KR101661897B1 - Non-oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

A method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention includes: preparing a hot rolled steel sheet by heating a slab and hot rolling; Cold-rolling the hot-rolled sheet to produce a cold-rolled sheet; And annealing the cold-rolled steel sheet for cold-rolled steel sheet, wherein annealing the cold-rolled steel sheet may be carried out while tension is applied to the steel sheet.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a non-oriented electrical steel sheet,

A non-oriented electrical steel sheet and a manufacturing method thereof.

The nonoriented electric steel sheet plays an important role in determining the energy efficiency of the electric equipment because the nonoriented electric steel sheet is used as an iron core material in rotating devices such as motors and generators and stationary devices such as small transformers, This is because it plays a role of converting it into mechanical energy.

The magnetic properties of the electric steel sheet include iron loss and magnetic flux density. The iron loss is energy loss, so the lower the better. On the other hand, when the magnetic flux density characteristic showing the property of easy magnetization is high, the same magnetic flux density can be obtained even if a smaller current is applied, so that heat loss caused by the copper wire wound can be reduced, and the higher the magnetic flux density characteristic is, the better.

In order to improve the iron loss among the magnetic properties of the non-oriented electrical steel sheet, a method of adding Si, Al, Mn or the like, which is an alloy element having a large resistivity, is generally used for increasing the electrical resistance. However, addition of an alloying element reduces the iron loss, but also decreases the magnetic flux density due to the decrease of the saturation magnetic flux density.

Moreover, if the amount of addition of silicon (Si) and aluminum (Al) increases, the workability is lowered, which makes it difficult to perform cold rolling, resulting in deteriorated productivity and increased hardness, resulting in poor workability.

The method that is effectively used for the improvement of the aggregate structure is known as a method of adding a trace alloy element. By using this, it is possible to manufacture a clean steel by reducing the fraction of crystal grains parallel to the <111> axis in the direction perpendicular to the sheet, which is a harmful texture, or by reducing the amount of impurities extremely.

However, all of these technologies cause a rise in manufacturing costs and difficulties in mass production, so that technology for improving magnetic properties is required without significantly increasing the manufacturing cost.

An embodiment of the present invention is to provide a non-oriented electrical steel sheet.

Another embodiment of the present invention is to provide a method for manufacturing a non-oriented electrical steel sheet.

The non-oriented electrical steel sheet according to one embodiment of the present invention is characterized in that the rolling direction of the steel sheet is defined as x axis, the width direction as y axis, and the normal direction of the xy plane as z axis, The length of the crystal grains) / (the length of the crystal grains in the z-axis direction) may be 1.5 or less.

Wherein said electrical steel sheet contains 0.0030% or less of Ti (not including 0%), 0.0035% or less of Nb (does not include 0%), 0.0040% or less (does not include 0% , [B]: 0.0003 to 0.0020%, and the balance of Fe and other inevitably added impurities, wherein (Ti) +0.8 [Nb] +0.5 [V] ) May be 0.17 to 7.8. Here, [Ti], [Nb], [V], and [B] are addition amounts (% by weight) of Ti, Nb, V and B, respectively.

In the electric steel sheet, inclusions containing Ti, Nb, V, and B were 500 / mm &lt; ^{2 &gt;} &Lt; / RTI &gt;

The grain size of the crystal grains of the electrical steel sheet may be 60 탆 to 95 탆.

Wherein said electrical steel sheet contains 0.004% or less of C (not including 0%), 2.5% to 3.5% of Si, 0.5% to 1.8% of Al, 0.05% to 0.9% 0.005% to 0.08% of Sn, 0.01% to 0.08% of Sn, 0.005% of Sb, and 0.005% or less of S (not including 0% To 0.05% or a combination thereof, wherein [P] + [Sn] + [Sb]: 0.01% to 0.1%.

A method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention includes: preparing a hot rolled steel sheet by heating a slab and hot rolling; Cold-rolling the hot-rolled sheet to produce a cold-rolled sheet; And annealing the cold-rolled steel sheet for cold-rolled steel sheet, wherein annealing the cold-rolled steel sheet may be carried out while tension is applied to the steel sheet.

