Plated steel sheet and method for manufacturing same

Abstract

A plated steel sheet according to one embodiment of the present invention comprises: a steel sheet substrate; a plated part positioned on the steel sheet; a coated part positioned on the plated part; and a cut part formed by cutting the steel sheet substrate. The plated part includes a first plated part positioned on the upper or lower surface of the steel sheet substrate and a second plated part positioned on the upper surface of the cut part, and the coated part includes a first coated part positioned on the first plated part.

Description

galvanized steel sheet and method of manufacturing the same

[0001] One embodiment of the present invention relates to a plated steel sheet and a method for manufacturing the same. More specifically, one embodiment of the present invention relates to a plated steel sheet with improved corrosion resistance when the plated steel sheet is cut and a method for manufacturing the same.

[0002] Straight blades are used during the cutting process of galvanized steel sheets. To prevent corrosion on the cut surface when using such straight blades, technologies are employed, such as improved blades designed to push the plating layer down and adhere in small amounts to the cut surface to slow down corrosion, or techniques where the upper and lower blades are positioned vertically to the steel sheet to allow the plating layer to slide down to the cut surface. However, while these technologies can be utilized to improve the corrosion resistance of the cut surface of sheet-type galvanized steel, they have limitations in that they are not easily applicable to the cut surface of coil-type galvanized steel. Furthermore, if the blade shape is changed from straight to circular and used to cut coil-type galvanized steel, it has the disadvantage of a shorter lifespan compared to conventional blades, and the cut surface becomes rough rather than clean, thereby accelerating corrosion.

[0003] Meanwhile, the sacrificial mode of the plating layer plays a key role in preventing corrosion at the cut edge of galvanized steel sheets. Additionally, the plating layer reacts with corrosive substances to generate corrosion products; these products flow down to the cut edge of the steel sheet via water droplets or rainfall and accumulate on the corroded areas, thereby serving as a barrier-type corrosion prevention mechanism.

[0004] The sacrificial and blocking mechanisms of the cut surface by the plating layer improve as the thickness of the galvanized steel sheet decreases and as the thickness of the plating layer increases. When the corrosion prevention performance of the cut surface of the galvanized steel sheet improves, the lifespan of the part also increases. However, there is a problem in that the thickness cannot be reduced below a certain level because the thickness must be maintained to ensure rigidity depending on the application of the galvanized steel sheet, and furthermore, it is not easy to plate more than a certain amount due to limitations in the galvanized steel sheet manufacturing process.

[0005] One embodiment of the present invention provides a plated steel sheet and a method for manufacturing the same. More specifically, one embodiment of the present invention provides a plated steel sheet with improved corrosion resistance when the plated steel sheet is cut and a method for manufacturing the same.

[0006] A plated steel sheet according to one embodiment of the present invention comprises a steel sheet substrate; a plating portion located on the steel sheet; a coating portion located on the plating portion; and a cut portion in which the steel sheet substrate is cut.

[0007] The plating section includes a first plating section located on the upper or lower surface of the steel plate substrate and a second plating section located on the upper surface of the cutting section, and the painting section includes a first painting section located on the first plating section.

[0008] The second plating section can be formed for more than 10% of the total length of the cut section.

[0009] The first plating portion adjacent to the cut portion may include a crack.

[0010] There may be 0 to 3 cracks per 0.5 mm length in the direction perpendicular to the thickness of the steel plate.

[0011] The first coating portion adjacent to the cut portion may include a crack.

[0012] There may be 0 to 3 cracks per 0.5 mm length in the direction perpendicular to the thickness of the steel plate.

[0013] The first coating portion adjacent to the cutting portion may include a peeling portion.

[0014] The peeled portions may have a height of 2㎛ or more and may be 0 to 5 per 0.1mm length in the direction perpendicular to the thickness of the steel plate.

[0015] It may include a compression section adjacent to the cutting section and having a thickness of 90% or less of the maximum thickness of the steel plate substrate.

[0016] In the compression section, the thickness of the steel plate substrate may decrease as it moves from the direction perpendicular to the thickness of the steel plate towards the cutting section.

[0017] The compressed portion can be curved in the direction opposite to the cut portion from the direction perpendicular to the thickness of the steel plate.

[0018] In the compression section, the slope of the interface between the steel plate substrate and the first plating section may change as it moves from the direction perpendicular to the thickness of the steel plate toward the cutting section.

[0019] The width of the compressed portion may be 1 mm to 4 mm.

[0020]

[0021] A method for manufacturing a plated steel sheet according to one embodiment of the present invention comprises: a step of supplying a plated steel sheet comprising a steel sheet substrate, a plating portion located on one or both sides of the steel sheet substrate, and a coating portion located on the surface of the plating portion; and a step of cutting the plated steel sheet to form a cut portion; wherein, in the step of forming the cut portion, a second plating portion located on the upper surface of the cut portion is formed.

[0022] After the step of supplying the galvanized steel sheet, the method may further include a step of forming a compressed portion by pressing the galvanized steel sheet.

[0023] After the step of forming the cut portion, the method may further include a step of forming a compressed portion by pressing the plated steel sheet.

[0024] In the step of forming the compression portion, a compression portion can be formed that is concave inward along the thickness direction of the steel plate, with a width greater than the compression depth.

[0025] In the step of forming the compressed portion, the compression pressure applied to the steel plate may be 5 kg / cm² to 300 kg / cm².

[0026] In the step of forming the cut portion, the cut portion may be formed to pass through the center in the width direction of the compressed portion.

[0027] In the step of forming the cut section, the plated section may occupy more than 10% of the total length of the cut section.

[0028]

[0029] A plated steel sheet according to one embodiment of the present invention comprises: a steel sheet substrate; a plating portion located on the steel sheet substrate; a coating portion located on the plating portion; a cut portion where the steel sheet substrate is cut; a compression portion adjacent to the cut portion having a thickness of 90% or less of the maximum thickness of the steel sheet substrate; and an uncompressed portion adjacent to the compression portion where the steel sheet substrate is not compressed.

[0030] The plating section comprises: a first plating section located on the upper or lower surface of the uncompressed portion of the steel sheet substrate; a second plating section located on the upper or lower surface of the compressed portion; and a third plating section located on the upper surface of the cutting portion.

[0031] The coating section includes a first coating section located on a first plating section; a second coating section located on a second plating section; and a third coating section located on a third plating section.

