ASTM A572 Grade 65: Extra-High-Strength Structural Steel
ASTM A572/A572M · Published: 2026-05-26 · Updated: July 2026
ASTM A572 Grade 65 is a columbium-vanadium HSLA steel offering 450 MPa minimum yield strength—80% stronger than A36. Its high strength-to-weight ratio enables dramatic structural weight reduction in bridges, high-rise buildings, and heavy...
ASTM A572 Grade 65 is a columbium-vanadium HSLA steel offering 450 MPa minimum yield strength—80% stronger than A36. Its high strength-to-weight ratio enables dramatic structural weight reduction in bridges, high-rise buildings, and heavy construction equipment. The controlled micro-alloy content limits carbon equivalent for good weldability despite the high strength. Available in plates, shapes, and bars with Charpy impact testing options for dynamic loading applications. Specify weathering Grade 65W (ASTM A871) for unpainted bridge applications.
Quick Facts
| Category | Carbon Steel |
| Standard | ASTM A572/A572M |
| Density | 7.85 g/cm³ |
| Yield Strength | 450 MPa (65 ksi) |
| Tensile Strength | 550 MPa (80 ksi) |
Global Equivalents & Cross-Reference
| Alternative Standard / Grade | Action |
|---|---|
| S460 | Compare |
| Q460 | Compare |
| SM570 | Compare |
| StE460 | Compare |
| E460 | Compare |
Heat Treatment & Processing
| Normalizing | 870-900°C, air cool |
| Note | Higher strength than Gr50. Used in bridges and high-stress structures. |
Welding & Fabrication
| Preheat | 50-100°C for sections >25mm |
| Filler Metal | E8018, ER80S-G |
| Weldability Rating | Good — higher CE than Gr50, preheat recommended |
Related Materials
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Frequently Asked Questions
What welding precautions are needed for A572 Gr 65?
Use low-hydrogen electrodes (E8018 or equivalent) and maintain preheat of 50-100°C for sections under 25 mm, increasing to 100-150°C for thicker material. The higher carbon equivalent (0.40-0.45) compared to Gr 50 requires more careful heat input control. For critical dynamically loaded welds, specify matching-strength filler with Charpy-tested weld metal. Avoid excessive heat input (>3.5 kJ/mm) which degrades the fine-grain HSLA microstructure.
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu