KR20240013557A - Non-oriented electrical steel sheet and method for manufacturing the same - Google Patents

Abstract

The present invention provides silicon (Si): 0.1 to 0.4% by weight, manganese (Mn): 0.2 to 0.5% by weight, aluminum (Al): more than 0 to 0.1% by weight, carbon (C): more than 0 to 0.003% by weight or less, phosphorus ( P): more than 0 and not more than 0.1% by weight, sulfur (S): more than 0 and not more than 0.002% by weight, nitrogen (N): more than 0 and not more than 0.003% by weight, titanium (Ti): more than 0 and not more than 0.003% by weight, and the remaining iron (Fe ) and other inevitable impurities, but the average grain size in the final microstructure is 80 to 100㎛, and provides a non-oriented electrical steel sheet that satisfies Equation 1 below.
Formula 1: 20 ≤ [Mn] × [average grain size] ≤ 50
(However, the [Mn] is the manganese content in weight%, and the [average grain size] is the average grain size in ㎛.)

Description

Non-oriented electrical steel sheet and method of manufacturing the same {NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a non-oriented electrical steel sheet and a method of manufacturing the same, and more specifically to a high-efficiency non-oriented electrical steel sheet and a method of manufacturing the same.

Electrical steel sheets can be divided into oriented electrical steel sheets and non-oriented electrical steel sheets depending on their magnetic properties. Oriented electrical steel sheet is manufactured to facilitate magnetization in the rolling direction of the steel sheet and has particularly excellent magnetic properties in the rolling direction, so it is mainly used as the iron core of large, small and medium-sized transformers that require low core loss and high magnetic permeability. . In contrast, non-oriented electrical steel sheets have uniform magnetic properties regardless of the direction of the steel sheet, so they are widely used as iron core materials for small electric motors, small power transformers, and stabilizers.

Republic of Korea Patent Publication No. 2015-0001467A

The technical problem to be achieved by the present invention is to provide a non-oriented electrical steel sheet with excellent high-frequency iron loss and a method of manufacturing the same.

However, these tasks are illustrative and do not limit the scope of the present invention.

The non-oriented electrical steel sheet according to one aspect of the present invention for solving the above problems includes silicon (Si): 0.1 to 0.4 wt%, manganese (Mn): 0.2 to 0.5 wt%, and aluminum (Al): 0 to 0.1 wt%. , Carbon (C): more than 0 and less than 0.003% by weight, phosphorus (P): more than 0 and less than 0.1% by weight, sulfur (S): more than 0 and less than 0.002% by weight, nitrogen (N): more than 0 and less than 0.003% by weight, titanium (Ti): It is a non-oriented electrical steel sheet containing more than 0 and less than 0.003% by weight and the remaining iron (Fe) and other inevitable impurities, and the average grain size in the final microstructure is 80 to 100㎛, satisfying Equation 1 below.

Formula 1: 20 ≤ [Mn] × [average grain size] ≤ 50

(However, the [Mn] is the manganese content in weight%, and the [average grain size] is the average grain size in ㎛.)

The thickness of the non-oriented electrical steel sheet is 0.1 to 0.3 mm, and the average iron loss (W _10/400 ) may be 40 to 50 W/kg.

In the non-oriented electrical steel sheet, hysteresis iron loss (W _10/400 ) may be 8 to 11 W/kg, and eddy current iron loss (W _10/400 ) may be 32 to 39 W/kg.

A method of manufacturing a non-oriented electrical steel sheet according to one aspect of the present invention to solve the above problem is (a) silicon (Si): 0.1 to 0.4 wt%, manganese (Mn): 0.2 to 0.5 wt%, aluminum (Al) : More than 0 0.1% by weight, Carbon (C): More than 0 but less than 0.003% by weight, Phosphorus (P): More than 0 but less than 0.1% by weight, Sulfur (S): More than 0 but less than 0.002% by weight, Nitrogen (N): More than 0 Providing a steel material containing 0.003 wt% or less, titanium (Ti): more than 0 and 0.003 wt% or less, and the remaining iron (Fe) and other inevitable impurities, but satisfying Equation 1 below; (b) hot rolling the steel; (c) cold rolling the hot rolled steel; and (d) annealing and heat treating the cold rolled steel.

