JP2017119897A - Non-oriented electrical steel sheet and method for producing non-oriented electrical steel sheet - Google Patents

Abstract

A non-oriented electrical steel sheet that has lower high-frequency iron loss, higher magnetic flux density, and higher strength, and that can be mass-produced at low cost, and a method for manufacturing the non-oriented electrical steel sheet. to do. A non-oriented electrical steel sheet according to the present invention has Si: 2.7 to 3.6%, Al: 0.5 to 1.4%, and Si+Al: 3.5 to 4.1% by mass. %, Mn: 0.1 to 1.5%, C: 0.0010 to 0.0040%, N: 0.0001 to 0.0030%, S: 0.0001 to 0.0018%, Ti: 0. 0001 to 0.0030% and P that satisfies the formula (1), the balance being Fe and impurities, and the plate thickness t (mm) is 0.15 or more and 0.28 or less Yes, iron loss W10/800 (W/kg), magnetic flux density B50 (T), yield stress YS (MPa), and steel plate grain size D (μm) satisfy formulas (2) to (5). [Selection figure] None

Description

  The present invention relates to a non-oriented electrical steel sheet and a method for producing a non-oriented electrical steel sheet.

  In recent years, global environmental problems have been attracting attention, and the demand for energy conservation efforts is increasing.

  In automobiles, improvement in fuel efficiency is strongly demanded, and electric cars that use a motor as a driving force and hybrid cars that use a motor and a gasoline (diesel) engine together as a driving force are being put into practical use. These motor cores are composed of a stator that is a stator and a rotor that is a rotor. With regard to this motor, when the running speed of the automobile is increased, that is, when the motor is rotated at a high speed, both the stator and the rotor generate a large amount of heat, but a material with a small amount of heat is required. In addition, since a high motor torque is required at the start of the automobile, a high magnetic flux density is particularly required for the stator material. Furthermore, the rotor material is required to have a certain material strength so that the core is not deformed or broken when rotated at high speed.

  In order to obtain the above required characteristics, it is possible to prepare the stator and rotor materials separately, but in order to reduce the core material cost, it is necessary to cover the stator and rotor with a single material. Furthermore, from the viewpoint of cost reduction of the material, it has become essential to obtain necessary characteristics only by one cold rolling without performing cold rolling two or more times.

  In the following Patent Document 1, the value of the iron loss W10 / 800 at a frequency of 800 Hz and a magnetic flux density of 1.0 T is set to W10 / 800 (W by making Si and Al a high alloy and adding P, Sn, and Sb in combination. / Kg) ≦ 100 × plate thickness (mm) +15 A good non-oriented electrical steel sheet is disclosed.

  Patent Document 2 below discloses a non-oriented electrical steel sheet having a high-frequency iron loss value of W10 / 800 ≦ 50 W / kg obtained by a combined addition of P and S and having a high magnetic flux density with respect to a reference material. Has been.

JP 2013-44010 A JP 2013-44012 A

  However, in recent years, non-oriented electrical steel sheets with better iron loss have been demanded, and with the non-oriented electrical steel sheets disclosed in Patent Document 1, it is difficult to achieve the desired iron loss. It has become.

  In addition, when a certain amount of P and S is combined in accordance with the technique disclosed in Patent Document 2, it has been found that the steel plate is cracked during manufacturing, particularly during cold rolling, and cannot be passed. It was. Further, since the cold rolling rate in a single pass increases when the final plate thickness is thin, it has become clear that the tendency of such a steel plate to crack increases as the final plate thickness decreases.

Further, regarding the strength of the product, when the plate thickness is reduced, the crystal grain size for obtaining a good iron loss is shifted to a larger side, so that there is a problem that the strength cannot be secured.
In this way, the recent needs for good non-oriented electrical steel sheets for motor cores, especially in automobiles, are to suppress the cracking of steel sheets with products with low high-frequency iron loss, high magnetic flux density, and high strength. However, it is to manufacture at low cost.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to have lower high-frequency iron loss, higher magnetic flux density, higher strength, and low cost. It is providing the manufacturing method of a non-oriented electrical steel plate and a non-oriented electrical steel plate which can be mass-produced by.

