JP6557526B2 - Soft magnetic steel sheet, laminated steel sheet using the same, and method for producing soft magnetic steel sheet - Google Patents

Description

  INDUSTRIAL APPLICABILITY The present invention is an electronic component such as an automobile, a train, and a ship, and is used as a soft core useful for a case or cover such as a solenoid or a relay used for direct current, or an iron core, or a magnetic core such as a motor or transformer used for alternating current. Regarding a soft magnetic steel sheet used as a material of a magnetic member, for example, a soft magnetic steel sheet that is manufactured by press molding and can exhibit excellent press formability and good magnetic characteristics in a soft magnetic member that requires magnetic characteristics, and The present invention relates to a laminated steel plate using the same and a method for producing a soft magnetic steel plate.

  In recent years, the need for improving the fuel efficiency of automobiles has become stronger, and electrical components used in engines, transmissions, and the like are desired to have further improved performance, such as responsiveness, power saving, and downsizing. For this purpose, it is effective that the magnetic properties are easily magnetized and the coercive force is small.

  Furthermore, there is a great need for a reduction in manufacturing costs. In other words, members that form magnetic circuits, such as cases and covers that form the outer shell of solenoids, and iron cores, instead of conventional methods of cold forging and cutting wires and steel bars, are pressed into steel plates. Thus, a method for producing a member shape has attracted attention.

  For example, Patent Document 1 discloses a steel material for electrical parts that has a pure iron-based component composition similar to that of the soft magnetic steel sheet according to the present invention and is excellent in cold forgeability and electrical conductivity. However, this steel material for electrical parts relates to a wire manufactured by drawing, and there is no description about a steel plate.

  Patent Document 2 discloses a hot-rolled steel sheet excellent in formability and magnetic properties. However, the hot-rolled steel sheet cannot be used as an electromagnetic component as it is because of its poor surface condition. Moreover, since the crystal grain size is too large, there is a concern about rough skin after bending.

  Patent Document 3 discloses a cold-rolled steel sheet for a TV CRT mask frame having excellent magnetic properties and workability. However, this cold-rolled steel sheet for a TV CRT mask frame is premised on containing a substantial amount of impurity elements such as Cu, Sn, Ni, Cr, etc., and is premised on a pure iron-based component composition. This is a technology that is originally different from the soft magnetic steel sheet.

Japanese Patent Laid-Open No. 2003-226938 JP 2010-53387 A Japanese Patent Laid-Open No. 11-50207

  This invention is made | formed in view of such a situation, The objective is to provide the soft magnetic steel plate which has the outstanding magnetic characteristic, the laminated steel plate using the same, and the manufacturing method of a soft magnetic steel plate. is there.

  Another object of the present invention is to provide a soft magnetic steel sheet having excellent formability, a laminated steel sheet using the same, and a method for producing a soft magnetic steel sheet.

  Another object of the present invention is to provide a soft magnetic steel sheet having excellent resistance to rough skin, a laminated steel sheet using the same, and a method for producing the soft magnetic steel sheet.

  Another object of the present invention is to provide a soft magnetic steel sheet having excellent machinability, a laminated steel sheet using the same, and a method for producing the soft magnetic steel sheet.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification.

The first invention according to the present invention is:
Ingredient composition is mass%,
C: 0.001 to 0.02%,
Si: 0 to 0.05%,
Mn: 0.05 to 0.5%
P: 0 to 0.02%,
S: 0 to 0.1%,
Al: 0 to 0.01%,
Cr: 0 to 0.1%,
N: 0 to 0.005%
And the balance is a soft magnetic steel plate made of iron and inevitable impurities,
The average crystal grain size is more than 50 μm and not more than 150 μm,
Furthermore, the ratio Ka / Kb between the KAM value Ka of the soft magnetic steel sheet and the KAM value Kb after annealing the soft magnetic steel sheet at 850 ° C. for 3 hours is 1.0 to 1.5. It is a soft magnetic steel plate.
Here, the “KAM value” means a “Kernel Average Mission value”.

According to a second aspect of the present invention, in the first aspect,
It is a soft magnetic steel plate having a plate thickness of 0.8 to 4.0 mm.

According to a third aspect of the present invention, in the first aspect,
It is a soft magnetic steel plate having a plate thickness of 0.3 to 1.0 mm.

According to a fourth aspect of the present invention, in any one of the first to third aspects of the invention,
It is a soft magnetic steel plate in which the content of S is S: 0.015 to 0.1% by mass.

