JPH10212558A - High strength nonoriented silicon steel sheet excellent in magnetic property and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the strength of a nonoriented silicon steel sheet without deteriorating its magnetic properties, particularly, its magnetic flux density. SOLUTION: This high strength nonoriented silicon steel sheet excellent in magnetic properties is the one having a compsn. contg. <=0.01% C, <=1.0% Si, <=1.0% Mn, <=0.01% S, <=1.0% Sol.Al, 0.005 to 0.1% P, 0.002 to 0.1% Zr, and the balance Fe with inevitable impurities. The slab having this components is heated to <=1,300 deg.C and is subjected to hot rolling, and the obtd. hot rolled steel sheet is subjected to cold rolling and is thereafter subjected to continuous finish annealing, by which the high strength nonoriented silicon steel sheet excellent in magnetic properties 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 high-strength non-oriented electrical steel sheet having excellent magnetic properties and used for electric motors and transformers, and a method for producing the same.

[0002]

2. Description of the Related Art Non-oriented electrical steel sheets are used for rotor cores of electric motors and cores of transformers. In recent years, with the progress of inverters, high-speed electric motors having a rotation speed exceeding 3600 rpm have been put into practical use. And the performance of the motor deteriorates due to the deformation of the rotor caused by centrifugal force. Generally, the gap between the rotor and the stator of the motor (air gap) greatly affects the performance of the motor. However, if the strength of the rotor is low, it is deformed by centrifugal force, and the gap between the rotor and the stator changes. Deteriorates. In order to prevent deformation of the rotor of the electric motor, it is necessary to increase the strength of the rotor, but it is known that in general high-strength materials, the magnetic properties are deteriorated due to the influence of texture and inclusions. I have.

As a method of increasing the strength of a non-oriented electrical steel sheet, Ni: 7 to 23%, Ti: 0.3 to 2.0%, the balance being Fe and a small amount of deoxidizing and desulfurizing elements, unavoidable Soft iron magnetic material composed of impurities (JP-A-53-10322), C + N: 0.01% or less, Si + Al: 2-5
%, Ni: more than 1% and 8% or less, Ni + Mn: 1 to 8%, S
A high tensile strength electrical steel sheet containing i + Al + Ni + Mn: 10% or less, P: 0.1% or less, and having a steel composition consisting of the balance of Fe and unavoidable impurities. High tensile strength steel sheet having columnar crystal grains grown inward and having <100> axes densely integrated in the above direction, C + N: 0.01% or less, Si
+ Al: 2 to 5%, Ni: more than 1% and 8% or less, Ni + M
n: 1 to 8%, Si + Al + Ni + Mn: 10% or less,
P: A cold-rolled steel sheet containing 0.1% or less, the balance being Fe and unavoidable impurities, is radiated from the surface layer in an amount of 5 to 2% at a temperature at which it becomes a substantially α-ferrite single phase after decarburization.
50μm area is decarburized, and then the whole steel sheet is C + N ≦
Method of decarburizing annealing to 0.01% (JP-A-3-2817)
No. 58) has been proposed.

[0004] Further, C: 0.06% or less, Si: 1 to
3.5%, P: less than 0.03%, Zr: 0.005 to
0.5% or less: C: 0.06% or less, Si: 1
-3.5%, P: less than 0.03%, Zr: 0.005-
A method comprising hot rolling and cold rolling a steel containing 0.5%, Al: 0.1 to 1%, the balance being Fe and unavoidable impurities, and then performing a final dulling in a ferrite region (Japanese Patent Laid-Open No. Sho 5).
8-25426) has been proposed.

[0005]

SUMMARY OF THE INVENTION The above-mentioned JP-A-53-10
In the soft iron magnetic material disclosed in Japanese Patent Publication No. 322, Ni is not only expensive, but also deteriorates in magnetic properties and has a problem in use. Further, the method disclosed in JP-A-3-281758 is difficult to control for obtaining a high texture, and is not practical.

Further, the method disclosed in Japanese Patent Application Laid-Open No. 58-25426 is to add Zr for improving magnetic properties, and is a region containing a large amount of Si of 1 to 3.5%. Although the strength is increased by Si, addition of Si causes deterioration of the magnetic flux density, and is not an object of a high-strength non-oriented electrical steel sheet having excellent magnetic properties.

