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KR-20260066780-A - Hot-dip galvanized steel and method for manufacturing hot-dip galvanized steel

KR20260066780AKR 20260066780 AKR20260066780 AKR 20260066780AKR-20260066780-A

Abstract

This hot-dip galvanized steel is a hot-dip galvanized steel having a steel and a plating layer having a predetermined chemical composition formed on the surface of the steel, wherein the thickness of the plating layer is 5 μm or more, and the plating layer has a first region and a second region and satisfies the following equations (1) to (6). Ra_A≤10.0 … (1), Ra_B≤10.0 … (2), 1.5≤|Ra_A-Ra_B| … (3), 150≤HV_x≤350 … (4), 200≤HV_max … (5), 0.80≤HV_big/HV_sml≤1.50 … (6).

Inventors

  • 다나카 도모히토
  • 도쿠다 고헤이
  • 고히가시 유스케
  • 우라나카 마사아키

Assignees

  • 닛폰세이테츠 가부시키가이샤

Dates

Publication Date
20260512
Application Date
20241108
Priority Date
20231110

Claims (7)

  1. A steel material and a hot-dip galvanized steel material having a plating layer formed on the surface of the steel material, The average chemical composition of the above plating layer is, in mass%, Al: greater than 10.0%, less than 40.0%, Mg: greater than 4.0%, less than or equal to 15.0%, Si: 0% or more, 1.00% or less, Sn: 0% or more, 0.7% or less, Bi: 0% or more, 0.3% or less, In: 0% or more, 0.3% or less, Total amount of Sn, Bi, and In ΣX: 0% or more, 0.7% or less, Ca: 0% or more, 0.60% or less, Y: 0% or more, 0.30% or less, La: 0% or more, 0.30% or less, Ce: 0% or more, 0.30% or less, Sr: 0% or more, 0.30% or less, Li: 0% or more, 0.30% or less, Total amount of Ca, Y, La, Ce, Sr, and Li ΣYa: 0% or more, 0.60% or less, Cr: 0% or more, 1.00% or less, Ni: 0% or more, 1.0% or less, Mo: 0% or more, 0.25% or less, Cu: 0% or more, 1.0% or less, Ag: 0% or more, 0.25% or less, Sb: 0% or more, 0.25% or less, Pb: 0% or more, 0.25% or less, Total amount of Cr, Ni, Mo, Cu, Ag, Sb, and Pb ΣYb: 0% or more, 1.0% or less, B: 0% or more, 0.50% or less, P: 0% or more, 0.50% or less, Total amount of B and P ΣYc: 0% or more, 0.50% or less, Ti: 0% or more, 0.25% or less, Co: 0% or more, 0.25% or less, V: 0% or more, 0.25% or less, Nb: 0% or more, 0.25% or less, Mn: 0% or more, 0.25% or less, Zr: 0% or more, 0.25% or less, W: 0% or more, 0.25% or less, Total amount of Ti, Co, V, Nb, Mn, Zr, and W ΣZ: 0% or more, 0.25% or less, Fe: 0% or more, 5.0% or less, Zn: Exceeding 42.0%, 85.0% or less Includes, The thickness of the above plating layer is 5㎛ or more, and The above plating layer has a first region and a second region, One of the first region or the second region is arranged to have a predetermined shape, and The arithmetic mean roughness (Ra) (μm) on the surface of the first region of the above-mentioned molten-plated steel is denoted as Ra_A, and The arithmetic mean roughness (Ra) (μm) on the surface of the second region of the above-mentioned molten-plated steel is denoted as Ra_B, and The larger value between the above Ra_A or the above Ra_B is called Ra_L, and When the average value of Vickers hardness (HV) between a depth position of (Ra_L+1.0)μm from the surface of the plating layer and a depth position of 1/2 the thickness of the plating layer is denoted as HV_x, and the maximum value of Vickers hardness (HV) is denoted as HV_max, Satisfying the following equations (1) to (5), In the region where the arithmetic mean roughness (Ra) is larger among the first region or the second region, the average value of Vickers hardness (HV) between a depth position of (Ra_L+1.0)μm from the surface of the plating layer and a depth position of 1/2 of the thickness of the plating layer is denoted as HV_big. In the case where the average value of Vickers hardness (HV) between a depth position of (Ra_L+1.0)μm from the surface of the plating layer and a depth position of 1/2 the thickness of the plating layer in the region with the smaller surface roughness (Ra) among the first region or the second region is denoted as HV_sml, Satisfying the following (6) equation, Hot-dip galvanized steel. Ra_A≤10.0 … (1) Ra_B≤10.0 … (2) 1.5≤|Ra_A-Ra_B| … (3) 150≤HV_x≤350 … (4) 200≤HV_max … (5) 0.80≤HV_big/HV_sml≤1.50 … (6)
  2. In paragraph 1, A hot-dip galvanized steel material in which one of the first region or the second region is arranged to have a shape of any one of a straight line, a curved section, a dot section, a figure, a number, a symbol, a shape, or a character, or a shape combining two or more of these.
  3. In paragraph 1, Hot-dip galvanized steel, wherein one side of the first region or the second region is arranged to form a shape of any one of a straight line, a curved section, a dot section, a figure, a number, a symbol, a shape, or a character, or an intentional shape combining two or more of these.
  4. In paragraph 1, The above steel material is a steel plate, The plating layer is provided on both sides of one side of the steel plate and the other side which is the back side of the one side, and A hot-dip galvanized steel material, wherein, in either or both of the plating layer on one side or the plating layer on the other side, one of the first region or the second region is arranged to have a shape of any one of a straight line, a curved section, a dot section, a figure, a number, a symbol, a shape, or a character, or a shape combining two or more of these.
  5. In paragraph 1, The above steel material is a steel plate, The plating layer is provided on both sides of one side of the steel plate and the other side which is the back side of the one side, and A hot-dip galvanized steel material, wherein, in either or both of the plating layer on one side or the plating layer on the other side, one of the first region or the second region is arranged to form a shape of any one type of straight line, curved line, dot, figure, number, symbol, shape, or character, or an intentional shape combining two or more of these types.
  6. A method for manufacturing molten-plated steel as described in any one of claims 1 to 3, and A method for manufacturing a hot-dip galvanized steel, wherein one of the first region or the second region is formed by colliding particles (shots) of iron or non-ferrous metal with the surface of a plating layer formed on the surface of the steel by a hot-dip galvanizing method through centrifugal force or air pressure.
  7. A method for manufacturing hot-dip galvanized steel as described in paragraph 4 or 5, and A method for manufacturing a hot-dip galvanized steel, wherein, among the plating layers formed on one side of a steel plate or on the other side which is the back side of said one side by a hot-dip galvanizing method, one side of said first region or said second region is formed by colliding particles (shots) of an iron or non-ferrous metal with the surface of one or both sides of said one side or said other side by centrifugal force or air pressure.

