What is the difference between s690ql and hardox 400 ?

What is the difference between s690ql and hardox 400 ?

S690QL is a high-yield structural steel with excellent weldability and formability for general construction, while Hardox 400 is a premium wear-resistant (AR) steel, significantly harder (370-430 HBW) and tougher for extreme abrasion/impact in heavy machinery, making S690QL better for load-bearing structures and Hardox 400 for protective linings. The main difference lies in their primary function: S690QL for structural strength and Hardox 400 for wear protection, with Hardox 400 prioritizing hardness over typical S690QL yield strength.

S690QL is a high yield strength structural steel grade produced in accordance with EN 10025-6. This steel is designed to provide an excellent combination of high strength, toughness, abrasion resistance and weldability

The combination of good availability and pricing and high strength combined with ease of fabrication has made S690QL steel plate a popular grade for both mobile applications such as cranes and lifting equipment and fixed steel structures. The high strength nature of this steel means that structures can be designed lighter and for mobile application this means increase in payload and operational efficiency.

Key Characteristics:

High Strength: A minimum yield strength of 690 MPa (Megapascals) for common thicknesses.

Quenched & Tempered (Q&T): A heat treatment process that enhances its mechanical properties, especially strength and toughness.

Excellent Toughness: Good impact resistance, even in cold conditions, making it suitable for harsh environments.

Good Weldability: Can be readily fabricated and assembled with appropriate welding procedures.

Lightweight Design: Enables engineers to create structures that are lighter, leading to better payload capacity and fuel efficiency.

Common Applications:

Cranes & Lifting Gear: Booms, jibs, and load-bearing components for increased reach and capacity.

Heavy Machinery: Components in mobile equipment.

Construction: Structural elements in bridges, buildings, and other heavy-duty structures.

Offshore Structures: Due to its toughness and corrosion resistance.

Grade Designation

S: Stands for Structural Steel.

690: Indicates the minimum yield strength in MPa.

QL: Denotes that the steel is quenched (Q) and tempered (L, often indicating low-temperature toughness).

What 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).

What 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.

Is 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.

Chemical composition % of steel S690QL (1.8928): EN 10025-6-2004

Mechanical properties of steel S690QL (1.8928)

S690QL - V Notch Impact Testing

Equivalent grades of steel S690QL (1.8928)

1What 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.

2What 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.

3What 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%).

4Is 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.

5What 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.

6What is the effective use of high strength S690QL steel in construction?

S690QL steel's effective use in construction leverages its high strength (690 MPa yield) and toughness for lighter, stronger, and more efficient designs in heavily loaded structures like bridges, high-rise buildings, wind turbines, and offshore platforms. It reduces self-weight, minimizing foundation loads and material use, while its excellent weldability, formability, and resistance to fatigue and abrasion suit demanding applications, including heavy machinery and seismic zones.

7What is S690QL grade steel?

S690QL is a high-yield strength, quenched and tempered structural steel (EN 10025 standard) known for its excellent strength (minimum 690 MPa yield), toughness, weldability, and low-temperature performance, enabling lighter, more efficient designs in heavy-duty applications like cranes, mobile equipment, bridges, and construction machinery. The "S" means structural, "690" is the yield strength in MPa, and "QL" signifies high quality and toughness, especially at low temperatures.

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