China Hot-Dip Galvanized Coil (GA) Suppliers - High-Quality Factory Steel Coils with Superior Weldability

Galvannealed (GA) coils are produced by leading suppliers in China through a specialized two-step process involving hot-dip zinc coating and subsequent in-line annealing at temperatures between 500–550°C. This thermal treatment allows for the diffusion of iron into the zinc layer, creating a Zn-Fe intermetallic alloy, which contains 7–15% Fe. This composition enhances the material's weldability and abrasion resistance significantly. Featuring a matte-gray finish that meets ASTM A653 Grade GA60-GA165 standards, the coils provide a phosphate-free surface that is perfect for paint adhesion. Our advanced factory utilizes a proprietary air-knife system to maintain coating weight accuracy of ±5 g/m², achieving a total range of 60–180 g/m² on both sides, complemented by a microhardness rating of 250–350 HV. Trust our top-tier China factory for high-quality Galvannealed coils that meet your industrial needs.