Effect of Oxygen Injections on the Porosity of High Pressure Die Castings

This study aims to investigate the role of oxygen in optimizing the Pore-Free Die Casting (PFDC) process to enhance the quality of aluminum castings by minimizing porosity defects. The effects of oxygen levels on the integrity of high pressure die casting specimens was investigated by injecting oxygen at different durations (1 s, 3 s, and 5 s) through air jet valves installed at the mold cavity. The CT results indicate that increasing the oxygen injection time significantly reduces the porosity volume from 0.9 to 0.18%, with smaller defects in size as well. Notably, after applying the PFDC process, the elongation improved from 2.23 to 4.58%, suggesting that replacing atmosphere in the cavity space with oxygen plays a crucial role in enhancing the mechanical properties of the HPDC specimens. The improvement is believed to be caused by promoting oxidation reactions with the high concentration of oxygen, which leads to a decrease in gas entrapment during the casting process.