In Quality management of Aluminium Alloy Casting, porosity is a major factor which is detrimental in terms of surface quality, corrosion resistance and mechanical properties.
Hydrogen, which easily dissolves in molten aluminium which causes gas porosity. Vacuum Pressure Test is the most widely used technique in aluminum foundries.
Vacuum pressure test is solidifying a sample of molten aluminium under reduced pressure (vacuum) up to 500mmHg. The reduced pressure enhances pore formation and pore expansion, giving out a visibly more porous sample than that solidified under atmospheric conditions. Porosity assessment is done in the following manner: