdenum) is an element that can inevitably mixed, is an element which forms inclusions bound to the carbon (carbide). However, Mo is at 750 ° C. or higher temperature such that the core annealing is carried out so easily solution, slight contamination is allowed. However, since the deterioration of the magnetic properties by inhibiting the growth of crystal grains and mixed amount increases too much, Mo content is 0.030% or less. Mo content is preferably not more than 0.020% or, more preferably not more than 0.015%, no measurable (tr.) (Including 0%) may be used.
　On the other hand, if an attempt to reduce the Mo content than 0.0005%, unnecessarily increase the cost. Therefore, from the viewpoint of manufacturing cost, Mo content is preferably set to 0.0005% or more. Mo content is preferably 0.0010% or more.
[0035]
[V: 0.0030% or less]
　V (vanadium) is an element contributing to strengthening by forming inclusions bound to the carbon and nitrogen (carbides, nitrides). However, V is also a element deteriorating magnetic properties by inhibiting the grain growth in the core annealing. Therefore, V content is to 0.0030% or less. V content is preferably not more than 0.0010%, more preferably no measurable (tr.) (Including 0%).
[0036]
[N: 0.0010% ~
　0.0030%] N (nitrogen) is an element inevitably mixed, increasing the iron loss causing magnetic aging, deteriorating the magnetic properties of non-oriented electrical steel sheet 10 is an element to be. Therefore, N content is required to be 0.0030% or less. N content is preferably not more than 0.0025%, and more preferably is 0.0020%.
　On the other hand, if an attempt to reduce the N content than 0.0010%, unnecessarily increase the cost. Therefore, N content is 0.0010% or more.
[0037]
[O: 0.0010% ~
　0.0500%] O (oxygen) is an element inevitably mixed, increasing the iron loss by forming an oxide, magnetic properties of non-oriented electrical steel sheet 10 it is an element that degrades the. Therefore, O content must be less 0.0500%. O Since sometimes mixed in the annealing step, the slab stage (i.e., ladle value) In is preferably set to 0.0050%.
　On the other hand, if the O content to try to reduce than 0.0010%, unnecessarily increase the cost. Therefore, O content is 0.0010% or more.
[0038]
[Cu: less than
0.10%] [Ni: less than
　0.50%] Cu (copper) and Ni (nickel) is an element that can inevitably mixed. Addition of intentional Cu and Ni increases the manufacturing cost of the non-oriented electrical steel sheet 10. Therefore, the non-oriented electrical steel sheet 10 according to the present embodiment, there is no need to add.
　Cu content is less than 0.10% which is the maximum value that can be inevitably mixed in the manufacturing process.
　On the other hand, in particular, Ni is also an element improving the strength of non-oriented electrical steel sheet 10, it may be contained intentionally added. However, since Ni is expensive, even if intentionally contained, the upper limit of its content is less than 0.50%.
　The lower limit of the Cu content and Ni content may be any particular 0% is not limited, when the Cu content and Ni content to try to reduce than 0.005%, unnecessarily increase the cost . Accordingly, the content of Cu content and Ni are both is preferably set to 0.005% or more. Cu content and Ni content is preferably respectively 0.01% or more, or less 0.09%, more preferably, 0.02% or more and 0.06% or less.
[0039]
[Sn:
0% ~ 0.20%] [Sb: 0% ~
　0.20%] Sn (tin) and Sb (antimony), by suppressing the oxidation during segregate to the surface of the steel sheet annealing, low is any additional element useful for securing the iron loss. Thus, in the non-oriented electrical steel sheet according to the present embodiment, in order to obtain the above effect, at least one of Sn or Sb, it may be contained in the base steel as optional additive elements. In order to sufficiently exhibit the above effect, the Sn content or Sb content is preferably set to each 0.01% or more. More preferably, 0.03% or more.
　On the other hand, when the Sn content or Sb content exceeds 0.20%, respectively, there is a possibility that the ductility of the steel matrix is difficult to cold rolling reduction. Accordingly, Sn content or Sb content, even if to be contained, it is preferable to 0.20% respectively less. In case of containing Sn or Sb in the base steel, Sn content or Sb content is more preferably not more than 0.10%.
[0040]
[[C] × ([Ti ] + [Nb] + [Zr] + [V]) <0.000010]
　base iron 11 of the non-oriented electrical steel sheet 10 according to this embodiment, the chemical as described above has the component, the content of C, Ti, Nb, Zr, V of the base steel 11 preferably further satisfying the condition represented by the following formula (1).
[0041]
　[C] × ([Ti] + [Nb] + [Zr] + [V]) <0.000010 ··· (1)
　where, in the formula (1), the notation of [X], elemental the content of X: represents a (unit weight%), i.e., if for example [C], a C content by mass%.
[0042]
　When C is present in the base steel 11, the base steel 11, carbide according to the C content can be formed. Also, as described prior, Ti, Nb, Zr, V is an element which forms carbides with the carbon, the presence of these elements in the base steel 11, tends carbides are more formed Become. Thus, the left side of the equation (1), in the base iron 11 of the non-oriented electrical steel sheet 10 of the present embodiment can be regarded as a indicator of the carbide-forming ability.
[0043]
　The present inventors have, while changing the content of chemical components in the base steel 11, as a result of extensive studies about how the formation of carbides in a base steel 11, is given by the left-hand side of the equation (1) value if the 0.000010 or more, carbides is inhibited the growth of crystal grains in the core annealing by being formed, the magnetic properties after the core annealing revealed that tends to deteriorate. Therefore, the non-oriented electrical steel sheet 10 according to the present embodiment, C, Ti, Nb, Zr, the content and V, the values given in the left-hand side of the equation (1) is made to be less than 0.000010 it is preferable. Value given by the left side of the equation (1) is more preferably at 0.000006 or less, still more preferably 0.000004 or less.
　Value given by the left side of the equation (1) is smaller Preferably, its lower limit is not particularly defined, based on the lower limit of the above elements in the base steel 11 of the present embodiment, 0 value of .00000075 is a substantial lower limit.
[0044]
　Although the chemical components of the steel matrix in the non-oriented electrical steel sheet according to the present embodiment has been described in detail.
　In addition to the above elements, as impurities, Pb, Bi, As, B , Se, Mg, Ca, La, even if elements such as Ce is not included in the range of 0.0001% to 0.0050% present It does not impair the effect of the non-oriented electrical steel sheet according to the embodiment.
[0045]
　When measuring chemical components of the steel matrix 11 in the non-oriented electrical steel sheet 10, it is possible to use various known measuring methods, for example, ICP-MS (Inductively Coupled Plasma Mass Spectrometry) method, or the like appropriate it may be utilized.
[0046]

