JP2016151063A - Nonoriented magnetic steel sheet and production method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonoriented magnetic steel sheet combining low iron loss with high magnetic flux density at a high level, and a production method therefor.SOLUTION: The nonoriented magnetic steel sheet is provided that contains, by mass%, Si:1.7% to 3.5%, Al:0.1% to 2.0% and Mn:0.08% or more and less than 1.5% in a range satisfying Si+2×Al-Mn≥2.0 and further P:over 0.03% and 0.15% or less, Sn:0.03% to 0.15%, C:0.005% or less, S:0.0040% or less, N:0.005% or less and Mo:0.002% to 0.2% and the balance Fe with inevitable impurities. In the nonoriented magnetic steel sheet, having strength of φ1=20° and Φ=15° of φ2=0° cross section in a crystal orientation distribution function is 5 or more at a sheet thickness 1/4 position after final annealing.SELECTED DRAWING: None

Description

  The present invention relates to a non-oriented electrical steel sheet and a method for producing the same. More specifically, the present invention provides high energy efficiency, small size, and high output, such as a drive motor mounted on a hybrid vehicle, an electric vehicle, and a fuel cell vehicle, and a small generator mounted on a motorcycle and a home cogeneration system. The present invention relates to a non-oriented electrical steel sheet suitable for a material for an iron core of an electrical device and a method for manufacturing the same.

  Due to the recent increase in global environmental problems, electrical equipment is required to be small, high power, and high energy efficiency, and non-oriented electrical steel sheets, which are core materials, are strongly required to have both low iron loss and high magnetic flux density. ing.

  Conventionally, as a means for reducing iron loss, an increase in the content of Si or Al, a higher purity, and a thinner plate thickness have been employed. Among the means for reducing iron loss, the most effective way to reduce iron loss in the high frequency range is to reduce the thickness of the plate, and there is a strong demand for low iron loss typified by drive motors for hybrid and electric vehicles. A thin non-oriented electrical steel sheet having a thickness of 0.35 mm or less is used for applications.

  Further, recrystallization texture control has been adopted as means for increasing the magnetic flux density. The basis of recrystallization texture control is to reduce the {111} plane that does not include the easy axis in the plate surface and increase the {110} plane and {100} plane that include the easy axis in the plate surface. Regarding the increase in the degree of integration of the {100} <001> orientation having two easy magnetization axes in the plate surface and the {110} <001> orientation in which the easy magnetization axes are aligned in one direction within the plate surface, two methods are used. Active investigations have been made not only in the field of grain-oriented electrical steel sheets and unidirectional electrical steel sheets, but also in the field of non-oriented electrical steel sheets.

For example, as a technique for increasing the degree of integration of {100} <001> orientation and {110} <001> orientation in a non-oriented electrical steel sheet, the following method has been proposed.
Patent Document 1 and Patent Document 2 describe a method of developing {100} <001> orientation by utilizing {510} <001> orientation accumulated under special hot rolling conditions, and Patent Document 3 describes hot processing. A method of accumulating in the {100} <001> orientation by rolling has been proposed. Patent Document 4 proposes a steel plate in which Al: 0.02% by mass or less and accumulated in the {100} <001> orientation.
The above is an example in which the recrystallized texture is controlled under relatively special conditions. In addition, Patent Document 5 proposes a method of developing the {100} <001> orientation in a non-oriented electrical steel sheet containing P. Has been. Patent Document 6 proposes a technique for improving the magnetic flux density by making steel containing Sn or Sb alone or in combination by annealing a hot-rolled sheet to a crystal grain size of 300 to 2000 μm. As a high-frequency non-oriented electrical steel sheet by reducing the thickness, Patent Document 7 proposes a non-oriented electrical steel sheet containing at least one of Sn and Sb and having a thickness of 0.1 to 0.3 mm.

JP 2000-160248 A JP 2000-160249 A Japanese Patent Laid-Open No. 10-226854 JP 2001-181803 A JP 2012-36454 A JP 2004-218036 A JP 2000-160303 A

  As described above, various studies have been made on the recrystallization texture control of non-oriented electrical steel sheets. However, reducing the sheet thickness for the purpose of reducing iron loss requires an increase in the cold rolling reduction ratio, and with the increase in the cold rolling reduction ratio, an unfavorable orientation is developed for improving magnetic properties. Therefore, it is difficult to achieve both the reduction in thickness and the recrystallization texture control aiming at high magnetic flux density. For this reason, the request | requirement of making low iron loss and high magnetic flux density compatible on a high dimension was not fully satisfied. Moreover, the control of the recrystallized texture under special conditions led to an increase in cost and was not practical.

