Abstract
1·4–1·7C–1·9–2·3Si steels melted in open atmosphere in an induction furnace and cast in dry sand moulds were found to solidify with nodular graphite and varying proportions of pro-eutectoid carbide. The pro-eutectoid carbide could be broken down by a short normalizing treatment. These steels could be ferritized by both subcritical annealing and quench-temper treatments. The microstructures and annealability of the steels were found to be influenced by minor additions of elemental zinc, bismuth, or sulphur to the melt just before pouring. SEM examination of deep etched-samples of the steels revealed that the graphite particles were hollow. It is suggested that the graphite in the as-cast samples was nucleated in the liquid state on gas bubbles.
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