JPH05171371A - Primary recrystallization annealed sheet for manufacturing high magnetic flux density grain-oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To stably manufacture a grain-oriented silicon steel sheet having extremely high magnetic flux density, at the time of manufacturing a grain-oriented silicon steel sheet, by regulating the product of the extreme density of the (110) plane and the (111) plane in the parallel face of the specified sheet thickness part into specified value. CONSTITUTION:A high Si steel slab is heated and is subjected to hot rolling, and after that, this hot rolled sheet is annealed in an N2 atmosphere, is cooled and is thereafter subjected to cold rolling into a thin steel sheet having a final sheet thickness, which is subjected to decarburization annealing serving also as primary recrystallization annealing in a hydrogen- nitrogen mixed gas. Successively, this steel sheet is coated with a separation agent for annealing, is subjected to secondary recrystallization annealing and purification annealing, is finally subjected to stress release annealing and is finished. At this time, by using a primary recrystallization annealed sheet in which the product P of the extreme density of the (110) plane and the extreme density of the (111) plane to the random azimuth in the parallel face of the sheet face at the 1/4 position of the sheet thickness after the primary recrystallization annealing is regulated so as to satisfy the inequality, the objective grain oriented silicon steel sheet having extremely high magnetic flux density can stably be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intermediate material for producing a grain-oriented electrical steel sheet mainly used as an iron core material of a power transformer.

[0002]

2. Description of the Related Art Many manufacturing methods have been disclosed so far for unidirectional electrical steel sheets, and the magnetic properties of products have been improved. However, the energy problem that gets worse year by year,
Reflecting environmental problems, the demand for improvement of magnetic properties of unidirectional electrical steel sheets, which is a main material of iron cores for power transformers, has been further strengthened.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a primary recrystallization annealed sheet as an intermediate material capable of stably producing a grain-oriented electrical steel sheet having a remarkably high magnetic flux density.

[0004]

Means for Solving the Problems In the grain-oriented electrical steel sheet, a so-called Goss-oriented texture is obtained by secondary recrystallization, in which the {110} plane is aligned with the rolling surface and the <001> axis is aligned with the rolling direction. It is manufactured by In this case, the texture of primary recrystallization and the inhibitor are important. That is, while the inhibitor suppresses the normal grain growth of the matrix, the Goss nuclei eclipse the matrix to cause abnormal grain growth, and a secondary recrystallization texture in the Goss orientation is obtained. As a result of intensive studies by the present inventor focusing on the texture of primary recrystallization and the inhibitor, as a result, dispersion of precipitates and a plate surface parallel plane at a position ¼ of the total plate thickness from the surface toward the central layer of the plate thickness Polar density of {110} plane and {1 for random orientation
A new finding that a unidirectional electrical steel sheet having a remarkably high magnetic flux density can be stably produced by using a primary recrystallization annealed sheet in which the product value of the pole density of the 11} plane is controlled so as to satisfy the following equation. And completed the present invention.

1.5 ≦ 50Z + P ≦ 2.5 Z ≧ 0.015 P ≧ 0.40 Z = (3/2) × (ρ / D) (μm ⁻¹ ) ρ; Volume fraction of precipitate D; Average particle size of precipitates (μm) P; Product of polar density of {110} plane and polar density of {111} plane Hereinafter, the background of the present invention will be described based on the results of Experiment 1.

(Experiment 1) C: 0.070% by weight,
Si: 3.00%, Mn: 0.080%, S: 0.00
02-0.0500%, acid-soluble Al: 0.0002-
A large number of 40 mm thick slabs containing various components of 0.0500%, N: 0.0002 to 0.0120% and the balance being Fe and unavoidable mixed elements were manufactured. Then 1
The slab is heated for 30 minutes soaking at various temperatures in the range of 100 to 1450 ° C, and the time from the heating of the slab to the start of hot rolling is set to 50 seconds. It was used as a hot rolled sheet. Then, in N ₂ atmosphere, 1150
1-300 ℃ after annealing at 120 ℃ for 120 seconds
The sample was cooled to room temperature at various average cooling rates of / sec. Then, it was cold-rolled to a plate thickness of 0.30 mm. In this case, the aging treatment was not performed during the cold rolling. Then H
_In the atmosphere of ₂ 75 vol%, N ₂ 25 vol%, and dew point of 65 ° C, primary recrystallization annealing that also serves as decarburization annealing at 850 ° C for 150 seconds of soaking is performed, an annealing separator is applied, and secondary recrystallization annealing is performed. I went. In the secondary recrystallization annealing, heating in an Ar atmosphere at a heating rate of 25 ° C./hour to 1200 ° C.
Purification annealing was performed at 1200 ° C. for 20 hours in _two atmospheres. Then, stress relief annealing was performed at 800 ° C. for 2 hours in a N ₂ atmosphere. Then, the magnetic flux density B ₈ was measured.

