JP5263012B2 - Non-oriented electrical steel sheet and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-oriented electromagnetic steel sheet that can be produced at a low cost with excellent productivity without changing a conventional production process, is excellent in crystal grain growing property at stress relief annealing and shows good high-frequency iron loss, and a method for producing the same. <P>SOLUTION: The non-oriented electromagnetic steel sheet is composed of, by mass, &le;0.01% C, 1.0-3.5% Si, 0.2-3.0% Al, 0.1-2.0% Mn, &le;0.1% P, &le;0.005% S, 0.0015-0.01% Ti, &le;0.005% N, 0.001-0.01% Nd and the balance being iron and unavoidable impurities. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention reduces the iron loss of high-grade non-oriented electrical steel sheets used for high-frequency applications such as motor iron cores, reduces energy loss, contributes to energy efficiency by improving the efficiency of electrical equipment, In particular, the present invention relates to a non-oriented electrical steel sheet excellent in iron loss after strain relief annealing and a method for producing the same.

  In recent years, energy saving has become a major problem from the viewpoint of preventing global warming, and further reduction of power consumption is required in fields such as motors for air conditioning equipment and main motors for electric vehicles. These motors are often used at high speeds. For this reason, the improvement of the iron loss in the 400-800 Hz range of a high frequency is calculated | required with respect to the non-oriented electrical steel plate used as a motor raw material from 50-60 Hz which is the conventional commercial frequency.

  As a measure for improving the iron loss in the high frequency range of the non-oriented electrical steel sheet, for example, as described in Patent Document 1, it has been generally performed to increase the electric resistance by increasing the content of Si or Al. It has been broken.

WO93 / 08313

  Here, with an increase in the amount of Si or Al, a large amount of Ti inevitably contained in the alloy raw material comes to be mixed into the steel sheet. When Ti in the steel sheet increases, Ti generates precipitates such as TiN, TiS, and TiC (hereinafter sometimes referred to as “Ti inclusions”) in the steel sheet. If these precipitates are deposited in a fine and large amount in the steel sheet, the crystal grain growth during the annealing of the steel sheet is pinned to inhibit the crystal grain growth and the magnetic properties are deteriorated. In particular, after the punching process, for example, a measure of strain relief annealing of about 750 ° C. × 2 hours, for example, to grow crystal grains has been selected, but Ti inclusions are formed at grain boundaries during strain relief annealing. Since it is fine and easily precipitates in large quantities, crystal grain growth is remarkably impaired and magnetic properties are greatly deteriorated.

  For this reason, it is necessary to reduce the fine Ti inclusions in the steel plate as much as possible. One of the measures is to use an alloy raw material having a small Ti content as an impurity, but there is a problem that the cost is increased. Reducing N, S, and C in steel is also one of the measures to reduce Ti inclusions, and although it is possible with current technology to sufficiently reduce S and C by vacuum degassing treatment, etc. Processing of time is necessary, and deterioration of productivity is inevitable. In addition, it is conceivable to strengthen the refining vessel seal so that N is not mixed into the molten steel, but this leads to an increase in cost, and even if such measures are taken, mixing of N into the molten steel is unavoidable. There is a problem.

  The present invention can be manufactured with excellent cost and productivity without changing the conventional manufacturing process, excellent crystal grain growth during strain relief annealing, and good non-directionality of high-frequency iron loss. An object of the present invention is to provide an electromagnetic steel sheet and a method for manufacturing the same.

