GL Grade E Shipbuilding Steel Plate
GL Grade E Shipbuilding Steel Plate - Certified Marine-Grade Structural Steel for High-Strength & Low-Temperature Service
Explore the properties, chemical composition, mechanical and thermal data of GL Grade E shipbuilding steel plate. Certified under Germanischer Lloyd rules, ideal for critical ship structures with excellent notch toughness at -40°C. Includes international equivalents and application guidance.
Hot rolling, normalizing, cutting, forming, welding, machining
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GL Grade E Shipbuilding Steel Plate Introduction
GL Grade E is a normalized, fine-grain structural steel plate prescribed by the Germanischer Lloyd (GL) rules for shipbuilding and offshore constructions. Minimum yield strength of 235 MPa and tensile strength in the range 400–520 MPa, combined with guaranteed impact toughness down to -40°C, make it suitable for hulls, decks, and structural members exposed to low-temperature environments.
- Excellent weldability and formability with controlled aluminium grain refinement.
- Supplied in normalized condition with inspection certificates in accordance with GL regulations.
- Fully compliant with IACS UR W11 and internationally recognized by all major classification societies.
GL Grade E Shipbuilding Steel Plate Chemical Composition
The chemical composition of GL Grade E steel plate is strictly controlled to ensure good weldability, grain refinement, and low-temperature toughness. Aluminium is added as a grain refiner; residual elements such as chromium, nickel, and copper are limited to avoid adverse effects on mechanical properties. The values below are typical ladle analysis requirements per GL rules.
| Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | ≤0.18% | Maximum |
| Manganese (Mn) | 0.70–1.50% | |
| Silicon (Si) | 0.10–0.50% | |
| Phosphorus (P) | ≤0.035% | Maximum |
| Sulfur (S) | ≤0.035% | Maximum |
| Aluminium (Al, total) | ≥0.015% | Acid-soluble Al equivalent; mandatory for fine-grain practice |
| Chromium (Cr, residual) | ≤0.30% | Typical maximum for residual elements |
| Nickel (Ni, residual) | ≤0.30% | Maximum |
| Copper (Cu, residual) | ≤0.35% | Maximum; slightly higher than other residuals |
| Molybdenum (Mo, residual) | ≤0.08% | Maximum |
GL Grade E Shipbuilding Steel Plate Thermal and Electrical Physical Properties
The following physical properties are typical for normalized carbon-manganese structural steels and serve as reference for design and simulation. These values are not mandatory requirements but are widely accepted for GL Grade E steel. Actual values can vary slightly with processing and temperature.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | At 20°C |
| Young's Modulus (E) | 205 | GPa | At room temperature |
| Shear Modulus (G) | 80 | GPa | At room temperature |
| Poisson's ratio (ν) | 0.29 | – | At room temperature |
| Coefficient of thermal expansion (α) | 12.0 | 10⁻⁶ /K | Between 20°C and 100°C |
| Coefficient of thermal expansion (α) | 13.0 | 10⁻⁶ /K | Between 20°C and 200°C |
| Coefficient of thermal expansion (α) | 14.0 | 10⁻⁶ /K | Between 20°C and 400°C |
| Thermal conductivity (λ) | 51 | W/(m·K) | At 20°C |
| Specific heat capacity (cp) | 460 | J/(kg·K) | At 20°C |
| Electrical resistivity (ρ_e) | 0.18 | µΩ·m | At 20°C |
GL Grade E Shipbuilding Steel Plate Mechanical Properties
Mechanical properties are determined on transverse test pieces taken from normalized plates. The impact test temperature is -40°C and the minimum absorbed energy depends on plate thickness. The bend test ensures ductility and formability. Values shown are the minimum requirements according to GL rules for Grade E steel plates.
