ASTM A131 DH32 Shipbuilding Steel Coil
ASTM A131 DH32 Shipbuilding Steel Coil - High-Strength Hull Structural Steel
Explore ASTM A131 DH32 shipbuilding steel coil: a normalized or TMCP high-strength steel for marine hull structures. Chemical, mechanical, and physical properties, equivalent grades, and applications.
Hot rolling, Controlled rolling (TMCP), Normalizing, Cutting, Forming, Welding, Bending
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ASTM A131 DH32 Shipbuilding Steel Coil Introduction
ASTM A131 DH32 is a high-strength hull structural steel grade specified under ASTM A131/A131M Standard Specification for Structural Steel for Ships. The 'DH' designation indicates that the steel is suitable for low-temperature service with minimum Charpy V-notch impact energy of 34 J at -20°C. It is typically supplied as hot-rolled coils, plates, or cut lengths in normalized or thermo-mechanically controlled processed (TMCP) condition. The steel offers excellent weldability, high notch toughness, and good resistance to brittle fracture, making it suitable for critical structural parts of ships, barges, and marine equipment. Its fine-grained microstructure ensures consistent mechanical properties across a range of thicknesses, complying with major classification society rules.
ASTM A131 DH32 Shipbuilding Steel Coil Chemical Composition
Chemical requirements as per ASTM A131/A131M for DH32 grade. The analysis is limited to elements shown; fine grain practice elements (Al, Nb, V, Ti) may be used singly or in combination. Residual elements Cr, Ni, Mo, Cu are not specified but are usually kept low to maintain weldability.
| Element | Standard Value (max, unless range) | Remarks |
|---|---|---|
| Carbon (C) | 0.18% | max |
| Manganese (Mn) | 0.90 – 1.60% | Range |
| Silicon (Si) | 0.10 – 0.50% | Range |
| Phosphorus (P) | 0.035% | max |
| Sulfur (S) | 0.035% | max |
| Aluminum (Als) | 0.015% min (acid soluble) | Fine grain element |
| Niobium (Nb) | 0.02 – 0.05% | If used |
| Vanadium (V) | 0.05 – 0.10% | If used |
| Titanium (Ti) | 0.007 – 0.05% | If used |
| Copper (Cu) | 0.35% | Residual, max if not specified |
| Chromium (Cr) | 0.20% | Residual, max if not specified |
| Nickel (Ni) | 0.40% | Residual, max if not specified |
| Molybdenum (Mo) | 0.08% | Residual, max if not specified |
ASTM A131 DH32 Shipbuilding Steel Coil Thermal and Electrical Physical Properties
Typical physical properties for normalized fine-grained structural steel (similar to carbon-manganese steel). These values are not mandatory in ASTM A131 but are provided for engineering reference. They may vary slightly with composition and condition.
| Property | Typical Value | Unit | Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20°C |
| Elastic Modulus (E) | 205 | GPa | 20°C |
| Shear Modulus (G) | 80 | GPa | 20°C |
| Poisson's Ratio (ν) | 0.29 | — | 20°C |
| Thermal Expansion Coefficient (α) | 11.7 | 10⁻⁶/°C | 20–100°C |
| Thermal Expansion Coefficient (α) | 12.2 | 10⁻⁶/°C | 20–200°C |
| Thermal Expansion Coefficient (α) | 12.9 | 10⁻⁶/°C | 20–300°C |
| Thermal Conductivity (λ) | 51.9 | W/m·K | 20°C |
| Thermal Conductivity (λ) | 50.2 | W/m·K | 100°C |
| Thermal Conductivity (λ) | 47.6 | W/m·K | 200°C |
| Specific Heat Capacity | 486 | J/kg·K | 20°C |
| Electrical Resistivity (ρ_e) | 0.20 | µΩ·m | 20°C |
ASTM A131 DH32 Shipbuilding Steel Coil Mechanical Properties
Tensile and impact properties as required by ASTM A131/A131M for DH32 grade, thickness ≤ 100 mm. Charpy V-notch tests are performed at -20°C. The values in the table are minimum requirements unless otherwise noted. For thickness > 100 mm, properties shall be agreed between purchaser and manufacturer.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | min 315 | MPa | Thickness ≤ 50 mm |
| Yield Strength (ReH) | min 315 | MPa | Thickness 50–70 mm |
| Yield Strength (ReH) | min 315 | MPa | Thickness 70–100 mm |
| Tensile Strength (Rm) | 440 – 590 | MPa | All thicknesses |
| Elongation (A), 200 mm gauge | min 22 | % | Thickness ≤ 50 mm |
| Elongation (A), 200 mm gauge | min 21 | % | Thickness 50–70 mm |
| Elongation (A), 200 mm gauge | min 20 | % | Thickness 70–100 mm |
| Bend Test (180° bend, dia. of plunger) | d = 2a | — | Thickness ≤ 25 mm |
| Bend Test (180° bend, dia. of plunger) | d = 3a | — | Thickness > 25 mm |
| Charpy Impact (KV), longitudinal | 34 (average), 24 (single) | J | -20°C |
| Charpy Impact (KV), transverse | 34 (average), 24 (single) | J | -20°C |
ASTM A131 DH32 Shipbuilding Steel Coil Full Equivalent Material Standards and Replaceable Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | IACS Classification Societies | DH32 | ABS DH32, BV DH32, CCS DH32, DNV DH32, KR DH32, LR DH32, NK DH32, RINA DH32 |
| USA | ASTM A131/A131M | DH32 | Original standard |
| European Union | EN 10025-3 / EN 10025-4 | S355N / S355M (approx.) | Similar but with different delivery conditions; verify with class society |
| Japan | JIS G 3106 | SM400BWDS (approx.) | For low-temperature marine structures, need verification |
ASTM A131 DH32 Shipbuilding Steel Coil Application Introduction
ASTM A131 DH32 steel coil is primarily used in the marine and offshore industry, where high strength and low-temperature toughness are essential. It can be formed, welded, and machined into various structural components. Typical applications and products include:
Product Applications: Hull plates and stiffeners, Deck plates and girders, Watertight bulkheads, Bottom and side shell plates, Superstructure elements, Offshore wind turbine foundation structures
Processed into products: Longitudinal and transverse frames, Keelsons and stringers, Brackets and gussets, Reinforcing ribs, Cut-outs and collars, Connection plates
Application industries: Shipbuilding, Offshore Oil & Gas Platforms, Marine Engineering, Barge and Tugboat Construction, Port and Harbor Equipment
ASTM A131 DH32 Shipbuilding Steel Coil Similar / Nearby Substitute Materials
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A131/A131M | AH32 | Lower toughness (0°C impact); same strength. Used where low-temperature requirement is less strict. |
| USA | ASTM A131/A131M | EH32 | Higher toughness (-40°C impact); same strength. Suitable for colder environments. |
| USA | ASTM A131/A131M | FH32 | Highest toughness (-60°C impact); same strength. For severe low-temperature applications. |
| China | GB/T 712 | DH32 | Similar chemical and mechanical properties, may differ slightly in residual element limits. |
Notes:
The purchaser should specify delivery condition (N, TMCP) and any supplementary requirements. When ordering to classification society rules, the material must also comply with the respective society's rules. For thicknesses beyond the standard range or for specific product forms (e.g., wide coils, cut-to-length plates), additional testing or agreement may be required. The typical physical properties listed are generic for carbon-manganese structural steel and should be confirmed by specific mill certificates if critical.
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