Laser scribing of electrical steels reduced core losses through magnetic domain refinement that occurred when thermal stresses were induced by laser heating. An experimental study with a 15 W, continuous wave diode laser for scribing and a finite element simulation model for determining the thermal stress distribution of cold-rolled, 3% silicon-steel were performed. The results showed that the maximum core loss reduction was attained only when the stresses reached the yield strength. In contrast, previous researchers attributed the maximum core loss reduction to the localized plastic deformation. This study also provided quantitative distribution of stresses in all three directions and clarified a controversy surrounding the type of stresses in the laser-scribed and rolled directions.

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