EN 10225 S420G2+QT Shipbuilding Steel Coil
EN 10225 S420G2+QT Shipbuilding Steel Coil - High Strength Quenched & Tempered Offshore Steel
EN 10225 S420G2+QT is a high strength quenched and tempered structural steel for fixed offshore structures and shipbuilding, with excellent toughness at low temperatures.
Hot rolling followed by quenching and tempering (QT)
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EN 10225 S420G2+QT Shipbuilding Steel Coil Introduction
S420G2+QT is a weldable structural steel grade specified in EN 10225-1, delivered in the quenched and tempered condition. It is designed primarily for fixed offshore structures and shipbuilding applications requiring high strength and resistance to brittle fracture at sub-zero temperatures. The +QT suffix indicates the heat treatment: quenching followed by tempering, which ensures a fine-grained microstructure with a minimum yield strength of 420 MPa for thicknesses up to 63 mm. This grade offers good weldability, toughness down to -40°C, and consistent mechanical properties, making it ideal for critical structural components in harsh marine environments.
EN 10225 S420G2+QT Shipbuilding Steel Coil Chemical Composition
Chemical composition according to EN 10225-1:2009 for grade S420G2+QT. All values are maximum unless a range is given. Microalloying elements such as Nb, V, Ti are added to achieve the required strength and toughness after quenching and tempering.
| Chemical Element | Standard Value | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.14 | - |
| Silicon (Si) | ≤ 0.55 | - |
| Manganese (Mn) | ≤ 1.65 | - |
| Phosphorus (P) | ≤ 0.020 | - |
| Sulfur (S) | ≤ 0.010 | - |
| Nitrogen (N) | ≤ 0.012 | - |
| Total Aluminum (Al_t) | ≥ 0.015 | Typically fine grain practice |
| Niobium (Nb) | ≤ 0.04 | Microalloying element |
| Vanadium (V) | ≤ 0.08 | Microalloying element |
| Titanium (Ti) | ≤ 0.025 | Microalloying element |
| Chromium (Cr) | ≤ 0.25 | Residual |
| Molybdenum (Mo) | ≤ 0.25 | Residual |
| Nickel (Ni) | ≤ 0.70 | Residual |
| Copper (Cu) | ≤ 0.30 | Residual |
EN 10225 S420G2+QT Shipbuilding Steel Coil Thermal and Electrical Physical Properties
Physical properties for quenched and tempered structural steel, representative for grade S420G2+QT. Values are typical for carbon-manganese steels and are not specified in EN 10225 but are based on published engineering data.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | 20°C |
| Modulus of Elasticity (E) | 210 | GPa | 20°C |
| Shear Modulus (G) | 80 | GPa | 20°C |
| Poisson's Ratio (ν) | 0.3 | - | 20°C |
| Thermal Expansion Coefficient (α) | 11.7 | 10⁻⁶/K | 20–100°C |
| Thermal Expansion Coefficient (α) | 12.5 | 10⁻⁶/K | 20–300°C |
| Thermal Conductivity (λ) | 40 | W/(m·K) | 20°C |
| Specific Heat (c) | 460 | J/(kg·K) | 20°C |
| Electrical Resistivity (ρ_e) | 0.15 | 10⁻⁶ Ω·m | 20°C |
EN 10225 S420G2+QT Shipbuilding Steel Coil Mechanical Properties
Minimum mechanical property requirements for S420G2+QT as per EN 10225-1:2009. Values depend on thickness and orientation. Impact testing is performed on Charpy V-notch specimens at -40°C. Bending tests are carried out at room temperature with specified mandrel diameters.
| Property | Requirement Value | Unit | Test Condition |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 420 | MPa | Thickness ≤ 63 mm, longitudinal or transverse |
| Yield Strength (ReH) | ≥ 400 | MPa | Thickness 63 < t ≤ 100 mm |
| Yield Strength (ReH) | ≥ 390 | MPa | Thickness 100 < t ≤ 150 mm |
| Tensile Strength (Rm) | 500 - 660 | MPa | All thicknesses |
| Elongation (A) | ≥ 19 | % | Thickness ≤ 63 mm, longitudinal, L₀=5.65√S₀ |
| Elongation (A) | ≥ 19 | % | Thickness 63 < t ≤ 100 mm, longitudinal |
| Elongation (A) | ≥ 18 | % | Thickness 100 < t ≤ 150 mm, longitudinal |
| Impact Energy (KV) | ≥ 50 | J | -40°C, longitudinal, thickness ≤ 50 mm |
| Impact Energy (KV) | ≥ 33 | J | -40°C, longitudinal, thickness > 50 mm |
| Impact Energy (KV) | ≥ 33 | J | -40°C, transverse, all thicknesses |
| Bending Test (Mandrel Diameter) | 3t | mm | Thickness ≤ 63 mm, 180° bend |
| Bending Test (Mandrel Diameter) | 3.5t | mm | Thickness 63 < t ≤ 100 mm, 180° bend |
| Bending Test (Mandrel Diameter) | 4t | mm | Thickness 100 < t ≤ 150 mm, 180° bend |
EN 10225 S420G2+QT Shipbuilding Steel Coil Equivalent Standards and Replaceable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10225-1 | S420G2+QT | Original standard, quenched and tempered |
| International | ISO 19902:2020 | S420+QT | Identical requirements for fixed offshore structures |
| Norway | NORSOK M-120 | Y42 | Equivalent yield strength grade, QT condition |
EN 10225 S420G2+QT Shipbuilding Steel Coil Application Introduction
S420G2+QT is approved for critical structural applications in offshore and marine industries due to its excellent combination of strength, toughness, and weldability. It is used in highly stressed components exposed to low temperatures and dynamic loads.
Product Applications: Fixed offshore platform jackets and topsides, Hull structures of ships and floating vessels, Transition pieces and monopile foundations, Deck plates and stiffened panels
Processed into products: Main support beams and columns, Brace and node connections, Piles and penetration pieces, Stiffeners and brackets, Lifting trunnions and padeyes
Application industries: Offshore oil and gas exploration and production, Shipbuilding and marine structures, Wind energy (offshore wind turbine foundations), Heavy civil and structural engineering
EN 10225 S420G2+QT Shipbuilding Steel Coil Similar or Alternative Material Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10225-1 | S420G1+QT | Different chemical composition, similar mechanical properties |
| European Union | EN 10225-1 | S420ML | TMCP condition instead of QT, same yield class |
| European Union | EN 10025-6 | S460QL | Higher yield strength (460 MPa), QT condition, for structural engineering |
| USA | ASTM A572/A572M | Grade 65 | Yield ≥ 450 MPa, not specifically offshore-certified |
| International | API 2W | Grade 60 | Yield ≥ 414 MPa, for offshore tubular joints, not identical |
Notes:
Additional information:
- S420G2+QT must be welded with low-hydrogen processes and appropriate preheat/interpass temperatures to avoid cold cracking.
- Post-weld heat treatment is generally not required for thicknesses ≤ 50 mm if proper procedures are followed.
- The product is available in normalized or as-rolled parent plate, but the +QT condition is specified for the delivered state.
- Consider ordering with supplementary impact testing at temperatures lower than -40°C if required.
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