In the present investigation, low superheat casting (LSC) was employed to
produce A356 thixoforming feedstock with athixotropic microstructure.
Optimization of the LSCprocess parameterswas carried out to obtain suitable
thixotropic feedstock for thixoforming process. The Taguchis optimization
approach has been employed to examine the influence of the LSC process
parameters, typically, pouring temperature and mould material on the
microstructural characteristics ofA356 alloys, typically, the average size and
shape factor of the primary á-Al grains. The level of significance of the
parameters and optimum parameter combination were determined using
analysis of variance (ANOVA) approach. Correlations for microstructural
characteristics as functions of LSC process parameterswere determined. The
results revealed that the mould material is the most influential parameter on
both the average grain size and shape factor of the primary á-Al grains. The
pouring temperature has lower effect on the aforementioned characteristics
than the mould material. There is no interaction between the mould material
and pouring temperature. The developed empirical model was successfully
used to predict the average grain size and shape factor of the A356 alloy
ingots produced using LSC. A356 ingot poured at a pouring temperature of
620 oC in the coppermould exhibited the bestmicrostructural characteristics
suitable for thixoforming. |
