MICROSTRUCTURE EVOLUTION OF TWIN-ROLL CAST Al-Mg ALLOYS DURING DOWNSTREAM PROCESSING

摘要

Microstructure evaluation of twin-roll cast AlMg3 (AA5754) and AlMg4.5Mn0.4 (AA5182) alloys in the as-cast condition and during downstream processing was performed using light and scanning electron microscopy. Primary intermetallic phases were identified by means of wavelength-dispersive X-ray spectroscopy as Al_6(Fe,Mn), Al_(12)(Fe,Mn)_3Si and Mg_2Si. Moreover, very coarse particles containing Al and Mg, but also Ga, Zn and Cu were found in centerline segregation channels. At the final gauge of 1 mm, the twin-roll cast (TRC) materials exhibit a homogeneous grain structure and very fine dispersion of intermetallic particles. Final gauge tensile properties of TRC alloys are nearly the same as these of equivalent materials produced by direct chill casting and hot rolling technology.