JP2008127612A - Non-oriented electromagnetic steel sheet for divided core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-oriented electromagnetic steel sheet having optimal magnetic properties for a divided core of a motor and a transformer. <P>SOLUTION: A hot-rolled plate of the non-oriented electromagnetic steel sheet has a composition comprising, by mass%, 0.005% or less C, 2 to 4% Si, 1% or less Mn, 0.2 to 2% Al, 0.003 to 0.2% Sn, and the balance Fe with unavoidable impurities. The non-oriented electromagnetic steel sheet with a thickness of 0.1 to 0.3 mm is manufactured by the steps of: cold-rolling the hot-rolled plate before and after an intermediate annealing step; and subsequently recrystallization-annealing the sheet. Then, the non-oriented electromagnetic steel sheet for the divided core has (1) a recrystallized structure in which a mean crystal grain size is 40 to 200 μm and (2) the magnetic properties in which magnetic flux density B<SB>50</SB>(C) in a direction of 90 degrees (C direction) with respect to a rolling direction (L direction) and magnetic flux density B<SB>50</SB>(X) in a direction of 45 degrees (X direction) with respect to the rolling direction (L direction) satisfy the expression (1): B<SB>50</SB>(C)/B<SB>50</SB>(X)>1.03. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a non-oriented electrical steel sheet used as a core (iron core) material for a motor or a transformer.

  In recent years, interest in electric vehicles has increased from the viewpoints of environmental protection and energy saving, and drive motors are required to be capable of being driven at a frequency of 400 to several kHz along with high-speed rotation and miniaturization.

  For this reason, in the non-oriented electrical steel sheet that is the core material of the motor, in order to reduce eddy current loss, the sheet thickness is reduced, the specific resistance is increased, and further the steel sheet strength (increasing the rotor rigidity) is improved. Therefore, it is necessary to increase the amount of Si and the amount of Al. Furthermore, non-oriented electrical steel sheets are also required to have a high magnetic flux density in order to improve the initial torque of the motor.

  Motor cores are manufactured by stamping non-oriented electrical steel sheets. Recently, from the viewpoint of improving punching yield and reducing the copper loss by increasing winding efficiency, the motor core and individual teeth are individually manufactured. Tend to be composed of split cores. And since a magnetic field is applied to the teeth part of a division | segmentation core in a length direction and a width direction (core back), it is requested | required that magnetic flux density is high.

  Usually, when one motor core is punched from a non-oriented electrical steel sheet, the magnetic properties of the non-oriented electrical steel sheet include the rolling direction of the steel sheet (coil longitudinal direction, hereinafter referred to as “L direction”), L. There is a difference (anisotropy) between the direction perpendicular to the direction (coil width direction, hereinafter referred to as “C direction”) and the L direction and 45 ° direction (hereinafter also referred to as “X direction”). It is desired to be small (see Patent Documents 1 to 6).

  However, when punching the split core, it is only necessary to punch through the teeth portion along the direction of excellent magnetic properties. Therefore, when using a non-oriented electrical steel sheet exclusively for the split core, the L direction, the C direction, and the X direction The anisotropy of the magnetic characteristics in is not necessarily small. In other words, the larger the magnetic property anisotropy, that is, the improvement of the magnetic properties in the L direction and the C direction at the expense of the magnetic properties in the X direction is required in the tooth portion of the divided core in the design of the divided core. It is preferable in that the magnetic characteristics can be secured.

Japanese Patent Laid-Open No. 2001-49402 Japanese Patent Laid-Open No. 2001-164343 JP 2006-45613 A JP 2006-45641 A JP 2006-144036 A JP 2006-199999 A

  The present inventor has a phenomenon that, in a non-oriented electrical steel sheet, in order to enhance magnetic properties, when the thickness of the steel sheet is reduced and the Si content and / or Al content is increased, the magnetic flux density anisotropy is reduced. I noticed. That is, the magnetic flux density in a specific direction, for example, the L direction or the C direction is reduced, and a desired magnetic flux density cannot be obtained. As a result, a non-oriented electrical steel sheet having such magnetic characteristics is suitable for a split core. Encountered the problem of not.

  Then, an object of this invention is to provide the non-oriented electrical steel sheet which has the optimal magnetic characteristic for the division | segmentation cores of a motor or a transformer.