　in non-oriented electrical steel sheet 10 according to the present embodiment, the average crystal grain size of the base steel 11, have after a finish annealing to be described (core annealing is performed in the following at the time of absence), and has a fine state of 10 [mu] m ~ 40 [mu] m. By average crystal grain size of the base steel 11 is miniaturized in the range of 10 [mu] m ~ 40 [mu] m, it is possible to increase the grain boundary percentage of in the base steel 11, it is possible to produce a strain aging phenomenon .
　Such miniaturized average crystal grain size in the finish annealing step to be described below, after the annealing of a specific annealing temperature and soaking time under certain atmosphere, cooling at a specific cooling rate It is realized by performing. The average crystal grain size of the base steel 11, by changing the heat treatment conditions at the time of finish annealing, it is possible to control.
[0047]
　When the average crystal grain size of the base steel 11 after the finish annealing (state core annealing is not performed) is less than 10μm is set to the maximum value of Si content, and, even when subjected to core annealing, no since iron loss increases, which is one of the important magnetic properties required for grain-oriented electrical steel sheet, which is not preferable.
　On the other hand, when the average crystal grain size of the base steel 11 after the finish annealing (state core annealing is not performed) exceeds 40μm, the result of the average crystal grain size is too large, good strength and required for the rotor since the yield ratio can not be obtained, which is not preferable. The average crystal grain size of the base steel 11 is preferably within the range of 15 [mu] m ~ 30 [mu] m, more preferably in the range of 20 [mu] m ~ 25 [mu] m.
[0048]
　Also, the non-oriented electrical steel sheet 10 according to the present embodiment, when subjected to core annealing performed in manufacturing the stator, and the crystal grain growth of the base steel 11, the average crystal grain size is coarse. This is an element to inhibit the growth of crystal grains C, Ti, Nb, Zr, V content is from being controlled to be within the above range. By performing the core annealing of a predetermined condition, the average crystal grain size of the base steel 11 were coarsened after the core annealing is preferably a 60 [mu] m ~ 150 [mu] m. In the present embodiment, the "core annealing", i.e., an annealing carried out for the purpose of promoting the grain growth grain of the base steel 11.
[0049]
　The predetermined condition of the core annealing, the annealing temperature of 750 ° C.-900 ° C., from a range of soaking time 10 to 180 minutes, conditions are appropriately selected depending on the thickness and the core annealing before particle diameter of the magnetic steel it is. Preferred annealing temperature is 775 ° C.-850 ° C., preferably soaking time is 30 minutes to 150 minutes. Dew point in the annealing atmosphere may be appropriately set depending on the type and performance of the furnace, for example, it may be set within a range of -40 ℃ above 20 ° C. or less. More specifically, for example, in a nitrogen atmosphere having a dew point of -40 ° C., it can be annealing temperature 800 ° C., a soaking time of 120 minutes to.
[0050]
　When the average crystal grain size of the base steel 11 after applying a predetermined core annealing is less than 60μm, even when the maximum value of Si content, a key required for non-oriented electrical steel sheet since iron loss increases, which is one of magnetic characteristics, which is not preferable. Further, when the average crystal grain size of the base steel 11 after applying a predetermined core annealing exceeds 150μm also because the result the iron loss of the grain is too growth increases, undesirably. The average crystal grain size of the base steel 11 after applying a predetermined core annealing is more preferably in the range of 65 .mu.m ~ 120 [mu] m, more preferably in the range of 70 [mu] m ~ 100 [mu] m.
[0051]
　As described above, the non-oriented electrical steel sheet 10 according to the present embodiment, when carrying out the core annealing a predetermined condition, the average crystal grain size of the base steel 11 changes greatly. By utilizing such characteristics, the non-oriented electrical steel sheet 10 according to the present embodiment, it is possible from a single non-oriented electrical steel sheet, to produce both the rotor and the stator, as a result, the yield it is possible to suppress the lowering of.
[0052]
　2, using a non-oriented electrical steel sheet 10 according to this embodiment, is a flowchart illustrating an example of a flow in the case of producing a rotor and a stator.
　As described above, the non-oriented electrical steel sheet 10 according to this embodiment, in the state not subjected to core annealing, the average crystal grain size of the base steel 11 is in the range of 10 [mu] m ~ 40 [mu] m, the crystal grains are fine in the reduction state. Using this non-oriented electrical steel sheet 10, by punching out the shape of the rotor and the stator (step 1), member for producing a rotor and a stator is manufactured. Subsequently, the manufactured rotor member for producing, and the respective stator member for producing, laminated (Step 2). Even after a punching process and laminating process, the average crystal grain size of the base steel 11 in the members are stacked is in the range of 10 [mu] m ~ 40 [mu] m.
[0053]
　As shown in FIG. 2, with a laminated rotor member for producing (without going through the core annealing), the rotor is manufactured. Rotor produced, so that they remain in whatever state the average crystal grain size of the base steel 11 is 10 [mu] m ~ 40 [mu] m and finer, excellent strength required for the rotor (e.g., tensile strength 580MPa or more strength), more It has a high yield ratio (0.82 or higher).
[0054]
　Further, as shown in FIG. 2, with respect to laminated stator member for producing, by performing core annealing (step 3), the stator is manufactured. Non-oriented electrical steel sheet 10 according to this embodiment, the crystal grains grow large base iron 11 by the core annealing, for example, by performing the core annealing predetermined condition becomes within the range of 60 [mu] m ~ 150 [mu] m as described above, excellent it is possible to realize the iron loss and magnetic flux density.
[0055]
　The average crystal grain size of the base steel 11 as described above, for example, with respect to Z section of tissue in the thickness direction center, JIS G0551 - can be determined according to the cutting method of "Steel microscopic examination method of grain size."
[0056]