  That is, the non-oriented electrical steel sheet described in Patent Documents 1 to 3 has a hot-rolling finish thickness of 0.8 mm as described in the examples, and has a large equipment load. In addition, productivity is significantly reduced. For this reason, it is not easy to apply to actual operation.

  The non-oriented electrical steel sheet described in Patent Document 4 is a steel sheet obtained by secondary recrystallization annealing in the same manner as the unidirectional electrical steel sheet, and a significant increase in production cost compared to a normal non-oriented electrical steel sheet. I cannot deny.

  Although the non-oriented electrical steel sheet described in Patent Document 5 does not require a special process, it contains a large amount of P. Therefore, steel with an increased Si content for the purpose of reducing iron loss, If the grain size before cold rolling is increased for the purpose of increasing the magnetic flux density, there is concern about cracking during cold rolling, and there is room for improvement in order to achieve both high iron loss and high magnetic flux density. There is. Moreover, although the method of finishing to a desired sheet thickness by two cold rollings with intermediate annealing interposed therebetween has an effect of suppressing cracks during cold rolling, there is a concern about an increase in cost due to an increase in processes.

  The technique described in Patent Document 6 is a technique for increasing the magnetic flux density by increasing the crystal grain size before cold rolling, but when applied to a thin plate material for the purpose of reducing iron loss, There is concern about the occurrence of cracks in rolling. The technique described in Patent Document 7 is intended to reduce iron loss by suppressing nitridation of the surface layer, but there is room for improvement from the viewpoint of magnetic flux density.

  This invention is made | formed in view of the said situation, The subject enjoys the effect of the high magnetic flux density increase by P and Sn to the maximum, and suppresses the crack at the time of cold rolling to be worried about. Another object of the present invention is to provide a non-oriented electrical steel sheet that achieves both low iron loss and high magnetic flux density at a high level without passing through a special process, and a method for producing the same.

  The inventors of the present invention first conducted intensive research on a method for increasing the magnetic flux density of a non-oriented electrical steel sheet, particularly a magnetic flux density in a thin plate material. As a result, it has been found that the magnetic flux density is increased by containing an appropriate amount of P. Moreover, the result that a magnetic flux density further increased by containing P and Sn in a composite was obtained. However, depending on the P content, cracks during cold rolling are induced, and when P and Sn are combined, there are concerns about cracks during cold rolling. We studied to suppress it. As a result, it has been found that by containing an appropriate amount of Mo, the effect of increasing the magnetic flux density by P and Sn can be enjoyed and cracking during cold rolling can be suppressed. The gist of the present invention based on such new findings is as follows.

That is, the present invention includes, in mass%, Si: 1.7% to 3.5%, Al: 0.1% to 2.0%, and Mn: 0.08% to less than 1.5%. It contains in the range which satisfies Formula (1), Furthermore, P: more than 0.03% 0.15% or less, Sn: 0.03% or more and 0.15% or less, C: 0.005% or less, S: 0.0040% or less, N: 0.005% or less, and Mo: 0.002% or more and 0.2% or less, with the balance being Fe and impurities, at a thickness of 1/4 position after finish annealing The non-oriented electrical steel sheet is characterized in that the strength of φ1 = 20 ° and φ = 15 ° of φ2 = 0 ° section in the crystal orientation distribution function is 5 or more.
Si + 2 × Al-Mn ≧ 2.0 (1)
(Here, Si, Al, and Mn indicate the content (unit: mass%) of each element.)

  In the present invention, since the steel composition is optimized, especially containing an appropriate amount of Mo, the effect of increasing the magnetic flux density by P and Sn is enjoyed, and cracking during cold rolling is suppressed. Can do.

  The non-oriented electrical steel sheet of the present invention preferably has a thickness of 0.10 to 0.25 mm. This is because the iron loss is reduced by reducing the plate thickness, and the magnetic flux density is increased even by a thin material having a high cold rolling reduction ratio due to the effect of the present invention, so that both low iron loss and high magnetic flux density are achieved.

  The present invention also includes a hot rolling process in which hot rolling is performed on a steel ingot or steel slab having the above-described steel composition, and a hot rolled sheet annealing process in which the hot rolled steel sheet obtained by the hot rolling process is annealed. And a cold rolling process in which cold rolling is performed on the steel sheet obtained by the hot rolled sheet annealing process, and a finish annealing process in which finish annealing is performed on the cold rolled steel sheet obtained by the cold rolling process. In the method of manufacturing grain-oriented electrical steel sheet, hot-rolled sheet annealing is maintained at 950 ° C. or higher and 1050 ° C. or lower for 10 seconds or longer and 3 minutes or shorter, and the total rolling reduction in cold rolling is 88% or higher and 96% or lower, and finish annealing is performed. Provided is a method for producing a non-oriented electrical steel sheet, which is performed at 950 ° C. to 1050 ° C. for 10 seconds to 120 seconds.

