Effects of Cu Content on Mechanical and Magnetic Properties of High‐Strength Nonoriented Silicon Steel

Abstract

Drive motors for new energy vehicles require nonoriented silicon steel with high strength and excellent magnetic properties, which are always difficult to balance. In this study, the effects of Cu content on the precipitates, microstructure, and properties of nonoriented silicon steel are investigated. The results show that a dispersed and coherent nanoscale B2 Cu‐rich precipitates are formed when Cu addition is 0.91 wt%, while ε‐Cu precipitates with large size and low number density are formed with higher Cu addition. The nanoscale B2 Cu‐rich precipitates afford a higher precipitation strengthening contribution than the larger ε‐Cu precipitates via cutting mechanism. Concurrently, the nanoscale B2 Cu‐rich precipitates nominally affect the iron loss deterioration. With increasing Cu content, the average grain size decreased, while the favorable λ texture diminished, and the unfavorable γ texture increased. With the combined effect of the grain size, texture, and precipitates, the iron loss increased first slightly and then significantly with further Cu addition, whereas the magnetic induction gradually decreased. The comprehensive properties of the steel are optimal when Cu addition was 0.91 wt%, which yielded a yield strength of 571.2 MPa, an iron loss P1.0/400 of 20.05 W kg−1, and a magnetic induction B5000 of 1.621 T.