Why Does Iron Rust But Galvanized Steel Not?

Iron and steel are common materials used in construction and industry. However, why does iron rust easily, while galvanized steel is more resistant to corrosion? The answer lies in the protection of the zinc layer (galvanization) which makes galvanized steel more durable and long-lasting.

1. Iron Oxidation Process That Causes Rust
Rust is formed due to a chemical reaction between iron (Fe), oxygen (O₂), and water (H₂O) in a process called oxidation.

When iron is exposed to humid air or water, its surface begins to react to form iron oxide (Fe₂O₃ nH₂O), known as rust. This rust is brittle and can eat away at iron, so that over time the material will weaken and be damaged.

2. Galvanized Steel is Given Zinc (Zn) Protection
Galvanized steel is steel that is coated with zinc through a galvanization process. This zinc layer functions as a protector from oxidation, so that air and water do not directly come into contact with the iron inside.

The galvanization process is generally done by two methods:

Hot-Dip Galvanizing: Steel is dipped in hot molten zinc, forming a thick, durable layer.

Electro-Galvanizing: Steel is coated with zinc through an electrolysis process, producing a thinner but still effective layer.

3. Zinc's Protective Effects Against Rust
The zinc layer on galvanized steel protects in two ways:

As a barrier layer: Zinc acts as a shield that protects the iron from air and water.

As a protective anode: If there is a scratch or minor damage to the zinc layer, the zinc will oxidize first before the iron is exposed to corrosion.

This is the reason why galvanized steel is more durable, especially in environments that are often exposed to water and high humidity.

4. When Can Galvanized Steel Rust?
Although more resistant to rust, galvanized steel can still corrode if:

The zinc layer has eroded away after years of use.

Exposed to strong chemicals that can damage the zinc layer.

Used in marine environments with high salt content without additional treatment.

Conclusion: Choose Galvanized Steel for Longer Protection
If you need a material that is more resistant to rust, galvanized steel is the best choice compared to regular iron. With protection from a zinc coating, galvanized steel can last longer in various environmental conditions.

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PT Intisumber Bajasakti (ISBS) provides various types of high-quality galvanized steel for construction and industrial needs.

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🌐 Website: www.intisumberbajasakti.com

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