  The present invention also relates to the above-described method for producing a non-oriented electrical steel sheet, wherein hot-rolled sheet annealing is maintained at 950 ° C. or higher and 1050 ° C. or lower for 10 seconds or longer and 3 minutes or shorter, and then at 800 ° C. or higher and 920 ° C. or lower for 10 seconds or longer 2 The present invention provides a method for producing a non-oriented electrical steel sheet, which is carried out by continuous annealing that is maintained for a minute or less.

  The present invention also provides a method for producing a non-oriented electrical steel sheet, characterized in that, in the above-described method for producing a non-oriented electrical steel sheet, a finish plate thickness in cold rolling is set to 0.10 to 0.25 mm. To do.

  In the present invention, it is possible to suppress breakage during cold rolling while enjoying the effect of increasing the magnetic flux density due to P and P and Sn, so that a non-oriented electrical steel sheet that achieves both low iron loss and high magnetic flux density at a high level is obtained. There is an effect that can be.

It is a figure which shows the relationship between P content and magnetic flux density. It is a figure which shows the relationship between P content and magnetic flux density. It is a figure which compares the result of a Charpy impact test.

  As a result of intensive studies on a method for increasing the magnetic flux density of a non-oriented electrical steel sheet, the present inventors have found that the magnetic flux density is increased by containing an appropriate amount of P. Moreover, the result that the magnetic flux density was further increased by including P and Sn in a composite manner was obtained, and the knowledge that the effect of the thin plate material was greater was obtained. However, depending on the contents of P and Sn, cracks during cold rolling are induced when they are contained in a complex manner. Therefore, studies were made to suppress this. As a result, it has been found that by containing an appropriate amount of Mo, the effect of increasing the magnetic flux density by P and Sn can be enjoyed and cracking during cold rolling can be suppressed. Hereinafter, the details will be described based on the experimental results.

  Steel containing, as a basic component, Si: 2.5%, Al: 1.1%, Mn: 0.2% in a vacuum melting furnace, and P in a range of 0.01 to 0.12% Steels F to J containing 0.01 to 0.12% of A to E and P and 0.05% of Sn were produced. At this time, the C amount is 0.002 to 0.003%, the S amount is 0.002 to 0.003%, the N amount is 0.0015 to 0.002%, and Mo is in the range of 0.002 to 0.005%. Met. Each steel was finished to a plate thickness of 2.0 mm by hot rolling, and then subjected to hot-rolled plate annealing held at 1000 ° C. for 90 seconds, and finished to a plate thickness: 0.15 mm by cold rolling. Then, the finish annealing which hold | maintains at 1000 degreeC for 15 second was given, the magnetic flux density B50 of a rolling direction and a rolling orthogonal direction was measured with the 55 mm square single-sheet test piece, and it evaluated by the average value.

  As shown in FIG. 1, the magnetic flux density is improved as the P content is increased, but it has been found that the magnetic flux density is further improved by containing P and Sn in a composite manner. The reason why the magnetic flux density is improved by compounding P and Sn is not clear, but Sn is also an element having a strong tendency to segregate at the grain boundaries as in the case of P. Therefore, grain boundaries are segregated by grain boundary segregation before cold rolling. It is presumed that non-uniform deformation is promoted by changing the deformation restraining force at, and recrystallization in a preferred orientation is promoted for improving magnetic properties. Further, P and Sn dissolved in the grains also contribute to the non-uniform deformation, and it is presumed that the mechanism is different between P and Sn, and it is considered that an effect exceeding the single addition was obtained by the composite addition.

  Furthermore, the steel sheet after hot-rolled sheet annealing of the steels F to J described above is finished to a thickness of 0.15 to 0.35 mm by cold rolling, and finish annealing is performed for 15 seconds at 1000 ° C. The magnetic flux density B50 was measured every 22.5 ° from the rolling direction with a single plate test piece, and the magnetic flux density was evaluated by the average value.

  As shown in FIG. 2, the magnetic flux density is improved as the P content is increased, and the effect is greater in the case of a thin sheet material having a high cold rolling reduction ratio. In addition to the average value of the magnetic flux density in the rolling direction and the direction perpendicular to the rolling shown in FIG. 1, the average value of the magnetic flux density every 22.5 °, that is, the average magnetic flux density in the plate surface is improved as the P content increases. The reason for this corresponds to the development of an orientation close to the {100} plane, and as a result of intensive investigations by the inventors of the present invention, it is shown that φ1 = 20 ° and φ = 15 ° of the φ2 = 0 ° cross section after finish annealing. The development of the orientation was confirmed.

