AZ50 aluminum–zinc coated steel coil (commonly called Galvalume® / Al–Zn) as the balanced, cost-effective substrate for painted roofing, cladding and many fabricated parts in 2025 — it delivers a strong combination of cut-edge protection, reflectivity and long service life while typically trading at a modest premium to standard hot-dip galvanized coil; typical FOB export quotations from large Asian mills in 2025 range roughly from USD 520–820 / tonne depending on thickness, surface finish and order size.
What “AZ50” means
When you read AZ50 on a mill spec, the “AZ” denotes an aluminum–zinc alloy coating and the number (50) indicates the coating weight expressed in the ounce-per-square-foot system — AZ50 is nominally 0.50 oz/ft² total both sides (TST). In metric terms that corresponds approximately to 150 g/m² (total both sides). This is the industry shorthand used in ASTM and producer literature.
Briefly: AZ50 is not pure zinc (galvanized) — it’s an Al-Zn alloy that behaves differently at edges and under paint.
Chemistry and coating structure
The Al–Zn coating is an alloy that typically contains around 55% aluminum and 45% zinc, with a small silicon addition used to control wetting and coating structure in continuous hot-dip processes. That composition gives a metallurgical layer that combines the barrier properties of aluminum with the sacrificial protection of zinc. The result is a smooth, silvery surface with fine spangle and very good resistance to atmospheric corrosion compared with the same coating mass of pure zinc.
From a buyer’s viewpoint, that means better long-term appearance and improved performance on cut edges compared to many galvanized coatings at the same nominal mass.
How AZ coatings are made (mills’ approach)
We summarize the continuous hot-dip route used in modern mills:
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Cold-rolled steel strip is cleaned and pretreated.
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The strip runs through a molten Al–Zn bath under controlled temperature and dwell time.
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Surface conditioners (silicon additions, bath composition controls) fix coating structure and adhesion.
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After exit, the strip is air-knifed, cooled and may be passivated, oiled, or painted.
Mills produce AZ50 typically for painted coil markets (prepainted products use AZ50 as a common baseline), while slightly heavier coatings (AZ55) appear more often in unpainted or exposed applications. Mill practice—bath composition, bath temperature and air-knife settings—affect spangle, adherence and the microscopic intermetallics that control forming behavior.
Standards and specification notes
Relevant standard families and spec pointers we reference when writing purchase specs:
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ASTM A792 / A792M — common U.S. standard for aluminum-zinc coated steel sheet.
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EN 10346 — European standard for continuously hot-dip coated steel; uses coating mass in g/m² (e.g., AZ150).
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Mill product data — always request TST (total both sides) test results per A924/A924M or equivalent.
Important practical point: request coating thickness in both the oz/ft² and g/m² units to avoid unit-conversion mistakes when dealing with suppliers from different regions. AZ50 ≈ AZM150 depending on the equivalence table used by the mill.
Physical and performance characteristics
Short, practical attributes we rely on in specification decisions:
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Corrosion resistance: Al–Zn coatings give barrier plus galvanic protection; typical atmospheric resistance is several times that of equivalent mass pure zinc in many environments. This is why AZ50 is often chosen for painted applications.
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Cut-edge protection: The alloy’s behavior at edges is generally superior, reducing undercut corrosion compared to similar mass galvanized coatings.
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Formability: AZ coatings are amenable to roll forming and bending but perform differently from pure zinc on severe forming; check forming trials for tight radii.
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Paint adhesion & solar reflectance: AZ coatings commonly serve as the substrate for prepainted steel; they have very good paint adhesion and higher solar reflectance than dark zinc surfaces, which improves roof energy performance.
Typical applications (who uses AZ50)
We see AZ50 widely used in:
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Prepainted roofing and through-color cladding systems.
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Architectural panels where long life and appearance matter.
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Ductwork, appliance housings and some automotive inner panels where corrosion resistance and paintability are priorities.
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Structural sections in benign exposures — when exposure is severe, heavier coatings or alternative alloys are selected.
Use AZ55 or higher coating masses in harsher exposures or where unpainted exposure is required.
Market pricing in 2025 — what buyers are seeing
Pricing is volatile and depends on order quantity, thickness, width, surface finish (oiled / passivated / unpainted / prepainted), and shipping terms. Below we present an indicative snapshot for 2025 assembled from international mill and trading house quotations and online marketplace price indications.
Indicative global price comparison (FOB / export, USD per tonne)
| Region / Typical source | Product example | Typical FOB range (USD/tonne) — 2025 indicative |
|---|---|---|
| China — export mills / marketplaces | AZ50 Galvalume coil (various mills) | 520 – 820 |
| Southeast Asia — regional distributors | Coils slitting & local supply | 540 – 880 |
| India — domestic mills & traders | Domestic supply with export options | 500 – 760 |
| Europe — EU mills (smaller volumes) | Higher freight & duties | 680 – 1,050 |
| North America — domestic & import mix | Mill & service center processed coil | 750 – 1,200 |
Notes on the table: the China export range is anchored by multiple current online offers and factory listings that show AFI / AZ50 product ranges, while prices for other regions reflect freight, duties, and smaller lot premiums. Exact quotes will fluctuate with base steel coil prices, aluminum and zinc alloy raw material costs, and supply chain availability.
Why ranges are broad: thickness (0.12 mm vs 1.0 mm), surface finish (oiled vs passivated), slit vs full coil, paint or bare, and mill lead time all change unit pricing substantially.
Factors that strongly influence AZ50 pricing in 2025
We track several drivers that materially affect the final per-ton price:
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Base steel coil hot-rolled/cold-rolled pricing: the underlying steel raw coil cost is often the single largest component.
