Hot-dip Galvanized Steel Sheets
Galvanized metal is steel with a coating of zinc on its surface. The zinc protects the steel in two ways: it forms a barrier against moisture and oxygen, and it acts as a sacrificial anode - because zinc is more reactive than iron, it corrodes first, even where the coating is scratched or cut.
That sacrificial action is the whole point. A painted coating fails at a scratch. A zinc coating keeps protecting the exposed steel around the scratch.
Four Processes, Very Different Results
"Galvanized" is not one thing. The process decides how thick the coating is and how long it lasts.
|
Process |
Standard |
Typical thickness |
Result |
Used for |
|
Continuous hot-dip (sheet/coil) |
EN 10346 / ASTM A653 |
Z100–Z600 g/m², 7–42 µm per side |
Smooth, uniform, spangle visible |
Roofing, cladding, purlins, appliance, duct |
|
Batch hot-dip (fabricated parts) |
ISO 1461 |
≥ 85 µm average |
Thick, rough, dull grey |
Structural steel, poles, brackets, fasteners |
|
Electro-galvanizing |
EN 10152 |
5 – 10 µm |
Very smooth, thin, paintable |
Indoor appliance panels, automotive |
|
Galvannealing (ZF) |
EN 10346 |
Similar to Z, alloyed |
Matte grey, no spangle, paints well |
Parts to be painted or welded |
How the Coating Designation Works
Under EN 10346 the letter tells you the alloy and the number tells you the total coating mass on both sides, in g/m².
|
Code |
Alloy |
Number means |
Example |
|
Z |
Zinc (≥ 99 % Zn) |
Total mass, both sides |
Z275 = 275 g/m² total, ~20 µm per side |
|
ZF |
Zinc-iron (galvannealed) |
Same |
ZF120 |
|
ZA |
Zinc-aluminium (5–12 % Al) |
Same |
ZA200 |
|
ZM |
Zinc-aluminium-magnesium |
Same |
ZM310 = 310 g/m² total |
|
AZ |
Aluminium-zinc (55 % Al, 43.4 % Zn, 1.6 % Si) |
Same |
AZ150 |
Under ASTM A653 the logic is different: G90 means 0.90 oz/ft² total on both sides, which equals about 275 g/m² - the same as Z275. Confusing the two systems is a common and expensive mistake.
How Long Does Galvanized Steel Last?
Rough indicative figures for zinc coatings in open air:
|
Environment |
Corrosion rate (µm/year) |
Life of a 20 µm coating |
|
Dry indoor |
< 0.1 |
Well over 50 years |
|
Rural / inland |
0.5 – 1.0 |
20 – 40 years |
|
Urban / industrial |
1.0 – 2.5 |
8 – 20 years |
|
Coastal / marine |
2.0 – 5.0 |
4 – 10 years |
These are indicative, not guarantees. Local pollution, salt load and wetting time all matter. In coastal and agricultural air, a ZM coating at the same mass usually lasts considerably longer because magnesium protects the cut edges.
Galvanized vs Other Options
|
Option |
Corrosion resistance |
Cost |
Best for |
|
Galvanized (Z) |
Good |
Low |
General building, the default |
|
Galvannealed (ZF) |
Good |
Low |
Painted parts |
|
Galvalume (AZ) |
Better in most atmospheres |
Low–medium |
Roofing, heat reflection |
|
Zn-Al-Mg (ZM) |
Best at cut edges |
Medium |
Solar, coastal, agricultural |
|
Stainless |
Excellent |
High |
Marine, chemical, hygiene-critical |
|
Aluminium |
Good |
Medium |
Weight-critical, no red rust |
Galvanized is usually the cheapest steel that will survive outdoors. Move up the list when cut edges, salt or a very long design life are involved.
Where Galvanized Steel Is Used
Building frames, purlins, girts and cladding
Balconies, verandas, staircases, ladders, walkways
Roofing, gutters, downpipes and flashings
HVAC ductwork and enclosures
Fences, guardrails and street furniture
Automotive bodies and underbody parts
Appliance housings
Solar mounting structures
Products Description
HOW DO SHEETS OF GALVANIZED METAL BENEFIT THE INDUSTRY?
Galvanization works by permanently binding steel and zinc together, making the base metal more rust-resistant. Different kinds of galvanization operate according to their own specific rules.
WHERE CAN YOU APPLY A SHEET OF GALVANIZED STEEL?
Sheet Galvanized steel, or zinc-coated steel sheets, is a form of regular steel that has been treated to prevent rusting. The iron in regular steel rusts when it comes into contact with moisture like rain or even the air's humidity. The rust will erode the steel until it breaks.
WHAT SHOULD YOU KNOW ABOUT GALVANIZED SHEET METAL?
Galvanized metal is a popular choice among the many kinds of sheet metal used in production. According to many steelmakers and manufacturers, galvanization is one of the finest ways to prevent corrosion.
GALVANIZED STEEL SHEET: IS IT RESISTANT TO CORROSION?
The durability of galvanized steel and its resistance to corrosion and stains makes it a go-to material for many steel artworks.
Galvanized steel is essentially steel that's been galvanized to protect it from corrosion and the elements. Virtually any experienced steel supplier will tell you that galvanization is one of the most effective tactics to protect steel from corrosion!
GNEE STEEL is committed to providing customers with galvanized steel that meets the highest possible quality requirements. It has a protective layer that prevents rust and corrosion, making it appropriate for various applications owing to its versatility.
Please visit our website or call us now for more information! Our team will be glad to assist you.
FAQS
1. What is the galvanized sheet metal used for?
Modern steel frame buildings use galvanized steel. Galvanized steel makes balconies, verandas, staircases, ladders, and walkways. Galvanized metal is best for outdoor projects.
2. Is sheet metal galvanized steel?
Galvanized metal is a popular choice among the many kinds of sheet metal used in production. According to many steelmakers and manufacturers, galvanization is one of the finest ways to prevent corrosion.
3. Where is a galvanized sheet used?
When sheet metal, such as steel, has been galvanized, it can be used for many construction purposes, including building frames, awnings, industrial walkways, and fences.
4. What is galvanized sheet metal made of?
Galvanized steel is zinc-coated carbon steel. The hot-dip process is the most widely used method of zinc coating. The carbon steel is immersed in a molten zinc bath during the hot-dip process.
5. Is galvanized steel better than steel?
Galvanized steel, in general, is more ductile and easier to deal with than stainless steel. Compared to galvanized steel, stainless is superior in strength and resistance to corrosion.
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