Role of CaO/SiO2 Ratio Upon Inclusion Characteristics of EH36 Shipbuilding Steel Treated by CaF2–MnO–CaO–SiO2 Fluxes

This study delves into the role of the CaO/SiO2 ratio in CaF2–MnO–CaO–SiO2 fluxes on the inclusion characteristics of EH36 shipbuilding steel welds. The research focuses on how varying this ratio affects the composition, number density, volume fraction, and size distribution of oxide inclusions, which are crucial for the mechanical properties of the weld metal. The findings reveal that increasing the CaO/SiO2 ratio reduces the oxygen content in the weld metal, leading to a decrease in the number density and volume fraction of inclusions. Notably, the average inclusion size also decreases, with over 80% of inclusions remaining under 1 μm, which is optimal for promoting acicular ferrite nucleation. The study concludes that adjusting the CaO/SiO2 ratio can significantly influence the transfer of Mn and Si to the weld metal, altering the inclusion composition and ultimately enhancing the weld's microstructure and mechanical properties.