[0007] An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to reduce the magnetic characteristics, particularly the magnetic flux density, without deteriorating the magnetic properties.
It is an object of the present invention to provide a high-strength non-oriented electrical steel sheet having high strength and excellent magnetic properties, and a method for manufacturing the same.

[0008]

Means for Solving the Problems The present inventors have intensively studied and studied to achieve the above object. As a result, in order to increase the strength without deteriorating the magnetic properties, particularly the magnetic flux density, it is conceivable to add Ti, Zr or the like. However, Ti or the like is a carbonitride forming element, Not only causes significant deterioration of magnetic properties, but also excessive addition causes precipitation of intermetallic compounds, further deteriorating magnetic properties. on the other hand,
From the viewpoint of strength, precipitation strengthening occurs as the carbonitride or intermetallic compound is finely dispersed, and strengthening with a solid solution element is also possible. It has been found that when Zr is added to a certain amount or less, solid solution strengthening by Zr can be achieved without generating carbonitrides or precipitates, and the present invention has been achieved.

The high-strength non-oriented electrical steel sheet having excellent magnetic properties according to claim 1 of the present invention comprises: C: 0.01% or less;
1.0% or less, Mn: 1.0% or less, S: 0.01% or less, Sol. Al: 1.0% or less, P: 0.005% or more and 0.1% or less, Zr: 0.002% or more and 0.1% or less, with the balance being Fe and unavoidable impurities.
As described above, when a large amount is added, S which causes deterioration of magnetic characteristics
By limiting the addition amounts of i and Zr as described above, it is possible to increase the strength without deteriorating the magnetic properties, particularly the magnetic flux density.

The method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties according to claim 2 of the present invention is as follows: C: 0.01% or less, Si: 1.0% or less, Mn: 1.0% or less. , S:
0.01% or less, Sol. Al: 1.0% or less, P:
A slab containing 0.005% or more and 0.1% or less, Zr: 0.002% or more and 0.1% or less, and the balance consisting of Fe and unavoidable impurities is heated to a temperature of 1300 ° C. or less, After performing rolling and performing cold rolling of the obtained hot-rolled steel sheet, continuous finish annealing is performed. As described above, by limiting the amounts of Si and Zr that cause deterioration of magnetic properties when added in a large amount as described above, it is possible to increase the strength without deteriorating the magnetic properties, particularly the magnetic flux density. Further, a slab of the above chemical component was
By performing hot rolling by heating to a temperature of 00 ° C. or less, rollability can be ensured without inducing dissolution of MnS in steel. Furthermore, by performing continuous finish annealing after cold rolling, workability and magnetic properties are improved, and high strength can be achieved without deteriorating magnetic properties, particularly, magnetic flux density.

According to a third aspect of the present invention, in the method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties, after hot rolling, annealing at 600 ° C. to 1000 ° C. is performed. . As described above, by performing the hot-rolled sheet annealing at 600 ° C. to 1000 ° C., the crystal grains are coarsened and the magnetic properties can be improved, and the magnetic properties, particularly the magnetic flux density, can be increased without deteriorating the strength. Can be achieved.

In the method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties according to a fourth aspect of the present invention, the cold-rolled hot-rolled steel sheet is subjected to one or two or more intermediate annealings. By sandwiching the intermediate annealing in this manner, excessive coarsening of crystal grains can be prevented, and troubles such as breakage of the rolled material during cold rolling can be prevented.

According to a fifth aspect of the present invention, there is provided a method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties, comprising the steps of: subjecting a cold-rolled steel sheet according to the second to fourth aspects to continuous finish annealing; Is to be applied to the surface of the composite. As described above, after the continuous finish annealing, by applying a surface coating made of an organic or an organic-inorganic composite, magnetic properties suitable for applications where emphasis is placed on punching properties, in particular, high magnetic flux density and high strength A grain-oriented electrical steel sheet can be manufactured.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the chemical components of steel in the present invention are as follows. C is 0.01%
If the content exceeds 0.1%, magnetic aging is caused and the magnetic properties are deteriorated.