The gist of the present invention is as follows.
(1) In mass%, Si: 2.7 to 3.6%, Al: 0.5 to 1.4%, Si + Al: 3.5 to 4.1%, Mn: 0.1 to 1.5% C: 0.0010 to 0.0040%, N: 0.0001 to 0.0030%, S: 0.0001 to 0.0018%, Ti: 0.0001 to 0.0030%, and the following formula It contains P satisfying (1), the remainder has a component consisting of Fe and impurities, the plate thickness t (mm) is 0.15 or more and 0.28 or less, and the iron loss W10 / 800 (W / kg), magnetic flux density B50 (T), yield stress YS (MPa), and steel plate crystal grain size D (μm) satisfy the following formulas (2) to (5).
(2) The non-oriented electrical steel sheet according to (1), wherein 0.005 to 0.100 mass% of at least one of Sn and Sb is contained instead of a part of the remaining Fe.
(3) The non-oriented electrical steel sheet according to (1) or (2), containing 0.02 to 0.20 mass% of at least one of Ni and Cu instead of a part of the remaining Fe.
(4) The non-oriented electrical steel sheet according to any one of (1) to (3), wherein the non-oriented electrical steel sheet is a non-oriented electrical steel sheet for a motor core.
(5) In the annealing performed before cold rolling in the manufacturing method of the non-oriented electrical steel sheet, which is subjected to annealing after a predetermined steel material is hot-rolled, and is subjected to a final sheet thickness by cold rolling and then subjected to finish annealing. The cooling rate of the steel sheet after annealing is set to 20 ° C./s to 150 ° C./s, and then cold rolling is performed at a rolling rate of 85.0 to 93.5% within 48 hours, and the temperature rise temperature in finish annealing In the range of 20 to 400 ° C./s, and the steel sheet is, by mass, Si: 2.7 to 3.6%, Al: 0.5 to 1.4%, Si + Al: 3.5 to 4.1. %, Mn: 0.1 to 1.5%, C: 0.0010 to 0.0040%, N: 0.0001 to 0.0030%, S: 0.0001 to 0.0018%, Ti: 0.00. 0001 to 0.0030%, and containing P satisfying the following formula (1), the balance being Fe and impurities Made has a component, the final sheet thickness t (mm), and 0.15 or more 0.28 or less, the manufacturing method of the non-oriented electrical steel sheet.
(6) The cooling rate of the steel plate after the annealing is a cooling rate up to 100 ° C, and the heating rate during the finish annealing is a heating rate up to 850 ° C. Method for producing an electrical steel sheet.
(7) The steel sheet further contains 0.005 to 0.100% by mass of at least one of Sn and Sb instead of a part of the remaining Fe, according to (5) or (6). A method for producing a non-oriented electrical steel sheet.
(8) The steel sheet further includes 0.02 to 0.20 mass% of at least one of Ni and Cu instead of a part of the remaining Fe, and any one of (5) to (7) The manufacturing method of the non-oriented electrical steel sheet as described in one.
(9) Iron loss W10 / 800 (W / kg), magnetic flux density B50 (T), yield stress YS (MPa) and steel plate crystal grain size D (μm) are expressed by the following formulas (2) to (5). The method for producing a non-oriented electrical steel sheet according to any one of (5) to (8), which is satisfied.
(10) The method for producing a non-oriented electrical steel sheet according to any one of (5) to (9), which is used for a motor core.

  As described above, according to the present invention, a non-oriented electrical steel sheet and a non-oriented electrical steel sheet that have lower high-frequency iron loss, higher magnetic flux density, higher strength, and can be mass-produced at low cost. It becomes possible to provide the manufacturing method of a grain-oriented electrical steel sheet.

  Hereinafter, preferred embodiments of the present invention will be described in detail.

  In the embodiment of the present invention described below, a non-oriented electrical steel sheet having a lower high-frequency iron loss, a higher magnetic flux density, a higher strength, and capable of mass production at a low cost, and a manufacturing method thereof are described in detail explain. More specifically, the non-oriented electrical steel sheet and the non-oriented electrical steel sheet manufacturing method according to the embodiment of the present invention are a thin non-oriented having a lower high-frequency iron loss, a higher magnetic flux density, and a higher strength. It solves various problems that occur when an electrical steel sheet is manufactured by a single cold rolling for the purpose of cost reduction. In such a case, there are a plurality of problems that the steel plate is cracked during cold rolling, the strength of the steel plate is reduced, and the magnetic flux density B50 of the steel plate is further reduced.

  The present inventors have addressed the problems in producing non-oriented electrical steel sheets having lower high-frequency iron loss, higher magnetic flux density, and higher strength, and capable of mass production at low cost. Took the following measures.

