High-tensile Ni-Cr-Mo steel — heavily loaded shafts, gears, crankshafts. Tough at high strength.
| Property | Typical value |
|---|---|
| Density | 7850 kg/m³ |
| Yield (T) | ≥650 MPa |
| Tensile (T) | 850–1000 MPa |
| Elongation | ~13 % |
| Young's E | 210 GPa |
| Hardness | ~248–302 HB (T) |
| CTE | ~12 µm/m·K |
| Thermal cond. | ~42 W/m·K |
| Max service | ~500 °C (stay below tempering temp) |
| 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 | ~0.25 µΩ·m |
| Melting range | ~1420–1500 °C |
| Fatigue (indicative) | ~380–500 MPa (T cond., ≈0.45–0.5 × UTS) — rotating-bend, polished specimen; indicative only, surface/size/loading factors apply |
~45–50% in ‘T’; rigid setup, carbide.
Preheat 200–300 °C + PWHT; not for general fabrication.
| System | Designation |
|---|---|
| EN | 34CrNiMo6 / 1.6582 (≈36CrNiMo4 / 1.6511) |
| DIN | 34CrNiMo6 |
| AISI | 4340 |
| ASTM | A29 / A322 4340 |
| JIS | SNCM439 (≈SNCM447) |
| BS | BS 970 817M40 (EN24) |
| UNS | G43400 |
Equivalents & alternatives: 817M40 (EN24); 1.6582 (34CrNiMo6); AISI 4340. Alt: EN19 (no Ni, lower cost).
Chromium-molybdenum alloy steel — high strength shafts, spindles, high-tensile bolts.
Fastener steelThe standard high-tensile bolt class — general structural and machine fasteners. Medium-carbon (or boron) steel, quenched & tempered.
Fastener steelHigh-strength class — preloaded structural assemblies (EN 14399/HSFG type) and high-duty machine fasteners.
Fastener steelThe socket-screw class — highest standard property class. Alloy steel, tightly controlled Q&T; usually self-colour/black.
