JPH1112703A - Nonoriented silicon steel sheet excellent in magnetic property, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonoriented silicon steel sheet commonly usable for a fullprocessed and a semiprocessed nonoriented steel sheet. SOLUTION: This nonoriented silicon steel sheet has a composition consisting of <=0.01% C, <=1.5% Si, <=1.0% Mn, <=0.01% S, <=0.02% sol.Al, 0.005-0.1% P, <=0.002% N, and the balance Fe with inevitable impurities and satisfying Al(%)×N(%)<1×10<-5> . In this case, by regulating the contents of sol.Al and N to <=0.02% and <=0.002%, respectively, and making the relation of Al(%)×N(%)<1×10<-5> be satisfied, the form of precipitation of AlN is changed and the precipitation of harmful AlN is inhibited and deterioration in magnetic properties can be prevented. Further, the necessity of skin pass rolling after finish annealing can be obviated, and this nonoriented silicon steel sheet can be commonly used for a fullprocessed and a semiprocessed nonoriented steel sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet having excellent magnetic properties and used for electric motors and transformers, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Non-oriented electrical steel sheets are used for stators of electric motors,
Used for rotors, stators for hydroelectric generators, core materials for transformers, etc.In recent years, motors used in refrigerators, air conditioners, etc. have been made more efficient due to both environmental and energy issues. As a result, the iron loss of magnetic steel sheets, which are iron core materials, has been reduced. Conventionally, it has been considered that the lower the impurity elements such as C, N and S, the lower the iron loss of the magnetic steel sheet.

[0003] As a method of reducing the iron loss of an electromagnetic steel sheet by reducing N, C: 0.005% or less, Si: 2.5 to 4.0.
%, Mn: 0.1 to 1.0%, among inevitable impurities, S: 15 ppm or less, O: 20 ppm or less,
A method in which a slab having N: 25 ppm or less is hot-rolled, then cold-rolled once or twice with intermediate annealing, and then subjected to continuous finish annealing at a temperature rising rate of 300 ° C./min or more (Japanese Patent Application Laid-Open JP-A-59-74223), C: 0.00
5% or less, Si: 2.5 to 4.0%, Al: 0.25 to
1.00%, Mn: 0.1 to 1.0%, among inevitable impurities, S: 15 ppm or less, O: 20 ppm
Hereinafter, the slab having N: 25 ppm or less is hot-rolled, subjected to hot-rolled sheet annealing at 900 to 1050 ° C for 2 to 15 minutes, and then cold-rolled at a rolling reduction of 65% or more, and continuously finished. Annealing method (JP-A-59-74224), C: 0.005% or less, Si: 2.5 to 4.0
%, Al: 0.25-1.00%, Mn: 0.1-1.
0%, S: 15 ppm of unavoidable impurities
Hereinafter, a slab having O: 20 ppm or less and N: 25 ppm or less is hot-rolled, and 950 to 1050 ° C., 2 to 15
2nd reduction rate of 70% or more with intermediate annealing for 2 minutes
Cold rolling and continuous finish annealing
9-74225), C: 0.005% or less, S
i: 2.5 to 4.0%, Al: 0.25 to 1.00%,
Mn: 0.1-1.0%, among inevitable impurities, S: 15 ppm or less, O: 20 ppm or less, N: 2
5 ppm or less and Ti + Zr + Ce + Ca ≦
An electromagnetic steel sheet having a concentration of 150 ppm (JP-A-59-74257)
Publication), C: 0.005% or less, Si: 2.5-4.
0%, Al: 0.25 to 1.00%, Mn: 0.1 to
1.0%, and among inevitable impurities, S: 15p
pm or less, O: 20 ppm or less, N: 25 ppm or less, and the average crystal grain size D expressed in relation to the Si and Al contents is 100 + 3.5 × [Si% + Al%] ²
≦ D ≦ 170 + 5.0 × [Si% + Al%] Electrical steel sheet showing a value in the range of ² (Japanese Patent Laid-Open No. 59-74258).
Has been proposed. N actually mentioned in the embodiment is 11
-25 ppm.

