JP2021115604A - Plated steel sheet with embossed part, and method for forming embossed part on plated steel sheet - Google Patents

Abstract

To provide a plated steel sheet with an embossed part; and to provide a method for forming an embossed part on a plated steel sheet.SOLUTION: In a plated steel sheet 1 with an embossed part 6, an embossed depth from the surface of the plated steel sheet 1 on a non-embossed part to the bottom of the embossed part 6 is 60 μm or less. Further, when forming an embossed part 6 on the plated steel sheet 1, the plated steel sheet 1 is rolled so that an embossed depth from the surface of the plated steel sheet 1 to the bottom of the embossed part 6 becomes 60 μm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a plated steel sheet having an embossed portion and a method of forming an embossed portion on the plated steel sheet.

Conventionally, embossed steel sheets have been known for the purpose of enhancing design and functionality. The type of steel sheet to be embossed is generally, for example, ordinary steel or stainless steel.

For example, Patent Document 1 discloses an embossed surface so that the sticking paper on the surface can be easily removed.

Further, Patent Document 2 discloses a steel sheet having an embossed surface in order to realize a steel sheet having excellent slip resistance.

JP-A-2002-66657 Japanese Unexamined Patent Publication No. 2000-129411

By the way, when a steel sheet is used outdoors, for example, excellent corrosion resistance is required. Therefore, as a steel sheet used outdoors, for example, a galvanized steel sheet in which a zinc-based metal is plated on the surface of ordinary steel is used. Will be done.

However, when the plated steel sheet is embossed, cracks occur in the plating layer or, if the plating layer is coated with a film, or the plating layer or the above-mentioned film is peeled off from the base steel sheet. Probability is high. Therefore, there are almost no examples of application of embossing to plated steel sheets.

The present invention has been made in view of these points, and an object of the present invention is to provide a plated steel sheet having an embossed portion and a method for forming an embossed portion on the plated steel sheet.

(1) The plated steel sheet having an embossed portion according to the present invention is characterized in that the embossing depth from the surface of the plated steel sheet to the bottom of the embossed portion is 60 μm or less.

According to the plated steel sheet of (1) above, when the plating layer or the plating layer is coated with a coating, cracks may occur in the coating, or the plating layer or the coating may peel off from the base steel plate. This can be suppressed, and a plated steel sheet having an embossed portion can be provided.

(2) In the plated steel sheet according to (1) above, the embossed portion has a concave portion having a radius of curvature of 0.15 mm or more between the surface of the plated steel sheet and the bottom of the embossed portion. It is preferably formed.

According to the plated steel sheet of the above (2), it is possible to further suppress the generation of cracks in the plating layer and the coating film, and the peeling of the plating layer and the coating film from the base steel sheet.

(3) The method for forming an embossed portion on a plated steel sheet of the present invention is characterized in that the plated steel sheet is rolled so that the embossing depth from the surface of the plated steel sheet to the bottom of the embossed portion is 60 μm or less. do.

According to the method of forming an embossed portion on the plated steel sheet of (3) above, if the plating layer or the plating layer is coated with a coating, cracks may occur in the coating, or the plating layer or the above may be formed from the base steel plate. It is possible to prevent the coating film from peeling off.

(4) In the method of forming an embossed portion on a plated steel sheet of the present invention, a concave portion having a radius of curvature of 0.15 mm or more is formed between the surface of the plated steel sheet and the bottom of the embossed portion. It is characterized in that the plated steel sheet is rolled so as to be performed.

According to the method of forming an embossed portion on the plated steel sheet of (4), cracks are further suppressed from the plating layer and the coating film, and peeling of the plating layer and the coating film from the base steel sheet is further suppressed. It becomes possible to do.

According to the present invention, it is possible to provide a plated steel sheet having an embossed portion and a method for forming an embossed portion on the plated steel sheet.

(A) An example of a schematic view showing an enlarged part of a cross section of a base steel sheet before embossing, and (B) a schematic view showing a part of a cross section of a plated steel sheet after embossing. This is an example. This is an example of a list showing test conditions for forming an embossed portion on a plated steel sheet. It is a graph which shows an example of the verification result of the presence or absence of white rust that performed the salt spray test using the embossed test piece. It is an image which shows an example of the state in which white rust was generated in the vicinity of the concave portion of the embossed portion after the salt spray test. This is an example of a graph showing the relationship between the uneven step D of the embossed test piece and the white rust occurrence rate, and was created based on FIG. This is an example of a graph showing the relationship between the radius of curvature of the concave portion of the embossed portion of the embossed test piece and the white rust occurrence rate, and was created based on FIG.