  The inventor of the present invention is a non-oriented electrical steel sheet having a thickness of 0.1 to 0.3 mm containing Si: 2 to 4% and Al: 0.2 to 2% by mass%. Add 003 to 0.2% to increase the Goss-oriented crystal grains and improve the magnetic properties (magnetic flux density) in the L and C directions, ensuring optimum magnetic properties for the split core We studied earnestly about the technique to do. As a result, the following knowledge was obtained.

(X) The difference in magnetic properties (anisotropy) in the L, C, and X directions is the distribution of the rolling reduction in cold rolling, the crystal grain size before and after intermediate annealing, and the crystal after recrystallization annealing (finish annealing). Although it is closely related to the particle diameter, if these are finally controlled, it is possible to secure a required magnetic flux density B _{50 having} a large anisotropy (magnetic flux density [T] obtained with a magnetizing force of 5000 A / m). it can.

(Y) connecting the magnetic properties of the L direction and the C direction and to reduce the magnetic flux density B ₅₀ in the X direction, because there is a tendency that the magnetic flux density B ₅₀ in the L direction and C direction are improved, the magnetic properties of the X-direction This is an important index for evaluating the magnetic properties of the non-oriented electrical steel sheet for the split core, and must be maintained within a predetermined ratio range in relation to the magnetic properties in the C direction.

  This invention was made | formed based on the said knowledge, and the summary is as follows.

(1) By mass%, C: 0.005% or less, Si: 2-4%, Mn: 1% or less, Al: 0.2-2%, Sn: 0.003-0.2% The thickness of the hot-rolled sheet consisting of Fe and inevitable impurities is cold-rolled twice with intermediate annealing, followed by recrystallization annealing. A grain-oriented electrical steel sheet,
(I) having a recrystallized structure having an average crystal grain size of 40 to 200 μm, and
(Ii) Magnetic flux density B ₅₀ (C) in the rolling direction (L direction) and 90 ° direction (C direction), and magnetic flux density B ₅₀ (X in the rolling direction (L direction) and 45 ° direction (X direction). ) Has a magnetic property satisfying the following formula (1): a non-oriented electrical steel sheet for split cores.
B ₅₀ (C) / B ₅₀ (X)> 1.03 (1)

(2) In the magnetic characteristics, the magnetic flux density B ₅₀ (L) in the rolling direction (L direction) satisfies the following formula (2): steel sheet.
B ₅₀ (L) /Bs≧0.82 (2)
Where Bs: saturation magnetic flux density

(3) The non-oriented electrical steel sheet for split core according to (1) or (2), wherein the iron loss W _10/800 is 40 W / kg or less in the magnetic characteristics.

  (4) The non-oriented electrical steel sheet for split core according to any one of (1) to (3), wherein the hot-rolled sheet is subjected to hot-rolled sheet annealing.

  (5) The non-oriented electrical steel sheet for split core according to any one of (1) to (4), wherein the intermediate annealing is performed at a high temperature of 900 ° C or higher.

  (6) The non-oriented electrical steel sheet for split core according to any one of (1) to (5), wherein a rolling reduction in cold rolling after the intermediate annealing is 40 to 75%.

  (7) The non-oriented electrical steel sheet for split core according to any one of (1) to (6), wherein the cold rolling after the intermediate annealing is lever rolling.

  (8) The non-oriented electrical steel sheet for split core according to any one of (1) to (7), wherein a temperature increase rate is 100 to 5000 ° C./second in the recrystallization annealing.

  ADVANTAGE OF THE INVENTION According to this invention, the non-oriented electrical steel sheet which has the optimal magnetic characteristic as an object for the split cores of a motor or a transformer can be provided. Further, according to the present invention, since the split core can be designed and punched according to the shape of the split core and / or the magnetic characteristics required for the tooth portion of the split core, the utilization of the non-oriented electrical steel sheet Increase.

