JPH06207216A - Production of grain-oriented electrical sheet with ultrahigh magnetic flux density - Google Patents

Abstract

PURPOSE:To produce a grain-oriented electrical sheet having high magnetic flux density by adding specific elements of the periodic table to a molten steel with specific composition into a bubble-like state and then per forming a rolling. CONSTITUTION:At the time of producing the grain oriented electrical sheet by using a material having a composition consisting of, by weight, 0.03-0.15% C, 2.5-4.5% Si, 0.01-0.70% Mn, 0.005-0.045% S, 0.010-0.065% thermally soluble Al, 0.0030-0.0450% N, and the balance Fe with inevitable impurities, at least one or more kinds among low melting metals of <=1000 deg.C melting point, constituted of the group IVb and Vb elements of the periodic table, and their compounds are added to a molten steel by 0.0005-0.20% by concentration after solidification. After casting, it is heated up to >=1000 deg.C to form the low melting metals and/or their compounds into bubble-like and/or liquid state and is hot rolled. Thus, the grain oriented electrical steel sheet having ultrahigh magnetic flux density can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ultrahigh magnetic flux density unidirectional electrical steel sheet having a highly developed {110} <001> orientation, ie, Goss orientation, which is used for iron cores of transformers and the like.

[0002]

2. Description of the Related Art Unidirectional electrical steel sheets are mainly used as a soft magnetic material for iron core materials of transformers and other electric equipment, and must have good magnetic excitation characteristics and iron loss characteristics. . Usually, magnetic flux density B ₈ (magnetic flux density at a magnetic field strength of 800 A / m) or B ₁₀ is used as an index showing the excitation characteristic, and W is used as an index showing the iron loss characteristic.
_17/50 (iron loss per unit weight when magnetized to 1.7 _{T at} 50 Hz) and W _13/60 are used. A unidirectional electrical steel sheet has a so-called “110” plane on the steel sheet surface and a <001> axis in the rolling direction by causing secondary recrystallization in the final annealing step at a temperature of 900 ° C. or higher at the final stage of the manufacturing process. It has been obtained by developing the Goth tissue.
Among them, a magnetic flux density B ₈ having an excellent excitation characteristic of 1.88 T or more is called a high magnetic flux density unidirectional electrical steel sheet.

As a typical method for producing a high magnetic flux density grain-oriented electrical steel sheet, Japanese Patent Publication No. 40-15644 and Japanese Patent Publication No. 51-
13469 publication is mentioned. It can be said that the high magnetic flux density unidirectional electrical steel sheets currently produced on a global scale are produced based on the above two patents. Therefore, the magnetic flux density B _{8 of the} product based on the above patent is 1.88 to at most 1.95.
The value is about T, which is only about 95% of the saturation magnetic flux density 2.03T of 3% Si steel. In recent years, however, social demands for energy conservation and resource conservation have become more intense,
The demands for reducing the iron loss and improving the magnetization characteristics of unidirectional electrical steel sheets are becoming fierce. On the other hand, technically, a magnetic domain control technique such as laser irradiation is used as a method for reducing iron loss.
968, Japanese Patent Publication No. 57-2252, etc., and in this method, the demand for a material having a higher magnetic flux density has become stronger as a means for reducing iron loss. In other words, the present situation is waiting for the appearance of a means for making the magnetic flux density B ₈ of the conventional high magnetic flux density unidirectional electrical steel sheet closer to the ideal orientation.

As means for achieving this object, the present inventors have proposed in Japanese Patent Publication No. 57-1565 a method of adding a carbonate-containing material to the molten steel of a conventional Al-containing high magnetic flux density unidirectional electrical steel sheet. However, although this method has feasibility in the laboratory, it is not practiced on an industrial scale.
Furthermore, the present inventors proposed a temperature gradient annealing method in Japanese Patent Publication No. 58-50295. With this method, a stable magnetic flux density B ₈ of 1.95 T or more can be obtained for the first time. However, when this method is carried out with a factory-sized coil foam, heating from one end of the coil, and cooling at the other end to create a temperature gradient entails a great loss of thermal energy, which poses a serious problem for industrial production. I am addicted.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to avoid such problems and to manufacture an ultrahigh magnetic flux density grain-oriented electrical steel sheet having an extremely high magnetic flux density. It is disclosed in JP-A-50-72817 and JP-A-51-78733 that Bi is added to the material for unidirectional electrical steel sheet.
JP-A No. 53-39922, etc., all of these patents contain S and Se as essential inhibitors and contain elements having the same effects as Sb and As. This is one meaning and is merely positioned as an alternative element of Sb.