On the other hand, Sol. As a method for reducing iron loss by reducing Al, for example, Sol. 0.002 Al
Method of improving magnetic properties after semi-process annealing by specific hot rolling conditions and skin pass rolling after finish annealing (Japanese Patent Application Laid-Open No. 58-171527), vacuum degassing of molten steel And C in steel: 0.015
% Or less, O: after reducing to 0.02% or less, aluminum is not used for deoxidation, only Si is used, and Si in steel:
A method of reducing the content of Al to 0.1 to 1.0% and Al: 0.007% or less (JP-A-53-109815) has been proposed.

The above-mentioned JP-A-59-74223, JP-A-59-74224, JP-A-59-74225, JP-A-59-74257 and JP-A-5-74257
N in steel actually mentioned in the examples in JP-A-9-74258 is a region in which 11 to 25 ppm is reduced, and N in a region of 10 ppm or less is not found. Also, JP-A-58-171527, JP-A-5-171527
In the method disclosed in Japanese Patent Application Laid-Open No. 3-109815, since skin pass rolling is performed after finish annealing, predetermined magnetic characteristics cannot be obtained unless semi-process annealing is performed.

In recent years, in the motor manufacturing industry, materials have been standardized to reduce costs. For example, semi-process annealing is performed on the core of a hermetic motor for a compressor of an air conditioner. Although it is necessary to cut out the core of the motor and not perform annealing in use in the full process, it is necessary to satisfy any of the characteristics. However, in the above-described conventional technology, both the semi-process and the full process could not be satisfied.

As a method for solving the above problem, there has been proposed a method for improving magnetic properties without performing skin pass rolling after finish annealing. For example, a method of controlling V mixed as an impurity (Japanese Unexamined Patent Publication No. 3-20413)
Has been proposed.

[0008]

SUMMARY OF THE INVENTION The above-mentioned JP-A-3-204
The method disclosed in Japanese Patent Publication No. 13 has a drawback that, in order to control V mixed as an impurity, it is necessary to examine the steelmaking raw material, which leads to an increase in raw material cost.

On the other hand, recent advances in steelmaking technology have made possible the commercial production of high-purity clean steel, which was impossible at all in the past, and made it possible to produce impurity elements such as C, N and S at 10 ppm or less. It is possible.

[0010] An object of the present invention is to solve the above-mentioned disadvantages of the prior art, and to solve Sol. It is an object of the present invention to provide a non-oriented electrical steel sheet having excellent magnetic properties that can be used for both a semi-process and a full process without deterioration of magnetic properties due to fine AlN precipitation even when Al is about 100 ppm, and a method of manufacturing the same. is there.

[0011]

Means for Solving the Problems The present inventors have intensively studied and studied to achieve the above object. As a result, Sol. It has been known that when Al exceeds 20 ppm, the magnetic properties are deteriorated, and when the content is about 100 ppm, fine AlN is precipitated to cause remarkable deterioration of the magnetic properties. By reducing N in steel to 10 ppm or less until Al is about 200 ppm, the precipitation form of AlN changes and magnetic characteristics can be prevented from deteriorating, skin pass rolling after finish annealing is eliminated, and semi-process and full process are performed. They have found that they can be shared by both processes and arrived at the present invention.

According to the first aspect of the present invention, the non-oriented electrical steel sheet having excellent magnetic properties comprises: C: 0.01% or less, Si: 1.5%
Mn: 1.0% or less, S: 0.01% or less, So
l. Al: 0.02% or less, P: 0.005% or more.
1% or less, N: 0.002% or less, and Al
(%) × N (%) <1 × 10 ⁻⁵ , the balance being Fe and unavoidable impurities. Thus, C: 0.0
1% or less, Si: 1.5% or less, Mn: 1.0% or less,
S: 0.01% or less, Sol. Al: 0.02% or less,
P: 0.005% to 0.1%, N: 0.002%
Contains the following and Al (%) × N (%) <1 × 10
^In the magnetic steel sheet satisfying ^-5 , the precipitation form of AlN that causes the deterioration of the magnetic characteristics changes, and the deterioration of the magnetic characteristics can be prevented.

