The Strength and Durability of Galvanized Steel

Steel is one of the most widely used metals in the world due to its strength, durability, and versatility. However, regular carbon steel has one major downside – it readily corrodes and rusts when exposed to moisture and oxygen. This can lead to aesthetic damage, weakened structural integrity, and high maintenance costs. Fortunately, there is a simple solution that allows steel to retain its benefits while eliminating the corrosion problem. Galvanized steel refers to carbon steel that has been coated with a protective layer of zinc. This galvanization process boosts the steel’s resistance to degradation and significantly extends its lifespan.

Galvanized steel offers many advantages in a wide range of applications and industries. This article will explore what exactly galvanized steel is, its key properties and benefits, and some of its most common and creative uses.

What is Galvanized Steel?

Galvanized steel starts out as regular carbon steel in the form of sheets, tubes, beams, bars, and more. It undergoes a galvanization process which involves coating the steel with a thin layer of zinc. This can be done in two ways:

Hot-Dip Galvanizing

The steel parts are submerged in a bath of molten zinc. The zinc reacts with the steel surface to form durable zinc alloy layers bonded tightly to the steel. Hot-dip galvanized steel is suitable for applications where severe corrosion resistance is needed.

Electrogalvanizing

The coating is applied using an automated electroplating process. A thinner and less durable zinc layer is deposited on the steel. Electrogalvanizing is cheaper and better suited for indoor applications.

In both methods, the zinc serves as a sacrificial anode for the underlying steel. If the zinc coating gets scratched, the exposed areas will still be protected by the surrounding zinc. The coating thickness generally ranges from 1 to 4 mils (25 to 100 microns).

Key Properties and Benefits

Galvanizing the steel is an extremely effective anti-corrosion treatment. It provides the following advantages:

• Prevents Rusting: The zinc barrier blocks moisture, oxygen, and other corrosion-causing elements from reaching the steel. This prevents the iron from oxidizing and rust formation.
• Long Lasting: Hot-dip galvanized steel can last over 70 years without maintenance in harsh outdoor environments, far longer than uncoated steel.
• Lower Maintenance: No need for time-consuming and costly paint jobs every few years.
• Impact Resistant: Galvanized coatings are very adherent and abrasion resistant. They are less likely to crack or flake off when handled or impacted.
• Cost Effective: The higher initial material cost is offset by lower lifetime maintenance costs.
• Versatile: Galvanizing lets steel be used in highly corrosive marine and industrial environments where regular steel would fail prematurely.
• Environmental Friendliness: No use of toxic paints and coatings that can release hazardous VOCs.

Common Uses of Galvanized Steel

Thanks to its ruggedness and cost-effectiveness, galvanized steel is used in an incredibly diverse array of applications including:

1. Building and Construction

Galvanized steel studs, roofing, ducts, pipes, and more are extensively used in construction. High-rise buildings depend on hot-dip galvanized rebar in concrete foundations and pillars for longevity. Exterior railings, balconies, canopies, and facade cladding also utilize galvanized materials.

2. Infrastructure and Transportation

Bridges, transmission towers, roadside signage, utility poles, rail tracks, and even entire train carriages and ship hulls are frequently made from galvanized steel. Airport jetways also rely on galvanized structural steel frames.

3. Agriculture and Livestock Management

Galvanized steel is ideal for rugged farm equipment like trailers, fences, barns, and storage silos which are exposed to the elements year-round. Livestock watering troughs, feeders, and galvanized mesh cages are ubiquitous sights in pastoral farming.

4. Telecommunication and Power

Vast networks of galvanized steel radio, TV, and cellphone towers keep our communication channels open. Similarly, electricity is delivered via durable galvanized steel power line pylons and poles.

5. Automotive Manufacturing

Car bodies and panels increasingly use galvanized steel due to its anti-corrosion properties, dent resistance, and lighter weight compared to pure zinc coatings. Galvanized steel also protects the fuel tanks, exhaust systems, and other key automotive components.

Unique Uses and Creative Applications

While galvanized steel is most commonly seen in industrial settings, it also enables unique applications thanks to its longevity, strength, and weather resistance:

• Permanent sculptures and artistic structures outdoors.
• Zero-maintenance roadside and park furniture like benches, dustbins, and sign boards.
• Rugged playground equipment and park installations.
• Life-sized animal models in zoos and natural spaces.
• High-detail miniature railroad models left permanently outdoors.
• Durable marine components like masts, booms, rails, and safety cages on ships, oil rigs, and docks.
• Weatherproof electric guitar bodies and drums with exotic metallic finishes.
• Unpainted galvanized steel exterior cladding with a dull matte sheen.
• Public garbage cans, mailboxes and bicycle stands able to withstand sun, rain and abuse.
• Off-the-grid tiny homes and cabins built from galvanized roofing and framing.
• Outdoor kitchens, barbecues and pizza ovens without rust or painting.