　The non-oriented electrical steel sheet 10 according to this embodiment has the aforementioned chemical composition, and finish the average crystal grain size of 10μm of the base steel 11 after annealing (in a state where the core annealing is not performed) ~ 40 [mu] m and it is fine. As a result, tensile strength, a 580MPa ~ 700MPa.
[0057]
　Also, the non-oriented electrical steel sheet 10 according to this embodiment, when manufacturing, after annealing of a specific annealing temperature and soaking time under certain atmosphere, to cool at a specific cooling rate. As a result, produce a breakdown phenomenon, it exhibits a upper yield point and lower yield point.
　In the present embodiment, the upper yield point, as the point A in FIG. 3, in a minute strain regions of tensile strength before (left from the position shown tensile strength), stress is defined as a point indicating the maximum value. The lower yield point, is that the stress value is lowered after passing the upper yield point. Since the non-oriented electrical steel sheet less likely is a constant value, as seen in other grades, the lower yield point in this embodiment, as the point B in FIG. 3, between the points showing the tensile strength from the upper yield point in, defined as the point at which stress the minimum value.
[0058]
　In non-oriented electrical steel sheet 10 according to the present exemplary embodiment, the yield ratio is 0.82 or more. By yield ratio is 0.82 or more, the non-oriented electrical steel sheet 10 according to this embodiment, exhibits a more excellent mechanical properties than a rotor. Yield ratio is preferably 0.84 or more. The upper limit of the yield ratio is not particularly defined, but may larger, in fact, approximately 0.90 is the upper limit.
　Also, the non-oriented electrical steel sheet 10 according to this embodiment, and the stress values of the upper yield point (a point in FIG. 3 A), in the difference (Fig. 3 between the stress value under the yield point (a point in FIG. 3 B) delta sigma ) is preferably equal to or greater than 5 MPa. Delta sigma is, if 5MPa or more, 0.82 or more yield ratio is easily obtained.
[0059]
　4, under the under the annealing atmosphere of a steel having a chemical composition as described prior, detailed below, after fixing the soaking time to 20 seconds, when changing the annealing temperature to five in the stress - it illustrates an example of a measurement result of the strain curve.
　77μm The annealing temperature is a final annealing temperature of a general non-oriented electrical steel sheet 950 ° C., when the 1000 ° C., an average crystal grain size of the base steel 11, in the case of 950 ° C. 54 .mu.m, in the case of 1000 ° C. It became. Meanwhile, 800 ° C. The annealing temperature is in the range of finish annealing temperature according to the present embodiment as described in detail below, when a 850 ° C., or 900 ° C., the average crystal grain size of the base steel 11 is, 16 [mu] m in the case of 800 ° C., 25 [mu] m in the case of 850 ° C., became 37μm in the case of 900 ° C..
　The resulting 5 kinds of non-oriented stress of the electromagnetic steel sheets 10 - measurement of the strain curve is as shown in FIG.
[0060]
　As shown in FIG. 4, the average crystal grain size of 16 [mu] m, 25 [mu] m, the stress of the non-oriented electrical steel sheet according to the present embodiment becomes 37 [mu] m - strain curve, so that the upper yield point and lower yield point are observed expressing Do not surrender phenomenon. On the other hand, the stress of the non-oriented electrical steel sheet having an average crystal grain size becomes 54 .mu.m, and 77 m - strain curve does not exist upper yield point and lower yield point.
[0061]
　Tensile strength and yield point as described above, in terms of a specimen was prepared as specified in JIS Z2201, by performing a tensile test by a tensile tester, it is possible to measure.
[0062]

　this embodiment the thickness of the base steel 11 in the non-oriented electrical steel sheet 10 according to the embodiment (may be regarded thickness in FIG. 1 t, product thickness of the non-oriented electrical steel sheet 10 and.) needs to be less than 0.30mm in order to reduce the high-frequency iron loss. 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, or less 0.30 mm. Thickness t of the base steel 11 in the non-oriented electrical steel sheet 10, preferably, 0.15 mm or more and 0.25mm or less.
[0063]

