Comparison of the Flow Behavior of Globulitically and Dendritically Solidified Metallic Suspensions

Abstract:
The deformation behavior of globulitically and dendritically solidified metallic suspensions is studied at the example of Sn-15%Pb with a fraction solid of 30%. Creep tests with stresses less than 20 Pa serve to identify the deformation properties relevant for the solidification process of castings. It is investigated if thermo-mechanical defects like hot tearing or shape distortion which occur during solidification in conventional casting (dendritic structure) can also be expected for globulitic material as used in Thixoforming. Additionally the flow behavior at higher shear rates and the recovery of structural changes after shear is examined by shear rate jump and oscillation experiments respectively. This aspect is of importance for Rheocasting processes where depending on the cooling conditions globules as well as dendrites are present in the primary material.