Formula 1: 20 ≤ [Mn] × [average grain size] ≤ 50

(However, the [Mn] is the manganese content in weight%, and the [average grain size] is the average grain size in ㎛.)

In the method of manufacturing the non-oriented electrical steel sheet, step (b) includes reheating temperature (SRT): 1100 to 1250°C, finish rolling temperature (FDT): 800 to 1000°C, and coiling temperature (CT): 600 to 700. It can be performed under conditions of ℃.

In the method of manufacturing the non-oriented electrical steel sheet, step (d) may include annealing for 30 to 90 seconds at a temperature range of 900 to 1,100°C.

In the method of manufacturing the non-oriented electrical steel sheet, the steel sheet thickness after the hot rolling is 1.6 to 2.6 mm, the steel sheet thickness after the cold rolling is 0.1 to 0.3 mm, and the average iron loss (W _10/400 ) is 40 to 50 W/ It may be kg.

According to an embodiment of the present invention, a non-oriented electrical steel sheet with excellent high-frequency iron loss and a method for manufacturing the same can be provided.

Of course, the scope of the present invention is not limited by this effect.

1 is a flowchart showing a method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention.

A method for manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention will be described in detail. The terms described below are terms appropriately selected in consideration of their functions in the present invention, and definitions of these terms should be made based on the content throughout the present specification.

Generally, electrical steel is divided into oriented electrical steel and non-oriented electrical steel. Grain-oriented electrical steel sheets are mainly used in stationary equipment such as transformers, while non-oriented electrical steel sheets are mainly used in rotating equipment such as motors and generators. Recently, in response to global environmental issues, technology is rapidly changing from existing internal combustion engines to replacements such as hybrid vehicles (HEV), electric vehicles (EV), and hydrogen vehicles. The characteristics of electrical steel materials can be evaluated by magnetic flux density and iron loss.

Iron loss refers to the energy loss that occurs in the non-oriented electrical steel sheet, which is an iron core material, in the process of sequential energy conversion of electrical energy into magnetic energy and mechanical energy. Iron loss is composed of the sum of hysteresis iron loss and eddy current iron loss. Unlike hysteresis iron loss, eddy current iron loss increases as a percentage of total iron loss as the frequency increases. Eddy current core loss is divided into loss across the entire sheet and loss across grains.

The magnetic flux density is generally evaluated at B ₅₀ , and the core loss is generally evaluated at W _15/50 , but in cases where high frequency characteristics are required, such as in electric vehicles, the core loss is evaluated at W _10/400 . B ₅₀ represents the magnetic flux density at 5000A/m, W _15/50 represents the iron loss at 50Hz and 1.5T, and W _10/400 represents the iron loss at 400Hz and 1.0T.

In the case of some types of existing non-oriented electrical steel sheets, there is a group of steel types that place more importance on magnetic flux density than core loss. However, with the recent development of electronic products, iron loss efficiency at high frequencies has become more important, so the demand for products that must reduce high frequency iron loss is increasing even in electrical steel grades where magnetic flux density is more important. For example, development is underway to reduce high-frequency iron loss in non-oriented electrical steel sheets, which are general materials with a silicon content of 1.6% by weight or less.

1 is a flowchart showing a method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention.

Referring to Figure 1, a method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention includes providing a steel containing silicon (Si), manganese (Mn), and aluminum (Al) (S10); Hot rolling the steel (S20); Cold rolling the hot rolled steel (S40); and a step of annealing and heat treating the cold rolled steel (S50).

Meanwhile, the method of manufacturing a non-oriented electrical steel sheet according to a modified embodiment of the present invention optionally includes hot rolling annealing heat treatment of the hot rolled steel between the hot rolling step (S20) and the cold rolling step (S40). Step S30 may be further included.

