Factors Affecting the Formation of Gas Porosity in A356 Alloy Wheel by Gravity Die Casting

The majority of the defects occur in the in Aluminium alloy casting are due to mold parameters, filling and during solidification. Aluminium alloys form oxide layer on top of the molten metal in holding furnace immediately when it comes in contact with the atmosphere forming oxide on its surface. This oxide layer forms bifilms due to turbulence. This leads the gas to get entrapped in the molten metal causing gas porosity in the casting. The gas entrapped in the casting during filling causes gas porosities during solidification. The study focused on identifying & controlling the parameters affecting formation of gas entrapment while casting A356 alloy wheel using GDC results into formation of gas porosity. Effect of various parameters like, pouring temperature, degassing time and Volume in holding furnace on the formation of porosity was checked for wheel samples and Reduced Pressure Test (RPT) samples.