The magnitude of the applied tension may be 0.6 kgf / mm ² or less.

Wherein the slab contains 0.0030% or less of Ti (not including 0%), 0.0035% or less of Nb (does not include 0%), 0.0040% or less (does not include 0% (B): 0.0003 to 0.0020%, and the balance includes Fe and other inevitably added impurities, wherein (Ti) +0.8 [Nb] +0.5 [V] / May be 0.17 to 7.8. Here, [Ti], [Nb], [V], and [B] are addition amounts (% by weight) of Ti, Nb, V and B, respectively.

Wherein the slab contains 0.004% or less C (not including 0%), 2.5 to 3.5% of Si, 0.5 to 1.8% of Al, 0.05 to 0.9% of Mn, 0.0015% of N, 0.005% to 0.08%, Sn: 0.01% to 0.08%, Sb: 0.005% to 0.05%, or combinations thereof , And [P] + [Sn] + [Sb]: 0.01% to 0.1%. [P], [Sn] and [Sb] are amounts of P, Sn and Sb added (wt%), respectively.

Further comprising the step of annealing the hot-rolled sheet by hot-rolling, and the hot-rolled sheet annealing temperature may be 850 to 1150 ° C.

In the step of annealing the cold rolled sheet, the annealing temperature of the cold rolled sheet may be 950 ° C to 1150 ° C.

According to an embodiment of the present invention, a non-oriented electrical steel sheet having low iron loss and excellent magnetic flux density can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

Thus, in some embodiments, well-known techniques are not specifically described to avoid an undesirable interpretation of the present invention. Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. Whenever a component is referred to as "including" an element throughout the specification, it is to be understood that the element may include other elements, not the exclusion of any other element, unless the context clearly dictates otherwise. Also, singular forms include plural forms unless the context clearly dictates otherwise.

Unless otherwise stated,% means weight%.

Hereinafter, a method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention will be described.

First, the slab is heated and hot-rolled to produce a hot-rolled sheet.

Wherein the slab contains 0.0030% or less of Ti (not including 0%), 0.0035% or less of Nb (does not include 0%), 0.0040% or less (does not include 0%) of V, , And B: 0.0003 to 0.0020%, and the remainder may contain Fe and other inevitably added impurities.

Further, the value of ([Ti] +0.8 [Nb] +0.5 [V]) / (10 * [B]) may be 0.17 to 7.8. Here, [Ti], [Nb], [V], and [B] are addition amounts (% by weight) of Ti, Nb, V and B, respectively.

The slab may contain, by weight%, 0.004% or less of C (not including 0%), 2.5 to 3.5% of Si, 0.5 to 1.8% of Al, 0.05 to 0.9% of Mn and 0.0015 [Sn] + [Sb] + [Sn] + [Sn] + 0.001% : 0.01% to 0.1%. [P], [Sn] and [Sb] are amounts of P, Sn and Sb added (wt%), respectively.

The reason why the composition of the slab is limited will be described.

If C is more than 0.004%, a problem of causing self-aging may occur.

Si plays a role of lowering the iron loss by increasing the resistivity. If the content of Si is less than 2.5%, the effect of improving the iron loss is insufficient. If the content of Si is more than 3.5%, the hardness may increase and the productivity and saturation may be lowered.

Al acts to lower the iron loss by increasing the resistivity. If the content of Al is less than 0.5%, there is no effect of reducing the high frequency iron loss, and the nitride may be formed finely to deteriorate the magnetic property. If the content of Al exceeds 1.8%, the magnetic flux density may be deteriorated, .

Mn enhances the resistivity and improves the iron loss and forms a sulfide. If the Mn content is less than 0.05%, MnS may be precipitated to deteriorate the magnetic properties. If the Mn content exceeds 0.9%, [111] aggregate structure may be formed and the magnetic flux density may be reduced.

If N is more than 0.0030%, it may be combined with Ti, Nb and V to form a nitride to suppress grain growth and magnetic domain migration. Therefore, in an embodiment of the present invention, N may not be added, but may be added in an amount of 0.0015 or more in view of the amount that is inevitably incorporated during the steelmaking process.

