ASTM A283 Grade C and D are carbon steel plates for general structural use, differing mainly in their mechanical properties and chemical composition, with Grade D having slightly higher minimum yield strength (around 33-55 ksi vs. 30-55 ksi for C) and higher max carbon content (0.27% vs 0.24%), while Grade C often shows higher ductility (elongation), with Grade D generally offering better weldability due to lower carbon. Both are low-to-intermediate tensile strength steels used in tanks, boilers, and structural parts, but Grade D's higher strength and slightly lower carbon make it versatile for more demanding conditions than Grade C, though C offers better ductility.
Material Properties
| Grade | Yield Point (ksi) | Tensile Strength (ksi) | Min. 8" Elongation % |
| C | 30 | 55-75 | 22 |
| D | 33 | 60-80 | 20 |
Chemical Composition
| Grade C | |
| Carbon max | 0.24% |
| Manganese max | 0.90% |
| Phosphorus max | 0.030% |
| Sulfur max | 0.030% |
| Silicon max, plates ≤ 1 1/2" thick | 0.40% |
| Silicon, plates over 1 1/2" thick | 0.15-0.40% |
| Copper min | 0.20% |
| Grade D | |
| Carbon max | 0.27% |
| Manganese max | 0.90% |
| Phosphorus max | 0.030% |
| Sulfur max | 0.030% |
| Silicon, plates ≤ 1 1/2" thick | 0.40% |
| Silicon, plates over 1 1/2" thick | 0.15-0.40% |
| Copper min | 0.20% |
Typical Applications
Grade C: General structural purposes, often for moderate pressure/temperature.
Grade D: Also general structural use, but its higher strength can suit more demanding applications where better performance is needed, such as offshore structures.
