SS400, compliant with JIS G3101, is a premium carbon structural steel coil with 400-510MPa tensile strength and ≥245MPa yield strength. Its optimized 0.12-0.20% carbon content ensures excellent weldability, formability, and impact toughness. Ideal for construction, bridges, machinery, and automotive frames, it offers cost-effective performance with strict chemical/mechanical controls. Surface options include hot-rolled, pickled, oiled, or galvanized finishes. With balanced strength-ductility ratio and reliable quality, SS400 delivers superior value for structural applications requiring durability and processability.