LR EH55 Shipbuilding Steel Coil
LR EH55 Shipbuilding Steel Coil: High-Strength Marine Grade for Extreme Environments
LR EH55 is a high-strength shipbuilding steel grade certified by Lloyd's Register, offering minimum yield strength of 550 MPa, excellent low-temperature toughness, and weldability. Ideal for critical structural components in ships and offshore platforms.
Hot rolling, Normalizing, TMCP (Thermo-Mechanical Control Process), Quenching and Tempering (optional), Cutting, Bending, Welding
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LR EH55 Shipbuilding Steel Coil Introduction
LR EH55 is a normalized or thermo-mechanically controlled processed (TMCP) steel with a minimum yield strength of 550 MPa, classified as an extra high-strength structural steel for marine applications. It is designed to withstand harsh sea conditions and heavy loads, providing superior weldability and impact toughness at temperatures down to -40°C. This grade is part of the EH series, where the letter E designates fine grain practice and enhanced low-temperature notch toughness, while H55 signifies 550 MPa yield point. LR EH55 steel coil is widely used in hull structures, deck plates, and offshore constructions requiring high strength-to-weight ratios and fatigue resistance.
LR EH55 Shipbuilding Steel Coil Chemical Composition
The chemical composition of LR EH55 steel is carefully controlled to achieve high strength and excellent low-temperature toughness. Key elements include carbon, manganese, silicon, and micro-alloying elements such as niobium, vanadium, and titanium. The carbon equivalent (CEV) is restricted to ensure good weldability.
| Element | Standard Value | Notes |
|---|---|---|
| Carbon (C) | ≤0.18% | Maximum, depending on thickness |
| Silicon (Si) | ≤0.50% | Usually 0.10-0.50% |
| Manganese (Mn) | 0.90-1.60% | Higher Mn for strength |
| Phosphorus (P) | ≤0.025% | Max |
| Sulfur (S) | ≤0.025% | Max |
| Aluminum (Al) | ≥0.015% | Fine grain practice, acid soluble |
| Niobium (Nb) | 0.02-0.05% | Micro-alloying, typical |
| Vanadium (V) | 0.05-0.10% | Micro-alloying, typical |
| Titanium (Ti) | 0.007-0.05% | Micro-alloying, typical |
| Nitrogen (N) | ≤0.009% | Max |
| Chromium (Cr) | ≤0.20% | Residual, may be added for hardenability |
| Nickel (Ni) | ≤0.40% | Residual or added for toughness |
| Molybdenum (Mo) | ≤0.08% | Residual |
| Copper (Cu) | ≤0.30% | Residual |
| Carbon Equivalent (CEV) | ≤0.43% | Typical for 550 MPa grade, based on IIW formula |
LR EH55 Shipbuilding Steel Coil Thermal and Electrical Physical Properties
Physical properties for LR EH55 steel are typical of high-strength low-alloy steels. These values are estimated based on similar steel grades and may vary with actual processing conditions.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | Room temperature |
| Modulus of Elasticity (E) | 210 | GPa | Room temperature |
| Shear Modulus (G) | 81 | GPa | Estimated |
| Poisson's Ratio (ν) | 0.3 | - | - |
| Thermal Expansion Coefficient (α) | 11.5 | 10⁻⁶/K | 20-100°C |
| Thermal Expansion Coefficient (α) | 12.3 | 10⁻⁶/K | 20-300°C |
| Thermal Conductivity (λ) | 42 | W/(m·K) | Room temperature |
| Specific Heat Capacity (cp) | 480 | J/(kg·K) | Room temperature |
| Electrical Resistivity (ρe) | 0.22 | µΩ·m | Room temperature |
LR EH55 Shipbuilding Steel Coil Mechanical Properties
The mechanical properties of LR EH55 steel are specified for tensile testing and impact testing. The minimum yield strength is 550 MPa for thicknesses up to 50 mm, but may reduce for thicker sections. Impact test temperatures are -40°C for longitudinal and transverse specimens, with minimum energy values depending on grade and thickness. Bend tests are also required.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥550 | MPa | Thickness ≤50 mm |
