The characteristics of alloy structure steel 4340

     Alloy structure steel 4340 has high strength, high toughness and good hardenability. When hardened reaches half martensite hardness (HRC45), water quenching critical quenching diameter for Φ ≥100mm, critical quenching oil quenching diameter for Φ ≥75mm; when hardened to 90% martensite, water quenched critical diameter for Φ 80 ~ 90mm, oil quenched critical diameter for Φ 55 ~ 66mm. AISI 4340 alloy steel has anti-overheating and stability, but the white spot high sensitivity, temper brittleness, poor welding, high temperature preheating before welding, eliminate stress after welding.
     The main purpose of alloy structure steel 4340: manufacture of turbine gears, gear ring, the whole forging rotor. Engine connecting rods, valve. High strength, high toughness, a greater cross-sectional size forgings such as forged part of wind generator, drive eccentric shaft of horizontal type forging machine, crankshaft of forging machine etc.. Automobile, airplane special wear-resistant parts etc..

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