MELT CLEANLINESS, HYDROGEN CONTENT AND TENSILE PROPERTIES OF A356

摘要

Degassing of aluminium melts is one of the most important stages in a casting operation. Main reason for this treatment is the removal of hydrogen from the melt, and thereby the ultimate goal is the achievement of a pore-free casting. However, it was shown that the interaction between the bifilms and the hydrogen plays a significant role on pore formation. Therefore, series of degassing experiments were carried out with the commercially available alloy A356. Two melts were prepared and one melt was upgassed gradually and the other was degassed gradually. Tensile samples were collected and bifilm index measurements were compared at each treatment sequences. Weibull analysis was used and it was found that the turbulence and vortex (increase in bifilm index) during rotary degassing caused an increase in the scatter irrespective of the hydrogen content.