WO2010018906A1

WO2010018906A1 - Steel sheet for enamelling, and a production method therefor

Info

Publication number: WO2010018906A1
Application number: PCT/KR2009/000901
Authority: WO
Inventors: 윤정봉; 조항식; 박수범; 김우성
Original assignee: 주식회사 포스코
Priority date: 2008-08-14
Filing date: 2009-02-25
Publication date: 2010-02-18
Also published as: KR20100021274A; JP2011530658A; CN102124132B; JP5699076B2; CN102124132A

Abstract

The present invention provides a steel sheet for enamelling which comprises, on a percent by weight basis, more than 0 and less than 0.005% carbon, 0.2-1.0% manganese, 0.04-0.08% sulphur, 0.005-0.02% phosphorus, 0.01-0.1% aluminium, 0.06-0.1% titanium and more than 0 and less than 0.003% nitrogen, and a balance of iron and unavoidable impurities, and in which there is a titanium sulphide or (titanium / manganese) sulphide precipitate having a size of 0.01-0.4 mm in an amount of at least 3x108 particles per cm2.

Description

Enamel steel plate and its manufacturing method

The present invention relates to a steel sheet for enamel. More specifically, the present invention relates to an enameled steel sheet excellent in formability without surface defects occurring and a manufacturing method thereof.

Enameled steel sheet is used for home appliances, chemical appliances, kitchen appliances, sanitary appliances and interior and exterior materials of buildings.

Enameled steel sheet includes hot rolled steel sheet or cold rolled steel sheet, but cold rolled steel sheet is mainly used in fields requiring high functionality and high processability. Examples of enameled steel sheets include rimmed steel, OCA steel (open coil aluminum steel), titanium-added steel, and high oxygen steel. High oxygen steel is a steel containing a large amount of oxygen in the limped steel. Increasing the oxygen content in the steel, like high-oxygen steel, can prevent fishscale, one of the defects of enamel steel sheet.

Fish scale refers to a phenomenon in which hydrogen gas condensed inside a river is released between the surface of the river and the enamel layer and lifts the surface of the enamel layer like fish scales. In the process of manufacturing the enamel steel sheet, fish scale is to release hydrogen dissolved in the steel to the surface of the steel in a cooled state. However, since the enamel layer on the steel surface is already hardened, hydrogen is not released to the outside, and thus a fish scale phenomenon occurs.

Thus, since fish scale is caused by hydrogen, it is necessary to make a place in the river where hydrogen can be adsorbed in order to prevent this defect from occurring. Such hydrogen adsorption sites may be micro-voids, inclusions, precipitates, dislocations, grain boundaries, and the like.

Limed steels have a high oxygen content, so large amounts of inclusions can be produced to prevent the occurrence of fish scales. However, since rimd steel can only be manufactured by ingot casting, productivity is low. Therefore, there is a need for an enameled steel that can be produced by high productivity continuous casting.

Titanium (Ti) -added steel can be produced by continuous casting. However, this enameled steel has to add a lot of expensive titanium, which increases the manufacturing cost. In addition, when the titanium-added steel is continuously cast, the added titanium blocks the nozzle, and other defects occur on the surface of the steel sheet due to the large amount of inclusions. In addition, in the case of titanium-added steel, the recrystallization temperature of the steel is increased due to the added titanium, and annealing is required at the temperature, thereby increasing the production cost of the product.

Most of the enameled steels listed above undergo decarburization annealing or phase annealing in order to prevent fish scale and improve formability. However, these processes are expensive due to the cost and time of annealing.

On the other hand, high oxygen strength can be made by continuous casting. However, high-oxygen steels have high oxygen content, so refractory is melted during continuous casting, resulting in low productivity.

The present invention provides an enamel steel sheet which can be made by continuous casting, has high productivity, has no surface defects and is excellent in formability.

