JPH02200733A - Manufacture of high magnetic density grain-oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To obtain the grain-oriented silicon steel sheet having high magnetic flux density by subjecting a silicon steel slab having specified C, Si, Mn, etc., to nitriding before, during or after decarburization annealing before finish annealing or further in the heating stage of finish annealing. CONSTITUTION:The silicon steel constituted of, by weight, 0.025 to 0.095% C, 2 to 4% Si, 0.08 to 0.45% Mn, <=0.015% S, 0.01 to 0.06% Al, 0.003 to 0.013% N and the balance Fe is refined. The slab of the steel is hot-rolled at <1280 deg.C and is left as hot-rolled or is subjected to hot rolled sheet annealing. Next, cold rolling is executed for one time or plural times with process annealing. Before, during or after decarburization annealing, the steel sheet is subjected to short time nitriding to form an inhibitor essentially consisting of (Al-Si)N. Then, the steel sheet is further subjected to nitriding in the heating stage of final annealing after coated with an annealing release agent.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a directional electrosand plate having an extremely high magnetic flux density.

(Prior Art) High-quality electrical steel sheets are mainly used for iron cores of transformers, generators, and other electrical equipment, and must have good magnetic properties such as excitation properties and iron loss properties. Grain-oriented electrical steel sheet utilizes the secondary recrystallization phenomenon to form a rolled surface at 7 (11
It is obtained by developing Thurlow, 4w crystal grains having the so-called Goss orientation with the (001) axis in the rolling direction. Secondary recrystallization is a well-known process, which is achieved by annealing, but secondary recrystallization occurs. In order to achieve η5 of 1 minute, it is necessary to
Fine /lnNMn5. The so-called precipitate of M□nse nato. Inhibitor, = , 1 must be present.

For this reason, the electrical steel slab has a temperature of 1350-1400℃f'j
Zr is heated to high temperatures to form an inhibitor.
y & min e.g. Affi, Mn, S, S e +
Annealing is performed to completely dissolve N'S' in solid solution and precipitate the inhibitor finely in the intermediate plate before the second hot rolling treatment or final cold rolling.

Applying this additional treatment? (51) Grain-oriented electrical steel sheets with high density are now being manufactured, but since the heating of the electromagnetic mesh slab is carried out at high temperatures as mentioned above, the amount of molten sgale produced is reduced by humans in the heating furnace. In addition, there are problems such as the height of the heating furnace and surface flaws.

A method for manufacturing grain-oriented electrical steel sheets that lowers the slab heating temperature is being considered. For example, in addition to A and e, Zr, Ti, B, Nb, Ta, V, and C
By containing nitride-forming elements such as r and Mo,
A manufacturing method is disclosed in which slab heating is performed at 1100-1260°C. JP-A No. 59-190324 discloses that the C content is as low as 0.01% F, and S, Se, AI,
A magnetic steel slab selectively containing B is mixed with the raw material, and during primary recrystallization annealing after cold rolling, pulse annealing is performed in which the surface of the steel plate is repeatedly heated to high temperatures for a short period of time. A manufacturing method is disclosed in which the temperature is 1300°C or less. Also, in Japanese Patent Application Laid-Open No. 59-5622, Mr+ is O, 08 to 0.45%, S is 0.007% or less, and (
By lowering the Mn:1(S) product and using an electromagnetic mesh slab containing /V, P, and N, we are using a manufacturing method that lowers the slab heating temperature to 1280°C or less. .

(Problems to be Solved by the Invention) As described above, in the production of grain-oriented electromagnetic steel sheets, methods using low-temperature slab heating have been studied, and although some effects have been achieved, secondary recrystallization occurs. It is difficult to form a sufficiently effective inhibitor for high density f1 to be industrially stable! ! ! Further study is required to construct a 4" model.

7. The present invention heats the electromagnetic steel slab at a low temperature of less than 1280C to prevent the occurrence of molten scale.
While obtaining advantages such as prevention and reduction of heating energy, grain-oriented electrical steel sheets with extremely high magnetic flux density - [industrially stable,
What you get is ``1 target.''

