KR RA32 Shipbuilding Steel Plate

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

Korean Register writes its 0 °C higher-strength hull steel as KR RA32 — official KR designation RA32, not “AH32”. KR Rules for the Classification of Steel Ships, Pt 2, keep the IACS UR W11 numbers, but the R prefix replaces the H used by ABS, CCS and DNV; on a KR certificate you will read RA32. Strength level 32 means minimum yield 315 N/mm², tensile 440–590 N/mm² and elongation 22 % min. (A5). The letter A fixes Charpy V-notch testing at 0 °C. In commercial enquiries it is called KR RA32 shipbuilding steel plate; “KR AH32” is a common but unofficial way of writing it.

Equivalent grades: KR RA32 ≈ ASTM A131 Grade AH32 ≈ ABS AH32 ≈ DNV NV A32 ≈ LR AH32 ≈ BV AH32 ≈ CCS A32 / AH32 ≈ NK KA32 ≈ RINA AH32 ≈ GB 712 Grade AH32 (all class-approved, stamped by the issuing society).

KR RA32 is selected when the scantling needs the 32 yield band and the KR material class assigns 0 °C toughness. Ordinary-strength KR RA–RE stay at 235 N/mm² and cannot replace RA32 without a drawing change. In the KR ladder for strength 32: RA32 0 °C → RD32 −20 °C → RE32 −40 °C → RF32 −60 °C; within the A 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 RA32 (stencils sometimes add the IACS form AH32 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 RA32 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 RA32 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 RA32 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 32):

Same tensile band applies to A/AH, D/DH, E/EH and F/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 AH32 (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 0 °C. Condition of supply and impact lot size depend on grain-refining practice and thickness (AR/CR/N/TM/QT as permitted). For TMCP RA32, respect Ceq caps ≈ 0.36 % (t≤50) / 0.38 % (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 RA32 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 32 band are linked via KR until each product page is live.

Pick RA32 when the drawing specifies higher-strength grade AH32 (KR writes AH32 as RA32). 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: A/AH 0 °C → D/DH −20 °C → E/EH −40 °C → F/FH −60 °C. Within the AH 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 AH420 or BV A420.

When KR RA32 is the right choice: typical uses are higher-strength hull girder plating (deck, bottom, side shell) of bulk carriers, tankers and container ships in normal service where 0 °C toughness suffices. The Charpy temperature (0 °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 hull girder plating (deck, bottom, side shell) of bulk carriers, tankers and container ships in normal service where 0 °C toughness suffices; 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 0 °C weld-metal toughness; preheat and heat input follow the approved WPS and often track Ceq/Pcm from the mill certificate. TMCP RA32 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 RA32: 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 ≥ 315 N/mm², Rm 440–590 N/mm², A ≥ 22 %), Charpy at 0 °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 RA32 (or KR RA32) stamp, 0 °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 RA32 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 32” without the letter — toughness class missing
• Writing AH32 (ABS/CCS style) on a KR PO without stating KR RA32 — the KR certificate and stamp read RA32
• Accepting ordinary-strength Grade A/B certificates for a RA32 PO
• Accepting a AH32 certificate from another society (or a product-standard paper) where KR RA32 is specified
• Ignoring TMCP Ceq caps on TM plate
• Substituting a different letter (e.g. AH for AH) without drawing approval
• Coil-cut plate without coil approval
• Missing KR endorsement on the MTC
• Writing DNV NV A32 or LR/AH32 on a KR-class PO without arranging that society’s survey

Write the KR grade (RA32), delivery condition, impact temperature and certificate type into the PO.

Specify KR RA32 (KR RA32), 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 RA32 (KR RA32), delivery condition [AR/CR/N/TM/QT], 20 × 2500 × 12000 mm, 30 pcs, marked KR RA32, certificate endorsed by KR Surveyor, EN 10204 3.2 [if required], UT [if required], CIF [port].”

KR RA32 / KR RA32 is higher-strength hull steel under KR Rules for the Classification of Steel Ships, Pt 2 and IACS UR W11: yield 315 N/mm², tensile 440–590 N/mm², Charpy at 0 °C, marking KR RA32. AH32 is the cross-society name for the same IACS grade, but only the KR RA32 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 RA32 plate rolled by Chinese mills that hold Korean Register works approval for the grade, so every plate carries the KR RA32 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 RA32 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 RA32 / KR RA32), 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.