JPS6365024A - Production of electrical steel sheet and single crystal manufacturing furnace to be used in said method - Google Patents

Abstract

PURPOSE:To improve the productivity of an electrical steel sheet having the ideal cubic texture by adjusting the angle between the growing end of a single crystal and the passage direction of a stock sheet at the time of connecting a seed crystal to one end of the stock sheet, passing the same into a furnace having a temp. gradient and growing the single crystal on the stock sheet. CONSTITUTION:The sheet 2 of the seed crystal consisting of the single crystal 3 having the crystal orientation which is going to be grown to the iron (alloy) stock sheet 1 is manufactured or connected at or to one end of the stock sheet 1. The stock sheet 1 is passed in the furnace having the temp. gradient from the side of the seed crystal 2 to grow the orientation of the seed crystal 2 and the single crystal to the stock sheet 1. The angle between the growing end 5 of the single crystal 3 and the passing direction of the stock sheet 1 is adjusted to 0 deg.<theta<90 deg. at this time and the stock sheet is passed in the furnace to manufacture the single crystal sheet or coarse crystal grain sheet having the crystal orientation within the specific orientation region. The sheet is then subjected to cold rolling in a specific direction then to recrystallization annealing, by which the electrical steel sheet of the cubic texture having the fine crystal grains is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing grain-oriented electrical steel sheets and a furnace for producing single crystals used in this method.

[Conventional technology]

Conventionally, the axis of easy magnetization <10 in two directions perpendicular to the inside of the plate surface.
A method for manufacturing a grain-oriented electrical steel sheet has been proposed with the aim of having 0>. However, it is difficult to industrially manufacture an electrical steel sheet with an ideal cubic orientation structure in which the orientation of each crystal of fine grains is aligned so that the axis of easy magnetization <100> lies in two directions perpendicular to the sheet plane. was extremely difficult.

In Japanese Patent Application No. 60-138039 filed by the same applicant, a single crystal plate or a coarse grain plate adjusted so that the +114] plane is within 15 degrees to the plate surface is We have proposed a method for manufacturing T4 magnetic steel sheets that is cold rolled in the direction of the steel sheet at a reduction rate of 40% or more and then annealed to obtain a primary recrystallized structure. According to this method, it is possible to produce a fine-grained electrical steel sheet with a highly integrated cubic orientation structure, and it is possible to produce electrical steel sheets with fine grains that have a highly integrated cubic orientation structure. A high saturation magnetic flux density, a low residual magnetic flux density, a low coercive force, a low hysteresis loss, and a low iron loss value, which could not be achieved with the i4 plate, can be obtained.

As in this Japanese Patent Application No. 138039/1983, in order to produce a single crystal plate or a coarse grain plate whose crystal orientation is within a specific orientation region, one of the conventionally known single crystal manufacturing methods is the strain annealing method. It is convenient. This strain annealing method is described, for example, in Tetsu to Hagane J 52 (1966), P, 187-203, after applying a slight processing to a blank plate to give it a strain, one end of the blank plate is A method of seeding a single crystal and growing the single crystal in the temperature gradient area by slowly passing the plate through a furnace with a temperature gradient from the seeding end.Adjusting the crystal orientation during zero seeding is a known method. Dun
This can be done by the n method.

[Problem that the invention seeks to solve]

When producing a single-crystal plate or a coarse-grain plate whose crystal orientation falls within a specific orientation region by strain annealing, the speed at which the plate passes through the furnace is related to the growth rate of the crystal; , there is a natural limit related to the rate of diffusion in the solid phase.

Therefore, when attempting to industrially produce a single crystal plate or a coarse grain plate having a desired crystal orientation, productivity becomes a problem.

The present invention was made for the purpose of improving the productivity of single crystal plates or coarse grain plates by strain annealing when producing electrical steel sheets.

[Means to solve problems]

The present invention involves fabricating or connecting a seed crystal whose crystal orientation is within a specific orientation region to one end of a raw plate of iron or iron alloy, and placing the raw plate 1ffi from the side of the seed crystal in a furnace with a temperature gradient. A single crystal having substantially the same crystal orientation as that of the seed crystal is grown in the base plate, thereby producing a single crystal plate or a coarse crystal grain plate whose crystal orientation is within a specific orientation region,
In the method of manufacturing an electrical steel sheet with a cubic orientation Mi weave having fine crystal grains by cold rolling this single crystal plate or coarse grain plate in a direction within a specific orientation region and recrystallizing the plate, the base plate is An electromagnetic device characterized in that, when passing the S crystal through a furnace having a temperature gradient, the angle θ between the growth end of the S crystal and the passing direction of the blank plate is adjusted to Qo<θ<90'. The present invention provides a method for manufacturing steel sheets.

