Analysis of the phenomena of non-Fourier heat conduction in switch-Q laser processing for reducing the core loss of grain-oriented silicon steel

In a previous study, it was found that the core loss of grain-oriented silicon steel sheets can prominently be reduced substantially by means of switch-Q laser processing: however, their coating is inevitably damaged. The experimental studies in the present paper were conducted to observe and analyse the effect of switch-Q laser processing on the domain structure, the metallographic structure and the core loss of the sheet. Two phenomena have been discovered that are difficult to explain: (i) the coating is more easily damaged; and (ii) the depth of the dislocation is much greater than predicted by means of conventional Fourier heat conduction. The two problems have been analyzed and explained by the non-Fourier heat conduction approximation. (C) 1998 Published by Elsevier Science S.A.