KR100701196B1 - Non-oriented electricalsteel sheet with improved magnetic property and Method for manufacturing the same - Google Patents

Abstract

A non-oriented electrical steel sheet with superior magnetic property which lowers energy loss and improves flux density by properly designing contents of Si, Al, Mn and P while reducing contents of impurity components such as C, S, N and O as low as possible, and a method for manufacturing the same are provided. A non-oriented electrical steel sheet with superior magnetic property comprises 0.005 wt.% or less of C, 1.5 wt.% or less of Si, 0.1 to 1.5 wt.% of Mn, 0.005 wt.% or less of S, 0.003 wt.% or less of N, and the balance of Fe and other inevitable impurities, wherein Al(%)>Si(%), Al(%)/20<=P<=Al(%)/8. A method for manufacturing a non-oriented electrical steel sheet with superior magnetic property comprises: reheating a slab at a temperature of 1200 to 1250 deg.C, wherein the slab comprises 0.005 wt.% or less of C, 1.5 wt.% or less of Si, 0.1 to 1.5 wt.% of Mn, 0.005 wt.% or less of S, 0.003 wt.% or less of N, and the balance of Fe and other inevitable impurities, wherein Al(%)>Si(%), Al(%)/20<=P<=Al(%)/8; and hot rolling the reheated slab, wherein the hot rolling is finished in a ferrite phase at a finish rolling temperature of 900 to 980 deg.C.

Description

Non-oriented electrical steel sheet with improved magnetic property and method for manufacturing the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet having excellent magnetic properties, which is widely used as an iron core material of electrical equipment, and more particularly, to a non-oriented electrical steel sheet having low iron loss and excellent magnetic density, and a manufacturing method thereof. .

In general, iron loss represents the energy loss per kilogram of iron when the required magnetic field is added, and the magnetic flux density is the number of magnetic lines as energy induced when the magnetic field is added. A magnetic field is added to obtain the magnetic flux density, and iron loss is an inevitable loss. It is important to reduce the possible losses and get the desired energy.

In the prior art, Japanese Patent Laid-Open No. 10-183311 focuses on improving workability by adding an alloy component such as Si + 0.6Al ≧ 0.8 wt%.

In addition, Japanese Patent Application Laid-Open No. 2001-49390 provides a method of improving magnetism by adding Si, Al, and Mn based on a formula, but has a disadvantage of low magnetic flux density even when performing hot-rolled sheet annealing during manufacture.

The present invention has been proposed in order to solve the above problems, while containing the impurities as small as possible, such as C, S, N, O, while properly designing the content of Si, Al, Mn and P to lower the iron loss and magnetic flux An object of the present invention is to provide a non-oriented electrical steel sheet excellent in magnetic properties capable of improving density and a method of manufacturing the same.

The present invention for achieving the above object by weight, C: 0.005% or less, Si: 1.5% or less, Mn: 0.1-1.5%, S: 0.005% or less, N: 0.003% or less, Al (% )> Si (%), Al (%) / 20≤P≤Al (%) / 8, and it is characterized by consisting of remainder Fe and other unavoidable impurities.

According to another aspect of the present invention, a method of manufacturing an excellent non-oriented electrical steel sheet having a magnetic property is weight%, C: 0.005% or less, Si: 1.5% or less, Mn: 0.1-1.5%, S: 0.005% or less, N: 0.003 When hot-rolling a slab made of Al (%)> Si (%), Al (%) / 20 ≦ P ≦ Al (%) / 8, which is less than%, balance Fe and other unavoidable impurities. The slab reheating temperature is set to 1200 to 1250 ° C, and the temperature of the finish hot rolling is finished on ferrite at 900 to 980 ° C.

Hereinafter, the present invention will be described in detail.

In the present invention, Si, Al, Mn and P were added to produce a non-oriented electrical steel sheet having a low iron loss and a high magnetic flux density.

In general, Si is a material that hardens the material and makes it difficult to roll even during cold rolling, but has a characteristic of lowering the magnetic flux density. However, simply lowering the content of Si does not lower the iron loss, so addition is inevitable.

On the other hand, Al may be added instead of Si, and in this case, there is a disadvantage in that the magnetic flux density is lowered according to the increase of Al.

