4340 steel is a low alloy ultra-high strength steel. Only steel with a tensile strength greater than 1400MPa and a yield strength greater than 1200MPa at room temperature is referred to as "ultra high strength steel". 4340 steel is a typical representative of ultra-high strength steel, which is obtained through heat treatment.
The chemical composition of 4340 alloy steel is as follows:
-Carbon content: 0.38-0.43%
-Silicon content: 0.15-0.35%
-Manganese content: 0.60-0.80%
-Phosphorus content: ≤ 0.035%
-Sulfur content: ≤ 0.040%
-Chromium content: 0.70-0.90%
-Nickel content: 1.65-2.00%
-Molybdenum content: 0.20-0.30%
4340 alloy steel has excellent mechanical properties, with a tensile strength of over 1200 MPa, a yield strength of 1000 MPa, and an elongation of over 12%. In addition, it also has good fatigue strength and toughness, and can maintain stable performance under high loads and high impact loads.
Features:
4340 alloy steel has high strength, toughness, and excellent stability in quenching and heat resistance, but white spots are very sensitive and have a brittle background. The welding was poor and subjected to high temperatures before welding. After welding, it is necessary to relieve pressure. Usually, it is used after quality.
Utilize:
4340 alloy steel is used to create important quality control components that require good toughness, high strength, and large dimensions, such as shafts for high load machines, rotor shafts with a diameter of 250mm, helicopter rotor shafts, and turbine shafts, blades, high load components, and crankshaft fasteners for turbojet engines. It can also be used to operate rotor shafts and blades with temperatures exceeding 400 ° C; It can also be executed to produce important parts with special performance requirements.
