What chemical elements are critical for Q355B angle steel performance?

Q355B angle steel (per GB/T 706) relies on key chemical elements to achieve its mechanical properties: 1) Carbon (C, ≤0.24%): Enhances strength but must be controlled to avoid reducing weldability-excess C causes brittleness during welding; 2) Manganese (Mn, ≤1.60%): Improves tensile strength and toughness, acting as a "strengthening agent" without significant loss of ductility; 3) Silicon (Si, ≤0.55%): Boosts yield strength by forming solid solutions with iron; 4) Phosphorus (P, ≤0.035%) and Sulfur (S, ≤0.035%): Harmful impurities-P causes cold brittleness (cracking at low temperatures), while S leads to hot brittleness (fracture during hot rolling); 5) Trace elements (V, Nb, Ti): Added in small amounts (≤0.15%) to refine grain structure, improving impact toughness (critical for use in -20℃ environments).