According to a fifth aspect of the present invention, in any one of the first to third aspects of the invention,
It is a soft magnetic steel plate in which the content of S is S: 0 to 0.06% by mass.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the invention,
Furthermore, Mn / S mass ratio is 3-20,
The average particle size of the MnS precipitate is 0.05-4 μm, and
The number density of MnS precipitates having a particle size of 0.2 μm or more is 0.02 to 0.5 / μm ² .
It is a soft magnetic steel plate.

  A seventh invention according to the present invention is a laminated steel plate, wherein two or more soft magnetic steel plates according to the first to sixth inventions are laminated.

The eighth aspect of the invention relates to
A hot rolling step of hot rolling a steel material having the component composition of any one of the first, fourth and fifth inventions into a hot rolled sheet;
A rough cold rolling process in which the hot-rolled sheet is cold-rolled at a reduction ratio R1: 30 to 70% to obtain a cold-rolled sheet;
A softening annealing step in which the cold-rolled sheet is held at a softening annealing temperature T1 ° C. and a softening annealing time H1 second so as to satisfy the following formula 1,
A method for producing a soft magnetic steel sheet, comprising:
Formula 1: 270 ≦ [{100−R1 + 0.2 × (273 + T1)} ² + H1 × exp {−10 / (273 + T1)}] ^1/2 ≦ 340
However, it is 750 degreeC <= T1 <= 860 degreeC.

According to a ninth aspect of the present invention, in the eighth aspect,
Furthermore, a finish cold rolling step of cold rolling the softened annealed plate at a rolling reduction R2: 0.1 to 3%;
Is a method for producing a soft magnetic steel sheet.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  According to one embodiment of the present invention, a soft magnetic steel sheet having excellent magnetic properties can be provided.

  The requirements for obtaining high magnetism for soft magnetic steel sheets are to control the additive elements and impurities in the proper range as the component composition, to sufficiently remove strain (dislocation due to plastic deformation) in the magnetically annealed member, It is important to have a crystal grain size. On the other hand, as for the moldability, it is important that the elongation in the tensile test is large as a basic characteristic.

  Therefore, the present inventors have examined in detail the relationship between the manufacturing conditions and the microstructure, and the relationship between the microstructure, formability, and magnetic properties of the steel sheets having various component compositions. As a result, it has been found that by optimizing the crystal grain size and strain amount of the steel sheet, the formability can be improved and the magnetic properties can be improved. Based on the above findings, further studies have been made and the present invention has been completed.

  Hereinafter, the structure characterizing the soft magnetic steel sheet according to the present invention will be described first.

[Structure of soft magnetic steel sheet]
As described above, the soft magnetic steel sheet according to the present invention is characterized in that the crystal grain size and strain amount are controlled.

<Average crystal grain size: more than 50 μm and less than 150 μm>
The average crystal grain size of the soft magnetic steel sheet has a great influence on the magnetic properties. If the average crystal grain size is too small, the coercive force and the magnetic permeability are deteriorated, so that it exceeds 50 μm, preferably 60 μm or more, more preferably 70 μm or more. It was. On the other hand, if the average crystal grain size is too large, rough skin after forming or bending and burrs after punching are likely to occur, and even when combined with finish rolling described later, for example, skin pass rolling, rough skin and burrs are prevented. Therefore, the thickness is set to 150 μm or less, preferably 140 μm or less, and more preferably 130 μm or less.

<Ratio Ka / Kb of KAM value Ka of the soft magnetic steel sheet and KAM value Kb after annealing the soft magnetic steel sheet at 850 ° C. for 3 hours: 1.0 to 1.5>
The KAM (Kernel Average Misoration) value is an index related to the amount of plastic strain when the material is plastically deformed. In the present invention, the soft magnetic steel sheet is annealed at 850 ° C. for 3 hours to increase the crystal grain size to a certain level and the KAM value Kb in the state where the plastic strain is substantially eliminated is used as a reference. The strain amount of the soft magnetic steel sheet was relatively evaluated using the magnification Ka / Kb of the KAM value Ka of the soft magnetic steel sheet. When trying to increase the magnetic properties by sufficiently coarsening the crystal grains by soft annealing after cold rolling, rough surface after bending and burrs after punching are likely to occur. By performing skin pass rolling, rough skin and burrs can be suppressed. However, if the amount of plastic strain introduced by skin pass rolling becomes excessive, that is, if the KAM value becomes excessive, the magnetic properties deteriorate, so the upper limit of Ka / Kb is 1.5, preferably 1.4, more preferably Was 1.3. On the other hand, considering the rough skin and burrs after processing, the lower limit of Ka / Kb is 1.0.

