LR DH32 Steel Plate | LR/DH32 Marine Steel Plate

Technical Reviewer: Jack | SHH STEEL Material Solutions Department · Updated: 2026-10-27

LR DH32, often written LR/DH32 on mill certificates and plate markings, is a higher-strength hull structural steel under Lloyd’s Register Rules for the Manufacture, Testing and Certification of Materials, which implement IACS UR W11 for the AH–FH 32/36/40 family. Strength level 32 means minimum yield 315 N/mm², tensile 440–590 N/mm² and elongation 22 % min. (A5). The letter DH fixes Charpy V-notch testing at −20 °C. In commercial enquiries it is called LR DH32 or LR/DH32 marine steel plate.

Equivalent grades: LR DH32 ≈ ASTM A131 Grade DH32 ≈ ABS DH32 ≈ DNV NV D32 ≈ BV DH32 ≈ CCS D32 / DH32 ≈ NK KD32 ≈ KR RD32 ≈ RINA DH32 ≈ GB 712 Grade DH32 (all class-approved, stamped by the issuing society).

LR/DH32 is selected when scantlings need the higher yield of the 32 band and the material class assigns −20 °C toughness. Ordinary-strength LR Grade A–E stay at 235 N/mm² yield and cannot replace DH32 without a drawing change. Within the 32 band, letter choice is toughness: AH 0 °C → DH −20 °C → EH −40 °C → FH −60 °C; within the DH letter, strength steps 32 → 36 → 40 raise yield from 315 to 355 to 390 N/mm².

Plates that pass mill tests under Lloyd’s Register survey are die-stamped or stencilled LR DH32 or LR/DH32 (plus Z or U where through-thickness or ultrasonic requirements apply) and are supplied with a mill certificate the LR Surveyor endorses. SHH STEEL supplies LR/DH32 from Chinese mills that hold Lloyd’s Register works approval for the grade, from stock in common sizes or from a mill rolling cycle, with LR survey arranged at the mill.

Size range. Common market thicknesses for DH32 are about 6–80 mm (heavier plates available as per mill approval), widths 1500–3500 mm. Exact maximum thickness for a given delivery condition is as per standard and mill certificate / LR works approval. Ask for confirmation above 100 mm.

Product (check) analysis column: LR Rules for Materials specify heat (ladle) limits; no numeric product-analysis tolerance is tabulated in the rule text reviewed, so product (check) limits are agreed on the order or taken from the approved mill specification and certificate.

Source: IACS UR W11 higher-strength chemistry tables (ladle samples) — the chemistry Lloyd’s Register applies to LR/DH32. AH/DH/EH share one chemistry column; FH is tighter on C, P, S and adds N control with higher Ni allowance. Toughness is differentiated by impact temperature and supply routes, not by separate C/Mn caps within AH/DH/EH. Product (check) analysis numeric tolerances are not tabulated in UR W11; when required, agree tolerances at enquiry. TMCP steels must also meet the applicable Ceq / Pcm limits on the mill approval — ask for Ceq on the certificate.

Alternative flat-specimen elongations by thickness (indicative UR W11 / industry table for strength 32):

Same tensile band applies to AH/DH/EH/FH 32; only impact temperature and chemistry group (FH vs AH/DH/EH) change across the letter.

Source: IACS UR W11 impact table for higher-strength Grade DH32 (full-size; either direction acceptable unless specified). Energies rise with thickness — a 60 mm plate must meet higher values than a 20 mm plate at the same −20 °C. Condition of supply and impact lot size depend on grain-refining practice and thickness (AR/CR/N/TM/QT as permitted). For TMCP DH32, respect Ceq caps ≈ 0.36 % (t≤50) / 0.38 % (50

Lloyd’s Register applies IACS UR W13 thickness tolerances unless the PO states otherwise (often 0.3 mm minus class — confirm on PO; see UNCERTAIN). Plus/flatness/width/length per agreed standard (ASTM A6 or EN 10029). Surface quality per EN 10163 or equivalent accepted by LR; state primer/surface class on receipt if needed.

Quantities are approximate and change daily (indicative — confirm before booking); all stock plates carry LR/DH32 marking and LR-endorsed mill certificates when sold as LR class plate. Sizes outside the table (for example 3000 mm width, 60–100 mm thickness, or fixed lengths for a cutting plan) are produced in the next mill rolling cycle, typically 3–6 weeks including LR survey. Send your size list and we will reply with what is in stock and what must be rolled.

Packing. Plates are bundled by size with steel strapping, marked with heat number, grade and LR stamp, and shipped in containers (up to about 11.8 m) or break bulk for longer plates.

These are comparisons, not substitutions. Multi-class stamps require joint survey before rolling.