The method for producing a 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;
i: 1.5% or less, Mn: 1.0% or less, S: 0.01
% Or less, Sol. Al: 0.02% or less, P: 0.00
A slab containing 5% or more and 0.1% or less, N: 0.002% or less, and satisfying Al (%) × N (%) <1 × 10 ⁻⁵ and the balance being Fe and unavoidable impurities. Is subjected to hot rolling by heating to a temperature of 1300 ° C. or less,
After cold rolling of the obtained hot-rolled steel sheet, 700 ° C.
Continuous finish annealing is performed at 1050 ° C. By heating the slab of the above chemical component to a temperature of 1300 ° C. or lower and performing hot rolling, it is possible to secure magnetic properties without inducing dissolution of MnS in steel. Also,
After cold rolling, continuous finish annealing at 700 ° C. to 1050 ° C. improves workability and magnetic properties.

According to a third aspect of the present invention, there is provided a method for producing a non-oriented electrical steel sheet having excellent magnetic properties, comprising the steps of:
The hot-rolled sheet annealing is performed at 00 ° C to 1000 ° C. 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.

According to a fourth aspect of the present invention, there is provided a method for producing a non-oriented electrical steel sheet having excellent magnetic properties, wherein the hot-rolled steel sheet is subjected to one or two or more intermediate annealings in cold rolling. 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 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; A surface coating consisting of an object is to be applied.
As described above, after performing the continuous finish annealing, by applying a surface coating made of an organic or an organic-inorganic composite, a non-oriented electrical steel sheet suitable for applications where emphasis is placed on punchability can be produced.

[0017]

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.

[0018] Si is an essential element for improving magnetic properties, but if contained in excess of 1.5%, improvement of magnetic properties by semi-process annealing at 750 ° C for 2 hours in a nitrogen gas atmosphere is expected. Since it cannot be satisfied, the content is set to 1.5% or less.

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

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

Sol. Al is an important element for improving the magnetic properties, but if it exceeds 0.02%, the crystal grains are refined and the magnetic properties are degraded. Therefore, the content of Al is set to 0.02% or less.

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.

N is an element harmful to magnetic properties.
If it exceeds 002%, it bonds with Al to form AlN, and the crystal grains are refined to cause deterioration of magnetic properties.
Although it was set to 2% or less, it is preferably 0.001% or less.

Normally, the precipitation of AlN is determined by the solubility product of AlN, but when the solubility product is exceeded, harmful AlN precipitates and the magnetic properties deteriorate. However, AlN that is harmful to magnetic properties is not all of the precipitated AlN, so that the solubility product becomes smaller than the solubility product [Al (%) × N (%) = 1 × 10 ⁻⁵ ]. Al: 0.02% or less, N: 0.002%
Even below, as shown in FIG. 1, Al (%) × N
If (%) <1 × 10 ⁻⁵ is not satisfied, good iron loss (full process iron loss value−semi-process iron loss value) / full process iron loss value ≧ 0.2 cannot be obtained.

The slab of the above-mentioned chemical composition is heated to a temperature of 1300 ° C. or lower and subjected to ordinary hot rolling. When the heating temperature of the slab exceeds 1300 ° C., precipitates such as MnS in the steel are re-dissolved, leading 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 hot rolled. Cold rolling is performed with one or two or more intermediate annealings, and finish annealing is performed by continuous annealing. If the annealing temperature of the hot rolled steel sheet is less than 600 ° C., there is no effect of improving the magnetic properties, and
If the temperature exceeds 100 ° C., the crystal grains become excessively coarse and troubles such as breakage of the rolled material occur during cold rolling.
It was 1100 ° C.

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 troubles such as breakage of the rolled material occur. The final annealing temperature by continuous annealing for improving workability and magnetic properties is 7
If the temperature is lower than 00 ° C., a sufficient recrystallized structure cannot be obtained due to the addition of Ti and V, resulting in poor magnetic properties. If the temperature exceeds 1100 ° C., the crystal becomes extremely coarse and the workability deteriorates, and α-γ
Transformation occurs and the magnetic properties and the flatness of the steel sheet deteriorate.
It should be between 00 ° C and 1100 ° C.