  That is, in order to realize a lower high-frequency iron loss, it is necessary to make the steel plate highly alloy and reduce the plate thickness. At this time, in order to maintain a higher magnetic flux density, the alloy addition amount was controlled and P was added. Further, it has been found that in reducing the sheet thickness in one cold rolling, the cold rolling rate increases, so that the amount of P to be added needs to be increased. Further, when the plate thickness is reduced, the crystal grain size at which the iron loss is optimal is shifted to the larger side, and as a result, the desired mechanical strength is not reached. However, it has been found that the mechanical strength value increases when P is added, and that the desired mechanical strength value is reached when P is added as much as the thinner material. Based on the above findings, the above problems can be solved.

  Below, each component in this embodiment is demonstrated in detail.

(About non-oriented electrical steel sheets)
<Chemical composition of non-oriented electrical steel sheet>
Below, the chemical component which the non-oriented electrical steel sheet which concerns on this embodiment has first is demonstrated in detail. In the following, “%” represents “mass%” unless otherwise specified.

[Si: 2.7 to 3.6%]
When the steel sheet contains Si, the specific resistance increases and the iron loss decreases. When the Si content is less than 2.7%, the specific resistance increase and the iron loss reduction effects are insufficient. On the other hand, if the Si content exceeds 3.6%, the toughness deteriorates and cold rolling becomes difficult. Therefore, the Si content is set to be 2.7% to 3.6%. The Si content is preferably 2.8% or more and 3.3% or less.

[Al: 0.5 to 1.4%]
The steel sheet contains Al, so that the specific resistance increases like Si, and the iron loss (especially high-frequency iron loss) decreases. If the Al content is less than 0.5%, the effect of increasing the specific resistance and reducing the iron loss becomes insufficient. On the other hand, if the Al content exceeds 1.4%, the reason is unknown, but the hysteresis loss increases and the commercial frequency iron loss increases. Therefore, the Al content is 0.5% or more and 1.4% or less. The Al content is preferably 0.6% or more and 1.2% or less.

[Si + Al: 3.5 to 4.1%]
If the total content of Si and Al is less than 3.5%, the effect of reducing iron loss cannot be obtained, so the lower limit of the total content of Si and Al was set to 3.5%. On the other hand, when there is too much total content, toughness will deteriorate, a crack will arise at the time of cold rolling, and it will become impossible to manufacture a non-oriented electrical steel sheet. In particular, when a thin steel plate is produced by cold rolling once, the rolling rate per pass is increased, and it is important to further suppress the total content of Si and Al. For this reason, the upper limit of the total content of Si and Al was set to 4.1%. The total content of Si and Al is preferably 3.7% or more and 4.0% or less.

[Mn: 0.1 to 1.5%]
The steel sheet contains Mn, thereby reducing iron loss. If the Mn content is less than 0.1%, fine precipitates are formed and the iron loss increases. On the other hand, when the content of Mn exceeds 1.5%, a large amount of carbides are formed and the iron loss increases. Therefore, the Mn content is 0.1% or more and 1.5% or less. The Mn content is preferably 0.2% or more and 1.2% or less.

[C: 0.0010 to 0.0040%]
When the C content in the steel sheet is less than 0.0010%, the magnetic flux density decreases, and when the C content in the steel sheet exceeds 0.0040%, the iron loss is deteriorated. Therefore, the C content is set to be 0.0010% or more and 0.0040% or less. The content of C is preferably 0.0010% or more and 0.0030% or less.

[N: 0.0001 to 0.0030%]
N is an element that causes magnetic aging and increases iron loss. For this reason, the N content needs to be 0.0030% or less. On the other hand, if the content of N is to be reduced below 0.0001%, only a cost increase is caused. Therefore, the N content is set to be 0.0001% or more and 0.0030% or less. The N content is preferably 0.0001% or more and 0.0020% or less.

[S: 0.0001 to 0.0018%]
S is an element that forms fine precipitates and increases iron loss. For this reason, content of S needs to be 0.0018% or less. On the other hand, if the content of S is to be reduced below 0.0001%, only the cost is unnecessarily increased. Therefore, the S content is set to be 0.0001% or more and 0.0018% or less. The S content is preferably 0.0001% or more and 0.0015% or less.

[Ti: 0.0001 to 0.0030%]
Ti is an element that forms fine precipitates and increases iron loss. For this reason, the Ti content needs to be 0.0030% or less. On the other hand, if it is attempted to reduce the Ti content to less than 0.0001%, only a cost increase is caused. Therefore, the Ti content is set to be 0.0001% or more and 0.0030% or less. The Ti content is preferably 0.0001% or more and 0.0020% or less.

