What is Grade D ship plate?
The normal-strength hull steels A, B, D and E share one strength level — 235 MPa yield, 400–520 MPa tensile — and differ in toughness temperature and steelmaking: Grade A is tested at +20 °C (no test below 50 mm), B at 0 °C, D at −20 °C and E at −40 °C. Grade D is fully killed with a fine-grain treatment (aluminium ≥ 0.015 % total or an equivalent grain refiner) and, above 25 mm, must be normalised or TM-rolled; below 25 mm it may be delivered as-rolled if the mill's approval covers it. The manganese-to-carbon balance (Mn ≥ 0.60 %, C ≤ 0.21 %) and the killed practice give the fine ferrite-pearlite structure that holds 27 J at −20 °C. The class material tables call for Grade D where Grade A would be too brittle for the plate's thickness and position: sheer strake and stringer plates above about 20 mm, bilge strakes, hatch coamings, and — for vessels trading in cold waters or carrying an ice-class notation — the exposed shell and deck plating throughout. It is the natural grade for river-sea coasters, ferries, dredgers and inland tankers whose scantlings are mild-steel throughout but whose operating area includes the Black Sea or Baltic winter. Every plate is rolled at a society-approved mill, stamped with society mark, heat and grade and released on the surveyor's certificate; unclassed barge work can be supplied on a 3.1 mill certificate.
Chemical composition
| Element | C | Si | Mn | P | S | Al |
|---|---|---|---|---|---|---|
| max. % (ladle) | ≤ 0.21 | 0.10–0.35 | ≥ 0.60 | ≤ 0.035 | ≤ 0.035 | ≥ 0.015 (total) |
Fully killed, fine-grain treated (Al total ≥ 0.015 % or Al/Nb/V/Ti equivalent). C + Mn/6 ≤ 0.40 %. Normalised or TM above 25 mm.
Mechanical properties
| Property | Requirement | Typical value | Note |
|---|---|---|---|
| Yield strength ReH | ≥ 235 MPa | 255–300 MPa | |
| Tensile strength Rm | 400–520 MPa | 420–470 MPa | |
| Elongation A5 | ≥ 22 % | 28–34 % | |
| Charpy V, longitudinal | ≥ 27 J at −20 °C | 50–110 J | t ≤ 50 mm; 20 J transverse |
| Charpy V, t 50–70 mm | ≥ 34 J at −20 °C | — | |
| Bend test | 180°, 3 t | passes |
Equivalent grades
| System | Grade | Note |
|---|---|---|
| ASTM A131 | Grade D | identical |
| LR | Grade D | |
| DNV | NV D | |
| BV | Grade D | |
| ABS | Grade D | |
| GL (legacy) | GL-D | |
| EN 10025-2 (approx.) | S235J2 | no class certificate — commercial only |
| GOST 5521 (approx.) | D | CIS shipbuilding steel |
Grade selection in a mild-steel hull
| Member class | ≤ 15 mm | 15–20 mm | 20–25 mm | 25–30 mm | 30–40 mm | 40–50 mm |
|---|---|---|---|---|---|---|
| I — secondary (deck plating in general, side shell) | A | A | A | A | B | D |
| II — primary (strength deck, bottom shell, bulkheads) | A | A | B | D | D | E |
| III — special (sheer strake, stringer, bilge strake, coamings) | A | B | D | D | E | E |
| Ice-belt plating (ice class) | B | D | D | E | E | E |
Lower design temperatures shift every entry one grade towards E. The yard's plate schedule fixes the grade per position; we quote and certify to that schedule.
Thickness range and stock sizes
| Thickness | Widths × lengths | Availability |
|---|---|---|
| 6–12 mm | 2 000 / 2 500 × 6 000 / 8 000 | class-stock mills, 2–3 weeks |
| 15–30 mm | 2 000 / 2 500 / 3 000 × 6 000–12 000 | mill order 4–6 weeks |
| 32–80 mm | 2 500 / 3 000 × 6 000–12 000 | mill order 5–7 weeks |
| Cut / bevelled | plasma to 80 mm, oxy above; K/V bevels | from the nesting file |
Weight per m² and per plate
| Thickness | kg/m² | 1 500 × 6 000 (kg) | 2 000 × 6 000 (kg) | 2 500 × 12 000 (kg) |
|---|---|---|---|---|
| 8 mm | 62.8 | 565 | 754 | 1 884 |
| 10 mm | 78.5 | 707 | 942 | 2 355 |
| 12 mm | 94.2 | 848 | 1 130 | 2 826 |
| 15 mm | 117.8 | 1 060 | 1 413 | 3 533 |
| 20 mm | 157.0 | 1 413 | 1 884 | 4 710 |
| 25 mm | 196.3 | 1 766 | 2 355 | 5 888 |
| 30 mm | 235.5 | 2 120 | 2 826 | 7 065 |
| 40 mm | 314.0 | 2 826 | 3 768 | 9 420 |
| 50 mm | 392.5 | 3 533 | 4 710 | 11 775 |
| 60 mm | 471.0 | 4 239 | 5 652 | 14 130 |
Nominal weights — mill tolerance to EN 10029 class A adds up to +4 % on thin plate; invoiced on theoretical weight unless agreed otherwise.