[0032] The third plating section can be formed for more than 10% of the total length of the cut section.

[0033] The second plating portion adjacent to the cut portion may include a crack.

[0034] There may be 0 to 3 cracks per 0.5 mm length in the direction perpendicular to the thickness of the steel plate.

[0035] The second coating portion adjacent to the cut portion may include a crack.

[0036] There may be 0 to 3 cracks per 0.5 mm length in the direction perpendicular to the thickness of the steel plate.

[0037] A second coating portion adjacent to the cutting portion may include a peeling portion.

[0038] The peeled portions may have a height of 2㎛ or more and may be 0 to 5 per 0.1mm length in the direction perpendicular to the thickness of the steel plate.

[0039] A Ni-plated steel sheet for cans according to one embodiment of the present invention has excellent durability and processability, so it can be usefully used in cylindrical battery cases.

[0040] FIG. 1 is a perspective view illustrating a portion of a plated steel sheet according to one embodiment of the present invention.

[0041] Figure 2 is a cross-sectional view showing the galvanized steel plate of Figure 1 viewed from the side.

[0042] Figure 3 is a partially enlarged cross-sectional view of the plated steel plate of Figure 1.

[0043] FIG. 4 is a perspective view illustrating a portion of a plated steel sheet according to another embodiment of the present invention.

[0044] Figure 5 is a cross-sectional view showing the galvanized steel plate of Figure 4 viewed from the side.

[0045] FIG. 6 is a cross-sectional view showing a portion of a plated steel sheet viewed from the side according to another embodiment of the present invention.

[0046] FIG. 7(a) is a cross-sectional view showing a portion of a plated steel sheet before cutting according to another embodiment of the present invention, and FIG. 7(b) is a cross-sectional view showing the plated steel sheet of FIG. 7(a) after cutting.

[0047] FIG. 8 schematically illustrates the state before starting the manufacture of a plated steel sheet according to another embodiment of the present invention.

[0048] FIG. 9 schematically illustrates an example of a method for manufacturing a plated steel sheet according to another embodiment of the present invention.

[0049] FIG. 10 is a cross-sectional view showing a plated steel sheet before being cut after the compression process is completed.

[0050]

[0051] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention.

[0052] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0053] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0054] In one embodiment of the present invention, the meaning of including additional elements is that the remainder of iron (Fe) is replaced by an amount of the additional element.

[0055] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0056] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0057]

[0058] FIG. 1 is a perspective view showing a portion of a plated steel sheet (10) according to one embodiment of the present invention. FIG. 2 and FIG. 3 are cross-sectional views showing the plated steel sheet of FIG. 1 viewed from the side.

[0059] Referring to FIGS. 1 to 3, a plated steel plate (10) according to one embodiment of the present invention may include a steel plate substrate (11), a plating portion (12), and a coating portion (15). The steel plate substrate (11) may have a long plate shape. The plated steel plate (10) has a plating portion (12) on the steel plate substrate (11), and a coating portion (15) on the plating portion (12). Additionally, the plated steel plate (10) includes a cutting portion (14) by cutting it to a predetermined length. At this time, the length of the plated steel plate (10) after cutting may be cut to various lengths based on the use of the plated steel plate (10), etc.

[0060] The plating portion (12) and the coating portion (15) partially cover the outer surface of the steel plate substrate (11), thereby improving the corrosion resistance and durability of the entire steel plate substrate (11) and the plated steel plate (10).

[0061] For example, zinc may be used as the plating material forming the plating portion (12). Additionally, the plating portion (12) may be formed by adding a small amount of aluminum and magnesium to zinc. In this case, the plating portion (12) may be configured to contain 1.5% to 13% aluminum, 1.5% to 7% magnesium, and 80% to 97% zinc in weight percent, but is not limited thereto. Meanwhile, the plating portion (12) may be formed by methods such as electroplating or hot-dip plating.

[0062] The plating portion (12) may include a plating portion (12a) covering the upper surface of the steel plate substrate (11) or a plating portion (12b) covering the lower surface of the steel plate substrate (11). Accordingly, the plating portion (12) may be formed on the upper or lower surface of the steel plate substrate (11). The plating portion (12) located on the upper or lower surface of the steel plate substrate (11) is designated as the first plating portion (12a, 12b). In addition, in one embodiment of the present invention, the plating portion (12) includes a second plating portion (12c) located on the upper surface of the cut portion (14) of the steel plate substrate (11). In one embodiment of the present invention, by covering at least a portion of the cut portion (14) with the second plating portion (12c), the exposed area of ​​the steel plate substrate (11) is reduced, and the corrosion resistance and durability of the entire steel plate substrate (11) and the plated steel plate (10) can be further improved. The second plating portion (12c) may extend from the upper surface of the steel plate substrate (11) or from the lower surface of the steel plate substrate (11). According to one embodiment, the plating portion (12) may not be formed on the side portion (11a) of the steel plate substrate (11). According to another embodiment, the plating portion (12) may be partially formed by extending a portion of it on the side portion (11a) of the steel plate substrate (11).

[0063] The coating material forming the coating portion (15) may include, for example, a resin. The resin may include one or more of polyester, epoxy, polyurethane, and acrylic, but is not limited thereto. The coating portion (15) may be formed by applying and drying a coating portion forming composition.

[0064] The coating portion (15) may include a coating portion (15a) located on a plating portion (12a) covering the upper surface of the steel plate substrate (11) or a coating portion (15b) located on a plating portion (12b) covering the lower surface of the steel plate substrate (11). The coating portion (15) located on the upper or lower surface of the steel plate substrate (11) is designated as the first coating portion (15a, 15b). In one embodiment of the present invention, the coating portion (15) may also exist on the second plating portion (12c), and this is designated as the second coating portion (15c). Although FIG. 1 shows an example in which the second coating portion (15c) exists, it is also possible for the second coating portion (15c) not to exist. According to one embodiment, the coating portion (15) may not be formed on the side portion (11a) of the steel plate substrate (11). According to another embodiment, the coating portion (15) may be partially formed by extending a portion of the side portion (11a) of the steel plate substrate (11).

[0065] The cutting portion (14) can be formed by cutting the plating portion (12), the coating portion (15), and the steel plate substrate (11). For example, the cutting portion (14) can be formed by cutting along a direction parallel to the thickness direction (or also called the second direction, B2) of the steel plate substrate (11).

