Why Galvanized Bolts Rust?

As mentioned earlier, galvanized bolts are not entirely rust-proof; they only delay the onset of rust. So, why do galvanized bolts rust, and how can we prevent it? Let's delve deeper into this issue.

**I. The Galvanized Layer is Not an "Impenetrable Shield"**

1. **Insufficient Thickness of the Galvanized Layer:** The thickness of the galvanized layer directly affects its rust resistance. If the galvanized layer is too thin, it cannot effectively isolate the base metal from the external environment, making it prone to corrosion.

2. **Uneven Galvanized Layer:** If the galvanizing process is not properly controlled, it can result in an uneven distribution of the galvanized layer, leading to defects such as missed spots and bubbles. These weak points can become entry points for corrosion.

3. **Damage to the Galvanized Layer:** During transportation, installation, and use, the galvanized layer may suffer mechanical damage, such as scratches and impacts. These damaged areas expose the base metal, leading to rust.

**II. Environmental Factors Accelerating Corrosion**

1. **Humid Environments:** Humid environments accelerate metal corrosion, especially in coastal areas or industrial zones where the air contains high levels of salt and corrosive gases, which exacerbate the corrosion of the galvanized layer.

2. **Acidic or Alkaline Environments:** Acidic or alkaline environments can destroy the protective effect of the galvanized layer, causing rapid corrosion of the base metal.

3. **High-Temperature Environments:** High temperatures accelerate the oxidation reaction of metals, causing the galvanized layer to fail and the base metal to rust.

**III. Measures to Prevent Rusting of Galvanized Bolts**

1. **Select the Appropriate Thickness of the Galvanized Layer:** Choose the appropriate thickness of the galvanized layer based on the usage environment. For example, use a thicker galvanized layer or double-layer galvanizing in harsh environments.

2. **Strictly Control the Galvanizing Process:** Ensure that the galvanized layer is uniform and dense, avoiding defects such as missed spots and bubbles.

3. **Avoid Mechanical Damage:** During transportation, installation, and use, take care to protect the galvanized layer from scratches, impacts, and other mechanical damage.

4. **Improve the Usage Environment:** Try to avoid using galvanized bolts in humid, acidic, alkaline, or high-temperature environments. If necessary, take protective measures such as applying anti-rust paint or using anti-rust oil.

5. **Regular Inspection and Maintenance:** Regularly inspect the surface condition of galvanized bolts, promptly identify and address rust issues, and extend their service life.

**IV. Comparison with Other Surface Treatment Methods**

In addition to galvanizing, there are other surface treatment methods that can improve the rust resistance of bolts, such as:

1. **Dacromet Treatment:** Dacromet treatment is a new metal surface treatment technology with excellent rust resistance, corrosion resistance, and high-temperature resistance, but it comes at a higher cost.

2. **Hot-Dip Galvanizing:** Hot-dip galvanizing provides a thicker galvanized layer with better rust resistance than electro-galvanizing, but the process is more complex and costly.

3. **Stainless Steel Material:** Stainless steel itself has excellent rust resistance, but it is more expensive and may not be as strong as carbon steel bolts.

**V. Conclusion**

Galvanized bolts are not entirely rust-proof, and their rust resistance is influenced by various factors. To extend the service life of galvanized bolts, we need to select the appropriate thickness of the galvanized layer, strictly control the galvanizing process, avoid mechanical damage, improve the usage environment, and conduct regular inspections and maintenance. Additionally, we can choose other surface treatment methods based on actual needs to achieve better rust resistance.