Weathering steel
After folding, its surface forms a
dense, stable oxide patina (mainly composed of FeOOH and Fe₃O₄) that tightly adheres to the substrate. This patina acts as a natural protective layer, blocking the infiltration of water, oxygen, and corrosive media (e.g., salt spray in coastal areas) into the folded edge crevices. Even if the surface is slightly scratched during bending, the patina can self-repair through oxidation, avoiding localized rusting.
No need for painting or galvanizing post-processing, which simplifies the production workflow.
Ordinary carbon steel
Lacks inherent corrosion resistance; folded edges are prone to rusting at crevices (a high-risk area for moisture accumulation). Must be coated with paint or electroplated, and the coating is easy to peel off at the folded edge due to stress concentration, leading to rapid rusting.
Galvanized steel
The zinc coating is easily cracked or peeled off during folding, exposing the base steel to corrosion. The zinc layer at the folded edge is thin and cannot be repaired after damage, resulting in galvanic corrosion between zinc and steel.
Weathering steel
It has high ductility and low yield ratio (e.g., ASTM A588 grade has a yield strength of ≥345MPa and elongation of ≥20%). Folding can be completed with a small bend radius (1–5× plate thickness) without micro-cracks or brittle fractures, even for plates 4–6mm thick. The folded edge maintains strong load-bearing capacity, suitable for load-bearing components such as flower box frames and signage brackets.
Residual stress after folding is low, and there is no significant deformation during long-term outdoor use.
Stainless steel (e.g., 304/316)
Although corrosion-resistant, it has high hardness and poor ductility compared to weathering steel. Folding requires a larger bend radius (3–8× plate thickness), and it is easy to cause springback (difficult to maintain the folding angle accurately). The high cost makes it uneconomical for large-area applications.
Aluminum alloy
Lightweight but low strength; folded edges are prone to deformation under wind load or external impact, not suitable for heavy-duty components. The oxide film is thin and easy to damage during processing.
Weathering steel
The rust patina forms uniformly on the folded edge surface and the flat area, presenting a consistent reddish-brown retro texture. The folded edge's three-dimensional lines are highlighted against the rust color, enhancing the industrial and artistic sense of products (e.g., screens, luminous signs).
The aesthetic effect will become more natural with time, without the need for frequent maintenance to maintain appearance.
Galvanized steel/painted steel
The coating at the folded edge is prone to peeling and chalking, resulting in color differences between the folded part and the flat part. The appearance is monotonous and lacks texture, making it difficult to meet the design requirements of high-end decorative products.
Weathering steel
No need for regular coating maintenance (unlike painted steel that requires repainting every 2–3 years). The one-time investment in processing is slightly higher than ordinary carbon steel, but the life-cycle cost is 30%–50% lower than galvanized steel or stainless steel in outdoor environments.
The folding process is compatible with conventional cold bending equipment, without the need for specialized tools, reducing production costs.