As an embodiment of the present invention, a plated steel sheet having an embossed portion and a method of forming the embossed portion on the plated steel sheet will be described below.

The embossing is generally performed by, for example, rolling, pressing, rolling, shot blasting, etching, etc., but in the present embodiment, the plated steel sheet is embossed by rolling using an embossing roll. An example of the case will be described.

FIG. 1A is an example of a schematic view showing an enlarged part of a cross section of the base steel plate 2 before being embossed. The plated steel sheet 1 in the present embodiment has a base steel sheet 2, a plating layer 3 coated on the surface of the base steel sheet 2, and a coating film 4 coated on the surface of the plating layer 3. The film 4 may be, for example, an organic resin film or an inorganic resin film. Further, although the case where the coating sheet 4 is coated in the plated steel sheet 1 in the present embodiment is described as an example, the plated steel sheet 1 may be one in which the coating film 4 is not coated.

In the present embodiment, for example, a black plated steel sheet, which is a zinc-based plated steel sheet, is used as the plated steel sheet 1 to be embossed. The black-plated steel sheet contains Al: 0.1 to 22.0% by mass and Mg: 0.1 to 10.0% by mass on the surface of the base steel sheet 2 and the base steel sheet 2, and the black oxidation of Zn. It has a molten Al and Mg-containing Zn plating layer 3 in which a substance is distributed in the plating layer.

Next, the plated steel sheet 1 on which the embossed portion 6 is formed by the embossing process will be described together with the embossing roll 30 for forming the embossed portion 6.

FIG. 1B is an example of a schematic view showing an enlarged part of a cross section of the plated steel sheet 1 after being embossed. In addition, in FIG. 1B, for convenience of explanation, a part of the cross section of the embossed roll 30 is also enlarged and shown. A concave embossed portion 6 and a flat flat portion 7 are formed on the surface portion other than the embossed portion 6 on the surface of the plated steel sheet 1 after the embossing process. The flat portion 7 is a non-embossed portion that is a portion other than the embossed portion 6 on the surface of the plated steel sheet 1. The embossed portion 6 is formed by pressing the roll convex portion 31, which will be described later, against the surface of the plated steel sheet 1.

The embossed portion 6 is formed in the embossing forming step in which the plated steel sheet 1 is rolled. In the embossing step, the plated steel sheet 1 having the concave embossed portion 6 is formed by rolling with the embossing roll 30.

The embossed portion 6 has an embossed bottom portion 21 formed as a bottom portion of the concavely formed embossed portion 6, and an embossed portion 6 formed as a side surface portion of the embossed portion 6 from the embossed bottom portion 21 to the flat portion 7 of the plated steel sheet 1. It has a side portion 22 and a concave portion 23 that smoothly connects the embossed bottom portion 21 and the embossed side portion 22 with a predetermined radius of curvature.

In the present specification, the distance (that is, the embossing depth) from the flat portion 7 of the plated steel sheet 1 shown in FIG. 1B to the embossed bottom portion 21 is referred to as an uneven step D. Strictly speaking, in one embossed portion 6, the distance from the flat portion 7 to the embossed bottom portion 21 is not always constant. Therefore, here, the average distance from the flat portion 7 to the embossed bottom portion 21 is defined as the uneven step D. ..

As shown in FIG. 1B, the embossed roll 30 has a plurality of roll convex portions 31 protruding from the outer peripheral surface of the embossed roll 30. The roll convex portion 31 has a top portion 32 formed in a flat surface shape at the tip portion portion, and a convex curved portion 33 formed as a curved surface having a predetermined radius of curvature at the edge portion of the top portion 32. The convex portion 33 is a portion for forming the concave portion 23 of the embossed portion 6 on the plated steel plate 1.

Next, an evaluation on corrosion resistance performed for the purpose of clarifying the conditions for embossing the plated steel sheet 1 that suppresses the occurrence of white rust will be described. In the evaluation of corrosion resistance, a salt spray test (SST test) based on JIS Z2371 was performed using a plated steel sheet 1 embossed with an embossed roll 30. In the salt spray test, a 5% NaCl aqueous solution at 35 ° C. is sprayed on the surface of the plated steel sheet 1 having the embossed portion 6, and it is visually confirmed whether or not white rust is generated after 24 hours and 48 hours. I went there. In the salt spray test, it was determined that white rust had occurred when white rust was confirmed on the plated steel sheet 1 in appearance. Further, when no white rust was confirmed on the surface of the plated steel sheet 1, it was judged that no white rust was generated. Further, even if the occurrence of white rust was not confirmed 24 hours after the spraying of the NaCl aqueous solution, it was determined that the white rust had occurred when the occurrence of white rust was confirmed in 48 hours.

