BV A620 Shipbuilding Steel Coil
BV A620 Shipbuilding Steel Coil - High Strength Marine Structural Steel with 620 MPa Yield
Explore BV A620 shipbuilding steel coil: 620 MPa minimum yield strength, exceptional weldability and toughness for harsh marine environments. Complies with Bureau Veritas rules, available in AH620, DH620, EH620, FH620 grades.
Available processes include hot rolling, controlled rolling, TMCP, normalizing, quenching and tempering; suitable for welding, forming, machining.
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BV A620 Shipbuilding Steel Coil Introduction
BV A620 is a high-strength shipbuilding structural steel grade approved by Bureau Veritas (BV) with a minimum yield strength of 620 MPa. It is designed for critical structural components in shipbuilding and offshore engineering, offering excellent weldability, formability, and low-temperature toughness. The steel is produced under strict control of chemical composition and thermo-mechanical processing to achieve required mechanical properties. Sub-grades (AH620, DH620, EH620, FH620) indicate different impact test temperatures and toughness levels. Typical delivery condition is thermo-mechanical controlled processing (TMCP) or quenching and tempering (Q&T). Its high strength-to-weight ratio enables design of lighter structures with improved payload and fuel efficiency.
BV A620 Shipbuilding Steel Coil Chemical Composition
Chemical composition limits for BV A620 grade according to IACS UR W11 and BV Rules. The composition is designed to achieve strength and toughness while maintaining good weldability.
- Carbon equivalent (CEV) is controlled to prevent cold cracking.
- Microalloying elements (Nb, V, Ti) ensure grain refinement.
- Low sulfur and phosphorus levels improve toughness.
| Element | Standard Value | Remarks |
|---|---|---|
| C | ≤ 0.20 | Ladle analysis |
| Si | ≤ 0.55 | Ladle analysis |
| Mn | ≤ 1.70 | Ladle analysis |
| P | ≤ 0.025 | Ladle analysis |
| S | ≤ 0.025 | Ladle analysis |
| Nb | ≤ 0.05 | May be added as grain refiner |
| V | ≤ 0.10 | May be added |
| Ti | ≤ 0.05 | May be added |
| Al (total) | ≥ 0.015 | Or sufficient other grain-refining elements |
| N | ≤ 0.012 | If not bound by Al or other elements |
| Nb+V+Ti | ≤ 0.12 | Sum if used in combination |
| Mo | ≤ 0.08 | May be present |
| Cu | ≤ 0.30 | May be present |
| Ni | ≤ 0.80 | May be present |
| Cr | ≤ 0.25 | May be present |
| Ceq (IIW) | ≤ 0.55 (typical) | Dependent on thickness and grade |
BV A620 Shipbuilding Steel Coil Thermal and Electrical Physical Properties
Physical properties for BV A620 steel at room temperature unless stated. These are typical values and may vary slightly with processing. Density is standard for steel; thermal expansion and conductivity are important for fabrication and fire design.
| Property | Standard Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20 °C |
| Modulus of Elasticity (E) | 205 | GPa | 20 °C, static |
| Shear Modulus (G) | 80 | GPa | typical |
| Poisson's Ratio (ν) | 0.3 | – | elastic range |
| Thermal Expansion Coefficient (α) | 12.0 | 10⁻⁶/K | 20 – 100 °C |
| Thermal Expansion Coefficient (α) | 12.5 | 10⁻⁶/K | 20 – 200 °C |
| Thermal Expansion Coefficient (α) | 13.3 | 10⁻⁶/K | 20 – 400 °C |
| Thermal Conductivity (λ) | 45 | W/(m·K) | 20 °C |
| Specific Heat Capacity (cp) | 460 | J/(kg·K) | 20 °C |
| Electrical Resistivity (ρ_e) | 0.25 | μΩ·m | 20 °C, typical low-alloy steel |
BV A620 Shipbuilding Steel Coil Mechanical Properties
Mechanical properties for BV A620 (AH620/DH620/EH620/FH620) according to BV Rules and IACS UR W11. Values depend on product thickness and sub-grade. Impact test requirements differ by sub-grade temperature.
- Transverse properties may be agreed.
