Effects of High-Temperature Annealing Atmosphere on the Secondary Recrystallization Behavior and Magnetic Properties of Fe-3.2%Si-0.055%Nb Grain-Oriented Silicon Steel

High-temperature annealing is a key step for the secondary recrystallization of grain-oriented silicon steel, which has an important effect on the final sharp Goss texture. In this work, the effects of three different annealing atmospheres during high-temperature annealing (100%H(2), 25%N(2) + 75%H(2) and 50%N(2) + 50%H(2)) on the secondary recrystallization microstructure and texture of Fe-3.2%Si-0.055%Nb low temperature grain-oriented silicon steel were analyzed by optical microscopy (OM) and electron back-scattered diffraction (EBSD) techniques, and the magnetic properties of the samples were compared. The results show that when the high-temperature annealing atmosphere is 100%H(2), the texture of the grains with secondary recrystallization is mainly <110>//ND orientation, but the grains without secondary recrystallization have a disordered orientation. When the high-temperature annealing atmosphere is 50%H(2) + 50%N(2), the secondary recrystallization grains present a Goss texture and brass texture. After high-temperature annealing in the 25%N(2) + 75%H(2) atmosphere, the sample can be fully recrystallized to obtain secondary recrystallization grains; the grain size is relatively uniform and the texture is mainly a Goss texture with a sharp edge. The content of this reaches 93.1%, the magnetic induction B(800) is the highest, reaching 1.89 T, and the iron loss P(1.7/50) is the lowest, reaching 1.33 W/kg.