NK E36 Shipbuilding Steel Coil
NK E36 Shipbuilding Steel Coil: High-Strength Marine Grade for Arctic Conditions
Explore NK E36 shipbuilding steel coil – a high-strength, low-temperature tough grade certified by Nippon Kaiji Kyokai. Ideal for hull structures, offshore platforms, and polar vessels with guaranteed impact properties at -40°C.
Cold forming, Hot rolling, Welding, Bending, Cutting, Machining
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NK E36 Shipbuilding Steel Coil Introduction
NK E36 is a high-strength hull structural steel grade certified by Nippon Kaiji Kyokai (ClassNK) under its Rules for the Survey and Construction of Steel Ships. This fully killed, fine-grain steel offers a minimum yield strength of 355 MPa and excellent notch toughness down to -40°C, making it suitable for critical shipbuilding applications in cold environments. It is typically delivered in normalized or thermomechanically rolled condition, available as coils and plates. NK E36 complies with IACS Unified Requirements and is internationally interchangeable with grades such as ABS EH36, LR EH36, and DNV E36.
NK E36 Shipbuilding Steel Coil Chemical Composition
The chemical composition of NK E36 steel is controlled to ensure high strength, good weldability, and excellent low-temperature toughness. Fine-grain practice elements such as niobium, vanadium, or titanium may be added singly or in combination. Carbon equivalent (CEV) is controlled to guarantee weldability.
| Element | Standard Value (max, unless range given) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.18 | |
| Silicon (Si) | ≤ 0.50 | |
| Manganese (Mn) | 0.90 – 1.60 | |
| Phosphorus (P) | ≤ 0.035 | |
| Sulfur (S) | ≤ 0.035 | |
| Aluminum (Al, acid soluble) | ≥ 0.015 | If used as grain refiner |
| Niobium (Nb) | 0.02 – 0.05 | Optional grain refiner |
| Vanadium (V) | 0.05 – 0.10 | Optional grain refiner |
| Titanium (Ti) | ≤ 0.02 | Optional grain refiner |
| Copper (Cu) | ≤ 0.35 | May be present |
| Chromium (Cr) | ≤ 0.20 | Residual element |
| Nickel (Ni) | ≤ 0.40 | Residual element |
| Molybdenum (Mo) | ≤ 0.08 | Residual element |
| Carbon Equivalent (CEV) | ≤ 0.38 | For thickness ≤ 50 mm; calculated per IACS formula |
NK E36 Shipbuilding Steel Coil Physical Properties
Physical properties are not mandatory in ClassNK rules but are provided for design purposes. Values are representative for high-strength structural steel with similar chemistry. They may vary slightly depending on exact composition and heat treatment condition.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | At room temperature |
| Modulus of Elasticity (E) | 205 | GPa | At room temperature |
| Shear Modulus (G) | 80 | GPa | At room temperature |
| Poisson's Ratio (ν) | 0.29 | – | At room temperature |
| Thermal Expansion Coefficient (α) | 11.7 × 10⁻⁶ | /K | 20 – 100°C |
| Thermal Conductivity (λ) | 51 | W/(m·K) | At room temperature |
| Specific Heat Capacity | 460 | J/(kg·K) | At room temperature |
| Electrical Resistivity (ρ_e) | 0.22 | μΩ·m | At 20°C |
NK E36 Shipbuilding Steel Coil Mechanical Properties
The mechanical properties are verified on tensile and impact specimens taken from normalized or TMCP delivered condition. Impact test temperature of -40°C is a defining characteristic of the 'E' grade. Values apply for thickness ≤ 50 mm; for thicker products, slightly reduced yield and impact values may apply. Bending tests require no cracking when bent through 180°.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 355 | MPa | Transverse tensile, thickness ≤ 50 mm |
| Tensile Strength (Rm) | 490 – 620 | MPa | Transverse tensile, thickness ≤ 50 mm |
| Elongation (A) | ≥ 21 | % | Gauge length 5.65√So, thickness ≤ 50 mm |
| Impact Energy (KV₂, longitudinal) | ≥ 24 (average of 3 specimens, 1 individual min 17) | J | -40°C, Charpy V-notch, thickness ≤ 50 mm |
| Bend Test (Diameter of former) | 3 × thickness (a) | – | 180° bend, no crack, thickness ≤ 50 mm (for tensile strength 490-620 class) |
| Impact Energy (KV₂, transverse) | ≥ 17 (average of 3 specimens, 1 individual min 12) | J | -40°C, Charpy V-notch, thickness ≤ 50 mm (when specified by purchaser) |
NK E36 Shipbuilding Steel Coil Identical Classification Society Grades
| Country / Classification Society | Standard | Grade | Remarks |
|---|---|---|---|
| Japan / NK | NK Rules Part K | NK E36 | Original grade (this datasheet) |
| USA / ABS | ABS Rules | ABS EH36 | Identical IACS UR W11 grade |
| UK / LR | Lloyd's Register Rules | LR EH36 | Identical IACS UR W11 grade |
| Norway / DNV | DNV Rules | DNV E36 | Identical IACS UR W11 grade |
| France / BV | Bureau Veritas Rules | BV EH36 | Identical IACS UR W11 grade |
| China / CCS | CCS Rules | CCS E36 | Identical IACS UR W11 grade |
| South Korea / KR | KR Rules | KR E36 | Identical IACS UR W11 grade |
NK E36 Shipbuilding Steel Coil Application Introduction
NK E36 steel coil is engineered for demanding marine and offshore environments where high strength, reliable low-temperature toughness, and excellent weldability are essential. Its ClassNK certification ensures compliance with strict ship classification rules, making it universally accepted for newbuilding and repair projects.
Product Applications: Hull plates and stiffeners for ice-strengthened vessels, Deck panels and bulkheads for polar supply ships, Offshore platform structural members (nodes, legs, braces), Ship rudder horns and stern frames, Heavy-lift crane booms and pedestals, Pressure hulls for submersibles (subject to special approval)
Processed into products: Cut-to-length plates for shell plating, Longitudinals and transverse frames, Web frames and stringers, Structural pipes and hollow sections (when hot finished from coil), Welded built-up beams and girders, Foundations for winches, engines, and thrusters
Application industries: Commercial shipbuilding (container ships, bulk carriers, tankers), Naval and defense vessel construction, Offshore oil and gas platforms (jackets, decks, modules), Ice-class vessels and Arctic shipping, Renewable offshore wind turbine foundations, Heavy marine engineering and crane structures
NK E36 Shipbuilding Steel Coil Similar Non-Marine Structural Steels
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| Japan | JIS G 3106 | SM490A/B/C | Similar strength (490 MPa TS min), but impact test temperature not as low; not class-certified. |
| USA | ASTM A572 / A572M | Grade 50 [345] | Yield strength 345 MPa, similar for non-marine structural use; impact requirement upon agreement. |
| Europe | EN 10025-4 | S355ML | Thermomechanically rolled, -50°C impact option possible; not ship class approved per se. |
| China | GB/T 712 | EH36 | National standard for shipbuilding steel, identical technical requirements to NK E36. |
Notes:
Weldability: NK E36 exhibits good weldability with standard low-hydrogen procedures. Preheating is typically not required for thicknesses below 30 mm, though precise recommendations depend on CEV and restraint.
Corrosion: As carbon-manganese steel, it requires protective coatings or cathodic protection in seawater. Inspection: All coils are supplied with ClassNK certificate (material certificate 3.1 per EN 10204) verifying chemical and mechanical tests. For critical applications, ultrasonic testing to NK standards can be arranged.
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