Formation of fine intragranular ferrite in cast plain carbon steel inoculated by titanium oxide nanopowder

The effect of titanium oxide nanopowder on the microstructure of a plain carbon steel was studied. Remelted base steel showed a microstructure consisting of coarse pearlite and minor allotriomorphic ferrite. After inoculation, the volume fraction of ferrite increased considerably. Further, the ferrite was grain-refined down to about 3 μm in the as-cast condition. Carbon oxidation during melting is proposed to thermodynamically favor a higher volume fraction of ferrite. Titanium oxide nanoparticles refine ferrite grains presumably by virtue of augmented nucleation and retarded growth.