　In non-oriented electrical steel sheet 10 according to the present embodiment, the iron loss W10 / 800 after finish annealing (state core annealing is not performed) is, 50 W / kg less. Iron loss W10 / 800 is preferably not more than 48W / kg, more preferably not more than 45W / kg.
[0064]

　non-oriented electrical steel sheet 10 according to this embodiment is grain base steel 11 by performing predetermined core annealing as described above was grown, better iron loss a is as shown. Non-oriented electrical steel sheet 10 according to this embodiment, the core loss W10 / 400 is preferably equal to or less than 11W / Kg. Iron loss W10 / 400 is more preferably is 10 W / Kg or less. Here, the conditions of core annealing, for example, in a nitrogen atmosphere having a dew point of -40 ° C., can be annealing temperature 800 ° C., a soaking time of 120 minutes to.
[0065]
　Various magnetic properties of non-oriented electrical steel sheet 10 according to this embodiment, Epstein method, defined in JIS C2550, JIS C2556 veneer magnetic property measuring method specified in: conforming to (Single Sheet Tester SST) Te, it is possible to measure.
[0066]

　Returning again to FIG. 1, for it is preferably an insulating film 13 which non-oriented electrical steel sheet 10 of the present embodiment has will be described briefly.
[0067]
　Non-oriented electrical steel sheets are stacked after punched out core blank used. Therefore, by providing the insulating film 13 on the surface of the base steel 11, it is possible to reduce the eddy current between the plates, it is possible to reduce the eddy current loss as a core.
[0068]
　Insulating coating 13 of non-oriented electrical steel sheet 10 according to this embodiment, as long as it is used as an insulating film of non-oriented electrical steel sheet, is not particularly limited, it may be a known insulating film it is. 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 dispersion it is to have insulation 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.
[0069]
　Coating weight of the insulation coating 13 as described above, it is not particularly limited, for example, per side 400 mg / m 2 or more, 1200 mg / m 2 is preferably on the order or less, per one side 800 mg / m 2 or more, 1000 mg / m 2 and more preferably be less. By forming the insulating film 13 so that the deposition amount, it becomes possible to retain good uniformity. When measuring the adhesion amount of the insulating coating 13, it is possible to use various known measuring methods, for example, a method of measuring the mass difference before and after an aqueous solution of sodium hydroxide dipping, using a calibration curve method X-ray fluorescence method and the like may be appropriately used.
[0070]
(Method of manufacturing the non-oriented electrical steel sheet)
　Next, referring to FIG. 5, a method for manufacturing the non-oriented electrical steel sheet 10 according to the present embodiment as described above, it will be described in detail. Figure 5 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.
[0071]
　In the method of manufacturing the non-oriented electrical steel sheet 10 according to this embodiment, with respect to the steel ingot having a predetermined chemical components as described above, hot rolling, hot-rolled sheet annealing, pickling, cold rolling, finish to implement the annealing in 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.
[0072]

　In the method of manufacturing the non-oriented electrical steel sheet 10 according to this embodiment, first, heating a steel ingot (slab) having the above chemical composition, subjected to hot rolling for the heated steel ingot Te to obtain a hot rolled sheet (hot rolled steel) (step S101). The heating temperature of the steel ingot when subjected to hot rolling is not particularly intended to define, for example, 1050 ° C. or higher, it is preferable to 1200 ° C. or less. As for the thickness of the hot rolled 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 1.5 mm ~ 3.0 mm . By hot rolling as described above with respect to the steel ingot is subjected, on the surface of the base steel 11, the scale consisting mainly of oxides of Fe is produced.
[0073]

　After the hot rolling, hot-rolled sheet annealing is performed (step S103). In the hot-rolled sheet annealing, for example, a dew point of -20 ° C. or more annealing atmosphere, and 50 ° C. or less, the annealing temperature 850 ° C. or higher, and 1100 ° C. or less, and the soaking time 10 seconds or more, or less 150 seconds it is preferable that the. Soaking time, the temperature of the hot-rolled sheet is subjected to hot-rolled sheet annealing, it refers to the time that is in the range of peak metal temperature ± 5 ° C..
[0074]
　It is, therefore leading to excessive cost to control the dew point to below -20 ° C., is not preferred. On the other hand, if the dew point is higher than 50 ° C., by advances oxidation of Fe of the base steel, the thickness is excessively reduced by the subsequent pickling, the yield deterioration occurs, which is not preferable. Dew point of the annealing atmosphere is preferably, -10 ° C. or more and 40 ° C. or less, more preferably, -10 ° C. or more and 20 ° C. or less.
[0075]
　If the annealing temperature is below 850 ° C., or, if the soaking time is less than 10 seconds, the magnetic flux density B50 is deteriorated, unfavorably.
　On the other hand, if the annealing temperature exceeds 1100 ° C., or, if the soaking time exceeds 150 seconds, because the possibility that the base steel in the later stage of the cold rolling step results in rupture occurs, which is undesirable.
　Annealing temperature is preferably, 900 ° C. or more and 1050 ° C. or less, more preferably, 950 ° C. or more and 1050 ° C. or less. Also, the soaking time is preferably 20 seconds or more and 100 seconds or less, more preferably, 30 seconds or more, or less 80 seconds.
[0076]
　Further, in the cooling process in the hot-rolled sheet annealing, the cooling process in the hot-rolled sheet annealing, the average cooling rate in the temperature range in order to more surely achieve 0.82 or more yield ratio, up to 800 ° C. ~ 500 ° C. and preferably set to 10 ° C. / sec ~ 100 ° C. / sec, and more preferably set to 25 ° C. / sec or more.
　If the cooling rate in the temperature range up to 800 ° C. ~ 500 ° C. is less than 10 ° C. / sec, strain aging due to solute C can not be obtained sufficiently, it upper yield point is less likely to occur, the yield ratio is reduced . To the average cooling rate is not less than 10 ° C. / sec strong cooling may be accomplished such as by increasing the amount of gas to flow from the rear stage.
　On the other hand, from the viewpoint of mechanical properties, although preferred higher average cooling rate to a sheet temperature 800 ° C. ~ 500 ° C., the productivity when the average cooling rate is too fast the plate shape deteriorates, so impair the steel quality, the upper limit and 100 ℃ / sec.
[0077]

