JPH02133524A - Production of thin-gaged grain oriented electrical steel sheet having excellent magnetic characteristics - Google Patents

Abstract

PURPOSE:To produce the thin-gaged grain oriented electrical steel sheet of a low iron loss and high magnetic flux density by subjecting the electrical steel sheet successively to coiling, water cooling, preliminary cold rolling, and inhibitor precipitation annealing at specific temps. after hot rolling in the process for producing the grain oriented electrical steel sheet consisting of a specific compsn. CONSTITUTION:The electrical steel slab consisting, by weight %, 0.02 to 0.10% C, 2.0 to 4.0% Si, 0.02 to 0.10% Mn, 0.01 to 0.04% S, 0.010 to 0.065% sol Al, 0.0030 to 0.0100% N, and the balance iron and unavoidable impurities is subjected to the hot rolling and the inhibitor precipitation annealing. The steel sheet is then made into 0.15 to 0.23mm final sheet thickness by >=1 passes of the cold rolling including the high-draft final rolling of 80% over to 95% draft and is subjected to decarburization annealing. An annealing and separating agent is applied thereon and the sheet is subjected to the finish annealing. The steel sheet is coiled at 200 to 400 deg.C after the hot rolling and the coil is cooled with water within about 15 minutes and is subjected to the preliminary cold rolling to about 20 to 50% then to the inhibitor precipitation annealing in this production process. The thin-gaged grain oriented electrical steel sheet of the low iron loss and the high magnetic flux density is obtd. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a thin oriented electromagnetic plate with improved magnetic properties.

(Prior Art) Grain-oriented electrical steel sheets are used as core materials for electrical equipment such as transformers, and must have good magnetic excitation properties and iron loss properties.

This steel plate contains inhibitors, such as IVN, MnS
.

Utilizing MnSe, CuS, BN, etc., secondary recrystallization is caused by final annealing to develop crystal grains called a Goss structure with (110) planes on the rolled surface and <001> axis in the rolling direction. It is obtained by letting In order to obtain good magnetic properties, it is important to align the <001> axis of easy magnetization to a high degree in the rolling direction.

In addition, the plate thickness, grain size, resistivity, surface coating, purity of the steel plate, etc. have a large effect on the magnetic properties, especially the iron loss properties.

The directionality has been significantly improved by a method characterized by using /VN and MnS as inhibitors and subjecting the final cold rolling to a high reduction, and the iron loss properties have also been improved accordingly.

By the way, in order to meet the recent demands for energy conservation,
Studies are being conducted to further reduce iron loss in grain-oriented electrical steel sheets. As is well known, iron loss is the sum of eddy current loss and hysteresis loss, but in order to reduce eddy current loss, which accounts for the majority of iron loss,
Development studies have been conducted on thin grain-oriented electrical steel sheets, and some of them have been put into practical use.

The production of grain-oriented electrical steel sheets using the above-mentioned AIN and MnS as inhibitors is extremely effective in increasing the magnetic flux density, but as the sheet thickness becomes thinner, there is a problem that secondary recrystallization becomes unstable.

As a countermeasure against this, hot-rolled sheet annealing is heated at two heating temperatures and then rapidly cooled to more finely disperse and precipitate the inhibitor.
A method has been proposed in which rolling is performed by heating at 00°C for 30 seconds to transform the Goss structure into a loose cold-rolled structure (Japanese Patent Laid-Open No. 6
0-59044).

In addition, before the inhibitor precipitation annealing, the hot rolled sheet was
It is disclosed in Japanese Patent Application Laid-Open No. 59-12672 that preliminary cold rolling is performed at a rolling reduction of 1.5% to prevent the generation of linear fine grains and improve iron loss characteristics.
This is proposed in Publication No. 2.

In addition, the cooling rate of inhibitor precipitation annealing was specified, and 2
By cold rolling more than once and aging between passes, solid solution C,
N or fine carbides and nitrides affect the cold rolling bed structure and change the recrystallization behavior in the subsequent intermediate annealing (1
10) Perform grain size adjustment to increase oriented grains and decrease (100) oriented grains. It has been proposed in JP-A-62-202024 that this stabilizes secondary recrystallization.

As a result, the occurrence of secondary recrystallization is improved, and a thin grain-oriented electrical steel sheet with high magnetic flux density and low iron loss can be obtained.

(Problems to be Solved by the Invention) However, the improvement in the magnetic properties of the directional type +ntHJ board is not sufficient, and further improvements are required.

The grain-oriented electrical steel sheet is heated to -a at a high temperature exceeding 1280°C in order to completely dissolve the inhibitor-forming component in the steel during slab heating. Due to the coarsening of the slab crystal grains at this time, the hot-rolled plate of the slab has (100) <Of 1>
Oriented distracted grains may be present. In such a case,
It has a negative effect on secondary recrystallization, for example, the final plate thickness is 0.1
When the thickness is less than 8 mm, it becomes a cause of generation of linear fine grains.