Steel provision step (S10)

Steel materials used in the hot rolling process are steel materials for manufacturing non-oriented electrical steel sheets, for example, silicon (Si): 0.1 to 0.4 wt%, manganese (Mn): 0.2 to 0.5 wt%, aluminum (Al): More than 0 0.1 wt%, Carbon (C): More than 0 0.003 wt% or less, Phosphorus (P): More than 0 0.1 wt% or less, Sulfur (S): More than 0 0.002 wt% or less, Nitrogen (N): More than 0 0.003 wt% Weight% or less, titanium (Ti): greater than 0 and less than 0.003% by weight, and the remainder includes iron (Fe) and other unavoidable impurities.

Below, the role and content of exemplary composition components to which the method for manufacturing a non-oriented electrical steel sheet according to the technical idea of the present invention can be applied will be described.

Silicon (Si): 0.1 to 0.4% by weight

Silicon (Si) is a major added element that increases resistivity and lowers iron loss (eddy current loss). If the amount of silicon added is low, below 0.1% by weight, it becomes difficult to obtain the desired high-frequency low iron loss value, and as the amount added, the permeability and magnetic flux density decrease. Additionally, if the amount of silicon added exceeds 0.4% by weight, brittleness increases, making cold rolling difficult and productivity decreasing.

Manganese (Mn): 0.2 to 0.5% by weight

Manganese (Mn), along with silicon, increases resistivity and improves texture. If manganese is added in excess of 0.5% by weight, coarse MnS precipitates are formed and magnetic properties are deteriorated, such as reducing magnetic flux density. Furthermore, when the manganese content exceeds 0.5% by weight, the reduction in iron loss is small compared to the addition amount, but cold rolling properties are significantly reduced. Furthermore, if the manganese content is less than 0.2% by weight, fine MnS precipitates can be formed to suppress grain growth, so the composition range of manganese can be adjusted to 0.2 to 0.5% by weight.

Aluminum (Al): 0 to 0.1% by weight

Aluminum (Al) is a major added element that, along with silicon, increases resistivity and lowers iron loss (eddy current loss). Aluminum plays a role in reducing magnetic deviation by reducing magnetic anisotropy. Aluminum meets nitrogen and induces AlN precipitation. If the aluminum content does not exist, it is difficult to expect the above-mentioned effects, and fine nitrides may be formed, which may increase the variation in magnetic properties. If the aluminum content exceeds 0.1% by weight, cold rolling properties will deteriorate, and nitrides may occur. If formed excessively, the magnetic flux density is reduced and the magnetic properties are deteriorated.

Carbon (C): greater than 0 and less than or equal to 0.003% by weight

Carbon (C) is an element that increases iron loss by forming carbides such as TiC and NbC. The smaller the carbon, the more desirable it is, and it is limited to 0.003% by weight or less. If the carbon content exceeds 0.003% by weight, self-aging occurs and magnetic properties are reduced, and if the carbon content is less than 0.003% by weight, the self-aging phenomenon is suppressed.

Phosphorus (P): More than 0 and less than 0.1% by weight

Phosphorus (P) is a grain boundary segregation element that develops texture. If the phosphorus content exceeds 0.1% by weight, grain growth is suppressed due to the segregation effect, magnetic properties are deteriorated, and cold rolling properties are deteriorated.

Sulfur (S): greater than 0 and less than or equal to 0.002% by weight

Sulfur (S) increases iron loss by forming precipitates such as MnS and CuS, and suppresses grain growth, so its addition is limited to 0.002% by weight or less. If the sulfur content exceeds 0.002% by weight, the problem of increased iron loss occurs.

Nitrogen (N): greater than 0 and less than or equal to 0.003% by weight

Nitrogen (N) increases iron loss by forming precipitates such as AlN, Tin, and NbN, and suppresses grain growth, so its addition is limited to 0.003% by weight or less. If the nitrogen content exceeds 0.003% by weight, the problem of increased iron loss occurs.

Titanium (Ti): More than 0 and less than 0.003% by weight

Titanium (Ti) suppresses grain growth by forming fine precipitates such as TiC and TiN. The magnetic properties deteriorate as titanium is added, so the addition is limited to as low as possible and limited to 0.003% by weight or less. If the titanium content exceeds 0.003% by weight, the problem of magnetic properties deterioration occurs.