  Next, in a vacuum melting furnace, Si: 2.0%, Al: 0.8%, Mn: 0.2%, Sn: 0.05% are contained as basic components in mass%, and the Mo content is 0.00. Steel L with less than 002%, P content 0.01%, Mo content less than 0.002%, Steel M with P content 0.14%, Mo content 0.1%, P content Produced 0.14% of steel N. At this time, the C content was 0.002 to 0.003%, the S content was 0.002 to 0.003%, and the N content was 0.0015 to 0.002%. Each steel was finished to a thickness of 2.0 mm by hot rolling, and then subjected to hot rolling annealing at 1000 ° C. for 90 seconds. Then, in order to evaluate cold rolling property, it used for the Charpy impact test. The results are shown in FIG.

  As shown in FIG. 3, the transition temperature rises as the P content increases, but decreases as Mo is contained. That is, it has been found that the increase in the P content and embrittlement due to the combined inclusion of P and Sn are alleviated by Mo, and the fracture during cold rolling is suppressed. Furthermore, as a result of investigating the influence of Mo on the magnetic properties of steel containing P, and steel containing P and Sn in combination, when Mo is excessively contained, the magnetic flux density is improved by P and Sn. It was found that the effect was reduced. Although the reason for this is not clear, the effect of P and Sn segregated at the grain boundary on the recrystallized texture is weakened as a result of the change in the grain boundary bonding force by Mo, and a recrystallized texture preferable for improving magnetic properties cannot be obtained. Inferred. From these results, it was found that by controlling the Mo content in an appropriate range, the effect of increasing the magnetic flux density by P and Sn was enjoyed and cracking during cold rolling was suppressed. Furthermore, in steel with the Mo content controlled to an appropriate range, it is found that by performing hot-rolled sheet annealing under appropriate conditions, the effect of increasing the magnetic flux density is enhanced and cracking during cold rolling is also suppressed. The present invention has been completed.

  Hereinafter, the non-oriented electrical steel sheet of the present invention based on such new knowledge and the manufacturing method thereof will be described in detail.

A. Non-oriented electrical steel sheet The non-oriented electrical steel sheet of the present invention is, in mass%, Si: 1.7% to 3.5%, Al: 0.1% to 2.0%, and Mn: 0.08. % And less than 1.5% in a range satisfying the above formula (1), P: more than 0.03% 0.15% or less, Sn: 0.15% or less, C: 0.005% Hereinafter, S: 0.0040% or less, N: 0.005% or less and Mo: 0.002% or more and 0.2% or less, with the balance being Fe and impurities, the thickness 1 / after finish annealing The non-oriented electrical steel sheet is characterized in that the strength of φ1 = 20 ° and φ = 15 ° in the φ2 = 0 ° cross section at 5 positions is 5 or more.

  Hereafter, each structure in the non-oriented electrical steel sheet of this invention is demonstrated in detail.

1. Chemical composition (1) Si, Al, Mn
Si, Al, and Mn have the effect of increasing the electrical resistance, so they are included for reducing iron loss. However, when it is excessively contained, the magnetic flux density is remarkably lowered. Furthermore, if Si is contained excessively, even if it has the effect of Mo described later, there is a possibility of breaking during cold rolling. Further, if Mn is contained excessively, austenite transformation occurs and it becomes difficult to ensure magnetic properties. The upper limit of each element is determined from these viewpoints, and the Si content is 3.5% or less, the Al content is 2.0% or less, and the Mn content is less than 1.5%.
The lower limit of the Si content is set to 1.7% or more from the viewpoint of increasing the electric resistance and securing a desired iron loss level. If the Al content is less than 0.1%, the movement of the domain wall is inhibited by fine nitride, and the grain growth may be inhibited to deteriorate the magnetic characteristics. Therefore, the Al content is 0.1% or more. When the Mn content is less than 0.08%, the movement of the domain wall is inhibited due to the refinement of the sulfide, and the grain growth is inhibited and the magnetic characteristics may be deteriorated. Therefore, the Mn content is 0.08% or more.

Here, in the case of steel having a ferrite-austenite transformation, the annealing temperature is restricted in order to make the finish annealing a ferrite region annealing, and as a result, it may be difficult to ensure a desired iron loss level. Therefore, Si + 2 × Al—Mn is adopted as an index for the ferrite-austenite transformation, and the following formula (1) is satisfied in order to obtain a steel having no transformation.
Si + 2 × Al-Mn ≧ 2.0 (1)
Here, Si, Al, and Mn indicate the content (unit: mass%) of each element.