Enamel steel sheet according to an embodiment of the present invention, in weight% C: greater than 0 and less than 0.005%, Mn: 0.2-1.0%, S: 0.04 ~ 0.08%, P: 0.005-0.02%, Al; 0.01-0.1 %, Ti; 0.06-0.1%, greater than N: 0, containing less than 0.003% and containing the remaining Fe and other unavoidable impurities, TiS or (Ti, Mn) S precipitates of 0.01-0.4 μm, per cm 2 3X10 can be ⁸ or more.

In such an enamel steel sheet, an L value defined as L = ((Ti / 48-N / 14-C / 12) + Mn / 58) / (S / 32) may be 2 to 10.

In this enamel steel sheet, the F value defined by F = (Ti / 48-N / 14-C / 12-S / 32) / (N / 14 + C / 12) may be greater than 0 and 5 or less.

Method for producing an enameled steel sheet according to an embodiment of the present invention, i) by weight% C: greater than 0 and less than 0.005%, Mn: 0.2-1.0%, S: 0.04 ~ 0.08%, P: 0.005-0.02%, Preparing a slab comprising Al; 0.01-0.1%, Ti; 0.06-0.1%, N: 0 and less than 0.003% and containing the remaining Fe and other unavoidable impurities; Ii) heating the slab to 1200 ° C. or higher; Iii) manufacturing the hot rolled steel sheet by rough rolling the heated slab and then finishing rolling at a temperature of Ar3 or higher; And iii) a winding step of winding the hot rolled steel sheet at 550 to 750 ° C.

The method for manufacturing the enamel steel sheet may further include the step of cold rolling the hot rolled steel sheet at 50 to 90% of a rolling reduction rate after the winding step to manufacture a cold rolled steel sheet.

In addition, the method for producing an enamel steel sheet may further include a step of continuously annealing the cold rolled steel sheet at a temperature of 700 ° C. or more for 20 seconds after the step of manufacturing the cold rolled steel sheet.

And the slab for producing the enamel steel sheet has an L value defined by L = ((Ti / 48-N / 14-C / 12) + Mn / 58) / (S / 32) is 2 ~ 10, F = The F value defined by (Ti / 48-N / 14-C / 12-S / 32) / (N / 14 + C / 12) may be greater than zero and less than or equal to five.

In addition, the enamel steel sheet thus prepared may have a TiS or (Ti, Mn) S precipitates of 0.01 to 0.4 μm, and 3 × ^{10 8} or more per cm 2.

In the steel sheet for enamel according to an embodiment of the present invention, since TiS or (Ti, Mn) S precipitates are uniformly dispersed, hydrogen may be adsorbed to prevent generation of fish scale.

Enamel steel sheet according to an embodiment of the present invention can properly control the correlation between the titanium, nitrogen, carbon, manganese and sulfur content defined by the L value, it is possible to prevent the occurrence of surface defects due to red light brittleness.

The steel sheet for enamel according to an embodiment of the present invention can improve the formability during processing by appropriately controlling the correlation of titanium, nitrogen, carbon and sulfur defined by the F value.

According to an embodiment of the present invention it can be provided by continuous casting, high productivity, there is no surface defects and excellent moldability can provide an enamel steel sheet.

Hereinafter, embodiments of the enamel steel sheet according to the present invention and a manufacturing method thereof will be described in detail, but the present invention is not limited to the following examples. Therefore, those skilled in the art may implement the present invention in various other forms without departing from the technical spirit of the present invention.

In the present invention, the content of component elements means all weight percent unless otherwise specified.

Hereinafter, the steel sheet for enamel according to the embodiment of the present invention will be described in detail.

Enamel steel sheet according to an embodiment of the present invention by weight% C: greater than 0 and less than 0.005%, Mn: 0.2-1.0%, S: 0.04 ~ 0.08%, P: 0.005-0.02%, Al; 0.01-0.1 %, Ti; 0.06-0.1%, greater than N: 0 and less than 0.003% and the remaining Fe and other unavoidable impurities.

And the steel sheet for enamel according to an embodiment of the present invention is L value of 2 to 10. Where L value is defined by the following equation (1).