The present invention aims to solve such problems without increasing the manufacturing cost. When manufacturing a thin grain-oriented electrical steel sheet using /IN as the main inhibitor, the sheet thickness is, for example, 0.18 mm as described above. The purpose is to sufficiently exhibit secondary recrystallization even if the thickness is less than mm, and to obtain a material with extremely low iron loss and high magnetic flux density.

(Means for Solving the Problems) In order to achieve the above object, the present inventors used AZN as the main inhibitor, performed inhibitor precipitation annealing after hot rolling,
Experiments and studies were carried out on the production of thin grain-oriented electrical steel sheets in which the final cold rolling is carried out under pressure with a rolling reduction of more than 80% to 95%. As a result, when a silicon steel slab is hot-rolled and then coiled at a low temperature, and the coiled coil is pre-cold-rolled at a low rolling reduction rate, the crystal grain structure of the hot-rolled sheet is caused by coarse grains during heating of the slab. The state in which carbides are finely precipitated in the elongated grains existing in the elongated grains is maintained, and the processing strain is accumulated in the elongated grains by the preliminary cold rolling, and the fine precipitates are reduced by the subsequent inhibitor precipitation annealing. It was discovered that the secondary recrystallization was fully expressed when the elongated grains were recrystallized and sized, and then subjected to final cold rolling, followed by decarburization annealing, and final annealing. Ta.

The present invention has been made based on this knowledge, and will be explained in detail below.

The composition of the electromagnetic steel slab to which the present invention is applied is
Tec: 0.02~0.10%, Si: 2.0~
4.0%, Mn: 0102-0.10%, S: 0.
01-0.04%, acid acceptable? 8A/(hereinafter referred to as so1.AI toy): 0.010 to 0.065%, N: 0.0030
-0.0100%, and if necessary, up to 0.08% Cu, 0.03-0.50% (7:l Sn,
0.10% or less) phylum. , 0.01-0.05% Se,
It contains one or more of 0.10% or less of Cr, and the remainder consists of iron and unavoidable impurities.

If C content is less than 0.02%, secondary recrystallization becomes unstable, and if the content is too large, decarburization annealing time becomes longer, so the upper limit is set at 0.10%.

If Si is less than 2.0%, good core loss cannot be obtained.

On the other hand, if its content increases, cold rollability deteriorates, so 4
．． 0% or less.

Mn is a component that combines with S to form the inhibitor MnS and contributes to the expression of secondary recrystallization, and also forms the inhibitor MnSe with Se that is selectively included. In order for these inhibitors to exhibit their effects, Mn needs to be 0.02% or more and 0.10% or less, S needs to be 0.01% or more and 0.04% or less, and Se is 0.01 to 0.
．． 05% is required.

s ol, AI combines with N and the inhibitor Δ! It is a component that forms N, and in order to achieve its effect, s
ol, AI hao, 010% or more, 2, 0.065% or less, and N needs to be 0.0030% or more and 0.0100% or less.

In addition to the above components, if necessary, Sn, Cu, Mo
.

Contains Cr. When Sn has a high Si content, it has the effect of preventing destabilization of secondary recrystallization, and also has the effect of segregating at grain boundaries and promoting the development of secondary recrystallization. is 0.03~0.50% required.Cu
It has the effect of improving magnetic properties by preventing deterioration of the haf-orsterite G1 film, and in order to achieve this effect,
The content of O, within 8% is required. MO and Cr segregate at grain boundaries2 and have the effect of stabilizing secondary recrystallization, and in order to achieve this effect, B. is o, 10% or less,
Cr is 0. It is necessary to contain 0% or less of I. One or more of these selected components may be contained.

An electromagnetic loss slab containing the above-mentioned steel composition with the balance being iron and unavoidable impurities is produced by a known method, for example, by continuous casting. The slab is a known 128
After heating to a temperature above 0°C, it is hot rolled.

Hot rolling is performed at a finishing temperature of 900° C. or higher, and the material is then wound up, but the cooling conditions after hot rolling are important. This point will be discussed with reference to experimental data.

A magnetic steel slab with a steel composition not shown in Table 1 was used as a test material,
The slab was heated at 1360°C and hot rolled at a finishing temperature of 1050°C.

Table 1 After the hot rolling was completed, the coiling conditions were changed and the coiling temperature was changed as shown in Table 2, and the samples were wound and cooled in water or allowed to cool. Next, it was preliminarily cold rolled, subjected to inhibitor precipitation annealing, and then cold rolled at a reduction rate of 85% to a plate thickness of 0.17 mm.
Decarburization annealing was performed at 40°C, an annealing separator containing MgO as a main component was applied, and final annealing was performed at 1200°C for 20 hours. Regarding the steel plate, magnetic flux density BIG and iron loss W l f
f/S. were measured, and the results are also shown in Table 2.