The present invention contains, in mass%, C: 0.005% or less, Si: 2-4%, Mn: 1% or less, Al: 0.2-2%, Sn: 0.003-0.2% Then, a hot-rolled sheet consisting of Fe and unavoidable impurities is subjected to cold rolling twice with intermediate annealing, and then subjected to recrystallization annealing, and is divided into a thickness of 0.1 to 0.3 mm. Non-oriented electrical steel sheet for core,
(I) having a recrystallized structure having an average crystal grain size of 40 to 200 μm, and
(Ii) Magnetic flux density B ₅₀ (C) in the rolling direction (L direction) and 90 ° direction (C direction), and magnetic flux density B ₅₀ (X in the rolling direction (L direction) and 45 ° direction (X direction). ) Has a magnetic property satisfying the following formula (1).
B ₅₀ (C) / B ₅₀ (X)> 1.03 (1)

B ₅₀ (C) is a magnetic flux density (unit: T) in the C direction measured by being magnetized at 5000 A / m in the C direction on the steel plate surface. B ₅₀ (X) is the magnetic flux density in the X direction measured by magnetization at 5000 A / m in the X direction on the steel plate surface. B ₅₀ (L) is the magnetic flux density in the L direction measured by magnetizing at 5000 A / m in the L direction.

  First, the reason for limiting the component composition of the hot-rolled sheet will be described. Hereinafter, “%” means mass%.

  C is an element that reinforces the steel sheet. However, C is an element harmful in terms of magnetic properties and is preferably reduced as much as possible. Therefore, C is limited to 0.005% or less. Preferably, it is 0.003% or less.

Since Si is an element that increases the electrical resistance of the steel sheet and reduces iron loss, it contains 2% or more. When the content exceeds 4%, the steel sheet is embrittled, and since the required magnetic flux density B ₅₀ is not obtained, and 4% the upper limit of Si.

  Mn is an element that fixes S as MnS at the time of hot rolling and prevents steel plate ear cracks during hot rolling. The solute Mn increases the electrical resistance of the steel sheet and reduces the iron loss. However, if Mn is too much, crystal grain growth is inhibited, so the upper limit of Mn is set to 1%.

  Al, like Si, is an element that increases the electrical resistance of the steel sheet and reduces the iron loss, and therefore contains 0.2% or more. However, since the anisotropy of the magnetic flux density tends to decrease as the Al content increases, various measures adopted in the present invention are required. On the other hand, if the content exceeds 2%, there is a concern about the problem of addition cost and a decrease in saturation magnetic flux density, so the upper limit was made 2%.

  Sn increases the number of Goss orientation grains in the recrystallized structure of non-oriented electrical steel sheets containing Si: 2 to 4% and Al: 0.3 to 2%. In order to improve (density), it is necessary to contain 0.003% or more. On the other hand, even if the content exceeds 0.2%, the above improvement effect is saturated, and surface defects increase due to hot brittleness, so the upper limit was made 0.2%.

  In the present invention, in addition to the above elements, S, P, N, O, Cu, Ni, Cr, Ca, REM (rare earth elements) and the like are inevitable impurities, and the mechanical and magnetic properties of the present invention are not impaired. You may contain. However, as in the past, it is preferable that S, N, and O as impurities are small. Each of these components is preferably 0.003% or less, 0.0025% or less, and 0.003% or less.

  Further, the ranges where it is confirmed that the target anisotropy is not inhibited are Cu <0.2%, Ni <0.1%, Cr <0.1%, Ca <0.01%, Nb <0. Since 0.002%, Ti <0.003%, and REM <0.01%, it is desirable to suppress these elements within the above ranges. Note that Sb should not be added because it reduces anisotropy. When Sb is inevitably contained, it is preferably less than 0.001%.

  The hot-rolled sheet having the above composition is subjected to hot-rolled sheet annealing or not, and subjected to cold rolling twice with intermediate annealing, and then subjected to finish annealing (recrystallization annealing), and the average A recrystallized structure having a crystal grain size of 40 to 200 μm is formed.

In the present invention, based on the above-described knowledge (x), the average crystal grain size of the recrystallized structure is limited to 40 to 200 μm. When the average grain size is large, the iron loss characteristics are improved, but the anisotropy of the magnetic flux density tends to be small. From this tendency, the average crystal grain size should be small, but if it is less than 40 μm, the desired high-frequency iron loss W _10/800 cannot be obtained.

On the other hand, when the average crystal grain size exceeds 200 μm, the anisotropy of the magnetic flux density becomes small, and it becomes difficult to secure the desired B ₅₀ (C) / B ₅₀ (X) aimed by the present invention. In order to further improve the high-frequency iron loss, the average crystal grain size of the recrystallized structure is more preferably 80 to 200 μm.

  The average crystal grain size was obtained by counting and averaging the number of crystal grain boundaries intersecting the line segment in the L direction in the structure obtained by observing the cross section of the steel sheet with an optical microscope.