Pick DH32 when the drawing specifies higher-strength grade DH32 (or the society equivalent). Do not substitute ordinary Grade A/B unless the designer recalculates scantlings — yield differs (315 vs 235). Within the 32 band, letter choice is toughness: AH 0 °C → DH −20 °C → EH −40 °C → FH −60 °C. Within the DH letter, strength steps 32 → 36 → 40 raise yield from 315 to 355 to 390 N/mm².

For yields above 390 N/mm² Lloyd’s Register / IACS move to extra-high strength (UR W16 naming — LR uses AH42…AH69, not AH420 / AH70).

When LR LR/DH32 is the right choice: typical uses are higher-strength members that the material class table assigns to −20 °C, such as thicker deck and bottom strakes, sheer strakes and hatch coamings. The Charpy temperature (−20 °C) is fixed by the letter, and the strength by the number (ReH 315 N/mm²). Pick the strength from the scantling calculation and the letter from the material class and design temperature on the approved drawing.

Typical uses: higher-strength members that the material class table assigns to −20 °C, such as thicker deck and bottom strakes, sheer strakes and hatch coamings; weight-saving vs ordinary-strength plate in large tankers, bulkers and container ships. See offshore platform steel plates when primary offshore grades apply.

Welding: higher-strength hull steels need approved higher-strength consumables matched to −20 °C weld-metal toughness; preheat and heat input follow the approved WPS and often track Ceq/Pcm from the mill certificate. TMCP DH32 must respect the Ceq caps noted above. Cutting by oxy-fuel/plasma/laser is routine; thick FH plate may need hydrogen control — follow mill recommendations.

Processing notes for LR/DH32: cold forming is routine within normal shipyard radii. Line heating and fairing of TMCP plate should stay within the temperature limits recommended by the mill, because overheating can reduce the strength gained in controlled rolling. Check the delivery condition on the certificate before planning hot forming.

Every plate is tested and marked at the mill under Lloyd’s Register survey; the mill certificate lists heat number, ladle chemistry, Ceq where applicable, tensile results (ReH ≥ 315 N/mm², Rm 440–590 N/mm², A ≥ 22 %), Charpy at −20 °C, delivery condition and plate numbers, endorsed by the Surveyor. Optional EN 10204 3.2, UT (U), Z-direction, multi-class.

On receipt: verify LR/DH32 stamp, −20 °C impact data, energies for the delivered thickness band, thickness within UR W13 / PO tolerance, LR endorsement present.

Charpy acceptance for LR/DH32 by thickness (IACS UR W11; actual results as per standard and mill certificate):

If UT or 3.2 was ordered, check the UT report and inspector’s plate list as well.

• Ordering “LR 32” without the letter (DH/…) — toughness class missing
• Accepting ordinary-strength Grade A/B certificates for a DH32 PO
• Ignoring TMCP Ceq caps on TM plate
• Substituting a different letter (e.g. AH for DH) without drawing approval
• Coil-cut plate without coil approval
• Missing LR endorsement on the MTC

Write grade, delivery condition, impact temperature and certificate type into the PO.

Specify LR DH32 (LR/DH32), delivery condition (AR/CR/N/TM/QT as applicable), thickness × width × length × qty, Z/U, multi-class, certificate type, port. Send to SHH STEEL.

Sample PO line: “Steel plate to Lloyd’s Register Rules for Materials, Grade DH32 (LR/DH32), delivery condition [AR/CR/N/TM/QT], 20 × 2500 × 12000 mm, 30 pcs, marked LR DH32 / LR/DH32, certificate endorsed by LR Surveyor, EN 10204 3.2 [if required], UT [if required], CIF [port].”

LR DH32 / LR/DH32 is higher-strength hull steel under Lloyd’s Register Materials rules and IACS UR W11: yield 315 N/mm², tensile 440–590 N/mm², Charpy at −20 °C, marking LR/DH32. Lock on the order: delivery condition, impact lot size, TMCP Ceq if TM, product analysis if needed, multi-class and 3.2.

SHH STEEL supplies LR/DH32 plate rolled by Chinese mills that hold Lloyd’s Register works approval for the grade, so every plate carries the LR/DH32 stamp and a Surveyor-endorsed certificate traceable to its heat. Common thicknesses are available from stock; other sizes are scheduled into the mill rolling cycle with LR survey arranged at the mill. On request we add EN 10204 3.2 certificates with third-party witness (TÜV, SGS, BV or another agency) and joint certification with ABS, DNV, BV, CCS, NK, KR or RINA.

We accept T/T or L/C payment, with inspection before the balance is paid. Small quantities in several sizes, or LR/DH32 mixed with LR Grade A/B/D/E or other AH–FH sizes, can be combined in one container. A dedicated coordinator sends production and shipping updates with photos, and our own workshop cuts to size, bevels, drills and machines plates before shipment so they arrive ready for fabrication.

Request a quotation: send SHH STEEL the grade (LR/DH32 / LR DH32), thickness, width, length, quantity per size and destination port, plus any multi-class, Z/U or 3.2 certificate requirement. We reply with price, available stock and lead time.