- Thickness direction (Z-grade) properties available on request.
| Property | Standard Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 620 | MPa | t ≤ 100 mm, transverse |
| Tensile Strength (Rm) | 720 – 890 | MPa | t ≤ 100 mm, transverse |
| Elongation (A5) | ≥ 14 | % | t ≤ 100 mm, gauge length 5.65√So |
| Charpy V-notch Impact (KV) – AH620 | ≥ 34 (longitudinal) | J | 0 °C |
| Charpy V-notch Impact (KV) – AH620 | ≥ 24 (transverse) | J | 0 °C |
| Charpy V-notch Impact (KV) – DH620 | ≥ 34 (longitudinal) | J | -20 °C |
| Charpy V-notch Impact (KV) – DH620 | ≥ 24 (transverse) | J | -20 °C |
| Charpy V-notch Impact (KV) – EH620 | ≥ 34 (longitudinal) | J | -40 °C |
| Charpy V-notch Impact (KV) – EH620 | ≥ 24 (transverse) | J | -40 °C |
| Charpy V-notch Impact (KV) – FH620 | ≥ 34 (longitudinal) | J | -60 °C |
| Charpy V-notch Impact (KV) – FH620 | ≥ 24 (transverse) | J | -60 °C |
| Bend Test (diameter d) | 180° bend, d = 3a | – | a = specimen thickness |
BV A620 Shipbuilding Steel Coil Full Equivalent Material Standards and Substitutable Grade Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | IACS UR W11 | AH620, DH620, EH620, FH620 | Unified requirement for all IACS members |
| USA | ABS Rules | ABS AH620, DH620, EH620, FH620 | Equivalent grades |
| Norway/Germany | DNV Rules | NV A620, NV D620, NV E620, NV F620 | Branded as "NV" grades |
| UK | Lloyd's Register Rules | LR AH620, DH620, EH620, FH620 | Equivalent grades |
| China | CCS Rules | CCS AH620, DH620, EH620, FH620 | Identical to BV grades |
| Korea | KR Rules | KR AH620, DH620, EH620, FH620 | Equivalent grades |
| Japan | ClassNK Rules | NK AH620, DH620, EH620, FH620 | Equivalent grades |
| Italy | RINA Rules | RINA AH620, DH620, EH620, FH620 | Equivalent grades |
| France | Bureau Veritas Rules | BV AH620, DH620, EH620, FH620 | Original designation |
BV A620 Shipbuilding Steel Coil Application Introduction
BV A620 steel is utilized where high strength and reduced weight are critical, withstanding dynamic loads, fatigue, and low-temperature toughness. It is suitable for welded structures requiring classification society approval. Typical processing includes cutting, cold forming, and welding under controlled conditions. Preheating and post-weld heat treatment may be specified based on thickness.
Product Applications: Container ship hatch coamings and decks, Jack-up rig legs and chords, FPSO structural modules, Icebreaker hull plating, Crane booms and jibs, Tubular joints for offshore structures
Processed into products: Longitudinal stiffeners, Transverse frames, Bulkhead plates, Deck plates, Bottom shell plating, Main girder webs
Application industries: Shipbuilding (hull, superstructure), Offshore oil & gas platforms, Marine and coastal engineering, Renewable energy (offshore wind turbine foundations), Heavy machinery and crane manufacturing
BV A620 Shipbuilding Steel Coil Similar / Alternative Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | IACS UR W11 | AH690, DH690, EH690, FH690 | Higher strength (690 MPa) alternative; requires more careful welding |
| International | IACS UR W11 | AH550, DH550, EH550, FH550 | Lower strength (550 MPa) alternative; better formability |
| International | IACS UR W11 | AH460, DH460, EH460, FH460 | Common lower strength alternative; good balance |
| Europe | EN 10025-6 | S690QL, S690QL1 | Quenched and tempered structural steel, not directly certified for marine but similar mechanicals |
| USA | ASTM A514 / A517 | Grade B, H, Q etc. | High yield strength quenched and tempered steel; used in construction but not ship classed |
Notes:
Welding: Low hydrogen welding processes recommended. Preheat and interpass temperatures depend on thickness and carbon equivalent. Z-Grade: For improved through-thickness properties, Z25 or Z35 can be specified per BV rules. Certification: Each shipment must include BV material certificates (Form 3.1 or 3.2). Thickness Range: Typical availability in coil form is 3–25 mm; plates up to 100 mm under TMCP or Q&T.
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