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, and the like, but is not particularly limited, and may be made of a resin or a mixture of a resin and an inorganic binder by spray coating, roll coating, curtain flow coating, or the like. A film is formed on both sides of the belt.

[0029]

【Example】

Example 1 Steel of the present invention of steel types 1 to 9 and steel types 10 to 13 shown in Table 1
Each slab having a thickness of 227 mm and a width of 1000 mm was subjected to hot rolling under the hot rolling conditions shown in Table 2 to 2.3.
After hot-rolled coil having a thickness of 0.5 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 cold-rolled sheet having a thickness of 0.50 mm. Finished into rolled coil. Thereafter, the cold-rolled coil was subjected to recrystallization annealing by continuous annealing at the finish annealing temperature shown in Table 2, and then an insulating film having a thickness of 0.4 μm made of an acrylic resin emulsion, magnesium chromate, and boric acid was formed on both sides of the cold-rolled steel strip. It was formed by a roll coater method. A test piece was sampled from each of the obtained steel sheets, and cut as it was (full process) using a 25 cm Epstein tester according to JIS C2550, in accordance with the electromagnetic steel sheet test method specified in JIS C2550, and a test piece in a nitrogen gas atmosphere.
The magnetic properties (iron loss W, magnetic flux density B) after strain relief annealing at 0 ° C. for 2 hours (semi-process) were evaluated. Table 3 shows the results.
Shown in

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

[Table 3]

As shown in Tables 1 to 3, all of the examples of the present invention of steel types 1 to 9 have JIS C25 in both iron loss and magnetic flux density.
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 10, both iron loss and magnetic flux density were JIS.
Type 5 specified by C2552 non-oriented electrical steel strip
0A470 to 50A800 is satisfied, but iron loss after semi-process annealing is too large. In addition, steel type 1
Comparative examples 1 and 12 show that both iron loss and magnetic flux density are JISC25.
Type 50A4 specified by 52 non-directional electromagnetic steel strips
The requirements of 70 to 50A800 are not satisfied. further,
The comparative example of steel type 13 shows that both iron loss and magnetic flux density are JIS C2.
Type 50A specified by 552 non-directional electromagnetic steel strip
It meets the requirements of 470-50A800, but the iron loss after semi-process annealing is too large.

Example 2 Sol. Al is changed in the range of 0.001 to 0.03%, N is changed in the range of 0.0001 to 0.0055%, and the content of other elements is C: 0.003%, Si: 0.3%. , M
n: 0.3%, S: 0.005%, P: 0.07%, and each slab having a constant thickness of 227 mm and a width of 1000 mm
Heated to 150 ° C and subjected to normal hot rolling to a thickness of 2.3m
m hot-rolled coil, and after normal pickling, cold-rolled to obtain a cold-rolled coil having a thickness of 0.5 mm. Then 8
After recrystallization annealing by continuous annealing at 50 ° C., a 0.4 μm-thick insulating film made of an acrylic resin emulsion, magnesium chromate, and boric acid was formed on both surfaces of the cold-rolled steel strip by a roll coater method. A test piece was sampled from each of the obtained steel sheets, and cut as it was (full process) using a 25 cm Epstein tester according to JIS C2550, in accordance with the method for testing electromagnetic steel sheets, and at 750 ° C. for 2 hours in a nitrogen gas atmosphere. (Semi-process iron loss value) / Full-process iron loss value is calculated by calculating (Full-process iron loss value-Semi-process iron loss value) / (Full-process iron loss value-Semi-process iron) Loss value) / Full process iron loss value ≧
0.2 is regarded as good iron loss and (full process iron loss value−semi-process iron loss value) / full process iron loss value <0.2 is regarded as poor iron loss, and N, Sol. The relationship between Al and iron loss good / bad was determined. The result is shown in FIG.