Description

Hot-dip galvanized steel and method for manufacturing hot-dip galvanized steel The present disclosure relates to hot-dip galvanized steel and a method for manufacturing hot-dip galvanized steel. The present application claims priority based on Japanese Patent Application No. 2023-191984 filed in Japan on November 10, 2023, and incorporates the contents thereof herein. Hot-dip galvanized steel is widely used in the construction, civil engineering, and automotive sectors. This steel is supplied for various processing applications, and steel structures are manufactured using the processed materials. For instance, one frequently encounters metallic-colored hot-dip galvanized steel on the streets, used for guardrails, windbreaks, distribution panels, and cable racks. Unlike conventional galvanized steel, steel structures that constitute part of roads, railways, and streetscapes often require consideration for aesthetics. For instance, there is a growing demand to apply color tones and designs to hot-dip galvanized steel, such as for safety-conscious lighting in road and railway infrastructure, or for black-based color tones and logos displaying advertisements or brand names in modern urban spaces. While painting is the most commonly adopted method, the cost—proportional to the construction area and the need for regular maintenance due to deterioration—remains a significant obstacle. Although stainless steel or aluminum are sometimes used for durability, there are many instances where their adoption is difficult due to material costs and strength requirements. As a means to solve these problems, there is a technology for marking the plated metal itself without painting when shipping hot-dip galvanized steel. For example, Patent Documents 1 to 3 are examples of hot-dip galvanized steel in which a design is imparted by controlling the internal composition of the plating layer, which is a metal film, and combining it with a resin-based film. In these examples, when imparting the design, differences in the metal composition of the plating layer are utilized to impart the design. Consequently, in these examples, there are challenges in realizing clarity such as text, durability associated with corrosion of the plating layer, and large-area processing using patterning. Figure 1 is a photograph showing an example of a design imparted to a plated steel sheet by shot blasting treatment. FIG. 2 is a schematic cross-sectional view of a hot-dip galvanized steel material of the present disclosure. The inventors have carefully examined means to display characters or designs, etc. on the surface (plating layer) of hot-dip galvanized steel, while simultaneously improving the clarity and permanence of the characters or designs, and further enabling the large-area display of the characters or designs. In order to display an ornament, such as characters or a design, on a specific area of a metal surface, it is possible to create a difference in color, gloss, reflectance, etc., between the area displaying the characters or design and the background area. Among these, color difference offers the greatest potential for clearly defining the design. Generally, the surface of metallic materials exhibits a nearly uniform hue, with the exception of, for example, the coloration caused by oxide films on titanium and stainless steel, or aluminum after anodizing; however, among metallic materials, alloys allow for changes in surface hue by altering the compositional ratio of their chemical components. Nevertheless, in hot-dip galvanized steel equipped with a Zn-Al-Mg plating layer, where the chemical composition is uniformly determined, it is difficult to partially alter the chemical composition during the manufacturing of the plating layer; consequently, it is difficult to intentionally change the color difference in specific areas of the plating layer. Furthermore, regarding gloss, there is an issue regarding the permanence of the design during the long-term use of metal materials. That is, as corrosion of the metal surface progresses with prolonged use, the difference in gloss between the design area and the background area decreases, raising concerns that the design may become difficult to stand out. Additionally, since gloss affects properties such as antiperspirability, its control must be performed carefully. Moreover, just like color difference, gloss is influenced by the compositional ratio of the alloy's chemical components; however, for the same reasons mentioned above, it is difficult to intentionally alter the gloss in specific areas of a Zn-Al-Mg plating layer. Meanwhile, since reflectance can be varied by controlling the surface roughness of the metal material, it is believed that it is possible to exhibit an appearance by partially changing the reflectance, even in Zn-Al-Mg-based plating layers where controlling the partial chemical composition is not easy. Therefore, in the present disclosure, an attempt was made to impart an