ASTM 4340 Steel Round Bar | EN24 Steel Round Bar | 34CrNiMo6 Steel Round Bar

ASTM 4340 Steel Round Bar | EN24 Steel Round Bar | 34CrNiMo6 Steel Round Bar

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.

Designation by Standards

Chemical Composition (%)

Mechanical Properties

ASTM 4340 alloy steel can be machined using all conventional techniques. Machining process can be performed in the annealed or normalized and tempered conditions.

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.

Welding

ASTM 4340 alloy steel can be welded using fusion or resistance welding methods. Preheat and post heat weld procedures are followed while welding this steel by established methods.

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.