Main factors of pinhole formation in aluminum die castings

Pinholes are a casting defect that is easy to appear in aluminum alloy castings and have a certain impact on the quality of the castings. Hydrogen is the main cause of pinholes (some materials introduce that 80%-90% of the gas dissolved in molten aluminum Is hydrogen), and the main source of hydrogen is the decomposition of water vapor. Therefore, the reason for the generation of water vapor in the aluminum alloy smelting process is the main factor that directly affects the formation of pinholes.

Does porosity affect the performance of aluminum die castings?

The effect of pinholes on the properties of aluminum alloys is mainly manifested in reducing the density of the casting structure and the decrease of mechanical properties. For this reason, in the production practice of aluminum alloy castings, it is very important to strengthen the research on the influence of pore grades on mechanical properties, and to ensure the quality of aluminum die castings by controlling pinhole grades. Pinhole grade evaluation, low power inspection shall be carried out according to GB10851-89, and shall be carried out in case of dispute; X-ray photography shall be carried out according to GB11346-89 aluminum alloy casting pinhole grading standard, which uses two alloys commonly used in industrial production. The test results of ZL101 (Al-Si-Mg series) and ZL201 (Al-Cu-Mn series) and measuring бb and σ5 in the T4 state show that there is a linear correlation between the mechanical properties of the casting and the pinhole grade. As the hole grade increases, the mechanical properties gradually decrease; for each increase in the pinhole grade, the mechanical properties бb decrease by about 3%, and σ5 decreases by about 5%.