JPS6256204B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a high-silicon ribbon with excellent magnetic properties, and in particular, the present invention relates to a method for producing a high-silicon ribbon with excellent magnetic properties, and in particular, the present invention relates to a method for manufacturing a high-silicon steel ribbon with excellent magnetic properties. The present invention relates to a method for producing an excellent high-silicon ribbon. A unidirectional silicon steel strip is characterized in that the <001> direction, which is the axis of easy magnetization, is aligned in the longitudinal direction of the steel strip with {110} planes being parallel surfaces of the steel strip. Because of its excellent soft magnetic properties and low core loss, it is used in large quantities as a material for power transformers, small transformers, wound iron cores, etc. Therefore, when actually used in transformers and the like, energy loss is small, and from the viewpoint of users of transformers and the like, this is extremely desirable in conjunction with recent energy saving considerations. However, for manufacturers, the manufacturing method is complex even with modern, more advanced industrial processes, and costs are bound to rise, and it is difficult to realize energy savings in this regard. This is an important issue from a national perspective as well. On the other hand, instead of the energy-consuming manufacturing method described above, a technology has recently begun to be developed for manufacturing silicon steel ribbon by a direct sheet manufacturing method from molten steel.
In this method, molten steel having a specific composition is injected from a nozzle with a predetermined spout onto the cooling surface of a cooling body moving at high speed, and is rapidly cooled. can be manufactured. According to this method, a finished product or a semi-finished product can be obtained from molten steel through one process. This is an extremely simple process compared to the previously mentioned unidirectional silicon steel strip, which is manufactured using a complicated process, so it also reduces costs.
It can be said that this method is excellent and effective from the viewpoint of energy saving. However, when the ribbon produced by the above method is used as it is, it is sufficient for some uses, but when used as an iron core material that requires low core loss, its characteristics are insufficient. be. Conventionally, when molten steel is rapidly cooled to directly produce a ribbon, the {100} plane is parallel to the ribbon surface, and the <001> direction is parallel to the normal direction of the ribbon, that is, parallel to the ribbon thickness direction. It is known that Of course, due to differences in the conditions during rapid cooling of molten steel, that is, the flow rate and velocity of the injected molten steel mentioned above, the moving speed of the moving cooling surface of the cooling body, etc.,
It is possible that the {110} plane <001> direction has an angular dispersion of about 20°. However, although such a silicon steel ribbon may be used as it is as a material with in-plane 100, there is a disadvantage that the magnetic properties of this material are only comparable to those of a low-grade non-oriented silicon steel strip. The applicant of the present invention disclosed in Japanese Unexamined Patent Application Publication No. 56-87627 that a thin ribbon obtained from molten steel by a direct sheet manufacturing method was heated to 1050 to 1300℃.
It has been disclosed that the magnetic properties can be improved by annealing within the temperature range of 200 to 3000, and that it can be used as a material for power transformers and the like. However, in order to further reduce energy loss in power transformers, etc., it is necessary to make the texture after annealing accumulate in the {110} <001> direction, as in the current unidirectional silicon steel sheet. There was no known means of accumulating it. The present invention utilizes {110}<
The object of the present invention is to provide a method for manufacturing a thin ribbon having excellent magnetic properties and having a texture of be able to. Next, the present invention will be explained in detail. The present inventors have newly discovered that magnetic properties can be improved by combining pretreatment such as pickling and rolling with annealing as necessary without complicating the manufacturing process. In other words, it has been found that excellent magnetic properties can be achieved by applying a novel means that can align the {110}<001> orientation in the longitudinal direction of the ribbon. According to the present invention, the silicon steel quenched ribbon produced by the method described above is rolled at a reduction rate of 40 to 80% to form a rolling texture in the longitudinal direction of the ribbon. It can be made possible.
In this case, if normal cold rolling is performed, {100}<110> will be formed in the longitudinal direction of the ribbon at a relatively low rolling reduction, and in further rolling, the above {100}<110> will be formed. The orientation becomes the same as rolling, and the final texture remains {100} <110>, and even if it is continued annealed, the magnetic properties will not improve significantly with the same orientation. . However, when hot-to-warm rolling is applied to a material with the above initial orientation, crystal slippage occurs in combination with recrystallization and recovery, which is different from cold rolling and changes the final rolling orientation to 40.