However, in the present invention, P was added to solve the problem of lowering the magnetic flux density according to the increase of Al.

In general, P is added to improve punchability, but in the present invention, P is added to improve magnetic flux density of Al-containing steel.

Al-rich steels were found to have coarse precipitates, as AlN, a fine precipitate, was found together with other precipitates, resulting in large grain growth, but a low magnetic flux density.

Therefore, in the present invention, in order to compensate for this, P is added as Al (wt%) / 20 ≦ P ≦ Al (wt%) / 8 in conjunction with Al content to improve magnetic flux density.

Further more the iron loss ratio W _{15/50 /} W _10/50 of 2.0 because of the core loss is low and it is desirable to lower the magnetic flux density relative to the ratio of W _15/50 for the high non-oriented electrical steel sheet the iron loss of ₁₀ W _{/ 50} in A large value was made.

EMBODIMENT OF THE INVENTION Hereinafter, the basis of limitation about the component of this invention is demonstrated.

Si increases the resistivity and serves to lower the iron loss, and is added below 1.5%. If the 1.5% or more is added, the iron loss is lowered, but the magnetic flux density is lowered, so it is preferably 1.5% or less.

Al serves to decrease the iron loss by increasing the specific resistance, and has the characteristics that workability is improved at the same iron loss, and since Al is easily suppressed and magnetic enhancement is easy, it is preferable to add at least more than the Si content.

Mn is a component that increases the resistivity, and is added at 0.1% or more and 1.5% or less, and by adding at least 0.1% or more, it is possible to suppress the formation of fine MnS precipitates and to add at most 1.5% or less. Here, if less than the sum of the amounts of S and Al can maintain the ferrite phase in the cold rolling annealing temperature zone.

P is added to improve the magnetic flux density by improving the texture of the Al-added steel, and in proportion to Al content, it is a ratio of Al (% by weight) / 20 and a ratio of Al (% by weight) / 8. When P is contained less than Al (wt%) / 20, the magnetic flux density is lowered because more (222) planes and (211) planes, etc., cause worse magnetic flux density in the texture, and P is lower than Al (wt%) / 8. If it contains a large amount, it does not help magnetic improvement, and since hardness may be excessively high and cold rolling is difficult, it is preferable to add it in the ratio of Al (wt%) / 20 to Al (wt%) / 8.

C is required to suppress the magnetic aging of the product and to be as low as possible for grain growth, to be contained less than 0.005%. More preferably, it is 0.003% or less.

N and S are preferably as low as possible in order to suppress the production of fine AlN and MnS, which are harmful to magnetic, and N and S should be 30 ppm or less, respectively.

Other inevitably added impurity components include components such as Ti, Nb, and V that should be lowered if possible.

Hereinafter, the basis of the manufacturing conditions of this invention is demonstrated.

In the present invention, the slab is heated to a temperature of 1200 ~ 1250 ℃ during hot rolling, the finish rolling temperature during hot rolling is carried out on a ferrite of 900 ~ 980 ℃, when the slab temperature is less than 1200 ℃ temperature of the finish rolling of hot rolling It is because it is difficult to finish-roll stably on ferrite of 900-980 degreeC.

The finish rolling temperature is carried out in the ferritic phase of 900 ~ 980 ℃, when rolling on the ferritic crystal grains are largely grown because less recrystallization and recovery occurs inside the tissue during rolling. If possible, the ferrite phase may be grown at a high temperature, whereby grains grow coarsened and the hot-rolled sheet annealing can be omitted. Therefore, the finish rolling temperature of hot rolling is preferably rolled on the ferritic phase 900 ~ 980 ℃.

The hot rolled hot rolled sheet may be wound to a temperature of 600 ° C. or higher, cooled in air, or subjected to self annealing at a temperature of 700 ° C. or higher. Self-annealing refers to the annealing of the hot rolled sheet by maintaining it at a high temperature when winding up. The hot rolled sheet is cold rolled after pickling, and when the hot rolled sheet is annealed, magnetism may be improved by grain growth.

