Evolution of microstructures in high and low Ti/Al ratio ferritic stainless steels after hot rolling

Abstract

The evolution of microstructures after hot rolling was studied on high and low Ti/Al ratio ferritic stainless steels. The steels were hot rolled using the Gleeble 1500D® thermomechanical simulation machine. The evolution of the microstructures was compared using the electron backscattered diffraction (EBSD) mode of scanning electron microscope (SEM) and optical microscopy (OM) methods by studying the grain sizes and recrystallization after hot rolling. The results showed that after hot rolling, the grain structure of the high Ti/Al ratio steel was more pancake like and smaller with high volume fraction of recrystallized grains. These recrystallised grains were mostly localised around TiNb(C,N) particles, which suggested particle stimulated nucleation (PSN) of grains. It was therefore seen that PSN occurred in both steels and therefore there was supposed fine grains and improved texture in both steels but the initial grain size prior to deformation overrides the effect of occurrence of PSN. Starting deformation with fine grained material yields higher recrystallization microstructures and textures.