An MTC is a legal and quality document provided by the steel mill. It certifies that the material supplied conforms to the ordered specification. It contains vital data traceable to the Heat/Batch numbers, including:
Chemical Composition (ladle analysis).
Mechanical Properties (yield strength, tensile strength, elongation, impact values).
Reference to the applicable standard (e.g., GB/T 706, ASTM A36).
Dimensional verification and statement of compliance.
It is essential for material verification, quality assurance, and engineering records.
Table: Comparison of Common Angle Steel Grades (Mechanical & Chemical Properties)
| Standard | Steel Grade | Minimum Yield Strength (MPa) | Minimum Tensile Strength (MPa) | Key Chemical Composition (Max %, unless range) | Primary Application |
|---|---|---|---|---|---|
| GB/T 706 | Q235B | 235 | 370-500 | C: ≤0.20, Mn: ≤1.40, Si: ≤0.35, P: ≤0.045, S: ≤0.045 | General construction, frames, brackets |
| GB/T 706 | Q355B | 355 | 470-630 | C: ≤0.24, Mn: ≤1.60, Si: ≤0.55, P: ≤0.045, S: ≤0.045, (V/Nb/Ti possible) | High-rise buildings, bridges, heavy structures |
| ASTM A6 | A36 | 250 | 400-550 | C: ≤0.26, Mn: - , P: ≤0.04, S: ≤0.05 | General structural purposes, most common US grade |
| ASTM A6 | A572 Gr.50 | 345 | 450 | C: ≤0.23, Mn: ≤1.35, P: ≤0.04, S: ≤0.05 | Where higher strength-to-weight ratio is needed |
| EN 10025-2 | S235JR | 235 | 360-510 | C: ≤0.17 (t≤40mm), Mn: ≤1.40, P: ≤0.045, S: ≤0 |