[0066] Additionally, when viewed from the side (e.g., ZX plane direction) along the width direction (or also called the first direction B1) of the steel plate substrate (11), the cut portion (14) may be present at both ends of the plated steel plate (10).

[0067] In one embodiment of the present invention, at least one portion of the upper surface of the cutting portion (14) is covered by the second plating portion (12c), thereby reducing the exposed area of ​​the steel plate substrate (11) and further improving the corrosion resistance and durability of the entire steel plate substrate (11) and the plated steel plate (10).

[0068] The length of the second plating section (12c) can be formed to be at least 10% of the total length of the cutting section (14).

[0069] At this time, the length of the cut portion (14) refers to the total length of the side portion of the steel plate substrate (11) connecting the upper and lower surfaces of the steel plate substrate (11). The second plating portion (12c) refers to the length that starts from a position extending in the first direction (B1) from the upper and lower surfaces of the steel plate substrate (11) and meets the cut portion (14). In one embodiment of the present invention, if the second plating portion (12c) exists discontinuously as shown in FIG. 1, the length of the second plating portion (12c) can be determined by the sum of these lengths. The method of determining the length can be determined using an electron microscope.

[0070] If the length of the second plating section (12c) is too short, it is difficult to sufficiently achieve the corrosion resistance and durability intended in one embodiment of the present invention. More specifically, the length of the second plating section (12c) may be formed to be 10 to 90% of the total length of the cut section (14). More specifically, the length of the second plating section (12c) may be formed to be 30 to 90% of the total length of the cut section (14). More specifically, the length of the second plating section (12c) may be formed to be 30 to 85% of the total length of the cut section (14).

[0071] The second plating section (12c) and the second coating section (15c) may be formed when a portion of the plating and coating components moves to the cutting section (14) during the cutting process of the plated steel plate (20). Accordingly, the thickness of the second plating section (12c) and the second coating section (15c) may be smaller than the thickness of the first plating section (12a, 12b) and the first coating section (15a, 15b). The thickness of the second plating section (12c) and the second coating section (15c) may decrease from the outer surface of the plated steel plate (10) toward the inside, but as another example, they may be formed to have the same or similar thickness overall along the second direction (B2).

[0072] As shown in FIG. 3, the first plating section (12a, 12b) adjacent to the cutting section (14) may contain a crack (16). During the process of creating the cutting section (14), some impact is applied to the first plating section (12a, 12b), and a crack (16) may be created within the first plating section (12a, 12b) adjacent to the cutting section (14). The crack (16) can be observed through microscopic observation, and it can be determined as a crack if the continuously connected length in the second direction (B2) is at least 80% of the thickness of the plating section (12a, 12b) and the coating section (15a, 15b). The meaning of being adjacent to the cutting section (14) is a length of 2 mm to 5 mm in the first direction from the cutting section (14). The crack creation length may be 1 mm to 2 mm wider than the width of the compression width (1 mm to 4 mm).

[0073] In one embodiment of the present invention, cracks (16) within the first plating portion (12a, 12b) can be minimized due to the presence of the coating portion (15) and the compression portion (13), thereby further improving corrosion resistance and durability. Specifically, the number of cracks may be 0 to 3 per 0.5 mm length in the direction perpendicular to the thickness of the plated steel plate (10) (width direction, first direction, B1, Y). More specifically, the number may be 0 to 2.

[0074] As shown in FIG. 3, the first coating portion (15a, 15b) adjacent to the cut portion (14) may contain a crack (16). During the process of creating the cut portion (14), some impact is applied to the first coating portion (15a, 15b), and a crack (16) may be created within the first coating portion (15a, 15b) adjacent to the cut portion (14). The crack (16) can be observed through microscopic observation, and can be determined as a crack if the continuously connected length in the second direction (B2) is at least 80% of the thickness of the coating portion (15a, 15b). In one embodiment of the present invention, the presence of the compression portion (13) can minimize the crack (16) within the first coating portion (15a, 15b), thereby further improving corrosion resistance and durability. Specifically, there may be 0 to 3 cracks per 0.5 mm length in the direction perpendicular to the thickness of the plated steel plate (10) (width direction, first direction, B1, Y). More specifically, there may be 1 to 2 cracks.

[0075] As shown in FIG. 3, the first coating portion (15a, 15b) adjacent to the cutting portion (14) may include a peeling portion (17). During the process of creating the cutting portion (14), some impact is applied to the first coating portion (15a, 15b), and the first coating portion (15a, 15b) adjacent to the cutting portion (14) may be partially peeled off and protrude from the first coating portion (15a, 15b) to exist as a peeling portion (17). The peeling portion (17) can be observed through microscopic observation, and a height of 2 μm or more in the second direction (B2, Z) can be determined as a peeling portion.

[0076] In one embodiment of the present invention, the peeling portion (17) can be minimized due to the presence of the compression portion (13), thereby further improving corrosion resistance and durability. Specifically, the peeling portion (17) may be 0 to 5 per 0.5 mm length in the direction perpendicular to the thickness of the plated steel sheet (10) (width direction, first direction, B1, Y). More specifically, it may be 0 to 3.

[0077]

[0078] A steel plate according to another embodiment of the present invention may include a compression portion (13) adjacent to a cutting portion (14) and having a thickness of 90% or less of the maximum thickness of the steel plate substrate (11).

[0079] FIG. 4 is a perspective view showing a part of a plated steel sheet (10) including a compression part (13). FIG. 5 and FIG. 6 are cross-sectional views showing the plated steel sheet of FIG. 4 viewed from the side.

[0080] As the configuration of the plated steel sheet (10) excluding the compression part (13) has been described in FIGS. 1 to 3, redundant descriptions are omitted.

[0081] Referring to FIG. 5, the plated steel sheet (10) may include a first plated steel sheet region (A10) and a second plated steel sheet region (A20).

[0082] The first plated steel plate area (A10) may include the first steel plate area (A11) and the first plating area (A12).

[0083] The first steel plate region (A11) may be in the form of a plate extending along the first direction (B1) to have a thickness equal to or similar to the maximum thickness of the steel plate substrate (11). In this case, the first steel plate region (A11) may include a portion of the steel plate (21) whose thickness has been reduced by compression processing. In this case, the portion of the steel plate (21) whose thickness has been reduced may be placed in a portion connected to the second steel plate region (A21) to be described later.

