Surface-treated hot-dipped steel material

Abstract

A surface-treated hot-dipped steel material comprises a steel material and a coating material formed on the surface of the steel material, wherein the coating material comprises a plating layer and a coating film formed on the surface of the plating layer and comprising an organic resin in this order when observed from the steel material side, the plating layer contains Al, Zn, Si and Mg as constituent elements, the Al content and the Mg content in the plating layer are 25 to 75 mass% and 0.1 to 10 mass%, respectively, the plating layer contains 0.2 to 15 vol% of an Si-Mg phase, the ratio of the content of Mg in the Si-Mg phase to the total content of Mg in the plating layer is 3 to 100% inclusive by mass, and the organic resin is crosslinked with at least one component selected from a silane coupling agent, a crosslinkable zirconium compound, a crosslinkable titanium compound, an epoxy compound and an amino resin.

Description

technical field [0001] The invention relates to a surface-treated hot-dipped steel material. [0002] This application claims priority based on Japanese Patent Application Japanese Patent Application No. 2011-182916 for which it applied on August 24, 2011, and uses the content here. Background technique [0003] In the past, Zn-Al-based hot-dipped steel materials have been widely used in applications such as building materials, automobile materials, and home appliance materials. Among them, high-aluminum (25 to 75% by mass)-zinc alloy-coated steel sheets represented by 55% aluminum-zinc alloy-coated steel sheets (Galvalume: hot-dip galvalume (registered trademark)) are different from ordinary hot-dip galvanized steel sheets. Compared with zinc steel sheet, the demand continues to expand due to its excellent corrosion resistance. In addition, in recent years, especially building materials have been required to further improve corrosion resistance and workability, and the im...

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Problems solved by technology

[0004] However, the high aluminum-zinc alloy plated steel sheet containing Mg tends to cause wrinkles on the surface of the plated layer, so the problem is the deterioration of the surface appearance.

Furthermore, sharp bulges are produced on the surface of the coating due to the wrinkles, so when the coating is subjected to surface conversion treatment to form a surface conversion treatment layer, or when coating is applied to form a coating layer, the thickness of the above-mentioned surface conversion treatment layer or coating layer is easy. become uneven

Therefore, there is a problem that the effect of improving the corrosion resistance of the plated steel sheet cannot be fully exerted by coating or the like.

However, wrinkle suppression is not sufficient

[0007] Wrinkles formed by such a plating layer are difficult to sufficiently remove by temper rolling, etc., and may lead to deterioration of the appearance of hot-dipped steel materials

[0008] In addition, the durability of the conventional high-alumina (25 to 75% by mass)-zinc alloy plated steel sheet for the coating (corrosion rate of the coating), red rust resistance (resistance to red rust generated by the steel sheet), or Although the red rust resistance and coating swelling resistance of the cut end surface of the coated steel plate after coating have been improved, there is no improvement in the white rust resistance of the coating (the ability to suppress the appearance caused by white rust caused by coating corrosion) Reduced performance), especially from the point of view of improving the white rust resistance of the processed part, scratch resistance, and stain resistance

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