Fluoride emissions during continuous casting operations could cause health problems and equipment corrosion. For these reasons, nowadays free fluor mould fluxes are developed, using other oxides in order to substitute fluoride compounds. Although physical properties of the flux must be garantizied to prevent operation problems and product defects, it is relevant to analyse the effect of the new fluxes on the nozzle wear mechanisms. In this paper, the influence of B2O3 and Li2O on the wear of the nozzle materials is determined. A post mortem study on a nozzle used for steel billet casting that it was in contact with fluorides fluxes were carried out to identify the real wear mechanisms acting during operation. To determine and compare the effect of B2O3 and Li2O on the wear, static corrosion tests were developed on the same type of nozzle material. A similar corrosion mechanisms were identified in both cases: refractory melt infiltration and grain dissolution, but less penetration depth was observed for the flux containing B2O3 and Li2O. The results were correlated with some physical properties of the fluxes such as viscosity and surface tension.