P enhances the resistivity of the material and segregates in grain boundaries to improve the texture and improve the magnetism. If less than 0.005% is added, there is no effect of improving the texture, and if it exceeds 0.08%, the grain segregation will be excessive, and the rolling property will be weakened and the scratching property may be lowered.

Sn can improve the magnetization by improving the texture. If the addition amount of Sn is less than 0.01%, the effect of improving the magnetic properties is not obtained. If the addition amount exceeds 0.08%, the grain boundary is weakened and fine inclusions are formed to deteriorate the magnetic properties.

Sb can improve the magnetization by improving the texture. If the addition amount of Sb is less than 0.005%, the effect of improving the magnetic properties is not obtained. If the addition amount exceeds 0.05%, not only the grain boundaries are weakened but also fine inclusions are formed to deteriorate the magnetic properties.

If the content of [P] + [Sn] + [Sb] is less than 0.01%, there is no effect of improving the magnetic property. If the content exceeds 0.1%, the grain growth is poor, It can aggravate.

If S is more than 0.0030%, fine sulphide is formed to suppress crystal grain growth and iron loss can be caused.

When Ti is added in an amount exceeding 0.0030%, fine nitride may be formed and the grain growth property may be deteriorated.

If Nb is added in an amount exceeding 0.0035%, fine nitride may be formed and the grain growth can be deteriorated.

If V is added in an amount exceeding 0.0040%, fine nitride may be formed and crystal growth may be deteriorated.

If B is less than 0.0003%, fine nitrides may be formed and magnetization may be dislocated. If B is more than 0.0020%, excess B that does not form nitride may interfere with the movement of the magnetic domains, and magnetic properties may be lowered.

When the value of (Ti + 0.8 [Nb] + 0.5 [V]) / (10 * [B]) is less than 0.17 or exceeds 7.8, the inclusions are not coarsened, , And [111] texture unfavorable to magnetism can be formed.

The slab of the substrate is heated. The heating temperature at the time of heating the slab may be between 1100 ° C and 1250 ° C. When the heating of the slab is completed, the slab is hot-rolled to produce a hot-rolled sheet. Finishing rolling in hot rolling can be carried out at 800 ° C or higher.

The hot-rolled hot-rolled sheet is subjected to hot-rolled sheet annealing at a temperature of 850 캜 to 1150 캜, if necessary, to increase the crystal orientation favorable to magnetism. If the annealing temperature of the hot-rolled sheet is less than 850 캜, the structure does not grow or grows finely and the synergistic effect of the magnetic flux density is small. If the annealing temperature exceeds 1150 캜, the magnetic properties may deteriorate and the plate-like shape may be deformed. More specifically, the hot-rolled sheet annealing temperature may be 950 ° C to 1,150 ° C. Then, the hot rolled sheet is pickled, and cold rolled at a reduction ratio of 70% to 95% to produce a cold rolled sheet.

The cold-rolled sheet is subjected to cold-rolled sheet annealing. It is possible to carry out the annealing while the tensile force is applied to the steel sheet by the winding roll at the time of annealing the cold rolled sheet.

The magnitude of the tension applied to the steel sheet may be 0.6 kgf / mm ² or less. It is possible to improve the magnetic properties of the electric steel sheet by controlling the ratio of the grain size of the electric steel sheet by performing the annealing of the cold rolled sheet in the state of applying the tensile force to the steel sheet. However, when the applied tension is 0.6 kgf / mm ² The crystal grains may be excessively deformed and the magnetism may become dull. Further, when the magnitude of the tension applied to the steel sheet is 0.2 kgf / mm &lt; ^{2 &gt;} , The improvement of the magnetic properties due to the crystal grain modification may be less likely to occur.

The cold-rolled sheet annealing temperature may be 950 캜 to 1150 캜. If the temperature is lower than 950 占 폚, recrystallization may not be sufficiently generated, and when the temperature exceeds 1050 占 폚, crystal grains may become larger and the high-frequency iron loss may become dull.

