NK A47 Shipbuilding Steel Coil
NK A47 Shipbuilding Steel Coil - High-Strength Hull Structural Steel for Marine Engineering
Detailed material data for NK A47 shipbuilding steel coil per Nippon Kaiji Kyokai rules, including chemical composition, mechanical properties, physical properties, and equivalent grades.
Controlled rolling (TMCP) or normalizing; suitable for cold forming, welding, cutting
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NK A47 Shipbuilding Steel Coil Introduction
NK A47 is a high-strength shipbuilding steel coil grade defined by Nippon Kaiji Kyokai (ClassNK) for hull structural applications. It corresponds to the IACS UR W11 grade A460, offering a minimum yield strength of 460 MPa and guaranteed impact toughness at 0°C. This fine-grain, fully killed steel is produced via controlled rolling or normalizing, ensuring excellent weldability and formability. The coil form enables efficient fabrication of large structural components with consistent thickness and mechanical properties. Typical applications include decks, side shells, bottom plates, and longitudinal stiffeners in ocean-going vessels and offshore structures.
NK A47 Shipbuilding Steel Coil Chemical Composition
ClassNK requirements for NK A47 steel are aligned with IACS UR W11. The steel is microalloyed with niobium, vanadium, or titanium to achieve fine grain size and high strength while maintaining low carbon equivalent for good weldability. All values are maximum unless a range is specified.
| Element | Standard Value (max %) | Remarks |
|---|---|---|
| Carbon (C) | 0.18 | |
| Manganese (Mn) | 0.90–1.60 | Range |
| Silicon (Si) | 0.50 | |
| Phosphorus (P) | 0.030 | |
| Sulfur (S) | 0.030 | |
| Niobium (Nb) | 0.05 | |
| Vanadium (V) | 0.10 | |
| Titanium (Ti) | 0.02 | |
| Aluminum (Al, total) | 0.015 min | Minimum required for fine-grain practice |
| Copper (Cu) | 0.35 | |
| Chromium (Cr) | 0.20 | |
| Nickel (Ni) | 0.40 | |
| Molybdenum (Mo) | 0.08 | |
| Nitrogen (N) | 0.009 | If not fixed by sufficient Al or other strong nitride formers |
NK A47 Shipbuilding Steel Coil Thermal and Electrical Physical Properties
The following physical properties are typical for high-strength low-alloy shipbuilding steel at room temperature unless otherwise noted. These values are not mandatory in the material standard but are useful for design and simulation.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | 20 °C |
| Elastic Modulus (E) | 210 | GPa | 20 °C |
| Shear Modulus (G) | 80 | GPa | 20 °C |
| Poisson's Ratio (ν) | 0.30 | 20 °C | |
| Thermal Expansion Coefficient (α) | 11.5 × 10⁻⁶ | /K | 20 – 100 °C |
| Thermal Expansion Coefficient (α) | 12.5 × 10⁻⁶ | /K | 20 – 200 °C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | 20 °C |
| Specific Heat Capacity (cp) | 460 | J/(kg·K) | 20 °C |
| Electrical Resistivity (ρₑ) | 0.20 × 10⁻⁶ | Ω·m | 20 °C |
NK A47 Shipbuilding Steel Coil Mechanical Properties
Mechanical properties as per NK/ IACS standards for thickness ≤ 100 mm. Tensile testing in transverse direction; impact test in longitudinal direction unless otherwise specified. Values may be adjusted for thinner/thicker materials per the rules.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 460 | MPa | Thickness ≤ 100 mm |
| Tensile Strength (Rm) | 570 – 720 | MPa | Thickness ≤ 100 mm |
| Elongation (A5) | ≥ 17 | % | Gauge length 5.65√S₀, thickness ≤ 50 mm |
| Elongation (A5) | ≥ 16 | % | Thickness > 50 mm to 70 mm |
| Elongation (A5) | ≥ 15 | % | Thickness > 70 mm to 100 mm |
| Impact Energy (KV2, longitudinal) | ≥ 34 | J | at 0 °C, thickness ≤ 50 mm |
| Impact Energy (KV2, longitudinal) | ≥ 27 | J | at 0 °C, thickness > 50 mm to 70 mm |
| Impact Energy (KV2, longitudinal) | ≥ 24 | J | at 0 °C, thickness > 70 mm to 100 mm |
| Impact Energy (KV2, transverse) | ≥ 24 | J | at 0 °C, thickness ≤ 50 mm |
| Impact Energy (KV2, transverse) | ≥ 18 | J | at 0 °C, thickness > 50 mm to 70 mm |
| Impact Energy (KV2, transverse) | ≥ 16 | J | at 0 °C, thickness > 70 mm to 100 mm |
| Bending Test (180°) | d = 3a | Thickness ≤ 25 mm | |
| Bending Test (180°) | d = 4a | Thickness > 25 mm to 50 mm | |
| Bending Test (180°) | d = 5a | Thickness > 50 mm |
NK A47 Shipbuilding Steel Coil Completely Equivalent Grades and Replacement Options
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| International | IACS UR W11 | A460 | Direct equivalent; identical requirements |
| USA | ABS | AH47 | American Bureau of Shipping |
| Norway/Germany | DNV | NVA47 | Det Norske Veritas |
| UK | LR | AH47 | Lloyd's Register |
| France | BV | AH47 | Bureau Veritas |
| China | CCS | AH47 | China Classification Society |
| South Korea | KR | AH47 | Korean Register |
| Italy | RINA | AH47 | Registro Italiano Navale |
| Russia | RS | A47 | Russian Maritime Register of Shipping |
NK A47 Shipbuilding Steel Coil Application Introduction
NK A47 shipbuilding steel coil is engineered for critical structural components in marine environments where high strength, good toughness, and weldability are essential. Its typical delivery as hot-rolled coil allows efficient fabrication of long continuous members.
Product Applications: Hull plates for container ships, bulk carriers, tankers, Deck stringer plates and sheer strakes, Bottom shell and bilge keel plates, Longitudinal stiffeners and frames, Transverse web frames and floors, Hatch coaming and mast house structures, Offshore platform legs and braces
Processed into products: Profiled deck beams, Welded T-section stiffeners, Flanged plate girders, Bulkhead panels, Corrugated bulkhead sections, Pipe support brackets, Crane pedestal reinforcements
Application industries: Shipbuilding (commercial and naval vessels), Offshore oil & gas platforms, Marine renewable energy (wind turbine foundations), Heavy barge and dredger construction, Bridge and structural engineering (if additional marine certification is needed)
NK A47 Shipbuilding Steel Coil Similar / Alternative Materials
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | NK | KA36 / KD36 / KE36 | Lower yield strength (≥355 MPa); same usage but lower load capacity |
| International | IACS UR W11 | D460, E460, F460 | Same strength but lower impact test temperatures (-20°C, -40°C, -60°C) |
| International | EN 10025-6 | S460G2+M/Q | Structural steel with 460 MPa yield; similar mechanicals but marine classification not guaranteed |
| Japan | JIS G 3106 | SM490YA | Yield 365 MPa, used in shipbuilding for less critical parts |
Notes:
Weldability: NK A47 has a controlled carbon equivalent (typically ≤ 0.43% CEV) to minimize cold cracking risk. Preheating may be required for thick sections or low ambient temperatures.
Corrosion: Standard shipbuilding paint systems or cathodic protection are needed for seawater immersion.
Availability: Coil thickness typically ranges from 3 mm to 25 mm, width up to 4500 mm; heavier gauges available as plates.
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