ASTM 4340 Steel Round Bar|EN24 Steel Round Bar|34CrNiMo6 Steel Round Bar
Material available in round and flat sections
ASTM 4340 steel is an ultra-high strength steel classified a medium-carbon, low-alloy steel. 4340 steel has high strength, ductility, toughness, creep resistance, and fatigue resistance relative to most other steels. Hardness ranging from 24 to 53 HRC can be achieved, depending on the heat treatment.
Applications
For use on:
- ASTM 4340 alloy steel is mainly used in power transmission gears and shafts, aircraft landing gear, and other structural parts.
Physical Properties
| Chemical Composition (%) | ||||||||||||
| C | Si | Mn | S | P | Cr | Mo | Ni | |||||
| 0.37~0.43 | 0.15~0.35 | 0.60~0.80 | ≤0.040 | ≤0.035 | 0.70~0.90 | 0.20~0.30 | 1.65~2.00 | |||||
Designation by Standards
| ASTM | JIS | DIN | CN | UK | EU |
| 4340 | SNCM447 | 1.6582 | 40CrNiMo | EN24/817M40 | 34CrNiMo6 |
Mechanical Properties
| Typical Mechanical Properties – Hot Rolled Condition | ||||||||||||
| Tensile Strength Mpa | 850-1000 | |||||||||||
| Yield Strength Mpa | 635-750 | |||||||||||
| Elongation in 50mm % | 12 – 13 | |||||||||||
| Hardness (QT) | 28~33 Hrc | |||||||||||
Forming
ASTM 4340 alloy steel has good ductility and formability in the annealed condition. It can be bent or formed by pressing or spinning in the annealed state.
Heat Treatment
ASTM 4340 alloy steel is heat treated at 830°C (1525°F) followed by quenching in oil.
Forging
ASTM 4340 alloy steel is forged at 427 to 1233°C (1800 to 2250°F).
Cold Working
ASTM 4340 alloy steel can be cold worked using all conventional methods in the annealed condition. It has high ductility.
Annealing
ASTM 4340 alloy steel is annealed at 844°C (1550°F) followed by cooling the furnace.
Tempering
ASTM 4340 alloy steel should be in the heat treated or normalized and heat treated condition before tempering. Tempering temperatures depend upon the desired strength level.
Hardening
ASTM 4340 alloy steel can be hardened by cold working or heat treatment.
Applications
ASTM 4340 alloy steel is mainly used in power transmission gears and shafts, aircraft landing gear, and other structural parts.