A comprehensive understanding of melt quality is of paramount importance for the control and prediction of actual casting characteristics. Among many phenomenon that occur during the solidification of castings, there are four that control structure and consequently mechanical properties: chemical composition, liquid metal treatment, cooling rate and temperature gradient. The cooling rate and alloy composition are most important among them. This paper investigates the effect of the major alloying elements (silicon and copper) of AlSi-Cu alloys on the size of secondary dendrite arm spacing. It has been shown that both alloying elements have reasonable influence on the refinement of this solidification parameter
The quality of the squeeze castings is significantly affected by secondary dendrite arm spacing, which is influenced by squeeze cast input
parameters. The relationships of secondary dendrite arm spacing with the input parameters, namely time delay, pressure duration, squeeze
pressure, pouring and die temperatures are complex in nature. The present research work focuses on the development of input-output
relationships using fuzzy logic approach. In fuzzy logic approach, squeeze cast process variables are expressed as a function of input
parameters and secondary dendrite arm spacing is expressed as an output parameter. It is important to note that two fuzzy logic based
approaches have been developed for the said problem. The first approach deals with the manually constructed mamdani based fuzzy
system and the second approach deals with automatic evolution of the Takagi and Sugeno’s fuzzy system. It is important to note that the
performance of the developed models is tested for both linear and non-linear type membership functions. In addition the developed models
were compared with the ten test cases which are different from those of training data. The developed fuzzy systems eliminates the need of
a number of trials in selection of most influential squeeze cast process parameters. This will reduce time and cost of trial experimentations.
The results showed that, all the developed models can be effectively used for making prediction. Further, the present research work will
help foundrymen to select parameters in squeeze casting to obtain the desired quality casting without much of time and resource
consuming.
In this study, the effects of grain size refiner addition and various pre-heating mold temperatures on AlSi9 cast alloy microstructure and solidification have been evaluated. For different process conditions, thermal analysis was performed for all samples and cooling curves were established. Important parameters in liquidus and eutectic Si-phase regions have been calculated using the first derivative cooling curves. Secondary Dendrite Arm Spacing (SDAS) variation was also determined. Experimental results question the effectiveness of cooling curve parameters in providing the microstructure data as a function of refinement. The present work shows that the effect of grain refiner addition on the value of SDAS was higher when the solidification time was lower. It indicated that the solidification parameters such as nucleation temperatures of α-Al phase, undercooling temperature and total solidification time were affected by grain refinement. It has been found that the addition of grain refiner affect the eutectic phase formation time. However, it has no effect on the eutectic phase morphology.