4340 Round Bar: Material Profile
4340 combines nickel, chromium, and molybdenum to provide deep hardenability and strong performance under impact and cyclic loading.
It is available in hot-rolled, cold-finished, annealed, and heat-treated conditions depending on the specification.
Purchase to the controlling ASTM, SAE, AMS, or customer specification. Section size, supply condition, mechanical properties, surface limits, testing, and heat/lot traceability can change the acceptable material and processing route.
Key Characteristics
- High tensile and fatigue strength
- Excellent toughness
- Deep hardenability
- Good machinability when annealed
Common Applications
- Crankshafts and gears
- Aircraft and defense components
- Power-transmission parts
- Heavy-equipment and oil-and-gas shafts
Typical Chemical Range
| Element | Weight % |
|---|---|
| Carbon | 0.38–0.43 |
| Manganese | 0.60–0.80 |
| Silicon | 0.15–0.35 |
| Nickel | 1.65–2.00 |
| Chromium | 0.70–0.90 |
| Molybdenum | 0.20–0.30 |
| Phosphorus (max) | 0.035 |
| Sulfur (max) | 0.040 |
Chemistry ranges are general reference values. The purchase specification and material certification govern the order.
Request Pricing for 4340 Round Bar
The material field is prefilled with 4340 and remains editable. Add the specification, size, condition, quantity, processing, testing, required date, and ship-to location.
