Effect of rare earth Yttrium on the tensile properties of 6.5%Si steel

Fe-6.5wt%Si alloy shows potential for a broad application with excellent soft magnetic properties including high permeability, low iron loss, and near-zero magnetostriction. However, brittle-ordered B2 and DO₃ structures hinders its mass production and applications. In this work, the effect of Y element on the tensile properties of Fe-6.5wt%Si alloy at 200~800 ℃ was investigated. A detailed study of the Y element in the microstructure and ordered structure of Fe-6.5wt%Si was carried out by EBSD, EPMA, XRD and TEM. Results showed that Y₂O₃ and Y₂O₂S precipitates as the efficient nucleation agents refined the microstructures. Adding Y not only refined the ordered domains, but also reduced the ordered phase contents, ordered degrees, and hardness. The fracture elongation of high silicon steel with 0.03% Y at 200~600 ℃ was higher than that of high silicon steel without Y. The tensile strength of high silicon steel containing 0.03% Y was higher than that of high silicon steel without Y at 200~400 ℃. The grain refinement and ordered degree reduction caused by the addition of rare earth Y in Fe-6.5wt%Si alloy were the important reasons for its improvement in ductility.