Study of Vertical Fold Formation on Al–Mg Alloys During Direct Chill Casting

The appearance of vertical foldsVertical folds (VF) is a known surfaceSurface defectDefects in direct chill (DC) aluminum castingAluminum casting of Al–Mg alloysMg alloys, which affects both productivityProductivity and quality in the scalper and downstream rolling process, respectively. In this study, a series of industrial DC castingDC Casting trials have been performed in terms of grain refinerGrain refiner additions and oxidation inhibitors with the objective to study their effect on VF formationFormation. The number, length, and width of the VF on the surfaceSurface of the produced ingots have been macroscopically recorded. In addition, the microstructureMicrostructure of corresponding as-cast samples has been examined by means of light optical microscopy (LOM) and scanning electron microscopy (SEM). Based on the results, a mechanism describing the contribution of oxidation and segregation phenomena on the formationFormation of vertical foldsVertical folds is presented. Finally, the efficiency of employed measures to constrain vertical foldsVertical folds generation has been evaluated.