With some creativity, galvanized steel components can add durability, style and functionality to projects that traditional steel cannot match.

Galvanized Steel vs Stainless Steel

Stainless steel is another hugely popular corrosion resistant variant of steel. How does its performance compare with galvanized steel?

Corrosion Resistance – Stainless steel ultimately wins this test. Its chromium oxide passivation layer prevents virtually all rusting and pitting. Galvanized steel still needs barrier protection from zinc.

Strength – Stainless steel has a much higher baseline tensile strength than plain carbon steel. But properly galvanized steel still matches or exceeds stainless steel grades in strength.

Initial Cost – Hot-dip galvanized steel is around 25-50% cheaper compared to an equivalent stainless steel product. Electrogalvanizing can be even more cost effective.

Maintenance – Neither needs much maintenance. Stainless steel may occasionally need passivation treatment to repair the oxidized surface layer.

Appearance – Stainless steel retains its pristine appearance over decades. Galvanized steel dulls and weathers over time.

Fabrication – Stainless steel is tougher to modify after production without damaging its protective layer. Galvanized steel can be welded, cut and drilled easily.

Availability – Galvanized steel is easier to source and has far more manufacturing capacity globally. Some stainless steel grades may have long lead times.

Environment – Both are fully recyclable. But stainless steel cannot be galvanized for enhanced corrosion protection due to the nickel content.

Applications – Galvanized dominates cost-driven sectors like construction, infrastructure and agriculture. Stainless prevails where appearance and complete corrosion resistance are paramount.

So while stainless steel wins on corrosion protection and aesthetics, galvanized steel offers the most cost-effective combination of strength, lifespan, and workability.

Is Galvanized Steel Susceptible to Rust After All?

The zinc coating gives galvanized steel vastly improved protection from rusting. However, it does have its limitations:

• Extreme Exposures – In exceptionally corrosive coastal or industrial environments, the zinc will sacrificially corrode over decades until the coating fails.
• Coating Breaches – Gaps or scratches in the zinc exposing the underlying steel will eventually rust if not patched up.
• Low-Quality Galvanizing – Insufficient galvanizing thickness or coverage due to poor workmanship leads to early coating failure and rusting.
• Wet Storage Staining – Water collecting on newly galvanized items causes unsightly but superficial white staining on the surface. It is prevented by proper storage and handling.
• Bimetallic Corrosion – Direct contact between galvanized steel and certain dissimilar metals can accelerate galvanic corrosion. Insulators must separate them.
• Welding Damage – Welding galvanized steel can vaporize the protective zinc around the weld joint, unless done correctly with specialized methods.

So while galvanized steel remains susceptible to rusting eventually, instances can mostly be traced back to extreme conditions or improper usage practices. The anti-corrosion protection still far outlasts other methods.

Best Practices for Maximizing the Lifespan

To get the most out of galvanized steel and delay rust formation indefinitely, the following guidelines must be kept in mind:

• Specify hot-dip galvanizing with minimum coating thickness of 2.0 mils (50 microns) or higher based on environmental corrosivity.
• Ensure complete and uniform galvanization quality by using reputable galvanizers who follow all standards.
• Store galvanized materials off the ground in clean, dry indoor environments prior to installation.
• Use galvanized steel fasteners to avoid bimetallic corrosion. Stainless steel fasteners are also suitable.
• Touch up any accidental coating damage immediately with appropriate zinc-rich primers.
• Avoid direct contact between galvanized steel and copper, brass and plain carbon steel.
• Consult an expert before attempting to weld galvanized steel due to the harmful zinc fumes. It may be better to weld first before galvanizing.
• Water test completed structures to ensure no pooling or dripping onto galvanized components.
• Periodically wash off accumulated surface dirt using gentle detergents and brushes. Never use abrasives.
• Inspect annually for any visible coating deterioration and address promptly. Early failure points can then be recoated before rust gains hold.

With proper preventative maintenance and care, galvanized steel offers unmatched longevity and value.

Cutting, Shaping and Joining Galvanized Steel

One of the key advantages of galvanized steel is how easy it remains to handle and work like regular steel, despite its coating. This allows limitless possibilities for fabrication and construction.

