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Grain Refinement of AA-356 by Adding AI-5TI-1B Grain Refiner and Inducing Ultrasonic Vibrations during Solidification

Sahadeva G N1 , A S Ravindran2, H R Vitala1, T Chandrashaker33,
1.Department of Mechanical Engineering, East Point College of Engineering & Technology, JnanaPrabha, Bidarahalli, Bangalore, Karnataka 560049, India
2.Department of Mechanical Engineering, Alpha College of Engineering, Kannur, Bangalore 560077, Karnataka, India
3.Velammal Institute of Technology, Panchetti, Thiruvallur (Dist), Tamil Nadu 601204, India

Abstract—Grain refinement plays vital role for improving the quality of AA-356 aluminium alloy castings. The aim of present investigation is to evaluate the grain refinement of AA-356 alloy by inducing ultrasonic vibrations through the die into the melt during solidification, which was treated at various frequencies and amplitudes by adding master alloy (Al-5Ti-1B) at different fractions. Experimental results shows that the columnar dendritic structure was changed into globular grain structure with reduced in grain size. These grains were obtained when melt was treated ultrasonically which leads to formation of equi-axed grains, degassing, increase in fluidity, refinement in phases, improvement in homogeneity, segregation control, uniform distribution of secondary phases and inclusions. It may imply that from the experiment the cavitations induces heterogeneous nucleation plays important role than dendrite fragmentation of globular grains. Due to cavitation phenomenon degassing of hydrogen from the melt during solidification takes place, due to this the formation small equi-axeed grain structure produced throughout the casting.

Index Terms—AA-356, Master alloy, Ultrasonic vibrations, Nucleation, Cavitations

Cite: Sahadeva G N, A S Ravindran, H R Vitala and T Chandrashaker, "Grain Refinement of AA-356 by Adding AI-5TI-1B Grain Refiner and Inducing Ultrasonic Vibrations during Solidification," International Journal of Mechanical Engineering and Robotics Research, Vol. 3, No. 3, pp. 723-730, July 2014.