Q690B, compliant with GB/T 1591-2008, is a high-strength low-alloy structural steel coil with yield strength ≥690MPa and tensile strength 770-940MPa. Its optimized chemistry (C≤0.18%, Nb/V/Ti microalloying) ensures excellent weldability, toughness, and fatigue resistance. Ideal for heavy machinery, bridges, wind towers, and pressure vessels, it reduces structural weight by 30% compared to conventional steel while maintaining safety. Surface options include hot-rolled, pickled, or galvanized finishes. With strict dimensional tolerance and reliable quality control, Q690B delivers cost-effective performance for demanding engineering applications requiring high strength-to-weight ratio and durability.