KR20230096878A - Non-oriented electrical steel sheet, method for manufacturing the same and motor core comprising the same - Google Patents

Abstract

A non-oriented electrical steel sheet according to an embodiment of the present invention includes: a steel sheet base material containing 1.0 to 6.5 wt% of Si, 0.1 to 1.3 wt% of Al, 0.3 to 2.0 wt% of Mn, and the balance Fe and inevitable impurities; and an insulating film located on the steel sheet base material, wherein the steel sheet base material satisfies the following Formula 1, and the insulating film satisfies the following Formula 2: [Formula 1] 0.1 <= [Mn(1)] / [Mn(10)] <= 1.0; and [Formula 2] [Fe] >= ([Al] + [Mn] + [Mg] / 10) (in the Formula 1, [Mn(1)] represents the Mn concentration (wt%) at a depth of 1 μm from the boundary surface between the base material and the insulating film in the inward direction of the base material, and [Mn(10)] represents the Mn concentration at a depth of 10 μm. In Formula 2, [Fe], [Al], [Mn], and [Mg] represent the contents (wt%) of Fe, Al, Mn, and Mg at the center of the thickness direction of the insulating film.) Therefore, non-oriented electrical steel sheets can improve the stability of the coating after stress relief annealing.

Description

Non-oriented electrical steel sheet, manufacturing method thereof, and motor core including the same

One embodiment of the present invention relates to a non-oriented electrical steel sheet, a manufacturing method thereof, and a motor core including the same. Specifically, an embodiment of the present invention increases the shot ball projection during scale removal, strengthens pickling, suppresses the concentration of Mn on the surface of the steel sheet, and controls the element content in the insulating film, so that the coating after stress relief annealing It relates to a non-oriented electrical steel sheet with improved bonding force, a method for manufacturing the same, and a motor core including the same.

Non-oriented electrical steel sheets are mainly used in motors that convert electrical energy into mechanical energy, and excellent magnetic properties of non-oriented electrical steel sheets are required to demonstrate high efficiency in the process. In particular, as eco-friendly technology has recently been attracting attention, it is considered very important to increase the efficiency of motors that account for the majority of the total electrical energy consumption. To this end, the demand for non-oriented electrical steel sheets having excellent magnetic properties is also increasing.

The magnetic properties of non-oriented electrical steel are mainly evaluated by iron loss and magnetic flux density. Iron loss means energy loss that occurs at a specific magnetic flux density and frequency, and magnetic flux density means the degree of magnetization obtained under a specific magnetic field. The lower the iron loss, the more energy efficient motors can be manufactured under the same conditions, and the higher the magnetic flux density, the smaller the motor or the lower the copper loss. It is important.

The characteristics of the non-oriented electrical steel sheet to be considered also vary according to the operating conditions of the motor. As a criterion for evaluating the characteristics of non-oriented electrical steel used in motors, many motors regard W15/50, which is the iron loss when a 1.5T magnetic field is applied at a commercial frequency of 50Hz, as the most important. However, not all motors for various purposes consider W15/50 core loss as the most important, and depending on the main operating conditions, core loss at different frequencies or applied magnetic fields is evaluated. In particular, in non-oriented electrical steel sheets used in recent electric vehicle drive motors, magnetic properties are often important at low fields of 1.0T or less and high frequencies of 400 Hz or more. characteristics will be evaluated.

In order to manufacture products such as motors or transformers from non-oriented electrical steel sheet, the non-oriented electrical steel sheet must be slit into a specific shape. In this process, stress is applied to the non-oriented electrical steel sheet, and stress relief annealing is performed to remove this stress.

In one embodiment of the present invention, it is intended to provide a non-oriented electrical steel sheet, a manufacturing method thereof, and a motor core including the same. Specifically, in one embodiment of the present invention, by increasing the shot ball projection during scale removal, strengthening pickling, suppressing the concentration of Mn on the surface of the steel sheet, and adjusting the element content in the insulating film, the coating after stress relief annealing It is intended to provide a non-oriented electrical steel sheet with improved bonding force, a method for manufacturing the same, and a motor core including the same.

In the non-oriented electrical steel sheet according to an embodiment of the present invention, by weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, and the balance of Fe and unavoidable impurities. Including an insulating film positioned on the base material, the steel sheet base material after stress relief annealing satisfies Expression 1 below, and the insulating film satisfies Expression 2 below.

[Equation 1]

0.1 ≤ [Mn(1)] / [Mn(10)] ≤ 1.0

[Equation 2]

[Fe] ≥ ([Al] + 2[Mn] + [Mg]) / 10

(In Equation 1, [Mn(1)] is the Mn concentration (wt%) at a depth of 1 μm from the interface between the base material and the insulating film toward the inside of the base material, and [Mn(10)] is at a depth of 10 μm represents the Mn concentration of

In Equation 2, [Fe], [Al], [Mn], and [Mg] represent the contents (wt%) of Fe, Al, Mn, and Mg at the center of the insulation film thickness direction.)

The steel sheet base material may further contain at least one of Cr: 0.2% or less (excluding 0%), Sn: 0.06% or less (excluding 0%), and Sb: 0.06% or less (excluding 0%). can

The steel plate base material may further include 0.005% by weight or less of one or more of C, N, S, Ti, Nb, and V.

The steel sheet base material contains at least one of Cu: 0.01 to 0.2 wt%, P: 0.100 wt% or less, B: 0.002 wt% or less, Mo: 0.01 wt% or less, Mg: 0.005 wt% or less, and Zr: 0.005 wt% or less. can include more.

The base material of the steel sheet may have an average grain size of 5 to 50 μm.

The adhesion amount of the insulating film may be 500 to 1500 mg/m ² .