As seen from this result, after hot rolling, the
The wires (1-A, 1-B) were wound at a low temperature of 400°C or lower and 200°C or higher, and then water-cooled.
J% W, qys. Both are excellent. Further, when the macrostructure of the crystal grains was investigated, secondary recrystallization was sufficiently expressed in the material under the above conditions. On the other hand, 500°C
(1-C), rolled at 460°C and then cooled in water (1-D), and rolled at 350°C and cooled (1-E), all have magnetic flux densities. B. , iron tMW+t/so is inferior.

From now on, in the present invention, the winding temperature is 400°C or less.
℃ or higher. Furthermore, since winding becomes unstable below 200°C, the lower limit is set at 200°C. Then it is cooled in water. Under these conditions, carbides do not precipitate coarsely and maintain a finely precipitated state, and are particularly effective against carbides that coarsen during slab heating and become elongated grains during hot rolling.
Precipitates finely within the grains. This influences the slip deformation in the subsequent preliminary cold rolling, prevents the movement of dislocations, and accumulates working strain in the elongated grains.Inhibitor precipitation annealing recrystallizes and refines the grains. We believe that dispersed precipitation can be achieved.

Further, it is preferable that water cooling after winding is performed within 15 minutes.

The cooled coil is pre-cold rolled and then subjected to inhibitor precipitation annealing. Preliminary cold rolling is preferably carried out at 20 to 50%, and inhibitor precipitation annealing is carried out at 108%.
Heat to 0 to 1160°C x 60 seconds or less, then further heat to 800°C
Hold at ~1o00'c for 30-90 seconds, 15-100''
Preferably, the cooling rate is C/sec.

Thereafter, the final cold rolling is performed, and this cold rolling may be performed once, and is performed under pressure with a rolling reduction of more than 80% and less than 95%. If this rolling reduction rate is less than 80%, the magnetic flux density will deteriorate;
If it exceeds 5%, secondary recrystallization becomes poor.

The plate thickness is set to 0.15 to 0.23 mm by the final cold rolling, but if the thickness exceeds 0.23 mm, the effect of reducing iron loss is small, and
A process such as that of the present invention is not necessarily necessary.

On the other hand, if the thickness is less than 0.15 mm, secondary recrystallization becomes unstable.

Next, known methods are employed for decarburization annealing and final annealing by applying an annealing separator.

(Example) An example will be described.

Using the electromagnetic steel slab shown in Table 3, hot rolling, pre-cold rolling, and inhibitor precipitation annealing under the conditions shown in Table 4,
It was cold rolled at a reduction rate of 88% to give a final thickness of 0.17 mm. Then, it was decarburized annealed at 840°C, coated with MgO,
Finish annealing was performed at 1200"C x 20 hours.

The magnetic flux density B of the steel plate. , iron H4W177,. The results are also shown in Table 4.

(Effects of the Invention) As described above, according to the present invention, secondary recrystallization is sufficiently expressed even by one-same rolling that does not require intermediate annealing. :ul
It depends on whether the board is obtained or not.

Claims (2)

[Claims] (1) In weight%, C: 0.02 to 0.10%, Si: 2
．． 0-4.0%, Mn: 0.02-0.10%, S: 0
．． 01-0.04%, sol. Al: 0.010-0.
065%, N: 0.0030 to 0.0100%, the balance consisting of iron and unavoidable impurities, hot rolled, inhibitor precipitation annealed, rolling reduction of more than 80% ~ 9
Orientation consisting of cold rolling one or more times including final cold rolling under 5% compression to a final thickness of 0.15 to 0.23 mm, decarburizing annealing, applying an annealing separator, and final annealing. In the method of manufacturing electrical steel sheets, after hot rolling, 200 to
A method for producing a thin grain-oriented electrical steel sheet with excellent magnetic properties, which comprises winding at a temperature of 400°C, water-cooling the wound coil, pre-cold rolling, and inhibitor precipitation annealing. (2) In weight%, C: 0.02 to 0.10%, Si: 2
．． 0-4.0%, Mn: 0.02-0.10%, S: 0
．． 01-0.04%, sol. Al: 0.010-0.
065%, N: 0.0030-0.0100%, Sn: 0.03-0.50%, Cu: 0.08% or less, Mo: 0.10% or less, Se: 0.01-0 .05%
, Cr: 0.10% or less, containing one or more types,
An electrical steel slab, the remainder of which is iron and unavoidable impurities, is hot rolled and annealed with inhibitor precipitation to achieve a rolling reduction of 80%.
The final plate thickness is 0.15 to 0.23 mm by one or more cold rolling operations including final cold rolling under ultra-95% compression, decarburization annealing, application of an annealing separator, and final annealing. In the method of manufacturing grain-oriented electrical steel sheet, after hot rolling, 2
Winding at a temperature of 00 to 400°C, cooling the wound coil with water,
A method for producing a thin grain-oriented electrical steel sheet with excellent magnetic properties, which comprises preliminary cold rolling and inhibitor precipitation annealing.