Fastener Materials Guide
Choosing the right material—carbon steel, stainless, aluminum, or coated—affects strength, corrosion resistance, and weight. Compare options below.
Common fastener materials
| Material | Pros | Cons |
|---|---|---|
| Carbon steel | Strong, cheap, many grades | Rusts unless coated |
| Stainless steel | Corrosion resistant | Can gall, more cost |
| Aluminum | Light, no rust | Weaker, soft threads |
| Zinc plated | Good corrosion, low cost | Coating can wear |
Strength and weight
Steel has the highest strength; stainless is similar but can work-harden. Aluminum is about one-third the density of steel—useful where weight matters. Use our Fastener Weight Calculator to compare weights by material for a given size and quantity.
Corrosion and galvanic pairing
Mixing dissimilar metals (e.g. stainless with aluminum) can cause galvanic corrosion. In corrosive environments, match materials or use isolation. For stainless-on-stainless, use anti-seize to reduce galling (see Why Stainless Bolts Gall).
FAQ
When should I use stainless steel bolts?
Use stainless for corrosion resistance in wet, chemical, or outdoor environments. Avoid mixing with carbon steel to prevent galvanic corrosion; watch for galling (use anti-seize).
Are aluminum fasteners strong enough?
Aluminum bolts are lighter but weaker than steel. Use where weight matters (e.g. aerospace, cycling) and load is moderate. Check torque specs—they differ from steel.
What is the difference between zinc and galvanized?
Zinc plating is a thin coating for corrosion resistance. Galvanized usually means hot-dip zinc, thicker and more durable. Both protect carbon steel.
Related
Tools: Fastener Weight Calculator, Bolt Torque Calculator
Charts: Universal Screw & Bolt Size Chart, Screw Size Chart
Guide: Why Stainless Bolts Gall