Development of low temperature superplasticity in commercial 5083 Al-Mg alloys

A simple rolling-type thermomechanical treatment (TMT) is used to process the low-priced commercial 5083 Al-Mg alloys to exhibit low temperature superplasticity (LTSP) at around 250 °C, with an optimum tensile elongation to 400%. The TMT processes thin sheet contained subgrains measuring 0.5×0.5×0.2 μm. At temperatures lower than 300 °C, the grains grew limitedly and maintained LTSP, with failure by cavitation coalescence. The flow stress of the LTSP specimens dropped to nearly one half and the strain rate sensitivity increased from 0.15-0.2 of the as-received (AR) specimens to 0.3-0.4 of the LTSP ones. The effects from rolling temperature, rolling reduction ratio, and rolling direction on the LTSP characteristics were also examined.