S620QL Quenched & Tempered Steel for SSAW Pipes
S620QL Quenched & Tempered Steel for SSAW Pipes: EN 10025-6 Grade Data & Equivalents
Comprehensive material data sheet for S620QL high-strength structural steel according to EN 10025-6, covering chemical composition, mechanical and thermal properties, international equivalents, similar materials, and application guidance for spiral submerged arc welded pipes.
Thermomechanical rolling followed by quenching and tempering. Suitable for welding (SMAW, GMAW, SAW), cold and hot forming, and machining.
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S620QL Quenched & Tempered Steel for SSAW Pipes Introduction
S620QL is a high-strength quenched and tempered structural steel defined in EN 10025-6. It offers a minimum yield strength of 620 MPa and excellent low-temperature toughness (QL class: impact energy at -20°C). The steel is characterised by good weldability, cold formability, and resistance to brittle fracture. Its fine-grain microstructure, achieved by controlled rolling and subsequent quenching and tempering, ensures a balance of strength and ductility. S620QL is widely used in heavy-duty welded structures such as SSAW (spiral submerged arc welded) pipes, cranes, offshore platforms, and bridges. The 'QL' designation guarantees Charpy V-notch impact energy of 40 J (average) at -20°C for longitudinal specimens, making it suitable for low-temperature environments.
S620QL Quenched & Tempered Steel for SSAW Pipes Chemical Composition
The table below lists the maximum allowed chemical composition according to EN 10025-6 for grade S620QL. Values are for cast analysis and apply unless otherwise agreed for product analysis. The steel is fully killed and fine-grain treated. Carbon equivalent (CEV) limits are specified to ensure weldability: for thickness ≤50 mm CEV ≤0.47; 50–100 mm ≤0.51; >100–150 mm ≤0.58.
| Element | Standard Value (max %) | Remarks |
|---|---|---|
| Carbon (C) | 0.20 | |
| Silicon (Si) | 0.80 | |
| Manganese (Mn) | 1.70 | |
| Phosphorus (P) | 0.020 | |
| Sulfur (S) | 0.010 | |
| 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, total (Al) | ≥0.015 | Minimum required for grain refinement |
S620QL Quenched & Tempered Steel for SSAW Pipes Thermal & Electrical Physical Properties
These physical properties are typical for quenched and tempered structural steels similar to S620QL. They are not specified in EN 10025-6 but are based on general material data for low-alloy steel. Actual values may vary slightly with exact composition and heat treatment.
| Property | Typical Value | Unit | Test Condition |
|---|---|---|---|
| Density (ρ) | 7850 | kg/m³ | 20°C |
| Elastic Modulus (E) | 210 | GPa | 20°C |
| Shear Modulus (G) | 81 | GPa | 20°C (calculated) |
| Poisson's Ratio (ν) | 0.3 | – | 20°C |
| Thermal Expansion (α) | 12.0 × 10&supminus;&sup6; | K&supminus;¹ | 20 – 100°C |
| Thermal Conductivity (λ) | 50 | W/(m·K) | 20°C |
| Specific Heat Capacity (cp) | 460 | J/(kg·K) | 20°C |
| Electrical Resistivity (ρe) | 0.2 × 10&supminus;&sup6; | Ω·m | 20°C |
S620QL Quenched & Tempered Steel for SSAW Pipes Mechanical Properties
The mechanical properties are specified for quenched and tempered condition. Values depend on product thickness. Impact test is conducted on longitudinal Charpy V-notch specimens at -20°C (QL quality). Minimum average energy 40 J, individual minimum 27 J for thickness ≥10 mm. Bending test (180°) is optional, with mandrel diameters as listed.
