JP3331478B2 - Manufacturing method of high magnetic flux density unidirectional electrical steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high magnetic flux density unidirectional magnetic steel sheet used for an iron core of a transformer or the like.

[0002]

2. Description of the Related Art Unidirectional electrical steel sheets are mainly used for core materials of transformers and generators. Recently, steel sheets with higher magnetic flux density and less iron loss have been required from the market for energy saving. Has been requested. To achieve low iron loss,
There are known a method of reducing the eddy current loss by increasing the Si content of the steel sheet as much as possible and increasing the specific resistance of the material, and a method of reducing the eddy current loss by reducing the thickness of the product sheet as much as possible. Also, recently, magnetic domain control technology such as laser irradiation on the steel plate surface of a product or forming grooves on the steel plate surface with a toothed roll has been developed and put into practical use, and it is possible to significantly reduce iron loss. Has become. In this case, it is known that the iron loss after the magnetic domain control decreases as the magnetic flux density before the magnetic domain control increases, and it is very important to manufacture a steel sheet having a high magnetic flux density.

[0003] In order to obtain a grain-oriented electrical steel sheet having a high magnetic flux density, it is necessary to obtain a secondary recrystallized structure highly integrated in the {110} <001> orientation, the so-called Goss orientation. It is known that the inhibitor and the primary recrystallization texture greatly influence the secondary recrystallization. About inhibitor, 100-1000Å in steel before finish annealing.
AlN, MnS, MnSe, and the like are generally known because it is necessary to have a certain amount of the dispersed dispersed phase uniformly and finely. Furthermore, the grain boundary segregation elements Sb, Sn,
It is useful to segregate Cu, Mo, Ge, B, Te, As, Bi and the like. On the other hand, the primary recrystallization texture has been conventionally controlled by appropriately combining the respective process conditions of hot rolling, cold rolling and annealing.

[0004] However, when the Si content is increased and the product thickness is reduced, it is difficult to control the secondary recrystallization orientation in finish annealing, and it is difficult to obtain a product having a high magnetic flux density of 0.25 mm or less. It was not easy. One of the causes of the difficulty in controlling the secondary recrystallization orientation when the product thickness becomes thinner is that in order to obtain a thinner product from the same hot rolled sheet, a larger cold rolling reduction is applied, resulting in a disadvantage in texture. That's why. In addition, a method of reducing the thickness of the hot-rolled sheet according to the product sheet thickness is conceivable, but making the hot-rolled sheet thinner inevitably lowers the hot-rolling end temperature, and the precipitation state of MnS, MnSe, etc. This method has a drawback that it becomes inappropriate and magnetic properties deteriorate, and this method has a limit. As a solution to such a problem, there is a method of pre-cold rolling a hot-rolled sheet. Incidentally, in the cold rolling process, it is known that the cold rolling ratio, the work roll diameter, the roughness of the work roll, and the like affect the magnetic properties. In particular, regarding the effect of the work roll diameter on the pre-cold rolling, Japanese Patent Application Laid-Open No. 4-289121 discloses that a hot-rolled sheet is reduced by a rolling mill of (roll diameter) / (sheet thickness) ≧ 50 with a rolling reduction of 0.
Disclosed is a method characterized in that after rolling down in 5 to 15%, hot-rolled sheet is annealed in a temperature range of 700 to 1100 ° C. and finished to a final sheet thickness by two or more cold rollings sandwiching intermediate annealing. I have.

[0005]

Problems to be Solved by the Invention Japanese Patent Laid-Open No. 4-28912
The method proposed in Japanese Patent Publication No. 1 is a method in which cold rolling is performed twice or more in addition to pre-cold rolling and hot-rolled sheet annealing, which increases the manufacturing cost and complicates the process control. There's a problem. Moreover, not using AlN as an inhibitor, final strength cold rolling reduction ratio is relates the manufacturing process of less than 80%, the magnetic flux density B ₈ is not only obtained before and after 1.92 T. The present invention uses AlN as an inhibitor, preliminarily cold-rolled on a hot-rolled sheet, precipitation-annealed,
% Pre-rolling is performed by a cold rolling machine with a work roll diameter / hot rolled sheet thickness of ≧ 60.
The purpose of the present invention is to provide a method for producing a high magnetic flux density unidirectional electrical steel sheet having a high magnetic flux density, a low manufacturing cost, and a simple process control without a complicated process control. is there.

