General structural mild steel — sections, plate, weldments. The default for fabrication.
| Property | Typical value |
|---|---|
| Density | 7850 kg/m³ |
| Yield (≤16mm) | 275 MPa |
| Tensile | 410–560 MPa (3–100 mm) |
| Elongation | 23 % |
| Young's E | 210 GPa |
| Hardness | ~120 HB |
| CTE | ~12 µm/m·K |
| Thermal cond. | ~50 W/m·K |
| Max service | ~350 °C |
| Poisson ν | ~0.29 |
| Shear modulus G | ~81 GPa (derived) |
| Shear strength | ≈0.6 × UTS (design convention — not test data) |
| Specific heat | ~460–480 J/kg·K |
| Elec. resistivity | ~0.15–0.20 µΩ·m |
| Melting range | ~1450–1520 °C |
| Fatigue (indicative) | ~180–270 MPa (≈0.45–0.5 × UTS) — rotating-bend, polished specimen; indicative only, surface/size/loading factors apply |
~65–70% (free-cutting = 100). Sharp HSS/carbide, moderate speeds.
Readily weldable by all processes; no preheat for thin sections (CEV low).
| System | Designation |
|---|---|
| EN | S275JR / 1.0044 |
| DIN | St 44-2 / 1.0044 |
| ASTM | ≈A36 |
| JIS | ≈SS400 / SM400 |
| BS | BS 4360 43A |
Equivalents & alternatives: S275JR (1.0044); old BS 43A; ASTM A36 (near); DIN St44. Alt: S355 (higher strength), EN3B (bar).
Higher-strength structural steel — same weldability as S275 with ~30% more yield.
Carbon steelFree-cutting bright mild steel — first choice for high-volume machined parts, studs, fittings.
Carbon steelGeneral bright mild steel bar — weldable, case-hardenable, good all-rounder for machined parts.
Carbon steelMedium-carbon steel — shafts, studs, gears, keys. Through-hardenable to moderate strength.
