SAE 4340 Alloy Steel Round Bars

SAE 4340 alloy steel is commonly used in applications requiring high strength and toughness, such as aircraft landing gear components, automotive parts, and industrial machinery components subjected to heavy loads and high stresses.

Chemical Composition:

Mechanical Properties:

• Tensile Strength: 930 - 1080 MPa
• Yield Strength (0.2% offset): 740 - 900 MPa
• Elongation: 10 - 20%
• Reduction of Area: 40 - 50%
• Impact Toughness (Charpy V-notch): 30 - 40 J/cm²

Physical Properties:

• Density: 7.85 g/cm³
• Melting Point: Approximately 1416°C (2571°F)

Heat Treatment:

• Annealing: Heat to 800-855°C (1472-1571°F), slow furnace cool at a rate not exceeding 10°C (18°F) per hour to 650°C (1202°F), then cool in air.
• Normalizing: Heat to 870-925°C (1598-1697°F), air cool.
• Quenching: Oil quench from 830-860°C (1526-1580°F) or water quench from 820-850°C (1508-1562°F), followed by tempering.
• Tempering: Temper at a desired temperature depending on the desired properties. Typical tempering temperatures range from 480-620°C (896-1148°F) for achieving a balance of strength and toughness.