1. How Plate Thickness Influences Patina Formation Speed
Thin plates (≤3 mm, mostly cold-rolled): Have faster heat dissipation. In outdoor environments with alternating hot and cold conditions, the surface temperature changes rapidly, accelerating the dry-wet cycle that promotes oxide layer densification. The patina formation speed is slightly faster (natural patina matures in 4–6 months in humid areas).
Thick plates (≥10 mm, mostly hot-rolled): Have slower heat dissipation and more stable surface temperatures. The dry-wet cycle effect is weakened, so the initial oxidation rate is slower. Natural patina maturation takes 6–12 months in the same humid environment.
Thick weathering steel plates are almost always hot-rolled, with a rougher surface and natural mill scale (iron oxide layer). This rough texture provides more nucleation sites for patina formation, partially offsetting the slowdown caused by heat dissipation.
Thin plates are often cold-rolled, with a smoother surface and fewer nucleation sites. Even though heat dissipation is faster, the smooth surface slows down the adhesion of moisture and oxygen, balancing the overall patina speed.
2. Key Clarification: Thickness vs. Core Influencing Factors
In high-humidity, rainy regions, even thick plates (20 mm) can form mature patina in 8 months; in arid regions, thin plates (2 mm) may take 12+ months to develop uniform patina.
Alloy composition (Cu, Cr, Ni content) is the most fundamental factor-without sufficient alloy elements, neither thin nor thick plates can form a dense protective patina.
3. Optimization Measures for Patina Formation on Plates of Different Thicknesses
