The Effect of TiO2 Nanoparticle Adding on Inclusion and Microstructure

Abstract A mixture consisting of TiO 2 nanoparticles and pure iron powder was directly added into molten steel, and its effects on inclusion and microstructure have been studied. Through a scanning electron microscope (SEM) and an Energy Dispersive Spectrometer (EDS), Ti-containing inclusions, in which the elements of Si, Mn and Al co-existed, were observed. Moreover, compared with the non-treated sample, statistical results indicated that the inclusion in the treated sample was refined and its number per unit area increased by 50 %. These phenomena meant the adding validity of TiO 2 nanoparticle, and may be due to the decomposition reaction of TiO 2 and the higher Gibbs free energy of the nanoparticles. After etching, it was found that the Ti-bearing inclusions can induce intragranular acicular ferrite nucleation. This appearance was consistent with the Ti-containing inclusion introduced through the internal precipitation method.