　after the hot rolled sheet annealing is pickled is performed (step S105), the scale layer formed on the surface of the base iron 11 is removed. The concentration of acid used for pickling, the concentration of accelerator used in pickling, pickling conditions such as the temperature of the pickling solution is not particularly limited, may be a known pickling conditions.
[0078]

　After the pickling, cold rolling is performed (step S107).
　In cold rolling, final thickness of the base steel is at a reduction rate such that less 0.30mm or 0.10 mm, pickled plate removed of the scale layer is rolled. By cold rolling, the metal structure of the base steel 11 becomes cold rolled tissue obtained by cold rolling.
[0079]

　After the cold rolling, finish annealing is performed (step S109).
　The method of manufacturing a non-oriented electrical steel sheet according to the present embodiment, the final annealing step is to achieve an average crystal grain size of the base steel 11 as described above, and to produce a breakdown phenomenon, a critical step is there. In recrystallization annealing step, the annealing atmosphere, dew point and wet atmosphere is -20 ° C. ~ 50 ° C., annealing temperature is 750 ° C. or higher, and 900 ° C. or less, soaking time is 10 seconds or more and less than 100 seconds . Soaking time, the temperature of the cold-rolled steel sheet is subjected to finish annealing, it refers to the time that is in the range of peak metal temperature ± 5 ° C.. Perform annealing finish above annealing conditions, by performing cooling as described later, to achieve an average crystal grain size of the base steel 11 as described above, and can give rise to breakdown phenomena.
[0080]
　If the dew point of the annealing atmosphere is less than -20 ° C. is deteriorated grain growth near the surface during the core annealing, since the iron loss becomes inferior undesirable. On the other hand, if the dew point of the annealing atmosphere is more than 50 ° C., since iron loss is deteriorated occurs internal oxidation undesirable. Also, when the annealing temperature is lower than 750 ° C. is too long annealing time, since the productivity is likely to decrease, which is undesirable. On the other hand, if the annealing temperature exceeds 900 ° C., since control of the grain size after finish annealing it becomes difficult unfavorably. Further, when the soaking time is less than 10 seconds it can not provide adequate finish annealing, since it may be difficult to cause an appropriately seed crystal base steel 11, which is not preferable. On the other hand, if the soaking time exceeds 100 seconds, the average crystal grain size of seed crystals caused the base steel 11, since the prior mentioned range and potentially increases, undesirable.
[0081]
　Dew point of the annealing atmosphere is preferably, -10 ° C. or more and 20 ° C. or less, more preferably, 0 ° C. or more and 10 ° C. or less. Further, the oxygen potential of the annealing atmosphere (H 2 partial pressure P of O H2 O to, H 2 partial pressure P of H2 divided by the: P H2 O / P H2 ) is a reducing atmosphere of 0.01 to 0.30 it is preferable.
[0082]
　Annealing temperature is preferably, 800 ° C. or more and 850 ° C. or less, more preferably, 800 ° C. or more and 825 ° C. or less. Soaking time is preferably 10 seconds or more and 30 seconds or less.
[0083]
　Prior mentioned as an average crystal grain size of the base steel 11 of 10 [mu] m ~ 40 [mu] m, and, in order to more surely achieve 0.82 or more yield ratio, the average cooling rate from the sheet temperature is 750 ° C. to 600 ° C. and preferably set to a 25 ° C. / sec or more strong cooling. The cooling rate from the sheet temperature is 400 ° C. to 100 ° C. It is more preferable to slow cooling of 20 ° C. / sec or less at any timing during this period.
　If the cooling rate from the plate temperature 750 ° C. until 600 ° C. is less than 25 ° C. / sec can not cooling rate is sufficiently fine crystal grains of the base steel 11 too late, as described above it may not be able to achieve an average crystal grain size of a 10 [mu] m ~ 40 [mu] m. Further, if the cooling rate from the plate temperature 750 ° C. until 600 ° C. is less than 25 ° C. / sec, caused precipitation of carbides such as TiC in the cooling process, since dissolved C is decreased, solute C strain aging due can not be obtained sufficiently, it upper yield point is less likely to occur, the yield ratio is reduced. On the other hand, the upper limit of the cooling rate from the sheet temperature 750 ° C. to 600 ° C. is not particularly intended to define, in fact, is the upper limit of about 100 ° C. / sec. Cooling rate from the plate temperature 750 ° C. to 600 ° C. preferably at 60 ° C. / sec or less 30 ° C. / sec or more.
　Also, performed between sheet temperature of 100 ° C. from 400 ° C., at least the cooling rate in some temperature interval 20 ° C. / sec or less for slow cooling (including the case where momentary cooling rate is 20 ° C. / sec) it is, progress in strain aging by solute C, the upper yield point is more likely to occur. By performing slow cooling at least part of the temperature zone, it is more preferable that the steel sheet to reside 16 seconds or longer in the temperature range of 400 ℃ ~ 100 ℃.
[0084]
　In the finish annealing, the heating rate up to a sheet temperature 750 ° C. or higher 900 ° C. or less of the temperature range, for example, preferably set to 20 ° C. / sec ~ 1000 ° C. / sec. The heating rate by a 20 ° C. / sec or more, it is possible to the magnetic properties of non-oriented electrical steel sheet with better ones. On the other hand, the heating rate as were raised beyond 1000 ° C. / sec, the effect of improving magnetic properties is saturated. Heating rate in the temperature range of the plate temperature 750 ° C. or higher 900 ° C. or less in the final annealing is more preferably 50 ° C. / sec ~ 200 ° C. / sec.
[0085]
　By going through the steps described above, it is possible to produce a non-oriented electrical steel sheet 10 according to this embodiment.
[0086]

