Galvanized steel is well known for its exceptional strength against corrosion, which positions it pretty high amongst leading industries, such as construction, automotive, and manufacturing. However, whereas this material is indeed resistant to rusting, it is not completely immune to rusting. Given some time and certain conditions, even galvanized steel can rust or corrode. Knowing why this occurs and what conditions affect the durability of it may assist you in making wise decisions about when to use it.
This article discusses whether galvanized steel rusts, the factors that influence its durability, and how its lifespan can be extended.
What Is Galvanized Steel?
Galvanized steel is steel coated with a layer of zinc to protect it from corrosion and rust. The zinc coating acts as a barrier, preventing moisture and oxygen from coming into direct contact with the steel surface. Additionally, zinc offers sacrificial protection—when the coating is scratched or damaged, the zinc corrodes first, sparing the steel beneath it.
There are several types of galvanized steel:
- Hot-Dip Galvanized Steel: Steel is submerged in molten zinc, creating a thick, durable coating.
- Electro-Galvanized Steel: A thinner layer of zinc is applied using electroplating, resulting in a smoother finish but less durability compared to hot-dip galvanizing.
- Pre-Galvanized Steel: Zinc coating is applied before fabrication, often used for items like pipes and sheets.
Does Galvanized Steel Rust?
The short answer is yes but under specific conditions. While the zinc coating significantly delays rust formation, it is not permanent. Over time, environmental exposure and physical damage to the coating can reduce its effectiveness, eventually leading to rust on the underlying steel.
How Galvanized Steel Resists Rust
Galvanized steel offers two layers of protection:
- Physical Barrier Protection: The zinc coating acts as a shield, keeping moisture and air away from the steel surface.
- Cathodic Protection: If the zinc layer is scratched or chipped, the surrounding zinc will sacrifice itself by corroding first, protecting the exposed steel.
However, once the zinc layer is completely depleted or compromised, the steel underneath becomes vulnerable to rust.
Factors Affecting the Longevity of Galvanized Steel
Several factors can influence how well-galvanized steel resists rust and how long it maintains its integrity:
1. Environmental Conditions
The environment in which galvanized steel is used plays a significant role in its durability.
- Marine Environments: Coastal or marine environments expose galvanized steel to high levels of salt, which accelerates the corrosion process.
- Industrial Environments: Pollutants and chemicals in industrial settings can increase the rate of corrosion.
- High Humidity: Areas with high humidity provide more moisture, which can wear down the zinc coating over time.
- Temperature Extremes: Repeated cycles of freezing and thawing can weaken the protective coating.
2. Thickness of the Zinc Coating
The thicker the zinc coating, the longer the galvanized steel will resist rust. For example, hot-dip galvanizing provides a much thicker coating compared to electro-galvanizing, making it more durable in harsh environments.
3. Exposure to Abrasions and Damage
Physical damage to the zinc layer—whether from scratches, dents, or cuts—can expose the steel underneath to moisture and oxygen, initiating the rusting process.
4. Contact with Certain Metals
Galvanized steel can corrode faster when it comes into contact with other metals, especially copper and brass, due to galvanic corrosion. This happens when two dissimilar metals come into contact in the presence of an electrolyte, such as water.
5. Poor Maintenance
Neglecting to clean and inspect galvanized steel can allow contaminants, dirt, and moisture to build up, leading to localized corrosion over time.
How to Extend the Lifespan of Galvanized Steel
1. Regular Maintenance
Inspect galvanized steel regularly for signs of wear or damage to the zinc coating. Cleaning the surface to remove dirt, debris, and salt deposits will help slow the corrosion process. Use mild detergents and soft brushes to clean the surface.
2. Avoid Harsh Environments
If possible, avoid using galvanized steel in environments with extreme salt exposure or high levels of industrial pollutants. For marine or industrial applications, consider additional protective measures, such as applying sealants or paint.
3. Apply Protective Coatings
Adding a layer of paint or a specialized sealant over the galvanized surface can provide extra protection. Be sure to use coatings that are compatible with galvanized steel.
4. Prevent Galvanic Corrosion
Avoid direct contact between galvanized steel and other metals like copper or brass. Use insulating materials, such as rubber gaskets or plastic spacers, to separate the metals.
5. Opt for Thicker Coatings
When purchasing galvanized steel, opt for products with a thicker zinc layer, especially for outdoor or heavy-duty applications.
6. Repair Damaged Areas
If the zinc coating is scratched or damaged, repair it promptly using zinc-rich paints or sprays. These products restore the protective layer and prevent rust from forming.
Common Applications of Galvanized Steel
Galvanized steel is used in a wide range of applications due to its durability and resistance to corrosion:
- Construction: Roofing, wall panels, and structural supports.
- Automotive Industry: Car frames, undercarriage parts, and exhaust systems.
- Agriculture: Fences, silos, and irrigation systems.
- HVAC Systems: Ventilation ducts and outdoor units.
- Infrastructure: Bridges, guardrails, and power transmission towers.
In these applications, galvanized steel’s ability to resist rust ensures longer service life and reduced maintenance costs.
Midwest Steel: Your Trusted Supplier for Galvanized Steel
Midwest Steel takes pride in ensuring your projects are backed with quality material. Our galvanized steel is produced to be as durable as possible and still function well under demanding conditions. For construction, automotive, and industrial use, galvanized steel will find a perfect match at Midwest Steel.
With over a decade of experience, Midwest Steel has dedicated itself to offering the highest quality customer service and premium-grade products at competitive prices. Contact us today to learn more about our range of galvanized steel and other steel solutions.
Conclusion
Galvanized steel is much more resistant to rust than its untreated counterpart; it is not, however, completely rust-proof. Conditions such as environmental factors and physical damage may degrade it. By knowing which factors contribute to degrading such material, the likely lifespan of galvanized steel can be considerable with proper measures taken.
For all your steel needs, look no further than Midwest Steel: delivering quality and value for you.