As shown by a circle in FIG. 1, Sol.
Even if Al is 0.015%, N in steel is 0.000%.
If it is 6%, the iron loss of the electromagnetic steel sheet is good, and the N
0.002% or less, Sol. By making Al not more than 0.02% and satisfying Al (%) × N (%) <1 × 10 ⁻⁵ , good iron loss (full process iron loss value−semi-process iron loss value) / full The process iron loss value can be maintained at ≧ 0.2.

[0036]

The non-oriented electrical steel sheet having excellent magnetic properties according to claim 1 of the present invention has a C content of 0.01% or less and a Si content of 1.5%.
%, Mn: 1.0% or less, S: 0.01% or less, S
ol. Al: 0.02% or less, P: 0.005% or more and 0.1% or less, N: 0.002% or less, and A
1 (%) × N (%) <1 × 10 ⁻⁵ , and the remainder is F
e and unavoidable impurities, which are harmful to magnetic properties.
Is set to 0.002% or less, and S
ol. Al is set to 0.02% or less, and Al (%) × N
By satisfying (%) <1 × 10 ⁻⁵ , the precipitation form of AlN that causes the deterioration of the magnetic characteristics changes, and the deterioration of the magnetic characteristics can be prevented.

Further, the method for producing a non-oriented electrical steel sheet having excellent magnetic properties according to claim 2 of the present invention is characterized in that N
Is set to 0.002% or less, and S
ol. Al is set to 0.02% or less, and Al (%) × N
By satisfying (%) <1 × 10 ⁻⁵ , the precipitation form of AlN that causes the deterioration of the magnetic characteristics changes, and the deterioration of the magnetic characteristics can be prevented. 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. Further, by performing the continuous finishing annealing after the cold rolling, the workability and the magnetic properties can be satisfied in both the full process and the semi-process.

Further, the method for producing a non-oriented electrical steel sheet having excellent magnetic properties according to claim 3 of the present invention is as follows.
By performing hot-rolled sheet annealing at 0 ° C., crystal grains can be coarsened to improve magnetic properties, and troubles such as breakage during cold rolling due to excessive coarsening of crystal grains can be prevented. Can be.

Further, the method for producing a non-oriented electrical steel sheet having excellent magnetic properties according to claim 4 of the present invention is characterized in that
By sandwiching the intermediate annealing twice or more times, 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 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; By applying a surface coating made of a material, the punching property can be improved and the life of the mold can be extended.

[Brief description of the drawings]

FIG. 1 shows N and Al contents and Al in steel in Example 2.
It is a graph which shows the relationship between (%) * N (%) = 1 * 10 < ^-5 > curve and iron loss good and bad.

Claims (5)

[Claims] 1. C: 0.01% or less, Si: 1.5% or less, Mn: 1.0% or less, S: 0.01% or less, So
l. Al: 0.02% or less, P: 0.005% or more.
1% or less, N: 0.002% or less, and Al
A non-oriented electrical steel sheet having excellent magnetic properties, satisfying (%) × N (%) <1 × 10 ⁻⁵ and the balance being Fe and inevitable impurities. 2. C: 0.01% or less, Si: 1.5% or less, Mn: 1.0% or less, S: 0.01% or less, So
l. Al: 0.02% or less, P: 0.005% or more.
1% or less, N: 0.002% or less, and Al
(%) × N (%) <1 × 10 ⁻⁵ , and the remainder is made of slabs composed of Fe and unavoidable impurities, heated to a temperature of 1300 ° C. or less, and hot-rolled. , And then performing a continuous finish annealing at 700 ° C. to 1050 ° C., thereby producing a non-oriented electrical steel sheet having excellent magnetic properties. 3. A hot-rolled steel sheet before cold rolling is subjected to a temperature of 600 ° C. to 10 ° C.
The method for producing a non-oriented electrical steel sheet having excellent magnetic properties according to claim 2, wherein the hot-rolled sheet is annealed at 00 ° C. 4. The cold rolling of a hot-rolled steel sheet includes one or more intermediate annealings.
A method for producing a non-oriented electrical steel sheet having excellent magnetic properties as described. 5. The non-oriented electrical steel sheet having excellent magnetic properties according to claim 2, wherein a surface coating comprising an organic or an organic-inorganic composite is applied after continuous finish annealing. Production method.