S500QL Steel for LSAW Pipe
S500QL Steel for LSAW Pipe: EN 10025-6 Quenched & Tempered High-Strength Structural Steel
Explore S500QL quenched and tempered structural steel for LSAW pipe applications per EN 10025-6. Detailed chemical composition, mechanical and physical properties, equivalents, and typical uses.
Hot rolling followed by quenching and tempering; suitable for welding, bending, cold forming (with caution), and cutting
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S500QL Steel for LSAW Pipe Introduction
S500QL is a high-strength, fine-grain structural steel defined in EN 10025-6, supplied in the quenched and tempered condition. It offers a minimum yield strength of 500 MPa and excellent low-temperature toughness down to -50°C (denoted by the 'L' designation). This grade is particularly suited for LSAW (Longitudinal Submerged Arc Welded) pipes used in demanding structural and pressure applications. The steel exhibits good weldability with a controlled carbon equivalent value, ensuring reliability in fabricated components. Key attributes include:
- High strength-to-weight ratio for weight‑sensitive designs
- Superior notch toughness in severe cold environments
- Consistent through-thickness properties for thick sections
- Compliance with strict European regulatory standards
S500QL Steel for LSAW Pipe Chemical Composition
The chemical composition conforms to EN 10025-6:2019 for grade S500QL. All values are maximum unless a range is indicated. Fine-grain practice (Al, Nb, V, Ti) is used to achieve the required mechanical properties. The carbon equivalent value (CEV) must comply with the table based on product thickness to ensure weldability.
| Element | Standard Value (max %) | Remarks |
|---|---|---|
| Carbon (C) | ≤ 0.20 | For thickness ≤ 50 mm |
| Silicon (Si) | ≤ 0.80 | |
| Manganese (Mn) | ≤ 1.70 | |
| Phosphorus (P) | ≤ 0.025 | |
| Sulfur (S) | ≤ 0.015 | |
| Nitrogen (N) | ≤ 0.015 | |
| Boron (B) | ≤ 0.005 | |
| Chromium (Cr) | ≤ 1.50 | |
| Copper (Cu) | ≤ 0.50 | |
| Molybdenum (Mo) | ≤ 0.70 | |
| Niobium (Nb) | ≤ 0.06 | |
| Nickel (Ni) | ≤ 2.0 | |
| Titanium (Ti) | ≤ 0.05 | |
| Vanadium (V) | ≤ 0.12 | |
| Zirconium (Zr) | ≤ 0.15 | |
| Aluminium (Al) | ≥ 0.015 total | Fine-grain requirement |
| CEV (typical) | ≤ 0.51 (t ≤ 50 mm) | CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15 |
S500QL Steel for LSAW Pipe Physical Properties
The following values represent typical physical properties for quenched and tempered low‑alloy steel of the S500QL type at room temperature, unless otherwise stated. They are provided for engineering calculations and are not mandatory requirements of the standard.