A method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention is a slab containing, by weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, the balance Fe, and unavoidable impurities. preparing a hot-rolled sheet by hot-rolling; removing scale present on the surface of the hot-rolled sheet; Cold-rolling the scale-removed hot-rolled sheet to prepare a cold-rolled sheet; It includes the steps of annealing a cold-rolled sheet and forming an insulating film on the surface of the cold-rolled sheet, and the step of removing the scale includes the step of projecting a short ball onto the steel sheet to remove scale and immersing in pickling liquid to pickle Include steps.

The following relationship between the projected amount of short balls (kg/(m2·min)) and the pickling solution immersion time (seconds) can be satisfied.

[thrown amount] / [immersion time] ≥ 0.5

In the step of removing the scale, the step of removing the scale by projecting a short ball on the steel plate in an amount of 15 kg / (m 2 min) to 35 kg / (m 2 min) and pickling may be immersed in pickling liquid for 5 seconds to 120 seconds.

The average particle size of the short ball is 0.3 to 0.8 mm, and it can be projected for 5 to 30 seconds.

The material of the short ball is not particularly limited, but Fe-based alloys may be used.

The step of annealing the cold-rolled sheet may be annealed at a temperature of 700 to 900 ° C.

A step of annealing the hot-rolled sheet may be further included prior to the step of removing the scale.

A motor core according to an embodiment of the present invention includes a stator formed by stacking a plurality of non-oriented electrical steel sheets, and the non-oriented electrical steel sheet in the stator contains, by weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%. , Mn: 0.3 to 2.0%, and a steel sheet base material containing Fe and unavoidable impurities, and an insulating film located on the steel plate base material, the steel plate base material satisfies the following formula 1, and the insulating film satisfies the following formula 2 .

[Equation 1]

0.1 ≤ [Mn(1)] / [Mn(10)] ≤ 1.0

[Equation 2]

[Fe] ≥ ([Al] + 2[Mn] + [Mg]) / 10

(In Equation 1, [Mn(1)] is the Mn concentration (wt%) at a depth of 1 μm from the interface between the base material and the insulating film toward the inside of the base material, and [Mn(10)] is at a depth of 10 μm represents the Mn concentration of

In Equation 2, [Fe], [Al], [Mn], and [Mg] represent the contents (wt%) of Fe, Al, Mn, and Mg at the center of the insulation film thickness direction.)

The motor core according to an embodiment of the present invention further includes a rotor formed by stacking a plurality of non-oriented electrical steel sheets, and the non-oriented electrical steel sheet contains, by weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%. , Mn: 0.3 to 2.0%, and a steel sheet base material containing Fe and unavoidable impurities, and an insulating film located on the steel plate base material, and the steel plate base material may have an average grain size of 5 to 50 μm.

The non-oriented electrical steel sheets included in the stator and the rotor may be non-oriented electrical steel sheets derived from the same coil.

A difference in Si, Al, and Mn contents between the non-oriented electrical steel sheets included in the stator and the rotor may be 0.20% by weight or less.

According to an embodiment of the present invention, it is possible to suppress the concentration of Mn on the surface of the steel sheet by increasing the shot ball projection amount and strengthening pickling during scale removal. Through this, the bonding strength of the coating after stress relief annealing is improved.

In addition, according to one embodiment of the present invention, the element content in the insulating film is controlled, and through this, the stability of the coating after stress relief annealing is improved.

Through this, the performance of eco-friendly automobile motors, high-efficiency home appliance motors, and super premium electric motors can be further improved through stress relief annealing.

Terms such as first, second and third are used to describe, but are not limited to, various parts, components, regions, layers and/or sections. These terms are only used to distinguish one part, component, region, layer or section from another part, component, region, layer or section. Accordingly, a first part, component, region, layer or section described below may be referred to as a second part, component, region, layer or section without departing from the scope of the present invention.

The terminology used herein is only for referring to specific embodiments and is not intended to limit the present invention. As used herein, the singular forms also include the plural forms unless the phrases clearly indicate the opposite. The meaning of "comprising" as used herein specifies particular characteristics, regions, integers, steps, operations, elements and/or components, and the presence or absence of other characteristics, regions, integers, steps, operations, elements and/or components. Additions are not excluded.

When a part is referred to as being “on” or “on” another part, it may be directly on or on the other part or may be followed by another part therebetween. In contrast, when a part is said to be “directly on” another part, there is no intervening part between them.

In addition, unless otherwise specified, % means weight%, and 1ppm is 0.0001 weight%.

In one embodiment of the present invention, the meaning of further including an additional element means replacing and including iron (Fe) as much as the additional amount of the additional element.

Although not defined differently, all terms including technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Terms defined in commonly used dictionaries are additionally interpreted as having meanings consistent with related technical literature and currently disclosed content, and are not interpreted in ideal or very formal meanings unless defined.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

A non-oriented electrical steel sheet according to an embodiment of the present invention includes a steel sheet base material and an insulating film positioned on the steel sheet base material.

The steel sheet base material according to an embodiment of the present invention includes Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, the balance Fe and unavoidable impurities, by weight%.

Hereinafter, the reason for limiting the components of the steel sheet base material will be explained.

Si: 2.0 to 6.5% by weight

Silicon (Si, silicon) serves to lower the iron loss by increasing the specific resistance of the material, and when too little is added, the effect of improving the high frequency iron loss may be insufficient. Conversely, if too much is added, the hardness of the material increases and the cold rolling property is extremely deteriorated, resulting in poor productivity and punching performance. Therefore, Si may be added within the above range. More specifically, it may include 2.5 to 5.0% by weight. More specifically, it may include 3.0 to 4.0% by weight.

