Understanding the Differences Between AH36, DH36, and EH36 Grades

Steel Grade	Yield Strength (MPa)	Tensile Strength (MPa)	Impact Test Temperature	Typical Application
AH36	355	490–620	0°C	General ship hulls and deck structures
DH36	355	490–620	-20°C	Offshore platforms, cold seawater exposure
EH36	355	490–620	-40°C	Arctic and cryogenic marine environments

All three have the same mechanical strength, but their impact energy absorption capability at different temperatures defines their classification and use.

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Chemical Composition

The chemical composition of AH36, DH36, and EH36 is virtually identical, designed to ensure high strength, good weldability, and corrosion resistance.

Typical Chemical Composition (%):

• Carbon (C): ≤ 0.18

• Manganese (Mn): 0.90–1.60

• Silicon (Si): 0.10–0.50

• Phosphorus (P): ≤ 0.035

• Sulfur (S): ≤ 0.035

• Niobium (Nb), Vanadium (V), Titanium (Ti): ≤ 0.10

Micro-alloying elements such as niobium, vanadium, and titanium refine the grain structure, which enhances the steel’s toughness, fatigue resistance, and mechanical strength.

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Mechanical Properties

AH36, DH36, and EH36 are all high-strength steels with the same minimum yield strength of 355 MPa and tensile strength ranging from 490 to 620 MPa.

Typical Mechanical Properties:

• Yield Strength: ≥ 355 MPa

• Tensile Strength: 490–620 MPa

• Elongation (in 50 mm): ≥ 21%

• Hardness (HB): 170–220

The key distinction among them lies in impact toughness, measured through Charpy V-Notch (CVN) tests at different temperatures:

• AH36 is tested at 0°C.

• DH36 is tested at -20°C.

• EH36 is tested at -40°C.

The lower the test temperature, the greater the steel’s ability to retain toughness and prevent brittle fracture in cold environments.

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Key Differences Between AH36, DH36, and EH36

1. Impact Toughness

The most critical distinction among the three grades is their resistance to brittle fracture at different temperatures.

• AH36 performs reliably in moderate climates, suitable for vessels operating in standard sea conditions.

• DH36 provides improved toughness, making it suitable for colder regions and offshore platforms.

• EH36 delivers exceptional impact strength at sub-zero temperatures, ideal for Arctic shipping, LNG carriers, and polar vessels.

This difference ensures each grade is used where it can provide maximum safety under environmental stress.

2. Service Temperature Range

• AH36: For use in temperate to warm climates (above 0°C).

• DH36: For cold-weather conditions (down to -20°C).

• EH36: For extreme cold environments (down to -40°C).

Ships or offshore structures operating in freezing or polar conditions rely on EH36 to prevent structural cracking due to temperature-induced brittleness.

3. Application Environment

While all grades are marine steels, their deployment differs based on environmental exposure:

• AH36: General-purpose hulls, cargo ships, and bulk carriers.

• DH36: Offshore drilling platforms, ocean-going tankers, and vessels in cold-water routes.

• EH36: Icebreakers, polar research vessels, and deep-sea platforms.

4. Testing and Certification

Each grade must pass strict testing standards defined by ABS (American Bureau of Shipping) and other classification societies. The difference in impact testing temperature ensures that each steel grade performs safely in its intended environment.

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Common Features of AH36, DH36, and EH36

Although their impact test requirements differ, the three grades share several key properties that make them universally valued in marine construction.

1. High Strength-to-Weight Ratio

Their superior strength allows for the construction of lighter, stronger ship structures, reducing material usage and fuel consumption, which improves overall energy efficiency.

2. Excellent Weldability

Thanks to controlled carbon content and alloy design, these steels are highly weldable using standard welding processes such as MIG, TIG, and submerged arc welding (SAW) without preheating or post-heat treatment.

3. Resistance to Corrosion and Fatigue

Designed for continuous exposure to saltwater, moisture, and cyclic stress, AH36, DH36, and EH36 offer excellent resistance to corrosion, oxidation, and fatigue failure.

4. Long-Term Durability

Even under constant vibration, impact, and wave pressure, these grades maintain their structural integrity for decades, making them ideal for ship hulls, decks, and offshore installations.

