Core Mechanical Properties (Per ASTM A36/A36M-19)
Below are the non-negotiable mechanical performance thresholds for A36 carbon steel:
| Property | Minimum Requirement | Test Method | Critical Notes |
|---|---|---|---|
| Yield Strength | 36 ksi (250 MPa) | ASTM A370 | Applies to material thickness ≤ 8" (200mm) |
| Tensile Strength | 58–80 ksi (400–550 MPa) | ASTM A370 | Results >80 ksi require manufacturing review |
| Elongation (in 8") | 20% | ASTM E8/E8M | Reduced to ≥18% for thickness >8" |
| Bend Test Performance | No cracking at 180° bend | ASTM E290 | Mandatory for plates & bars |
| Impact Testing | Not required | – | Not approved for sub-zero service |
Safety Alert: Using tensile strength (instead of yield strength) for structural calculations violates U.S. building codes. ALWAYS design based on 36 ksi yield.
The Thickness Factor: Why Dimensions Dictate Strength
A36 properties change dramatically with cross-section size – a reality often overlooked:
Thicker sections (>200mm): Permissible yield strength drops to 32 ksi (220 MPa).
Elongation reduction: Plate thickness exceeding 8 inches (200mm) lowers minimum elongation to 18%.
Certification Requirement: Mills MUST issue Mill Test Reports (MTRs) confirming lot-specific properties.
Real-World Applications vs. Limitations
Valid Uses:
Structural framing (beams, columns, joists)
Base plates & machinery supports
Staircases & non-critical brackets
Prohibited Applications:
Pressure vessels (fails ASME BPVC Section VIII)
Cryogenic service (-20°F/-29°C and below)
Dynamically loaded components (e.g., crane hooks)
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