39NiCrMo3
1.6510Nickel-chromium-molybdenum quench & temper steel. Similar to AISI 4340 but with lower Ni — more economical. Good hardenability for sections up to ~80mm. Excellent balance of strength, toughness, and fatigue resistance. High white-point sensitivity — hydrogen control required. Used for crankshafts, connecting rods, gear shafts, landing gear components, and heavy-duty machinery parts.
International equivalents
| Flag | Standard | Country | Grade | Number | Match |
|---|---|---|---|---|---|
| 🇺🇸 | AISI | USA | AISI 9840 | — | REF |
| 🇪🇺 | EN | Europe | 39NiCrMo3 / 1.6510 | 1.6510 | 100% |
| 🇫🇷 | AFNOR | France | 40NCD3 | — | 95% |
Sources: ASTM A519, EN 10083-3, NF
Mechanical properties — Pro
QT
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | ||
| Yield Strength | ||
| Elongation | ||
| Hardness HB | ||
| Elastic Modulus | ||
| Density |
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