[0006]

The gist of the present invention is as follows: C: 0.015 to 0.100% by weight;
i: 2.0 to 4.0%, Mn: 0.03 to 0.12%,
Sol. Al: 0.010-0.065%, N: 0.0
040 to 0.0100%, one or two selected from S and Se: 0.005 to 0.050%, further Sb, Sn, Cu, Mo, Ge, B, Te, As, and Bi One or more selected from the group consisting of 0.003
After the slab heating is applied to the continuous cast slab containing approximately 0.3% and the balance is substantially Fe, hot rolling, preliminary cold rolling, precipitation annealing, and reduction of 81 to 95% are performed. In the method of producing a high magnetic flux density unidirectional magnetic steel sheet by decarburizing / primary recrystallization annealing, final finishing annealing, and coating application, the final cold rolling is performed to obtain a final sheet thickness of 0.25 mm or less by final strong cold rolling. A method for producing a high magnetic flux density unidirectional magnetic steel sheet, characterized in that the processing is performed at a rolling reduction of 20 to 50% with a cold rolling mill having a roll diameter / hot rolled sheet thickness ≧ 60.

The present inventor has studied a method of manufacturing a high magnetic flux density unidirectional magnetic steel sheet having excellent magnetic properties. As a result, the work roll diameter of the pre-cold rolling is calculated as work roll diameter / hot rolled sheet thickness ≧
It has been found that a value of 60 is very effective. FIG. 1 is an example of the results of an experiment performed by the present inventors. C: 0.077%, Si: 3 in the component range according to the present invention.
29%, Mn: 0.073%, S: 0.021%, So
l. Al: 0.030%, N: 0.0074%, Sn:
A cast slab containing 0.10% and the balance substantially consisting of Fe was continuously cast, and after slab heating, the plate thickness was hot-rolled to 2.30 mm. And it is 1.8 with various cold rolls of work roll diameter.
Pre-cold rolled to 0 mm at a rolling reduction of 22%,
After soaking, the steel was subjected to precipitation annealing in which it was rapidly cooled, and was finally deeply cold-rolled at a reduction ratio of 87.8% to 0.22 mm by a cold rolling mill having a work roll diameter of 100 mmφ to obtain a product sheet thickness. Then, the cold-rolled sheet was subjected to decarburization / primary recrystallization annealing, final finish annealing, and a step of applying a coating to obtain a product. FIG. 1 shows the relationship between the work roll diameter / hot rolled sheet thickness and the magnetic flux density of the pre-cold rolling at this time. This shows that a particularly high magnetic flux density can be obtained when the work roll diameter / hot rolled sheet thickness is ≧ 60.

The components of the present invention and the reasons for the limitations will be described. If the lower limit of C is less than 0.015%, the secondary recrystallization becomes unstable, and the upper limit of 0.100% is C
As the number of carbon dioxide increases, the time required for decarburization becomes longer, which is economically disadvantageous. If the lower limit of Si is less than 2.0%, good iron loss cannot be obtained, and if the upper limit is more than 4.0%, the cold rolling property is significantly deteriorated.

Mn causes hot embrittlement when the lower limit is less than 0.03%, and causes magnetic failure when the upper limit exceeds 0.12%. S and Se are elements necessary for forming MnS and MnSe, and one or two of these elements have a lower limit of 0.1.
If it is less than 005%, the absolute amounts of MnS and MnSe are insufficient,
If the upper limit is more than 0.050%, hot cracking occurs, and it is difficult to purify by final finishing annealing.

Sol. Al is an element necessary for forming AlN. If the lower limit is less than 0.010%, the absolute amount of AlN is insufficient, and if the upper limit is more than 0.065%, an appropriate dispersion state of AlN cannot be obtained. N is an element necessary for forming AlN. If the lower limit is less than 0.0040%, the absolute amount of AlN is insufficient.
Cannot be obtained in an appropriate dispersion state.

Sb, Sn, Cu, Mo, Ge, B, T
e, As and Bi segregate at the grain boundaries and stabilize the secondary recrystallization, but if the content of one or more selected from these is less than the lower limit of 0.003%, the segregation amount will be insufficient,
The upper limit of 0.3% is due to economic reasons and decarbonization. The work roll diameter of the pre-cold rolling is set to work roll diameter / hot rolled sheet thickness ≧ 60. If it is smaller than this, the magnetic flux density cannot be increased.