Al: 0.1 to 1.3% by weight

Aluminum (Al) serves to lower iron loss by increasing the resistivity of the material. If too little is added, there is no effect on reducing high-frequency iron loss, and fine nitrides may be formed to deteriorate magnetism. Conversely, if too much is added, it can cause problems in all processes such as steelmaking and continuous casting, greatly reducing productivity. Therefore, Al may be added within the above range. More specifically, it may contain 0.5 to 1.2% by weight. More specifically, it may contain 0.7 to 1.0% by weight.

Mn: 0.3 to 2.0% by weight

Manganese (Mn) is an element that serves to improve iron loss and form sulfides by increasing the resistivity of materials. If too little Mn is added, sulfides may be finely precipitated to deteriorate magnetism. Conversely, if too much Mn is added, the formation of {111} texture, which is unfavorable to magnetism, may be promoted and the magnetic flux density may decrease. Therefore, Mn may be added within the above-mentioned range. More specifically, 0.5 to 1.5 wt % of Mn may be included.

In one embodiment of the present invention, the specific resistance may be 55 to 80 μΩ cm.

The steel sheet base material may further contain at least one of Cr: 0.2% or less (excluding 0%), Sn: 0.06% or less (excluding 0%), and Sb: 0.06% or less (excluding 0%). can

Cr: 0.20% by weight or less

Chromium (Cr) serves to reduce iron loss by increasing the resistivity of the material. It also serves to prevent diffusion of Mn from the base material into the insulating film in the stress relief annealing step. Therefore, Cr may be added within the above range. More specifically, it may contain 0.010 to 0.10% by weight. More specifically, it may include 0.050 to 0.040% by weight. As described above, when an additional element is further included, Fe, which is the remainder, is replaced and included.

Sn: 0.06% by weight or less and Sb: 0.06% by weight or less

Tin (Sn) and antimony (Sb) are segregated elements at grain boundaries, suppressing the diffusion of nitrogen through grain boundaries, suppressing {111} texture harmful to magnetism, and increasing advantageous {100} texture for magnetic properties. added to improve When too much Sn and Sb are added, crystal grain growth is hindered, resulting in deterioration of magnetism and poor rolling properties. Therefore, Sn and Sb may be added within the above range. More specifically, Sn: 0.005 to 0.050% by weight and Sb: 0.005 to 0.050% by weight may be included. More specifically, Sn: 0.01 to 0.02% by weight and Sb: 0.01 to 0.02% by weight may be included.

The steel sheet base material contains at least one of Cu: 0.01 to 0.2 wt%, P: 0.100 wt% or less, B: 0.002 wt% or less, Mo: 0.01 wt% or less, Mg: 0.005 wt% or less, and Zr: 0.005 wt% or less. can include more.

Cu: 0.01 to 0.20% by weight

Copper (Cu) serves to form a sulfide together with Mn. When Cu is further added, CuMnS may finely precipitate and degrade magnetism if too little is added. If too much Cu is added, high-temperature brittleness may occur and cracks may be formed during playing or hot rolling. More specifically, 0.05 to 0.10 wt% of Cu may be included.

P 0.100% by weight or less

Phosphorus (P) not only serves to increase the specific resistance of the material, but also segregates at the grain boundary to improve the texture to increase the specific resistance and lower the iron loss, so it can be additionally added. However, too much addition of P results in the formation of a texture that is unfavorable to magnetism, so there is no effect on improving the texture, and excessive segregation at grain boundaries reduces rollability and workability, making production difficult. Therefore, P may be added in the above range. More specifically, 0.001 to 0.090% by weight of P may be included. More specifically, 0.005 to 0.085% by weight of P may be included.

B: 0.002 wt% or less, Mo: 0.01 wt% or less, Mg: 0.005 wt% or less, and Zr: 0.005 wt% or less

In the case of boron (B), molybdenum (Mo), magnesium (Mg), and zirconium (Zr), they react with impurity elements to form fine sulfides, carbides, and nitrides, which have a detrimental effect on magnetism. can be limited

The steel plate base material may further include 0.005% by weight or less of one or more of C, N, S, Ti, Nb, and V.

C: 0.005% by weight or less

When carbon (C) is added in large amounts, it expands the austenite region, increases the phase transformation period, and inhibits the grain growth of ferrite during annealing to increase iron loss. When used after processing from a product to an electrical product, iron loss is increased by magnetic aging. Therefore, C may be added within the above range. More specifically, 0.003% by weight or less of C may be included.

S: 0.005% by weight or less

Sulfur (S) is preferably added as low as possible because it forms fine sulfides inside the base material to suppress crystal grain growth and weaken iron loss. When a large amount of S is included, it may combine with Mn to form precipitates or cause high temperature brittleness during hot rolling. Accordingly, S may be further included in an amount of 0.005% by weight or less. Specifically, it may further include 0.0030% by weight or less of S. More specifically, 0.0001 to 0.0030% by weight of S may further be included.

N: 0.005% by weight or less

Nitrogen (N) forms nitride by strongly combining with Al, Ti, etc. to suppress crystal grain growth, and when precipitated, it is preferable to contain less because it interferes with magnetic domain movement. Therefore, N may be added in the above range. More specifically, 0.003% by weight or less of N may be included.

Ti, Nb, V: 0.005 wt% or less each

Since titanium (Ti), niobium (Nb), and vanadium (V) are also strong carbonitride-forming elements, it is preferable not to add them as much as possible, and each content is 0.005% by weight or less.

The balance includes Fe and unavoidable impurities. As for the unavoidable impurities, they are impurities introduced during the steelmaking step and the grain-oriented electrical steel sheet manufacturing process, and since they are well known in the relevant field, a detailed description thereof will be omitted. In one embodiment of the present invention, the addition of elements other than the above-described alloy components is not excluded, and may be variously included within a range that does not impair the technical spirit of the present invention. When additional elements are included, they are included in place of Fe, which is the remainder.

