Element Transfer Behaviors of Agglomerated CaF2-ZrO2 Fluxes in EH36-Shipbuilding Steel Subject to High-Heat Input Submerged Arc Welding

EH36-shipbuilding steel has been welded by CaF 2 -ZrO 2 fluxes with designed ZrO 2 additions. Possible chemical and electrochemical reactions have been postulated to analyze alloying element transfer behaviors. The decomposition of ZrO 2 during SAW has been validated by applying the gas–slag–metal equilibrium model and the O supply capacity of ZrO 2 has been quantified. For the entire compositional range, O content has been controlled within a well-maintained range from 220 to 400 ppm, and the transferred quantity of Zr content reaches to the maximum value of 120 ppm. It is further demonstrated that ZrO 2 addition incurs appreciable Si loss within the weld metal.