WO2017052273A1 - Method for manufacturing plated steel sheet having excellent distinctness of image after coating, and plated steel sheet manufactured thereby - Google Patents

Abstract

The present invention relates to a plated steel sheet used as an automobile outer panel, etc., and more specifically, to a method for manufacturing a plated steel sheet having excellent distinctness of image after coating, and a plated steel sheet manufactured thereby.

Description

Manufacturing method of plated steel sheet having excellent coating sensibility and plated steel sheet manufactured thereby

The present invention relates to a plated steel sheet used in automobile exterior plates, and the like, and more particularly, to a method for producing a plated steel sheet excellent in paint selectivity and a plated steel sheet produced thereby.

The plated steel sheet plated with zinc, aluminum, etc. is excellent in corrosion resistance, weldability, and paintability, and thus is widely used as a steel sheet for automobile exterior panels. As such, the plated steel sheet is required as well as press formability and excellent paint screening properties.

Painting selectivity refers to the degree to which the surface coated with the painting is beautiful and can be clearly seen without distortion of the image reflected on the surface of the coating. Mainly reviewed. As a result, the coating quality has been dramatically improved by the advancement of coating and coating technology.

In particular, in recent years, in order to reduce costs in automobile companies, the primer process omitted in the three-coat coating system consisting of the top coat of the existing electrodeposition coating, the middle coat of the primer coating, and the top coat of the base coating and the clear coating is omitted. -We are actively applying the coat coating system.

The purpose of primer coating is first of all to adjust the surface unevenness of the unevenness, orange peel, etc. that may be present on the surface of the plated steel sheet to be coated, the overall thickness of the coating system is greatly reduced while the primer process is omitted, Since it does not exhibit the function of primer coating, the non-uniformity of the plated steel sheet may be exposed as it is after coating.

Accordingly, in accordance with the application of the two-coat coating system, which is a primer process omitted, a more stringent surface quality of the coated steel sheet is required.

According to these trends, studies on plated steel sheet to improve paint selectivity have been mainly examined the effects of surface roughness and shape control of surface roughness, but the surface of plated steel sheet, which is a factor affecting paint selectivity, has been studied. In terms of waviness, which is a shape profile, surface roughness (Ra) and the number of peaks (RPc) per unit length of fine unevenness, etc. are short period (short wavelength) waves covered by the coating film. It is known to be insignificant.

In addition, the study on the wave shape of the plated steel sheet is limited to controlling the average wave shape (Wca) of the plated steel sheet by adjusting the roll shape of the temper roll after plating and the temper rolling operation conditions.

For example, Patent Document 2 discloses that the solid particles are projected on the surface of the galvanized steel sheet, so that the surface average roughness of the galvanized steel sheet, that is, the surface average roughness (Ra) is 0.3 to 3.0 µm, and the number of peaks per inch (PPI) of the steel sheet surface is 250. It is proposed to improve the press formability and paint selectivity by adjusting the number of pieces or more (98 or more in the case of RPc, which is the number of peaks per unit Cm) and the average waviness (Wca) of the surface of the steel sheet to 0.8 mu m, respectively.

In addition, Patent Documents 3 and 4 are processed by laser processing (LT), and Patent Document 5 is applied by electron beam processing (EBT) to adjust the roughness and wave shape of the roll, and to use it to A method of controlling the average surface roughness Ra, the number of peaks per unit length RPc, and the average wave shape Wca has been proposed.

However, even if the shape profile of the surface of the plated layer is removed by controlling the average waviness (Wca) of the tempered rolled plated steel sheet, the shape profile of the base plate remaining in the plated layer and the base steel appears during the processing to the automotive parts before coating, which is There is a problem that it remains as it is after painting and impairs selectivity.

(Patent Document 1) Korean Unexamined Patent Publication No. 2010-0112186

(Patent Document 2) Korean Unexamined Patent Publication No. 2002-0068525

(Patent Document 3) Japanese Patent Laid-Open No. 7-136701

(Patent Document 4) Japanese Patent Laid-Open No. 6-075728

(Patent Document 5) Japanese Patent Laid-Open No. 11-302816

One aspect of the present invention is a method capable of improving the coating selectivity of a plated steel sheet without such defects even during coating, without generating an orange peel having a long wavelength when processing into an automotive component, and a coating line manufactured thereby. It is to provide a plated steel sheet excellent in spirituality.