(To solve the problem) The gist of the present invention: 0.0
25~□0.095%.

Si; 2.0・-・4.0%1 MRI:0.0B”=0.45% S: 0.015% or less Eight! :0.010~0.060% 0.0030-0.0130%.

Including 1. Also, if necessary, P: 0.005...
0.045%.

Cr; 0.07 to 0.25% of one or two types of 1MO2, Nh, Sti.

1.5% in total of one or more of Sn, Ti, Te, 11.
An electrical steel slab containing F and the remainder being iron and unavoidable pure substances is heated to a temperature of less than 1280 ° C. 2, hot rolled 7, as hot rolled or hot rolled sheet annealed, once. Or intermediate annealing and 2 recovery = F cold rolling 2, nitriding the steel plate for a short time before, during or after decarburization annealing 1'\ (AZ, 5
i) A high-magnetic-flux-density-direction external conductor characterized by forming an inhibitor having an N--based composition, separating it by annealing, and further nitriding it in the heating process of final annealing after applying fll+!
It is in the manufacturing method of AM board.

Hereinafter, the present invention will be explained in detail.

The present inventors applied low-temperature slab heating, which heats a magnetic steel slab to an unknown temperature of 1280"C, to conduct a test S1 test in order to industrially stably mold a grain-oriented electrical steel sheet with a high magnetic flux density. As a result, when the components that form inhibitors, such as Al, Mn, S, and N, are not dissolved in solid solution during the slab heating stage, and nitriding is performed for a short time before, during, or after decarburization annealing, highly functional inhibitors can be formed. (Δ/, 54)N is uniformly dispersed in the steel sheet and formed as 2, and when it is further nitrided during the heating process of final annealing, a new fine inhibitor (Aj, 5i) is formed.
It has been found that N is formed and that a magnetic leakage flux density material can be stably obtained.

The composition of the electromagnetic steel slab to which the present invention is applied is as follows.

When the C content decreases, secondary recrystallization becomes unstable,
Further, even if secondary recrystallization is performed, the magnetic flux density will be low (1025% or more). On the other hand, if the content increases, the decarburization annealing time will become longer, so the content should be 0.095% or less.

Si is a necessary component for reducing iron m and forming an inhibitor, and for this purpose it is contained in an amount of 2.0% or more.

On the other hand, if the f1 content increases, plate breakage, edge cracking, etc. will occur frequently during cold rolling, so it should be kept at 4.0% or less.

Mn has the effect of preventing hot brittleness and improving the quality of the glass coating, and 0.08% or more is required to achieve this effect. On the other hand, if the content increases, the magnetic flux density deteriorates, so the content should be 0.45% or more. Furthermore, in the present invention, since the slab heating is performed at a temperature below 1280°C, for example, the compound MnS with S is not completely dissolved in solid solution, but as an inhibitor of Mn.
Since S is not used, the limit is the same as described above.

S is set to 0.015% or less in order to prevent segregation and inhibit the growth of normal secondary recrystallized grains.

Al combines with N or Si to form (AI, 5i)N2, which is necessary for the development and stability of secondary recrystallization, and is therefore included in an amount of 0.010% or more. On the other hand, since the slab heating temperature is lower than 1280°C, M is completely dissolved in solid solution.
When the content of I increases, inappropriate A,
Since IN is formed, the content should be 0.060% or more.

N is contained in an amount of 0.0030% or more in order to combine with the aforementioned AI, Si, etc. and stabilize secondary recrystallization. However, if the content increases, surface defects called blisters will occur, so the content should be 000130% or less.

Furthermore, 11! of P + Cr as necessary. i or 2 types. Also, Mo, Sea Nb+ Sh+
Contains one or more of Sn, Ti*Tet 8.

In the case of low-temperature slab heating, P has the effect of increasing the magnetic flux density, and in order to exhibit this effect, 0.005% or more is required. On the other hand, if the content increases, cold rollability deteriorates, so the content should be 0.045% or less.

