LR DH46 Shipbuilding Steel Coil
LR DH46 Shipbuilding Steel Coil: High-Strength Hull Plate for Extreme Conditions
Comprehensive data sheet for LR DH46 shipbuilding steel coil, including chemical composition, mechanical properties, physical characteristics, equivalent grades, and applications.
Hot rolling, normalizing, thermomechanical controlled processing (TMCP), quenching and tempering (optional)
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LR DH46 Shipbuilding Steel Coil Introduction
LR DH46 is a high-strength shipbuilding steel grade specified by Lloyd's Register (LR) under the IACS Unified Requirement W11. It is designed for critical structural components in ship hulls and offshore structures where high strength, excellent weldability, and good low-temperature toughness are essential. DH46 exhibits a minimum yield strength of 460 MPa and is supplied in normalized or thermomechanically controlled processed (TMCP) condition. The 'D' designation indicates an impact test temperature of -20°C, ensuring reliable performance in cold environments. This grade offers a fine-grained microstructure with controlled carbon equivalent to maintain superior weldability without compromising strength.
LR DH46 Shipbuilding Steel Coil Chemical Composition
The following chemical composition limits apply as per LR Rules for DH46 grade. All values are in weight percent. Microalloying elements such as Nb, V, and Ti may be added individually or in combination to achieve the required strength and toughness. The carbon equivalent (Ceq) is controlled for weldability and shall not exceed the specified limit.
| Element | Standard Value (max, unless range given) | Remarks |
|---|---|---|
| C | ≤ 0.20 | |
| Mn | 0.90 – 1.70 | |
| Si | 0.10 – 0.55 | |
| P | ≤ 0.030 | |
| S | ≤ 0.030 | |
| Al (total) | ≥ 0.015 | Acid soluble aluminium minimum |
| Nb | ≤ 0.05 | Optional microalloying |
| V | ≤ 0.10 | Optional microalloying |
| Ti | ≤ 0.03 | Optional microalloying |
| Cu | ≤ 0.35 | May be present from scrap |
| Cr | ≤ 0.25 | |
| Ni | ≤ 0.40 | |
| Mo | ≤ 0.08 | |
| N | ≤ 0.009 | |
| Ceq | ≤ 0.45 | Carbon equivalent (IIW formula) |
LR DH46 Shipbuilding Steel Coil Physical Properties
The physical properties listed below are typical for low-alloy structural steels and are not part of the mandatory ship classification specification. They are provided for engineering calculations such as thermal stress analysis, heat transfer, and electrical resistance. Actual values may vary slightly with heat treatment and composition.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | at 20°C |
| Modulus of Elasticity (E) | 205 | GPa | at 20°C |
| Shear Modulus (G) | 80 | GPa | at 20°C |
| Poisson's Ratio (ν) | 0.3 | – | Room temperature |
| Thermal Expansion Coefficient (α) | 12.0 × 10&supminus;&sup6; | K&supminus;¹ | 20–100°C |
| Thermal Conductivity (λ) | 46 | W/(m·K) | at 20°C |
| Specific Heat Capacity | 460 | J/(kg·K) | at 20°C |
| Electrical Resistivity (ρe) | 0.23 | µΩ·m | at 20°C |
LR DH46 Shipbuilding Steel Coil Mechanical Properties
Mechanical properties are tested in accordance with LR Rules. The values below apply to plate/coil thicknesses up to 50 mm. For thicker sections, slightly reduced strength and elongation may apply. Impact tests are carried out on longitudinal Charpy V-notch specimens at a temperature of -20°C, with a minimum average absorbed energy of 34 J.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 460 | MPa | Transverse, t ≤ 50 mm |
| Tensile Strength (Rm) | 570 – 720 | MPa | Transverse, t ≤ 50 mm |
| Elongation (A) | ≥ 17 | % | Gauge length 5.65√So, t ≤ 50 mm |
| Bend Test (180°) | d = 3a (no cracks) | – | Bend diameter ratio, t ≤ 50 mm |
| Impact Energy (KV, -20°C) | ≥ 34 | J | Longitudinal, min. average of 3 specimens |
LR DH46 Shipbuilding Steel Coil Exact Equivalent Grades Under Classification Society Rules
| Country/Region | Standard/Rules | Equivalent Grade | Remarks |
|---|---|---|---|
| International IACS | IACS UR W11 | DH46 | Common designation across all members |
| USA | ABS Rules | DH46 | American Bureau of Shipping |
| France | BV Rules | DH46 | Bureau Veritas |
| China | CCS Rules | DH46 | China Classification Society |
| Norway/Germany | DNV Rules | DH46 | DNV GL (now DNV) |
| South Korea | KR Rules | DH46 | Korean Register |
| Japan | NK Rules | KD46 | Nippon Kaiji Kyokai (ClassNK) |
| Italy | RINA Rules | DH46 | Registro Italiano Navale |
| Russia | RS Rules | DH46 | Russian Maritime Register of Shipping |
LR DH46 Shipbuilding Steel Coil Application Introduction
LR DH46 steel is specifically certified for welded construction in ship and offshore structures. Its combination of high yield strength and excellent low-temperature toughness makes it suitable for heavily stressed members. It is widely used in newbuild and repair projects for both merchant and naval vessels, as well as offshore platforms, where weight savings and structural integrity are critical.
Product Applications: Hull main deck and strength deck plates, Bottom shell and bilge plates, Longitudinal and transverse bulkheads, Web frames and stringers, Jack-up rig leg chords and racks, Heavy-lift crane pedestals, Semi-submersible pontoon structures
Processed into products: Primary hull stiffeners (T-bars, bulb flats), Transverse frame webs, Bottom plate stiffeners, Side shell insert plates, Watertight flat panel assemblies, Hatch coaming and corner plates, Offshore module skid beams
Application industries: Shipbuilding and ship repair, Offshore oil and gas exploration, Marine renewable energy (wind turbine foundations), Heavy civil engineering (bridge construction), Naval defence
LR DH46 Shipbuilding Steel Coil Similar or Alternative Materials with Close Properties
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International IACS | IACS UR W11 | EH46 | Impact temperature -40°C; superior low-temperature toughness |
| International IACS | IACS UR W11 | AH46 | Impact temperature 0°C; slightly lower toughness requirements |
| European Union | EN 10025-4 | S460ML | Thermomechanical rolled fine-grain structural steel; similar yield strength but not specifically a shipbuilding grade; additional certification may be required |
| USA | ASTM A572/A572M | Grade 65 (Type 1) | High-strength low-alloy structural steel with minimum yield 450 MPa; differs in impact test conditions and shipbuilding approval |
| China | GB/T 712 | DH46 | Chinese national shipbuilding steel equivalent; identical under CCS implementation |
Notes:
Weldability: DH46 is designed for good weldability with conventional shipyard practices. Preheating may be required for thicknesses above 30 mm, especially when using low heat input processes. Through-thickness properties: For applications with significant out-of-plane loading, Z-grade requirements (Z25, Z35) can be specified in line with EN 10164 or ship classification rules. Corrosion resistance: As a standard carbon-manganese structural steel, DH46 requires protective coatings or cathodic protection in seawater environments.
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