Letter and number
The letter (A, B, D, E, F) sets the impact test temperature, the number (32, 36, 40) the strength: AH36 is 355 N/mm² tested at 0 °C.
Reference tool — not a test
Read the steel grade before it goes in an RFQ.
Hull structural steel
Grade, strength, impact.
Type the steel marking. Below the examples, the grade of an offered replacement can be checked against it: yield strength and impact test temperature. The drawing and the RFQ line update with every change.
Examples:
Replacement check
On the grade names alone: the class society, the mill certificate and the approved drawings decide.
All 130 engineering tools
Hull steel is marked with an IACS UR W11 grade and the class society’s stamp: the letter sets the impact test temperature, the number the strength level. Type the marking from the plate or the certificate, and the reader gives the yield and tensile strength, the elongation, the impact test temperature and the impact energy for the thickness, and writes the RFQ line.
The figures are the minimum requirements of IACS UR W11, not the properties of a given plate; the certificate with the heat number confirms those.
How a grade is read
Letter, number, stamp.
Normal strength
A, B, D and E share 235 N/mm² yield and 400 to 520 tensile; only the test temperature differs, from +20 to -40 °C.
Class stamp
LR, ABS, DNV, BV and the other societies stamp the grade they certify; the certificate carries the heat number on the plate.
| Grade | Yield, N/mm² | Tensile, N/mm² | Elongation, % | Test, °C | Impact up to 50 mm, J (long / trans) |
|---|---|---|---|---|---|
| A | 235 | 400–520 | 22 | +20 | — (t > 50) |
| B | 235 | 400–520 | 22 | 0 | 27 / 20 |
| D | 235 | 400–520 | 22 | -20 | 27 / 20 |
| E | 235 | 400–520 | 22 | -40 | 27 / 20 |
| AH32 | 315 | 440–570 | 22 | 0 | 31 / 22 |
| DH32 | 315 | 440–570 | 22 | -20 | 31 / 22 |
| EH32 | 315 | 440–570 | 22 | -40 | 31 / 22 |
| FH32 | 315 | 440–570 | 22 | -60 | 31 / 22 |
| AH36 | 355 | 490–630 | 21 | 0 | 34 / 24 |
| DH36 | 355 | 490–630 | 21 | -20 | 34 / 24 |
| EH36 | 355 | 490–630 | 21 | -40 | 34 / 24 |
| FH36 | 355 | 490–630 | 21 | -60 | 34 / 24 |
| AH40 | 390 | 510–660 | 20 | 0 | 39 / 26 |
| DH40 | 390 | 510–660 | 20 | -20 | 39 / 26 |
| EH40 | 390 | 510–660 | 20 | -40 | 39 / 26 |
| FH40 | 390 | 510–660 | 20 | -60 | 39 / 26 |
Per IACS UR W11, Tables 6 and 7. Over 50 and over 70 mm the impact energy is higher; grade B up to 25 mm is generally not impact tested. IACS writes the higher strength grades without H: A36, D36, E36, F36.
Sources
IACS Unified Requirement W11 "Normal and higher strength hull structural steels" (Rev.8 2014, as published by Türk Loydu), Tables 6 and 7: the grades, yield, tensile strength, elongation, test temperature and average impact energy by thickness, and the notes on grades A and B. The market names with H and the strength levels per Sakysteel, Total Materia and ArcelorMittal’s catalogue, which agree with the IACS tables.
Before you send the grade
Questions about hull steel in an RFQ
What does AH36 mean?
A higher strength hull steel to IACS UR W11: 36 is the strength level, 355 N/mm² minimum yield; A is the impact test temperature, 0 °C. DH36 is tested at -20 °C, EH36 at -40 °C and FH36 at -60 °C; IACS writes them A36, D36, E36 and F36.
What is the difference between grades A, B, D and E?
They are normal strength steels with the same strength, 235 N/mm² minimum yield and 400 to 520 N/mm² tensile; they differ in the impact test temperature: +20 °C for A (over 50 mm only), 0 °C for B, -20 °C for D and -40 °C for E.
Is A36 the same as AH36?
Not necessarily. IACS writes the 355 N/mm² grade as A36 and the market as AH36, but ASTM A36 is a different, US structural steel with a 36 ksi (250 MPa) yield. Check the certificate and the class stamp.
What does the impact energy depend on?
On the grade and the thickness. For AH36 the average is 34 J longitudinal and 24 J transverse up to 50 mm, 41 and 27 J up to 70 mm, and 50 and 34 J up to 100 mm (IACS UR W11, Table 7).
What should the request include?
The grade and the class society, the thickness and the plate size, the quantity and the certificate needed — the class society’s, or EN 10204 3.1 or 3.2. Photograph the stencil and the heat number of the old plate where one is to be matched.
Grade read?
Send the line with the photographs.
A decoded marking is a cross-check, not proof. Attach photographs of the stencil and the certificate, and Vessel Core checks them against each other before an offer goes back.
Buyer tools