Hot rolling step (S20)

Steel having the above-described composition undergoes a hot rolling process. The step of hot rolling the steel (S20) is performed under the conditions of reheating temperature (SRT): 1100 to 1250°C, finish rolling temperature (FDT): 800 to 1000°C, and coiling temperature (CT): 600 to 700°C. It can be.

If the slab reheating temperature exceeds 1250°C, precipitates such as C, S, and N in the slab may be re-dissolved and fine precipitates may be generated in the subsequent rolling and annealing process, suppressing grain growth and deteriorating magnetism. If the slab reheating temperature is less than 1100°C, the rolling load increases and a problem of increased iron loss in the final product may occur.

After performing the step (S20) of hot rolling the steel, the thickness of the hot rolled sheet may be, for example, 1.6 to 2.6 mm. As the thickness of the hot-rolled sheet increases, the cold rolling reduction rate increases and the texture becomes inferior, so it is desirable to control the thickness to 2.6 mm or less.

The hot rolled steel may be coiled under conditions of coiling temperature (CT): 600 to 700°C. If the coiling temperature is less than 600°C, there is no annealing effect on the steel, so grain growth does not occur. If the coiling temperature is higher than 700°C, oxidation may increase during cooling, which may worsen pickling properties.

Cold rolling step (S40)

A step (S40) of cold rolling the hot rolled steel is performed. The reduction rate of cold rolling is 81 to 92%, and the thickness of the steel after cold rolling can be 0.1 to 0.3 mm. In order to provide rolling properties, warm rolling can be performed by raising the plate temperature to 100 to 200°C.

Annealing heat treatment step (S50)

The cold rolled steel may be annealed and heat treated. The annealing heat treatment is the ACL (Annealing and Coating Line) step of final annealing the cold rolled sheet and can be understood as cold rolled annealing treatment. The annealing heat treatment step (S50) is annealing under the conditions of temperature increase rate: 10°C/s or more, annealing temperature: 900 to 1100°C, holding time: 30 to 90 seconds, and cooling under the conditions of cooling rate: 30°C/s or more. It may include steps.

Annealing heat treatment is performed on the cold-rolled sheet obtained after cold rolling. The temperature that derives the optimal grain size is applied considering the improvement of iron loss and mechanical properties. In cold rolling annealing, heating is performed under mixed atmosphere conditions to prevent surface oxidation and nitriding. The surface condition becomes smoother through a mixed atmosphere of nitrogen and hydrogen. If the cold rolling annealing temperature is less than 900°C, the grain size may be fine and hysteresis loss may increase, and if the cold rolling annealing temperature exceeds 1100°C, the grain size may become coarse and eddy current loss may increase.

The average grain size in the final microstructure after the cold rolling annealing heat treatment may be 80 to 100 μm.

Meanwhile, after the final cold rolling annealing, a coating process may be performed to form an insulating coating layer. By forming an insulating coating layer, punchability can be improved and insulation properties can be secured. The thickness of the insulating coating layer formed on the top and bottom of the cold rolled material may be about 1 to 2 μm.

Meanwhile, the method of manufacturing a non-oriented electrical steel sheet according to a modified embodiment of the present invention optionally includes hot rolling annealing heat treatment of the hot rolled steel between the hot rolling step (S20) and the cold rolling step (S40). Step S30 may be further included. The hot rolling annealing heat treatment can be divided into a first annealing heat treatment, and the cold rolling annealing heat treatment can be divided into a second annealing heat treatment.

The hot-rolled annealing heat treatment is an APL (Annealing and Pickling Line) step of annealing and pickling a hot-rolled sheet and can be understood as a preliminary annealing treatment. The hot rolling annealing heat treatment step (S30) may include an annealing process in which annealing is started at a temperature of 900 to 1050°C after raising the temperature at a temperature increase rate of 10°C/s or more and maintained for 30 to 90 seconds. After annealing, the steel may be cooled at a cooling rate of 20° C./s or more. The step of pickling after cooling may be further included.

