This specification covers carbon-manganese steel shapes, plates, and bars of structural quality for use in riveted, bolted, or welded construction of buildings and for general structural purposes.
| Element | Composition, % |
|---|---|
| Grades 50 [345] and 55 [380] | |
| Carbon, max | 0.27 |
| Manganese, max | 1.35 |
| Phosphorus, max | 0.04 |
| Sulfur, max | 0.05 |
| Silicon, max | 0.40 |
| Copper, min, when copper is specified | 0.20 |
| Grade 50 [345] | Grade 55 [380] | |
|---|---|---|
| ksi [MPa] | ksi [MPa] | |
| Tensile strength, min | 70B [485] | 70 [485] |
| Tensile strength, max | 100 [690] | 100 [690] |
| Yield strength, min | 50 [345] | 55 [380] |
| Elongation in 8 in. [200 mm], min, % | 18 | 17 |
| Elongation in 2 in. [50 mm], min, % | 21 | 20 |
A. See the Orientation subsection in the Tension Tests section of Specification
A6/A6M.
B. Minimum tensile strength for Grade 50 shapes with flange or leg thickness to 1
1⁄2 in. [40 mm] inclusive, shall be 65 ksi [450 MPa].