| Property | Required Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH, min.) | 235 | MPa | Plate thickness ≤ 100 mm |
| Tensile Strength (Rm) | 400–520 | MPa | Plate thickness ≤ 100 mm |
| Elongation after fracture (A, min.) | 22 | % | Gauge length 5.65√So; transverse specimen |
| Impact energy (KV, longitudinal, min.) | 24 | J | -40°C; plate thickness t ≤ 50 mm |
| Impact energy (KV, longitudinal, min.) | 34 | J | -40°C; plate thickness 50 < t ≤ 70 mm |
| Impact energy (KV, longitudinal, min.) | 41 | J | -40°C; plate thickness 70 < t ≤ 100 mm |
| Bend test (180°) | d = 3a | – | Plate thickness ≤ 50 mm; no cracks or defects |
| Bend test (180°) | d = 4a | – | Plate thickness > 50 mm |
GL Grade E Shipbuilding Steel Plate Internationally Equivalent Standards and Replaceable Grades
| Country / Region | Standard / Classification Society | Grade | Remarks |
|---|---|---|---|
| International (IACS) | IACS UR W11 | E | All IACS members recognize this grade |
| United States | ABS | Grade E | American Bureau of Shipping |
| France | BV | Grade E | Bureau Veritas |
| China | CCS | E | China Classification Society |
| Norway / Germany | DNV GL (now DNV) | NV E / GL-E | Merged class; rules refer to original societies |
| United Kingdom | LR | Grade E | Lloyd's Register |
| Japan | NK (ClassNK) | Grade E | Nippon Kaiji Kyokai |
| Italy | RINA | Grade E | Registro Italiano Navale |
| Russia | RS | Grade E | Russian Maritime Register of Shipping |
| South Korea | KR | Grade E | Korean Register |
| India | IRS | Grade E | Indian Register of Shipping |
GL Grade E Shipbuilding Steel Plate Application Introduction
GL Grade E steel is engineered for welded structures in shipbuilding requiring guaranteed toughness at subzero temperatures. Its typical yield point allows lightweight design without compromising safety. Following normalizing, the plate exhibits uniform mechanical properties and excellent fatigue resistance.
- Hull envelopes, longitudinal and transverse bulkheads.
- Structural members in ice-class vessels operating at low ambient temperatures.
- Offshore platform topsides and substructures where classification society certification is mandatory.
Product Applications: Merchant ships (cargo, container, bulk carriers), Tankers and LNG/LPG carriers, Offshore platforms (jack-up rigs, semi-submersibles), Ice-breakers and polar supply vessels, Floating production storage and offloading units (FPSO)
Processed into products: Deck plates and bottom shell plating, Side shell and longitudinal stiffeners, Bulkhead plates and brackets, Hatch coamings and superstructure supports, Web frames and stringers, Bilge keels and skegs, Caisson structures and module support stools
Application industries: Shipbuilding and repair, Offshore oil & gas exploration, Port and harbour construction, Marine heavy engineering, Defence and naval architecture
GL Grade E Shipbuilding Steel Plate Materials with Comparable Properties
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-2 | S235JR/ S235J0/ S235J2 | Similar yield strength but different impact test requirements; may lack Al grain refinement |
| USA | ASTM A36/A36M | A36 | Yield 250 MPa, but no guaranteed low-temperature toughness |
| International | ISO 630-2 | E235B | Structural steel with similar tensile range; often fine-grain killed but needs verification |
| Russia/Ukraine | ГОСТ 5521-93 | S235J2 | May match when impact tested at -20°C; contact classification society for substitution |
Notes:
Delivery condition: Normalized (N) is the standard treatment; thermo-mechanically controlled rolling (TMCP) may be accepted subject to GL approval. Certification must include GL surveyor or recognized independent inspection.
Plates are usually produced with close thickness tolerances as per GL rules. In case of substitution with an equivalent grade from another classification society, the purchaser must obtain prior agreement from the overseeing class surveyor. Welding consumables should be matched to the base material and qualified for the intended service temperature.
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