FIG. 2 is an example of a list showing test conditions for forming the embossed portion 6 on the plated steel sheet 1. In the salt spray test, a black-plated steel sheet having a thickness of 0.8 mm, a width of 60 mm, and a length of 1000 mm was used. Further, the embossing roll 30 for forming the embossed portion 6 on the plated steel sheet 1 was 110 mm in diameter.

Regarding the wire load of the embossed roll 30 (also referred to as roll wire load) in the present embodiment, a load was applied to the plated steel sheet 1 at 0.6 kN / mm to 1.6 kN / mm. At this time, for example, it is possible to increase the uneven step D formed in the embossed portion 6 by increasing the roll wire load and rolling. Further, it is also possible to reduce the uneven step D formed in the embossed portion 6 by reducing the roll wire load and rolling.

When the embossed portion 6 was formed on the plated steel sheet 1 by the embossing roll 30, the rolling speed was 1 m / min. It should be noted that the uneven step D can be increased or decreased by changing the magnitude of the roll wire load as described above, but the rolling speed can be changed or the embossed portion 6 can be increased or decreased. It is also possible to change the hardness of the steel plate forming the above.

When the plated steel sheet 1 was rolled by the emboss roll 30, the rolling oil was not used. Further, the rolling of the plated steel sheet 1 by the embossing roll 30 was performed by setting the number of passes to one.

FIG. 3 is a graph showing an example of verification results of the presence or absence of white rust generated by performing a salt spray test using an embossed test piece. In FIG. 3, the uneven step D formed on the test piece is shown on the horizontal axis, and the radius of curvature of the concave portion 23 formed on the test piece is shown on the vertical axis. The test piece used for the salt spray test is embossed using four types of embossing rolls 30 having a radius of curvature of the convex portion 33 of 0.02 mm, 0.08 mm, 0.18 mm and 0.40 mm. The thickness of the steel plate used for the test piece is 0.8 mm.

In the present embodiment, 22 test pieces embossed using the embossing roll 30 having a radius of curvature of the convex portion 33 of 0.02 mm are produced, and the embossing roll 30 having the radius of curvature of the convex portion 33 having a radius of curvature of 0.08 mm is produced. 35 test pieces embossed using this were prepared, and 27 test pieces embossed using an embossed roll 30 having a radius of curvature of the convex portion 33 of 0.18 mm were prepared. Twenty-seven test pieces embossed using a 0.40 mm embossed roll 30 were prepared. Then, a salt spray test was conducted using these test pieces.

The uneven step D of the test piece embossed using the embossing roll 30 having a radius of curvature of the convex portion 33 of 0.02 mm is within the range of 0.04 mm to 0.15 mm, and the radius of curvature of the convex portion 33 is 0. The uneven step D of the test piece embossed using the .08 mm embossed roll 30 is within the range of 0.04 mm to 0.16 mm, and the convex portion 33 is embossed using the embossed roll 30 having a radius of curvature of 0.18 mm. The uneven step D of the test piece was 0.03 mm to 0.06 mm, and the uneven step D of the test piece embossed using the embossing roll 30 having a radius of curvature of the convex portion 33 of 0.40 mm was 0.02 mm. It was in the range of ~ 0.06 mm. However, the value of the uneven step D is rounded off to the third decimal place.

Further, the radius of curvature of the concave portion 23 of the test piece embossed using the emboss roll 30 having the radius of curvature of the convex portion 33 of 0.02 mm is within the range of 0.04 mm to 0.07 mm, and the convex portion 23 has a radius of curvature of 0.04 mm to 0.07 mm. The radius of curvature of the concave portion 23 of the test piece embossed using the emboss roll 30 having a radius of curvature of 0.08 mm is within the range of 0.06 mm to 0.13 mm, and the radius of curvature of the convex portion 33 is 0.18 mm. The radius of curvature of the concave portion 23 of the test piece embossed using the emboss roll 30 is in the range of 0.24 mm to 0.54 mm, and the radius of curvature of the convex portion 33 is 0.40 mm. The radius of curvature of the concave portion 23 of the processed test piece was in the range of 0.47 mm to 2.09 mm. However, the value of the radius of curvature of the concave portion 23 is rounded off to the third decimal place.

