On the Mechanical Properties of Medium Carbon Ni-Cr-Mo-V Forging Die Steel with Bainite Microstructure

Characteristics of mechanical properties of medium carbon Ni-Cr-Mo-V forging die steel with bainite microstructure was investigated and following results were obtained; (1) Impact property at elevated temperature: Impact property of lower bainite at elevated temperature (from 100°C up to 600°C) is superior to that of tempered martensite with similar strength, on the other hand, impact property of upper bainite is similar to that of tempered martensite. (2) Tensile ductility: Tensile ductility of lower and upper bainite is superior to tempered martensite. (3) Notch tensile strength: Notch tensile strength of lower bainite is superior to tempered martensite, but that of upper bainite is similar to or slightly better than that of tempered martensite. Consequently, medium carbon Ni-Cr-Mo-V steel with bainite microstructure is expected to be excellent for forging dies.