What is AH32 steel plate?
AH32 sits between the normal-strength grades (A–E, 235 MPa) and the H36 series (355 MPa): 315 MPa minimum yield, 440–570 MPa tensile, Charpy 31 J longitudinal at 0 °C, delivered as-rolled up to 12.5 mm and normalised, controlled-rolled or thermo-mechanically rolled above, with fine-grain treatment by aluminium, niobium, vanadium or titanium. The steel is fully killed, carbon is held at 0.18 % maximum and manganese at 0.90–1.60 %, so the carbon equivalent stays low enough that no preheat is needed below 30 mm with low-hydrogen consumables. The H32 series exists because a 315 MPa plate lets a designer use a lower material factor (k = 0.78 against 1.0 for mild steel and 0.72 for H36) with more modest alloying and better fatigue behaviour at welded details than H36 — Japanese and Korean yards standardised on it for bulk-carrier and tanker hulls, and class rules for river-sea, ferry and offshore-supply tonnage frequently call it up throughout the hull. AH32 is the 0 °C member of the series; DH32 and EH32 carry the same strength to −20 and −40 °C. Every plate is rolled at a society-approved mill, stamped with the society mark, heat number and grade, and covered by the surveyor's certificate.
Chemical composition
| Element | C | Si | Mn | P | S | Al | Nb | V | Ti | Cu | Cr | Ni | Mo |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| max. % (ladle) | ≤ 0.18 | ≤ 0.50 | 0.90–1.60 | ≤ 0.035 | ≤ 0.035 | ≥ 0.015 (total) | 0.02–0.05 | 0.05–0.10 | ≤ 0.02 | ≤ 0.35 | ≤ 0.20 | ≤ 0.40 | ≤ 0.08 |
IACS UR W11 ladle analysis for the H32 series; grain refinement by Al, Nb, V or Ti singly or in combination. CEV ≤ 0.36 typical for TM plate, ≤ 0.38 normalised.
Mechanical properties
| Property | Requirement | Typical value | Note |
|---|---|---|---|
| Yield strength ReH | ≥ 315 MPa | 335–380 MPa | |
| Tensile strength Rm | 440–570 MPa | 460–520 MPa | |
| Elongation A5 | ≥ 22 % | 26–32 % | |
| Charpy V, longitudinal | ≥ 31 J at 0 °C | 60–120 J | t ≤ 50 mm; 22 J transverse |
| Charpy V, t 50–70 mm | ≥ 38 J at 0 °C | — | 50 J above 70 mm |
| Bend test | 180°, 3 t | passes | transverse |
Equivalent grades
| System | Grade | Note |
|---|---|---|
| ASTM A131 | AH32 | identical |
| LR | AH32 | Lloyd's Register |
| DNV | NV A32 | |
| BV | AH32 | |
| ABS | AH32 | |
| GL (legacy) | GL-A32 | |
| EN 10025-2 (approx.) | S315 — none; nearest S275J0 | not a substitute: no class certificate |
| JIS G3106 (approx.) | SM400 – SM490 range | commercial only |
Class approval and delivery condition
Ordering AH32 means ordering it under a named society: the mill's approval, the plate stamp and the certificate all carry that society's mark and a plate certified LR is not automatically accepted by a BV-classed yard. Turkish and EU mills we work with hold approvals for the H32 series with LR, BV, DNV, ABS, RINA and Türk Loydu; the delivery condition (AR / N / TM) is chosen by the mill within the rules for the thickness and is stated on the certificate — TM plate keeps the low carbon equivalent that makes AH32 easy to weld at thickness. For unclassed barges and pontoons the same chemistry can be sold with a 3.1 mill certificate only, at a lower price and a shorter lead time.
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) |
|---|---|---|---|---|
| 6 mm | 47.1 | 424 | 565 | 1 413 |
| 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 |
| 80 mm | 628.0 | 5 652 | 7 536 | 18 840 |
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 80 mm and oxy-fuel above, from the yard's nesting files; bevels 30–37.5° for hull butt welds. Welding: SMAW, FCAW and SAW with consumables of grade 2Y or 3Y (class-approved, 400 MPa class); preheat is not required below 30 mm at CEV ≤ 0.36, 50 °C above; heat input up to 3.5 kJ/mm on TM plate. The plate can be shot-blasted to Sa 2½ and shop-primed with a class-approved zinc silicate (15–20 µm) before delivery, with the stamp area masked or re-marked under survey.
Where it is used
- Shell, deck and bulkhead plating of bulk carriers and tankers built to the H32 series
- Ferries, river-sea vessels and offshore supply craft
- Hatch coamings and cover plates
- Barges and pontoons (with or without class)
- Repair plate where the original hull is H32
AH32 vs AH36 vs Grade A
AH36 gives 355 MPa — 13 % more strength for a few percent more per ton, and is the more common higher-strength grade in European yards; AH32 wins where the design is already based on k = 0.78 or where the yard wants the easier welding and better fatigue ratio. Grade A is the 235 MPa mild-steel baseline, used where thickness is set by stiffness or corrosion margin rather than strength. For cold-water tonnage the same 315 MPa is available as DH32 (−20 °C) and EH32 (−40 °C).
Price
Class-certified plate is quoted per certificate lot rather than from a list band: AH32 sits a few percent below AH36 and 5–10 % above Grade A of the same thickness, plus the society survey fee per lot. Send the plate list with society and delivery 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 AH32 steel 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 8–25 mm: 2–3 weeks; mill order 4–6 weeks |
| Packing | Plates on bearers, banded, stamped; primed plates with separators |
| 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
AH32 steel plate 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 AH32, the society, thickness × width × length or the nesting list, delivery condition if the rules fix it (N / TM), shop primer, quantity and port; state whether 3.2 society certification or a 3.1 mill certificate (unclassed) is required.
Standards
- IACS UR W11
- LR / BV / DNV / ABS / RINA / TL rules
- ASTM A131 Grade AH32
- Society certificate (3.2 equivalent)
Grades
Grade data sheets (chemistry, mechanicals, equivalents) are on our reference site: AH32 · AH36 · DH32
Frequently asked questions
What is AH32 steel?
A higher-strength shipbuilding steel with 315 MPa minimum yield and 440–570 MPa tensile, impact-tested at 0 °C, killed and fine-grain treated, certified by a classification society (LR, BV, DNV, ABS, RINA, TL) to IACS UR W11 / ASTM A131.
What is the difference between AH32 and AH36?
Yield: 315 against 355 MPa; tensile 440–570 against 490–630 MPa. Same chemistry limits and impact temperature (0 °C); AH36 is stronger, AH32 has a lower yield ratio and slightly easier welding. The design series (k factor) decides.
Is AH32 weldable without preheat?
Yes below about 30 mm with low-hydrogen class-approved consumables at a carbon equivalent up to 0.36; above that 50 °C preheat is usual.
Which classification societies can certify AH32?
Lloyd's Register, Bureau Veritas, DNV (as NV A32), ABS, RINA and Türk Loydu; dual-certified plate (BV/LR, DNV/ABS) is common from the mills we use.
What thicknesses are available?
6–80 mm; 8–25 mm from class stock in 2–3 weeks, other thicknesses to mill order in 4–6 weeks, cut and bevelled at Dilovası.