Numerical modeling and experimental analysis of benchmark experiment of Sn-10 wt%Pb alloy under forced convection by electromagnetic stirring

Abstract

3D numerical simulation of solidification was carried out for a benchmark experiment on a binary Sn-Pb alloy with rigorous controlled thermal boundary conditions. The experiment consists of solidifying a parallelepiped ingot of Sn-10wt.%Pb composition. The main objective is to give both details of 3D numerical simulation and experimental analysis of the effect of forced convection driven by an alternative traveling magnetic field on the solidification process of Sn-10wt.%Pb alloy. The experiment was carried out under an average experimental temperature difference (DT) equal to 40 K and a cooling rate of (-0.03 K/s). This slow-cooling condition has been used in order to promote segregation formation. A periodically reversed electromagnetic stirring (EM) case with a modulation frequency equal to 0.125 Hz has been investigated in this both numerical and experimental studies. During the solidification process, the time evolution of the temperature field is recorded by more than 68 thermocouples and analyzed. This enables us to determine the temperature evolution over time owing to forced convection. The patterns of the of solute (lead) concentration distribution obtained by numerical results are compared to the experimental X-ray radiographies. A post-mortem analysis is performed allowing us to determine the grain’s form and size in the final macrostructure. Results illustrate clearly that the EM stirring modifies the macrostructure in terms of columnar-equiaxed transition (CET), namely the grain refinement and, on the other hand, it significantly affects the segregation pattern, especially the segregated channel morphology and distribution. Indeed, it shows that this periodicity in the reversal electromagnetic stirring reduces significantly the macrosegregation corresponding to the last liquid solidified, while remaining inactive for reducing the development of segregated channels.