L = ((Ti / 48-N / 14-C / 12) + Mn / 58) / (S / 32) (1)

In addition, in the steel sheet for enamel according to an embodiment of the present invention, the F value is 0 to 5. The F value is defined by the following equation (2).

F = (Ti / 48-N / 14-C / 12-S / 32) / (N / 14 + C / 12) (2)

And the steel sheet for enamel according to an embodiment of the present invention has the size of TiS or (Ti, Mn) S precipitates of 0.01 ~ 0.4㎛, and has 3X10 ⁸ or more per cm 2.

Hereinafter, the reason for limiting the component elements in the enamel steel sheet according to an embodiment of the present invention.

Carbon (C) is greater than zero and less than 0.005%. If the carbon is 0.005% or more, the amount of solid solution carbon in the steel increases. When the amount of solid solution carbon increases, the annealing prevents the development of the aggregate structure, resulting in low moldability and aging. Therefore, if the steel sheet for enamel is produced and then left for a long time, plastic processing is likely to cause surface defects such as stretcher strain. Therefore, the upper limit of carbon is limited to 0.005%.

Manganese (Mn) is 0.2-1.0%. Manganese is combined with sulfur dissolved in the river to precipitate as manganese sulfide. Precipitated manganese sulfide prevents hot shortness. However, in one embodiment of the present invention, since titanium is added, titanium sulfide is precipitated earlier than manganese sulfide, and the first precipitated titanium sulfide can also prevent red brittleness. If the titanium and manganese contained in the steel is low, red brittleness may occur. That is, in one embodiment of the present invention, when the content of manganese is 0.2% or less, there is a high possibility that red light brittleness occurs. Therefore, the content of manganese is made 0.2% or more. On the other hand, when manganese content is 1.0% or more, moldability will become low at the time of processing. Therefore, the content of manganese is made 1.0% or less.

Sulfur (S) is generally known as an element that degrades the physical properties of steel. However, in one embodiment of the present invention, sulfur combines with titanium to form fine titanium sulfide. The formed titanium sulfide absorbs and stores hydrogen from the enameling process, thus preventing fishscale defects. If the sulfur content is less than 0.04%, less titanium sulfide is produced, so it is not possible to occlude a lot of hydrogen, so fish scale is likely to occur. Therefore, the content of sulfur is limited to 0.04% or more. On the other hand, when the sulfur content is 0.08% or more, the ductility of the steel sheet is greatly lowered, and red brittleness by sulfur is likely to occur. Therefore, the sulfur content is limited to 0.08% or less.

Phosphorus (P), like sulfur (S), is known as an element that inhibits the properties of steel. However, in one embodiment of the present invention, when titanium is added, Ti (Fe, P) precipitates are precipitated and the precipitates prevent fish scales from occurring. Therefore, in the embodiment of the present invention, an appropriate amount of phosphorus is added. If the content of phosphorus is 0.005% or less, Ti (Fe, P) precipitates are small and hydrogen cannot be occluded much. Therefore, phosphorus is added at 0.005% or more. On the other hand, when phosphorus is added 0.02% or more, moldability worsens when processing. Therefore, the upper limit of phosphorus content is made into 0.02%.

Aluminum (Al) is a deoxidizer. Aluminum suppresses the formation of oxides in steel and increases ductility. When the content of aluminum is 0.01% or less, a lot of oxides are generated in the steel, resulting in poor ductility. Therefore, the lower limit of the amount of aluminum added is made 0.01%. On the other hand, when 0.1% or more of aluminum is added, the aluminum oxide remains in steel or on the surface, so that ductility deteriorates or surface defects are likely to occur. Therefore, the upper limit of the amount of aluminum added is limited to 0.1%.

Titanium (Ti) combines with sulfur (S) and phosphorus (P) to produce titanium sulfides and Ti (Fe, P) precipitates. These precipitates prevent fish scales. When the content of titanium is made 0.06% or less, there is a high possibility that fish scale is generated due to the small amount of titanium-based precipitates. Therefore, the lower limit of the amount of titanium added is 0.06%. On the other hand, when there is much content of titanium, a bubble defect is likely to arise and enamel adhesion is low. Therefore, the upper limit of the amount of titanium addition is made into 0.1%.