[0084] The first plating area (A12) is an area where compression processing is not directly performed in the plating section (12) and can be formed on the first steel plate area (A11). More specifically, the first plating area (A12) can cover the upper and lower surfaces of the first steel plate area (A11). At this time, the first plating area (A12) may not be formed on both side portions (11a) of the first steel plate area (A11), or only partially formed.

[0085] The first coating area (A15) is an area where compression processing is not directly performed in the coating section (15), and can be formed on the first plating area (A12). At this time, the first coating area (A15) may not be formed on both side sections (11a) of the first steel plate area (A11), or only partially formed.

[0086] The second plated steel plate area (A20) is an area of ​​the plated steel plate (10) where compression processing is performed, and can be arranged to be continuous with the first plated steel plate area (A10). More specifically, the first end (E1) of the second plated steel plate area (A20) can be continuous with the first plated steel plate area (A10). At this time, the first end (E1) may be a location where the thickness of the steel plate substrate (11) is 90% of the maximum thickness of the steel plate substrate (11) (i.e., the thickness of the steel plate substrate in the first plated steel plate area (A11)).

[0087] Additionally, the second end (E2) of the second plated steel plate area (A20) may be formed in an area extending to the opposite side of the first plated steel plate area (A10) along the first direction (B1). Here, the first direction (B1) is the width direction of the plated steel plate (10) and may be a direction parallel to the Y-axis direction of the drawing. A cut portion (14) is formed at the second end (E2) of the second plated steel plate area (A20).

[0088] The second plated steel plate area (A20) may include a second steel plate area (A21), a second plating area (A22), and a second coating area (A25). The second plating area (A22) may be formed on the upper and lower surfaces of the second steel plate area (A21). The second coating area (A25) may be formed on the second plating area (A22). At this time, the second plating area (A22) and the second coating area (A25) may not be formed on both side portions (11a) of the second steel plate area (A21), or may only be formed on a portion thereof.

[0089] The second plated steel plate area (A20) may include a compression portion (13) and a cutting portion (14). The compression portion (13) may be formed by compression processing. The compression portion (13) may be in a shape that is inwardly concave on one surface of the second plating area (A22) and the second coating area (A25). The aforementioned one surface of the second plating area (A22) and the second coating area (A25) may be either the upper surface or the lower surface of the second plating area (A22) and the second coating area (A25). Accordingly, the compression portion (13) may be formed inwardly concave by a compression depth (P1) along the second direction (B2) from the upper surface and the lower surface of the second plating area (A22) and the second coating area (A25). Here, the second direction (B2) is the thickness direction of the plated steel sheet (10) and may be a direction parallel to the Z-axis direction in the drawing.

[0090] In the compression section (13), the thickness of the steel plate substrate (11) can decrease as it moves from the direction perpendicular to the thickness of the steel plate (first direction Y, B1) toward the cutting section (14). That is, the compression depth (P1) can vary along the width direction (i.e., first direction) (B1) of the compression section (13). More specifically, the compression depth (P1) can increase from the first end (E1) of the second plated steel plate area (A20) toward the second end (E2) along the first direction (B1). In this case, the compression depth (P1) of the compression section (13) can be minimum at the first end (E1) and maximum at the second end (E2).

[0091] For example, the compression part (13) may be curved in the direction opposite to the cutting part in the direction perpendicular to the thickness of the steel plate (first direction, B1, Y). That is, the compression part (13) may have a shape curved toward the inside of the second plated steel plate area (A20). In this case, when viewed from the side direction (e.g., the YZ plane direction), the compression part (13) may extend in a curved shape along the first direction (B1). At this time, the width (L1) of the compression part (13) may be formed to be greater than the compression depth (P1). Accordingly, the compression part (13), which is in a curved shape, may have a minimum radius of curvature at the second end (E2) of the second plated steel plate area (A20) and a maximum radius of curvature at the first end (E1) of the second plated steel plate area (A20). At this time, the minimum radius of curvature may be, for example, 1 mm, and in this case, the radius of curvature of the compression part (13) may be 1 mm or more.

[0092] Because it is formed in a curved shape, the slope (θ) of the tangent (TL) of the compression part (13) can vary along the first direction (B1). More specifically, as the compression part (13) moves toward the cutting part (14) in the direction perpendicular to the thickness of the steel plate (first direction, B1, Y), the slope of the steel plate substrate (11), the interface of the first plating part (12a, 12b), and the first plating part (12a, 12b) and the second coating part (15a, 15b) changes. That is, at the second end (E2) of the second plated steel plate area (A20) where the compression depth (P1) is minimized, the slope (θ) of the tangent (TL) can be minimized. At this time, the slope (θ) of the tangent (TL) can gradually increase as it moves toward the first end (E1) of the second plated steel plate area (A20) along the first direction (B1). Accordingly, the slope (θ) of the tangent (TL) can be maximized at the first end (E1) of the second plated steel plate area (A20) where the compression depth (P1) is maximum. At this time, the slope of the tangent (TL) at the center (C') of the compression part (13) with respect to the first direction (B1) may have a magnitude between the maximum slope and the minimum slope described above. In this case, the compression part (13) can be formed such that the average slope of the tangent (TL) from the second end (E2) of the second plated steel plate area (A20) to the center (C') of the compression part (13) is 45° or less.

[0093] The second plated steel plate area (A20) may include two compression portions (13) on both sides of the plated steel plate (10). In this case, one of the two compression portions (13) (hereinafter referred to as the first compression portion) (13a) may be formed concavely downward from the upper surface of the second plating area (A22) and the second coating area (A25). Then, the other of the two compression portions (13) (hereinafter referred to as the second compression portion) (13b) may be formed concavely upward from the lower surface of the second plating area (A22) and the second coating area (A25). At this time, the first compression portion (13a) and the second compression portion (13b) may be arranged to face each other along the first direction (B1).

[0094] Meanwhile, for the sake of convenience of explanation, the first compression part (13a) and the second compression part (13b) are described based on the case where they are in opposite directions but have the same shape and size, but the present invention is not limited thereto.

[0095] The compression portion (13) can be formed by cutting the plated steel plate (10) after the compression processing is completed, or by compressing around the cut portion (14) after the plated steel plate (10) has been cut.