After hot rolling, a hot rolling annealing process can be performed to ensure microstructure uniformity and cold rolling properties. The hot rolling annealing temperature is adjusted at 900 to 1050°C to form a uniform microstructure with the stretched cast structure removed. If the first annealing temperature is too low, below 900°C, the stretched cast structure remaining after hot rolling may remain, causing microstructure unevenness and forming small crystal grains, which may act as an obstacle to cold rolling. On the other hand, if the hot-rolled annealing temperature is too high, exceeding 1050℃, it causes an imbalance in the texture of the final product and causes anisotropy in properties.

The non-oriented electrical steel sheet implemented by the above-described manufacturing method includes silicon (Si): 0.1 to 0.4% by weight, manganese (Mn): 0.2 to 0.5% by weight, aluminum (Al): 0.1% by weight exceeding 0, and carbon (C). : More than 0 and less than or equal to 0.003% by weight, Phosphorus (P): More than 0 and less than or equal to 0.1% by weight, Sulfur (S): More than 0 and less than or equal to 0.002% by weight, Nitrogen (N): More than 0 and less than or equal to 0.003% by weight, Titanium (Ti): 0 It is a non-oriented electrical steel sheet containing less than 0.003% by weight of iron (Fe) and other inevitable impurities, and the average grain size in the final microstructure is 80 to 100㎛, satisfying Equation 1 below.

Formula 1: 20 ≤ [Mn] × [average grain size] ≤ 50

(However, the [Mn] is the manganese content in weight%, and the [average grain size] is the average grain size in ㎛.)

The thickness of the electrical steel sheet is 0.1 to 0.3 mm, the average iron loss (W _10/400 ) is 40 to 50 W/kg, and among the average iron losses, the hysteresis iron loss (W _10/400 ) is 8 to 11 W/kg. And the eddy current iron loss (W _10/400 ) may be 32 to 39 W/kg.

Since the non-oriented electrical steel sheet of the above-described composition is a steel type focused on improving magnetic flux density, there is a problem in that the efficiency of high-frequency iron loss is low. The present invention provides a non-oriented electrical steel sheet and a manufacturing method thereof in which high-frequency iron loss is reduced by controlling the composition and grain size.

Experiment example

Below, preferred experimental examples are presented to aid understanding of the present invention. However, the following experimental examples are only intended to aid understanding of the present invention, and the present invention is not limited by the following experimental examples.

1. Composition of the Psalm

In this experimental example, specimens having the alloy element composition (unit: weight%) shown in Table 1 are provided.

Si Mn Al C P S N Ti Bal. 0.3 variable 0.002 0.0025 0.005 0.0014 0.0018 0.0011 Fe

The slab having the above composition was reheated to 1130°C and hot rolled at a finish rolling temperature (FDT) of 850°C to produce a hot rolled sheet with a thickness of 2.3 mm. The hot-rolled sheet was pre-annealed at 1000°C and then cold-rolled to a thickness of 0.3 mm. Non-oriented electrical steel sheets were manufactured by final annealing the cold rolled steel sheets at a temperature of 900 to 1100°C for 60 seconds.

2. Evaluation of process conditions and physical properties

Table 2 shows the manganese composition (unit: weight %), cold rolling annealing heat treatment temperature, and structure and physical property evaluation results of the electrical steel sheet of this experimental example. The final annealing atmosphere temperature was conducted in a mixed atmosphere of 30% hydrogen and 70% nitrogen. At this time, the temperature increase rate was 10°C/s and the cooling rate was 30°C/s.

