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Materials
SGCC hot-dip galvanized steel
SGCC is hot-dip zinc-coated steel sheet and coil to JIS G 3302, equivalent to EN DX51D+Z and ASTM A653 CS. The zinc layer protects the steel without painting, so SGCC is widely used for cabinets, enclosure panels and internal brackets. We stamp SGCC from 1.2 mm coil and fabricate SGCC sheet into enclosures and cabinets.
Key specs at a glance
| Standard | JIS G 3302 |
|---|---|
| Equivalents | EN DX51D+Z (EN 10346), ASTM A653 CS, GB DX51D+Z |
| In production at Sierxi | 1.2 mm coil for stamping; sheet for fabrication |
| Coating | State coating mass, e.g. Z12, Z18, Z27 |
What is SGCC?
SGCC is commercial-quality steel coil that has been passed through molten zinc. The zinc protects the steel as a barrier and also sacrificially: where the coating is scratched, the surrounding zinc corrodes first. That is why SGCC parts can be used bare indoors and are a common base for powder-coated outdoor cabinets.
SGCD and higher grades in the same standard offer better formability. For most brackets and cabinet panels, SGCC is sufficient.
Coating mass designations
The base grade says nothing about how much zinc is on the sheet. Always specify the coating designation.
| JIS designation | Minimum total coating, both sides (g/m², triple-spot average) | Approx. zinc per side | Approx. ASTM A653 equivalent |
|---|---|---|---|
| Z08 | 80 | about 6 μm | G30 (approx.) |
| Z12 | 120 | about 8 μm | G40 (approx.) |
| Z18 | 180 | about 13 μm | G60 |
| Z27 | 275 | about 19 μm | G90 |
Surface options to state on the order
| Option | Choices |
|---|---|
| Spangle | Regular spangle or minimized spangle (better for painting) |
| Chemical treatment | Chromate-free passivation, oiled, or untreated |
| Painting afterwards | Tell us, so the treatment does not interfere with paint adhesion |
Design and fabrication notes for SGCC
- Cut edges and punched holes expose bare steel. Zinc gives some sacrificial protection near the edge, but edges are the first place red rust appears in humid or outdoor conditions.
- Bending is fine with an inside radius of about 1 × t; very tight bends can crack or flake the zinc on the outside of the bend.
- Welding burns off the zinc at the seam and creates zinc fumes and porosity. Avoid welds on SGCC where possible, or plan for zinc-rich touch-up or coating after welding.
- For powder coating over SGCC, specify a suitable pretreatment; our finishing partners confirm the process.
- Grounding: zinc and chromate-free treatments are conductive enough for most earthing points, but mask or specify contact areas if bonding resistance matters.
Typical properties
| Property | Typical value |
|---|---|
| Base metal | Low-carbon commercial-quality steel |
| Density (steel) | about 7.85 g/cm³ |
| Magnetic | Yes |
| Zinc layer | As specified by coating designation |
How to call out SGCC on a drawing
- Grade, coating and standard: for example “SGCC Z12 (JIS G 3302)” or “DX51D+Z140 (EN 10346)”
- Thickness, and whether it is measured including or excluding the zinc
- Spangle and chemical treatment
- Whether the part is powder coated afterwards
- Welds, if any, and how they are to be touched up
SGCC vs SPCC vs SUS304 for cabinets
| Material | Corrosion protection | Cost | Typical cabinet use |
|---|---|---|---|
| SPCC + powder coat | From the coating only | Low | Indoor painted cabinets |
| SGCC (bare or powder coated) | Zinc layer, plus coating if applied | Medium | Internal panels; outdoor cabinets when coated |
| SUS304 | Inherent | High | Wash-down, humid or exposed sites |
Frequently asked questions
Is SGCC the same as DX51D+Z?
They are close equivalents. The coating designation must be specified separately in both standards, for example Z12 in JIS or Z275 in EN.
Does SGCC need painting?
Not indoors in most cases. For outdoor or humid environments, powder coating over SGCC gives longer protection than either alone.
Can SGCC be laser welded?
It can, but zinc vaporizes at the seam, causing spatter and porosity, and the coating is lost there. We recommend avoiding welds on SGCC, or planning touch-up after welding.
Why do SGCC cut edges rust?
Laser cutting and punching expose bare steel at the edge. The surrounding zinc protects it sacrificially for a while, but in humid or outdoor conditions edges show rust first. Powder coating after fabrication covers them.
What SGCC thickness do you stamp?
We currently run 1.2 mm SGCC coil; our stamping range is 0.15–1.2 mm. Thicker sheet is laser cut and bent.
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