  Next, the component composition constituting the soft magnetic steel sheet according to the present invention will be described. Hereinafter, all the units of chemical components are mass%.

[Component composition of soft magnetic steel sheet]
C: 0.001 to 0.02%
C should be reduced as much as possible because it dissolves in steel or forms carbides to deteriorate the magnetic properties. However, even if the C content is less than 0.001%, the effect of improving the magnetic properties is not achieved. Since it is small, the lower limit is made 0.001%. On the other hand, if the C content exceeds 0.02%, the magnetic properties deteriorate rapidly, so the upper limit is made 0.02%, preferably 0.015%, more preferably 0.01%.

Si: 0 to 0.05%
Si is used as a deoxidizer, but has the effect of reducing elongation, so the upper limit of Si content is 0.05%, preferably 0.04%, and more preferably 0.03%.

Mn: 0.05 to 0.5%
Since Mn has a deoxidizing action, in the present invention, in order to achieve both magnetic properties and press formability, instead of lowering the contents of C, S and Al as compared with conventional steel, Mn It plays a role as a deoxidizer, and exhibits its effect when the Mn content is 0.05% or more, preferably 0.1% or more, more preferably 0.15% or more. On the other hand, if Mn is contained excessively, elongation and magnetic properties are lowered, so the upper limit of the Mn content is 0.5%, preferably 0.4%, and more preferably 0.3%.

P: 0 to 0.02%
Since P decreases both elongation and magnetic properties, the upper limit of the P content is 0.02%, preferably 0.015%, and more preferably 0.01%.

S: 0 to 0.1%
When S is excessively contained, the elongation and magnetic properties are lowered. Therefore, the upper limit of the S content is set to 0.1%, and when high magnetic properties or elongation is required, preferably 0.06%, More preferably, it is 0.02%.
On the other hand, when S is contained in an appropriate amount, MnS is formed in steel together with Mn while sacrificing elongation and magnetic properties, and when stress is applied during punching, it becomes a stress concentration point. The machinability can be improved and the occurrence of burrs during punching can be suppressed. In order to obtain such an effect, the S content is 0.015% or more, preferably 0.04% or more.

Al: 0 to 0.01%
Since Al acts as a deoxidizing agent, it is an element effective for detoxifying by combining with O, which is harmful to magnetic properties, that is, oxygen. However, if Al is contained excessively, it combines with N to produce AlN, and the crystal grains are refined to reduce the elongation, or the magnetic grains remain fine even after magnetic annealing and the magnetic properties are deteriorated. The upper limit of the Al content is 0.01%, preferably 0.006%, and more preferably 0.005%.

Cr: 0 to 0.1%
Cr forms a precipitate such as sulfide in the steel, which causes deterioration of magnetic properties. Therefore, Cr should be reduced as much as possible, and the Cr content is 0.1% or less, preferably 0.07% or less, and more preferably. Is 0.05% or less.

N: 0 to 0.005%
When N dissolves in steel, the magnetic properties deteriorate, and even if some of them form AlN, the magnetic properties deteriorate due to the refinement of crystal grains, so the N content is 0.005% or less. , Preferably 0.004% or less, more preferably 0.003% or less.

  Furthermore, in the soft magnetic steel sheet of the present invention, in order to improve the machinability of the steel sheet, it is also preferable to control the ratio of Mn and S and the form of MnS as follows.

<Mn / S mass ratio: 3 to 20>
By combining Mn and S contained in the steel and finely dispersing as MnS precipitates, the machinability is improved and the generation of burrs during punching is suppressed. In order to obtain such an effect, it is necessary to ensure 3 or more in the mass ratio of Mn / S. A more preferable range of the Mn / S mass ratio is 5 or more, and the upper limit is 20.

MnS morphology <MnS precipitate average particle size: 0.05 to 4 μm>
In order to reduce the burr height at the time of punching, it is effective to disperse MnS. However, if it is too coarse, the magnetic properties are deteriorated, so the upper limit is set to 4 μm. On the other hand, if it is too fine, the burr height reduction effect will not be exhibited, so the lower limit is made 0.05 μm.
Here, the MnS grain size means an average value of the minor axis and the major axis of MnS observed in a cross section parallel to the rolling direction of the rolled sheet and perpendicular to the sheet surface.