[0096] An example of cutting the plated steel plate (10) after the compression process is completed is specifically described in FIG. 7. In this case, the cutting section (14) can be formed by cutting along a direction parallel to the second direction (B2) passing through the center (C) of the compression section (13AA, 13BB in FIG. 10) before cutting. In addition, if two compression sections (13) are provided, the cutting section (14) can be formed by cutting along a direction parallel to the second direction (B2) passing through the common center (C) of the first compression section (13AA) and the second compression section (13BB) before cutting. By cutting in this manner, the cutting section (14) can be placed at the aforementioned second end (E2) of the second plated steel plate area (A20) in the plated steel plate (10) after the cutting process is completed.

[0097] Figure 6 is a cross-sectional view showing the galvanized steel plate of Figure 1 viewed from the side.

[0098] Referring to FIG. 6, the thickness of the second plated steel plate region (A20) may be 90% or less of the thickness of the steel plate substrate (11) of the first plated steel plate region (A10) (i.e., maximum thickness of the steel plate substrate). As a compression portion (13) is formed in the second plated steel plate region (A20) such that the compression depth (P1) changes along the first direction (B1), the thickness of the second plated steel plate region (A20) may also vary along the first direction (B1).

[0099] More specifically, the compressed portion (13) of the steel plate substrate (11) may have a maximum thickness at the first end (E1). Then, the thickness of the steel plate substrate (11) may gradually decrease as it moves toward the second end (E2) along the first direction (B1), so that it may have a minimum thickness (T3a) at the second end (E2). At this time, the maximum thickness of the compressed portion (13) of the steel plate substrate (11) may be 90% of the thickness of the steel plate substrate (11) in the first plated steel plate region (A10). Accordingly, the thickness of the second plated steel plate region (A20) between the first end (E1) and the second end (E2) may be smaller than the thickness of the first plated steel plate region (A10). The thickness (i.e., minimum thickness) at the second end (E2) of the second plated steel plate area (A20) may be 10% to 90% of the thickness of the steel plate substrate (11) of the first plated steel plate area (A10).

[0100] Additionally, during compression processing, the steel plate substrate (11) can be compressed along with the plating portion (12) and the coating portion (15) to reduce its thickness. At this time, the first steel plate area (A11) can have a minimum thickness (T3a) of the steel plate substrate (11) at the second end (E2) where the compression depth (P1) is maximum. In this case, the second end (E2) is the part where the cutting portion (14) is formed, and the thickness (T3a) of the steel plate substrate (11) of the first steel plate area (A11) at the cutting portion (14) becomes minimum. As a result, the area of ​​the steel plate substrate (11) exposed to the outside through the cutting portion (14) can be minimized. The length of the second plating section (12c) and the second coating section (15c) is calculated by excluding the thickness of the first plating section (12a, 12b) and the first coating section (15a, 15b) in the cutting section (14).

[0101] The width of the compression portion (13) may be 1 mm to 4 mm. The width of the second plated steel plate area (A20) may be greater than the compression depth (P1) of the compression portion (13). At this time, the width of the second plated steel plate area (A20) may be the same as the width (L1) of the compression portion (13). Accordingly, the compression portion (13) may have a shape in which the width (L1) is greater than the compression depth (P1). At this time, the width (L1) of the compression portion (13) may be, for example, 1 mm to 4 mm.

[0102] As described above, since the compression process is performed only on the second plated steel plate area (A20), the second plating area (A22) and the second coating area (A25) may have a greater density than the first plating area (A12) and the first coating area (A15). This may be the result of performing the compression process so as to press the plated steel plate (10) inward along the second direction (B2, Z) only on the second plating area (A22) and the second coating area (A25), which are parts of the plating portion (12) having the same or similar thickness before the compression process.

[0103] Additionally, when the compression process is performed, a portion of the steel plate substrate (11) corresponding to the second steel plate region (A21) is pressed together, so the second steel plate region (A21) may have a greater density than the first steel plate region (A11).

[0104] The thickness of the second plating area (A22) and the second coating area (A25) formed by the compression process may be thinner than the thickness of the first plating area (A12) and the second coating area (A25) that are not compressed. As described above, the compression part (13), which is in a curved shape, has a minimum slope (θ) of the tangent (TL) and a radius of curvature at the second end (E2) of the second plated steel plate area (A20), so that the second plating area (A22) and the second coating area (A25) can maintain a predetermined thickness at the second end (E2). That is, by compression processing the compression part (13) in a curved shape, it is possible to prevent the plating part (12) and the coating part (15) from being damaged or peeled off at the second end (E2) of the second plated steel plate area (A20) while the compression process is in progress.

[0105] The thickness of the second plating area (A22) and the second coating area (A25) may, for example, have the same or similar thickness overall along the longitudinal direction (first direction) (B1) of the second plating area (A22) and the second coating area (A25), but the present invention is not limited thereto. As another example, the thickness (T2a) of the second plating area (A22) and the thickness of the second coating area (A25) may have a thickness (second thickness) at the second end (E2) that is smaller than the thickness (first thickness) at the first end (E1). According to an embodiment, the second plating area (A22) and the second coating area (A25) may have a maximum thickness at the first end (E1) and decrease slightly along the first direction (B1) toward the second end (E2), so that the thickness at the second end (E2) becomes minimum. At this time, the density of the second plating area (A22) and the second coating area (A25) is maximized at the second end (E2) where the thickness is minimized, and the density can be minimized at the first end (E1) where the thickness is maximum.

[0106] FIG. 7(a) is a cross-sectional view showing a portion of a plated steel sheet before cutting according to another embodiment of the present invention, and FIG. 7(b) is a cross-sectional view showing the plated steel sheet of FIG. 7(a) after cutting.

[0107] Referring to FIG. 7, a plated steel sheet (10) according to another embodiment of the present invention may include a first plated steel sheet region (A10) and a second plated steel sheet region (A20). At this time, since the specific features of the first plated steel sheet region (A10) are identical or similar to those described above, redundant descriptions will be omitted, and the differences will be explained in detail.

[0108] First, as shown in FIG. 7(a), after the compression process is completed, a compression portion (13AA) may be formed only on the upper part of the plated steel sheet (10). At this time, the compression portion (13AA) is a compression portion before cutting and may have a wider width (2L1) than the compression portion (13) after the cutting process is completed. In this case, the lower part of the plated steel sheet (10) may be a flat shape where no compression process is performed.