(2) P
P has an effect of improving magnetic properties, particularly magnetic flux density, and is an extremely important element in the present invention. From the viewpoint of obtaining a clear effect of increasing the magnetic flux density, the P content is more than 0.03%. On the other hand, if the P content exceeds 0.15%, there is a possibility that breakage may occur during cold rolling even with the effect of Mo described later. Therefore, the P content is 0.15% or less.

(3) C
C is contained as an impurity, and when the content exceeds 0.005%, fine carbides are precipitated and the magnetic properties are deteriorated. Therefore, the C content is 0.005% or less.

(4) S
When S is contained in a large amount, a large amount of sulfide precipitates and the magnetic properties deteriorate. Therefore, the upper limit is set to 0.004%. Preferably it is 0.002% or less.

(5) N
N is contained as an impurity, and when it is contained in a large amount, the magnetic properties deteriorate due to an increase in nitride. Therefore, the upper limit is set to 0.005%.

(6) Mo
Mo has an effect of suppressing a decrease in cold rollability when P, P, and Sn are combined, that is, cracking during cold rolling. However, when the content is 0.2% or more, the effect of increasing the magnetic flux density is reduced. In addition, precipitates may be formed to adversely affect the magnetic properties. The range of the Mo content is determined from these viewpoints and is set to 0.002% or more and 0.2%. A preferable upper limit is 0.1%.

(7) Sn
Sn has the effect of improving the magnetic flux density by being combined with P. However, if it is excessively contained, the grain growth property may be lowered. When hot-rolled sheet annealing is performed in a box-annealing mold, the grain growth drop during hot-rolled sheet annealing due to an increase in Sn content is significant, but the effect is favorable under the preferred hot-rolled sheet annealing conditions of the present invention. Small, Sn content is allowed up to more. In this respect, the content is made 0.15% or less. The lower limit of the content is determined from the viewpoint of improving the magnetic flux density, and is 0.03% or more, preferably 0.04% or more.

(8) Remainder The remainder is Fe and impurities. Of impurities, Ti, V, Nb, and Zr, which adversely affect grain growth, are desirably reduced as much as possible, and each is preferably 0.01% or less. Moreover, you may contain at least 1 sort (s) selected from the group which consists of Ca, Mg, and REM for the purpose of the magnetic characteristic improvement by the form control of sulfide. Here, REM refers to a total of 17 elements of 15 elements having atomic numbers 57 to 71 and 2 elements of Sc and Y. When these elements are contained, the content of each element is preferably Ca: 0.03% or less, Mg: 0.02% or less, and REM: 0.1% or less. In order to reliably obtain the above effects, the content of each element is preferably set to Ca: 0.0001% or more, Mg: 0.0001% or more, and REM: 0.0001% or more. Further, in the present invention, since it is important to improve the cold rolling property, 0.15% or less is preferable for Cu that changes the surface properties of the rolling base material.

2. Texture From the viewpoint of improving the magnetic flux density of the thin plate material, it is important to develop not only the {111} plane but also the {100} plane or an orientation close thereto. The non-oriented electrical steel sheet of the present invention is characterized by the development of the orientation of φ1 = 20 ° and φ = 15 ° of the φ2 = 0 ° section in the crystal orientation distribution function (ODF) as the orientation for improving the magnetic flux density. From the viewpoint of improving the density, the strength (random strength ratio) is set to 5 or more. Preferably it is 6 or more. The ODF is analyzed from the pole figure obtained by the X-ray diffraction method, and {110}, {200}, {211} and {310} pole figures may be used. The position at which the pole figure is measured is a 1/4 position of the plate thickness. The reason why the orientation develops is not clear, but as a result of nonuniform deformation being promoted by the deformation restraint force at the grain boundary being changed by P and Sn segregated at the grain boundary before cold rolling, It is presumed that it develops when

3. Sheet Thickness While reducing the sheet thickness, the iron loss is reduced, and the effect of the present invention increases the magnetic flux density even in the case of a sheet-thin material that has a high cold rolling reduction ratio and tends to decrease the magnetic flux density. Therefore, from the standpoint of achieving both low iron loss and high magnetic flux density, the plate thickness is preferably 0.10 to 0.25 mm.

B. Next, a method for producing a non-oriented electrical steel sheet according to the present invention will be described. The method for producing a non-oriented electrical steel sheet according to the present invention includes a hot rolling process in which hot rolling is performed on a steel ingot or steel slab having the steel composition described above, and a hot rolled steel sheet obtained by the hot rolling process. Hot-rolled sheet annealing process for annealing, cold-rolling process for cold-rolling the steel sheet obtained by the hot-rolled sheet annealing process, and finish annealing for the cold-rolled steel sheet obtained by the cold-rolling process In the manufacturing method of a non-oriented electrical steel sheet having a finish annealing step to be applied, hot-rolled sheet annealing is maintained at 950 ° C. or higher and 1050 ° C. or lower for 10 seconds or longer and 3 minutes or shorter, and the total rolling reduction in cold rolling is 88% or higher. 96% or less, and finish annealing is performed at 950 ° C. or more and 1050 ° C. or less for 10 seconds or more and 120 seconds or less.

