Gamma layer
Gamma layer is the innermost alloy layer formed during the hot-dip galvanizing process, playing a foundational role in the overall coating's adhesion.
Formation and Function
Gamma layer is a zinc-iron alloy that forms immediately adjacent to the base steel substrate. It is the first layer to nucleate when the molten zinc reacts with the iron.
- Composition: It is the most iron-rich of all the alloy layers, typically containing around 25% iron by weight.
- Structure and Thickness: The Gamma layer is extremely thin and has a compact, crystalline structure. Because it is the closest layer to the steel, it forms a metallurgical bond, which is the primary reason the zinc coating adheres so strongly to the pipe surface.
- Adhesion: The strength of the galvanizing bond—its resistance to impact and flaking—is directly dependent on the quality and continuity of this thin Gamma layer.
If the galvanizing temperature or immersion time is not precisely controlled, the formation of the Gamma layer can be compromised, leading to poor adhesion and premature coating failure.