ASTM A131 Grade B Shipbuilding Steel Coil
ASTM A131 Grade B Shipbuilding Steel Coil - Properties & Equivalents
Comprehensive material data for ASTM A131 Grade B shipbuilding steel coil: chemical composition, mechanical and thermal properties, international equivalents, and application guidance.
Hot rolling, controlled rolling, normalizing, TMCP, welding, forming, machining
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ASTM A131 Grade B Shipbuilding Steel Coil Introduction
ASTM A131 Grade B is a hot-rolled structural steel for shipbuilding, specified under ASTM A131/A131M standard. It belongs to ordinary-strength hull structural steel category with a minimum yield strength of 235 MPa (34 ksi). This grade offers good weldability, toughness at 0°C, and is suitable for offshore and marine construction.
- Key Features: Good combination of strength and ductility, reliable impact properties at low temperatures, and excellent weldability.
- Delivery Conditions: Normalized, controlled rolled, or as-rolled; supplied as coils, plates, or sheets.
ASTM A131 Grade B Shipbuilding Steel Coil Chemical Composition
The chemical composition of ASTM A131 Grade B is governed by ASTM A131/A131M. Carbon content is restrained to ensure weldability. Manganese acts as a strengthener and deoxidizer. Phosphorus and sulfur are kept low to guarantee toughness and avoid hot shortness. Note: If the steel is to be supplied with impact properties, the carbon equivalent (CE) may be limited to ≤0.38% by agreement.
| Element | Value (max, %) | Remarks |
|---|---|---|
| C | 0.21 | Heat Analysis |
| Mn | 0.80 – 1.10 | If specified, minimum 0.80, maximum 1.10 for Grade B |
| P | 0.035 | Max |
| S | 0.035 | Max |
| Si | 0.35 | Max (may be 0.10–0.35 if Al killed) |
| Cu | 0.35 | Max (if copper-bearing steel is required) |
| Cr | 0.25 | Max (residual) |
| Ni | 0.25 | Max (residual) |
| Mo | 0.08 | Max (residual) |
| Ceq | ≤0.38 | Carbon Equivalent, by agreement when impact properties specified |
ASTM A131 Grade B Shipbuilding Steel Coil Thermal and Electrical Physical Properties
Typical physical properties for ASTM A131 Grade B carbon steel at room temperature. These values are for general guidance and may vary slightly with actual chemical composition and heat treatment. Key points: Density is 7.85 g/cm³; modulus of elasticity is approximately 205 GPa; thermal conductivity decreases with increasing temperature; coefficient of thermal expansion is about 12 µm/m·°C.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density, ρ | 7.85 | g/cm³ | 20°C |
| Elastic Modulus, E | 205 | GPa | Room temperature |
| Shear Modulus, G | 80 | GPa | Room temperature |
| Poisson's Ratio, ν | 0.30 | – | Room temperature |
| Thermal Expansion Coeff., α (20–100°C) | 12.0 | 10⁻⁶/K | 20–100°C |
| Thermal Expansion Coeff., α (20–200°C) | 12.5 | 10⁻⁶/K | 20–200°C |
| Thermal Conductivity, λ | 51.9 | W/m·K | 20°C |
| Specific Heat Capacity, cp | 486 | J/kg·K | 20°C |
| Electrical Resistivity, ρe | 0.16 | µΩ·m | 20°C |
ASTM A131 Grade B Shipbuilding Steel Coil Mechanical Properties
Tensile and impact properties are determined as per ASTM A370. The yield strength and tensile strength values apply to as-rolled or normalized condition. Elongation varies with thickness. Impact test is often required for Grade B: minimum 27 J at 0°C (longitudinal) for thicknesses up to 50 mm; transverse values are 20 J at 0°C. Bend test: 180° bending over diameter as specified without cracking.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength, ReH | ≥235 | MPa | t ≤ 50 mm; for t>50–100 mm min 225 MPa |
| Tensile Strength, Rm | 400 – 490 | MPa | t ≤ 50 mm; for t>50–100 mm 400-490 MPa |
| Elongation, A (200 mm) | ≥22 | % | t ≤ 50 mm (8 in. gauge) – longitudinal |
| Elongation, A (50 mm) | ≥26 | % | t ≤ 50 mm (2 in. gauge) – longitudinal |
| Impact Energy, KV (long.) | ≥27 (avg.) / ≥20 (single) | J | 0°C; specimen 10×10 mm |
| Impact Energy, KV (trans.) | ≥20 (avg.) / ≥16 (single) | J | 0°C; specimen 10×10 mm |
| Bend Test (180°) | No cracks | – | Bend diameter: 1.5t (t≤25mm); 2t (25 |
ASTM A131 Grade B Shipbuilding Steel Coil Direct International Equivalent Standards & Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | ABS Rules | Grade B | American Bureau of Shipping |
| Norway/Germany | DNV Rules | NV B | Det Norske Veritas |
| France | BV Rules | Grade B | Bureau Veritas |
| UK | LR Rules | Grade B | Lloyd's Register |
| Germany | GL Rules | Grade B | Germanischer Lloyd |
| China | CCS Rules | B | China Classification Society |
| Japan | NK Rules | B | Nippon Kaiji Kyokai |
| Korea | KR Rules | B | Korean Register |
| Italy | RINA Rules | B | Registro Italiano Navale |
| Russia | RS Rules | B | Russian Maritime Register |
ASTM A131 Grade B Shipbuilding Steel Coil Application Introduction
ASTM A131 Grade B steel is widely used in marine and structural applications due to its balanced strength, weldability, and toughness. It can be processed into plates, coils, sections, and welded fabrications.
- Processing note: Preheating may be required for thicker sections (>30 mm) during welding to avoid hydrogen cracking.
- Can be used in temperatures down to 0°C for structural integrity.
Product Applications: Ship hulls and decks, Bulkheads and superstructures, Offshore platform modules, Cranes and lifting equipment, Storage tanks and silos, Structural frames and girders
Processed into products: Welded beams and columns, Stiffeners and frames, Plates for shell and web frames, Cut and bent parts for ship assembly, Piping support structures, Machinery bases and support structures
Application industries: Shipbuilding and offshore engineering, Marine construction (barges, docks), Bridge and structural engineering, Pressure vessel components (limited to non-critical parts), Industrial machinery and equipment
ASTM A131 Grade B Shipbuilding Steel Coil Similar/Comparable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| USA | ASTM A131 | Grade A | Lower strength, C≤0.23, yield 235 MPa but no mandatory impact |
| USA | ASTM A131 | Grade D | Higher toughness, impact at -20°C, similar strength |
| USA | ASTM A36 | A36 | Structural quality, yield 250 MPa, but not ship class certified |
| Europe | EN 10025-2 | S235JR / S235J0 | Yield 235 MPa, similar carbon content, for general structural use |
| Japan | JIS G 3106 | SM400A/B | 250 MPa class, for welded structures; B has impact at 0°C |
| China | GB/T 712 | B | Chinese shipbuilding steel grade B, equivalent to A131 B |
Notes:
- ASTM A131 Grade B can be supplied with ultrasonic testing (UT) as per ASTM A578 or A435 for lamellar tearing resistance.
- Mill test certificates (EN 10204 3.1 or 3.2) are usually provided showing chemical and mechanical test results.
- Coils are often supplied with pickled and oiled surface, or hot-rolled black. Thickness tolerance per ASTM A6/A6M.
- For sub-zero service, Grade D or E should be considered instead of Grade B.
- The data contained herein are typical values based on the standard; actual properties may vary depending on the production process and specific mill practice.
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