[P: (−0.2 × t + 0.08) to (0.2 × t + 0.08)%]
Since P is an element that has an effect of improving the texture, the magnetic flux density B50 (the magnetic flux density at 5000 A / m) can be improved by containing it in the steel sheet. In particular, if the thickness of the non-oriented electrical steel sheet is reduced, the cold rolling rate increases and B50 decreases. In that case, it is necessary to contain a large amount of P. In addition, when the plate thickness is thin, the optimum crystal grain size for obtaining a low iron loss becomes large, so that a desired mechanical strength cannot be obtained. It has been found that the strength of can be obtained. For the above reasons, in the present embodiment, the P content in the steel sheet is set to a value within a range defined according to the thickness (final thickness) of the non-oriented electrical steel sheet.

  Although it demonstrates concretely in Example 1 shown below, when the plate thickness of a non-oriented electrical steel sheet is set to t (mm) when the effect of improving magnetic flux density B50 was concretely verified while changing the plate thickness, It was revealed that the effect of improving the magnetic flux density B50 can be realized with certainty by setting the P content to (−0.2 × t + 0.08)% or more. On the other hand, when the content of P is increased, the toughness is lowered and cracking occurs during cold rolling. Moreover, since the cold rolling load increases as the plate thickness is reduced, the upper limit of the P content must be reduced as the plate thickness is reduced. Therefore, for the upper limit value that satisfies the balance between the two phenomena in a trade-off relationship, that is, the mechanical strength is improved by containing a large amount of P and the toughness is reduced by containing a large amount of P, the plate thickness is set to When actually verified while changing, it was found to be 0.2 × t + 0.08. Accordingly, the P content is set to (−0.2 × t + 0.08)% or more and (0.2 × t + 0.08)% or less as represented by the following formula (1). The content of P is preferably (−0.2 × t + 0.09)% or more and (0.2 × t + 0.07)% or less.

  In the chemical composition of the non-oriented electrical steel sheet according to the present embodiment, the balance of the above elements is Fe and impurities. In addition, in the chemical component of the non-oriented electrical steel sheet according to the present embodiment, the following optional additive element may be contained instead of a part of the remaining Fe.

[Sn, Sb: 0.005 to 0.100%]
Sn and Sb are elements that have a function of ensuring low iron loss by segregating on the surface and suppressing oxidation during annealing. In order to obtain such an effect, it is preferable to contain 0.005% or more of at least one of Sn and Sb. Moreover, when the total content of Sn and Sb exceeds 0.10%, this effect is saturated. Therefore, the content (total content) of at least one of Sn and Sb is preferably 0.005% or more and 0.10% or less. The content of at least one of Sn or Sb is more preferably 0.010% or more and 0.080% or less.

[Ni, Cu: 0.02 to 0.20%]
Ni and Cu are elements that have the effect of changing the texture and improving the magnetic flux density. In order to obtain such an effect, it is preferable to contain 0.02% or more of at least one of Ni and Cu. Moreover, when the total content of Ni and Cu exceeds 0.20%, this effect is saturated. Therefore, the content (total content) of at least one of Ni and Cu is preferably 0.02% or more and 0.20% or less. The content of at least one of Ni and Cu is more preferably 0.03% or more and 0.12% or less.

  In addition to the above elements, Cr and Mo are included in the range of 0.0001 to 0.0500%, and elements such as Pb, Bi, V, As, and B are included in the range of 0.0001 to 0.0050%. Even if this is done, the present invention is not impaired.

Heretofore, the chemical components of the non-oriented electrical steel sheet according to the present embodiment have been described in detail.
In addition, when measuring the chemical composition of a non-oriented electrical steel sheet ex post, it is possible to use various known measuring methods, for example, ICP-MS (inductively coupled plasma mass spectrometry) method, etc. What is necessary is just to use suitably.

<Thickness of non-oriented electrical steel sheet>
The product plate thickness t (mm) needs to be 0.28 mm or less in order to reduce high-frequency iron loss. On the other hand, if the product plate thickness is less than 0.15 mm, it is difficult to pass the annealing line because the plate thickness is thin. Therefore, the thickness of the non-oriented electrical steel sheet is set to 0.15 mm or more and 0.28 mm or less. The thickness of the non-oriented electrical steel sheet is preferably 0.20 mm or more and 0.25 mm or less.

  The non-oriented electrical steel sheet according to the present embodiment has been described in detail above.