The present invention is characterized in that a non-oriented electrical steel sheet having a thickness of 0.1 to 0.3 mm having a recrystallized structure having an average crystal grain size of 40 to 200 μm has a magnetic property satisfying the following formula (1). .
B ₅₀ (C) / B ₅₀ (X)> 1.03 (1)

B ₅₀ (C), B ₅₀ (X), and B ₅₀ (L) are as described above.

B ₅₀ (X) in the X direction is a process in which B ₅₀ (L) in the L direction transitions to B ₅₀ (C) in the C direction (usually B ₅₀ (L)> B ₅₀ (C)). Magnetic flux density B ₅₀ to be connected. The inventor paid attention to B ₅₀ (X) in the X direction.

_{B 50 (C) / B 50} (X) is focused on the X-direction of the B ₅₀ (X), the difference between the B ₅₀ (C) and B ₅₀ (X), an indicator for evaluating in their ratio, Defining this ratio within a predetermined range means that the difference between B ₅₀ (C) and B ₅₀ (X) is suppressed within the predetermined range.

The present inventor has recognized that this is extremely important in determining the appropriateness of the non-oriented electrical steel sheet for the split core for the following reasons, and the non-direction for the split core. "B ₅₀ (C) / B ₅₀ (X)" was introduced as an index for evaluating the magnetic properties of the heat-resistant electrical steel sheet.

  1 (a) and 1 (b) show how the split core is punched. FIG. 1A shows an aspect in which the tooth portion of the split core is set in the C direction (90 degrees with respect to the L direction) and punching is performed with the highest priority on the punching yield (hereinafter sometimes referred to as “punching aspect A”). In FIG. 1B, the tooth portion of the split core is set in the L direction, and punching is performed with emphasis on the core characteristics (magnetic flux density of the tooth portion) as well as the punching yield (hereinafter referred to as “punching mode B”). .)

  Recently, in the field of electric motors, in addition to the conventional integrated core, the number of cases using a split core is increasing from the viewpoint of improving the punching yield and improving copper loss by increasing the efficiency of winding. In many cases, the split core is punched in the punching mode A or the punching mode B with respect to the rolling direction (L direction) of the magnetic steel sheet coil wound in a coil shape after rolling.

  In general, non-oriented electrical steel sheets manufactured industrially have inferior magnetic properties (magnetization characteristics, iron loss characteristics) in the C direction and X direction compared to magnetic characteristics (magnetization characteristics, iron loss characteristics) in the L direction. Yes, the magnetic characteristics in the C direction or the X direction influence the magnetic characteristics of the entire split core iron core.

  The flux flow of the split core iron core includes a transitional X direction in the middle of the magnetic flux rotating from the L direction to the C direction in both cases of the split core punched in the punching mode A and the punching mode B. Although there is a magnetic flux flow, in the split core, the transitional magnetic flux region in the X direction is small, and it is estimated that the degree of influence on the magnetic properties of the split core iron core is small.

In other words, the present inventor can control the magnetic properties of the entire split core iron core by designing the material so that the ratio of the magnetic properties in the C direction to the magnetic properties in the X direction: B ₅₀ (C) / B ₅₀ (X) is increased. I thought it could be improved.

  The appropriate balance of magnetic characteristics in the L direction and the C direction is determined by the size and shape of the split core piece.

Since defining B ₅₀ (C) / B ₅₀ (X) within a predetermined range is to limit the anisotropy of the magnetic properties of the non-oriented electrical steel sheet to a predetermined range, a split core is designed. At this time, the shape of the split core and the punching mode can be designed in consideration of the improvement of the magnetic characteristics of the entire split core iron core.

Therefore, B ₅₀ (C) / B ₅₀ (X) is a very important index for judging the accuracy of the non-oriented electrical steel sheet for the split core. In the present invention, B ₅₀ (C) / B ₅₀ (X) is defined by the above formula (1). That is, in the present invention, if B ₅₀ (L) / B ₅₀ (X) is 1.03 or less, the magnetic property anisotropy is reduced, and the required magnetic properties in the L and C directions are reduced. I can't get it.

  The above formula (1) is a relational expression that is established when the thickness of the non-oriented electrical steel sheet is 0.1 to 0.3 mm, and is applied to the non-oriented electrical steel sheet whose thickness exceeds the above range. It is not possible.

