EN10025-6 S500QL Steel
EN10025-6 S500QL Steel: High-Strength Quenched & Tempered Structural Steel Coil
In-depth material data for S500QL steel coil under EN10025-6. Includes chemical composition, mechanical and physical properties, international equivalents, and applications for high-strength structural engineering.
Hot Rolling, Quenching and Tempering (Q+T), Cold Forming, Welding, Machining
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EN10025-6 S500QL Steel Introduction
EN10025-6 S500QL is a high-yield-strength, quenched and tempered structural steel grade with a minimum yield strength of 500 MPa. It belongs to the low-alloy steel family and is characterized by excellent weldability, good low-temperature impact toughness, and high resistance to brittle fracture. The 'Q' in its designation signifies 'Quenched and Tempered,' while 'L' indicates it has been tested for impact energy at a low temperature of -50 °C. This steel is primarily supplied in coil form and is designed for heavily loaded structures where weight reduction without compromising strength is critical. Its balanced chemical composition, with micro-alloying elements like niobium, vanadium, and titanium, ensures a fine-grained microstructure and superior mechanical properties after heat treatment.
EN10025-6 S500QL Steel Chemical Composition
The chemical composition of S500QL steel is precisely controlled to achieve high strength and excellent toughness after quenching and tempering. Key elements like Manganese (Mn) and Silicon (Si) contribute to deoxidation and solid solution strengthening. Micro-alloying elements such as Niobium (Nb), Vanadium (V), and Titanium (Ti) are critical for grain refinement and precipitation strengthening. Phosphorus (P) and Sulfur (S) are kept at very low levels to ensure high purity, good weldability, and superior low-temperature toughness.
| Element | Standard Value (Max unless range given) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.20% | Key strength and hardenability element |
| Silicon (Si) | ≤ 0.80% | Deoxidizer; contributes to strength |
| Manganese (Mn) | ≤ 1.70% | Enhances strength and toughness |
| Phosphorus (P) | ≤ 0.020% | Impurity; controlled for toughness |
| Sulfur (S) | ≤ 0.010% | Impurity; critical for formability and weldability |
| Chromium (Cr) | ≤ 1.50% | Improves hardenability and corrosion resistance |
| Nickel (Ni) | ≤ 2.0% | Enhances low-temperature toughness |
| Molybdenum (Mo) | ≤ 0.70% | Increases hardenability and high-temperature strength |
| Copper (Cu) | ≤ 0.50% | Provides limited atmospheric corrosion resistance |
| Niobium (Nb) | ≤ 0.06% | Grain refiner, precipitation strengthener |
| Vanadium (V) | ≤ 0.12% | Precipitation strengthener |
| Titanium (Ti) | ≤ 0.05% | Grain refiner, binds free nitrogen |
| Nitrogen (N) | ≤ 0.015% | Controlled to prevent aging |
| Boron (B) | ≤ 0.005% | Powerful hardenability enhancer |
EN10025-6 S500QL Steel Thermal and Electrical Physical Properties
The following physical properties are typical for quenched and tempered low-alloy structural steels and are suitable for engineering calculations. Properties such as thermal conductivity and thermal expansion are essential for designing welded structures and components subjected to thermal cycling. The elastic moduli are comparable to other constructional steels. These values may exhibit minor variations depending on the exact tempering temperature and microstructural condition.
| Property | Standard Requirement Value (Typical) | Unit | Test Condition / Reference |
|---|---|---|---|
| Density (ρ) | ~ 7.85 | g/cm³ | At 20 °C |
| Elastic Modulus (E) | ~ 210 | GPa | At 20 °C |
| Shear Modulus (G) | ~ 81 | GPa | At 20 °C |
| Poisson's Ratio (ν) | ~ 0.3 | - | At 20 °C |
| Thermal Expansion Coefficient (α) | 12.0 | 10⁻⁶/K | 20–100 °C |
| Thermal Expansion Coefficient (α) | 12.5 | 10⁻⁶/K | 20–200 °C |
| Thermal Expansion Coefficient (α) | 13.5 | 10⁻⁶/K | 20–400 °C |
| Thermal Conductivity (λ) | ~ 40 – 45 | W/(m·K) | At 20 °C |
| Specific Heat Capacity | ~ 460 | J/(kg·K) | At 20 °C |
| Electrical Resistivity (ρ_e) | ~ 0.20 – 0.25 | Ω·mm²/m | At 20 °C |
EN10025-6 S500QL Steel Mechanical Properties
The mechanical properties are guaranteed in the quenched and tempered condition. The S500QL grade is distinguished by its high minimum yield strength of 500 MPa and specified minimum impact energy at -50 °C. The tensile strength range provides a consistent margin above the yield point. The elongation values indicate good ductility for cold forming operations. Impact test values (KV2) are measured on longitudinal Charpy V-notch specimens, ensuring reliable performance in extremely cold environments.
