4330V Steel
A Ni-Cr-Mo-V alloy steel with high strength and toughness
Typical values for the temper in the title
4330V is a steel with lower carbon than 4340 (about 0.3%), with nickel, chromium, molybdenum and added vanadium. The lower carbon and vanadium give it high toughness at high strength (about 1170 MPa tensile).
It is used in aerospace structural parts and in oil and gas tools, where a combination of strength and toughness is needed in thick parts.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 1170 MPa | |
| Yield strength Rp0.2 | 1070 MPa | |
| Elongation A | 12% | |
| Hardness | 340 HB | |
| Modulus of elasticity E | 207 GPa | |
| Density ρ | 7.85 g/cm³ | |
| Machinability | 35% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| C carbon | about 0.30 (nominal) | strength |
| Ni nickel | about 1.8 (nominal) | toughness |
| Cr chromium | about 0.9 (nominal) | hardenability |
| Mo molybdenum | about 0.45 (nominal) | hardenability |
| V vanadium | about 0.08 (nominal) | fine grains and toughness |
| Fe iron | balance |
Nominal (typical) composition. Exact ranges are defined in the AMS specifications. Equivalents in other standards are close in composition, not identical.
Conditions and heat treatment
In alloy steels, chromium, molybdenum and nickel raise hardenability: thicker parts reach full hardness even at the center. Properties are set mainly by heat treatment.
| Condition | Properties | When to choose it |
|---|---|---|
| Annealed / normalized and tempered | for machining | delivery condition |
| Hardened and tempered | about 1170 MPa tensile, high toughness | structural parts |
Applications
- Aerospace structural parts
- Oil and gas drilling tools
- Heavy shafts
- Thick forgings
- Landing gear parts
Fabrication
Heat treatment
Hardened and tempered. As with any high-strength steel, beware of hydrogen embrittlement in plating.
Welding
Possible with a controlled procedure, preheat and post-weld treatment.
Machining
Annealed or normalized.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 4340 | 1080–1470 / 970–1380 MPa | Difficult — Preheat 200C | more carbon, higher strength · material page |
| 300M | 1930 / 1690 MPa | Very difficult | much higher strength, lower toughness · material page |
| 4140 | 655–1000 / 415–835 MPa | Medium — Preheat 150C | cheaper, for less critical parts · material page |
Common mistakes
Plating without baking
Risk of hydrogen embrittlement.
Replacing with 4340 without calculation
Properties differ, especially toughness.
Welding without a procedure
Risk of cracking.
Equivalents, standards and supply
| Standards | AMS 6411 |
|---|---|
| Forms | rod · forging · rings |
| Producers | Firth Rixson · Carpenter |
Learn more
Values are typical and for comparison only, and depend strongly on condition and diameter. For design, rely on the standard and on the mill certificate. Sources: SAE J403 and J404, ASTM A29, A322 and A519 (composition), producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026