Products Description
S690QL and S890QL are high-strength quenched and tempered (Q&T) structural steels that comply with the EN 10025-6 standard, specifically designed for engineering structures requiring high load-bearing capacity and reliability.
- S690QL is a versatile high-yield steel suitable for most heavy-duty engineering projects. It has a minimum yield strength of 690 MPa, a tensile strength ranging from 770 to 940 MPa, impact toughness ≥ 30 J at –40°C, and elongation ≥ 14%, with a thickness range of 12–60 mm. With these properties, S690QL provides reliable support for bridges, lifting equipment, heavy machinery, and steel structures.
- S890QL is an ultra-high-strength steel with a minimum yield strength of 890 MPa and a tensile strength of 930–1080 MPa. It maintains impact
toughness ≥ 30 J at –40°C, with elongation ≥ 12% and a thickness range of 12–50 mm. S890QL is designed for extreme loads and demanding conditions, making it ideal for critical load-bearing components, crane booms, railway tracks, and high-strength steel structures.
Both grades offer good weldability and can be welded using MAG, TIG, SMAW, or SAW methods. Typical welding parameters include a heat input of 1.5–2.5 kJ/mm, maximum diffusible hydrogen content ≤ 5 ml/100 g, and interpass temperature ≤ 150°C. Preheating (50–100°C) is recommended for thick plate welding, especially for S890QL.
Mechanical Properties
| Property | S690QL | S890QL | Notes |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 690 MPa | ≥ 890 MPa | S890QL has higher strength, suitable for extreme load applications |
| Tensile Strength (Rm) | 770–940 MPa | 930–1080 MPa | Higher strength enables lighter structures with greater load capacity |
| Impact Energy (KV, –40°C) | ≥ 30 J | ≥ 30 J | Low-temperature toughness is similar, ensuring safety in cold environments |
| Elongation (A5) | ≥ 14% | ≥ 12% | S890QL has higher strength, so elongation is slightly lower |
| Thickness Range | 12–60 mm | 12–50 mm | Typical supply range |
| Delivery Condition | Quenched & Tempered | Quenched & Tempered |
Welding and Fabrication
S690QL: Good weldability; welding can be done without preheating if hydrogen content is controlled. Suitable for MAG, TIG, SMAW, and SAW welding methods.
S890QL: Weldable, but requires strict control of heat input and interpass temperature; preheating is recommended for thick plates. Machining is more demanding and requires high-strength tooling and higher processing force.
Typical Welding Parameters (Reference)
Heat Input: 1.5–2.5 kJ/mm
Maximum Diffusible Hydrogen Content: ≤ 5 ml/100 g
Interpass Temperature: ≤ 150°C
Preheating for Thick Plates: 50–100°C (recommended for S890QL)
Applications
S690QL
S690QL high-yield structural steel is widely used in engineering projects that require high load-bearing capacity and durability. Typical applications include the frames and load-bearing components of heavy transport vehicles, providing enhanced load efficiency and safety; various machinery manufacturing, such as mining equipment, cranes, and large industrial machines, where S690QL can withstand impact and wear, extending service life; steel construction projects, including bridges, factories, and warehouses, where it offers stable structural support while enabling lightweight design due to its high strength; and lifting equipment, such as cranes, forklifts, and booms, ensuring safe and reliable operation under heavy loads.
S890QL
S890QL ultra-high-strength steel is designed for extreme loads and demanding conditions, suitable for critical components subjected to high stress. It is commonly used in heavy-duty machinery, including large crane booms and key parts of construction equipment, as well as high-speed train rails that must withstand high-speed and high-pressure operation.
In bridges and specialized engineering structures, S890QL is used for critical load-bearing components to ensure stability and safety under extreme loads. Additionally, it is widely applied in special engineering projects, such as high-strength steel structures, elevated lifting platforms, and offshore engineering equipment, maintaining excellent performance even in harsh environments.