Mn
(%) ACL
Annealing temperature
(℃) average
grain
size
(㎛) Mn (%) x
Crystal grain (㎛) average core loss
W _10/400
(W/kg) Record
Core loss W _10/400
(W/kg) eddy current
Core loss W _10/400
(W/kg) iron loss
Standard Deviation
(W/kg) Experimental Example 1 0.12 900 66.9 8.70 57.8 11.1 46.7 0.4 Experimental Example 2 0.17 900 64.1 10.90 60.1 10.6 49.5 0.6 Experimental Example 3 0.19 900 75.1 15 52.6 13.2 39.4 0.6 Experimental Example 4 0.4 950 81.0 32.4 47.6 9.1 38.5 0.5 Experimental Example 5 0.5 950 82.5 41.25 41.8 9.2 32.6 0.6 Experimental Example 6 0.35 950 83.3 29.05 43.9 9.9 34 0.7 Experimental Example 7 0.65 1000 115.9 75.335 51.6 7.7 43.9 0.4 Experimental Example 8 0.72 1050 130.7 94.104 55.9 6.9 49.0 0.5

Referring to Table 2, Experimental Examples 4 to 6 include silicon (Si): 0.1 to 0.4% by weight, manganese (Mn): 0.2 to 0.5% by weight, aluminum (Al): 0.1% by weight exceeding 0, and carbon (C ): more than 0 and less than 0.003% by weight, phosphorus (P): more than 0 and less than 0.1% by weight, sulfur (S): more than 0 and less than 0.002% by weight, nitrogen (N): more than 0 and less than 0.003% by weight, titanium (Ti): In steel that contains more than 0.003% by weight and the remaining iron (Fe) and other inevitable impurities, but satisfies Equation 1 (20 ≤ [Mn] × [average grain size] ≤ 50), in the temperature range of 900 to 1100°C When cold-rolled annealing heat treatment is applied for 30 to 90 seconds, the average grain size in the final microstructure satisfies 80 to 100㎛, and the average iron loss (W _10/400 ) is 40 to 50 W/ when the thickness of the electrical steel sheet is 0.3mm. kg, and the hysteresis iron loss (W _10/400 ) is 8 to 11 W/kg, and the eddy current iron loss (W _10/400 ) satisfies 32 to 39 W/kg.

On the other hand, Experimental Examples 1 to 3 were not satisfied as the manganese (Mn): fell below the range of 0.2 to 0.5% by weight, and the average grain size: fell below the range of 80 to 100㎛, so [Mn] × If the value of [average grain size] is less than 20 and the thickness of the electrical steel sheet is 0.3mm, the average iron loss (W _10/400 ) exceeds 50 W/kg, and the hysteresis iron loss (W _10/400 ) It can be confirmed that it exceeds 11W/kg, and the eddy current iron loss (W _10/400 ) exceeds 39W/kg.

In addition, Experimental Examples 7 to 8 were not satisfied as the manganese (Mn): exceeded the range of 0.2 to 0.5% by weight, and the average grain size: was not satisfied as it exceeded the range of 80 to 100㎛, [Mn] × When the value of [average grain size] exceeds 50 and the thickness of the electrical steel sheet is 0.3 mm, the average iron loss (W _10/400 ) exceeds 50 W/kg, and the eddy current iron loss (W _10/400 ) ) can be confirmed to exceed 39W/kg.

If the grain size is too small, the hysteresis iron loss becomes larger and the anomalous iron loss becomes smaller. Conversely, if the grain size is too large, the hysteresis iron loss becomes smaller and the anomalous iron loss becomes smaller. Accordingly, the grain size must be controlled within an appropriate range, and for this purpose, the grain size is controlled by the cold rolled annealing (ACL annealing) temperature.

Experimental Examples 1 to 3 are comparative examples and are similar to existing composition systems, with an average grain size of 60 to 80 ㎛ and an Mn content of less than 0.2% by weight. Accordingly, the average high-frequency iron loss, W _10/400 , is relatively high, and because the Mn content is low, the eddy current iron loss value is also high.

Experimental Examples 4 to 6 are examples, and the Mn content is higher than that of Experimental Examples 1 to 3, and the average grain size is controlled to 80 ㎛ or more. As a result, the eddy current iron loss was greatly reduced, and the high-frequency iron loss value was significantly reduced to 40~50 W/kg. The standard at this time is 20 ≤ Mn (wt%) x grain size (㎛) ≤ 50.