[0015] Si is an essential element for improving the magnetic properties, but if it exceeds 1.0%, the magnetic flux density is reduced.
1.0% or less.

Mn is an important element for improving the magnetic properties, but if it is contained in excess of 1.0%, the ductility is deteriorated and cold rolling becomes difficult.

If S exceeds 0.01%, the magnetic properties deteriorate, so S is set to 0.01% or less.
0.005% or less.

Sol. Al is an important element for improving the magnetic properties, but if it exceeds 1.0%, the magnetic flux density is reduced.

P is an important element for improving the mechanical properties, especially the punching property, but if it is less than 0.005%, the cost of the dephosphorization treatment increases, and more than 0.1%. , The ductility deteriorates, and troubles such as breakage of the rolled material occur during cold rolling.

Zr is an element effective for increasing the strength and is an essential element of the present invention. However, if it is less than 0.002%, there is no effect of increasing the strength, and if it exceeds 0.1%, the magnetic properties are not improved. Since it causes deterioration, the content is made 0.002% or more and 0.1% or less.

The slab of the above chemical component is heated to a temperature of 1300 ° C. or lower and subjected to ordinary hot rolling. If the heating temperature of the slab exceeds 1300 ° C., precipitates such as MnS in the steel are re-dissolved, which leads to deterioration of magnetic properties.
The temperature was set to 300 ° C. or less. However, in order to ensure the rollability in hot rolling, the temperature is preferably in the range of 1100 to 1250 ° C.

The hot-rolled hot-rolled steel sheet is pickled and then annealed at a temperature of 600 ° C. or more and 1100 ° C. or cold-rolled as it is, or once or twice. Cold rolling is performed with the intermediate annealing at least twice, and finish annealing is performed by continuous annealing. The annealing temperature of hot rolled steel sheet is 60
If the temperature is lower than 0 ° C., there is no effect of improving the magnetic properties. If the temperature is higher than 1100 ° C., the crystal grains become excessively coarse and troubles such as breakage of the rolled material occur during cold rolling.
And

The intermediate annealing temperature in cold rolling is 600
If the temperature is lower than 1000C, there is no effect. If the temperature is higher than 1000C, the crystal grains become excessively coarse and cause troubles such as breakage of the rolled material. Also, workability,
The final annealing temperature by continuous annealing to improve magnetic properties is
If the temperature is lower than 700 ° C., a sufficient recrystallized structure cannot be obtained, resulting in poor magnetic properties. If the temperature exceeds 1100 ° C., grain boundary oxidation occurs from the surface layer, and conversely, the magnetic properties deteriorate. It is.

The finish-annealed cold-rolled steel strip is coated on both sides with a surface coating made of an organic material or a mixture of an organic material and an inorganic material for applications where emphasis is placed on punching properties. The surface coating is not particularly limited as long as it is not affected by insulating varnish, transformer oil, machine oil, etc., but is not particularly limited, but is spray-coated with a resin or a mixture of a resin and an inorganic binder, etc., by a roll coater, curtain flow coat, etc. A film is formed on both sides of the belt.

[0025]

EXAMPLE A slab having a thickness of 227 mm and a width of 1000 mm of the steels of the present invention of steel types A to D and the comparative steels of steel types EG shown in Table 1 was subjected to hot rolling under the hot rolling conditions shown in Table 2. After forming a hot-rolled coil having a thickness of 2.3 mm, the hot-rolled sheet was annealed or pickled without annealing under the conditions shown in Table 2, and then cold-rolled under the conditions shown in Table 2 to obtain a sheet thickness of 0.50 mm. After recrystallization annealing by continuous annealing at the finish annealing temperature shown in Table 2, a 0.4 μm-thick film of acrylic resin emulsion, magnesium chromate, and boric acid was formed on both sides of the cold-rolled steel strip. An insulating film was formed by a roll coater method. A test piece was collected from each of the obtained magnetic steel sheets, and the magnetic properties (iron loss W, magnetic flux density B) were evaluated using a 25 cm Epstein tester according to the JIS C2550 electromagnetic steel test method, and JIS Z
Using a No. 5 test piece specified as the metal material tensile test piece 2201, a metal material tensile test specified in JIS Z2241 was performed to measure the tensile strength. Table 3 shows the results.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

