Interphase precipitation in vanadium-alloyed steels: Strengthening contribution and morphological variability with austenite to ferrite transformation

The evolution of characteristic features of interphase precipitation in steels with progressive of austenite-to-ferrite transformation is analyzed from both experimental and modeling approaches. The model developed describing the time and temperature evolution of sheet spacing and particle spacing shows good agreement with the experimental data. The interactions between the transformation and interphase-precipitated carbides are discussed, and particular attention is paid to the occurrence of fibrous carbides. It is suggested that the ease of interface motion is the main factor controlling its appearance. Finally, the local strengthening in a single ferrite grain containing different precipitation states is analyzed by nanoindentation and compared with the theoretical calculations. The evolution of strengthening induced by interphase precipitation with the microstructural parameters is then discussed.