Cutting, welding and shop primer
Plasma to 60 mm from the nesting file; bevels for hull butts. Grade D welds like any mild steel — SMAW, FCAW or SAW with class-approved grade 2 or 3 consumables, no preheat below 40 mm, heat input on TM plate kept below about 4 kJ/mm to preserve the −20 °C HAZ toughness. Sa 2½ blast and class-approved zinc silicate shop primer 15–20 µm on request, stamps re-marked under survey.
Where it is used
- Sheer strake, stringer and bilge plates of mild-steel hulls above 20 mm
- Exposed shell and deck plating for cold-water and ice-class operation
- Hatch coamings and heavy stringers in tanks
- River-sea coasters, ferries, dredgers and inland tankers
- Repair plate where the original hull was Grade D
Grade D vs Grade A vs Grade E
Grade A is the general hull plate — as-rolled, tested at +20 °C, cheapest and always in stock; Grade D replaces it where thickness, position or cold water require −20 °C toughness. Grade E takes the same 235 MPa to −40 °C for the most critical plates and Arctic service. For a higher-strength hull the −20 °C equivalents are DH32 and DH36.
Price
Grade D is quoted per certificate lot: typically 5–8 % above Grade A for the killed, fine-grain and normalised route and the −20 °C test, plus the society survey fee. Send the plate list with society and condition for a firm price within a working day.
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 for Grade D ship plate: plates banded on hardwood skids (max 5 t per pack), edges protected, heat numbers marked; A 40' HC takes 24–25 t of 6 m plate. Over-length plate is loaded flat-rack, and heavy plate above 25 t per piece travels breakbulk from Derince. HS 7208.51 / 7208.52.
| Term | Detail |
|---|---|
| MOQ | 5 t per size; 20 t per certificate lot |
| Incoterms | FOB Istanbul · CIF / CFR Gulf, Africa · DAP EU, Balkans, Iraq, Caucasus · DAP Aktau |
| Lead time | Class stock 10–25 mm: 2–3 weeks; mill order 4–6 weeks |
| Packing | Plates on bearers per size, banded and stamped; shop-primed plates with separators so the primer is not scuffed |
| Container / truck | 20' ≈ 20 t; 40' HC ≈ 24 t; 12 m and heavy plate breakbulk from Derince |
| 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
Documentation for Grade D ship plate: EN 10204 3.1 mill certificate as standard (heat number, analysis, tensile, Charpy, condition); 3.2 with an independent inspector, EN 10160 UT reports and additional low-temperature Charpy tests are available on plates above 8 mm at order.
How to order
Specify Grade D, the society, thickness × width × length or the nesting list, delivery condition (AR below 25 mm / N / TM), shop primer, quantity and port; state 3.2 society or 3.1 mill certificate.
Standards
- IACS UR W11
- LR / BV / DNV / ABS / RINA / TL rules
- ASTM A131 Grade D
- Society certificate (3.2 equivalent)
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: Grade D · Grade A · Grade E
Frequently asked questions
What is Grade D ship steel?
Normal-strength shipbuilding steel with 235 MPa yield and 400–520 MPa tensile, fully killed and fine-grain treated, impact-tested at −20 °C (27 J), normalised or TM-rolled above 25 mm and certified by a classification society.
What is the difference between Grade A and Grade D?
Same strength; Grade A is as-rolled and tested at +20 °C, Grade D is killed, fine-grain, normalised above 25 mm and tested at −20 °C. Class rules require D for thicker and more critical plates and cold-water service.
Is Grade D the same as S235J2?
Mechanically close (235 MPa, −20 °C impact) but S235J2 is a structural grade with no class certificate and no fine-grain / normalising requirement; it cannot be used in a classed hull.
Does Grade D need preheat for welding?
No, below 40 mm with low-hydrogen class-approved consumables; heat input on TM plate is kept below about 4 kJ/mm.
Which societies can certify Grade D?
LR, BV, DNV (NV D), ABS, RINA and Türk Loydu; dual certification is common.