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Grain oriented electrical steels (GOES) produced by the AlN + Cu technology usually contain ca 0.5 wt. % of Cu. Evolution of microstructure during the final high temperature annealing of GOES is strongly affected by microstructural changes during the individual steps of industrial production process. Inhibition phases, AlN and sulphides, are expected to play an important role in the formation of the final Goss texture.This paper deals with TEM characterization of sulphides in Cu – bearing GOES after basic steps of industrial production process: hot rolling, decarburization annealing (DCA) and high temperature annealing (HTA). In specimens after hot rolling only sulphides of manganese and complex sulphides of manganese containing, a small fraction of copper were identified. Typical size of these sulphides reached several hundreds of nanometres. These results prove a low solvus temperature of Cu rich sulphides in GOES. Re-precipitation of copper-rich sulphides was observed after decarburization annealing. Due to low temperature of precipitation, typical size of these sulphides reached only several tens of nanometres. Apart from complex sulphides of copper and manganese, fine Cu2S particles were detected. In the paper the effect of Cu – bearing sulphides precipitation on the formation of other minor phases is discussed. Heterogeneous nucleation of AlN particles on fine sulphides was often observed. During high temperature annealing all sulphides gradually dissolved.
Keywords: GOES, precipitation processes, sulphides© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.