Effect of rolling temperature on the recrystallization behavior of 4.5 wt.% Si non-oriented electrical steel

Abstract

A 4.5 wt.% Si non-oriented electrical steel with a thickness of 0.50 mm was prepared following a conventional process route. Due to the insufficient formability of high-Si steels, this study focuses on the effect of warm rolling temperature on the evolution of microstructure and texture in the hot-rolled sheet after appropriately selected annealing process. The optical microscope (OM) and field emission scanning electron microscope (SEM) with EBSD equipment were utilized to characterize the microstructure evolution during the fabrication process. The results show that the warm rolling temperature significantly impacts the evolution of the microstructure and texture of the 4.5 wt.% Si steel. When rolling at a lower temperature, shear bands appeared within the plate. The shear band vanished as the rolling temperature increased, and obvious delamination can be observed. When further increasing the temperature, the dynamic recrystallization occurred on the surface layer of the plate. The increase of the warm rolling temperature reduced the average grain size after final annealing, and the structural delamination was more obvious. The microstructural characteristics of the warm-rolled sheet affect the subsequent evolution of the texture. Affected by shear bands and delamination, different warm-rolled sheets have different recrystallization textures after final annealing.

Keywords

• 4.5 wt.% Si non-Oriented electrical steel
• Warm rolling
• Microstructure
• Texture
• Recrystallization