S690QL

S690QLAlloy Steel High Yield Structural Steel Product Overview

S690QL is a high-yield, low-alloy structural steel grade under the EN 10025-6:2004 standard, known for its exceptional strength, toughness, and weldability. With a minimum yield strength of 690 MPa (for thicknesses ≤50 mm), it is a quenched and tempered steel designed for heavy-duty applications requiring high payload capacity and energy efficiency. Typically supplied in the quenched and tempered condition (hardness ~220–260 HB), S690QL offers excellent bending properties, abrasion resistance, and performance at low temperatures (tested at -40°C, denoted by "QL"). Its high strength allows for leaner, lightweight structural designs.

Applications

S690QL is used in industries requiring high-strength, lightweight, and durable structural components:

Construction:

• Cranes, bridges, and high-rise buildings.
• Offshore structures, including oil platforms and wind turbine towers.
• Structural components for stadiums and infrastructure projects.

Heavy Machinery:

• Mining equipment, such as excavators and dump trucks.
• Material handling equipment, including conveyor systems and lifting gear.
• Yellow goods (e.g., bulldozers, loaders).

Other Uses:

• Oil and gas industry components, such as pressure vessels and pipelines.
• Shipbuilding and marine structures.
• Energy sector applications, including turbine supports and heavy-load machinery.

Chemical Composition

The chemical composition of S690QL ensures its high strength, toughness, and weldability:

• Carbon (C): Limited to ensure weldability and toughness.
• Chromium (Cr), Molybdenum (Mo), Nickel (Ni): Enhance strength, toughness, and corrosion resistance.
• Manganese (Mn): Improves hardenability and tensile strength.
• Phosphorus (P) and Sulfur (S): Kept low to minimise brittleness.
• Niobium (Nb), Vanadium (V), Titanium (Ti): Grain-refining elements for improved strength and toughness.

Supply Size

S690QL is available in various forms and sizes to meet industrial requirements:

• Round Bars:
  Diameter 16 mm to 700 mm.
• Flat Bars:
  Minimum: 10 mm thickness x 80 mm width.
  Maximum: 500 mm thickness x 2000 mm width.