(About manufacturing method of non-oriented electrical steel sheet)
In the method for producing a non-oriented electrical steel sheet according to the present embodiment, first, a slab having the above composition is heated (slab heating), hot rolling is performed on the heated slab, and a steel strip (hot-rolled steel strip) is obtained. ) Here, the content of P in the slab is adjusted in advance to be within the range of the above formula (1) in consideration of the final thickness t (mm) of the non-oriented electrical steel sheet to be manufactured.

  Although the slab heating temperature at the time of subjecting to hot rolling is not particularly specified, it is preferably, for example, 1000 ° C. or more and 1250 ° C. or less. The thickness after hot rolling is not particularly specified, but is preferably about 1.6 to 2.4 mm, for example.

  After the hot rolling step, the steel strip is further annealed, and then the steel strip is brought to a predetermined final thickness by a single cold rolling. Then, finish annealing of the obtained steel strip is performed.

  Among the above steps, the plate temperature and annealing time in the hot-rolled sheet annealing are not particularly specified, but for example, the plate temperature is preferably about 850 to 1100 ° C., and the annealing time is about 10 to 180 seconds. It is preferable to do. The reason for this is to obtain a good magnetic flux density B50 by recrystallization and grain growth of the structure of the hot-rolled sheet by annealing. If the plate temperature is too high, or if the annealing time is too long, the effect of improving the magnetic flux density B50 is saturated, which is not preferable.

  The cooling rate from 900 ° C. to 100 ° C. in the hot-rolled sheet annealing needs to be 20 to 150 ° C./s. The reason for this is that by setting the cooling rate to 20 ° C./s or more, solid solution C is present in the steel after cooling, and the magnetic flux density B50 is improved. On the other hand, when the cooling rate exceeds 150 ° C./s, the steel plate is greatly deformed by rapid cooling, and cold rolling becomes difficult. Therefore, the cooling rate from 900 ° C. to 100 ° C. in the hot-rolled sheet annealing is set to 20 ° C./s or more and 150 ° C./s or less. The cooling rate from 900 ° C. to 100 ° C. in the hot-rolled sheet annealing is preferably 30 ° C./s or more and 100 ° C./s or less.

  The time from the end of hot-rolled sheet annealing to the start of cold rolling needs to be within 48 hours. The reason for this is that the magnetic flux density B50 is improved when cold rolling is performed while a certain amount of solid solution C is present in the steel by hot-rolled sheet annealing. In addition, the lower limit of the time from the end of hot-rolled sheet annealing to the start of cold rolling is not particularly specified, and cold rolling may be performed immediately after the end of hot-rolled sheet annealing. The time from the end of hot-rolled sheet annealing to the start of cold rolling is preferably within 36 hours.

  The rolling rate in cold rolling needs to be in the range of 85.0% or more and 93.5% or less. The reason for this is that if the rolling rate is less than 85.0%, the effect of adding P becomes difficult to obtain, and if the rolling rate exceeds 93.5%, the magnetic flux density B50 is significantly deteriorated. The rolling rate in the cold rolling is preferably 86.0% or more and 92.5% or less.

  After the cold rolling, finish annealing is performed. The crystal grain size D (μm) of the steel plate after such finish annealing needs to be in the range of (−100 × t + 65) to (−100 × t + 105), where the plate thickness is t (mm). This is because the range of the crystal grain diameter D that minimizes the iron loss W10 / 800 changes according to the plate thickness. The range of the crystal grain size D as described above is obtained by specifically verifying the change in the iron loss W / 800 while changing the plate thickness. The range of the crystal grain size D is preferably (−100 × t + 80) μm or more and (−100 × t + 100) μm or less.

  The range of the temperature of the steel plate and the annealing time in the finish annealing is not particularly defined as long as the crystal grain size D is within the above range, but the plate temperature is set to 850 to 1100 ° C., and the annealing time is set to 10 to 240 seconds. It is common. If the plate temperature is too high, the temperature of the annealing furnace needs to be further increased, which is not preferable for the equipment. If the plate temperature is too low, the annealing time becomes long and the productivity is hindered. The annealing time is determined according to the above.

  Here, the steel plate temperature increase rate from 450 ° C. to 850 ° C. in the finish annealing heating region needs to be 20 ° C./s or more and 400 ° C./s or less. The reason for this is that by setting the steel plate heating rate to 20 ° C./s or more, the magnetic flux density B50 becomes good, and even if the steel plate heating rate is increased beyond 400 ° C./s, the effect of improving the magnetic flux density is saturated. is there. The steel sheet heating rate from 450 ° C. to 850 ° C. in the finish annealing heating region is preferably 30 ° C./s or more and 400 ° C./s or less.

