BV Grade D Shipbuilding Steel Coil
BV Grade D Shipbuilding Steel Coil – High Strength, Excellent Low-Temperature Toughness
BV Grade D is a normal-strength hull structural steel certified by Bureau Veritas for marine applications. It offers excellent weldability, good low-temperature impact toughness, and high reliability in ship structures.
Welding, Cutting, Forming, Bending, Straightening
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BV Grade D Shipbuilding Steel Coil Introduction
BV Grade D is a normal-strength shipbuilding steel grade classified according to the rules of Bureau Veritas (BV). It belongs to the standard hull structural steels defined by the International Association of Classification Societies (IACS) UR W11. The steel is designed for use in marine environments and is primarily used for hull plates, webs, stiffeners, and other ship structural components.
- Typical yield strength: ≥ 235 MPa
- Excellent notch toughness at -20°C
- Good weldability with conventional methods
- Supplied in normalized or thermo-mechanically controlled rolled (TMCP) condition
BV Grade D can be delivered as plate, coil, or sections, and is suitable for cold forming and welding.
BV Grade D Shipbuilding Steel Coil Chemical Composition
The chemical composition of BV Grade D complies with the IACS UR W11 requirements for Grade D steel. Key elements are controlled to ensure good toughness and weldability. Grain-refining elements such as aluminum are typically added. The analysis is performed on ladle samples.
| Element | Standard Value | Remarks |
|---|---|---|
| C | ≤ 0.21 | Carbon content; max 0.21% |
| Mn | ≥ 2.5 × C | Manganese provides strength; minimum 2.5 times carbon content |
| Si | ≤ 0.50 | Silicon as deoxidizer; typically 0.10–0.50% |
| P | ≤ 0.035 | Phosphorus as impurity |
| S | ≤ 0.035 | Sulfur as impurity |
| Al (acid soluble) | ≥ 0.015 | Fine grain practice; acid soluble aluminum minimum 0.015% |
| Nb | 0.02–0.05 | Optional microalloying for grain refinement (in TMCP conditions) |
| V | 0.05–0.10 | Optional microalloying (in TMCP conditions) |
| Ti | ≤ 0.02 | Optional microalloying |
BV Grade D Shipbuilding Steel Coil Thermal and Electrical Physical Properties
Physical properties are typical for carbon-manganese structural steels and are not specifically mandated by classification society rules. These values are provided for engineering reference and are based on literature for similar C-Mn steels at room temperature unless noted.
| Property | Typical Value | Unit | Test Conditions |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20 °C |
| Modulus of Elasticity (E) | 200 | GPa | At 20 °C |
| Shear Modulus (G) | 80 | GPa | At 20 °C |
| Poisson's Ratio (ν) | 0.3 | - | At 20 °C |
| Coefficient of Thermal Expansion (α) | 12.0 | 10⁻⁶/K | Between 20 °C and 100 °C |
| Coefficient of Thermal Expansion (α) | 12.5 | 10⁻⁶/K | Between 20 °C and 200 °C |
| Thermal Conductivity (λ) | 52 | W/(m·K) | At 20 °C |
| Specific Heat Capacity | 470 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρe) | 0.20 | μΩ·m | At 20 °C |
BV Grade D Shipbuilding Steel Coil Mechanical Properties
Mechanical properties of BV Grade D are in accordance with BV rules and IACS UR W11. Testing is performed on fully killed steel in the delivery condition (normalized or TMCP). The following values apply to thicknesses up to 50 mm unless otherwise noted.