| Property | Typical Value | Unit | Test Condition / Remarks |
|---|---|---|---|
| Density (ρ) | 7.85 | g/cm³ | Room temperature |
| Modulus of elasticity (E) | 210 | GPa | Room temperature |
| Shear modulus (G) | 81 | GPa | Room temperature |
| Poisson's ratio (ν) | 0.3 | dimensionless | |
| Thermal expansion coefficient (α) | 12.0 | 10⁻⁶/K | 20°C to 100°C |
| Thermal expansion coefficient (α) | 12.8 | 10⁻⁶/K | 20°C to 200°C |
| Thermal conductivity (λ) | 45 | W/(m·K) | Room temperature |
| Specific heat capacity (cp) | 460 | J/(kg·K) | Room temperature |
| Electrical resistivity (ρe) | 0.22 | Ω·mm²/m | Room temperature |
S500QL Steel for LSAW Pipe Mechanical Properties
Properties are based on EN 10025-6 for flat products of thickness ≤50 mm. For thicker sections, a reduction in mechanical values may apply. Impact testing is performed at -50°C on longitudinal Charpy V‑notch specimens. The material exhibits high strength with ductile behavior and excellent toughness.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| Yield strength (ReH) | ≥ 500 | MPa | t ≤ 50 mm, transverse |
| Tensile strength (Rm) | 590 – 770 | MPa | t ≤ 50 mm, transverse |
| Elongation (A5) | ≥ 17 | % | Proportional gauge length 5.65√S₀, transverse |
| Impact energy (KV2) | ≥ 27 | J | -50°C, longitudinal |
| Impact energy (KV2) | ≥ 27 | J | -50°C, transverse (optional) |
| Bend test (mandrel diameter) | 3t (t ≤ 16 mm); 4t (16 < t ≤ 50 mm) | 180° bend, no cracks |
S500QL Steel for LSAW Pipe Direct Equivalent Standards and Replaceable Designations
| Country/Region | Standard | Designation | Remarks |
|---|---|---|---|
| Europe | EN 10025-6:2019 | S500QL | Base standard |
| International | ISO 4950-2:1995 | E500QL | High yield strength flat steel; technically equivalent |
| Germany | DIN EN 10025-6 | S500QL | Identical adoption of EN |
| France | NF EN 10025-6 | S500QL | Identical adoption of EN |
| United Kingdom | BS EN 10025-6 | S500QL | Identical adoption of EN |
| Italy | UNI EN 10025-6 | S500QL | Identical adoption of EN |
S500QL Steel for LSAW Pipe Application Introduction
S500QL steel is engineered for load‑bearing structures that demand high strength, low‑temperature toughness, and reliable weldability. Its typical application in LSAW pipes exploits the material's homogeneous through‑thickness properties and excellent fatigue resistance. Key industries and products include:
Product Applications: Longitudinal Submerged Arc Welded (LSAW) pipes up to X80 strength level, Heavy structural sections and box columns, Fabricated plate girders and box beams, Welded pipe for sour service (with additional HIC testing)
Processed into products: LSAW pipe mill: oil trunklines, gas transmission pipelines, Jack-up rig legs and spud cans, Offshore wind turbine foundation substructures (monopiles, jackets), Hydraulic cylinder bodies and high‑pressure tubing, Heavy‑duty crane booms and lattice structures, Piping for abrasive slurries in mining
Application industries: Oil & Gas (offshore and onshore pipeline systems), Renewable Energy (wind turbine towers, monopiles, transition pieces), Shipbuilding and Marine (offshore platform substructures, crane arms), Heavy Construction (bridges, stadiums, high‑rise buildings), Mining and Earthmoving (dump bodies, excavator booms), Pressure vessels and Penstocks (hydropower)
S500QL Steel for LSAW Pipe Similar or Alternative Material Grades
| Country/Region | Standard | Designation | Remarks |
|---|---|---|---|
| Europe | EN 10025-6 | S500Q | Same strength, minimum impact temperature -20°C (instead of -50°C) |
| Europe | EN 10025-6 | S690QL | Higher strength (690 MPa min. yield), similar low-temperature toughness |
| USA | ASTM A514/A517 | Grade B, F, H, Q | Quenched and tempered alloy steel; yield ≥ 690 MPa; higher strength but similar application; careful substitution required |
| Germany | DIN EN 10025-6 | S460QL | Lower strength (460 MPa min. yield), same -50°C toughness, often used for less demanding structures |
| World | ISO 4950-2 | E550QL | Yield 550 MPa, -50°C, slightly higher strength alternative |
Notes:
S500QL may be supplied with enhanced properties such as improved through‑thickness characteristics (Z‑quality per EN 10164), and can be delivered with a +N (normalized) or +QT (quenched and tempered) condition, though the standard stipulates only the QT delivery. For LSAW pipe manufacturing, the steel plate is cold‑formed or crimped, welded longitudinally, and dimensionally expanded. Post‑weld heat treatment is usually not required for thicknesses ≤30 mm, but a qualified welding procedure (WPS) must be followed. Supplementary testing for sour service (HIC/SSC) can be performed according to NACE MR0175 when specified.
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