As a single crystal plate or a coarse grain plate produced according to the present invention, the +1141 plane of the crystal is parallel to the plate surface or within at least 15°, and the <401> direction of the crystal is parallel to the longitudinal direction of the plate or at least within 15°. If this plate is cold rolled in the longitudinal direction and subjected to primary recrystallization annealing, an electrical steel plate with fine grains having an ideal cubic orientation structure can be obtained, as described in Japanese Patent Application No. 138039/1983. can be manufactured. Here, a single crystal plate is a plate consisting of one single crystal in the desired orientation.

A coarse-grain plate is a plate consisting of multiple large single crystals with a desired orientation.In the production of electrical steel sheets, the crystal orientation of the raw plate before cold-rolling and recrystallization annealing is usually called the initial orientation. In practicing the invention.

As mentioned above, especially +1141 <401
> is advantageous.

It is advantageous to fabricate a blank sheet with such an initial orientation into a strip shape that is longer in the longitudinal direction than in the width direction for subsequent cold-rolling and annealing treatment. An example of a recipe for single crystallization is shown in FIGS. 1 to 3.

Figure 1 shows a state in which a seed crystal plate 2 is connected to one end of the blank plate 1.The blank plate 1 and the seed crystal plate 2 are, for example, laser welded.The seed crystal plate 2 is grown on the blank plate 1. A single crystal with the crystal orientation of a single crystal.

Alternatively, use one made of polycrystals including single crystals with that orientation. In Figure 1, the seed crystal with this target orientation is indicated by 3. Next, as shown in Figure 2, leave the seed crystal 3 with the target orientation and cut out and remove the crystals in other orientations. .

A 0-seed crystal molding body that can thereby connect a seed crystal having a desired orientation to one end of the blank plate 1 can also be produced by the well-known Dunn method. The blank seeded by either method is passed through an annealing furnace with a temperature gradient from the seed crystal side to grow a single crystal in the same orientation as the seed crystal onto the blank l.

Figure 3 diagrammatically shows the growth process of the single crystal.
The single crystal in the growing process is indicated by 3, the original polycrystalline portion of the blank plate 1 is indicated by 4, and 5 is the growth end of the single crystal. By passing the plate at a predetermined speed in the direction of the arrow in the figure so that the growth end 5 of the single crystal always passes through the temperature gradient section of the annealing furnace, the growth end 5 continues to grow into the polycrystalline portion 4. . The principle of manufacturing a single crystal plate or a coarse grain plate having such a desired orientation is well known as the strain annealing method. However, even if it is possible to produce a single crystal plate or a coarse crystal grain plate with a desired orientation in a laboratory, the reality is that it is difficult to put this method to practical use industrially from the viewpoint of productivity.

The present invention is characterized in that, as shown in FIG. 4, the growth end 5 of the single crystal in the target orientation is inclined with respect to the direction in which the blank sheet passes. That is, in FIG. 3, the temperature gradient zone sandwiched between the low-temperature region and the high-temperature region in the furnace is provided so as to be perpendicular to the advancing direction of the blank sheet, and therefore the growth end 5 has an angle substantially perpendicular to the width direction of the sheet. (From a macroscopic perspective, the direction of crystal growth is the direction of the temperature gradient.) In contrast, in the present invention, the growth end 5 is inclined at an angle of θ within the plate plane with respect to the direction of movement of the blank plate. It is something that can be grown while doing so.

Now, let the threading speed of the blank plate be V (mIl/h), the temperature gradient at the crystal growth edge be ΔT (℃/c■), and the growth rate at which the single crystal grows stably be G wax (T). shall be.

When passing a sheet through a furnace with a temperature gradient, the temperature increase rate at one point where the material is made is temperature gradient ΔT6 sheet passing rate ■.

Under this, ΔT I' V + per unit time.

In order for the growth edge of the crystal to grow stably, ■.

is less than Gmax(T), so the maximum speed of ■ cannot exceed Gmax(T) at that temperature.

Since G wax (T) is generally difficult to obtain, the maximum value of the stable growth rate at ΔTI, V wax, is determined.

This is taken as the maximum threading speed at ΔT1. Considering a temperature gradient ΔT2 smaller than ΔT1, the growth rate v2 at ΔT,
Against.