The gist of the present invention is as follows.
(1) By mass%, C: 0.01% or less, Si: 1.0% to 3.5%, Al: 0.2% to 3.0%, Mn: 0.1% to 2. 0% or less, P: 0.1% or less, S: 0.005% or less, Ti: 0.0015% or more and 0.01% or less, N: 0.005% or less, Nd: 0.001% or more. A non-oriented electrical steel sheet comprising 01% or less, the balance being iron and inevitable impurities.
(2) The non-oriented electrical steel sheet according to (1), further comprising at least one of Cu: 0.5% or less or Cr: 20% or less in mass%.
(3) The non-oriented electrical steel sheet according to (1) or (2), characterized in that the total amount of at least one of Sn and Sb is 0.3% by mass or less by mass%.
(4) The non-oriented electrical steel sheet according to any one of (1) to (3), further containing Ni: 1.0% or less in mass%.
(5) By mass%, C: 0.01% or less, Si: 1.0% or more and 3.5% or less, Al: 0.2% or more and 3.0% or less, Mn: 0.1% or more. 0% or less, P: 0.1% or less, S: 0.005% or less, Ti: 0.0015% or more and 0.01% or less, N: 0.005% or less, Nd: 0.001% or more. The molten steel component is adjusted to 01% or less, the slab obtained by casting the molten steel is hot-rolled, and is retained in the range of 1000 ° C. to 1200 ° C. for 10 minutes or more with respect to the obtained hot rolled sheet. A method for producing a non-oriented electrical steel sheet, characterized by performing a heat treatment.
(6) When adjusting the above-mentioned molten steel component, further, by mass%, any one or more of Cu: 0.5% or less or Cr: 20% or less is added to (5) The manufacturing method of the non-oriented electrical steel sheet of description.
(7) When adjusting the above-mentioned molten steel component, it is further characterized by adding 0.3% or less of Sn or Sb as a total amount in an amount of 0.3% or less by mass%. ) Manufacturing method of the non-oriented electrical steel sheet.
(8) When adjusting the molten steel component, the non-directional property according to any one of (5) to (7), wherein Ni: 1.0% or less is further added by mass%. A method for producing electrical steel sheets.

  According to the present invention, the fine Ti inclusions present in the non-oriented electrical steel sheet having a high Si and Al content can be sufficiently suppressed, the crystal grain growth during annealing can be improved, and the iron in the high frequency range can be improved. Non-oriented electrical steel sheets with excellent loss can be manufactured with excellent cost and productivity, and can contribute to energy saving by improving motor characteristics.

The relationship between Nd content in steel and the iron loss value after stress relief annealing is shown.

  The present invention will be specifically described below.

  When Nd is added to a non-oriented electrical steel (hereinafter abbreviated as “steel”), TiS formation in the steel is suppressed, precipitation and growth of TiN are promoted, coarse TiN is generated in the steel, and strain is further increased. TiC in the product plate after pre-annealing is significantly reduced, fine Ti inclusions are reduced by the above, suppression of crystal grain growth by fine Ti inclusions is alleviated, and crystal grain growth is greatly improved. As a result of earnest investigation, it became clear. This will be described in detail below. Nd is an element having an atomic number of 60 and is a kind of lanthanoid.

  A laboratory experiment using vacuum melting was performed, and in mass%, C: 0.01% or less, Si: 1.0% to 3.5%, Al: 0.2% to 3.0%, Mn: 0.1% or more and 2.0% or less, P: 0.1% or less, S: 0.005% or less, Ti: 0.0015% or more and 0.01% or less, N: 0.0004% or more and 0.005 Based on molten steel with a component of less than or equal to%, Nd: Various molten steels with components changed within a range of more than 0% and less than 0.05% are manufactured, solidified, and then hot-rolled and annealed in a laboratory Experiments were carried out in the order of cold rolling, finish annealing and strain relief annealing to produce product samples, and inclusions and crystal grains were investigated by the following method.

  An example of the inclusion investigation method will be described. The sample is polished from the surface to an appropriate thickness to make a mirror surface, and after performing etching described later, a replica is collected, and the inclusions transferred to the replica are subjected to a field emission transmission electron microscope and a field emission scanning electron microscope. Was observed. In the former case, instead of replicas, a thin film may be prepared and observed.

  The etching method is, for example, electrolytic corrosion of a sample in a non-aqueous solvent solution by the method of Kurosawa et al. (Fumio Kurosawa, Isamu Taguchi, Ryutaro Matsumoto: Journal of the Japan Institute of Metals, 43 (1979), p. 1068). The inclusions were extracted by dissolving only steel while leaving

  The crystal grain size was measured by mirror-polishing the cross section of the sample, performing nital etching to reveal crystal grains, and measuring the average crystal grain size.

  As a result, when the product sample contains Nd of 0.001% or more by mass%, the Ti inclusions in the product sample after the strain relief annealing are remarkably reduced, and the crystal grain growth property is greatly improved. As a result of earnest investigation, it became clear. This mechanism will be described in detail below.

  Types of Ti precipitates formed in steel include TiN, TiS and TiC. The temperature at which the precipitation starts is different, TiN is 1000 ° C. or higher, TiS is lower than 1000 ° C., and TiC is precipitated at 800 ° C. or lower. These usually precipitate a large number of fine grain boundaries, dislocations and the like as precipitation sites, and inhibit the grain growth of steel.

