EN 10025-6 S620QL is a high-strength, high-toughness, and easily weldable quenched and tempered structural steel plate. Its core advantage lies in balancing load-bearing capacity with low-temperature impact resistance, making it a key material for achieving "lightweight and high-reliability" designs in heavy engineering fields.

Standard and Grade Designation

1. Standard: EN 10025-6

The full title is "Hot-rolled structural steels - Part 6: Technical delivery conditions for flat products of high yield strength structural steels in the quenched and tempered condition," which is a unified European standard for high-strength structural steel.



2. Grade: S620QL

S: Structural steel.

620: The specified minimum yield strength is 620MPa.

Q: The delivery condition is Quenched and Tempered.

L: Low temperature impact toughness (Tested at -60°C or -40°C, depending on the sub-grade and thickness).

The chemical composition of S690QL ensures hardenability, strength, and toughness. EN 10025-6 specifies the limits for key elements, with the following typical ranges:

Carbon Equivalent of S620QL High Strength Steel Plate

* The carbon equivalent value varies depending on the thickness.For detailed information, please contact us for inquiries.

* Carbon equivalent (CEV) is calculated using the International Institute of Welding (IIW) formula:

CEV = C + Mn/6 + (Cr+Mo+V)/5 + (Ni+Cu)/15

* The mechanical properties of S620QL high-strength structural steel plate vary with thickness.

S620QL high-strength structural steel plate is known for its "high strength, high toughness, and good weldability," making it primarily suitable for structural components that endure high loads, complex stresses, or low-temperature environments. Typical applications include:

Construction Machinery: Crane booms, excavator buckets, bulldozer frames, etc., where high strength reduces structural weight and enhances load-bearing capacity.

Mining Machinery: Dump truck bodies, crusher frames, etc., designed to withstand impact and abrasion.

Pressure Vessels and Storage Tanks: Shells of high-pressure vessels, heads of large storage tanks (requires supporting welding procedure qualification).

Bridges and Buildings: Load-bearing components of long-span bridges, steel core columns of high-rise buildings.

Special Vehicles: Protective armor or load-bearing structures for military vehicles and armored cars.

Delivery Conditions

S620QL is typically delivered in the quenched and tempered condition, with surface treatments such as sandblasting and painting available as required.

Weldability

EN 10025-6 S620QL high-strength steel plate is weldable. However, due to its high carbon and alloy element content, preheating is required before welding (typically at 100-150°C), and stress relief heat treatment (such as tempering at 200-300°C) is necessary after welding to avoid welding cracks. It is recommended to use low-hydrogen electrodes or welding wires with matching strength.

The Differences Between Grades Within The Same Series

Procurement and Acceptance

Material Test Certificate (MTC): The steel mill must provide a certificate compliant with EN 10204 Type 3.1 or 3.2, clearly stating mechanical properties, chemical composition, and non-destructive testing results (such as UT inspection).

Thickness Tolerance: Executed according to EN 10029, typically ±0.5mm (for thickness ≤10mm) or ±1.0mm (for thickness >10mm). Special tolerances must be negotiated in advance.

Surface Quality: Default is "as-rolled" surface. If anti-corrosion pretreatment (such as shot blasting or painting) is required, it must be specified in the order.

Non-Destructive Testing: For critical structures (e.g., wind power, bridges), it is recommended to require sheet-by-sheet UT inspection (compliant with EN 10160 Class 2 or higher) to detect internal defects.

Summary

EN 10025-6 S620QL steel plate is a high-strength, high-toughness, and easily weldable quenched and tempered structural steel plate. Its core advantage lies in balancing load-bearing capacity with low-temperature impact resistance, making it a key material for achieving "lightweight and high-reliability" designs in heavy engineering fields.