One aspect of the invention, cold rolling to prepare a cold rolled steel sheet; Manufacturing the plated steel sheet by plating the cold rolled steel sheet; And inserting the plated steel sheet into the temper rolling mill to temper the rolling.

It provides a method for producing a plated steel sheet having excellent coating stiffness, characterized in that the long wavelength wave shape (Wsa1-5) of the final stent rolling roll during the cold rolling is 0.4㎛ or less.

Another aspect of the present invention is a plated steel sheet manufactured by the above-described method and including a cold rolled steel sheet and a plating layer formed on the cold rolled steel sheet, wherein the cold rolled steel sheet has a long wavelength wave shape (Wsa1-5) of 0.2 μm or less. Provided is a plated steel sheet having excellent paint selectivity.

According to the present invention, there is no surface defect such as an orange peel even after coating by controlling the long wavelength wave degree of the cold rolled steel sheet, which is a plating material, thereby providing an excellent coated film.

In particular, the present invention has no change in the roughness value such as the average roughness Ra of the plated steel sheet, the number of peaks per unit length RPc, and the like, and thus, the coating lineability can be improved without reducing the press formability of the plated steel sheet.

In addition, the plated steel sheet of the present invention is excellent in paint filmability, there is an effect that can be advantageously applied for automotive exterior plates.

1 is a schematic diagram showing a phenomenon in which the shape profile of the surface of the body is reproduced after processing of the plated steel sheet.

Fig. 2 is a graph showing the relationship between the long wavelength wave diagram (Wsa1-5) of the coated steel sheet and the selectivity of the coated steel sheet coated with the coated steel sheet.

Rough coating after plating is performed to prevent coating defects such as orange peel after coating of automotive exterior plated steel sheets, and roughness values such as average roughness (Ra) and peak number per unit length (RPc) of plated steel sheets and average wave shape. Although a method of appropriately adjusting the shape profile of the figure (Wca) has been proposed, since the roughness value is filtered to the coating layer (coating film) of the coated steel sheet at a short period wavelength, it is known that the influence on the coating selectivity is insignificant.

Therefore, the inventors of the present invention, in order to prevent coating defects such as orange peel after coating of the plated steel sheet for automobiles, as well as the plated steel sheet, the long wavelength wave shape of the cold rolled steel sheet (plating material) of the plated steel sheet to the plated steel sheet and the coated steel sheet The impact was examined in detail.

As a result, as shown in FIG. 1, even though the shape of the plated layer is removed by rough rolling by optimizing the rolled roll to optimize the long wavelength wave, the plated layer is processed in the manufacturing process of automobile parts before coating even if the shape profile of the surface of the plated layer is removed. It was confirmed that the shape profile of the base (original) remaining between the base steel sheet and the base steel plate appeared again on the surface of the plated layer, which remained as it is after coating, which hindered the coating screenability. From this, it can be confirmed that the coating sensibility is determined by combining not only the long wavelength wave diagram of the plated steel sheet but also the long wavelength wave diagram of the cold rolled steel sheet which is a plating material.

Among these, the long wavelength wave shape generated in the plating process can be controlled by optimizing the long wavelength wave shape of the roll used in the temper rolling, but the long wavelength wave shape of the cold rolled steel sheet, which is a plating material, is exposed after the plated steel sheet is processed. It has been found that controlling the long wave wavelength of the cold rolled sheet itself is advantageous for improving the paint selectivity.

In the present invention, it is preferable to use Wsa1-5 as the long wavelength wave diagram rather than the filtered center line waviness (WIS B0651 regulation) of conventional Wca. According to the SEP 1941 specification, Wsa1-5 is measured length ( This is because it is shown by filtering only the long wavelength wave diagram, which is the shape profile most visible to the naked eye having a wavelength of 1 to 5 mm in the shape profile including the nonuniformity, tent, etc. within 50 mm).

That is, the numbers 1 and 5 represent the lower and upper limits of the cut-off value, where 1 is the roughness cutoff value λc that removes the roughness component having a wavelength of 1 mm or less from the shape profile, and 5 is the shape profile. It means the coarse cut off value (lambda f) which removes the coarse shape of 5 mm or more. Therefore, the roughness component and the shape covered by the coating in the shape profile are coarse, and only the pure long wavelength wave diagram which removes the coarse form which is not observed by the orange peel defect etc. is shown.

