Effect of punching edge deformation on the magnetic properties of Fe49-Co49-V2 alloy

Abstract The rotor and the stator of electrical machines consists of an assembly of soft magnetic laminates typically fabricated by punching from the thin sheets. In this work, the effect of edge deformation on the magnetic properties of laminates resulting from the punching of Fe49-Co49-V2 alloy thin sheets is investigated. Ring samples with varying circumference to area ratios, defined by a CTAR index, were made by punching and subsequently annealed to optimize the magnetic properties. The magnetic properties of the annealed samples were investigated for its correlation with the microstructure. It was found that the magnetic performance of Fe49-Co49-V2 alloy decreases with increasing volume of edge deformation, corresponding to an increasing CTAR index. The deterioration in the magnetic properties can be attributed to the high density of recrystallized grains along the edges of the Fe49-Co49-V2 samples. These recrystallized grains are significantly smaller than those away from the edges and pose a higher degree of restriction to the magnetic domain wall movement. The decrease in magnetic properties from edge damage can be mitigated by increasing the annealing time to allow for grain growth at the edges.