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Zn-Al-Mg Steel Coil
Zinc Aluminum Magnesium Coated Steel Coil
ZAM coated coil with a self-healing cut edge and less coating weight per year of life
Zn-Al-Mg steel coil is a coated steel coil whose coating is mainly zinc with aluminum, magnesium and a small amount of silicon added. It is specified by roll formers, building product makers and structural fabricators who need outdoor corrosion life without moving to stainless steel, and it is also sold as AZM coating steel coil, zinc aluminum magnesium steel coil and aluminum zinc magnesium steel coil. Because the magnesium and aluminum in the coating re-form a protective film over a scratch or a sheared edge, cut and punched parts stay protected without the edge touch-up that ordinary galvanized parts need. Coil is supplied in 0.1mm-300mm thickness with coating mass from Z40 through Z350.
- Product Name — Zn-Al-Mg Steel Coil
- Also Known As — AZM coating steel coil zinc aluminum magnesium steel coil aluminum zinc magnesium steel coil
- Standards — BS EN GB AiSi ASTM DIN JIS
- Material — Q195 Q215 Q235B Q345B S235JR S355JR SS400 SS490 SM400 SM490 G350 G550
- Base Grades — G250 G350 G450 G550 A36 SS400 S275jr S235
Why It Is Specified
Key Benefits of Zn-Al-Mg Steel Coil
Corrosion Resistance Stated at 10 to 20 Times Galvanized
Aluminum, magnesium and silicon in the coating raise the corrosion inhibition effect so the coil reaches better corrosion resistance with less coating adhesion than ordinary galvanized product. The stated figure is 10 to 20 times that of hot-dip galvanized steel coil.
Self Healing at Scratches and Cut Edges
At a scratch or cut, dissolved magnesium aluminum and zinc form a dense film of zinc hydroxide, alkaline zinc chloride and magnesium hydroxide over the exposed steel. That film separates the corrosive medium from the bare edge and stops further corrosion spreading.
Alkali Resistance That Can Replace Stainless
The coating has excellent alkali resistance and corrosion resistance and can replace stainless steel in individual fields, which changes the cost basis of a part that was specified in stainless for environment reasons alone.
Less Coating Weight for the Same Protection
Better corrosion resistance is achieved with less coating adhesion, so a lighter coating mass can be specified where a heavier zinc layer would otherwise be needed.
Good Scratch Resistance in Handling and Forming
Scratch resistance is a stated property of the coating, which matters on coil that goes through roll forming lines, stacking and site handling before it is installed.
Paintable Like Galvalume
Paintability is similar to that of galvalume steel coil, so the coil can be painted to improve appearance and extend service life where a color finish is specified.
Problems It Solves
What This Material Removes From Your Process
Rust Starting at Sheared and Punched Edges
On ordinary galvanized parts the cut edge is the first place to corrode and usually needs painting after fabrication. The dissolved magnesium aluminum and zinc at the cut form a protective film over the exposed base, so the edge protects itself.
Heavy Zinc Coatings Cracking in Forming
Specifying more zinc to buy corrosion life makes the coating harder to form. This coil reaches better corrosion resistance with less coating adhesion, so the forming behaviour does not have to be traded away.
Stainless Steel Cost on Parts That Only Need Corrosion Life
Where stainless was chosen purely for an alkaline or aggressive environment, the excellent alkali resistance of this coating means it can replace stainless steel in individual fields.
Short Replacement Cycles on Outdoor Structures
With corrosion resistance stated at 10 to 20 times hot-dip galvanized coil and a self-healing cut section, the service life of formed components is extended rather than the structure being rebuilt.
Mixed Grade and Coating Callouts Across One Project
Base grades from G250 through G550 plus Q195 to Q345B and S235JR to S355JR are supplied against BS, EN, GB, AiSi, ASTM, DIN and JIS callouts from one coil order.
Application Scenarios
Where It Is Used
Roofing and Wall Cladding Profiles
Roll formed roof and wall sheets in outdoor exposure where the cut ends and fixing holes are the usual corrosion starting points.
Solar Mounting and Support Structures
Purlins, rails and brackets for ground mount and roof mount arrays where parts are punched and sheared before installation.
Agricultural and Livestock Buildings
Structures exposed to alkaline and ammonia-bearing atmospheres where the alkali resistance of the coating is the reason for specifying it.
Cable Tray Ducting and Enclosures
Punched and folded components where every hole exposes a bare edge that ordinary galvanized coil would need protected.
Highway and Guardrail Components
Outdoor structural parts in snow, ice and rain where a longer corrosion life reduces the replacement cycle.
Air Conditioning and Equipment Housings
Formed and welded housings that see outdoor condensation and where a painted finish is applied over the coating.