Further, it can be said that these patents do not essentially contain Al as an inhibitor element, and differ from the present invention in character. Further containing Bi is disclosed in JP-A-51-107499 and JP-A-63-10012.
It is also described in JP-A-7. These patents are similar to the present invention in that they contain Al as an essential inhibitor, but they are all positioned as the same acting element such as Sb and As, and therefore, there is no description of examples containing Bi added, The idea and character of addition of Bi etc. is unknown.

[0007]

The features of the present invention are as follows. 1) wt%, C: 0.03 to 0.15%, Si: 2.
5 to 4.5%, Mn: 0.01 to 0.70%, S: 0.
005-0.045%, acid-soluble Al: 0.010
0.065%, N: 0.0030 to 0.0450%, balance: Fe and a material consisting of unavoidable impurities as a starting material, when producing a grain-oriented electrical steel sheet, in molten steel, IVb group of the periodic table, 1000 ℃ composed of Vb group elements
0.0005 to 0.50% of the following low melting point metal and at least one kind of compound of the metal in the concentration after solidification
After being added and cast, it is heated to 1000 ° C. or higher to make the low melting point metal and / or the compound of the metal into bubbles and / or liquids in steel, and hot rolling.

2) C: 0.03 to 0.15 by weight%
%, Si: 2.5 to 4.5%, Mn: 0.01 to 0.7
0%, S: 0.005-0.045%, acid-soluble Al:
0.010 to 0.065%, N: 0.0030 to 0.0
When producing a unidirectional electrical steel sheet with a starting material of 450%, the balance: Fe and inevitable impurities,
An alloy having a low melting point of 1000 ° C. or less or a mixture of the alloys, which is composed of elements of Group IVb and Group Vb of the periodic table, was added to molten steel in a concentration after solidification of 0.0005 to 0.50% and cast. Then, it is heated to 1000 ° C. or higher to make the low melting point alloy or a mixture of the alloys into a bubble and / or liquid state in steel, and hot rolling.

3) C: 0.03 to 0.15 by weight%
%, Si: 2.5 to 4.5%, Mn: 0.01 to 0.7
0%, S: 0.005-0.045%, acid-soluble Al:
0.010 to 0.065%, N: 0.0030 to 0.0
450%, Sn: 0.02 to 0.50%, Cu: 0.0
1 to 0.10%, balance: Fe and a material consisting of unavoidable impurities as a starting material, in the production of a grain-oriented electrical steel sheet, a molten steel containing 1000 elements of IVb group and Vb group of the periodic table The low melting point metal having a melting point of ℃ or less and at least one kind of the compound of the metal have a concentration of 0.0 after solidification.
005 to 0.50% is added, and after casting, the mixture is heated to 1000 ° C. or higher to make the low melting point metal and / or the compound of the metal bubble and / or liquid in steel, and hot rolling.

4) C: 0.03 to 0.15 by weight%
%, Si: 2.5 to 4.5%, Mn: 0.01 to 0.7
0%, S: 0.005-0.045%, acid-soluble Al:
0.010 to 0.065%, N: 0.0030 to 0.0
450%, Sn: 0.02 to 0.50%, Cu: 0.0
1 to 0.10%, balance: Fe and a material consisting of unavoidable impurities as a starting material, in the production of a grain-oriented electrical steel sheet, a molten steel containing 1000 elements of IVb group and Vb group of the periodic table A low-melting point alloy or a mixture of the alloys having a melting point of 0.0005 to 0.50% is added at a concentration after solidification, and the mixture is cast and heated to 1000 ° C. or higher to obtain the low-melting point alloy or the alloy mixture. Bubble and / or liquefy in steel and hot roll.

5) The IVb group element of 1) or 3) above is Pb, and the Vb group element is Bi.

6) The elements of IVb group of 2) or 4) above are Pb, Sn, and the elements of Vb group are Sb, Bi.

7) 100 of any one of 1) to 6) above
As bubbles and / or liquids in steel at 0 ° C or higher, the size of each bubble and / or liquid is 20
μm or less.