  By applying an insulating coating to the annealed sheet, a non-oriented electrical steel sheet product is obtained.

  The method for manufacturing the non-oriented electrical steel sheet according to the present embodiment has been described in detail above.

(About characteristics of non-oriented electrical steel sheet)
When the non-oriented electrical steel sheet was manufactured by changing the final thickness by the manufacturing method as described above, it was revealed that the manufactured non-oriented electrical steel sheet exhibited the following characteristics.

  For example, if the thickness of the produced non-oriented electrical steel sheet is t (mm), the iron loss W10 / 800 satisfies the following formula (2), and the magnetic flux density B50 is expressed by the following formula (3 ). These values of iron loss W10 / 800 and magnetic flux density B50 are very good.

  Moreover, about the yield stress YS which shows mechanical strength, it will satisfy | fill the following formula | equation (4) and the mechanical strength of a non-oriented electrical steel sheet will become favorable. Usually, when the product plate thickness is reduced, the crystal grain size D at which the iron loss is optimal increases, so the yield stress YS decreases. However, this embodiment is characterized in that when the plate thickness is thin, a large amount of P is contained in order to ensure the magnetic flux density B50, so that a desired mechanical strength value can be achieved. If the yield point cannot be clearly confirmed during the tensile test, a 0.2% proof stress may be substituted.

  Furthermore, the crystal grain size D of the produced non-oriented electrical steel sheet satisfies the following formula (5) as described above.

  The iron loss W10 / 800 and the magnetic flux density B50 of the produced non-oriented electrical steel sheet are the Epstein method defined in JIS C2550 and the single plate magnetic property measurement method (Single Sheet Tester: SST) defined in JIS C2556. ) And can be measured. Moreover, the yield stress YS of the manufactured non-oriented electrical steel sheet can be measured by preparing a JIS test piece specified in JIS Z2201 and using a known tensile tester. Further, the crystal grain size D of the produced non-oriented electrical steel sheet can be measured by various known measuring methods. For example, the obtained non-oriented electrical steel sheet is obtained at a magnification of about 100 times. It is possible to specify by observing about three visual fields under a microscope and averaging the obtained crystal grain size measurement results by the number of visual fields.

  As described above, the present embodiment can achieve both low-frequency iron loss, higher magnetic flux density, and higher strength, non-oriented electrical steel sheet that can be mass-produced at low cost, and non-directionality. A method for producing an electrical steel sheet is provided. The non-oriented electrical steel sheet and the non-oriented electrical steel sheet manufacturing method according to the present embodiment greatly contribute to the development of motors such as air compressors and refrigerators as well as high efficiency and low cost of electric vehicles or hybrid vehicles. The social effects are enormous.

  Next, experiments conducted by the present inventors will be described. The conditions in these experiments shown below are examples adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these examples.

Example 1
Using a vacuum melting furnace, in mass%, C: 0.0023%, Mn: 0.23%, S: 0.0014%, Ti: 0.0011%, N: 0.0018%, Si, Various ingots of Al, Sn, Sb, Ni, Cu, and P were prepared to prepare a steel ingot with the balance being Fe and inevitable impurities.

  Subsequently, the steel ingot was heated at 1150 ° C. for 1 hour and removed from the furnace, and then subjected to hot rolling for a total of 6 passes to obtain a hot rolled sheet having a thickness of 2.0 mmt. About the said hot-rolled sheet, hot-rolled sheet annealing was performed at 1000 degreeC * 60 second. At this time, the cooling rate from 900 to 100 ° C. was 35 ° C./s. Within 10 hours after the hot-rolled sheet annealing, the steel sheet was cold-rolled once and subjected to finish annealing at 900 ° C. to 1050 ° C. × 20 seconds. The temperature increase rate of the steel sheet up to 450 to 850 ° C. in the finish annealing was 35 ° C./s. Further, coating coating and baking were performed to form an insulating film.

  The component composition, sheet thickness, rolling rate, and crystal grain size of the obtained non-oriented electrical steel sheet are as shown in Table 1 below. In addition, the crystal grain size of the obtained non-oriented electrical steel sheet was measured by observing with an optical microscope by said method.

  Evaluation of the steel sheet was performed by evaluating the presence or absence of cracks in the cold rolling in the middle of the process, and by performing magnetic measurements and mechanical tests after forming the insulating coating.