| Property | Standard Requirement (Nominal Thickness ≤ 50 mm) | Unit | Test Condition / Specification |
|---|---|---|---|
| Minimum Yield Strength (ReH) | 500 | MPa | Nominal thickness 3–50 mm; t ≤ 50 mm |
| Minimum Yield Strength (ReH) | 480 | MPa | Nominal thickness 50 < t ≤ 100 mm |
| Minimum Yield Strength (ReH) | 440 | MPa | Nominal thickness 100 < t ≤ 150 mm |
| Tensile Strength (Rm) | 590 – 770 | MPa | Nominal thickness 3–50 mm |
| Tensile Strength (Rm) | 590 – 770 | MPa | Nominal thickness 50 < t ≤ 100 mm |
| Tensile Strength (Rm) | 590 – 770 | MPa | Nominal thickness 100 < t ≤ 150 mm |
| Minimum Elongation (A5) | 17 | % | Longitudinal; t ≤ 50 mm |
| Minimum Elongation (A5) | 17 | % | Longitudinal; 50 mm < t ≤ 100 mm |
| Minimum Elongation (A5) | 17 | % | Longitudinal; 100 mm < t ≤ 150 mm |
| Minimum Impact Energy (KV2, Longitudinal) | 30 | J | Test temperature: -50 °C |
| Minimum Bending Radius | 3t (t = thickness) | - | Bend test: 180° mandrel bend, t ≤ 16 mm |
EN10025-6 S500QL Steel Fully Equivalent Material Standards and Replaceable Grade Recommendations
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| International (ISO) | ISO 4950-2 | E550DD | Same concept; 550 MPa yield class, low-temperature toughness |
| China | GB/T 16270 | Q500E | Closest equivalent; impact tested at -40 °C vs -50 °C for S500QL |
| Germany (withdrawn) | DIN EN 10025-6 | S500QL | Direct adoption of European standard |
| United Kingdom | BS EN 10025-6 | S500QL | Direct adoption of European standard |
EN10025-6 S500QL Steel Application Introduction
S500QL steel is engineered for structural applications demanding a superior strength-to-weight ratio under severe loading and climatic conditions. Its guaranteed impact toughness at -50 °C makes it a primary choice for safety-critical components in arctic environments. The material is designed for excellent weldability, which is essential for on-site fabrication of large structures. Key applications include:
Product Applications: Telescopic crane booms and outriggers, Heavy-duty tipper truck and semi-trailer chassis, Offshore platform modules and flare booms, Steel bridge girders and box sections, Tunnel boring machine (TBM) cutting heads, Concrete pump truck booms, High-pressure hydraulic piping
Processed into products: Flanges and webs for welded plate girders, Load-carrying pins and lugs, Welded tubular joints and nodes, Reinforcement pads and load distribution plates, Bearing housings and slewing rings, Armor plate components
Application industries: Mobile Crane Manufacturing, Heavy Transport and Trailer Engineering, Offshore and Marine Construction, Bridge Building, Mining and Earthmoving Machinery, Pressure Vessel and Penstock Construction, Military and Defense Vehicle Armor
EN10025-6 S500QL Steel Recommendations for Similar/Comparable Substitute Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| European Union | EN 10025-6 | S500Q | Same strength level, but minimum impact energy tested at -20 °C, not -50 °C. Suitable for less demanding low-temp conditions. |
| European Union | EN 10025-6 | S550QL | Higher minimum yield strength (550 MPa). Slight premium in cost and potential trade-off in formability. |
| USA | ASTM A514 / A514M | Grade S | Quenched & tempered high-strength plate. Yield strength is 690 MPa for t ≤ 65 mm, significantly higher than S500QL. Requires careful welding procedure review. |
| China | GB/T 16270 | Q550E | Higher strength class (550 MPa yield). Good low-temperature toughness, comparable to S550QL in the EN system. |
Notes:
Welding Considerations: S500QL has excellent weldability with a low carbon equivalent value (CEV typically ≤ 0.52%). Preheating and interpass temperature control are essential following the recommendations of EN 1011-2 to avoid hydrogen-induced cold cracking. Low-hydrogen welding consumables should be used. The heat input should be controlled to preserve the quenched and tempered microstructure in the heat-affected zone (HAZ). Cold Forming: The steel can be bent and press-braked to tight radii. For thicknesses up to 16 mm, a minimum bending radius of 3 times the thickness (3t) is generally safe for ambient temperature forming. Subsequent stress-relief annealing is generally not recommended as it may reduce the base material strength.
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