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
We quote 4340 for manufacturers and commercial buyers. Requirements of 3,000–10,000 lb are welcome, along with multi-ton and truckload programs.
We are not a retail metal store. Small personal-use, typical single-bar, and cut-piece orders are generally not a fit. The material field is prefilled and remains editable; add the specification, size, condition, total weight, processing, testing, required date, and ship-to location.