In contrast, Wca, which means filtered centerline wave diagram, has a cut-off value of 0.8 to 8 mm and includes a coarseness component of 0.8 or more and a coarse form component between 5 and 8 mm. Since it is not expressed, it does not exactly match the shape profile observed with the naked eye.

Accordingly, in the present invention, in order to prevent coating defects such as orange peel after coating of the plated steel sheet for automobiles, by controlling the long wavelength wave diagram (Wsa1-5) of the cold rolled steel sheet is a plating material, Surface defects such as peeling do not appear, and to maintain this even after coating is to propose a way to secure excellent screening.

Hereinafter, the present invention will be described in detail.

According to an aspect of the present invention, a method of manufacturing a coated steel sheet having excellent paint selectivity may include preparing a cold rolled steel sheet by cold rolling, and manufacturing the plated steel sheet by plating the cold rolled steel sheet.

In manufacturing a plated steel sheet according to the present invention, it is preferable to prepare a cold rolled steel sheet is a plated material, it is preferable that the long wavelength wave shape (Wsa1-5) is a cold rolled steel sheet of 0.2㎛ or less.

Even if the long-wave wave shape (Wsa1-5) of the cold rolled steel sheet is 0.2 μm or less (excluding 0), even if the component processing is performed after plating, surface defects such as orange peel do not appear, and thus excellent screenability can be obtained even after coating. .

However, when the long wavelength waviness (Wsa1-5) of the cold rolled steel sheet, which is a plated material, exceeds 0.2 μm, surface defects such as orange peel appear during the processing of parts after plating. do.

As described above, in order to obtain a cold rolled steel sheet having a long wavelength wave shape (Wsa1-5) of 0.2 µm or less, it is preferable to control the long wavelength wave shape (Wsa1-5) of the rolling roll used during cold rolling, and more preferably, It is preferable to control the long wavelength wave shape Wsa1-5 of a stand rolling roll to 0.4 micrometer or less (except 0).

If the long wavelength wave shape (Wsa1-5) of the final stand rolling roll exceeds 0.4 μm during cold rolling, the long wave shape (Wsa1-5) of the cold rolled steel sheet manufactured exceeds 0.2 μm. A defect arises, and this remains after coating, and there exists a problem of reducing coating selectivity.

On the other hand, the cold-rolled steel sheet may be any steel sheet that can produce a conventional plated steel sheet.

For example, it may be a low carbon steel sheet, the low carbon steel sheet, for example, by weight% carbon (C): 0.002% or less (excluding 0%), manganese (Mn): 0.08% or less (excluding 0%), Silicon (Si): 0.003% or less (except 0%), aluminum (Al): 0.028% or less (except 0%) and the like, Cu, Ni for the purpose of improving the mechanical properties of the coated steel sheet It may further comprise Mo, Nb, V, B and the like, it may be made of the remaining Fe and other unavoidable impurities.

However, in the present invention, the cold rolled steel sheet is not limited to the low carbon steel sheet.

Subsequently, the cold-rolled steel sheet having the long wavelength wave shape (Wsa1-5) is preferably plated and manufactured as a plated steel sheet. In this case, the plating is preferably performed so that the plating adhesion amount of one surface is 45 g / m ² or more. More preferably, plating can be performed so that it may become 45 g / m <^2> or more and 80 g / m <^2> or less.

If the plating adhesion amount at the time of plating is less than 45g / m ² , even if the cold-rolled steel sheet having a long wavelength wave shape (Wsa1-5) intended in the present invention as a plating material, surface defects such as orange peel appears when processing parts after plating, There is a problem that it is retained even after painting, thereby reducing the selectivity.

The plating method is not particularly limited, but for example, hot dip plating or electroplating may be used.

The plated steel sheet in the case of using the hot dip plating may be, for example, a hot dip galvanized steel sheet, a hot dip aluminum plated steel sheet and an aluminum alloy plated steel sheet, and may be an alloyed hot dip galvanized steel sheet alloyed with the plated steel sheet.

In addition, the plated steel sheet in the case of using the electroplating may be, for example, an electrogalvanized steel sheet or an electrogalvanized steel sheet.

The plated steel sheet manufactured according to the above can be loaded into a conventional temper rolling mill to perform temper rolling. At this time, 150 tons using a tempered roll having a long wavelength waviness (Wsa1-5) of 0.4 μm or less (excluding 0) It is preferable to carry out by the above roll rolling force.