The details of the present invention will be described below. The present inventors have conducted various studies to further increase the magnetic flux density of a so-called high magnetic flux density unidirectional electrical steel sheet, and when producing a unidirectional electrical steel sheet using aluminum nitride as a main inhibitor, in molten steel. A metal having a low melting point of 1000 ° C. or less composed of IVb group and Vb group of the periodic table, one or more kinds of compounds and alloys of the metal, and having a concentration after solidification of 0.0
Add 005 to 0.50%, cast and add 100% of the additive material.
1.95 T or more, which far exceeds the magnetic flux density B ₈ = 1.93 T of the high magnetic flux density unidirectional electrical steel sheet currently on the market by dispersing it in the form of bubbles and / or liquid in steel at 0 ° C. or more, We have succeeded in producing an ultra-high magnetic flux density unidirectional electrical steel sheet of up to 2T.

The reasons for limiting the component composition of the present invention will be described.
If C is less than 0.03%, abnormal grain growth occurs during slab reheating prior to hot rolling, and secondary recrystallization defects called linear fine grains occur in the product, which is not preferable. On the other hand, if it exceeds 0.15%, decarburization in the decarburization annealing step is likely to be incomplete, which causes magnetic aging in the product, which is not preferable. If the Si content is less than 2.5%, the eddy current loss of the product will increase.
%, It becomes difficult to perform cold rolling at room temperature, which is not preferable.

Mn and S form a compound with manganese sulfide or a low-melting point metal and become a precipitation site of aluminum nitride or the like, so that Mn and S act as auxiliary inhibitors.
0.01-0.70%, S: 0.005-0.045%
is necessary. The reason is that if S is less than 0.005% and Mn is less than 0.01%, a sufficient inhibitory effect cannot be obtained, while if S exceeds 0.045%, desulfurization time is required. Acid-soluble Al is a main inhibitor constituent element for producing a high magnetic flux density unidirectional electrical steel sheet, and if it is less than 0.010%, the amount is insufficient and the inhibitor strength is insufficient. On the other hand, if it exceeds 0.065%, the precipitated aluminum nitride becomes coarse and, as a result, the inhibitor strength decreases, which is not preferable. N, like the acid-soluble Al, is a main inhibitor constituent element, and 0.0030 to
If it deviates from 0.045%, the optimum conditions for the inhibitor will be broken, which is not preferable.

Further, Sn is effective as an element for stabilizing the secondary recrystallization of a thin product, and has the effect of reducing the secondary recrystallization grain size, but if it is 0.05% or less, the effect is not sufficient. However, it is necessary to add 0.05% or more, and even if it exceeds 0.5%, its action is saturated, so from the viewpoint of cost increase, it is limited to 0.5% or less. Cu is effective as a film-improving element for the Sn-added material. If it is less than 0.01%, the effect is small, and if it exceeds 0.10%, the magnetic flux density of the product is lowered, which is not preferable.

When a grain-oriented electrical steel sheet is manufactured by the manufacturing process that causes AlN to function as an inhibitor, which is a feature of the present invention, a low melting point of 1000 ° C. or less, which is composed of IVb group and Vb group of the periodic table, is contained in the steel. At least one or more kinds of metals, compounds and alloys of the metals are added at a concentration after solidification in an amount of 0.0005 to 0.50%, cast, and the additive is made into a bubble and / or a liquid state in steel at 1000 ° C. or higher. Dispersing is extremely effective. The concentration is 0.000 even if it is used alone and / or two or more kinds.
If it is less than 5%, the improvement of the magnetic flux density is slight, and 0.5
If it exceeds 0%, the number of defects in the material increases and the effect of improving the magnetic flux density saturates. Therefore, the upper limit was set to 0.50%.
Although a slight difference in the effect due to the metal here is recognized, it is governed by the size and amount of the bubbles and / or liquid.

As a method of adding an element consisting of IVb group and Vb group of the periodic table, metals, alloys, intermetallic compounds, oxides, carbides, nitrides, sulfides, phosphides, borides,
Halide, silicate, carbonate, borate, sulfate,
A readily available compound form such as nitrate may be used. In particular, the present invention is composed of groups IVb and Vb of the periodic table
A metal having a low melting point of ℃ or less, one or more of the metals and alloys are added in a concentration after solidification of 0.0005 to 0.50% and cast, and the additive is bubbled and / or Alternatively, it is considered that uniform fine dispersion in liquid form many defects and the like when a few atoms of IVb group and Vb group having an atomic radius larger than that of iron atom escape, which becomes a precipitation site of the inhibitor. As a result, (1)
AlN, the main inhibitor, can be effectively and finely dispersed.
(2) It was confirmed that coarsening of crystal grains can be suppressed.