  According to the present invention, a steel ingot or steel slab having a predetermined steel composition is used, and the hot rolled sheet annealing conditions, the cold rolling conditions, and the finish annealing conditions are in a predetermined range. A steel sheet can be produced without causing breakage during cold rolling.

  Hereinafter, each process in the manufacturing method of the non-oriented electrical steel sheet according to the present invention will be described.

(1) Hot rolling process The hot rolling process in this invention is a process of hot-rolling the steel ingot or steel slab (henceforth "slab") provided with the steel composition mentioned above. In addition, about the steel composition of a steel ingot or a steel piece, since it is the same as that of what was described in the term of the "A. non-oriented electrical steel sheet" mentioned above, description here is abbreviate | omitted.

  In this step, the steel having the above-described composition is made into a slab by a general method such as a continuous casting method or a method of rolling a steel ingot, and is charged in a heating furnace and subjected to hot rolling. At this time, when the slab temperature is high, hot rolling may be performed without charging the heating furnace. The slab heating temperature is not particularly limited, but is preferably 1000 to 1300 ° C. from the viewpoint of cost and hot rolling properties. More preferably, it is 1050-1250 degreeC. Moreover, various conditions of hot rolling are not specifically limited, For example, what is necessary is just to perform according to general conditions, such as finishing temperature 700-950 degreeC and coiling temperature 750 degrees C or less. The finished thickness of hot rolling is preferably 1.8 mm or more and 2.8 mm or less from the viewpoint of productivity. This is because when the finished thickness is less than 1.8 mm, the efficiency of hot rolling and pickling is significantly deteriorated. Moreover, said finishing thickness is preferable also from a viewpoint of ensuring the preferable cold rolling reduction rate mentioned later.

(2) Hot-rolled sheet annealing process In this invention, the hot-rolled sheet annealing process which performs hot-rolled sheet annealing to the hot-rolled steel plate obtained by the said hot-rolling process is performed. This is because the magnetic properties are improved by performing the hot-rolled sheet annealing step. Hot-rolled sheet annealing is performed by continuous annealing at 950 ° C. or higher and 1050 ° C. or lower for 10 seconds or longer and 3 minutes or shorter. When the hot-rolled sheet annealing temperature exceeds the above-described range, the load on the equipment becomes large, and when the hot-rolled sheet annealing time exceeds the above-mentioned range, productivity is deteriorated. When the hot-rolled sheet annealing temperature and the hot-rolled sheet annealing time are less than the above range, the effect of improving the magnetic properties is small. In the hot-rolled sheet annealing step, it is preferable to hold at 950 ° C. or higher and 1050 ° C. or lower for 10 seconds or longer and 3 minutes or shorter, and then hold at 800 ° C. or higher and 920 ° C. or lower for 10 seconds or longer and 2 minutes or shorter. This is because the effect of improving the magnetic flux density is increased. Although the reason for this is not clear, it is presumed that the segregation of P and Sn to the grain boundaries proceeds by maintaining the temperature range during cooling, and a preferable texture develops after subsequent cold rolling and finish annealing. By implementing these as a series of annealing, the magnetic flux density of a thin material can be improved without impairing productivity. From the viewpoint of advancing segregation, box annealing type hot-rolled sheet annealing is advantageous, but productivity is inferior. In addition, precipitates are formed during box annealing-type hot-rolled sheet annealing that Mo contained for improving cold-rollability is maintained for a long time, and the effect of improving cold-rollability is reduced as well as deterioration of magnetic properties. cause. In the present invention, the difference in the effect of improving the magnetic flux density, which is presumed to be caused by the progress of the grain boundary segregation of P in the continuous annealing type hot rolled sheet annealing compared with the box annealing type hot rolled sheet annealing, P and Sn are improved by containing P and Sn in a composite manner, and P and Sn dissolved in the grains as well as the grain boundaries are important for the expression of the composite effect. In order to obtain the effect of improving the cold rolling property by Mo and obtaining the effect of improving the composite magnetic flux density by P and Sn, it is preferable to perform the above-described two-stage hot-rolled sheet annealing.