The non-oriented electrical steel sheet according to an embodiment of the present invention may have an average grain size of 5 to 50 μm. If the average grain size is too small, magnetic properties are inferior, and crystal grain growth is limited even after stress relief annealing (SRA), so that magnetism may be inferior even after SRA. If the average grain size is too large, mechanical strength may be inferior. More specifically, the average grain size may be 10 to 35 μm. The average grain size described above is a characteristic before SRA.

After SRA, the base material of the steel sheet may satisfy Equation 1 below.

[Equation 1]

0.1 ≤ [Mn(1)] / [Mn(10)] ≤ 1.0

(In Equation 1, [Mn(1)] is the Mn concentration (wt%) at a depth of 1 μm from the interface between the base material and the insulating film toward the inside of the base material, and [Mn(10)] is at a depth of 10 μm represents the Mn concentration of

As shown in Equation 1, the steel sheet base material according to an embodiment of the present invention has a concentration gradient in which the concentration of Mn increases from the surface to the inside. Conversely, when Mn is concentrated on the surface, the Mn of the base material diffuses into the coating in the stress relief annealing step, and the properties of the coating change, thereby deteriorating the bonding strength of the coating. In addition, even when the value of [Mn(1)]/[Mn(10)] is too small, high-frequency iron loss, which is a magnetic characteristic, may be inferior due to a decrease in resistivity of the base material surface. More specifically, the value of [Mn(1)]/[Mn(10)] may be 0.3 to 0.7. The concentration of Mn by thickness can be analyzed through glow discharge spectroscopy (GDS).

The insulating film is located on the surface of the base material of the steel sheet. The insulating film 20 serves to insulate between the non-oriented electrical steel sheets when a product is manufactured by laminating the non-oriented electrical steel sheets. The insulating film may be treated with an organic, inorganic, or organic/inorganic composite film, and may be formed by treating with another insulating film.

In one embodiment of the present invention, concentration of Mn on the surface side of the steel sheet base material is prevented, and thus, diffusion of Mn into the insulating film can be suppressed. After stress relief annealing, the insulating film may satisfy Equation 2 below.

[Equation 2]

[Fe] ≥ ([Al] + 2[Mn] + [Mg])/10

(In Equation 2, [Fe], [Al], [Mn], and [Mg] represent the contents (wt%) of Fe, Al, Mn, and Mg in the center of the insulation film thickness direction.)

Specifically, it varies depending on the type of insulating film, but in the center of the thickness direction of the insulating film, 0.5 to 30% by weight of Fe, 1 to 20% by weight of Al, 0.5 to 5% by weight of Mn, and 0.1 to 10% by weight of Mg may be included. Some of Al, Mn, and Mg, which are components in the insulation coating, are components diffused from the base material of the steel sheet. On the other hand, when the content of Al, Mn, Mg, etc. in the insulating film is high, the insulating property of the insulating film may be deteriorated. In addition, the bonding strength between the insulating film and the base material may be weakened.

A method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention includes the steps of hot-rolling a slab to prepare a hot-rolled sheet; removing scale present on the surface of the hot-rolled sheet; Cold-rolling the scale-removed hot-rolled sheet to prepare a cold-rolled sheet; It includes the steps of annealing a cold-rolled sheet and forming an insulating film on the surface of the cold-rolled sheet.

First, a slab is hot rolled.

Since the alloy components of the slab have been described in the above-described alloy components of the non-oriented electrical steel sheet, overlapping descriptions will be omitted. Since the alloy components are not substantially changed during the manufacturing process of the non-oriented electrical steel sheet, the alloy components of the non-oriented electrical steel sheet and the slab are substantially the same.

Specifically, the slab includes Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, and the balance Fe and unavoidable impurities, by weight%.

Since the other additional elements have been described in the alloy components of the non-oriented electrical steel sheet, overlapping descriptions are omitted.

The slabs may be heated prior to hot rolling. The heating temperature of the slab is not limited, but the slab can be heated to 1100 to 1250 ° C. If the slab heating temperature is too high, precipitates that harm magnetism may be re-dissolved and finely precipitated after hot rolling.

Next, a hot-rolled sheet is manufactured by hot-rolling the slab. The thickness of the hot-rolled sheet may be 2 to 3.0 mm.

After the step of manufacturing the hot-rolled sheet, a step of annealing the hot-rolled sheet may be further included. Hot-rolled sheet annealing is preferably performed in the manufacture of a high-grade electrical steel sheet without phase transformation, and is effective in improving the magnetic flux density by improving the texture of the final annealed sheet.

At this time, the step of annealing the hot-rolled sheet may be annealed at a temperature of 850 to 1200 ℃. If the hot-rolled sheet annealing temperature is too low or less, the structure does not grow or grows finely, making it difficult to expect the effect of increasing the magnetic flux density. If the annealing temperature of the hot-rolled sheet is too high, the magnetic properties are rather deteriorated, and the rolling workability may be deteriorated due to deformation of the plate shape. Hot-rolled sheet annealing is performed to increase orientation favorable to magnetism, if necessary, and can be omitted. The annealed hot-rolled sheet may be pickled.

Next, the scale present on the surface of the hot-rolled sheet is removed. In one embodiment of the present invention, the concentration of Mn on the surface of the steel sheet is suppressed through the removal of the oxide layer before final annealing by increasing the amount of shot balls and strengthening pickling.

