Grain-oriented silicon steel (GOSS) is a key soft
magnetic material used in electrical devices such as motors and transformers.
Optimizing its magnetic properties remains a research focus in materials
science and electromagnetics. Magnetic domain morphology, a critical factor
influencing magnetic properties, directly determines the key characteristics of
silicon steel, including saturation magnetic flux density (
B800)
and core loss, thereby impacting its energy efficiency in practical
applications. Therefore, elucidating the intrinsic relationships among domain
morphology, crystallographic orientation, and magnetic properties is important
for developing high-performance silicon steel. However, current research
predominantly focuses on local domain observations, while the relationships
among large-area domain morphology, crystallographic orientation, and
macroscopic magnetic properties are rarely studied. To address this gap, the
large-area domain morphology, fine microscale domain structures, and
crystallographic orientations of GOSS were systematically investigated using
large-scale domain observation method (Bitter method) combined with
forescatter detector domain imaging and electron
backscatter diffraction. The relationships between domain structures and
magnetic properties, including
B800 and iron loss, were
thoroughly examined. The results show that increasing both the area fraction of
180° primary domains with less than 2° deviation from the rolling direction and
the average width of the primary domains enhances
B800 while
reducing iron loss. Moreover, smaller average in-plane deviation angle (
α)
and out-of-plane deviation angle (
β)
of the ⟨100⟩ easy-magnetization axis
from the rolling direction or rolling plane, as well as more concentrated
α and
β distributions, are associated with higher
B800 and lower iron loss. Furthermore, the presence of island grains and
fine-grained microstructures possibly leads to a decrease in
B800 and an increase in iron loss. Microdomain observations and crystallographic
orientation analyses reveal that low-angle grain boundaries do not impede
domain transfer and that wedge-shaped domains form near boundaries with
increasing misorientation. Additionally, unlike low-angle grain boundaries, high-angle
grain boundaries completely block domain transfer. The orientations of both
island grains and fine grains substantially deviate from the Goss texture,
typically forming high-angle grain boundaries with surrounding coarse secondary
recrystallized grains. The magnetic domains within these finer grains—primarily
supplementary domains such as strip and lancet domains—obstruct the movement of
180° primary domains during magnetization, thereby degrading the overall
magnetic properties of the material.
