The Effect of TiO2 Nanoparticle Adding on Inclusion and Microstructure

Abstract

Abstract A mixture consisting of TiO2 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 TiO2 nanoparticle, and may be due to the decomposition reaction of TiO2 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.