The solidification process of Fe-C alloys consisting in part of non-magnetic constituents, is influneced by the action of spatially travelling electromagnetic fields which alternate in direction. This is done by treating heavy thickwalled castings with one or more linearly progressing electromagnetic travelling fields having a frequency of between 0.5 and 10 Hz and a wave length of over 0.8 mm, the travelling direction of which is periodically altered. Pref. the inductor is disposed parallel to the ingot-axis in the lower mould region, the mould consisting of a non magnetic material in this region. The treatment effects a stirring action in the solidifying melt, resulting in reduction of temp. and concn. gradients, finer structure and more non-metallic inclusion distribution.
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