Cutting – Galvanized steel is readily cut to size using anything from hand shears up to computerized plasma and laser cutters. Sheets facing upwards are securely clamped down before cutting to avoid coating damage.

Drilling – Standard power drills with high-speed steel bits smoothly create holes in galvanized steel. Coolants help reduce friction and overheating. Deburring is done carefully to avoid ripping off any zinc around the holes.

Stamping – Hydraulic presses and dies stamp sheet galvanized steel into customized shapes for manufacturing. The zinc holds up well to the drawing process compared to coatings which can flake or crack.

Bending – Galvanized steel retains good ductility and formability. It can be bent into any shape using brake presses, tube benders, or even 3-roll plate rollers for cylinders.

Welding – While welding galvanized steel produces toxic zinc fumes, it can be done safely. The area around the weld is pretreated with a degalvanizing agent and special low-fume electrodes. Welding before galvanizing is simpler.

Fastening – Galvanized screws, bolts, nuts and other fasteners avoid bimetallic corrosion. Adhesives, rivets and resistance spot welding also work very well.

Grinding – Excess zinc around welds and cuts can be ground off with angle grinders. Dust masks are worn to avoid inhaling zinc particles.

With the right tools and precautions, galvanized steel can be fabricated and installed just like uncoated steel while retaining its anti-corrosion abilities.

Affordable Options for Restoring Rusted Galvanized Steel

Even quality galvanized steel may eventually exhibit rusting, often around joints or edges. Thankfully, restoring the corrosion protection is straightforward without needing to replace the entire component. Some proven methods include:

Wire Brushing – This manually removes loose surface rust using steel wire brushes. Power wire brush tools speed up the process for larger areas. Brushing reveals pitted but intact zinc below most light rust.

Sanding – Sandpapers, emery cloths and flap wheels are used to sand down rust until only clean galvanizing remains. It also smoothens out any remaining roughness.

Pickling Solutions – Special acidic solutions are brushed or sprayed on heavily rusted areas to dissolve the rust and etch the surface clean. Pickling reveals the underlying galvanizing layer.

Zinc-Rich Primers – After preparing the surface, liquid zinc primers containing 93% or more pure zinc dust are spray or brush applied. This replenishes the corroded zinc layer and prevents recurring rust.

Zinc Spray Metallizing – For severely corroded sections, melted zinc is sprayed on. This deploys a layered zinc coating matching hot-dip galvanizing standards for corrosion protection and longevity.

Mechanical Zinc Plating – Electro-plated zinc coatings can rapidly restore corroded galvanized steel without using any hazardous chemicals. The new coating alloys with the existing galvanized layer.

With the right restoration processes, damaged galvanized steel can regain its protective barrier and remain in service for many more years. The options balance affordability and high performance.

The Environmental Sustainability of Galvanized Steel

Beyond enhancing any steel product’s durability and lifespan, galvanized steel offers sustainability benefits:

• Conserves Resources – Lower lifecycle maintenance requirements compared to painted steel reduces the energy, raw materials, chemicals, and labor needed over decades of service.
• Recyclable – Both the steel and zinc are 100% recoverable for recycling at end-of-life with no loss of material quality.
• Energy Efficient – The reflective surface of newly galvanized steel reduces cooling costs when used in building cladding or rooftops.
• Reduces Pollutants – The avoidance of repetitive paint jobs minimizes emissions from fossil fuel-derived paints over the structure’s service life.
• Fire Resistance – Galvanized steel has higher heat thresholds before losing strength or collapsing. This enhances fire safety margins.
• Carbon Cost Savings – Using galvanized steel in durable low-maintenance infrastructure like transmission towers shrinks the whole lifecycle carbon footprint.

Galvanized steel is the ideal sustainable material choice when engineering structures and components meant to serve for generations, not just years.

Conclusion

Galvanized steel clearly demonstrates that affordable corrosion resistance, high strength, and extraordinary longevity need not be mutually exclusive properties. The simple zinc coating transforms regular steel into a uniquely rugged and adaptable modern building material. Although it has been used for over 150 years, galvanized steel resolves the corrosion challenges of steel like no other technology can. It provides an optimal balance of capabilities and costs. Galvanization has allowed steel to realize its full potential in shaping our built environment. Whether the application is a small backyard fixture or a massive bridge, galvanized steel is up to the task. This venerable material will continue serving our infrastructure needs indefinitely even as new alloys and processes are developed. In the ongoing battle against rust, galvanized steel remains well ahead.