(3) Cold rolling process The cold rolling process in the present invention is a process in which the steel sheet obtained by the hot-rolled sheet annealing process is subjected to a single cold rolling without intermediate annealing. In this step, the total rolling reduction is set to 88% or more and 96% or less, and the steel sheet is finished to a predetermined thickness. Preferably it is 90% or more. By carrying out rolling under the above conditions, the above-mentioned texture preferable for improving magnetic properties is effectively developed after finish annealing in the steel sheet having the conditions of the present invention.

(4) Finish annealing process In the finish annealing process in this invention, the cold rolled steel plate obtained by the cold rolling process mentioned above is annealed at 950 degreeC or more and 1050 degrees C or less for 10 seconds or more and 120 seconds or less. When the annealing temperature in finish annealing (hereinafter also referred to as “finish annealing temperature”) is less than 950 ° C., or the annealing time in finish annealing (hereinafter also referred to as “finish annealing time”) is less than 10 seconds. This is because it may be difficult to ensure the desired iron loss. Further, when the finish annealing temperature exceeds 1050 ° C., the load on the equipment increases, and when the finish annealing time exceeds 120 seconds, the productivity is deteriorated.

(5) Others In the present invention, it is preferable to perform a coating process for applying an insulating coating after the finish annealing process. The type of insulating coating is not particularly limited, and it is only necessary to apply an insulating coating made of only an organic component, only an inorganic component, or an organic-inorganic composite. Dichromic acid-boric acid-based, phosphoric acid-based, silica-based, etc. can be used as inorganic components, and organic components such as general acrylic-based, acrylic styrene-based, acrylic silicon-based, silicon-based, polyester-based, epoxy-based, Fluorine resin can be used. In consideration of paintability, an emulsion type resin is preferable. Moreover, you may give the coating which exhibits adhesiveness by heating and pressurizing. As the coating having adhesiveness, acrylic, phenol, epoxy, melamine, and the like are preferable.

The non-oriented electrical steel sheet manufactured according to the present invention is the same as that described in the above-mentioned section “A. Non-oriented electrical steel sheet”, and thus the description thereof is omitted here.
The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

Hereinafter, the present invention will be described specifically by way of examples and comparative examples.
[Example 1]
Steels having chemical components shown in Table 1 below were melted and finished to a thickness of 2.0 mm by hot rolling. Subsequently, continuous annealing-type hot-rolled sheet annealing was performed, which was held at 1000 ° C. for 40 seconds and then held at 800 ° C. for 60 seconds, and finished to a sheet thickness of 0.15 mm by cold rolling. Then, the finish annealing which hold | maintains at 1000 degreeC for 30 second was given. The obtained non-oriented electrical steel sheet was punched into a 55 mm square single plate test piece, and the magnetic flux density B ₅₀ and iron loss W _10/800 (iron when magnetized to 1.0 T at 800 Hz by a single plate magnetometer) Loss), and {110}, {200}, {211} and {310} pole figures are measured by X-ray diffractometry at a thickness of 1/4, and φ1 of φ2 = 0 ° cross section from ODF The degree of integration (intensity) at 20 ° and Φ = 15 ° was evaluated. The results are shown in Table 1. The underline indicates outside the range defined in the present invention.

Steel number 1 not only satisfied the above formula (1), but also had an inferior iron loss, as well as the Si content not exceeding the lower limit defined in the present invention. Steel No. 2 broke during cold rolling because the Si, Mn, and Mo contents deviated from the range limited by the present invention, and in particular, the Si content deviated from the upper limit defined by the present invention. Steel number 3 not only satisfied the above formula (1) but also inferior in magnetic flux density and iron loss, as well as the Mn content not exceeding the upper limit defined in the present invention. Steel No. 4 not only exceeded the lower limit value defined by the present invention for the Al content, but also did not satisfy the above formula (1), and was inferior in both magnetic flux density and iron loss. Steel No. 5 had a low magnetic flux density because the Al content deviated from the upper limit defined in the present invention. Steel No. 6 was inferior in both the magnetic flux density and iron loss because the S content in Steel No. 7 and the N content in Steel No. 7 deviated from the upper limits defined in the present invention. Steel number 8 broke during cold rolling because the P content deviated from the upper limit defined in the present invention. Steel No. 9 was inferior in both magnetic flux density and iron loss because the Mo content deviated from the upper limit defined in the present invention. Steel No. 10 had a low magnetic flux density because the P content was outside the lower limit defined in the present invention.
On the other hand, Steel Nos. 11 to 16 and Steel Nos. 17 to 22 satisfying the conditions limited in the present invention have developed favorable textures for improving magnetic properties, and have equivalent Si, Mn, and Al contents. Compared with Steel No. 10, both iron loss and magnetic flux density were excellent. When steel numbers 11-16 and steel numbers 17-22 were compared, the direction of steel numbers 17-22 of the range with preferable Sn content was excellent in the magnetic flux density.