The hot rolled sheet is subjected to cold rolled sheet annealing after cold rolling. Annealing is carried out in a non-oxidizing atmosphere containing hydrogen, and the annealing temperature is carried out at a normal temperature. Surface coating is the same as general coatings such as organic, inorganic and organic-inorganic composite coatings commonly used.

Magnetic Properties of iron loss was measured at 50Hz, and measuring the loss at 1.0 Tesla and 1.5Tesla, then the iron loss ratio that is _{W 15/50 / W 10/} 50 is calculated on the. Here, the ratio was made into the value exceeding 2.0. The ratio When greater than 2.0 relative to W _10/50 are listed and a lower value therefore the core loss is low primarily and can be used as a material of gogeupjae, and the magnetic flux density is high in magnetic characteristics W _15/50 values are also lowered in There is an advantage.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

The steel slab was reheated under the same conditions as in Table 2 in the composition shown in Table 1, and the finish rolling of hot rolling was performed. After hot rolling to a thickness of 2.3 mm, it was air-cooled after winding at 700 ° C. The hot rolled steel sheet wound and cooled in air was pickled and cold rolled to a thickness of 0.5 mm. The cold rolled steel sheet was annealed in an atmosphere of 25% hydrogen and 75% nitrogen at an annealing temperature of 1000 ° C. for 1 minute. After cutting the annealing plate to investigate the magnetic properties are shown in Table 2.

Steel grade Ingredient (% by weight) P addition range (wt%) C Si Mn S Al P N Al / 20 (lower limit) Al / 8 (upper limit) Inventive Steel A 0.0015 0.92 0.82 0.0011 1.21 0.11 0.0011 0.06 0.15 Inventive Steel B 0.0016 0.92 0.50 0.0007 1.02 0.09 0.0013 0.05 0.13 Invention Steel C 0.0015 0.90 0.90 0.0010 1.29 0.12 0.0009 0.07 0.16 Inventive Steel D 0.0015 0.89 0.81 0.0012 1.03 0.10 0.0015 0.05 0.13 Comparative Steel A 0.0015 0.91 0.80 0.0010 1.20 0.02 0.0010 0.06 0.15 Comparative Steel B 0.0015 0.92 0.30 0.0006 1.22 0.18 0.0009 0.06 0.15 Comparative Steel C 0.0015 0.92 0.91 0.0011 2.10 0.30 0.0011 0.11 0.26

As shown in Table 2 below, the inventive materials (1 to 6) prepared under the manufacturing conditions of the present invention using the inventive steels (A to D) satisfying the component ranges of the present invention are prepared with the components within the scope of the invention. The magnetism is excellent depending on the conditions.

 division  Steel grade Slab reheating temperature (℃) Finish Hot Rolling Temperature (℃) Ferrite Upper Limit Temperature (℃) The iron loss _{(W 10/50) (W} / kg) The iron loss _{(W 15/50) (W} / kg) Magnetic flux density (B ₅₀ ) (Tesla) Iron loss ratio _{(W 15/50 / W 10} /50) Invention 1 Inventive Steel A 1240 920 990 1.32 2.85 1.76 2.16 Invention 2 Inventive Steel B 1240 920 981 1.40 2.98 1.75 2.13 Invention 3 Invention Steel C 1240 920 992 1.34 2.80 1.74 2.09 Invention 4 Inventive Steel D 1200 920 976 1.31 2.90 1.75 2.21 Invention 5 Inventive Steel D 1220 950 976 1.38 2.92 1.75 2.12 Invention 6 Inventive Steel D 1240 970 976 1.35 2.90 1.75 2.15 Comparative Material 1 Inventive Steel D 1240 880 976 1.43 3.05 1.72 2.13 Comparative Material 2 Inventive Steel D 1140 860 976 1.46 2.98 1.71 2.04 Comparative Material 3 Comparative Steel A 1240 920 984 1.49 3.12 1.69 2.09 Comparative Material 4 Comparative Steel B 1240 920 999 1.60 3.20 1.70 2.00 Comparative Material 5 Comparative Steel C 1240 920 1041 1.50 2.90 1.67 1.93

1) the iron loss (W _10/50) is being loss (W / kg) when the detection magnetic flux density of the organic 1.0Tesla at 50Hz frequency.