The more nitrogen (N) is added, the worse the formability of the steel and the higher the possibility of bubble defects. Therefore, the upper limit of the amount of nitrogen addition is limited to 0.003%.

In one embodiment of the present invention, the amount of titanium sulfide (TiS) precipitate which is a hydrogen adsorption site is appropriately adjusted. The amount of titanium sulfide deposited is correlated with the titanium content. In addition, when the titanium content is high, defects occur on the surface of the steel sheet or the enamel adhesion is poor. On the other hand, if the content of titanium is small, less precipitates are generated, and fish scales are more likely to occur, and when processing, the moldability is lowered, or the probability of surface defects due to redness brittle is increased. Therefore, the relationship between titanium, nitrogen, carbon, manganese and sulfur content in the enamel steel sheet according to an embodiment of the present invention should be properly controlled. The correlation between these elements is defined as L value {L = ((Ti / 48-N / 14-C / 12) + Mn / 58) / (S / 32)} as in the formula (1).

The L value is correlated with the occurrence of surface defects due to red light brittleness. If L is less than 2, there is a high probability of surface defects. Therefore, the lower limit of the L value is set to 2. On the other hand, when L value is larger than 10, enamel adhesion worsens. Therefore, the upper limit of L value shall be 10.

And the relationship between titanium, nitrogen, carbon, and sulfur in the enamel steel sheet according to an embodiment of the present invention is related to the formability when processing. The correlation between these elements is defined as F value {F = (Ti / 48-N / 14-C / 12-S / 32) / (N / 14 + C / 12)} as in the formula (2).

If the F value is less than 0, the moldability is too low, so defects are likely to occur during machining. Therefore, the lower limit of the F value is 0. If the F value is 5 or more, the probability of bubble defects is high. Therefore, the upper limit of the F value is set to 5.

In the steel sheet for enamel according to an embodiment of the present invention, in order to prevent fish scale, the size and number of TiS or (Ti, Mn) S precipitates are limited. This is because the place where hydrogen can be occluded in the enamel steel sheet is a fine pore generated at the interface between the precipitate and the matrix steel sheet or cold rolling.

The reason for limiting the size of the precipitate to 0.01 ~ 0.4㎛ is as follows. If the size of the precipitate is smaller than 0.01 μm, micropores are made too small when cold rolling. If the size of the micropores is too small, it is impossible to occlude much hydrogen. If the size of the precipitate is larger than 0.4 mu m, the area ratio between the interface of the precipitate and the base metal becomes too small. If the area ratio between the precipitate and the base metal interface is too small, it is difficult to prevent fish scale.

And the number of precipitates in the enamel steel sheet according to an embodiment of the present invention is limited to 3X10 ⁸ / cm 2 or more. When the number of precipitates is less than 3 × ^{10 8} / cm 2, it is difficult to prevent fish scale.

Hereinafter, a method of manufacturing an enamel steel sheet according to an embodiment of the present invention.

First by weight C: greater than 0 and less than 0.005%, Mn: 0.2-1.0%, S: 0.04-0.08%, P: 0.005-0.02%, Al; 0.01-0.1%, Ti; 0.06-0.1%, N: Slabs containing greater than 0 and less than 0.003% and the remaining Fe and other unavoidable impurities are prepared.

Next, the produced slab is heated to 1200 ° C. or higher. The reheated slab is rough rolled and then finish rolled at a temperature above Ar3 to produce a hot rolled steel sheet.

The prepared hot rolled steel sheet is wound at 550 to 750 ° C. The wound hot rolled steel sheet is pickled to remove the oxide film on the surface of the steel sheet and then cold rolled to produce a cold rolled steel sheet. When cold rolling, the reduction ratio is 50 to 90%. Cold-rolled steel sheet is continuously annealed for 20 seconds or more at 700 degreeC or more.

The reason for limiting the temperature for heating the slab to 1200 ℃ or more in the manufacturing method of the enamel steel sheet according to an embodiment of the present invention is as follows.

