The effect of Si and Al concentration gradients on the mechanical and magnetic properties of electrical steel

Si and Al addition to electrical steel has a beneficial effect on its soft magnetic properties, which are optimal for 6.5 Si wt%. At this concentration the power losses are low and the magnetostriction is almost zero. However, the increase of these alloying elements has two drawbacks: both magnetic saturation and ductility are reduced. The use of materials with a Si and Al concentration gradient appears as an interesting alternative because it presents the advantages of homogeneous 6.5 wt% Si steel without the cited disadvantages. Samples are produced by hot dipping in a Si–Al hypereutectic bath, followed by annealing treatments for diffusion, leading to different concentration profiles. The effect of the Si and Al gradients on the magnetic saturation, hysteresis losses as well as on the tensile stress–strain behaviour are described.