Structural Homogeneity of Direct-Chill Cast Ingots of Aluminum Alloy EN AW-5083

Abstract

Structural homogeneity of direct-chill (DC) cast ingots of aluminum alloy EN AW-5083 was investigated in terms of grain size and grain distribution using the Latin square experimental design. The ingot cross-sectional homogeneity, the grain sizes, and the mean grain number per unit area were determined at precise, statistically defined locations in the slice by means of a semiautomatic method for measuring mean lineal intercept lengths. Based on the analysis of the differences in the number and distribution of grains between the slices cut from the ingot front and those from its rear, a general assessment of the ingot structural homogeneity was made. Analysis of variance showed the highly significant differences, in grain number in specimens taken from the ingot front section to be related to slice height/ingot depth and in those taken from the ingot rear section to individual charges and slice height. The grand means of the mean number of grains per unit area for the ingot front and rear sections show relatively high values with respect to ingot size. The obtained correlation coefficient, which suggests a good agreement between the number and distribution of grains at the ingot front and those at its rear, is indicative of good structural homogeneity of the ingot in general.