If the slab is heated at a temperature lower than 1200 ° C, the TiS or (Ti, Mn) S precipitates become too large in the steelmaking process. If the precipitate is too large, the grain boundary area between the precipitate and the base metal is reduced. On the other hand, when the slab is heated at 1200 ° C. or higher, the precipitate is re-dissolved to a suitable size, thereby increasing the grain boundary area between the precipitate and the base metal. Therefore, fish scale can be prevented.

In the manufacturing method of the enamel steel sheet according to an embodiment of the present invention, the reason for limiting the temperature for finishing hot rolling to Ar3 or more is as follows. This is because when finish hot rolling is carried out at a temperature of Ar3 or lower, crystal grains formed by hot rolling are formed, thereby decreasing the formability of the annealing plate.

And the reason for limiting the coiling temperature to less than 700 ℃ when hot rolling is as follows. If the coiling temperature is 700 ° C or higher, the precipitate is too large to prevent the fish scale because the grain boundary area between the precipitate and the base metal is small. Therefore, the upper limit of a coiling temperature shall be 700 degreeC. On the other hand, when the coiling temperature is 550 ° C. or less, the crystal grains by hot rolling become too small and the moldability deteriorates. Therefore, the minimum of winding temperature shall be 550 degreeC.

If the cold reduction rate is too low during cold rolling, the recrystallized texture does not develop well, resulting in poor formability. Conversely, if the cold reduction rate is too high, the ductility is lowered. Therefore, the cold reduction rate is limited to 50 to 90%.

Continuous annealing produces ductility and formability in the cold rolled steel sheet. Continuous annealing at 700 ° C. or lower does not result in recrystallization and thus does not produce ductility and formability. Therefore, the lower limit of the temperature for continuous annealing is set at 700 ° C. On the other hand, even if the time of continuous annealing is too short, recrystallization is not completed and ductility and moldability do not occur. Therefore, continuous annealing is performed for 20 seconds or more.

EXAMPLE

Steel ingots having the composition shown in Table 1 were prepared.

Table 1

division	C	Mn	P	S	Al	N	Ti	L	F
Inventive Steel 1	0.0013	0.32	0.011	0.055	0.035	0.0021	0.078	4.01	1.96
Inventive Steel 2	0.0016	0.46	0.009	0.049	0.032	0.0025	0.087	6.16	2.36
Invention Steel 3	0.0021	0.58	0.012	0.055	0.04	0.0018	0.059	6.36	0.22
Inventive Steel 4	0.0012	0.29	0.015	0.071	0.042	0.0017	0.092	3.02	2.65
Comparative Steel 1	0.0019	0.11	0.015	0.075	0.053	0.0024	0.054	1.15	-1.14
Comparative Steel 2	0.0028	0.42	0.009	0.093	0.043	0.0018	0.045	2.69	-2.42
Comparative Steel 3	0.0018	0.45	0.012	0.032	0.042	0.0048	0.072	8.77	1.03
Comparative Steel 4	0.0024	0.12	0.009	0.022	0.036	0.0073	0.12	5.60	1.99

In Table 1, the content of the component elements is in weight%, and the L value and the F value for each specimen are shown together.

A steel ingot having a composition as shown in Table 1 was maintained in a 1250 ° C. heating furnace for 1 hour, and then hot rolled to prepare a hot rolled steel sheet. Finish hot rolling was performed at 900 ° C. and wound up at 650 ° C. After hot rolling, the final thickness of the steel sheet was 3.2 mm. The hot rolled steel sheet thus prepared was pickled to remove the surface oxide film, and then cold rolled to prepare a cold rolled steel sheet. At this time, the cold reduction ratio was 75%, and the thickness of the steel sheet after cold rolling was 0.8 mm.

Using a cold rolled steel sheet, an enameled specimen for investigating the properties of enamel and a tensile specimen for investigating mechanical properties were prepared. The enameled and tensile specimens were annealed continuously.