　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.
[0087]
　Surface of the base steel which 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 it may be the surface remains after annealing finish without performing these pre-treatment.
[0088]
　Above with reference to FIG. 5, a method for manufacturing the non-oriented electrical steel sheet according to the present embodiment has been described in detail.
[0089]
(Method of manufacturing the motor core)
　Subsequently, with reference to FIG. 2 again, using the non-oriented electrical steel sheet according to the present embodiment as described above, a method of manufacturing a motor core (rotor / stator), easily explain.
[0090]
　The motor core manufacturing method obtained from non-oriented electrical steel sheet according to the present embodiment, first, the non-oriented electrical steel sheet 10 according to this embodiment, punching the core shape (rotor shape / stator configuration) (Step 1), the resulting respective members are stacked (step 2), to form the desired motor core shape (i.e., the desired rotor shape and the stator shape). For laminating non-oriented electrical steel sheets punched in the core shape, non-oriented electrical steel sheet 10 used in the manufacture of motor core, it is important that the surface of the base steel 11 in which the insulating film 13 is formed.
[0091]
　Thereafter, the non-oriented electromagnetic steel plates laminated in the desired stator shape, annealing (core annealing) is performed (step 3). The core annealing is preferably carried out in an atmosphere containing 70 vol% or more nitrogen. Further, the annealing temperature of the core annealing is preferably 750 ° C. or higher 900 ° C. or less. By implementing the core annealed at above annealing conditions, grain growth proceeds from the recrystallized structure present in the base iron 11 of a non-oriented electrical steel sheet 10. As a result, the resulting stator showing the desirable magnetic properties.
[0092]
　If the proportion of nitrogen in the atmosphere is less than 70% by volume, because increased cost of core annealing, is not preferred. The proportion of nitrogen in the atmosphere is more preferably 80% by volume or more, more preferably from 90 vol% to 100 vol%, particularly preferably 97 vol% to 100 vol%. The atmosphere gas other than nitrogen is not particularly intended to define, in general, can be used hydrogen, carbon dioxide, carbon monoxide, water vapor, a reducing mixed gas consisting of methane. To obtain these gases, a method that may by burning propane gas and natural gas, is generally employed.
[0093]
　Also, when the annealing temperature of the core annealing is less than 750 ° C. can not be achieved sufficient grain growth is undesirable. On the other hand, if the annealing temperature of the core annealing exceeds 900 ° C. is too grain growth of recrystallized structure proceeds, although the hysteresis loss is reduced, since the increased eddy current loss, the total iron loss as a result increases , which is not preferable. Annealing temperature of the core annealing, preferably at 775 ° C. or higher 850 ° C. or less.
[0094]
　Soaking time of implementing the core annealing may be appropriately set according to the annealing temperature, but for example, can be 10 minutes to 180 minutes. If the soaking time is less than 10 minutes is well may not be realized grain growth. On the other hand, if the soaking time exceeds 180 minutes, too long annealing time, is very likely that reduces the productivity. Soaking time, more preferably, from 30 minutes to 150 minutes.
[0095]
　The heating rate in the temperature range of 500 ° C. or higher 750 ° C. or less in the core annealing is preferably set to 50 ℃ / Hr ~ 300 ℃ / Hr. The heating rate With 50 ℃ / Hr ~ 300 ℃ / Hr, is because it is possible to the characteristics of the stator even better ones, the heating rate as were raised beyond 300 ° C. / Hr also, because the effect of improving the properties is saturated. Heating rate in the temperature range of 500 ° C. or higher 750 ° C. or less in the core annealing, more preferably 80 ℃ / Hr ~ 150 ℃ / Hr.
