Different formation mechanisms of {210} orientation in η fiber texture of ultra-thin grain-oriented silicon steel using quasi-in-situ analysis method

Abstract

Using high-permeability grain-oriented silicon steel as starting material, an ultra-thin grain-oriented silicon steel was prepared by the primary recrystallization method, which was mainly composed of strong η fiber (<100>//RD) texture including major Goss ({110}<001>) component, a certain amount of {210}<001> component and a few Cube ({100}<001>) grains. In this study, the formation of η fiber texture, especially the {210}<001> component, was analyzed by a quasi-in-situ analysis method. The results show that the {210}<001> texture exists in two forms. The first type, characterized by some {210}<001> grains distributed in Goss grain colony, is common in the product. The texture originates from exact Goss initial grain, and the {210}<001> nuclei are mainly observed in shear bands of {111}<112> rolling texture. The {210}<001> nuclei are mainly distributed in the surface and subsurface layers and are formed by roller friction. The second type is a sharp {210}<001> texture together with a few scattered Cube grains. After rolling, large {210}<001> initial grain rotates toward {112}<241> deformation texture, which is swallowed by transition bands composed of many {210}<001> nuclei and a few Cube nuclei during annealing. This is because the transition bands act as principal sites for nucleation. A few Cube grain clusters originating from {210}<001> initial island grains are observed, and the Cube nuclei are formed by a strong rotation effect of initial grain boundaries. Due to the high-angle boundaries with Goss grains, the {210}<001> grains grow abnormally at higher temperature, and the magnetic properties deteriorate because of large deviation angle of <001> axis from the rolling direction.