Here, the enameled specimen was cut into 70mm X 150mm, and the tensile specimen was processed into a standard specimen according to ASTM E-8 standard.

Continuous annealing was performed at 830 ° C. After annealing was completed, the yield strength, tensile strength, elongation, and plastic anisotropy index (r _m ) of the tensile specimens were measured with a tensile tester (INSTRON, Model 6025).

Plastic anisotropy index (r _m ) shows moldability. When the tensile specimens were taken in the rolling direction, the right angle to the rolling direction, and in the direction of 45 ° to the rolling direction, respectively, and were stretched at 15%, the shrinkage ratio in the width direction and the thickness direction, that is, r = ln (w _f -w ₀ ) / ln ( t _f / t ₀ ) was measured to derive the plastic anisotropy index. The derived values were r ₀ , r ₄₅ and r ₉₀ , and r _m was r _m = (r ₀ + 2r ₄₅ + r ₉₀ ) / 4.

The enameled specimens were completely degreased, dried with glaze, and dried at 200 ° C. for 10 minutes to completely remove moisture. The dried specimens were maintained at 830 ° C. for 7 minutes, and then cooled to room temperature. After the lower enamel treatment was completed, the specimen was coated with an oil glaze and dried at 200 ° C. for 10 minutes to completely remove moisture. The dried specimen was held at 800 ° C. for 7 minutes, and then cooled in air. At this time, the atmosphere of the kiln was a harsh condition where fish scale was most likely to occur at a dew point temperature of 30 ° C. The enameled specimens were kept in a 200 ° C. holding furnace for 20 hours to generate fish scale and then visually examined the number of fish scales generated.

The enamel adhesion evaluation was performed using the adhesion index. The adhesion index was measured using an adhesion test device (a test device according to ASTM C313-78 standard).

Table 2 below shows the mechanical properties, enamel characteristics, and size and number of precipitates of the inventive and comparative steels, respectively.

TABLE 2

division	YS (MPa)	TS (MPa)	El. (%)	rm	Material defect	Bubble defect	Fish Scale Generation Count	Enamel adhesion index	Precipitate size (㎛)	Precipitate number (pieces / ㎠)
Inventive Steel 1	196	301	48	1.98	Good	Good	0	98%	0.21	5.5 × 10 ⁸
Inventive Steel 2	205	313	48	2.04	Good	Good	0	95%	0.27	4.8 × 10 ⁸
Invention Steel 3	203	322	47	1.93	Good	Good	0	97%	0.18	6.7 × 10 ⁸
Inventive Steel 4	192	304	49	1.97	Good	Good	0	95%	0.26	6.5 × 10 ⁸
Comparative Steel 1	207	325	44	1.65	Occur	Good	21	98%	0.007	0.8 × 10 ⁸
Comparative Steel 2	212	329	43	1.72	Good	Good	42	97%	0.006	0.54 × 10 ⁸
Comparative Steel 3	201	310	46	1.89	Good	Occur	38	95%	0.018	0.7 × 10 ⁸
Comparative Steel 4	172	292	48	1.93	Good	Occur	2	85%	0.64	4.5 × 10 ⁸

In Table 2, the inventive steels 1 to 4 have good mechanical properties because the r _m value is 1.5 or more and the elongation is 45% or more. In addition, the inventive steels 1 to 4 can be seen that the fish scale can be prevented even in the harsh conditions because the number and size of the precipitate falls within the limit of the present invention.

In addition, the inventive steels 1 to 4 have high enamel adhesion indexes of 95% or more, indicating good adhesion.

On the other hand, referring to Table 1, the L value of Comparative Steel 1 was 1.44, which is smaller than 2.0, and a defect occurred on the surface of Comparative Steel 1. In addition, the F value of the comparative steel 1 is -1.14, which is smaller than zero. In addition, referring to Table 2, the r _m value of Comparative Steel 1 is 1.65.

Therefore, using comparative steel 1, machining cracks are more likely to occur when making parts with complicated shapes or requiring deep soiling. Comparative steel 1 also had 21 small fish scale defects due to small precipitates and low number of titanium.

