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Nowadays, optimization of non-oriented (NO) electrical steels toward lower iron-loss, improved, and isotropic magnetizability is critical to the improvement of rotating electrical machines. The whole production process chain adjusts the microstructure evolution, e.g., grain size and crystallographic texture, determining the magnetic properties. In particular, the interdependence of raw material properties and the resulting mechanical stress distribution during final assembly, e.g., punching, leading to magnetic property deterioration is crucial for the optimization of NO steel properties of rotating machines. This paper studies the effect of different cold rolling strategies, annealing treatments, and sheet metal blanking (punching) regarding microstructure evolution, magnetic properties, and deterioration. [ABSTRACT FROM AUTHOR]

In this work the microstructure development during annealing of AZ31 sheets processed by equal channel angular pressing (ECAP) is presented. Samples with dimensions of 200 × 200 × 1.8 mm 3 were processed in a single ECAP pass at 225 °C using a channel angle of 130°. Subsequent isothermal and isochronal heat treatments were used to reveal the microstructure stability of the ECAPed sheets at temperatures between 180 and 300 °C. A systematic analysis of the microstructure development was conducted using optical microscopy and electron backscatter diffraction (EBSD). It was found that a texture modification produced by the profuse activation of 10 1 - 2 extension twinning during ECAP is lost during annealing as a result of thermal detwinning. Moreover, a bimodal microstructure composed by small and coarse grains was observed at 250 °C and 300 °C as a result of the fast growth of a few grains. The reason for the selective grain growth is related with the activation of strain induced grain boundary migration which was stimulated by the large stored strain contained in the as-ECAP processed sheets. The dissolution of Mg 17 Al 12 particles during annealing is also seen as a possible factor for the onset of rapid grain growth. [ABSTRACT FROM AUTHOR]

The microstructure, texture development and mechanical properties of AZ31 magnesium alloy sheets processed by equal channel angular pressing (ECAP) were investigated in this work. The results were correlated with the forming behavior at room temperature after single ECAP pass at different processing temperatures. A novel tool was developed for the implementation of ECAP to deform sheets with dimension of 200 × 200 × 1.8 mm 3 . ECAP trials were carried out successfully at three temperatures of 175, 200 and 225 °C using a channel angle of 130°. After the ECAP process, significant grain refinement and texture changes occurred in the AZ31 sheets. In particular, dynamic recrystallization was observed in the ECAPed sheets at 225 °C. The tensile tests at room temperature showed that uniform elongation along the pressing direction (PD) increased with increasing processing temperature. The highest uniform strain at room temperature was 17.6% in the ECAPed sheet at 225 °C. Forming tests of a U-channel section at room temperature revealed that the drawing depth of the ECAPed sheet at 225 °C was improved by more than 50% as compared with the as-rolled condition. [ABSTRACT FROM AUTHOR]