ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Laser scribing can be used to reduce the ferromagnetic domain size, and thus core loss, in grain-oriented electrical steels. The localized stress required for domain-size control can be produced either by shock deformation, optimally associated with beam dwell times (pulse lengths) less than 2×10−8 sec, or by thermal stressing occurring with dwell times optimally longer than 1×10−4 sec. In this paper we show that comparable core loss improvements can be obtained at greatly different dwell times, but that the associated changes in the surface condition of coated silicon steel laser scribed for maximum core loss reduction vary dramatically as dwell time varies. At the very short times characterizing shock deformation, achieved using a Q-switched solid-state laser, the coating is almost completely removed, but there is little effect on the steel itself, and recoating has been used to restore coating integrity. Under optimum dwell times for thermal expansion effects, achieved using continuous-wave radiation, there is no significant effect on the coating, and no postscribing treatment is required. At intermediate dwell times, however, significant core loss reduction is associated with extensive disruption of the coating and with melting of the steel. At dwell times of approximately 1×10−6 sec using CO2 laser radiation, there is an unstable transition between the shock (vaporization) and heating modes, with intermittent melting.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.334615
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