ASTM A36 Carbon Steel: Properties, Equivalents & Applications
ASTM A36/A36M · Published: 2026-05-22 · Updated: 2026-07-07
ASTM A36 is the most widely used hot-rolled structural carbon steel in North America. Containing 0.25-0.29% carbon, 0.80-1.20% manganese, ≤0.04% phosphorus, and ≤0.05% sulfur, it provides an optimal balance of strength, weldability, and...
ASTM A36 is the most widely used hot-rolled structural carbon steel in North America. Containing 0.25-0.29% carbon, 0.80-1.20% manganese, ≤0.04% phosphorus, and ≤0.05% sulfur, it provides an optimal balance of strength, weldability, and machinability at low cost. A36 is the default material for building frameworks, bridges, transmission towers, and general fabrication. Typical applications: structural beams and columns, base plates, gussets, stiffeners, bridge components, and machinery frames. Not recommended for: cryogenic service (brittle transition below -20°C), high-temperature pressure vessels, or applications requiring hardenability (use AISI 1045 or 4140 for heat-treated wear resistance).
Quick Facts
| Category | Carbon Steel |
| Standard | ASTM A36/A36M |
| Density | 7.85 g/cm³ |
| Yield Strength | 250 MPa (36 ksi) |
| Tensile Strength | 400-550 MPa (58-80 ksi) |
Detailed Mechanical Properties
| Elongation | 20% (in 200mm) |
| Hardness | 119-159 HB |
| Charpy V Notch | 27J at 0°C (longitudinal) |
| Shear Modulus | 79.3 GPa |
Physical Properties
| Melting Point | 1425-1540 °C |
| Thermal Conductivity | 52 W/m·K at 20°C |
| Electrical Resistivity | 0.0000174 Ω·cm |
| Specific Heat | 486 J/kg·K |
Global Equivalents & Cross-Reference
| Alternative Standard / Grade | Action |
|---|---|
| Q235 | Compare |
| S275JR | Compare |
| SS400 | Compare |
| E250 | Compare |
| St37-2 | Compare |
Heat Treatment & Processing
| Normalizing | 890-940°C, air cool |
| Annealing | 840-880°C, furnace cool |
| Stress Relieving | 595-650°C, 1h per 25mm thickness, air cool |
| Note | A36 is typically used in as-rolled condition; heat treatment is uncommon for structural applications |
Welding & Fabrication
| Preheat | Not required for thicknesses under 20mm; 50-100°C for 20-40mm; 100-150°C for >40mm |
| Filler Metal | E7018 (SMAW), ER70S-6 (GMAW), E71T-1 (FCAW) |
| Interpass Temp | Max 315°C |
| Pwht | Not typically required; stress relieve at 595-650°C if specified |
| Weldability Rating | Excellent — one of the most weldable carbon steels |
Related Comparisons
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Frequently Asked Questions
What is the difference between ASTM A36 and A572 Grade 50?
ASTM A36 has a minimum yield strength of 250 MPa (36 ksi), while A572 Grade 50 offers 345 MPa (50 ksi) minimum yield—approximately 38% stronger. A572 Gr 50 also has tighter chemistry controls with micro-alloying elements (niobium, vanadium) for improved strength-to-weight ratio.
Can ASTM A36 be used for pressure vessels?
No. ASTM A36 is not approved for pressure vessel construction. ASME Boiler and Pressure Vessel Code requires materials with certified elevated-temperature properties such as SA-516 Gr 70. Using A36 for pressure-containing applications violates code and creates safety hazards.
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