Scalable molten salt electrochemical siliconizing tailors texture in silicon steel for superior electromagnetic properties

The 6.5 wt%Si silicon steel is an ideal electromagnetic material for generating, transmitting, and utilizing electricity with near-zero energy loss, but its production remains a big challenge due to rolling fracture in traditional steelmaking process. Herein we propose a scalable molten salt electrolysis process to produce 6.5 wt%Si silicon steel by electrochemical siliconizing in 1 wt%Si silicon steel. Silicon ions in molten salt was electrodeposited to form a 13 wt%Si Fe₃Si alloy layer in the 1 wt%Si silicon steel, followed by heating for facilitating silicon uniform diffusion to obtain 6.5 wt%Si silicon steel. The electrodeposited silicon caused lattice distortion near cube-oriented grains, further inducing the texture selective transformation from initial γ-fiber texture into cube texture with superior electromagnetic property. Consequently, 1000A-level molten salt electrolysis operation was performed to continuously produce large-sized 6.5 wt%Si silicon steel sheets with thickness of 0.35 mm and 0.60 mm (length: 50 cm, width: 25 cm), which achieved record-breaking electromagnetic properties with high magnetic flux density (B₈) of 1.38 T and1.42 T, as well as low iron loss (P_2/5000) of 11.8 W/kg and 20.6 W/kg, respectively. This molten salt electrolysis process avoids brittle failure of silicon steel and precisely regulates its texture, providing a feasible route for industrial production of high-performance 6.5 wt%Si silicon steel.