<MnS precipitate having a particle size of 0.2 μm or more: 0.02 to 0.5 / μm ² >
The number density in the case of finely dispersing MnS precipitates is also important. If it is less than 0.02 / μm ² , there is no effect, and if it exceeds 0.5 / μm ² , cracking during molding becomes prominent. The number density is 0.02 to 0.5 / μm ² .

  In the soft magnetic steel sheet of the present invention, the components other than those described above are desirably Fe and inevitable impurities. However, as long as the effects of the present invention are not impaired, the inclusion of components other than those described above is not rejected.

<Thickness>
The thickness of the soft magnetic steel sheet of the present invention may be selected according to the shape and size of the parts to be applied. Among the electrical parts such as automobiles, trains, ships, etc. that are the subject of the present invention, the solenoid used in direct current When applied to cases and covers such as relays and relays, or iron cores, a magnetic circuit is formed. Therefore, when the plate thickness is reduced, the magnetic flux passing through the member is insufficient, and the component characteristics such as attractive force and responsiveness deteriorate. . Moreover, since the strength required for the components cannot be secured, the lower limit is set to 0.8 mm. Further, if it is too thick, it becomes impossible to meet the needs for downsizing of the component size, so the upper limit is set to 4 mm.
On the other hand, when applied to magnetic cores of electromagnetic parts such as motors and transformers used in alternating current, it is thin when considering reduction of eddy current loss and reduction of iron loss, which is the sum of eddy current loss and hysteresis loss. The upper limit is preferably about 1 mm. On the other hand, if the thickness is too thin, it becomes difficult to manufacture parts, so the lower limit in consideration of manufacturability is about 0.3 mm.

<Laminated steel sheet>
The soft magnetic steel sheet of the present invention can also be suitably used as a laminated steel sheet formed by stacking two or more sheets. In particular, when applied to electromagnetic parts used in alternating current, etc., by laminating multiple soft magnetic steel sheets with thin plate thickness, eddy current loss can be further reduced while securing the manufacturability and strength of the parts. This is a preferred embodiment. In order to further improve the magnetic properties of the laminated steel sheets and to ensure the insulation between the soft magnetic steel sheets, it is also preferable to provide an insulating coating between the soft magnetic steel sheets. As the insulating film, for example, an inorganic film such as a phosphoric acid-based chemical conversion film or a silicone resin film, a semi-organic film containing an inorganic compound and an organic resin, an organic film mainly containing a resin, and the like can be applied. It is not a thing. In addition, as for the plate | board thickness of a laminated steel plate, when applying to electromagnetic components, such as a motor and a transformer used by alternating current, it is preferable that an upper limit is about 1.0 mm and a minimum is about 0.3 mm like the above. Further, the two or more soft magnetic steel plates constituting the laminated steel plate are not necessarily limited to using the same plate thickness having the same composition and the same structure, but having different component compositions and structures. Those having different plate thicknesses may be used in appropriate combination.

  Next, a method for producing a soft magnetic steel sheet according to the present invention will be described. Although a manufacturing method in particular is not limited, For example, it can manufacture as follows.

[Preferred production method of soft magnetic steel sheet]
In order to produce the soft magnetic steel sheet as described above, first, a steel having the above component composition is melted and formed into a hot-rolled material by hot rolling after forming a slab by ingot forming or continuous casting. This process is called a hot rolling process. Although the temperature conditions at the time of hot rolling need not be particularly limited, for example, hot rolling may be performed at a rolling end temperature of 950 ° C. or lower.
Next, this hot-rolled material is cold-rolled at a reduction ratio R1: 30 to 70% to obtain a cold-rolled sheet. This process is called a rough cold rolling process. Then, this cold-rolled sheet is expressed by the formula 1: 270 ≦ [{100−R1 + 0.2 × (273 + T1)} ² + H1 × exp {−10 / (273 + T1)}] ^1/2 ≦ 340, where 750 ° C. ≦ T1 In order to satisfy ≦ 860 ° C., the soft annealing temperature is T1 ° C. and the soft annealing time is maintained for H 1 second to obtain a soft annealing plate. This process is called a soft annealing process. And it is also preferable to cold-roll this softening annealing board by rolling reduction R2: 0.1 to 3%. This process is called a finish cold rolling process. A soft magnetic steel sheet can be obtained through these steps.