Cr has the effect of increasing magnetic properties by expanding the range of AI that can obtain high magnetic flux density.
．． 0.7% or more is required. - As the amount of carbon content increases, the decarburization performance deteriorates, so it should not exceed 0.25%.

Mo, Si, Nh, Sb, Sn, Ti, Te, and B are added within 0.30% of each component to improve magnetic properties.
However, if the total amount of fli contained increases, the magnetic flux density deteriorates, so the amount of fli is kept at 1.5%.

Electromagnetic steel slabs are heated in a converter or electric furnace at a cold temperature of 1:゛.
;'-furnace)6, then vacuum degassed (vacuum degassing treatment), and formed by continuous casting2. or ingot-forming to blooming rolling.

The electromagnetic steel slab is heated prior to hot rolling, and the heating temperature is less than 1280°C, which saves energy, prevents IE from generating molten scale, and prevents surface flaws. At this heating temperature, I'd in the electromagnetic steel strip is not completely dissolved in solid solution but becomes incompletely dissolved in solid solution. In addition, M with an even higher solid solution temperature
Naturally, nS becomes a more incomplete solid solution.

After the dump heating, it is hot rolled and optionally annealed, or cold rolled without annealing. Cold rolling is performed once or twice with intermediate annealing in between to achieve the final thickness.

In the present invention, as mentioned above, since the slab is heated at a low temperature, there is no inhibitor present in the steel sheet.Therefore, before the onset of secondary recrystallization, N is introduced into the steel to inhibit it (81.
5i) Form N. Strong inhibitor effect (fJ
, S i ) N cannot be obtained even if the thickness of the steel plate is added to the width.

Therefore, in the present invention, we conducted an experiment to solve this problem4 and found that the steel plate was nitrided for a short time under the decomposition of nitrogen compound gas in the form of strips or tubes before, during, or after decarburization annealing. 7,5i) It was confirmed that N was formed.

When the nitriding treatment time is increased to, for example, 3 minutes, the magnetic flux density of the product deteriorates. The amount of nitriding should be 120 to 2001) PM. The same effect can be obtained whether nitriding is performed before decarburization annealing, during decarburization annealing, or after decarburization annealing. Further, nitriding is preferably carried out in an atmosphere mixed with NH while the strip is being passed through, but the method is not limited thereto. It is also possible to pass through a salt bath containing a nitrogen compound, and the first stage may be any one that can perform nitriding for a short time.

After that, an annealing separator is applied to the sakikari and annealing is performed. In the final annealing, the size and dispersion state of the previously formed inhibitor (AC3i)N change slightly during heating at elevated temperatures, so in the present invention, nitridation is further performed in the heating process before the first-order crystal formation. For nitriding, a nitriding gas such as N, N2114, etc. is added to the annealing atmosphere. NO 100-1000PI
A nitrogen compound such as MnN or silicon nitride is added each time M is added or annealing is performed.
This can be achieved through various means. This amount of nitriding is 20~・10
0 yen) h, a new inhibitor (AI.

5t) N is formed, the secondary reconsolidation occurs sufficiently, and occurs throughout the entire steel plate, resulting in an extremely high magnetic flux density. Also, the temperature range of the heating process for nitriding is 600 to 9
It is sufficient to deviate from 00°C.

Next, examples will be described.

Example-1 A slab having the composition shown in Table 1 was heated under the conditions shown in the same table, hot-rolled to a depth of 2.3 m:ml7, and then rolled as a hot-rolled sheet or The hot-rolled sheet is annealed, and as shown in the same table, it is rolled once or twice with intermediate annealing as shown in the table.
The plate jV was 30I71m. After that, 850°CX3
Decarburization annealing was performed in an atmosphere consisting of 11.70% with a dew point of 60° C. for 1 minute. 1111 During or after the decarburization annealing, nitriding was performed as shown in the same table. After that, annealing separator 4! : Applied to a steel plate and finish annealed. During heating for final annealing, the material was further nitrided as shown by a colleague. The magnetic properties and coating properties of the obtained steel plate were measured7, and the results are shown in Table 2.