The step of removing the scale includes removing the scale by projecting a short ball onto the steel sheet in an amount of 15 to 35 kg/(m 2 ·min). If the projection amount of the shot ball is too small, the oxide layer remains and amplifies the surface segregation phenomenon of Mn. As a result, Mn diffusion into the insulating film is increased in the stress relief annealing step. Conversely, if the projected amount of the short ball is too large, the surface of the steel plate is greatly damaged, so the upper limit can be adjusted appropriately. More specifically, it may be projected onto the steel sheet in an amount of 17 to 30 kg/(m 2 ·min). Even if the same amount per area is projected, a difference occurs in securing the fine crystal grains depending on the length of time to be projected, so in one embodiment of the present invention, the amount of projection according to time and area is defined.

The average particle size of the short ball is 0.1 to 1 mm, and it can be projected for 1 second to 60 seconds. More specifically, the average particle size of the short ball is 0.3 to 0.8 mm, and it can be projected for 5 to 30 seconds. The average particle size of the shotball and the shotball projection time can also affect the surface nucleation site.

The material of the short ball is not particularly limited, but Fe-based alloys may be used.

By immersing the hot-rolled sheet in pickling liquid, the surface of the steel sheet with high radiation can be made smooth. The pickling solution is not particularly limited, and hydrochloric acid and sulfuric acid may be used. If the concentration of the pickling solution and the immersion time are too low or short, the roughness of the steel sheet damaged by short balls is not improved, and thus Mn diffuses to the surface through the defective part during final annealing. This phenomenon may be a problem in maintaining the bonding strength of the insulating film in the stress relief annealing step. Conversely, if the concentration of the pickling solution and the immersion time are too high or too long, a large amount of damage to the surface of the steel sheet may occur. More specifically, pickling may be performed by immersing in pickling liquid for 5 to 120 seconds. The concentration of the pickling solution may be 5 to 30 wt%.

The following relationship between the projected amount of short balls (kg/(m2·min)) and the pickling solution immersion time (seconds) can be satisfied.

[thrown amount] / [immersion time] ≥ 0.5

If the value is less than 0.5, the bonding force of the insulating film may be weakened or surface defects may occur. More specifically, [thrown amount] / [immersion time] may be 0.5 to 2. More specifically, it may be 0.75 to 1.5.

Next, the hot-rolled sheet is cold-rolled to manufacture a cold-rolled sheet. Cold rolling is final rolling to a thickness of 0.15 mm to 0.65 mm. If necessary, secondary cold rolling may be performed after primary cold rolling and intermediate annealing, and the final reduction ratio may be in the range of 50 to 95%.

Next, the cold-rolled sheet is annealed. Cold-rolled sheet annealing is performed for 10 to 1000 seconds within a range of 700 to 900° C. so that the grain size in the cross section of the steel sheet is 10 to 50 μm. If the cold-rolled sheet annealing temperature is too low, the crystal grains are small and iron loss may be deteriorated. If the temperature is too high, grains may be coarsened and mechanical strength may be reduced. More specifically, it may be annealed in the range of 750 to 850 ℃.

After cold-rolled sheet annealing, most (95% or more) of the steel sheet processed by cold-rolling can be recrystallized.

Next, an insulating film can be formed after cold-rolled sheet annealing. The insulating coating may be treated with organic, inorganic, and organic/inorganic composite coatings, and may be treated with other insulating coatings. For example, it may be formed by applying an insulating film-forming composition containing 40 to 70% by weight of metal phosphate and 0.5 to 10% by weight of silica.

Next, a step of stress relief annealing is performed. The stress relief annealing step is performed at a temperature of 700° C. to 850° C. for 10 minutes to 300 minutes.

The motor core according to an embodiment of the present invention includes a stator formed by stacking a plurality of non-oriented electrical steel sheets, and the non-oriented electrical steel sheet contains, by weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3 %, Mn: 0.3 to 2.0%, and includes a steel sheet base material containing Fe and unavoidable impurities and an insulating film located on the steel plate base material, the steel plate base material satisfies the following formula 1, and the insulating film satisfies the following formula 2 do.

[Equation 1]

0.1 ≤ [Mn(1)] / [Mn(10)] ≤ 1.0

[Equation 2]

[Fe] ≥ ([Al] + 2[Mn] + [Mg]) / 10

(In Equation 1, [Mn(1)] is the Mn concentration (wt%) at a depth of 1 μm from the interface between the base material and the insulating film toward the inside of the base material, and [Mn(10)] is at a depth of 10 μm represents the Mn concentration of

In the case of a stator, since magnetic properties are more important than mechanical properties, magnetic properties can be improved through SRA after punching and lamination. Therefore, after SRA, the characteristics of non-oriented electrical steel sheet appear in the stator. Since the steel component of the non-oriented electrical steel sheet and the Mn diffusion and alloy components in the insulating film have been described in relation to the aforementioned non-oriented electrical steel sheet, duplicate descriptions will be omitted.

The motor core according to an embodiment of the present invention further includes a rotor formed by stacking a plurality of non-oriented electrical steel sheets, and the non-oriented electrical steel sheet is weight%, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, the balance Fe and unavoidable impurities, and an insulating film positioned on the steel sheet base material, and the steel sheet base material may have an average grain size of 5 to 50 μm.

In the case of a rotor, mechanical properties are more important than magnetic properties. Therefore, it is possible to omit the SRA process, which may deteriorate mechanical properties. Accordingly, the characteristics of the non-oriented electrical steel sheet before SRA are derived, and the steel sheet base material may have an average grain size of 5 to 50 μm. Since the steel components and average grain size of the non-oriented electrical steel sheet have been described in relation to the aforementioned non-oriented electrical steel sheet, overlapping descriptions will be omitted.