For example, when the plate thickness exceeds 0.3 mm, B ₅₀ (C) / B ₅₀ (X) increases rapidly, which is satisfactory as a magnetic property for a split core, but is not suitable for a high frequency core. It is.

According to the present invention, even if the plate thickness is thin (the thin the sheet, the magnetic property anisotropy becomes small), and B ₅₀ (C) / B ₅₀ (X) is large (ie, the magnetic property anisotropy). As a result, we have developed non-oriented electrical steel sheets for split cores.

That is, the present invention introduces an index “B ₅₀ (C) / B ₅₀ (X)” indicating the anisotropy of the magnetic properties in order to evaluate the magnetic properties of the non-oriented electrical steel sheet for the split core. The basic idea is to define the lower limit.

When designing a split core, the magnetic flux density B ₅₀ (L) in the L direction that does not appear in the above equation (1) is also an important index. Since the value of B ₅₀ (L) naturally changes depending on the composition of the steel plate, the ratio with the saturation magnetic flux density Bs is adopted: B ₅₀ (L) / Bs (crystal orientation index). Therefore, it is preferable to evaluate the magnetic properties of the non-oriented electrical steel sheet.

In order to obtain a split core having better magnetic properties, it is necessary to design the material so that B ₅₀ (L) / Bs satisfies the following formula (2).
B ₅₀ (L) /Bs≧0.82 (2)

When the crystal orientation index B ₅₀ (L) / Bs is less than 0.82, the magnetic properties as a split core are insufficient.

  The present invention requires that the hot-rolled sheet is annealed or not, subjected to cold rolling twice with intermediate annealing, and then subjected to finish annealing (recrystallization annealing). Therefore, next, preferable manufacturing requirements will be described.

Hot-rolled sheet annealing can be performed or not performed. However, when hot-rolled sheet annealing is performed, the magnetic flux density B ₅₀ (L) can be improved by about 0.01T. The annealing temperature is preferably a normal 850 ° C. or higher.

  There is no special restriction condition for cold rolling (primary cold rolling) after hot-rolled sheet annealing, but subsequent intermediate annealing, cold rolling (secondary cold rolling) after intermediate annealing and finish annealing (recrystallization) Annealing is important.

In the present invention, the hot-rolled sheet is subjected to cold rolling twice with intermediate annealing, whereby the ratio of the magnetic flux density B ₅₀ (C) in the C direction and the magnetic flux density B ₅₀ (X) in the X direction: B ₅₀ (C) / B ₅₀ (X), that is, the feature is to increase the anisotropy of the magnetic properties.

  In particular, by performing cold rolling in two steps, primary cold rolling and secondary cold rolling, the rolling reduction per cold rolling can be greatly increased compared to the usual cold rolling method. In addition, the selection range of the rolling reduction can be increased in combination with the thickness of the hot rolled sheet and the thickness of the product sheet, and the crystal orientation can be controlled under the optimum rolling ratio. it can.

In particular, it was found that the rolling reduction ratio in the secondary cold rolling, that is, the secondary cold rolling ratio, has a dominant effect on the value of the index B ₅₀ (C) / B ₅₀ (X).

The intermediate annealing is desirably performed at a high temperature of 900 ° C. or higher in order to sufficiently grow crystal grains. By performing the intermediate annealing at a high temperature, the magnetic flux densities B ₅₀ (L) and B ₅₀ (C) can be improved.

In the present invention, the rolling reduction in cold rolling (secondary cold rolling) after intermediate annealing is preferably 40 to 75% from the viewpoint of increasing the magnetic property anisotropy. The maximum anisotropy B ₅₀ (C) / B ₅₀ (X) is obtained at a reduction ratio of about 60%, and the peak reduction ratio is about 60%. The anisotropy B ₅₀ (C) / B ₅₀ (X) gradually decreases. If the rolling reduction is less than 40% and more than 75%, the magnetic flux density anisotropy for the desired split core of the present invention cannot be obtained.

In a non-oriented electrical steel sheet with increased magnetic property anisotropy, a split core having a tooth portion with a high magnetic flux density can be obtained by punching the split core with the tooth portion set in the L direction. By adjusting the rolling reduction in skin pass rolling, the ratio of B _{50 in} the C direction and the X direction can be adjusted, so that it is possible to produce a non-oriented electrical steel sheet according to the magnetic flux density required in the design of the split core. it can.