  When Nd is added to the steel in an amount exceeding the amount that forms NdS by combining with S, a part of Nd combines with S at the molten steel stage to form NdS. Thereby, S in the steel is fixed as NdS, and formation of sulfides such as TiS and MnS is suppressed.

  The remaining Nd dissolves in the steel. The formation of TiN and TiC in the steel is promoted by the dissolved Nd. Although this mechanism is not clear, it is considered that precipitation and growth of Ti precipitates were promoted by increasing the activity of Ti in the solid solution Nd.

  However, the steel is cooled from a high temperature exceeding 1000 ° C. in hot rolling or the like. At this time, if the formation of Ti precipitates is promoted by the effect of solute Nd, precipitation of TiN that starts precipitation at a higher temperature than TiC. -Growth is promoted and Ti in the steel is consumed by precipitation of TiN. For this reason, if the amount of Ti is 0.01% by mass or less, Ti is almost consumed by the precipitation of TiN, and the remaining Ti is greatly reduced, so that the precipitation of TiC is rather suppressed.

  Thus, it has also been found that the Ti content must be 0.0015% by mass or more in order to promote TiN precipitation / growth.

  That is, when the Ti content is in the range of 0.0015 to 0.01% by mass and the same Ti content is compared, when Nd is added, precipitation and growth of TiN are further promoted, and precipitation and growth of TiS and TiC. Turned out to be more suppressed. At this time, since TiN not only promotes precipitation but also promotes growth, the size of TiN becomes larger and fine TiN disappears, and the pinning effect of crystal grain growth becomes smaller. Is improved.

  Here, the reason why the size of TiN increases is considered as follows. When TiN precipitates with crystal grain boundaries and dislocations as precipitation sites, the number of sites does not change even if Nd is added. Here, when the formation of Ti precipitates is promoted by increasing the activity of Ti, the number of TiN precipitates does not change, and TiN grows more.

  Next, heat treatment for promoting the growth of TiN for further promoting the effect of promoting the precipitation and growth of TiN by Nd will be described. TiN precipitates at 1000 ° C. or higher, but heat treatment at a higher temperature is preferable in order to promote growth more efficiently. However, since problems such as a large amount of scale generation occur in the high temperature range, it has been experimentally found that the temperature range from 1200 ° C. to 1000 ° C. may be maintained for 10 minutes or more.

  By the above mechanism, when the Ti amount is in the range of 0.0015 to 0.01 mass% and Nd is added to the steel in excess of the amount that forms NdS by combining with S, the size of TiN increases, and TiS and TiC are reduced, and the crystal grain growth is improved by reducing the pinning suppression force of the crystal grain growth. At this time, the TiN growth is promoted by increasing the Ti rather than the inevitable impurity level, thereby making the Ti harmless. Thereby, not only hot-rolled sheet annealing or cold-rolled sheet finish annealing, but also the grain growth in each annealing is remarkably improved by suppressing TiC particularly in strain relief annealing.

  Next, the reasons for limiting the components in the present invention will be described.

  [C]: C not only deteriorates the magnetic properties by forming TiC in the steel, but also the magnetic aging due to the precipitation of C becomes remarkable, so the upper limit was made 0.01 mass%. The lower limit includes 0% by mass.

  [Si]: Si is an element that reduces iron loss. If it is less than the lower limit of 1.0% by mass, sufficient low iron loss cannot be obtained. In addition, from a viewpoint of further reducing an iron loss, a preferable minimum is 1.5 mass%, More preferably, it is 2.0 mass%. Further, if the upper limit of 3.5% by mass is exceeded, the workability becomes remarkably poor, so the upper limit was set to 3.5% by mass. A more preferable value as the upper limit is 3.1% by mass with better cold rolling properties, a further preferable value is 3.0% by mass, and a more preferable value is 2.5% by mass.

  [Al]: Al is an element that reduces iron loss in the same manner as Si. If it is less than the lower limit of 0.2% by mass, sufficient low iron loss cannot be obtained. When the upper limit of 3.0% by mass is exceeded, the cost increases remarkably. The lower limit of Al is preferably 0.3% by mass, more preferably 0.4% by mass, and still more preferably 0.5% by mass from the viewpoint of iron loss. The upper limit of Al is preferably 2.5% by mass, more preferably 2.0% by mass, and still more preferably 1.8% by mass from the viewpoint of cost.

