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
Compatibility verdict
39NiCrMo3 and 40NCD3: 95% composition match
Related materials
42CrMo4
1.7225High-strength quenched and tempered chromium-molybdenum steel. Widely used for shafts, gears, crankshafts, connecting rods, and high-strength bolts. Excellent hardenability and good fatigue resistance.
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.
16MnCr5
1.7131Low-carbon case-hardening steel with manganese and chromium. Excellent for carburizing to produce a hard, wear-resistant surface with a tough core. Standard choice for gears, camshafts, piston pins, and transmission components.
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