When selecting a corrosion-resistant coating for SUS630 laminated steel plate, the core principle is “match the service environment + do not affect the substrate performance + consider constructability,” taking into account the steel’s corrosion resistance and the application scenario.
1. Core selection principles
The coating must be compatible with the SUS630 passivation layer, free of strong acids or bases to avoid damaging the surface protection layer.
Prefer coatings with high adhesion and low volatility to prevent peeling or cracking during long-term use.
The coating should not affect subsequent processing or assembly; for example, welding areas require weldable coatings or should be left uncoated.

2. Selection based on service environment
(1) Indoor dry environment (light corrosion protection)
Recommended coatings: stainless steel-specific silane passivation layer, transparent fluorocarbon clear coat.
Advantages: thin application is sufficient, does not affect the steel’s appearance or dimensional accuracy, strong adhesion, enhances passivation layer stability, and is cost-effective.
Applicable scenarios: internal equipment components, indoor shelving, dry workshop equipment.
(2) Humid/outdoor environment (medium corrosion protection)
Recommended coatings: water-based polyurethane coating, epoxy zinc-rich primer + polyurethane topcoat (two-layer system).
Advantages: strong weather resistance, protects against rain and humidity, zinc-rich primer enhances cathodic protection, and the double-layer system provides longer-lasting protection.
Applicable scenarios: outdoor brackets, humid workshop equipment, outdoor assembled components.
(3) Marine/salt spray/industrial areas (heavy corrosion protection)
Recommended coatings: fluorocarbon coating, polyurea coating, ceramic composite coating.
Advantages: resistant to salt spray, chemical exposure (mild acids and bases, high-chloride environments), UV and aging resistance, service life up to 5–10 years.
Applicable scenarios: marine platform components, salt-spray environment equipment, chemical plant corrosive environments.

3. Key performance parameters
Adhesion: cross-cut test ≥1 grade (ASTM D3359), to prevent coating peeling.
Corrosion resistance: neutral salt spray test ≥1000 hours (heavy environment) or ≥500 hours (medium environment) without significant corrosion.
Temperature resistance: must match the service temperature (SUS630 recommended ≤600℃), coating temperature resistance should exceed the maximum service temperature by 50℃ to avoid decomposition.
Constructability: prefer room-temperature curing coatings to avoid affecting the plate’s age-hardening effect, suitable for brushing or spraying.

4. Selection precautions
Avoid coatings containing chromates: poor environmental performance, may react with copper or nickel in SUS630, reducing corrosion resistance.
Handling of welded areas: if the coating covers welded areas, use weldable coatings or weld first and then touch up to avoid decomposition from high temperatures.
Thickness control: single-layer thickness 50–100 μm, double-layer total thickness 100–150 μm; too thick may affect assembly accuracy, too thin is insufficient for protection.

5. Optional functional preferences
Self-cleaning: reduces dust and contaminant adhesion, lowering maintenance frequency (e.g., fluorocarbon coating).
Transparent coating: preserves the steel’s original appearance and allows visual inspection of the surface condition (e.g., silane passivation layer, transparent clear coat).