| Yield Strength (ReH) | ≥530 | MPa | Thickness 50-70 mm |
| Yield Strength (ReH) | ≥510 | MPa | Thickness 70-100 mm |
| Tensile Strength (Rm) | 670-830 | MPa | Thickness ≤100 mm |
| Elongation (A5) | ≥14 | % | Gauge length 5.65√S0 |
| Impact Energy (KV2) | ≥34J (longitudinal), ≥24J (transverse) | J | At -40°C, average of 3 specimens, min single value 70% |
| Bend Test (Dia. of former) | 3t (t=specimen thickness) | 180° bend, no cracks | |
| Hardness | Not specified, typically 220-300 HB | HBW | For reference |
LR EH55 Shipbuilding Steel Coil Fully Equivalent Material Standards and Alternative Grades
| Country/Region | Standard | Grade | Notes |
|---|---|---|---|
| International (IACS) | UR W11 | EH55 | Common notation |
| Lloyd's Register (LR) | LR Rules | EH55 | Original grade |
| American Bureau of Shipping (ABS) | ABS Rules | EH55 | Direct equivalent |
| DNV GL (now DNV) | DNV Rules | E550 | Similar notation |
| Bureau Veritas (BV) | BV Rules | EH55 | Direct equivalent |
| Germanischer Lloyd (GL) | GL Rules | E550 | Now part of DNV |
| Korean Register (KR) | KR Rules | EH55 | Direct equivalent |
| China Classification Society (CCS) | CCS Rules | EH550 | Equivalent |
| Nippon Kaiji Kyokai (ClassNK) | NK Rules | KE550 | K for high tensile, E550 |
| Russian Maritime Register (RS) | RS Rules | E550 | Similar |
| Registro Italiano Navale (RINA) | RINA Rules | E550 | Similar |
| EN Standard | EN 10025-6 | S690QL (approx, higher strength) | Not exact, S690QL has higher strength; shipbuilding standards specific |
LR EH55 Shipbuilding Steel Coil Application Introduction
LR EH55 shipbuilding steel coil is primarily used in the construction of hull structures that require high strength and excellent toughness at low temperatures. It is suitable for critical components in ships and offshore installations operating in harsh marine environments.
Product Applications: Hull plates, Deck plates, Longitudinal stiffeners, Transverse bulkheads, Icebreakers, Heavy-lift crane vessels, FPSO hulls, Jack-up rig components, Semi-submersible platforms, Offshore wind turbine transition pieces and foundations
Processed into products: Bottom shell plating, Side shell frames, Bilge keels, Deck girders, Hatch coamings, Crane pedestals, Stern frames, Rudder horns, Sea fastenings, Anchor racks, Mooring brackets
Application industries: Shipbuilding, Offshore Oil & Gas, Renewable Energy (Offshore Wind), Defense (Naval Vessels), Marine Engineering
LR EH55 Shipbuilding Steel Coil Similar/Comparable Substitute Materials
| Country/Region | Standard | Grade | Notes |
|---|---|---|---|
| China | GB/T 712 | E550 | Shipbuilding steel, similar strength; toughness may vary |
| Japan | JIS G 3106 | SM570 | Similar tensile strength (570-720 MPa), but not specifically marine certified; may need additional impact testing |
| USA | ASTM A131 / A131M | EH36 | Lower strength (355 MPa), but similar low-temperature toughness; EH55 not in ASTM A131, EH36 is standard |
| Europe | EN 10025-6 | S550Q | Quenched and tempered steel, minimum yield 550 MPa, but different toughness and weldability requirements |
| Russia | GOST 5521 | E550 | Shipbuilding steel, comparable |
| Korea | KS D 3605 | EH55K | Similar notation |
Notes:
LR EH55 steel must be certified by Lloyd's Register surveyors during manufacturing. Welding procedures must be approved, and preheat may be applied for thicker sections. Normalized or TMCP conditions are standard; if quenched and tempered, properties may differ. Dimensional tolerances and flatness are per LR rules and industry standards. For coils, thickness is typically up to 12 mm; for plates, up to 100 mm or more. Always consult the latest LR rules and manufacturer's datasheets for exact specifications.
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