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Alloy component costs: aluminum and zinc prices in global commodity markets influence bath replenishment costs for Al–Zn coatings.
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Freight and logistics: after 2020, freight variability remains an important factor; ocean freight and port congestion add premiums to smaller shipments.
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Order size and value-added processing: slitting, primer/paint, and cut-to-length processing add cost. Large purchase volumes (100+ tonnes) usually unlock mill pricing discounts.
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Quality/inspection and mill reputation: certified mills with firm QA documentation typically command higher quotes but reduce rework risk.
When we negotiate, we model quotes against these factors and ask vendors to itemize the unit price into base coil + coating + processing + freight so we can compare apples to apples.
How to interpret supplier quotations
When you receive an AZ50 quote, we expect the following minimum information (and require it when we prepare a purchase order):
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Material grade (e.g., DX51D, G550) and base steel spec.
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Coating mass: AZ50 (0.50 oz/ft² TST) stated explicitly, and metric equivalent (g/m²) for clarity.
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Surface condition: passivated, oiled, lacquer sealed, or uncoated.
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Surface finish and spangle: minimized spangle / regular / spangle-free.
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Dimensions: thickness, width, ID, coil weight.
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Testing and certificates: TST results, coating mass reports, mill test certificates (MTC).
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Delivery terms: FOB mill, CIF, or DDP and estimated lead time.
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Value-added work: painting specification (if prepainted), slit tolerances, edge trim allowances.
If a quote omits coating mass units or gives only vague phrasing, we request correction immediately — unit confusion is a common source of disputes.
Quality control and inspection checklist
For AZ50 we insist on these checks before shipment or at incoming goods inspection:
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Coating mass test (TST per A924/A924M) sample certificates.
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Thickness and flatness sampling using calibrated micrometers and straightness gauges.
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Visual surface inspection for spangle, discoloration, spray marks and oil coverage.
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Adhesion and bend tests on tri-point samples to ensure forming performance.
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Cut edge corrosion evaluation where possible — compare with control samples in a salt spray pretest for qualification lots.
We recommend independent third-party inspection for larger orders and new suppliers.
Lead times, logistics and storage
Lead times vary. For standard AZ50 unpainted coil from major export mills expect 6–12 weeks typical; prepainted or custom colors can add 4–8 weeks. Spot market buys may be faster but cost more.
Storage tips we use at the warehouse:
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Keep coils dry and elevated from ground; avoid condensation.
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Rotate stock (FIFO).
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Oiled coils: maintain oil film, re-oil if storage extends beyond 3 months in humid environments.
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Avoid direct contact between coils of different finishes to prevent abrasion.
Environmental and recycling notes
Al–Zn coated steel is fully recyclable as steel; the coating is part of the steel scrap stream and is reclaimed in typical steel mill furnaces. The alloy composition does not present unusual end-of-life recycling hurdles. For sustainability reporting, some buyers include the reflective and energy-saving benefits of AZ coatings in embodied energy calculations for roofing (higher solar reflectance reduces building cooling loads). We encourage purchasers to capture mill scrap recycle certificates when green accounting is required.
Practical buying checklist (our recommended PO template items)
When we prepare a purchase order for AZ50 coil we include:
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Product name and unit (AZ50 Galvalume / Al–Zn 0.50 oz/ft² TST)
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Base steel grade and mechanical property min maxima.
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Exact dimensions, slit tolerances and coil weights.
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Surface finish and passivation instructions.
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Delivery terms, lead time, and penalty clauses for delay.
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Inspection and acceptance criteria with test report references.
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Packaging and marking requirements.
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Payment terms and any escrow/acceptance milestones.
Clear POs reduce disagreements and protect project timelines.
Common pitfalls and how we avoid them
A few recurring issues we see and our mitigations:
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Unit mismatch: oz/ft² vs g/m² — always request both measures on quotes.
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Assuming all AZ is equal: bath practice and mill QA vary; insist on mill data.
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Ignoring processing effects: slit edge quality and edge trimming tolerances matter for automated production lines.
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Not testing paint adhesion: when you receive prepainted AZ50 panels, run adhesion & bake tests.
FAQs
1) Is AZ50 the same as “Galvanized”?
No. AZ50 is an aluminum–zinc alloy coating (often called Galvalume or Al–Zn) and differs metallurgically from pure zinc hot-dip galvanizing. AZ50 combines aluminum’s barrier protection with zinc’s sacrificial behavior. This results in a different corrosion profile and appearance.
2) How thick is AZ50 in g/m²?
AZ50 is approximately 150 g/m² total both sides (the metric designation sometimes referenced as AZM150). Always ask suppliers to state both oz/ft² and g/m² to prevent confusion.
3) Does AZ50 rust faster at cut edges than galvanized?
Generally, AZ50 provides better cut-edge protection than the same nominal mass of pure zinc due to the alloy’s barrier effect and aluminum content, but local conditions and paint systems can change relative performance. For exposed unpainted edges in coastal or industrial atmospheres, consider heavier coating mass or additional edge sealer.
4) What price should I expect in 2025?
Indicative FOB export ranges in 2025 for AZ50 vary widely; current observed ranges from Chinese export listings and marketplaces are roughly USD 520–820 / tonne, with other regions carrying premiums for freight and duties. For final landed price, include processing, paint, freight and duty.
5) Should I buy prepainted AZ50 or paint locally?
If color match, warranty and uniform finish are priorities, prepainted coil from an experienced mill or dedicated coil coater is usually better. Local painting may be economical for small runs but increases variability and risk of adhesion problems. Always request paint system data sheets and accelerated weathering test results for prepainted material.
