Abstract
The study of the metallurgical evolution of different chemical elements related to the manufacture of poured castings provides an useful tool in order to avoid the appearance of gas porosities. The formation of these defects into the metallic material has a critical influence on the technological properties of the obtained castings and affects to their functionality. This work analyses the most important types of gas porosities normally found in graphitic iron, aluminium and steel. In addition, the most apparent causes for these defects formation are discussed according to the physical and chemical processes which take place inside the melt.