<Rolling ratio R1: 30 to 70%>
The rolling reduction R1 in the rough cold rolling process is important for controlling the average crystal grain size in the subsequent softening annealing process. When the rolling reduction R1 is less than 30%, the crystal grains on the steel sheet are too large. On the other hand, when the rolling reduction R1 exceeds 70%, the crystal grains are too small, and the crystal grain size is controlled to a predetermined crystal grain size in combination with softening annealing conditions. It becomes difficult. For this reason, the lower limit of the rolling reduction R1 is 30%, more preferably 40%, and particularly preferably 50%. On the other hand, the upper limit of the rolling reduction R1 is 70%, more preferably 60%.

<Formula 1: 270 ≦ [{100−R1 + 0.2 × (273 + T1)} ² + H1 × exp {−10 / (273 + T1)}] ^1/2 ≦ 340 However, 750 ° C. ≦ T1 ≦ 860 ° C. is satisfied. , Soft annealing time T1 ° C., Soft annealing time H1 sec hold>
The average crystal grain size can be controlled to be more than 50 μm and 150 μm or less by combining the softening annealing conditions so as to satisfy the above formula 1 together with the adjustment of the rolling reduction R1 in the rough cold rolling step. If the value of the middle side of the above formula 1 is less than 270, the average crystal grain size becomes too small.
The above equation 1 is derived as follows. That is, there is a general theory that the recrystallization and grain growth behavior during annealing in the ferrite single phase temperature range is determined by the balance between the strain amount of cold rolling, the annealing temperature, and the annealing time. Therefore, the larger the amount of strain and the lower the annealing temperature, the smaller the recrystallized grain size. The r representing the crystal grain size by the subsequent grain growth by the radius is r ₀ representing the initial grain size by the radius, As a function of the annealing temperature T and the annealing time t, it was assumed that the relational expression r ² −r ₀ ² = k × t was established. Here, it is assumed that the rate constant k follows ア レ exp (−A / RT) which is an Arrhenius equation. The unit of T is K. For example, Nishizawa Yoji: “Grain growth in single-phase and dual-phase steels”, Iron and Steel (1984) No. 15, p. Detailed on 194-2020. In this general theory, the hypothesis that the effect of strain is smaller than usual for steel sheets of the component system of the present invention in which precipitates, which are a special grain growth inhibiting factor, are reduced as much as possible, is applied, and the rolling reduction rate in the rough cold rolling process is applied. Experiments were carried out with various combinations of R1 and soft annealing conditions T1 and H1, and the relationship between the press formability and the magnetic properties after the subsequent annealing was investigated and the above formula 1 was derived by regression analysis. .

<Rolling ratio R2: 0.1 to 3%>
It is also preferable to perform finish cold rolling at a rolling reduction R2 of 0.1 to 3% after softening annealing. By performing finish cold rolling, rough skin after bending and burr after punching can be prevented. In order to exert these effects, the rolling reduction R2 is set to 0.1% or more. However, when the rolling reduction R2 exceeds 3%, the amount of strain becomes excessive, and the magnetic characteristics are deteriorated.

  The soft magnetic steel sheet according to the present invention produced as described above exhibits good formability, and good magnetic properties are ensured in the formed member.

  As described above, sufficiently good magnetic properties are ensured for the formed member simply by press-forming the soft magnetic steel sheet according to the present invention. This process is called a press molding process.

  However, for cases where even higher magnetic properties are required for the molded member, or when extremely large plastic deformation is imparted to the molded member by molding, resulting in an increase in strain and deterioration of the magnetic properties. For example, magnetic annealing may be further added after molding. The recommended conditions for this magnetic annealing are a magnetic annealing temperature: 750 to 900 ° C. and a magnetic annealing time: 3600 s or more. This process is called a magnetic annealing process.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

[Example 1]
The steel materials having the components shown in Table 1 below were hot-rolled to obtain hot-rolled sheets having a predetermined thickness. After this hot-rolled sheet was pickled, it was processed in the order of rough cold rolling, soft annealing, and finish cold rolling under the conditions shown in Table 2 below to obtain a soft magnetic steel sheet having a final thickness of 1.0 mm. In Table 2, the value of the middle side of the formula 1 that defines the conditions for the magnetic annealing is also shown.

