Effect of Homogenization on Al-Fe-Si Centerline Segregation of Twin-Roll Cast Aluminum Alloy AA 8011

The effect of homogenization on centerline segregation has been studied in twin roll cast aluminum alloy AA 8011. It is observed that second phase particles generally form when the alloy contains high Fe and Si. During twin-roll casting process, beta phase of AlFeSi segregates at the centre of the strip in the thickness range of 10-15 mu m. Such phase has a needle shape morphology that inversely affects the formability. Phase transformation from beta-AlFeSi to alpha-AlFeSi is found to occur when homogenization is carried out at high temperature. During the phase transformation, the morphology of second phase particles also changes from needle to circular shape. Furthermore, it is also observed that the area fraction of second phase particles decreases with an increase in time and temperature. If homogenization temperature is increased, particle size growth is found to be dominant on the spread of intermetallic particles.