Low Temperature Superplasticity and Intragranular Misorientation in Severely Rolled Sheets of Al-4.5Mg-0.7Mn based Alloys

摘要

Severely rolled sheets of Al-4.5%Mg-0.7%Mn based alloys have been prepared to achieve grain refinement leading to low temperature superplasticity. Rolling is one of straining technique which has a high possibility of industrial application. The alloys used were T1: base one adding 0.08%Zr and 0.05Ti for suppression of grain growth, F1: 0.80%Fe addition and F2: 1.92%Fe addition to increase nucleation sites of recrystallization. For comparison, M1: Al-4.2%Mg was also prepared. All of samples were 99.8% cold rolled to thin sheet 0.1mm thick. The maximum elongation of 150%, which was markedly large in consideration of specimen thickness of 0.1mm, was obtained at 533K and 1.4×10{sup}(-3)s{sup}(-1) for T1 sample while the elongations for F1 and F2 showed less than 100%. On the other hand, M1 exhibited larger elongation of 190% at 533K and 1.4×10{sup}(-3)s{sup}(-1). Further, difference in superplastic deformation of these alloys was investigated by using SEM/EBSP analysis of intragranular misorientation, which reflects strain or stored energy generated during deformation with dislocation glide, to discuss the deformation mechanism.