[0109] In the case of a plated steel sheet (10) that has been cut, as shown in FIG. 7 (b), a single compression portion (13) may be included in the second plated steel sheet region (A20). In this case, since only one compression portion (13) is formed, the thickness of the steel sheet substrate (11) in the cutting portion (14) may have a thickness (T3) that is smaller than the maximum thickness of the steel sheet substrate (11).

[0110] Meanwhile, in the embodiments described above, for convenience of explanation, each region of the plated steel plate (10) was designated separately, but the first plated steel plate region (A10) and the second plated steel plate region may refer to each region of a single plated steel plate (10).

[0111]

[0112] FIG. 8 schematically illustrates the state before starting the manufacture of the plated steel sheet (10) according to the present invention. FIG. 9 schematically illustrates an example of a method for manufacturing the plated steel sheet (10) according to the present invention. FIG. 10 is a cross-sectional view illustrating the plated steel sheet (10) before it is cut after the compression process is completed.

[0113] Referring to FIGS. 8 to 10, a manufacturing device (20) for pressing and cutting a plated steel sheet (10) includes a first pressing unit (100) and a second pressing unit (200). In this case, the pressing units (100, 200) are arranged to face each other along the vertical direction (Z-axis direction).

[0114] Two compression units (100, 200) include a body (110, 210), a connecting part (120, 220), and a pressing part (130, 140). The body (110, 210) may be a pressing roll rotatable about each rotation axis (C1, C2). Additionally, the body (110, 120) may be arranged to be vertically movable along a second direction (B2).

[0115] The connecting portion (120, 220) may be connected to the body (110, 120). The connecting portion (120, 220) may be in the form of a pressure roll extending along the circumferential direction of the body (110, 120) and may be in the form of wrapping around the outer surface of the body (110, 120).

[0116] The pressure portion (130, 230) may be disposed on the outer surface of the connecting portion (120, 220). At this time, the pressure portion (130, 230) may have the same shape and size as the pre-cut compression portion (13AA, 13BB) as described above. More specifically, the pressure portion (130, 230) may have a protrusion distance (P2) that is the same or similar to the compression depth (P1) of the compression portion (13AA, 13BB). In addition, the pressure portion (130, 230) may have a width (L2) that is the same or similar to the pre-cut compression portion (13AA, 13BB). For example, to form a compression portion (13) having a width of 1 mm to 4 mm after the cutting process is completed, the pressure portion (130, 230) may have a width of 2 mm to 8 mm. These pressurizing parts (130, 230) can be arranged to face each other along the second direction (B2).

[0117] Meanwhile, in order to form a plurality of compression portions (13) on a plated steel plate (10) in a single compression process, the body (110, 210) may include a plurality of connecting portions (120, 220) and pressing portions (130, 230). In this case, the plurality of pressing portions (130, 230) may be arranged to face each other in a one-to-one manner.

[0118] Additionally, the manufacturing device (20) may further include a cutting device (not shown). The cutting device can cut the plated steel sheet (10) after the compression process is completed to adjust its length. At this time, the cutting device can cut the compression portions (13AA, 13BB) before cutting using a cutting cutter (not shown). For example, the cutting device can cut the common center (C) of two compression portions (13AA, 13BB) facing each other along the second direction (B2).

[0119] Referring again to FIGS. 8 to 10, the method of manufacturing a plated steel sheet (10) according to embodiments of the present invention using a plated steel sheet manufacturing device (20) may be as follows.

[0120] A method for manufacturing a plated steel sheet according to one embodiment of the present invention comprises the steps of: supplying a plated steel sheet (10) comprising a steel sheet substrate (11), a plating portion (12) located on one or both sides of the steel sheet substrate (11), and a coating portion (15) located on the surface of the plating portion (12); and cutting the plated steel sheet (10) to form a cut portion (14).

[0121] First, a plated steel sheet (10) can be supplied to a plated steel sheet manufacturing device (20). At this time, the plated steel sheet (10) supplied may have a flat upper and lower surface and may have an overall thickness (T1) that is the same or similar. That is, the plated steel sheet (10) before processing may be in a form that includes only the first plated steel sheet region (A10). Before being supplied to the manufacturing device (20), this plated steel sheet (10) may be in a wound state. When the manufacturing process begins, one end of the wound plated steel sheet (10) may be unwound and supplied between the compression units (100, 200).

[0122] Next, a cutting process can be performed to form a cutting portion (14) on the plated steel plate (10). In the cutting process step, a cutting cutter (not shown) can be used to simultaneously cut the first compression portion (13a) and the second compression portion (13b) arranged to face each other. At this time, the cutting cutter can cut along a direction parallel to the thickness direction (second direction) (B2) of the plated steel plate (10) while passing through the common center (C) of the compression portions (13a, 13b).

[0123] In one embodiment of the present invention, during the cutting process step, as the second plating area (A22) is cut by a cutting cutter, a portion of the plating material contained in the second plating area (A22) is moved onto the cutting portion (14), thereby forming a second plating portion (12c). This second plating portion (12c) may have a shape that extends along the second direction (B2), so as to cover at least partially the cutting portion (14). A second coating portion (15c) may also be formed on the second plating portion (12c). FIGS. 1 to 7 illustrate an example in which the second plating portion (12c) and the second coating portion (15c) are formed simultaneously.

[0124] Afterward, the plated steel sheet (10) from which the cutting process is completed can be transported for subsequent processes or manufacturing operations depending on its intended use.

[0125] After the step of supplying the plated steel sheet, the method may further include the step of forming a compressed portion by compressing the plated steel sheet.

[0126] During compression processing, pressure units (130, 230) that are rotationally driven by the body (110, 210) can press the upper and lower surfaces of the plated steel sheet (10). The supply time of the plated steel sheet (10) may be after the compression units (100, 200) start rotating, or simultaneously with the start of rotation.

[0127] More specifically, as the plated steel plate (10) passes between rotating pressure parts (130, 230), a first compression part (13a) may be formed at the upper end of the plated steel plate (10), and a second compression part (13b) may be formed at the lower end of the plated steel plate (10). At this time, the first compression part (13a) and the second compression part (13b) may be formed at positions facing each other along the second direction (B2). Through this compression process, the first plated steel plate area (A10) and the second plated steel plate area (A20) may be formed in the plated steel plate (10) so as to be continuous with each other along the width direction (first direction) (B1). At this time, the second plated steel plate area (A20) may not have a cutting part (14) formed therein.

