Date of Award
Master of Engineering Science
Mechanical and Materials Engineering
Dr. J. T. Wood
The solidification pattern for a material is strongly dependent on the process parameters, such as cooling rate, thermal gradient, solidification time, mold shape and dimensions, mold filling rate, superheat temperature etc. Thus, the obtained microstructural features have a direct functional relation with these initial variables. In this study, two commercial Mg alloys (AM60B and AZ91D) were studied under different solidification conditions to characterize 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 and correlated with the process variables recording during the casting process. It was determined that the process of mold filling and solidification are simultaneous in nature and they significantly affect the development of microstructure and its dependency on the process parameters. This significantly affects the obtained porosity values and their variation along the casting. These results clearly indicate that rate of filling, nature of flow o f liquid and shape o f the mold greatly affect the solidification process and thereby the microstructure. Any predictive solidification model, treating these factors singularly wouldn’t be appropriate to pre-determine the microstructure and properties of the casted component.
Basu, Indranil, "Effect of Process Variables on the Microstructural Features for As-Cast Magnesium Alloys" (2011). Digitized Theses. 3354.