The Influence of Fiber Laser Pulse Processing on Coercivity and Nanohardness of Fe-3.2Si Grain-Oriented Electrical Steel in relation with its Surface Changes and Magnetic Domains Modifications
V. Puchý, L. Falat, F. Kováč, I. Petryshynets, R. Džunda and M. Šebek
Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 04001 Košice, Slovak Republic
Received: December 6, 2015; In final form: April 14, 2017
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Fiber laser scribing of Fe-3.2Si grain-oriented electrical steel was carried out using three different laser pulse regimes, namely a single pulse laser regime, multipulse laser regime and multipulse laser regime with modulation of laser pulses. The samples were tested for coercivity and nanohardness before and after laser processing. Clear improvements in soft magnetic characteristics were observed for all the regimes using the lowest single pulse energy of 0.6 mJ. The best improvement i.e. the most significant decrease in coercivity was obtained after the regime with 5 pulses. Further increasing in both pulse energy and pulse number resulted only in detrimental effects on both magnetic and mechanical characteristics. Introduction of 50 kHz pulse modulation within 100-pulse laser regimes resulted in lower coercivity values in comparison with the same regimes without modulation. The major effects responsible for the observed improvement are related to optimal refinement and rearrangement of magnetic domains determined by the balance of laser-induced residual stresses and plastic deformation at the surface of the treated material. Thus the fiber laser pulse processing has been recognised as a useful and energy efficient tool in obtaining electrical steels for power transformers with lower core losses.

DOI: 10.12693/APhysPolA.131.1445
PACS numbers: 61.80.Ba, 81.05.Bx, 81.40.Rs, 81.40.-z, 75.60.Ch, 79.20.Eb