[Example 2]
Steel No. 10 of Table 1 and to 19 of the hot-rolled sheet (sheet thickness 2.0 mm), (A) hot-rolled sheet annealing for holding at 1000 ° C. for 40 seconds, 800 ° C. after holding for 40 seconds at 1000 ° C. (B) (C) Hot-rolled sheet annealing held at 900 ° C. for 40 seconds, (D) Hot-rolled sheet annealing held at 950 ° C. for 5 seconds, and cooled. Finished to a sheet thickness of 0.15 to 0.30 mm by hot rolling. Then, the finish annealing which hold | maintains at 1000 degreeC for 30 second was given. For test number 2-15, finish annealing was held at 900 ° C. for 10 seconds, and for test number 2-16, finish annealing was held at 950 ° C. for 5 seconds. The obtained non-oriented electrical steel sheet was punched into a 55 mm square single plate test piece, and the magnetic flux density B ₅₀ and iron loss W _10/800 (iron when magnetized to 1.0 T at 800 Hz by a single plate magnetometer) Loss), and {110}, {200}, {211} and {310} pole figures are measured by X-ray diffractometry at a thickness of 1/4, and φ1 of φ2 = 0 ° cross section from ODF = 20 °, Φ = 15 ° integration degree was evaluated. The results are shown in Table 2.

  Test numbers 2-1 to 2-6 using steel number 10 are inferior in both magnetic flux density and iron loss because the steel composition is outside the limited range of the present invention and the degree of integration in a preferred orientation for improving magnetic properties is weak. It was. On the other hand, test numbers 2-7 to 2-12 using steel number 19 whose steel composition satisfies the limitation of the present invention are superior in magnetic properties to test numbers 2-1 to 2-6 regardless of the plate thickness. In particular, the effect was remarkable in a thin plate material having a high cold rolling reduction ratio. Moreover, in the test numbers 2-10 to 2-12 which implemented the hot-rolled sheet annealing conditions on the preferable conditions of this invention, it was further excellent in the magnetic characteristic. On the other hand, the test number 2-13, 14 when the temperature during the hot-rolled sheet annealing and the holding time are out of the preferred range of the present invention and the test number 2-15 when the temperature during the finish annealing and the holding time are out of the preferable range of the present invention. As for 16, the desired texture was not obtained.

Claims (5)

By mass%, Si: 1.7% to 3.5%, Al: 0.1% to 2.0% and Mn: 0.08% to less than 1.5% satisfy the following formula (1) In addition, P: more than 0.03% 0.15% or less, Sn: 0.03% to 0.15%, C: 0.005% or less, S: 0.0040% or less, N: 0.005% or less and Mo: 0.002% or more and 0.2% or less, with the balance being Fe and impurities, in the crystal orientation distribution function at the 1/4 thickness position after finish annealing A non-oriented electrical steel sheet characterized by a strength of φ1 = 20 ° and φ = 15 ° of a φ2 = 0 ° cross section being 5 or more.
Si + 2 × Al-Mn ≧ 2.0 (1)
(Here, Si, Al, and Mn indicate the content (unit: mass%) of each element.)   The non-oriented electrical steel sheet according to claim 1, wherein the thickness is 0.10 to 0.25 mm.   A hot rolling step for hot rolling a steel ingot or steel slab comprising the steel composition according to claim 1, and a hot rolled sheet annealing step for annealing the hot rolled steel sheet obtained by the hot rolling step; A non-directional method comprising: a cold rolling process in which cold rolling is performed on the steel sheet obtained by the hot-rolled sheet annealing process; and a finish annealing process in which finishing annealing is performed on the cold-rolled steel sheet obtained by the cold rolling process. In the manufacturing method of the heat-resistant electrical steel sheet, the hot-rolled sheet annealing is held at 950 ° C. or higher and 1050 ° C. or lower for 10 seconds or longer and 3 minutes or shorter, the total rolling reduction in cold rolling is 88% or higher and 96% or lower, and the final annealing is 950 A method for producing a non-oriented electrical steel sheet, which is performed at a temperature of from 950 ° C to 1050 ° C for from 10 seconds to 120 seconds.   The hot-rolled sheet annealing is carried out by continuous annealing of holding at 950 ° C or higher and 1050 ° C or lower for 10 seconds or longer and 3 minutes or shorter, and thereafter holding at 800 ° C or higher and 920 ° C or lower for 10 seconds or longer and 2 minutes or shorter. The manufacturing method of the non-oriented electrical steel sheet described in 1.   The method for producing a non-oriented electrical steel sheet according to claim 4, wherein the finished sheet thickness in cold rolling is set to 0.10 to 0.25 mm.

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