Galvanized Steel Texture Variations Different Types

Galvanized steel has a zinc coating applied to shield it from rust. Its surface texture can vary depending on the galvanizing process, coating thickness, and exposure to environmental factors.

This article provides texture images of different types of galvanized steel, including hot-dip galvanized, electro-galvanized, corroded, and zinc-coated steel with white rust. These images will help you identify and compare the various surface textures found in galvanized steel.

Galvanized Steel ( Hot-dip Galvanized Steel)

Hot-dip galvanized steel is steel coated by dipping it into molten zinc to create a protective layer. Its surface texture is typically rough and spangled, with variations depending on the zinc coating thickness.

Freshly produced hot-dip galvanized steel typically has a shiny, metallic surface with visible spangles. The surface may also appear slightly rough, depending on the thickness of the zinc coating, and the overall finish is smooth with a reflective sheen.

Over time, the surface of hot-dip galvanized steel can alter in appearance. It may lose its initial shine and become duller due to exposure to environmental elements like moisture and air. The spangles may still be visible, but the surface might develop a more matte or slightly weathered appearance.

Why Does Hot-Dip Galvanized Steel Develop Spangles?

Hot-dip galvanized steel develops spangles due to the cooling and solidification of the zinc coating. When steel is dipped into molten zinc, a reaction occurs between the iron and zinc, forming an alloyed layer. As the steel cools, pure zinc solidifies on the surface, forming small crystals that create the pattern known as spangle.

Spangles appear as shiny, star-like patterns of zinc grains. Their size and visibility depend on the temperature of the molten zinc, cooling speed, and any trace metals like lead or antimony in the bath. In modern production, spangle size can be controlled for specific applications.

The reason spangles appear in this particular shape is tied to the crystal structure of zinc. As zinc cools and crystallizes, the atoms are arranged in hexagonal shapes due to zinc’s natural atomic structure. This atomic arrangement creates the signature star-like or hexagonal formations.

Aço eletrogalvanizado

Electro-galvanized steel receives a thin zinc layer through an electroplating technique. Its surface texture is usually smooth and uniform, with less pronounced spangling compared to hot-dip galvanized steel.

White Rusted Galvanized Steel

White rust on galvanized steel forms due to a chemical reaction between zinc and moisture in low-oxygen conditions. When exposed to water or high humidity, the zinc coating reacts to produce zinc oxide. In confined spaces with limited airflow, it further transforms into zinc hydroxide, appearing as a powdery white layer known as white rust.

White rust is soft, chalky, and easily visible as a white or light gray layer on the steel’s surface. Unlike red rust on iron, it doesn’t bond strongly with the zinc, so it can often be wiped off in early stages, though extensive white rust can weaken the zinc coating’s corrosion resistance.

The unique appearance of white rust results from the porous structure of zinc hydroxide, which forms soft, irregular clusters that create a powdery look. Prevention involves keeping galvanized steel in dry, ventilated areas and avoiding prolonged moisture exposure during storage or shipping.

Heavily Rusted Galvanized Steel

Severely corroded galvanized steel typically has a rough, pitted surface with visible signs of zinc loss. The protective zinc layer has been largely degraded, exposing the underlying steel.

The surface may appear uneven, with deep rust spots or areas where the metal has oxidized. Corrosion often results in a flaky, reddish-brown rust appearance, and in extreme cases, the steel may show signs of structural damage, such as thinning or holes.

Perguntas frequentes

Is Galvanized Steel Rough?

Hot-dip galvanized steel can be rough, especially if the zinc coating is thick. The surface may have a spangled pattern or slight unevenness, giving it a textured feel. Electro-galvanized steel, is usually smoother.

Why Does Galvanized Steel Look Patchy?

Galvanized steel may look patchy due to variations in the zinc coating. This can happen with hot-dip galvanized steel if the coating is uneven or if it cools inconsistently, causing areas to appear more shiny or matte.

Is Galvanized Steel Shiny or Dull?

Freshly galvanized steel (hot-dip) is shiny and metallic-looking with a reflective surface. Over time, it becomes duller as the zinc oxidizes, but it still has a matte appearance compared to its original shine. Electro-galvanized steel tends to be shinier and more uniform in appearance.

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