EFFECT OF SOLUTE CARBON PRESENT DURING COLD-ROLLING AND ANNEALING ON THE MAGNETIC-PROPERTIES OF ELECTRICAL STEELS

Fully processed (FP) electrical steels benefit from vacuum degassing t hanks to the improved cleanliness and the superfluity of decarburisati on during annealing. On the other hand, it is known from research on d eep drawing steels [1], that lowering the carbon content by vacuum deg assing significantly increases the intensity or (magnetically unfavour able) {111}-grains in the final product. In this paper, it is shown fo r three FP-steels with Si-contents between 0 and 1.8 wt% that a higher amount of solute carbon (C-s) present during cold rolling and anneali ng results in an increase of the magnetic polarisation measured in the rolling direction. The polarisation in the transverse direction is al most independent of C-s and so are the eddy current and hysteresis los s. The observations can be explained by the fact that solute carbon pr omotes a higher intensity of magnetically favourable Goss grains and i n a lower intensity of {111}-grains. The current study implies that in non-degassed steels, carbon can be used to improve the magnetic polar isation, provided coiling after hot rolling retains sufficient carbon in solution. For degassed steels. this work shows that there is no rea son to reduce the C-content below the 30 ppm limit for prevention of m agnetic ageing.