  About the crack in cold rolling, it evaluated by whether the 5 mm or more crack entered into the steel plate end surface. About the magnetic measurement, the obtained steel plate was sheared to 55 mm square, the iron loss and magnetic flux density in the direction perpendicular to rolling and rolling were measured by the SST method (Single Sheet Tester method), and the average value was calculated. Thus, the average of 6 sheets was taken for each composition, and the values of the iron loss and magnetic flux density in the composition were taken.

  The iron loss was W10 / 800 (1.0 T magnetic flux density, iron loss at 800 Hz), and the magnetic flux density was B50 (5000 A / m magnetic flux density). In the mechanical test, a JIS No. 5 tensile test piece was prepared and evaluated by performing a tensile test, and the yield stress YS was evaluated by 0.2% proof stress when no yield point was obtained. The obtained results are shown in Table 2 below.

  In Table 2 below, when the plate thickness t = 0.15 mm, the iron loss W10 / 800 can be judged good when W10 / 800 ≦ 25 W / kg, and the magnetic flux density B50 is good when B50 ≧ 1.648T. It can be judged that the yield stress YS is good when YS ≧ 400 MPa.

  In Table 2 below, when the plate thickness t = 0.20 mm, the iron loss W10 / 800 can be determined to be good when W10 / 800 ≦ 30 W / kg, and the magnetic flux density B50 is good when B50 ≧ 1.654T. It can be judged that the yield stress YS is good when YS ≧ 400 MPa.

  Furthermore, in Table 2 below, when the plate thickness t = 0.23 mm, the iron loss W10 / 800 can be judged as good when W10 / 800 ≦ 33 W / kg, and the magnetic flux density B50 is good when B50 ≧ 1.658T. It can be judged that the yield stress YS is good when YS ≧ 400 MPa.

  In Table 2 below, when the plate thickness is t = 0.25 mm, the iron loss W10 / 800 can be determined to be good when W10 / 800 ≦ 35 W / kg, and the magnetic flux density B50 is good when B50 ≧ 1.660T. It can be judged that the yield stress YS is good when YS ≧ 400 MPa.

Of Table 2 above, Samples 10, 18, 23, 28, and 29 were cracked during cold rolling and sample production and measurement were possible, but the results were unsuitable for mass production. I understood. In addition, among samples 1 to 35, 3.5 ≦ Si + Al ≦ 4.1, −0.2 × t (mm) + 0.08 ≦ P (%) ≦ 0.12, −100 × t (mm) + 65 ≦ Samples 2 to 9, 12, 13, 16, 17, 21, 24 to 27, 31, 33 in the range of D (μm) ≦ −100 × t (mm) +105 are W10 / 800 (W / kg) ≦ 100 × t (mm) +10, B50 (T) ≧ 0.11 × (t) ^0.5 (mm) +1.605, YS (MPa) ≧ 400 were satisfied, and it was favorable.

(Example 2)
Using a vacuum melting furnace, in mass%, C: 0.0015%, Mn: 0.28%, S: 0.0011%, Ti: 0.0016%, Si: 3.1%, Al: 0.5 %, P: 0.07%, N: 0.0015%, Sn: 0.015%, Ni: 0.031%, Cu: 0.021%, the balance being Fe and inevitable impurities A lump was prepared.

  Subsequently, the steel ingot was heated at 1150 ° C. for 1 hour and removed from the furnace, and then subjected to hot rolling for a total of 6 passes to obtain a hot rolled sheet having a thickness of 2.0 mmt. About the said hot-rolled sheet, hot-rolled sheet annealing was performed at 1000 degreeC * 60 second. At this time, hot-rolled sheet annealing was performed by variously changing the cooling rate to 900 to 100 ° C. Also, various changes were made to the waiting time from hot-rolled sheet annealing to cold rolling.

  The obtained steel sheet was cold-rolled once to obtain a cold-rolled sheet having a final sheet thickness t = 0.20 mm, and then subjected to finish annealing at 1000 ° C. for 20 seconds. The temperature increase rate of the steel sheet up to 450 to 850 ° C. in the finish annealing was also variously changed. Further, coating coating and baking were performed to form an insulating film. Table 3 below shows the cooling rate of hot-rolled sheet annealing with changed manufacturing conditions, the standby time from hot-rolled sheet annealing to cold rolling, and the temperature increase rate of finish annealing.