On the other hand, the stator and rotor are punched out in an approximate donut or disc shape. When the stator and the rotor are manufactured by punching the stator and the rotor from coils of separate non-oriented electrical steel sheets, the remaining punched parts are scrapped, which leads to an increase in process cost and a waste of resources and energy. When the stator and the rotor are manufactured by punching out the same coil, scrap processing can be minimized.

Accordingly, in one embodiment of the present invention, the non-oriented electrical steel sheets included in the stator and the rotor may be non-oriented electrical steel sheets derived from the same coil. In one embodiment of the present invention, the meaning derived from the same coil means that steel components such as Si, Al, and Mn in the non-directional included in the stator and the rotor are substantially the same. Specifically, it means that the difference in Si, Al and Mn contents between the stator and the rotor is 0.20% by weight or less. More specifically, it means that the difference in Si, Al and Mn content between the stator and the rotor is 0.10% by weight or less. More specifically, it means that the difference in Si, Al and Mn content between the stator and the rotor is 0.05% by weight or less. More specifically, it means that the difference in Si, Al and Mn contents between the stator and the rotor is 0.01% by weight or less. Components of the insulating film may also be substantially the same between the stator and the rotor.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only for exemplifying the present invention, and the present invention is not limited thereto.

Example 1

A slab composed of Tables 1 and 2 below and the balance of Fe and other unavoidably added impurities was prepared. The slab was heated to 1150° C., and hot finish rolling was performed at 850° C. to produce a hot-rolled sheet having a thickness of 2.3 mm. The hot-rolled hot-rolled sheet was annealed at 1100° C. for 4 minutes. Next, a steel shortball with an average diameter of 0.5 μm was blasted at the projection amount listed in Table 3 to remove scale, and pickled in a 20 wt% aqueous hydrochloric acid solution for the time listed in Table 3 below. Thereafter, the sheet was cold rolled to a thickness of 0.27 mm, and then cold-rolled sheet annealed at 800° C. for 5 minutes. The insulating film was formed to a thickness of 0.5 μm using an insulating film composition containing 50% by weight of Al phosphate and 5% by weight of silica.

Thereafter, annealing was performed at 825° C. for 1 hour to relieve stress. Through this, a finally stress-removed non-oriented electrical steel sheet was manufactured. The depth direction component was measured three times with a glow discharge spectrometer, and the average values of [Mn1] and [Mn10] are shown in Table 5 below according to the experimental conditions. Insulation film adhesion was measured by the Crosscut Test (ASTM D3359) method after stress relief annealing.

Iron loss and magnetic flux density were measured as averages in the rolling direction and in the vertical direction of rolling with a single sheet tester by cutting 5 specimens with a width of 60 mm × a length of 60 mm × the number of sheets for each specimen.

The strength was measured through a tensile test, and the standard of the tensile test piece was JIS13-A.

(wt%) Si Al Mn Cr Sn Sb One 2.4 1.1 0.6 0.015 0.01 0.05 2 2.9 0.9 0.9 0.020 0.01 0.04 3 3.3 0.7 1.2 0.025 0.02 0.06 4 3.5 0.5 1.5 0.030 0.02 0.05 5 4.0 0.3 1.8 0.035 0.02 0.04 6 3.8 1.2 1.7 0.045 0.03 0.02 7 3.5 0.8 1.1 0.055 0.06 0.03 8 1.8 1.3 0.3 0.010 0.01 0.06 9 7.0 0.4 0.5 0.055 0.06 0.01 10 3.1 0.08 1.5 0.030 0.02 0.05 11 3.9 1.5 1.8 0.035 0.02 0.04 12 3.2 0.6 0.2 0.035 0.02 0.04 13 3.8 0.9 2.3 0.025 0.02 0.06 14 3.4 1.2 1.7 0.045 0.03 0.02 15 3.5 1.0 1.4 0.500 0.03 0.01 16 3.6 1.0 1.4 0.500 0.03 0.01 17 3.7 1.0 1.4 0.500 0.03 0.01 18 2.0 1.1 0.6 0.015 0.01 0.05 19 2.5 0.9 0.9 0.020 0.01 0.04 20 3.0 0.7 1.2 0.025 0.02 0.06 21 3.5 0.5 1.5 0.030 0.02 0.05 22 4.0 1.2 1.7 0.045 0.03 0.02 23 4.2 1.0 1.4 0.500 0.03 0.01 24 3.4 0.7 1.2 0.025 0.02 0.06 25 3.5 0.5 1.5 0.030 0.02 0.05

(wt%) C N S Ti Nb V One 0.002 0.003 0.001 0.004 0.001 0.005 2 0.003 0.001 0.003 0.003 0.005 0.003 3 0.001 0.005 0.003 0.003 0.005 0.003 4 0.002 0.003 0.003 0.003 0.005 0.002 5 0.003 0.001 0.005 0.002 0.003 0.002 6 0.001 0.004 0.005 0.001 0.001 0.001 7 0.003 0.001 0.002 0.005 0.003 0.002 8 0.001 0.005 0.001 0.004 0.001 0.005 9 0.005 0.003 0.004 0.005 0.005 0.003 10 0.002 0.003 0.003 0.003 0.005 0.002 11 0.003 0.001 0.005 0.002 0.003 0.002 12 0.003 0.001 0.005 0.002 0.003 0.002 13 0.001 0.005 0.003 0.003 0.005 0.003 14 0.001 0.004 0.005 0.001 0.001 0.001 15 0.002 0.005 0.002 0.001 0.002 0.002 16 0.002 0.005 0.002 0.001 0.002 0.002 17 0.002 0.005 0.002 0.001 0.002 0.002 18 0.002 0.003 0.001 0.004 0.001 0.005 19 0.003 0.001 0.003 0.003 0.005 0.003 20 0.001 0.005 0.003 0.003 0.005 0.003 21 0.002 0.003 0.003 0.003 0.005 0.002 22 0.001 0.004 0.005 0.001 0.001 0.001 23 0.002 0.005 0.002 0.001 0.002 0.002 24 0.001 0.005 0.003 0.003 0.005 0.003 25 0.002 0.003 0.003 0.003 0.005 0.002

