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 strong chloride, acidic, alkaline or mixed chemical exposure, compare metal and FRP options using the actual concentration, temperature, wetting mode, cleaning regime and design life. 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?
- No fixed life applies to every site. Estimate it from the specified galvanizing standard and measured coating, corrosivity, chloride deposition, wetness, detailing and maintenance. A duplex system may extend time to maintenance, but verify the selected coating specification for the exposure.
- 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.