Influence of mould vibration on microstructural behaviour and mechanical properties of LM25 aluminium alloy using gravity die casting process

Abstract

Abstract In present scenario, industry aims at situation where the number of internal defective products in casting must be minimized to zero (Zero defect approach) and to enhance its mechanical properties. Gravity die casting process is one of the best continuous casting process for non-ferrous alloys such as LM25 aluminium alloys. Vibration of mould during casting is one of the latest techniques employed to reduce the internal defects such as porosity, blow holes, shrinkage etc. In the present experimental work, melting of the LM 25 alloy was carried out using electrical resistance furnace. Vibration was induced using electro mechanical exciter to the graphite mould during pouring and solidification of the LM 25 aluminum alloy by varying the frequency intervals of 20\u202fHz, 25\u202fHz, 30\u202fHz, 35\u202fHz, 50\u202fHz, and 100\u202fHz at constant amplitude of vibration of 0.5\u202fmm was maintained. The casted sample without mould vibration was also prepared (0\u202fHz). Both the vibrated and un- vibrated samples were subjected to mechanical testing’s such as Hardness, Ultimate tensile strength, percentage elongation, yield strength and microstructural morphology such as grain refinement was analyzed using scanning electron microscope images. The experimental results and microstructures of both vibrated and un- vibrated samples were compared. It is observed that with increase in frequency of vibration the hardness increases linearly the UTS increased at higher frequencies whereas the ductility decreased with higher frequency, grain refinement showed significant improvement at an optimum frequency range of 30–35\u202fHz.