  [Mn]: Mn is added in an amount of 0.1% by mass or more in order to increase the hardness of the steel sheet and improve the punchability. The upper limit of 2.0% by mass is due to economic reasons.

  [P]: P increases the strength of the material and improves workability, so that the lower limit exceeds 0% by mass. However, if it is excessive, cold rolling properties are impaired, so 0.1% by mass or less is preferable.

  [S]: S forms TiS or the like, worsens crystal grain growth, and worsens iron loss. Although it is rendered harmless by forming NdS with Nd, when NdS is excessively produced, crystal grain growth is inhibited by NdS. The upper limit for preventing the excessive production of NdS was 0.005% by mass. In addition, a more preferable upper limit is 0.003 mass%. The lower limit includes 0% by mass.

  [N]: N becomes a nitride such as TiN and worsens iron loss. Although detoxified by the present invention, if TiN is excessively produced, TiN cannot be sufficiently grown even after annealing, and fine TiN cannot be eliminated. Therefore, the allowable upper limit is set to 0.005% by mass. The upper limit is preferably 0.003 mass%, more preferably 0.002 mass%. For the above reasons, it is preferable that N is as small as possible. However, since there are large industrial restrictions to make it as close as possible to 0% by mass, the lower limit is made more than 0% by mass. In addition, 0.001 mass% is a standard as a minimum of the denitrification possible in an industrial manufacturing process. Further, in the case of denitrification to the limit, it is more preferable to reduce the content to 0.0005% by mass because the nitride is further suppressed.

  [Ti]: Ti generates fine inclusions such as TiN, TiS, and TiC, thereby worsening crystal grain growth and iron loss. Although Ti inclusions are made harmless by promoting TiN growth by increasing Ti according to the present invention, when TiN is excessively produced, it becomes impossible to sufficiently grow TiN and eliminate fine TiN even after annealing. . Therefore, the allowable upper limit is set to 0.01% by mass. For the above reason, the upper limit is preferably 0.005% by mass. If the amount is less than 0.0015% by mass, the amount of Ti precipitates becomes too small. In order to promote TiN precipitation / growth, the amount of Ti needs to be 0.0015% by mass or more. Further, if the Ti content is less than 0.0015% by mass, the effect of inhibiting the growth of crystal grains is substantially eliminated. From this viewpoint, the lower limit is made 0.0015% by mass.

  Incidentally, since the precipitation and growth of TiN can be promoted as the amount of Ti increases, the lower limit is preferably 0.002% by mass, more preferably 0.0025% by mass, and still more preferably 0.00. 003 mass%.

  [Nd]: Nd is a desulfurization element, which forms NdS in steel and fixes S. Further, Nd added in an amount exceeding the amount of Nd combined with S to form NdS becomes Nd dissolved in the steel, thereby promoting TiN precipitation and growth. This prevents or suppresses the generation of fine TiS and TiC. Even in steel with S of 0.005% by mass or less, when Nd is less than 0.001% by mass, Nd is consumed due to the formation of NdS and there is no sufficient solute Nd. confirmed. Therefore, the effect of Nd is exhibited if the lower limit for producing solute Nd is 0.001% by mass or more. Here, in order to exhibit the effect more, if it is 0.003 mass% or more, it is preferable, and if it exceeds 0.005 mass%, it is more preferable. Moreover, when it exceeds 0.01 mass% as an upper limit, it is unpreferable from a viewpoint of cost. Therefore, it is set as 0.001 mass% or more and 0.01 mass% or less.

  Nd is a kind of lanthanoid consisting of 15 elements from lanthanum having an atomic number of 57 to lutesium having 71, but the above effect is specific to Nd, and other lanthanoid elements are contained in the content. Not included.

  Below, a selective element is demonstrated. In addition, since the lower limit of these content should just be contained even if it is trace amount, it is all over 0 mass%.

  [Cu]: Cu improves corrosion resistance and increases specific resistance to improve iron loss. However, if the amount is excessive, scabs or the like are generated on the surface of the product plate and the surface quality is impaired, so 0.5 mass% or less is preferable.

  [Cr]: Cr improves the corrosion resistance and increases the specific resistance to improve the iron loss. However, excessive addition increases the cost, so 20 mass% was made the upper limit.