If the size of the bubbles and / or liquid is more than 20 μm in the form of bubbles and / or liquid in steel at 1000 ° C. or higher, they will be crushed during hot rolling, and as a major defect, the surface of the material, etc. Is preferably 20 μm or less because it does not contribute to the improvement of magnetic flux density and the suppression of coarsening of crystal grains.

Next, the manufacturing process conditions will be described.
The starting material for ultra-high magnetic flux density unidirectional electrical steel sheet having the components prepared as described above can be used as the starting material of the present invention even when a usual melting method or casting method is used. Next, this raw material for electromagnetic steel sheets is rolled into a hot rolled coil by ordinary hot rolling. Subsequently, the final plate thickness is obtained by cold rolling of one stage or cold rolling of multiple stages including intermediate annealing, but since the high magnetic flux density unidirectional electrical steel sheet is obtained, the rolling ratio of the final cold rolling (the cold rolling of one stage In the case of hot rolling, the rolling ratio is preferably 65 to 95%. The rolling ratio of the stages other than the final rolling need not be specified.

Before the final cold rolling, 30 at 950 to 1200 ° C.
Annealing is performed for seconds to 30 minutes, and precipitation of AlN is controlled by rapid cooling. The conditions for decarburizing annealing of the cold rolled sheet rolled to the final product sheet thickness by a usual method are not particularly specified, but preferably hydrogen or hydrogen, nitrogen which is wet for 30 seconds to 30 minutes in a temperature range of 700 to 900 ° C. It is better to carry out in a mixed atmosphere.
After the decarburization annealing, the surface of the steel sheet is coated with an annealing separator having a normal composition to prevent seizure in secondary recrystallization annealing and to form a glass film. The secondary recrystallization annealing is performed at a temperature of 1000 ° C. or more for 5 hours or more in hydrogen or a mixed atmosphere thereof. Subsequently, after removing the excess annealing separator, continuous annealing is performed to straighten the coil winding, and at the same time, an insulating coating is applied and baked. Further, it is not necessary to specify the method of magnetic domain subdivision such as laser irradiation, if necessary.

[0023]

【Example】

(Example 1) C: 0.07% by weight, Si: 3.2
A low melting point metal shown in Table 1 was added to molten steel containing 0%, Mn: 0.05%, S: 0.023%, acid-soluble Al: 0.025%, N: 0.008%, and continuous casting was performed. The cast slab was reheated to 1350 ° C. and immediately hot-rolled to obtain a 2.3 mm hot-rolled sheet. The hot rolled sheet was annealed at 1100 ° C and cold rolled to 0.3 mm. Subsequently, decarburization annealing is performed at 850 ° C. to obtain Mg
After the annealing separator containing O as a main component was applied, finish annealing was performed at 1200 ° C.

After the powder remaining on the steel sheet after the finish annealing was removed, the magnetic measurement sample of 60 × 300 mm was sheared and subjected to strain relief annealing at 850 ° C. to measure the magnetic flux density B ₈ . Further, the sample was irradiated with a laser at a pitch of 5 mm to subdivide the magnetic domains. Table 1 shows the measured iron loss values together with the magnetic flux density values. FIG. 1 shows a photograph of the magnetic measurement value in that state, which was observed by a transmission electron microscope on a hot rolled plate containing Bi of the present invention in the form of bubbles and / or liquid. In the figure, the white circles are bubble-like or liquid particles containing Bi.

[0025]

[Table 1]

As is clear from Table 1, the steel sheet obtained according to the present invention has a B ₈ of 1.95 T or more, which cannot be obtained by the conventional method, and has an iron loss characteristic of 0.
An extremely excellent product of 90 W / kg or less was obtained. On the other hand, the steel sheet of the comparative example had a low B ₈ of 1.92 T, and the core loss after magnetic domain refinement showed a high value of 0.96 W / kg. (Example 2) C: 0.08% and Si: 3.5 by weight%
%, Mn: 0.05%, S: 0.022%, acid-soluble A
1: 0.028%, N: 0.0088%, Sn: 0.1
A low melting point metal shown in Table 2 was added to a material containing 2% and Cu: 0.08%. The subsequent steps were the same as in Example 1. Table 2 shows the measured values of the magnetic flux density.

