Steel E4340-VAR
Grade
GOST E4340
VAR = vacuum arc remelted premium aircraft quality (AMS 6414), supplied…
Choose when cleanliness-driven fatigue life and transverse toughness are required (landing gear, rotor shafts).
Values for the VAR condition
Other E4340 tempers and conditions
E4340 is listed in 14 conditions; see the grade overview at E4340.
- Annealed
- CR
- HR
- N&T
- CD
- Normalized
- Q&T 28-32 HRC
- VAR
- Q&T
- Q&T 32-36 HRC
- Q&T 36-40 HRC
- Q&T 40-44 HRC
- Q&T 44-48 HRC
- Q&T 50-53 HRC
Compare all 14 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/spheroidize annealed (≈ 800 °C, slow cool) | Softest supply condition for machining, deep hole drilling and cold forming before final Q&T. | 470 | 745 | 22 | 217 HB | 45 W/m·K |
Cold rolled | Thin sheet/strip supply form for blanking and forming before hardening. | 600 | 800 | 15 | 21 HRC | 7 % IACS |
HRDefault Hot rolled | Standard mill stock for re-heat-treating; not for final load-bearing use in as-rolled state. | 620 | 950 | 16 | 30 HRC | — |
Normalized and tempered | Machining-friendly pre-treatment for large aerospace bar/forgings that will be finish heat treated later. | 700 | 930 | 18 | 29 HRC | 7 % IACS |
Cold drawn | Close-tolerance bright bar for shafts and parts machined without further heat treatment. | 720 | 860 | 13 | 25 HRC | — |
870 °C, air cooled | Grain-refining condition used before machining/hardening; high strength but low ductility for a deep-hardening steel. | 862 | 1,279 | 12 | 39 HRC | — |
Tempered ≈620 °C | Toughest Q&T level; for weld-repaired or impact-loaded parts and thick sections. | 880 | 1,000 | 19 | 30 HRC | — |
VARThis page Vacuum arc remelted premium aircraft quality (AMS 6414), supplied… | Choose when cleanliness-driven fatigue life and transverse toughness are required (landing gear, rotor shafts). | 950 | 1,100 | 15 | 35 HRC | 7 % IACS |
Quenched and tempered | General service condition for shafts, gears and structural parts needing balanced strength and toughness. | 1,035 | 1,150 | 17 | 34 HRC | — |
Tempered ≈580 °C | Most common commercial hardness band for shafts, couplings and machinery components. | 1,035 | 1,150 | 17 | 34 HRC | — |
Tempered ≈500 °C | Higher-strength band for gears, torsion bars and highly loaded shafting. | 1,160 | 1,270 | 15 | 38 HRC | — |
Tempered ≈450 °C | Used for high-strength fasteners, tooling and aircraft fittings needing wear plus strength. | 1,270 | 1,400 | 14 | 42 HRC | — |
Tempered ≈370 °C | Very high strength for landing-gear-class parts; notch sensitivity and hydrogen embrittlement risk rise sharply. | 1,400 | 1,560 | 13 | 46 HRC | — |
Tempered ≈205–260 °C | Maximum-strength aerospace condition (VAR stock only); use where mass is critical and fracture control is engineered. | 1,720 | 1,900 | 11 | 52 HRC | — |
What is E4340-VAR?
E4340-VAR is E4340 in the VAR grade — choose when cleanliness-driven fatigue life and transverse toughness are required (landing gear, rotor shafts). E4340-VAR has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi). E4340-VAR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,427°C (2,601 °F). HR is the default condition FabDigit quotes; VAR is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- High strength — 950 MPa (138 ksi), better than 91% of steel grades
Limitations
- Low fracture toughness — 65 MPa·√m (59.2 ksi·√in), worse than 75% of steel grades
E4340-VAR properties
Typical room-temperature values for E4340-VAR; 23 are specific to this condition. Other listed values are E4340 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
E4340-VAR has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,427°C (2,601 °F).
Mechanical16
E4340-VAR has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
E4340-VAR is rated for continuous service to 425°C (797 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
E4340-VAR conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of E4340-VAR takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 40%.