  As the evaluation of the steel plate, the steel plate obtained after the formation of the insulating coating was sheared to 55 mm square, and the magnetic flux density in the direction of rolling and perpendicular to the rolling was measured by the SST method (Single Sheet Tester method), and the average value was calculated. . In this way, the average of 6 sheets was taken for each composition, and the value was taken as the value of magnetic flux density for that composition. For the magnetic flux density, B50 (magnetic flux density in a magnetic field of 5000 A / m) was measured. The obtained results are also shown in Table 3 below.

  Of Table 3, Samples 36, 43, and 44 had a magnetic flux density B50 lower than 1.654T, and good magnetic properties were not obtained. For samples 37 to 42 and 45 to 50, each of the cooling rate of hot-rolled sheet annealing, the standby time from hot-rolled sheet annealing to cold rolling, and the temperature increase rate of finish annealing were within the ranges specified by the present invention. Good magnetic properties have been obtained. Among them, the higher the hot-rolled sheet annealing cooling rate, the shorter the waiting time from hot-rolled sheet annealing to cooling, and the higher the heating rate of finish annealing, the better It had magnetic properties.

As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to this example. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

Claims (10)

% By mass
Si: 2.7 to 3.6%
Al: 0.5 to 1.4%
Si + Al: 3.5 to 4.1%
Mn: 0.1 to 1.5%
C: 0.0010 to 0.0040%
N: 0.0001 to 0.0030%
S: 0.0001 to 0.0018%
Ti: 0.0001 to 0.0030%, and
P satisfying the following formula (1)
And the balance has a component consisting of Fe and impurities,
The plate thickness t (mm) is 0.15 or more and 0.28 or less,
Iron loss W10 / 800 (W / kg), magnetic flux density B50 (T), yield stress YS (MPa), and steel plate crystal grain size D (μm) satisfy the following formulas (2) to (5). Non-oriented electrical steel sheet.

  The non-oriented electrical steel sheet according to claim 1, comprising 0.005 to 0.100 mass% of at least one of Sn and Sb instead of a part of the remaining Fe.   The non-oriented electrical steel sheet according to claim 1 or 2, comprising 0.02 to 0.20 mass% of at least one of Ni and Cu instead of a part of the remaining Fe.   The non-oriented electrical steel sheet according to any one of claims 1 to 3, wherein the non-oriented electrical steel sheet is a non-oriented electrical steel sheet for a motor core. In the method of manufacturing a non-oriented electrical steel sheet, after subjecting a predetermined steel material to hot rolling, annealing, cold rolling to a final sheet thickness, and then finishing annealing,
The cooling rate of the steel sheet after annealing in annealing performed before cold rolling is set to 20 ° C./s to 150 ° C./s, and then cold rolling is performed at a rolling rate of 85.0 to 93.5% within 48 hours. Run,
The temperature elevation temperature in the finish annealing is in the range of 20 to 400 ° C./s,
The steel sheet is in mass%,
Si: 2.7 to 3.6%
Al: 0.5 to 1.4%
Si + Al: 3.5 to 4.1%
Mn: 0.1 to 1.5%
C: 0.0010 to 0.0040%
N: 0.0001 to 0.0030%
S: 0.0001 to 0.0018%
Ti: 0.0001 to 0.0030%, and
P satisfying the following formula (1)
And the balance has a component consisting of Fe and impurities,
The manufacturing method of the non-oriented electrical steel sheet which makes final board thickness t (mm) 0.15 or more and 0.28 or less.

The cooling rate of the steel plate after annealing is a cooling rate up to 100 ° C.,
The method for producing a non-oriented electrical steel sheet according to claim 5, wherein a temperature increase rate during the finish annealing is a temperature increase rate up to 850 ° C.   The non-oriented electrical steel sheet according to claim 5 or 6, wherein the steel sheet further contains 0.005 to 0.100 mass% of at least one of Sn and Sb instead of a part of the remaining Fe. Manufacturing method.   The steel sheet according to any one of claims 5 to 7, further containing 0.02 to 0.20 mass% of at least one of Ni and Cu in place of a part of the remaining Fe. A method for producing a non-oriented electrical steel sheet. Iron loss W10 / 800 (W / kg), magnetic flux density B50 (T), yield stress YS (MPa), and steel plate crystal grain size D (μm) satisfy the following formulas (2) to (5). The manufacturing method of the non-oriented electrical steel sheet according to any one of claims 5 to 8.

The manufacturing method of the non-oriented electrical steel sheet according to any one of claims 5 to 9, which is used for a motor core.