When the roll having the long wavelength wave shape (Wsa1-5) of 0.4 µm or less is used during temper rolling, a plated steel sheet having a long wavelength wave shape (Wsa1-5) of 0.28 µm or less (excluding 0) can be finally obtained.

The long wavelength wave shape (Wsa1-5) of the plated steel sheet before processing is determined by the long wavelength wave diagram of the cold rolled steel sheet, which is a plating material, and the long wavelength wave diagram after plating, which affects the long wavelength wave value after processing. Therefore, in order to control the long wavelength wave shape of the plated steel sheet after processing to less than 0.35 μm, it is preferable to manage the long wavelength wave shape of the plated steel sheet before processing to 0.28 μm or less.

Hereinafter, a plated steel sheet which is another aspect of the present invention will be described in detail.

The plated steel sheet according to the present invention includes a cold rolled steel sheet and a plated layer formed on the cold rolled steel sheet, and the cold rolled steel sheet preferably has a long wavelength wave shape (Wsa1-5) of 0.2 μm or less.

In this case, the plating layer may be a zinc plating layer, an aluminum plating layer, a zinc alloy plating layer or an aluminum alloy plating layer, but is not limited thereto.

The above-described plated steel sheet of the present invention is manufactured by the above-described manufacturing method according to the present invention, and in particular, a cold rolled roll having a long wavelength waviness (Wsa1-5) of 0.4 µm or less is used as the final stand rolling roll. As a result, the long-wave wave shape (Wsa1-5) of the cold-rolled steel sheet satisfies 0.2 µm or less, whereby a plated steel sheet excellent in coating selectivity can be provided.

Meanwhile, the present inventors evaluated the selectivity of the coated steel sheet as shown in FIG. 2 in order to derive the relationship of how the long wavelength waviness (Wsa1-5) of the coated steel sheet affects the selectivity of the coated steel sheet. In general, paint selectivity of automotive steel sheet is quantitatively evaluated using DIO wavescan (DIO wavescan, BYK-Gardner). The DIO value of the DIO wave scan is represented in the structural spectrum continuously from the short-period wavelength to the long-period wavelength, and the value of each wavelength band is represented as a dimensionless 0 to 100 value.

As a result of the evaluation, as shown in FIG. 2, there is a high correlation between the long period wavelength of the cup steel plate (5% top surface) plated steel sheet (not coated) and the long period wavelength of the coated steel sheet coated with the two-coat coating system. can confirm.

More specifically, in the long period wavelength of 0.35㎛ or more of the processed plated steel sheet, the coated steel sheet has a problem that the orange peel is formed with a long period wavelength of 5㎛ or more, the coating screening performance is lowered.

Through this, since it is possible to estimate the orange peel formation after coating and the reduction of paint stiffness by measuring the long wavelength wave shape (Wsa1-5) after 5% processing of the plated steel sheet, in the present invention, after 5% processing of the plated steel sheet The coating selectivity can be evaluated by measuring the long wavelength wave diagram.

Accordingly, the plated steel sheet of the present invention preferably has a long wavelength wavelength (Wsa1-5) of less than 0.35 µm (excluding 0) after processing at a strain of 5%.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, it is necessary to note that the following examples are only intended to illustrate the present invention in more detail, and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the claims and the matters reasonably inferred therefrom.

(Example)

After preparing a pickling hot rolled steel sheet of general low carbon steel, the hot rolled steel sheet was cold rolled to produce a cold rolled steel sheet. At this time, by giving the surface unevenness of the last rolling roll of the cold rolling process by shot blasting and discharge processing, the average roughness Ra and the number of peaks per unit length RPc are adjusted to adjust the long wavelength wave shape (Wsa1-5) by 0.18. After adjusting to -0.66 micrometer, it cold-rolled at 77-83% of cold rolling ratio using this rolling roll. As a result, a cold rolled steel sheet having an average roughness (Ra) of 0.61 to 0.85 µm, a number of peaks (RPc) per unit length of 34 to 56 particles / cm, and a long wavelength waviness (Wsa1-5) of 0.18 to 0.28 µm was produced. It was. Here, roughness values and wave shape values, such as the average roughness Ra of each roll and cold rolled steel sheet, the number of peaks per unit length (RPc), and the long wavelength wave shape (Wsa1-5), are measured using a contact type two-dimensional roughness meter (HOSAKAWA). Measured according to SEP 1941 regulations.

