What are the different classifications of galvanized steel sheets and their corresponding advantages and characteristics?

I. Classification by Galvanizing Process
1. Hot-Dip Galvanized Steel Sheet (GI)
Process: Steel sheet immersed in molten zinc at high temperature, forming a zinc-iron alloy layer + pure zinc layer
Advantages
Exceptional adhesion; zinc coating resists peeling during bending and stamping
Superior corrosion resistance with extended service life
High cost-effectiveness and broadest application range
Applications: Ductwork, computer cases, home appliances, construction, hardware fittings
2. Electrogalvanized Steel Sheet (EG / Electrolytic Galvanized)
Process: Electrolytic deposition of a thin zinc layer onto steel surface
Advantages
Exceptionally smooth, bright, and refined surface finish
Uniform thickness, ideal for high-precision stamping and coating
Disadvantages: Thin zinc layer, inferior corrosion resistance compared to hot-dip galvanizing
Applications: Computer chassis, appliance internals, automotive interior components
II. Classification by Zinc Coating Weight (Corrosion Resistance Grade)
Higher numbers indicate thicker zinc layers and stronger corrosion resistance
Z80 / Z100: Thin zinc coating, for indoor components and light corrosion protection
Z180 / Z275: Standard general-purpose, suitable for outdoor use
Z350 / Z450: Heavy zinc coating, for high humidity, coastal environments, and heavy-duty corrosion protection
III. Classification by Surface Structure
1. Standard Zinc Flower (Regular Zinc Flower)
Distinct surface pattern
Low cost, high versatility
Suitable for structural components with minimal aesthetic requirements
2. Fine Zinc Flower
Dense, fine pattern
Superior appearance, easy to spray
Commonly used for home appliances and enclosures
3. Zinc-Free (ZF)
Mirror-like uniform surface
Aesthetic, easy to clean, easy to post-process
Preferred for high-end appliances, purification panels, and enclosures
IV. Classification by Post-Processing
1. Chromate Passivation
Prevents oxidation and white rust
Most conventional, low cost
2. Anti-Fingerprint Treatment (AFP)
Resists fingerprint marks
Specialized for electronics, appliances, and chassis
3. Oiled / Uncoated
Oiled: Scratch and rust resistance, facilitates processing
Uncoated: Clean finish, suitable for direct spraying and clean environments
V. Classification by Base Material
1. Cold-Rolled Steel Sheet Galvanized
Flat surface, high precision
Suitable for stamping, bending, home appliances
2. Hot-rolled substrate galvanized
High strength, thick gauge
Used for structural components, steel pipes, steel structures
VI. Classification by Strength Grade
Standard Strength (CQ/DQ): Good bendability, general purpose
Deep Drawing Grade (DDQ): Capable of deep drawing, home appliance housings
High Strength (HSS): Load-bearing, structural components