  In order to evaluate the formability of each soft magnetic steel sheet, it was processed into a JIS 13B test piece, a tensile test was performed, the elongation was measured, and this was used as an evaluation index for formability.

  In addition, in order to evaluate the rough surface after molding, as a bending test, the inner surface R was bent at 2 mm and the bending angle was 180 °, and the surface roughness of the outer R was measured with a cutoff of 0.8 μm and a measurement length of 5 mm. This was used as an evaluation index for rough skin.

  In addition, in order to evaluate the magnetic properties of the steel plate after forming and the magnetic properties after further magnetic annealing after forming, the soft magnetic steel plates are cut into 60 mm × 60 mm, and the steel plates remain as they are, and Each of the samples after magnetic annealing in hydrogen at 850 ° C. for 3 hours was evaluated for DC magnetic characteristics according to JIS C2556 using a single-plate measurement frame. The magnetic flux density and coercive force were measured with an applied magnetic field of 300 A / m.

  Further, the average crystal grain size and KAM value of the steel plate as well as the KAM value of the steel plate magnetically annealed at 850 ° C. for 3 hours were measured.

  The average crystal grain size of the steel plates was photographed by observing a microscope at the t / 4 position when the plate thickness was t after corroding the longitudinal section of each steel plate. And the particle size number was calculated | required with the comparison method with the standard figure of JISG0551, and it converted into the average crystal grain size.

  As for the KAM value of the steel plate as it is and after the magnetic annealing, each steel plate is mirror-polished, using a JEOL JSM-5410 as a scanning electron microscope, and at the t / 4 position when the plate thickness is t, Measure the electron backscatter diffraction image in the region of 500 μm × 500 μm at 1 step 0.2 μm, and use it as analysis software to obtain KAM values at each measurement point using OIM analysis 6 made by TSL, and arithmetically average them. KAM value.

  Table 3 below shows the measurement results. In the same table, the magnetic properties of the steel plates satisfying all the standards for the three items of coercive force of 100 A / m or less, magnetic flux density of 0.70 T or more at a magnetic field strength of 300 A / m 2, and elongation of 30% or more. As a soft magnetic steel sheet having excellent magnetic properties and formability, the overall judgment is indicated by A. In the table, Steel No. It was confirmed that 1-4, 9-12 and 16 satisfy all the criteria.

  Moreover, in the same table, out of the cases where the comprehensive judgment is A, those satisfying the criteria of Ra 2.5 μm or less after bending were regarded as soft magnetic steel plates having excellent skin roughness resistance, and the evaluation was indicated by AA. In the table, steel No. It confirmed that 1-4 and 9-12 showed the favorable rough skin resistance.

  Moreover, in the same table, among those of comprehensive judgment A, the magnetic properties of the steel plate after magnetic annealing satisfy both the coercive force of 37 A / m or less and the magnetic flux density of 1.25 T or more at a magnetic field strength of 300 A / m 2, The evaluation was indicated by AAA as a soft magnetic steel plate having superior magnetic properties. In the table, steel No. It was confirmed that 1-4, 9-12 and 16 showed good magnetic properties even after magnetic annealing.

  On the other hand, the steel No. using the steel type E. In No. 5, the C content was high beyond the upper limit, the crystal grain size as it was in the steel plate was small, and the magnetic properties did not meet the standards.

  Steel No. using steel type F In No. 6, the Al content was high beyond the upper limit, the crystal grain size as it was in the steel sheet was small, and the magnetic properties did not meet the standards.

  Steel No. using steel grade G In No. 7, the Mn content was high beyond the upper limit, and the magnetic properties did not meet the standards.

  Steel No. using steel type H In No. 8, the N content was high beyond the upper limit, the crystal grain size as it was in the steel plate was small, and the magnetic properties did not meet the standards.

  Steel No. No. 13, the rolling reduction R1 in the rough cold rolling is lower than the recommended range, and the value of the middle side of the formula 1 is larger than the recommended range. Sex did not meet the standards.

  Steel No. In No. 14, the rolling reduction R2 in the finish cold rolling was higher than the recommended range, and the ratio Ka / Kb value of the KAM value as it was in the steel sheet exceeded the upper limit, so the magnetic characteristics did not satisfy the standard.

  Steel No. No. 15, since the softening annealing temperature was lower than the recommended range, the crystal grain size as it was in the steel sheet was small, and the magnetic properties did not meet the standards.