note Shortball throw amount/
immersion time Shortball throw amount
(kg/min ㎡) short ball throw time
(candle) immersion time
(candle) Mn1 Mn10 [Mn1]
/[Mn10] One 0.81 25 21 31 0.45 0.59 0.76 2 0.71 25 11 35 0.90 0.98 0.92 3 0.77 30 27 39 1.21 1.25 0.97 4 1.59 35 29 22 1.31 1.42 0.92 5 1.19 31 9 26 1.62 1.71 0.95 6 0.69 29 30 42 1.50 1.65 0.91 7 0.55 27 29 49 0.98 1.02 0.96 8 1.18 20 60 17 0.35 0.31 1.13 9 3.17 19 5 6 0.53 0.49 1.08 10 2.43 17 3 7 1.72 1.48 1.16 11 1.88 15 One 8 0.16 1.82 0.09 12 2.00 18 4 9 0.25 0.19 1.32 13 2.80 14 6 5 0.13 1.96 0.07 14 0.45 27 25 60 0.23 1.72 0.13 15 0.36 25 20 70 0.51 1.41 0.36 16 0.44 35 20 80 0.19 1.41 0.13 17 0.43 15 20 35 0.21 1.41 0.15 18 0.65 13 24 20 0.53 0.61 0.87 19 0.55 11 28 20 0.75 0.89 0.84 20 0.54 38 32 70 1.15 1.19 0.97 21 0.57 40 36 70 1.28 1.52 0.84 22 0.71 30 0.5 42 1.65 1.72 0.96 23 0.81 35 70 43 1.27 1.38 0.92 24 11.67 35 45 3 1.08 1.18 0.92 25 0.54 70 11 130 1.32 1.49 0.89

Insulation film note Fe Al Mn Mg (Al+2*Mn+Mg)/10 Expression 2 Satisfaction One 2.93 9.81 1.35 9.25 2.176 O 2 2.75 9.11 2.7 8.87 2.338 O 3 2.93 7.39 3.63 8.94 2.359 O 4 3.05 8.38 3.9 9.35 2.553 O 5 2.56 7.74 3.25 9.09 2.333 O 6 2.81 8.61 4.5 8.94 2.655 O 7 3.01 10.12 2.94 8.78 2.478 O 8 2.67 8.51 1.05 9.27 1.988 O 9 No cold rolling 10 2.88 6.23 5.16 9.1 2.565 O 11 2.86 9.25 5.36 8.9 2.887 X 12 2.64 8.86 0.75 8.93 1.929 O 13 1.25 8.17 6.6 8.85 3.022 X 14 1.85 11.11 0.69 8.64 2.113 X 15 1.68 8.35 1.53 8.62 2.003 X 16 1.98 10.82 0.57 8.79 2.075 X 17 1.67 6.88 0.63 8.85 1.699 X 18 2.38 7.06 2.25 8.93 2.049 O 19 2.72 8.12 2.94 8.74 2.274 O 20 3.13 9.23 6.23 9.26 3.095 O 21 2.92 8.87 5.38 8.64 2.827 O 22 3.00 9.12 5.85 8.76 2.958 O 23 2.76 11.04 3.55 9.23 2.737 O 24 2.85 9.01 4.05 8.79 2.59 O 25 3.05 9.43 6.38 8.21 3.04 O

Before stress relief annealing After stress relief annealing note magnetic flux density yield strength Magnetic flux density after heat treatment Iron loss after heat treatment W10/400 adhesion surface defects One 1.68 524 1.64 10.9 5B X 2 1.66 517 1.63 11.4 5B X 3 1.66 536 1.63 11.2 5B X 4 1.66 514 1.63 11 5B X 5 1.64 571 1.61 11.5 5B X 6 1.65 563 1.62 11.3 5B X 7 1.65 544 1.63 10.8 5B X 8 1.64 385 1.6 13.3 4B O 9 No cold rolling 10 1.63 420 1.59 12.2 3B O 11 1.64 472 1.6 12.1 3B O 12 1.63 476 1.6 11.9 4B O 13 1.61 510 1.57 12.3 4B O 14 1.64 542 1.59 13.2 3B O 15 1.63 535 1.6 12.8 4B O 16 1.63 533 1.59 12.2 4B O 17 1.62 548 1.58 11.9 3B O 18 1.67 483 1.63 11.7 5B X 19 1.66 495 1.63 11.6 5B X 20 1.67 519 1.64 11.7 5B X 21 1.66 523 1.62 11.4 5B X 22 1.65 537 1.63 11.9 5B X 23 1.65 557 1.62 11.4 5B X 24 1.66 546 1.61 12 5B X 25 1.67 534 1.63 11.5 5B X

As shown in Tables 1 to 5, steel No. 1 to 7 can confirm that the effect is excellent.

On the other hand, Kang No. In Nos. 8 to 13, the Si, Al, and Mn contents were not properly added, so that the magnetic flux density before and after stress relief annealing, the yield strength before stress relief annealing, and the iron loss, adhesion, and surface properties after stress relief annealing were inferior.

River No. In 14 to 17, the short ball projection amount / immersion time is small, Mn1 / Mn10 is high, or Equation 2 is not satisfied, so that the magnetic flux density before / after stress relief annealing, iron loss after stress relief annealing, adhesion, and surface characteristics are part of it. there is.