  [Sn] and [Sb]: Sn or Sb is a segregating element, which inhibits the texture of the (111) plane that deteriorates the magnetic properties and improves the magnetic properties. Even if these are used alone or in combination of the two, the above-described effects can be exhibited. However, if it exceeds 0.3% by mass, the cold rollability deteriorates, so 0.3% by mass was made the upper limit.

  [Ni]: Ni develops a texture favorable to magnetic properties and improves iron loss. However, excessive addition increases the cost, so 1.0 mass% was made the upper limit.

  In addition, elements other than the components described above may be contained as long as the effects of the steel of the present application are not greatly affected, and are included in the scope of the present invention.

  Inevitable impurities include the following elements.

  [Zr]: Zr inhibits crystal grain growth even in a small amount, and worsens iron loss after strain relief annealing. Therefore, it is preferable to reduce it as much as possible to 0.01% by mass or less.

  [V]: V forms nitrides or carbides and inhibits domain wall movement and crystal grain growth. For this reason, it is preferable to set it as 0.01 mass% or less.

  [Mg]: Mg is a desulfurization element, reacts with S in steel to form sulfide, and fixes S. If the content is increased, the desulfurization effect is enhanced, but if the upper limit of 0.05% by mass is exceeded, crystal grain growth is hindered by excessive Mg sulfide. Therefore, it is preferable to set it as 0.05 mass% or less.

  [O]: When O is contained in an amount of more than 0.005% by mass, a large number of oxides are generated, and domain wall movement and crystal grain growth are inhibited by the oxides. Therefore, it is preferable to set it as 0.005 mass% or less.

  [B]: B is a grain boundary segregation element and forms a nitride. Grain boundary movement is hindered by this nitride, and iron loss deteriorates. Therefore, it is preferable to reduce as much as possible to 0.005 mass% or less.

  Next, preferable manufacturing conditions and the reason for the definition in the present invention will be described.

  In the steelmaking stage, it is refined by conventional methods such as converters and secondary refining furnaces, melted within the desired composition range, the molten steel is taken into a ladle, poured into a mold through a tundish, and continuously cast or ingot A slab or other slab is cast by casting.

  Thereafter, the product is further hot-rolled and subjected to one or more cold rollings with intermediate annealing and pickling treatment as necessary to finish the product. At that time, in order to obtain the non-oriented electrical steel sheet of the present invention, after hot rolling or before cold rolling, TiN in the steel is grown for 10 minutes in the range of 1200 ° C to 1000 ° C. It is important to perform the above heat treatment. Next, finish annealing is performed and an insulating film is applied.

  By the method described above, Ti inclusions in the steel sheet can be controlled.

Below, the effect of the present invention is explained based on an example.
Example 1
% By mass, C: 0.0019%, Si: 2.5%, Mn: 0.3%, P: 0.05%, N: 0.0025%, Al: 1.2%, and Table 1 It consists of various elements shown in the figure, and the remainder is composed of iron and inevitable impurities. The refined steel is refined by a converter and vacuum degassing equipment, and the metal Nd is added to the molten steel and received in the ladle. The molten steel was supplied into the mold by an immersion nozzle and continuously cast to obtain a slab. Thereafter, the slab is hot rolled, heat treatment at 1050 ° C. for 15 minutes is performed in a batch furnace, cold rolled to a thickness of 0.35 mm, finish annealing at 950 ° C. for 30 seconds, an insulating film is applied, The product was obtained by performing strain relief annealing at 750 ° C. for 2 hours. The precipitates and crystal grain size of the product plate were investigated by the above method, and the iron loss of the product plate was examined by the Epstein method shown in JIS-C-2550 after cutting the product plate into 25 cm length. Here, since it was observed that precipitates having a diameter of 50 nm or less pinned the grain boundaries, attention was paid to the existence of precipitates having a diameter of 50 nm or less.