The preliminary cold rolling is performed in one or more passes, and the total reduction is set to 20 to 50%. If less than 20%
Magnetic defects are caused by the linear fine particles. Preliminary cold rolling rate is 50%
If it exceeds, the texture becomes inappropriate, and the magnetic flux density is significantly reduced. Regarding the rolling reduction of the final strong cold rolling, if it is less than 81% or more than 95%, the texture becomes inappropriate, so that the secondary recrystallization becomes unstable.

The reason why the thickness of the product is limited to 0.25 mm or less is to obtain a product with low iron loss in response to recent demand needs.

[0014]

【Example】

Example 1 C: 0.068%, Si: 3.19%, Mn: 0.07
8%, S: 0.021%, Sol. Al: 0.021
%, N: 0.0079%, Sn: 0.14%, Cu:
Continuously casts a slab containing 0.07%, with the balance substantially consisting of Fe, slab-heated and hot-rolled to 2.1 mm
A thick hot coil was used. Then, it was pre-cold rolled to 1.30 mm with various work roll diameters at a rolling reduction of 38%,
Precipitation annealing was performed by quenching after soaking at 50 ° C for 2 minutes.
The final cold rolling was performed at a rolling reduction of 86.9% using a cold rolling mill having a work roll diameter of 00 mmφ, and the sheet thickness was set to 0.17 mm. Next, the obtained cold-rolled sheet was subjected to decarburization / primary recrystallization annealing, final finish annealing, and a step of applying a final coating to obtain a product. Indicates the work roll diameter of the pre-cold-rolled at this time, the magnetic flux density B ₈ of the work roll diameter / hot-rolled sheet product obtained with thicknesses in Table 1. From this, it can be seen that the present invention example can obtain a higher magnetic flux density than the comparative example.

[0015]

[Table 1]

Example 2 A slab containing various components was continuously cast, slab-heated, and then hot-rolled to obtain a hot-rolled sheet having a thickness of 1.8 mm. Cold roller with a work roll diameter of 70 mmφ where work roll diameter / hot rolled sheet thickness = 38.9, and work roll diameter / hot rolled sheet thickness = 3
Preliminarily cold-rolled to 1.10 mm with a rolling reduction of 39% using a cold-rolling machine with a work roll diameter of 600 mmφ to obtain 33.3,
After soaking at 2 ° C for 2 minutes, quenching precipitation annealing was performed, and 0.15 m
86.4% with a cold roll mill with a work roll diameter of 70 mmφ to m
The final cold rolling was performed at a rolling reduction of. Thereafter, the obtained cold rolled sheet was subjected to decarburization / primary recrystallization annealing, final finish annealing, and a step of applying a final coating to obtain a product. Component of the time of slab, Table 2 the work roll diameter and product of the magnetic flux density B ₈ of the pre-cold rolled, Table 3 (Table 2 continued -1), shown in Table 4 (Table 2 continued -2). This shows that the present invention example can obtain a higher magnetic flux density than the comparative example.

[0017]

[Table 2]

[0018]

[Table 3]

[0019]

[Table 4]

[0020]

As described above, according to the present invention, a high magnetic flux density unidirectional magnetic steel sheet having excellent magnetic properties can be manufactured, and its industrial effect is very large.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the work roll diameter / hot rolled sheet thickness of pre-cold rolling and the magnetic flux density B ₈ of a product.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C21D 8/12 C21D 9/46 501 C22C 38/00-38/60 H01F 1/16-1/18

Claims (1)

(57) [Claims] 1. C: 0.015 to 0.100 by weight%
%, Si: 2.0 to 4.0%, Mn: 0.03 to 0.1
2%, Sol. Al: 0.010-0.065%, N:
0.0040 to 0.0100%, one or two selected from S and Se: 0.005 to 0.050
%, Sb, Sn, Cu, Mo, Ge, B, Te, A
one or more selected from s and Bi are 0.0
A continuous cast slab containing 0.3 to 0.3%, with the balance being substantially Fe, is subjected to slab heating, hot rolled, pre-cold rolled, precipitation annealed, and reduced by 81 to 95%. In the method of producing a high magnetic flux density unidirectional electrical steel sheet by final strong cold rolling at a final sheet thickness of 0.25 mm or less, decarburization, primary recrystallization annealing, final finish annealing, and coating application, A method for producing a high magnetic flux density unidirectional magnetic steel sheet, which is performed at a reduction ratio of 20 to 50% using a cold rolling machine having a work roll diameter / hot rolled sheet thickness of ≧ 60.