Who It Is For
Buyers Who Specify This Product
- Roll forming plants buying coil for roof wall and purlin profiles
- Solar structure manufacturers specifying coated coil for punched mounting rails
- Building product fabricators replacing hot-dip galvanized coil in outdoor exposure
- Design engineers evaluating a replacement for stainless steel in alkaline environments
- Cable management and enclosure makers whose parts are punched and sheared before assembly
- Coil importers and stockists supplying coated coil to regional forming shops
Technical Data
Specifications and Technical Features
Values below come from the product data published by Shandong Tianyu Metal Products. Confirm the exact grade and size against your order.
| Product Name | Zn-Al-Mg Steel Coil |
|---|---|
| Also Known As | AZM coating steel coil zinc aluminum magnesium steel coil aluminum zinc magnesium steel coil |
| Standards | BS EN GB AiSi ASTM DIN JIS |
| Material | Q195 Q215 Q235B Q345B S235JR S355JR SS400 SS490 SM400 SM490 G350 G550 |
| Base Grades | G250 G350 G450 G550 A36 SS400 S275jr S235 |
| Coating Mass | G20 G30 G40 G60 G90 Z40 Z60 Z80 Z100 Z120 Z150 Z275 Z350 |
| Coating Composition | Zinc with aluminum magnesium and a small amount of silicon |
| Thickness | 0.1mm-300mm or customized as required |
| Width | 1500mm-2000m or customized as required |
| Paintability | Similar to galvalume steel coil |
| Weldability | Weldable with a reasonable process |
| Place of Origin | China |
Technical Features
- Coating of zinc with aluminum magnesium and a small amount of silicon
- Coating mass G20 G30 G40 G60 G90 Z40 Z60 Z80 Z100 Z120 Z150 Z275 and Z350
- Base grades G250 G350 G450 G550 A36 SS400 S275jr and S235
- Structural grades Q195 Q215 Q235B Q345B S235JR S355JR SS400 SS490 SM400 SM490 G350 and G550
- Thickness 0.1mm-300mm or customized as required
- Standards BS EN GB AiSi ASTM DIN and JIS
- Paintability similar to galvalume steel coil
- Weldable with a reasonable process and repairable with Zn-Al paint at the weld
Materials
- Cold rolled or hot rolled steel base in structural grades from Q195 to Q345B and S235JR to S355JR
- High strength base grades G250 G350 G450 and G550
- Zinc aluminum magnesium coating with a small amount of silicon
- Zn-Al paint for repairing the coating at welded areas
Manufacturing
How It Is Made and Processed
Base coil preparation and cleaning before coating
Hot dip coating in a bath of zinc with aluminum magnesium and silicon
Coating mass control to the ordered Z or G designation
Coil decoiling to the ordered width
Cutting to length where sheet is ordered instead of coil
Optional painting where a color finish is required
Coil packing and strapping for export loading
Quality Control
Checks Before It Ships
- Coating mass verified against the ordered G or Z designation
- Base grade confirmed against the ordered structural designation
- Thickness checked across the 0.1mm-300mm range before decoiling
- Coil surface inspected for coating defects before packing
- Edge condition checked after decoiling to the ordered width
Customization
What We Can Change on Your Order
- Thickness and width customized as required outside the standard coil sizes
- Coating mass selected from Z40 up to Z350 for the exposure the part will see
- Base grade selected from structural grades through to G550 for formed strength
- Painted finish applied where appearance and added service life are needed
- Coil slit to strip width or cut to length as sheet
- Grade quoted to BS EN GB AiSi ASTM DIN or JIS designations
Comparison
Zn-Al-Mg Steel Coil Against the Alternatives
| Hot-dip galvanized steel coil | Corrosion resistance is stated at 10 to 20 times that of hot-dip galvanized coil and the cut edge forms its own protective film instead of rusting first. |
|---|---|
| Zinc aluminum coated coil | Adding magnesium and silicon to the zinc aluminum coating improves the corrosion inhibition effect further, so less coating adhesion gives more protection. |
| Stainless steel sheet | The excellent alkali resistance of the coating means it can replace stainless steel in individual fields at coated steel cost, where corrosion life is the only reason stainless was specified. |
| Hot rolled and cold rolled uncoated sheet | Welding performance is slightly worse than uncoated sheet but achievable with a reasonable process, and the coating gives outdoor corrosion life that bare sheet does not have. |
Use Guide
Specifying Handling and Welding Notes
- Match the coating mass to the exposure rather than defaulting to the heaviest Z designation since more protection is reached with less coating adhesion
- Weld with a reasonable process and repair the welded area with Zn-Al paint to bring it back to a coating similar to the original
- Leave sheared edges and punched holes unpainted where the self-healing behaviour of the coating is being relied on
- Confirm the base grade separately from the coating mass because strength and corrosion life are specified independently
- Store coils dry and stacked off the ground to avoid white rust from trapped condensation
- Send the profile drawing with the order so strip width and thickness are set for your roll former
Questions Buyers Ask
Zn-Al-Mg Steel Coil FAQ
How much better is the corrosion resistance than plain galvanized coil?
The stated figure is 10 to 20 times that of hot-dip galvanized steel coil, reached with less coating adhesion because of the aluminum magnesium and silicon in the coating.
Do we have to paint the cut edges after fabrication?
At a scratch or cut, the dissolved magnesium aluminum and zinc form a dense film of zinc hydroxide, alkaline zinc chloride and magnesium hydroxide over the exposed steel, which prevents further corrosion at that edge.
What thickness and width can you supply?
Thickness is 0.1mm-300mm and width is 1500mm-2000m, and both can be customized as required for your line.
Can this coil be welded?
Yes. Welding performance is slightly worse than hot-rolled and cold-rolled sheet but with a reasonable process the joint reaches its due strength, and the welded area can be repaired with Zn-Al paint.
Can it be painted after coating?
Paintability is similar to that of galvalume steel coil, so it can be painted to improve appearance and further extend service life.
Which coating mass should we order?
Coating mass runs from G20 and Z40 up to Z275 and Z350. Tell us the environment and the expected service life and we will confirm a designation with the base grade.
Is it a genuine alternative to stainless steel?
The coating has excellent alkali resistance and corrosion resistance and can replace stainless steel in individual fields. Whether it fits your duty depends on the medium and temperature, so send the application details.
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