Abstract:Microstructure and hardness of twin-roll casting (TRC) process and direct-chill casting (DC) for A8006 alloy with and without homogenization were investigated by means of scanning electron microscopy (SEM), X-ray diffraction analysis and Vickers hardness measurement. The results show that the eutectic phase of the homogenized TRC alloy becomes fine as the microstructure of the as-cast TRC alloy is refined. The short rodlike eutectic phase of the as-cast TRC alloy is dispersed homogeneously, which is similar to the morphology of eutectic phase of the homogenized DC alloy. After homogenization, elements Fe and Mn in DC and TRC alloys are diffused from eutectic phase to Al matrix, resulting in the decrease of microhardness. The formability of the as-cast TRC alloy is superior to that of the homogenized DC alloy. For TRC A8006 alloy, the homogenizing cycle can be removed from the subsequent processing.

Key words: A8006 alloy; twin-roll casting; homogenization; microstructure