The crystal grains are grown at the time of annealing the cold rolled sheet, and the size of the grain can be adjusted to 60 to 95 占 퐉 by controlling the annealing temperature of the cold rolled sheet and annealing time of the cold rolled sheet. If the thickness is less than 60 mu m, recrystallization does not sufficiently occur and the magnetic property is not improved. When the thickness exceeds 95 mu m, the crystal grains are excessively grown and the magnetic property can be dislocated at a high frequency.

Hereinafter, a non-oriented electrical steel sheet according to an embodiment of the present invention will be described.

The non-oriented electrical steel sheet according to one embodiment of the present invention is characterized in that the rolling direction of the steel sheet is defined as x axis, the width direction as y axis, and the normal direction of the xy plane as z axis, The length of the crystal grains) / (the length of the crystal grains in the z-axis direction) may be 1.5 or less. When the value of (the length of the crystal grains in the y-axis direction) / (the length of the crystal grains in the z-axis direction) at this time exceeds 1.5, the crystal grain deformation becomes excessively large, Can be lowered. The value of (the length of the crystal grains in the y-axis direction) / (the length of the crystal grains in the z-axis direction) may be 1.18 or more. If it is less than 1.18, the effect of improving the magnetic properties due to crystal grain modification can not be expected.

Wherein said electrical steel sheet contains 0.0030% or less of Ti (not including 0%), 0.0035% or less of Nb (does not include 0%), 0.0040% or less (does not include 0% , [B]: 0.0003 to 0.0020%, and the balance of Fe and other inevitably added impurities, wherein (Ti) +0.8 [Nb] +0.5 [V] ) May be 0.17 to 7.8. Here, [Ti], [Nb], [V], and [B] are addition amounts (% by weight) of Ti, Nb, V and B, respectively.

The electrical steel sheet may further contain 0.004% or less of C (not including 0%), 2.5% to 3.5% of Si, 0.5% to 1.8% of Al, 0.05% to 0.9% of Mn, and N : 0.0030% or less (excluding 0%), P: 0.005% to 0.08%, Sn: 0.01% to 0.08%, Sb: 0.005% to 0.05% + [Sn] + [Sb]: 0.01% to 0.1%. [P], [Sn] and [Sb] are amounts of P, Sn and Sb added (wt%), respectively.

The reason for limiting the components in the electric steel sheet is the same as the reason for the limitation in the slab.

In the electrical steel sheet, the inclusions containing Ti, Nb, V, and B have a density of 500 / mm ² &Lt; / RTI &gt; More specifically, it may be 5 pieces / mm ² or less. 5 inclusions / mm ² If it is exceeded, the inclusions may be excessive and the magnetism may be dislocated.

The grain size of the grain of the electrical steel sheet may be 60 to 95 탆.

Hereinafter, the embodiment will be described in detail. The following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention.

[Example 1]

Slabs having the same composition as shown in Table 1 were prepared. Then, the slab was heated to 1150 DEG C and hot-rolled. The hot rolling was carried out at 850 ° C and the hot rolled steel sheet was 2.0 mm thick.

The hot-rolled sheet was then annealed at 1100 ° C for 4 minutes, hot rolled, and pickled.

Thereafter, cold-rolled steel sheets having thicknesses as shown in Table 2 were prepared.

Thereafter, cold rolled sheet annealing was performed at 970 캜 for 35 seconds.

In the case of the steel according to the present invention, the grain growth is good, and P, Sn, and Sb are added to improve the texture, and thus the magnetic properties are excellent. On the other hand, it can be seen that the remaining steel grades deviate from the scope of the present invention and the grain size is smaller and the magnetism is larger than that of the final annealed at the similar temperature to open the grain growth.

[Example 2]

The slabs having the components shown in Table 3 were heated, hot rolled, hot rolled sheet annealed, and cold rolled in the same manner as in Example 1.

Thereafter, cold rolled sheet annealing was performed at 970 캜 for 35 seconds, and annealing was performed while applying a tensile force as shown in Table 4.

In Table 3,% is wt%.

