In the present investigation, low superheat casting (LSC) was employed to produce A356 thixoforming feedstock with athixotropic microstructure. Optimization of the LSC process parameters was carried out to obtain suitable thixotropic feedstock for thixoforming process. The Taguchi’s optimization approach has been employed to examine the influence of the LSC process parameters, typically, pouring temperature and mould material on the micro-structural characteristics of A356 alloys, typically, the average size and shape factor of the primary α-Al grains. The level of significance of the parameters and optimum parameter combination were determined using analysis of variance (ANOVA) approach. Correlations for micro-structural characteristics as functions of LSC process parameters were 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 α-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 copper mould exhibited the best micro-structural characteristics suitable for thixoforming. |
