Corrosion Resistance: How to Extend the Life of Your Projects
As one of the most expensive maintenance challenges, corrosion is a fastener’s arch nemesis. Whether you’re in the marine, water treatment, or construction industry, corrosion presents a consistent challenge. One study estimated a $276 billion direct cost of corrosion in the U.S. alone. This direct cost refers to expenses directly related to preventing corrosion or correcting damage caused by corrosion, including:
Material selection
Corrosion allowance
Corrosion protection
Labor
Equipment
Overhead
The largest impact is, not surprisingly, in offshore / marine / maritime sectors, which spends $50 to 80 billion annually on corrosion-related maintenance and replacement. The cost is so high, in part, due to 40% of all produced steel being used to replace corroded steel and corrosion accounts for 60% of offshore maintenance costs.
Replacements and repair, downtime and lost production, collateral damage and safety risks also contribute to the cost of corrosion.
Keeping corrosion costs at bay requires a proactive approach. Here are options and best-fit environments for preventing fastener corrosion and their pros and cons.
Zinc Plating
What it is
A thin zinc layer is applied via electroplating. After this, a chromate/oxide (“passivation”) layer is often added for increased corrosion resistance.
Advantages
Low cost (among the cheapest protective coatings)
Fair corrosion resistance in mild environments
Good for indoor applications, assemblies, non-critical parts
Best for: Indoor steel frames, machinery, parts not exposed to salt or heavy moisture, and light-duty structural applications.
Galvanizing
What it is
A thicker zinc coating applied by immersing steel parts into molten zinc or via mechanical galvanizing.
Advantages
Higher corrosion resistance
Even if the coating is damaged, the zinc continues to protect
Good for outdoor, structural, and exposed environments
Best for: Outdoor structural steel, bridges, light poles, fencing, general construction, infrastructure, and non-marine exterior assemblies.
Stainless Steel (Various Grades)
What it is
An alloy of steel that contains chromium, which forms a film that resists corrosion.
Advantages
Excellent corrosion resistance
The passive oxide film can self-heal when scratched
Good strength, long lifecycle, low maintenance
Broad temperature range
Reduced costs when used appropriately
Best for: Marine hardware, water treatment plants, chemical exposure zones, bridges near ocean spray, desalination plants, or environments where maintenance / replacement is very costly or risky.
Zinc-Flake
What it is
A non-electrolytic coating consisting of zinc and aluminum flakes embedded in an inorganic matrix. The flakes form an overlapping barrier. This has become a standard for high-performance fasteners (especially in automotive and wind power).
Advantages
Very good corrosion resistance
Thin coating, so less impact on tolerances
No hydrogen embrittlement risk (unlike some electroplated processes)
Good friction / torque performance (important for fastener sizing)
Configurable coatings (organic topcoats, color options, etc.)
Best for: High-strength fasteners, structural bolts in moderately corrosive environments, wind towers, critical assemblies where weight, tolerance, and performance matter.
Other Coatings: Phosphate, Black Oxide, Polymer (PTFE / Xylan / Dry Film)
Phosphate (Conversion Coatings): A chemical conversion of the steel surface into an adherent phosphate (iron, zinc, manganese) layer. It provides moderate corrosion resistance, often used as a base for paint/coating or for lubrication.
Black Oxide / Black Zinc: Primarily for aesthetics or light corrosion resistance.
Polymer coatings (PTFE, Xylan, Teflon): Used where friction reduction, chemical resistance, or non-stick behavior is required.
Cadmium plating: Historically used because of excellent corrosion resistance and sacrificial behavior, but environmental regulations limit its use in many regions.
These are generally lower in corrosion protection than galvanized or stainless for harsh environments.
Not sure which fastener coating would best protect your project? Contact the experts at Melfast for guidance.
Request a quote today and get expert guidance on corrosion-resistant fasteners.
