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What is ASTM 588 Grade A? steel plate

ASTM 588 Grade A is a ​​high-strength low-alloy structural steel​ standardized by ASTM International, renowned for its ​​superior atmospheric corrosion resistance​ and commonly known as ​​weathering steel​ or ​​Corten steel​. Below is a detailed technical breakdown:

​​1. Core Characteristics​

​​Atmospheric Corrosion Resistance​: Forms a protective rust layer (patina) when exposed to weather, reducing corrosion rates by 2–4 times compared to carbon steel  .

​​High Strength​: Minimum yield strength of ​​50 ksi (345 MPa)​ for thickness ≤4 inches, decreasing slightly for thicker sections  .

​​Weldability & Fabrication​: Suitable for welded, bolted, or riveted structures (e.g., bridges, buildings)  .

​​2. Chemical Composition (%)​ 

​​Element​ ​​Grade A Range​ ​​Role in Performance​
Carbon (C) ≤0.19 Balances strength and weldability
Manganese (Mn) 0.80–1.25 Enhances toughness and hardenability
Chromium (Cr) 0.40–0.65 Key for corrosion-resistant patina formation
Copper (Cu) 0.25–0.40 Improves atmospheric corrosion resistance
Vanadium (V) 0.02–0.10 Refines grain structure for strength
Phosphorus (P) ≤0.04 Controlled to avoid brittleness
Sulfur (S) ≤0.05 Minimized to reduce hot cracking

​​3. Mechanical Properties​ 

​​Thickness Range​ ​​Yield Strength (min)​ ​​Tensile Strength (min)​ ​​Elongation (min, %)​
≤4 inches (≤101.6 mm) 50 ksi (345 MPa) 70 ksi (485 MPa) 21% (in 2")
>4–5 inches 46 ksi (317 MPa) 67 ksi (462 MPa) 21%
>5–8 inches 42 ksi (290 MPa) 63 ksi (435 MPa) 21%

​​4. Primary Applications​

​​Bridges & Buildings​: Ideal for exposed structural components (e.g., girders, façades) due to corrosion resistance  .

​​Engineering Machinery​: Used in mining equipment (excavators, cranes), transmission poles, and rail tracks  .

​​Containers & Cladding​: Storage tanks and architectural cladding in industrial environments  .

​​5. Standards & Certifications​

​​ASTM Standard​: Governed by ​​ASTM A588/A588M​ (latest version: A588/A588M-19)  .

​​Equivalent Grades​:

​​ASME SA588 Grade A​ (identical to ASTM A588)  .

​​European Equivalent​: S355J2G1W (EN 10025-5)  .

​​Testing Compliance​: Requires mill test reports (MTRs) confirming chemical/mechanical properties  .

6. Key Considerations​

​​Thickness Limit​: Applicable only for ​​≤8 inches (200 mm)​  .

​​Welding Protocols​: Must follow ASTM A6/A6M guidelines to avoid cracking  .

​​Unpainted Use​: Optimal for bare exposure but requires proper ventilation to avoid moisture trapping  .

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