[0128] Meanwhile, in the compression process step, the pressure (compression pressure) applied by the compression unit (100, 200) to the plated steel plate (10) can be adjusted to match the shape of the plated steel plate (10) to be manufactured. The compression pressure can be adjusted, for example, within a range of 5 kg / cm² to 300 kg / cm², but is not limited thereto. Based on such compression pressure, the width (L1) and compression depth (P1) of the compression part (13) can be changed. For example, if the pressure applied to the plated steel plate (10) increases or decreases, the width (L1) [or the width of the second plated steel plate area] and compression depth (P1) of the compression part (13) can increase or decrease in proportion to this.

[0129] Additionally, since the thickness (T3) of the cut portion (14) formed through the cutting process step is determined by the thickness of the second plated steel plate area (A20), the thickness (T3) of the cut portion (14) can also be changed based on the compression pressure. For example, if the applied compression pressure increases or decreases, the thickness (T3) of the cut portion (14) may decrease or increase in inverse proportion to this. Accordingly, the area of ​​the second steel plate area (A21) exposed to the outside through the cut portion (14) can be determined.

[0130] The compression process step may also be performed after the step of forming the cut section. The specific description of the compression process is the same as that previously described, so it is omitted.

[0131] The plated steel sheet (10) according to the embodiments of the present invention as described above can minimize the area of ​​the steel sheet substrate (11) exposed to the outside by cutting. By doing so, the time for rust to occur in the cut portion is delayed, thereby allowing the plated steel sheet (10) to retain improved corrosion resistance even after cutting.

[0132] In addition, when the compression process is performed, the compression portion (13) is formed in an inwardly curved shape on the plated steel plate (10), so that damage such as damage or peeling of the plating portion (12) can be prevented during the compression process compared to cases where the compression process is performed using a conventional sharp shape structure. Furthermore, when the compression process is performed, by applying pressure using a curved pressing portion (130, 230) corresponding to the compression portion (13), the thickness and plating amount in the compression portion (13) do not decrease rapidly, thereby further improving the corrosion resistance of the plated steel plate (10).

[0133]

[0134] A plated steel sheet according to one embodiment of the present invention (hereinafter referred to as “Example 2”) comprises: a steel sheet substrate; a plating portion located on the steel sheet substrate; a coating portion located on the plating portion; a cut portion where the steel sheet substrate is cut; a compression portion adjacent to the cut portion having a thickness of 90% or less of the maximum thickness of the steel sheet substrate; and an uncompressed portion adjacent to the compression portion where the steel sheet substrate is not compressed.

[0135] The plating section comprises: a first plating section located on the upper or lower surface of the uncompressed portion of the steel sheet substrate; a second plating section located on the upper or lower surface of the compressed portion; and a third plating section located on the upper surface of the cutting portion.

[0136] The coating section includes a first coating section located on a first plating section; a second coating section located on a second plating section; and a third coating section located on a third plating section.

[0137] In the case of Example 2, the compression portion is an essential component of the above-mentioned example. The uncompressed portion refers to a part adjacent to the compression portion where the steel plate substrate is not compressed, that is, a part having a thickness exceeding 90% of the maximum thickness of the steel plate substrate.

[0138] In the above embodiment, the first plating section (12a, 12b) is divided into a plating section (first plating section) located in the first plating area (A12) and a plating section (second plating section) located in the second plating area (A22) in Example 2, and the plating section (12c) located on the upper surface of the cut section becomes the third plating section.

[0139] In addition, the coating section is similarly divided into the first coating section (15a, 15b) located in the first coating area (A15) and the second coating section located in the second coating area (A25) in Example 2, and the coating section (15c) located on the upper surface of the cutting section becomes the third coating section.

[0140] As the compressed section, uncompressed section, plated section, and painted section are as described above, redundant explanations are omitted.

[0141] The third plating section can be formed for more than 10% of the total length of the cut section.

[0142] The second plating portion adjacent to the cut portion may include a crack.

[0143] There may be 0 to 3 cracks per 0.5 mm length in the direction perpendicular to the thickness of the steel plate.

[0144] The second coating portion adjacent to the cut portion may include a crack.

[0145] There may be 0 to 3 cracks per 0.5 mm length in the direction perpendicular to the thickness of the steel plate.

[0146] A second coating portion adjacent to the cutting portion may include a peeling portion.

[0147] The peeled portions may have a height of 2㎛ or more and may be 0 to 5 per 0.1mm length in the direction perpendicular to the thickness of the steel plate.

[0148]

[0149] The present invention will be explained in more detail below through examples. However, these examples are merely for illustrating the invention and the invention is not limited thereto.

[0150]

[0151] Examples

[0152] The plating layer consists of 1.5% aluminum, 1.5% magnesium, and the remainder being zinc by weight, with a plating weight of 120 g / m² on both sides. The thickness of the steel sheet substrate is 0.8 mm, and it has a tensile strength of 340 MPa. A plated steel sheet was prepared with a liquid coating layer, a polyester composition, and a thickness of 25 μm.

[0153] When pressing the galvanized steel sheet, the width of the pressed portion was rolled to 2 mm, and the pressing pressure was adjusted as shown in Table 1 below. Afterwards, the center of the pressed portion was cut to manufacture the galvanized steel sheet.

[0154] The length of the cut section (T3a), the length of the second plating section (12c) relative to the length of the cut section (T3a), the number of cracks per 0.5 mm length, and the number of peeled sections per 0.1 mm length were observed by magnifying them 100 times using a scanning electron microscope (SEM) and summarized in Table 1 below.

[0155] In addition, the corrosion resistance of the cross-section of the test specimen was evaluated using the accelerated test method of the international standard ISO 14993.

[0156] Classification Compression Pressure (kg / cm²) Cut Section Length (T3a, mm) 2nd Plating Section / Cut Section Length (%) Number of Cracks Number of Stripped Sections Time to Recover (cycles(hr)) 1 Compression Process X 0.8000 120(960) 2 100.77 3.81 1120(960) 3 200.72 10.02 1180(1440) 4 300.51 36.32 2240(1920) 5 500.138 3.856 120(960)

[0157] As shown in Table 1, it can be confirmed that corrosion resistance is significantly improved by properly forming a second plating layer on the cut portion.

