Deformation modeling of superplastic AA-5083

The superplastic deformation characteristics of a modified aluminum alloy w ere investigated at temperature range from 500 to 550 degrees C. The alloy chemical composition was 4.69% Mg, 1.56% Mn, 0.177% Cr, 0.03% Si, and 0.07% Fe by weight. Total tensile elongations as high as 750% were observed at l ower strain rates. A non-isothermal constitutive equation, that includes th e evolution of grain size, was established and implemented in a finite elem ent code. Numerical simulations of the uniaxial tension specimen were perfo rmed, and good agreement between the testing and the modeling results was o btained. A pressure control algorithm for the blow forming model was develo ped based on an averaging scheme that considered a subset of finite element s with the highest strain rate. A pressure history was generated from the f inite element simulations for a constant target strain rate of 1x10(-3) s(- 1). When these pressure histories were used in tray forming experiments, go od agreement was obtained between the forming and modeling results. (C) 199 8 Elsevier Science Ltd. All rights reserved.