Replacing shipbuilding steel with an equivalent standard is an important solution, helping to ensure quality and optimize costs. Steel standards such as AH36, DH36, EH36 are popular choices due to their technical properties and high strength. However, in some cases, replacing equivalent steel is necessary. This article will help you better understand the alternative standards.
1. Overview of AH36, DH36, EH36 Steel
AH36, DH36, and EH36 steel are widely used in shipbuilding. They meet ASTM A131 standards and international classification requirements. “A” is tested at 0°C, “D” at -20°C, and “E” at -40°C. The number “36” represents a yield strength of 355 MPa. These technical properties ensure durability in harsh conditions.
2. Mechanical Properties of AH36, DH36, EH36 Steel
2.1 Yield Strength
All three types have a minimum yield strength of 355 MPa, ensuring strong structural integrity for ships. The maximum thickness is typically 100mm.
2.2 Tensile Strength
Tensile strength ranges from 490 to 620 MPa. AH36, DH36, and EH36 maintain stable strength, making them ideal for handling dynamic loads at sea.
2.3 Impact Toughness
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AH36 is tested at 0°C with a minimum impact energy of 34J (longitudinal).
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DH36 is tested at -20°C with a similar 34J rating.
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EH36 is tested at -40°C, achieving at least 34J. EH36 excels in low-temperature conditions.
3. Chemical Composition of AH36, DH36, EH36 Steel
3.1 Basic Composition
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Carbon content: max 0.18%
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Manganese: 0.90-1.60%
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Silicon: max 0.50%
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Phosphorus & Sulfur: max 0.035%
This composition ensures excellent weldability and durability.
3.2 Microalloying Elements
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EH36 contains Niobium and Vanadium for enhanced toughness.
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DH36 may include Aluminum for deoxidation.
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AH36 requires fewer microalloying elements.
4. Practical Applications of AH36, DH36, EH36 Steel
4.1 AH36 Steel
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Used in hulls and decks operating in warm seas.
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Performs well in temperatures above 0°C, suitable for tropical regions.
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Cost-effective with high efficiency.
4.2 DH36 Steel
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Applied in oil tankers in moderately cold environments.
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Can withstand -20°C, suitable for regions like Northern Europe.
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Balances toughness and cost.
4.3 EH36 Steel
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Used in icebreakers and offshore structures in polar regions.
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Operates safely at -40°C, such as in the Arctic.
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Superior toughness and load-bearing capacity.
5. Equivalent Alternative Steel for AH36, DH36, EH36
5.1 ASTM A516 Gr.70 Steel
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Yield strength: 260-485 MPa, with high tensile strength.
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Impact tested at -20°C, a potential substitute for DH36.
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Commonly used in pressure vessels and small ships.
5.2 S355 Steel (EN 10025)
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Yield strength: 355 MPa, equivalent to AH36 and DH36.
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Tested at -20°C, suitable for moderate cold conditions.
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Versatile for structural applications.
5.3 Grade E Steel (ABS/LR)
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A substitute for EH36 with impact toughness at -40°C.
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Meets 34J impact energy requirements for extreme cold regions.
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Fully compliant with classification society standards.
6. Comparison of AH36, DH36, EH36 and Alternative Choices
6.1 Technical Property Comparison Table
| Steel Type | Yield Strength (MPa) | Test Temperature (°C) | Impact Toughness (J) | Primary Application |
|---|---|---|---|---|
| AH36 | 355 | 0 | 34 | Warm sea regions |
| DH36 | 355 | -20 | 34 | Moderate cold areas |
| EH36 | 355 | -40 | 34 | Extreme cold zones |
| ASTM A516 Gr.70 | 260-485 | -20 | 27-34 | Pressure vessels, small ships |
| S355 (EN 10025) | 355 | -20 | 27-34 | Structural steel |
| Grade E (ABS/LR) | 355 | -40 | 34 | Extreme cold zones |
6.2 Analysis
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AH36, DH36, and EH36 are optimal for large ship structures.
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ASTM A516 Gr.70 suits smaller applications.
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S355 is versatile but less common in shipbuilding.
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Grade E is an effective substitute for EH36 in extreme conditions.
7. Key Highlights and Selection Criteria
7.1 Low-Temperature Performance
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EH36 and Grade E excel at -40°C.
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DH36 and S355 perform well at -20°C.
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AH36 is ideal for normal temperature operations.
7.2 Cost and Availability
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AH36 is more affordable and widely available.
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DH36 and EH36 are more expensive due to specialized properties.
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Alternatives like S355 offer cost savings.
7.3 Weldability
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All three grades have excellent weldability due to low carbon content.
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ASTM A516 and S355 also weld easily.
8. Considerations When Choosing Equivalent Steel
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Ensure compliance with international standards and technical specifications.
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Verify certification from classification bodies such as ABS, BV, DNV, LR.
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Consider operating conditions and practical application of substitute steel.
9. Conclusion
AH36, DH36, and EH36 shipbuilding steels meet diverse maritime conditions.
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AH36 is suitable for warm seas.
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DH36 works well in moderately cold climates.
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EH36 is ideal for extreme cold environments.
Equivalent options like S355 and Grade E offer flexibility. Choosing the right steel depends on technical properties and application requirements.
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