Effects of morphology on the mechanical behavior of a dual phase Fe/2Si/0.1C steel

A study has been made on the effects of morphology on the mechanical behavior of a dual phase Fe/2Si/0.1C steel. The coarse dual phase structure obtained by continuously annealing in the two phase region directly from the austenite region results in poor elongation ductility with relatively high strength. However, upon obtaining a fine fibrous or fine globular dual phase structure by following different transformation paths, significant improvements occur in elongation ductility without much sacrifice in strength. The poor elongation ductility of the coarse dual phase structure is due to the initiation of cleavage cracks in the ferrite region where maximum localized stress concentration took place. But, in steels with both fine fibrous or globular morphologies, fracture occurred by void nucleation and coalescence after large amounts of plastic deformation.