| Property | Standard Requirement | Unit | Test Condition / Thickness Range |
|---|---|---|---|
| Yield Strength (ReH) | 620 | MPa | Nominal thickness ≤ 50 mm |
| Yield Strength (ReH) | 580 | MPa | 50 mm < t ≤ 100 mm |
| Yield Strength (ReH) | 560 | MPa | 100 mm < t ≤ 150 mm |
| Tensile Strength (Rm) | 700 – 890 | MPa | t ≤ 50 mm |
| Tensile Strength (Rm) | 650 – 830 | MPa | 50 mm < t ≤ 100 mm |
| Tensile Strength (Rm) | 620 – 800 | MPa | 100 mm < t ≤ 150 mm |
| Elongation (A) | 15 | % | t ≤ 50 mm (gauge length 5.65√So) |
| Elongation (A) | 15 | % | 50 mm < t ≤ 100 mm |
| Elongation (A) | 15 | % | 100 mm < t ≤ 150 mm |
| Charpy Impact (KV, longitudinal) | 40 (avg) / 27 (ind) | J | Test temperature -20°C; t ≥ 10 mm |
| Bend Test (180°) | 3t | – | t ≤ 16 mm (mandrel diameter) |
| Bend Test (180°) | 4t | – | 16 mm < t ≤ 50 mm |
| Bend Test (180°) | 5t | – | 50 mm < t ≤ 150 mm |
S620QL Quenched & Tempered Steel for SSAW Pipes Exact Equivalent Materials – Standards and Grades
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe (CEN) | EN 10025-6 | S620QL | Original standard – quenched and tempered structural steel with QL toughness class |
| International | ISO 630-6 | S620Q | ISO equivalent; comparable chemistry and mechanical properties; toughness class Q may be specified similarly |
| Germany | DIN EN 10025-6 | S620QL | German adoption of European standard |
| France | NF EN 10025-6 | S620QL | French adoption |
| United Kingdom | BS EN 10025-6 | S620QL | British adoption |
| Italy | UNI EN 10025-6 | S620QL | Italian adoption |
| Spain | UNE EN 10025-6 | S620QL | Spanish adoption |
S620QL Quenched & Tempered Steel for SSAW Pipes Application Introduction
S620QL is an ideal choice for SSAW (spiral submerged arc welded) pipes used in demanding structural and pipeline applications. Its high strength and low-temperature toughness enable lighter designs and reliable performance in harsh environments. The steel can be welded with conventional methods, but preheating and post-weld heat treatment may be necessary depending on thickness and welding procedure. Typical industries and products include:
Product Applications: Spiral submerged arc welded (SSAW) pipes for piling and structural columns, Longitudinally welded and seamless hollow sections, Heavy plates for welded beams and box girders, Offshore platform components, Crane booms and lattice structures, Pressure vessels and storage tanks
Processed into products: Pipe piles and foundation tubes, Structural pipe columns and beams, Welded pipe joints and flanges, Heavy-duty base frames and machinery housings, Truss chords and bracings
Application industries: Heavy civil engineering and construction, Offshore and marine engineering (platforms, jackets, risers), Mining and earthmoving equipment, Crane and lifting machinery, Pipeline and transmission systems, Bridge building
S620QL Quenched & Tempered Steel for SSAW Pipes Similar / Alternative Materials with Comparable Properties
| Country / Region | Standard | Grade | Remarks |
|---|---|---|---|
| Europe | EN 10025-6 | S690QL | Higher strength (690 MPa yield) similar toughness class; often used when weight saving is critical. |
| Europe | EN 10025-6 | S550Q | Lower strength (550 MPa) quenched and tempered steel; suitable for less demanding stress conditions. |
| Europe | EN 10025-6 | S460Q | Even lower strength grade; still quenched and tempered with good toughness. |
| USA | ASTM A514 / A517 | Grade S | Quenched and tempered alloy steel plate with 690 MPa yield; intended for similar structural applications. |
| Japan | JIS G 3128 | SHY685 | High yield strength steel plate with 685 MPa yield; comparable in strength and toughness. |
Notes:
- S620QL is supplied with inspection certificate 3.1 according to EN 10204. The steel is fully killed and fine-grain treated with aluminium.
- For SSAW pipe production, the parent plate properties may be affected by welding heat. Post-weld heat treatment (PWHT) or stress relieving may restore toughness in the heat-affected zone (HAZ).
- Welding consumables should match the strength and toughness level; low-hydrogen processes are recommended.
- The CEV limits stated in the chemical section are crucial for weldability assessment and must be agreed upon at ordering.
- For thicknesses above 150 mm or for transverse impact requirements, special agreements apply.
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