Silicon steels are the preferred materials to manufacture cores of electrical machineries primarily due to low core loss. Addition of silicon increases resistivity of steel and thereby, reduces core loss to a great extent. This work involved two high silicon (~3.1 wt%) steels with similar silicon content, namely grain oriented (GO) and non grain oriented (NGO) silicon steel. Major difference between compositions of these two grades was carbon content. GO grade contained 0.06 wt.% carbon and NGO grade had insignificant level of carbon (30 ppm). Because of higher carbon, GO grade had some amount of austenite phase in the hot working temperature range of this steel, while NGO did not show any transformation to austenite phase in the same temperature range. This was also confirmed in dilatometry experiments and optical microscopy of the quenched specimens. Hot deformation (Plane strain compression) experiments, performed using Gleeble 3800 thermo-mechanical simulator, showed significant difference in the evolution of hot deformed microstructure and texture in these two steels (Figure 1). NGO showed dynamic recovery, evident from the presence of low angle grain boundaries and subgrain formation. The GO showed clear grain refinement, largely, in the region of ferrite grains, near the austenite phase. 

Effect of Hot band annealing (HBA) on the post hot rolled microstructure was also explored. HBA appeared to facilitate grain interior strain localization in subsequent cold rolled microstructure. As a result of this, more uniform distribution of recrystallized Goss grains was observed in the primary recrystallized microstructure.