After annealing and heat-treating each cold-rolled steel sheet manufactured according to the above-mentioned conditions under normal conditions, immersing it in a hot dip galvanizing bath and plating the surface with an air knife at 40 to 80 g / m ² , followed by electric discharge machining (EDT). ) And is roughly rolled with a roll force of 150 tons using a rough rolling work roll having an average roughness (Ra) of 2.7 탆 and a long wavelength waviness (Wsa1-5) of 0.3 탆. A hot dip galvanized steel sheet having a degree (Wsa1-5) of 0.17 to 0.46 µm was manufactured.

After manufacturing each hot-dip galvanized steel sheet by a cupping test (Cupping test) so that the deformation rate of the flat portion of the evaluation surface with a molding tester (5%), the long wavelength wave shape (Wsa1-5) was measured, and the orange peel visually Formation was evaluated and the results are shown in Table 1 below.

At this time, the cupping test was such that the diameter of the flat deformed flat portion of the cup to at least 100mm, the strain was adjusted to the processing height.

Steel grade	Final Stand Rolling Roll		Cold rolled steel sheet			Coating Weight (g / m 2 )	Temper Roll			Plated steel sheet			Sunyoung Evaluation		Remarks
	Average roughness (㎛)	Wsa1-5	Average roughness (㎛)	RPc (/ cm)	Wsa1-5		Average roughness (㎛)	Wsa1-5	Roll rolling force (ton)	Average roughness (㎛)	RPc (/ cm)	Before processing Wsa1-5	Wsa1-5 after machining	Defect
One	2.1	0.36	0.85	56	0.18	60	2.7	0.3	150	1.15	78	0.27	0.28	Not Occurred	Inventive Example 1
2	2.1	0.26	0.81	43	0.18	60	2.7	0.3	150	1.21	76	0.26	0.28	Not Occurred	Inventive Example 2
3	2.1	0.26	0.75	36	0.18	60	2.7	0.3	150	1.09	77	0.26	0.27	Not Occurred	Inventive Example 3
4	2.1	0.28	0.72	34	0.19	60	2.7	0.3	150	1.15	75	0.23	0.26	Not Occurred	Inventive Example 4
5	2.1	0.25	0.66	39	0.18	60	2.7	0.3	150	1.12	77	0.24	0.25	Not Occurred	Inventive Example 5
6	2.1	0.23	0.61	35	0.18	60	2.7	0.3	150	1.24	75	0.23	0.25	Not Occurred	Inventive Example 6
7	2.1	0.66	0.7	35	0.28	60	2.7	0.3	150	1.06	78	0.46	0.54	Occur	Comparative Example 1
8	2.1	0.49	0.7	35	0.26	60	2.7	0.3	150	1.11	77	0.35	0.42	Occur	Comparative Example 2
9	2.1	0.42	0.7	35	0.26	60	2.7	0.3	150	1.07	77	0.33	0.38	Occur	Comparative Example 3
10	2.1	0.38	0.7	35	0.2	60	2.7	0.3	150	1.1	75	0.28	0.3	Not Occurred	Inventive Example 7
11	2.1	0.34	0.7	35	0.2	60	2.7	0.3	150	1.08	78	0.27	0.27	Not Occurred	Inventive Example 8
12	2.1	0.26	0.7	35	0.2	60	2.7	0.3	150	1.08	78	0.23	0.27	Not Occurred	Inventive Example 9
13	2.1	0.18	0.7	35	0.19	60	2.7	0.3	150	1.12	78	0.17	0.24	Not Occurred	Inventive Example 10
14	2.1	0.34	0.7	35	0.2	40	2.7	0.3	150	1.08	78	0.32	0.37	Occur	Comparative Example 4
15	2.1	0.34	0.7	35	0.2	45	2.7	0.3	150	1.16	76	0.27	0.32	Not Occurred	Inventive Example 11
16	2.1	0.34	0.7	35	0.2	50	2.7	0.3	150	1.21	78	0.26	0.3	Not Occurred	Inventive Example 12
17	2.1	0.34	0.7	35	0.2	75	2.7	0.3	150	1.11	80	0.27	0.29	Not Occurred	Inventive Example 13
18	2.1	0.34	0.7	35	0.2	80	2.7	0.3	150	1.19	79	0.26	0.28	Not Occurred	Inventive Example 14
19	2.1	0.42	0.7	35	0.26	45	2.7	0.3	150	1.12	80	0.37	0.47	Occur	Comparative Example 5

(In Table 1, 'Wsa1-5 after processing' means Wsa1-5 value accumulated after 5% processing, and 'defect present' refers to orange peel formation.)