Because ΔTz Vz = ΔT1vIIlax.

V Z = (ΔTl/ΔTz) ・Vmax. Therefore, by making the temperature gradient gentler, the apparent growth rate can be increased.

However, with this method, the maximum growth rate at ΔTi cannot theoretically be made higher than Gmax (T), so it cannot necessarily be said to be an effective method. Growth of unnecessary grains becomes more likely to occur, leading to other problems.

The present invention is characterized in that the sheet passing speed is improved not by changing the temperature gradient (but by changing the direction of the temperature gradient. In other words, in Fig. 4, the temperature gradient area of the furnace is For example, the growth end 5 is inclined from the direction of movement of the blank by an angle of θ, for example, but the growth direction Y of the single crystal is in the temperature gradient region. is the direction of the temperature gradient at .

Now, once the temperature gradient ΔT is determined, the maximum growth rate of the crystal growth edge is determined, and this is set as V ssx.

The angle between the longitudinal direction (threading direction) of the blank sheet and the temperature gradient area is θ.
Then, the threading speed V(θ) in the longitudinal direction is.

V(θ) ” V saw/Cos θ≧V wax. That is, by tilting the temperature gradient region with respect to the longitudinal direction of the blank sheet, the larger θ is, the greater the sheet passing speed can be increased. Table 1 shows the increase ratio V(θ)/V l1ax when the angle of θ is changed. In order to fully obtain the effects of the present invention, it is preferable that θ is 30° or more.

The reason for this is that when θ is small, crystals with orientations other than the intended one tend to grow. on the other hand.

If θ exceeds 80°, the furnace structure becomes complicated (for example, the cooling sleeve described below becomes long), making it impractical. Therefore, it is recommended that θ be in the range of 30° <θ<80°. desirable.

Table 1 FIG. 5 shows an example of a temperature gradient furnace suitable for carrying out the method of the present invention. Reference numeral 10 denotes a cylindrical furnace wall made of refractory bricks, and a furnace tube 11 is installed inside this cylindrical furnace wall 10, which has a 5-vertical shape.
installed coaxially and vertically. A water-cooled sleeve 12 is passed partway through the furnace core tube 11, and an inner end 13 of the water-cooled sleeve 12 is inclined at an angle of θ with respect to the longitudinal direction of the furnace. A plurality of heating elements 14 are attached so as to surround the outside of the furnace core tube 11. Each heating element 14 is designed so that its heating temperature can be adjusted independently.

FIG. 6 shows a cross section taken along the line Vl--Vl in FIG. 5. As seen in this figure, a water-cooled sleeve 12 is also installed coaxially within the reactor core tube 11, and this water-cooled sleeve 12
A cooling water passage 15 is provided inside. 7 to 9 show the shape of this water-cooled sleeve 12 in more detail. In this example, a slit-shaped blank passageway 16 for passing the blank plate through a copper cylinder is created in the axial direction. Cooling water passages 15 are provided on both sides of the blank passage 16. Each cooling water passage 15
A pipe 17 is inserted into the pipe 17, and cooling water is discharged from the lower end of the pipe 17 to the distal end side of the passage 15 (the inner end side of the water cooling sleeve 12).

The return water is discharged out of the system from a drainage channel 18 provided above the cooling water passage 15.

When the furnace core tube 11 is heated by each heating element 14 and cooling water is passed through the water-cooled sleeve 12 using the furnace configured as described above, the passing direction is different from θ at the inner end 13 of the water-cooled sleeve 12. A temperature gradient area is formed that is inclined by an angle. Therefore, when the raw plate l is passed through the raw plate passage 16 of the water-cooled sleeve 12 from the outer end (upper end) downward in the direction of the arrow, the growth end of the single crystal is formed at the inclined furnace end 13 of the water-cooled sleeve 12. The edge will have an inclination substantially equal to this inclination, and the method of the invention described above can be carried out suitably.

It is preferable that each heating element 14 be installed so as to surround the furnace core tube 12 so as to have an inclination equal to the furnace inner end 13 of the water-cooled sleeve 12 as shown in the drawing.

Depending on the case, it may be installed in a direction perpendicular to the axis of the furnace core tube 12. Although not shown in FIG. 2, it is preferable that the furnace atmosphere inside the furnace core tube 11 be an inert gas atmosphere such as argon gas. . And in some cases, water cooling sleeve 1
It is also possible to process a plurality of blank plates at the same time by providing a plurality of blank passages in parallel in the furnace tube 2 or by installing a plurality of water cooling sleeves 12 in the furnace core tube 11.

