Toughness of High Strength Ni-Cr-Mo-V Steels Containing 1-5% Nickel

Abstract

A study has been made of mechanical characteristics with special reference to toughness of low carbon Ni-Cr-Mo-V structural steels containing 1-5% nickel with the intermediate stage transformed structure and tempered-martensitic structure.
Some intermediate structures have been compared with the tempered-martensitic structure at a similar strength level, by evalution of charpy impact values, transition temper-atures and fracture toughness values and also examination of microfractograghs.
In the intermediate structures as well as the tempered-martensitic structure of these steels, it is generally to say that the toughness is improved with increasing nickel amount though the latter structure is always superior to the former ones.
Considerations on microfractograghs of fractured Charpy impact or slow bend specimens lead to some informations concerning the influence of microstructural factors, e. g. morphology of the precipitates and mixture of different transformation products at different temperatures, on the toughness and fracture behaviour of these steels.