What is S350GD galvanized steel?
S350GD is produced from a micro-alloyed (Nb or Ti) low-carbon strip, hot-rolled pickled or cold-rolled, that reaches 350 MPa yield with a fine grain rather than with carbon — so it still bends at 1.5 × t, roll-forms lips and stiffeners, and welds without preheat. EN 10346 guarantees yield ≥ 350 MPa, tensile ≥ 420 MPa and 16 % elongation; typical certificates show 380–420 MPa yield. In EN 1993-1-3 design the higher fyb translates directly into capacity: a Z-purlin in S350GD carries about 25 % more than the same section in S280GD, and a composite deck profile can drop a gauge. That is why S350GD has become the reference grade for composite floor decking (EN 1994), long-span and snow-load purlins, solar mounting structures (rails, posts, trackers), heavy racking uprights, light-gauge steel-framed buildings and highway components. It is delivered with Z275 as the export standard, Z350 for agriculture and coastal sites, and — on request — with a zinc-magnesium (ZM) coating for solar and coastal structures. The old EN 10147 name Fe E 350 G and the ASTM comparison SS Grade 50 are still common in tenders.
Chemical composition
| Element | C | Si | Mn | P | S | Nb + Ti |
|---|---|---|---|---|---|---|
| max. % (ladle) | 0.20 | 0.60 | 1.70 | 0.10 | 0.045 | ≤ 0.10 (micro-alloy) |
Typical heat: C 0.06–0.10, Mn 0.60–1.20, Nb 0.02–0.04 or Ti 0.03–0.06.
Mechanical properties
| Property | Requirement | Typical value | Note |
|---|---|---|---|
| Yield strength ReH / Rp0.2 | ≥ 350 MPa | 380–420 MPa | fyb = 350 |
| Tensile strength Rm | ≥ 420 MPa | 450–500 MPa | |
| Elongation A80 | ≥ 16 % | 19–24 % | |
| Bend radius (180°) | 1.5 × t | passes |
Equivalent grades
| System | Grade | Note |
|---|---|---|
| EN 10147 (old) | Fe E 350 G / S350GD+Z | withdrawn |
| DIN 17162 | StE 350 Z | historic |
| ASTM A653 | SS Grade 50 Class 1 (340 MPa) / HSLAS Gr. 50 | near |
| JIS G3302 | SGC490 / SGC570 (near) | |
| GB/T 2518 | S350GD+Z | |
| EN 10346 | S390GD / S420GD / S550GD | higher grades on request |
Zinc coating classes (Z100–Z600)
| Class | Zinc mass (g/m², both sides) | Thickness per side (µm) | Typical life C3 | Where used |
|---|---|---|---|---|
| Z100 | 100 | ≈ 7 | 4–6 years | indoor, painted parts, ducting |
| Z140 | 140 | ≈ 10 | 6–9 years | the Turkish stock standard |
| Z200 | 200 | ≈ 14 | 9–13 years | roofing, outdoor cladding |
| Z275 | 275 | ≈ 20 | 12–18 years | export standard, purlins, structural |
| Z350 | 350 | ≈ 25 | 15–22 years | agriculture, coastal |
| Z450 / Z600 | 450 / 600 | ≈ 32 / 42 | 20–35 years | highway, marine, ground contact |
Life = time to 5 % red rust per ISO 9223 C3 (0.7–2.1 µm zinc loss per year); halve it for C4 industrial-coastal, double it for C2 rural. Spangle: normal (N) or minimised (M); surface quality A (normal) or B (improved, for painting); surface treatment C (chemical passivation), O (oiled), CO (both).
Thickness range and stock sizes
| Thickness | Widths × lengths | Availability |
|---|---|---|
| 0.60–1.2 mm | coil 1 000 / 1 250 / 1 500 mm (decking widths) | stock Z275 |
| 1.5–3.0 mm | coil 1 250 / 1 500 mm; slit to purlin and rail widths | stock Z275 |
| Z350 / ZM120–ZM310 | coil 1 250 / 1 500 mm | to order 3 weeks |
| S390GD–S550GD | coil 1 250 mm | to order 4 weeks |
Weight per m² and per sheet
| Thickness | kg/m² | 1 000 × 2 000 (kg) | 1 250 × 2 500 (kg) | 1 500 × 3 000 (kg) |
|---|---|---|---|---|
| 0.6 mm | 4.99 | 10.0 | 15.6 | 22.4 |
| 0.7 mm | 5.77 | 11.5 | 18.0 | 26.0 |
| 0.8 mm | 6.56 | 13.1 | 20.5 | 29.5 |
| 1 mm | 8.13 | 16.3 | 25.4 | 36.6 |
| 1.2 mm | 9.70 | 19.4 | 30.3 | 43.6 |
| 1.5 mm | 12.05 | 24.1 | 37.7 | 54.2 |
| 2 mm | 15.98 | 32.0 | 49.9 | 71.9 |
| 2.5 mm | 19.90 | 39.8 | 62.2 | 89.6 |
| 3 mm | 23.83 | 47.7 | 74.5 | 107.2 |
Includes Z275 coating; subtract 0.135 kg/m² for Z140.
