Oriented 3% silicon-iron with high magnetic permeability is used to produce laminations for the cores of electrical transformers. This steel is made up of magnetic domains whose wall movements can contribute significantly to the anomalous eddy current loss in the core of the transformer. This loss can be minimized by control of the magnetic domain size. This is accomplished through a final processing step consisting of refinement of the domain size by introducing dislocations in the microstructure to cause new domain walls to form. A finely focused laser beam is scanned across the material surface to introduce the dislocations via a thermal shock to the microstructure.
© 1984 Optical Society of AmericaPDF Article