| Property | Standard Value | Unit | Test Conditions |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 235 | MPa | Transverse specimens; ambient temperature |
| Tensile Strength (Rm) | 400 – 520 | MPa | Transverse specimens; ambient temperature |
| Elongation (A) | ≥ 22 | % | Gauge length 5.65√S₀; transverse (or longitudinal for thickness >50 mm) |
| Bend Test (Diameter) | 3a (thickness ≤25 mm) | - | 180° bend; no cracks or defects |
| Bend Test (Diameter) | 4a (thickness 25–50 mm) | - | 180° bend; no cracks or defects |
| Charpy V-Notch Impact Energy (KV₂) | ≥ 27 (average of 3 specimens) | J | Temperature: -20 °C; longitudinal specimens (transverse if agreed) |
| Charpy V-Notch Impact Energy (KV₂) | ≥ 20 (single specimen min.) | J | Temperature: -20 °C |
BV Grade D Shipbuilding Steel Coil Equivalent Standards and Replaceable Grades
The following standards and grades are recognized as fully equivalent to BV Grade D based on IACS UR W11 harmonization. These grades may be used as direct substitutes under the approval of the relevant classification society.
| Country/Region | Standard/Specification | Grade | Remarks |
|---|---|---|---|
| International (IACS) | IACS UR W11 | Grade D | Unified requirements for normal strength hull structural steel |
| China | GB 712 | D | Chinese standard for shipbuilding steel |
| USA | ASTM A131/A131M | Grade D | Standard specification for structural steel for ships |
| Japan | JIS G3106 | SM400B | For thickness ≤50 mm; welding structural steel (not all properties identical but accepted by BV by agreement) |
| Europe | EN 10025-2 | S235J2 | Comparable yield strength and impact temperature; must be verified for marine use |
| Korea | KS D 3515 | SM400B | Korean standard equivalent to JIS G3106 |
BV Grade D Shipbuilding Steel Coil Application Introduction
BV Grade D steel coil/plate is intended for primary load-bearing components in marine vessels and offshore units. Its combination of adequate strength, excellent weldability, and guaranteed notch toughness at -20 °C makes it suitable for hull structures operating in moderate cold environments. The steel can be formed, cut, and welded with standard shipyard procedures. Typical processing includes plasma cutting, beveling, press bending, and submerged arc welding. The guaranteed impact properties ensure resistance to brittle fracture under dynamic loading conditions.
Product Applications: Hull plates (shell, bottom, side), Weather deck plating, Bulkheads and transverse webs, Longitudinal stiffeners and frames, Rudder blades and stock bearings, Hatch coamings and covers, Foundations for deck equipment
Processed into products: Hull shell plates, Bottom and bilge plates, Deck stringer plates, Transverse and longitudinal web frames, Bulkhead plates, Floor plates in double bottom, Engine room structural members, Bracket plates
Application industries: Shipbuilding and ship repair, Offshore engineering (fixed platforms, FPSOs), Barge and pontoon construction, Marine structural components (docks, lock gates), Port infrastructure
BV Grade D Shipbuilding Steel Coil Similar and Alternative Materials with Comparable Performance
These grades are not classified as direct equivalents but offer similar strength levels and may be used as alternatives in shipbuilding when approved by the classification society. They may have different delivery conditions or slight compositional variations.
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International (BV) | BV Rules | BV Grade A | Normal strength but lower toughness (impact test at 0°C) |
| International (BV) | BV Rules | BV Grade E | Higher toughness (impact -40°C); used for thicker and more critical structures |
| International (ABS) | ABS Rules | Grade D | American Bureau of Shipping equivalent |
| International (DNV) | DNV Rules | NV D | DNV GL equivalent |
| International (LR) | Lloyd's Register Rules | LR Grade D | Lloyd's Register equivalent |
| Europe | EN 10025-3 | S275N/NL | Normalized fine-grain structural steel with higher strength |
| Europe | EN 10225 | S235G2 | Weldable structural steels for fixed offshore structures |
Notes:
- All mechanical property values refer to the minimum requirements as per BV Rules unless stated otherwise.
- For thicknesses above 50 mm, chemical composition and mechanical requirements may be subject to separate agreement.
- Weldability is ensured by low carbon equivalent (typically ≤0.40 for this grade) and controlled impurity levels.
- Hydrogen-induced cracking (HIC) resistance is not required unless specified for sour service applications.
- BV Grade D can be supplied with additional requirements such as through-thickness tensile testing (Z-quality) or CTOD testing by arrangement.
- Marking includes heat number, grade, and BV stamp in accordance with BV Rules.
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