[0158] [Explanation of the symbol]

[0159] 10: Galvanized steel sheet, 11: Steel sheet substrate,

[0160] 12: Plating section, 13: Pressing section,

[0161] 14: Cutting section, 15: Painting section,

[0162] 20: Steel plate manufacturing device, A10: First plated steel plate area,

[0163] A11: First steel plate area, A12: First plating area,

[0164] A15: 1st coating area, A20: 2nd plated steel sheet area,

[0165] A21: Second steel plate area, A22: Second plating area,

[0166] A25: Second painting area

Claims

1. Steel plate material; A plating portion located on the above steel plate substrate; A coating portion located on the above-mentioned plating portion; and The above steel plate substrate includes a cut portion, and The plating portion includes a first plating portion located on the upper or lower surface of the steel plate substrate and a second plating portion located on the upper surface of the cutting portion. A plated steel sheet comprising a first coating portion located on the first plating portion.

2. In Paragraph 1, A plated steel sheet, wherein the second plating portion is formed for at least 10% of the total length of the cut portion.

3. In Paragraph 1 or 2, A plated steel sheet having a crack in the first plating portion adjacent to the above-mentioned cutting portion.

4. In Paragraph 3, The above-mentioned cracks are 0 to 3 per 0.5 mm length in the direction perpendicular to the thickness of the steel plate, in a plated steel plate.

5. In any one of paragraphs 1 through 4, A plated steel sheet having a crack in the first coating portion adjacent to the above-mentioned cutting portion.

6. In Paragraph 5, The above-mentioned cracks are 0 to 3 per 0.5 mm length in the direction perpendicular to the thickness of the steel plate, in a plated steel plate.

7. In any one of paragraphs 1 through 6, A plated steel sheet, wherein the first coating portion adjacent to the above-mentioned cutting portion includes a peel portion.

8. In Paragraph 7, A plated steel sheet having a height of 2㎛ or more and 0 to 5 pieces per 0.1mm length in the direction perpendicular to the thickness of the steel sheet.

9. In any one of paragraphs 1 through 8, A plated steel sheet comprising a compression portion adjacent to the above-mentioned cutting portion and having a thickness of 90% or less of the maximum thickness of the steel sheet substrate.

10. In Paragraph 9, The above-mentioned compression portion is a plated steel plate in which the thickness of the steel plate substrate decreases as it moves toward the cutting portion in the direction perpendicular to the thickness of the steel plate.

11. In Paragraph 9 or 10, A plated steel plate in which the above-mentioned compression portion is curved in the direction opposite to the cutting portion in the direction perpendicular to the thickness of the steel plate.

12. In any one of paragraphs 9 through 11, A plated steel plate in which the slope of the interface between the steel plate substrate and the first plating portion changes as it moves toward the cutting portion in the direction perpendicular to the thickness of the steel plate.

13. In any one of paragraphs 9 through 12, A plated steel sheet having a width of 1 mm to 4 mm for the above-mentioned compression portion.

14. A step of supplying a plated steel plate comprising a steel plate substrate, a plating portion located on one or both sides of the steel plate substrate, and a coating portion located on the surface of the plating portion; and The step of cutting the plated steel plate to form a cut portion; is included. A method for manufacturing a plated steel sheet, wherein a second plating portion is formed on the upper surface of the cutting portion during the step of forming the cutting portion.

15. In Paragraph 14, A method for manufacturing a plated steel sheet, further comprising the step of forming a compressed portion by pressing the plated steel sheet after the step of supplying the plated steel sheet.

16. In Paragraph 14 or 15, A method for manufacturing a plated steel sheet, further comprising the step of forming a cut portion, and then forming a compressed portion by pressing the plated steel sheet.

17. In Paragraph 15 or 16, In the step of forming the above-mentioned compression portion, A method for manufacturing a plated steel sheet, wherein a compression portion is formed that is concave inwardly along the thickness direction of the steel sheet, and the width is greater than the compression depth.

18. In any one of paragraphs 15 through 17, In the step of forming the above-mentioned compression portion, A method for manufacturing a galvanized steel sheet, wherein the compression pressure applied to the steel sheet is 5 kg / cm² to 300 kg / cm².

19. In any one of paragraphs 15 through 18, In the step of forming the above-mentioned cutting portion, A method for manufacturing a plated steel sheet, wherein the above-mentioned cutting portion is formed to pass through the center in the width direction of the above-mentioned pressing portion.

20. In any one of paragraphs 15 through 19, In the step of forming the above-mentioned cutting portion, A method for manufacturing a plated steel sheet in which the plating portion occupies at least 10% of the total length of the cut portion.

21. Steel plate material; A plating portion located on the above steel plate substrate; A coating portion located on the above-mentioned plating portion; A cut portion of the above steel plate substrate; A compression portion adjacent to the above-mentioned cutting portion, having a thickness of 90% or less of the maximum thickness of the above-mentioned steel plate substrate; It includes an uncompressed portion adjacent to the above-mentioned compression portion where the steel plate substrate is not compressed, and The above plating part is, A first plating portion located on the upper or lower surface of the uncompressed portion of the above steel plate substrate; A second plating portion located on the upper or lower surface of the above-mentioned compression portion; and It includes a third plating portion located on the upper surface of the above-mentioned cutting portion; and The above-mentioned coating part is, A first coating part located on the first plating part above; A second coating portion located on the second plating portion above; and A plated steel sheet comprising a third coating portion located on the third plating portion.

22. In Paragraph 21, A plated steel sheet in which the third plating portion is formed for at least 10% of the total length of the cut portion.

23. In Paragraph 21 or 22, A plated steel sheet having a crack in the second plating portion adjacent to the above-mentioned cutting portion.

24. In Paragraph 23, The above-mentioned cracks are 0 to 3 per 0.5 mm length in the direction perpendicular to the thickness of the steel plate, in a plated steel plate.

25. In any one of paragraphs 21 through 24, A plated steel sheet having a crack in the second coating portion adjacent to the above-mentioned cutting portion.

26. In Paragraph 25, The above-mentioned cracks are 0 to 3 per 0.5 mm length in the direction perpendicular to the thickness of the steel plate, in a plated steel plate.

27. In any one of paragraphs 21 through 26, A plated steel sheet, wherein the second coating portion adjacent to the above-mentioned cutting portion includes a peel portion.

28. In Paragraph 27, A plated steel sheet having a height of 2㎛ or more and 0 to 5 pieces per 0.1mm length in the direction perpendicular to the thickness of the steel sheet.

Images