34CrNiMo6
1.6582High-strength quenched and tempered Cr-Ni-Mo steel. Excellent hardenability and toughness, suitable for large cross-sections. Used for heavy-duty shafts, gears, turbine parts, and aerospace components.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 4340 | G43400 | REF |
| 🇪🇺 | EN | Europe | 34CrNiMo6 | 1.6582 | 100% |
| 🇨🇳 | GB | China | 34CrNiMo6 | — | 95% |
| 🇬🇧 | BS | United Kingdom | 817M40 / EN24 | — | 93% |
| 🇯🇵 | JIS | Japan | SNCM439 | — | 88% |
Sources: ASTM A29, EN 10083-3:2006, GB/T 3077, BS 970, JIS G4103
Chemical composition comparison (wt%)
Side-by-side: 34CrNiMo6 (EN) (EN 10083-3:2006) vs AISI 4340 (AISI) (ASTM A29)
| Element | 34CrNiMo6 (EN) | AISI 4340 (AISI) | Overlap |
|---|---|---|---|
| C | 0.3–0.38% | 0.38–0.43% | Partial ⚠️ AISI upper limit 0.05% higher |
| Si | 0–0.4% | 0.15–0.35% | OK |
| Mn | 0.5–0.8% | 0.6–0.8% | OK |
| P | 0–0.025% | 0–0.035% | OK |
| S | 0–0.035% | 0–0.04% | OK |
| Cr | 1.3–1.7% | 0.7–0.9% | No overlap ❌ |
| Mo | 0.15–0.3% | 0.2–0.3% | OK |
| Ni | 1.3–1.7% | 1.65–2% | Partial ⚠️ AISI upper limit 0.3% higher |
Mechanical properties
QT
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 1000–1200 | MPa |
| Yield Strength | ≥ 800 | MPa |
| Elongation | ≥ 11 | % |
| Hardness HRC | 30–36 | HRC |
| Elastic Modulus | ≥ 210 | GPa |
| Density | ≥ 7.85 | g/cm3 |
Heat treatment
| Process | Temperature | Medium | Holding Time | Notes |
|---|---|---|---|---|
| normalizing | 850–880 °C | air | min 2 min per mm | — |
| quenching | 830–860 °C | oil | min 30 min | Oil quench mandatory due to high hardenability |
| tempering | 540–660 °C | air | min 60 min | Select temperature based on desired hardness |
| annealing | 650–700 °C | furnace | Several hours | Soft annealing for machinability |
Compatibility verdict
34CrNiMo6 and AISI 4340: 90% composition match
Close equivalents but NOT identical. Critical differences: C range (0.3–0.38 vs 0.38–0.43), Si range (0–0.4 vs 0.15–0.35), Mn range (0.5–0.8 vs 0.6–0.8), P range (0–0.025 vs 0–0.035).
For dual certification, melt must hit: C 0.38–0.38, Si 0.15–0.35, Mn 0.6–0.8, P 0–0.025
Related materials
50CrV4
1.8160Chromium-vanadium spring/tool steel — identical alloy system to 51CrV4 (1.8159) but recognized as a separate grade in some standards. Dual use: heavy-duty springs (EN 10089) AND cold work tools (knives, shear blades). V improves temper resistance and grain refinement. UTS 1200-1500 QT. Used for heavy leaf springs, stabilizer bars, torsion bars, and cold work cutting tools.
51CrMoV4
1.7701CrMoV alloyed spring steel — THE European automotive suspension spring material. CrMo gives deep hardenability for large coil springs, V adds grain refinement and secondary hardening for fatigue resistance. UTS 1350-1600 MPa QT. Used for hot-formed coil springs (cars, trucks), leaf springs, torsion bars, and stabilizer bars. Excellent sag resistance to 200°C.
20MnCr5
1.7147Manganese-chromium case-hardening steel with higher core strength than 16MnCr5. Used for heavily loaded gears, shafts, camshafts, and transmission components requiring high surface hardness with tough core. Popular in automotive and heavy machinery.
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