Correlating magnetic properties of ferritic NO electrical steel containing 2.4 m.%Si with hot strip microstructure

Understanding the interdependencies of the processing steps of high silicon containing non-oriented (NO) electrical steel is a key factor for improving its final magnetic properties. Moreover, every process step in the production has a significant impact on the properties. Steels with a high silicon content are ferritic (α-Fe). Accordingly, the microstructure and texture are inherited from one processing step to the next. The presented research relates the hot strip microstructure and texture to the magnetic properties of the final annealed material. To investigate the impact of hot strip microstructure and texture for a ferritic 2.4 m.%Si silicon containing steel, the material was hot rolled from an initial thickness of 64 mm down to a thickness of 1 mm whereby different microstructures and textures were achieved by varied hot rolling conditions. Subsequently, the material was cold rolled to 0.25 mm and annealed at 800 °C or 1000 °C for 3 min. Finally, samples of each processing step were analyzed by means of light microscopy and XRD texture measurements. Samples after hot rolling and final annealing were tested in a single sheet tester for specific losses and magnetic polarization. Findings show an influence of the initial hot strip microstructure on the microstructure and magnetic properties of the final annealed samples.