What is the S690QL standard?

What is the S690QL standard?

S690QL is a European standard, ultra-high-strength structural steel (EN 10025-6) known for its excellent strength-to-weight ratio, toughness, and weldability, achieved through quenching and tempering (Q+L), making it ideal for lighter, more efficient designs in cranes, lifting equipment, and heavy structures. Its designation signifies a minimum yield strength of 690 MPa, reducing slightly with thickness, and it offers good formability, abrasion resistance, and low-temperature impact toughness, allowing for reduced material use and increased payload capacity.

S690QL is an ultra-high-strength structural steel produced in compliance with the EN 10025-6 technical standard. The "S" signifies its primary use in structural applications, while "690" denotes its exceptional minimum yield strength of 690 MPa. The material is supplied as steel plate that has undergone a quenched and tempered heat treatment process, which is essential for achieving its high-performance characteristics.

This grade of steel is characterized by its excellent mechanical properties, including high resistance to abrasion and fatigue, as well as good impact resistance. Despite its extreme strength, S690QL maintains excellent formability, weldability, and toughness. Its good bending and welding properties make it a versatile choice for complex fabrication in industrial environments, even for structures operating in cold climates.

S690QL is ideal for heavy-duty applications where lighter designs and high performance are needed.

Key Characteristics:

S (Structural): Indicates it's a steel for structural purposes.

690: Denotes a minimum yield strength of 690 Megapascals (MPa).

QL (Quenched & Low-temperature): Shows it's heat-treated (quenched and tempered) for high strength and excellent toughness, even at low temperatures.

High Strength-to-Weight Ratio: Allows for lighter structures, increasing payload in mobile applications.

Toughness: Resists impact and fatigue, with good performance down to -40°C or lower.

Weldability: Low carbon content and careful production ensure good weldability, though preheating is often recommended.

Common Applications:

-Cranes and lifting equipment

-Heavy-duty transport and armored vehicles

-Bridges and large steel structures

-Mining and construction machinery

-Energy sector components

What welding rod for S690QL?

For welding S690QL high-strength steel, you need a matching high-strength filler metal, typically an ER110S-G (AWS A5.28) solid wire or equivalent flux-cored wire (like G 69 4 M21 Mn3Ni1CrMo) for GMAW/FCAW, or matching low-hydrogen stick electrodes (like E11018-G/H8), to maintain mechanical properties, often requiring controlled heat input and sometimes preheating to manage cracking risks, especially with higher carbon equivalents.

Is S690QL steel hard to drill ?

Yes, drilling S690QL (a high-strength quenched and tempered steel) is harder than standard mild steel because of its high yield strength (690 MPa) and hardness, requiring specialized tools like carbide or cobalt bits, slower speeds, and proper cooling to prevent bit wear and maintain material integrity, but it's a standard fabrication process if done correctly.

What is the P number of S690QL?

The P (Phosphorus) number (or rather, the maximum percentage) for S690QL steel is typically 0.025%, though some specifications allow for slightly lower (e.g., 0.020%) or slightly higher (e.g., max 0.022%) limits, as it's a controlled minor element in this high-strength, quenched, and tempered structural steel grade.

Equivalent grades of steel S690QL (1.8928)

S690QL - Chemical Composition

S690QL - Mechanical Properties

S690QL - V Notch Impact Testing

1What is S690QL standard?

S690QL is a European standard (EN 10025-6) for ultra-high-strength structural steel, known for its excellent combination of high yield strength (minimum 690 MPa), toughness, and weldability, achieved through a quenched and tempered (Q+T) heat treatment. It's used in demanding applications like cranes, heavy machinery, bridges, and wind turbines, allowing for lighter, more efficient designs with increased payload capacity.

2Is S690QL carbon steel?

Yes, S690QL is considered a high-strength structural steel that contains carbon, but it's more accurately described as a low-alloy, high-yield (HY) steel due to controlled additions of other elements (like Manganese, Silicon, Chromium, Molybdenum) for enhanced properties, making it stronger and tougher than plain carbon steel, especially for demanding, cold-temperature applications.

3What is the maximum allowable stress value for S690QL ?

The maximum allowable stress for S690QL steel isn't a single fixed number but is defined by its minimum yield strength, which is 690 MPa (MegaPascals) for thicknesses up to 50mm, decreasing slightly for thicker plates (e.g., 650 MPa for 50-100mm). The "allowable stress" in design is often this yield strength, though a safety factor is applied, and the actual tensile strength (ultimate strength) is higher, around 770-940 MPa, depending on thickness.

4What temperature is S690QL?

S690QL is a high-yield structural steel known for its toughness at low temperatures, specifically tested to provide at least 27-30 Joules of impact energy at -40°C, ensuring excellent performance in cold conditions, unlike S690Q which is tested at 0°C. Its name indicates a minimum yield strength of 690 MPa (S for Structural, 690 for strength, Q for Quenched & Tempered, L for Low-temperature impact toughness).

5What is S690QL high speed steel?

S690QL is an ultra-high-strength structural steel, not high-speed steel, known for its exceptional yield strength (minimum 690 MPa) achieved through quenching and tempering (the 'Q' and 'L' in its name), making it ideal for lighter, stronger structures in cranes, lifting equipment, bridges, and heavy machinery, offering excellent weldability, toughness, and low-temperature performance for demanding heavy-duty applications.

6What is the composition of S690QL?

S690QL is a high-strength structural steel (EN 10025-6) known for its minimum 690 MPa yield strength after quenching and tempering, with key alloying elements like Carbon, Manganese, Silicon, Chromium, Molybdenum, Nickel, and microalloying elements (Nb, Ti, V, Zr) that enhance strength and toughness, making it ideal for heavy machinery, cranes, and construction. Its composition includes typical limits for C (0.2%), Si (0.8%), Mn (1.7%), P (0.025%), S (0.015%), with additions of Cr (1.5%), Mo (0.7%), Ni (2%), Nb (0.06%), Ti (0.05%), V (0.12%), and Zr (0.15%).

7What are the primary advantages of S690QL?

S690QL's primary advantages are its exceptional strength (690 MPa yield), enabling lighter, more efficient designs; excellent toughness, even at low temperatures, for harsh environments; superb weldability and formability for complex fabrication; and high resistance to fatigue and abrasion, making it ideal for heavy-duty, demanding applications like construction, cranes, and offshore structures.

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