On the Si content prediction for submerged arc welded metal via Calphad technique: a brief discussion

Abstract

The slag-metal and gas-slag-metal equilibrium models have been employed via the Calphad technique to predict Si content in submerged arc welded metal. The investigated fluxes possess a wide range of basicity indices at full coverage with acidic, neutral, and basic fluxes. It is revealed that the gas-slag-metal equilibrium model offers better prediction accuracy for Si content than the slag-metal equilibrium model since the flux O potential is underestimated by the slag-metal equilibrium model. Especially, the gas-slag-metal equilibrium model is capable of predicting the transfer direction of Si between flux and weld metal, as well as Si content in submerged arc welded metal even when no SiO2 is contained in the initial flux. Additionally, the kinetic factors that influence the transfer behavior of Si have been evaluated to interpret the deviation between measured Si content and the value predicted from the equilibrium model. At last, we have proposed the limitations of the equilibrium models, as well as the models to be further developed with respect to improving the prediction accuracy.