The present invention is suitably applied to the production of electrical steel sheets made of iron or iron alloys with a body-centered cubic structure, and in the case of iron alloys, the alloy components include 8% or less Si, 20% or less Any of A1.5% or less Mo, 25% or less Cr, 6% or less W, 3% or less Ti, 3% or less Nb, or 5% or less ■ can be used alone or in combination. can. The effects of these alloy components on the material quality are summarized as follows. Addition of Si is effective in improving the magnetic properties and in improving the iron loss value by increasing the electrical resistance. Furthermore, when the St becomes high, the wear resistance is also improved. Addition of 5% or more of Si leads to poor processability.

It is possible to manufacture up to 8% by warm processing, and the content up to 8% is acceptable. Like Si, Al is effective in improving magnetic permeability, increasing electrical resistance, and improving wear resistance.
Furthermore, the wear resistance is significantly improved by adding Si in combination. However, if it exceeds 20%, it becomes brittle and difficult to manufacture, so it is better to keep it below 20%.For Mo, the i3 if ratio can be improved up to 5%, but 5%
ACR is effective in improving corrosion resistance and is allowed up to 25%. Others, 6%
The physical properties of the steel sheet can be improved by adding the following W, 3% or less V, 3% or less Nb, 5% or less V, etc.

Further, they can be added singly or in combination within the range of sb≦2%, As52%, and Be52%.

1. In the present invention, as a single crystal to be grown, the +114) plane of the crystal is parallel to the plate surface, and the <401> direction of the crystal is the longitudinal direction of the plate. This single crystal plate or coarse grain plate can be
By rolling the steel sheet in the 401> direction at a reduction rate of 40% or more and performing primary recrystallization, it is possible to produce an electrical steel sheet having an ideal cubic orientation structure.

[Brief explanation of drawings]

Figures 1 to 3 are plan views illustrating the process of manufacturing single crystal plates or coarse grain plates by strain annealing;
The figure is a plan view illustrating the single crystal growth method according to the present invention.
FIG. 5 is a schematic cross-sectional plan view showing the main parts of a temperature gradient furnace suitable for carrying out the method of the present invention. 6 is a sectional view taken along the line Vl-Vl in FIG. 5, FIG. 7 is a front view of the water cooling sleeve, FIG. 8 is a right side view of FIG. 7, and FIG.
The figure is a sectional view taken along the line IX-IX in FIGS. 7 and 8. 1. Base plate, 2. Seed crystal plate, 3. Single crystal with target orientation, 4. Polycrystalline part of base plate. 5. Growth end, 10. Furnace wall refractories, 11.. Furnace core tube, 12.. Water cooling sleeve, 13.. Furnace inner end with slope of water cooling sleeve, 14.. Heating element. 15... Cooling water passage, 16... Raw plate passage.

Claims (4)

[Claims] (1) Fabricate or connect a seed crystal whose crystal orientation is within a specific orientation region to one end of an iron or iron alloy blank, and pass this blank into a furnace with a temperature gradient from the side of the seed crystal. A single crystal with substantially the same crystal orientation as that of the seed crystal is grown in a base plate, thereby producing a single crystal plate or a coarse grain plate with crystal orientation within a specific orientation region, and this single crystal plate Alternatively, in a method of manufacturing an electrical steel sheet with a cubic orientation structure having fine grains by cold rolling a coarse grained sheet in a direction within a specific orientation region and recrystallizing it, the raw sheet has a temperature gradient. When passing the sheet through the furnace, the angle θ that the growth end of the single crystal makes with the direction of passing the blank is set to 0°<θ<
A method for producing electrical steel sheets characterized by threading the sheets by adjusting the angle to 90°. (2) The manufacturing method according to claim 1, wherein θ is 30°<θ<80°. (3) A single crystal plate or a coarse grain plate is
14} plane has an orientation within 15° with respect to the plate surface, and the direction of cold rolling of this single crystal plate or coarse grain plate is within 15° around the <401> direction. The manufacturing method according to claim 1 or 2. (4) A single-crystal manufacturing furnace in which a raw plate is passed longitudinally through a temperature gradient section in the furnace at a predetermined speed, and a water-cooled sleeve with an inclined inner end of the furnace is inserted into the furnace, and the sleeve is tilted. A single crystal manufacturing furnace used in the method according to claim 1, wherein the blank plate is passed into the furnace from the inner end of the furnace.