EVALUATION OF THE SUSCEPTIBILITY OF AN ELECTRICAL STEEL TO MAGNETIC AGING USING A NEW INTERNAL-FRICTION TECHNIQUE

Magnetic aging of a low grade of grain non-oriented electrical steel c ontaining a total carbon content of 100 ppm was evaluated as a functio n of interstitial carbon content. The interstitial carbon content was altered by annealing at 400-degrees-C for different times and measured using a new internal friction technique. A very good correlation was found between the amount of interstitial carbon and the increase of th e core loss due to magnetic aging at 225-degrees-C. Magnetic aging dec reases linearly from 3.2 W/kg for 50 ppm interstitial carbon to 0.5 W/ kg for 17 ppm carbon. From the study of the precipitation kinetics at 400-degrees-C it can be concluded that the overaging section of a cont inuous annealing and processing line is not effective in reducing the magnetic aging of a non-decarburized steel.