Prepainted galvanized iron corrugated sheet

Galvalume® Substrate Superiority
Galvalume® (AZ coating: 55% Al, 43.4% Zn, 1.6% Si) provides the optimal substrate for pre-painted coils in corrosive environments. During hot-dipping at 600°C, the alloy forms a multi-phase microstructure: 80% Al-rich dendritic matrix providing barrier protection, and 20% Zn-Al eutectic delivering sacrificial protection. Coating weights range 60-180 g/m² (AZ60-AZ180), with Si preventing brittle Fe-Al intermetallic formation. The unique composition yields 4-6x the lifespan of galvanized steel in salt spray tests (ASTM B117: >1500hrs to red rust for AZ150 vs 240hrs for Z275).

Performance advantages are quantifiable:

• Cut Edge Protection: Galvalume® exhibits <0.3mm undercut after 1000hrs cyclic testing (ISO 14993) versus 2-5mm for GI.

• Heat Resistance: Withstands 315°C continuous service (vs 200°C for GI) without oxidation.

• Formability: AZ coatings achieve 180° bends without cracking (EN 10130).

• Paint Adhesion: Micro-roughness (Rz 1.5-2.5µm) enhances mechanical interlock.

• Sustainability: 35% lower carbon footprint than GI production.

Real-world data confirms Galvalume®-painted roofs in coastal Florida show no perforation after 30 years, while GI systems fail in 12-15 years. The alloy's galvanic current (0.1-1 µA/cm²) is optimized to protect steel without excessive zinc consumption. For architectural applications, Galvalume® substrates enable 40-year warranties when paired with PVDF topcoats.