The results are shown in Table 1 and FIG. In Nos. 1 to 5 according to the present invention, fine TiN, TiS and TiC having a diameter of 50 nm or less were not observed in the product plate. The crystal grains grew relatively coarse and the iron loss value was good. On the other hand, No. 6 in the comparative example is an example in which Nd was not added, and No. 7 was an example in which the amount of Nd added was below the range of the present invention. The size of the TiC film was small and precipitation of TiC was observed. Further, TiS was observed in No. 6 to which Nd was not added, and the crystal grain growth and iron loss values were inferior to those of the inventive examples. Comparative Example No. 8 is an example in which the amount of S in the steel exceeds the upper limit of the range of the present invention, but S fixation by Nd is insufficient, TiS precipitates, and the grain growth and iron loss values are in the invention example. It was inferior in comparison. Furthermore, No. 9 of the comparative example is an example in which the amount of Ti in the steel exceeds the upper limit of the range of the present invention. The grain growth and iron loss values were inferior to those of the inventive examples.
(Example 2)
In mass%, C: 0.0015%, Si: 3.0%, Mn: 0.4%, P: 0.1%, S: 0.0021%, Al: 0.6%, Ti: 0.00. 002%, N: 0.0022%, Nd: 0.0035%, the remainder of the steel composed of iron and inevitable impurities was melted by a high-frequency vacuum melting device and injected into a mold to obtain an ingot . Thereafter, the ingot was hot-rolled and subjected to various annealing treatments shown in Table 2 on the hot-rolled sheet, and then cold-rolled to a thickness of 0.35 mm and subjected to finish annealing at 950 ° C. × 30 seconds to obtain a steel plate sample. The precipitates on the product plate and the crystal grain size were investigated by the method described above.

  The results are shown in Table 2. In Nos. 1 to 4 according to the present invention, relatively coarse TiN having an average diameter of 65 to 80 nm was found in the product plate, and the crystal grain size was sufficiently grown to 115 to 130 μm. In addition, scale wrinkles did not occur on the surface of the product plate. On the other hand, No. 5, which has an annealing temperature of 1250 ° C., which exceeds the range of the present invention, has a relatively coarse TiN average diameter of 105 nm and a crystal grain size of 140 μm. Many indentations of the scale occurred on the surface of the product, which was not possible as a product. No. 6 is an annealing time, No. 7 is an annealing temperature, and No. 8 is an example in which the annealing temperature and time are below the range of the present invention, both of which have an average diameter of TiN in the product plate. The crystal grain size was 80 to 90 μm, which was relatively inferior to the examples of the present invention.

  As explained above, by sufficiently suppressing the fine Ti precipitates contained in the non-oriented electrical steel sheet, it becomes possible to obtain sufficiently good magnetic properties, which can contribute to energy saving while satisfying customer needs. .

Claims (8)

  In mass%, C: 0.01% or less, Si: 1.0% or more and 3.5% or less, Al: 0.2% or more and 3.0% or less, Mn: 0.1% or more and 2.0% or less P: 0.1% or less, S: 0.005% or less, Ti: 0.0015% or more and 0.01% or less, N: 0.005% or less, Nd: 0.001% or more and 0.01% or less A non-oriented electrical steel sheet, characterized in that the balance is iron and inevitable impurities.   The non-oriented electrical steel sheet according to claim 1, further comprising at least one of Cu: 0.5% or less or Cr: 20% or less in mass%.   3. The non-oriented electrical steel sheet according to claim 1, wherein the non-oriented electrical steel sheet according to claim 1, further comprising 0.3% or less of a total amount of at least one of Sn and Sb.   The non-oriented electrical steel sheet according to any one of claims 1 to 3, further comprising Ni: 1.0% or less in mass%.   In mass%, C: 0.01% or less, Si: 1.0% or more and 3.5% or less, Al: 0.2% or more and 3.0% or less, Mn: 0.1% or more and 2.0% or less P: 0.1% or less, S: 0.005% or less, Ti: 0.0015% or more and 0.01% or less, N: 0.005% or less, Nd: 0.001% or more and 0.01% or less The molten steel component is adjusted to the above, the slab obtained by casting the molten steel is hot-rolled, and the obtained hot-rolled sheet is subjected to a heat treatment for holding in the range of 1000 ° C. to 1200 ° C. for 10 minutes or more. The manufacturing method of the non-oriented electrical steel sheet characterized by the above-mentioned.   When adjusting the molten steel component, at least one of Cu: 0.5% or less or Cr: 20% or less is added by mass%. A method for producing grain-oriented electrical steel sheets.   When adjusting the said molten steel component, 0.3% or less of Sn or Sb 1 type or 2 types is further added with the total amount by the mass%, The nothing of Claim 5 or 6 characterized by the above-mentioned. A method for producing grain-oriented electrical steel sheets.   The method for producing a non-oriented electrical steel sheet according to any one of claims 5 to 7, further comprising adding Ni: 1.0% or less in mass% when adjusting the molten steel component. .

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