1. Carbon (C): max 0.22%
Carbon is the primary strengthener in steel, increasing yield and tensile strength.
However, the level is limited to max 0.22% to preserve weldability and ductility and prevent brittleness in the heat‑affected zone during welding.
Low carbon also ensures consistent formability for bending, rolling, and stamping thin sheets.
2. Manganese (Mn): max 1.25%
Manganese strongly improves strength and toughness without seriously reducing ductility.
It refines the microstructure and counteracts the brittling effect of sulfur.
Together with carbon, it provides the minimum yield strength of 345 MPa required for structural performance.
3. Silicon (Si): 0.30 – 0.65%
Silicon contributes to solid‑solution strengthening and increases strength and hardness.
It also deoxidizes the steel during production, leading to a cleaner, more uniform microstructure with better mechanical consistency.
Unlike some stronger alloys, silicon maintains sufficient ductility for fabrication.
4. Copper (Cu): min 0.20%
Copper is mainly for corrosion resistance and patina formation, but it also provides mild precipitation strengthening.
It slightly increases strength while preserving ductility and helps maintain toughness in outdoor environments.
5. Chromium (Cr): 0.40 – 0.65%
Chromium enhances strength, hardness, and wear resistance.
It stabilizes the microstructure and improves long‑term mechanical stability during outdoor weathering.
It supports uniform deformation during bending and forming, reducing cracking risk.
6. Nickel (Ni): up to 0.40%
Nickel significantly improves low‑temperature toughness and ductility.
It helps prevent brittle fracture in cold climates while maintaining high strength.
It also reduces sensitivity to welding and thermal cycles.
7. Vanadium (V): 0.02 – 0.10%
Vanadium is a microalloying element that creates fine precipitation during hot rolling.
It strongly increases yield and tensile strength without lowering ductility.
It refines grains, improving both strength and toughness simultaneously.