  Steel No. No. 16 met the criteria for magnetic properties and elongation. On the other hand, since the finish rolling was not performed, the rough skin resistance as the steel plate did not satisfy the standard.

  In the table, steel No. It was confirmed that 1-4, 9-12 and 16 showed good magnetic properties even after magnetic annealing.

  Moreover, it was confirmed that the soft magnetic steel sheet according to the present invention can be obtained reliably by manufacturing under the recommended manufacturing conditions.

  Moreover, it was confirmed that a soft magnetic member having superior magnetic properties can be obtained reliably by further adding magnetic annealing under the recommended magnetic annealing conditions.

[Example 2]
The steel materials having the components shown in Table 4 below were hot-rolled to obtain hot-rolled sheets having a predetermined thickness. After this hot-rolled sheet was pickled, it was processed in the order of rough cold rolling, soft annealing, and finish cold rolling under the conditions shown in Table 5 below to obtain a soft magnetic steel sheet having a final thickness of 1.0 mm.

  In order to evaluate the formability of each soft magnetic steel sheet, it was processed into a JIS 13B test piece, a tensile test was performed, the elongation was measured, and this was used as an evaluation index for formability.

  Further, as an evaluation of punchability at the time of punching, punching was performed using a punch having a diameter of 10 mm and a die having a diameter of 10.20 mm and a clearance of 0.10 mm, and the maximum height of the burr generated around the hole was measured.

  Further, in order to evaluate the magnetic properties of the soft magnetic member after the magnetic annealing, each of the soft magnetic steel sheets is cut into 60 mm × 60 mm, and magnetic annealing is performed in hydrogen under conditions of T2: 850 ° C. × H2: 3 hours. After that, DC magnetic characteristics were evaluated according to JIS C2556 using a single plate measurement frame. The magnetic flux density and coercive force were measured with an applied magnetic field of 300 A / m.

  The average crystal grain size of the steel plates was photographed by observing a microscope at the t / 4 position when the plate thickness was t after corroding the longitudinal section of each steel plate. And the particle size number was calculated | required with the comparison method with the standard figure of JISG0551, and it converted into the average crystal grain size. On the other hand, with respect to the average crystal grain size of the steel plate after the magnetic annealing, in order to evaluate the average crystal grain size in the entire area of the soft magnetic steel plate, the depth of 200 μm from the outermost surface is obtained after the longitudinal section of each steel plate is subjected to nital corrosion. The surface portion of each and the positions of t / 4 and t / 2 when the plate thickness is t were observed with a microscope and photographed. And the particle size number was calculated | required by the comparison method with the standard figure of JISG0551, it converted into an average crystal grain size, and let the minimum value among three positions be the average crystal grain size of the steel plate after the said magnetic annealing.

  For the KAM value, each steel plate was mirror-polished, and JSM-5410 manufactured by JEOL was used as a scanning electron microscope. The electron backscatter diffraction image of the region was measured, and the KAM value at each measurement point was obtained using OIM analysis 6 manufactured by TSL as analysis software, and the KAM value was obtained by arithmetically averaging them.

  The particle size of the MnS precipitate was observed by SEM at a magnification of 1000 times in a cross section parallel to the rolling direction of the steel sheet and perpendicular to the plate surface, and the major and minor diameters of MnS were measured for 10 fields of view and their arithmetic average values were calculated. The particle size was defined. Further, the number density of MnS precipitates having a particle size of 0.2 μm or more was measured, and the number density was calculated.

  The measurement results are shown in Table 6 below. In the table, the magnetic characteristics satisfying all the criteria for the three items of the coercive force of 100 A / m or less, the magnetic flux density of 0.70 T or more and the elongation of 30% or more at a magnetic field strength of 300 A / m 2 As a soft magnetic steel sheet having excellent formability, the overall judgment is indicated by A. In the table, Steel No. 101-104, 110-113 and 117 were confirmed to meet all criteria.

  Moreover, in the same table, among the cases where the comprehensive judgment is A, the evaluation satisfying the burr height of 1 mm or less after the punching test is indicated as AA as a soft magnetic steel plate having excellent punchability. In the table, steel No. It was confirmed that 101 to 104 and 110 to 113 showed good pull-out properties.

  Also, in the table, among the cases where the overall judgment is A, the magnetic properties of the steel sheet after magnetic annealing satisfy both the coercive force of 37 A / m or less and the magnetic flux density of 1.25 T or more at a magnetic field strength of 300 A / m 2. As a soft magnetic steel plate that is more excellent in magnetic properties, its evaluation is indicated by AAA. In the table, steel No. It was confirmed that 101-104, 110-113, and 117 showed good magnetic properties even after magnetic annealing.

