Effects of Mg contents on porosity formation in Al–Mg alloy DC slabs

The effect of Mg content on porosity in Al–Mg alloy DC slabs was investigated. In this investigation, we performed an experimental study of the amount of porosity on laboratory scale (250 mm by 400 mm cross-section) DC slabs of Al–2, 3, 4, 5and 6 mass% Mg. We clarified the relationship between porosity formation and Mg contents of the DC slab quantitatively by measuring porosity size, fractions, and number of porosity from the surface to the center of slab. The following conclusions were obtained, (1) As the Mg contents increase the initial hydrogen contents increase, and the hydrogen contents can be expressed in a quadratic of Mg contents (mass%) with good accuracy. (2) When the Mg content is less than 2 mass%, the porosity were very small and distributed uniformly from the surface to the center of the slab. (3) When the Mg content exceeds 3 mass%, the pore sizes and the fractions increase from the surface to the center of the slab. As the Mg content increases the porosity content and number increase.