Effect of Process Variables on Microstructural Features during Solidification of AM60B Magnesium Alloy

Abstract

In this study, commercial AM60B magnesium alloy was studied under different solidification conditions to understand the influence of cooling rate, thermal gradient, growth velocity, Niyama criterion, solidification time and mold dimensions on microstructural features such as secondary and tertiary dendrite arm spacing, grain size, porosity, pore shape and size, local morphological and phase variations. Porosity, grain size and dendrite arm spacing were measured as functions of the process variables. It was realized that the process of mold filling and solidification are simultaneous in nature and they significantly affect the microstructure development trends and its dependency on the process parameters. A significant effect, of the above mentioned, was found on the obtained porosity values and their variation along the casting. The results clearly indicate that rate of filling, nature of flow of liquid and shape of the mold greatly affect the solidification process and thereby the microstructure.