# Alloy Steel 4340

> The landing-gear steel: maximum strength with toughness for safety-critical rotating parts.

- Category: Carbon, Alloy & Tool Steels → alloy-steel
- HTML page: https://fabvector.com/materials/alloy-steel-4340 (Portuguese: https://fabvector.com/pt/materials/alloy-steel-4340)
- Price index: $$$ (1–5, 6061-T6 = $)

## Mechanical properties (typical values, not certified minimums)

| Property | Value |
|---|---|
| Tensile strength | ~1280 MPa (Q&T) |
| Yield strength | ~1180 MPa (Q&T) |
| Hardness | ~40 HRC (Q&T typical) |
| Density | 7.85 g/cm³ |
| Machinability | ★★☆☆☆ (2/5) |
| Corrosion resistance | ★☆☆☆☆ (1/5) |

## When to choose it

The step above 4140 for safety-critical parts: nickel addition preserves toughness at very high strength, so it survives the shock and fatigue that crack lesser steels — the classic landing-gear recipe.

## When to look elsewhere

If 4140 pre-hard meets the load case, 4340 just adds cost and harder machining. It is equally rust-prone bare, and welding is even less forgiving than 4140.

## Typical applications

- Landing-gear and high-toughness shafts
- Power transmission gears and couplings
- Crankshafts and heavy axles
- Defense and motorsport drivetrain parts

## Compatible surface finishes

- [As-Machined](https://fabvector.com/md/finishes/as-machined)
- [Black Oxide](https://fabvector.com/md/finishes/black-oxide)
- [Zinc Plating](https://fabvector.com/md/finishes/zinc-plating)
- [Nickel Plating (Electrolytic)](https://fabvector.com/md/finishes/nickel-plating)
- [Electroless Nickel Plating (ENP)](https://fabvector.com/md/finishes/electroless-nickel-plating)
- [Hard Chrome Plating](https://fabvector.com/md/finishes/chrome-plating)
- [Powder Coating](https://fabvector.com/md/finishes/powder-coating)
- [Wet Painting](https://fabvector.com/md/finishes/wet-painting)
- [PTFE Coating (Teflon)](https://fabvector.com/md/finishes/ptfe-coating)
- [Laser Marking](https://fabvector.com/md/finishes/laser-marking)

Industries: aerospace, defense, oil-and-gas, automotive · Instant quote: https://fabvector.com/quote