Cold-rolled (CRC / DC01) vs galvanized (GI / DX51D) sheet — which one to order
Galvanized sheet is cold-rolled sheet with 100–275 g/m² of zinc on it — same base steel, same gauges, 5–15% more per ton — so the question is whether the part will be painted or powder-coated after fabrication (cold-rolled) or must resist rust as delivered (galvanized). Everything else follows from that.
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Side by side
| Cold-rolled (CRC, DC01–DC04) | Galvanized (GI, DX51D–DX54D) | |
|---|---|---|
| What it is | Cold-reduced, annealed, skin-passed steel, bare | The same cold-rolled strip hot-dip coated with zinc |
| Surface | Bright or matt, oiled; rusts within weeks if wet | Spangled zinc, passivated; 10–40 yr outdoors by zinc class |
| Thickness | 0.40–3.00 mm | 0.30–4.00 mm |
| Tolerance | EN 10131 (±0.05–0.12 mm) | EN 10143 (±0.05–0.19 mm) |
| Formability | DC01–DC06: best, deep drawing | DX51D–DX54D: very good; zinc may flake at tight radii |
| Welding | Clean, no fumes | Spot / MIG fine; zinc fumes, extraction needed |
| Painting / powder | Excellent adhesion after degreasing | Needs phosphate / etch primer; powder OK on chromate-free |
| Price per ton | 1.00 | 1.05–1.15 (Z140) to 1.20 (Z275) |
| Typical use | Appliances, furniture, enclosures, doors (painted), drums | Roofing, ducting, purlins, panels, outdoor parts, unpainted |
Decision table
| The part will be… | Order | Why |
|---|---|---|
| Powder-coated or wet-painted indoors | Cold-rolled DC01 | Cheaper, best paint finish, no zinc fumes |
| Painted but stored or used in humid / coastal air | Galvanized DX51D + paint | Zinc under the paint doubles the life |
| Left unpainted outdoors | Galvanized Z200–Z275 (or aluzinc) | Only the zinc protects it |
| Deep-drawn (sinks, housings) | Cold-rolled DC04–DC06 | Highest drawability; zinc would crack |
| Roll-formed (roofing, purlins, ducting) | Galvanized DX51D / S350GD+Z | Coated before forming, no post-treatment |
| Welded frames to be hot-dip galvanized after | Cold-rolled or HRPO | Galvanize the finished frame instead |
| Visible bright metal (trim, reflectors) | Cold-rolled BA or stainless | Zinc spangle is not decorative |
Corrosion: the only real difference
Bare cold-rolled steel corrodes at 20–80 µm per year in humid or coastal air and shows red rust within days if wet; it survives only under paint or oil. Zinc corrodes 20–50× slower and protects cut edges sacrificially: Z140 lasts 10–15 years rural, Z275 25–30 years rural and 8–12 years coastal (see the galvanized coil page for the class table). For long-life outdoor use without paint, aluzinc AZ150 or zinc-magnesium ZM go further still.
Price and availability
On our weekly export list galvanized DX51D+Z140 runs 5–15% above cold-rolled DC01 of the same thickness (the zinc plus the coating line), Z275 a few percent more; both are stocked in 0.40–3.0 mm × 1 000–1 500 mm in Dilovası. Bands: cold-rolled DC01 and galvanized DX51D.
Common mistakes
- Ordering cold-rolled for a Gulf or West African destination and storing it in an open warehouse — it rusts before use; order galvanized or ship with VCI and use within weeks
- Welding galvanized sheet without extraction (zinc fume fever)
- Powder-coating chromate-passivated galvanized sheet without pre-treatment — adhesion failures; specify chromate-free (Cr-free) passivation
- Specifying DC01 for deep-drawn parts — use DC04; or DX51D for drawing — use DX53D/DX54D
- Comparing quotes per ton without the zinc class: Z100 is not Z275
Frequently asked questions
Is galvanized sheet stronger than cold-rolled?
No — the base steel is the same (DX51D ≈ DC01); zinc adds corrosion protection, not strength. Structural galvanized grades S250GD–S350GD have guaranteed yield for purlins and decking.
Can I paint galvanized sheet?
Yes with an etch or phosphate primer (or on chromate-free passivation); pre-painted PPGI is galvanized sheet painted on the coil line and is the better answer for volume.
How much more does galvanized cost?
Typically 5–15% per ton over cold-rolled at the same thickness for Z140, up to 20% for Z275.
Which should I import for a workshop making painted enclosures?
Cold-rolled DC01 — better paint finish, lower price — provided it is stored dry and used within a few months; in humid climates add VCI packing or switch to galvanized.
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