In this study, the effect of the hot-cold rolling process on the evolution of the microstructure, texture and magnetic properties of strip-cast non-oriented electrical steel was investigated by introducing hot rolling with different reductions. The results indicate that hot rolling with an appropriate reduction, such as the 20% used in this study, increases the shear bands and {100} deformed microstructure in the cold roll sheet. As a result, in our study, enhanced η and Cube recrystallization texture and the improved magnetic induction were obtained. However, hot rolling with excessive reduction (36–52%) decreased the shear bands and increased the α-oriented deformation microstructure with low stored energy. It enhanced the α recrystallization texture and weakened the η texture, resulting in a decrease in the magnetic induction. In addition, hot rolling promoted the precipitation of supersaturated solid solution elements in the as-cast strip, thereby affecting the subsequent microstructure evolution and the optimization of its magnetic properties.

Figure 15. Values of a) magnetic induction B 50 and b) core loss P 15/50 for the samples subjected to different annealing process.

In order to improve the {100} recrystallisation texture of non-oriented electrical steel, a pre-recovery annealing process was proposed to regulate recrystallisation behaviour of {100} grains by altering the structure and stored energy of deformed microstructure. Pre-annealing was conducted at 500°C for 0–90 min. The microstructural and textural evolution was carried out by optical microscopy, electron backscattered diffraction and X-ray diffraction analysis. The results indicate that the pre-recovery annealing promotes the formation of large {100} recrystallised grains. With the prolongation of pre-annealing time, the {100} recrystallisation texture expands from Cube to the vicinity of {001}<130>-{001}<110>, and the volume fraction gradually increases. In addition, the changes of recrystallised microstructure are discussed on the basis of strain-induced boundary migration.

No abstract