Deformation modeling of superplastic AA-5083

The superplastic deformation characteristics of a modified aluminum alloy were 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 lower strain rates. A non-isothermal constitutive equation, that includes the evolution of grain size, was established and implemented in a finite element code. Numerical simulations of the uniaxial tension specimen were performed, and good agreement between the testing and the modeling results was obtained. A pressure control algorithm for the blow forming model was developed based on an averaging scheme that considered a subset of finite elements with the highest strain rate. A pressure history was generated from the finite element simulations for a constant target strain rate of 1x10(-3) s(-1). When these pressure histories were used in tray forming experiments, good agreement was obtained between the forming and modeling results. (C) 1998 Elsevier Science Ltd. All rights reserved.