Machinery Grade
4340 Steel
Demanding applications
Low-alloy nickel-chrome-molybdenum steel, quench and temper grade, with very high mechanical strength, excellent toughness and exceptional hardenability in large sections. Supplied quenched and tempered, ready to machine, and stands out for its high fatigue strength.
Main features
Very high strength
Excellent toughness
Hardens in large sections
Standards and equivalents
| SAE / AISI | EN | DIN | JIS |
|---|---|---|---|
| 4340 | ≈ 40NiCrMo8-4 | ≈ 1.6565 | ≈ SNCM439 |
Chemical composition
| % | C | Si | Mn | Cr | Ni | Mo | P | S |
|---|---|---|---|---|---|---|---|---|
| Min | 0.38 | 0.15 | 0.60 | 0.70 | 1.65 | 0.20 | — | — |
| Max | 0.43 | 0.35 | 0.80 | 0.90 | 2.00 | 0.30 | 0.035 | 0.040 |
Supply condition
Hot forgedQuenched and tempered
Hot rolledQuenched and temperedAvailable package sizes
Round bars1/2" – 24"13 mm – 610 mm—
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Typical applications
- High-strength shafts
- Drive shafts
- Crankshafts
- High-load gears
- Industrial spindles
- Engine connecting rods
- High-strength bolts
- Landing gear
- Heavy machinery components
Note: The information and values in this data sheet are provided for reference only and may vary depending on manufacturing, treatment and application conditions. They do not constitute guaranteed specifications, so use and interpretation of this data is the user's responsibility.
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