In FIG. 3, the hatched region shows the region where the test pieces in which white rust did not occur in the salt spray test are distributed. That is, when embossing is performed using an embossing roll 30 having a radius of curvature of the convex portion 33 of 0.18 mm, and when embossing is performed using an embossing roll 30 having a radius of curvature of 0.40 mm of the convex portion 33. It was possible to suppress the occurrence of white rust in the salt spray test. On the other hand, in the test piece outside the hatched region of FIG. 3, white rust occurred in the salt spray test. Although not shown in FIG. 3, it is a person skilled in the art that white rust occurs in the salt spray test in the range where the uneven step D is larger than 0.08 mm and the radius of curvature of the concave portion is larger than 0.2 mm. It is self-evident among.

FIG. 4 is an image showing an example of a state in which white rust 8 is generated in the vicinity of the concave portion 23 of the embossed portion 6 after the salt spray test. FIG. 4 shows an enlarged photograph of the surface of the plated steel sheet 1 after the salt spray test. In FIG. 4, it can be confirmed that the occurrence is mainly in the vicinity of the edge portion of the embossed portion 6, more specifically, in the embossed side portion 22 and the concave curved portion 23. It is probable that the white rust 8 is generated in the vicinity of the embossed portion 6 because the coating 4 of the plated steel sheet 1 is stretched or bent by the embossing to cause cracks in the coating 4. When cracks occur in the plating layer 3, it is considered that the coating film 4 is naturally damaged.

By the way, referring to FIG. 3, it is presumed that the uneven step D (both refer to FIG. 1B) of the embossed portion 6 formed on the plated steel sheet 1 affects the generation of white rust 8. Further, it is presumed that the radius of curvature of the concave portion 23 of the embossed portion 6 formed on the plated steel sheet also affects the generation of white rust 8. In the following, first, the relationship between the uneven step D and the white rust occurrence rate will be considered, and then the relationship between the radius of curvature of the concave portion 23 of the embossed portion 6 formed on the plated steel sheet 1 and the white rust occurrence rate. Consider.

FIG. 5 is an example of a graph showing the relationship between the uneven step D of the embossed test piece and the white rust occurrence rate, and was created based on FIG. The value of the uneven step D shown on the horizontal axis in FIG. 5 is rounded off to the third decimal place. Further, the ratio shown on the vertical axis of FIG. 5 is the number of test pieces in which white rust 8 did not occur in each value of the uneven step D, and the number of test pieces in which the presence or absence of white rust 8 was evaluated was evaluated. It is the value divided by the number.

As shown in FIG. 5, as a result of performing a salt spray test using the above-mentioned test piece, when the uneven step D formed on the test piece exceeds 0.06 mm (more specifically, 0.063 mm). , White rust 8 was generated in all the test pieces. On the other hand, it was confirmed that the proportion of the test pieces in which the white rust 8 did not occur increased sharply when the uneven step D was 0.06 mm. This is because the uneven step D of the embossed portion 6 formed on the plated steel sheet 1 is reduced, so that the plating layer 3 of the plated steel sheet 1 and the film 4 when the plating layer 3 is covered with the film 4 are applied. It is considered that the rolling of the embossed roll 30 prevented the embossing roll 30 from being excessively stretched and suppressed the occurrence of cracks.

To elaborate on the results of the salt spray test shown in FIG. 5, the salt spray test was performed in the range where the value of the uneven step D was 0.04 mm to 0.06 mm (more specifically, 0.063 mm). Of the 45 test pieces, 29 test pieces did not generate white rust 8. In FIG. 5, the result of the salt spray test performed using the test piece having the uneven step D value of 0.04 mm to 0.06 mm is shown as the result when the uneven step D value is 0.05 mm. did.

Further, when the value of the uneven step D was less than 0.04 mm, white rust 8 did not occur in 24 of the 29 test pieces subjected to the salt spray test. That is, when the uneven step D was 0.04 mm or less, the ratio of the number of test pieces in which the white rust 8 did not occur was 0.83. In FIG. 5, the ratio of the number of test pieces in which the white rust 8 did not occur when the value of the uneven step D was 0.04 mm or less was shown as the result when the value of the uneven step D was 0.03 mm.

FIG. 6 is an example of a graph showing the relationship between the radius of curvature of the concave portion 23 of the embossed portion 6 of the embossed test piece and the white rust occurrence rate, which was created based on FIG. be. For convenience of explanation, the value of the radius of curvature of the concave portion 23 is rounded to the fourth decimal place for values less than 0.2 mm, and rounded to the second decimal place for values of 0.2 mm or more. It is a value. Further, the ratio shown on the vertical axis of FIG. 6 evaluates the number of test pieces in which white rust 8 did not occur at each value of the radius of curvature of the concave portion 23, and evaluates the presence or absence of white rust 8. It is a value divided by the number of test pieces.