The secondary cold rolling is preferably lever rolling. By this rolling, B ₅₀ (L) can be improved by about 0.02 T as compared with so-called tandem rolling of unidirectional rolling. The lever rolling can be carried out by ordinary Sendzimir mill rolling or the like.

In finish annealing (recrystallization annealing), it is preferable to rapidly heat at a temperature increase rate of 100 to 5000 ° C./second in a temperature range of at least 600 to 700 ° C. This rapid heating can increase Goss orientation grains and in particular improve B ₅₀ (C) / B ₅₀ (X). If the rate of temperature increase is less than 100 ° C./second, the above improvement effect is small, and if it is 5000 ° C./second or more, it is impossible in terms of industrial equipment cost.

The iron loss W _10/800 is preferably 40 W / kg or less. This is because it is applied to a high-speed rotation specification for making a compact motor core.

  Next, examples of the present invention will be described. The conditions of the examples are one example of conditions adopted for confirming the feasibility and effects of the present invention, and the present invention is limited to this one example of conditions. Is not to be done. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example 1)
The component composition was adjusted while melting steel in a vacuum melting furnace, and an ingot having the component composition shown in Table 1 was cast. This was heated to 1070 ° C. and hot-rolled to obtain a hot-rolled sheet having a thickness of 2.10 mm. Next, annealing was performed in a N ₂ atmosphere at 900 ° C. for 120 seconds. After pickling, cold rolling was performed to obtain a cold-rolled sheet having a sheet thickness of 0.40 mm (81% reduction).

Intermediate annealing was performed by soaking at 1000 ° C. for 3 seconds in an H ₂ atmosphere. Subsequently, the sheet was secondarily cold rolled to a thickness of 0.20 mm (50% reduction).

The finish annealing was soaked at 1000 ° C. for 10 seconds in an H ₂ atmosphere, and the cold rolled sheet was subjected to recrystallization annealing. A 55 mm square was punched out, and the magnetic characteristics for each angle were measured by SST. The average crystal grain size was in the range of 100 to 110 μm. The obtained results are shown in Table 1.

The saturation magnetic flux density Bs was measured with a vibrating sample magnetometer. W _10/800 is an iron loss at a magnetic flux density of 1.0 T and a frequency of 800 Hz, and is an average of measured values in the L direction and the C direction.

  Example 2 and the following also conform to these symbols.

  An anisotropy of excellent magnetic flux density could be obtained when the Sn amount was within the range of the present invention.

(Example 2)
In mass%, C: 0.0010%, Si: 2.3%, Mn: 0.2%, Al: 1.95%, Sn: 0.03%, S: 0.0001%, N: 0.00. A hot-rolled sheet having a thickness of 1.6 mm containing 0008%, O: 0.002%, and P: 0.025% is subjected to primary cold rolling (tandem rolling) to a thickness of 0.40 mm (75% reduction). Then, heat treatment was performed at an intermediate annealing temperature shown in Table 2 for 10 seconds in an H ₂ atmosphere. Next, secondary cold rolling (tandem rolling) was performed to obtain a sheet thickness of 0.12 mm (70% reduction).

Finish annealing was performed at a temperature shown in Table 2 by soaking in an H ₂ atmosphere for 20 seconds. After punching out to 55 mm square, the magnetic characteristics for each angle were measured by SST, and the average crystal grain size was also measured. The obtained results are shown in Table 2.

When the intermediate annealing temperature is high within the range of the present invention, it is shown in Experiment No. 1 that magnetic properties having excellent magnetic flux density in the L direction and C direction are obtained for the split core. It can be seen from 1-5. For the average crystal grain size after finish annealing, Experiment No. From 6 to 12, it can be seen that high-frequency iron loss W _10/800 is obtained simultaneously with excellent anisotropy B ₅₀ (C) / B ₅₀ (X) within the scope of the present invention.

(Example 3)
In terms of mass%, C: 0.003%, Si: 3.5%, Mn: 0.6%, Al: 0.3%, Sn: 0.05%, and other inevitable ingredients, Cu: 0.00%. A slab containing 15%, Ni: 0.01%, Cr: 0.01%, Ti: 0.002%, Mo: 0.002%, P: 0.02% is heated to 1000 ° C. A hot rolled sheet having a thickness of 2.7 mm was obtained. The hot-rolled sheet was annealed at 1050 ° C. for 150 seconds in an N ₂ atmosphere, then pickled and subjected to primary cold rolling (tandem rolling).

