EFFECTS OF DIFFERENT ANNEALING PROCESSES ON MICROSTRUCTURAL FEATURES OF TWIN ROLL CAST 3003 AND 8006 ALUMINUM ALLOYS

摘要

Twin roll casting (TRC) can be used to produce aluminum sheets by direct solidification from the melt. Rapidly solidified (upto 800°C/sec) outer skin has a supersaturated microstructure with very fine grains. Application of prescribed processing routes of TRC cast material, like soft annealing to produce H1X tempers, to the TRC 3003 and 8006 alloys, results in the formation of very large surface grains after recrystallization which causes unwanted surface features called "orange peel" after bending or deep drawing processes. In the present work, annealing processes were carried out in a salt bath in order to see the effect of high heating rate on recrystallized grain size. In addition, the effect of high temperature rapid annealing process prior to the rolling operation on microstructural features were also demonstrated. Surfaces and through-thickness microstructures of the specimens were investigated under optical microscope and the mechanical properties have been discussed accordingly.