Microstructural evolution of a niobium-microalloyed steel during hot shear deformation and subsequent cooling

For the purpose of obtaining a niobium-microalloyed steel with a preferable ultrafine-grained ferrite microstructure, a thermomechanical controlled processing (TMCP) strategy that included a hot shear deformation conducted near the local phase transformation temperature and a subsequent cooling process is proposed. As a large plastic strain was enforced by the simple hot shear deformation, severe plastic deformation (SPD) of the...