After the primary recrystallization annealing, the amount of MnS, the amount of AlN and the dispersed state of the precipitate were investigated. The amount of MnS was determined by dissolving the sample by the potentiostatic electrolysis method, filtering the residue, and adding the residue to HCl and HN.
It was dissolved in a mixed solution of O ₃ , filtered, and the Mn content of the filtrate was determined by the ICP method. The amount of AlN was determined by dissolving the sample in an iodine-methanol solution, filtering, dissolving the residue in a NaOH solution, filtering, and quantifying the Al content of the filtrate by the ICP method. For the precipitated dispersed phase, use Sel
active Potentiostatic Etch
ing by Electronic Disso
Electrolysis was carried out by the solution method (SPEED method), and the precipitate exposed on the electrolysis surface was peeled off by attaching an acetyl cellulose film, and an extraction replica was prepared and observed with a transmission electron microscope. The particle size of the precipitate was determined by observing a 6 μm × 8 μm portion of the replica with a transmission electron microscope at a magnification of 10,000 times, photographing 8 representative visual fields, and obtaining the image by an image analysis method. In this case, the particle size was calculated by regarding the particle image as a circle having the same area. In addition, the precipitate of each size,
It was assumed to be extracted from the thickness of the sample corresponding to ½ × particle diameter. The volume fraction of the precipitate was determined from the amount of MnS and the amount of AlN. In this case, the density of MnS and AlN, respectively 4.0 g / cm ³ and 3.3 g / cm ³ (Dictionary of Physics and Chemistry 4th ed. - see Iwanami Shoten) was calculated as. From the volume fraction (ρ) of the precipitate and the average particle diameter (D), Z value {(3/2)
× (ρ / D)} was calculated.

After the primary recrystallization annealing, the X-ray pole density of the {110} plane and the {111} plane with respect to the random orientation in the plane parallel to the plate at a position ¼ of the total plate thickness from the surface to the central layer of the plate thickness. The value (P value) of the product of the X-ray polar densities of the {} plane was measured. FIG. 1 shows the relationship between the Z value and P value and the magnetic flux density B ₈ .
That is, the horizontal axis is the Z value and the vertical axis is the P value. Symbols ◯, Δ, × and the like in the figure indicate the level of the magnetic flux density B ₈ . However, illustration is omitted for Z values exceeding 0.070 and P values exceeding 3.00. As is apparent from FIG. 1, a remarkably high magnetic flux density is obtained in the region surrounded by the straight line a, the straight line b, the straight line c, and the straight line d. Here, each straight line is Z value, P
The following relationships are shown for the values.

Straight line a: Z = 0.015 Straight line b: N = 0.40 Straight line c: 50Z + P = 1.5 Straight line d: 50Z + P = 2.5 That is, dispersion of precipitates and from the surface to the central layer of plate thickness The linear value was controlled so that the product of the polar density of the {110} plane and the polar density of the {111} plane with respect to the random orientation in the plane parallel to the plate at a position of 1/4 of the total plate thickness that satisfies the following equation It was found that a grain-oriented electrical steel sheet having a remarkably high magnetic flux density can be stably manufactured by using a recrystallization annealed sheet.