In Experimental Examples 7 to 8, the Mn content is higher than the standard 0.2 to 0.5%, and the average grain size is coarse at 100 ㎛ or more. As the grain size decreased, the hysteresis iron loss was relatively reduced, but in terms of eddy current iron loss, the anomalous eddy current iron loss actually increased. This is a comparative example in which high-frequency iron loss is not reduced because the effect of reducing eddy current iron loss due to the addition of Mn is offset. Additionally, excessively high Mn levels may cause magnetic deterioration due to the formation of inclusions/precipitates.

Although the above description focuses on the embodiments of the present invention, various changes and modifications can be made at the level of those skilled in the art. These changes and modifications can be said to belong to the present invention as long as they do not depart from the scope of the present invention. Therefore, the scope of rights of the present invention should be determined by the claims described below.

Claims (8)

Silicon (Si): 0.1 to 0.4% by weight, Manganese (Mn): 0.2 to 0.5% by weight, Aluminum (Al): more than 0 to 0.1% by weight, Carbon (C): more than 0 to 0.003% by weight or less, phosphorus (P): Exceeding 0 and not exceeding 0.1% by weight, Sulfur (S): exceeding 0 and not exceeding 0.002% by weight, Nitrogen (N): exceeding 0 and not exceeding 0.003% by weight, Titanium (Ti): exceeding 0 and not exceeding 0.003% by weight, and the remaining iron (Fe) and others It is a non-oriented electrical steel sheet containing inevitable impurities.
The average grain size in the final microstructure is 80 to 100㎛,
Characterized by satisfying the following equation 1,
Non-oriented electrical steel sheet.
Formula 1: 20 ≤ [Mn] × [average grain size] ≤ 50
(However, the [Mn] is the manganese content in weight%, and the [average grain size] is the average grain size in ㎛.) According to claim 1,
The thickness of the electrical steel sheet is 0.1 to 0.3 mm, and the average iron loss (W _10/400 ) is 40 to 50 W/kg,
Non-oriented electrical steel sheet. According to claim 3,
Hysteresis iron loss (W _10/400 ) is 8 to 11 W/kg, and eddy current iron loss (W _10/400 ) is 32 to 39 W/kg.
Non-oriented electrical steel sheet. (a) Silicon (Si): 0.1 to 0.4 wt%, Manganese (Mn): 0.2 to 0.5 wt%, Aluminum (Al): 0 to 0.1 wt%, Carbon (C): 0 to 0.003 wt% or less, phosphorus ( P): more than 0 and not more than 0.1% by weight, sulfur (S): more than 0 and not more than 0.002% by weight, nitrogen (N): more than 0 and not more than 0.003% by weight, titanium (Ti): more than 0 and not more than 0.003% by weight, and the remaining iron (Fe ) and other unavoidable impurities, but providing a steel that satisfies Equation 1 below;
(b) hot rolling the steel;
(c) cold rolling the hot rolled steel; and
(d) annealing heat treatment of the cold rolled steel; including,
Method for manufacturing non-oriented electrical steel sheet.
Formula 1: 20 ≤ [Mn] × [average grain size] ≤ 50
(However, the [Mn] is the manganese content in weight%, and the [average grain size] is the average grain size in ㎛.) According to claim 4,
Step (b) is performed under the conditions of reheating temperature (SRT): 1100 to 1250°C, finish rolling temperature (FDT): 800 to 1000°C, and coiling temperature (CT): 600 to 700°C.
Method for manufacturing non-oriented electrical steel sheet. According to claim 5,
Step (d) includes annealing for 30 to 90 seconds at a temperature range of 900 to 1100°C.
Method for manufacturing non-oriented electrical steel sheet. According to claim 5,
The average grain size in the final microstructure after step (d) is 80 to 100 ㎛,
Method for manufacturing non-oriented electrical steel sheet. According to claim 6,
The thickness of the steel sheet after the hot rolling is 1.6 to 2.6 mm, the thickness of the steel sheet after the cold rolling is 0.1 to 0.3 mm, and the average iron loss (W _10/400 ) is 40 to 50 W/kg,
Method for manufacturing non-oriented electrical steel sheet.