Description

4340 is a high-strength, low-alloy steel known for its exceptional toughness, wear resistance, and impact strength. It contains nickel, chromium, and molybdenum, which contribute to its excellent properties.

Applications

4340 alloy steel is commonly used in applications such as aerospace components, automotive parts, oil and gas industry equipment, gears, shafts, and tooling.

Blacksmith Applications

For blacksmiths, 4340 alloy steel can be used to create various high-strength tools and components such as punches, chisels, drifts, hammers, and specialized tooling requiring superior toughness and wear resistance.

4340 Forging Temperature

Forging should be done between 2200°F to 1800°F (1204°C to 982°C), followed by slow cooling in a furnace or insulating material to minimize the risk of cracking.

4340 Heat Treatment

4340 Annealing Temperature

Annealing is typically performed at 1525°F to 1600°F (829°C to 871°C) for a sufficient amount of time, followed by slow cooling in a furnace to relieve internal stresses.

4340 Normalizing Temperature

Normalizing can be carried out at 1525°F to 1575°F (829°C to 857°C) for a proper soak time, followed by air cooling.

4340 Hardening Temperature

Hardening is typically done by oil quenching from the austenitizing temperature of 1475°F to 1550°F (802°C to 843°C), followed by tempering to achieve the desired hardness and toughness.

4340 Tempering Temperature

Tempering should be performed at specific temperatures depending on the desired hardness and mechanical properties. Typical tempering temperature ranges from 400°F to 1200°F (204°C to 649°C).

Machinability

4340 alloy steel has a machinability rating of 60, indicating that it is moderately machinable. Suitable cutting tools and machining techniques should be used for optimal results.

Weldability

4340 alloy steel has good weldability with suitable preheating and post-weld heat treatment. Welding should be performed using low hydrogen electrodes or methods, and stress relieving after welding is recommended.