High-Strength Nonoriented Electrical Steel with Excellent Magnetic Properties Accomplished by Cu-Ni Multialloying

Nonoriented electrical steel for new energy vehicles should have high strength and excellent magnetic properties simultaneously. However, it is challenging to optimize mechanical and magnetic properties simultaneously during nonoriented electrical steel processing. This article prepares nonoriented electrical steel with high strength and excellent magnetic properties by Cu-Ni alloying, and the evolution of properties of Cu-Ni-alloyed nonoriented electrical steel during aging and underlining mechanisms is studied. The optimal strength is achieved when aging for 10 min with a yield strength of 773 MPa, where the magnetic induction intensity (B50) is 1.66 T, and the iron loss (P1.0/400) is 18.07 W Kg-1. The optimal strength is attributed to the Cu-Ni recombination, which induces a rapid precipitation of numerous small-sized Cu-rich phases within a short period. Besides, the main strengthening mechanisms of the small-size Cu-rich phases are modulus strengthening and ordered strengthening. Furthermore, the small-size Cu-rich phases with B2 and body-centered cubic structure in the earlier aging period do not deteriorate the magnetic properties of the steel. Nevertheless, in the late aging period, due to the coarsening of the precipitated Cu-rich phase with face-centered cubic structure and the abnormal growth of some grains, the eddy current loss increases, leading to worsen magnetic properties. This study successfully produces a nonoriented electrical steel with a yield strength of 773 MPa, where B50 is 1.66 T, and P1.0/400 is 18.07 W kg-1. This optimal strength is attributed to the Cu-Ni recombination, which induces a rapid precipitation of numerous fine coherent Cu-rich phases within a short period. Importantly, these precipitates do not deteriorate the steel's magnetic properties.image (c) 2024 WILEY-VCH GmbH