What is EN10025-6 S690QL?
EN 10025-6 S690QL is a high strength steel plate, quenched and tempered structural steel that offers exceptional mechanical properties. It’s specifically designed for use in demanding applications where high strength and excellent toughness are required. This steel grade is commonly used in the construction, heavy transportation, and manufacturing sectors.
Chemical Composition
The chemical composition of EN 10025-6 S690QL steel is carefully balanced to provide optimal performance. The key elements include:
- Carbon (C): 0.20% max
- Manganese (Mn): 1.70% max
- Silicon (Si): 0.80% max
- Phosphorus (P): 0.025% max
- Sulfur (S): 0.015% max
- Chromium (Cr): 1.50% max
- Nickel (Ni): 2.00% max
- Molybdenum (Mo): 0.70% max
- Vanadium (V): 0.12% max
- Titanium (Ti): 0.05% max
- Boron (B): 0.005% max
- Copper (Cu): 0.50% max
- Nitrogen (N): 0.015% max
- Zirconium (Zr): 0.15% max
- Iron (Fe): Balance
Mechanical Properties
EN 10025-6 S690QL steel is renowned for its impressive mechanical properties, making it an ideal choice for high-stress applications. These properties include:
| Property | Value |
|---|---|
| Yield Strength | 690 MPa |
| Tensile Strength | 770-940 MPa |
| Elongation | 14% min |
| Impact Toughness | 50 J @ 0°C, 40 J @ -20°C |
| Hardness | 190-220 HBW |
| Modulus of Elasticity | 210 GPa |
| Density | 7.85 g/cm³ |
| Poisson’s Ratio | 0.3 |
Key Features and Benefits
High Strength: The primary advantage of EN 10025-6 S690QL steel is its high yield strength, which allows for the construction of lighter and stronger structures. This feature is particularly beneficial in applications where weight reduction is essential without compromising strength.
Excellent Toughness: The steel maintains excellent toughness even at low temperatures, making it suitable for use in harsh and cold environments. This toughness ensures that the steel can withstand heavy loads and impacts without fracturing.
Good Weldability: Despite its high strength, S690QL steel maintains good weldability. It can be welded using standard welding techniques, which simplifies fabrication processes. The low carbon content also reduces the risk of weld cracking.
Enhanced Durability: The steel’s enhanced durability and resistance to wear and tear make it an excellent choice for applications requiring long-lasting performance. Its resistance to abrasion and impact ensures that structures made from S690QL steel have a longer service life.
Corrosion Resistance: While not as corrosion-resistant as stainless steel, S690QL steel offers good resistance to atmospheric corrosion. This makes it suitable for outdoor and marine environments where it is exposed to the elements.
Applications
EN 10025-6 S690QL steel is used in a variety of industries and applications due to its unique properties. Some common applications include:
Construction: This steel is widely used in the construction of bridges, high-rise buildings, and other structures that require high-strength materials. Its high yield strength allows for the construction of lighter structures without compromising stability and safety.
Heavy Machinery: S690QL steel is used in the manufacture of heavy machinery and equipment such as cranes, bulldozers, and excavators. The high strength and toughness of the steel ensure that these machines can handle heavy loads and harsh operating conditions.
Transportation: In the transportation industry, S690QL steel is used in the production of heavy-duty vehicles, trailers, and railway components. The reduced weight of the structures made from this steel leads to increased fuel efficiency and lower emissions.
Offshore and Marine: The good toughness and resistance to corrosion make S690QL steel suitable for offshore and marine applications. It is used in the construction of offshore platforms, ships, and other structures exposed to seawater.
Energy Sector: This steel grade is used in the energy sector for the construction of wind towers, pipelines, and pressure vessels. The high strength and durability of S690QL steel ensure the safe and efficient operation of these structures.
Fabrication and Welding
Fabrication of EN 10025-6 S690QL steel involves standard methods such as cutting, drilling, and bending. Due to its high strength, it is essential to use appropriate tools and techniques to avoid damaging the material.
Welding: Welding S690QL steel requires careful attention to preheat and interpass temperatures to prevent hydrogen-induced cracking. The steel can be welded using common methods such as MMA (Manual Metal Arc), MAG (Metal Active Gas), and TIG (Tungsten Inert Gas) welding. Post-weld heat treatment is usually not necessary, but it is crucial to follow the recommended welding procedures to maintain the steel’s properties.
Heat Treatment
The mechanical properties of EN 10025-6 S690QL steel are achieved through a quenching and tempering process. This heat treatment involves heating the steel to a high temperature (above 900°C) followed by rapid cooling (quenching) in water or oil. The steel is then reheated to a lower temperature (tempering) to enhance its toughness and reduce brittleness.
Conclusion
EN 10025-6 S690QL steel is a versatile and high-performance material that offers numerous benefits for structural and engineering applications. Its combination of high strength, good weldability, and excellent toughness makes it an ideal choice for demanding projects. Whether in construction, heavy machinery, transportation, offshore, or energy sectors, S690QL steel delivers reliable performance and long-lasting durability.
By understanding the properties and advantages of EN 10025-6 S690QL steel, industries can leverage its potential to create stronger, lighter, and more efficient structures. Its ability to withstand harsh conditions and heavy loads ensures that it remains a preferred material for critical applications worldwide.