Effect of cold working and heat treatment on the magnetic properties of iron-silicon alloys

Electrical steels also called Iron-Silicon (FeSi) alloys are used in electrical and magnetic applications due to their excellent magnetic properties, such as high magnetic permeability and low energy dissipation. These characteristics make FeSi alloy an important material in the production of transformers, motors and other electromagnetic devices. The performance of these materials is not only determined by their chemical composition but it is also influenced by their microstructure like the grain size and crystallographic texture. Mechanical deformation processes such as cold working as well as thermal treatments like annealing and recrystallization can drastically alter the magnetic behaviour of FeSi alloys. Cold workning generates strain and defects into the crystal lattice which results in the degradation of the magnetic properties. The subsequent heat treatments, annealing and recrystallization in this study, are employed to restore the properties by reducing dislocation density, relieving internal stresses and promoting grain growth. In this study the variation of the magnetic properties of five different FeSi alloy samples were investigated. The meauserements were carried out before the cold working, after the cold working, after the annealing treatment and finally after the recrystallization treatment. Moreover the attention is focused to the evolution of grain size and its correlation with magnetic performance.