Forming, welding and design
Roll-forms decking, purlins, sigma and rail profiles at 1.5 × t inside radius; spring-back is noticeably higher than S280GD (allow 3–5° over-bend) and lip stiffeners need proper roll design. Punching clearance 10–12 %. MAG and spot welding with fume extraction, no preheat; shear-stud welding through 0.75–1.25 mm deck works with Z275. Design to EN 1993-1-3 / EN 1994-1-1 with fyb = 350 MPa, fu = 420 MPa, core thickness = nominal − 0.04 mm (Z275). Do not hot-form or galvanize again after forming — the micro-alloyed strip is already coated.
Where it is used
- Composite floor decking (EN 1994) 0.75–1.25 mm
- Long-span and snow-load C / Z purlins 1.5–3.0 mm
- Solar mounting rails, posts, purlins and tracker components
- Heavy racking uprights and mezzanine joists
- Light-gauge steel-framed buildings (studs, joists, trusses)
- Guardrail posts and highway furniture
S350GD vs S280GD — when the upgrade pays
At about 20 USD/t more per ton, S350GD carries 25 % more than S280GD in the same section, so any purlin or deck schedule governed by strength (not deflection) saves weight and money by upgrading. Deflection-governed spans gain nothing — the modulus is the same — and S280GD stays the better buy. Forming is the other limit: S350GD needs 1.5 × t radii and firmer tooling. See S280GD for the standard purlin grade and S320GD for the intermediate step; finished C & Z purlins and composite deck are rolled from S350GD on request.
Price
S350GD carries about 30 USD/t over DX51D of the same thickness and coating; the bands below are indicative FOB Istanbul for our stock by thickness. ZM coatings and grades above S350GD are quoted per order.
Bands from our weekly export list (September 2026), FOB Istanbul, full-container quantities, excluding freight and certificates. Firm price per project on RFQ within one working day.
Export and packing
Packing of S350GD galvanized steel: coils on cradles (eye-to-sky, VCI wrap, four straps, 5–25 t) or sheet packs on skids up to 3 t with interleaving paper and corner protectors; 20' ≈ one coil (≤ 20 t), 40' HC ≈ two coils or 24 t of sheet. Tariff 7210 / 7209 / 7208.
| Term | Detail |
|---|---|
| MOQ | One coil (10–20 t) or 5 t of slit strip |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus · DAP Aktau |
| Lead time | Stock 0.60–3.0 mm Z275: 3–5 working days; slit strips 5–8 days; Z350 / ZM to order 3 weeks |
| Packing | Coil eye-to-sky, VCI wrap; slit coils on pallets |
| Container / truck | 20' one coil ≤ 20 t; 40' HC two coils |
| Documents | Invoice, packing list, EN 10204 3.1 (3.2 on request), certificate of origin; SASO / SONCAP / PVoC on request |
| Payment | 30% advance, balance against B/L copy; L/C at sight for orders above 100 t |
Certificates and testing
S350GD galvanized steel ships with EN 10204 3.1 certificates cross-referenced to the stencilled heat numbers. Where the project requires it we arrange 3.2 certification with Lloyd's, BV, TÜV or SGS, ultrasonic examination to EN 10160 and Charpy testing at the temperature you specify.
How to order
Specify thickness × width (or slit widths), coating (Z275 standard, Z350 or ZM on request), spangle, tonnage and the product (deck / purlin / rail) — we advise if a lower grade would do and quote finished profiles from our own lines.
Standards
- EN 10346:2015 — S350GD+Z, 1.0529
- EN 10143 — tolerances
- EN 1993-1-3 / EN 1994-1-1 — design (fyb = 350 MPa)
- EN 10204 3.1
- Former EN 10147 Fe E 350 G
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: S350GD · S280GD · S320GD
Frequently asked questions
What is S350GD?
A high-strength structural hot-dip galvanized strip to EN 10346 (1.0529) with guaranteed yield ≥ 350 MPa and tensile ≥ 420 MPa, used for composite decking, long-span purlins, solar structures and light-gauge framing; old name Fe E 350 G.
What is the yield strength of S350GD?
Minimum 350 MPa by the standard; typical mill certificates show 380–420 MPa.
What is the difference between S350GD and S280GD?
Guaranteed yield 350 vs 280 MPa — about 25 % more capacity for the same section, 1.5 × t instead of 1 × t bend radius, and about 20 USD/t higher price.
What is the ASTM equivalent of S350GD?
ASTM A653 SS Grade 50 Class 1 (340 MPa) or HSLAS Grade 50; JIS SGC490 is close.
Is S350GD suitable for solar mounting structures?
Yes — it is the standard grade for rails, posts and tracker parts; order Z350 or a zinc-magnesium coating for coastal or high-corrosion sites.
Is S350GD in stock in Turkey?
Yes — 0.60–3.0 mm with Z275 in 1 000–1 500 mm widths at Dilovası; slitting in 5–8 days.