Secondary Recrystallization Behaviors of Grain-Oriented 6.5 wt% Silicon Steel Sheets Produced by Rolling and Nitriding Processes

Abstract

By rolling and nitriding processes, 0.23- to 0.3-mm-thick grain-oriented 6.5 wt% silicon steel sheets were produced. The core losses of grain-oriented 6.5 wt% silicon steel at frequencies ranging from 400 Hz to 20 kHz were lower than that of the grain-oriented 3 wt% silicon steel with the same thickness by 16.6–35.8%. The secondary recrystallization behavior was investigated by scanning electron microscopy, energy-dispersive spectroscopy, and electron backscattered diffraction. The results show that the secondary recrystallization in high-silicon steel sheets develops more completely as the nitrogen content increases after nitriding, secondary recrystallized grain sizes become larger, and the sharpness of Goss texture increases. Because more \(\left\{ {110} \right\}\left\langle {116} \right\rangle\) grains in the subsurface and the central layer of the sheets have a lot of 20°–45° high-energy boundaries in addition to Goss grains, \(\left\{ {110} \right\}\left\langle {116} \right\rangle\) can be the main component through selective growth during secondary recrystallization when the inhibitor quantity is not enough and inhibitor intensity is weaker. The increases in nitrogen content can increase the inhibitor intensity and hinder abnormal growth of a mount of \(\left\{ {110} \right\}\left\langle {116} \right\rangle\) grains and therefore enhance the sharpness of Goss texture.