Effect of deformation parameters on microstructural evolution during hot compression of Nb–V–Mo microalloyed steel

Abstract The flow behavior of Nb–V–Mo microalloyed steel at different deformation parameters was investigated using isothermal compression tests. The microstructures of the specimens after deformation were observed through the use of a metallographic microscope. The results indicated that the deformation temperature had a significant effect on the grain size of the deformed specimen and the average size of grains increases with corresponding increase in temperature in the range of 800 °C–1100 °C. The dislocations and substructures of the specimens after deformation were characterized using TEM. The bulged grain boundary was observed through TEM when the specimen was deformed at 1100 °C and 1 s−1. The effect of the strain rate on the dynamic recrystallization behavior was investigated using electron backscatter diffraction (EBSD). The EBSD results indicated that the fraction of low-angle grain boundaries decreased with a corresponding decrease in strain rate, and the average sub-boundary misorientation increased with a decreasing strain rate. The continuous dynamic recrystallization mechanism was determined through EBSD analysis.