In the rolling reduction range of ~95%, a texture with {112}<111> as the main orientation and a slight {110}<001> as the minor orientation is formed. In this manner, by applying rolling at a high temperature, a texture can be generated in the longitudinal direction of the silicon steel quenched ribbon. However, it is not possible to sufficiently improve the magnetic properties by this rolling alone. In order to achieve the above improvement, it is necessary to perform secondary recrystallization in the {110}<001> orientation. For this purpose, it is necessary to perform final annealing at a temperature range of 1000 to 1300°C. However, in this annealing, it is important to make the annealing atmosphere appropriate. That is, the secondary recrystallization can be efficiently performed by setting the atmosphere to a reduced pressure to vacuum. It is also important to suppress primary recrystallization grain growth in the stage before secondary recrystallization, which was performed in the production of conventional unidirectional silicon steel sheets, and for this purpose, box annealing is In this case, a release agent is applied to the silicon steel ribbon before final annealing, and an element that tends to segregate at grain boundaries, such as sulfur, is added to this release agent and then applied.
Finish annealing at 1000-1300℃ is also possible {110}<001
＞Very effective for developing orientation. In addition, in the case of continuous annealing, unlike the above-mentioned annealing method in which the coils are annealed, so-called sticking of the plates to each other does not occur, so there is no need to apply a release agent. Therefore, in the case of continuous annealing methods, such known treatments are usually not carried out. Next, the present invention will be explained in order of manufacturing steps. Silicon steel with Si2 to 8% is made into a molten steel state,
Injected through a circular hole or rectangular slit nozzle and rapidly cooled at a rate of 10 ³ °C/sec or more on rotating twin rolls or a single roll surface or a moving belt to produce a silicon steel strip with a thickness of 20 to 500 μm. do. At this time, the width of the ribbon can be adjusted to any desired width depending on the shape of the nozzle described above. Although it can be used as an electromagnetic steel strip as it is, its uses are extremely limited. Therefore, by annealing the quenched ribbon produced by the above method within a temperature range of 1000 to 1300°C, the magnetic properties can be improved by coarsening the crystal grain size of the ribbon. Conventionally, it has been known that this treatment exhibits excellent magnetic properties, but the present inventors came up with a method for producing high-grade silicon steel ribbon with even lower core loss, and completed the present invention. It is. 1000~ for the ribbon produced by the above method
Rolling is performed at a reduction rate in the range of 40 to 95% while heating to a temperature of 1300°C. The present invention is characterized in that the rolling texture is sharpened in the rolling direction by this rolling, and even a silicon steel strip with a high Si content of 4% or more can be processed easily. In addition, the rolling reduction rate varies depending on the misalignment of the dendrite orientation when the molten steel is rapidly cooled, but if the plane of the ribbon is approximately 100 planes, the misalignment between the normal direction of the plate surface and the <101> axis is approximately When the temperature is 0 degrees, the reduction rate is approximately 60 to 95%, depending on the temperature during rolling, and if the deviation of the 100 axis in the surface normal direction is close to 45 degrees, the reduction is approximately 40 to 85%. It is possible to generate a rolling texture with {112}<111> as the main orientation and {110}<001> as the minor orientation. A silicon steel ribbon having the necessary conditions for secondary recrystallization as described above is wound into a coil and subjected to final annealing. When coiled, alumina or MgO can be applied as a release agent between the coil layers. When aligning the 110 planes on the ribbon surface, it is effective to perform the annealing in a reduced pressure atmosphere. That is, FIG. 1 shows the relationship between the annealing temperature and atmospheric pressure that strengthens the {110} plane accumulation of the recrystallized texture after the final annealing. It can be seen that as the degree of vacuum in the annealing atmosphere increases, the proportion of {110} planes occupying the ribbon surface increases. Also,
It can be seen that the annealing temperature, where {110} accounts for 50% or more, also decreases as the degree of vacuum increases. That is, in order to improve the degree of integration of {110} planes, which is the gist of the present invention, it is necessary to set the annealing temperature higher than the straight line in FIG. The straight line in Figure 1 is approximated by T=alogV+b (where T
is the annealing temperature (°C), V is the degree of vacuum (Torr), and a and b are constants), but the first
From the figure, in the preferred range of V (10 ^-4 ≦V≦1),
Since T=50logV+1300 (℃), the suitable annealing temperature T _A in the present invention is T _A ≧50logV+1300
It is indicated by. It can be seen that the magnetic properties at this time become better as the coercive force decreases as the degree of vacuum in the annealing atmosphere increases, as shown in FIG. Even if the degree of vacuum is lower than 1 × 10 ^-4 , the magnetic properties will not be much advantageous.
In fact, it is only disadvantageous in terms of reducing manufacturing costs. In Figure 2, the reason why the coercive force Hc is improved when the annealing temperature is 1200°C than 1100°C is because the coarsening of crystal grains has progressed more at 1200°C, and also because the annealing atmosphere When (Torr) decreases
As shown in Figure 3, Hc is improved by {110}
This is because the surface area increases. Further, in order to align the {110} planes on the ribbon surface, it is also possible to perform annealing by controlling the oxygen potential during the final annealing. Oxygen volume fraction in the atmosphere and X of the ribbon surface when annealing is performed at 1200℃ with the dew point of the final annealing atmosphere changed from room temperature to a lower one.