Manufacturability8
E4340-VAR's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (30/100); formability poor (30/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with E4340-VAR
Is E4340 easy to machine?
Machine in annealed or ≤32 HRC condition with rigid setups, carbide tooling and flood coolant; above 45 HRC use CBN/ceramic or grinding.
Can E4340 be welded?
Weldable only with preheat 200–320 °C, low-hydrogen or matching filler, and immediate post-weld temper below the part's tempering temperature; avoid welding at high-strength tempers.
Can E4340 be formed, bent or molded?
Cold form only in the annealed state with generous radii; hot forge 1050–1200 °C, finish above 900 °C, then normalize before hardening.
What surface finishes work on E4340?
No anodizing (ferrous): use Cd or Zn-Ni plating, hard chrome, black oxide, phosphate or shot peening; bake 190 °C ≥23 h after plating to relieve hydrogen at strengths above ~1240 MPa.
E4340 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| C | 0.38 – 0.43 | 0.4 |
| Mn | 0.65 – 0.85 | 0.75 |
| Si | 0.15 – 0.35 | 0.25 |
| Ni | 1.65 – 2 | 1.8 |
| Cr | 0.7 – 0.9 | 0.8 |
| Mo | 0.2 – 0.3 | 0.25 |
| PE-prefix electric-furnace limit; AMS 6414 VAR restricts to 0.010 max | ≤ 0.03 | 0.01 |
| SAMS 6414 VAR restricts to 0.010 max | ≤ 0.03 | 0.01 |
| Curesidual | ≤ 0.35 | 0.1 |
| Fe | balance | — |
E4340-VAR — frequently asked
What is E4340-VAR used for?
E4340-VAR is typically used for aircraft landing gear components, power-transmission shafts, gears and pinions, high-strength bolts and studs, torsion bars and forging die holders. In short: aerospace high-strength bar.
What is the yield strength of E4340-VAR?
E4340-VAR has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,100 MPa (160 ksi) — stronger than 91% of steel grades. Strength varies by condition: see the 14 listed tempers.
Is E4340-VAR easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machine in annealed or ≤32 HRC condition with rigid setups, carbide tooling and flood coolant; above 45 HRC use CBN/ceramic or grinding.
Can E4340-VAR be welded?
Not readily — weldability is rated poor (30/100). Weldable only with preheat 200–320 °C, low-hydrogen or matching filler, and immediate post-weld temper below the part's tempering temperature; avoid welding at high-strength tempers.
What surface finishes work on E4340-VAR?
No anodizing (ferrous): use Cd or Zn-Ni plating, hard chrome, black oxide, phosphate or shot peening; bake 190 °C ≥23 h after plating to relieve hydrogen at strengths above ~1240 MPa.
Can E4340-VAR be formed, bent or molded?
Cold form only in the annealed state with generous radii; hot forge 1050–1200 °C, finish above 900 °C, then normalize before hardening.
What is the maximum service temperature of E4340-VAR?
E4340-VAR is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between E4340-HR and E4340-VAR?
HR is the default condition — standard mill stock for re-heat-treating; not for final load-bearing use in as-rolled state. VAR: choose when cleanliness-driven fatigue life and transverse toughness are required (landing gear, rotor shafts). Yield strength is 620 MPa in HR versus 950 MPa in VAR.
Can FabDigit make parts in E4340-VAR?
Yes — E4340-VAR is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. Upload a STEP file to get a price and a DFM check.
Sources
- SAE J404 — Chemical Compositions of SAE Alloy Steels — SAE International (2021)
- AMS 6414 — Steel Bars, Forgings, Tubing 0.80Cr-1.8Ni-0.25Mo, Consumable Electrode Vacuum Melted — SAE International (2019)
- AMS 6415 — Steel Bars, Forgings and Tubing 4340 — SAE International (2019)
- GB/T 3077 (40CrNiMoA) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- MMPDS-17 (4340 and 4340 VAR allowables) — Battelle/FAA (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.