Grain refining of aluminium foundry alloys using Al5Ti1B

GRAIN REFINING OF ALUMINIUM FOUNDRY ALLOYS USING AL5Ti1B(M.Sc. Thesis)Fatih BAYPINARGAZ UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYDecember 2005ABSTRACTAl-Si alloys are widely used in automobile, electrical, aircraft industries due totheir good casting characteristics and mechanical properties, low shrinkage,high corrosion resistance. Grain refinement of aluminum alloys is usuallyachieved by an addition of master alloys based on Al-Ti or Al-Ti-B, It is used toimprove mechanical strength, ductility, homogeneity, feeding duringsolidification. The grain size obtained during grain refinement depends onnumber of parameters such as type and level of grain refiner, pouringtemperature, mould temperature. In this thesis, the effects of these parameterson the mechanical properties of Al%7 Si foundry alloys were investigated.Grain refinement was achieved by adding Al5Ti1B master alloy. The pouringtemperatures were selected as 730, 750 and 770 ˚C. Two different level of 0,15and 0,2 Ti were used for grain refinement of molten aluminum. Aftersolidification, the half of specimens were applied T6 heat treatment. Significantimprovements in mechanical properties have been obtained with grain refiningand heat treatment. Experimental results show that optimum processparameters are the pouring temperature of 770 ºC, mould temperature 250 ºCand 0,2 % Ti content.Science Code : 710.3.011Key Words : Al5Ti1B, Al-Si Alloys, Grain Refinement, PouringTemperature and Mold TemperaturePage Number : 107Adviser : Doç. Dr. Ferhat GÜL