[0096]
　The cooling rate in the temperature range of 750 ° C. or less 500 ° C. or more, preferably set to 50 ℃ / Hr ~ 500 ℃ / Hr. The cooling rate by a 50 ° C. / Hr or more, it is possible to further and better ones properties of the stator, whereas, even if the cooling rate as in excess of 500 ° C. / Hr, the cooling unevenness in inverse distortion due to thermal stress becomes more likely to be introduced into, there is a possibility that the deterioration of the iron loss occurs. Cooling rate in the temperature range of 750 ° C. or less 500 ° C. or higher in the core annealing is more preferably 80 ℃ / Hr ~ 200 ℃ / Hr.
[0097]
　By going through the steps described above, it is possible to manufacture the motor core.
[0098]
　Although the method of manufacturing a motor core according to the present embodiment has been briefly described.
Example
[0099]
　Hereinafter, while showing Examples and Comparative Examples, the non-oriented electrical steel sheet according to the present invention will be specifically described. Examples shown below is only one example of a non-oriented electrical steel sheet according to the present invention, the non-oriented electrical steel sheet according to the present invention is not limited to the following examples.
[0100]
　After heating the slab having the chemical composition shown in Table 1 below to 1150 ° C., finishing temperature 850 ° C., subjected to hot rolling at a finishing thickness 2.0 mm, it was hot-rolled steel sheets and wound up at 650 ° C..
　The obtained hot-rolled steel sheet, in an atmosphere of a dew point of 10 ° C., were hot-rolled sheet annealing of 1000 ° C. × 50 seconds. The average cooling rate of 800 ~ 500 ° C. after the hot rolled sheet annealing, No. 6 is a 7.0 ℃ / sec., And the other was 35 ℃ / sec. After hot band annealing, to remove the scale of the surface by pickling.
　The thus obtained pickled plate (hot-rolled steel sheet after pickling), and a cold rolled steel sheet having a thickness of 0.25mm by cold rolling. Furthermore, hydrogen 10%, 90% nitrogen, a mixed atmosphere having a dew point of 0 ° C., to an average grain size as shown in the following table 2A, Table 2B, finish annealing conditions (annealing temperature and soaking time) and annealed by changing the. Specifically, when the average crystal grain size is controlled to be large, the final annealing temperature higher, and / or it was longer soaking time. Also, when controlling so that the average crystal grain size becomes small, and vice versa.
　Heating rate to a temperature range temperatures higher than 750 ℃ 900 ° C. or less at the time of finish annealing were both 100 ° C. / sec. The cooling rate in the temperature range from 750 ° C. after final annealing to 600 ° C. is, No. 7 and No. 13 only a 10 ° C. / sec, other was 35 ° C. / sec.
　The minimum value of the cooling rate of 400 ~ 100 ° C. at the time of final annealing were as shown in Table 2A, Table 2B. In the invention examples are both the minimum value of the cooling rate in the 400 ~ 100 ° C. is 20 ° C. / sec or less was 400 ~ 100 ° C. The residence time for more than 16 seconds between.
[0101]
　Thereafter, an insulating coating was applied, was non-oriented electrical steel sheet. Insulating coating is acrylic aluminum phosphate and particle size 0.2 [mu] m - an insulating film composed of a styrene copolymer resin emulsion was applied to be a predetermined coating weight, the atmosphere was formed by baking at 350 ° C..
[0102]
　Performing a portion of the resulting non-oriented electrical steel sheet, annealing at 800 ° C. × 120 minutes in a nitrogen atmosphere at a dew point -40 ° C. (the ratio of nitrogen is more than 99.9% by volume in the atmosphere) (processing of the core since not, in this experiment example, simply referred to as "annealing", corresponds to the core annealing. hereinafter referred to as "pseudo-core annealing".) I was subjected to.
[0103]
　Heating rate at less than 700 ° C. 500 ° C. or higher in a pseudo-core annealing, and cooling rate, respectively, 100 ° C. / Hr, and was 100 ° C. / Hr.
[0104]
[Table 1]