In Table 4, the longitudinal direction stretching ratio is defined as (the length of the crystal grains in the y-axis direction) / (the length of the crystal grains in the y-axis direction) measured in the yz plane when the rolling direction of the steel sheet is the x axis, the width direction is the y axis, (the length of the crystal grains in the z-axis direction).

The inclusion was measured by TEM and analyzed by EDS. The TEM observation was carried out at a randomly selected area with a magnification of at least 0.01 μm, and the size and distribution of all inclusions were measured. The EDS spectra were used to determine the type of inclusions Respectively.

In the case of F2, F4, F6 and F7 falling within the scope of the present invention, the annealing tension is 0.6 kgf / mm2 or less and the elongation ratio in the tensile direction is 1.5 or less. On the other hand, if the tensile strength was 0.6 kgf / mm &lt; 2 &gt; or more, the elongation in the longitudinal direction was increased, the distribution density was increased, and the iron loss at 800 Hz was worse.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (11)

(Inclusive of 0%), C: 2.5% to 3.5%, Al: 0.5% to 1.8%, Mn: 0.05% to 0.9%, C: N: not more than 0.0030% (not including 0%), S: not more than 0.0030% (not including 0%), Ti: not more than 0.0030% , V: not more than 0.0040% (excluding 0%), and B: not more than 0.0003 to 0.0020%, the balance including Fe and other inevitably added impurities,
0.005 to 0.08% of P, 0.01 to 0.08% of Sn, 0.005 to 0.05% of Sb, or a combination thereof,
[P] + [Sn] + [Sb]: 0.01% to 0.1%
([Ti] +0.8 [Nb] +0.5 [V]) / (10 * [B]) is 0.17 to 7.8,
(The length of the crystal grains in the y-axis direction) / (the length of the crystal grains in the z-axis direction) measured on the yz plane when the rolling direction of the steel sheet is the x-axis, the width direction is the y- Of 1.18 to 1.25.
(% By weight) of Ti, Nb, V and B, respectively, where [Ti], [Nb], [V]
([P], [Sn], and [Sb] are the addition amounts (% by weight) of P, Sn, and Sb, respectively)
delete The method according to claim 1,
Wherein the inclusion containing Ti, Nb, V, and B in the electrical steel sheet is 500 / mm ² or less.
The method of claim 3,
Wherein the grain size of the grain of the electrical steel sheet is 60 占 퐉 to 95 占 퐉.
delete C: not more than 0.004% (not including 0%), Si: 2.5 to 3.5%, Al: 0.5 to 1.8%, Mn: 0.05 to 0.9%, N , 0.0030% to 0.0030% of S, 0.0030% or less of S (not including 0%), 0.0030% or less of Ti (not including 0%), 0.0035% or less of Nb : 0.0040% or less (does not include 0%), and B: 0.0003 to 0.0020% or less, the balance including Fe and other inevitably added impurities,
0.001 to 0.08% of P, 0.01 to 0.08% of Sn, 0.005 to 0.05% of Sb, or a combination thereof, and satisfies 0.01 to 0.1% of [P] + [Sn] + [Sb] and,
Heating a slab having a value of (Ti + 0.8 [Nb] +0.5 [V]) / (10 * [B]) of 0.17 to 7.8, followed by hot rolling to produce a hot rolled sheet;
Cold-rolling the hot-rolled sheet to produce a cold-rolled sheet; And
And annealing the cold-rolled sheet for cold-rolled sheet,
Wherein the step of annealing the cold rolled sheet is carried out while applying a tensile force of 0.2 kgf / mm ² to 0.5 kgf / mm ^{2 to} the steel sheet.
(% By weight) of Ti, Nb, V and B, respectively, where [Ti], [Nb], [V]
([P], [Sn] and [Sb] are the addition amounts (% by weight) of P, Sn and Sb, respectively)
delete delete delete The method according to claim 6,
Further comprising the step of annealing the hot-rolled sheet by hot-
Wherein the hot-rolled sheet annealing temperature is 850 to 1150 ° C.
11. The method of claim 10,
Wherein the annealing temperature of the cold rolled sheet in the step of annealing the cold rolled sheet is 950 ° C to 1150 ° C.