5. Compliance with International Standards

All three grades conform to the specifications of major classification societies:

• ABS (American Bureau of Shipping)

• Lloyd’s Register (LR)

• Det Norske Veritas (DNV)

• Bureau Veritas (BV)

• China Classification Society (CCS)

Each plate supplied by sakysteel is fully traceable, with EN 10204 3.1/3.2 Mill Test Certificates ensuring complete quality assurance.

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Applications in the Marine and Offshore Industry

1. Shipbuilding

AH36, DH36, and EH36 are extensively used in hull construction, deck plating, and bulkheads, ensuring vessels remain stable and safe in heavy seas.

2. Offshore Platforms

In offshore drilling rigs and floating production systems, DH36 and EH36 steels are used for main decks, support legs, and structural beams, where exposure to cold seawater and high stress demands superior toughness.

3. LNG Carriers and Cryogenic Vessels

EH36 steel is particularly suited for cryogenic applications, maintaining excellent ductility even at sub-zero temperatures, which is crucial for storing and transporting liquefied gases.

4. Naval and Military Vessels

Due to their high strength and impact resistance, these steels are ideal for frigates, patrol boats, and defense vessels, providing durability and structural reliability under dynamic loading.

5. Offshore Wind Turbines

As the renewable energy industry expands offshore, AH36 and DH36 steels are increasingly used in foundation structures, support towers, and underwater platforms, where corrosion and fatigue resistance are critical.

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Processing and Fabrication Characteristics

1. Hot Rolling and TMCP (Thermo-Mechanical Controlled Processing):
   All three grades are produced using TMCP technology, which refines grain size and enhances both strength and toughness.

2. Cutting and Forming:
   The steels offer excellent machinability, allowing plasma, laser, or oxy-fuel cutting without edge cracking or distortion.

3. Welding:
   Weldability is excellent for all grades due to low carbon equivalent values, minimizing the risk of hydrogen cracking during fabrication.

4. Surface Condition:
   Plates are available in shot-blasted, primed, or coated finishes for added corrosion resistance during shipping and storage.

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Testing and Certification

Every plate supplied by sakysteel undergoes strict quality testing to ensure compliance with marine standards:

• Tensile and Yield Strength Tests

• Charpy V-Notch Impact Tests at specified temperatures

• Ultrasonic Testing (UT) for internal flaws

• Dimensional and Surface Inspection

• Spectrometer Analysis for chemical accuracy

All test results are documented in Mill Test Certificates (EN 10204 3.1/3.2) and approved by recognized classification societies.

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Why Choose sakysteel for Marine Steel Solutions

sakysteel is a globally recognized supplier of shipbuilding and offshore steels, offering a complete range of AH36, DH36, and EH36 plates that meet all major classification society standards.

Our Advantages Include:

• Full size range: thickness 5–150 mm, width up to 3,500 mm, length up to 12,000 mm

• Certifications from ABS, LR, DNV, BV, and CCS

• Fast delivery and global shipping solutions

• Customized cutting, beveling, and surface treatments

• Third-party inspection services available (SGS, TUV, BV)

By choosing sakysteel, clients benefit from top-quality materials backed by decades of expertise, ensuring superior performance and cost-effectiveness in every marine project.

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Future Outlook: High-Strength Steels in Modern Shipbuilding

As the maritime industry continues to evolve, the demand for lighter, stronger, and more energy-efficient vessels is rapidly increasing. High-strength steels such as AH36, DH36, and EH36 are at the forefront of this transformation.

Their combination of strength, toughness, and weldability supports the development of next-generation ships, offshore platforms, and renewable marine structures. Emerging technologies like TMCP, laser welding, and corrosion-resistant coatings will continue to enhance their performance, ensuring longer service life and reduced maintenance in future marine environments.

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Conclusion

While AH36, DH36, and EH36 share similar compositions and strength levels, their impact toughness and service temperature capabilities set them apart. AH36 is ideal for standard marine environments, DH36 for colder regions, and EH36 for extreme Arctic and cryogenic conditions.

These high-performance steels combine mechanical strength, corrosion resistance, and excellent weldability, making them indispensable in modern shipbuilding and offshore engineering.

Backed by international certifications and advanced manufacturing expertise, sakysteel delivers AH36, DH36, and EH36 shipbuilding steel plates that ensure safety, durability, and reliability for every maritime application. As the global demand for sustainable and efficient ships grows, these grades will continue to form the foundation of strong, future-ready marine structures.