[0105]
　The non-oriented electrical steel sheet before and after the pseudo-core annealing, JIS G0551 - according cleavage method of "Steel microscopic examination method of grain size", to observe the tissue Z cross section of the center of plate thickness, the average crystal grain size of the base steel It was measured. Moreover, the non-oriented electrical steel sheet before and after the pseudo-core annealing, were taken Epstein test pieces in the rolling direction and the width direction, by Epstein test conforming to JIS C2550, the magnetic properties (after finish annealing, and, for the previous pseudo core annealing is, iron loss W10 / 800, for after the pseudo core annealing, was to evaluate the iron loss W10 / 400).
　Furthermore, after the finish annealing, and the non-oriented electrical steel sheet before the pseudo core annealing, a tensile test piece in the rolling direction were taken in accordance with JIS Z2241, by performing a tensile test, the yield point, tensile strength (TS), and, the yield ratio was measured. The measured various characteristics as described above, the following table 2A, are summarized in Table 2B.
[0106]
[Table. 2A]

[0107]
[Table 2B]

[0108]
　Table 2A, as is apparent from Table 2B, an invention example No. For 2,4,11,12,15,18,24,25,28,31,32,34,36,37,39 ~ 41 and 45 ~ 47,50,51, proper and annealing conditions finishing with the component because the control in a high yield ratio of 0.82 or more was obtained. Further, each of the upper yield point and lower yield point occurs, the difference between the upper yield point and lower yield point is not less than 5 MPa.
[0109]
　However, No. 18, since the value of "C × (Ti + Nb + Zr + V)" steels C used exceeds the 0.000010, although simulated core properties before annealing is excellent, the average crystal grain size after the pseudo core annealing is small, also, iron loss W10 / 400 is a preferred characteristic by forming carbides, it exceeded 11W / kg.
[0110]
　In addition, No. 24, No. 25, since the Al content exceeds 0.50%, Ti is not fixed as a nitride, as a result, carbide is increased, the iron loss W10 / 400 after a pseudo core annealing exceeds 11W / kg It was.
[0111]
　In addition, No. 28, since the Nb content exceeds 0.0030 mass%, core loss W10 / 400 by the formation of carbides exceeds the 11W / kg.
　In other inventive examples, also in the magnetic properties after simulated core annealing, good results were obtained.
[0112]
　On the other hand, No. 1, the average crystal grain size after finish annealing is because below the 10 [mu] m, the iron loss W10 / 800 after final annealing has exceeded 50 W / kg.
[0113]
　No. About 8 to 10,16,17,26,27,29,30,35,38,43,44,48,49,53,54, average crystal grain size after finish annealing under the influence of such final annealing temperature is 40μm the upper yield point is not generated clear to exceeded, the yield ratio was low.
[0114]
　No. 3,5,14,42,52 the yield ratio is below 0.82. Grain size after finish annealing in these steels were 40μm or less is the upper yield point - lower the lower yield point. Age hardening by carbon for the entire cooling process was quenched over 20 ° C. / sec finish annealing of 400 ° C. ~ 100 ° C. It is believed that did not work sufficiently.
[0115]
　No. 6, the yield ratio is below 0.82. The average cooling rate 800 ~ 500 ° C. After the hot-rolled sheet annealing steel was slow compared to other grades, will be precipitated as carbides solute carbon in the meantime, the strain aging after recrystallization after finish annealing contributes solid solution carbon is considered to have been lost.
[0116]
　No. 7 and 13, the yield ratio is below 0.82. In these steels, a slow cooling than cooling rate and other 600 ° C. from 750 ° C. of finish annealing, considered that the upper yield point is lowered by a carbide starts to precipitate overaging at high temperature It is.
[0117]
　No. For 19-23, upper yield point for the C content was less steels D used does not occur clearly had lower yield ratio.
[0118]
　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
[0119]
　According to the present invention, the manufacturing cost is suppressed, and it is possible to obtain a non-oriented electrical steel sheet more excellent in magnetic properties after mechanical properties and core annealing. Therefore, there is a high availability of the industry.
DESCRIPTION OF SYMBOLS
[0120]
　　10 non-oriented electrical steel sheets
　　11 base steel
　　13 insulation coating

WE CLAIM

[Requested item 1]
　Chemical composition, in
　　mass%, C:
　　0.0015% ~ 0.0040%, Si:
　　3.5% ~ 4.5%, Al: 0.65% or
　　less, Mn: 0.2% ~ 2.0
　　Pasento,
　　Sn:
　　0 Pasento ～ 0.20 Pasento, Sb: 0 Pasento ～ 0.20
　　Pasento, P: 0.005 Pasento ～ 0.150 Pasento, S: 0.0001 Pasento ～ 0.0030
　　Pasento, Ti: 0. 0030% or less,
　　Nb: 0.0050% or
　　less, Zr: 0.0030% or
　　less, Mo: 0.030% or
　　less, V: 0.0030% or
　　less, N: 0.0010% ~
　　0.0030%, O: 0.0010% ~
　　0.0500% Cu: less than
　　0.10% Ni: less than 0.50%,
containing, the balance being Fe and impurities,
　the product plate thickness, 0.10 mm ~ 0.30 mm , and the
　average crystal grain size is 10 [mu] m ~ 40 [mu] m,
　the core loss W10 / 800 is 50 W / Kg It is below,
　Tensile strength is 580 MPa ~ 700 MPa,
　the yield ratio is 0.82 or more,
the non-oriented electrical steel sheet.
[Requested item 2]
　C, Ti, Nb, Zr, content and V, to satisfy the condition represented by the following formula (1), non-oriented electrical steel sheet according to claim 1.
　[C] × ([Ti] + [Nb] + [Zr] + [V]) <0.000010 ··· (1)
　where, in the formula (1), the notation of [X], elemental represents (in weight percent) content of X.
[Requested item 3]
　Annealing temperature 750 ° C. or higher 900 ° C. or less, by annealing at annealing conditions comprised within the range of the soaking time of 10 minutes to 180 minutes, the average crystal grain size is 60 [mu] m-150 [mu] m, and core loss W10 / 400 is , equal to or less than 11W / Kg, non-oriented electrical steel sheet according to claim 1 or 2.
[Requested item 4]
　It comprises an upper yield point and lower yield point, the upper yield point 5MPa or more higher than the lower yield point, non-oriented electrical steel sheet according to any one of claims 1-3.
[Requested item 5]
　The chemical composition, by
　mass%,
　Sn: 0.01% ~ 0.20%, Sb: 0.01% ~ 0.20%,
containing one or both of,
any of claims 1 to 4, non-oriented electrical steel sheet according to any one of claims.
[Requested item 6]
　Further comprising an insulating film on a surface, the non-oriented electrical steel sheet according to any one of claims 1 to 5.