Study of the Simultaneous Effects of the Hot Band Grain Size and Cold Rolling Reduction on the Structure and Magnetic Properties of Nonoriented 3% Si Steel

The simultaneous effects of the hot band grain size and cold reduction on the final grain structure, texture and magnetic properties of 3% Si steel were studied by variation of finishing temperature and hot band thickness during hot rolling, followed by cold rolling to final thickness and annealing in H₂/N₂ atmosphere. The results have shown that there is an optimum combination of hot band thickness and hot band grain size for maximum Eta/Gamma ratio and better magnetic properties (B₅₀ and W_1.5/60) after final annealing. For the thicker hot band, it was observed that higher finishing temperature, or larger hot band grain size, was necessary to achieve high Eta/Gamma and better magnetic properties. Too large hot band grain size, however, could result in smaller final grain size due to the intense nucleation on recrystallization in the shear bands and consequently poor core loss values. This behavior was explained based on the hot band grain structure and cold rolling effects on the texture evolution.