(Notes) 1. Film adhesion; 180 degree bending without releasing i + diameter 2, + 1 defect with a spot of metallic luster in the area where there is no glass coating (effect of the invention) less than 128 O'C When manufacturing a sheet of ζζ-oriented electrical steel by applying low-temperature slab heating, conventionally nitriding was performed by pre-annealing to form an inhibitor, but in the present invention, this nitriding is performed before pre-annealing. Strip-shaped g-Q is performed before, during or after decarburization annealing.

Because it is carried out during the heating process of double annealing, ・(A7, 5i) N with high inhibitory effect is formed stably (7), and (j! (in terms of things).

Claims (4)

[Claims] (1) C in weight%; 0.025-0.095%, Si;
2.0 to 4.0%, Mn; 0.08 to 0.45%, S; 0.015% or less Al; 0.010 to 0.060%, N; 0.0030 to 0.0130%, A magnetic steel slab containing iron and unavoidable impurities is heated to a temperature of less than 1280 ° C. and hot rolled,
The steel sheet is annealed as hot-rolled or hot-rolled, cold-rolled once or twice or more with intermediate annealing, and the steel sheet is nitrided for a short time before, during, or after decarburization annealing to produce (Al, Si)N. A method for producing a high magnetic flux density grain-oriented electrical steel sheet, characterized in that an inhibitor having a main composition of (2) C in weight%; 0.025-0.095%, Si;
2.0 to 4.0%, Mn; 0.08 to 0.45%, S; 0.015% or less Al; 0.010 to 0.060%, N; 0.0030 to 0.0130%, Contains, furthermore, P; 0.005 to 0.045%, Cr
; An electrical steel slab containing 0.07 to 0.25% of one kind or two kinds, with the balance consisting of iron and unavoidable impurities.
Heated to a temperature of less than 80°C, hot rolled, annealed as hot rolled or hot rolled sheet, cold rolled once or twice or more with intermediate annealing, before, during or after decarburization annealing. A high magnetic flux density direction characterized by nitriding a steel plate for a short time to form an inhibitor whose main composition is (Al, Si)N, and further nitriding in the heating process of finish annealing after applying an annealing separator. manufacturing method of magnetic steel sheet. (3) C in weight%; 0.025-0.095%, Si;
2.0 to 4.0%, Mn; 0.08 to 0.45%, S; 0.015% or less Al; 0.010 to 0.060%, N; 0.0030 to 0.0130%, Contains, furthermore, Mo, V, Nb, Sb, Sn, Ti,
An electrical steel slab containing one or more of Te and B in a total of 1.5% or less, with the balance consisting of iron and unavoidable impurities,
Heated to a temperature of less than 80°C, hot rolled, annealed as hot rolled or hot rolled sheet, cold rolled once or twice or more with intermediate annealing, before, during or after decarburization annealing. High magnetic flux density characterized by nitriding the steel plate for a short time afterwards to form an inhibitor whose main composition is (Al, Si)N, and further nitriding in the heating process of finish annealing after applying an annealing separator. A method for manufacturing grain-oriented electrical steel sheets. (4) C in weight%; 0.025-0.095%, Si;
2.0 to 4.0%, Mn; 0.08 to 0.45%, S; 0.015% or less Al; 0.010 to 0.060%, N; 0.0030 to 0.0130%, Contains, furthermore, P; 0.005 to 0.045%, Cr
; 0.07-0.25% of one or two types, Mo, V, N
A total of one or more of b, Sb, Sn, Ti, Te, and B
．． An electrical steel slab containing 5% or less and the remainder consisting of iron and unavoidable impurities is heated to a temperature below 1280°C, hot rolled, as hot rolled or hot rolled sheet annealed, and once or intermediate annealed. Cold rolling the steel plate two or more times, nitriding the steel plate for a short time before, during or after decarburization annealing to form an inhibitor whose main composition is (Al, Si)N, and applying an annealing separator. A method for producing a high magnetic flux density grain-oriented electrical steel sheet, characterized in that it is further nitrided in the heating process of final annealing after nitriding.