Q: What's the difference between the glossy (B) and matte (D) finishes of SPCC?
A: B-side is precision ground on the rolls, Ra≤0.4μm, used for exterior parts; D-side is shot-peened on the rolls, Ra0.8–1.6μm, used for structural parts, and is less expensive.
Q: Why is SPCC prone to rusting?
A: It contains no alloying elements, and the cold-rolled surface is dense but lacks a protective layer. It easily forms iron oxide when exposed to water/oxygen/salt spray, requiring rust prevention treatment.
Q: What are common rust prevention solutions for SPCC?
A: Short-term: Rust-preventive oil/vapor phase rust-preventive paper; Medium-term: Electro-galvanizing/hot-dip galvanizing, phosphating + passivation; Long-term: Powder coating, electrophoresis, painting.
Q: How to package SPCC for rust prevention during export by sea?
A: Single-layer film → desiccant → sealed PE bag → iron frame + moisture-proof paper → steel strapping, with rust prevention label and humidity indicator card.
Q: How to treat pitting/scratches on the SPCC surface? A: Minor: Grinding + Polishing; Major: Replace roll or downgrade; Source control: Optimize rolling and packaging to avoid scratches from foreign objects.