Investigation of the structural, electronic and mechanical properties of Ca-SiO2 compound particles in steel based on density functional theory

Ca-SiO2 compounds compromise one of the most common series of oxide particles in liquid steels, which could significantly affect the service performance of the steels as crack initiation sites. However, the structural, electronic, and mechanical properties of the compounds in Ca-SiO2 system are still not fully clarified due to the difficulties in the experiments. In this study, a thorough investigation of these properties of Ca-SiO2 compound particles in steels was conducted based on first-principles density functional theory. Corresponding phases were determined by thermodynamic calculation, including gamma dicalcium silicate (gamma-C2S), alpha-prime (L) dicalcium silicate (alpha '(L)-C2S), alpha-prime (H) dicalcium silicate (alpha '(L)-C2S), alpha dicalcium silicate (alpha-C2S), rankinite (C3S2), hatrurite (C3S), wollastonite (CS), and pseudowollastonite (Ps-CS). The results showed that the calculated crystal structures of the eight phases agree well with the experimental results. All the eight phases are stable according to the calculated formation energies, and gamma-C2S is the most stable. O atom contributes the most to the reactivity of these phases. The Young's modulus of the eight phases is in the range of 100.63-132.04 GPa. Poisson's ratio is in the range of 0.249-0.281. This study provided further understanding concerning the Ca-SiO2 compound particles in steels and fulfilled the corresponding property database, paving the way for inclusion engineering and design in terms of fracture-resistant steels.

Automated summary

In this study, the structural and mechanical properties of Ca-SiO2 compounds in liquid steels were investigated using first-principles density functional theory. Eight different phases were identified and their stability and properties were determined. The results provide valuable insights into the Ca-SiO2 compound particles in steels and contribute to the development of a corresponding property database.