Abstract:Ferritic steel with a nominal composition of Fe−14Cr−3W−0.42Ti−0.32Y was prepared by mixing gas-atomized prealloyed powder and mechanically alloyed powder. The microstructure is much different from other ferritic steels with the same composition and prepared via only mechanically alloyed powder. A bi-modal structure, which consists of pure ferritic grains and martensitic grains, was obtained after hot forging and air cooling. A phase transformation of α_bcc→γ_fcc→α´_bcc was also discovered in microstructural observation. The bi-modal microstructure shows a good combination of high strength and high ductility.

Key words: ferritic steel; powder metallurgy; phase transformation; bi-modal microstructure; mechanical property