Comparative steel 2 had an L value of 2.69 and no defects on the surface. However, since the F value of Comparative Steel 2 is negative and the r _m value is small, there is a high possibility of cracking when forming. In addition, Comparative Steel 2 had a small amount of titanium, a small precipitate and a small number, resulting in 42 fish scales.

L value and F value of the comparative steel 3 were included in the scope of the present invention, and the surface defect did not generate | occur | produce. In addition, the r _m value is good at 1.89. However, Comparative Steel 3 contained more nitrogen than the inventive steel, so bubble defects occurred after enameling. Comparative steel 3 also contains less sulfur and the size of precipitates is within the range defined by the present invention. However, the number of precipitates was small and fish scale occurred.

L value and F value of the comparative steel 4 were included in the scope of the present invention, and the surface defect did not generate | occur | produce. In addition, since the r _m value is large, moldability may be good. However, Comparative Steel 4 contained less sulfur. And precipitates were outside the scope of the present invention and the number of precipitates was also small. In addition, fish scale occurred in Comparative Steel 4. On the other hand, Comparative Steel 4 contained a large amount of nitrogen bubble defects after the enamel treatment. In addition, Comparative Steel 4 contained a large amount of titanium and had low enamel adhesion of 85%.

As described above, the steel sheet for enamel and its manufacturing method have been described with reference to the preferred embodiments of the present invention, but a person skilled in the art does not depart from the spirit and scope of the present invention described in the claims below. It will be understood that various modifications and variations can be made in the present invention.

Claims

% By weight C: greater than 0 and less than 0.005%, Mn: 0.2-1.0%, S: 0.04-0.08%, P: 0.005-0.02%, Al; 0.01-0.1%, Ti; 0.06-0.1%, N: 0 Greater than 0.003% and containing the remaining Fe and other unavoidable impurities,

An enamel steel sheet having a size of TiS or (Ti, Mn) S precipitates of 0.01 to 0.4 µm, with 3 × 10 8 or more per cm 2.
The method of claim 1,

The enamel steel sheet is an enamel steel sheet having an L value of 2 to 10 defined by L = ((Ti / 48-N / 14-C / 12) + Mn / 58) / (S / 32).
The method of claim 2,

The enamel steel sheet is an enamel steel sheet having an F value greater than 0 and less than or equal to 5 defined by F = (Ti / 48-N / 14-C / 12-S / 32) / (N / 14 + C / 12).
% By weight C: greater than 0 and less than 0.005%, Mn: 0.2-1.0%, S: 0.04-0.08%, P: 0.005-0.02%, Al; 0.01-0.1%, Ti; 0.06-0.1%, N: 0 Preparing a slab that is greater than 0.003% and consists of the remaining Fe and inevitable impurities;

Heating the slab to at least 1200 ° C .;

The heated slab is roughly rolled and then finish rolled at a temperature of Ar3 or higher to produce a hot rolled steel sheet and

Winding step of winding the hot rolled steel sheet at 550 ~ 750 ℃

Method for producing a steel sheet for enamel comprising a.
The method of claim 4, wherein

After the winding step, by cold rolling at a reduction ratio of 50 to 90% further comprising the step of manufacturing a cold rolled steel sheet.
The method of claim 5,

Method for producing an enameled steel sheet further comprising the step of continuously annealing the cold rolled steel sheet at a temperature of 700 ℃ or more for 20 seconds or more.
The method according to any one of claims 4 to 6,

The slab has an L value of 2 to 10 defined by L = ((Ti / 48-N / 14-C / 12) + Mn / 58) / (S / 32), and F = (Ti / 48-N / The manufacturing method of the enameled steel plate whose F value defined by 14-C / 12-S / 32) / (N / 14 + C / 12) is larger than 0 and 5 or less.
The method of claim 7, wherein

The enameled steel sheet produced by the method for producing an enameled steel sheet has a TiS or (Ti, Mn) S precipitates having a size of 0.01 to 0.4 µm and having 3 × 10 8 or more per cubic centimeter.