KR RD36 Shipbuilding Steel Plate

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

KR RD36 is the Korean Register higher-strength grade with Charpy at −20 °C (IACS UR W11 equivalent DH36). KR plan approval on Korean-built tankers and container ships assigns RD36 to thicker deck, bottom and sheer strakes where 0 °C is not enough. Strength level 36 means minimum yield 355 N/mm², tensile 490–630 N/mm² and elongation 21 % min. (A5). The letter D fixes Charpy V-notch testing at −20 °C. In commercial enquiries it is called KR RD36 shipbuilding steel plate; “KR DH36” is a common but unofficial way of writing it.

Equivalent grades: KR RD36 ≈ ASTM A131 Grade DH36 ≈ ABS DH36 ≈ DNV NV D36 ≈ LR DH36 ≈ BV DH36 ≈ CCS D36 / DH36 ≈ NK KD36 ≈ RINA DH36 ≈ GB 712 Grade DH36 (all class-approved, stamped by the issuing society).

KR RD36 is selected when the scantling needs the 36 yield band and the KR material class assigns −20 °C toughness. Ordinary-strength KR RA–RE stay at 235 N/mm² and cannot replace RD36 without a drawing change. In the KR ladder for strength 36: RA36 0 °C → RD36 −20 °C → RE36 −40 °C → RF36 −60 °C; within the D letter, RA32 → RA36 → RA40-style steps raise yield from 315 to 355 to 390 N/mm².

Plates that pass mill tests under KR survey are stamped with the KR mark and RD36 (stencils sometimes add the IACS form DH36 for the yard; plus Z or U where through-thickness or ultrasonic requirements apply) and are supplied with a mill certificate the KR Surveyor endorses. SHH STEEL supplies KR RD36 from Chinese mills that hold KR works approval for the grade, from stock in common sizes or from a mill rolling cycle, with KR survey arranged at the mill.

Size range. Common market thicknesses for RD36 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 / KR works approval. Ask for confirmation above 100 mm.

Product (check) analysis column: KR Rules (Part 2) 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), adopted by Korean Register for KR RD36 in Rules for the Classification of Steel Ships Pt 2 (KR paragraph numbers UNCERTAIN). The full grain-refining and residual set (Al, Nb, V, Ti, Cu, Cr, Ni, Mo, N) is shown so you can check every row on the certificate. 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 36):

Same tensile band applies to A/AH, D/DH, E/EH and F/FH 36; 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 DH36 (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 RD36, respect Ceq caps ≈ 0.38 % (t≤50) / 0.40 % (50

Korean 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, EN 10029 or GB/T 709). Surface quality per EN 10163 or equivalent accepted by KR; state primer/surface class on receipt if needed.

Quantities are approximate and change daily (indicative — confirm before booking); all stock plates carry KR RD36 marking and KR-endorsed mill certificates when sold as KR 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 KR 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 KR 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 (KR + ABS / DNV / LR / BV) require joint survey before rolling. Other KR siblings in the 36 band are linked via KR until each product page is live.

Pick RD36 when the drawing specifies higher-strength grade DH36 (KR writes DH36 as RD36). Do not substitute ordinary Grade A/B unless the designer recalculates scantlings — yield differs (355 vs 235). Within the 36 band, letter choice is toughness: A/AH 0 °C → D/DH −20 °C → E/EH −40 °C → F/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 KR moves to extra-high strength (IACS UR W16): RA43…RF70, numbered by ABS-style yield class (420 → 43 … 690 → 70; UNCERTAIN vs local KR text) rather than CCS/DNV DH420 or BV A420.

When KR RD36 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 355 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 built to KR class. 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 RD36 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 KR RD36: 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 Korean Register survey; the mill certificate lists heat number, ladle chemistry, Ceq where applicable, tensile results (ReH ≥ 355 N/mm², Rm 490–630 N/mm², A ≥ 21 %), Charpy at −20 °C, delivery condition and plate numbers, endorsed by the Surveyor. Optional EN 10204 3.2, UT (U), Z-direction, multi-class with ABS/DNV/LR/BV.

On receipt: verify KR RD36 (or KR RD36) stamp, −20 °C impact data, energies for the delivered thickness band, thickness within UR W13 / PO tolerance, KR Surveyor endorsement present — not a mill-only certificate.

Charpy acceptance for KR RD36 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 “KR 36” without the letter — toughness class missing
• Writing DH36 (ABS/CCS style) on a KR PO without stating KR RD36 — the KR certificate and stamp read RD36
• Accepting ordinary-strength Grade A/B certificates for a RD36 PO
• Accepting a DH36 certificate from another society (or a product-standard paper) where KR RD36 is specified
• 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 KR endorsement on the MTC
• Writing DNV NV D36 or LR/DH36 on a KR-class PO without arranging that society’s survey

Write the KR grade (RD36), delivery condition, impact temperature and certificate type into the PO.

Specify KR RD36 (KR RD36), 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 KR Rules for the Classification of Steel Ships, Pt 2, Grade RD36 (KR RD36), delivery condition [AR/CR/N/TM/QT], 20 × 2500 × 12000 mm, 30 pcs, marked KR RD36, certificate endorsed by KR Surveyor, EN 10204 3.2 [if required], UT [if required], CIF [port].”

KR RD36 / KR RD36 is higher-strength hull steel under KR Rules for the Classification of Steel Ships, Pt 2 and IACS UR W11: yield 355 N/mm², tensile 490–630 N/mm², Charpy at −20 °C, marking KR RD36. DH36 is the cross-society name for the same IACS grade, but only the KR RD36 stamp and KR-endorsed certificate are accepted for KR class. 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 KR RD36 plate rolled by Chinese mills that hold Korean Register works approval for the grade, so every plate carries the KR RD36 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 KR survey arranged at the mill. On request we add EN 10204 3.2 certificates with third-party witness (TÜV, SGS, LR or another agency) and joint certification with ABS, DNV, LR, BV, 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 KR RD36 mixed with KR RA/RB/RD/RE or other RA–RF 32/36/40 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 (KR RD36 / KR RD36), 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.