The Influence of Hot Rolling Finishing Temperature on the Structure and Magnetic Properties of 2.0%Si Non-Oriented Silicon Steel

Abstract

Rougher bar samples of 2.0%Si and 0.25%Al Non Oriented Grain with 25mm thickness were rolled to 2.3mm in a pilot reversible mill with temperatures ranging from 920 to 1120°C and processed until the final annealing to study the evolution of grain size and crystallographic orientation. The results showed that higher hot rolling finishing temperature results in larger hot band grain size, but the texture, composed mainly by alpha, gamma, {100} , and eta fibers suffers little effect. As a consequence, after final annealing, an increase of fraction of the grains with eta fiber orientation and a reduction of grains with gamma fiber orientation are observed, improving the magnetic induction. The final grain size decreases with hot rolling finishing temperatures above 1040°C in spite of increasing hot band grain size, deteriorating the core loss results. This was explained by the increasing of shear bands when the grain size prior to cold rolling increases. More shear bands generates more sites for nucleation on recrystallization, then smaller final grain size results. The Goss orientation is generated mainly in the sites inside shear bands. The increasing of prior grain size also increases the fraction of grains with Goss orientation after final annealing and its fraction increases suddenly when the hot rolling finishing temperature achieves 1040°C, supporting that affirmation.