As shown in FIG. 6, as a result of performing a salt spray test using the above-mentioned test piece, when the radius of curvature of the concave portion 23 formed on the test piece is 0.132 mm or less, white rust 8 is formed on the test piece. Was confirmed to occur. On the other hand, it was confirmed that the proportion of the test pieces in which the white rust 8 did not occur increased sharply when the radius of curvature of the concave portion 23 was 0.132 mm. This is because the ductility of the base steel plate 2 and the plating layer 3 or the coating 4 is different due to the local bending of the concave portion 23 in the embossed portion 6, and the base steel plate 2 and the plating layer 3 or / It is considered that this is because the peeling from the coating film 4 could be suppressed.

To elaborate on the results of the salt spray test shown in FIG. 6, white rust 8 did not occur in all the test pieces having the radius of curvature of the concave portion 23 of 0.2 mm or more. On the other hand, when the radius of curvature of the concave portion 23 was in the range of 0.034 mm to 0.132 mm, white rust 8 was generated in all 68 test pieces subjected to the salt spray test.

According to the embodiments described above, the following inventions can be provided.

The plated steel sheet 1 having the embossed portion 6 according to the present invention has an embossing depth of 60 μm or less from the surface thereof to the bottom portion of the embossed portion 6. In this case, it is considered that the rolled plated steel sheet 1 does not have the plating layer 3 and the coating 4 excessively stretched, cracks occur in the plating layer 3 and the coating 4, and the base steel plate 2 to the plating layer 3 It is possible to prevent the coating film 4 from peeling off. As a result, it is possible to provide the plated steel sheet 1 having an embossed portion even when excellent corrosion resistance is required, for example, when used outdoors.

The plated steel sheet 1 having the embossed portion 6 according to the present invention has a concave portion 23 having a radius of curvature of 0.15 mm or more formed from the surface thereof to the bottom portion of the embossed portion 6. In this case, it is possible to further suppress the generation of cracks in the plating layer 3 and the coating film 4 and the peeling of the plating layer 3 and the coating film 4 from the base steel plate 2. In particular, it is considered to be effective in suppressing peeling between the base steel plate 2 and the plating layer 3 and / and the coating 4 caused by the difference in ductility between the base steel plate 2 and the plating layer 3 and the coating film 4.

In the method of forming an embossed portion on the plated steel sheet of the present invention, the plated steel sheet 1 is rolled so that the embossing depth from the surface of the plated steel sheet 1 to the bottom of the embossed portion 6 is 60 μm or less. In this case, when the plated steel sheet 1 is rolled, it is considered that the plating layer 3 and the coating film 4 do not become excessively stretched, cracks occur in the plating layer 3 and the coating film 4, or the plating layer from the base steel sheet 2 is plated. It is possible to prevent the 3 and the coating film 4 from peeling off. As a result, it is possible to provide a method for forming an embossed portion on a plated steel sheet that can be used in a situation where excellent corrosion resistance is required, such as outdoors.

In the method of forming the embossed portion on the plated steel sheet of the present invention, the concave portion 23 having a radius of curvature of 0.15 mm or more is formed from the surface of the plated steel sheet 1 to the bottom of the embossed portion 6. The plated steel sheet 1 is rolled. In this case, it is possible to further suppress the generation of cracks in the plating layer 3 and the coating film 4 and the peeling of the plating layer 3 and the coating film 4 from the base steel plate 2.

1 Plated steel plate 6 Embossed part 21 Embossed bottom part 23 Concave part

Claims (4)

A plated steel sheet with an embossed portion
A plated steel sheet having an embossing depth of 60 μm or less from the surface of the plated steel sheet to the bottom of the embossed portion. In the plated steel sheet according to claim 1,
The embossed portion is a plated steel sheet in which a concave portion having a radius of curvature of 0.15 mm or more is formed between the surface of the plated steel sheet and the bottom of the embossed portion. It is a method of forming an embossed portion on a plated steel sheet.
A method for forming an embossed portion on a plated steel sheet, which comprises rolling the plated steel sheet so that the embossing depth from the surface of the plated steel sheet to the bottom of the embossed portion is 60 μm or less. In the method of forming an embossed portion on a plated steel sheet according to claim 3.
The plated steel sheet is rolled so that a concave portion having a radius of curvature of 0.15 mm or more is formed between the surface of the plated steel sheet and the bottom of the embossed portion. How to form an embossed part.

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