Microstructure, texture and precipitate of grain-oriented 4.5 wt% Si steel by strip casting

Abstract

A 0.23mm grain-oriented 4.5wt% Si steel sheet was prepared by strip casting, hot rolling, one-stage warm rolling, primary annealing and secondary annealing. A detailed study of microstructure, texture and precipitate was carried out by methods of OM, EBSD, XRD and TEM. It was found that the as-cast strip exhibited equaxied microstructure with random orientation, enabling the fine and homogeneous primary microstructure to be obtained after one-stage warm rolling. After hot rolling, weak Goss texture was observed, which could not act as Goss seed. In contrast, the Goss seed was found to originate within the shear bands in {111}〈112〉 grains during warm rolling. Another finding was that the precipitates was suppressed during strip casting due to the rapid solidification and subsequent cooling rate, and mainly precipitated during hot rolling. After secondary annealing, abnormal Goss grains evolved sufficiently, and showed prominent properties. The B8 was 1.73T, which was similar to 1.85T for grain-oriented 3.0wt% Si steel, and the core losses were low than the grain-oriented 3.0wt% Si steel and non-oriented high silicon steel.