Galvanized vs stainless vs aluminum grating
Material decides roughly 40% of a grating RFQ's total cost. This page compares hot-dip galvanized carbon steel, stainless 304 / 316L, and aluminum 6061-T6 across mechanical properties, corrosion performance, and cost.
Key takeaways
- Carbon steel + hot-dip galvanizing (85–100 µm zinc) is the global default: 85% of industrial grating by volume.
- Stainless 304 is specified for mild chlorides; 316L for coastal, pharma, and food plants.
- Aluminum 6061-T6 is 3× lighter and non-corroding but 30–50% deeper bar is needed for the same load.
- Cost per m²: galvanized 1.00× · aluminum 1.8–2.2× · stainless 304 2.5–3× · stainless 316L 3–4×.
Mechanical properties
| Property | HDG carbon steel (A36 / Q235) | Stainless 304 | Stainless 316L | Aluminum 6061-T6 |
|---|---|---|---|---|
| Density (g/cm³) | 7.85 | 8.00 | 8.00 | 2.70 |
| Yield strength (MPa) | 235–250 | 205 | 170 | 275 |
| Tensile strength (MPa) | 370–510 | 515 | 485 | 310 |
| Modulus E (GPa) | 200 | 193 | 193 | 69 |
| Allowable bending (Fb, MPa) | 155 (ASD 0.66Fy) | 135 | 112 | 182 |
| Max service temp (°C) | −20 / +200 | −196 / +870 | −196 / +870 | −50 / +150 |
Corrosion performance
| Environment | HDG steel (85 µm Zn) | Stainless 304 | Stainless 316L | Aluminum 6061-T6 |
|---|---|---|---|---|
| C2 rural / indoor | 30–40 years | 50+ years | 50+ years | 40+ years |
| C3 urban / industrial | 15–25 years | 30+ years | 50+ years | 25–40 years |
| C4 coastal | 10–15 years | 15–25 years (pitting possible) | 40+ years | 20–30 years |
| C5 chloride splash | 5–10 years | Not recommended | 20–30 years | 10–20 years |
| Food / pharma wash-down | Not recommended | Acceptable | Preferred | Acceptable |
| Acidic fume (pH < 4) | Not recommended | Limited | Limited – consider FRP | Not recommended |
For chloride >30,000 ppm or acidic pH < 3 service, see our steel vs FRP grating comparison.
Weight and load implications
Because aluminum's modulus is one-third of steel's, an aluminum panel with the same bearing-bar geometry deflects about 3× under the same load. To match a welded 30×3 mm steel panel's deflection, the aluminum bar usually has to be 40×5 mm — lighter overall, but deeper profile.
- Panel self-weight (1 m² of 30×3 mesh): HDG steel ~27 kg · stainless ~28 kg · aluminum ~10 kg.
- Typical span at 5 kPa uniform load: steel 1.30 m · aluminum 0.85 m with same bars (1.25 m with 40×5 bars).
- Shipping cost per m² (CIF example port): aluminum is 40–50% cheaper to ship than steel, partially offsetting material premium.
Indicative cost per m² (30-100 / 30×3 mesh, 1.0 m span)
| Material | Relative cost (HDG = 1.0×) | Typical region |
|---|---|---|
| HDG carbon steel | 1.0× | Default industrial, structural, outdoor |
| Untreated (painted) carbon steel | 0.85× | Indoor dry only |
| Aluminum 6061-T6 | 1.8–2.2× | Rooftops, marine, hand-carry |
| Stainless 304 | 2.5–3.0× | Food plants, mild chloride |
| Stainless 316L | 3.0–4.0× | Coastal, pharma, chloride splash |
Prices move with the LME zinc and nickel indices. We quote firm numbers within 12 hours of receiving a spec.
Selection cheat-sheet
- Default (80% of RFQs): hot-dip galvanized carbon steel welded 30×3 at 30-100 mesh.
- Coastal / marine, 15+ year design life: stainless 316L or aluminum 6061-T6 depending on load.
- Pharma / food / clean-room: stainless 316L — hygiene and cleanability override cost.
- Rooftops, removable access covers: aluminum 6061-T6 for weight.
- Chemical plant, acidic or caustic fumes: FRP grating — see the Steel vs FRP comparison.
Frequently asked questions
- When should I choose stainless steel grating over galvanized?
- When the zinc sacrificial layer won't reach design life (coastal C5, acidic fumes), when chloride pitting is a risk, or when hygiene/cleanability is a regulatory requirement (food, pharma).
- How much lighter is aluminum grating than steel?
- Aluminum 6061-T6 has a density of 2.70 g/cm³ vs 7.85 for carbon steel, so an aluminum panel of the same geometry weighs ~34% of the steel panel. Because aluminum modulus is one-third of steel, deflection usually governs and the bar must be 30–50% deeper.
- What is the service life of hot-dip galvanized grating?
- With 85 µm zinc per ASTM A123 / ISO 1461: ~20–40 years in rural atmosphere, 15–25 years in industrial, 10–15 years in coastal, 5–10 years in chloride splash. Thicker zinc (100 µm) or duplex paint+zinc systems double service life.
- Is stainless grating much more expensive?
- Yes. Stainless 304 is typically 2.5–3.0× the cost per m² of HDG carbon steel at equivalent mesh; 316L is 3–4×. Aluminum 6061-T6 is 1.8–2.2×. Over a 20-year life the premium is often offset by avoided replacement cycles.
- Can I mix materials on one project?
- Yes. Common on chemical plants: galvanized for dry elevated walkways, stainless 316L for wet process floors, FRP around chemical tanks. Wiberg supplies all three from one factory with a single project code.
Not sure which material?
Send us the environment (atmosphere, chemicals, temperature) and load. We'll return a material recommendation and a 3-option quote.