Evolution of Microstructure and Texture in Grain-Oriented 6.5% Si Steel Processed by Rolling with Intrinsic Inhibitors and Additional Inhibitors

Abstract

A grain-oriented steel containing 6.5% Si, characterized by a notable Goss texture, was effectively manufactured through the rolling technique, incorporating both intrinsic inhibitors and additional inhibitors. This investigation focuses on tracking the development of texture and magnetic properties during the manufacturing process and delineates the mechanism underlying secondary recrystallization. The empirical findings clearly demonstrated the significant influence of nitriding duration and quantity on the secondary recrystallization process. In instances where additional nitrogen is absent, the intrinsic inhibitors alone do not lead to secondary recrystallization. However, when the nitriding duration is 90 s and the nitriding amount is 185 ppm, a complete secondary recrystallization structure with a strong Goss texture enables the finished products have excellent magnetic properties. The preferential growth of Goss grains is mainly governed by the enhanced mobility of high-energy (HE) grain boundaries. With the increase in annealing temperature, the occurrence of 20°–45° HE grain boundaries with Goss grains becomes more progressively frequent. At the secondary recrystallization temperature of 1000 °C, the frequency of 20°–45° HE grain boundaries with Goss grains reaches 62.7%, providing favorable conditions for the abnormal growth of Goss grains. This results in a secondary recrystallization structure predominantly characterized by a strong Goss texture. In light of these observations, the present study provides fundamental theoretical insights and serves as a valuable procedural guideline for the industrial manufacturing of 6.5% Si grain-oriented electrical steels.