River No. 18 to 25 have relatively low Mn1/Mn10 and steel No. Compared to 1 to 7, it can be seen that the magnetic flux density before and after stress relief annealing, iron loss after stress relief annealing, adhesion, and surface properties are partially inferior.

The present invention is not limited to the examples and can be manufactured in various different forms, and those skilled in the art to which the present invention pertains may change other specific forms without changing the technical spirit or essential features of the present invention. It will be appreciated that this can be implemented. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

Claims (16)

By weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, and a steel sheet base material containing Fe and unavoidable impurities, and an insulating film located on the steel sheet base material,
After stress relief annealing, the base material of the steel sheet satisfies Equation 1 below, and the non-oriented electrical steel sheet satisfies Equation 2 below.
[Equation 1]
0.1 ≤ [Mn(1)] / [Mn(10)] ≤ 1.0
[Equation 2]
[Fe] ≥ ([Al] + 2[Mn] + [Mg]) / 10
(In Equation 1, [Mn(1)] is the Mn concentration (wt%) at a depth of 1 μm from the interface between the base material and the insulating film toward the inside of the base material, and [Mn(10)] is at a depth of 10 μm represents the Mn concentration of
In Equation 2, [Fe], [Al], [Mn], and [Mg] represent the contents (wt%) of Fe, Al, Mn, and Mg at the center of the insulation film thickness direction.) According to claim 1,
The base material of the steel plate further includes at least one of Cr: 0.2% or less (excluding 0%), Sn: 0.06% or less (excluding 0%), and Sb: 0.06% or less (excluding 0%). non-oriented electrical steel sheet. According to claim 1,
The steel sheet base material is a non-oriented electrical steel sheet further comprising 0.005% by weight or less of one or more of C, N, S, Ti, Nb, and V. According to claim 1,
The steel sheet base material contains at least one of Cu: 0.01 to 0.2 wt%, P: 0.100 wt% or less, B: 0.002 wt% or less, Mo: 0.01 wt% or less, Mg: 0.005 wt% or less, and Zr: 0.005 wt% or less. Non-oriented electrical steel sheet further comprising a. According to claim 1,
A non-oriented electrical steel sheet having an average grain size of 5 to 50 μm of the base material of the steel sheet. According to claim 1,
The coating amount of the insulating film is 500 to 1500mg / m ² Non-oriented electrical steel sheet. By weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, and the balance Fe and unavoidable impurities by hot rolling a slab to prepare a hot-rolled sheet;
removing scale present on the surface of the hot-rolled sheet;
manufacturing a cold-rolled sheet by cold-rolling the scale-removed hot-rolled sheet;
Cold-rolled sheet annealing of the cold-rolled sheet and
Forming an insulating film on the surface of the cold-rolled sheet,
The step of removing the scale is the step of removing the scale by projecting a short ball onto the steel plate, and
Including the step of pickling by immersion in pickling liquid,
A method for manufacturing a non-oriented electrical steel sheet that satisfies the following relationship between the shot amount of the short ball (kg / (m 2 min)) and the pickling solution immersion time (seconds).
[thrown amount] / [immersion time] ≥ 0.5 According to claim 7,
In the step of removing the scale, the step of removing the scale by projecting a short ball onto the steel plate in an amount of 15 kg / (m 2 min) to 35 kg / (m 2 min) and pickling is a non-directional electric immersion in pickling solution for 5 to 120 seconds Manufacturing method of steel sheet. According to claim 7,
The average particle size of the short ball is 0.3 to 0.8 mm, and a method for producing a non-oriented electrical steel sheet projected for 5 seconds to 30 seconds. According to claim 7,
The material of the short ball is a method of manufacturing a non-oriented electrical steel sheet of an Fe-based alloy. According to claim 7,
The cold-rolled sheet annealing step is a method of manufacturing a non-oriented electrical steel sheet annealed at a temperature of 700 to 900 ℃. According to claim 7,
Method for producing a non-oriented electrical steel sheet further comprising the step of annealing the hot-rolled sheet before the step of removing the scale. It includes a stator formed by stacking a plurality of non-oriented electrical steel sheets,
The non-oriented electrical steel sheet in the stator contains, by weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, and the remainder Fe and unavoidable impurities. Including an insulating film,
The motor core in which the base material of the steel plate satisfies Equation 1 below, and the insulating coating satisfies Equation 2 below.
[Equation 1]
0.1 ≤ [Mn(1)] / [Mn(10)] ≤ 1.0
[Equation 2]
[Fe] ≥ ([Al] + 2[Mn] + [Mg]) / 10
(In Equation 1, [Mn(1)] is the Mn concentration (wt%) at a depth of 1 μm from the interface between the base material and the insulating film toward the inside of the base material, and [Mn(10)] is at a depth of 10 μm represents the Mn concentration of
In Equation 2, [Fe], [Al], [Mn], and [Mg] represent the contents (wt%) of Fe, Al, Mn, and Mg at the center of the insulation film thickness direction.) According to claim 13,
Further comprising a rotor formed by stacking a plurality of non-oriented electrical steel sheets,
The non-oriented electrical steel sheet in the rotor contains, by weight, Si: 2.0 to 6.5%, Al: 0.1 to 1.3%, Mn: 0.3 to 2.0%, and the balance is Fe and unavoidable impurities, and is located on the steel sheet base material. Including an insulating film that
The motor core of the steel sheet base material having an average grain size of 5 to 50 μm. According to claim 14,
The motor core of claim 1, wherein the non-oriented electrical steel sheets included in the stator and the rotor are non-oriented electrical steel sheets derived from the same coil. According to claim 14,
A motor core wherein a difference in Si, Al, and Mn contents between the non-oriented electrical steel sheets included in the stator and the rotor is 0.20% by weight or less.