2) _Iron loss (W _15/50 ) is the loss (W / kg) when the magnetic flux density of 1.5 Tesla is induced at 50Hz frequency.

3) The magnetic flux density (B ₅₀ ) is the magnitude of the magnetic flux density (Tesla) induced when a magnetic field of 5000 A / m is added.

On the other hand, although the composition ratio consists of the component of this invention, it turns out that the comparative material (1,2) whose manufacturing conditions are out of the range of this invention has low magnetic characteristics.

In addition, the comparative steels A and B in which the content of P is outside the scope of the present invention, and the comparative materials (3 to 5) according to the comparative steel C in which the content of Al and P exceeded the upper limit of the present invention have low magnetic properties. It can be seen.

Example 2

By weight%, C: 0.0023%, Si: 0.602%, Al: 0.810%, P: 0.07% (P range: 0.04 to 0.10), S: 0.0005%, N: 0.0012%, Ti: 0.0011%, Mn : 0.53%, the slab composed of the remaining Fe and other unavoidable impurities is reheated to 1250 ℃, and the rolling temperature at finishing rolling of finishing rolling during hot rolling is 920 ℃, which is a ferrite region, and a 2.5mm thick hot rolled steel sheet is manufactured. It was.

The hot rolled steel sheet was wound at 700 ° C. and then air cooled, cold rolled to a thickness of 0.5 mm after pickling, and cold-rolled annealing was performed at 1000 ° C. for 70 minutes in nitrogen and 30% in hydrogen.

After the annealing is cut and then coated with an insulating coating of the continuously-inorganic composite, a result of measuring the magnetic properties, W _10/50 was 1.70W / kg. W _15/50 was 3.80W / kg. Therefore, the iron loss ratio (W _10/50 W _15/50) was 2.24, the magnetic flux density (B ₅₀₎ were excellent in magnetic properties as 1.81Tesla.

Example 3

By weight%, C: 0.0020%, Si: 1.10%, Al: 1.2%, P: 0.12% (P addition range: 0.06 to 0.17%), S: 0.0011%, N: 0.0016%, Mn: 0.70%, The slabs composed of the remaining Fe and other unavoidable impurities were reheated to 1140 ° C. and then hot rolled.

The end temperature of filament rolling during hot rolling was set at 980 ° C. to produce 2.0 mm thick hot rolled steel sheet. The steel sheet was wound up, cooled, cold rolled to a thickness of 0.5 mm, and annealed at 50 ° C. for 50 seconds.

Wherein the annealed sheet is a result, the iron loss of the magnetic characteristics of the steel sheet W _10/50 is was 1.30W / kg iron loss W _10/50 was 2.75W / kg investigated the magnetic properties were cut, dried and then coated with an insulating film was, W _{10 /} W _{50 15/50} / is was 2.12, the magnetic flux density (B ₅₀₎ is a magnetic characteristic was good to 1.74Tesla.

As described above, the non-oriented electrical steel sheet having excellent magnetic properties and a method of manufacturing the same according to the present invention produce more steel from Fe-Si steel by adding more Al instead of Si as a resistivity increasing component. As a result of adding Al, the magnetic flux density was higher than that of Si-added steel by adding P in the range of the invention. In particular, the magnetic properties were excellent even without annealing the hot rolled sheet.

Claims (2)

By weight%, C: 0.005% or less, Si: 1.5% or less, Mn: 0.1-1.5%, S: 0.005% or less, N: 0.003% or less, Al (%)> Si (%), Al (% ) / 20 ≦ P ≦ Al (%) / 8, wherein the non-oriented electrical steel sheet having excellent magnetism is characterized by consisting of a balance Fe and other inevitable impurities. By weight%, C: 0.005% or less, Si: 1.5% or less, Mn: 0.1-1.5%, S: 0.005% or less, N: 0.003% or less, Al (%)> Si (%), Al (% ) / 20≤P≤Al (%) / 8, the slab reheating temperature is set to 1200-1250 ° C when hot rolling a slab composed of remainder Fe and other unavoidable impurities. The method of producing a non-oriented electrical steel sheet having excellent magnetic properties, characterized in that the temperature of the finish hot rolling is terminated in a ferrite phase of 900 ~ 980 ℃.