  On the other hand, steel No. using steel type AE. In No. 105, the C content was high beyond the upper limit, the crystal grain size as it was in the steel plate was small, and the magnetic properties did not meet the standards.

  Steel No. using steel grade AF No. 106 had a high Al content outside the upper limit, the crystal grain size as it was in the steel sheet was small, and the magnetic properties did not meet the standards.

Steel No. using steel grade AG In 107, the Mn content was higher than the upper limit and the Mn / S mass ratio was larger than the recommended range, so the average particle size of the MnS precipitate was small, and the elongation and magnetic properties did not meet the standards.

  Steel No. using steel type AH. In No. 108, the S content was higher than the upper limit and the Mn / S mass ratio was smaller than the recommended range, so the average particle size and number density of the MnS precipitates were both large, and the magnetic properties did not meet the standards.

  Steel No. using steel grade AI. No. 109 had a high N content exceeding the upper limit, and the magnetic characteristics did not satisfy the standard.

  Steel No. In No. 114, since the rolling reduction R1 in the rough cold rolling was lower than the recommended range, the crystal grain size as it was in the steel plate was large, and the magnetic properties, elongation, and punchability did not satisfy the standards.

  Steel No. In No. 115, since the rolling reduction R2 in the finish cold rolling was higher than the recommended range, and the ratio Ka / Kb value of the KAM value exceeded the upper limit, the magnetic characteristics did not satisfy the standard.

  Steel No. In 116, the softening annealing temperature was lower than the recommended range, so the crystal grain size of the steel sheet was small, and the magnetic properties did not satisfy the standard.

  Steel No. For 117, the magnetic properties and elongation met the criteria, but because the finish rolling was not performed, the punchability did not meet the criteria.

Claims (7)

Ingredient composition is mass%,
C: 0.001 to 0.02%,
Si: 0 to 0.05%,
Mn: 0.05 to 0.5%
P: 0 to 0.02%,
S: 0.015 to 0.10%,
Al: 0 to 0.010%,
Cr: 0 to 0.1%,
N: 0 to 0.005%
And the balance is a soft magnetic steel plate made of iron and inevitable impurities,
The average crystal grain size is more than 50 μm and not more than 150 μm,
Furthermore, the ratio Ka / Kb between the KAM value Ka of the soft magnetic steel sheet and the KAM value Kb after annealing the soft magnetic steel sheet at 850 ° C. for 3 hours is 1.0 to 1.5. Soft magnetic steel sheet.
Here, the “KAM value” means a “Kernel Average Mission value”.   The soft magnetic steel plate according to claim 1, wherein the plate thickness is 0.8 to 4.0 mm.   The soft magnetic steel plate according to claim 1, wherein the plate thickness is 0.3 to 1.0 mm. Furthermore, the mass ratio Mn / S between the content of Mn and the content of S is 3.0 to 20.0,
The average particle size of the MnS precipitate is 0.05-4 μm, and
The number density of MnS precipitates having a particle size of 0.2 μm or more is 0.02 to 0.5 / μm ² .
The soft magnetic steel sheet according to claim 1 , claim 2 or claim 3 . Laminated steel, characterized in that formed by laminating two or more sheets of soft magnetic steel sheet according to at least one of claims 1-4. A hot rolling step of hot rolling a steel material having the component composition according to claim 1 to obtain a hot rolled sheet;
A rough cold rolling process in which the hot-rolled sheet is cold-rolled at a reduction ratio R1: 30 to 70% to obtain a cold-rolled sheet;
A softening annealing step in which the cold-rolled sheet is held at a softening annealing temperature T1 ° C. and a softening annealing time H1 second so as to satisfy the following formula 1,
The method for producing a soft magnetic steel sheet according to any one of claims 1 to 4 , further comprising:
Formula 1: 270 ≦ [{100−R1 + 0.2 × (273 + T1)} ² + H1 × exp {−10 / (273 + T1)}] ^1/2 ≦ 340
However, it is 750 degreeC <= T1 <= 860 degreeC. Furthermore, a finish cold rolling step of cold rolling the softened annealed plate at a rolling reduction R2: 0.1 to 3%;
The manufacturing method of the soft-magnetic steel plate of Claim 6 provided with these.