Effects of Casting Speed on Thin Gauge Foil Surface Quality of 8079 Aluminum Alloy Produced by Twin Roll Casting Method

Abstract

In twin roll casting method, casted strips exhibit centerline segregation due to solidification kinetics. Casting parameters have an essential impact on aluminum’s microstructural properties as segregations. Therefore, these parameters have unfavorable effects on strip and foil products. Moreover, in foil products, pinhole surface defects do exist and reveal themselves as undesirable quality problems. In the present study, 8079 aluminum alloys were produced by twin roll casting method at different casting speeds. Diversified homogenization annealing processes were applied in laboratories for indicating optimum temperature leading to microstructural alterations. In order to analyze the influence of casting speed on foil products, microstructural investigations were accomplished on as-cast specimens and homogenized samples with optical microscope and scanning electron microscope. EDS and XRD analysis were conducted to analyze intermetallic structure inside 8079 alloy. In addition, mechanical tests were carried out for indicating the required temper designation for foil product. Scanning electron microscope analysis was performed on the final product surfaces of thin gauge foil in order to characterize the pinhole surface defect. © 2019, The Indian Institute of Metals - IIM.