[0027]

[Table 2]

As shown in Table 2, the steel sheet obtained by the present invention is an excellent product having a magnetic flux density B ₈ of 1.95 T or more.

On the other hand, in the steel sheet of the comparative example, B ₈ was 1.92.
It only showed a low value for T.

In the examples of the present invention, the heating before hot rolling was shown only at an example of 1350 ° C., but in the present invention, the additive is heated to 1000 ° C. or higher to disperse the additive in the form of bubbles and / or liquid. As long as it is in a state, even if it is heated to the melting temperature limit of the slab and hot-rolled, the same high magnetic flux density and low iron loss characteristics can be obtained.

[0031]

[Effects of the Invention] A metal having a low melting point of 1000 ° C or less, at least one kind of a compound and an alloy of the metal, which is composed of group IVb and group Vb of the periodic table of the present invention, has a concentration of 0.0005 after solidification ˜0.50% is added and cast, and the additive is dispersed in a steel at 1000 ° C. or higher in a bubble and / or liquid state and hot rolled to produce an ultra-high magnetic flux density unidirectional electrical steel sheet. A product having a high magnetic flux density and an extremely excellent iron loss property after the magnetic domain refining treatment is obtained, which is industrially very useful.

[Brief description of drawings]

FIG. 1 is a photograph of a metal structure of a hot rolled sheet of an electromagnetic steel sheet of the present invention observed with a transmission electron microscope.

Claims (7)

[Claims] 1. By weight%, C: 0.03 to 0.15%, Si: 2.5 to 4.5%, Mn: 0.01 to 0.70%, S: 0.005 to 0. 045%, acid-soluble Al: 0.010 to 0.065%, N: 0.0030 to 0.0450%, balance: Fe and a material consisting of unavoidable impurities as a starting material when producing a grain-oriented electrical steel sheet. , Composed of elements of Group IVb and Group Vb of the Periodic Table in molten steel
0.0005 to 0.50 in concentration after solidification of at least one kind of metal having a low melting point of ℃ or less and a compound of the metal
%, Added and cast, and then heated to 1000 ° C. or higher to make the low melting point metal and / or the compound of the metal into bubbles and / or liquids in the steel, and hot-roll it. Manufacturing method of density unidirectional electrical steel sheet. 2. An alloy having a low melting point of 1000.degree. C. or less or a mixture of the alloys composed of elements of Group IVb and Group Vb of the periodic table in molten steel in a concentration after solidification of 0.0005 to 0.5.
2. Addition of 0%, casting, and then heating to 1000 ° C. or higher to make the low melting point alloy or a mixture of the alloys into bubbles and / or liquids in steel and hot rolling. For manufacturing ultra-high magnetic flux density grain-oriented electrical steel sheet. 3. By weight%, C: 0.03 to 0.15%, Si: 2.5 to 4.5%, Mn: 0.01 to 0.70%, S: 0.005 to 0. 045%, acid-soluble Al: 0.010 to 0.065%, N: 0.0030 to 0.0450%, Sn: 0.02 to 0.50%, Cu: 0.01 to 0.10%, balance : When a unidirectional electrical steel sheet is manufactured using a material consisting of Fe and unavoidable impurities as a starting material, 1000 is formed in molten steel from elements of groups IVb and Vb of the periodic table.
0.0005 to 0.50 in concentration after solidification of at least one kind of metal having a low melting point of ℃ or less and a compound of the metal
%, Added and cast, and then heated to 1000 ° C. or higher to make the low melting point metal and / or the compound of the metal into bubbles and / or liquids in the steel, and hot-roll it. Manufacturing method of density unidirectional electrical steel sheet. 4. A solidified alloy having a low melting point of 1000 ° C. or less or a mixture of the alloys composed of elements of Group IVb and Group Vb of the periodic table in molten steel in a concentration of 0.0005 to 0.5.
4. Addition of 0%, casting, and then heating to 1000 ° C. or higher to form the low melting point alloy or a mixture of the alloys into bubbles and / or liquids in steel and hot rolling. For manufacturing ultra-high magnetic flux density grain-oriented electrical steel sheet. 5. The element according to claim 1, wherein the group IVb element is Pb and the group Vb element is Bi.
The method described. 6. The IVb element is Pb, Sn, and the Vb group element is Sb, Bi.
Alternatively, the method described in 4. 7. Bubbles and / or in steel above 1000 ° C.
Alternatively, the size of each bubble and / or liquid as a liquid is 20 μm or less, and the method according to claim 1.