1.5 ≦ 50Z + P ≦ 2.5 Z ≧ 0.015 P ≧ 0.40 Z = (3/2) × (ρ / D) (μm ⁻¹ ) ρ; Volume fraction of precipitate D; Average particle size of precipitates (μm) P; C and M are controlled so as to satisfy the product formula of the polar density of {110} plane and the polar density of {111} plane.
n, S, acid-soluble Al, N, Sn, and other material components, slab heating conditions, hot rolling conditions, hot-rolled sheet annealing conditions (especially soaking temperature and cooling conditions), cold rolling conditions (especially rolling reduction and aging) Treatment conditions), primary recrystallization annealing conditions and the like can be mentioned. Moreover, you may perform a process of sulfur immersion, nitrogen immersion, etc. in an appropriate process.

The Z value is considered to be an index of the grain boundary migration inhibiting force of crystal grains due to fine precipitates. Pole density of {110} plane,
The pole densities of the {111} plane are Goss orientation and {11}, respectively.
1} <112> can be considered as an index of the amount of orientation.
The {111} <112> orientation is T with respect to the Goss orientation.
It is known to have a rotational relationship of about 35 ° around the D axis, close to the corresponding azimuth Σ9, and easily eroded by the Goss azimuth. The value of the product of the pole density of the {110} plane and the pole density of the {111} plane can be considered as an index of the encounter chance of Goss nuclei and oriented grains that are easily eaten by Goss nuclei.

[0012]

[Example] Except for the following, processing was performed under the same conditions as in Experiment 1. Ingredients of slab in wt%, S: 0.0270%,
Acid-soluble Al: 0.0290%, N: 0.0085%,
Sn: no addition (0.001% or less) and 0.25%, the slab heating temperature was 1400 ° C., the time until hot rolling start after slab heating was 3 seconds, 60 seconds and 150 seconds, and hot rolling Later plate thickness of 2.0mm, 3.0mm and 4.0m
m, the average cooling rate after hot-rolled sheet annealing was 30 ° C./sec, and there was no aging treatment and there was aging treatment during the cold rolling. The aging treatment condition in this case is 10 at the plate thickness of equal rolling reduction.
This was repeated once, and each was kept at 250 ° C. for 10 minutes. Table 1 shows the Z value, P value and magnetic flux density B ₈ after the primary recrystallization annealing. As is clear from Table 1, in the case of the present invention, a remarkably high magnetic flux density is obtained.

[0013]

[Table 1]

[0014]

EFFECTS OF THE INVENTION Dispersion of precipitates and polar density of {110} plane and {111} with respect to random orientation in parallel plane of plate surface at a position of ¼ of total plate thickness from surface to center layer of plate thickness
By using a primary recrystallization annealed sheet whose surface polar density product value is controlled so as to satisfy the following equation, it becomes possible to stably produce unidirectional electrical steel sheets with extremely high magnetic flux density. It was

1.5 ≦ 50Z + P ≦ 2.5 Z ≧ 0.015 P ≧ 0.40 Z = (3/2) × (ρ / D) (μm ⁻¹ ) ρ; Volume fraction of precipitate D; Average particle size of precipitates (μm) P; Product of polar density of {110} plane and polar density of {111} plane

[Brief description of drawings]

FIG. 1 shows a relationship between a magnetic flux density B ₈ and a P value, which is a product of a Z value showing a dispersion state of precipitates, a polar density of {110} plane and a polar density of {111} plane. That is, the horizontal axis is the Z value and the vertical axis is the P value. Symbols ◯, Δ, × and the like in the figure indicate the level of the magnetic flux density B ₈ .

Claims (1)

[Claims] 1. Dispersion of precipitates and polar density of {110} plane and {111} with respect to random orientation in parallel plane of plate surface at a position of ¼ of total plate thickness from the surface to the central layer of plate thickness.
A primary recrystallization annealed plate for producing a high magnetic flux density unidirectional electrical steel sheet in which the product value of the surface pole density is controlled to satisfy the following equation. 1.5 ≦ 50Z + P ≦ 2.5 Z ≧ 0.015 P ≧ 0.40 Z = (3/2) × (ρ / D) (μm ⁻¹ ) ρ; Volume fraction of precipitate D; Deposit Average particle size (μm) P; Product of polar density of {110} plane and polar density of {111} plane