The relationship with line strength is shown in Figure 3. In body-centered cubic metals, depending on the arrangement of atoms, there are {110} and {100} planes.
Since the dense density of atoms is different from the surface, for example,
In Trans.Metall.Soc.AIME218 (1960) 914
As shown by Walter and Dunn, the {110} and {100} planes have different surface energies. On the other hand,
A trace amount of oxygen in the annealing atmosphere acts to reduce the surface energy of the crystal planes by adsorbing them to the crystal planes. Figure 3 shows this phenomenon. When the oxygen volume fraction is small, a large amount of oxygen molecules {100}
The number of crystal grains on the {100} plane increases due to adsorption to the plane, but
When there are many oxygen molecules, the number of {110} plane crystal grains increases. The X-ray intensity varies depending on the number of crystal grains.
From the same figure, when the oxygen volume fraction is less than 1.6×10 ^-3 %, the {110} surface strength becomes stronger than the {100} surface strength, and when the oxygen content is higher than this oxygen volume fraction, the {110} surface strength becomes {100} surface strength. It can be seen that it becomes weaker than the strength. Therefore, the annealing atmosphere for manufacturing ribbon containing many {110} planes is
It is necessary to do this at 1.6×10 ^-3 % or less. In this way, by heating and rolling a silicon steel ribbon at a high temperature, the texture is sharpened in the rolling direction, and by annealing in a selected atmosphere, the texture becomes {110}<001> in the rolling direction. By accumulating oriented secondary recrystallized grains, it is possible to produce a ribbon for electrical steel sheets having excellent magnetic properties. Next, the present invention will be explained with reference to examples. Example A 300 μm thick ribbon was made by directly quenching molten steel containing 6.5% Si, 0.1% Mn, 0.05% P, and 0.001% C, with the balance being Fe. 980
It was immediately rolled while heating to ℃. During rolling,
When the temperature fell below 800°C, it was reheated to 980°C for about 1 minute and rolled to a thickness of 100 μm. After that, degreasing is performed, and the alumina is made into a slurry and applied to the steel plate, and dried at approximately 200 degrees Celsius to evaporate the moisture. Thereafter, it was immediately rolled into a coil, placed in a Box furnace, and vacuum annealed at 1100°C and 1200°C for 5 hours. Coercive force when annealing with different degrees of vacuum (when Bm measurement magnetic flux density is 1.0T)
The results are shown in the table below.

[Table] According to the present invention, a high-silicon ribbon with excellent magnetic properties can be produced.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the tendency of 110 plane formation when annealing temperature and annealing atmosphere are changed, and Figure 2 is a diagram showing the tendency of 110 plane formation when annealing temperature and annealing atmosphere are changed.
Figure 3 shows the relationship between the annealing atmosphere and coercive force when annealing is performed at 1200°C and 5 hours. Figure 3 is a diagram showing the relationship between oxygen volume % and X-ray intensity of the 110,100 plane .

Claims (1)

[Claims] 1 Molten steel containing 2 to 8% Si and the remainder substantially Fe is injected from a nozzle onto the moving cooling surface of a cooling body, rapidly cooled and solidified to create a steel ribbon, and then annealed. In the method for producing a high silicon steel ribbon, the rapidly cooled and solidified steel ribbon is rolled at a constant circumferential speed or at different circumferential speeds within a temperature range of 800 to 1300°C and a reduction rate of 40 to 95%. After applying, within the temperature range of 1000 to 1300℃ and under the degree of vacuum shown by the following formula (1),
The final annealing is performed at the temperature shown by the following equation (2), which is calculated from the degree of vacuum shown by equation (1). A method for manufacturing high-silicon steel ribbon with excellent magnetic properties that is integrated in the direction. 10 ^-4 ≦V≦1 (Torr) ... (1) T _A ≧50logV + 1300 (℃) ... (2) However, V represents the degree of vacuum (Torr). 2 High-silicon steel thin steel containing 2 to 8% Si and the remainder substantially Fe is injected from a nozzle onto the moving cooling surface of a cooling body, rapidly cooled and solidified to create a steel thin strip, and then annealed. In the method for manufacturing a strip, the rapidly cooled and solidified steel ribbon is rolled at a constant circumferential speed or at different circumferential speeds within a temperature range of 800 to 1300°C and a rolling reduction range of 40 to 95%, and then rolled at 1.6 ×10 ^-3 (vol
%) under oxygen partial pressure atmosphere below 1000~1300℃
A method for producing a high-silicon steel ribbon with excellent magnetic properties in which the {100}<001> orientation is concentrated in the longitudinal direction of the steel ribbon as the final orientation of crystal grains, the method comprising performing final annealing within a temperature range of .