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ABS Grade AH36, DH36, EH36, FH36 Shipbuilding Steel Differences
- John
When choosing the right steel for shipbuilding, it’s important to consider both the environmental conditions and the specific vessel requirements. AH36 is suitable for general-purpose ships such as bulk carriers, container ships, and tankers operating in mild climates. DH36 is tougher and works best for offshore vessels and ships in colder regions. EH36 offers superior strength and low-temperature performance, making it ideal for large tankers, offshore platforms, and ships operating in harsh marine environments. FH36, the strongest and most resilient of the four, is designed for icebreakers and Arctic-class vessels working in extreme cold.
To truly grasp the differences between ABS Grade AH36, DH36, EH36, and FH36, it’s important to explore their composition, mechanical properties, processing methods and uses. This article will provide a detailed comparison of these aspects.
ABS Grade: AH36 | DH36 | EH36 | FH36
AH36, DH36, EH36, and FH36 are structural carbon steels specifically designed for shipbuilding and marine structures. These grades are commonly used in critical components such as decks, keels, bulkheads, and other vital parts of offshore platforms. These steels are governed by international standards ASTM A131 and ISO 636.
American Bureau of Shipping (ABS) classifies these materials based on their strength and toughness. Other grades under the ABS classification include A, B, C, D, and E, as well as AH32, DH32, EH32, and higher-strength variants like AH40, DH40, and EH40.
Overview Of Differences Of AH36, DH36, EH36, FH36
Here is a comparison table for AH36, DH36, EH36, and FH36 based on key attributes:
| Grade | Tensile Strength | Charpy Impact Strength | CVN Temperature | Common Applications |
| AH36 | 490-620 MPa | ≥ 27 J | Ambient to 0°C | General-purpose ships (cargo, bulk, container) in mild climates. |
| DH36 | 490-620 MPa | ≥ 27 J | -20°C or lower | Offshore vessels, and ships in cold regions for moderate climates. |
| EH36 | 510-690 MPa | ≥ 27 J | -40°C or lower | Large tankers, offshore platforms in high-latitude regions |
| FH36 | 510-690 MPa | ≥ 27 J | -60°C or lower | Icebreakers, Arctic vessels, offshore platforms in extreme cold |
- These minimum impact strength values are for material thicknesses up to 50 mm. For thicker sections (such as parts of the hull), the required toughness might be different.
- The Charpy impact test is performed in the longitudinal direction.
Chemical Composition Of AH36, DH36, EH36, FH36
Here is a table comparing the key differences in the chemical composition of AH36, DH36, EH36, and FH36 shipbuilding steel.
| Element | C | Mn | Si | Ni | Cr | CEV |
| AH36 | ≤ 0.18% | 0.90% – 1.60% | 0.15% – 0.35% | ≤ 0.40% | ≤ 0.15% | ≤0.40% |
| DH36 | ≤ 0.18% | 1.00% – 1.70% | 0.15% – 0.40% | 0.40% – 0.50% | ≤ 0.20% | ≤0.40% |
| EH36 | ≤ 0.20% | 1.00% – 1.70% | 0.15% – 0.50% | 0.40% – 0.50% | 0.15% – 0.25% | ≤0.40% |
| FH36 | ≤ 0.20% | 1.00% – 1.70% | 0.15% – 0.50% | ≤ 0.50% | 0.15% – 0.30% | ≤0.40% |
- The carbon equivalent calculation formula: CEV = C + (Mn / 6) + ((Cr + Mo + V) / 5) + ((Ni + Cu) / 15).
Mechanical Properties Of AH36, DH36, EH36, FH36
This table shows their mechanical properties based on the air-cooled (AC) state.
| Property | AH36 | DH36 | EH36 | FH36 |
| Yield Strength (min) | 355 MPa (51.5 ksi) | 355 MPa(51.5 ksi) | 355 MPa (51.5 ksi) | 355 MPa (51.5 ksi) |
| Tensile Strength (min) | 490 – 620 MPa (74–96 ksi) | 490 – 620 MPa (71 – 90 ksi) | 510 – 660 MPa (74 – 96 ksi) | 510 – 660 MPa (74 – 96 ksi) |
| Elongation (min) | 20% in 200 mm (8 in) | 20% in 200 mm (8 in) | 20% in 200 mm (8 in) | 20% in 200 mm (8 in) |
| Charpy V-Notch Impact | ≥ 27 J at 0°C | ≥ 47 J at -20°C | ≥ 47 J at -40°C | ≥ 47 J at -60°C |
Prossesing Of AH36, DH36, EH36, FH36
AH36 and DH36
Processing Type: Air Cooled (AC)
For standard shipbuilding applications, these steels are typically rolled and air-cooled after rolling. They do not undergo additional heat treatments unless specifically requested for certain applications.
EH36
Processing Type: Air Cooled (AC) or Quenched & Tempered (QT).
EH36 steels are more often processed in the QT state for use in offshore platforms and heavy-duty vessels. The tempering process increases both the strength and toughness, making the steel more resistant to cracks or failure under stress.
FH36
Processing Type: Quenched & Tempered (QT).
FH36 is almost always delivered in the QT state. This is critical to improve the steel’s ability to handle extremely low temperatures and high stress, essential for vessels operating in polar or Arctic regions.
Applications Of AH36, DH36, EH36, FH36
AH36, DH36, EH36, and FH36 offer varying mechanical properties, making each grade suitable for specific applications in the maritime industry
| Grade | Applications | Environments |
| AH36 | Bulk carriers, container ships, tankers, general cargo ships | Mild to temperate maritime climates |
| DH36 | Oil tankers, offshore supply vessels, docks, offshore platforms | Moderate to high-stress marine environments, temperate regions |
| EH36 | Offshore drilling rigs, offshore platforms, FPSOs, cold-weather vessels | Cold-weather operations, severe marine environments, high-stress conditions |
| FH36 | Icebreakers, Arctic-class vessels, oil rigs, platforms, deep-sea exploration vessels | Arctic/polar environments, harsh weather, high-impact conditions |
If you’d like to see how our shipbuilding steels have been used in real projects, check out our Key Study examples. Just send us an email, and we’ll be happy to share more details with you!
Product Dimensions Of AH36, DH36, EH36, FH36 Steel Plate
AH36, DH36, EH36, and FH36 plates are the most common products form. Shipbuilders and marine construction companies purchase hot-rolled steel plates that can be cut and welded into different shapes for various parts of a vessel or offshore structure. Here are the standard ranges of their dimensions：
- Thickness: ≥1.5mm (0.059 in)
- Width: 1500 mm to 4000 mm (59.06 in to 157.48 in)
- Length: 6000 mm to 12000 mm (236.22 in to 472.44 in)
High-Quality Shipbuilding Steel Plates for Your Projects
SteelPro Group offers AH36, DH36, EH36, and FH36 shipbuilding steel plates that meet ASTM A131 standards. Our products are certified by international classification societies including:
- American Bureau of Shipping (ABS)
- Lloyd’s Register (LR)
- China Classification Society (CCS)
- Korean Register (KR)
- ClassNK (Japan)
We also provide services such as shot blasting, sandblasting, painting, coating, and more custom options. Contact us today to discuss how we can support your project needs!