As shown in Tables 1 to 3, all of the steel types A to D of the present invention have both iron loss and magnetic flux density according to JIS C25.
Type 50A4 specified by 52 non-directional electromagnetic steel strips
The requirements of 70 to 50A800 are satisfied. On the other hand, in the comparative example of steel type E, both iron loss and magnetic flux density were JIS C
Type 50 specified by 2552 non-oriented electrical steel strip
Although it satisfies the requirements of A470 to A800, the tensile strength is greatly reduced to 365 N / mm ² . Also,
In the comparative examples of steel types F and G, defective magnetic properties in which iron loss was significantly increased compared to the examples of the present invention were recognized.

[0030]

The high-strength non-oriented electrical steel sheet having excellent magnetic properties according to claim 1 of the present invention has C: 0.01% or less and Si:
1.0% or less, Mn: 1.0% or less, S: 0.01% or less, Sol. Al: 1.0% or less, P: 0.005% or more and 0.1% or less, Zr: 0.002% or more and 0.1% or less, the balance being Fe and unavoidable impurities,
By limiting the amounts of Si and Zr that cause the deterioration of magnetic properties when added in a large amount as described above, it is possible to increase the strength without deteriorating the magnetic properties, particularly the magnetic flux density.

Further, in the method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties according to claim 2 of the present invention, the amounts of Si and Zr that cause deterioration of the magnetic properties when added in large amounts are limited as described above. Thereby, high strength can be achieved without deteriorating the magnetic characteristics, particularly the magnetic flux density. By subjecting the slab of the chemical component to hot rolling at a temperature of 1300 ° C. or lower, rollability can be ensured without inducing dissolution of MnS in the steel. Furthermore, by performing continuous finish annealing after cold rolling, workability and magnetic properties are improved, and high strength can be achieved without deteriorating magnetic properties, particularly, magnetic flux density.

Further, the method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties according to claim 3 of the present invention is characterized in that:
By performing the hot-rolled sheet annealing at 1000 ° C., the crystal grains are coarsened, and the magnetic characteristics can be improved.
Troubles such as breakage during cold rolling due to excessive coarsening of crystal grains can be prevented, and high strength can be achieved without deteriorating magnetic properties, particularly magnetic flux density.

Further, in the method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties according to claim 4 of the present invention, the method comprises the steps of: Is prevented from being excessively coarsened, troubles such as breakage of the rolled material at the time of cold rolling can be prevented, and high strength can be achieved without deteriorating magnetic properties, particularly, magnetic flux density.

According to a fifth aspect of the present invention, there is provided a method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties, comprising the steps of: subjecting a cold-rolled steel sheet according to any of the second to fourth aspects to continuous finish annealing; By applying a surface coating composed of the composite of the above, the punching property can be improved and the life of the mold can be extended.

Claims (5)

[Claims] 1. C: 0.01% or less, Si: 1.0% or less, Mn: 1.0% or less, S: 0.01% or less, So
l. Al: 1.0% or less, P: 0.005% or more and 0.1
%, Zr: 0.002% or more and 0.1% or less, with the balance being Fe and unavoidable impurities. 2. C: 0.01% or less, Si: 1.0% or less, Mn: 1.0% or less, S: 0.01% or less, So
l. Al: 1.0% or less, P: 0.005% or more and 0.1
% Or less, Zr: 0.002% or more and 0.1% or less, and the rest is heated to a temperature of 1300 ° C. or less by hot rolling a slab composed of Fe and unavoidable impurities,
A method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties, comprising performing cold rolling of the obtained hot-rolled steel sheet and then performing continuous finish annealing. 3. The method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties according to claim 2, wherein the hot-rolled steel sheet is annealed at 600 ° C. to 1000 ° C. 4. The cold rolling of a hot-rolled steel sheet includes one or more intermediate annealings.
A method for producing a high-strength non-oriented electrical steel sheet having excellent magnetic properties as described. 5. The non-directional sheet having excellent dimensional accuracy after punching according to claim 2, wherein a surface coating comprising an organic or an organic-inorganic composite is applied after continuous finish annealing. Manufacturing method of electrical steel sheet.