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What Is ASTM A653? Galvanized Steel Coil Specification
This article provides a technical interpretation of ASTM A653 requirements for galvanized steel coil, a specification commonly referenced by steel manufacturers, fabricators, and engineering teams worldwide.
Such standardized technical frameworks are frequently used by steel suppliers, including Hengze Steel, in product documentation, quality control systems, and international trade contracts.
Table of Contents
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1️⃣ Overview of ASTM A653 for Galvanized Steel Coil1️⃣ Overview of ASTM A653 for Galvanized Steel Coil
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2️⃣ ASTM A653 Steel Grades and Designations2️⃣ ASTM A653 Steel Grades and Designations
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3️⃣ Chemical Composition Requirements by Grade3️⃣ Chemical Composition Requirements by Grade
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4️⃣ Mechanical Property Requirements4️⃣ Mechanical Property Requirements
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5️⃣ Zinc Coating Designations and Coating Weight5️⃣ Zinc Coating Designations and Coating Weight
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6️⃣ Thickness Range and Thickness Tolerance in ASTM A6536️⃣ Thickness Range and Thickness Tolerance in ASTM A653
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7️⃣ Surface Condition and Finish Options7️⃣ Surface Condition and Finish Options
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8️⃣ How to Specify ASTM A653 Galvanized Steel Coil8️⃣ How to Specify ASTM A653 Galvanized Steel Coil
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ConclusionConclusion
1️⃣ Overview of ASTM A653 for Galvanized Steel Coil
ASTM A653 / A653M is the primary American standard governing hot-dip zinc-coated (galvanized) and zinc-iron alloy-coated (galvannealed) carbon steel sheet and coil.
The specification defines critical parameters including:
Base steel grade classification
Chemical composition limits
Mechanical performance requirements
Zinc coating weight and designation
Dimensional and tolerance practices
ASTM A653 galvanized steel coil is widely used in construction systems, structural framing, roofing, appliances, HVAC equipment, and general fabrication, making it one of the most commonly specified coated steel standards in global procurement.
2️⃣ ASTM A653 Steel Grades and Designations
ASTM A653 classifies steel primarily by intended application and forming capability, rather than by coating type alone.
2.1 Commercial and Forming Grades
CS (Commercial Steel) – General-purpose applications
FS (Forming Steel) – Improved cold-forming performance
DDS (Deep Drawing Steel) – High ductility for complex shapes
EDDS (Extra Deep Drawing Steel) – Extremely demanding forming operations
These grades are commonly used where bendability, stretch forming, and surface quality are critical.
2.2 Structural Steel Grades
SS Grade 33
SS Grade 37
SS Grade 40
SS Grade 50 (Class 1 / Class 2)
Structural grades are defined by minimum yield strength, making them suitable for load-bearing and framing applications.
3️⃣ Chemical Composition Requirements by Grade
ASTM A653 controls chemical composition to ensure a balance between strength, formability, weldability, and galvanizing performance.
Exact limits vary by grade, but typical maximum values are as follows:
| Element | Typical Maximum (%) |
|---|---|
| Carbon (C) | 0.10 – 0.25 |
| Manganese (Mn) | 0.60 – 1.35 |
| Phosphorus (P) | ≤ 0.035 – 0.10 |
| Sulfur (S) | ≤ 0.035 – 0.04 |
| Silicon (Si) | ≤ 0.03 – 0.50 |
For DDS and EDDS grades, carbon and phosphorus levels are usually more tightly controlled to achieve superior elongation and forming performance.
4️⃣ Mechanical Property Requirements
ASTM A653 specifies minimum mechanical properties, typically verified through tensile testing.
The requirements depend on steel grade and thickness.
Typical Mechanical Property Ranges
| Grade | Yield Strength (MPa) Min | Tensile Strength (MPa) Min | Elongation (%) Min |
|---|---|---|---|
| CS Type A | ~170 | — | ≥20 |
| CS Type B | ~205 | — | ≥20 |
| FS Type A | ~170 | — | ≥26 |
| DDS | ~140 | — | ≥32 |
| SS Grade 33 | ~230 | ≥310 | ≥20 |
| SS Grade 37 | ~255 | ≥360 | ≥18 |
| SS Grade 40 | ~275 | ≥380 | ≥16 |
| SS Grade 50 | ~340 | ≥450 | ≥12 |
These mechanical limits ensure predictable forming behavior for commercial grades and reliable load capacity for structural grades.
5️⃣ Zinc Coating Designations and Coating Weight
ASTM A653 uses standardized coating designations based on the total zinc coating weight on both sides of the steel sheet.
Common Galvanized Coating Designations
| Coating Designation | Total Zinc Weight (oz/ft²) | Approx. g/m² |
|---|---|---|
| G30 | 0.30 | ~90 |
| G40 | 0.40 | ~120 |
| G60 | 0.60 | ~180 |
| G90 | 0.90 | ~275 |
| G115 | 1.15 | ~350 |
| G140 | 1.40 | ~425 |
6️⃣ Thickness Range and Thickness Tolerance in ASTM A653
6.1 Typical Thickness Range (Industry Practice)
ASTM A653 galvanized steel coils are commonly supplied in the following ranges:
Thickness: approximately 0.12 mm to 4.0 mm
Common commercial range: 0.30 – 3.00 mm
Coil inner diameter (ID): 508 mm or 610 mm
6.2 Thickness Tolerance
ASTM A653 does not provide a single mandatory thickness tolerance table.
Instead, thickness tolerance is:
Based on cold-rolled base steel tolerance practices
Defined by purchase order, contract, or supplier agreement
Typical industry practice includes:
±1.0% of nominal thickness, or
Explicit limits such as ±0.05 mm at 1.00 mm thickness
For engineering clarity, thickness tolerance should always be clearly stated in procurement and technical specifications, rather than assumed.
7️⃣ Surface Condition and Finish Options
ASTM A653 galvanized steel coil may be supplied with various surface characteristics:
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Spangle finish: regular, minimized, or zero spangle
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Surface treatment:
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Chromate passivation
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Oiled or dry
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Anti-fingerprint (by agreement)
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These options influence paint adhesion, temporary corrosion resistance, and downstream processing performance such as roll forming or stamping.
In practical supply scenarios, steel producers such as Hengze Steel typically recommend surface treatments based on the final application and storage conditions.
8️⃣ How to Specify ASTM A653 Galvanized Steel Coil
A complete and technically sound ASTM A653 specification should include:
Standard reference: ASTM A653 / A653M
Steel grade: CS, FS, DDS, or SS (33–50)
Mechanical property requirements
Chemical composition limits (if required)
Zinc coating designation (e.g., G60, G90)
Thickness, width, and thickness tolerance
Surface finish and treatment
Coil ID and coil weight range
Clear specification reduces quality disputes, inspection issues, and performance risks.
Conclusion
ASTM A653 provides a comprehensive and globally accepted framework for galvanized steel coil, defining:
Steel grade classification
Chemical composition control
Mechanical performance requirements
Zinc coating weight systems
Dimensional and tolerance practices
Correct application of these parameters is essential for engineering design, material selection, procurement accuracy, and long-term service performance.
For steel manufacturers and suppliers involved in international markets—such as Hengze Steel—ASTM A653 remains a core technical reference for galvanized steel coil production and supply.
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