As shown in Table 1 above, when using a rolling roll having a long wavelength waviness (Wsa1-5) of 0.4 µm or less during the final stand rolling of the cold rolling process (Invention Example 1-14), the long waviness (Wsa1-5) A cold rolled steel sheet having a thickness of 0.2 µm or less can be obtained. When the hot-dip galvanizing is performed using the cold rolled steel sheet as a plating material at a plating adhesion amount of 45g / m ² or more on one side, the long wavelength after 5% cupping of the hot-dip galvanized steel sheet which is a coating material The waviness (Wsa1-5) was less than 0.35 µm, and even when observed with the naked eye, long-wavelength defects such as orange peel did not occur, resulting in excellent paint selectivity.

On the other hand, in the case of using a rolling roll having a long wavelength waviness (Wsa1-5) of more than 0.4 µm in the final pass of the cold rolling process (Comparative Examples 1-3 and 5), the long wavelength waviness (Wsa1-5) was 0.2 µm. When the cold rolled steel sheet is exceeded, and hot-dip galvanizing is performed using the cold-rolled steel sheet as a plating material at a plating adhesion amount of 45g / m ² or more on one side, the long-wave wave shape after 5% cupping processing of the hot-dip galvanized steel sheet as a coating material As (Wsa1-5) became 0.35 micrometer or more, the long-wavelength defect like orange peel was visually recognized.

In addition, even when a roll having a long wavelength waviness (Wsa1-5) of 0.4 µm or less is used, even when the plating adhesion amount of one side is less than 45 g / m ² at the time of plating (Comparative Example 4), the long wavelength waviness after 5% cupping processing (Wsa1) As -5) became 0.35 micrometer or more, the long-wavelength defect like orange peel was visually recognized.

Claims (8)

1. Cold rolling to prepare a cold rolled steel sheet;

   Manufacturing the plated steel sheet by plating the cold rolled steel sheet; And

   Inserting the plated steel sheet into a temper rolling mill to temper rolling;

   The long wavelength wave shape (Wsa1-5) of the final stand rolling roll during the cold rolling is 0.4㎛ or less (excluding 0), the method of manufacturing a coated steel sheet excellent in paint filmability.
2. The method of claim 1,

   The cold rolled steel sheet has a long wavelength wave shape (Wsa1-5) of 0.2 μm or less (excluding 0).
3. The method of claim 1,

   The plating is a method for producing a coated steel sheet excellent coating selectivity that is carried out so that the plating adhesion amount on one side of 45g / m ² or more.
4. The method of claim 1,

   The temper rolling is a method of producing a coated steel sheet having excellent coating stiffness that uses a roll having a long wavelength wave shape (Wsa1-5) of 0.4 ㎛ or less (excluding 0).
5. The method according to any one of claims 1 to 4,

   The plated steel sheet is a hot dip galvanized steel sheet, a hot dip aluminum plated steel sheet, an aluminum alloy plated steel sheet, an electrogalvanized steel sheet, an electro zinc alloy plated steel, and an alloyed hot dip galvanized steel sheet, any one of the methods of producing a plated steel sheet having excellent coating goodness .
6. As a plated steel sheet comprising a cold rolled steel sheet and a plating layer formed on the cold rolled steel sheet,

   The cold-rolled steel sheet is a plated steel sheet having excellent coating clarity, characterized in that the long wavelength wave shape (Wsa1-5) is 0.2㎛ or less (excluding 0).
7. The method of claim 6,

   The plated steel sheet is a plated steel sheet having excellent coating sensibility having a long wavelength wave shape (Wsa1-5) of 0.28 μm or less (excluding 0).
8. The method of claim 6,

   The plated steel sheet is a plated steel sheet having excellent coating sensibility having a surface long wavelength (Wsa1-5) of less than 0.35㎛ (excluding 0) after processing at a strain rate of 5%.

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