About the Formation of Macrosegregations During Continuous Casting of Sn-Bronze

Abstract

In continuous casting of bronze, macrosegregations cause weaknesses in the final product. Besides sedimentationand flotationofequiaxed grains,feeding flow,thermal and solutal buoyancy driven flow, and inlet flow are potential convection mechanisms which cause the formation of macrosegregations. Since macrosegregations are formed during solidificationprocesses where relative motion between melt and solidifying dendrites occurs, their formation is strongly dependent on the flow, especially in the mushy zone. To study and compare the impact of the different flow phenomena, a numerical investigation has been carried out. The presented study discusses the impact of different convection types like inlet flow,thermal andsolutalbuoyancyflow,and feedingflow ontheformationofmacrosegregationsforonehighlyand one low permeable mushy zone. It is shown that low mush permeabilityfavors positivemacrosegregations adjacent to the wall and strong negative segregations at the center line. In contrast, a higher permeability favors significant negative macrosegregations at the wall and at the center line and positive macrosegregations between wall and center line. It is demonstrated how the different flow phenomena contribute to this finding.