Intermediate annealing was performed at 950 ° C. for 10 seconds in an H ₂ atmosphere, and then secondary cold rolling at the rolling reduction shown in Table 3 was performed with a lever mill to obtain a plate thickness of 0.28 mm. Then, finish annealing was performed by soaking at 970 ° C. for 8 seconds in an H ₂ atmosphere. The temperature increase rate in the finish annealing was 12 ° C./second. After the Epstein sample was cut out, the magnetic properties and crystal grain size were measured for each angle. The obtained results are shown in Table 3.

  When the secondary cold rolling rate is within the range of the present invention, anisotropy suitable for the split core is developed.

Example 4
Experiment No. used in Example 3 A secondary cold-rolled plate having a thickness of 0.28 mm was rapidly heated with an induction heating device. The heating rate was changed from room temperature to 1030 ° C. as shown in Table 4. The atmosphere was 30% H ₂ + 70% N ₂ and soaking was performed at 1030 ° C. for 10 seconds. Next, the Epstein sample was cut out, and the magnetic characteristics and crystal grain size were measured for each angle. The crystal grain size was all 190 μm. Table 4 shows the obtained results.

From Table 4, when the heating rate is increased, the anisotropy of the magnetic flux density is improved. Especially when the heating rate is 100 ° C./second or more, excellent B ₅₀ (C) / B ₅₀ (X) is obtained. I understood that.

  As described above, according to the present invention, it is possible to provide a non-oriented electrical steel sheet that has optimum magnetic characteristics for a split core of a motor or a transformer and has high utilization. Therefore, the present invention has great applicability in the electrical equipment manufacturing industry using non-oriented electrical steel sheets as raw materials.

It is a figure which shows the punching aspect of a split core. (A) shows a mode in which the tooth portion of the split core is set in the C direction (90 ° C. in the L direction) and punched, and (b) shows a mode in which the tooth portion of the split core is set in the L direction and punched. Indicates.

Explanation of symbols

1 split core 2 teeth

Claims (8)

In mass%, C: 0.005% or less, Si: 2-4%, Mn: 1% or less, Al: 0.2-2%, Sn: 0.003-0.2%, the balance being Non-directional electromagnetic with a thickness of 0.1 to 0.3 mm manufactured by subjecting a hot-rolled sheet made of Fe and inevitable impurities to cold rolling twice with intermediate annealing and then recrystallization annealing A steel plate,
(I) having a recrystallized structure having an average crystal grain size of 40 to 200 μm, and
(Ii) Magnetic flux density B ₅₀ (C) in the rolling direction (L direction) and 90 ° direction (C direction), and magnetic flux density B ₅₀ (X in the rolling direction (L direction) and 45 ° direction (X direction). ) Has a magnetic property satisfying the following formula (1): a non-oriented electrical steel sheet for split cores.
B ₅₀ (C) / B ₅₀ (X)> 1.03 (1) 2. The non-oriented electrical steel sheet for split core according to claim 1, wherein a magnetic flux density B ₅₀ (L) in a rolling direction (L direction) satisfies the following formula (2) in the magnetic characteristics.
B ₅₀ (L) /Bs≧0.82 (2)
Where Bs: saturation magnetic flux density 3. The non-oriented electrical steel sheet for split core according to claim 1, wherein an iron loss W _10/800 is 40 W / kg or less in the magnetic characteristics.   The non-oriented electrical steel sheet for split core according to any one of claims 1 to 3, wherein the hot-rolled sheet is subjected to hot-rolled sheet annealing.   The non-oriented electrical steel sheet for a split core according to any one of claims 1 to 4, wherein the intermediate annealing is performed at a high temperature of 900 ° C or higher.   The non-oriented electrical steel sheet for split core according to any one of claims 1 to 5, wherein a rolling reduction in cold rolling after the intermediate annealing is 40 to 75%.   The non-oriented electrical steel sheet for split core according to any one of claims 1 to 6, wherein the cold rolling after the intermediate annealing is lever rolling.   The non-oriented electrical steel sheet for split core according to any one of claims 1 to 7, wherein in the recrystallization annealing, a temperature rising rate is 100 to 5000 ° C / second.

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